89 results on '"Maezawa I"'
Search Results
2. Rett Syndrome Astrocytes Are Abnormal and Spread MeCP2 Deficiency through Gap Junctions
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Maezawa, I., primary, Swanberg, S., additional, Harvey, D., additional, LaSalle, J. M., additional, and Jin, L.-W., additional
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- 2009
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Catalog
3. Possible Involvement of Catalase in the Protective Effect of Interleukin-6 Against 6-Hydroxydopamine Toxicity in PC12 Cells
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Yamada, K., Umegaki, H., Maezawa, I., Iguchi, A., Kameyama, T., and Nabeshima, T.
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- 1997
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4. Isolation and structure of narbonolide, narbomycin aglycone, from Streptomyces venezuelae and its biological transformation into picromycin via narbomycin
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Hori, T., primary, Maezawa, I., additional, Nagahama, I., additional, and Suzuki, N., additional
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- 1971
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5. MeCP2 modulates gene expression pathways in astrocytes
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Yasui Dag H, Xu Huichun, Dunaway Keith W, LaSalle Janine M, Jin Lee-Way, and Maezawa Izumi
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MeCP2 ,Epigenetics ,Astrocytes ,Rett syndrome ,ChIP-seq ,Transcription ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Mutations in MECP2 encoding methyl-CpG-binding protein 2 (MeCP2) cause the X-linked neurodevelopmental disorder Rett syndrome. Rett syndrome patients exhibit neurological symptoms that include irregular breathing, impaired mobility, stereotypic hand movements, and loss of speech. MeCP2 protein epigenetically modulates gene expression through genome-wide binding to methylated CpG dinucleotides. While neurons have the highest level of MeCP2 expression, astrocytes and other cell types also express detectable levels of MeCP2. Recent studies suggest that astrocytes likely control the progression of Rett syndrome. Thus, the object of these studies was to identify gene targets that are affected by loss of MeCP2 binding in astrocytes. Methods To identify gene targets of MeCP2 in astrocytes, combined approaches of expression microarray and chromatin immunoprecipitation of MeCP2 followed by sequencing (ChIP-seq) were compared between wild-type and MeCP2-deficient astrocytes. MeCP2 gene targets were compared with genes in the top 10% of MeCP2 binding levels in gene windows either within 2 kb upstream of the transcription start site, or the ‘gene body’ that extended from transcription start to end site, or 2 kb downstream of the transcription end site. Results A total of 118 gene transcripts surpassed the highly significant threshold (P < 0.005, fold change > 1.2) in expression microarray analysis from triplicate cultures. The top 10% of genes with the highest levels of MeCP2 binding were identified in two independent ChIP-seq experiments. Together this integrated, genome-wide screen for MeCP2 target genes provided an overlapping list of 19 high-confidence MeCP2-responsive gene transcripts in astrocytes. Validation of candidate target gene transcripts by RT-PCR revealed that expression of Apoc2, Cdon, Csrp and Nrep were consistently responsive to MeCP2 deficiency in astrocytes. Conclusions The first MeCP2 ChIP-seq and gene expression microarray analysis in astrocytes reveals a set of potential MeCP2 target genes that may contribute to normal astrocyte signaling, cell division and neuronal support functions, the loss of which may contribute to the Rett syndrome phenotype. more...
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- 2013
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6. Neuropathologic features in the hippocampus and cerebellum of three older men with fragile X syndrome
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Greco Claudia M, Navarro Celestine S, Hunsaker Michael R, Maezawa Izumi, Shuler John F, Tassone Flora, Delany Mary, Au Jacky W, Berman Robert F, Jin Lee-Way, Schumann Cynthia, Hagerman Paul J, and Hagerman Randi J more...
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Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Fragile X syndrome (FXS) is the most common inherited form of intellectual disability, and is the most common single-gene disorder known to be associated with autism. Despite recent advances in functional neuroimaging and our understanding of the molecular pathogenesis, only limited neuropathologic information on FXS is available. Methods Neuropathologic examinations were performed on post-mortem brain tissue from three older men (aged 57, 64 and 78 years) who had received a clinical or genetic diagnosis of FXS. In each case, physical and cognitive features were typical of FXS, and one man was also diagnosed with autism. Guided by reports of clinical and neuroimaging abnormalities of the limbic system and cerebellum of individuals with FXS, the current analysis focused on neuropathologic features present in the hippocampus and the cerebellar vermis. Results Histologic and immunologic staining revealed abnormalities in both the hippocampus and cerebellar vermis. Focal thickening of hippocampal CA1 and irregularities in the appearance of the dentate gyrus were identified. All lobules of the cerebellar vermis and the lateral cortex of the posterior lobe of the cerebellum had decreased numbers of Purkinje cells, which were occasionally misplaced, and often lacked proper orientation. There were mild, albeit excessive, undulations of the internal granular cell layer, with patchy foliar white matter axonal and astrocytic abnormalities. Quantitative analysis documented panfoliar atrophy of both the anterior and posterior lobes of the vermis, with preferential atrophy of the posterior lobule (VI to VII) compared with age-matched normal controls. Conclusions Significant morphologic changes in the hippocampus and cerebellum in three adult men with FXS were identified. This pattern of pathologic features supports the idea that primary defects in neuronal migration, neurogenesis and aging may underlie the neuropathology reported in FXS. more...
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- 2011
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7. Apolipoprotein E isoform-dependent dendritic recovery of hippocampal neurons following activation of innate immunity
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Maezawa Izumi, Zaja-Milatovic Snjezana, Milatovic Dejan, Stephen Christina, Sokal Izabela, Maeda Nobuyo, Montine Thomas J, and Montine Kathleen S
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Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Innate immune activation, including a role for cluster of differentiation 14/toll-like receptor 4 co-receptors (CD14/TLR-4) co-receptors, has been implicated in paracrine damage to neurons in several neurodegenerative diseases that also display stratification of risk or clinical outcome with the common alleles of the apolipoprotein E gene (APOE): APOE2, APOE3, and APOE4. Previously, we have shown that specific stimulation of CD14/TLR-4 with lipopolysaccharide (LPS) leads to greatest innate immune response by primary microglial cultures from targeted replacement (TR) APOE4 mice and greatest p38MAPK-dependent paracrine damage to neurons in mixed primary cultures and hippocampal slice cultures derived from TR APOE4 mice. In contrast, TR APOE2 astrocytes had the highest NF-kappaB activity and no neurotoxicity. Here we tested the hypothesis that direct activation of CD14/TLR-4 in vivo would yield different amounts of paracrine damage to hippocampal sector CA1 pyramidal neurons in TR APOE mice. Methods We measured in vivo changes in dendrite length in hippocampal CA1 neurons using Golgi staining and determined hippocampal apoE levels by Western blot. Neurite outgrowth of cultured primary neurons in response to astrocyte conditioned medium was assessed by measuring neuron length and branch number. Results Our results showed that TR APOE4 mice had slightly but significantly shorter dendrites at 6 weeks of age. Following exposure to intracerebroventricular LPS, there was comparable loss of dendrite length at 24 hr among the three TR APOE mice. Recovery of dendrite length over the next 48 hr was greater in TR APOE2 than TR APOE3 mice, while TR APOE4 mice had failure of dendrite regeneration. Cell culture experiments indicated that the enhanced neurotrophic effect of TR APOE2 was LDL related protein-dependent. Conclusion The data indicate that the environment within TR APOE2 mouse hippocampus was most supportive of dendrite regeneration while that within TR APOE4 hippocampus failed to support dendrite regeneration in this model of reversible paracrine damage to neurons from innate immune activation, and suggest an explanation for the stratification of clinical outcome with APOE seen in several degenerative diseases or brain that are associated with activated innate immune response. more...
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- 2006
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8. Apolipoprotein E-specific innate immune response in astrocytes from targeted replacement mice
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Montine Thomas J, Maeda Nobuyo, Maezawa Izumi, and Montine Kathleen S
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Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Inheritance of the three different alleles of the human apolipoprotein (apo) E gene (APOE) are associated with varying risk or clinical outcome from a variety of neurologic diseases. ApoE isoform-specific modulation of several pathogenic processes, in addition to amyloid β metabolism in Alzheimer's disease, have been proposed: one of these is innate immune response by glia. Previously we have shown that primary microglia cultures from targeted replacement (TR) APOE mice have apoE isoform-dependent innate immune activation and paracrine damage to neurons that is greatest with TR by the ε4 allele (TR APOE4) and that derives from p38 mitogen-activated protein kinase (p38MAPK) activity. Methods Primary cultures of TR APOE2, TR APOE3 and TR APOE4 astrocytes were stimulated with lipopolysaccharide (LPS). ApoE secretion, cytokine production, and nuclear factor-kappa B (NF-κB) subunit activity were measured and compared. Results Here we showed that activation of primary astrocytes from TR APOE mice with LPS led to TR APOE-dependent differences in cytokine secretion that were greatest in TR APOE2 and that were associated with differences in NF-κB subunit activity. Conclusion Our results suggest that LPS activation of innate immune response in TR APOE glia results in opposing outcomes from microglia and astrocytes as a result of TR APOE-dependent activation of p38MAPK or NF-κB signaling in these two cell types. more...
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- 2006
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9. Isolation and structure of narbonolide, narbomycin aglycone, from Streptomyces venezuelae and its biological transformation into picromycin via narbomycin.
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Hori, T., Maezawa, I., Nagahama, I., and Suzuki, N.
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- 1971
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10. Unique N-glycosylation signatures in Aβ oligomer-and lipopolysaccharide-activated human iPSC-derived microglia.
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Tang X, Schindler R, Lucente J, Oloumi A, Tena J, Harvey D, Lebrilla C, Zivkovic A, Jin LW, and Maezawa I
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Microglia are the immune cells in the central nervous system (CNS) and become pro-inflammatory/activated in Alzheimer's disease (AD). Cell surface glycosylation plays an important role in immune cells; however, the N-glycosylation and glycosphingolipid (GSL) signatures of activated microglia are poorly understood. Here, we study comprehensive combined transcriptomic and glycomic profiles using human induced pluripotent stem cells-derived microglia (hiMG). Distinct changes in N-glycosylation patterns in amyloid-β oligomer (AβO) and LPS-treated hiMG were observed. In AβO-treated cells, the relative abundance of bisecting N-acetylglucosamine (GlcNAc) N-glycans decreased, corresponding with a downregulation of MGAT3. The sialylation of N-glycans increased in response to AβO, accompanied by an upregulation of genes involved in N-glycan sialylation (ST3GAL4 and 6). Unlike AβO-induced hiMG, LPS-induced hiMG exhibited a decreased abundance of complex-type N-glycans, aligned with downregulation of mannosidase genes (MAN1A1, MAN2A2, and MAN1C1) and upregulation of ER degradation related-mannosidases (EDEM1-3). Fucosylation increased in LPS-induced hiMG, aligned with upregulated fucosyltransferase 4 (FUT4) and downregulated alpha-L-fucosidase 1 (FUCA1) gene expression, while sialofucosylation decreased, aligned with upregulated neuraminidase 4 (NEU4). Inhibition of sialyation and fucosylation in AβO- and LPS-induced hiMG alleviated pro-inflammatory responses. However, the GSL profile did not exhibit significant changes in response to AβO or LPS activation. AβO- and LPS- specific glycosylation changes could contribute to impaired microglia function, highlighting glycosylation pathways as potential therapeutic targets for AD., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. Additional Declarations: No competing interests reported. more...
