PGC-1alpha pathway dysregulation disrupts myofiber specification in a mouse model of SBMA

Using a gene-targeted SBMA mouse model, we applied single-nucleus RNA sequencing to identify a previously unrecognized, disease-specific population of skeletal muscle myonuclei that replace normal myonuclear subtypes.

This transition was driven by dysregulation of the PGC-1α pathway, a central regulator of myofiber specification and metabolic identity. PGC-1α dysfunction in SBMA muscle was age-, hormone-, and polyQ length–dependent and was partially rescued by subcutaneous delivery of AR-targeted antisense oligonucleotides. Integrated ChIP-seq and RNA-seq analyses revealed that aberrant PGC-1α activity promoted the expression of a distinct set of myofiber specification genes while downregulating those defining healthy Type IIb and Type IIx myonuclei.