title: Negative regulation of HDM2 to attenuate p53 degradation by ribosomal protein L26.
abstract: HDM2 is a p53-specific E3 ubiquitin ligase. Its overexpression leads to excessive inactivation of tumor protein p53, diminishing its tumor suppressor function. HDM2 also affects the cell cycle, apoptosis and tumorigenesis through interacting with other molecules, including several ribosomal proteins. To identify novel HDM2 regulators, we performed a yeast two-hybrid screening using HDM2 as bait. Among the candidates, ribosomal protein L26 (RPL26) was characterized as a novel HDM2-interactor. The interaction between HDM2 and RPL26 was further validated by in vivo and in vitro assays. RPL26 modulates the HDM2-p53 interaction by forming a ternary complex among RPL26, HDM2 and p53, which stabilize p53 through inhibiting the ubiquitin ligase activity of HDM2. The ribosomal stress caused by a low dose of Act D enhances RPL26-HDM2 interaction and activates p53. Overexpression of RPL26 results in activating of p53, inhibits cell proliferation and induces a p53-dependent cell cycle arrest. These results provide a novel regulatory mechanism of RPL26 to activate p53 by inhibiting HDM2.
authors.affiliation: State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 102206, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Yanzhi
authors.initials: Y
authors.lastname: Yuan
authors.forename: Wanqiao
authors.initials: W
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Guan
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Wu
authors.forename: Chaozhi
authors.initials: C
authors.lastname: Jin
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Lingqiang
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yang
authors.forename: Fuchu
authors.initials: F
authors.lastname: He
mesh_terms: D000818:Animals; D002453:Cell Cycle; D049109:Cell Proliferation; D002478:Cells, Cultured; D003609:Dactinomycin / Q000494:pharmacology; D006801:Humans; D051379:Mice; D054730:Protein Interaction Domains and Motifs; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: C489216:RPL26 protein, human; D012269:Ribosomal Proteins; D016159:Tumor Suppressor Protein p53; D003609:Dactinomycin; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2