CATALYTIC SUBUNIT OF THE TELOMERASE GENE HEST2

描述（由申请人提供）：许多类型的哺乳动物细胞在置于培养物中时停止增殖并进入称为衰老的非生长状态。流行的理论认为，衰老的开始是由染色体末端端粒的双链（ds）DNA区域的长度决定的。我们已经证明，相反，衰老不是由ds端粒DNA的总长度控制的，而是由从端粒的dsDNA部分（ssOH）的末端突出（突出端）的单链DNA的短延伸的长度控制的。当细胞进入衰老时，ssOH大量丢失。我们将开发测定ssOH和dsDNA部分的原位长度的方法。使用这些测定以及更直接的分子测量，我们将测试的分子模型，即细胞遭受的生理应激引起的ssOH的损失，这种损失，反过来，诱导p53依赖的DNA损伤反应，导致衰老细胞表型。我们将研究的概念，ssOH的损失是一种常见的机制触发衰老在各种生理应激，这种损失，往往是由细胞遭受的累积氧化损伤引起的。使用原位测量的ssOH和dsDNA部分的端粒内的细胞将使我们能够确定是否在一个协调的方式在个别细胞中发生的ssOH的损失，从而积极挑起或在异步，随机的方式。此外，这些测量将使我们能够确定是否损失的ssOH和相关的p53激活发生在活组织内的细胞，从而提供证据，细胞衰老的状态发生在体内，并可能导致细胞的增殖潜力在老化组织和各种病理状态的损失。

DESCRIPTION (provided by applicant): Many types of mammalian cells, when placed into culture, halt proliferation and enter into a non-growing state termed senescence. The prevailing theory says that the onset of senescence is dictated by the length of double strand (ds) DNA regions of the telomeres at the ends of chromosomes. We have demonstrated that, on the contrary, senescence is not controlled by the overall length of the ds telomeric DNA, but instead by the length of a short stretch of single-strand DNA that protrudes from (overhangs) from the ends of the dsDNA portion of a telomere (ssOH). ssOH is largely lost when cells enter into senescence. We shall develop assays to gauge the lengths in situ of the ssOH and dsDNA portions. Using these assays as well as more direct molecular measurements, we will test a molecular model whereby physiologic stress suffered by cells provokes loss of the ssOH, and that this loss, in turn, induces a p53-dependent DNA damage response that results in the senescent cell phenotype. We will examine the notion that loss of the ssOH is a common mechanism for triggering senescence in response to a variety of physiologic stresses, and that this loss, is often provoked by cumulative oxidative damage suffered by cells. Use of in situ measurements of the ssOH and dsDNA portions of the telomeres within cells will allow us to determine whether the loss of ssOH occurs in a concerted fashion in individual cells and is thus actively provoked or in an asynchronous, stochastic fashion. In addition, these measurements will allow us to determine whether loss of ssOH and associated p53 activation occur in cells within living tissues, thereby providing evidence that the state of cell senescence occurs in vivo and may contribute to the loss of proliferative potential of cells in aging tissues and in various pathological states.