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- 2024
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11. Nitroxyl Hybrids with Curcumin and Stilbene Scaffolds Display Potent Antioxidant Activity, Remodel the Amyloid Beta Oligomer, and Reverse Amyloid Beta-Induced Cytotoxicity.
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Budamagunta MS, Mori H, Silk J, Slez RR, Bognár B, Mendiola UR, Kálai T, Maezawa I, and Voss JC
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The disorder and heterogeneity of low-molecular-weight amyloid-beta oligomers (AβOs) underlie their participation in multiple modes of cellular dysfunction associated with the etiology of Alzheimer's disease (AD). The lack of specified conformational states in these species complicates efforts to select or design small molecules to targeting discrete pathogenic states. Furthermore, targeting AβOs alone may be therapeutically insufficient, as AD progresses as a multifactorial, self-amplifying cascade. To address these challenges, we have screened the activity of seven new candidates that serve as Paramagnetic Amyloid Ligand (PAL) candidates. PALs are bifunctional small molecules that both remodel the AβO structure and localize a potent antioxidant that mimics the activity of SOD within live cells. The candidates are built from either a stilbene or curcumin scaffold with nitroxyl moiety to serve as catalytic antioxidants. Measurements of PAL AβO binding and remolding along with assessments of bioactivity allow for the extraction of useful SAR information from screening data. One candidate (HO-4450; PMT-307), with a six-membered nitroxyl ring attached to a stilbene ring, displays the highest potency in protecting against cell-derived Aβ. A preliminary low-dose evaluation in AD model mice provides evidence of modest treatment effects by HO-4450. The results for the curcumin PALs demonstrate that the retention of the native curcumin phenolic groups is advantageous to the design of the hybrid PAL candidates. Finally, the PAL remodeling of AβO secondary structures shows a reasonable correlation between a candidate's bioactivity and its ability to reduce the fraction of antiparallel β-strand. more...
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- 2024
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12. Effects of Sex and Western Diet on Spatial Lipidomic Profiles for the Hippocampus, Cortex, and Corpus Callosum in Mice Using MALDI MSI.
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Shafer CC, Di Lucente J, Mendiola UR, Maezawa I, Jin LW, and Neumann EK
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- Animals, Female, Male, Mice, Mice, Inbred C57BL, Sex Factors, Lipids analysis, Corpus Callosum metabolism, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization methods, Diet, Western, Hippocampus metabolism, Hippocampus chemistry, Lipidomics methods, Cerebral Cortex metabolism, Cerebral Cortex chemistry
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Diet is inextricably linked to human health and biological functionality. Reduced cognitive function among other health issues has been correlated with a western diet (WD) in mouse models, indicating that increases in neurodegeneration could be fueled in part by a poor diet. In this study, we use matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) to spatially map the lipidomic profiles of male and female mice that were fed a high-fat, high-sucrose WD for a period of 7 weeks. Our findings concluded that the cortex and corpus callosum showed significant lipid variation by WD in female mice, while there was little to no variation in the hippocampus, regardless of sex. On the other hand, lipid profiles were significantly affected by sex in all regions. Overall, 83 lipids were putatively identified in the mouse brain; among them, HexCer(40:1;O3) and PE(34:0) were found to have the largest statistical difference based on diet for female mice in the cortex and corpus callosum, respectively. Additional lipid changes are noted and can serve as a metric for understanding the brain's metabolomic response to changes in diet, particularly as it relates to disease. more...
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- 2024
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13. The impact of mild episodic ketosis on microglia and hippocampal long-term depression in 5xFAD mice.
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Di Lucente J, Ramsey JJ, Jin LW, and Maezawa I
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Ketotherapeutics is a potential metabolic intervention for mitigating dementias; however, its mechanisms and optimal methods of application are not well understood. Our previous in vitro study showed that β-hydroxybutyrate (BHB), a major ketone body, reverses pathological features of amyloid-β oligomer (AβO)-activated microglia. Here we tested the in vivo effects of BHB on microglia and synaptic plasticity in the 5xFAD Alzheimer's disease (AD) mouse model. A short 1-week regimen of daily intraperitoneal injection of BHB (250 mg/kg), which induced brief and mild daily episodic ketosis, was sufficient to mitigate pro-inflammatory microglia activation and reduce brain amyloid-β deposition by enhancing phagocytosis. Remarkably, it mitigated the deficits of hippocampal long-term depression but not long-term potentiation, and this effect was linked to suppression of NLRP3 inflammasome-generated IL-1β. As ketogenic diets are known for poor compliance, our study opens the possibility for alternative approaches such as short-term BHB injections or dietary ketone esters that are less restrictive, potentially safer, and easier for compliance., Competing Interests: The authors report no competing interests., (© 2024 The Author(s). FASEB BioAdvances published by Wiley Periodicals LLC on behalf of The Federation of American Societies for Experimental Biology.) more...
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- 2024
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14. Elevated lipopolysaccharide binding protein in Alzheimer's disease patients with APOE3/E3 but not APOE3/E4 genotype.
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Romo EZ, Hong BV, Patel RY, Agus JK, Harvey DJ, Maezawa I, Jin LW, Lebrilla CB, and Zivkovic AM
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Introduction: The role of lipopolysaccharide binding protein (LBP), an inflammation marker of bacterial translocation from the gastrointestinal tract, in Alzheimer's disease (AD) is not clearly understood., Methods: In this study the concentrations of LBP were measured in n = 79 individuals: 20 apolipoprotein E (APOE)3/E3 carriers with and 20 without AD dementia, and 19 APOE3/E4 carriers with and 20 without AD dementia. LBP was found to be enriched in the 1.21-1.25 g/mL density fraction of plasma, which has previously been shown to be enriched in intestinally derived high-density lipoproteins (HDL). LBP concentrations were measured by ELISA., Results: LBP was significantly increased within the 1.21-1.25 g/mL density fraction of plasma in APOE3/E3 AD patients compared to controls, but not APOE3/E4 patients. LBP was positively correlated with Clinical Dementia Rating (CDR) and exhibited an inverse relationship with Verbal Memory Score (VMS)., Discussion: These results underscore the potential contribution of gut permeability to bacterial toxins, measured as LBP, as an inflammatory mediator in the development of AD, particularly in individuals with the APOE3/E3 genotype, who are genetically at 4-12-fold lower risk of AD than individuals who express APOE4 ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Romo, Hong, Patel, Agus, Harvey, Maezawa, Jin, Lebrilla and Zivkovic.) more...
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- 2024
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15. Ketogenic diet and BHB rescue the fall of long-term potentiation in an Alzheimer's mouse model and stimulates synaptic plasticity pathway enzymes.
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Di Lucente J, Persico G, Zhou Z, Jin LW, Ramsey JJ, Rutkowsky JM, Montgomery CM, Tomilov A, Kim K, Giorgio M, Maezawa I, and Cortopassi GA
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- Humans, Mice, Animals, Aged, Long-Term Potentiation, Amyloid beta-Protein Precursor genetics, Amyloid beta-Protein Precursor metabolism, Mice, Transgenic, Mice, Inbred C57BL, Neuronal Plasticity, Alzheimer Disease metabolism, Diet, Ketogenic
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The Ketogenic Diet (KD) improves memory and longevity in aged C57BL/6 mice. We tested 7 months KD vs. control diet (CD) in the mouse Alzheimer's Disease (AD) model APP/PS1. KD significantly rescued Long-Term-Potentiation (LTP) to wild-type levels, not by changing Amyloid-β (Aβ) levels. KD's 'main actor' is thought to be Beta-Hydroxy-butyrate (BHB) whose levels rose significantly in KD vs. CD mice, and BHB itself significantly rescued LTP in APP/PS1 hippocampi. KD's 6 most significant pathways induced in brains by RNAseq all related to Synaptic Plasticity. KD induced significant increases in synaptic plasticity enzymes p-ERK and p-CREB in both sexes, and of brain-derived neurotrophic factor (BDNF) in APP/PS1 females. We suggest KD rescues LTP through BHB's enhancement of synaptic plasticity. LTP falls in Mild-Cognitive Impairment (MCI) of human AD. KD and BHB, because they are an approved diet and supplement respectively, may be most therapeutically and translationally relevant to the MCI phase of Alzheimer's Disease., (© 2024. The Author(s).) more...
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- 2024
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16. The ketone body β-hydroxybutyrate shifts microglial metabolism and suppresses amyloid-β oligomer-induced inflammation in human microglia.
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Jin LW, Di Lucente J, Ruiz Mendiola U, Suthprasertporn N, Tomilov A, Cortopassi G, Kim K, Ramsey JJ, and Maezawa I
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- Humans, Animals, Mice, 3-Hydroxybutyric Acid pharmacology, Amyloid beta-Peptides, Ketone Bodies, Inflammation, Microglia, Alzheimer Disease
- Abstract
Fatty acids are metabolized by β-oxidation within the "mitochondrial ketogenic pathway" (MKP) to generate β-hydroxybutyrate (BHB), a ketone body. BHB can be generated by most cells but largely by hepatocytes following exercise, fasting, or ketogenic diet consumption. BHB has been shown to modulate systemic and brain inflammation; however, its direct effects on microglia have been little studied. We investigated the impact of BHB on Aβ oligomer (AβO)-stimulated human iPS-derived microglia (hiMG), a model relevant to the pathogenesis of Alzheimer's disease (AD). HiMG responded to AβO with proinflammatory activation, which was mitigated by BHB at physiological concentrations of 0.1-2 mM. AβO stimulated glycolytic transcripts, suppressed genes in the β-oxidation pathway, and induced over-expression of AD-relevant p46Shc, an endogenous inhibitor of thiolase, actions that are expected to suppress MKP. AβO also triggered mitochondrial Ca
2+ increase, mitochondrial reactive oxygen species production, and activation of the mitochondrial permeability transition pore. BHB potently ameliorated all the above mitochondrial changes and rectified the MKP, resulting in reduced inflammasome activation and recovery of the phagocytotic function impaired by AβO. These results indicate that microglia MKP can be induced to modulate microglia immunometabolism, and that BHB can remedy "keto-deficiency" resulting from MKP suppression and shift microglia away from proinflammatory mitochondrial metabolism. These effects of BHB may contribute to the beneficial effects of ketogenic diet intervention in aged mice and in human subjects with mild AD., (© 2023 Federation of American Societies for Experimental Biology.) more...- Published
- 2023
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17. Cholesterol, Amyloid Beta, Fructose, and LPS Influence ROS and ATP Concentrations and the Phagocytic Capacity of HMC3 Human Microglia Cell Line.
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Muñoz Herrera OM, Hong BV, Ruiz Mendiola U, Maezawa I, Jin LW, Lebrilla CB, Harvey DJ, and Zivkovic AM
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- Humans, Adenosine Triphosphate metabolism, Apolipoproteins E metabolism, Cell Line, Cholesterol pharmacology, Fructose pharmacology, Lipopolysaccharides pharmacology, Microglia metabolism, Reactive Oxygen Species metabolism, Alzheimer Disease metabolism, Amyloid beta-Peptides pharmacology
- Abstract
Research has found that genes specific to microglia are among the strongest risk factors for Alzheimer's disease (AD) and that microglia are critically involved in the etiology of AD. Thus, microglia are an important therapeutic target for novel approaches to the treatment of AD. High-throughput in vitro models to screen molecules for their effectiveness in reversing the pathogenic, pro-inflammatory microglia phenotype are needed. In this study, we used a multi-stimulant approach to test the usefulness of the human microglia cell 3 (HMC3) cell line, immortalized from a human fetal brain-derived primary microglia culture, in duplicating critical aspects of the dysfunctional microglia phenotype. HMC3 microglia were treated with cholesterol (Chol), amyloid beta oligomers (AβO), lipopolysaccharide (LPS), and fructose individually and in combination. HMC3 microglia demonstrated changes in morphology consistent with activation when treated with the combination of Chol + AβO + fructose + LPS. Multiple treatments increased the cellular content of Chol and cholesteryl esters (CE), but only the combination treatment of Chol + AβO + fructose + LPS increased mitochondrial Chol content. Microglia treated with combinations containing Chol + AβO had lower apolipoprotein E (ApoE) secretion, with the combination of Chol + AβO + fructose + LPS having the strongest effect. Combination treatment with Chol + AβO + fructose + LPS also induced APOE and TNF-α expression, reduced ATP production, increased reactive oxygen species (ROS) concentration, and reduced phagocytosis events. These findings suggest that HMC3 microglia treated with the combination of Chol + AβO + fructose + LPS may be a useful high-throughput screening model amenable to testing on 96-well plates to test potential therapeutics to improve microglial function in the context of AD. more...
