Systematic Characterization of an Aging Stem Cell Niche

 描述（由申请人提供）：干细胞不能支持组织稳态和修复是许多年龄相关表型的基础。被称为小生境的特殊微环境通过控制干细胞自我更新和其子细胞分化之间的平衡来帮助维持适当的组织稳态。然而，在体内小生境的形成，大小和信号输出的机制仍然知之甚少。我们的长期目标是确定和表征在体内调节生态位功能的因素。在许多哺乳动物组织中，干细胞及其支持性微环境通常被证明难以在体内识别。因此，我们目前对生态位的理解大多源于对无脊椎动物模型的研究。在这个建议中，我们试图建立在以前的努力，已经建立了果蝇卵巢作为一个强大的系统，研究干细胞龛老化。我们建议使用最先进的细胞纯化和大规模平行测序技术来系统地表征小生境细胞及其近邻的转录谱。此外，我们试图通过使用功能强大的细胞特异性功能丧失和功能获得技术，在衰老过程中发生在小生境内的基因表达变化的功能相关性进行遗传测试。我们已经建立了一个业务管道，以进行本提案概述的所有实验。我们的初步数据已经表明，小生境执行以前未被识别的功能，这些功能可能对干细胞的健康和维护很重要。在目标1中，我们试图全面和定量评估基因表达的变化，在果蝇卵巢生殖干细胞龛在衰老过程中。在目标2中，我们将建立在我们的初步数据基础上，并测试小生境是否有助于保护干细胞免受可以通过自然途径或通过损伤引入的微生物的侵害。最后，在目标3中，我们探索超氧化物歧化酶有助于延长生命后期适当生态位功能的分子机制。我们相信，这种对衰老过程中体内生态位功能的全面分析将为干细胞活性随年龄增长而下降的原因提供关键见解，并将为开发旨在促进衰老生物体持续组织稳态和再生的疗法揭示新的分子靶点。

 DESCRIPTION (provided by applicant): The inability of stem cells to support tissue homeostasis and repair underlies many age- related phenotypes. Specialized microenvironments called niches help maintain proper tissue homeostasis by controlling the balance between stem cell self-renewal and the differentiation of their daughters. However, the mechanisms that govern the formation, size and signaling output of in vivo niches remain poorly understood. Our long-term goal is to identify and characterize the factors that regulate niche function in vivo. Stem cells and their supportive microenvironments have often proven difficult to identify in vivo in many mammalian tissues. As a result, much of our current understanding of niches stems from the study of invertebrate models. In this proposal, we seek to build upon previous efforts that have established the Drosophila ovary as a powerful system with which to study stem cell niche aging. We propose to use state of the art cell purification and massive parallel sequencing techniques to systematically characterize the transcriptional profile of niche cells and their immediate neighbors. Moreover, we seek to genetically test the functional relevance of gene expression changes that occur within the niche during aging by using powerful cell-specific loss-of-function and gain-of- function techniques. We have established an operational pipeline for conducting all the experiments outlined under this proposal. Already, our preliminary data suggests that niches carry out previously unrecognized functions that are likely to be important for stem cell health and maintenance over time. In Aim 1, we seek to comprehensively and quantitatively assess changes in gene expression within the Drosophila ovarian germline stem cell niche during aging. In Aim 2, we will build upon our preliminary data and test whether niches help to protect stem cells from microbes that can be introduced through natural routes or via injury. Finally in Aim 3, we probe the molecular mechanisms by which a superoxide dismutase helps to prolong proper niche function late in life. We believe this comprehensive analysis of in vivo niche function during the course of aging will provide key insights into why stem cell activity declines with age and will reveal new molecular targets for the development of therapies designed to foster continued tissue homeostasis and regeneration in aging organisms.