背景:致心律失常性心肌病(ACM)是一种以进行性心肌纤维化和心力衰竭为特征的遗传性心肌病。然而,驱动ACM心脏纤维化和心力衰竭进展的确切机制仍然难以捉摸。这项研究旨在探讨新发现的Desmoglein-2(DSG2)变异引起的ACM进行性心肌纤维化的潜在机制。
方法:我们使用全外显子组测序在一个有8名ACM患者的家庭中鉴定了纯合DSG2F531C变体,并产生了Dsg2F536C敲入小鼠。使用从Dsg2F536C敲入小鼠分离的新生儿和成年小鼠心室肌细胞。我们表现出功能性,转录组和质谱分析,以评估DSG2F531C变体引起的ACM的机制。
结果:所有8例ACM患者均为DSG2F531C变体纯合。Dsg2F536C/F536C小鼠显示心脏扩大,功能障碍,和两个心室的进行性心脏纤维化。机制研究表明,变体DSG2-F536C蛋白发生了错误折叠,导致其在内质网内被BiP识别,引发内质网应激,激活PERK-ATF4信号通路并增加心肌细胞中的ATF4水平。ATF4升高促进心肌细胞TGF-β1的表达,从而通过旁分泌信号激活心脏成纤维细胞并最终促进Dsg2F536C/F536C小鼠的心脏纤维化。值得注意的是,在Dsg2F536C/F536C小鼠中,PERK-ATF4信号传导的抑制减弱了进行性心脏纤维化和心脏收缩功能障碍。
结论:心肌细胞中ATF4/TGF-β1信号的过度激活是ACM进行性心肌纤维化的一种新的机制。靶向ATF4/TGF-β1信号传导可能是管理ACM的新治疗靶标。
BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized with progressive cardiac fibrosis and heart failure. However, the exact mechanism driving the progression of cardiac fibrosis and heart failure in ACM remains elusive. This study aims to investigate the underlying mechanisms of progressive cardiac fibrosis in ACM caused by newly identified Desmoglein-2 (DSG2) variation.
METHODS: We identified homozygous DSG2F531C variant in a family with 8 ACM patients using whole-exome sequencing and generated Dsg2F536C knock-in mice. Neonatal and adult mouse ventricular myocytes isolated from Dsg2F536C knock-in mice were used. We performed functional, transcriptomic and mass spectrometry analyses to evaluate the mechanisms of ACM caused by DSG2F531C variant.
RESULTS: All eight patients with ACM were homozygous for DSG2F531C variant. Dsg2F536C/F536C mice displayed cardiac enlargement, dysfunction, and progressive cardiac fibrosis in both ventricles. Mechanistic investigations revealed that the variant DSG2-F536C protein underwent misfolding, leading to its recognition by BiP within the endoplasmic reticulum, which triggered endoplasmic reticulum stress, activated the PERK-ATF4 signaling pathway and increased ATF4 levels in cardiomyocytes. Increased ATF4 facilitated the expression of TGF-β1 in cardiomyocytes, thereby activating cardiac fibroblasts through paracrine signaling and ultimately promoting cardiac fibrosis in Dsg2F536C/F536C mice. Notably, inhibition of the PERK-ATF4 signaling attenuated progressive cardiac fibrosis and cardiac systolic dysfunction in Dsg2F536C/F536C mice.
CONCLUSIONS: Hyperactivation of the ATF4/TGF-β1 signaling in cardiomyocytes emerges as a novel mechanism underlying progressive cardiac fibrosis in ACM. Targeting the ATF4/TGF-β1 signaling may be a novel therapeutic target for managing ACM.