Regulator of G Protein Signaling 1 (RGS1) Markedly Impairs Giα Signaling Responses of B Lymphocytes

Abstract

Regulator of G protein signaling (RGS) proteins modulate signaling through pathways that use heterotrimeric G proteins as transducing elements. RGS1 is expressed at high levels in certain B cell lines and can be induced in normal B cells by treatment with TNF-α. To determine the signaling pathways that RGS1 may regulate, we examined the specificity of RGS1 for various Gα subunits and assessed its effect on chemokine signaling. G protein binding and GTPase assays revealed that RGS1 is a Giα and Gqα GTPase-activating protein and a potential G12α effector antagonist. Functional studies demonstrated that RGS1 impairs platelet activating factor-mediated increases in intracellular Ca+2, stromal-derived factor-1-induced cell migration, and the induction of downstream signaling by a constitutively active form of G12α. Furthermore, germinal center B lymphocytes, which are refractory to stromal-derived factor-1-triggered migration, express high levels of RGS1. These results indicate that RGS proteins can profoundly effect the directed migration of lymphoid cells.