Molecular Mechanisms of Regeneration Termination

项目摘要 干细胞增殖的分子机制是在过程中精确控制的， 对再生的认识很少。也就是说，受损组织如何感知何时终止 再生过程中，灭活干细胞有丝分裂活动，并组织ECM的完整性仍然是根本 没有答案的问题再生组织中干细胞的不受控制的增殖可导致肿瘤 阵果蝇中肠肠干细胞（ISC）是近年来出现的一个有吸引力的模型 研究组织稳态和再生的系统。这是由于遗传控制的惊人相似性 和细胞组成之间的果蝇和哺乳动物的消化系统，以及强大的遗传 该模型中的工具。重要的是，果蝇ISC增殖是响应组织 以刺激组织修复。利用这个模型系统，已经进行了一些研究， 揭示激活ISC增殖的途径。 尽管对干细胞增殖能力的激活有丰富的知识，但在很大程度上， 目前还不清楚组织如何在再生结束时适当地下调干细胞增殖，以及组织如何在再生结束时适当地下调干细胞增殖。 这一过程与上皮重塑有关。我们最近建立了果蝇ISCs作为一个优秀的 模型研究再生终止的分子基础。使用RNA-seq，我们鉴定了 在再生的不同阶段上调/下调的基因和途径。其中，我们 发现dMOV 10是microRNA（miRNA）基因沉默复合物的一种成分，是基因沉默所必需的。 正确终止再生过程。进一步的分析确定了直接靶向mRNA， 包含dMOV 10的miRISC，包括狒狒（激活素信号传导的I型受体）和两种主要的非- 整合素ECM受体、Syndecan（一种跨膜硫酸乙酰肝素蛋白聚糖）和Dystroglycan（一种 肌营养不良蛋白-糖蛋白复合物的完整膜组分）。除了确定 dMOV 10作为终止阶段特异性基因，该相同的RNA-seq分析显示关键组分 对于分隔连接，肌动蛋白调节因子在再生过程中特异性上调， 后期正常水平。 在这个建议中，我们将定义这些关键分子在干细胞失活和ECM重塑。 果蝇中肠再生的终止阶段通过以下特定目的。目标1. 确定中肠再生中隔连接成分的作用。目标2.定义SDC的角色 和Dg在ECM重塑中的作用。目标3。定义miRNA介导的网络的全球格局。

Project Summary The molecular mechanisms by which stem cell proliferation is precisely controlled during the course of regeneration are poorly understood. Namely, how a damaged tissue senses when to terminate the regeneration process, inactivates stem cell mitotic activity, and organizes ECM integrity remain fundamental unanswered questions. Uncontrolled proliferation of stem cells in regenerative tissues can result in tumor formation. The Drosophila midgut intestinal stem cell (ISC) has recently emerged as an attractive model system to study tissue homeostasis and regeneration. This is due to striking similarities in genetic control and cellular composition between the Drosophila and mammalian digestive systems, and powerful genetic tools available in this model. Importantly, Drosophila ISC proliferation is promoted in response to tissue damage to stimulate tissue repair. Using this model system, a number of studies have been conducted to reveal the pathways that activate ISC proliferation. Despite a wealth of knowledge on the activation of proliferative capacity of stem cells, it is largely unknown how the tissue properly down-regulates stem cell proliferation at the end of regeneration and how this process is linked to epithelial remodeling. We recently established the Drosophila ISCs as an excellent model to study the molecular basis for regeneration termination. Using RNA-seq, we identified sets of genes and pathways that are up/down-regulated at different phases of regeneration. Among these, we found that dMOV10, a component of the microRNA (miRNA) gene silencing complex, is required for the proper termination of the regeneration process. Further analyses identified direct target mRNAs of dMOV10-containing miRISC, including baboon (the Type I receptor of activin signaling) and two major non- integrin ECM receptors, Syndecan (a transmembrane heparan sulfate proteoglycan) and Dystroglycan (an integral membrane component of the dystrophin-glycoprotein complex). In addition to the identification of dMOV10 as a termination stage-specific gene, this same RNA-seq analysis showed that key components for septate junctions, and actin regulators are specifically upregulated during regeneration and return to normal level at a late stage. In this proposal, we will define these key molecules in stem cell inactivation and ECM remodeling at the termination stage of Drosophila midgut regeneration through the following Specific Aims. Aim 1. Determine the role of septate junction components in midgut regeneration. Aim 2. Define the role of Sdc and Dg in ECM remodeling. Aim 3. Define the global landscape of the miRNA-mediated network.