Analysis of p53 in vivo using unique mouse model

描述（由申请人提供）：为了研究p53在响应遗传毒性损伤和肿瘤发生中的作用，我们构建了一种独特的敲入小鼠，其中内源性p53基因被编码p53 ER TAM融合蛋白的基因所取代。在这些动物中，以及在从它们衍生的细胞中，野生型p53功能的能力似乎完全依赖于合成活化配体4-羟基他莫昔芬的供应。我们将验证和优化这个模型，并使用它来建立的作用，依赖性和时间的p53状态在体外细胞中的DNA损伤和癌基因激活的反应。我们还将确定持续或间歇性p53功能恢复在体内对DNA损伤的反应以及淋巴和皮肤肿瘤的预防和消退的功效。MDM 2和MDMX蛋白是p53的关键调节因子，除非p53也不存在，否则其损失导致早期胚胎致死。我们将使用我们的可转换p53 ER TAMKI小鼠来建立MDM 2/MDMX对p53状态的依赖性的机制和时间，并探索两种蛋白质的p53独立功能。我们的模型将为p53介导的肿瘤抑制的机制、时间和持续时间提供独特的见解，以及关于p53与其MDM 2和MDMX调节剂之间关系的独特信息。

DESCRIPTION (provided by applicant): To investigate the role of p53 in response to genotoxic damage and oncogenesis we have constructed a unique knock-in mouse in which the endogenous p53 gene has been replace with one encoding a p53ER TAMfusion protein. In such animals, and in cells derived from them, competence for wild type p53 function appears to be completely dependent upon supply of the synthetic activating ligand 4-hydroxytamoxifen. We will validate and optimize this model and use it to establish the role, dependence and timing of p53 status in the response to DNA damage and oncogene activation in cells in vitro. We will also determine the efficacy of sustained or episodic p53 functional restoration in vivo in the response to DNA damage and in the prevention and regression of lymphoid and skin tumors. MDM2 and MDMX proteins are critical regulators of p53 whose loss leads to early embryonic lethality unless p53 is also absent. We will use our switchable p53ER TAMKI mice to establish the mechanism and timing of the dependency of MDM2/MDMX on p53 status and to explore p53 independent functions of both proteins. Our model will provide unique insights into the mechanism, timing and duration of p53-mediated tumor suppression as well unique information on the relationship between p53 and its MDM2 and MDMX regulators.