THE HIV NEF PROTEIN ASSOCIATES WITH PROTEIN-KINASE-C-THETA

Expression of the human immunodeficiency virus (HIV) Nef protein has b een linked to both decreased cell surface expression of CD4 and an imp airment of signal transduction, The recently reported association of N ef with an unidentified serine kinase provides a clue as to how Nef mi ght exert its effects, Considering the key role of protein kinase C (P KC) in T cell activation, we investigated the possibility that Nef int eracts with PKC, Our results, using two approaches for detecting inter actions between Nef and PKC isozymes in Jurkat cells, show that Nef in teracts preferentially with beta PKC. The interaction of Nef and theta PKC is independent of calcium, enhanced by phospholipid activators of PKC and not affected by a PKC pseudosubstrate peptide, Phorbol 12-myr istate 13-acetate and phytohemagglutinin stimulation of Jurkat cells e xpressing Nef fails to produce the usual translocation of theta PKC fr om the cytosol to the particulate fraction; translocation of beta PKC and epsilon PKC was unaffected, Indeed, there appears to be a net loss of theta PKC in Nef-expressing cells following stimulation, The loss of theta PKC, which may be a result of inhibition of its binding to RA CKs due to Nef binding, could contribute to the various impairments of T cell function associated with HIV infection and Nef expression.