title: HIV-1 Vpr transactivates LTR-directed expression through sequences present within -278 to -176 and increases virus replication in vitro.
abstract: Human immunodeficiency virus type 1 (HIV-1) Vpr, a 14-kDa virion-associated protein, plays an important role in the viral life cycle. Using a panel of truncated HIV-1 LTR-CAT constructs and Vpr expression plasmid, we have identified sequences from nucleotide -278 to -176 in LTR as Vpr-mediated transactivation domain. This region includes the glucocorticoid response element (GRE) in HIV-1 LTR. Transactivation by Vpr was noted with the HIV-1 LTR reporter constructs containing CAT or luciferase. A similar effect was also observed with a construct in which the GRE motif was linked to CAT. Studies involving Vpr mutants identified that helical domains I and III, and amino acid residues at G75 and C76, are responsible for GRE-mediated LTR transactivation. The transactivation function of Vpr is independent of its cell cycle arrest activity. Further, viral replication studies indicated that Vpr-mediated increase in viral replication is directly correlated with the ability of Vpr to transactivate HIV-1 LTR. The results presented here demonstrate that Vpr activates HIV-1 LTR through the host GR pathway and suggest that an intact GRE in the LTR is critical for Vpr activity.
authors.affiliation: Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: R
authors.initials: R
authors.lastname: Vanitharani
authors.forename: S
authors.initials: S
authors.lastname: Mahalingam
authors.forename: Y
authors.initials: Y
authors.lastname: Rafaeli
authors.forename: S P
authors.initials: SP
authors.lastname: Singh
authors.forename: A
authors.initials: A
authors.lastname: Srinivasan
authors.forename: D B
authors.initials: DB
authors.lastname: Weiner
authors.forename: V
authors.initials: V
authors.lastname: Ayyavoo
mesh_terms: D016336:Gene Products, vpr / Q000235:genetics / Q000502:physiology*; D005938:Glucocorticoids / Q000494:pharmacology; D016322:HIV Enhancer; D015658:HIV Infections / Q000821:virology*; D016325:HIV Long Terminal Repeat / Q000235:genetics; D015497:HIV-1 / Q000737:chemistry / Q000472:pathogenicity / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases; D009154:Mutation; D020218:Response Elements; D015534:Trans-Activators / Q000502:physiology*; D014779:Virus Replication; D054325:vpr Gene Products, Human Immunodeficiency Virus
chemical_list: D016336:Gene Products, vpr; D005938:Glucocorticoids; D015534:Trans-Activators; D054325:vpr Gene Products, Human Immunodeficiency Virus; D008156:Luciferases