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- 2023
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18. Transcriptomic and glycomic analyses highlight pathway-specific glycosylation alterations unique to Alzheimer's disease.
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Tang X, Tena J, Di Lucente J, Maezawa I, Harvey DJ, Jin LW, Lebrilla CB, and Zivkovic AM
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- Humans, Glycosylation, Transcriptome, Glycomics, Glycosyltransferases genetics, Glycosyltransferases metabolism, Polysaccharides metabolism, Mannosyltransferases genetics, Alzheimer Disease genetics, Alzheimer Disease metabolism, MicroRNAs genetics, MicroRNAs metabolism
- Abstract
Glycosylation has been found to be altered in the brains of individuals with Alzheimer's disease (AD). However, it is unknown which specific glycosylation-related pathways are altered in AD dementia. Using publicly available RNA-seq datasets covering seven brain regions and including 1724 samples, we identified glycosylation-related genes ubiquitously changed in individuals with AD. Several differentially expressed glycosyltransferases found by RNA-seq were confirmed by qPCR in a different set of human medial temporal cortex (MTC) samples (n = 20 AD vs. 20 controls). N-glycan-related changes predicted by expression changes in these glycosyltransferases were confirmed by mass spectrometry (MS)-based N-glycan analysis in the MTC (n = 9 AD vs. 6 controls). About 80% of glycosylation-related genes were differentially expressed in at least one brain region of AD participants (adjusted p-values < 0.05). Upregulation of MGAT1 and B4GALT1 involved in complex N-linked glycan formation and galactosylation, respectively, were reflected by increased concentrations of corresponding N-glycans. Isozyme-specific changes were observed in expression of the polypeptide N-acetylgalactosaminyltransferase (GALNT) family and the alpha-N-acetylgalactosaminide alpha-2,6-sialyltransferase (ST6GALNAC) family of enzymes. Several glycolipid-specific genes (UGT8, PIGM) were upregulated. The critical transcription factors regulating the expression of N-glycosylation and elongation genes were predicted and found to include STAT1 and HSF5. The miRNA predicted to be involved in regulating N-glycosylation and elongation glycosyltransferases were has-miR-1-3p and has-miR-16-5p, respectively. Our findings provide an overview of glycosylation pathways affected by AD and potential regulators of glycosyltransferase expression that deserve further validation and suggest that glycosylation changes occurring in the brains of AD dementia individuals are highly pathway-specific and unique to AD., (© 2023. The Author(s).) more...
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- 2023
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19. The role of FUT8-catalyzed core fucosylation in Alzheimer's amyloid-β oligomer-induced activation of human microglia.
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Jin LW, di Lucente J, Ruiz Mendiola U, Tang X, Zivkovic AM, Lebrilla CB, and Maezawa I
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- Humans, Mice, Animals, Fucosyltransferases metabolism, Microglia metabolism, Amyloid beta-Peptides metabolism, Tumor Suppressor Protein p53, Cytokines metabolism, Catalysis, Alzheimer Disease metabolism, Induced Pluripotent Stem Cells metabolism
- Abstract
Fucosylation, especially core fucosylation of N-glycans catalyzed by α1-6 fucosyltransferase (fucosyltransferase 8 or FUT8), plays an important role in regulating the peripheral immune system and inflammation. However, its role in microglial activation is poorly understood. Here we used human induced pluripotent stem cells-derived microglia (hiMG) as a model to study the role of FUT8-catalyzed core fucosylation in amyloid-β oligomer (AβO)-induced microglial activation, in view of its significant relevance to the pathogenesis of Alzheimer's disease (AD). HiMG responded to AβO and lipopolysaccharides (LPS) with a pattern of pro-inflammatory activation as well as enhanced core fucosylation and FUT8 expression within 24 h. Furthermore, we found increased FUT8 expression in both human AD brains and microglia isolated from 5xFAD mice, a model of AD-like cerebral amyloidosis. Inhibition of fucosylation in AβO-stimulated hiMG reduced the induction of pro-inflammatory cytokines, suppressed the activation of p38MAPK, and rectified phagocytic deficits. Specific inhibition of FUT8 by siRNA-mediated knockdown also reduced AβO-induced pro-inflammatory cytokines. We further showed that p53 binds to the two consensus binding sites in the Fut8 promoter, and that p53 knockdown abolished FUT8 overexpression in AβO-activated hiMG. Taken together, our evidence supports that FUT8-catalyzed core fucosylation is a signaling pathway required for AβO-induced microglia activation and that FUT8 is a component of the p53 signaling cascade regulating microglial behavior. Because microglia are a key driver of AD pathogenesis, our results suggest that microglial FUT8 could be an anti-inflammatory therapeutic target for AD., (© 2023 Wiley Periodicals LLC.) more...
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- 2023
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20. Regio-Specific N-Glycome and N-Glycoproteome Map of the Elderly Human Brain With and Without Alzheimer's Disease.
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Tena J, Maezawa I, Barboza M, Wong M, Zhu C, Alvarez MR, Jin LW, Zivkovic AM, and Lebrilla CB
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- Humans, Aged, Glycosylation, Proteome metabolism, Polysaccharides metabolism, Brain metabolism, Alzheimer Disease metabolism
- Abstract
The proteins in the cell membrane of the brain are modified by glycans in highly interactive regions. The glycans and glycoproteins are involved in cell-cell interactions that are of fundamental importance to the brain. In this study, the comprehensive N-glycome and N-glycoproteome of the brain were determined in 11 functional brain regions, some of them known to be affected with the progression of Alzheimer's disease. N-glycans throughout the regions were generally highly branched and highly sialofucosylated. Regional variations were also found with regard to the glycan types including high mannose and complex-type structures. Glycoproteomic analysis identified the proteins that differed in glycosylation in the various regions. To obtain the broader representation of glycan compositions, four subjects with two in their 70s and two in their 90s representing two Alzheimer's disease subjects, one hippocampal sclerosis subject, and one subject with no cognitive impairment were analyzed. The four subjects were all glycomically mapped across 11 brain regions. Marked differences in the glycomic and glycoproteomic profiles were observed between the samples., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.) more...
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- 2022
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21. Plasma biomarkers predict cognitive trajectories in an ethnoracially and clinically diverse cohort: Mediation with hippocampal volume.
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Sapkota S, Erickson K, Harvey D, Tomaszewski-Farias SE, Olichney JM, Johnson DK, Dugger BN, Mungas DM, Fletcher E, Maillard P, Seshadri S, Satizabal CL, Kautz T, Parent D, Tracy RP, Maezawa I, Jin LW, and DeCarli C more...
- Abstract
Introduction: We examine whether the association between key plasma biomarkers (amyloid β [aβ] 42/40, total tau (t-tau), neurofilament light [NfL]) and cognitive trajectories (executive function [EF] and episodic memory [EM]) is mediated through neurodegeneration., Methods: All participants were recruited from the University of California, Davis-Alzheimer's Disease Research Center ( n = 473; baseline age range = 49-95 years, 60% women). We applied an accelerated longitudinal design to test latent growth models for EF and EM, and path and mediation analyses. Age was centered at 75 years, and all models were adjusted for sex, education, and ethnicity., Results: HV differentially mediated the association aβ 42/40 and NfL on EF and EM level and change. Hippocampal volume (HV) did not mediate the association between t-tau and cognitive performance., Discussion: Neurodegeneration as represented with HV selectively mediates the association between key non-invasive plasma biomarkers and cognitive trajectories in an ethnoracially and clinically diverse community-based sample., Competing Interests: All authors report no disclosures relevant to the manuscript. Author disclosures are available in the supporting information., (© 2022 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.) more...
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- 2022
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22. High-Density Lipoprotein Changes in Alzheimer's Disease Are APOE Genotype-Specific.
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Hong BV, Zheng J, Agus JK, Tang X, Lebrilla CB, Jin LW, Maezawa I, Erickson K, Harvey DJ, DeCarli CS, Mungas DM, Olichney JM, Farias ST, and Zivkovic AM
- Abstract
High-density lipoproteins (HDL) play a critical role in cholesterol homeostasis. Apolipoprotein E ( APOE) , particularly the E4 allele, is a significant risk factor for Alzheimer's disease but is also a key HDL-associated protein involved in lipid transport in both the periphery and central nervous systems. The objective was to determine the influence of the APOE genotype on HDL function and size in the context of Alzheimer's disease. HDL from 194 participants (non-demented controls, mild cognitive impairment, and Alzheimer's disease dementia) were isolated from the plasma. The HDL cholesterol efflux capacity (CEC), lecithin-cholesterol acyltransferase (LCAT) activity, and particle diameter were measured. Neuropsychological test scores, clinical dementia rating, and magnetic resonance imaging scores were used to determine if cognition is associated with HDL function and size. HDL CEC and LCAT activity were reduced in APOE3E4 carriers compared to APOE3E3 carriers, regardless of diagnosis. In APOE3E3 carriers, CEC and LCAT activity were lower in patients. In APOE3E4 patients, the average particle size was lower. HDL LCAT activity and particle size were positively correlated with the neuropsychological scores and negatively correlated with the clinical dementia rating. We provide evidence for the first time of APOE genotype-specific alterations in HDL particles in Alzheimer's disease and an association between HDL function, size, and cognitive function. more...
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- 2022
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23. Novel Stilbene-Nitroxyl Hybrid Compounds Display Discrete Modulation of Amyloid Beta Toxicity and Structure.
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Hilt S, Liu R, Maezawa I, Rojalin T, Aung HH, Budamagunta M, Slez R, Gong Q, Carney RP, and Voss JC
- Abstract
Several neurodegenerative diseases are driven by misfolded proteins that assemble into soluble aggregates. These "toxic oligomers" have been associated with a plethora of cellular dysfunction and dysregulation, however the structural features underlying their toxicity are poorly understood. A major impediment to answering this question relates to the heterogeneous nature of the oligomers, both in terms of structural disorder and oligomer size. This not only complicates elucidating the molecular etiology of these disorders, but also the druggability of these targets as well. We have synthesized a class of bifunctional stilbenes to modulate both the conformational toxicity within amyloid beta oligomers (AβO) and the oxidative stress elicited by AβO. Using a neuronal culture model, we demonstrate this bifunctional approach has the potential to counter the molecular pathogenesis of Alzheimer's disease in a powerful, synergistic manner. Examination of AβO structure by various biophysical tools shows that each stilbene candidate uniquely alters AβO conformation and toxicity, providing insight towards the future development of structural correctors for AβO. Correlations of AβO structural modulation and bioactivity displayed by each provides insights for future testing in vivo . The multi-target activity of these hybrid molecules represents a highly advantageous feature for disease modification in Alzheimer's, which displays a complex, multifactorial etiology. Importantly, these novel small molecules intervene with intraneuronal AβO, a necessary feature to counter the cycle of dysregulation, oxidative stress and inflammation triggered during the earliest stages of disease progression., Competing Interests: Author JV was employed by Paramag Biosciences Inc., which retains a license to commercialize the PAL compounds. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor MC declared a shared affiliation with the authors at the time of review., (Copyright © 2022 Hilt, Liu, Maezawa, Rojalin, Aung, Budamagunta, Slez, Gong, Carney and Voss.) more...
