The HCM-causing Y235S cMyBPC mutation accelerates contractile function by altering C1 domain structure
The HCM-causing Y235S cMyBPC mutation accelerates contractile function by altering C1 domain structure
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DOI：
10.1016/j.bbadis.2019.01.007
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发表时间：
2019-03-01
影响因子：
6.2
通讯作者：
Stelzer, Julian E.
中科院分区：
文献类型：
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作者：
Doh, Chang Yoon;Li, Jiayang;Stelzer, Julian E.
心肌肌球蛋白结合蛋白C(CMyBPC)基因突变是肥厚型心肌病(HCM)的主要原因。特别是，人类第237位酪氨酸到丝氨酸的单一氨基酸替代(老鼠第235位残基)与肥厚性心肌病有很强的疾病关联性。虽然cMyBPC的截断、缺失和插入以及移码突变已经被研究过，但对错义突变在cMyBPC中的功能后果知之甚少。在这项研究中，我们通过进行力学实验和分子动力学模拟(MDS)来表征导致HCM的Y235S突变的功能和结构效应。将野生型(WT)或Y235S cMyBPC(KOY235S)病毒导入cMyBPC基因缺失的小鼠心肌。我们发现Y235S cMyBPC基因正确表达并整合到心肌肌节中，提示Y235S突变的致病机制不是单倍体功能不全或毒肽。机械实验表明，与KOY235S心脏相比，KOY235S心脏经洗涤剂处理后的心肌表现出超收缩行为，表现为跨桥动力学加速和钙离子对力产生的敏感性增加。此外，MDS显示Y235S突变导致cMyBPC的C1区重要的分子内相互作用、表面构象和静电电位的改变。我们在体外和计算机中的联合数据表明，Y235S突变直接破坏了cMyBPC C1域的内部和表面性质，这可能改变其配体结合作用。这些分子变化可能是过度收缩跨越桥行为的基础，最终导致心肌肥厚和活体心功能障碍的发展。
Mutations in cardiac myosin binding protein C (cMyBPC) are a major cause of hypertrophic cardiomyopathy (HCM). In particular, a single amino acid substitution of tyrosine to serine at residue 237 in humans (residue 235 in mice) has been linked to HCM with strong disease association. Although cMyBPC truncations, deletions and insertions, and frame shift mutations have been studied, relatively little is known about the functional consequences of missense mutations in cMyBPC. In this study, we characterized the functional and structural effects of the HCM-causing Y235S mutation by performing mechanical experiments and molecular dynamics simulations (MDS). cMyBPC null mouse myocardium was virally transfected with wild-type (WT) or Y235S cMyBPC (KOY235S). We found that Y235S cMyBPC was properly expressed and incorporated into the cardiac sarcomere, suggesting that the mechanism of disease of the Y235S mutation is not haploinsufficiency or poison peptides. Mechanical experiments in detergent-skinned myocardium isolated from KOY235S hearts revealed hypercontractile behavior compared to KOWT hearts, evidenced by accelerated cross-bridge kinetics and increased Ca2+ sensitivity of force generation. In addition, MDS revealed that the Y235S mutation causes alterations in important intramolecular interactions, surface conformations, and electrostatic potential of the C1 domain of cMyBPC. Our combined in vitro and in silico data suggest that the Y235S mutation directly disrupts internal and surface properties of the C1 domain of cMyBPC, which potentially alters its ligand-binding interactions. These molecular changes may underlie the mechanism for hypercontractile cross-bridge behavior, which ultimately results in the development of cardiac hypertrophy and in vivo cardiac dysfunction.