Fibro-Adipogenic Progenitor cells from murine SMA muscles are intrinsically adipogenic

Although classically viewed as a neurogenic disease, SMA patients exhibit poor skeletal muscle regeneration and increased fatty-fibrotic infiltration. Fibro-Adipogenic progenitors are mesenchymal precursor cells that contribute to muscle remodeling and underly fat and fibrosis formation.

Because FAPs transiently express Smn1 during regeneration, FAPs were examined in muscles from adult SMA and control mice to determine if reduced Smn activity altered their properties. We performed a non-biased screen of FAPs following BaCl2-induced injury using an in-situ cell surface proteomic strategy that probed the cellular membrane and environment of FAPs in early regeneration. Proteomic profiling revealed early adipogenic priming in SMA tissues, with increased levels of perilipin-4 and adipocyte lipid-binding proteins.