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- 2022
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24. Glycosylation alterations in serum of Alzheimer's disease patients show widespread changes in N -glycosylation of proteins related to immune function, inflammation, and lipoprotein metabolism.
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Tena J, Tang X, Zhou Q, Harvey D, Barajas-Mendoza M, Jin LW, Maezawa I, Zivkovic AM, and Lebrilla CB
- Abstract
Introduction: There is an increased need for the development of novel blood-based biomarkers for early detection, prevention, or intervention in Alzheimer's disease (AD). This study sought to determine whether serum glycopeptide analysis holds potential for identifying novel diagnostics and prognostics of AD., Methods: The study involved 195 participants, including 96 patients with an AD diagnosis and 99 controls with no cognitive deficit. Utilizing a validated analytical mass spectrometry method, we monitored the site-specific glycosylation of 52 serum glycoproteins., Results: Partial least-squares discriminant analysis revealed that changes in overall sialylation and fucosylation of serum glycoproteins may be indicators of an AD disease state. Loss of fucosylation of immunoglobulin G1 (IgG1) and IgG2 was indicative of AD diagnosis. Individual glycopeptide analysis found separation between the AD patients and controls on complement proteins and apolipoprotein B., Discussion: The results of this study suggest that serum glycoprofiling may be a promising approach for biomarker discovery., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.) more...
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- 2022
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25. 1700 nm optical coherence microscopy enables minimally invasive, label-free, in vivo optical biopsy deep in the mouse brain.
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Zhu J, Freitas HR, Maezawa I, Jin LW, and Srinivasan VJ
- Abstract
In vivo, minimally invasive microscopy in deep cortical and sub-cortical regions of the mouse brain has been challenging. To address this challenge, we present an in vivo high numerical aperture optical coherence microscopy (OCM) approach that fully utilizes the water absorption window around 1700 nm, where ballistic attenuation in the brain is minimized. Key issues, including detector noise, excess light source noise, chromatic dispersion, and the resolution-speckle tradeoff, are analyzed and optimized. Imaging through a thinned-skull preparation that preserves intracranial space, we present volumetric imaging of cytoarchitecture and myeloarchitecture across the entire depth of the mouse neocortex, and some sub-cortical regions. In an Alzheimer's disease model, we report that findings in superficial and deep cortical layers diverge, highlighting the importance of deep optical biopsy. Compared to other microscopic techniques, our 1700 nm OCM approach achieves a unique combination of intrinsic contrast, minimal invasiveness, and high resolution for deep brain imaging., (© 2021. The Author(s).) more...
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- 2021
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26. Dysregulated bile acid receptor-mediated signaling and IL-17A induction are implicated in diet-associated hepatic health and cognitive function.
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Jena PK, Sheng L, Nguyen M, Di Lucente J, Hu Y, Li Y, Maezawa I, Jin LW, and Wan YY
- Abstract
Background: Chronic consumption of high sugar and high fat diet associated with liver inflammation and cognitive decline. This paper tests a hypothesis that the development and resolution of diet-induced nonalcoholic fatty liver disease (NAFLD) has an impact on neuroplasticity and cognition., Methods: C57BL/6 wild-type mice were fed with either a healthy control diet (CD) or a fructose, palmitate, and cholesterol (FPC)-enriched diet since weaning. When mice were 3-months old, FPC diet-fed mice were randomly assigned to receive either FPC-enriched diet with or without 6% inulin supplementation. At 8 months of age, all three groups of mice were euthanized followed by analysis of inflammatory signaling in the liver and brain, gut microbiota, and cecal metabolites., Results: Our data showed that FPC diet intake induced hepatic steatosis and inflammation in the liver and brain along with elevated RORγ and IL-17A signaling. Accompanied by microglia activation and reduced hippocampal long-term potentiation, FPC diet intake also reduced postsynaptic density-95 and brain derived neurotrophic factor, whereas inulin supplementation prevented diet-reduced neuroplasticity and the development of NAFLD. In the gut, FPC diet increased Coriobacteriaceae and Erysipelotrichaceae, which are implicated in cholesterol metabolism, and the genus Allobaculum, and inulin supplementation reduced them. Furthermore, FPC diet reduced FXR and TGR5 signaling, and inulin supplementation reversed these changes. Untargeted cecal metabolomics profiling uncovered 273 metabolites, and 104 had significant changes due to FPC diet intake or inulin supplementation. Among the top 10 most affected metabolites, FPC-fed mice had marked increase of zymosterol, a cholesterol biosynthesis metabolite, and reduced 2,8-dihydroxyquinoline, which has known benefits in reducing glucose intolerance; these changes were reversible by inulin supplementation. Additionally, the abundance of Barnesiella, Coprobacter, Clostridium XIVa, and Butyrivibrio were negatively correlated with FPC diet intake and the concentration of cecal zymosterol but positively associated with inulin supplementation, suggesting their benefits., Conclusion: Taken together, the presented data suggest that diet alters the gut microbiota and their metabolites, including bile acids. This will subsequently affect IL-17A signaling, resulting in systemic impacts on both hepatic metabolism and cognitive function. more...
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- 2020
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27. Biophysical basis for Kv1.3 regulation of membrane potential changes induced by P2X4-mediated calcium entry in microglia.
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Nguyen HM, di Lucente J, Chen YJ, Cui Y, Ibrahim RH, Pennington MW, Jin LW, Maezawa I, and Wulff H
- Subjects
- Adenosine Triphosphate, Alzheimer Disease, Animals, Calcium, Female, Inflammation, Microglia, Receptors, Purinergic P2, Receptors, Purinergic P2X4, Membrane Potentials
- Abstract
Microglia-mediated inflammation exerts adverse effects in ischemic stroke and in neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the voltage-gated potassium channel Kv1.3 is required for microglia activation. Both genetic deletion and pharmacological inhibition of Kv1.3 are effective in reducing microglia activation and the associated inflammatory responses, as well as in improving neurological outcomes in animal models of AD and ischemic stroke. Here we sought to elucidate the molecular mechanisms underlying the therapeutic effects of Kv1.3 inhibition, which remain incompletely understood. Using a combination of whole-cell voltage-clamp electrophysiology and quantitative PCR (qPCR), we first characterized a stimulus-dependent differential expression pattern for Kv1.3 and P2X4, a major ATP-gated cationic channel, both in vitro and in vivo. We then demonstrated by whole-cell current-clamp experiments that Kv1.3 channels contribute not only to setting the resting membrane potential but also play an important role in counteracting excessive membrane potential changes evoked by depolarizing current injections. Similarly, the presence of Kv1.3 channels renders microglia more resistant to depolarization produced by ATP-mediated P2X4 receptor activation. Inhibiting Kv1.3 channels with ShK-223 completely nullified the ability of Kv1.3 to normalize membrane potential changes, resulting in excessive depolarization and reduced calcium transients through P2X4 receptors. Our report thus links Kv1.3 function to P2X4 receptor-mediated signaling as one of the underlying mechanisms by which Kv1.3 blockade reduces microglia-mediated inflammation. While we could confirm previously reported differences between males and females in microglial P2X4 expression, microglial Kv1.3 expression exhibited no gender differences in vitro or in vivo. MAIN POINTS: The voltage-gated K
+ channel Kv1.3 regulates microglial membrane potential. Inhibition of Kv1.3 depolarizes microglia and reduces calcium entry mediated by P2X4 receptors by dissipating the electrochemical driving force for calcium., (© 2020 The Authors. Glia published by Wiley Periodicals LLC.) more...- Published
- 2020
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28. Metabolic flux analysis of the neural cell glycocalyx reveals differential utilization of monosaccharides.
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Wong M, Xu G, Barboza M, Maezawa I, Jin LW, Zivkovic A, and Lebrilla CB
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- Humans, Glycocalyx metabolism, Monosaccharides metabolism, Neural Stem Cells metabolism, Pluripotent Stem Cells metabolism
- Abstract
Saccharides in our diet are major sources of carbon for the formation of biomass such as proteins, lipids, nucleic acids and glycans. Among the dietary monosaccharides, glucose occupies a central role in metabolism, but human blood contains regulated levels of other monosaccharides as well. Their influence on metabolism and how they are utilized have not been explored thoroughly. Applying metabolic flux analysis on glycan synthesis can reveal the pathways that supply glycosylation precursors and provide a snapshot of the metabolic state of the cell. In this study, we traced the incorporation of six 13C uniformly labeled monosaccharides in the N-glycans, O-glycans and glycosphingolipids of both pluripotent and neural NTERA-2 cells. We gathered detailed isotopologue data for hundreds of glycoconjugates using mass spectrometry methods. The contributions of de novo synthesis and direct incorporation pathways for glucose, mannose, fructose, galactose, N-acetylglucosamine and fucose were determined based on their isotope incorporation. Co-feeding studies revealed that fructose incorporation is drastically decreased by the presence of glucose, while mannose and galactose were much less affected. Furthermore, increased sialylation slowed down the turnover of glycans, but fucosylation attenuated this effect. Our results demonstrated that exogenous monosaccharide utilization can vary markedly depending on the cell differentiation state and monosaccharide availability, and that the incorporation of carbons can also differ among different glycan structures. We contend that the analysis of metabolic isotope labeling of glycans can yield new insights about cell metabolism., (© The Author(s) 2020. Published by Oxford University Press.) more...
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- 2020
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29. Intellectual and Developmental Disabilities Research Centers: A Multidisciplinary Approach to Understand the Pathogenesis of Methyl-CpG Binding Protein 2-related Disorders.
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Fagiolini M, Patrizi A, LeBlanc J, Jin LW, Maezawa I, Sinnett S, Gray SJ, Molholm S, Foxe JJ, Johnston MV, Naidu S, Blue M, Hossain A, Kadam S, Zhao X, Chang Q, Zhou Z, and Zoghbi H
- Subjects
- Carrier Proteins, Child, Developmental Disabilities, Humans, Mutation, Reproducibility of Results, Methyl-CpG-Binding Protein 2 genetics, Methyl-CpG-Binding Protein 2 metabolism, Rett Syndrome genetics
- Abstract
Disruptions in the gene encoding methyl-CpG binding protein 2 (MECP2) underlie complex neurodevelopmental disorders including Rett Syndrome (RTT), MECP2 duplication disorder, intellectual disabilities, and autism. Significant progress has been made on the molecular and cellular basis of MECP2-related disorders providing a new framework for understanding how altered epigenetic landscape can derail the formation and refinement of neuronal circuits in early postnatal life and proper neurological function. This review will summarize selected major findings from the past years and particularly highlight the integrated and multidisciplinary work done at eight NIH-funded Intellectual and Developmental Disabilities Research Centers (IDDRC) across the US. Finally, we will outline a path forward with identification of reliable biomarkers and outcome measures, longitudinal preclinical and clinical studies, reproducibility of results across centers as a synergistic effort to decode and treat the pathogenesis of the complex MeCP2 disorders., (Copyright © 2020. Published by Elsevier Ltd.) more...
