Role of the Histone Modifier KDM6A in Stem Cell Differentiation

组蛋白修饰剂 KDM6A 在干细胞分化中的作用

• 批准号: 8185689
• 负责人: Min Gyu Lee
• 金额: $ 29.86万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8185689
• 关键词: Affect; Architecture; Biochemical; Biological; Biological Process; Cell Line; Cells; Chromatin; Complex; Data; Development; ES Cell Line; Embryonal Carcinoma; Enzymes; Epigenetic Process; Event; Gene Activation; Gene Cluster; Gene Expression; Gene Expression Regulation; Gene Silencing; Gene Targeting; Genes; Genetic Transcription; Histone H3; Histones; Homeobox Genes; Human; Individual; Link; Location; Lysine; Malignant Neoplasms; Maps; Mediating; Medical; Methylation; Methyltransferase; Modification; Molecular; Neuronal Differentiation; Neurons; Nucleic Acid Regulatory Sequences; Play; Process; Promoter Regions; Proteins; Resolution; Role; Science; Signal Transduction; Site; Stem Cell Research; Stem cells; Therapeutic; Therapeutic Uses; Transactivation; Transcriptional Activation; Transcriptional Regulation; Tretinoin; Undifferentiated; anticancer research; base; cancer stem cell; cell type; chromatin immunoprecipitation; cofactor; demethylation; design; embryonic stem cell; gene repression; genome-wide; human stem cells; innovation; insight; leukemia; novel; promoter; reconstitution; research study; small molecule; stem cell differentiation

DESCRIPTION (provided by applicant): Histone lysine (K) methylation has emerged as a key epigenetic mark associated with transcriptional regulation of gene expression. In particular, trimethylation at histone H3 lysine 27 (H3K27me3) is linked with gene silencing, whereas trimethylation at histone H3 lysine 4 (H3K4me3) is highly correlated with gene activation. H3K4me3 and H3K27me3 occupy and affect 68-75% and 7%, respectively, of all human gene- regulatory regions in embryonic stem cells and play critical roles in numerous epigenetic processes, including stem cell differentiation. Interestingly, these two types of methylation with opposing roles co-occupy many promoter regions, forming so-called bivalent domains that can be resolved to monovalent domains containing only H3K4me3 during cellular differentiation. Bivalent domains are transcriptionally inactive, indicating a dominant role for H3K27me3 over H3K4me3. Recently, we identified the H3K27 demethylase KDM6A (also called UTX), a long-sought histone methylation modifier that up-regulates gene expression by demethylating H3K27me3. Our long-term objective is to define the epigenetic role of KDM6A in stem cell differentiation. Our KDM6A knockdown experiments indicate that KDM6A acts as a key epigenetic regulator for retinoic acid- induced differentiation of the human stem cell line NT2/D1. Importantly, we previously showed that KDM6A interacts with the H3K4 methyltransferases mixed-lineage leukemia (MLL) 3/4 in a histone modifier complex. Therefore, the KDM6A complex is able to catalyze enzymatic processes for both H3K4 methylation and H3K27 demethylation by which bivalent domains can be resolved to monovalent domains. Consistent with this, our additional preliminary data indicate that in both NT2/D1 and the ES cell line H9, KDM6A contributes to the resolution of bivalent domains at the promoters of several key development/differentiation-specific HOX genes. Based on these exciting preliminary results, our central hypothesis is that KDM6A plays an essential role in stem cell differentiation by modifying key epigenetic signatures, such as bivalent domains, in cooperation with its associated proteins. The focus of this proposed study is on understanding the functions of KDM6A and its associated proteins in mediating stem cell differentiation and their roles in modifying epigenetic signatures of stem cells. Here, we propose the following three specific aims: 1) Characterize the role of KDM6A in mediating stem cell differentiation; 2) Determine the role of KDM6A in modifying bivalent domains; and 3) Define the roles of the KDM6A-associated proteins in KDM6A-mediated cellular differentiation. These studies will uncover the unprecedented roles for the epigenetic modifier KDM6A and its cofactor proteins in stem cell differentiation and are fundamental to our understanding at the molecular level of how key epigenetic signatures, such as bivalent domains, are modified during stem cell differentiation. PUBLIC HEALTH RELEVANCE: The studies proposed here are designed to provide molecular mechanistic insights into how the differentiation of stem cells is mediated by the epigenetic modifier KDM6A and its partner proteins and how bivalent domains, a key epigenetic signature of stem cells, are resolved in such epigenetic event. Given that stem cells have numerous potential therapeutic and medical uses, a better understanding of the molecular basis underlying the lineage commitment of stem cells may enable the design of a safe, practical strategy for the therapeutic use of stem cells. In addition, our findings will likely be applicable to the pharmacological manipulation of the lineage commitment of stem cells involving small molecule modulators of KDM6A.

描述(由申请人提供)：组蛋白赖氨酸(K)甲基化已成为与基因表达转录调控相关的关键表观遗传标记。特别是，组蛋白H3赖氨酸27(H3K27me3)的三甲基化与基因沉默有关，而组蛋白H3赖氨酸4(H3K4me3)的三甲基化与基因激活高度相关。H3K4me3和H3K27me3分别占据和影响人类胚胎干细胞基因调控区的68-75%和7%，并在包括干细胞分化在内的许多表观遗传过程中发挥关键作用。有趣的是，这两种类型的甲基化具有相反的作用，共同占据了许多启动子区域，形成了所谓的二价域，在细胞分化过程中可以分解为只含有H3K4me3的单价域。二价结构域在转录上不活跃，表明H3K27me3比H3K4me3起主导作用。最近，我们发现了H3K27去甲基酶KDM6A(又称UTX)，它是一种长期寻找的组蛋白甲基化修饰物，通过去甲基化H3K27me3上调基因表达。我们的长期目标是确定KDM6A在干细胞分化中的表观遗传学作用。我们的KDM6A基因敲除实验表明，KDM6A在维甲酸诱导的人干细胞系NT2/D1分化中起着关键的表观遗传调节作用。重要的是，我们先前证明KDM6A与H3K4甲基转移酶混合系白血病(MLL)3/4在组蛋白修饰物复合体中相互作用。因此，KDM6A络合物能够催化H3K4甲基化和H3K27去甲基化的酶过程，通过这些过程可以将二价结构域解析为一价结构域。与此一致，我们的其他初步数据表明，在NT2/D1和ES细胞系H9中，KDM6A有助于在几个关键的发育/分化特异性HOX基因的启动子上解析二价结构域。基于这些令人兴奋的初步结果，我们的中心假设是KDM6A通过修改关键的表观遗传特征，如二价结构域，与其相关蛋白合作，在干细胞分化中发挥重要作用。这项拟议的研究的重点是了解KDM6A及其相关蛋白在调节干细胞分化中的功能，以及它们在修改干细胞表观遗传特征方面的作用。在这里，我们提出了以下三个具体目标：1)表征KDM6A在介导干细胞分化中的作用；2)确定KDM6A在修饰二价结构域中的作用；以及3)确定KDM6A相关蛋白在KDM6A介导的细胞分化中的作用。这些研究将揭示表观遗传修饰物KDM6A及其辅因子蛋白在干细胞分化中前所未有的作用，对于我们在分子水平上理解关键的表观遗传特征，如二价结构域，在干细胞分化过程中如何被修改是基本的。 与公共卫生相关：这里提出的研究旨在提供关于干细胞分化如何由表观遗传修饰物KDM6A及其伙伴蛋白介导，以及如何在这种表观遗传事件中解决干细胞的关键表观遗传特征的二价域的分子机制见解。鉴于干细胞具有许多潜在的治疗和医疗用途，更好地了解干细胞的谱系承诺背后的分子基础可能有助于设计一种安全、实用的干细胞治疗使用策略。此外，我们的发现可能适用于涉及KDM6A小分子调节剂的干细胞谱系承诺的药理学操作。