Control of Stem Cell Fate in Drosophila Spermatogenesis

描述(申请人提供)：尽管精原干细胞对于生殖是必不可少的，但人们对其调控知之甚少。环境、遗传和表观遗传因素对干细胞的建立、维持和功能至关重要，但在哺乳动物系统中系统地识别这些因素是极具挑战性的。因此，大多数干细胞在其自然组织微环境或利基环境中的行为还没有被很好地理解。然而，了解干细胞-利基相互作用对于开发成功的基于干细胞的治疗方法是至关重要的。我们使用果蝇精子发生作为一个模型系统，因为它与哺乳动物的系统相似，但我们可以精确地定位干细胞并从基因上操纵它们的生态位。先前的资助使我们能够发现控制果蝇睾丸干细胞更新的分子机制。干细胞附着在一小群名为HUB的体细胞支持细胞上，HUB分泌一种配体，激活相邻细胞中的Janus-Kinase-Signal Transfer and Actifator of Transcription(JAK-STAT)信号，指示它们保持干细胞身份。背井离乡的女儿会有所区别。在这些发现的基础上，在这次更新中，我们将表征我们最近发现的在这个利基中干细胞维持所需的其他因素，并确定它们是否在这一过程中与Jak-STAT信号通路一起作用。这包括使用遗传和生化方法的组合来评估1)染色质重塑复合体和2)激素信号通路在精原干细胞更新中的作用。我们还将确定由Jak-STAT信号调节的其他基因，然后使用遗传学方法来确定它们在正常和老化的生态位中的作用。总之，这项工作将为调节干细胞维持的遗传和表观遗传机制提供基本的见解。

DESCRIPTION (provided by applicant): Although spermatogonial stem cells are essential for reproduction, their regulation is poorly understood. Environmental, genetic and epigenetic factors are crucial for stem cell establishment, maintenance, and function, but systematically identifying these factors is extremely challenging in mammalian systems. Consequently, the behavior of most stem cells within their natural tissue microenvironments, or niches, is not well-understood. However, understanding stem cell-niche interactions is critical for developing successful stem cell-based therapeutic approaches. We use Drosophila spermatogenesis as a model system, since it parallels mammalian systems, yet we can precisely locate the stem cells and manipulate their niche genetically. Prior funding enabled us to discover the molecular mechanism controlling stem cell renewal in the Drosophila testis. Stem cells adhere to a small cluster of somatic support cells called the hub, which secretes a ligand that activates Janus-kinase-signal transducer and activator of transcription (Jak-STAT) signaling in adjacent cells, instructing them to remain as stem cells. Daughters displaced away from the hub differentiate. Building on these findings, in this renewal we will characterize additional factors we have recently found to be required for stem cell maintenance in this niche, and determine if they act together with the Jak-STAT signaling pathway during this process. This includes using a combination of genetic and biochemical approaches to assess the role of 1) chromatin remodeling complexes and 2) hormonal signaling pathways in spermatogonial stem cell renewal. We will also identify additional genes regulated by Jak-STAT signaling then use genetic approaches to determine their roles in both normal and aged niches. Together this work will provide fundamental insight into the genetic and epigenetic mechanisms that regulate stem cell maintenance.