Connexin 43: a new player in Duchenne muscular dystrophy associated cardiomyopathy

Connexin 43：杜氏肌营养不良症相关心肌病的新参与者

• 批准号: 9494823
• 负责人: Jorge Enrique Contreras
• 金额: $ 39.48万
• 依托单位: RBHS-NEW JERSEY MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9494823
• 关键词: 18 year old; Address; Affect; Arrhythmia; Biochemical; Blinded; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cell Membrane Permeability; Cell membrane; Cells; Cessation of life; Communities; Connexin 43; Connexins; Cysteine; Data; Development; Dilated Cardiomyopathy; Duchenne cardiomyopathy; Duchenne muscular dystrophy; Dystrophin; Environment; Exhibits; Fibrosis; Functional disorder; Genetic; Glutamic Acid; Goals; Heart; Heart Diseases; Heart failure; Hela Cells; Histologic; Homeostasis; Impairment; Intercalated disc; Ions; Knock-in Mouse; Knockout Mice; Lead; Longevity; Mechanics; Mediator of activation protein; Medical; Methionine; Molecular; Molecular Target; Mus; Mutant Strains Mice; Mutation; Myocardium; Myopathy; Oxidation-Reduction; Oxidative Stress; Oxides; Paper; Pathologic; Pathology; Pathway interactions; Patients; Permeability; Pharmacologic Substance; Pharmacology; Phosphorylation; Predisposition; Prevention; Production; Proteins; Publishing; Reactive Oxygen Species; Research Proposals; Role; Serine; Signal Transduction; Skeletal Muscle; Stem cells; Stimulus; Stress; Testing; Therapeutic; Triplet Multiple Birth; Utrophin; Xenopus oocyte; cardiogenesis; cellular pathology; driving force; dystrophic cardiomyopathy; gap junction channel; heart function; improved; mdx mouse; mitochondrial metabolism; mutant; novel therapeutic intervention; novel therapeutics; oxidation; premature; prevent; small molecule; therapeutic target

SUMMARY Duchenne muscular dystrophy (DMD) is a progressive muscle disease with severe cardiac complications. Dilated cardiomyopathy is a serious condition apparent in 100% of DMD patients over 18 years of age. Over 40% (and increasing) of DMD patients are dying from heart failure. However, studies of dystrophic cardiomyopathy remain quite limited. The culprit – loss of dystrophin – is a subsarcolemmal protein that protects skeletal and cardiac muscle from mechanically induced damage and regulates a number of downstream cellular pathways. While recent strategies to restore dystrophin levels keep hopes up, the medical and scientific communities are also seeking alternative therapeutic targets downstream of dystrophin. We found key evidence suggesting a detrimental role for connexin-43 (Cx43) in DMD-cardiomyopathy. We showed that Cx43 is upregulated and remodeled in the heart of mdxand mdx:utrophin knockout mice, as well as in the heart of DMD patients. We also showed that selective pharmacological inhibition of Cx43 function or genetic reduction of Cx43 leads to a rescue of arrhythmias and prevention of premature death in stressed mdx mice, as well as protection from the development of long-term cardiomyopathy. We determined that Cx43 in mdx is hypophosphorylated in a specific triplet of serine residues (S325/328/330). Reduction of phosphorylation in this same triplet promotes Cx43 remodeling in a variety of cardiac pathologies, leading to undesired opening of Cx43 hemichannels, arrhythmic susceptibility and irreversible long-term consequences. We believe that cardiac remodeling of Cx43 in DMD contributes to cellular Ca2+ overload and oxidative stress, leading to arrhythmias, fibrosis and consequently, to the development of heart failure. We believe that the phospho-triplet S325/328/330 is the driving force for Cx43 remodeling. In this proposal we will first determine whether expression of a mutant form of Cx43 protects mdx mice from developing cardiac pathology on functional and histological (Aim 1) as well as on cellular (Aim 2) levels. To address this question, Cx43 knockin mice will be crossed with mdx mice, to incorporate the Cx43 phospho-mutation harboring glutamic acids instead of serines in the phospho-triplet thus mimicking permanent phosphorylation. In Aim 3 we will investigate molecular mechanisms responsible for enhanced opening of Cx43 hemichannels in dystrophic hearts. In particular, we will examine if excessive ROS opens the hemichannels. Rigorous blinded functional, histological and biochemical analysis will be conducted.

概括 Duchenne肌肉营养不良（DMD）是一种进行性心脏并发症的进行性肌肉疾病。 在18岁以上的100％的DMD患者中，扩张的心肌病很明显。超过 DMD患者的40％（和增加）因心力衰竭而死。但是，营养不良的研究 心肌病仍然非常有限。罪魁祸首 - 肌营养不良蛋白的丧失 - 是一种亚羧基蛋白 保护骨骼和心肌免受机械诱导的损害，并调节多个 下游细胞途径。虽然最近恢复肌营养不良素水平的策略保持了希望，但医疗 科学界还寻求肌营养不良蛋白下游的替代治疗靶标。我们 找到了关键证据，表明连接蛋白43（CX43）在DMD型肌病中的作用有害。我们展示了 该CX43在MDXand MDX的心脏中进行了更新和重塑：Utrophin敲除小鼠以及在 DMD患者的心脏。我们还表明，CX43功能或通用的选择性药物抑制 减少CX43导致心律不齐和预防压力MDX小鼠的过早死亡， 以及免受长期心肌病的发展。我们确定MDX中的CX43是 在特定的连续保留三重态中降低了phypophy（S325/328/330）。降低磷酸化 相同的三重序列促进了各种心脏病理中的CX43重塑，导致不希望的开放 CX43半通道，心律失常的敏感性和不可逆转的长期后果。我们相信 DMD中CX43的心脏重塑有助于细胞CA2+过载和氧化应激，导致 心律不齐，纤维化，因此是心力衰竭发展的。我们相信磷酸三重 S325/328/330是CX43重塑的驱动力。在此提案中，我们将首先确定是否 CX43突变形式的表达可保护MDX小鼠免受功能和功能性心脏病理的影响 组织学（AIM 1）以及细胞（AIM 2）水平。为了解决这个问题，CX43敲蛋白小鼠将是 与MDX小鼠交叉，结合了含有谷氨酸而不是串行的CX43磷酸化的磷酸化。 在AIM 3中，我们将研究分子 负责增强营养不良心脏中CX43半通道开放的机制。特别是我们 将检查过多的ROS是否打开半通道。严格的盲目功能，组织学和 将进行生化分析。