title: SCF TrCP1 activates and ubiquitylates TAp63gamma.
abstract: p63 is a member of the p53 tumor suppressor family that is critical for epithelial differentiation and also has an important role in cancer progression. Currently, the molecular mechanisms governing regulation of p63 function remain largely unclear. This study identifies a unique E3 ubiquitin ligase for p63, SCF(betaTrCP1). SCF(betaTrCP1) is able to bind p63gamma isoforms, with a higher affinity for the TAp63gamma isoform. Strikingly, co-expression of TAp63gamma and betaTrCP1 leads to the stabilization of TAp63gamma. This stabilization of TAp63gamma leads to up-regulation of p21 at the mRNA and protein level by increased binding of TAp63gamma at the p21 promoter. The up-regulation of p21 causes a subsequent increase in G(1) phase cell cycle arrest. Last, SCF(betaTrCP1) is able to ubiquitylate TAp63gamma, and this ubiquitylation, as well as the increased activity of TAp63gamma, is ablated with the expression of a ubiquitin-deficient mutant of betaTrCP1 (DeltaFbetaTrCP1). Therefore, our study reveals that SCF(betaTrCP1) is an E3 ligase that activates p63 through ubiquitylation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239.
authors.forename: Jayme R
authors.initials: JR
authors.lastname: Gallegos
authors.affiliation: Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239.
authors.forename: Joel
authors.initials: J
authors.lastname: Litersky
authors.affiliation: Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239.
authors.forename: Hunjoo
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan 48109.
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan; CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Nakayama
authors.affiliation: Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan; Department of Developmental Biology, Center for Translational and Advanced Animal Research, Graduate School of Medicine, Tohoku University, 2-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Nakayama
authors.affiliation: Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239; Department of Biochemistry and Molecular Biology, University of Indiana, Indianapolis, Indiana 46202. Electronic address: hualu@iupui.edu.
authors.forename: Hua
authors.initials: H
authors.lastname: Lu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008954:Models, Biological; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D015854:Up-Regulation
chemical_list: D004268:DNA-Binding Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases