27 results on '"Haruki Higashimori"'
Search Results
2. Functionally Clustered mRNAs Are Distinctly Enriched at Cortical Astroglial Processes and Are Preferentially Affected by FMRP Deficiency
- Author
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Yuqin Men, Haruki Higashimori, Kathryn Reynolds, Leona Tu, Rachel Jarvis, and Yongjie Yang
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Male ,Mammals ,Mice, Knockout ,Fragile X Mental Retardation Protein ,Mice ,Excitatory Amino Acid Transporter 2 ,Astrocytes ,Receptor, Metabotropic Glutamate 5 ,General Neuroscience ,Synapses ,Animals ,RNA, Messenger ,Research Articles - Abstract
Mature protoplasmic astroglia in the mammalian CNS uniquely possess a large number of fine processes that have been considered primary sites to mediate astroglia to neuron synaptic signaling. However, localized mechanisms for regulating interactions between astroglial processes and synapses, especially for regulating the expression of functional surface proteins at these fine processes, are largely unknown. Previously, we showed that the loss of the RNA binding protein FMRP in astroglia disrupts astroglial mGluR5 signaling and reduces expression of the major astroglial glutamate transporter GLT1 and glutamate uptake in the cortex of Fmr1 conditional deletion mice. In the current study, by examining ribosome localization using electron microscopy and identifying mRNAs enriched at cortical astroglial processes using synaptoneurosome/translating ribosome affinity purification and RNA-Seq in WT and FMRP-deficient male mice, our results reveal interesting localization-dependent functional clusters of mRNAs at astroglial processes. We further showed that the lack of FMRP preferentially alters the subcellular localization and expression of process-localized mRNAs. Together, we defined the role of FMRP in altering mRNA localization and expression at astroglial processes at the postnatal development (P30-P40) and provided new candidate mRNAs that are potentially regulated by FMRP in cortical astroglia. SIGNIFICANCE STATEMENT Localized mechanisms for regulating interactions between astroglial processes and synapses, especially for regulating the expression of functional surface proteins at these fine processes, are largely unknown. Previously, we showed that the loss of the RNA binding protein FMRP in astroglia disrupts expression of several astroglial surface proteins, such as mGluR5 and major astroglial glutamate transporter GLT1 in the cortex of FMRP-deficient mice. Our current study examined ribosome localization using electron microscopy and identified mRNAs enriched at cortical astroglial processes in WT and FMRP-deficient mice. These results reveal interesting localization-dependent functional clusters of mRNAs at astroglial processes and demonstrate that the lack of FMRP preferentially alters the subcellular localization and expression of process-localized mRNAs.
- Published
- 2022
3. Exosome reporter mice reveal the involvement of exosomes in mediating neuron to astroglia communication in the CNS
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Yongjie Yang, Julia Yelick, Eoin Brown, Shijie Jin, Rachel Jarvis, Haruki Higashimori, Yuqin Men, Ming Sum R. Chiang, and Yang Tian
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Central Nervous System ,0301 basic medicine ,Cell biology ,Cell signaling ,Endosome ,Science ,Green Fluorescent Proteins ,General Physics and Astronomy ,Cell Communication ,Biology ,Exosomes ,Models, Biological ,Exosome ,Article ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,0302 clinical medicine ,Genes, Reporter ,medicine ,Animals ,Humans ,lcsh:Science ,Neurons ,Multidisciplinary ,Intercellular Communication Process ,General Chemistry ,Microvesicles ,Mice, Inbred C57BL ,MicroRNAs ,030104 developmental biology ,medicine.anatomical_structure ,Excitatory Amino Acid Transporter 2 ,nervous system ,Astrocytes ,Soma ,lcsh:Q ,Neuron ,Astrocyte ,030217 neurology & neurosurgery ,Neuroscience - Abstract
Astroglia play active and diverse roles in modulating neuronal/synaptic functions in the CNS. How these astroglial functions are regulated, especially by neuronal signals, remains largely unknown. Exosomes, a major type of extracellular vesicles (EVs) that originate from endosomal intraluminal vesicles (ILVs), have emerged as a new intercellular communication process. By generating cell-type-specific ILVs/exosome reporter (CD63-GFPf/f) mice and immuno-EM/confocal image analysis, we found that neuronal CD63-GFP+ ILVs are primarily localized in soma and dendrites, but not in axonal terminals in vitro and in vivo. Secreted neuronal exosomes contain a subset of microRNAs (miRs) that is distinct from the miR profile of neurons. These miRs, especially the neuron-specific miR-124-3p, are potentially internalized into astrocytes. MiR-124-3p further up-regulates the predominant glutamate transporter GLT1 by suppressing GLT1-inhibiting miRs. Our findings suggest a previously undescribed neuronal exosomal miR-mediated genetic regulation of astrocyte functions, potentially opening a new frontier in understanding CNS intercellular communication., Our current understanding of exosome signaling among CNS cells is mostly limited to culture models. In this study, authors generated a new cell-type specific exosome reporter mouse line which allows the first in vivo investigation of the localization of neuronal exosomes in the CNS, and also potentially highlights the role of exosomally transferred miR-124-3p in mediating astroglial glutamate uptake function
- Published
- 2019
4. Astroglial FMRP modulates synaptic signaling and behavior phenotypes in FXS mouse model
- Author
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Yuqin Men, Ming Sum R. Chiang, Shan-Xue Jin, Christina Schin, Alessandra Tamashiro, Dan Cox, Haruki Higashimori, Larry A. Feig, Yongjie Yang, and Rachel Jarvis
- Subjects
0301 basic medicine ,Cell signaling ,Cell type ,congenital, hereditary, and neonatal diseases and abnormalities ,Biology ,Receptors, N-Methyl-D-Aspartate ,Open field ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Fragile X Mental Retardation Protein ,Mice ,0302 clinical medicine ,medicine ,Animals ,medicine.disease ,FMR1 ,Phenotype ,nervous system diseases ,Fragile X syndrome ,Disease Models, Animal ,030104 developmental biology ,Neurology ,Astrocytes ,Fragile X Syndrome ,NMDA receptor ,Synaptic signaling ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Fragile X syndrome (FXS) is one of the most common inherited intellectual disability (ID) disorders, in which the loss of FMRP protein induces a range of cellular signaling changes primarily through excess protein synthesis. Although neuron-centered molecular and cellular events underlying FXS have been characterized, how different CNS cell types are involved in typical FXS synaptic signaling changes and behavioral phenotypes is largely unknown. Recent evidence suggests that selective loss of astroglial FMRP is able to dysregulate glutamate uptake, increase spine density, and impair motor-skill learning. Here we investigated the effect of astroglial FMRP on synaptic signaling and FXS-related behavioral and learning phenotypes in astroglial Fmr1 cKO and cON mice in which FMRP expression is selectively diminished or restored in astroglia. We found that selective loss of astroglial FMRP contributes to cortical hyperexcitability by enhancing NMDAR-mediated evoked but not spontaneous miniEPSCs and elongating cortical UP state duration. Selective loss of astroglial FMRP is also sufficient to increase locomotor hyperactivity, significantly diminish social novelty preference, and induce memory acquisition and extinction deficits in astroglial Fmr1 cKO mice. Importantly, re-expression of astroglial FMRP is able to significantly rescue the hyperactivity (evoked NMDAR response, UP state duration, and open field test) and social novelty preference in astroglial Fmr1 cON mice. These results demonstrate a profound role of astroglial FMRP in the evoked synaptic signaling, spontaneously occurring cortical UP states, and FXS-related behavioral and learning phenotypes and provide important new insights in the cell type consideration for the FMRP reactivation strategy.
