Regulation of stem cell differentiation during Drosophila oogenesis

摘要 配子的产生是启动下一代的关键。为了产生配子，生殖系干细胞 (GSCs)必须退出管理自我更新和转移扩增的有丝分裂计划，并启动 减数分裂程序。而在减数分裂过程中抑制减数分裂程序的几种生殖细胞内在机制 有丝分裂阶段已经被描述，但关于有丝分裂程序是如何调节的知之甚少。我们有 确定了一种特殊的转录复合体，它允许表达种系特异性的 核糖体蛋白，调节有丝分裂程序和向减数分裂的转变。我们发现了一个 保守的男性特异性致死蛋白3(MSL3)在调节雌性生殖系有丝分裂中的意外作用 阶段转录。在果蝇中，msl3是上调的剂量补偿复合体(DCC)的一部分 男性X染色体的转录。我们发现msl3在雌性有丝分裂期有表达。 生殖系，在那里它独立于DCC发挥作用，既促进GSC的维持，又过渡到减数分裂 命运。我们的数据表明，MSL3招募了含有Ada2a的组蛋白乙酰转移酶(HAT)活性 (ATAC)综合体。我们发现msl3和atac复合体的缺失导致了a基因转录水平的降低。 核糖体蛋白，RpS19b。我们发现RpS19b在生殖系有丝分裂阶段和 建议它控制RNA结合蛋白Fox 1(RBFOX1)等因子的翻译，以调节有丝分裂- 减数分裂开关。这项提议的目的是揭示MSL3是如何调节从有丝分裂到有丝分裂的转变的。 通过RpS19b进行减数分裂程序。我们的中心假设是，MSL3通过ATAC复合体招募HAT活动 促进RpS19b的转录，进而调节RBFOX1的翻译。我们计划检验我们的假设 有以下三个具体目的：1)确定MSL3如何促进卵子发生。2)确定 HATS在MSL3依赖的转录中。3)揭示RpS19b在卵子发生中的作用和机制。这个 这项拟议工作的理论基础是对msl3介导的有丝分裂到减数分裂转变的调控的洞察。 将阐明功能性卵母细胞是如何产生的。在哺乳动物中，msl3是雄性特异性致死(Msl)的一部分。 复合体，它调节着多能性计划的维持和分化，暗示着一种潜在的 MSL3在干细胞室中的保守功能。

Abstract The production of gametes is pivotal to launching the next generation. To generate gametes, germline stem cells (GSCs) must exit the mitotic program, which governs self-renewal and transit amplification, and initiate the meiotic program. While several germ cell intrinsic mechanisms that repress the meiotic program during the mitotic phase have been described, little is known about how the mitotic program is regulated. We have identified a specialized transcriptional complex that permits the expression of a germline-specific ribosomal protein that regulates the mitotic program and the shift to meiosis. We discovered an unexpected role for the conserved Male-specific lethal 3 (Msl3) protein in regulating female germline mitotic phase transcription. In Drosophila, Msl3 is part of the Dosage Compensation Complex (DCC) that upregulates transcription from the X chromosome in males. We find that msl3 is expressed in the mitotic phase of the female germ line, where it acts independently of the DCC to both promote GSC maintenance and transition into meiotic fate. Our data suggest that Msl3 recruits the histone acetyltransferase (HAT) activity of the Ada2a-Containing (ATAC) complex. We found that loss of msl3 and ATAC complex components lead to reduced transcription of a ribosomal protein, RpS19b. We find that RpS19b is expressed specifically in the germline mitotic stages and propose that it controls translation of factors such as RNA binding protein Fox 1 (Rbfox1) to regulate the mitosis- to-meiosis switch. The objective of this proposal is to uncover how Msl3 regulates the transition from the mitotic- to-meiotic program via RpS19b. Our central hypothesis is that Msl3 recruits HAT activity via the ATAC complex to promote transcription of RpS19b, which in turn regulates Rbfox1 translation. We plan to test our hypothesis with the following three specific aims: 1) Determine how Msl3 promotes oogenesis. 2) Determine the role of HATs in Msl3-dependent transcription. 3) Uncover the role and mechanism of RpS19b in oogenesis. The rationale for the proposed work is that insight into Msl3-mediated regulation of the mitotic-to-meiotic transition will illuminate how functional oocytes are generated. In mammals, Msl3 is part of the Male Specific Lethal (MSL) complex, which regulates maintenance and differentiation from the pluripotency program, suggesting a potential conserved function of Msl3 in stem cell compartments.