Zebrafish models of muscular dystrophies

描述(申请人提供)：肌营养不良症是一组不同的原发遗传性疾病，以进行性骨骼肌无力和退化为特征。该项目的长期目标是使用两种不同遗传形式的脊椎动物模型来了解肌肉营养不良的分子基础，并为这些虚弱疾病的患者开发治疗方法。先天性强直性脊柱肌营养不良症(RSMD1)在出生时或婴儿早期表现，由SEPN1基因突变引起，而强直性肌营养不良症(MMD)通常出现在成年，最近被认为与BIN1基因的错误剪接有关。有趣的是，SEPN1和BIN1都编码对T管的生物发生和功能重要的蛋白质，T管是骨骼肌中负责三联体兴奋收缩耦合的结构。为了进一步阐明这些分子相关疾病的病理生理学，并大规模筛选小分子疗法，需要合适的脊椎动物模型。斑马鱼由于其体积小、透明度高、增殖能力强、基因组特征完整等特点，近年来已成为发育生物学中一种强大的遗传工具，并被建议作为RSMD1和MMD的可靠模型。该项目的具体目标是：1)创建和表征斑马鱼BIN1和Sepn1基因的靶向敲除；2)开发这些突变体，用于高通量药物筛选，以确定对RSMD1和MMD具有治疗潜力的先导化合物。这些研究的成功结束将增加对这些疾病的基本生物学、受影响的系统以及导致骨骼肌无力的机制的总体了解。此外，识别减缓或防止骨骼肌紊乱的小分子将为临床前测试可能用于治疗肌肉营养不良和其他相关神经肌肉疾病的新疗法奠定基础。 公共卫生相关性：神经肌肉疾病，如本提案的核心肌肉营养不良，往往会导致严重的骨骼肌无力、无法行走和进行日常活动、呼吸困难和过早死亡--通常是在婴儿期或幼儿时期。“斑马鱼肌肉营养不良模型”与公众健康密切相关，因为它将在一个高度同源的系统中模拟两种主要形式的人类肌营养不良症，目前还没有良好的脊椎动物模型可用，其病理生理机制尚未完全阐明。新型斑马鱼先天性强直性脊柱肌营养不良症(RSMD1)和强直性肌营养不良症(MMD)模型将被用来识别可能改善营养不良骨骼肌特征紊乱的小分子。该项目的结果将是为患有这些严重神经肌肉疾病的儿童和成人开发未来治疗方法的基础。

DESCRIPTION (provided by applicant): Muscular dystrophies are a diverse group of primary inherited disorders characterized by progressive weakness and degeneration of skeletal muscle. The long-term goals of this project are to understand the molecular basis of muscular dystrophies using vertebrate models of two genetically distinct forms, and to develop therapies for patients with these debilitating conditions. Congenital rigid spine muscular dystrophy (RSMD1) manifests at birth or in early infancy and is caused by mutations in the SEPN1 gene, whereas myotonic muscular dystrophy (MMD) commonly presents in adulthood and has recently been associated with mis-splicing of the BIN1 gene. Interestingly, SEPN1 and BIN1 both encode proteins important for the biogenesis and function of T-tubules, the structures in skeletal muscles responsible for excitation-contraction coupling at the triads. To further elucidate the pathophysiology of these molecularly related conditions, and to screen small molecule therapeutics on a large scale, appropriate vertebrate models are required. Zebrafish, due to their small size, transparency, high proliferative capacity, and well-characterized genome, have recently emerged as a powerful genetic tool in developmental biology and are proposed here as reliable models for RSMD1 and MMD. The specific aims of this project are 1) to create and characterize targeted knockouts of the bin1 and sepn1 genes in zebrafish, and 2) to develop these mutants for use in high throughput drug screens to identify lead compounds with therapeutic potential for RSMD1 and MMD. The successful conclusion of these studies will increase general understanding of the basic biology of these disorders, the affected systems, and the mechanisms that lead to skeletal muscle weakness. Furthermore, the identification of small molecules that slow or prevent derangements of skeletal muscle will set the stage for preclinical testing of new therapies that may be used to treat patients with muscular dystrophy and other related neuromuscular diseases. PUBLIC HEALTH RELEVANCE: Neuromuscular diseases, such as the muscular dystrophies central to this proposal, often lead to severe skeletal muscle weakness, the inability to walk and conduct daily activities, respiratory difficulties, and premature death-often in infancy or early childhood. "Zebrafish models of muscular dystrophies" is deeply relevant to public health because it will model two major forms of human muscular dystrophy in a highly homologous system, forms for which no good vertebrate models are currently available and whose pathophysiological mechanisms have not yet been fully elucidated. Novel zebrafish models of congenital rigid spine muscular dystrophy (RSMD1) and myotonic muscular dystrophy (MMD) will be used to identify small molecules that may ameliorate the characteristic derangements of dystrophic skeletal muscle. The results of this project will be fundamental towards developing future treatments for children and adults born with these crippling neuromuscular disorders.