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: 8468671
• 负责人: YANPING ZHANG
• 金额: $ 28.5万
• 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/8468671
• 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）：TP53是一种关键的抑制肿瘤基因，能够诱导细胞周期停滞，衰老和凋亡。从规范上讲，TP53蛋白产物P53，MDM2的主要负调节剂被认为可以通过两种机制调节p53。 1）通过直接结合p53反式激活结构域，抑制p53活性，2）通过充当E3泛素连接酶的功能，能够泛素p53，以核导出和降解为目标。除了MDM2（同源蛋白）外，MDMX还在p53调控中起作用，主要是通过与MDM2相似的机制结合和阻断p53反式激活域的结合和阻断。 MDM2和MDMX敲除小鼠均具有胚胎致死，并完全伴随p53的缺失，这表明它们在p53调节中的关键作用。发现维持MDM2-P53结合但破坏MDM2 E3连接酶活性的MDM2C462A敲入小鼠模型的发展导致胚胎致死性，并同时删除了p53。令人惊讶的是，这项研究表明，仅MDM2-P53结合不足以适应p53调节，并暗示MDM2环手指结构域在p53调节中至关重要。在破坏MDM2 E3泛素活性的同时，该突变还破坏了MDM2-MDMX异二聚化。由于MDM2C462A突变破坏了环手指结构域的两个功能，E3泛素连接酶活性和MDMX结合，因此不能推断出这些变化中的哪些变化导致观察到的p53造成误差。尽管进行了深入的研究，但对于MDM2和MDMX在体内如何调节p53的功能仍未清楚。在体外，这种结合已被证明可以扩增或拯救MDM2 E3连接酶对p53的活性，但其在体内的作用尚不清楚。 MDM2Y487A敲入小鼠的最新发展，该小鼠保持与MDMX和p53结合的能力，但已破坏了E3泛素连接酶活性，使这两个MDM2环手指域功能可以分离。通过利用此模型，我们希望进一步阐明 p53调节中的MDM2环形域，因为进一步了解p53调节对于有效疗法的发展至关重要。