Comprehensive Myocardial Proteogenomics Profiling Reveals C/EBPα as the Key Factor in the Lipid Storage of ARVC

Arrhythmogenic
right ventricular cardiomyopathy (ARVC) is hereditary
cardiomyopathy characterized by the fibro-fatty replacement of the
myocardium. A small number of noncomprehensive profiling studies based
on human cardiac tissues have been conducted and reported; consequently,
ARVC’s gene expression pattern characteristics remain largely
undocumented. Our study applies large-scaled, quantitative proteomics
based on TMT-labeled LC–MS/MS to analyze the left and right
ventricular myocardium of four ARVC and four DCM explanted hearts
to compare them with normal hearts. Our objective is to reveal the
characteristic proteome pattern in ARVC compared with DCM as well
as nondiseased heart. We also conducted the RNA sequencing of 10 right
ventricles from ARVC hearts paired with four nondiseased donor hearts
to validate the proteome results. In a manner similar to that of the
well-defined DCM heart failure model, the ARVC model demonstrates
the downregulation of mitochondrial function proteins and the effects
of many heart failure regulators such as TGFB, RICTOR, and KDM5A.
In addition, the inflammatory signaling, especially the complement
system, was activated much more severely in ARVC than in DCM. Our
most significant discovery was the lipid metabolism reprogramming
of both ARVC ventricles in accordance with the upregulation of lipogenesis
factors such as FABP4 and FASN. We identified the key upstream regulator
of lipogenesis as C/EBPα. Transcriptome profiling verified the
consistency with proteome alterations. This comprehensive proteogenomics
profiling study reveals that an activation of C/EBPα, along
with the upregulation of its lipogenesis targets, accounts for lipid
storage and acts as a hallmark of ARVC.

致心律失常性右室心肌病（Arrhythmogenic right ventricular cardiomyopathy, ARVC）是一类以心肌组织脂肪纤维性替代为特征的遗传性心肌病。目前仅有少量基于人类心脏组织的非系统性表征分析研究被报道，因此ARVC的基因表达模式特征仍未被充分阐明。本研究采用基于TMT标记的液相色谱-串联质谱（LC–MS/MS）的大规模定量蛋白质组学技术，对4例ARVC及4例扩张型心肌病（Dilated Cardiomyopathy, DCM）的切除心脏标本的左、右心室心肌进行分析，并与正常心脏样本进行对比。本研究旨在揭示ARVC相较于DCM及正常心脏的特征性蛋白质组表达模式。此外，我们对10例ARVC心脏的右心室组织及4例正常供体心脏进行了RNA测序，以验证蛋白质组学分析结果。与已被充分表征的DCM心衰模型类似，ARVC模型同样表现出线粒体功能相关蛋白的表达下调，以及包括转化生长因子β（TGFB）、雷帕霉素不敏感伴侣蛋白（RICTOR）和赖氨酸去甲基化酶5A（KDM5A）在内的多种心衰调控因子的异常调控。此外，ARVC的炎症信号通路（尤其是补体系统）的激活程度远高于DCM。本研究最显著的发现为：ARVC双心室均出现脂质代谢重编程，表现为脂肪酸结合蛋白4（FABP4）、脂肪酸合酶（FASN）等脂质生成因子的表达上调；我们还鉴定出脂质生成的关键上游调控因子为CCAAT增强子结合蛋白α（C/EBPα）。转录组表征分析结果验证了其与蛋白质组学改变的一致性。本项全面的蛋白质基因组学表征分析研究表明，C/EBPα的激活及其下游脂质生成靶标的上调可介导脂质蓄积，这可作为ARVC的标志性病理特征。