title: c-Jun phosphorylation by the human vaccinia-related kinase 1 (VRK1) and its cooperation with the N-terminal kinase of c-Jun (JNK).
abstract: The VRK1 kinase is a novel Ser-Thr kinase in the human kinome that diverged from the casein kinase 1 branch. These kinases phosphorylate transcription factors related to stress responses, such as p53. In this report we have studied the phosphorylation of the transcription factor c-Jun in its N-terminal region. The VRK1 protein phosphorylates c-Jun with a Km of 0.4 muM, and is not inhibited by SP600125. VRK1 phosphorylates c-Jun in Ser63 and Ser73 in vitro, the same residues targeted by the N-terminal kinase of c-Jun (JNK). This phosphorylation induces the stabilization and accumulation of the c-Jun protein. VRK1 phosphorylates the endogenous c-Jun in Ser63. VRK1 activates c-Jun dependent transcription, which is dependent on phosphorylation of Ser63 and Ser73. The c-Jun with Ser63Ala and Ser73Ala substitutions is not transcriptionally active when cotransfected with VRK1. VRK1 interacts with c-Jun but not with JNK. The cotransfection of VRK1 and JNK has an additive effect on the transcriptional activation of c-Jun indicating that they can cooperate when both are at suboptimal dose; otherwise, maximum effect by one of them prevents the effect of the other. The VRK1-c-Jun connection represents a component of a new signaling pathway whose upstream elements remain to be identified.
authors.affiliation: Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas-Universidad de Salamanca, Campus Miguel de Unamuno, E-37007 Salamanca, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Sevilla
authors.forename: Claudio R
authors.initials: CR
authors.lastname: Santos
authors.forename: Ramiro
authors.initials: R
authors.lastname: Barcia
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Vega
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Lazo
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000939:Epitopes / Q000737:chemistry; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009154:Mutation; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D014158:Transcription, Genetic; D014162:Transfection; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000873:Anthracenes; D004791:Enzyme Inhibitors; D000939:Epitopes; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D016755:Proto-Oncogene Proteins c-jun; D011993:Recombinant Fusion Proteins; C432165:pyrazolanthrone; D012694:Serine; D005982:Glutathione Transferase; D017346:Protein Serine-Threonine Kinases; C109890:VRK1 protein, human; D014357:Trypsin