- Published
- 2020
5. The role of Nhe6 in inhibitory synaptic vesicles during development using Slc9A6-deficient rats
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Adam Friedberg, Haruki Higashimori
- Published
- 2020
- Full Text
- View/download PDF
6. Long-term depression induced by endogenous cannabinoids produces neuroprotection via astroglial CB1R after stroke in rodents
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Li Tong, Jingjing Liu, Lize Xiong, Jingyi Wang, Haruki Higashimori, Yongjie Yang, Hailong Dong, Feng Wang, Xia Zhang, and Jing Han
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Programmed cell death ,business.industry ,Ischemia ,Endogeny ,medicine.disease ,Neuroprotection ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,medicine.anatomical_structure ,Neurology ,chemistry ,medicine ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,business ,Long-term depression ,Stroke ,Neuroscience ,030217 neurology & neurosurgery ,JZL195 ,Astrocyte - Abstract
Ischemia not only activates cell death pathways but also triggers endogenous protective mechanisms. However, it is largely unknown what is the essence of the endogenous neuroprotective mechanisms induced by preconditioning. In this study we demonstrated that systemic injection of JZL195, a selective inhibitor of eCB clearance enzymes, induces in vivo long-term depression at CA3-CA1 synapses and at PrL-NAc synapses produces neuroprotection. JZL195-elicited long-term depression is blocked by AM281, the antagonist of cannabinoid 1 receptor (CB1R) and is abolished in mice lacking cannabinoid CB1receptor (CB1R) in astroglial cells, but is conserved in mice lacking CB1R in glutamatergic or GABAergic neurons. Blocking the glutamate NMDA receptor and the synaptic trafficking of glutamate AMPA receptor abolishes both long-term depression and neuroprotection induced by JZL195. Mice lacking CB1R in astroglia show decreased neuronal death following cerebral ischemia. Thus, an acute elevation of extracellular eCB following eCB clearance inhibition results in neuroprotection through long-term depression induction after sequential activation of astroglial CB1R and postsynaptic glutamate receptors.
- Published
- 2018
7. Intracortical astrocyte subpopulations defined by astrocyte reporter Mice in the adult brain
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Lydie Morel, Julia Yelick, Yuqin Men, Haruki Higashimori, Shijie Jin, Yongjie Yang, Yang Tian, and Ming S. R. Chiang
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0301 basic medicine ,Male ,Population ,Mice, Transgenic ,Biology ,Green fluorescent protein ,Transcriptome ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Mice ,Random Allocation ,0302 clinical medicine ,Organ Culture Techniques ,medicine ,Animals ,education ,Gliogenesis ,Cerebral Cortex ,education.field_of_study ,Age Factors ,Brain ,Flow Cytometry ,Cortex (botany) ,Cell biology ,Mice, Inbred C57BL ,030104 developmental biology ,medicine.anatomical_structure ,Neurology ,Cerebral cortex ,Astrocytes ,Female ,030217 neurology & neurosurgery ,Intracellular ,Astrocyte - Abstract
Although historically regarded as a homogeneous cell population, astrocytes in different brain regions exhibit differences in their physiological properties, such as gap-junction coupling, glutamate uptake dynamics, and intracellular Ca2+ response. Recent in vivo RNA profiles have further demonstrated the molecular heterogeneity of astrocytes in the adult CNS. Astrocyte heterogeneity exists not only inter-regionally but also intra-regionally. Despite the characteristic laminal organization of cortical layers and multiple sources of radial glia progenitors for (astro)gliogenesis, the molecular profile and functional properties of astroglial subpopulations in the adult cerebral cortex remain essentially undefined. Using two astrocyte reporter mouse lines: eaat2-tdTomato and Bac aldh1l1-eGFP, we identified tdT- eGFP+ , tdTlow eGFP+ , and tdThigh eGFP+ astroglial subpopulations (in an approximate 1:7:2 ratio) within the cortex. The tdT- eGFP+ astrocyte population is selectively localized at layers I-II and exhibits increased resting membrane potential and membrane resistance but reduced functional expression of the potassium channel Kir4.1. We also isolated individual astrocyte subpopulations through fluorescence activated cell sorting (FACS) and examined their transcriptome differences by RNA-seq. We found that the whole-genome transcriptional profiles of tdT- eGFP+ astrocytes are drastically different from that of tdTlow eGFP+ and tdThigh eGFP+ astrocytes. Particularly, elevated levels of several nonastrocyte genes that are typically specific to other glial cells, such as mog, mobp, Iba1, and pdgfrα, are observed in tdT- eGFP+ astrocytes, suggesting a less-specific molecular identity of these astrocytes. Overall, our study has unveiled molecular differences between adult cortical astroglial subpopulations, shedding new light on understanding their unique functions in the adult cortex.
- Published
- 2018
8. Long-term depression induced by endogenous cannabinoids produces neuroprotection via astroglial CB
- Author
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Feng, Wang, Jing, Han, Haruki, Higashimori, Jingyi, Wang, Jingjing, Liu, Li, Tong, Yongjie, Yang, Hailong, Dong, Xia, Zhang, and Lize, Xiong
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Stroke ,Mice ,Receptor, Cannabinoid, CB1 ,Receptors, Glutamate ,Cannabinoids ,Astrocytes ,Long-Term Synaptic Depression ,Animals ,Rodentia ,Carbamates ,Original Articles ,Neuroprotection ,Piperazines - Abstract
Ischemia not only activates cell death pathways but also triggers endogenous protective mechanisms. However, it is largely unknown what is the essence of the endogenous neuroprotective mechanisms induced by preconditioning. In this study we demonstrated that systemic injection of JZL195, a selective inhibitor of eCB clearance enzymes, induces in vivo long-term depression at CA3-CA1 synapses and at PrL-NAc synapses produces neuroprotection. JZL195-elicited long-term depression is blocked by AM281, the antagonist of cannabinoid 1 receptor (CB(1)R) and is abolished in mice lacking cannabinoid CB(1) receptor (CB(1)R) in astroglial cells, but is conserved in mice lacking CB(1)R in glutamatergic or GABAergic neurons. Blocking the glutamate NMDA receptor and the synaptic trafficking of glutamate AMPA receptor abolishes both long-term depression and neuroprotection induced by JZL195. Mice lacking CB(1)R in astroglia show decreased neuronal death following cerebral ischemia. Thus, an acute elevation of extracellular eCB following eCB clearance inhibition results in neuroprotection through long-term depression induction after sequential activation of astroglial CB(1)R and postsynaptic glutamate receptors.
- Published
- 2018
9. Loss of SIRT4 decreases GLT-1-dependent glutamate uptake and increases sensitivity to kainic acid
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Gizem Donmez, Andrew Mason, Haruki Higashimori, Jennifer Shih, and Lei Liu
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Male ,Kainic acid ,Traumatic brain injury ,Excitotoxicity ,Glutamic Acid ,Neurotransmission ,medicine.disease_cause ,Biochemistry ,Mitochondrial Proteins ,Mice ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Seizures ,Excitatory Amino Acid Agonists ,medicine ,Extracellular ,Animals ,Sirtuins ,Biotinylation ,Amyotrophic lateral sclerosis ,Cells, Cultured ,Mice, Knockout ,Neurons ,Kainic Acid ,biology ,Glutamate receptor ,Brain ,Embryo, Mammalian ,medicine.disease ,Cell biology ,Disease Models, Animal ,Excitatory Amino Acid Transporter 2 ,Gene Expression Regulation ,chemistry ,Sirtuin ,biology.protein ,Female ,Synaptosomes - Abstract
Glutamate transport is a critical process in the brain that maintains low extracellular levels of glutamate to allow for efficient neurotransmission and prevent excitotoxicity. Loss of glutamate transport function is implicated in epilepsy, traumatic brain injury, and amyotrophic lateral sclerosis. It remains unclear whether or not glutamate transport can be modulated in these disease conditions to improve outcome. Here, we show that sirtuin (SIRT)4, a mitochondrial sirtuin, is up-regulated in response to treatment with the potent excitotoxin kainic acid. Loss of SIRT4 leads to a more severe reaction to kainic acid and decreased glutamate transporter expression and function in the brain. Together, these results indicate a critical and novel stress response role for SIRT4 in promoting proper glutamate transport capacity and protecting against excitotoxicity. Loss of sirtuin 4 (SIRT4) in mice leads to decreased glutamate transporter expression and function in the brain, which can ultimately cause increased excitotoxic effects. SIRT4 is up-regulated in response to treatment with the potent excitotoxin kainic acid. These results indicate a critical and novel stress response role for SIRT4 in promoting proper glutamate transport capacity and protecting against excitotoxicity. GLT-1, Glutamate Transporter 1, same as excitatory amino acid transporter 2; Glu, glutamate.
- Published
- 2014
10. VGluT1+ Neuronal Glutamatergic Signaling Regulates Postnatal Developmental Maturation of Cortical Protoplasmic Astroglia
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Lydie Morel, Michaela Tolman, Haruki Higashimori, and Yongjie Yang
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Receptor, Metabotropic Glutamate 5 ,Glutamic Acid ,Mice, Transgenic ,Biology ,Mice ,Glutamatergic ,medicine ,Animals ,Cerebral Cortex ,Neurons ,Developmental maturation ,Metabotropic glutamate receptor 5 ,General Neuroscience ,Glutamate receptor ,Excitatory Postsynaptic Potentials ,Articles ,Cell biology ,medicine.anatomical_structure ,nervous system ,Cerebral cortex ,Metabotropic glutamate receptor ,Astrocytes ,Synapses ,Vesicular Glutamate Transport Protein 1 ,Synaptic signaling ,Signal transduction ,Neuroscience ,Signal Transduction - Abstract
Functional maturation of astroglia is characterized by the development of a unique, ramified morphology and the induction of important functional proteins, such as glutamate transporter GLT1. Although pathways regulating the early fate specification of astroglia have been characterized, mechanisms regulating postnatal maturation of astroglia remain essentially unknown. Here we used a new in vivo approach to illustrate and quantitatively analyze developmental arborization of astroglial processes. Our analysis found a particularly high increase in the number of VGluT1(+) neuronal glutamatergic synapses that are ensheathed by processes from individual developing astroglia from postnatal day (P) 14 to P26, when astroglia undergo dramatic postnatal maturation. Subsequent silencing of VGluT1(+) synaptic activity in VGluT1 KO mice significantly reduces astroglial domain growth and the induction of GLT1 in the cortex, but has no effect on astroglia in the hypothalamus, where non-VGluT1(+) synaptic signaling predominates. In particular, electron microscopy analysis showed that the loss of VGluT1(+) synaptic signaling significantly decreases perisynaptic enshealthing of astroglial processes on synapses. To further determine whether synaptically released glutamate mediates VGluT1(+) synaptic signaling, we pharmacologically inhibited and genetically ablated metabotropic glutamate receptors (mGluRs, especially mGluR5) in developing cortical astroglia and found that developmental arborization of astroglial processes and expression of functional proteins, such as GLT1, is significantly decreased. In summary, our genetic analysis provides new in vivo evidence that VGluT1(+) glutamatergic signaling, mediated by the astroglial mGluR5 receptor, regulates the functional maturation of cortical astroglia during development. These results elucidate a new mechanism for regulating the developmental formation of functional neuron-glia synaptic units.
