Canonical Wnt Signaling in Pathogenesis and Rescue of ARVC Phenotype

ARVC 表型发病机制和拯救中的经典 Wnt 信号转导

• 批准号: 7753654
• 负责人: Ali J Marian
• 金额: $ 37.5万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-15 至 2012-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7753654
• 关键词: Address; Adenoviruses; Adipocytes; Apoptosis; Appearance; Arrhythmia; Arrhythmogenic Right Ventricular Dysplasia; Arts; Attenuated; BCL9 gene; Binding; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; Cardiac; Cardiac Death; Cardiac Myocytes; Cardiac Myosins; Cardiomyopathies; Catheters; Cells; Cessation of life; Characteristics; Chimera organism; Coculture Techniques; Core Protein; Desmosomes; Detection; Development; Diagnostic; Disease; Doxycycline; Echocardiography; Etiology; Evaluation Studies; Family; Family Dasypodidae; Fibroblasts; Fibrosis; Functional disorder; Gene Expression; Genetic; Heart; Heart Atrium; Heart failure; Hereditary Disease; Homing; Human; In Vitro; Incidence; Infiltration; Lead; Left Ventricular Dysfunction; Ligands; Lymphoid; Magnetic Resonance Imaging; Maps; Mediating; Methods; Modeling; Molecular; Mus; Muscle Cells; Mutation; Myocardial; Myocardium; Myofibroblast; Myopathy; Myosin Heavy Chains; Nuclear; Nuclear Protein; Nuclear Proteins; Nuclear Translocation; Pathogenesis; Patients; Performance; Phenotype; Physiological; Prevention; Principal Investigator; Protein Binding; Proteins; Published Comment; Recombinants; Reporter; Resistance; Right Ventricular Function; Signal Transduction; Small Interfering RNA; Smooth Muscle; Source; Staging; Stromal Cells; Sudden Death; Supporting Cell; T-Lymphocyte; Technology; Testing; Tetanus Helper Peptide; Toxic effect; Transducers; Transgenic Mice; Transplantation; Ventricular; Ventricular Arrhythmia; Ventricular Function; Wild Type Mouse; armadillo proteins; base; design; desmoglein 2; desmoplakin; disease-causing mutation; experience; in vivo; interest; lipid biosynthesis; member; mouse model; mutant; novel; novel marker; overexpression; paracrine; plakoglobin; plakophilin 2; precursor cell; premature; prevent; primitive cell; programs; protein complex; protein protein interaction; recombinase; research study; response; sudden cardiac death; transdifferentiation

DESCRIPTION (provided by applicant): The overall objective is to delineate the molecular pathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC) in order to prevent, attenuate and reverse its evolving phenotype. ARVC is an uncommon genetic disease caused by mutations in at least five desmosomal proteins. Patients with ARVC typically present with cardiac arrhythmias, sudden cardiac death (SCD) and in advances stages with global heart failure. SCD is the first manifestation of the disease in approximately 25% of the cases. The phenotypic hallmark of ARVC is fibro-adipocytic infiltration of the myocardium that occurs in conjunction with myocyte apoptosis. The molecular pathogenesis of ARVC and the cellular origin of fibro-adiposis are unknown. Elucidation of the genetic basis of ARVC, as a disease of mutant desmosomal proteins, has provided the opportunity to delineate the pathogenesis of its phenotype. Based on structural and functional similarities between plakoglobin (PG), a desmosomal protein and a member armadillo family, and 2-catenin, the signal transducer of the canonical Wnt signaling and also an armadillo protein, we posit competitive interactions between PG (aka 3-catenin) and 2-catenin suppresses the canonical Wnt signaling, leads to myocyte apoptosis and enhanced adipogenesis. To test the hypothesis, we generated cardiac-restricted desmoplakin (DP) deficient mice and siRNA-mediated DP-deficient atrial myocytes. We showed DP-deficiency led to nuclear translocation of PG, suppression of the canonical Wnt signaling, myocyte apoptosis, fibrosis and adipogenesis. We propose to identify the cellular origin of excess adipocytes in the heart, delineate the molecular basis of suppressed canonical Wnt signaling and prevent the phenotype by activating the canonical Wnt signaling. The aims are: 1. To identify the cellular origin of excess adipocytes in ARVC through in vivo genetic fate-mapping and co-culture studies; 2. To determine whether suppressed canonical Wnt signaling is a common mechanism for the pathogenesis of ARVC by expression of titratable levels of mutant desmosomal proteins in transgenic mice hearts; 3. To delineate the mechanism by which nuclear PG suppresses the canonical Wnt signaling by studying protein-protein interactions and the effects of PG on effective assembly of Wnt core proteins complex; 4. To rescue the ARVC phenotype in vivo and in vivo by activating the canonical Wnt signaling through conditional activation of degradation-resistant 2-catenin and pharmacological activation and hence, to fulfill the Koch's postulates of causality. Studies in genetically modified mice, transduced cardiac myocytes and myofibroblasts are designed to delineate the components of each aim. The results could elucidate the molecular pathogenesis of desmosomal ARVC and lead to identification of new molecular diagnostic markers and novel pharmacological targets for the treatment and prevention of ARVC in humans. Project Narrative we propose to study the molecular basis of human heart muscle disease ARVC and to prevent its development in genetically modified mouse models. ARVC is an important cause of sudden death in the young. Currently, there is no specific treatment or prevention for ARVC.

