Stem cell aging and the control of abscission

 描述（由申请人提供）：我们的组织在衰老过程中不可阻挡地衰退。其原因之一是负责组织稳态的干细胞的内在变化，或调节干细胞活性的小生境的变化。为了探索细胞骨架功能与衰老之间的潜在联系，研究一种已经从根本上帮助我们理解衰老对干细胞功能影响的组织可能具有很大的优势。果蝇睾丸就是这样一种组织，因为生殖干细胞（GSC）已被证明会老化，并且已经定义了内在和外在调节剂。为了维持组织的稳态，干细胞必须在空间和时间上严格控制子细胞的产生。因此，我们把重点放在分裂，胞质分裂的最后一步，包括子细胞的完全分离。脱落是胞质分裂过程中的一个重要调控点，微管和肌动蛋白在此过程中起着重要作用。脱落一直难以在体内成像，但我们已经成功地使用肌动蛋白和肌球蛋白II的同时成像。我们的分析表明，在GSC中，即使在收缩环和中间体微管被分解后，收缩也会显著延迟。令人惊讶的是，一个新的，丝状肌动蛋白丰富的结构成功的收缩环，并用于稳定中体。我们定义了一个调控电路控制这种新的细胞骨架功能，以及极光B激酶的控制。最后，我们发现，老化显着地影响了细胞分裂，打开了这个系统的老化和细胞骨架的研究。由于遗传和药理学操作的容易性，沿着GSC在稳态和衰老时的良好特征化行为，果蝇睾丸提供了一个理想的系统，在其中研究时间动态，遗传控制和细胞骨架成分在凋亡事件中的作用。在这里，我们测试的潜在的因果关系之间的联系，细胞骨架控制在这一成人干细胞群体的凋亡和衰老。

 DESCRIPTION (provided by applicant): Our tissues inexorably decline during aging. A cause of this is intrinsic changes to the stem cells responsible for tissue homeostasis, or changes in the niche regulating stem cell activity. To explore potential links between cytoskeletal function and aging, there can be great advantage to studying a tissue that has already contributed fundamentally to our understanding of the impact of aging on stem cell function. The Drosophila testis is such a tissue, as germline stem cells (GSCs) have been shown to age, and both intrinsic and extrinsic regulators have been defined. To maintain tissue homeostasis, stem cells must exercise tight spatial and temporal control over daughter cell production. Thus, we have focused on abscission, the last step of cytokinesis, involving the complete separation of daughter cells. Abscission is a key point of regulation generally during cytokinesis, and microtubule and f-actin cytoskeletal dynamics play seminal roles during this process. Abscission has been difficult to image in vivo, but we have been successful using simultaneous imaging of Actin and Myosin II. Our analysis shows that abscission is dramatically delayed in GSCs, even after the contractile ring and the midbody microtubules are disassembled. Surprisingly, a new, filamentous actin-enriched structure succeeds the contractile ring, and serves to stabilize the midbody. We define a regulatory circuit controlling this novel cytoskeletal feature, as well as controls by Aurora B Kinase. Lastly, we find that aging significantly affects abscission, opening up this system to the study of aging and the cytoskeleton. Due to the ease of genetic and pharmacological manipulations, along with the well-characterized behavior of GSCs at steady state and upon aging, the Drosophila testis provides an ideal system in which to study the temporal dynamics, genetic control and roles for cytoskeletal components in abscission events. Here, we test for potential causative links between cytoskeletal control over abscission and aging within this adult stem cell population.