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Synaptic dysfunction is widely thought to play a key role in the pathogenesis of Alzheimer's disease (AD). Presenilins, the major gene products involved in familial AD, are essential for short- and long-term synaptic plasticity in mature neurons as well as for the survival of cortical neurons during aging. Presenilin and nicastrin are both indispensable components of the γ-secretase complex, but it remains unknown whether presenilin regulates synaptic function in a γ-secretase-dependent or γ-secretase-independent manner and whether nicastrin plays similar roles in central synapses. In the current study, we address these questions using an electrophysiological approach to analyze nicastrin conditional knockout (cKO) mice in the hippocampal Schaffer collateral pathway. In these mice, we found that, even at 2 mo of age, deletion of nicastrin in excitatory neurons of the postnatal forebrain using Cre recombinase expressed under the control of the αCaMKII promoter led to deficits in presynaptic short-term plasticity including paired-pulse facilitation and frequency facilitation. Depletion of Ca2+ in the endoplasmic reticulum mimics and occludes the presynaptic facilitation deficits in nicastrin cKO mice, suggesting that disrupted intracellular Ca2+ homeostasis underlies the presynaptic deficits. In addition, NMDA receptor-mediated responses and long-term potentiation induced by theta-burst stimulation were decreased in nicastrin cKO mice at 3 mo but not at 2 mo of age. Together, these findings show that, similar to presenilins, nicastrin plays essential roles in the regulation of short- and longterm synaptic plasticity, highlighting the importance of γ-secretase in the function of mature synapses. [ABSTRACT FROM AUTHOR]

Context: Various Ocimum species (Labiateae) are commonly used for the treatment of inflammation, stress, diarrhea, and as an antioxidant drug in the Indian ethnic system of medicine. Objective: The present study was carried out to investigate the antimelanoma and radioprotective activity of different species of Ocimum in C57BL and Swiss albino mice. Materials and methods: The antimelanoma activity of 50% alcoholic aqueous leaf extract of five species of Ocimum [ Ocimum sanctum (SE), Ocimum gratissimum (GE), Ocimum basilicum (BE), Ocimum canum (CE), and Ocimum kilimandscharicum (KE)] alone or in combination with radiotherapy was determined on the basis of tumor volume, body weight, and survival rate of animals. The radioprotective potential of different species of Ocimum was determined by chromosomal aberration assay. The effect of the alcoholic aqueous extract of different species of Ocimum was also evaluated for the estimation of glutathione level and glutathione S-transferase activity in Swiss albino mice. Results: The 50% alcoholic aqueous extract of different species of Ocimum administered orally (200 mg/kg, p.o.) resulted in significant reduction in tumor volume, increase in average body weight, and survival rate of mice. The various extracts showed modulatory influence against lethal irradiation doses of gamma radiation in terms of radiation-induced chromosomal damage, while at the same time induced an increase in reduced glutathione level and GST activity. Discussion and conclusion: These findings demonstrate that Ocimum species have antimelanoma and radioprotective activity against B16F10 metastatic melanoma cell line-induced metastasis and could be exploited as one of the potential sources for plant-based pharmaceutical products. [ABSTRACT FROM AUTHOR]

A neuron forms thousands of presynaptic nerve terminals on its axons, far removed from the cell body. The protein CSPα resides in presynaptic terminals, where it forms a chaperone complex with Hsc70 and SGT. Deletion of CSPα results in massive neurodegeneration that impairs survival in mice and flies. In CSPα-knockout mice, levels of presynaptic SNARE complexes and the SNARE protein SNAP-25 are reduced, suggesting that CSPα may chaperone SNARE proteins, which catalyse synaptic vesicle fusion. Here, we show that the CSPα-Hsc70-SGT complex binds directly to monomeric SNAP-25 to prevent its aggregation, enabling SNARE-complex formation. Deletion of CSPα produces an abnormal SNAP-25 conformer that inhibits SNARE-complex formation, and is subject to ubiquitylation and proteasomal degradation. Even in wild-type mouse terminals, SNAP-25 degradation is regulated by synaptic activity; this degradation is decreased by CSPα overexpression, and enhanced by CSPα deletion. Thus, SNAP-25 function is maintained during rapid SNARE cycles by equilibrium between CSPα-dependent chaperoning and ubiquitin-dependent degradation, revealing unique protein quality-control machinery within the presynaptic compartment. [ABSTRACT FROM AUTHOR]

Presynaptic nerve terminals release neurotransmitters repeatedly, often at high frequency, and in relative isolation from neuronal cell bodies. Repeated release requires cycles of soluble N-ethylmaleimide--sensitive factor attachment protein receptor (SNARE)--complex assembly and disassembly, with continuous generation of reactive SNARE-protein intermediates. Although many forms of neurodegeneration initiate presynaptically, only few pathogenic mechanisms are known, and the functions of presynaptic proteins linked to neurodegeneration, such as α-synuclein, remain unclear. Here, we show that maintenance of continuous presynaptic SNARE-complex assembly required a nonclassical chaperone activity mediated by synucleins. Specifically, α-synuclein directly bound to the SNARE-protein synaptobrevin-2/vesicle-associated membrane protein 2 (VAMP2) and promoted SNARE-complex assembly. Moreover, triple-knockout mice lacking synucleins developed age-dependent neurological impairments, exhibited decreased SNARE-complex assembly, and died prematurely. Thus, synucleins may function to sustain normal SNARE-complex assembly in a presynaptic terminal during aging. [ABSTRACT FROM AUTHOR]

