Ciliary Hedgehog signaling during adult tissue repair and disease

项目摘要 脂肪纤维化，用脂肪和纤维化瘢痕组织替代健康肌肉组织，是肥胖的一个突出特征。 慢性肌肉疾病，如杜氏肌营养不良症（DMD）、肌肉减少症、年龄相关的 骨骼肌和力量，以及肥胖和糖尿病。该项目将确定和描述 肌内脂肪形成的细胞和分子机制，以及 肌内脂肪对肌肉健康的影响最近的证据表明纤毛刺猬信号是一种有效的蚂蚁- 在肌肉再生过程中和mdx小鼠（DMD的小鼠模型）中的脂肪形成信号。此外，Hedgehog 促进肌肉修复并防止mdx小鼠中肌纤维尺寸的下降。通过什么机制（s）Hedgehog 平衡脂肪形成和肌肉再生的作用是未知的。该提案将利用创新和强大的 小鼠模型，以确定Hedgehog信号传导在肌肉再生过程中的作用，目的如下：1） 识别和表征负责的Hedgehog配体; 2）确定哪些细胞类型对Hedgehog有反应 信号;和3）证明肌内脂肪是否直接影响肌肉健康。综合来看，这一建议 将提供深入了解肌内脂肪的起源和功能，并将有助于寻找新的治疗方法， 干预受脂肪纤维化影响的人类疾病。

Project Summary Fatty fibrosis, the replacement of healthy muscle tissue with fat and fibrotic scar tissue, is a prominent feature of chronic muscle diseases such as Duchenne muscular dystrophy (DMD), sarcopenia, the age-related loss of skeletal muscle and strength, in addition to obesity, and diabetes. This project will identify and characterize the cellular and molecular mechanisms by which intramuscular fat forms, and the functional consequences of intramuscular fat on muscle health. Recent evidence points to ciliary Hedgehog signaling as a potent ant- adipogenic signal during muscle regeneration and in mdx mice, a mouse model of DMD. In addition, Hedgehog promotes muscle repair and prevents the decline in myofiber size in mdx mice. By what mechanism(s) Hedgehog acts to balance fat formation and muscle regeneration is unknown. This proposal will use innovative and powerful mouse models to identify the role of Hedgehog signaling during muscle regeneration in the following aims: 1) Identify and characterize the responsible Hedgehog ligand; 2) determine which cell types respond to Hedgehog signaling; and 3) demonstrate if intramuscular fat directly affects muscle health. Taken together, this proposal will provide insights into the origin and function of intramuscular fat and will aid in the search for novel therapeutic interventions into human diseases affected by fatty fibrosis.