Jung Haiyoung, Seong Hyun-A, Ha Hyunjung
Department of Biochemistry, Biotechnology Research Institute, School of Life Sciences, Chungbuk National University, Cheongju 361-763, Republic of Korea.
J Biol Chem. 2007 Nov 30;282(48):35293-307. doi: 10.1074/jbc.M705181200. Epub 2007 Oct 3.
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.
p53在多种生长抑制反应中发挥关键作用,包括细胞周期停滞、分化和凋亡,并有助于肿瘤抑制。在此我们表明,NM23-H1及其结合伴侣STRAP(丝氨酸-苏氨酸激酶受体相关蛋白)与p53相互作用并增强p53活性。NM23-H1和STRAP均直接与113 - 290位残基内的中央DNA结合域相互作用。使用NM23-H1和STRAP突变体表明,NM23-H1的Cys(145)以及STRAP的Cys(152)(或Cys(270))负责与p53结合。此外,p53的Cys(176)和Cys(135)分别是结合NM23-H1和STRAP所必需的。野生型NM23-H1和STRAP而非NM23-H1(C145S)和STRAP(C152S/C270S)的异位表达以剂量依赖方式正向调节p53介导的转录。内源性NM23-H1或STRAP的敲低产生相反趋势并抑制p53介导的转录。同样,NM23-H1和STRAP刺激p53诱导的凋亡和生长抑制,而NM23-H1(C145S)和STRAP(C152S/C270S)突变体则无作用。我们还证明,NM23-H1和STRAP对p53的激活是通过从p53-Mdm2复合物中去除p53的负调节因子Mdm2介导的。这些结果表明,NM23-H1及其相互作用伴侣STRAP与p53发生物理相互作用并正向调节其功能,包括p53诱导的凋亡和细胞周期停滞。