The in vivo role of the Mdm2-MdmX interaction in p53 regulation

Mdm2-MdmX 相互作用在 p53 调节中的体内作用

• 批准号: 8680038
• 负责人: YANPING ZHANG
• 金额: $ 29.67万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8680038
• 关键词: Acetylation; Address; Affect; Alanine; Amino Acids; Apoptosis; Binding; Biochemical; Cell Cycle Arrest; Cells; Collection; Comparative Study; Development; Embryo; Embryonic Development; Fingers; Gene Targeting; Genetic; Goals; Heterodimerization; Homo; Homologous Gene; Homologous Protein; In Vitro; Investigation; Knock-in Mouse; Knockout Mice; Mediating; Modeling; Mus; Mutant Strains Mice; Mutation; Nuclear Export; Positioning Attribute; Process; Protein p53; Proteins; Regulation; Role; Stress; TP53 gene; Testing; Therapeutic; Therapeutic Agents; Transactivation; Tumor Suppressor Genes; Tyrosine; Ubiquitin; Ubiquitination; biological adaptation to stress; cancer therapy; experience; in vivo; insight; mdm2 protein; mouse model; mutant; novel; senescence; tool; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): TP53 is a critical tumor suppressor gene capable of inducing cell cycle arrest, senescence, and apoptosis. Canonically, the primary negative regulator of the TP53 protein product p53, Mdm2, is considered to regulate p53 through two mechanisms; 1) through direct binding to the p53 transactivation domain, suppressing p53 activity, and 2) through functioning as an E3 ubiquitin ligase capable of ubiquitinating p53, targeting it for nuclear export and degradation. In addition to Mdm2, a homologous protein, MdmX also functions in p53 regulation, primarily through binding and blocking the p53 transactivation domain in a similar mechanism to Mdm2. Both Mdm2 and MdmX knockout mice are embryonically lethal, and rescued completely with concomitant deletion of p53, indicative of their critical role in p53 regulation. The development of an Mdm2C462A knock-in mouse model that maintains Mdm2-p53 binding, but disrupts Mdm2 E3 ligase activity, was found to result in embryonic lethality, rescued with simultaneous deletion of p53. Surprisingly, this study suggests that Mdm2-p53 binding alone is not sufficient for p53 regulation, and implicates the Mdm2 RING finger domain as critical in p53 regulation. Along with disrupting Mdm2 E3 ubiquitin activity, the mutation also disrupts Mdm2-MdmX heterodimerization. Because the Mdm2C462A mutation disrupts both functions of the RING finger domain, the E3 ubiquitin ligase activity and the MdmX binding, it cannot be deduced which of these changes is causing the observed misregulation of p53. Despite intensive study, much remains unknown about how Mdm2 and MdmX function in vivo to regulate p53. In vitro this binding has been demonstrated to amplify or rescue Mdm2 E3 ligase activity towards p53, but its role in vivo is not yet clear. Recent development of an Mdm2Y487A knock-in mouse, which maintains the ability to bind to MdmX and p53, but has disrupted E3 ubiquitin ligase activity has allowed for the separation of these two Mdm2 RING finger domain functions. Through utilizing this model, we hope to further elucidate the function of the Mdm2 RING finger domain in p53 regulation, as further understanding p53 regulation is critical in the development of effective therapeutics.

描述（由申请人提供）：TP 53是一种重要的肿瘤抑制基因，能够诱导细胞周期停滞、衰老和凋亡。通常，TP 53蛋白产物p53的主要负调节因子Mdm 2被认为通过两种机制调节p53; 1）通过直接结合p53反式激活结构域，抑制p53活性，和2）通过作为能够泛素化p53的E3泛素连接酶，靶向其用于核输出和降解。除了同源蛋白Mdm 2之外，MdmX还在p53调节中起作用，主要通过与Mdm 2类似的机制结合和阻断p53反式激活结构域。Mdm 2和MdmX基因敲除小鼠都是胚胎致死的，并且伴随着p53的缺失而完全获救，这表明它们在p53调节中的关键作用。发现维持Mdm 2-p53结合但破坏Mdm 2 E3连接酶活性的Mdm 2C 462 A敲入小鼠模型的开发导致胚胎致死，用同时缺失p53挽救。令人惊讶的是，这项研究表明，Mdm 2-p53结合单独是不够的p53调控，并暗示Mdm 2环指结构域作为关键的p53调控。沿着破坏Mdm 2 E3泛素活性，该突变也破坏Mdm 2-MdmX异源二聚化。由于Mdm 2C 462 A突变破坏了RING指结构域的功能，E3泛素连接酶活性和MdmX结合，因此无法推断这些变化中的哪一个导致了观察到的p53的失调。尽管进行了深入的研究，但关于Mdm 2和MdmX如何在体内调节p53的功能仍有很多未知之处。在体外，这种结合已被证明放大或拯救Mdm 2 E3连接酶对p53的活性，但其在体内的作用尚不清楚。最近开发的Mdm 2 Y 487 A敲入小鼠保持了与MdmX和p53结合的能力，但破坏了E3泛素连接酶活性，这使得这两个Mdm 2 RING指结构域功能分离。通过利用该模型，我们希望进一步阐明 P53调控中的Mdm 2 RING指结构域，因为进一步理解P53调控在开发有效疗法中至关重要。