In Vivo Functions of Myotubularins and Therapy for Myotubular Myopathy

该项目的长期目标是了解肌管/肌纤维的分子基础。 中枢性肌病及其肌肉功能缺陷，并利用这些信息来开发 治疗这些神经肌肉疾病的患者。X连锁肌管性肌病（XLMTM）是 由肌管蛋白（MTM 1）突变引起，MTM 1是脂质磷酸酶新家族的原型成员 包括有催化活性和无活性的（接头）家族成员（肌微管蛋白相关蛋白 或“MTMR”）。有强有力的证据表明，尽管具有相似的生化活性， myotubularin家族成员在生理上起着不同的作用。例如，两个相关基因的突变 基因（MTMR 2和MTMR 13）都导致遗传性神经病，腓骨肌萎缩症（CMT） 疾病本计画的主要目标为：1）开发脊椎动物模型系统 （斑马鱼）以确定MTM 1及其几个家族成员的生理功能，2） 利用候选基因突变研究来鉴定相关形式的中枢性肌病的基因，以及3） 利用X连锁肌管性肌病的小鼠Mtm 1敲除模型开发AAV 8介导的基因 治疗这种致命疾病的方法。从斑马鱼研究中得到的信息将使我们 以确定家庭成员之间潜在的功能冗余程度，并确定 负责任何组织或分子特异性的特定蛋白质结构域。识别这些 功能互补的MTMR基因可以鉴定合适的候选基因，以帮助发现 一种严重的常染色体隐性形式的中枢性肌病的基因。关于从 瞬时转录敲低鱼类MTM 1，也将是重要的设计有效的 使用小鼠模型进行治疗。基因替代疗法实验将解决疗效问题 以及这种治疗XLMTM方法的适当治疗窗口，并将为 未来可能的人类临床试验和动物研究，可能尝试通过上调 通过斑马鱼实验鉴定的功能等同的MTMR。总的来说，这个项目的成功 将导致1）新的见解的相似性和差异之间的功能肌管蛋白和一些 它的相关家庭成员，2）增加了对分子病理生理学的理解， 人类患者的肌管性肌病，以及3）关于基因治疗方法是否 可能对治疗这种毁灭性的儿童疾病有效。

The long-term goals of this project are to understand the molecular basis for the myotubular/ centronuclear myopathies and their defects in muscle function, and to use this information to develop therapies for patients with these neuromuscular diseases. X-linked myotubular myopathy (XLMTM) is caused by mutations of myotubularin (MTM1), the prototypic member of a novel family of lipid phosphatases that includes both catalytically active, and inactive (adaptor) family members (myotubularin-related proteins or "MTMRs"). There is strong evidence that, despite having similar biochemical activities, different myotubularin family members play physiologically distinct roles. For example, mutations of two related genes (MTMR2 and MTMR13) both cause forms of the inherited neuropathy, Charcot-Marie-Tooth (CMT) disease. The primary goals of this Project are 1) to develop and exploit a vertebrate model system (zebrafish) to determine the physiological function(s), of MTM1 and several of it's family members, 2) to utilize candidate gene mutation studies to identify genes for related forms of centronuclear myopathy and 3) to utilize a mouse Mtm1 knockout model of X-linked myotubular myopathy to develop AAV8-mediated gene therapy approaches to treat this fatal disease. Information resulting from the zebrafish studies will allow us to determine the degree of potential functional redundancy between family members and to identify the specific protein domains responsible for any tissue or molecular specificity. Identification of these functionally complementary MTMR genes may identify appropriate candidate genes to aid in finding the gene(s) for a severe autosomal recessive form of centronuclear myopathy. Observations on recovery from transient transcriptional knockdowns of MTM1 in the fish, will also be important in design of effective therapies using the mouse model. Gene replacement therapy experiments will address questions of efficacy and the appropriate therapeutic window for this approach to treating XLMTM, and will set the stage for possible future human clinical trials and animal studies that may attempt treatment via up-regulation of functionally equivalent MTMRs identified through the zebrafish experiments. Overall, success in this project will lead to 1) new insights into the similarities and differences in function between myotubularin and some of it's related family members, 2) an increased understanding of the molecular pathophysiology underlying myotubular myopathy in human patients, and 3) the first indications as to whether a gene therapy approach is likely to be effective in treating this devastating childhood disease.