AEGiS-15IAC: Heat shock protein 70 is an innate anti-HIV factor targeting Vpr.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

Heat shock protein 70 is an innate anti-HIV factor targeting Vpr.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. TuOrA1108)

Bukrinsky MI, Zhao Y, Iordanskiy SN
The George Washington University Medical Center, Washington, DC, United States

BACKGROUND: HIV-1 Vpr is an important contributor to viral pathogenesis. Vpr displays several highly conserved pathogenic activities, including induction of cell cycle G2 arrest and cell death, as well as stimulating HIV-1 infection of macrophages. To identify innate anti-Vpr factors, we performed a genetic search for multicopy suppressors of Vpr activities in fission yeast. Several heat shock proteins (Hsp's) were identified in these experiments. We focus here on analysis of activity of Hsp70, a member of the Hsp family involved in innate immunity and protection from environmental stress.

METHODS: For Vpr and Hsp70 expression in 293T cells, a modified episomal system for ecdysone-inducible expression was used. In this system, vpr and hsp70 are maintained as episomes and can be induced by muristerone A. Infections were performed using MLV Env-psudotyped HIV-1. To analyze spreading HIV-1 infection, we stably expressed Hsp70 in H9 cells, which were infected with a Vpr-positive or Vpr-deficient HIV-1. To knockout Hsp70 expression, RNAi approach was used.

RESULTS: Hsp70 significantly reduced Vpr-induced G2 arrest and inhibited Vpr nuclear localization. Both in proliferating T cells and macrophages, Hsp70 suppressed replication of the Vpr-positive virus, but not of the Vpr-defective construct. Suppression of Hsp70 expression by RNAi resulted in increased G2 arrest and apoptosis of target cells. Vpr and Hsp70 co-immunoprecipitated from HIV-infected cells.

CONCLUSIONS: Our results demonstrate that Hsp70 functions as an innate anti-HIV factor that neutralizes activity of Vpr. The balance between Vpr and Hsp70 may determine, at least in part, the level of HIV-1 replication. Together, these results illustrate another example of antagonistic interactions between the viral and cellular proteins and reveal a new activity of Hsp70.

Keywords: AEGIS, Genes, vpr, Acquired Immunodeficiency Syndrome, HIV Seropositivity, HIV-1, Heat-Shock Proteins 70, HIV Infections, Virus Replication, Heat-Shock Proteins, Cell Cycle, Schizosaccharomyces, Macrophages, Apoptosis, genetics, virology

040711
TuOrA1108