title: HIV-1 Vpr induces ATM-dependent cellular signal with enhanced homologous recombination.
abstract: An ATM-dependent cellular signal, a DNA-damage response, has been shown to be involved during infection of human immunodeficiency virus type-1 (HIV-1), and a high incidence of malignant tumor development has been observed in HIV-1-positive patients. Vpr, an accessory gene product of HIV-1, delays the progression of the cell cycle at the G2/M phase, and ATR-Chk1-Wee-1, another DNA-damage signal, is a proposed cellular pathway responsible for the Vpr-induced cell cycle arrest. In this study, we present evidence that Vpr also activates ATM, and induces expression of gamma-H2AX and phosphorylation of Chk2. Strikingly, Vpr was found to stimulate the focus formation of Rad51 and BRCA1, which are involved in repair of DNA double-strand breaks (DSBs) by homologous recombination (HR), and biochemical analysis revealed that Vpr dissociates the interaction of p53 and Rad51 in the chromatin fraction, as observed under irradiation-induced DSBs. Vpr was consistently found to increase the rate of HR in the locus of I-SceI, a rare cutting-enzyme site that had been introduced into the genome. An increase of the HR rate enhanced by Vpr was attenuated by an ATM inhibitor, KU55933, suggesting that Vpr-induced DSBs activate ATM-dependent cellular signal that enhances the intracellular recombination potential. In context with a recent report that KU55933 attenuated the integration of HIV-1 into host genomes, we discuss the possible role of Vpr-induced DSBs in viral integration and also in HIV-1 associated malignancy.
authors.affiliation: Department of Intractable Diseases, International Medical Center of Japan, Shinjuku-ku, Tokyo, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Nakai-Murakami
authors.forename: M
authors.initials: M
authors.lastname: Shimura
authors.forename: M
authors.initials: M
authors.lastname: Kinomoto
authors.forename: Y
authors.initials: Y
authors.lastname: Takizawa
authors.forename: K
authors.initials: K
authors.lastname: Tokunaga
authors.forename: T
authors.initials: T
authors.lastname: Taguchi
authors.forename: S
authors.initials: S
authors.lastname: Hoshino
authors.forename: K
authors.initials: K
authors.lastname: Miyagawa
authors.forename: T
authors.initials: T
authors.lastname: Sata
authors.forename: H
authors.initials: H
authors.lastname: Kurumizaka
authors.forename: A
authors.initials: A
authors.lastname: Yuo
authors.forename: Y
authors.initials: Y
authors.lastname: Ishizaka
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D016336:Gene Products, vpr / Q000502:physiology*; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011995:Recombination, Genetic; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D016336:Gene Products, vpr; D025521:Tumor Suppressor Proteins; D004247:DNA; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases