The Molecular Basis of Cardiac Senescence: From Transcriptomics to Function

心血管科学实验室一直致力于老化心肌的研究。为了鉴定心脏中可能与衰老有关的基因产物，采用功能基因组分析（cDNA微阵列和基因表达序列分析）分析了有热量限制或无热量限制的Fisher 344大鼠、Wistar大鼠、围产期和衰老的C57Bl/6小鼠、用涉及老年保护的生物肽治疗的CBA小鼠左心室的mRNA，以及衰竭和非衰竭心肌的人类活组织检查。这些项目的目的是确定哪些基因产物作为年龄或疾病的功能受到调节，然后使用独立的方法确定导致基因表达改变的潜在机制。2002年，我们发表了一个公开可用的小鼠心肌参考数据集（SAGE分析），我们将这些研究扩展到雄性小鼠与雌性小鼠以及年轻小鼠与老年小鼠。

The Laboratory of Cardiovascular Science has a strong commitment to the study of aging myocardium. To identify gene products in heart potentially involved in aging, functional genomic analyses (cDNA microarrays and Serial Analysis of Gene Expression) have been employed to analyze mRNA from left ventricles of Fisher 344 rats with or without caloric restriction, Wistar rats, C57Bl/6 mice during the perinatal period and with aging, CBA mice treated with biopeptides implicated in gerontoprotection, and human biopsies from failing and non-failing myocardium. The aim of these projects are to determine which gene products are regulated as a function of age or disease, and then use independent methods to determine the underlying mechanisms responsible for the altered changes in gene expression. In 2002, we published a reference dataset (SAGE analysis) of the mouse myocardium that is publicly available, and we have expanded these studies to examine male versus female mice and young versus old mice. We have completed a large-scale transcriptome analysis of an aging Fisher 344 aging rat model and compared these results with other rodent strains. We are completing an extensive quantitative-PCR analysis to validate these data, and by independent techniques, to determine the significance of the changes in gene expression with the aging process. We have expanded our aging studies in rodent to include in vitro analyses of cultured cardiomyoyctes and fibroblasts to delineate mechanisms underlying the aging response of cardiac genes, and are in the process of elucidating genetic correlates underlying these changes in transcript abundance. Finally, we have employed functional genomic techniques (microarrays) to examine the transcriptomes of LVs from failing (n=8) and non-failing human myocardium (n=7). Following identification of a pool of HF-responsive candidate genes by microarrays and statistical methods, we employed Q-PCR on a larger sample population (n=34) to validate and examine the role of contributing biological variables (age and gender). We find that most of the HF-candidate genes (including transcription factors, modifying enzymes, ECM proteins and metabolic enzymes) demonstrated significant changes in gene expression; however, the majority of the putative changes depended on variables such as sex and age, and not on HF alone. Additionally, some putative HF-responsive gene products demonstrated highly significant changes in expression as a function of age and/or sex, but independent of HF. Based on these previously published data and subsequent microarray analyses using Prediction Analysis of Microarray software, our research efforts have focused on two transcription factors - Ets1 and Ets2. Their specific roles in aging are yet to be elucidated, but from in vitro analyses, these factors are pro-apoptotic; however, the effects differ between fibroblasts and cardiomyocytes. Ets2 is preferentially pro-apoptotic in cardiomyocytes, and both Ets1 and Ets2 can be up-regulated by angiotensin II. These findings are now being expanded to tissue samples obtained from aged rodents and and recent data suggest that the mechanisms of apoptosis in fibroblasts versus cardiomyocytes differ depending on activation via Ets1 and Ets2.