Length-dependent activation in human myocardium

摘要 这一翻译项目使用从器官捐赠者和患者那里获得的人类生物标本。 心脏移植以促进对支撑Frank-Starling的细胞水平机制的理解 两性关系。具体地说，该项目侧重于依赖长度的激活，定义为增加的最大值 心肌牵张引起的收缩作用力和钙敏感性。作为长度基础的机制- 依赖性激活尚不清楚，但可能涉及粗丝调节和新的 断断续续地发现了肌球蛋白。 Co-Pi Campbell花了十年时间建立了一个生物库，现在包含10,000个心肌样本，这些样本来自 &gt；360名患者。Co-PI Tanner对这些样品进行的初步实验表明，长度依赖于 非缺血性心力衰竭患者心肌中钙离子敏感性的变化被消除，但 保存在器官捐赠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以下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素的额外实验的支持。 极化技术评估人心肌粗丝的关断动力学。进一步试行 研究测试了针对粗丝的多肽的效果。稳定关闭状态的多肽减少 长肌节收缩的钙敏感性，而不稳定多肽增强了钙敏感性 用很短的篇幅。通过我们的计算机模拟预测了这些效应的长度依赖关系。 该项目建立在这些来自人类生物标本的数据基础上，并整合了五项技能和资源 心血管研究人员、统计学家和专门研究晚期心力衰竭的内科科学家。 其目的是探索全球假说，即在患有非霍奇金淋巴瘤的患者中，依赖于长度的激活减少 缺血性心力衰竭是因为他们的心脏粗丝偏向于开状态。 目的1：验证一种假设，即心肌钙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。 目的2：验证患者心肌粗丝关闭状态不稳定的假说 患有非缺血性心力衰竭的患者。 目的3：靶向关闭/开启转换以调控人心肌细胞的钙敏感性。

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.