- Published
- 2014
11. Selective Deletion of Astroglial FMRP Dysregulates Glutamate Transporter GLT1 and Contributes to Fragile X Syndrome Phenotypes In Vivo
- Author
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Ming Sum R. Chiang, Temitope Shoneye, Haruki Higashimori, David L. Nelson, Yongjie Yang, Lydie Morel, and Christina Schin
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0301 basic medicine ,congenital, hereditary, and neonatal diseases and abnormalities ,Action Potentials ,Nerve Tissue Proteins ,Biology ,In Vitro Techniques ,Pathogenesis ,03 medical and health sciences ,Fragile X Mental Retardation Protein ,Mice ,Downregulation and upregulation ,medicine ,Animals ,Loss function ,Regulation of gene expression ,Cerebral Cortex ,General Neuroscience ,Pyramidal Cells ,Age Factors ,Estrogen Antagonists ,Articles ,medicine.disease ,FMR1 ,nervous system diseases ,Fragile X syndrome ,Mice, Inbred C57BL ,Disease Models, Animal ,Tamoxifen ,030104 developmental biology ,medicine.anatomical_structure ,Animals, Newborn ,Excitatory Amino Acid Transporter 2 ,Gene Expression Regulation ,Cerebral cortex ,Astrocytes ,Fragile X Syndrome ,Neuroscience ,Astrocyte ,Transcription Factors - Abstract
How the loss of fragile X mental retardation protein (FMRP) in different brain cell types, especially in non-neuron glial cells, induces fragile X syndrome (FXS) phenotypes has just begun to be understood. In the current study, we generated inducible astrocyte-specific Fmr1 conditional knock-out mice (i-astro- Fmr1 -cKO) and restoration mice (i-astro- Fmr1 -cON) to study the in vivo modulation of FXS synaptic phenotypes by astroglial FMRP. We found that functional expression of glutamate transporter GLT1 is 40% decreased in i-astro- Fmr1 -cKO somatosensory cortical astrocytes in vivo , which can be fully rescued by the selective re-expression of FMRP in astrocytes in i-astro- Fmr1 -cON mice. Although the selective loss of astroglial FMRP only modestly increases spine density and length in cortical pyramidal neurons, selective re-expression of FMRP in astrocytes significantly attenuates abnormal spine morphology in these neurons of i-astro- Fmr1 -cON mice. Moreover, we found that basal protein synthesis levels and immunoreactivity of phosphorylated S6 ribosomal protein (p-s6P) is significantly increased in i-astro- Fmr1 -cKO mice, while the enhanced cortical protein synthesis observed in Fmr1 KO mice is mitigated in i-astro- Fmr1 -cON mice. Furthermore, ceftriaxone-mediated upregulation of surface GLT1 expression restores functional glutamate uptake and attenuates enhanced neuronal excitability in Fmr1 KO mice. In particular, ceftriaxone significantly decreases the growth rate of abnormally accelerated body weight and completely corrects spine abnormality in Fmr1 KO mice. Together, these results show that the selective loss of astroglial FMRP contributes to cortical synaptic deficits in FXS, presumably through dysregulated astroglial glutamate transporter GLT1 and impaired glutamate uptake. These results suggest the involvement of astrocyte-mediated mechanisms in the pathogenesis of FXS. SIGNIFICANCE STATEMENT Previous studies to understand how the loss of function of fragile X mental retardation protein (FMRP) causes fragile X syndrome (FXS) have largely focused on neurons; whether the selective loss of astroglial FMRP in vivo alters astrocyte functions and contributes to the pathogenesis of FXS remain essentially unknown. This has become a long-standing unanswered question in the fragile X field, which is also relevant to autism pathogenesis. Our current study generated astrocyte-specific Fmr1 conditional knock-out and restoration mice, and provided compelling evidence that the selective loss of astroglial FMRP contributes to cortical synaptic deficits in FXS, likely through the dysregulated astroglial glutamate transporter GLT1 expression and impaired glutamate uptake. These results demonstrate previously undescribed astrocyte-mediated mechanisms in the pathogenesis of FXS.
- Published
- 2016
12. Inhibition of inducible nitric oxide synthase reduces an acute peripheral motor neuropathy produced by dermal burn injury in mice
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Thomas P. Whetzel, Richard C. Carlsen, and Haruki Higashimori
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medicine.medical_specialty ,Burn injury ,Neural Conduction ,Nitric Oxide Synthase Type II ,Mice, Transgenic ,Inflammation ,Nitric Oxide ,Nitric oxide ,Proinflammatory cytokine ,Mice ,chemistry.chemical_compound ,Internal medicine ,medicine ,Animals ,Enzyme Inhibitors ,Axon ,Nitrites ,Skin ,Motor Neurons ,biology ,business.industry ,General Neuroscience ,Peripheral Nervous System Diseases ,Mice, Inbred C57BL ,Nitric oxide synthase ,medicine.anatomical_structure ,Endocrinology ,chemistry ,Anesthesia ,Knockout mouse ,biology.protein ,Female ,Neurology (clinical) ,Tibial Nerve ,medicine.symptom ,Burns ,business ,Peripheral Motor Neuropathy - Abstract
The systemic inflammatory response produced by a full-thickness dermal burn injury is associated with a peripheral motor neuropathy. We previously reported that a 20% body surface area (BSA) full-thickness dermal burn in C57BL6 mice produced structural and functional deficits in motor axons at a distance from the burn site. The etiology of the neuropathy, however, is not well characterized. Burn injury leads to an increase in production of a number of proinflammatory mediators, including nitric oxide (NO). We tested the hypothesis that dermal burn-induced motor neuropathy is mediated by increased production of NO. NO synthase (NOS) activity was inhibited following a 20% BSA full-thickness burn by injection of non-specific NOS inhibitor, nitro-L-arginine methyl ester or inducible NOS (iNOS) inhibitors, L-N6-(1-iminoethyl) lysine, and aminoguanidine. NOS inhibitors also prevented the reduction in ventral roots mean axon caliber and the decrease in a motor nerve conduction velocity (MCV) following burn. iNOS knockout mice prevented MCV decrease in the first 3 days post-burn, but iNOS knockout MCV was significantly reduced at 7-14 days post-burn. These results suggest that an increase in NO production generated by systemic inflammatory response pathways after burn injury contributes to the development of structural and functional deficits in peripheral motor axons.
- Published
- 2008
13. Early Excision of a Full-Thickness Burn Prevents Peripheral Nerve Conduction Deficits in Mice
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Richard C. Carlsen, Thomas P. Whetzel, and Haruki Higashimori
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Burn injury ,Time Factors ,Body Surface Area ,Neutrophils ,Neural Conduction ,Sensory system ,Nitric Oxide ,Nerve conduction velocity ,Nitric oxide ,H-Reflex ,Leukocyte Count ,Mice ,chemistry.chemical_compound ,Animals ,Medicine ,Body surface area ,Tumor Necrosis Factor-alpha ,business.industry ,Peripheral ,Mice, Inbred C57BL ,medicine.anatomical_structure ,chemistry ,Anesthesia ,Potassium ,Female ,Surgery ,Tibial Nerve ,Burns ,business ,Sensory nerve - Abstract
Background A full-thickness 20 percent body surface area burn in mice produces a significant decrease in tibial motor nerve conduction velocity within 6 hours of the burn and in sensory conduction velocity within 7 days. This suggests that cutaneous burn injury produces a systemic response that affects peripheral motor and sensory nerve function at a distance from the burn site. The authors tested the hypothesis that burn wound excision either 30 minutes or 3 hours after burn would prevent neuropathy. Methods A 20 percent body surface area third-degree burn was applied to the backs of anesthetized mice using procedures that followed National Institutes of Health guidelines. Motor nerve conduction velocity and sensory conduction velocity were determined in intact, anesthetized mice by percutaneous nerve stimulation. Burn wounds were excised and closed at 30 minutes or 3 hours after burn. Motor nerve conduction velocity and sensory conduction velocity were measured before burn and 1, 3, 7, 14, and 21 days after a burn or sham procedure. The number of circulating neutrophils and serum concentrations of tumor necrosis factor-alpha, nitrite, and electrolytes were also determined in each group. Results Motor nerve conduction velocity and sensory conduction velocity in the 30-minute excision (n = 10) and sham group (n = 5) were not significantly different. Motor nerve conduction velocity and sensory conduction velocity in the nonexcised group (n = 10) and 3-hour excision group (n = 10) were significantly decreased. Serum tumor necrosis factor-alpha concentration was elevated 6 hours after burn in nonexcised animals (n = 9) and in 3-hour excision mice (n = 8) but was not significantly different in the sham (n = 8) and the 30-minute excision group (n = 7). Conclusion The authors conclude that burn wound excision at 30 minutes but not at 3 hours prevents the nerve conduction deficits measured in mice with 20 percent body surface area burns. The cellular basis of burn-induced neuropathy is unknown, but nitric oxide and tumor necrosis factor alpha-alpha appear to play a role.
