Suppressing PDGFRβ Signaling Enhances Myocyte Fusion to Promote Skeletal Muscle Regeneration

Abstract

Muscle cell fusion is critical for forming and maintaining multinucleated myotubes during skeletal muscle development and regeneration. However, the molecular mechanisms directing cell-cell fusion are not fully understood. Here, we identify platelet-derived growth factor receptor beta (PDGFR{beta}) signaling as a key modulator of myocyte fusion in adult muscle cells. Our findings demonstrate that genetic deletion of Pdgfr{beta} enhances muscle regeneration and increases myofiber size, whereas PDGFR{beta} activation impairs muscle repair. Inhibition of PDGFR{beta} activity promotes myonuclear accretion in both mouse and human myotubes, whereas PDGFR{beta} activation stalls myotube development by preventing cell spreading to limit fusion potential. Transcriptomics analysis show that PDGFR{beta} signaling cooperates with TGF{beta} signaling to direct myocyte size and fusion. Mechanistically, PDGFR{beta} signaling requires STAT1 activation, and blocking STAT1 phosphorylation enhances myofiber repair and size during regeneration. Collectively, PDGFR{beta} signaling acts as a regenerative checkpoint and represents a potential clinical target to rapidly boost skeletal muscle repair.