title: Regulation of cytoplasmic division of Xenopus embryo by rho p21 and its inhibitory GDP/GTP exchange protein (rho GDI).
abstract: Evidence is accumulating that the rho family, a member of the ras p21-related small GTP-binding protein superfamily, regulates cell morphology, cell motility, and smooth muscle contraction through the actomyosin system. The actomyosin system is also known to be essential for cytoplasmic division of cells (cytokinesis). In this study, we examined the action of rho p21, its inhibitory GDP/GTP exchange protein, named rho GDI, its stimulatory GDP/GTP exchange protein, named smg GDS, and botulinum ADP-ribosyltransferase C3, known to selectively ADP-ribosylate rho p21 and to impair its function, in the cytoplasmic division using Xenopus embryos. The sperm-induced cytoplasmic division of Xenopus embryos was not affected by microinjection into the embryos of either smg GDS or the guanosine-5'-(3-O-thio)triphosphate (GTP gamma S)-bound form of rhoA p21, one member of the rho family, but completely inhibited by microinjection of rho GDI or C3. Under these conditions, nuclear division occurred normally but the furrow formation, which was induced by the contractile ring consisting of actomyosin just beneath the plasma membrane, was impaired. Comicroinjection of rho GDI with the GTP gamma S-bound form of rhoA p21 prevented the rho GDI action. Moreover, the sperm-induced cytoplasmic division of Xenopus embryos was inhibited by microinjection into the embryos of the rhoA p21 pre-ADP-ribosylated by C3 which might serve as a dominant negative inhibitor of endogenous rho p21. These results indicate that rho p21 together with its regulatory proteins regulates the cytoplasmic division through the actomyosin system.
authors.affiliation: Department of Biochemistry, Kobe University School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kishi
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
authors.forename: S
authors.initials: S
authors.lastname: Kuroda
authors.forename: T
authors.initials: T
authors.lastname: Itoh
authors.forename: Y
authors.initials: Y
authors.lastname: Takai
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism*; D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000818:Animals; D001905:Botulinum Toxins; D002455:Cell Division; D002970:Cleavage Stage, Ovum / Q000502:physiology* / Q000648:ultrastructure; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D020730:Guanine Nucleotide Dissociation Inhibitors; D008845:Microinjections; D011499:Protein Processing, Post-Translational; D013329:Structure-Activity Relationship; D014982:Xenopus laevis / Q000196:embryology*; D020692:rab3 GTP-Binding Proteins; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020742:rhoA GTP-Binding Protein
chemical_list: D020730:Guanine Nucleotide Dissociation Inhibitors; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein