title: Role of the Sec14-like domain of Dbl family exchange factors in the regulation of Rho family GTPases in different subcellular sites.
abstract: Mechanisms underlying subcellular region-specific regulation of Rho family GTPases through Dbl family guanine nucleotide exchange factors (GEFs) remain totally unknown. Here we show that the Sec14-like domain, which lies in the N-terminus of the Dbl family GEFs Dbl and Ost, directs the subcellular localization of these GEFs and also their substrate Cdc42. When coexpressed with Cdc42 in human adenocarcinoma HeLa cells, Dbl-I and Ost-I, which lack the Sec14-like domain, translocated Cdc42 to the plasma membrane, where Dbl-I or Ost-I was colocalized. In marked contrast, Dbl-II and Ost-II, which contain the Sec14-like domain, were colocalized with Cdc42 in endomembrane compartments. Furthermore, ruffle membrane formation upon epidermal growth factor treatment was mediated by Dbl-I or Ost-I, but neither Dbl-II nor Ost-II, supporting a notion that GEFs with or without the Sec14-like domain are linked to different upstream signals. By employing a novel method to detect the active GTP-bound form of Cdc42 in situ, we demonstrate that Dbl-I and Ost-I, but neither Dbl-II nor Ost-II, indeed activate colocalized Cdc42.
authors.affiliation: Division of Molecular Biology, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo, Kobe 650-0017, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Ueda
authors.forename: Tohru
authors.initials: T
authors.lastname: Kataoka
authors.forename: Takaya
authors.initials: T
authors.lastname: Satoh
mesh_terms: D000595:Amino Acid Sequence; D002451:Cell Compartmentation; D003001:Cloning, Molecular; D005455:Fluorescent Antibody Technique; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary / Q000502:physiology; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins