An improved method for culturing myotubes on laminins for the robust clustering of postsynaptic machinery

This study demonstrates an improved protocol for culturing C2C12 muscle cells that reproducibly promote the formation of complex AChR clusters. The authors tested several laminin isoforms and found that laminin-121, laminin-211, laminin-221, laminin-511, and laminin-521 induced significantly more AChR clusters in C2C12 myotubes than the commonly used laminin-111. Moreover, they found that clusters of postsynaptic machinery that were formed in C2C12 myotubes cultured on laminin-121 and laminin-221 were the most developed. Laminin-421 and laminin-511 were the isoforms that promoted formation of the most podosome-containing AChR clusters in human primary myotubes. Myotubes that were derived from human primary myoblasts obtained from human biopsies also formed AChR clusters in vitro that underwent the remodeling process, thus demonstrating the potential utility of this methodology for further studies that seek to improve diagnoses of neuromuscular disorders and elucidate their underlying mechanisms. Thus, this novel method may facilitate the identification of novel synaptic regulators and the high reproducibility of culturing and robust formation of AChR clusters are important prerequisites for establishing high-throughput screening. The protocol is also useful for obtaining and freezing a large number of cell stocks and utilizing cells for experimentation with a constant and low passage number, which significantly increases experimental reproducibility. The method can be implemented in different formats, such as permanox slides, glass surfaces as well as multi-well culturing dishes. Collectively, these results demonstrate an advancement of culturing myotubes.