In vivo role of the fibroblast in muscular dystrophy

摘要 肌肉营养不良是一种遗传性疾病，主要影响横纹肌组织，导致 进行性肌肉无力，消瘦，在许多情况下，过早死亡。许多人都具有 导致肌营养不良症(MD)的人类突变是结构依附改变的结果 将潜在的收缩蛋白附着在基底板上的蛋白质，为骨骼提供刚性 肌细胞膜(肌膜)。肌营养不良蛋白糖蛋白中选择性附着蛋白的丢失 复合体(DGC)允许收缩引起的膜撕裂和钙内流，从而导致细胞 肌肉纤维变性和坏死。在这个坏死过程中，细胞因子、趋化因子和生长 因子作为炎症和修复过程的一部分被释放，尽管会诱导纤维化和瘢痕形成 是一种有害的副作用，会加重疾病。一种重要的细胞因子是转化生长因子-β (转化生长因子β)，为MD的纤维化反应和肌肉病理恶化提供主要调节。 虽然成纤维细胞直接受转化生长因子β的调节，但还没有人研究成纤维细胞在 骨骼肌直接在体内，作为一种介体或纤维化和肌营养不良。在这里，我们生成了一个独特的 选择性调节心肌和骨骼肌活动的小鼠遗传模型 体内成纤维细胞和营养不良小鼠的疾病模型。因此，在这里我们将检验这一新颖的假设 肌成纤维细胞在心脏和骨骼中介导纤维化和组织重塑中的选择性作用 肌肉对MD细胞丢失的反应，而滞留在肌肉纤维和心肌细胞的 生理性细胞外基质/胶原蛋白的产生和基底膜的产生分别由不同的组织构成 发展，并作为持续动态平衡的一部分。申请有两个全面的具体目标：1) 从遗传学角度分析肌成纤维细胞在小鼠骨骼肌和心脏中的作用 研究转化生长因子β、Smad2/3和p38α信号通路如何通过肌成纤维细胞在体内介导MD疾病。 该应用程序将尝试明确地解决激活的成纤维细胞(肌成纤维细胞)在 肌肉在MD疾病发生和发展过程中的作用。它还将试图阐明转化生长因子β的重要性。 在体内介导肌成纤维细胞形成和疾病活动的信号，作为典型和非典型的 规范的路径将从基因上进行解剖。

Abstract The muscular dystrophies are inherited disorders that largely affect striated muscle tissue resulting in progressive muscle weakness, wasting, and in many instances, premature death. Many characterized mutations in humans that cause muscular dystrophy (MD) result from alterations in structural attachment proteins that affix the underlying contractile proteins to the basal lamina, providing rigidity to the skeletal muscle cell membrane (sarcolemma). Loss of select attachment proteins in the dystrophin-glycoprotein complex (DGC) permits contraction-induced membrane tears and influx of calcium that causes cellular degeneration and necrosis of muscle fibers. During this necrotic process cytokines, chemokines and growth factors are released as part of the inflammatory and repair process, although induction of fibrosis and scarring are an unwanted side effect that worsens disease. One prominent cytokine is transforming growth factor-β (TGFβ) that serves a master regulator of the fibrotic response and worsening of muscle pathology in MD. While fibroblasts are directly regulated by TGFβ, no one has yet to examine the function of the fibroblast in skeletal muscle directly in vivo, as a mediator or fibrosis and muscular dystrophy. Here we generated a unique genetic model in the mouse that will selectively modulate the activity of the cardiac and skeletal muscle fibroblast in vivo and in dystrophic mouse models of disease. Thus, here we will test the novel hypothesis that myofibroblasts play a selective role in mediating fibrosis and tissue remodeling in heart and skeletal muscle in response to cellular dropout from MD, while resident myofibers and cardiomyocytes in their respective tissues underlie physiologic ECM / collagen production and basal lamina production during development and as part of ongoing homeostasis. The application has 2 comprehensive specific aims: 1) To genetically parse the role of myofibroblasts in skeletal muscle and heart during MD in the mouse, 2) To examine how TGFβ, SMAD2/3 and p38α signaling mediate disease in MD through the myofibroblast in vivo. The application will attempt to definitively address the function of the activated fibroblast (myofibroblast) in muscle during MD disease onset and progression. It will also attempt to elucidate the importance of TGFβ signaling in mediating myofibroblast formation and disease activity in vivo, as both canonical and non- canonical pathways will be genetically dissected.