Analysis of p53 in vivo using unique mouse model

描述(申请人提供)：为了研究p53在应对遗传毒性损伤和肿瘤发生中的作用，我们构建了一个独特的敲入小鼠，在该小鼠中，内源性p53基因已被编码p53ER TAMFusion蛋白的基因取代。在这些动物中，以及从这些动物衍生的细胞中，野生型P53功能的能力似乎完全依赖于合成激活配体4-羟基三苯氧胺的供应。我们将验证和优化这一模型，并利用它来确定P53状态在体外细胞对DNA损伤和癌基因激活的反应中的作用、依赖性和时机。我们还将确定体内持续的或间歇性的P53功能恢复在应对DNA损伤以及预防和消退淋巴系和皮肤肿瘤方面的有效性。MDM2和MDMX蛋白是P53的关键调节因子，它们的缺失会导致早期胚胎死亡，除非P53也缺失。我们将使用我们的可切换的p53ER 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，以及关于P53与其MDM2和MDMX调节因子之间的关系的独特信息。

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.