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增殖或启动减数分裂 发育/配子发生。这种发育开关的中断会导致不孕，在某些情况下， 生殖系肿瘤梭秀丽线虫的雌雄同体是了解控制的重要模型， 从生殖系干细胞命运转换到减数分裂发育/配子发生，其中该过程的概述是 正在浮现小生境依赖性GLP-1 Notch信号转导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 增殖基因的表达）、GLD-2途径（其促进减数分裂基因的表达）和第三途径（其促进减数分裂基因的表达）。 其存在已通过遗传分析揭示，但没有基因产物已被确定， 约会在细胞水平上，我们最近发现干细胞数量很大，生殖细胞进入 减数分裂直接进行，不进行过渡放大分裂。没有传播放大分裂 简化了分析，允许进行简单的分析来识别参与抑制茎中减数分裂的基因 细胞和抑制增殖的减数分裂进入，是主要原因，C。秀丽线虫是主要的动物 研究这一重要发展转变的模型。 这项建议涉及干细胞的三个主要领域-减数分裂发育/配子发生开关 在我们的知识中有很大的差距。首先，GLP-1信号转导的转录靶点， 干细胞命运和/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转录靶点，并确定其抑制的减数分裂进入途径。第二， 构成第三条减数分裂进入途径是未知的。我们的初步结果表明，SCFprom-1 泛素介导的降解复合物是第三个途径，我们提出实验来进一步测试这一点 假说.第三，gld-1 mRNA翻译/稳定性调节是生殖系干细胞的核心部分， 分化作为表达必须在干细胞中被抑制并被激活用于减数分裂;然而， GLD-1的积累是不完全理解的。我们建议（一）确定两个机制如何 已知的GLP-1转录靶抑制GLD-1积累，（ii）确定空间和定量表达， 新鉴定的生殖系干细胞分化调节因子在控制GLD-1中的作用 积累，和（iii）确定新的监管机构，因为已知的监管机构解释只有一部分的GLD-1 积累模式，作为一种途径，以确定控制发育开关的其他基因。

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.