HIV-1 p17 Matrix Protein Interacts with Heparan Sulfate Side Chain of CD44v3, Syndecan-2, and Syndecan-4 Proteoglycans Expressed on Human Activated CD4+ T Cells Affecting Tumor Necrosis Factor α and Interleukin 2 Production

HIV-1 p17 contains C- and N-terminal sequences with positively charged residues and a consensus cluster for heparin binding. We have previously demonstrated by affinity chromatography that HIV-1 p17 binds strongly to heparin-agarose at physiological pH and to human activated CD4+ T cells. In this study we demonstrated that the viral protein binds to heparan sulfate side chains of syndecan-2, syndecan-4, and CD44v3 purified from HeLa cells and that these heparan sulfate proteoglycans (HSPGs) co-localize with HIV-1 p17 on activated human CD4+ T cells by confocal fluorescence analysis. Moreover, we observed a stimulatory or inhibitory activity when CD4+ T cells were activated with mitogens together with nanomolar or micromolar concentrations of the matrix protein.