Analysis of p53 in vivo using unique mouse model

描述（由申请人提供）：为了研究p53在基因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p53ER TAMfusion蛋白的基因所取代。在这些动物和来源于它们的细胞中，野生型p53功能的能力似乎完全依赖于合成激活配体4-羟他莫昔芬的供应。我们将对该模型进行验证和优化，并利用该模型确定p53状态在体外细胞DNA损伤和癌基因激活反应中的作用、依赖性和时机。我们还将确定持续或偶发性p53功能恢复在体内对DNA损伤的反应以及在淋巴和皮肤肿瘤的预防和消退中的功效。MDM2和MDMX蛋白是p53的关键调节因子，除非p53也缺失，否则p53的缺失会导致早期胚胎死亡。我们将使用可切换p53ER的TAMKI小鼠来建立MDM2/MDMX依赖于p53状态的机制和时间，并探索这两种蛋白的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p53与其MDM2和MDMX调节因子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.