Hypoxia and cardiac stem cell homing

缺氧与心脏干细胞归巢

基本信息

批准号：
9106367
负责人：
YAO LIANG TANG
金额：
$ 38万
依托单位：
AUGUSTA UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-03-01 至 2020-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9106367
关键词：
Ablation Address Antigen-Presenting Cells Autologous Binding Binding Sites Biochemical CXC Chemokines Cardiac Cell Aging Cell Therapy Cell Transplantation Cell physiology Cells Chromatin Complex Data E2F1 gene Elderly Enhancers Enzymes Epigenetic Process Exhibits Funding Future Gene Expression Gene Silencing Gene Targeting Genes Genetic Genetic Transcription HDAC11 gene Heart Diseases Histones Homing Homologous Gene Hypoxia Impairment Interleukin-10 Lead Link Lysine Mammalian Cell Mediating Mesenchymal Stem Cells MicroRNAs Molecular Molecular Target Mus Myocardial Ischemia Myocardium Patients Polycomb Population Process Proteins Reperfusion Therapy Reporting Repression Research Role Signal Transduction Stem cell transplant Stem cells Testing Therapeutic Transplantation Treatment Efficacy age related aged angiogenesis cardiac repair cell age chemokine receptor chromatin modification high risk histone methyltransferase histone modification improved improved functioning improved outcome neovascularization novel therapeutics overexpression preconditioning promoter public health relevance research study response stem stem cell therapy tissue repair

项目摘要

DESCRIPTION (provided by applicant): Stem cell therapy is emerging as a beneficial strategy to treat patients with advanced heart disease. However, limited homing and survival of transplanted stem cells in the myocardium represents a barrier to therapeutic efficacy. During the initial term of funding, we focused on hypoxia preconditioning (HP) as a means to enhance homing and survival of cardiac stem cells by activating CXC chemokine receptor-4 (CXCR4) in HIF- 1α-dependent manner, which led to improved outcomes following cell transplantation in young mice. Unfortunately, aged C-MSC respond poorly to HP, suggesting that research into the molecular mechanisms that regulate HP in aged cells is needed to optimize this novel therapeutic strategy. Age-related impairments in tissue repair are associated with decreased neovascularization, a process that is regulated by HIF-1α- dependent signaling. Our preliminary data suggest that chromatin modifications in aged sca-1+ cardiac mesenchymal stem cells (C-MSC) may underlie impaired HIF-1α responses and compromise their function. Specifically, aged cells exhibit significantly greater histone 3 lysine 27 trimethylation (H3K27me3, a repressive chromatin modification) at the promoters of the HIF-1α target genes CXCR4 and IL-10, which are crucial regulators of stem/progenitor cell homing and survival. Moreover, aged cells exhibit increased expression of the histone methyltransferase enhancer of zeste homolog 2 (EZH2), the catalytic component of the Polycomb Repressor Complex 2 (PRC2). EZH2 is the only known enzyme capable of inducing H3K27me3 in mammalian cells. EZH2 may also cooperate with histone deacetylases (HDAC), which repress transcription by removing specific acetyl groups from histones. We hypothesize that in aged C-MSC, aberrant expression of EZH2 leads to repression of key HIF-1α-dependent genes through H3k27me3-induced gene "silencing" and by interacting with HDAC11, thus impairing HP responses and compromising therapeutic efficacy. We propose three aims to test our hypothesis. In Aim 1, we will determine the mechanisms whereby EZH2 is regulated by the transcription factor E2F1 in C-MSC, and we will target E2F1 in aged C-MSC to determine whether it is mechanistically linked to changes in EZH2 expression and function. In Aim 2, we will carry out genetic and biochemical experiments to determine whether HDAC11 functions as a part of the multi-protein EZH2-PRC2 complex that associates with the IL-10 promoter and represses HIF-1α-induced IL-10 gene expression in aged C-MSC. In Aim 3, we will ablate EZH2 in aged C-MSC to investigate functional responses to cell transplantation (i.e., cell homing, angiogenesis, cardiac repair). This will be the first i-depth study to investigate the role of epigenetic remodeling in regulating the function of aged stem cells. Our findings may lead to enhanced efficacy of cardiac stem cell therapy and identify new molecular targets that could improve cardiac repair in the elderly.

描述（由申请人提供）：干细胞疗法正在成为治疗晚期心脏病患者的有益策略，然而，移植的干细胞在心肌中的归巢和存活有限是资助初期治疗效果的障碍。，我们重点关注缺氧预处理（HP）作为一种通过以 HIF-1α 依赖性方式激活 CXC 趋化因子受体 4（CXCR4）来增强心脏干细胞归巢和存活的方法，不幸的是，老年 C-MSC 对 HP 的反应较差，这表明需要研究调节老年细胞 HP 的分子机制来优化这种与年龄相关的损伤的新治疗策略。组织修复与新血管形成减少有关，这一过程受 HIF-1α 依赖性信号传导调节。我们的初步数据表明，衰老的 sca-1+ 心脏间充质干细胞 (C-MSC) 中的染色质修饰可能是 HIF-1α 反应受损的基础。具体而言，衰老细胞在 HIF-1α 靶基因 CXCR4 和 IL-10（干细胞/祖细胞的关键调节因子）的启动子处表现出更显着的组蛋白 3 赖氨酸 27 三甲基化（H3K27me3，一种抑制性染色质修饰）。此外，衰老细胞表现出 zeste 同源物 2 (EZH2) 组蛋白甲基转移酶增强子的表达增加， Polycomb 阻遏物复合体 2 (PRC2) 的催化成分是唯一已知能够在哺乳动物细胞中诱导 H3K27me3 的酶，EZH2 也可能与组蛋白脱乙酰酶 (HDAC) 合作，通过去除组蛋白中的特定乙酰基来抑制转录。研究发现，在衰老的 C-MSC 中，EZH2 的异常表达通过以下途径导致关键 HIF-1α 依赖性基因的抑制H3k27me3 诱导基因“沉默”并与 HDAC11 相互作用，从而损害 HP 反应并损害治疗效果。在目标 1 中，我们将确定 EZH2 受转录因子 E2F1 调节的机制。 C-MSC，我们将靶向老化 C-MSC 中的 E2F1，以确定它是否与 EZH2 表达和功能的变化有机械联系。将进行遗传和生化实验，以确定 HDAC11 是否作为多蛋白 EZH2-PRC2 复合物的一部分发挥作用，该复合物与 IL-10 启动子相关并抑制老化 C-MSC 中 HIF-1α 诱导的 IL-10 基因表达。在目标 3 中，我们将消除老化 C-MSC 中的 EZH2，以研究细胞移植的功能反应（即细胞归巢、血管生成、心脏修复）。我深入研究表观遗传重塑在调节衰老干细胞功能中的作用，我们的研究结果可能会提高心脏干细胞治疗的功效，并确定可以改善老年人心脏修复的新分子靶点。