Macrophage regulation of the spermatogonial stem cell niche

项目总结/摘要 组织干细胞自我更新和分化缺陷与胎儿期器官畸形有关 发育和器官功能障碍。尽管有这种广泛的医疗保健影响， 对干细胞的分子调控知之甚少，特别是在微环境方面 其中组织干细胞驻留，称为小生境。研究干细胞生物学的一个很好的模型是 哺乳动物精原干细胞（SSC）的生态位，自我更新和分化的严格调节， 在很长的生殖期内持续产生大量配子所必需的; 这一过程的不平衡直接导致不育或生殖细胞衍生的癌症。尽管研究 尽管在这些努力中，SSC生态位的细胞成分在很大程度上仍然不确定。我们的初步数据显示， 巨噬细胞是精子发生所需的生态位的关键部分。巨噬细胞是免疫细胞， 存在于大多数器官中，传统上与吞噬外来病原体有关， 先天免疫反应;然而，人们越来越意识到组织特异性发育作用， 巨噬细胞此外，一些研究报道巨噬细胞位于组织干细胞附近， 生态位，但它们在这种生物背景下的作用尚不清楚。因此，巨噬细胞 形成干细胞小生境的一部分和直接干细胞活性代表了该领域的一个显著的知识差距。在 特别地，巨噬细胞在SSC生态位中的特定作用先前尚未被研究。这 研究计划将通过三个重点解决SSC生态位生物学中重要的未回答的问题 目的：1）确定巨噬细胞促进SSC分化的机制; 2）确定 将巨噬细胞募集到干细胞龛的信号;和3）确定巨噬细胞在 与其他体细胞类型，如支持细胞和管周肌样细胞协调，以建立和 保持niche。为了实现这些目标，我们将采用：体内遗传小鼠模型;离体培养 系统;纯化细胞群的谱系特异性基因组研究;和整个器官的时间推移生活 显像这些方法将使我们能够深入了解睾丸干细胞的生态位功能， 以前是无法实现的。这项工作将确定新的细胞和分子机制，指导SSC 利基和发现干细胞生物学的新范式，都与发展和疾病。 最终，这项研究将导致对男性不育和睾丸癌病因的新见解， 有助于为这些病症创造改进的诊断和治疗方法。

Project Summary/Abstract Defects in tissue stem cell self-renewal and differentiation are linked to organ malformations during fetal development and organ dysfunction in adult life. Despite this wide range of healthcare implications, the cellular and molecular regulation of stem cells is poorly understood, in particular with respect to the microenvironment in which tissue stem cells reside, termed the niche. An excellent model for studying stem cell biology is the mammalian spermatogonial stem cell (SSC) niche, as tight regulation of self-renewal and differentiation is required for the constant production of a large number of gametes over a long reproductive lifespan; imbalances in this process directly contribute to infertility or germ-cell-derived cancers. Despite research efforts, the cellular components of the SSC niche remain largely undefined. Our preliminary data reveal that macrophages are a critical part of the niche required for spermatogenesis. Macrophages are immune cells that are present throughout most organs and are traditionally associated with phagocytosis of foreign pathogens in the innate immune response; however, there is a growing awareness of tissue-specific developmental roles for macrophages. Additionally, several studies have reported that macrophages are located near tissue stem cell niches, but their roles in this biological context are unclear. Therefore, the mechanisms by which macrophages form part of stem cell niches and direct stem cell activity represent a significant knowledge gap in the field. In particular, specific roles for macrophages in the SSC niche have not been previously investigated. This research program will address important unanswered questions in SSC niche biology through three focused goals: 1) to identify the mechanisms used by macrophages to promote SSC differentiation; 2) to determine the signals that recruit macrophages to the stem cell niche; and 3) to define the role of macrophages in coordinating with other somatic cell types, such as Sertoli cells and peritubular myoid cells, to establish and maintain the niche. To accomplish these goals, we will employ: in vivo genetic mouse models; ex vivo culture systems; lineage-specific genomic studies of purified cell populations; and whole organ time-lapse live imaging. These approaches will allow us to obtain an in-depth knowledge of testis stem cell niche function that was previously unattainable. This work will identify novel cellular and molecular mechanisms directing the SSC niche and uncover new paradigms of stem cell biology that are relevant to both development and disease. Ultimately, this research will lead to new insights into the etiology of male infertility and testicular cancer, and aid in the creation of improved diagnostic and treatment methods for these conditions.