Arising from T. Bartels, J. G. Choi & D. J. Selkoe. 477, 107-110 (2011).α-Synuclein is an abundant presynaptic protein that binds to negatively charged phospholipids, functions as a SNARE-complex chaperone and contributes to Parkinson's disease pathogenesis. Recombinant α-synuclein in solution is largely unfolded and devoid of tertiary structure, but Bartels et al. have proposed that native α-synuclein purified from human erythrocytes forms a stably folded, soluble tetramer that resists aggregation. By contrast, we show here that native α-synuclein purified from mouse brain consists of a largely unstructured monomer, exhibits no stable tetramer formation, and is prone to aggregation. The native state of α-synuclein is important for understanding its pathological effects as a stably folded protein would be much less prone to aggregation than a conformationally labile protein. There is a Reply to this Brief Communication Arising by Bartels, T. & Selkoe, D. J. Nature 498, http://dx.doi.org/10.1038/nature12126 (2013). [ABSTRACT FROM AUTHOR]

The article offers the author's insights on the study of Sasidran and colleagues regarding the hepatoprotective effects of lantadene A against acetaminophen-induced active pharmaceutical ingredient damage in mice. The author says that high performance liquid chromatography (HPLC) purity data of the lantadene A must be included in the research. The author adds that the use of the active pharmaceutical ingredient (API) is recommended for animal studies rather than using of marketed tablets.

The objective of this study was to evaluate the cytotoxicity of (+)-cyanidan-3-ol (CD-3) in human hepatocellular carcinoma cell line (HepG2) and chemopreventive potential against hepatocellular carcinoma (HCC) in Balb/c mice. The HepG2 cell line was treated with CD-3 at various concentrations and the proliferation of the HepG2 cells was measure by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT), sulforhodamine B (SRB) and lactate dehydrogenase (LDH) assays. Cell apoptosis was detected by Hoechst 33258 (HO), Acridine orange/ethylene dibromide (AO/EB) staining, DNA fragmentation analysis and the apoptosis rate was detected by flow cytometry. The HCC tumor model was established in mice by injecting N-nitrosodiethylamine/carbon tetrachloride (NDEA/CCl4) and the effect of CD-3 on tumor growth in-vivo was studied. The levels of liver injury markers, tumor markers, and oxidative stress were measured. The expression levels of apoptosis-related genes in in-vitro and in vivo models were determined by RT-PCR and ELISA. The CD-3 induced cell death was considered to be apoptotic by observing the typical apoptotic morphological changes under fluorescent microscopy and DNA fragmentation analysis. Annexin V/PI assay demonstrated that apoptosis increased with increase in the concentration of CD-3. The expression levels of apoptosis-related genes that belong to bcl-2 and caspase family were increased and AP-1 and NF-κB activities were significantly suppressed by CD-3. Immunohistochemistry data revealed less localization of p53, p65 and c-jun in CD-3 treated tumors as compared to localization in NDEA/CCl4 treated tumors. Taken together, our data demonstrated that CD-3 could significantly inhibit the proliferation of HepG2 cells in-vitro and suppress HCC tumor growth in-vivo by apoptosis induction. [ABSTRACT FROM AUTHOR]

Abstract: Sepiapterin reductase (SPR) gene is an enzyme which catalyses the final step of tetrahydrobiopterin synthesis (BH4) and was implicated in Parkinson''s disease (PD) pathogenesis as a candidate gene for PARK3 locus. A number of studies yielded association of the PARK3 locus with PD, and SPR knockout mice were shown to display parkinsonian features. To evaluate the role of SPR gene polymorphisms in diverse populations in PD, we performed collaborative analyses in the Genetic Epidemiology of Parkinson Disease (GEO-PD) Consortium. A total of 5 single nucleotide polymorphisms (3 in the promoter region and 2 in the 3′ untranslated region [UTR]) were genotyped. Fixed as well as random effect models were used to provide summary risk estimates of SPR variants. A total of 19 sites provided data for 6547 cases and 9321 controls. Overall odds ratio estimates varied from 0.92 to 1.01. No overall association with the SPR gene using either fixed effect or random effect model was observed in the studied population. I2 Metric varied from 0% to 36.2%. There was some evidence for an association for participants of North European/Scandinavian descent with the strongest signal for rs1876487 (odds ratio = 0.82; p value = 0.003). Interestingly, families which were used to map the PARK3 locus, have Scandinavian ancestry suggesting a founder effect. In conclusion, this large association study for the SPR gene revealed no association for PD worldwide. However, taking the initial mapping of the PARK3 into account, the role of a population-specific effect warrants consideration in future studies. [Copyright &y& Elsevier]

Summary: SNARE-complex assembly mediates synaptic vesicle fusion during neurotransmitter release and requires that the target-SNARE protein syntaxin-1 switches from a closed to an open conformation. Although many SNARE proteins are available per vesicle, only one to three SNARE complexes are minimally needed for a fusion reaction. Here, we use high-resolution measurements of synaptic transmission in the calyx-of-Held synapse from mutant mice in which syntaxin-1 is rendered constitutively open and SNARE-complex assembly is enhanced to examine the relation between SNARE-complex assembly and neurotransmitter release. We show that enhancing SNARE-complex assembly dramatically increases the speed of evoked release, potentiates the Ca2+-affinity of release, and accelerates fusion-pore expansion during individual vesicle fusion events. Our data indicate that the number of assembled SNARE complexes per vesicle during fusion determines the presynaptic release probability and fusion kinetics and suggest a mechanism whereby proteins (Munc13 or RIM) may control presynaptic plasticity by regulating SNARE-complex assembly. [Copyright &y& Elsevier]