Degenerative and regenerative pathways underlying Duchenne muscular dystrophy revealed by single-nucleus RNA sequencing

Duchenne muscular dystrophy (DMD) is a fatal muscle disorder characterized by cycles of degeneration and regeneration of multinucleated myofibers and pathological activation of a variety of other muscle-associated cell types. The extent to which different nuclei within the shared cytoplasm of a myofiber may display transcriptional diversity and whether individual nuclei within a multinucleated myofiber might respond differentially to DMD pathogenesis is unknown. Similarly, the potential transcriptional diversity among nonmuscle cell types within dystrophic muscle has not been explored. Here, we describe the creation of a mouse model of DMD caused by deletion of exon 51 of the dystrophin gene, which represents a prevalent disease-causing mutation in humans. To understand the transcriptional abnormalities and heterogeneity associated with myofiber nuclei, as well as other mononucleated cell types that contribute to the muscle pathology associated with DMD, we performed single-nucleus transcriptomics of skeletal muscle of mice with dystrophin exon 51 deletion. Our results reveal distinctive and previously unrecognized myonuclear subtypes within dystrophic myofibers and uncover degenerative and regenerative transcriptional pathways underlying DMD pathogenesis. Our findings provide insights into the molecular underpinnings of DMD, controlled by the transcriptional activity of different types of muscle and nonmuscle nuclei.