Lack of PKCθ Promotes Regenerative Ability of Muscle Stem Cells in Chronic Muscle Injury.

Duchenne muscular dystrophy (DMD) is a genetic disease characterized by muscle wasting and chronic inflammation, leading to impaired satellite cells (SCs) function and exhaustion of their regenerative capacity. We previously showed that lack of PKCθ in mice, a mouse model of DMD, reduces muscle wasting and inflammation, and improves muscle regeneration and performance at early stages of the disease. In this study, we show that muscle regeneration is boosted, and fibrosis reduced in θ mice, even at advanced stages of the disease. This phenotype was associated with a higher number of Pax7 positive cells in θ muscle compared with muscle, during the progression of the disease. Moreover, the expression level of Pax7 and Notch1, the pivotal regulators of SCs self-renewal, were upregulated in SCs isolated from θ muscle compared with derived SCs. Likewise, the expression of the Notch ligands Delta1 and Jagged1 was higher in θ muscle compared with . The expression level of Delta1 and Jagged1 was also higher in PKCθ muscle compared with WT muscle following acute injury. In addition, lack of PKCθ prolonged the survival and sustained the differentiation of transplanted myogenic progenitors. Overall, our results suggest that lack of PKCθ promotes muscle repair in dystrophic mice, supporting stem cells survival and maintenance through increased Delta-Notch signaling.