Berkholz Janine, Eberle Regina, Boller Klaus, Munz Barbara
Charité - University Medicine Berlin, Institute of Physiology, Charitéplatz 1, D-10117 Berlin, Germany.
Paul-Ehrlich-Institute, Paul-Ehrlich-Str. 51-59, D-63225 Langen, Germany.
Micron. 2018 May;108:6-10. doi: 10.1016/j.micron.2018.02.009. Epub 2018 Feb 24.
skNAC (skeletal and heart muscle-specific variant of nascent polypeptide-associated complex) and Smyd1 (SET and MYND domain-containing 1) form a protein dimer which is specific for striated muscle cells. Its function is largely unknown. On the one hand, skNAC-Smyd1 appears to control transcriptional processes in the nucleus, on the other hand, specifically at later stages of myogenic differentiation, both proteins translocate to the sarcoplasm and at least Smyd1 specifically associates with sarcomeric structures and might control myofibrillogenesis and/or sarcomere architecture. Here, using immunofluorescence and electron microscopy, we analyzed sarcomere formation and myofibril organization after siRNA-mediated knockdown of skNAC or Smyd1 expression in murine C2C12 skeletal muscle cells. We found that inhibition of skNAC or Smyd1 expression indeed prevents myofibrillogenesis and sarcomere formation, leading to a disorganized array of myofilaments predominantly within the region immediately beneath the plasma membrane.
skNAC（新生多肽相关复合物的骨骼肌和心肌特异性变体）和Smyd1（含SET和MYND结构域的蛋白1）形成一种对横纹肌细胞具有特异性的蛋白质二聚体。其功能在很大程度上尚不清楚。一方面，skNAC - Smyd1似乎控制细胞核中的转录过程，另一方面，特别是在成肌分化的后期，这两种蛋白质都易位到肌浆中，并且至少Smyd1特异性地与肌节结构相关联，可能控制肌原纤维生成和/或肌节结构。在这里，我们使用免疫荧光和电子显微镜，分析了在小鼠C2C12骨骼肌细胞中通过siRNA介导敲低skNAC或Smyd1表达后的肌节形成和肌原纤维组织。我们发现，抑制skNAC或Smyd1的表达确实会阻止肌原纤维生成和肌节形成，导致肌丝主要在质膜正下方的区域内排列紊乱。
