DETERMINANTS OF SELF-RENEWAL, DIFFERENTIATION, AND REPROGRAMMING OF HESCS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 目的：人类胚胎干细胞是一种特殊的细胞，因为它可以无限生长，并可以分化为所有其他类型的细胞。在这里，我们将试图了解为什么人类胚胎干细胞具有如此显著的发育潜力，并开发条件将潜力更有限的细胞转化为胚胎干细胞。这种重新编程对移植和再生医学有影响。 了解人类胚胎干细胞(ES)如何无限制地增殖，同时保持分化为任何细胞类型的能力，是将该提案的三个单独项目联系在一起的主题。项目1将使用一种新的质谱学技术在人类ES细胞中识别新的组蛋白修饰，该技术允许前所未有的能力来识别和绘制翻译后蛋白质修饰。人类ES细胞中的组蛋白修饰将在全球范围内、在启动子和由关键的多能性因子直接调节的特定基因上确定。我们还将研究组蛋白H3变体在建立长期表观遗传记忆中的作用。这些研究将确定在多能细胞中是否存在新的组蛋白密码，并确定组蛋白修饰在分化过程中如何动态变化。项目2研究了在BMP诱导分化时，人类ES细胞承诺退出多能状态的时间窗内发生的关键事件。该项目将提供对人类胚胎干细胞退出多能性状态的过程的更多了解，并指定不同的谱系结果。项目3将确定ES细胞特异性基因的组合，这些基因可以将分化后的细胞重新编程为多能状态。我们先前已经报道，当髓系细胞与人ES细胞融合时，髓系核被重新编程为ES细胞状态，表明ES细胞中的交易因子足以介导核重新编程。我们的初步结果表明，过度表达人类ES细胞丰富的基因组合可以对髓系细胞进行重新编程，该项目将优化这种重新编程。这些项目的结合将提供对多能性状态以及细胞离开或返回该状态的基本过程的更多了解。这样的理解对移植和再生医学将是重要的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: Human ES cells are special because they can grow without limit and can give rise to all other cell types. Here we will try to understand why human ES cells have this remarkable developmental potential, and develop conditions to convert a cell with a more limited potential to an ES cell. Such reprogramming has implications for transplantation and regenerative medicine. Understanding how human embryonic stem (ES) cells can proliferate without limit and yet retain the ability to differentiate to any cell type is the theme that links the three individual projects of this proposal. Project 1 will identify novel histone modifications in human ES cells using a new mass spectrometry technique that allows an unprecedented ability to identify and map posttranslational protein modifications. Histone modifications in human ES cells will be identified globally, at promoters, and at select genes directly regulated by critical pluripotency factors. We will also examine the role of histone H3 variants in establishing long-term epigenetic memory. These studies will determine whether there is a novel histone code in pluripotent cells and determine how histone modifications change dynamically during differentiation. Project 2 examines the critical events that occur in the window of time during which human ES cells commit to exit the pluripotent state upon BMP-induced differentiation. This project will provide an increased understanding of the processes that commit human ES cells to exit the pluripotent state and specify different lineage outcomes. Project 3 will identify combinations of ES cell-specific genes that can reprogram differentiated cells to a pluripotent state. We have previously reported that when myeloid cells are fused with human ES cells, the myeloid nucleus is reprogrammed to an ES cell state, indicating that transacting factors in ES cells are sufficient to mediate nuclear reprogramming. Our preliminary results suggest that over expressing combinations of human ES cell-enriched genes can reprogram myeloid cells, and this project will optimize this reprogramming. The combination of these projects will provide an increased understanding of the pluripotent state and the basic processes by which a cell can leave or return to that state. Such an understanding will be important to transplantation and regenerative medicine.