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- 2020
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30. Corrigendum to "Modulation of mitochondrial complex I activity averts cognitive decline in multiple animal models of familial Alzheimer's disease" [EBioMedicine 2 (2015) 294-305].
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Zhang L, Zhang S, Maezawa I, Trushin S, Minhas P, Pinto M, Jin LW, Prasain K, Nguyen TDT, Yamazaki Y, Kanekiyo T, Bu G, Gateno B, Chang KO, Nath KA, Nemutlu E, Dzeja P, Pang YP, Hua DH, and Trushina E more...
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- 2019
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31. Repurposing the KCa3.1 inhibitor senicapoc for Alzheimer's disease.
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Jin LW, Lucente JD, Nguyen HM, Singh V, Singh L, Chavez M, Bushong T, Wulff H, and Maezawa I
- Subjects
- Amyloid beta-Peptides metabolism, Animals, Brain drug effects, Brain metabolism, Drug Repositioning methods, Humans, Mice, Transgenic, Microglia drug effects, Acetamides pharmacology, Alzheimer Disease drug therapy, Amyloid beta-Peptides pharmacology, Intermediate-Conductance Calcium-Activated Potassium Channels antagonists & inhibitors, Trityl Compounds pharmacology
- Abstract
Objective: Microglia play a pivotal role in the initiation and progression of Alzheimer's disease (AD). We here tested the therapeutic hypothesis that the Ca
2+ -activated potassium channel KCa3.1 constitutes a potential target for treating AD by reducing neuroinflammation., Methods: To determine if KCa3.1 is relevant to AD, we tested if treating cultured microglia or hippocampal slices with A β oligomer (A β O) activated KCa3.1 in microglia, and if microglial KCa3.1 was upregulated in 5xFAD mice and in human AD brains. The expression/activity of KCa3.1 was examined by qPCR, Western blotting, immunohistochemistry, and whole-cell patch-clamp. To investigate the role of KCa3.1 in AD pathology, we resynthesized senicapoc, a clinically tested KCa3.1 blocker, and determined its pharmacokinetic properties and its effect on microglial activation, A β deposition and hippocampal long-term potentiation (hLTP) in 5xFAD mice., Results: We found markedly enhanced microglial KCa3.1 expression/activity in brains of both 5xFAD mice and AD patients. In hippocampal slices, microglial KCa3.1 expression/activity was increased by A β O treatment, and its inhibition diminished the proinflammatory and hLTP-impairing activities of A β O. Senicapoc exhibited excellent brain penetrance and oral availability, and in 5xFAD mice, reduced neuroinflammation, decreased cerebral amyloid load, and enhanced hippocampal neuronal plasticity., Interpretation: Our results prompt us to propose repurposing senicapoc for AD clinical trials, as senicapoc has excellent pharmacological properties and was safe and well-tolerated in a prior phase-3 clinical trial for sickle cell anemia. Such repurposing has the potential to expedite the urgently needed new drug discovery for AD., Competing Interests: The authors declare no conflicts of interest. more...- Published
- 2019
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32. The voltage-gated potassium channel Kv1.3 is required for microglial pro-inflammatory activation in vivo.
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Di Lucente J, Nguyen HM, Wulff H, Jin LW, and Maezawa I
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- Animals, Brain drug effects, Brain metabolism, Calcium-Binding Proteins metabolism, Cytokines metabolism, Escherichia coli, Kv1.3 Potassium Channel antagonists & inhibitors, Kv1.3 Potassium Channel genetics, Lipopolysaccharides, Long-Term Potentiation immunology, Mice, Inbred C57BL, Mice, Knockout, Microfilament Proteins metabolism, Microglia drug effects, Potassium Channels, Inwardly Rectifying metabolism, Tissue Culture Techniques, Immunity, Innate drug effects, Inflammation metabolism, Kv1.3 Potassium Channel metabolism, Microglia metabolism
- Abstract
Microglia show a rich repertoire of activation patterns regulated by a complex ensemble of surface ion channels, receptors, and transporters. We and others have investigated whether microglia vary their K
+ channel expression as a means to achieve functional diversity. However, most of the prior studies were conducted using in vitro models such as BV2 cells, primary microglia, or brain slices in culture, which may not accurately reflect microglia physiology in adult individuals. Here we employed an in vivo mouse model of selective innate immune activation by intracerebroventricular injection of lipopolysaccharides (ICV-LPS) to determine the role of the voltage-gated Kv1.3 channel in LPS-induced M1-like microglial activation. Using microglia acutely isolated from adult brains, we detected Kv1.3 and Kir2.1 currents, and found that ICV-LPS increased the current density and RNA expression of Kv1.3 but did not affect those of Kir2.1. Genetic knockout of Kv1.3 abolished LPS-induced microglial activation exemplified by Iba-1 immunoreactivity and expression of pro-inflammatory mediators such as IL-1β, TNF-α, IL-6, and iNOS. Moreover, Kv1.3 knockout mitigated the LPS-induced impairment of hippocampal long-term potentiation (hLTP), suggesting that Kv1.3 activity regulates pro-inflammatory microglial neurotoxicity. Pharmacological intervention using PAP-1, a small molecule that selectively blocks homotetrameric Kv1.3 channels, achieved anti-inflammatory and hLTP-recovery effects similar to Kv1.3 knockout. We conclude that Kv1.3 is required for microglial M1-like pro-inflammatory activation in vivo. A significant implication of our in vivo data is that Kv1.3 blockers could be therapeutic candidates for neurological diseases where microglia-mediated neurotoxicity is implicated in the pathogenesis., (© 2018 Wiley Periodicals, Inc.) more...- Published
- 2018
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33. A Bifunctional Anti-Amyloid Blocks Oxidative Stress and the Accumulation of Intraneuronal Amyloid-Beta.
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Hilt S, Altman R, Kálai T, Maezawa I, Gong Q, Wachsmann-Hogiu S, Jin LW, and Voss JC
- Subjects
- Alzheimer Disease genetics, Alzheimer Disease metabolism, Alzheimer Disease pathology, Amyloid beta-Peptides chemistry, Amyloid beta-Peptides genetics, Amyloid beta-Peptides pharmacology, Amyloid beta-Protein Precursor chemistry, Amyloid beta-Protein Precursor genetics, Amyloid beta-Protein Precursor metabolism, Cell Line, Fluorenes chemistry, Fluorenes pharmacology, Gene Expression, Humans, Models, Molecular, Protein Aggregates drug effects, Protein Aggregation, Pathological metabolism, Protein Conformation, Protein Multimerization, Reactive Oxygen Species metabolism, Signal Transduction, Spin Labels, Amyloid beta-Peptides metabolism, Neurons drug effects, Neurons metabolism, Oxidative Stress drug effects
- Abstract
There is growing recognition regarding the role of intracellular amyloid beta (Aβ) in the Alzheimer's disease process, which has been linked with aberrant signaling and the disruption of protein degradation mechanisms. Most notably, intraneuronal Aβ likely underlies the oxidative stress and mitochondrial dysfunction that have been identified as key elements of disease progression. In this study, we employed fluorescence imaging to explore the ability of a bifunctional small molecule to reduce aggregates of intracellular Aβ and attenuate oxidative stress. Structurally, this small molecule is comprised of a nitroxide spin label linked to an amyloidophilic fluorene and is known as spin-labeled fluorene (SLF). The effect of the SLF on intracellular Aβ accumulation and oxidative stress was measured in MC65 cells, a human neuronal cell line with inducible expression of the amyloid precursor protein and in the N2a neuronal cell line treated with exogenous Aβ. Super-resolution microscopy imaging showed SLF decreases the accumulation of intracellular Aβ. Confocal microscopy imaging of MC65 cells treated with a reactive oxygen species (ROS)-sensitive dye demonstrated SLF significantly reduces the intracellular Aβ-induced ROS signal. In order to determine the contributions of the separate SLF moieties to these protective activities, experiments were also carried out on cells with nitroxides lacking the Aβ targeting domain or fluorene derivatives lacking the nitroxide functionality. The findings support a synergistic effect of SLF in counteracting both the conformational toxicity of both endogenous and exogenous Aβ, its promotion of ROS, and Aβ metabolism. Furthermore, these studies demonstrate an intimate link between ROS production and Aβ oligomer formation. more...
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- 2018
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34. Dysregulated bile acid synthesis and dysbiosis are implicated in Western diet-induced systemic inflammation, microglial activation, and reduced neuroplasticity.
- Author
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Jena PK, Sheng L, Di Lucente J, Jin LW, Maezawa I, and Wan YY
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- Animals, Dysbiosis chemically induced, Dysbiosis pathology, Hippocampus pathology, Inflammation chemically induced, Inflammation metabolism, Inflammation pathology, MAP Kinase Signaling System, Male, Mice, Microglia pathology, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Receptors, Cytoplasmic and Nuclear metabolism, Tretinoin metabolism, Bile Acids and Salts biosynthesis, Diet, Western adverse effects, Dysbiosis metabolism, Hippocampus metabolism, Microglia metabolism, Neuronal Plasticity
- Abstract
The goal of this study was to identify the intrinsic links that explain the effect of a Western diet (WD) on cognitive dysfunction. Specific pathogen-free, wild-type mice were fed either a control diet (CD) or a high-fat, high-sucrose WD after weaning and were euthanized at 10 mo of age to study the pathways that affect cognitive health. The results showed that long-term WD intake reduced hippocampal synaptic plasticity and the level of brain-derived neurotrophic factor mRNA in the brain and isolated microglia. A WD also activated ERK1/2 and reduced postsynaptic density-95 in the brain, suggesting postsynaptic damage. Moreover, WD-fed mice had increased inflammatory signaling in the brain, ileum, liver, adipose tissue, and spleen, which was accompanied by microglia activation. In the brain, as well as in the digestive tract, a WD reduced signaling regulated by retinoic acid and bile acids (BAs), whose receptors form heterodimers to control metabolism and inflammation. Furthermore, a WD intake caused dysbiosis and dysregulated BA synthesis with reduced endogenous ligands for BA receptors, i.e., farnesoid X receptor and G-protein-coupled bile acid receptor in the liver and brain. Together, dysregulated BA synthesis and dysbiosis were accompanied by systemic inflammation, microglial activation, and reduced neuroplasticity induced by WD.-Jena, P. K., Sheng, L., Di Lucente, J., Jin, L.-W., Maezawa, I., Wan, Y.-J. Y. Dysregulated bile acid synthesis and dysbiosis are implicated in Western diet-induced systemic inflammation, microglial activation, and reduced neuroplasticity. more...
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- 2018
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35. Kv1.3 inhibition as a potential microglia-targeted therapy for Alzheimer's disease: preclinical proof of concept.
