Epigenetic Regulation of Germ Cell Derivation from heSCs

这个项目的目标是确定区分人类原始的遗传和表观遗传特征 来自人胚胎干细胞（hESC）的生殖细胞（PGCs），特别关注三甲基化（me3） 组蛋白H3赖氨酸（K）27的表达，以及Polycomb Group（PcG）蛋白在PGC形成中的功能。人类 胚胎干细胞是唯一的遗传可塑性的人类细胞为基础的模型，用于检查人类生殖细胞的形成。 从外胚层分化生殖细胞需要一个微妙的平衡，涉及多能基因的表达 (such如NANOG和OCT 4），抑制体细胞基因（如HOXB 1和BRACHYURY）， 功能性单能性以专门形成配子。生殖系单能性丧失导致生殖细胞 肿瘤发生因此，调节生殖细胞衍生的因子平衡的破坏导致 不良临床结局。在以前的工作中，克拉克博士已经表明，人类生殖细胞的来源， hESC在独立衍生的系之间变化。她的初步数据显示， 与未分化胚胎干细胞中生殖细胞特异性基因转录的差异相关， H3K27me3在生殖细胞表达基因座的启动子处的差异甲基化。在这个项目中，克拉克博士将 继续研究PcG蛋白和H3K27me3在调节PGC形成中的作用。 以下具体目的：1）在两个细胞系中评估PGC发育期间H3K27me3和X的再活化， 2）破译H3K27me3在四个系的hESC和PGCs中的全基因组定位 3）确定PGC中PcG阻遏复合物（PCR 2）的功能 在四个独立衍生的hESC系中形成。分享从hESC形成生殖细胞的结果 与项目1和3是必不可少的了解hESC的潜力，因为形成生殖系的能力是 同时逆转以形成神经和造血谱系（多能性的丧失和造血干细胞的激活）。 体细胞转录程序）。因此，鉴定能够忠实表达 生殖细胞的形成和健壮的体细胞分化将构成最好的发育模型 以及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.