title: Activation of the ATR pathway by human immunodeficiency virus type 1 Vpr involves its direct binding to chromatin in vivo.
abstract: The human immunodeficiency virus type 1 (HIV-1) protein Vpr (viral protein R) arrests cells in the G2 phase of the cell cycle, a process that requires activation of the ATR (ataxia-telangiectasia and Rad3-related) pathway. In this study we demonstrate that the expression of Vpr does not cause DNA double-strand breaks but rather induces ATR activation, as indicated by induction of Chk1 phosphorylation and the formation of gamma-H2AX and 53BP1 nuclear foci. We define a C-terminal domain containing repeated H(F/S)RIG sequences required for Vpr-induced activation of ATR. Further investigation of the mechanism by which Vpr activates the ATR pathway reveals an increase in chromatin binding of replication protein A (RPA) upon Vpr expression. Immunostaining shows that RPA localizes to nuclear foci in Vpr-expressing cells. Furthermore, we demonstrate direct binding of Vpr to chromatin in vivo, whereas Vpr C-terminal domain mutants lose this chromatin-binding activity. These data support a mechanism whereby HIV-1 Vpr induces ATR activation by targeting the host cell DNA and probably interfering with normal DNA replication.
authors.affiliation: Division of Oncology Research, Mayo Clinic, Guggenheim 1342, Rochester, MN 55905, USA.
authors.forename: Maoyi
authors.initials: M
authors.lastname: Lai
authors.forename: Erik S
authors.initials: ES
authors.lastname: Zimmerman
authors.forename: Vicente
authors.initials: V
authors.lastname: Planelles
authors.forename: Junjie
authors.initials: J
authors.lastname: Chen
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D002843:Chromatin / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation; D016336:Gene Products, vpr / Q000235:genetics / Q000494:pharmacology*; D015497:HIV-1 / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D054325:vpr Gene Products, Human Immunodeficiency Virus
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D016336:Gene Products, vpr; D054325:vpr Gene Products, Human Immunodeficiency Virus; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases