title: Mitotic kinase Aurora-A phosphorylates RASSF1A and modulates RASSF1A-mediated microtubule interaction and M-phase cell cycle regulation.
abstract: RASSF1A (RAS-association domain family 1, isoform A) is a newer tumor suppressor that binds to and stabilizes microtubules as well as induces M-phase cell cycle arrest. Several other proteins that interact with and stabilize microtubules also undergo mitotic phase phosphorylation to regulate microtubule dynamics and M-phase cell cycle progression. Currently, however, there is a paucity of information regarding the phosphorylation status of RASSF1A and its regulation during mitosis. In this study, for the first time, we demonstrate that Aurora-A is a RASSF1A kinase and, to the best of our knowledge, this is also the first study reporting the identification of a kinase for RASSF1A. We show that the mitotic kinase Aurora-A directly interacts with and phosphorylates RASSF1 and that RASSF1A is phosphorylated by Aurora-A during mitosis. These findings therefore link an important oncogenic mitotic kinase to regulate RASSF1A tumor suppressor. Aurora-A appears to phosphorylate RASSF1A at Threonine202 and/or Serine203 that reside within the known microtubule-binding domain of RASSF1A. Substitutions of these residues with glutamic acid at both positions, mimicking constitutive phosphorylation of RASSF1A, disrupt RASSF1A interactions with microtubules and abolish its ability to induce M-phase cell cycle arrest. Our results further demonstrate that Aurora-A overexpression also interferes with RASSF1A-mediated growth suppression. In view of our results, we propose that Aurora-A-mediated phosphorylation of RASSF1A is a novel mechanism that regulates the ability of this tumor suppressor to interact with microtubules and modulate M-phase cell cycle progression.
authors.affiliation: Department of Pharmacology, State University of New York, Upstate Medical University, Syracuse, NY 13210, USA.
authors.forename: R
authors.initials: R
authors.lastname: Rong
authors.forename: L Y
authors.initials: LY
authors.lastname: Jiang
authors.forename: M S
authors.initials: MS
authors.lastname: Sheikh
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
mesh_terms: D064127:Aurora Kinases; D002453:Cell Cycle / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D006801:Humans; D047468:Immunoprecipitation; D008870:Microtubules / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000737:chemistry / Q000235:genetics; D013912:Threonine / Q000737:chemistry / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins; D013912:Threonine; D012694:Serine; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases