title: The small GTPase Rho3 and the diaphanous/formin For3 function in polarized cell growth in fission yeast.
abstract: We identified a novel Rho gene rho3(+) and studied its interaction with diaphanous/formin for3(+) in the fission yeast Schizosaccharomyces pombe. Both rho3 null cells and for3 null cells showed defects in organization of not only actin cytoskeleton but also cytoplasmic microtubules (MTs). rho3 for3 double null cells had defects that were more severe than each single null cell: polarized growth was deficient in the double null cells. Function of For3 needed the highly conserved FH1 and FH2 domains, an N-terminal region containing a Rho-binding domain, and the C-terminal region. For3 bound to active forms of both Rho3 and Cdc42 but not to that of Rho1. For3 was localized as dots to the ends of interphase cells and to the mid-region in dividing cells. This localization was probably dependent on its interaction with Rho proteins. Overexpression of For3 produced huge swollen cells containing depolarized F-actin patches and thick cytoplasmic MT bundles. In addition, overexpression of a constitutively active Rho3Q71L induced a strong defect in cytokinesis. In conclusion, we propose that the Rho3-For3 signaling system functions in the polarized cell growth of fission yeast by controlling both actin cytoskeleton and MTs.
authors.affiliation: Division of Biology, Department of Life Sciences, Graduate Program of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan. cnakano@bio.c.u-tokyo.ac.jp
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nakano
authors.forename: Jun
authors.initials: J
authors.lastname: Imai
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Arai
authors.forename: Akio
authors.initials: A
authors.lastname: Toh-E
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Matsui
authors.forename: Issei
authors.initials: I
authors.lastname: Mabuchi
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D016764:Cell Polarity; D000080865:Formins; D015966:Gene Expression Regulation, Fungal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D009154:Mutation; D011485:Protein Binding; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C444419:FOR3 protein, S pombe; D000080865:Formins; D029702:Schizosaccharomyces pombe Proteins; C489566:rho3 protein, S pombe; D020741:rho GTP-Binding Proteins