PROLIFERATIVE VS MEIOTIC FATE DECISION IN C. ELEGANS

项目摘要 生殖系干细胞必须做出的一个重要决定是进行有丝分裂或启动减数分裂。 发育/配子发生。这种发育转换的中断可能导致不孕不育，在某些情况下 生殖系肿瘤。线虫成虫两性体是了解线虫控制的重要模型。 从生殖系干细胞的命运切换到减数分裂发育/配子发生，其中过程的概要是 正在浮现。依赖小生境的GLP-1 Notch信号促进干细胞命运并抑制三个冗余 促进减数分裂发育/配子发生的途径：GLD-1途径(抑制表达 增殖基因)、GLD-2途径(促进减数分裂基因的表达)和第三途径 它的存在已通过遗传分析被揭示，但尚未发现有基因产物 约会。在细胞层面上，我们最近发现干细胞种群很大，生殖细胞进入 直接减数分裂，不干预运输放大分裂。不存在放大运输的分歧 简化了分析，允许直接的分析来识别参与抑制茎的减数分裂的基因 细胞和抑制减数分裂进入的增殖，是线虫成为主要动物的主要原因 研究这一重要的发育开关的模型。 这项建议涉及干细胞减数分裂发育/配子发生开关的三个主要领域 我们的知识有很大的差距。首先，促进GLP-1信号传导的转录靶点 干细胞的命运和/或抑制减数分裂进入途径尚不完全清楚。我们建议确定 GLP-1的转录靶点，并确定它们抑制哪条减数分裂进入途径(S)。第二，基因 构成减数分裂的第三条进入途径尚不清楚。我们的初步结果表明，SCFprom-1 泛素介导的降解复合体是第三条途径，我们建议进行实验以进一步验证这一点 假设。第三，GLD-1mRNA的翻译/稳定性调节是生殖系干细胞的核心部分 分化AS的表达必须在干细胞中被抑制，并被激活以进行减数分裂；然而，控制 GLD-1的积累还不完全清楚。我们建议：(I)确定两个 已知的GLP-1转录靶点抑制GLD-1的积聚，(Ii)决定空间和数量 新发现的生殖系干细胞分化调节因子在控制GLD-1中的作用 (三)确定新的监管者，因为已知的监管者只解释了GLD-1的一部分 积累模式，作为识别控制发育开关的额外基因的途径。

Project Summary An essential decision that germline stem cells must make is to proliferate mitotically or initiate meiotic development/gametogenesis. Disruption of this developmental switch can result in infertility and in some cases germline tumors. The C. elegans adult hermaphrodite is an important model for understanding control of the switch from germline stem cell fate to meiotic development/gametogenesis, where an outline of the process is emerging. Niche dependent GLP-1 Notch signaling promotes the stem cell fate and represses three redundant pathways that promote meiotic development/gametogenesis: the GLD-1 pathway (which represses expression of proliferation genes), the GLD-2 pathway (which promotes expression of meiotic genes), and a 3rd pathway whose existence has been revealed through genetic analysis but no gene products have been identified to date. At a cellular level, we have recently shown that the stem cell population is large and germ cells enter meiosis directly, without intervening transit-amplifying divisions. The absence of transit-amplifying divisions simplifies the analysis allowing straightforward assays to identify genes involved in repressing meiosis in stem cells and repressing proliferation at meiotic entry and is the primary reason why C. elegans is the major animal model for studying this important developmental switch. This proposal addresses three major areas in the stem cell - meiotic development/gametogenesis switch where there are large gaps in our knowledge. First, the transcriptional targets of GLP-1 signaling that promote the stem cell fate and/or repress the meiotic entry pathways are incompletely known. We propose to identify GLP-1 transcriptional targets and determine which meiotic entry pathway(s) they inhibit. Second, genes that constitute the 3rd meiotic entry pathway are unknown. Our preliminary results indicate that the SCFprom-1 ubiquitin mediated degradation complex is the 3rd pathway and we propose experiments to further test this hypothesis. Third, gld-1 mRNA translation/stability regulation is a central part of germline stem cell differentiation as expression must be repressed in stem cells and activated for meiosis; however control of GLD-1 accumulation is incompletely understood. We propose to (i) determine the mechanism of how two known GLP-1 transcriptional targets repress GLD-1 accumulation, (ii) determine the spatial and quantitative contribution of newly identified regulators of the germline stem cell differentiation in control of GLD-1 accumulation, and (iii) identify new regulators, since known regulators explain only part of the GLD-1 accumulation pattern, as a route to identify additional genes that control the developmental switch.