Rho Guanine Nucleotide Exchange Factor 15 (ARHGEF15)

Rho GTPases play a fundamental role in numerous cellular processes that are initiated by extracellular stimuli that work through G protein-coupled receptors. ARHGEF15 encodes a protein that functions as a specific guanine nucleotide exchange factor for RhoA. Endogenous rat Arhgef15 was coimmunoprecipitated by anti-Epha4 antibody in a rat aortic smooth muscle cell line, and mouse Epha4 immunoprecipitated with human ARHGEF15 when coexpressed in a human embryonic kidney cell line. Mutation analysis indicated that the Dbl homology domain and the pleckstrin homology (PH) domain of ARHGEF15, but not the PH domain alone, mediated the interaction with Epha4. The authors presented evidence that ARHGEF15 has a role in RHOA activation and the regulation of vascular smooth muscle contractility.