MIP-1 alpha induces activation of phosphatidylinositol-3 kinase that associates with Pyk-2 and is necessary for B-cell migration

The chemokine macrophage inflammatory protein-1 alpha [MIP-1 alpha] causes migration of B cells and also induces changes in antibody secretion. Howeve r, the signal transduction pathways leading to these phenotypic changes rem ain undefined. We have identified a signal transduction pathway initiated b y MIP-1 alpha in B cells. Here we report that stimulation of tonsil B cells with MIP-1 alpha induces phosphatidylinositol 3-kinase [P13-K] activation. Kinase activity was transient with peak induction occurring within 2.5 to 5 min after stimulation and was dose-dependent. In addition stimulation wit h MIP-1 alpha induces tyrosine phosphorylation of the proline-rich tyrosine kinase Pyk-2. Immunoprecipitation analysis showed a constitutive associati on between Pyk-2 and P13-K and pretreatment of MIP-1 alpha -stimulated B ce lls with wortmannin, a specific inhibitor of P13-K, resulted in a loss of P 13-K activity. The P13-K inhibitor wortmannin prevented B cells from migrat ing in response to MIP-1 alpha. Hence, P13-K and Pyk-2 seem to be component s of a signal transduction pathway induced by stimulation of B cells with M IP-1 alpha, and this pathway may play a role in B-cell migration. (C) 2001 Academic Press.