Studies in differentiating skeletal muscle cells in vitro have revealed that the microtubule-organizing center shifts from the centrosome to the perinuclear sites. As the Golgi apparatus surrounds the nucleus in a myotube, it is unclear whether microtubules are nucleated at the nuclear envelope or at the surrounding Golgi apparatus. In this study, we investigated the positional relationship between the microtubule nucleating sites and the Golgi apparatus in C2C12 myotubes and in primary cultured mouse skeletal myotubes. We focused on gaps in the perinuclear Golgi apparatus where the nuclear envelope was not covered with the Golgi apparatus. In microtubule regrowth assay, microtubule regrowth after cold-nocodazole depolymerization of preexisting microtubules was not found at the gap of the perinuclear Golgi apparatus. Most of the microtubule regrowth was detected at the CDK5RAP2 (CDK5 regulatory subunit-associated protein 2)-rich spots on the perinuclear Golgi apparatus. Disruption of the perinuclear Golgi apparatus with brefeldin A treatment eliminated the perinuclear microtubule regrowth. The Golgi apparatus of undifferentiated myoblasts and those at the cytoplasm of myotubes were also the microtubule nucleating sites. From these observations, we concluded that most of the perinuclear microtubule nucleation occurs on the Golgi apparatus surrounding the nucleus.

体外分化骨骼肌细胞的研究表明，微管组织中心从中心体转移到核周部位。由于高尔基体围绕着肌管中的细胞核，因此尚不清楚微管是在核膜还是在周围的高尔基体上成核。在这项研究中，我们研究了 C2C12 肌管和原代培养的小鼠骨骼肌管中微管成核位点与高尔基体之间的位置关系。我们专注于核周高尔基体中的间隙，其中核膜没有被高尔基体覆盖。在微管再生试验中，在核周高尔基体的间隙处未发现先前存在的微管的冷-诺考达唑解聚后的微管再生。大多数微管再生在核周高尔基体上富含 CDK5RAP2（CDK5 调节亚基相关蛋白 2）的点处检测到。用brefeldin A处理破坏核周高尔基体消除了核周微管再生。未分化成肌细胞的高尔基体和肌管细胞质中的高尔基体也是微管成核部位。根据这些观察，我们得出结论，大部分核周微管成核发生在核周围的高尔基体上。未分化成肌细胞的高尔基体和肌管细胞质中的高尔基体也是微管成核部位。根据这些观察，我们得出结论，大部分核周微管成核发生在核周围的高尔基体上。未分化成肌细胞的高尔基体和肌管细胞质中的高尔基体也是微管成核部位。根据这些观察，我们得出结论，大部分核周微管成核发生在核周围的高尔基体上。