S-glutathiolation of cardiac myosin-binding protein C in contractile dysfunction

心力衰竭（HF）是一种由多种原因引起的临床综合征，是人类死亡的主要因素之一。了解控制心脏功能的分子机制及其在疾病发展过程中的修饰可能会确定可能为新治疗策略提供靶点的关键因素。心肌肌球蛋白结合蛋白C （cMyBP-C）是一种厚纤维相关蛋白，参与肌节完整性的维持和收缩舒张的调节。重要的是，n端m结构域内cMyBP-C的磷酸化导致跨桥循环动力学加速，并通过去除肌球蛋白头部的结构约束来产生力。此外，磷酸化已被描述为在疾病条件下保护肌丝免受酶降解，如缺血/再灌注。我们已经获得证据表明cMyBP-C受到氧化翻译后修饰，即s -谷胱甘肽化。我们将cMyBP-C C1-M-C2结构域内的一个s -谷胱甘肽位点定位到半胱氨酸249，靠近磷酸化调节的m结构域。然而，cMyBP-C在Cys249位点的s -谷胱甘肽化是否会影响心肌细胞和整个心脏功能，以及磷酸化和氧化在健康和疾病中的相互作用和平衡，值得深入研究。因此，我们提出(1)在体外研究s -谷胱甘肽化对cMyBP-C功能的影响；(2)阐明磷酸化和氧化之间潜在的串音；(3)在（病理）生理条件下研究s -谷胱甘肽化对体内cMyBP-C功能的影响。该项目将有助于更好地了解收缩功能障碍的分子机制，并可能为推进新型治疗策略的发展提供视角。

Heart failure (HF) is a clinical syndrome that arises from diverse causes and remains one of the leading factors of human mortality. Understanding the molecular mechanisms that govern cardiac function and their modifications during disease development is likely to identify key elements that might provide targets for novel treatment strategies. Cardiac myosin-binding protein C (cMyBP-C) is a thick filament-associated protein involved in the maintenance of sarcomere integrity and in the regulation of contraction and relaxation. Importantly, phosphorylation of cMyBP-C within the N-terminal M-domain leads to acceleration of cross-bridge cycling kinetics and force generation through removal of a structural constraint on myosin heads. Furthermore, phosphorylation has been described to protect myofilaments from enzymatic degradation under disease conditions, such as ischemia/reperfusion. We have obtained evidence that cMyBP-C is subject to oxidative post-translational modification, namely S-glutathiolation. We mapped one S-glutathiolation site within the C1-M-C2 domain of cMyBP-C to cysteine 249, in close vicinity to the phosphorylation-regulated M-domain. However, whether S-glutathiolation of cMyBP-C at Cys249 impacts on cardiac myocyte and whole heart function and the interplay and balance between phosphorylation and oxidation in health and disease warrants thorough investigation. Therefore, we propose (1) to explore the effect of S-glutathiolation on cMyBP-C function in vitro, (2) to elucidate a potential crosstalk between phosphorylation and oxidation and (3) to investigate the impact of S-glutathiolation on cMyBP-C function in vivo under (patho)physiological conditions. The project will lead to a better understanding of the molecular mechanisms underlying contractile dysfunction and may provide perspective to advance the development of novel treatment strategies.