Cellular Lifespan and the Telomere Proteome

描述(由申请人提供)：有限的细胞寿命被认为在生物衰老中起着关键作用。尽管假设细胞寿命在衰老中的重要性有限，但我们目前对分子过程只有一个初步的了解。因此，阐明控制细胞寿命的分子机制将在衰老、癌症生物学和组织再生等领域具有深远的意义。当在培养中生长时，正常的人类细胞在进入复制衰老状态之前会分裂有限的次数，在这种状态下它们仍然活着，但无法进一步分裂。据推测，这种有限的复制能力导致了与衰老相关的表型，如伤口愈合减少和免疫系统减弱。我们对细胞寿命的兴趣集中在端粒--一种由DNA和蛋白质组成的特殊结构，位于线性染色体的末端--因为它在控制细胞寿命方面发挥着关键作用。这项建议将采用一种新的蛋白质组学方法来鉴定端粒结合蛋白。虽然这些蛋白质的鉴定将是非常重要的，但描绘它们在端粒稳态中的功能将是进一步了解细胞衰老的关键。我们将使用这些新发现的蛋白质，以及已知的结合端粒的蛋白质，在人类细胞中建立一些抑制屏幕。我们在基于载体的RNAi系统方面的专业知识使这些研究成为可能。这些后一项研究将使我们不仅能够识别端粒结合蛋白，而且还将使我们能够揭示通过影响端粒的动态平衡和细胞寿命来影响端粒的信号转导通路的关键成分。目前，我们有几个基于细胞的系统，可以用来解决新蛋白质在端粒稳态和细胞寿命中的功能。我们的基于细胞的系统与我们提出的新的蛋白质发现系统相结合，将被证明是一个强大的武器库，我们将通过它开始了解细胞衰老。了解端粒结构是如何监测、维持和降解的，将使我们能够描绘衰老的分子机制。一旦我们了解了这一过程，我们就能够确定衰老是否在生物体衰老中起到了致因作用。出于这些原因，对控制细胞衰老的分子机制的详细了解是至关重要的。

DESCRIPTION (provided by applicant): A limited cellular lifespan is hypothesized to play a crucial role in organismal aging. Despite the putative limited importance of cellular lifespan in aging, we currently have only a rudimentary understanding of the molecular process. Therefore, elucidation of the molecular mechanisms that control cellular lifespan will have far-reaching implications in the fields of aging, cancer biology, and tissue regeneration. When grown in culture, normal human cells divide a limited number of times before entering a state of replicative senescence, in which they remain viable but are unable to divide further. It is postulated that this limited replicative capacity contributes to the phenotypes associated with aging, such as reduced wound healing and a weakened immune system. Our interest in cellular lifespan is focused on the telomere - a specialized structure composed of DNA and proteins, which is located at the end of linear chromosomes - because it plays a key role in controlling cellular lifespan. This proposal will take a novel proteomics approach to identify telomeric binding proteins. While the identification of these proteins will be of great importance, delineation of their function in telomere homeostasis will be paramount to furthering our understanding of cellular aging. We will use these newly identified proteins, and proteins already known to bind the telomere, to set up a number of suppressor screens in human cells. Our expertise in vector-based RNAi systems makes these studies feasible. These latter studies will allow us to not only identify telomere binding proteins, but will also allow us to uncover critical components of the signal transduction pathways that impinge on the telomere by affecting its homeostasis and cellular lifespan. Currently we have several cell-based systems with which we can address the function of new proteins in telomere homeostasis and cellular lifespan. Our cell-based systems combined with the novel protein discovery systems we have proposed will prove to be a powerful arsenal with which we will begin to understand cellular aging. Understanding how telomere structure is monitored, maintained, and degraded will allow us to delineate the molecular mechanisms of senescence. Once we have an understanding of this process, we will be able determine whether senescence plays a causative role in organismal aging. For these reasons, a detailed understanding of the molecular mechanisms governing cellular senescence is critical.