Specific labelling of myonuclei by an antibody against Pericentriolar material 1 (PCM1) on skeletal muscle tissue sections

Aim: Skeletal muscle is a heterogeneous tissue containing several different cell types, and only about 40%‐50% of the cell nuclei within the tissue belong to myofibres. Existing technology, attempting to distinguish myonuclei from other nuclei at the light microscopy level, has led to controversies in our understanding of the basic cell biology of muscle plasticity. This study aims at demonstrating that an antibody against the protein pericentriolar material 1 (PCM1) can be used to reliably identify myonuclei on histological cross sections from humans, mice and rats. Methods: Cryosections were labelled with a polyclonal antibody against PCM1. The specificity of the labelling for myonuclei was verified using 3D reconstructions of confocal z‐stacks triple‐labelled for DNA, dystrophin and PCM1, and by co‐localization with nuclear mCherry driven by the muscle‐specific Alpha‐Actin‐1 promoter after viral transduction. Results: The PCM1 antibody specifically labelled all myonuclei, and myonuclei only, in cryosections of muscles from rats, mice and men. Nuclei in other cell types including satellite cells were not labelled. Both normal muscles and hypertrophic muscles after synergist ablation were investigated. Conclusion: Pericentriolar material 1 can be used as a specific histological marker for myonuclei in skeletal muscle tissue without relying on counterstaining of other structures or cumbersome and subjective analysis of nuclear positioning