ROLE OF RHO IN CHEMOATTRACTANT-ACTIVATED LEUKOCYTE ADHESION THROUGH INTEGRINS

Heterotrimeric guanine nucleotide binding protein (G protein)-linked r eceptors of the chemoattractant subfamily can trigger adhesion through leukocyte integrins, and in this role they are thought to regulate im mune cell-cell interactions and trafficking. In lymphoid cells transfe cted with formyl peptide or interleukin-8 receptors, agonist stimulati on activated nucleotide exchange on the small guanosine triphosphate-b inding protein RhoA in seconds. Inactivation of Rho by C3 transferase exoenzyme blocked agonist-induced lymphocyte alpha 4 beta 1 adhesion t o vascular cell adhesion molecule-1 and neutrophil beta 2 integrin adh esion to fibrinogen. These findings suggest that Rho participates in s ignaling from chemoattractant receptors to trigger rapid adhesion in l eukocytes.