title: p63 maintains keratinocyte proliferative capacity through regulation of Skp2-p130 levels.
abstract: p63 is a master regulator of proliferation and differentiation in stratifying epithelia, and its expression is frequently altered in carcinogenesis. However, its role in maintaining proliferative capacity remains unclear. Here, we demonstrate that hypoproliferation and loss of differentiation in organotypic raft cultures of primary neonatal human foreskin keratinocytes (HFKs) depleted of the α and β isoforms of p63 result from p53-p21-mediated accumulation of retinoblastoma (Rb) family member p130. Hypoproliferation in p63-depleted HFKs can be rescued by depletion of p53, p21(CIP1) or p130. Furthermore, we identified the gene encoding S-phase kinase-associated protein 2 (Skp2), the recognition component of the SCF(Skp2) E3 ubiquitin ligase, as a novel target of p63, potentially influencing p130 levels. Expression of Skp2 is maintained by p63 binding to a site in intron 2 and mRNA levels are downregulated in p63-depleted cells. Hypoproliferation in p63-depleted cells can be restored by re-expression of Skp2. Taken together, these results indicate that p63 plays a multifaceted role in maintaining proliferation in the mature regenerating epidermis, in addition to being required for differentiation.
authors.affiliation: Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Science, Queen's University Belfast, Belfast BT9 7BL, UK.
authors.forename: Simon S
authors.initials: SS
authors.lastname: McDade
authors.forename: Daksha
authors.initials: D
authors.lastname: Patel
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: McCance
mesh_terms: D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism*; D020033:Protein Isoforms; D050717:Retinoblastoma-Like Protein p130 / Q000378:metabolism*; D044786:S-Phase Kinase-Associated Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D020033:Protein Isoforms; D050717:Retinoblastoma-Like Protein p130; D044786:S-Phase Kinase-Associated Proteins; C115051:TP63 protein, human; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins