Myonuclear homeostasis in craniofacial muscles

项目摘要/摘要 吞咽困难是一种吞咽困难，在20%的老年人和几种肌肉形式的患者中都会出现这种症状。 营养不良患者，并导致营养不良和潜在的威胁生命的影响，如窒息或 由食物吸入引起的肺炎；然而，目前还没有治愈或治疗的方法。舌咽 肌肉是正确吞咽和防止食物/水吸入肺部所必需的，但 舌头和咽部肌肉功能随年龄和年龄变化的细胞机制 眼咽肌营养不良症(OPMD)等疾病是未知的。OPMD是一种晚发、 常染色体显性遗传性肌肉病，伴有明显的眼睑、舌肌和咽肌功能障碍； 然而，人们对这种疾病肌肉特异性的机制知之甚少。肌茎 颅面肌细胞(卫星细胞，SC)具有独特的生肌特性，如慢性高水平 在没有损伤的情况下，与肌纤维的增殖和融合。尽管高水平和恒定的 通过慢性卫星细胞融合将肌核添加到肌纤维中，每个 肌纤维保持不变，意味着肌核发生了高水平的周转。这种不同寻常的肌核 动态平衡可能会使头面部肌肉更容易受到特定疾病和年龄的影响。 我们提出了三条实验路线来解决肌核的细胞机制。 头面部肌肉动态平衡。这些研究将有助于确定涉及到的特异性的机制 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：比较成纤维脂肪前体细胞(FAPs)对卫星细胞与肌纤维融合的影响 在头面部和四肢肌肉之间。我们将确定肌肉特异性FAP的差异是否会影响 用体外和体内实验检测不同年龄小鼠卫星细胞的增殖或分化。 目的2：量化头面部肌肉的肌核周转，并检查自噬作为一种机制 肌核周转率。我们将应用BrdU标记方法测量颅面部的肌核转换率 并比较随着年龄的增长肌核增加的水平。自噬，它在细胞中起着作用 动态平衡，将被视为头面部肌肉肌核转换的一个潜在机制。 目的3：探讨眼咽肌肌核加成受损的机制 营养不良(OPMD)以及肌核周转是否也发生改变。我们将测试内部是否存在 SC的肌生电位或FAP对SCs的外在作用影响受损的核加成 OPMD患者的头面部肌肉。此外，我们还将测量头面部肌肉的肌核周转率。 并确定自噬信号的增强是否影响肌核周转和 OPMD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.