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“We have studied the developmental changes of glutamate-induced calcium (Ca2+) response in primary cultured hippocampal neurons at three different stages of cultures, 3, 7-8, and 14-16 days in vitro (DIV), using fura-2 single-cell digital micro-fluorimetry. We found that glutamate-induced Ca2+ signaling was altered during development, and that two different ionotropic glutamate receptors, -amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) and N-methyl-D-aspartate receptors (NMDARs), were differently involved in the modulation

of calcium response at different stages of neuronal culture. In the stages of culture at 3 and 8 DIV, glutamate-induced Ca2+ influx was mostly because of AMPAR activation and subsequent opening of voltage-dependent calcium channels, as Ca2+

response selleck chemical can be largely reduced by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and by nifedipine. In the advanced culture (14-17 DIV), glutamate-induced Ca2+ response was less sensitive to 6-cyano-7-nitroquinoxaline-2,3-dione and nifedipine. Furthermore, AMPA-induced Ca2+ response increased in a time-dependent manner during the cultures of 3-8 DIV and then reduced in the advanced culture of 14-17 DIV. NMDA-induced Ca2+ influx increased in a time-dependent manner, with a marked increase in the advanced culture (14-17 DIV). These results suggest that glutamate-induced Selleck KU55933 Ca2+ signaling switched from AMPA-voltage-dependent calcium channel to NMDA-calcium signaling during development.”
“The

ubiquitin-proteasome system (UPS) is involved in the replication of a broad range of viruses. Since replication of the murine hepatitis virus (MHV) is impaired upon proteasomal inhibition, the relevance of the UPS for the replication of the severe acute respiratory Levetiracetam syndrome coronavirus (SARS-CoV) was investigated in this study. We demonstrate that the proteasomal inhibitor MG132 strongly inhibits SARS-CoV replication by interfering with early steps of the viral life cycle. Surprisingly, other proteasomal inhibitors (e.g., lactacystin and bortezomib) only marginally affected viral replication, indicating that the effect of MG132 is independent of proteasomal impairment. Induction of autophagy by MG132 treatment was excluded from playing a role, and no changes in SARS-CoV titers were observed during infection of wild-type or autophagy-deficient ATG5(-/-) mouse embryonic fibroblasts overexpressing the human SARS-CoV receptor, angiotensin-converting enzyme 2 (ACE2). Since MG132 also inhibits the cysteine protease m-calpain, we addressed the role of calpains in the early SARS-CoV life cycle using calpain inhibitors III (MDL28170) and VI (SJA6017). In fact, m-calpain inhibition with MDL28170 resulted in an even more pronounced inhibition of SARS-CoV replication (>7 orders of magnitude) than did MG132.