Critical implication of the (70-96) domain of human immunodeficiency virus type 1 Vpr protein in apoptosis of primary rat cortical and striatal neurons.
The human immunodeficiency virus (HIV)-1 regulatory protein Vpr has been detected in the serum of HIV-seropositive individuals and in the cerebrospinal fluid of acquired immunodeficiency syndrome (AIDS) patients suffering from neurological disorders. Therefore, Vpr could play a critical role in the neuronal apoptosis observed postmortem in the brain of patients, often connected to a severe AIDS-related disease termed HIV-associated dementia (HAD). This suggests that the Vpr neurotoxicity already observed in vitro on hippocampal neurons could also occur in other brain structures. In this study the authors have investigated the ability of synthetic Vpr to induce apoptosis in primary cultures of rat cortical and striatal neurons. Moreover, the authors have explored the Vpr minimal proapoptotic region using synthetic Vpr fragments and mutants of the protein. Treatments of both neuronal types with Vpr, its C-terminal domain, Vpr(52-96), or a shorter fragment, Vpr(70-96), led to dose- and time-dependent cell death as determined by flow cytometry after propidium iodide labeling, phase-contrast microscopy, and TUNEL labeling. Taken together, these results support an apoptosis-induced death of these neurons. The (71-82) Vpr peptide, previously shown toxic to isolated mitochondria, was inactive on neurons. Vpr-induced neuronal apoptosis was associated with activation of caspase-3 beginning 3 h after Vpr extracellular addition and peaking 3 h later. Moreover, an hyperproduction of reactive oxygen species was observed. In addition to hippocampal neurons, the extension of the apoptotic property of Vpr to cortical and striatal neurons could account for several signs observed in HAD and is thus consistent with a possible involvement of Vpr in this syndrome.
Sabbah
Emmanuelle N
EN
Unite de Pharmacochimie Moleculaire et Structurale, INSERM U266, CNRS UMR 8600, UFR des Sciences Pharmaceutiques et Biologiques, Universite Rene Descartes, Paris, France.
Roques
Bernard P
BP
D015526:AIDS Dementia Complex / Q000209:etiology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002540:Cerebral Cortex / Q000166:cytology*; D003342:Corpus Striatum / Q000166:cytology*; D016336:Gene Products, vpr / Q000737:chemistry / Q000633:toxicity*; D015699:HIV Envelope Protein gp120 / Q000633:toxicity; D015497:HIV-1 / Q000737:chemistry* / Q000472:pathogenicity; D006801:Humans; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D054325:vpr Gene Products, Human Immunodeficiency Virus
D016336:Gene Products, vpr; D015699:HIV Envelope Protein gp120; D054325:vpr Gene Products, Human Immunodeficiency Virus