title: NM23-H1 tumor suppressor and its interacting partner STRAP activate p53 function.
abstract: p53 plays a critical role in a variety of growth inhibitory responses, including cell cycle arrest, differentiation, and apoptosis, and contributes to tumor suppression. Here we show that NM23-H1 and its binding partner STRAP (serine-threonine kinase receptor-associated protein) interact with p53 and potentiate p53 activity. Both NM23-H1 and STRAP directly interact with the central DNA binding domain within residues 113-290. The use of NM23-H1 and STRAP mutants revealed that Cys(145) of NM23-H1 and Cys(152) (or Cys(270)) of STRAP were responsible for p53 binding. Furthermore, Cys(176) and Cys(135) of p53 were required to bind NM23-H1 and STRAP, respectively. Ectopic expression of wild-type NM23-H1 and STRAP, but not NM23-H1(C145S) and STRAP(C152S/C270S), positively regulated p53-mediated transcription in a dose-dependent manner. Knockdown of endogenous NM23-H1 or STRAP produced an opposite trend and inhibited the p53-mediated transcription. Similarly, NM23-H1 and STRAP stimulated p53-induced apoptosis and growth inhibition, whereas the NM23-H1(C145S) and STRAP(C152S/C270S) mutants had no effect. We also demonstrated that p53 activation by NM23-H1 and STRAP was mediated by removing Mdm2, a negative regulator of p53, from the p53-Mdm2 complex. These results suggest that NM23-H1 and its interacting partner STRAP physically interact with p53 and positively regulate its functions, including p53-induced apoptosis and cell cycle arrest.
authors.affiliation: Department of Biochemistry, Biotechnology Research Institute, School of Life Sciences, Chungbuk National University, Cheongju 361-763, Republic of Korea.
authors.forename: Haiyoung
authors.initials: H
authors.lastname: Jung
authors.forename: Hyun-A
authors.initials: HA
authors.lastname: Seong
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Ha
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry; D003593:Cytoplasm / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D009154:Mutation; D054778:NM23 Nucleoside Diphosphate Kinases / Q000378:metabolism / Q000502:physiology*; D011506:Proteins / Q000378:metabolism*; D016601:RNA-Binding Proteins; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D054778:NM23 Nucleoside Diphosphate Kinases; D011506:Proteins; D016601:RNA-Binding Proteins; C116758:STRAP protein, mouse; D016159:Tumor Suppressor Protein p53; D025801:Ubiquitin; D003545:Cysteine