Induction and prevention of apoptosis in human HEp-2 cells by herpes simplex virus type 1.
Cultured human epithelial cells infected with an ICP27 deletion strain of herpes simplex virus type 1 (HSV-1) show characteristic features of apoptotic cells including cell shrinkage, nuclear condensation, and DNA fragmentation. These cells do not show such apoptotic features when infected with a wild-type virus unless the infections are performed in the presence of a protein synthesis inhibitor. Thus, both types of virus induce apoptosis, but the ICP27-null virus is unable to prevent this process from killing the cells. In this report, we show that this ICP27-deficient virus induced apoptosis in human HEp-2 cells through a pathway which involved the activation of caspase-3 and the processing of the death substrates DNA fragmentation factor and poly(ADP-ribose) polymerase. The induction of apoptosis by wild-type HSV-1 occurred prior to 6 h postinfection (hpi), and de novo viral protein synthesis was not required to induce the process. The ability of the virus to inhibit apoptosis was shown to be effective between 3 to 6 hpi. Wild-type HSV-1 infection was also able to block the apoptosis induced in cells by the addition of cycloheximide, staurosporine, and sorbitol. While U(S)3- and ICP22-deficient viruses showed a partial prevention of apoptosis, deletion of either the U(L)13 or vhs gene products did not affect the ability of HSV-1 to prevent apoptosis in infected cells. Finally, we demonstrate that in UV-inactivated viruses, viral binding and entry were not sufficient to induce apoptosis. Taken together, these results suggest that either gene expression or another RNA metabolic event likely plays a role in the induction of apoptosis in HSV-1-infected human cells.
Aubert
M
M
Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029, USA.
O'Toole
J
J
Blaho
J A
JA
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D061945:Caspase Inhibitors; D002522:Chlorocebus aethiops; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017353:Gene Deletion; D018259:Herpesvirus 1, Human / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D012260:Ribonucleases; D013012:Sorbitol; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics; D054334:Viral Regulatory and Accessory Proteins
D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C057294:ICP22 protein, human herpesvirus 1; C057120:ICP27 protein, human herpesvirus 1; D017874:Immediate-Early Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C048925:herpes simplex virus, type 1 protein ICP4; C070722:virion host shutoff protein, Simplexvirus; C078424:EUS1 protein, Equine herpesvirus 1; D013012:Sorbitol; D011494:Protein Kinases; C082380:UL13 protein, Simplexvirus; D017346:Protein Serine-Threonine Kinases; C095207:US3 protein, Human herpesvirus 1; D012260:Ribonucleases; C505407:CASP3 protein, human; D053148:Caspase 3; D019311:Staurosporine