The role of ATR in preventing age-related diseases

描述(由申请人提供)：长期以来，基因组完整性的逐渐丧失一直被认为是导致衰老过程的原因。与这一理论一致的是，参与维持基因组完整性的基因突变往往会导致过早衰老。识别与年龄相关的疾病的潜在遗传易感性，以及更重要的是，了解这些遗传决定因素如何导致疾病，可能会指导我们更好地预测、诊断和减缓这些疾病的发生。ATR蛋白激酶在哺乳动物细胞中维持基因组的完整性，是细胞周期检查点的中央调节因子。使用允许2-3月龄成年小鼠有条件地删除ATR基因的cre/lox系统，我们的初步工作表明，在ATR缺失3-6个月后，一些与年龄相关的表型出现。这些衰老表型包括脱发、头发花白、后凸、骨质疏松症、心肌病、睾丸萎缩和急性免疫抑制。通过这一独特的小鼠模型，我们建议在此证实这些初步发现，并进一步探索ATR在预防年龄相关疾病中的作用。建议进行实验，以进一步探讨ATR缺失对人类衰老的几个组成部分(脱发和衰老、骨质疏松症和造血再生能力降低)的影响，以及重要的是，解决这些表型是否是由ATR缺失后再生能力丧失和/或对分化细胞的直接影响引起的。为了确定p53转录因子的激活是否在ATR缺失导致的与年龄相关的表型中起作用，将ATR小鼠中观察到的过早衰老与ATR和P53缺失的小鼠进行比较。最后，建议进行实验，以确定正常代谢过程造成的氧化DNA碱基损伤是否会因ATR丢失而加剧，从而导致剧毒的DNA双链断裂。这种DNA损伤的放大可能会加速正常衰老。为了验证这一假设，通过调节ATR基因敲除细胞内羟基自由基浓度的处理将减少或增加DNA氧化损伤，这些处理的效果将通过染色体扩散分析进行监测。这些研究将寻求ATR缺失如何导致过早衰老的分子理解。

DESCRIPTION (provided by applicant): A gradual loss of genomic integrity has long been proposed to contribute to the aging process. Consistent with this theory, mutation of genes involved in maintaining genome integrity often leads to premature aging. Identifying the potential genetic predispositions to age-related diseases and, more importantly, understanding how these genetic determinants lead to disease will likely guide our ability to better predict, diagnose and slow the onset of these disorders. The ATR protein kinase maintains genome integrity in mammalian cells and is a central regulator of cell cycle checkpoints. Using a cre/lox system that allows conditional deletion of the ATR gene in 2-3 month old adult mice, our preliminary work has demonstrated that several age-related phenotypes appear 3-6 months after ATR deletion. These aging phenotypes include alopecia, hair graying, kyphosis, osteoporosis, cardiomyopathy, testicular atrophy and acute immune suppression. With this unique mouse model, we propose herein to substantiate these initial findings and further explore the role of ATR in preventing age-related diseases. Experiments are proposed to further explore the effect of ATR loss on several disorders that are components of human aging (hair loss and graying, osteoporosis and reduced hematopoietic regenerative capacity) and, importantly, to address if these phenotypes are caused by a loss of regenerative capacity following ATR deletion and/or a direct effect on differentiated cells. To determine if activation of the p53 transcription factor plays a causative role in age-related phenotypes that result from ATR deletion, the premature aging observed in ATR mice will be compared with that observed in mice that lack both ATR and p53. Finally, experiments are proposed that will determine whether the oxidative DNA base damage that results from normal metabolic processes is exacerbated by ATR loss, leading to highly toxic DNA double strand breaks. Such amplification of DNA damage may accelerate normal aging. To test this hypothesis, oxidative DNA damage will be reduced or increased by treatments that modulate intracellular hydroxyl radical concentrations in ATR knockout cells, and the effect of these treatments will be monitored by chromosome spread analysis. These studies will seek a molecular understanding of how ATR deletion leads to premature aging.