HIV-1 gp120 and chemokine activation of Pyk2 and mitogen-activated proteinkinases in primary macrophages mediated by calcium-dependent, pertussis toxin-insensitive chemokine receptor signaling

Human immunodeficiency virus type 1 (HIV-1) uses the chemokine receptors CC R5 and CXCR4 as coreceptors for entry. It was recently demonstrated that HI V-1 glycoprotein 120 (gp120) elevated calcium and activated several ionic s ignaling responses in primary human macrophages, which are important target s for HIV-1 in vivo. This study shows that chemokine receptor engagement by both CCR5-dependent (R5) and CXCR4-dependent (X4) gp120 led to rapid phosp horylation of the focal adhesion-related tyrosine kinase Pyk2 in macrophage s. Pyk2 phosphorylation was also induced by macrophage inflammatory protein -1 beta (MIP-1 beta) and stromal cell-derived factor-1 alpha, chemokine lig ands for CCR5 and CXCR4. Activation was blocked by EGTA and by a potent blo cker of calcium release-activated Ca++ (CRAG) channels, but was insensitive to pertussis toxin (PTX), implicating CRAC-mediated extracellular Ca++ inf lux but not Gal protein-dependent mechanisms. Coreceptor engagement by gp12 0 and chemokines also activated 2 members of the mitogen-activated protein kinase (MAPK) superfamily, c-Jun amino-terminal kinase/stress-activated pro tein kinase and p38 MAPK. Furthermore, gp120-stimulated macrophages secrete d the chemokines monocyte chemotactic protein-1 and MIP-1 beta in a manner that was dependent on MAPK activation. Thus, the gp120 signaling cascade in macrophages includes coreceptor binding, PTX-insensitive signal transducti on, ionic signaling including Ca++ influx, and activation of Pyk2 and MAPK pathways, and leads to secretion of inflammatory mediators. HIV-1 Env signa ling through these pathways may contribute to dysregulation of uninfected m acrophage functions, new target cell recruitment, or modulation of macropha ge infection. (C) 2001 by The American Society of Hematology.