title: The p53-inducible E3 ubiquitin ligase p53RFP induces p53-dependent apoptosis.
abstract: Recently, it has been shown that really interesting new gene (RING)-in between ring finger (IBR)-RING domain-containing proteins, such as Parkin and Parc, are E3 ubiquitin ligases and are involved in regulation of apoptosis. In this report, we show that p53-inducible RING-finger protein (p53RFP), a p53-inducible E3 ubiquitin ligase, induces p53-dependent but caspase-independent apoptosis. p53RFP contains an N-terminal RING-IBR-RING domain and an uncharacterized, evolutionally highly conserved C-terminal domain. p53RFP interacts with E2 ubiquitin-conjugating enzymes UbcH7 and UbcH8 but not with UbcH5, and this interaction is mediated through the RING-IBR-RING domain of p53RFP. Interestingly, the conserved C-terminal domain of p53RFP is required and sufficient for p53RFP-mediated apoptosis, suggesting p53RFP-mediated apoptosis does not require its E3 ubiquitin ligase activity. Together with a recent report showing that p53RFP is involved in ubiquitination and degradation of p21, a p53 downstream protein promoting growth arrest and antagonizing apoptosis, our findings suggest that p53RFP is involved in switching a cell from p53-mediated growth arrest to apoptosis.
authors.affiliation: Department of Cell Biology and Genetics, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.forename: Liang-Guo
authors.initials: LG
authors.lastname: Xu
authors.forename: Ting
authors.initials: T
authors.lastname: Liu
authors.forename: Zhonghe
authors.initials: Z
authors.lastname: Zhai
authors.forename: Hong-Bing
authors.initials: HB
authors.lastname: Shu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D014166:Transferases; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D016159:Tumor Suppressor Protein p53; C400192:Cul9 protein, human; D014166:Transferases; C079437:UBE2L3 protein, human; C471622:UBE2L6 protein, human; D044763:Ubiquitin-Conjugating Enzymes; C508914:RNF144B protein, human; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; D020169:Caspases