title: p53 mediates the negative regulation of MDM2 by orphan receptor TR3.
abstract: MDM2 is an oncoprotein whose transforming potential is activated by overexpression. The expression level of MDM2 is negatively regulated by orphan receptor TR3 that mainly acts as a transcriptional factor to regulate gene expression. However, the underlying mechanism is largely unclear. Here, we present the first evidence that inhibition of TR3 on MDM2 is mediated by p53. We found that TR3 directly interacts with p53 but not MDM2, and such interaction is critical for TR3 to inhibit MDM2 expression. TR3 downregulates p53 transcriptional activity by blocking its acetylation, leading to a decrease on the transcription level of MDM2. Furthermore, TR3 binding to p53 obstructs its ubiquitination and degradation induced by MDM2, resulting in the MDM2 ubiquitination and degradation. In addition, TR3 could enhance p53-mediated apoptosis induced by UV irradiation. Taken together, our findings demonstrate that p53 mediates the suppression of TR3 on MDM2 at both transcriptional and post-transcriptional level and suggest TR3 as a potential target to develop new anticancer agents that restrict MDM2-induced tumor progression.
authors.affiliation: Key Laboratory of the Ministry of Education for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen 361005, Fujian, China.
authors.forename: Bi-xing
authors.initials: BX
authors.lastname: Zhao
authors.forename: Hang-zi
authors.initials: HZ
authors.lastname: Chen
authors.forename: Na-zi
authors.initials: NZ
authors.lastname: Lei
authors.forename: Gui-deng
authors.initials: GD
authors.lastname: Li
authors.forename: Wen-xiu
authors.initials: WX
authors.lastname: Zhao
authors.forename: Yan-yan
authors.initials: YY
authors.lastname: Zhan
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Sheng-cai
authors.initials: SC
authors.lastname: Lin
authors.forename: Qiao
authors.initials: Q
authors.lastname: Wu
mesh_terms: D015536:Down-Regulation; D006801:Humans; D008954:Models, Biological; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D016159:Tumor Suppressor Protein p53; D025801:Ubiquitin; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2