Neuromuscular junction dynamics in muscle growth and atrophy

Skeletal muscle exhibits remarkable adaptability in response to physiological and pathological stimuli. This study explores the plasticity of the neuromuscular junction (NMJ), a neural–muscle interface that is crucial for synapse formation and force transmission, with a focus on terminal (tSCs), post-synaptic myonuclei (Syn-myo), and muscle stem cells (MuSCs). We have implemented a three-dimensional visualization technique that maintains the spatial tissue context to delineate the communication changes between NMJ and MuSCs at the morphologic and molecular levels in muscle atrophy or hypertrophy. Our findings reveal that a subset of MuSCs is in intimate contact with the NMJ domain, potentially contributing to the local accretion of new Syn-myo. Additionally, tSC proliferation dynamics vary in response to neural- and muscular-derived cues. Using single-cell and single-nucleus RNA-sequencing as well as spatial transcriptomics, we have now characterized the transcriptional adaptations of MuSCs, SCs, and Syn-myo to distinct conditions. This work enhances our understanding of NMJ modulation and its critical role in muscle degeneration or growth.