Control of Trophoblast Differentiation in Placental Development

 描述（由申请人提供）：胎盘对生殖成功至关重要，胎盘缺陷是一个主要的生殖健康挑战。拟议工作的总体目标是解码滋养层分化的调节电路，以确保人类和小鼠的胎盘正常发育，这是一个关键但知之甚少的领域。BCOR编码PRC 1 Polycomb组阻遏复合物的一个组分，该复合物对小鼠胎盘发育至关重要，它提供了一个强大的工具来识别该过程背后的电路的新的关键发育调节因子。该提议的中心假设是，含BCOR的PRC 1复合物在滋养层干/祖细胞及其后代中差异部署，以沉默交替细胞命运的关键谱系决定基因。BCOR的这种细胞类型特异性靶向确保滋养层细胞类型被建立并保持其分化的命运，并且以适当的数量存在。由于许多关键的体内和体外系统和试剂的可用性，包括Bcor条件性小鼠等位基因和允许Bcor条件性缺失的干细胞系，该提议将能够从小鼠和人类的发育和机制的角度获得早期BCOR复合体功能的核心。本文提出的研究将解决三个目标中的三个关键问题，其答案将填补滋养层分化电路的主要知识空白1）Bcor如何调节体内祖细胞和分化细胞命运的分配？这一目标将确定Bcor在胎盘发育和细胞命运规范中的基本体内作用，重点是祖细胞隔室和细胞类型分配。2)哪种谱系特异性BCOR靶点网络是滋养层分化回路的基础，并解释了Bcor突变型胎盘表型？这一目标将确定小鼠培养的TS细胞、原代人滋养层细胞和BMP 4处理的hESC及其分化后代中的BCOR功能靶标。这些数据的生物信息学分析将确定滋养层分化的关键调节因子，帮助定义胎盘谱系特化的基础监管架构以及BCOR如何控制它。3）什么是谱系特异性转录因子（TF），指导细胞类型特异性靶向BCOR复合物？这个目标将确定小鼠和人类滋养层细胞类型中BCOR复合物相关的转录因子，然后测试它们是否有助于细胞类型特异性招募靶基因。这些目标的成功将产生关于滋养层分化和PcG复合物的谱系特异性募集机制的电路的基础知识。这些基本信息不仅将导致对早期胎盘发育的更深入了解，这是一个对健康和生殖至关重要的过程，而且还有望为控制干细胞分化的方法的设计提供信息。

 DESCRIPTION (provided by applicant): The placenta is of paramount importance for reproductive success and placental defects present a major reproductive health challenge. The overall objective of the proposed work is to decode the regulatory circuitry of trophoblast differentiation that ensures proper placental development in humans and mice, a crucial but poorly understood area. BCOR encodes a component of a PRC1 Polycomb group repression complex that is essential for placental development in the mouse and it provides a powerful tool to identify new key developmental regulators of the circuitry underlying this process. The central hypothesis of this proposal is that the BCOR-containing PRC1 complex is differentially deployed in trophoblast stem/progenitor cells and their progeny to silence key lineage-determining genes of alternate cell fates. This cell type-specific targeting of BCOR ensures that the trophoblastic cell types are established and maintain their differentiated fates and are present in appropriate numbers. This proposal will be able to get to the heart of early BCOR complex function from both developmental and mechanistic standpoints in both mouse and human due to the availability of many key in vivo and in vitro systems and reagents, including a Bcor conditional mouse allele and stem cell lines allowing conditional deletion of Bcor. The studies proposed here will tackle three key questions in three aims whose answers will fill major knowledge gaps about the circuitry of trophoblast differentiation 1) How does Bcor regulate the allocation of progenitor and differentiated cell fates in vivo? This aim will determine the fundamental in vivo role of Bcor in placental development and cell fate specification with a focus on progenitor cell compartments and cell type allocation. 2) Which networks of lineage-specific BCOR targets underlie the trophoblast differentiation circuitry and explain the Bcor mutant placental phenotype? This aim will define the BCOR functional targets in mouse cultured TS cells, primary human trophoblasts and BMP4-treated hESCs, and their differentiated progeny. Bioinformatic analysis of these data will identify key regulators of trophoblast differentiation an help define the regulatory architecture underlying placental lineage specification and how BCOR controls it. 3) What are the lineage-specific transcription factors (TF) that direct cell type-specfic targeting of the BCOR complex? This aim will identify BCOR complex-associated transcription factors in mouse and human trophoblast cell types and then test whether they contribute to cell type-specific recruitment to target genes. Success in these aims will generate fundamental knowledge about the circuitry underlying trophoblast differentiation and lineage-specific recruitment mechanisms of PcG complexes. This basic information will lead not only to a deeper understanding of early placental development, a process vital for health and reproduction, but also promises to inform the design of approaches to control the differentiation of stem cells.