Role of the giant protein titin in cardiac health and disease

巨型蛋白肌联在心脏健康和疾病中的作用

• 批准号: 9904740
• 负责人: Henk L. GRANZIER
• 金额: $ 88.44万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9904740
• 关键词: Address; Animal Model; Biology; Cardiac Myosins; Cardiac health; Clinical; Dilated Cardiomyopathy; Drug Screening; EFRAC; Elements; Excision; Exons; Failure; Functional disorder; Genes; Genetic Transcription; Goals; Heart; Heart Diseases; Heart failure; Location; Microfilaments; Molecular; Mutate; Mutation; Patients; Phosphorylation; Post-Translational Protein Processing; Protein Isoforms; Proteins; RNA Splicing; Research; Resolution; Role; Sarcomeres; Scientist; Stress; Striated Muscles; Structure; Talents; Techniques; Testing; Thick Filament; Time; Work; base; cardiac tissue engineering; connectin; disease-causing mutation; drug candidate; experience; heart function; innovation; myosin-binding protein C; novel; preservation; therapeutic target

Summary This proposal focuses on titin, the largest protein known, in heart function and disease. Titin forms a novel and multifunctional myofilament in the striated-muscle sarcomere with important roles that include regulating the diastolic stiffness of the heart. Recent breakthrough studies revealed that titin is of high clinical importance in both heart failure with preserved ejection fraction (HFpEF), and heart failure with reduced ejection fraction (HFrEF). Although significant progress has been made in understanding the basic biology of titin, major gaps in our understanding still remain, including a mechanistic understanding of how titin causes/contributes to heart disease. An important focus of this proposal will be on titin’s role in diastolic dysfunction, motivated by recent studies on patients with HFpEF that revealed deranged phosphorylation of titin’s molecular spring elements and diastolic stiffening. The full spectrum of posttranslational modifications that occur in HFpEF will be studied and high-resolution time-resolved spectroscopic techniques will focus on uncovering the structural changes in titin’s spring elements triggered by posttranslational modification. Drug screens will focus on identifying compounds that mimic or block these structural changes and functional studies will test whether newly discovered and candidate drugs ameliorate titin-based diastolic stiffening in HFpEF. Post-transcriptional mechanisms will be investigated as well, taking advantage of our recent work that has shown that splicing of titin can be manipulated to upregulate complaint titin isoforms and restore diastolic function. The functional efficacy of identified compounds will be tested on engineered heart tissues as well as on animal models. The second major focus of this proposal will be on titin in HFrEF. Several recent sequencing studies in large groups of patients revealed that mutations in the titin gene (TTN) are causative in ~20% of studied dilated cardiomyopathy (DCM) patients. Many of the mutations are truncation mutations (TTNtv) and they have a preferential location in the A-band segment of titin. The A-band segment is the least well-studied part of titin and an important goal of our research is to critically examine the biology of titin in this region of the sarcomere where disease-causing mutations are prominent. These studies include a focus on the role of titin in interacting with cMyBP-C (cardiac myosin-binding protein C, a clinically important thick filament protein). Animal models will be investigated in which TTNtv have been introduced in different regions of titin’s A-band segment. The effects of the mutations will be studied under baseline conditions, when stressed, and when occurring in combination with mutations in other genes. Importantly, we will also test whether excision of the mutated titin exons ameliorates titin-based DCM. In summary, capitalizing on my >20-year track record of innovative titin research, and utilizing our team of experienced scientists and talented trainees, this proposal sets ambitious goals that are expected to further accelerate understanding of the biology of titin, its role in heart disease and titin’s potential to function as a therapeutic target.

概括 该提案的重点是肌联蛋白，这是已知的最大的蛋白质，在心脏功能和疾病中形成一种新型的肌联蛋白。 横纹肌肌节中的多功能肌丝具有重要作用，包括调节 心脏舒张僵硬度最近的突破性研究表明，肌联蛋白在临床上具有很高的重要性。 射血分数保留的心力衰竭（HFpEF）和射血分数降低的心力衰竭 (HFrEF)虽然在理解肌联蛋白的基础生物学方面取得了重大进展，但仍存在重大差距。 我们的理解仍然存在，包括对肌动蛋白如何导致/影响心脏的机械理解 该提案的一个重要焦点是肌联蛋白在舒张功能障碍中的作用，这是由最近的研究推动的。 对 HFpEF 患者的研究揭示了 titin 分子弹簧元件的磷酸化紊乱和 将研究 HFpEF 中发生的全部翻译后修饰。 高分辨率时间分辨光谱技术将重点揭示肌动蛋白的结构变化 由翻译后修饰触发的弹簧元件将集中于识别化合物。 模仿或阻止这些结构变化和功能研究将测试新发现和 改善 HFpEF 中基于肌动蛋白的舒张期僵硬的候选药物将是 也进行了研究，利用我们最近的工作表明，肌动蛋白的剪接可以被操纵 上调主诉肌联蛋白亚型并恢复舒张功能已确定的功能功效。 化合物将在工程心脏组织和动物模型上进行测试。 该提案将针对 HFrEF 中的 titin，最近对大组患者进行的几项测序研究表明。 在所研究的扩张型心肌病 (DCM) 患者中，约有 20% 是由肌联蛋白基因 (TTN) 突变引起的。 许多突变是截短突变 (TTNtv)，它们优先位于 A 带 A 带片段是肌动蛋白研究最少的部分，也是我们研究的一个重要目标。 是严格检查肌小节区域中肌动蛋白的生物学特性，该区域是引起疾病的突变所在 这些研究重点关注肌联蛋白在与 cMyBP-C（心肌肌球蛋白结合）相互作用中的作用。 蛋白质 C，一种临床上重要的粗丝蛋白）将在 TTNtv 的动物模型中进行研究。 突变的影响将在下文中进行研究。 基线条件、压力时以及与其他基因突变结合发生时。 重要的是，我们还将测试突变的肌联蛋白外显子的切除是否可以改善基于肌联蛋白的 DCM。 总结，利用我超过 20 年的创新 titin 研究记录，并利用我们的团队 经验丰富的科学家和才华横溢的受训者，该提案设定了雄心勃勃的目标，预计将进一步推动 加速了解肌动蛋白的生物学特性、其在心脏病中的作用以及肌动蛋白作为药物的潜力 治疗目标。