Determinants of Self-Renewal, Differentiation, and Reprogramming of hESCs

描述：(申请人提供)：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连接本提案三个单独项目的主题。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检查了在人类胚胎干细胞将分化的细胞提交给多能状态的时间窗口内发生的关键事件。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。 人类胚胎干细胞是特殊的，因为它们可以无限制地生长，并可以分化出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。

DESCRIPTION: (provided by applicant): 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 eprogram 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. Lay Description: 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.