title: Small GTPase Tc10 and its homologue RhoT induce N-WASP-mediated long process formation and neurite outgrowth.
abstract: Rho family small GTPases regulate multiple cellular functions through reorganization of the actin cytoskeleton. Among them, Cdc42 and Tc10 induce filopodia or peripheral processes in cultured cells. We have identified a member of the family, designated as RhoT, which is closely related to Tc10. Tc10 was highly expressed in muscular tissues and brain and remarkably induced during differentiation of C2 skeletal muscle cells and neuronal differentiation of PC12 and N1E-115 cells. On the other hand, RhoT was predominantly expressed in heart and uterus and induced during neuronal differentiation of N1E-115 cells. Tc10 exogenously expressed in fibroblasts generated actin-filament-containing peripheral processes longer than the Cdc42-formed filopodia, whereas RhoT produced much longer and thicker processes containing actin filaments. Furthermore, both Tc10 and RhoT induced neurite outgrowth in PC12 and N1E-115 cells, but Cdc42 did not do this by itself. Tc10 and RhoT as well as Cdc42 bound to the N-terminal CRIB-motif-containing portion of N-WASP and activated N-WASP to induce Arp2/3-complex-mediated actin polymerization. The formation of peripheral processes and neurites by Tc10 and RhoT was prevented by the coexpression of dominant-negative mutants of N-WASP. Thus, N-WASP is essential for the process formation and neurite outgrowth induced by Tc10 and RhoT. Neuronal differentiation of PC12 and N1E-115 cells induced by dibutyryl cyclic AMP and by serum starvation, respectively, was prevented by dominant-negative Cdc42, Tc10 and RhoT. Taken together, all these Rho family proteins are required for neuronal differentiation, but they exert their functions differentially in process formation and neurite extension. Consequently, N-WASP activated by these small GTPases mediates neuronal differentiation in addition to its recently identified role in glucose uptake.
authors.affiliation: Department of Biology, Faculty of Science, and Graduate School of Science and Technology, Chiba University, Yayoicho, Inageku, Chiba, Chiba 263-8522, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Abe
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kato
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Miki
authors.forename: Tadaomi
authors.initials: T
authors.lastname: Takenawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Endo
mesh_terms: D016475:3T3 Cells; D008841:Actin Cytoskeleton / Q000378:metabolism*; D051377:Actin-Related Protein 2; D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D001921:Brain / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D016716:PC12 Cells; D010802:Phylogeny; D011554:Pseudopodia / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D051377:Actin-Related Protein 2; C495927:Actr2 protein, mouse; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D009419:Nerve Tissue Proteins; C485944:Rhoj protein, mouse; C495772:Wasl protein, mouse; C495770:Wasl protein, rat; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D003994:Bucladesine; D020558:GTP Phosphohydrolases; C477150:RhoT protein, mouse; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins