PTBP1 inhibition reprograms myogenesis to rescue impaired muscle regeneration in mdx mice through correcting E2A splicing

Duchenne muscular dystrophy, caused by mutations in the DMD gene encoding dystrophin, is a severe progressive muscle-wasting disorder characterized by impaired muscle regeneration. We reveal the alternative splicing of transcription factor E2-alpha (encoding transcription factors E12 and E47) plays a pivotal role in myogenic progression. E47 is highly expressed in proliferating myoblasts and promotes proliferation, whereas E12 is upregulated during differentiation and drives myogenic commitment. Mechanistically, we identify the nuclear splicing factor polypyrimidine tract binding protein 1 as a key regulator of transcription factor E2-alpha mutually exclusive alternative splicing. Polypyrimidine tract binding protein 1 levels decline during normal myoblast differentiation, facilitating the switch from E47 to E12. However, in Duchenne muscular dystrophy patients and mdx mice, polypyrimidine tract binding protein 1 remains aberrantly elevated, resulting in dysregulated E47/E12 ratios (increased E47 and decreased E12), which disrupts myogenic differentiation and impairs muscle regeneration. Therapeutically, polypyrimidine tract binding protein 1 knockdown restores myoblast differentiation, enhances muscle repair, and improves muscle function in mdx mice. Furthermore, we demonstrate that dergrasyn, a deubiquitinase inhibitor, induces polypyrimidine tract binding protein 1 degradation, restores myogenic differentiation, and ameliorates dystrophic pathology. Our findings identify polypyrimidine tract binding protein 1 as a potential therapeutic target for Duchenne muscular dystrophy and highlight modulation of transcription factor E2-alpha splicing as a promising strategy to restore muscle regeneration.