MyoD and Myogenin are Required for Agrin‐induced AChR Clustering

During skeletal muscle development, specific transcription factors called myogenic regulatory factors are expressed at specific times to guide myogenesis. Gene expression of MyoD correlates with myoblast proliferation, while gene expression of Myogenin correlates with myoblast fusion into multinucleated myotubes and subsequent muscle fiber differentiation. Our lab investigates myogenesis and neuromuscular synapse formation using the C2C12 myotube cell culture model. C2C12 myoblasts proliferate in growth medium, and then fuse into myotubes when switched to low‐serum differentiation medium (DM) for 72 hours. Myotubes are stimulated to cluster acetylcholine receptors (AChRs) by the addition of agrin for the last 16 hours in DM. Our hypothesis was that Myogenin, but not MyoD, is required for agrin‐induced AChR clustering. Daily exposure to 1 ug/ml of MyoD antibody (Ab) or Myogenin Ab was sufficient to decrease agrin‐induced AChR clustering. In addition, exposure to 1 ug/ml of MyoD Ab or Myogenin Ab limited to the first or second 24 hours in DM also decreased agrin‐induced AChR clustering. However, agrin‐induced AChR clustering was unaffected by exposure to MyoD Ab or Myogenin Ab exposure during the last 24 hours in DM. We conclude that both MyoD and Myogenin are required for agrin‐induced AChR clustering. Grant Funding Source : None