Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University , Richmond, Virginia.
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology , Atlanta, Georgia.
Am J Physiol Cell Physiol. 2019 Jun 1;316(6):C876-C887. doi: 10.1152/ajpcell.00282.2018. Epub 2019 Mar 20.
Regenerative medicine treatments for severe skeletal muscle injuries are limited, resulting in persistent functional deficits. Clinical options include neglecting the wound with the expectation that fibrosis will develop or using an autologous muscle graft with minimal functional improvement. A regenerative matrix can be used, but muscle fiber development on these matrices remains a challenge in vivo. Here, we explored the fundamental mechanisms that mediate cell-substrate signaling and its effect on cell-cell communication during myoblast fusion and tube formation to improve outcomes following implantation of matrices used to stimulate muscle regeneration. We previously reported that integrin-α7 was increased on anisotropic biomaterials, suggesting a role for α7β1 signaling in myoblast communication via connexin 43 and M-cadherin. Our results demonstrated that α7 silencing blocked expression of myogenic differentiation factor 1 (Myod), myogenin (Myog), myogenic factor 6 (Myf6), myosin heavy chain type 1 (Myh1), and transmembrane protein 8c (Tmem8c), indicating that myoblast fusion was inhibited. Expression of α5 and M-cadherin decreased but β1 and connexin 43 increased. We examined protein production and observed reduced extracellular-signal regulated kinase 1/2 (ERK) in α7-silenced cells that correlated with upregulation of connexin 43 and M-cadherin, suggesting a compensatory pathway. These results indicate that α7 signaling plays a critical role in ex vivo fusion and implicates a relationship with connexin 43 and M-cadherin.
再生医学治疗严重的骨骼肌损伤的方法有限，导致持续的功能缺陷。临床选择包括忽视伤口，期望纤维化会发展，或使用自体肌肉移植物，但功能改善最小。可以使用再生基质，但这些基质上的肌纤维发育仍然是体内的一个挑战。在这里，我们探讨了介导细胞-基质信号的基本机制及其对成肌细胞融合和管状形成过程中细胞间通讯的影响，以改善用于刺激肌肉再生的基质植入后的结果。我们之前报道过，整合素-α7在各向异性生物材料上增加，表明α7β1 信号在成肌细胞通讯中通过连接蛋白 43 和 M-钙黏蛋白发挥作用。我们的结果表明，α7 沉默阻断了肌生成分化因子 1 (Myod)、肌生成素 (Myog)、肌生成因子 6 (Myf6)、肌球蛋白重链 1 型 (Myh1) 和跨膜蛋白 8c (Tmem8c) 的表达，表明成肌细胞融合被抑制。α5 和 M-钙黏蛋白的表达减少，但β1 和连接蛋白 43 增加。我们检查了蛋白质的产生，并观察到α7 沉默细胞中细胞外信号调节激酶 1/2 (ERK) 的减少，这与连接蛋白 43 和 M-钙黏蛋白的上调相关，表明存在代偿途径。这些结果表明，α7 信号在体外融合中起着关键作用，并暗示与连接蛋白 43 和 M-钙黏蛋白有关。
