Alcohol and Muscle Stem Cells

描述(由申请人提供)：过量饮酒是非缺血性扩张型心肌病的主要原因。虽然酒精性心肌病的发病机制尚不清楚，但酒精及其主要代谢物乙醛的直接毒性作用已被推测。直到最近，心脏一直被视为由终末分化细胞形成的器官。然而，已经出现的数据支持心脏和心脏外来源的干细胞的存在，能够取代死亡的心肌细胞。这项提议试图验证这样一种假设，即酒精损害心脏的一个核心机制是通过削弱内源性干细胞取代受损心脏组织的能力。我们建议使用细胞和整个动物的方法来检验这一假说，并探索细胞疗法治疗酒精损伤心脏的潜在用途。为了开始我们的研究，我们将寻求量化酒精暴露期间的心肌干细胞替代，以及来自骨髓的替代细胞的贡献。本申请中提供的初步数据表明，酒精可以直接影响骨骼卫星细胞的分化。我们将通过探索酒精对从心脏分离的祖细胞以及胚胎干细胞的心肌细胞特异性分化的影响来扩展这些研究。组织特异性干细胞分化需要谱系决定转录因子的协调输入。我们的初步数据显示，酒精单独以及与代谢酶酒精脱氢酶(ADH)一起显著降低心脏决定转录因子GATA4的转录活性。为了更好地了解酒精如何直接影响心脏特异干细胞分化，我们将研究酒精如何影响GATA4依赖的转录。最后，为了更好地了解酒精代谢和乙醛对心脏干细胞的影响，我们将研究在心脏中表达酒精脱氢酶的转基因小鼠品系。通过将心脏祖细胞暴露在酒精中，无论是否有ADH过表达，我们将寻求更好地了解乙醇及其主要代谢物对祖细胞增殖和分化的影响。为了完成我们的分析，我们将试图将酒精性肌病的收缩异常与干细胞数量相关联，然后确定外源性干细胞替代在实验性酒精性心肌病治疗中的作用。酒精性心肌病仍然是一个重大的公共卫生问题。本申请中概述的研究旨在为酒精在干细胞组织修复中的作用提供必要的见解。

DESCRIPTION (provided by applicant): Excessive alcohol intake is a leading cause of non-ischemic dilated cardiomyopathy. While the pathogenesis of alcoholic cardiomyopathy is poorly understood, a direct toxic role for alcohol and its principal metabolite acetaldehyde has been postulated. Until recently, the heart has been viewed as an organ formed from terminally differentiated cells. Data have emerged however to support the existence of cardiac- and extra-cardiac-derived stem cells capable of replacing dead myocardial cells. This proposal seeks to test the hypothesis that one central mechanism by which alcohol damages the heart is by impairing the ability of endogenous stem cells to replace damaged heart tissue. We propose to use cellular and whole animal approaches to test this hypothesis and to explore the potential use of cellular therapies for treatment of the alcohol-damaged heart. To begin our study we will seek to quantify cardiomyocyte stem cell replacement during alcohol exposure, as well the contribution of replacement cells derived from the bone marrow. Preliminary data presented in this application demonstrates that alcohol can directly affect skeletal satellite cell differentiation. We will extend these studies by exploring the effect of alcohol on progenitor cells isolated from the heart as well as the cardiomyocyte-specific differentiation of embryonic stem cells. Tissue-specific stem cell differentiation requires the coordinated input of lineage-determining transcription factors. As shown in our preliminary data, alcohol alone and in conjunction with the metabolic enzyme alcohol dehydrogenase (ADH), significantly reduces the transcriptional activity of the cardiac determination transcription factor GATA4. To better understand how alcohol may directly affect cardiac-specific stem cell differentiation we will study how alcohol affects GATA4-dependent transcription. Finally to better understand the impact of alcohol metabolism and acetaldehyde on cardiac stem cells we will study a transgenic line of mice that express alcohol dehydrogenase in the heart. By exposing heart progenitor cells to alcohol, with and without ADH overexpression, we will seek to better understand the effect of ethanol and its principal metabolite on progenitor cell proliferation and differentiation. To complete our analysis we will seek to correlate the contractile abnormalities of alcoholic myopathy with stem cell number, and then determine the role of exogenous stem cell replacement in the treatment of experimental alcoholic cardiomyopathy. Alcoholic cardiomyopathy remains a significant public health problem. Studies outlined in this application are designed to provide needed insight into the role of alcohol on stem cell-based tissue-repair.