title: Phosphorylation of RhoB by CK1 impedes actin stress fiber organization and epidermal growth factor receptor stabilization.
abstract: RhoB is a small GTPase implicated in cytoskeletal organization, EGF receptor trafficking and cell transformation. It is an immediate-early gene, regulated at many levels of its biosynthetic pathway. Herein we show that the serine/threonine protein kinase CK1 phosphorylates RhoB in vitro but not RhoA or RhoC. With the use of specific CK1 inhibitors, IC261 and D4476, we show that the kinase phosphorylates also RhoB in HeLa cells. Mass spectrometry analysis demonstrates that RhoB is monophosphorylated by CK1, in its C-terminal end, on serine 185. The substitution of Ser185 by Ala dramatically inhibited the phosphorylation of RhoB in cultured cells. Lastly we show that the inhibition of CK1 activates RhoB and promotes RhoB dependent actin fiber formation and EGF-R level. Our data provide the first demonstration of RhoB phosphorylation and indicate that this post-translational maturation would be a novel critical mechanism to control the RhoB functions.
authors.affiliation: INSERM, U563, CPTP, Département Innovation Thérapeutique et Oncologie Moléculaire, Toulouse F-31052, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Tillement
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lajoie-Mazenc
authors.forename: Anne
authors.initials: A
authors.lastname: Casanova
authors.forename: Carine
authors.initials: C
authors.lastname: Froment
authors.forename: Marie
authors.initials: M
authors.lastname: Penary
authors.forename: Daniel
authors.initials: D
authors.lastname: Tovar
authors.forename: Rudolfo
authors.initials: R
authors.lastname: Marquez
authors.forename: Bernard
authors.initials: B
authors.lastname: Monsarrat
authors.forename: Gilles
authors.initials: G
authors.lastname: Favre
authors.forename: Anne
authors.initials: A
authors.lastname: Pradines
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence / Q000502:physiology; D019943:Amino Acid Substitution / Q000502:physiology; D048128:Casein Kinase Ialpha / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D022502:Stress Fibers / Q000378:metabolism* / Q000648:ultrastructure; D020743:rhoB GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000199:Actins; D004791:Enzyme Inhibitors; D012694:Serine; D066246:ErbB Receptors; D048128:Casein Kinase Ialpha; D017346:Protein Serine-Threonine Kinases; D020743:rhoB GTP-Binding Protein