Rho GTPase is required for actin filament assembly and serum response
element (SRE)-dependent gene transcription. Certain G protein-coupled
receptors (GPCRs) induce Rho-dependent responses, but the intermediary
signaling steps are poorly understood. The heterotrimeric Gα12 family can
induce Rho-dependent responses. In contrast, there are conflicting reports
on the role of the Gαq family in Rho signaling. We report that expression
of activated Gαq members, or activation of endogenous Gαq via GPCR
stimulation, induces SRE reporter activation via Rho, and increased GTP-Rho
levels. Moreover, microinjection of activated Gαq in fibroblasts induces
actin stress fiber formation via Rho. Gαq functionally cooperates with Lbc
Rho guanine nucleotide exchange factor. Overall, these findings indicate
that Gαq family signals are sufficient to induce Rho-dependent cellular
responses.