title: rac p21 is involved in insulin-induced membrane ruffling and rho p21 is involved in hepatocyte growth factor- and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced membrane ruffling in KB cells.
abstract: Insulin and hepatocyte growth factor (HGF) induced morphologically different membrane rufflings in KB cells. Insulin-induced membrane ruffling was inhibited by microinjection of rho GDI, an inhibitory GDP/GTP exchange regulator for both rho p21 and rac p21 small GTP-binding proteins, but not inhibited by microinjection of botulinum exoenzyme C3, known to selectively ADP-ribosylate rho p21 and to impair its function. This rho GDI action was prevented by comicroinjection with guanosine 5'-(3-O-thio)triphosphate (GTP gamma S)-bound rac1 p21. In contrast, HGF-induced membrane ruffling was inhibited by microinjection of rho GDI or C3. This rho GDI action was prevented by comicroinjection with GTP gamma S-bound rhoA p21, and this C3 action was prevented by comicroinjection with GTP gamma S-bound rhoAIle-41 p21, which is resistant to C3. Microinjection of either GTP gamma S-bound rac1 p21 or rhoA p21 alone induced membrane ruffling in the absence of the growth factors. The rac1 p21-induced membrane ruffling was morphologically similar to the insulin-induced kind, whereas rhoA p21-induced ruffling was apparently different from both the insulin- and HGF-induced kinds. Membrane ruffling was also induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), a protein kinase C-activating phorbol ester, but not by Ca2+ ionophore or microinjection of a dominant active Ki-ras p21 mutant (Ki-rasVal-12 p21). The phorbol ester-induced membrane ruffling was morphologically similar to the rhoA p21-induced kind and inhibited by microinjection of rho GDI or C3. These results indicate that rac p21 and rho GDI are involved in insulin-induced membrane ruffling and that rho p21 and rho GDI are involved in HGF- and phorbol ester-induced membrane rufflings.
authors.affiliation: Department of Biochemistry, Kobe University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nishiyama
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
authors.forename: K
authors.initials: K
authors.lastname: Takaishi
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: H
authors.initials: H
authors.lastname: Yaku
authors.forename: K
authors.initials: K
authors.lastname: Araki
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuura
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
mesh_terms: D036002:ADP Ribose Transferases / Q000494:pharmacology; D001905:Botulinum Toxins; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007624:KB Cells; D008845:Microinjections; D011485:Protein Binding; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins
chemical_list: D007328:Insulin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D017228:Hepatocyte Growth Factor; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate