Mechanisms of age-associated cardiac heterochromatin dysfunction

年龄相关心脏异染色质功能障碍的机制

基本信息

批准号：
9165389
负责人：
David Benner Lombard
金额：
$ 15.51万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-09-01 至 2018-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9165389
关键词：
Acetylation Age Aging Aging-Related Process Aneuploidy Attenuated Biological Assay Biology of Aging Cardiac Cardiac Myocytes Cardiac health Cardiovascular Diseases Cataloging Catalogs Cell Culture Techniques Chromatin Clinical DNA DNA Methylation Data Deacetylase Development Elderly Ensure Epigenetic Process Fluorescent in Situ Hybridization Functional disorder Genetic Genome Stability Gerontology Goals Health Heart Heterochromatin Histone H3 Histones Human Immunofluorescence Immunologic Individual Knowledge Laboratories Lead Light Link Longevity Lysine Maintenance Mammals Medicine Micrococcal Nuclease Mission Modeling Molecular Mouse Strains Mus Myocardial Myocardium Northern Blotting Nuclear Performance Phenocopy Play Ploidies Public Health Publishing Repression Research Risk Factors Role Seminal Sirtuins Structure System Testing Tissues Work age effect aged base chromatin immunoprecipitation derepression functional decline heart function improved improved functioning in vivo innovation insight interest novel novel therapeutic intervention novel therapeutics overexpression premature reconstitution segregation senescence

项目摘要

A large body of evidence indicates that 1) epigenetic alterations are a conserved feature of aging, 2) they contribute to age-associated functional decline, and 3) manipulation of epigenetic regulators can markedly increase health- and lifespan. However, knowledge regarding mechanisms of age-associated epigenetic changes is far from complete. This proposal focuses on elucidating the basis for age-associated alterations in cardiac heterochromatin. The major satellite repeats (MSRs) are a key heterochromatin component in the mouse. Twenty-five years ago, it was noted that MSR repression is attenuated with aging in mouse heart. The molecular basis for this effect has never been elucidated. Moreover, the functional impact of this derepression is unclear, although in other contexts loss of MSR silencing is associated with impaired chromosomal segregation and development of aneuploidy, a non-diploid cellular chromosomal content. The long-term goal is to understand both mechanisms and functional consequences of altered chromatin function with age. The objective of this application is to elucidate the basis for age-associated cardiac MSR derepression, and to test its impact on cardiac genomic stability. Supporting studies potentially link this effect to reduced function of the NAD+-dependent deacetylase SIRT1. The hypothesis is that acquired loss of SIRT1 function, due to reductions in NAD+ levels in the aging heart, lead in turn to impaired MSR heterochromatin structure and transcriptional derepression. It is further proposed that dysregulation of MSR heterochromatin contributes to age-associated cardiac aneuploidization. The rationale for these studies is that epigenetic changes are reversible, at least in principle. Therefore, mechanistic insight into age-associated heterochromatin alterations may identify novel therapeutic opportunities in rejuvenative medicine. The work will be carried out in the context of two Specific Aims. First, the potential role of reduced NAD+ levels and SIRT1 activity in age-associated MSR derepression will be assessed. This Aim will be carried out via chromatin immunoprecipitation, immunofluorescence, and micrococcal nuclease studies, analyzing mice of varied ages, and strains with genetic or pharmacological reconstitution of NAD+ levels or SIRT1 function in aged myocardium. Second, the functional impact of impaired MSR heterochromatinization will be assessed in the context of age-associated cardiac aneuploidization. A cell culture-based system will be developed to rigorously test functional relationships between SIRT1 activity, MSR expression, and maintenance of euploidy. This proposal is innovative, since the basis for age-associated loss of cardiac MSR silencing remains unknown. The work is significant, in that it will provide mechanistic insight into a 25-year old mystery in chromatin and aging biology. In light of published data showing that enhanced euploidy maintenance in the heart is associated with improved function at later ages, the studies in this proposal may provide insight into novel therapeutic interventions to ameliorate cardiac health in older individuals.

大量证据表明：1）表观遗传改变是衰老的一个保守特征，2）它们导致与年龄相关的功能衰退，3）表观遗传调节因子的操纵可以显着增加健康和寿命。然而，关于与年龄相关的表观遗传机制的知识改变还远未完成。该提案的重点是阐明与年龄相关的变化的基础心脏异染色质。主要卫星重复序列 (MSR) 是异染色质的关键组成部分老鼠。二十五年前，人们注意到小鼠心脏中的 MSR 抑制随着年龄的增长而减弱。这这种效应的分子基础从未被阐明。此外，这种去压抑的功能影响尚不清楚，尽管在其他情况下 MSR 沉默的丧失与染色体受损有关非整倍体（非二倍体细胞染色体内容）的分离和发育。长期目标是了解染色质功能随年龄变化的机制和功能后果。这本应用的目的是阐明与年龄相关的心脏 MSR 去抑制的基础，并测试它对心脏基因组稳定性的影响。支持研究可能将这种影响与大脑功能下降联系起来 NAD+ 依赖性脱乙酰酶 SIRT1。假设 SIRT1 功能的后天性丧失是由于减少衰老心脏中 NAD+ 水平的升高，进而导致 MSR 异染色质结构和转录受损去压抑。进一步提出，MSR 异染色质的失调有助于年龄相关的心脏非整倍体化。这些研究的基本原理是表观遗传变化是可逆的，至少在原则。因此，对与年龄相关的异染色质改变的机制洞察可能会发现新的再生医学的治疗机会。这项工作将在两个具体的背景下进行目标。首先，NAD+水平和SIRT1活性降低在年龄相关的MSR去抑制中的潜在作用将被评估。该目标将通过染色质免疫沉淀、免疫荧光和微球菌核酸酶研究，分析不同年龄的小鼠以及具有遗传或药理学特性的菌株重建衰老心肌中的 NAD+ 水平或 SIRT1 功能。二、功能障碍的影响 MSR 异染色质化将在与年龄相关的心脏非整倍化的背景下进行评估。一个细胞将开发基于文化的系统来严格测试 SIRT1 活动、MSR 之间的功能关系表达和整倍体的维持。该提案具有创新性，因为与年龄相关的损失的基础心脏 MSR 沉默的作用仍然未知。这项工作意义重大，因为它将提供机制方面的见解揭开染色质和衰老生物学领域 25 年来的谜团。根据公布的数据显示，增强心脏整倍体的维持与晚年功能的改善有关，这项研究该提案可能会为改善老年人心脏健康的新型治疗干预措施提供见解个人。