Myonuclear homeostasis in craniofacial muscles

项目总结/摘要 吞咽困难是一种吞咽困难，在20%的老年人和几种形式的肌肉萎缩症中观察到。 营养不良患者，并导致营养不良和潜在的危及生命的影响，如窒息或 通过吸入食物引起的肺炎;然而，没有治愈或治疗方法存在。舌咽 肌肉对于正确的吞咽和防止食物/水吸入肺部是必不可少的， 舌和咽肌功能随年龄和 诸如眼咽肌营养不良症（OPMD）的疾病是未知的。OPMD是一种迟发性， 常染色体显性肌肉疾病，眼睑、舌和咽肌功能明显障碍; 然而，对这种疾病的肌肉特异性的潜在机制知之甚少。肌肉干 颅面肌的卫星细胞（SC）具有独特的肌原性，如慢性高水平的 在没有损伤的情况下与肌纤维的增殖和融合。尽管高水平和持续的 慢性卫星细胞融合使肌细胞核加入肌纤维中， 肌纤维得以维持，这意味着发生了高水平的肌核更新。这种不寻常的神秘感 内稳态可能使颅面肌肉更容易受到特定疾病和年龄的影响。 我们提出了3条实验路线，以解决肌萎缩症的细胞机制 颅面肌的内稳态这些研究将有助于确定参与特异性的机制， 在OPMD中受影响的肌肉，并为吞咽困难提供潜在的靶向治疗策略。 目的1：比较成纤维脂肪祖细胞（FAPs）对卫星细胞与肌纤维融合的影响 颅面和四肢肌肉之间。我们将确定肌肉特异性FAP差异是否影响 卫星细胞（SC）增殖或分化在不同年龄的小鼠使用体外和体内试验。 目的2：量化颅面肌中的肌钙蛋白周转，并检查自噬作为一种机制， 心肌细胞周转率我们将应用BrdU标记方法来测量颅面肌的转换， 肌肉，并与随着年龄增长的肌肉增加水平进行比较。自噬，在细胞内 动态平衡，将作为颅面肌中肌纤维转换的潜在机制进行检查。 目的3：探讨眼咽肌肌外肌功能受损的机制 营养不良（OPMD）和肌萎缩症的营业额是否也改变。我们将测试内在的 SC的生肌潜能或FAP对SC的外在作用影响了 颅面肌的损伤此外，我们还将测量颅面肌的肌张力周转 在OPMD小鼠中，并确定自噬信号的增强是否影响肌钙蛋白转换， OPMD中的病理学

Project Summary/Abstract Dysphagia is a difficulty in swallowing which is observed in 20% of the elderly and several forms of muscular dystrophy patients and causes malnutrition and potential life threatening effects such as choking or pneumonia by aspiration of food; however, no cure or therapeutic treatment exists. Tongue and pharyngeal muscles are essential for proper swallowing and prevention of food/water aspiration into the lungs yet the cellular mechanisms that underlie changes in tongue and pharyngeal muscle function with age and with diseases, such as oculopharyngeal muscular dystrophy (OPMD), are unknown. OPMD is a late-onset, autosomal dominant muscle disease with prominent dysfunction of the eyelid, tongue and pharyngeal muscles; however, little is known about the mechanisms underlying the muscle-specificity of this disease. Muscle stem cells (satellite cells, SC) of craniofacial muscles have unique myogenic properties such as chronic high levels of proliferation and fusion with the myofiber in the absence of injury. Despite high and constant levels of myonuclear addition into myofibers by chronic satellite cell fusion, a constant number of myonuclei per myofiber is maintained, implying a high level of myonuclei turnover is occurring. This unusual myonuclear homeostasis may make craniofacial muscles more vulnerable to specific diseases and age. We propose 3 lines of experimentation addressing the cellular mechanisms underlying myonuclear homeostasis of craniofacial muscles. These studies will help identify mechanisms involved in the specificity of affected muscles in OPMD and provide potential targeted therapeutic strategies for dysphagia. Aim 1: To compare the effect of fibroadipogenic progenitor cells (FAPs) on satellite cell fusion with myofibers between craniofacial and limb muscles. We will determine whether muscle-specific FAP differences influence satellite cell (SC) proliferation or differentiation at different ages in mice using assays in vitro and in vivo. Aim 2: To quantify myonuclear turnover in craniofacial muscles and examine autophagy as a mechanism for myonuclear turnover. We will apply BrdU labeling methods to measure myonuclear turnover of craniofacial muscles and compare to the level of myonuclear addition with aging. Autophagy, which has a role in cellular homeostasis, will be examined as a potential mechanism for myonuclear turnover in craniofacial muscles. Aim 3: To determine the mechanism of impaired myonuclear addition in oculopharyngeal muscular dystrophy (OPMD) and whether myonuclear turnover is also altered. We will test whether the intrinsic myogenic potential of SC or the extrinsic effect of FAPs on the SCs influences impaired nuclear addition in craniofacial muscles in OPMD. In addition, we will measure the myonuclear turnover of craniofacial muscles in OPMD mice and determine whether augmentation of autophagy signaling affects myonuclear turnover and pathology in OPMD.