- Author
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Maezawa I, Nguyen HM, Di Lucente J, Jenkins DP, Singh V, Hilt S, Kim K, Rangaraju S, Levey AI, Wulff H, and Jin LW
- Subjects
- Amyloid beta-Peptides pharmacology, Amyloid beta-Protein Precursor genetics, Animals, Animals, Newborn, Avoidance Learning drug effects, Cells, Cultured, Disease Models, Animal, Exploratory Behavior drug effects, Ficusin therapeutic use, Gene Expression Regulation drug effects, Gene Expression Regulation genetics, Kv1.3 Potassium Channel genetics, Membrane Potentials drug effects, Membrane Potentials genetics, Mice, Mice, Inbred C57BL, Mice, Transgenic, Microglia drug effects, Mutation genetics, Peptide Fragments pharmacology, Potassium Channel Blockers pharmacology, Presenilin-1 genetics, Shab Potassium Channels metabolism, Alzheimer Disease drug therapy, Alzheimer Disease metabolism, Alzheimer Disease pathology, Kv1.3 Potassium Channel metabolism, Microglia metabolism
- Abstract
Microglia significantly contribute to the pathophysiology of Alzheimer's disease but an effective microglia-targeted therapeutic approach is not yet available clinically. The potassium channels Kv1.3 and Kir2.1 play important roles in regulating immune cell functions and have been implicated by in vitro studies in the 'M1-like pro-inflammatory' or 'M2-like anti-inflammatory' state of microglia, respectively. We here found that amyloid-β oligomer-induced expression of Kv1.3 and Kir2.1 in cultured primary microglia. Likewise, ex vivo microglia acutely isolated from the Alzheimer's model 5xFAD mice co-expressed Kv1.3 and Kir2.1 as well as markers traditionally associated with M1 and M2 activation suggesting that amyloid-β oligomer induces a microglial activation state that is more complex than previously thought. Using the orally available, brain penetrant small molecule Kv1.3 blocker PAP-1 as a tool, we showed that pro-inflammatory and neurotoxic microglial responses induced by amyloid-β oligomer required Kv1.3 activity in vitro and in hippocampal slices. Since we further observed that Kv1.3 was highly expressed in microglia of transgenic Alzheimer's mouse models and human Alzheimer's disease brains, we hypothesized that pharmacological Kv1.3 inhibition could mitigate the pathology induced by amyloid-β aggregates. Indeed, treating APP/PS1 transgenic mice with a 5-month oral regimen of PAP-1, starting at 9 months of age, when the animals already manifest cognitive deficits and amyloid pathology, reduced neuroinflammation, decreased cerebral amyloid load, enhanced hippocampal neuronal plasticity, and improved behavioural deficits. The observed decrease in cerebral amyloid deposition was consistent with the in vitro finding that PAP-1 enhanced amyloid-β uptake by microglia. Collectively, these results provide proof-of-concept data to advance Kv1.3 blockers to Alzheimer's disease clinical trials., (© The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.) more...
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- 2018
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36. Defective GABAergic neurotransmission in the nucleus tractus solitarius in Mecp2-null mice, a model of Rett syndrome.
- Author
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Chen CY, Di Lucente J, Lin YC, Lien CC, Rogawski MA, Maezawa I, and Jin LW
- Subjects
- Animals, Disease Models, Animal, GABA-A Receptor Agonists, Methyl-CpG-Binding Protein 2 genetics, Mice, Inbred C57BL, Mice, Knockout, Miniature Postsynaptic Potentials, Neurons drug effects, RNA, Messenger metabolism, Receptors, GABA-A administration & dosage, Receptors, GABA-A physiology, Rett Syndrome metabolism, Solitary Nucleus metabolism, Inhibitory Postsynaptic Potentials, Methyl-CpG-Binding Protein 2 physiology, Neurons physiology, Rett Syndrome physiopathology, Solitary Nucleus physiology, Synaptic Transmission, gamma-Aminobutyric Acid physiology
- Abstract
Rett syndrome (RTT) is a devastating neurodevelopmental disorder caused by loss-of-function mutations in the X-linked methyl-CpG binding protein 2 (Mecp2) gene. GABAergic dysfunction has been implicated contributing to the respiratory dysfunction, one major clinical feature of RTT. The nucleus tractus solitarius (NTS) is the first central site integrating respiratory sensory information that can change the nature of the reflex output. We hypothesized that deficiency in Mecp2 gene reduces GABAergic neurotransmission in the NTS. Using whole-cell patch-clamp recordings in NTS slices, we measured spontaneous inhibitory postsynaptic currents (sIPSCs), miniature IPSCs (mIPSCs), NTS-evoked IPSCs (eIPSCs), and GABA
A receptor (GABAA -R) agonist-induced responses. Compared to those from wild-type mice, NTS neurons from Mecp2-null mice had significantly (p<0.05) reduced sIPSC amplitude, sIPSC frequency, and mIPSC amplitude but not mIPSC frequency. Mecp2-null mice also had decreased eIPSC amplitude with no change in paired-pulse ratio. The data suggest reduced synaptic receptor-mediated phasic GABA transmission in Mecp2-null mice. In contrast, muscimol (GABAA -R agonist, 0.3-100μM) and THIP (selective extrasynaptic GABAA -R agonist, 5μM) induced significantly greater current response in Mecp2-null mice, suggesting increased extrasynaptic receptors. Using qPCR, we found a 2.5 fold increase in the delta subunit of the GABAA -Rs in the NTS in Mecp2-null mice, consistent with increased extrasynaptic receptors. As the NTS was recently found required for respiratory pathology in RTT, our results provide a mechanism for NTS dysfunction which involves shifting the balance of synaptic/extrasynaptic receptors in favor of extrasynaptic site, providing a target for boosting GABAergic inhibition in RTT., (Copyright © 2017 Elsevier Inc. All rights reserved.) more...- Published
- 2018
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37. Inhibition of the potassium channel Kv1.3 reduces infarction and inflammation in ischemic stroke.
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Chen YJ, Nguyen HM, Maezawa I, Jin LW, and Wulff H
- Abstract
Objective: Inhibitors of the voltage-gated K
+ channel Kv1.3 are currently in development as immunomodulators for the treatment of autoimmune diseases. As Kv1.3 is also expressed on microglia and has been shown to be specifically up-regulated on "M1-like" microglia, we here tested the therapeutic hypothesis that the brain-penetrant small-molecule Kv1.3-inhibitor PAP-1 reduces secondary inflammatory damage after ischemia/reperfusion., Methods: We studied microglial Kv1.3 expression using electrophysiology and immunohistochemistry, and evaluated PAP-1 in hypoxia-exposed organotypic hippocampal slices and in middle cerebral artery occlusion (MCAO) with 8 days of reperfusion in both adult male C57BL/6J mice (60 min MCAO) and adult male Wistar rats (90 min MCAO). In both models, PAP-1 administration was started 12 h after reperfusion., Results: We observed Kv1.3 staining on activated microglia in ischemic infarcts in mice, rats, and humans and found higher Kv1.3 current densities in acutely isolated microglia from the infarcted hemisphere than in microglia isolated from the contralateral hemisphere of MCAO mice. PAP-1 reduced microglia activation and increased neuronal survival in hypoxia-exposed hippocampal slices as effectively as minocycline. In mouse MCAO, PAP-1 dose-dependently reduced infarct area, improved neurological deficit score, and reduced brain levels of IL-1 β and IFN- γ without affecting IL-10 and brain-derived nerve growth factor (BDNF) levels or inhibiting ongoing phagocytosis. The beneficial effects on infarct area and neurological deficit score were reproduced in rats providing confirmation in a second species., Interpretation: Our findings suggest that Kv1.3 constitutes a promising therapeutic target for preferentially inhibiting "M1-like" inflammatory microglia/macrophage functions in ischemic stroke. more...- Published
- 2017
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38. CX 3 CR1 ablation ameliorates motor and respiratory dysfunctions and improves survival of a Rett syndrome mouse model.
- Author
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Horiuchi M, Smith L, Maezawa I, and Jin LW
- Subjects
- Animals, Disease Models, Animal, Methyl-CpG-Binding Protein 2 genetics, Mice, Knockout, Neurons metabolism, Neurotoxicity Syndromes metabolism, Reactive Oxygen Species metabolism, Rett Syndrome genetics, Brain metabolism, CX3C Chemokine Receptor 1 genetics, Microglia metabolism, Mutation genetics, Rett Syndrome mortality
- Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by loss-of-function mutations in the gene encoding MeCP2, an epigenetic modulator that binds the methyl CpG dinucleotide in target genes to regulate transcription. Previously we and others reported a role of microglia in the pathophysiology of RTT. Because microglia in the Mecp2 knockout (Mecp2KO) mouse model of RTT over-produce neurotoxic mediators glutamate and reactive oxygen species, we hypothesize that blocking neuron-microglia interaction by ablation of CX
3 CR1, a chemokine receptor expressed in microglia/myeloid cells mediating such interaction by pairing with its neuronal ligand CX3 CL1, would ameliorate the RTT-like phenotype in Mecp2KO mice. Here we report that CX3 CR1 ablation prolonged the lifespan of Mecp2KO mice from a median survival of 54.5-74days, and significantly improved the body weight gain, symptomatic scores, major respiratory parameters, and motor coordination and performance. CX3 CR1 ablation rectified previously identified histological abnormalities in the Mecp2KO brain such as neuronal soma size in hippocampal CA2, and the number, soma size, and process complexity of microglia. Moreover, CX3 CR1 ablation enhanced the neurotrophic action of microglia in Mecp2KO mice by producing higher amount of insulin-like growth factor 1. Our data support a role of myeloid cells/microglia in RTT and suggest a novel therapeutic approach for RTT by targeting CX3 CR1 with specific antagonists or genetic downregulation., (Copyright © 2016. Published by Elsevier Inc.) more...- Published
- 2017
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39. Differential Kv1.3, KCa3.1, and Kir2.1 expression in "classically" and "alternatively" activated microglia.
- Author
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Nguyen HM, Grössinger EM, Horiuchi M, Davis KW, Jin LW, Maezawa I, and Wulff H
- Subjects
- Animals, Cells, Cultured, Interferon-gamma metabolism, Lipopolysaccharides pharmacology, Macrophage Activation, Membrane Potentials, Mice, Inbred C57BL, Intermediate-Conductance Calcium-Activated Potassium Channels metabolism, Kv1.3 Potassium Channel metabolism, Microglia metabolism, Potassium Channels, Inwardly Rectifying metabolism
- Abstract
Microglia are highly plastic cells that can assume different phenotypes in response to microenvironmental signals. Lipopolysaccharide (LPS) and interferon-γ (IFN-γ) promote differentiation into classically activated M1-like microglia, which produce high levels of pro-inflammatory cytokines and nitric oxide and are thought to contribute to neurological damage in ischemic stroke and Alzheimer's disease. IL-4 in contrast induces a phenotype associated with anti-inflammatory effects and tissue repair. We here investigated whether these microglia subsets vary in their K
+ channel expression by differentiating neonatal mouse microglia into M(LPS) and M(IL-4) microglia and studying their K+ channel expression by whole-cell patch-clamp, quantitative PCR and immunohistochemistry. We identified three major types of K+ channels based on their biophysical and pharmacological fingerprints: a use-dependent, outwardly rectifying current sensitive to the KV 1.3 blockers PAP-1 and ShK-186, an inwardly rectifying Ba2+ -sensitive Kir 2.1 current, and a Ca2+ -activated, TRAM-34-sensitive KCa 3.1 current. Both KV 1.3 and KCa 3.1 blockers inhibited pro-inflammatory cytokine production and iNOS and COX2 expression demonstrating that KV 1.3 and KCa 3.1 play important roles in microglia activation. Following differentiation with LPS or a combination of LPS and IFN-γ microglia exhibited high KV 1.3 current densities (∼50 pA/pF at 40 mV) and virtually no KCa 3.1 and Kir currents, while microglia differentiated with IL-4 exhibited large Kir 2.1 currents (∼ 10 pA/pF at -120 mV). KCa 3.1 currents were generally low but moderately increased following stimulation with IFN-γ or ATP (∼10 pS/pF). This differential K+ channel expression pattern suggests that KV 1.3 and KCa 3.1 inhibitors could be used to inhibit detrimental neuroinflammatory microglia functions. GLIA 2016;65:106-121., (© 2016 The Authors. Glia Published by Wiley Periodicals, Inc.) more...- Published
- 2017
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40. A Metal-Free Method for Producing MRI Contrast at Amyloid-β.
