title: TIP60 represses transcriptional activity of p73beta via an MDM2-bridged ternary complex.
abstract: TIP60, a histone acetyl transferase, acts as a p53 coactivator by interfering with MDM2-mediated degradation of p53. However, little is known about its functional regulation of p73, which has structural features similar to p53. In this study we found that TIP60 represses apoptosis, which is induced by exogenous and endogenous p73beta. TIP60 also negatively regulated the expression of p73beta downstream target genes such as p21 and Bax. Moreover, the specific repression of p73beta-mediated transactivation by TIP60 was independent of p53 expression and not due to histone deacetylase recruiting transcriptional machinery. Transcriptional activities of both p73 splicing variants, p73alpha and p73beta, were also repressed by TIP60. Furthermore, TIP60 markedly enhanced p73beta binding affinity to MDM2 and physically associated with MDM2 through its zinc finger domain, which is specifically localized in the nucleus. Therefore, we demonstrate that TIP60 forms a ternary complex with p73beta, which is directly bridged by MDM2. It is important to note that our findings contribute to a functional linkage between TIP60 and p73beta through MDM2 in the transcriptional regulation of cellular apoptosis.
authors.affiliation: Department of Life Science, Chung-Ang University, Dongjak-Ku, Seoul, South Korea.
authors.forename: Jung-Woong
authors.initials: JW
authors.lastname: Kim
authors.forename: Peter I
authors.initials: PI
authors.lastname: Song
authors.forename: Mi-Hee
authors.initials: MH
authors.lastname: Jeong
authors.forename: Joo-Hee
authors.initials: JH
authors.lastname: An
authors.forename: So-Youn
authors.initials: SY
authors.lastname: Lee
authors.forename: Sang-Min
authors.initials: SM
authors.lastname: Jang
authors.forename: Ki-Hyun
authors.initials: KH
authors.lastname: Song
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Armstrong
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Choi
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D051548:Histone Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000074443:Lysine Acetyltransferase 5; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation / Q000235:genetics*; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C000606460:TP73 protein, human; C000606368:Trp73 protein, mouse; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; D051548:Histone Acetyltransferases; C098489:KAT5 protein, human; D000074443:Lysine Acetyltransferase 5; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2