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STEM cells, MUSCLE regeneration, HORMONE receptors, MUSCULAR dystrophy, MUSCLE cells, SKELETAL muscle, and THYROID hormone receptors

Duchenne muscular dystrophy (DMD) is a severe and progressive myopathy leading to motor and cardiorespiratory impairment. We analyzed samples from patients with DMD and a preclinical rat model of severe DMD and determined that compromised repair capacity of muscle stem cells in DMD is associated with early and progressive muscle stem cell senescence. We also found that extraocular muscles (EOMs), which are spared by the disease in patients, contain muscle stem cells with long-lasting regenerative potential. Using single-cell transcriptomics analysis of muscles from a rat model of DMD, we identified the gene encoding thyroid-stimulating hormone receptor (Tshr) as highly expressed in EOM stem cells. Further, TSHR activity was involved in preventing senescence. Forskolin, which activates signaling downstream of TSHR, was found to reduce senescence of skeletal muscle stem cells, increase stem cell regenerative potential, and promote myogenesis, thereby improving muscle function in DMD rats. These findings indicate that stimulation of adenylyl cyclase leads to muscle repair in DMD, potentially providing a therapeutic approach for patients with the disease. Activating adenylyl cyclase to treat DMD: Duchenne muscular dystrophy (DMD) is characterized by repeated contraction-induced muscle injury that eventually leads to failure of skeletal muscle regeneration. Extraocular muscles (EOMs) are generally spared in DMD, suggesting the presence of a potential compensatory mechanism. Here, Taglietti and colleagues generated a rat model of DMD and found that EOMs had increased thyroid stimulating hormone receptor (TSHR), resulting in decreased muscle stem cell senescence. Forskolin, an adenylyl cyclase activator, stimulated TSHR signaling and led to improved proliferation and reduced senescence of skeletal muscle stem cells, resulting in improved functional performance in affected rats. These findings suggest that activation of TSHR signaling may have therapeutic value in patients with DMD. —MN [ABSTRACT FROM AUTHOR]