title: Dock6, a Dock-C subfamily guanine nucleotide exchanger, has the dual specificity for Rac1 and Cdc42 and regulates neurite outgrowth.
abstract: Small GTPases of the Rho family, Rho, Rac, and Cdc42, are critical regulators of the changes in the actin cytoskeleton. Rho GTPases are typically activated by Dbl-homology (DH)-domain-containing guanine nucleotide exchange factors (GEFs). Recent genetic and biochemical studies revealed a new type of GEF for the Rho GTPases. This family is composed of 11 genes, designated as Dock1 to Dock11, and is structurally divided into four classes Dock-A, -B, -C, and -D. Dock-A and -B subfamilies are typically GEFs specific for Rac1, while the Dock-D subfamily is specific for Cdc42. Here we show that Dock6, a member of the Dock-C subfamily, exchanges GDP for GTP for Rac1 and Cdc42 in vitro and in vivo. Furthermore, we find that, in mouse N1E-115 neuroblastoma cells, expression of Dock6 is increased following differentiation. Transfection of the catalytic Dock Homology Region-2 (DHR-2) domain of Dock6 promotes neurite outgrowth mediated by Rac1 and Cdc42. Conversely, knockdown of endogenous Dock6 by small interference RNA reduces activation of Rac1 and Cdc42 and neurite outgrowth. Taken together, these results suggest that Dock6 differs from all of the identified Dock180-related proteins, in that it is the GEF specific for both Rac1 and Cdc42 and may be one of physiological regulators of neurite outgrowth.
authors.affiliation: Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Junji
authors.initials: J
authors.lastname: Yamauchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sanbe
authors.forename: Akito
authors.initials: A
authors.lastname: Tanoue
mesh_terms: D000818:Animals; D019556:COS Cells; D020134:Catalytic Domain; D002522:Chlorocebus aethiops; D020690:GTPase-Activating Proteins / Q000378:metabolism / Q000502:physiology*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism / Q000502:physiology*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D051379:Mice; D016501:Neurites / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism*; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein
chemical_list: C518736:Dock6 protein, mouse; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D009479:Neuropeptides; C484602:Rac1 protein, mouse; D006160:Guanosine Triphosphate; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein