The inhibitory subunit of cardiac troponin (cTnI) is modified by arginine methylation in the human heart
The inhibitory subunit of cardiac troponin (cTnI) is modified by arginine methylation in the human heart
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DOI：
10.1016/j.ijcard.2019.01.102
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发表时间：
2019-05-01
影响因子：
3.5
通讯作者：
Beltran-Alvarez, Pedro
中科院分区：
文献类型：
--
作者：
Onwuli, Donatus O.;Samuel, Sabrina Francesca;Beltran-Alvarez, Pedro
背景：心肌肌钙蛋白抑制亚基（cTnl）是心脏生物标志物的金标准，也是心肌细胞兴奋-收缩偶联的必需蛋白。通过对cTnl进行翻译后修饰，cTnl与其他蛋白的相互作用得以微调。cTnl突变可导致肥厚性心肌病。方法和结果：本文首次报道了人心肌中精氨酸甲基化修饰cTnl。使用Western blot，我们观察到与扩张型心肌病活检相比，人类肥厚性心肌病患者的cTnl精氨酸甲基化水平降低。同样，使用心脏肥厚的大鼠模型，我们观察到与假对照组相比，cTnl精氨酸甲基化水平降低。利用质谱法，我们在人类心脏样本中鉴定了R74/R79和R146/R148的cTnl甲基化位点。R146和R148位于关键的cTnl抑制肽和开关肽之间；PRMT1甲基化了R146和R148的延伸抑制肽。与肥厚性心肌病相关的R145突变在体外阻碍了PRMT1对R146/R148的甲基化。转染编码甲基化缺陷R146A/R148A cTnl蛋白的质粒的H9c2心脏样细胞出现细胞肥大，与对照细胞相比，72小时后细胞大小增加32%。讨论：我们的结果为一种新颖而重要的cTnl翻译后修饰提供了证据。我们的工作为cTnI精氨酸甲基化作为疾病生物标志物的转化研究打开了大门，这些疾病包括心肌病、心肌梗死和心力衰竭，并为研究cTnI突变在抑制开关肽中的作用提供了一种新的方法。(C) 2019 Elsevier B.V.版权所有
Background: The inhibitory subunit of cardiac troponin (cTnl) is a gold standard cardiac biomarker and also an essential protein in carcliomyocyte excitation-contraction coupling. The interactions of cTnl with other proteins are fine-tuned by post-translational modification of cTnl. Mutations in cTnl can lead to hypertrophic cardioniyopathy. Methods and results: Here we report, for the first time, that cTnl is modified by arginine methylation in human myocardium. Using Western blot, we observed reduced levels of cTnl arginine methylation in human hypertrophic cardiomyopathy compared to dilated cardiomyopathy biopsies. Similarly, using a rat model of cardiac hypertrophy we observed reduced levels of cTnl arginine methylation compared to sham controls. Using mass spectrometry, we identified cTnl methylation sites at R74/R79 and R146/R148 in human cardiac samples. R146 and R148 lie at the boundary between the critical cTnl inhibitory and switch peptides; PRMT1 methylated an extended inhibitory peptide at R146 and R148 in vitro. Mutations at R145 that have been associated with hypertrophic cardiomyopathy hampered R146/R148 methylation by PRMT1 in vitro. H9c2 cardiac-like cells transfectecl with plasmids encoding for a methylation-deficient R146A/R148A cTnl protein developed cell hypertrophy, with a 32% increase in cell size after 72 h, compared to control cells. Discussion: Our results provide evidence for a novel and significant cTnl post-translational modification. Our work opens the door to translational investigations of cTnl arginine methylation as a biomarker of disease, which can include e.g. cardiomyopathies, myocardial infarction and heart failure, and offers a novel way to investigate the effect of cTnI mutations in the inhibitory switch peptides. (C) 2019 Elsevier B.V. All rights reserved.