- Author
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Hilt S, Tang T, Walton JH, Budamagunta M, Maezawa I, Kálai T, Hideg K, Singh V, Wulff H, Gong Q, Jin LW, Louie A, and Voss JC
- Subjects
- Age Factors, Alzheimer Disease genetics, Alzheimer Disease pathology, Amyloid beta-Peptides metabolism, Amyloid beta-Protein Precursor genetics, Animals, Brain pathology, Disease Models, Animal, Female, Humans, Image Processing, Computer-Assisted, Male, Mice, Mice, Transgenic, Microscopy, Confocal, Mutation genetics, Presenilin-1 genetics, Alzheimer Disease diagnostic imaging, Brain diagnostic imaging, Contrast Media metabolism, Magnetic Resonance Imaging, Metals metabolism
- Abstract
Alzheimer's disease (AD) is characterized by depositions of the amyloid-β (Aβ) peptide in the brain. The disease process develops over decades, with substantial neurological loss occurring before a clinical diagnosis of dementia can be rendered. It is therefore imperative to develop methods that permit early detection and monitoring of disease progression. In addition, the multifactorial pathogenesis of AD has identified several potential avenues for AD intervention. Thus, evaluation of therapeutic candidates over lengthy trial periods also demands a practical, noninvasive method for measuring Aβ in the brain. Magnetic resonance imaging (MRI) is the obvious choice for such measurements, but contrast enhancement for Aβ has only been achieved using Gd(III)-based agents. There is great interest in gadolinium-free methods to image the brain. In this study, we provide the first demonstration that a nitroxide-based small-molecule produces MRI contrast in brain specimens with elevated levels of Aβ. The molecule is comprised of a fluorene (a molecule with high affinity for Aβ) and a nitroxide spin label (a paramagnetic MRI contrast species). Labeling of brain specimens with the spin-labeled fluorene produces negative contrast in samples from AD model mice whereas no negative contrast is seen in specimens harvested from wild-type mice. Injection of spin-labeled fluorene into live mice resulted in good brain penetration, with the compound able to generate contrast 24-h post injection. These results provide a proof of concept method that can be used for early, noninvasive, gadolinium-free detection of amyloid plaques by MRI. more...
- Published
- 2017
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41. The Anti-Amyloid-β and Neuroprotective Properties of a Novel Tricyclic Pyrone Molecule.
- Author
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Maezawa I, Zou B, Di Lucente J, Cao WS, Pascual C, Weerasekara S, Zhang M, Xie XS, Hua DH, and Jin LW
- Subjects
- Alzheimer Disease pathology, Alzheimer Disease physiopathology, Amyloid beta-Protein Precursor genetics, Amyloidogenic Proteins toxicity, Animals, Brain pathology, Cell Line, Tumor, Disease Models, Animal, Drinking Behavior drug effects, Excitatory Postsynaptic Potentials drug effects, Excitatory Postsynaptic Potentials genetics, Humans, Locomotion drug effects, Locomotion genetics, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Motor Activity drug effects, Motor Activity genetics, Mutation genetics, Neuroblastoma pathology, Neuroprotective Agents chemistry, Presenilin-1 genetics, Pyrones chemical synthesis, Pyrones chemistry, Alzheimer Disease drug therapy, Amyloidogenic Proteins metabolism, Brain drug effects, Brain metabolism, Neuroprotective Agents therapeutic use, Pyrones therapeutic use
- Abstract
There is an urgent unmet need for new therapeutics for Alzheimer's disease (AD), the most common cause of dementia in the elderly. Therapeutic approaches targeting amyloid-β (Aβ) and its downstream toxicities have become major strategies in AD drug development. We have taken a rational design approach and synthesized a class of tricyclic pyrone (TP) compounds that show anti-Aβ and other neuroprotective actions. The in vivo efficacy of a lead TP named CP2 to ameliorate AD-like pathologies has been shown in mouse models. Here we report the selection and initial characterization of a new lead TP70, which exhibited an anti-Aβ therapeutic index even higher than CP2. Moreover, TP70 was able to reduce oxidative stress, inhibit acyl-coenzyme A:cholesterol acyltransferase (ACAT), and upregulate the expression of ATP-binding cassette subfamily A, member 1 (ABCA1), actions considered neuroprotective in AD. TP70 further showed excellent pharmacokinetic properties, including brain penetration and oral availability. When administered to 5xFAD mice via intraperitoneal or oral route, TP70 enhanced the overall solubility and decreased the level of cerebral Aβ, including both fibrillary and soluble Aβ species. Interestingly, TP70 enhanced N-methyl-D-aspartate (NMDA) receptor-mediated excitatory post-synaptic potential (EPSP) in the hippocampal CA1 area, increased the magnitude of NMDA-dependent hippocampal long-term potentiation (LTP), a cellular model of learning and memory, and prevented the Aβ oligomer-impaired LTP. Significantly, a single dose of TP70 administered to aged 5xFAD mice was effective in mitigating the impaired LTP induction, recorded at 24 h after administration. Our results support a potential of TP70 in clinical development for AD in view of its synergistic neuroprotective actions, ability to positively modulate NMDA receptor-mediated hippocampal plasticity, and favorable pharmacokinetic properties in rodents. more...
- Published
- 2017
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42. The potassium channel KCa3.1 constitutes a pharmacological target for neuroinflammation associated with ischemia/reperfusion stroke.
- Author
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Chen YJ, Nguyen HM, Maezawa I, Grössinger EM, Garing AL, Köhler R, Jin LW, and Wulff H
- Subjects
- Animals, Brain metabolism, Brain Ischemia pathology, Cells, Cultured, Disease Models, Animal, Humans, Infarction, Middle Cerebral Artery, Macrophage Activation, Mice, Molecular Targeted Therapy, Pyrazoles pharmacology, Pyrazoles therapeutic use, Intermediate-Conductance Calcium-Activated Potassium Channels antagonists & inhibitors, Neurogenic Inflammation drug therapy, Stroke pathology
- Abstract
Activated microglia/macrophages significantly contribute to the secondary inflammatory damage in ischemic stroke. Cultured neonatal microglia express the K
+ channels Kv1.3 and KCa3.1, both of which have been reported to be involved in microglia-mediated neuronal killing, oxidative burst and cytokine production. However, it is questionable whether neonatal cultures accurately reflect the K+ channel expression of activated microglia in the adult brain. We here subjected mice to middle cerebral artery occlusion with eight days of reperfusion and patch-clamped acutely isolated microglia/macrophages. Microglia from the infarcted area exhibited higher densities of K+ currents with the biophysical and pharmacological properties of Kv1.3, KCa3.1 and Kir2.1 than microglia from non-infarcted control brains. Similarly, immunohistochemistry on human infarcts showed strong Kv1.3 and KCa3.1 immunoreactivity on activated microglia/macrophages. We next investigated the effect of genetic deletion and pharmacological blockade of KCa3.1 in reversible middle cerebral artery occlusion. KCa3.1-/- mice and wild-type mice treated with the KCa3.1 blocker TRAM-34 exhibited significantly smaller infarct areas on day-8 after middle cerebral artery occlusion and improved neurological deficit. Both manipulations reduced microglia/macrophage activation and brain cytokine levels. Our findings suggest KCa3.1 as a pharmacological target for ischemic stroke. Of potential, clinical relevance is that KCa3.1 blockade is still effective when initiated 12 h after the insult., (© The Author(s) 2015.) more...- Published
- 2016
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43. Protective spin-labeled fluorenes maintain amyloid beta peptide in small oligomers and limit transitions in secondary structure.
- Author
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Altman R, Ly S, Hilt S, Petrlova J, Maezawa I, Kálai T, Hideg K, Jin LW, Laurence TA, and Voss JC
- Subjects
- Cell Line, Circular Dichroism, Humans, Protein Structure, Secondary, Amyloid beta-Peptides chemistry, Fluorenes chemistry, Spin Labels
- Abstract
Alzheimer's disease is characterized by the presence of extracellular plaques comprised of amyloid beta (Aβ) peptides. Soluble oligomers of the Aβ peptide underlie a cascade of neuronal loss and dysfunction associated with Alzheimer's disease. Single particle analyses of Aβ oligomers in solution by fluorescence correlation spectroscopy (FCS) were used to provide real-time descriptions of how spin-labeled fluorenes (SLFs; bi-functional small molecules that block the toxicity of Aβ) prevent and disrupt oligomeric assemblies of Aβ in solution. Furthermore, the circular dichroism (CD) spectrum of untreated Aβ shows a continuous, progressive change over a 24-hour period, while the spectrum of Aβ treated with SLF remains relatively constant following initial incubation. These findings suggest the conformation of Aβ within the oligomer provides a complementary determinant of Aβ toxicity in addition to oligomer growth and size. Although SLF does not produce a dominant state of secondary structure in Aβ, it does induce a net reduction in beta secondary content compared to untreated samples of Aβ. The FCS results, combined with electron paramagnetic resonance spectroscopy and CD spectroscopy, demonstrate SLFs can inhibit the growth of Aβ oligomers and disrupt existing oligomers, while retaining Aβ as a population of smaller, yet largely disordered oligomers., (Copyright © 2015 Elsevier B.V. All rights reserved.) more...
- Published
- 2015
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44. Modulation of mitochondrial complex I activity averts cognitive decline in multiple animal models of familial Alzheimer's Disease.
- Author
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Zhang L, Zhang S, Maezawa I, Trushin S, Minhas P, Pinto M, Jin LW, Prasain K, Nguyen TD, Yamazaki Y, Kanekiyo T, Bu G, Gateno B, Chang KO, Nath KA, Nemutlu E, Dzeja P, Pang YP, Hua DH, and Trushina E
- Abstract
Development of therapeutic strategies to prevent Alzheimer's Disease (AD) is of great importance. We show that mild inhibition of mitochondrial complex I with small molecule CP2 reduces levels of amyloid beta and phospho-Tau and averts cognitive decline in three animal models of familial AD. Low-mass molecular dynamics simulations and biochemical studies confirmed that CP2 competes with flavin mononucleotide for binding to the redox center of complex I leading to elevated AMP/ATP ratio and activation of AMP-activated protein kinase in neurons and mouse brain without inducing oxidative damage or inflammation. Furthermore, modulation of complex I activity augmented mitochondrial bioenergetics increasing coupling efficiency of respiratory chain and neuronal resistance to stress. Concomitant reduction of glycogen synthase kinase 3β activity and restoration of axonal trafficking resulted in elevated levels of neurotrophic factors and synaptic proteins in adult AD mice. Our results suggest metabolic reprogramming induced by modulation of mitochondrial complex I activity represents promising therapeutic strategy for AD. more...
- Published
- 2015
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45. Dysregulation of glutamine transporter SNAT1 in Rett syndrome microglia: a mechanism for mitochondrial dysfunction and neurotoxicity.
