title: Pirh2, a p53-induced ubiquitin-protein ligase, promotes p53 degradation.
abstract: The p53 tumor suppressor exerts anti-proliferative effects in response to various types of stress including DNA damage and abnormal proliferative signals. Tight regulation of p53 is essential for maintaining normal cell growth and this occurs primarily through posttranslational modifications of p53. Here, we describe Pirh2, a gene regulated by p53 that encodes a RING-H2 domain-containing protein with intrinsic ubiquitin-protein ligase activity. Pirh2 physically interacts with p53 and promotes ubiquitination of p53 independently of Mdm2. Expression of Pirh2 decreases the level of p53 protein and abrogation of endogenous Pirh2 expression increases the level of p53. Furthermore, Pirh2 represses p53 functions including p53-dependent transactivation and growth inhibition. We propose that Pirh2 is involved in the negative regulation of p53 function through physical interaction and ubiquitin-mediated proteolysis. Hence, Pirh2, like Mdm2, participates in an autoregulatory feedback loop that controls p53 function.
authors.affiliation: Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9.
authors.forename: Roger P
authors.initials: RP
authors.lastname: Leng
authors.forename: Yunping
authors.initials: Y
authors.lastname: Lin
authors.forename: Weili
authors.initials: W
authors.lastname: Ma
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Benedicte
authors.initials: B
authors.lastname: Lemmers
authors.forename: Stephen
authors.initials: S
authors.lastname: Chung
authors.forename: John M
authors.initials: JM
authors.lastname: Parant
authors.forename: Guillermina
authors.initials: G
authors.lastname: Lozano
authors.forename: Razqallah
authors.initials: R
authors.lastname: Hakem
authors.forename: Samuel
authors.initials: S
authors.lastname: Benchimol
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002461:Cell Line, Transformed; D015971:Gene Expression Regulation, Enzymologic; D016153:Genes, Suppressor; D006801:Humans; D007438:Introns; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53; D014452:Ubiquitins; D044767:Ubiquitin-Protein Ligases; D008025:Ligases