The Role of TAF4b in Spermatogonial Stem Cell Maintenance and Self-Renewal

描述（由申请人提供）：了解干细胞如何平衡自我更新与分化对于利用其在医学中的治疗潜力至关重要。虽然最近的工作已经确定了控制小鼠和人类胚胎干细胞（ES）多能性的主转录调节基因，但仍不清楚是否有类似的机制指导组织特异性单能干细胞（如哺乳动物睾丸中发现的精原干细胞（SSC））的细胞命运决定。与ES细胞中的主调节蛋白相反，最近的工作已经发现了细胞类型特异性或富集形式的细胞调节蛋白的基本功能。 调节基因表达的核心转录机制。这些都需要驱动关键的基因表达程序参与与多细胞和器官发生相关的各种发育事件。核心转录机制的多样化在生殖系中最为显著，其中一般转录因子TFIIA和TFIID的生殖细胞特异性或富集的变体在调节转录过程中执行高度关键和选择性的功能。 生殖和生育能力。这种生殖细胞特异性基因调控的新范式在无脊椎动物和脊椎动物之间是保守的，并且可能反映了进化生殖细胞特异性基因调控模式的重要机制。然而，仍然需要了解这种精细的生育调节背后的分子机制。本研究的目的是描述TAF4b在小鼠睾丸中建立和维持精原干细胞自我更新谱系中的作用。TAF4b是一种性腺富集的通用转录因子变体，雄性和雌性Taf4b缺陷小鼠均表现出生殖缺陷。有证据表明，它在精原干细胞（SSC）的自我更新和寿命中起着至关重要的作用。本研究的具体目标之一是鉴定和表征TAF4b相互作用蛋白辅因子，以研究它们在SSC调节中的功能。TAF4b可以控制SSC特异性基因表达的方式之一是通过与其他蛋白质的直接相互作用，这些蛋白质的功能是打开或关闭适当的SSC基因。本研究旨在通过鉴定这些蛋白质并分析它们在SSC基因表达中的功能来验证这一假设。第二个具体目标是确定TAF4b在SSC基因组中结合的位置，并确定TAF4b直接靶向调节哪些基因。这将为TAF4b如何决定它将调节哪些基因，如何建立SSC特异性基因调控程序以及这些程序如何驱动SSC自我更新提供机制性见解。这里提出的工作，揭示TAF4b在调节SSC维持和自我更新中的机制，将揭示男性生育所需的干细胞生物学和生殖功能的基本生物学原理。这些研究可能揭示原因不明的男性不育症背后的病因，并导致先进的诊断和治疗工具，以更好地解决和管理男性不育症。

DESCRIPTION (provided by applicant): Understanding how stem cells balance self-renewal with differentiation is paramount in harnessing their therapeutic potential in medicine. While recent work has identified master transcriptional regulator genes controlling pluripotency in mouse and human embryonic stem (ES) cells, it is still unclear whether similar mechanisms direct cell fate decisions in tissue-specific unipotent stem cells, such as the spermatogonial stem cells (SSCs) found in mammalian testes. In contrast to the master regulator proteins in ES cells, recent works has discovered essential functions for cell type-specific or -enriched forms of the core transcription machinery in regulating gene expression. These are required to drive critical gene expression programs involved in diverse developmental events associated with multicellularity and organogenesis. The diversification of core transcription machinery is most notable in the germline where germ cell-specific or -enriched variants of the general transcription factors TFIIA and TFIID execute highly critical and selective functions in regulating reproduction and fertility. This new paradigm of germ cell-specific gene regulation is conserved between invertebrates and vertebrates, and may reflect an important mechanism for evolving germ cell-specific modes of gene regulation. However, the need to understand the molecular mechanisms underlying such exquisite regulation of fertility persists. The goal of this research proposal is to characterize the role of TAF4b in the establishment and maintenance of the self-renewing lineage of SSCs in the mouse testis. TAF4b is a gonad-enriched general transcription factor varient and both male and female Taf4b-deficient mice exhibit reproductive defects. Several lines of evidence suggest it plays an essential role in spermatogonia stem cell (SSC) self-renewal and longevity. One of the specific aims in this research proposal is to identify and characterize TAF4b-interacting protein cofactors to investigate their function in SSC regulation. One of the ways TAF4b may control SSC-specific gene expression is through direct interaction with other proteins that function to turn appropriate SSC genes on or off. This aim will test this hypothesis by identifying these proteins and analyzing their function in SSC gene expression. The second specific aim is to identify where TAF4b binds in the SSC genome and identify which genes TAF4b is directly targeting for regulation. This will provide mechanistic insight into how TAF4b determines which genes it will regulate, how SSC-specific gene regulatory programs are established and how these programs drive SSC self-renewal. The work proposed here, to uncover the mechanisms of TAF4b in regulating SSC maintenance and self-renewal, will reveal fundamental biological principles underlying both stem cell biology and reproductive functions in men required for fertility. These studies may reveal the etiologies behind unexplained male infertility and lead to advanced diagnostic and therapeutic tools to better address and manage male infertility.