Roles of p53 and caspases in the induction of cell cycle arrest and apoptosis by HIV-1 vpr.
The vpr gene from the human immunodeficiency virus type-1 (HIV-1) encodes a 14-kDa protein that prevents cell proliferation by causing a block in the G(2) phase of the cell cycle. This cellular function of vpr is conserved in evolution because other primate lentiviruses, including HIV-2, SIV(mac), and SIV(agm) encode related genes that also induce G(2) arrest. After G(2) arrest, cells expressing vpr undergo apoptosis. The signaling pathways that result in vpr-induced cell cycle arrest and apoptosis have yet to be determined. The p53 tumor suppressor protein is involved in signaling pathways leading to cell cycle arrest and apoptosis in a variety of cell types. In this work, we examine the potential role of p53 in mediating cell cycle block and/or apoptosis by HIV-1 vpr and demonstrate that both phenomena occur independently of the presence and function of p53. Caspases are common mediators of apoptosis. We examined the potential role of caspases in mediating vpr-induced apoptosis by treating vpr-expressing cells with Boc-D-FMK, a broad spectrum, irreversible inhibitor of the caspase family. Boc-D-FMK significantly reduced the numbers of apoptotic cells induced by vpr. Therefore, we conclude that vpr-induced apoptosis is effected via the activation of caspases.
Shostak
L D
LD
Department of Medicine, University of Rochester Cancer Center, 601 Elmwood Avenue, Rochester, New York 14642, USA.
Ludlow
J
J
Fisk
J
J
Pursell
S
S
Rimel
B J
BJ
Nguyen
D
D
Rosenblatt
J D
JD
Planelles
V
V
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019556:COS Cells; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D053938:DNA Fragmentation; D004317:Doxorubicin / Q000494:pharmacology; D004789:Enzyme Activation; D016195:G2 Phase / Q000187:drug effects / Q000528:radiation effects; D005720:Gamma Rays; D016336:Gene Products, vpr / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors / Q000235:genetics; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D008466:Mechlorethamine / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*; D054325:vpr Gene Products, Human Immunodeficiency Virus
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D016336:Gene Products, vpr; D016159:Tumor Suppressor Protein p53; C103192:butyloxycarbonyl-O-methyl-aspartyl-fluoromethyl ketone; D054325:vpr Gene Products, Human Immunodeficiency Virus; D008466:Mechlorethamine; D004317:Doxorubicin; D020169:Caspases