- Published
- 2006
14. Long-term depression induced by endogenous cannabinoids produces neuroprotection via astroglial CB1R after stroke in rodents.
- Author
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Feng Wang, Jing Han, Haruki Higashimori, Jingyi Wang, Jingjing Liu, Li Tong, Yongjie Yang, Hailong Dong, Xia Zhang, and Lize Xiong
- Abstract
Ischemia not only activates cell death pathways but also triggers endogenous protective mechanisms. However, it is largely unknown what is the essence of the endogenous neuroprotective mechanisms induced by preconditioning. In this study we demonstrated that systemic injection of JZL195, a selective inhibitor of eCB clearance enzymes, induces in vivo long-term depression at CA3-CA1 synapses and at PrL-NAc synapses produces neuroprotection. JZL195-elicited long-term depression is blocked by AM281, the antagonist of cannabinoid 1 receptor (CB
1 R) and is abolished in mice lacking cannabinoid CB1 receptor (CB1 R) in astroglial cells, but is conserved in mice lacking CB1 R in glutamatergic or GABAergic neurons. Blocking the glutamate NMDA receptor and the synaptic trafficking of glutamate AMPA receptor abolishes both long-term depression and neuroprotection induced by JZL195. Mice lacking CB1 R in astroglia show decreased neuronal death following cerebral ischemia. Thus, an acute elevation of extracellular eCB following eCB clearance inhibition results in neuroprotection through long-term depression induction after sequential activation of astroglial CB1 R and postsynaptic glutamate receptors. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
15. [Untitled]
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Norman C. Staub, Neal Fleming, E. H. Jerome, Vladimir B. Serikov, T. V. Glazanova, and Haruki Higashimori
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business.industry ,Phagocytosis ,CD14 ,Immunology ,Peritonitis ,Pharmacology ,medicine.disease ,In vitro ,Sepsis ,medicine ,Immunology and Allergy ,Macrophage ,Receptor ,business ,Tyloxapol ,medicine.drug - Abstract
We have previously demonstrated that the detergent Tyloxapol is effective in preventing reactions to endotoxin. We studied the effects of Tyloxapol on the morbidity and mortality from endotoxemia in rabbits and on the mortality in rats with sepsis. The effects of Tyloxapol on endotoxin binding and macrophage activation were studied in the macrophage cell line RAW264.7 and CHO cells expressing CD14. Isolated human leukocytes were used to study the effects of Tyloxapol on immune reactions, leukocyte motility, and phagocytosis. Intravenous Tyloxapol (200 mg/kg), given prior to or at the time of endotoxin infusion protected rabbits from developing shock. In rats with peritoneal sepsis, a lipid-rich diet and Tyloxapol given at the time of induction of peritonitis protected them from septic death. In vitro, Tyloxapol blocked the binding of endotoxin to murine macrophages and CHO cells expressing CD14, activation of macrophages, and also some antigen–antibody immune reactions (mediated by CD2, CD4, CD22, HLA-DR). Tyloxapol may prevent the reaction to endotoxin by desensitizing endotoxin-recognizing receptors.
- Published
- 2003
16. Abnormal Intracellular Calcium Signaling and SNARE-Dependent Exocytosis Contributes to SOD1G93A Astrocyte-Mediated Toxicity in Amyotrophic Lateral Sclerosis
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Philip G. Haydon, Giovanni Manfredi, Lydie Morel, Hibiki Kawamata, Natalia Diaz, Alexandra Osgood, Haruki Higashimori, Seng Kah Ng, Brittany Sider, Suzanne R. Burstein, and Yongjie Yang
- Subjects
Male ,chemistry.chemical_element ,Calcium ,Biology ,Calcium in biology ,Exocytosis ,Mice ,medicine ,Animals ,Calcium Signaling ,Cells, Cultured ,Calcium signaling ,Motor Neurons ,Superoxide Dismutase ,General Neuroscience ,Purinergic receptor ,Amyotrophic Lateral Sclerosis ,Articles ,Motor neuron ,Coculture Techniques ,Cell biology ,medicine.anatomical_structure ,chemistry ,Astrocytes ,Female ,SNARE Proteins ,Homeostasis ,Astrocyte - Abstract
Motor neurons are progressively and predominantly degenerated in ALS, which is not only induced by multiple intrinsic pathways but also significantly influenced by the neighboring glial cells. In particular, astrocytes derived from the SOD1 mutant mouse model of ALS or from human familial or sporadic ALS patient brain tissue directly induce motor neuron death in culture; however, the mechanisms of pathological astroglial secretion remain unclear. Here we investigated abnormal calcium homeostasis and altered exocytosis in SOD1G93A astrocytes. We found that purinergic stimulation induces excess calcium release from the ER stores in SOD1G93A astrocytes, which results from the abnormal ER calcium accumulation and is independent of clearance mechanisms. Furthermore, pharmacological studies suggested that store-operated calcium entry (SOCE), a calcium refilling mechanism responsive to ER calcium depletion, is enhanced in SOD1G93A astrocytes. We found that oxidant-induced increased S-glutathionylation and calcium-independent puncta formation of the ER calcium sensor STIM1 underlies the abnormal SOCE response in SOD1G93A astrocytes. Enhanced SOCE contributes to ER calcium overload in SOD1G93A astrocytes and excess calcium release from the ER during ATP stimulation. In addition, ER calcium release induces elevated ATP release from SOD1G93A astrocytes, which can be inhibited by the overexpression of dominant-negative SNARE. Selective inhibition of exocytosis in SOD1G93A astrocytes significantly prevents astrocyte-mediated toxicity to motor neurons and delays disease onset in SOD1G93A mice. Our results characterize a novel mechanism responsible for calcium dysregulation in SOD1G93A astrocytes and provide the firstin vivoevidence that astrocyte exocytosis contributes to the pathogenesis of ALS.
- Published
- 2014
17. Developmental maturation of astrocytes and pathogenesis of neurodevelopmental disorders
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Lydie Morel, Haruki Higashimori, and Yongjie Yang
- Subjects
medicine.medical_specialty ,Neurology ,Cognitive Neuroscience ,Developmental disorder ,Review ,Biology ,Pathology and Forensic Medicine ,Pathogenesis ,Glutamate homeostasis ,medicine ,Developmental maturation ,Glutamate receptor ,medicine.disease ,Human genetics ,medicine.anatomical_structure ,Pediatrics, Perinatology and Child Health ,GLT1 ,Neurology (clinical) ,Glutamate ,Glutamate transporter ,Astrocyte ,Neuronal to astrocyte signaling ,Neuroscience - Abstract
Recent studies have implicated potentially significant roles for astrocytes in the pathogenesis of neurodevelopmental disorders. Astrocytes undergo a dramatic maturation process following early differentiation from which typical morphology and important functions are acquired. Despite significant progress in understanding their early differentiation, very little is known about how astrocytes become functionally mature. In addition, whether functional maturation of astrocytes is disrupted in neurodevelopmental disorders and the consequences of this disruption remains essentially unknown. In this review, we discuss our perspectives about how astrocyte developmental maturation is regulated, and how disruption of the astrocyte functional maturation process, especially alterations in their ability to regulate glutamate homeostasis, may alter synaptic physiology and contribute to the pathogenesis of neurodevelopmental disorders.
- Published
- 2013
18. Astroglial FMRP-dependent translational down-regulation of mGluR5 underlies glutamate transporter GLT1 dysregulation in the fragile X mouse
- Author
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James Huth, Yongjie Yang, Haruki Higashimori, Michael M Freeman, Amaro Taylor, Chris G. Dulla, Lothar Lindemann, and Lydie Morel
- Subjects
Kainic acid ,congenital, hereditary, and neonatal diseases and abnormalities ,Receptor, Metabotropic Glutamate 5 ,Down-Regulation ,Glutamic Acid ,Biology ,Receptors, Metabotropic Glutamate ,chemistry.chemical_compound ,Fragile X Mental Retardation Protein ,Mice ,Genetics ,medicine ,Animals ,Humans ,Molecular Biology ,Genetics (clinical) ,Cerebral Cortex ,Neurons ,Kainic Acid ,Metabotropic glutamate receptor 5 ,Glutamate receptor ,General Medicine ,Glutamic acid ,Articles ,FMR1 ,Molecular biology ,nervous system diseases ,medicine.anatomical_structure ,chemistry ,Excitatory Amino Acid Transporter 2 ,Astrocytes ,Fragile X Syndrome ,Gene Knockdown Techniques ,Protein Biosynthesis ,Synaptic plasticity ,Metabotropic glutamate receptor 1 ,Astrocyte - Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by the loss-of-function of fragile X mental retardation protein (FMRP). The loss of FMRP function in neurons abolishes its suppression on mGluR1/5-dependent dendritic protein translation, enhancing mGluR1/5-dependent synaptic plasticity and other disease phenotypes in FXS. In this study, we describe a new activation function of FMRP in regulating protein expression in astroglial cells. We found that astroglial glutamate transporter subtype glutamate transporter 1 (GLT1) and glutamate uptake is significantly reduced in the cortex of fmr1(-/-) mice. Correspondingly, neuronal excitability is also enhanced in acute fmr1(-/-) (but not in fmr1(+/+) control) cortical slices treated with low doses (10 μm) of the GLT1-specific inhibitor dihydrokainate (DHK). Using mismatched astrocyte and neuron co-cultures, we demonstrate that the loss of astroglial (but not neuronal) FMRP particularly reduces neuron-dependent GLT1 expression and glutamate uptake in co-cultures. Interestingly, protein (but not mRNA) expression and the (S)-3,5-dihydroxyphenylglycine-dependent Ca(2+) responses of astroglial mGluR5 receptor are also selectively reduced in fmr1(-/-) astrocytes and brain slices, attenuating neuron-dependent GLT1 expression. Subsequent FMRP immunoprecipitation and QRT-PCR analysis showed that astroglial mGluR5 (but not GLT1) mRNA is associated with FMRP. In summary, our results provide evidence that FMRP positively regulates translational expression of mGluR5 in astroglial cells, and FMRP-dependent down-regulation of mGluR5 underlies GLT1 dysregulation in fmr1(-/-) astrocytes. The dysregulation of GLT1 and reduced glutamate uptake may potentially contribute to enhanced neuronal excitability observed in the mouse model of FXS.
- Published
- 2013
19. Neuronal exosomal miRNA-dependent translational regulation of astroglial glutamate transporter GLT1
- Author
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Yongjie Yang, Lydie Morel, Seng Kah Ng, Jeffrey D. Rothstein, Melissa R. Regan, Svetlana Vidensky, Christine Esau, and Haruki Higashimori
- Subjects
Immunoblotting ,Mice, Transgenic ,Biology ,Exosomes ,Biochemistry ,Mice ,Glutamates ,Neurobiology ,microRNA ,Translational regulation ,medicine ,Animals ,Humans ,Molecular Biology ,Cells, Cultured ,Regulation of gene expression ,Mice, Knockout ,Neurons ,Messenger RNA ,Superoxide Dismutase ,Amyotrophic Lateral Sclerosis ,Glutamate receptor ,Cell Biology ,Molecular biology ,Microvesicles ,Corpus Striatum ,Endocytosis ,MicroRNAs ,Microscopy, Electron ,medicine.anatomical_structure ,HEK293 Cells ,nervous system ,Excitatory Amino Acid Transporter 2 ,Gene Expression Regulation ,Spinal Cord ,Astrocytes ,Gene Knockdown Techniques ,Protein Biosynthesis ,Signal transduction ,Astrocyte ,Signal Transduction - Abstract
Perisynaptic astrocytes express important glutamate transporters, especially excitatory amino acid transporter 2 (EAAT2, rodent analog GLT1) to regulate extracellular glutamate levels and modulate synaptic activation. In this study, we investigated an exciting new pathway, the exosome-mediated transfer of microRNA (in particular, miR-124a), in neuron-to-astrocyte signaling. Exosomes isolated from neuron-conditioned medium contain abundant microRNAs and small RNAs. These exosomes can be directly internalized into astrocytes and increase astrocyte miR-124a and GLT1 protein levels. Direct miR-124a transfection also significantly and selectively increases protein (but not mRNA) expression levels of GLT1 in cultured astrocytes. Consistent with our in vitro findings, intrastriatal injection of specific antisense against miR-124a into adult mice dramatically reduces GLT1 protein expression and glutamate uptake levels in striatum without reducing GLT1 mRNA levels. MiR-124a-mediated regulation of GLT1 expression appears to be indirect and is not mediated by its suppression of the putative GLT1 inhibitory ligand ephrinA3. Moreover, miR-124a is selectively reduced in the spinal cord tissue of end-stage SOD1 G93A mice, the mouse model of ALS. Subsequent exogenous delivery of miR-124a in vivo through stereotaxic injection significantly prevents further pathological loss of GLT1 proteins, as determined by GLT1 immunoreactivity in SOD1 G93A mice. Together, our study characterized a new neuron-to-astrocyte communication pathway and identified miRNAs that modulate GLT1 protein expression in astrocytes in vitro and in vivo.