描述（由申请人提供）：总体目标是描述致心律失常性右心室心肌病（ARVC）的分子发病机制，以预防、减弱和逆转其不断演变的表型。 ARVC 是一种罕见的遗传性疾病，由至少五种桥粒蛋白突变引起。 ARVC 患者通常会出现心律失常、心源性猝死 (SCD) 以及晚期全身性心力衰竭。 SCD 是大约 25% 病例的首发表现。 ARVC 的表型特征是心肌纤维脂肪细胞浸润，与心肌细胞凋亡同时发生。 ARVC 的分子发病机制和纤维脂肪病的细胞起源尚不清楚。 ARVC 作为一种突变桥粒蛋白疾病，其遗传基础的阐明为描述其表型的发病机制提供了机会。基于板珠蛋白 (PG)（一种桥粒蛋白和犰狳家族成员）与 2-连环蛋白（经典 Wnt 信号传导的信号转导器，也是犰狳蛋白）之间的结构和功能相似性，我们假设 PG（又名 3- 连环蛋白）之间存在竞争性相互作用。连环蛋白）和 2-连环蛋白抑制经典 Wnt 信号传导，导致心肌细胞凋亡并增强脂肪生成。为了检验这一假设，我们生成了心脏限制性桥粒斑蛋白 (DP) 缺陷小鼠和 siRNA 介导的 DP 缺陷心房肌细胞。我们发现 DP 缺陷会导致 PG 核易位、经典 Wnt 信号传导抑制、心肌细胞凋亡、纤维化和脂肪生成。我们建议确定心脏中过量脂肪细胞的细胞起源，描绘受抑制的经典 Wnt 信号传导的分子基础，并通过激活经典 Wnt 信号传导来预防表型。目的是： 1. 通过体内遗传命运图谱和共培养研究，确定 ARVC 中过量脂肪细胞的细胞起源； 2. 通过转基因小鼠心脏中可滴定水平的突变桥粒蛋白的表达，确定抑制的经典Wnt信号传导是否是ARVC发病机制的常见机制； 3. 通过研究蛋白质-蛋白质相互作用以及PG对Wnt核心蛋白复合物有效组装的影响，阐明核PG抑制经典Wnt信号传导的机制； 4.通过抗降解2-连环蛋白的条件激活和药理学激活来激活经典Wnt信号传导，从而在体内挽救ARVC表型，从而满足科赫因果关系假设。对转基因小鼠、转导心肌细胞和肌成纤维细胞的研究旨在描绘每个目标的组成部分。这些结果可以阐明桥粒 ARVC 的分子发病机制，并确定用于治疗和预防人类 ARVC 的新分子诊断标志物和新药理学靶点。项目叙述我们建议研究人类心肌疾病 ARVC 的分子基础，并在转基因小鼠模型中预防其发展。 ARVC是年轻人猝死的重要原因。目前，ARVC 没有具体的治疗或预防方法。