CMYA5 regulation of cardiac dyad structure and function

CMYA5对心脏二元体结构和功能的调节

• 批准号: 10607816
• 负责人: William Tswenching Pu
• 金额: $ 61.46万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-15 至 2026-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10607816
• 关键词: Architecture; Arrhythmia; Binding; Cardiac; Cardiac Myocytes; Cell membrane; Cells; Coupled; Coupling; Data; Development; Diffusion; Dilated Cardiomyopathy; Disease; Endoplasmic Reticulum; Functional disorder; Heart; Heart Diseases; Heart failure; Homeostasis; Human; Inherited; Link; Maintenance; Mediating; Membrane; Molecular; Mus; Mutation; Myocardial dysfunction; Myocardium; Nanostructures; Pathogenesis; Pattern; Positioning Attribute; Proteins; Proteomics; Regulation; Relaxation; Risk; Ryanodine Receptor Calcium Release Channel; Sarcomeres; Sarcoplasmic Reticulum; Signal Transduction; Structure; Testing; Tubular formation; Work; cardiac muscle disease; extracellular; in vivo; induced pluripotent stem cell; insight; muscular structure; nanoscale; novel; overexpression; preservation; pressure; response; transmission process

In cardiomyocytes, dyads are nanoscale structures formed by the juxtaposition of T-tubules, a network of tubular invaginations of the plasma membrane, and regions of the endoplasmic reticulum specialized for Ca2+ release, known as the junctional sarcoplasmic reticulum (jSR). Dyads are positioned adjacent to Z-lines, such that sarcomere Z-lines, jSR, and T-tubules co-localize in a regular, transverse, linear pattern. Dyads mediate excitation-contraction (E-C) coupling, which converts rapidly propagating plasma membrane electrical signals into coordinated Ca2+ transients throughout the cardiomyocyte, resulting in synchronized, forceful sarcomere contraction. A hallmark of failing cardiomyocytes is disorganization of dyads, which disrupts Ca2+ handling and results in decreased contraction and increased risk of arrhythmia. The molecular mechanisms underlying dyad architecture and positioning have remained a mystery, despite their importance to heart homeostasis and disease. Our preliminary data establish a hierarchy for dyad formation in which a little studied protein, CMYA5, tethers jSR to sarcomere Z-lines, and T-tubules associate with jSR to form dyads. We further show that CMYA5 is required for normal dyad architecture, fidelity of E-C coupling, and regulation of RYR2 Ca2+ release activity. Mice lacking CMYA5 had dilated cardiomyopathy and were sensitized to develop severe cardiac dysfunction in response to pressure overload. In failing human hearts, loss of T-tubule and jSR organization were coupled to perturbed CMYA5 localization. Our studies establish CMYA5 as a novel entry point to study mechanisms responsible for dyad architecture and positioning adjacent to Z-lines, and implicate abnormalities of CMYA5-dependent mechanisms in the disorganization of dyads in human heart failure3–5, which contributes to heart failure pathogenesis. Building on these novel observations, we will pursue the following Specific Aims to gain further insights into the function of CMYA5 in regulating CM Ca2+ release and E-C coupling: (1) Investigate CMYA5 regulation of RYR2 activity. We will test the hypothesis that CMYA5 interaction with RYR2 regulates RYR2 Ca2+ release by controlling RYR2 channel activity and RYR2 channel clustering. (2) Identify mechanisms by which CMYA5 tethers RYR2/jSR to Z-lines. We will test the hypothesis that CMYA5 anchors RYR2/jSR at Z-lines through interaction with currently unknown bridging proteins. (3) Evaluate contribution of CMYA5 mislocalization to dyad disruption in human and experimental heart disease. This proposal will reveal novel mechanisms responsible for the subcellular organization of dyads, hallmark nanostructures of CMs that are essential for normal E-C coupling. Elucidation of these mechanisms will provide insights into the mechanisms that perturb dyads in human heart failure, exacerbating contractile dysfunction and arrhythmia, and may lead to avenues to protect E-C coupling in inherited and acquired forms of heart disease.

在心肌细胞中，二元组是纳米级结构，由T管的并置，T-Tubes的并置，质膜的结核病网络，以及专门用于Ca2+释放的内质网的区域，被称为Ca2+释放，称为联合性肌乳清骨质网（JSR）。二元组位于Z线相邻的位置，使得肌节z-线，JSR和T管以常规的横向线性模式共定位。 Dyads培养基兴奋能力（E-C）耦合，在整个心肌细胞中迅速将质膜电信号转换为协调的Ca2+瞬变，从而导致同步，有力的肉瘤收缩。心肌细胞失败的标志是二元组混乱，这破坏了CA2+处理并导致收缩的改善和心律不齐的风险增加。二元组结构和定位的分子机制仍然是神秘的，它对心脏体内稳态和疾病的重要性。我们的初步数据建立了二元组形成的层次结构，其中少量研究蛋白，CMYA5，TETHERS JSR到肌节z-lines以及与JSR相关的T管以形成二元组。我们进一步表明，正常的二元组结构，E-C耦合的保真度以及RYR2 CA2+释放活性的调节是必需的。缺乏CMYA5的小鼠心肌病已经扩张，并且对响应压力超负荷的严重心脏功能障碍敏感。在失败的人心脏中，T管和JSR组织的损失与CMYA5的扰动耦合。我们的研究将CMYA5建立为研究二元结构和与Z线相邻定位的研究机制的新入口点，并暗示了CMYA5依赖机制的异常在人类心脏故障中二元组的混乱3-5，这有助于心脏失败的致病性。在这些新颖的观察结果的基础上，我们将采取以下具体目标，以进一步了解CMYA5在调节CM Ca2+释放和E-C耦合中的功能：（1）研究RYR2活性的CMYA5调节。我们将通过控制RYR2通道活性和RYR2通道聚类来测试CMYA5与RYR2相互作用调节RYR2 Ca2+释放的假设。 （2）确定CMYA5将RYR2/JSR扭转到Z线的机制。我们将通过与目前未知的桥接蛋白相互作用来测试CMYA5将RYR2/JSR锚定在Z线上的假设。 （3）评估CMYA5错误定位对人和实验性心脏病中二元干扰的贡献。该建议将揭示负责二元组亚细胞组织的新型机制，即CMS的标志性纳米结构，这对于正常的E-C耦合至关重要。阐明这些机制将提供有关人类心力衰竭中二元组的机制，加剧收缩功能障碍和心律不齐的机制，并可能导致以遗传和获得形式的心脏病形式保护E-C耦合的途径。