Epigenetic Regulation of Germ Cell Derivation from heSCs

这个项目的目标是定义区分人类原始生物的遗传和表观遗传特征。 人类胚胎干细胞(HESCs)中的生殖细胞(PGCs)，特别是三甲基化(ME3) 组蛋白H3赖氨酸(K)27，以及多梳基(PcG)蛋白在PGC形成中的作用。人类 胚胎干细胞是检测人类生殖细胞形成的唯一具有遗传可塑性的基于人类细胞的模型。 来自外胚层的生殖细胞需要微妙的平衡，涉及多能基因的表达。 (如NANOG和OCT4)，抑制体细胞基因(如HOXB1和brachyury)和 独占形成配子的功能单性。生殖系单性丧失导致生殖细胞 肿瘤发生学。因此，调节生殖细胞衍生的因素的平衡被破坏，导致 不良的临床结果。在之前的工作中，克拉克博士已经证明了人类生殖细胞的来源 HESCS在独立衍生的线之间有所不同。她的初步数据现在显示，这可能是 与未分化胚胎干细胞中生殖细胞特异性基因转录的差异以及 生殖细胞表达基因启动子上H3K27me3的差异甲基化。在这个项目中，克拉克博士将 继续她对PcG蛋白和H3K27me3在调节PGC形成中的作用的研究 以下具体目标：1)在PGC发育过程中评估H3K27me3和X的重新激活 雌性hESCs；2)H3K27me3在hESCs和pGCs四个系中的全基因组定位 来源于hESCs，以及3)确定PcG抑制复合体(PCR2)在PGC中的功能 在四个独立衍生的hESCs系中形成。分享人类胚胎干细胞形成生殖细胞的研究结果 项目1和3对于理解hESC潜力是必不可少的，因为形成胚系的能力是 同时逆转以形成神经和造血谱系(多能性丧失和激活 体细胞转录程序)。从而鉴定出既能忠实的hESC品系 生殖细胞的形成和强劲的体细胞分化将构成最佳的发育模式。 以及用于未来研究的治疗工具。

The goal of this project is to define the genetic and epigenetic signature that distinguishes human primordial germ cells (PGCs) from human embryonic stem cells (hESCs) with a specific focus on trimethylation (me3) of histone H3 lysine (K) 27, and function of the Polycomb Group (PcG) proteins on PGC formation. Human ESCs are the only genetically malleable human cell-based model for examining human germ cell formation. Germ cell derivation from the epiblast requires a delicate balance involving expression of pluripotent genes (such as NANOG and OCT4), suppression of somatic genes (such as HOXB1 and BRACHYURY) and functional unipotency to exclusively form gametes. Loss of germ line unipotency results in germ cell tumorigenesis. Therefore, disruption of the balance of factors that regulate germ cell derivation results in adverse clinical outcomes. In previous work Dr. Clark has shown that derivation of human germ cells from hESCs varies between independently derived lines. Her preliminary data now reveals that this can be correlated with differences in transcription of germ cell specific genes in undifferentiated ESCs as well as differential methylation of H3K27me3 at promoters of germ cell-expressed loci. In this Project, Dr Clark will continue her research on the role of the PcG proteins and H3K27me3 in modulating PGC formation in the following specific Aims: 1) Evaluating H3K27me3 and X reactivation during PGC development in two lines of female hESCs; 2) Deciphering the genome wide localization of H3K27me3 in four lines of hESCs, and PGCs derived from hESCs, and 3) Determining the function of the PcG repressive complex (PCR2) in PGC formation in four independently derived lines of hESCs. Sharing results on germ cell formation from hESCs with Projects 1 and 3 are essential to understanding hESC potential because the ability to form germ line is simultaneously reversed to form neural and hematopoietic lineages (loss of pluripotency and activation of somatic cell transcriptional programs). Thus identification of hESC lines that are capable of both faithful germ cell formation and robust somatic cell differentiation would constitute the best developmental models and therapeutic tools for future research.