Stem Cell Renewal and Differentiation in Spermatogenesis

描述(由申请人提供)： 人们对引导干细胞行为的回路有着浓厚的兴趣。由于很难在组织中识别干细胞，大多数工作都集中在控制干细胞的内在作用因素上，或者是识别允许干细胞扩张但仍保持未分化状态的培养条件。因此，尽管微环境提供了许多支配干细胞基本属性的信号，但人们对构成干细胞自然生态位的微环境知之甚少。了解利基-干细胞相互作用是解开在再生医学中使用这些细胞所必需的电路的核心。最广为人知的干细胞-生态位系统之一是果蝇睾丸，因为干细胞和它们的生态位得到了精确的定义，并且制定了监管计划的大纲。睾丸壁龛既有生殖系干细胞，又有体细胞干细胞(分别为GSCs和SSCs)。在这里，两个基本的SSC因子，LINES和ZFH-1，被集中在一起，他们的研究引导我们重新考虑管理这一已建立的干细胞-利基模型的规则。这项提案涉及干细胞-生态位生物学在概念上的重要方面。首先，很少有系统可以高分辨率地研究在发育过程中区分干细胞和其利基细胞的遗传电路。目的1A试图确定LINES及其伴侣蛋白碗在调节性腺发生中SSC-生态位命运选择中的作用。由于神经干细胞也能产生其特定部位的细胞，因此人们对这里发现的电路会很感兴趣。其次，Hedgehog信号与多种干细胞类型的维持有关，包括癌症干细胞，但HH信号分配给干细胞的特殊特征仍然难以捉摸。目的1B试图确定HH在SSCs中的作用，特别是评估哪些干细胞的定义特征受HH信号调节。第三，了解抑制干细胞分化的机制是再生医学许多工作的主要目标。AIM 2A试图确定ZFH-1阻止分化并赋予体细胞干细胞特性的机制。AIM 2A旨在定义ZFH-1如何(非自主地)与GSC中的STAT激活合作。Aim 2C提出了互补的方法来识别ZFH-1控制下的基因，这有助于完成这两项任务。我们的工作可以对干细胞生物学的这一方面做出根本性的贡献，这一前景也很好。 与公共健康相关：人们对引导干细胞行为的回路非常感兴趣。了解利基-干细胞相互作用是解开在再生医学中使用这些细胞所必需的电路的核心。这项提案涉及干细胞-生态位生物学在概念上的重要方面。

DESCRIPTION (provided by applicant): There is intense interest in the circuits that guide stem cell behavior. Due to the difficulty in identifying stem cells in tissues, most work has centered on intrinsically-acting factors that control stem cells, or on identifying culture conditions that allow their expansion while yet maintaining their undifferentiated state. Thus, there is significantly less known about the microenvironment that comprises a stem cell's natural niche, even though it provides many of the signals that govern fundamental stem cell properties. Understanding niche-stem cell interactions is central to unraveling the circuitry necessary to use these cells in regenerative medicine. One of the most well-understood stem cell-niche systems is the Drosophila testis, because the stem cells and their niche are precisely defined and the outlines of a regulatory program are in place. The testis niche maintains both germline and somatic stem cells (GSCs and SSCs, respectively). Here, two essential SSC factors, lines and zfh-1, are focused upon, and their study has led us to a reconsideration of the rules governing this well-established stem cell-niche model. This proposal addresses conceptually significant facets of stem cell-niche biology. First, there are precious few systems where one can at high resolution investigate the genetic circuitry that discriminates a stem cell from its niche cell during development. Aim 1A seeks to define the role of lines and its partner protein bowl in mediating SSC-niche fate choice in gonadogenesis. Since a neural stem cell can also generate cells of its niche, interest in the circuitry identified here will be high. Second, Hedgehog signaling has been implicated in the maintenance of various stem cell types, including cancer stem cells, but the particular characteristics that Hh signaling assigns to stem cells have remained elusive. Aim 1B seeks to define the role of Hh in SSCs, in particular, assessing which of the defining characteristics of stem cells are regulated by Hh signaling. Third, understanding the mechanisms that repress differentiation in stem cells is a major goal of much work in regenerative medicine. Aim 2A seeks to identify the mechanism whereby Zfh-1 blocks differentiation and confers stem cell properties to somatic cells. Aim 2A seeks to define how Zfh-1 cooperates (non-autonomously) with STAT activation in GSCs. Aim 2C proposes complementary approaches to identify genes under Zfh-1 control that help accomplish both of these tasks. The prospects are also excellent that our work can contribute in a fundamental manner to this aspect of stem cell biology. Public Health Relevance: There is intense interest in the circuits that guide stem cell behavior. Understanding niche-stem cell interactions is central to unraveling the circuitry necessary to use these cells in regenerative medicine. This proposal addresses conceptually significant facets of stem cell-niche biology.