- Published
- 2013
20. Imaging analysis of neuron to glia interaction in microfluidic culture platform (MCP)-based neuronal axon and glia co-culture system
- Author
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Haruki Higashimori and Yongjie Yang
- Subjects
Transcriptional Activation ,General Chemical Engineering ,Central nervous system ,Green Fluorescent Proteins ,Dendrite ,Mice, Transgenic ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Mice ,medicine ,Animals ,Axon ,Promoter Regions, Genetic ,Cerebral Cortex ,Neurons ,General Immunology and Microbiology ,General Neuroscience ,Microfluidic Analytical Techniques ,Axons ,Coculture Techniques ,Cell biology ,medicine.anatomical_structure ,nervous system ,Excitatory Amino Acid Transporter 2 ,Cell culture ,Cerebral cortex ,Astrocytes ,Neuroglia ,Soma ,Neuron ,Neuroscience - Abstract
Proper neuron to glia interaction is critical to physiological function of the central nervous system (CNS). This bidirectional communication is sophisticatedly mediated by specific signaling pathways between neuron and glia(1,2) . Identification and characterization of these signaling pathways is essential to the understanding of how neuron to glia interaction shapes CNS physiology. Previously, neuron and glia mixed cultures have been widely utilized for testing and characterizing signaling pathways between neuron and glia. What we have learned from these preparations and other in vivo tools, however, has suggested that mutual signaling between neuron and glia often occurred in specific compartments within neurons (i.e., axon, dendrite, or soma)(3). This makes it important to develop a new culture system that allows separation of neuronal compartments and specifically examines the interaction between glia and neuronal axons/dendrites. In addition, the conventional mixed culture system is not capable of differentiating the soluble factors and direct membrane contact signals between neuron and glia. Furthermore, the large quantity of neurons and glial cells in the conventional co-culture system lacks the resolution necessary to observe the interaction between a single axon and a glial cell. In this study, we describe a novel axon and glia co-culture system with the use of a microfluidic culture platform (MCP). In this co-culture system, neurons and glial cells are cultured in two separate chambers that are connected through multiple central channels. In this microfluidic culture platform, only neuronal processes (especially axons) can enter the glial side through the central channels. In combination with powerful fluorescent protein labeling, this system allows direct examination of signaling pathways between axonal/dendritic and glial interactions, such as axon-mediated transcriptional regulation in glia, glia-mediated receptor trafficking in neuronal terminals, and glia-mediated axon growth. The narrow diameter of the chamber also significantly prohibits the flow of the neuron-enriched medium into the glial chamber, facilitating probing of the direct membrane-protein interaction between axons/dendrites and glial surfaces.
- Published
- 2012
21. Role of epoxyeicosatrienoic acids as autocrine metabolites in glutamate-mediated K+ signaling in perivascular astrocytes
- Author
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Vengopal Raju Tuniki, Jessica A. Filosa, John R. Falck, Haruki Higashimori, and Víctor M. Blanco
- Subjects
Vascular smooth muscle ,Patch-Clamp Techniques ,Potassium Channels ,Physiology ,Glutamic Acid ,chemistry.chemical_compound ,Vascular Biology ,Eicosanoic Acids ,medicine ,Animals ,Patch clamp ,Rats, Wistar ,Neurotransmitter ,Autocrine signalling ,Cytochrome P450 Family 2 ,Chemistry ,Glutamate receptor ,Cell Biology ,Amides ,Rats ,Autocrine Communication ,medicine.anatomical_structure ,Biochemistry ,Steroid 16-alpha-Hydroxylase ,Astrocytes ,Neuroglia ,Pyrazoles ,Calcium ,Aryl Hydrocarbon Hydroxylases ,Signal transduction ,Astrocyte ,Signal Transduction - Abstract
Epoxyeicosatrienoic acids (EETs), synthesized and released by astrocytes in response to glutamate, are known to play a pivotal role in neurovascular coupling. In vascular smooth muscle cells (VSMC), EETs activate large-conductance, Ca2+-activated K+(BK) channels resulting in hyperpolarization and vasodilation. However, the functional role and mechanism of action for glial-derived EETs are still to be determined. In this study, we evaluated the effect of the synthetic EET analog 11-nonyloxy-undec-8(Z)-enoic acid (NUD-GA) on outward K+currents mediated by calcium-activated K+channels. Addition of NUD-GA significantly increased intracellular Ca2+and outward K+currents in perivascular astrocytes. NUD-GA-induced currents were significantly inhibited by BK channel blockers paxilline and tetraethylammonium (TEA) (23.4 ± 2.4%; P < 0.0005). Similarly, NUD-GA-induced currents were also significantly inhibited in the presence of the small-conductance Ca2+-activated K+channel inhibitor apamin along with a combination of blockers against glutamate receptors (12.8 ± 2.70%; P < 0.05). No changes in outward currents were observed in the presence of the channel blocker for intermediate-conductance K+channels TRAM-34. Blockade of the endogenous production of EETs with N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide (MS-PPOH) significantly blunted ( dl)-1-aminocyclopentane-trans-1,3-dicarboxylic acid ( t-ACPD)-induced outward K+currents ( P < 0.05; n = 6). Both NUD-GA and t-ACPD significantly increased BK channel single open probability; the later was blocked following MS-PPOH incubation. Our data supports the idea that EETs are potent K+channel modulators in cortical perivascular astrocytes and further suggest that these metabolites may participate in NVC by modulating the levels of K+released at the gliovascular space.
- Published
- 2010
22. Bi‐directional neurovascular communication in the brain
- Author
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Víctor M. Blanco, Haruki Higashimori, and Jessica A. Filosa
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business.industry ,Genetics ,Medicine ,business ,Neurovascular bundle ,Molecular Biology ,Biochemistry ,Neuroscience ,Biotechnology - Published
- 2009
23. Role of Kir4.1 channels in growth control of glia
- Author
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Harald Sontheimer and Haruki Higashimori
- Subjects
G2 Phase ,Cellular differentiation ,Biology ,Resting Phase, Cell Cycle ,Article ,Cell membrane ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,Astrocyte differentiation ,Mice ,Cell Line, Tumor ,medicine ,Animals ,Tissue Distribution ,Potassium Channels, Inwardly Rectifying ,Cells, Cultured ,Cell Proliferation ,Membrane potential ,Cell growth ,Cell Membrane ,Electric Conductivity ,G1 Phase ,Gene Transfer Techniques ,Cell Differentiation ,Membrane hyperpolarization ,Glioma ,Resting potential ,Potassium channel ,Cell biology ,Rats ,medicine.anatomical_structure ,Neurology ,Astrocytes ,Neuroglia ,Cell Division - Abstract
The inwardly rectifying potassium channel Kir4.1 is widely expressed by astrocytes throughout the brain. Kir4.1 channels are absent in immature, proliferating glial cells. The progressive expression of Kir4.1 correlates with astrocyte differentiation and is characterized by the establishment of a negative membrane potential (> -70 mV) and an exit from the cell cycle. Despite some correlative evidence, a mechanistic interdependence between Kir4.1 expression, membrane hyperpolarization, and control of cell proliferation has not been demonstrated. To address this question, we used astrocyte-derived tumors (glioma) that lack functional Kir4.1 channels, and generated two glioma cell lines that stably express either AcGFP-tagged Kir4.1 channels or AcGFP vectors only. Kir4.1 expression confers the same K+ conductance to glioma membranes and a similar responsiveness to changes in [K+]o that characterizes differentiated astrocytes. Kir4.1 expression was sufficient to move the resting potential of gliomas from -50 to -80 mV. Importantly, Kir4.1 expression impaired cell growth by shifting a significant number of cells from the G2/M phase into the quiescent G0/G1 stage of the cell cycle. Furthermore, these effects could be nullified entirely if Kir4.1 channels were either pharmacologically inhibited by 100 microM BaCl2 or if cells were chronically depolarized by 20 mM KCl to the membrane voltage of growth competent glioma cells. These studies therefore demonstrate directly that Kir4.1 causes a membrane hyperpolarization that is sufficient to account for the growth attenuation, which in turn induces cell maturation characterized by a shift of the cells from G2/M into G0/G1.
