Detyrosinated microtubules in cardiomyocyte mechanics

项目摘要 心力衰竭的一个常见且目前难以治愈的特征是心脏组织僵硬，这损害了 心脏的放松能力。微管细胞骨架有助于心肌细胞的内部僵硬， 在某些条件下，会阻碍心肌细胞的收缩和松弛能力。超过第一个 在R01的五年里，我们发现心肌细胞的僵硬受到翻译后的严格调控 微管变性，并且变性的微管在人类心脏中持续升高 衰竭，伴随心肌僵硬增加。我们还发现，减少脂肪含量会导致 微管足以降低心肌细胞的僵硬和改善收缩和松弛 来自不同形式心力衰竭患者的心肌组织。我们进一步鉴定了这种酶 负责心脏的退化，并表明靶向这种酶足以强健地 改善衰竭的人体心脏细胞的松弛状态。因此，去酪氨酸症形成了一种很有前途的新疗法 治疗心力衰竭的靶点。这项拟议的研究将检验这样一种假设，即基因或小 “酪氨酸化循环”的分子靶向可稳定改善不同疾病患者的收缩和舒缩功能 心力衰竭的小动物和大动物模型。三个目标下的研究将涉及以下几个组成部分 这个假说。在目标1中，我们将探索过表达酪氨酸的基因治疗方法 酶(TTL)足以改善遗传性心力衰竭小鼠的收缩功能，并 在保留射血分数的情况下改善心衰手术模型的舒张期功能。目标2实验 将专注于一种不同的治疗方式，由新型和高效的小分子抑制剂组成 去酪氨酸酶(VASH)。我们将评估这些新型抑制剂的药代动力学并进行试验。 它们在减少啮齿类动物和小鼠心脏功能方面的耐受性和有效性 人类细胞和组织。在目标3中，我们将把我们的探索转移到更大的动物研究，并测试 靶向去酪氨酸酶足以改善肥厚猫的心肌细胞和心肌功能 心肌病和心力衰竭，射血分数保留。我们的跨物种、多尺度和 多管齐下的方法将平衡我们的简约主义严谨和综合相关性的目标，最终 进一步促进临床翻译。总之，这项工作将确定靶向去酪氨酸化微管能否稳定 改善心力衰竭患者的心功能，并确定可能适合于 进入临床流水线。

Project Summary A common and currently intractable feature of heart failure is the stiffening of cardiac tissue that impairs the heart's ability to relax. The microtubule cytoskeleton contributes to the internal stiffness of heart muscle cells, and under certain conditions can impede the ability of cardiomyocytes to both contract and relax. Over the first five years of this R01, we found that cardiomyocyte stiffness is tightly regulated by post-translational detyrosination of microtubules, and that detyrosinated microtubules are consistently elevated in human heart failure, concomitant with increased myocardial stiffness. We also found that reducing detyrosinated microtubules is sufficient to lower stiffness and improve contraction and relaxation in cardiomyocytes and myocardial tissue from patients with diverse forms of heart failure. We further identified the enzyme responsible for detyrosination in the heart, and showed that targeting this enzyme is sufficient to robustly improve relaxation in failing human heart cells. As such, detyrosination forms a promising new therapeutic target for the treatment of heart failure. The proposed research will test the hypothesis that genetic or small molecule targeting of the “tyrosination cycle” can stably improve both systolic and diastolic function in different small and large animal models of heart failure. Studies under three aims will address several components of this hypothesis. In Aim 1, we will explore whether a gene therapy approach overexpressing the tyrosinating enzyme (TTL) is sufficient to improve systolic function in a genetic mouse model of heart failure, and to improve diastolic function in surgical model of heart failure with preserved ejection fraction. Aim 2 experiments will focus on a different therapeutic modality consisting of novel and highly potent small molecule inhibitors of the detyrosinating enzyme (VASH). We will evaluate the pharmacokinetics of these novel inhibitors and test their tolerability and efficacy for reducing detyrosination and improving cardiac function in both rodent and human cells and tissues. In Aim 3, we will move our exploration to larger animal studies and test whether targeting detyrosination is sufficient to improve myocyte and myocardial function in cats with hypertrophic cardiomyopathy and with heart failure with preserved ejection fraction. Our cross-species, multi-scale and multi-pronged approach will balance our goals of reductionist rigor and integrative relevance that ultimately furthers clinical translation. Together, this work will determine if targeting detyrosinated microtubules can stably improve cardiac function in heart failure, and identify therapeutic compounds that may be suitable for progression into a clinical pipeline.