Pedrosa-Domellöf F, Tiger C F, Virtanen I, Thornell L E, Gullberg D
Department of Integrative Medical Biology, Section for Anatomy, Umeå University, and Department of Musculoskeletal Research, National Institute for Working Life, Umeå, Sweden.
J Histochem Cytochem. 2000 Feb;48(2):201-10. doi: 10.1177/002215540004800205.
In addition to being the specialized site for transmission of force from the muscle to the tendon, the myotendinous junction (MTJ) also plays an important role in muscle splitting during morphogenesis. An early event in the formation of the MTJ is a regional deposition of basement membranes. We used immunocytochemistry to investigate the distribution of laminin chains during the development of MTJs in human limb muscle at 8-22 weeks of gestation (wg) and in adult MTJs. We used polyclonal antibodies and a new monoclonal antibody (MAb) against the human laminin alpha1 G4/G5 domains. At 8-10 wg, laminin alpha1 and laminin alpha5 chains were specifically localized to the MTJ. Laminin alpha1 chain remained restricted to the MTJ at 22 wg as the laminin beta2 chain had appeared, whereas the laminin alpha5 chain became deposited along the entire length of the myotubes from 12 wg. In the adult MTJ, only vestigial amounts of laminin alpha1 and laminin alpha5 chains could be detected. On the basis of co-distribution data, we speculate that laminin alpha1 chain in the forming MTJ undergoes an isoform switch from laminin 1 to laminin 3. Our data indicate a potentially important role for laminin alpha1 chain in skeletal muscle formation. (J Histochem Cytochem 48:201-209, 2000)
除了作为肌肉向肌腱传递力量的特殊部位外，肌-腱连接（MTJ）在形态发生过程中的肌肉分裂中也起着重要作用。MTJ形成的早期事件是基底膜的区域沉积。我们采用免疫细胞化学方法研究了妊娠8 - 22周（wg）的人肢体肌肉MTJ发育过程中以及成人MTJ中层粘连蛋白链的分布。我们使用了针对人层粘连蛋白α1 G4/G5结构域的多克隆抗体和一种新的单克隆抗体（MAb）。在8 - 10 wg时，层粘连蛋白α1和层粘连蛋白α5链特异性定位于MTJ。当层粘连蛋白β2链出现时，层粘连蛋白α1链在22 wg时仍局限于MTJ，而层粘连蛋白α5链从12 wg开始沿肌管全长沉积。在成人MTJ中，仅能检测到少量残留的层粘连蛋白α1和层粘连蛋白α5链。基于共分布数据，我们推测正在形成的MTJ中的层粘连蛋白α1链经历了从层粘连蛋白1到层粘连蛋白3的异构体转换。我们的数据表明层粘连蛋白α1链在骨骼肌形成中可能具有重要作用。（《组织化学与细胞化学杂志》48:201 - 209, 2000）
