389 HIV gp120 and CD4 Binding Induces Activation of STAT1, STAT3, and STAT5 in Promonocytes and Macrophages J. Kohler*1, C. Gavegnano2, J. Sleasman1, M. Goodenow1 1Univ of Florida, Coll of Med, Gainesville and 2Univ of Florida, Gainesville
Background: Signal transducer and activator of transcription (STAT) proteins are cytoplasmic transcription factors that translocate to the nucleus when activated and regulate gene expression as mediators of cytokine and growth factor stimulation. Several viruses, including Human Immunodeficiency Virus (HIV-1), have been reported to alter STAT activation. We designed a study to investigate direct and immediate interactions between HIV-1 envelope gp120 and STAT signal transduction pathways through functional measurement of activated STATs in nuclear extracts from CD4+ promonocytes and monocyte-derived macrophages.
Methods: Nuclear extracts were prepared from cells treated with IFN-gamma, purified gp120 proteins from various HIV-1 strains, envelope-deficient recombinant virus, or mouse monoclonal IgG1 anti-human CD4 antibody. Activation levels of STAT proteins were determined by electro-mobility shift assays and super-shifting with a panel of anti-STAT specific antibodies.
Results: IFNgamma stimulation induced STAT1. In contrast, purified gp120 proteins from various HIV strains, which utilize either coreceptor R5 or X4, induced STAT1, STAT3, and STAT5 activation. Anti-CD4 antibody binding also resulted in the activation of STAT1, STAT3, and STAT5.
Conclusions: HIV gp120 is sufficient to induce intracellular signalling in CD4+ promonocytes and macrophages independent of coreceptor R5 or X4. Monoclonal antibody engagement of CD4 identified a novel role for CD4 as a mediator in the activation of multiple STATs. Results provide a model for HIV-1 pathogenesis in both infected and non-infected hematopoietic cells.
