📄 Severe acute respiratory syndrome coronavirus 3a protein activates the mitochondrial death pathway through p38 MAP kinase activation

The molecular mechanisms governing severe acute respiratory syndrome coronavirus-induced pathology are not fully understood. Virus infection and some individual viral proteins, including the 3a protein, induce apoptosis. However, the cellular targets leading to 3a protein-mediated apoptosis have not been fully characterized. This study showed that the 3a protein modulates the mitochondrial death pathway in two possible ways. Activation of caspase-8 through extrinsic signal(s) caused Bid activation. In the intrinsic pathway, there was activation of caspase-9 and cytochrome c release from the mitochondria. This was the result of increased Bax oligomerization and higher levels of p53 in 3a protein-expressing cells, which depended on the activation of p38 MAP kinase (MAPK) in these cells. For p38 activation and apoptosis induction, the 3a cytoplasmic domain was sufficient. In direct Annexin V staining assays, the 3a protein-expressing cells showed increased apoptosis that was attenuated with the p38 MAPK inhibitor SB203580. A block in nuclear translocation of the STAT3 transcription factor in cells expressing the 3a protein was also observed. These results have been used to present a model of 3a-mediated apoptosis. © 2008 SGM.

keywords 🔗 severe acute (1373) 🔗 syndrome coronavirus (1074) 🔗 cells expressing (60) 🔗 viral proteins (89) 🔗 respiratory syndrome (2004) 🔗 acute respiratory (1734)

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