A role for nuclear actin filaments at damaged telomeres

核肌动蛋白丝在受损端粒处的作用

• 批准号: 8058216
• 负责人: Brittany Jo Belin
• 金额: $ 4.14万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8058216
• 关键词: role; nuclear; actin; filaments; damaged

DESCRIPTION (provided by applicant): Actin is among the most well characterized proteins in eukaryotic organisms and is required for many cytosolic processes, including cell motility, intracellular transport and the structural integrity of the cell. Recent reports have suggested that actin also participates in a range of nuclear processes in numerous cell types, though the role of this nuclear pool of actin is largely unknown. Previous work on nuclear actin has been limited due to the difficulty associated with visualizing actin in intact somatic nuclei. I have recently developed novel reporters of both monomeric and filamentous pools of nuclear actin in live cells. Using these tools in collaboration with the Blackburn lab, we have made the exciting discovery that actin filaments colocalize with uncapped telomeres. To investigate the role of telomeric actin, I propose to determine the live cell dynamics of nuclear actin with respect to both capped and deprotected telomeres. I will also investigate whether the association is dependent on the DNA damage response, as well as factors responsible for recruitment and regulation of telomeric actin. PUBLIC HEALTH RELEVANCE: Decades of experimental research on telomere biology have provided a clear link between telomere function and aging. Disruption or loss of active telomerase has been shown to cause telomeres to shorten and trigger cellular senescence, both in vivo and in vitro (Yu et al. 1990, Harley et al. 1990). When active telomerase is introduced into cell cultures with low telomerase activity, telomeres lengthen and the cells can become immortalized (Bodnar et al. 1998, Counter et al. 1998). From these observations, the traditional view that emerged was that the loss of telomere "critical length" promotes senescence. However, more recent evidence suggests that rather than telomere length per se, it is the loss of protection ("uncapping") of the telomere that results from telomere shortening that limits cell proliferation (Blackburn 2000). The proposed research identifies nuclear actin as a novel factor present at uncapped telomeres, and investigates potential roles for telomeric actin in signaling to the machineries involved in cell cycle exit, apoptosis and genomic instability. This research will provide insight into the consequences of uncapped telomeres that are responsible for promoting cellular senescence.

描述（由申请人提供）：肌动蛋白是真核生物中表征最充分的蛋白质之一，是许多细胞质过程所必需的，包括细胞运动、细胞内运输和细胞结构完整性。最近的报告表明，肌动蛋白还参与多种细胞类型的一系列核过程，尽管肌动蛋白核库的作用很大程度上未知。由于在完整体细胞核中观察肌动蛋白存在困难，先前关于核肌动蛋白的工作受到限制。我最近开发了活细胞中核肌动蛋白单体和丝状库的新型报告基因。与布莱克本实验室合作使用这些工具，我们取得了令人兴奋的发现：肌动蛋白丝与无帽端粒共定位。为了研究端粒肌动蛋白的作用，我建议确定核肌动蛋白在加帽端粒和去保护端粒方面的活细胞动力学。我还将研究这种关联是否依赖于 DNA 损伤反应，以及负责端粒肌动蛋白募集和调节的因素。 公共健康相关性：数十年的端粒生物学实验研究已经提供了端粒功能与衰老之间的明确联系。在体内和体外，活性端粒酶的破坏或丧失已被证明会导致端粒缩短并引发细胞衰老（Yu et al. 1990，Harley et al. 1990）。当将活性端粒酶引入端粒酶活性较低的细胞培养物中时，端粒会延长，细胞可以永生化（Bodnar 等人，1998 年；Counter 等人，1998 年）。从这些观察中，出现的传统观点是端粒“临界长度”的丧失会促进衰老。然而，最近的证据表明，限制细胞增殖的不是端粒长度本身，而是端粒缩短导致的端粒保护丧失（“脱帽”）（Blackburn 2000）。拟议的研究将核肌动蛋白确定为存在于无帽端粒上的一种新因子，并研究了端粒肌动蛋白在向涉及细胞周期退出、细胞凋亡和基因组不稳定的机制发出信号中的潜在作用。这项研究将深入了解导致细胞衰老的无帽端粒的后果。