Rho guanine nucleotide exchange factor 40 (ARHGEF40)

Rho guanine nucleotide exchange factor 40 (ARHGEF40), also known as Solo, is an enzyme that facilitates the activation of the small GTPase RhoA by promoting the exchange of GDP for GTP. This activation is essential for mechanotransduction—the process by which cells convert mechanical stimuli into biochemical signals—particularly in the remodeling of the cytoskeleton and cell adhesion complexes[1][3]. ARHGEF40 binds to keratin-8/keratin-18 intermediate filaments and interacts with β4-integrin, regulating hemidesmosome formation in epithelial cells. Its activity is linked to the generation of cellular traction forces, collective cell migration, tissue morphogenesis, and homeostasis. Genetic variants in ARHGEF40 have been associated with altered lung function, cancer predisposition (especially in non-small cell lung cancer and melanoma), and primary open-angle glaucoma[1][5]. In cancer, ARHGEF40 promotes cell proliferation and invasion via RhoA-mediated signaling and by influencing pathways such as AKT-Wnt[5]. Although no direct drugs for ARHGEF40 exist, RhoA pathway inhibitors (such as Y-27632) indirectly influence its downstream effects[3]. Disruption of ARHGEF40 impairs cell adhesion, polarity, and proliferation, indicating its essential physiological role and the potential risks of direct therapeutic intervention[3][5][1].

Other names

ARHGEF40SOLOsoloFLJ10357Protein SOLO

Drugs that modulate ARHGEF40 typically act on its downstream effectors (e.g. RhoA, ROCK); Y-27632 is a ROCK inhibitor that interferes with RhoA-ROCK pathway. No direct small molecule inhibitors of ARHGEF40 are reported.