The Role of Actin in Cellular Aging

 描述（由申请人提供）：肌动蛋白细胞骨架在细胞功能中具有重要作用，包括细胞内和细胞运动、细胞极性的建立和维持、连接和形状、肌肉收缩、细胞信号传导和胞质分裂。虽然很明显，肌动蛋白功能经历了年龄相关的下降，在所有系统的研究，包括骨骼肌和心肌和免疫系统，显着很少有人知道细胞骨架在正常衰老过程中的作用。事实上，目前尚不清楚肌动蛋白细胞骨架的调节是否可以延长哺乳动物细胞的寿命。我们获得了第一个证据，肌动蛋白细胞骨架的调制可以延长寿命使用酵母作为模型系统。我们实验室以前的研究揭示了肌动蛋白细胞骨架在控制线粒体运动和促进酵母子细胞遗传更适合的线粒体中的作用，并揭示了该过程的机制。同样重要的是，我们发现，促进肌动蛋白动力学和功能延长酵母寿命和健康的依赖性机制。最后，我们获得的证据表明，肌动蛋白细胞骨架经历了结构，极化和功能在酵母中，因为他们的年龄下降，并在老细胞中观察到的肌动蛋白的缺陷是类似的Sir 2 p，寿命调节器的Sirtuin家族的创始成员删除后观察到的。在R21阶段，我们将使用酵母作为模型系统研究肌动蛋白细胞骨架功能与年龄相关的下降的机制。具体来说，我们将测试是否有年龄相关的下降，在稳定性组装的肌动蛋白细胞骨架，以及是否观察到类似的变化，在酵母中的寿命已延长或减少的调制Sir 2 p。我们获得的证据表明，肌动蛋白经历年龄相关的翻译后修饰（PTM），并将确定这些PTM的性质和肌动蛋白上的网站，他们发生。最后，我们将测试肌动蛋白极化的年龄相关性下降是否是由于Cdc 42的极化或活性缺陷所致。 （保守的Rho蛋白和肌动蛋白调节剂）和/或formins（其介导肌动蛋白聚合和在极化细胞表面生长位点的组装，并被Cdc 42募集到那些位点）。在R33阶段，我们将确定促进肌动蛋白细胞骨架的结构，极化和功能或防止肌动蛋白蛋白的年龄相关PTM的干预措施是否延长寿命和/或健康寿命。此外，我们确定了基因，包括以前未表征的开放阅读框架，增强肌动蛋白的结构和极性在酵母遗传筛选。我们将测试这些基因和其他肌动蛋白相关蛋白的调节是否可以延长寿命（R21期），以及延长寿命基因（R33期）的肌动蛋白调节机制。由于肌动蛋白功能的下降发生在衰老的哺乳动物细胞、组织和器官中，而稳定的肌动蛋白延长了C。这些研究将为理解肌动蛋白细胞骨架中与年龄相关的下降提供基础，并可能揭示在酵母和其他真核生物中促进肌动蛋白在寿命和健康控制中的功能的干预措施。

 DESCRIPTION (provided by applicant): The actin cytoskeleton has essential roles in cellular functions including intracellular and cellular movement, establishment and maintenance of cell polarity, junctions and shape, muscle contraction, cell signaling and cytokinesis. While it is clea that actin function undergoes an age-associated decline in all systems studied including skeletal and cardiac muscle and the immune system, remarkably little is known about the role of the cytoskeleton in the normal aging process. Indeed, it is not clear whether modulation of the actin cytoskeleton can extend lifespan in mammalian cells. We obtained the first evidence that modulation of the actin cytoskeleton can extend lifespan using yeast as a model system. Previous studies from our laboratory revealed a role for the actin cytoskeleton in control of mitochondrial movement and promoting inheritance of fitter mitochondria by yeast daughter cells, and uncovered the mechanism underlying that process. Equally important, we found that promoting actin dynamics and function extends yeast lifespan and healthspan by a mitochondria-dependent mechanism. Finally, we obtained evidence that the actin cytoskeleton undergoes a decline in structure, polarization and function in yeast as they age, and that the defects in actin observed in old cells are similar to those observed upon deletion of Sir2p, the founding member of the Sirtuin family of lifespan regulators. In the R21 phase, we will study the mechanisms underlying age-linked declines in function of the actin cytoskeleton using yeast as a model system. Specifically, we will test whether there are age-linked declines in the stability o assembly of the actin cytoskeleton, and whether similar changes are observed in yeast in which lifespan has been extended or reduced by modulation of Sir2p. We obtained evidence that actin undergoes age-linked post- translational modifications (PTMs), and will determine the nature of those PTMs and the sites on actin where they occur. Finally, we will test whether the age-associated decline in actin polarization is due to defects in the polarization or activity of Cdc42 (a conserved Rho protein and actin regulator) and/or formins (which mediate actin polymerization and assembly at sites of polarized cell surface growth and are recruited to those sites by Cdc42). In the R33 phase, we will determine whether interventions that promote the structure, polarization and function of the actin cytoskeleton or prevent age-linked PTM of actin protein extend lifespan and/or healthspan. Moreover, we identified genes, including previously uncharacterized open reading frames, which enhance actin structure and polarity in a yeast genetic screen. We will test whether modulation of these genes and other actin-associated proteins can extend lifespan (R21 phase), and the mechanism underlying actin regulation by lifespan-extending genes (R33 phase). Since declines in actin function occur in aging mammalian cells, tissues and organs, and stabilizing actin extends lifespan in C. elegans, these studies will provide a foundation for understanding age-associated declines in the actin cytoskeleton, and may reveal interventions to promote actin function in lifespan and healthspan control in yeast and other eukaryotes.