Coxsackievirus protein 2BC blocks host cell apoptosis by inhibiting caspase-3.
Virus infection may induce host cell death by apoptosis, but some DNA viruses are capable of preventing this process. RNA viruses were thought not to display anti-apoptotic activities, as their spread appears to benefit from a rapid induction of cell death. Here, we report an antiapoptotic activity in the Picornavirus Coxsackievirus B4 (CVB4). CVB4 infection of HeLa cells induced negligible apoptosis over a period of 10 h. However, infected cells developed resistance to drug-induced apoptosis using staurosporine and actinomycin D and to death receptor-induced apoptosis using tumor necrosis factor-related apoptosis-inducing ligand. Despite this resistance, the apoptotic machinery was nonetheless fully activated in these drug-treated infected cells because the levels of pro-caspase-3 processing to its active form were similar to control cells. However, the DEVDase (Asp-Glu-Val-Asp protease) activity of the processed caspase was significantly inhibited in the virus-infected staurosporine-treated cells compared with drug treatment alone. Likewise, extracts of CVB4-infected cells suppressed recombinant caspase-3 activity in vitro. Immunoprecipitation of activated caspase-3 from radiolabeled virus-infected cells revealed the co-precipitation of a 48-kDa protein that was tentatively identified as viral protein 2BC. Recombinant caspase-3 was found to co-precipitate with virus protein 2BC. Finally, when protein 2BC was expressed in HeLa cells, both staurosporine-induced apoptosis and in vitro caspase-3 DEVDase activity were significantly reduced. Taken together these data imply that CVB4 infection suppresses apoptosis through virus protein 2BC associating with caspase-3 and inhibiting its function. Thus, 2BC is the first reported RNA virus inhibitor of apoptosis protein.
Salako
Michael A
MA
School of Biomedical and Molecular Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom.
Carter
Michael J
MJ
Kass
George E N
GE
D000595:Amino Acid Sequence; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004770:Enterovirus; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005434:Flow Cytometry; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D017361:Viral Nonstructural Proteins; D003609:Dactinomycin; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases