The role of ATR in preventing age-related diseases

描述(申请人提供)：衰老通常可以被描述为组织结构、功能和再生能力的长期丧失。在之前的资助期间，我们使用一种新的系统在成年小鼠中删除ATR检查点激酶，探索了两个关键挑战对组织长期维持的影响。我们发现，1)通过干细胞磨损和复制需求的增加而耗尽再生潜力会加速年龄相关病理的出现，2)未能抑制高度受损细胞的积累主要会抑制组织再生。这种后一种机制被认为是一个组织更新检查点，在受损细胞被有效清除之前阻止再生。最后，我们的初步结果表明，延迟的更新紧随其后的是一个高度刺激的阶段，最终加速退化。在这里，我们建议通过定义促进复制相关DNA损伤的生理条件并将这种损伤与衰弱的干细胞潜力相关联来进一步发展这些研究领域。为了实现这一目标，亚型ATR抑制将被用来将瞬时复制异常转化为更长期的中间产物(双链断裂)。该系统将允许识别在代偿性更新过程中选择性地易受复制异常影响的细胞群体和基因组位置。此外，我们建议使用我们的ATR条件系统来表征DNA损伤细胞如何通过外部因素协调不同的再生阶段。这些因素包括抑制更新的因素和随后刺激更新的因素。总而言之，这些研究将确定如何调节补偿性更新的紧急事件，以及这些事件如何导致长期更新潜力的下降。 公共卫生相关性：在美国，年龄相关的病理是导致发病率和死亡率的主要因素。这些疾病的发生受到器官维护和组织再生的有效性的强烈影响。在这项建议中，我们描述了两个实验，以更好地确定随着年龄增长而减弱的再生潜力的原因，并研究在组织完整性急性丧失后用于组织更新的机制。

DESCRIPTION (provided by applicant): Aging can be generally characterized as the long-term loss of tissue architecture, function and regenerative capacity. In the previous funding period, we explored the effects of two key challenges to long-term tissue maintenance using a novel system to delete the ATR checkpoint kinase in adult mice. We showed 1) that exhaustion of regenerative potential through stem cell attrition and increased replicative demand accelerates the appearance of age-related pathologies, and 2) that failure to suppress the accumulation of highly-damaged cells can dominantly inhibit tissue regeneration. This later mechanism putatively serves as a tissue renewal checkpoint that prevents regeneration until damaged cells can be effectively cleared. Finally, our preliminary results indicate that delayed renewal is immediately followed by a highly stimulatory phase that ultimately accelerates degeneration. Herein, we propose to further develop these research areas by defining the physiological conditions that promote replication-associated DNA damage and correlating this damage with debilitated stem cell potential. To accomplish this goal, hypomorphic ATR suppression will be used to convert transient replication abnormalities into more long-lived intermediates (double strand breaks). This system will permit the identification of both cell populations and genomic loci that are selectively susceptible to replication abnormalities during compensatory renewal. In addition, we propose to use our ATR-conditional system to characterize how DNA-damaged cells coordinate the distinct phases of regeneration through extrinsic factors. These factors include ones that that inhibit renewal and those that subsequently stimulates it. In aggregate, these studies will determine how urgent episodes of compensatory renewal are regulated and how these events can lead to the decline of long-term renewal potential. PUBLIC HEALTH RELEVANCE: Age-associated pathologies are a major contributor to morbidity and mortality in the United States. Occurrence of these diseases is strongly influenced by the effectiveness of organ maintenance and tissue regeneration. In this proposal, we describe experiments to both better define the causes of debilitated regenerative potential with age and investigate the mechanisms used to renew tissues following acute loss of tissue integrity.