Molecular Mechanisms of Heart Disease Resulting from Inherited Genetic Mutations

描述（由申请人提供）：肥厚型心肌病（HCM）是一种常见的心脏疾病，其特征是由于过度的肌节复制导致心脏组织增厚。肥厚型心肌病在任何年龄组的突发性意外心源性死亡中占很大比例，并且是致残性心脏症状的原因。产生的力量？心肌肌球蛋白重链（？MHC）是HCM中最常见的肌节蛋白突变之一。如何在单一的突变？MHC在HCM中的作用尚不清楚。这里提出的研究将研究不同的人类？单分子水平上的MHC突变体。实验将测试：1）在单分子水平上的变化？？心肌肌球蛋白力的产生和2）时间分数的变化？心肌肌球蛋白花结合到肌丝上，占整个ATP循环的比例。即使一个人的力量？？虽然心肌肌球蛋白突变体可以施加的力与野生型没有区别，但马达占空比的变化会影响马达集合（例如在肌节中）可以产生的总力的大小。这些实验将涉及一个新的系统来表达和纯化人类？心肌肌球蛋白、光学捕获、运动性测定和停流动力学测定。了解单点突变对单个分子的影响是了解突变马达在肥大中的作用和开发针对疾病来源的治疗方法的必要前提。 公共卫生相关性：心脏病是世界上一直存在的问题，影响所有年龄段。虽然我们在识别心脏病的症状和特征方面取得了很大进展，但我们目前的治疗和疗法受到缺乏有关疾病来源的信息的限制，这些信息来自共同工作并使心脏正常工作的单个蛋白质的水平。我建议直接研究基因突变对这些单个蛋白质的影响，以便我们能够更好地开发针对心脏病根源的治疗方法。

DESCRIPTION (provided by applicant): Hypertrophic cardiomyopathy (HCM) is a prevalent cardiac disorder characterized by thickening of heart tissue due to excessive sarcomere replication. HCM contributes to a significant percentage of sudden unexpected cardiac death in any age group and is a cause of disabling cardiac symptoms. The force generating ??cardiac myosin heavy chain (?MHC) is one of the most common sarcomeric proteins mutated in HCM. How single mutations in the ?MHC result in HCM is unclear. The research proposed here will study different human ? MHC mutants on the single molecule level. The experiments will test: 1) changes at the single molecule level in ??cardiac myosin force production and 2) changes in the fraction of time the ??cardiac myosin spends bound to the filament out of the entire ATP cycle, the duty ratio. Even if the amount of force that an individual ??cardiac myosin mutant can exert does not differ from the wild type, a change in the motor's duty ratio influences the amount of total force that an ensemble of motors can produce (such as in the sarcomere). These experiments will involve a novel system to express and purify human??-cardiac myosin, optical trapping, motility assays and stop-flow kinetic assays. Understanding the effect of single point mutations on individual molecules is a necessary precursor to both understanding the role that ensembles of mutant motors play in hypertrophy and developing therapies that target the source of the disease. PUBLIC HEALTH RELEVANCE: Heart disease is an ever-present problem in the world, affecting all ages. Though we have made great progress in identifying symptoms and characteristics of heart disease, our current treatments and therapies are limited by a lack of information about the sources of the disease, on the level of the individual proteins that work together and make a heart function properly. I propose to directly study the influence of genetic mutations on these individual proteins that so that we can better develop treatments that target the source of heart disease.