Length-dependent activation in human myocardium

人类心肌的长度依赖性激活

• 批准号: 10259881
• 负责人: Kenneth S Campbell
• 金额: $ 69.46万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10259881
• 关键词: American; Biochemical; Biological Assay; Biophysics; Calcium; Cardiac; Cardiomyopathies; Cardiovascular system; Computer Models; Data; Data Set; Dependence; Development; Disease; Electrophoresis; Genetic; Genomics; Head; Heart Transplantation; Heart failure; Histologic; Histology; Human; Impairment; Infarction; Kentucky; Length; Levosimendan; Mus; Muscle Cells; Muscle Contraction; Mutation; Myocardial; Myocardial Ischemia; Myocardium; Myosin ATPase; Organ Donor; Organ Transplantation; Patients; Penetrance; Peptides; Pharmacologic Substance; Phenotype; Physicians; Physiologic pulse; Pilot Projects; Preparation; Property; Regulation; Research; Research Personnel; Resources; Sampling; Sarcomeres; Scientist; Specimen; Stretching; Structure; Sturnus vulgaris; Techniques; Testing; Thick Filament; Transplant Recipients; Transplantation; Universities; base; biobank; biophysical techniques; design; experimental study; gel electrophoresis; genomic data; human data; predictive modeling; preservation; skills

ABSTRACT This translational project uses human biospecimens procured from organ donors and patients undergoing cardiac transplant to advance understanding of a cellular-level mechanism that underpins the Frank-Starling relationship. Specifically, the project focuses on length-dependent activation, defined as the increased maximum force and Ca2+ sensitivity of contraction induced by myocardial stretch. The mechanisms that underlie length- dependent activation remain unclear, but may involve thick-filament regulation and transitions between the newly discovered OFF and ON states of myosin. Co-PI Campbell has spent a decade building a biobank that now contains >10,000 myocardial specimens from >360 patients. Pilot experiments performed by Co-PI Tanner with these samples show that length-dependent changes in Ca2+ sensitivity are eliminated in myocardium from patients who have non-ischemic heart failure, but preserved in myocardium from organ donors and patients who have ischemic heart failure. New computer modeling predicts that these functional effects reflect destabilization of the myosin OFF state in patients who have non-ischemic heart failure. This hypothesis is supported by additional experiments that used fluorescent polarization techniques to assess OFF/ON dynamics in the thick filaments of human myocardium. Further pilot studies tested the effects of peptides targeted to the thick filament. Peptides that stabilize the OFF state reduced the Ca2+ sensitivity of contraction at long sarcomere length while destabilizing peptides enhanced Ca2+ sensitivity at short length. The length-dependence of these effects was predicted by our computer modeling. The project builds on these data from human biospecimens and integrates the skills and resources of five cardiovascular researchers, a statistician, and a physician-scientist who specializes in advanced heart failure. The Aims explore the global hypothesis that length-dependent activation is reduced in patients who have non- ischemic heart failure because their cardiac thick filaments are biased towards the ON state. Aim 1: Test the hypothesis that length-dependent changes in Ca2+ sensitivity are reduced in myocardium from patients who have non-ischemic heart failure. Aim 2: Test the hypothesis that the OFF state of the thick filament is destabilized in myocardium from patients who have non-ischemic heart failure. Aim 3: Target OFF/ON transitions to manipulate the Ca2+ sensitivity of human myocardium.

抽象的 该转化项目使用从器官捐献者和接受移植手术的患者那里获取的人类生物样本 心脏移植以促进对支撑 Frank-Starling 的细胞水平机制的理解 关系。具体来说，该项目侧重于长度相关的激活，定义为增加的最大 心肌拉伸引起的收缩力和 Ca2+ 敏感性。长度背后的机制—— 依赖性激活仍不清楚，但可能涉及粗丝调节和新细胞之间的转换 发现了肌球蛋白的关闭和开启状态。 联合 PI Campbell 花了十年时间建立了一个生物库，目前包含超过 10,000 个心肌样本 >360 名患者。 Co-PI Tanner 对这些样本进行的初步实验表明，长度依赖性 非缺血性心力衰竭患者心肌中 Ca2+ 敏感性的变化被消除，但 保存在器官捐献者和缺血性心力衰竭患者的心肌中。新电脑 模型预测这些功能效应反映了患者肌球蛋白关闭状态的不稳定 患有非缺血性心力衰竭。这一假设得到了使用荧光的其他实验的支持 偏振技术评估人体心肌粗丝的关闭/开启动态。进一步试点 研究测试了针对粗丝的肽的效果。稳定关闭状态的肽减少 长肌节长度收缩的 Ca2+ 敏感性，同时不稳定肽增强 Ca2+ 敏感性 长度较短。我们的计算机模型预测了这些效应的长度依赖性。 该项目以人类生物样本的这些数据为基础，整合了五个人的技能和资源 心血管研究人员、统计学家和专门研究晚期心力衰竭的医师科学家。 目标探讨了一个整体假设，即非患有非抑郁症的患者的长度依赖性激活会减少。 缺血性心力衰竭，因为他们的心脏粗丝偏向于开启状态。 目标 1：检验以下假设：心肌中 Ca2+ 敏感性的长度依赖性变化从 患有非缺血性心力衰竭的患者。 目标 2：检验患者心肌中粗丝的关闭状态不稳定的假设 患有非缺血性心力衰竭的人。 目标 3：以 OFF/ON 转换为目标来控制人体心肌的 Ca2+ 敏感性。