- Author
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Jin LW, Horiuchi M, Wulff H, Liu XB, Cortopassi GA, Erickson JD, and Maezawa I
- Subjects
- Adenosine Triphosphate metabolism, Animals, Glutamic Acid metabolism, Glycine metabolism, Methyl-CpG-Binding Protein 2 genetics, Methyl-CpG-Binding Protein 2 metabolism, Mice, Mice, Inbred C57BL, Mice, Knockout, Oxygen Consumption physiology, Primary Cell Culture, Amino Acid Transport System A metabolism, Microglia metabolism, Mitochondrial Diseases metabolism, Neurotoxicity Syndromes metabolism, Rett Syndrome metabolism
- Abstract
Rett syndrome (RTT) is an autism spectrum disorder caused by loss-of-function mutations in the gene encoding MeCP2, an epigenetic modulator that binds the methyl CpG dinucleotide in target genes to regulate transcription. Previously, we and others reported a role of microglia in the pathophysiology of RTT. To understand the mechanism of microglia dysfunction in RTT, we identified a MeCP2 target gene, SLC38A1, which encodes a major glutamine transporter (SNAT1), and characterized its role in microglia. We found that MeCP2 acts as a microglia-specific transcriptional repressor of SNAT1. Because glutamine is mainly metabolized in the mitochondria, where it is used as an energy substrate and a precursor for glutamate production, we hypothesize that SNAT1 overexpression in MeCP2-deficient microglia would impair the glutamine homeostasis, resulting in mitochondrial dysfunction as well as microglial neurotoxicity because of glutamate overproduction. Supporting this hypothesis, we found that MeCP2 downregulation or SNAT1 overexpression in microglia resulted in (1) glutamine-dependent decrease in microglial viability, which was corroborated by reduced microglia counts in the brains of MECP2 knock-out mice; (2) proliferation of mitochondria and enhanced mitochondrial production of reactive oxygen species; (3) increased oxygen consumption but decreased ATP production (an energy-wasting state); and (4) overproduction of glutamate that caused NMDA receptor-dependent neurotoxicity. The abnormalities could be rectified by mitochondria-targeted expression of catalase and a mitochondria-targeted peptide antioxidant, Szeto-Schiller 31. Our results reveal a novel mechanism via which MeCP2 regulates bioenergetic pathways in microglia and suggest a therapeutic potential of mitochondria-targeted antioxidants for RTT., (Copyright © 2015 the authors 0270-6474/15/352516-14$15.00/0.) more...
- Published
- 2015
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46. Tomoregulin (TMEFF2) Binds Alzheimer's Disease Amyloid-β (Aβ) Oligomer and AβPP and Protects Neurons from Aβ-Induced Toxicity.
- Author
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Hong HS, Maezawa I, Petrlova J, Zhao XY, C Voss J, and Jin LW
- Subjects
- Amyloid Precursor Protein Secretases metabolism, Animals, Astrocytes pathology, Astrocytes physiology, Cell Line, Tumor, Cell Survival physiology, Electron Spin Resonance Spectroscopy, Fluorescent Antibody Technique, Gene Silencing, Humans, Immunoprecipitation, Mice, Transgenic, Microscopy, Confocal, Neurons pathology, Plaque, Amyloid pathology, Plaque, Amyloid physiopathology, RNA Interference, Recombinant Proteins metabolism, Surface Plasmon Resonance, Amyloid beta-Protein Precursor metabolism, Membrane Proteins metabolism, Neoplasm Proteins metabolism, Neurons physiology
- Abstract
Amyloid-β (Aβ) protein causes neurotoxicity and its abnormal aggregation into amyloid is a pathological hallmark of Alzheimer's disease (AD). Cellular proteins able to interact with Aβ or its precursor, AβPP (amyloid-β protein precursor), may regulate Aβ production and neurotoxicity. We identified a brain-enriched type I transmembrane protein, tomoregulin (TR), that directly binds Aβ and Aβ oligomers (AβO). TR co-immunoprecipitated with Aβ and AβO in cultured cells and co-localized with amyloid plaques and intraneuronal Aβ in the 5xFAD AD mouse model. TR was also enriched in astrocytic processes reactive to amyloid plaques. Surface plasmon resonance spectroscopy studies showed that the extracellular domain of TR binds to AβO with a high affinity (KD = 76.8 nM). Electron paramagnetic resonance spectroscopy also demonstrated a physical interaction between spin-labeled Aβ and the TR extracellular domain in solution. Furthermore, TR also interacted with AβPP and enhanced its cleavage by α-secretase. Both cellular expression of TR and application of recombinant TR extracellular domain protected N2a neurons from AβO-induced neuronal death. These data provide first evidence that neuronal and astrocytic expression of TR is intimately related to Aβ metabolism and toxicity, and could be neuroprotective through its direct interaction with Aβ and AβPP. more...
- Published
- 2015
- Full Text
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47. Syntheses of 3-[(Alkylamino)methylene]-6-methylpyridine-2,4(1 H ,3 H )-diones, 3-Substituted 7-Methyl-2 H -pyrano[3,2- c ]pyridine-2,5(6 H )-dione Fluorescence Probes, and Tetrahydro-1 H ,9 H -2,10-dioxa-9-azaanthracen-1-ones.
- Author
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Prior AM, Gunaratna MJ, Kikuchi D, Desper J, Kim Y, Chang KO, Maezawa I, Jin LW, and Hua DH
- Abstract
Various condensation and ring-closing reactions were used for the syntheses of 3-[(alkylamino)methylene]-6-methylpyri-dine-2,4(1 H ,3 H )-diones, bicyclic pyridinones, and tricyclic morpholinopyrones. For instance, 3-[(dialkylamino)methylene]-6-methylpyridine-2,4(1 H ,3 H )-diones were synthesized from the condensation of dialkylamines and 3-formyl-4-hydroxy-6-methylpyridin-2(1 H )-one. 3-Formyl-4-hydroxy-6-methylpyridin-2(1 H )-one, derived from 3-formyl-4-hydroxy-6-methylpyridin-2(1 H )-one, was used to construct a number of bicyclic pyridinones via a one-pot Knoevenagal and intramolecular lactonization reaction. Tricyclic morpholinopyrones were assembled from a dialkylation reaction involving a dinucleophile, 3-amino-4-hydroxy-6-methyl-2 H -pyran-2-one, and a dielectrophile, trans -3,6-dibromocyclohexene. Depending on the reaction conditions, isomers of the tricyclic molecules can be selectively produced, and their chemical structures were unequivocally determined using single-crystal X-ray analyses and 2D COSY spectroscopy. The fluorescently active bicyclic pyridinone compounds show longer absorption (368-430 nm; maximum) and emission wavelengths (450-467 nm) than those of 7-amino-4-methylcoumarin (AMC; λ
abs,max = 350 nm; λem = 430 nm) suggesting these molecules, such as 3-(2-aminoacetyl)-7-methyl-2 H -pyrano[3,2- c ]pyridine-2,5(6 H )-dione, can be employed as fluorescence activity based probes for tracing biological pathways. more...- Published
- 2014
- Full Text
- View/download PDF
48. Syntheses, neural protective activities, and inhibition of glycogen synthase kinase-3β of substituted quinolines.
- Author
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Lu J, Maezawa I, Weerasekara S, Erenler R, Nguyen TD, Nguyen J, Swisher LZ, Li J, Jin LW, Ranjan A, Srivastava SK, and Hua DH
- Subjects
- Alzheimer Disease metabolism, Animals, Cell Line, Dose-Response Relationship, Drug, Enzyme Inhibitors chemical synthesis, Enzyme Inhibitors chemistry, Glycogen Synthase Kinase 3 metabolism, Mice, Models, Animal, Molecular Structure, Protein Kinase C metabolism, Quinolines chemical synthesis, Quinolines chemistry, Structure-Activity Relationship, Alzheimer Disease enzymology, Enzyme Inhibitors pharmacology, Glycogen Synthase Kinase 3 antagonists & inhibitors, Quinolines pharmacology
- Abstract
A new series of fifteen 5-, 6-, and 8-appended 4-methylquinolines were synthesized and evaluated for their neural protective activities. Selected compounds were further examined for their inhibition of glycogen synthase kinase-3β (GSK-3β) and protein kinase C (PKC). Two most potent analogs, compounds 3 and 10, show nanomolar protective activities in amyloid β-induced MC65 cells and enzymatic inhibitory activities against GSK-3β, but poor PKC inhibitory activities. Using normal mouse model, the distribution of the most potent analog 3 in various tissues and possible toxic effects in the locomotors and inhibition of liver transaminases activities were carried out. No apparent decline of locomotor activity and no inhibition of liver transaminases were found. The compound appears to be safe for long-term use in Alzheimer's disease mouse model., (Copyright © 2014 Elsevier Ltd. All rights reserved.) more...
- Published
- 2014
- Full Text
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49. Synthesis and functional survey of new Tacrine analogs modified with nitroxides or their precursors.
- Author
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Kálai T, Altman R, Maezawa I, Balog M, Morisseau C, Petrlova J, Hammock BD, Jin LW, Trudell JR, Voss JC, and Hideg K
- Subjects
- Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Antioxidants chemical synthesis, Antioxidants chemistry, Cell Line, Tumor, Cell Proliferation drug effects, Cholinesterase Inhibitors chemical synthesis, Cholinesterase Inhibitors chemistry, Dose-Response Relationship, Drug, Drug Screening Assays, Antitumor, Humans, Models, Molecular, Molecular Structure, Structure-Activity Relationship, Tacrine chemical synthesis, Tacrine chemistry, Acetylcholinesterase metabolism, Antineoplastic Agents pharmacology, Antioxidants pharmacology, Cholinesterase Inhibitors pharmacology, Nitrogen Oxides chemistry, Tacrine analogs & derivatives, Tacrine pharmacology
- Abstract
A series of new Tacrine analogs modified with nitroxides or pre-nitroxides on 9-amino group via methylene or piperazine spacers were synthesized; the nitroxide or its precursors were incorporated into the Tacrine scaffold. The new compounds were tested for their hydroxyl radical and peroxyl radical scavenging ability, acetylcholinesterase inhibitor activity and protection against Aβ-induced cytotoxicity. Based on these assays, we conclude that Tacrine analogs connected to five and six-membered nitroxides via piperazine spacers (9b, 9b/HCl and 12) exhibited the best activity, providing direction for further development of additional candidates with dual functionality (anti Alzheimer's and antioxidant)., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.) more...
- Published
- 2014
- Full Text
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50. Inhibition of Acyl-CoA: cholesterol acyltransferase (ACAT), overexpression of cholesterol transporter gene, and protection of amyloid β (Aβ) oligomers-induced neuronal cell death by tricyclic pyrone molecules.
- Author
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Pokhrel L, Maezawa I, Nguyen TD, Chang KO, Jin LW, and Hua DH
- Subjects
- ATP Binding Cassette Transporter 1, ATP-Binding Cassette Transporters genetics, Cell Death, Cell Line, Gene Expression, Heterocyclic Compounds, 3-Ring chemistry, Heterocyclic Compounds, 3-Ring pharmacology, Humans, Neurons cytology, Pyrones chemistry, Pyrones pharmacology, Stereoisomerism, Structure-Activity Relationship, ATP-Binding Cassette Transporters metabolism, Acetyl-CoA C-Acetyltransferase antagonists & inhibitors, Amyloid beta-Peptides physiology, Heterocyclic Compounds, 3-Ring chemical synthesis, Neurons drug effects, Pyrones chemical synthesis
- Abstract
A major effort in Alzheimer's disease therapeutic development has targeted Aβ and downstream events. We have synthesized a small library of tricyclic pyrone compounds. Their protective action in MC65 cells and inhibition of ACAT along with the upregulation of cholesterol transporter gene were investigated. Five active compounds exhibited potencies in the nanomolar ranges. The multiple effects of the compounds on Aβ and cellular cholesterol pathways could be potential mechanisms underlying the protective effects in vivo. more...
- Published
- 2012
- Full Text
- View/download PDF
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