Dystrophin Function in Aging Heart

描述（由申请人提供）：这项工作的长期目标是实施基于基因的治疗方法，以对抗衰老心脏中的进行性收缩功能障碍。心力衰竭是老年人住院、发病和死亡的主要原因。心脏肌营养不良蛋白是一个关键的和潜在的统一组成部分进行性心脏功能障碍的老化。肌营养不良蛋白是收缩肌节和细胞膜之间的重要联系。肌营养不良蛋白缺乏与心肌缺血和心力衰竭有关，并导致杜氏肌营养不良症（DMD），一种进行性横纹肌退化的致命疾病。DMD在这里被用作随着年龄的增长而逐渐衰退的心脏功能障碍的模型。新的数据显示，抗肌萎缩蛋白在老化的啮齿动物心脏中减少。该提议的总体假设是肌营养不良蛋白缺乏是心肌对疾病损伤易感性的原因，并且是衰老心肌对损伤易感性增加的核心组成部分。第二个假设：将心脏肌营养不良蛋白质增加到基线水平以上将在体内对老年动物的心肌提供长期保护。具体目标是：目标1。确定血管内rAAV介导的微小肌营养不良蛋白基因递送对年轻和老年野生型和肌营养不良蛋白缺陷小鼠体内心脏性能的年龄依赖性影响。假设：全身性微小肌养蛋白基因转移将防止年龄依赖性心室重构，并在体内心脏应激试验期间提供长期（年）保护;微小肌养蛋白将逆转年龄依赖性心室重构，但不纠正最大压力不足;微小肌养蛋白将防止野生型小鼠舒张性能的年龄依赖性下降。目标2.优化微肌营养不良蛋白和铰链修饰的微肌营养不良蛋白基因盒，用于校正野生型和肌营养不良蛋白缺陷动物体内衰老介导的心脏血流动力学缺陷。假设：具有优化的铰链和血影蛋白样重复结构域的截短的肌营养不良蛋白将在肌营养不良蛋白缺陷小鼠体内赋予相对于第一代微肌营养不良蛋白增加的心脏性能。目标3。在野生型小鼠心脏中完成年龄依赖性全长肌养蛋白基因切除/沉默，并直接评估体内病理学和血液动力学结果。假设：暂时性肌营养不良蛋白基因缺失将导致心脏损伤和心脏功能缺陷，与年轻动物相比，老年动物的影响更大。 公共卫生相关性：心力衰竭是一种临床综合征，定义为总体心脏泵功能降低，是老年人住院的主要原因。由于目前的医疗保健和美国人口结构的变化，老年人的渐进性心脏功能障碍是一个日益不可避免的公共卫生现实。因此，该提案关注衰老衰竭心脏的健康相关性对于国家老龄化研究所和NIH的使命是实质性的和非常重要的。

DESCRIPTION (provided by applicant): The long-term goal of this work is to implement gene-based therapeutics to combat progressive contractile dysfunction in the aging heart. Heart failure is the primary cause of hospitalization, morbidity and mortality in the elderly. Cardiac dystrophin is a key and potentially unifying component of progressive heart dysfunction in aging. Dystrophin is a vital link between the contractile sarcomere and the cell membrane. Dystrophin deficiency is associated with myocardial ischemia and heart failure and causes Duchenne Muscular Dystrophy (DMD), a fatal disease of progressive striated muscle deterioration. DMD is used here as a model of cardiac dysfunction that progressively worsens in aging. New data shows dystrophin protein is decreased in the aging rodent heart. The overarching hypothesis of this proposal is that dystrophin deficiency is causal for cardiac muscle susceptibility to damage in disease and is a central component to increased susceptibility to damage in the aging myocardium. Second hypothesis: increasing cardiac dystrophin protein above baseline levels will confer long-term protection to the myocardium in aged animals in vivo. The Specific Aims are: Aim 1. To determine the aging-dependent effects of intravascular rAAV-mediated micro-dystrophin gene delivery on cardiac performance in young and old wild-type and dystrophin-deficient mice in vivo. Hypotheses: systemic micro-dystrophin gene transfer will prevent aging-dependent ventricular remodeling and confer long-term (year) protection during in vivo cardiac stress testing in vivo; micro- dystrophin will reverse age-dependent ventricular remodeling but not redress maximum pressure deficits; micro-dystrophin will prevent age-dependent decline in diastolic performance in wild-type mice. Aim 2. To optimize mini-dystrophin and hinge modified micro-dystrophin gene cassettes for correction of aging-mediate cardiac hemodynamic deficits in wild-type and dystrophin deficient animals in vivo. Hypothesis: truncated dystrophin with optimized hinge and spectrin-like repeat domains will confer increased cardiac performance relative to first generation micro-dystrophin in dystrophin-deficient mice in vivo. Aim 3. To accomplish age-dependent, full-length dystrophin gene excision/silencing in the hearts of wild- type mice and to directly assess the resulting pathological and hemodynamic outcomes in vivo. Hypothesis: temporal dystrophin gene deletion will cause cardiac injury and heart performance deficits with effects greater in old compared to young animals. PUBLIC HEALTH RELEVANCE: Heart failure, a clinical syndrome defined as reduction in overall heart pump performance, is the leading cause of hospitalization of the elderly. Progressive heart dysfunction in the elderly is an increasingly inescapable public health reality owing to current medical care and shifting US demographics. Therefore the health relevance of the proposal's focus on the aging failing heart is substantial and highly significant to the mission of the National Institute of Aging and NIH.