- Published
- 2007
24. Molecular and Functional Properties of Regional Astrocytes in the Adult Brain.
- Author
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Morel, Lydie, Chiang, Ming Sum R., Haruki Higashimori, Shoneye, Temitope, Iyer, Lakshmanan K., Yelick, Julia, Tai, Albert, and Yongjie Yang
- Subjects
ASTROCYTES ,CENTRAL nervous system ,RIBOSOMES ,RNA sequencing ,MESSENGER RNA ,CEREBRAL cortex ,HIPPOCAMPUS (Brain) - Abstract
The molecular signature and functional properties of astroglial subtypes in the adult CNS remain largely undefined. By using translational ribosome affinity purification followed by RNA-Seq, we profiled astroglial ribosome-associated (presumably translating) mRNAs in major cortical and subcortical brain regions (cortex, hippocampus, caudate-putamen, nucleus accumbens, thalamus, and hypothalamus) of BACfl/d/tf/l-translational ribosome affinity purification (TRAP) mice (both sexes). We found that the expression of astroglial translating mRNAs closely follows the dorsoventral axis, especially from cortex/hippocampus to thalamus/hypothalamus posteriorly. This region-specific expression pattern of genes, such as synaptogenic modulator spare and transcriptional factors (emx2, lhx2, and hopx), was validated by qRT-PCR and immunostaining in brain sections. Interestingly, cortical or subcortical astrocytes selectively promote neurite growth and synaptic activity of neurons only from the same region in mismatched cocultures, exhibiting regionmatched astrocyte to neuron communication. Overall, these results generated new molecular signature of astrocyte types in the adult CNS, providing insights into their origin and functional diversity. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
25. Peripheral axon caliber and conduction velocity are decreased after burn injury in mice
- Author
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Thomas P. Whetzel, Tamara Mahmood, Richard C. Carlsen, and Haruki Higashimori
- Subjects
Burn injury ,Physiology ,Neuromuscular transmission ,Neural Conduction ,Nerve conduction velocity ,H-Reflex ,Cellular and Molecular Neuroscience ,Mice ,Physiology (medical) ,Respiratory muscle ,Medicine ,Animals ,Neurons, Afferent ,Axon ,Tibial nerve ,Cell Size ,Motor Neurons ,business.industry ,Peripheral Nervous System Diseases ,Anatomy ,Dermis ,medicine.disease ,Axons ,Electric Stimulation ,Mice, Inbred C57BL ,Disease Models, Animal ,medicine.anatomical_structure ,Peripheral neuropathy ,Female ,Neurology (clinical) ,Tibial Nerve ,business ,Burns ,Wallerian Degeneration ,Sensory nerve - Abstract
Peripheral neuropathies are reported to arise as a result of the systemic inflammatory response produced by a full-thickness cutaneous burn injury. This study was designed to characterize the magnitude and time course of functional and morphological changes in peripheral axons that arise after a full-thickness dermal burn injury in an animal model. A 20% body surface area (20% BSA) full-thickness dermal burn was applied to the back of C57BL6 female mice. Longitudinal H- and M-wave recordings were used to determine the conduction velocities (CV) of large myelinated motor and sensory axons in the tibial nerve of sham control and burn-injured mice. Motor CVs were significantly reduced from 6 h to 28 days after the burn, and sensory CVs were significantly reduced from 7 to 14 days after the burn. Morphological evaluation also showed that the mean caliber of large axons in tibial nerves and L5 ventral and dorsal roots in burned mice was significantly decreased. The results demonstrate that both functional and morphological deficits may be produced in peripheral nerve axons at sites well removed from a full-thickness dermal burn injury. The neural deficits may contribute to changes in neuromuscular transmission and the development of limb and respiratory muscle weakness that also accompany burn injury.
- Published
- 2005
26. Selective Deletion of Astroglial FMRP Dysregulates Glutamate Transporter GLT1 and Contributes to Fragile X Syndrome Phenotypes In Vivo.
- Author
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Haruki Higashimori, Schin, Christina S., Ming Sum R. Chiang, Morel, Lydie, Shoneye, Temitope A., Nelson, David L., and Yongjie Yang
- Subjects
- *
ASTROCYTES , *AUTISM research , *GLUTAMATE transporters , *CARRIER proteins , *PROTEIN synthesis - Abstract
How the loss of fragile X mental retardation protein (FMRP) in different brain cell types, especially in non-neuron glial cells, induces fragile X syndrome (FXS) phenotypes has just begun to be understood. In the current study, we generated inducible astrocyte-specific Fmrl conditional knock-out mice (i-astro-Fmrl-cKO) and restoration mice (i-astro-Fmrl-cON) to study the in vivo modulation of FXS synaptic phenotypes by astroglial FMRP. We found that functional expression of glutamate transporter GLT1 is 40% decreased in i-astro-FmrJ-cKO somatosensory cortical astrocytes in vivo, which can be fully rescued by the selective re-expression of FMRP in astrocytes in i-astro-Fmrl-cON mice. Although the selective loss of astroglial FMRP only modestly increases spine density and length in cortical pyramidal neurons, selective re-expression of FMRP in astrocytes significantly attenuates abnormal spine morphology in these neurons of i-astro-Fmri-cON mice. Moreover, we found that basal protein synthesis levels and immunoreactivity of phosphorylated S6 ribosomal protein (p-s6P) is significantly increased in i-astro-Fmri-cKO mice, while the enhanced cortical protein synthesis observed in Fmrl KO mice is mitigated in i-astro-Fmr/-cON mice. Furthermore, ceftriaxone-mediated upregulation of surface GLT1 expression restores functional glutamate uptake and attenuates enhanced neuronal excitability in Fmrl KO mice. In particular, ceftriaxone significantly decreases the growth rate of abnormally accelerated body weight and completely corrects spine abnormality in Fmrl KO mice. Together, these results show that the selective loss of astroglial FMRP contributes to cortical synaptic deficits in FXS, presumably through dysregulated astroglial glutamate transporter GLT1 and impaired glutamate uptake. These results suggest the involvement of astrocyte-mediated mechanisms in the pathogenesis of FXS. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
27. Early Excision of a Full-Thickness Burn Prevents Peripheral Nerve Conduction Deficits in Mice.
- Author
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Haruki Higashimori, Richard C Carlsen, and Thomas P Whetzel
- Published
- 2006
- Full Text
- View/download PDF
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