LXR activation in skeletal muscle cells enhances differentiation and promotes protein synthesis

Skeletal muscle possesses a remarkable capacity for regeneration, which is largely orchestrated by muscle satellite cells (MuSCs), a population of tissue-resident stem cells. Upon injury, these cells sense cues from their niche, transition from quiescence to activation, and subsequently undergo proliferation and differentiation to restore damaged myofibers. Although cholesterol, an essential component of the plasma membrane, is critical for cell growth and membrane dynamics, the regulatory landscape governing cholesterol metabolism during muscle regeneration remains poorly defined. In this study, we investigated the temporal expression patterns of lipid-associated genes during regeneration and identified a pronounced upregulation of liver X receptor (LXR) target genes 3 days postinjury, implicating oxysterol-mediated signaling as a potential modulator of the regenerative process. Furthermore, gas chromatography-mass spectrometry (GC-MS) analyses revealed elevated levels of oxysterols, specifically 4β-hydroxycholesterol and 25-hydroxycholesterol, in response to muscle injury induced by cardiotoxin (CTX) or barium chloride (BaCl₂). Complementary in vitro experiments demonstrated that the administration of LXR agonists promoted myogenic differentiation in cultured skeletal muscle cells, whereas pharmacological inhibition of LXR signaling impaired this process. Importantly, LXR activation attenuates lipopolysaccharide (LPS)-induced inflammatory responses in myocytes and concurrently enhances anabolic signaling through the Akt-mTOR axis, leading to increased protein synthesis. Collectively, these findings highlight the previously underappreciated role of cholesterol-derived metabolites in coordinating muscle regeneration, suggesting that LXR-mediated transcriptional programs simultaneously govern differentiation, inflammation, and biosynthetic capacity in regenerating skeletal muscle.<b>NEW & NOTEWORTHY</b> This study aimed to investigate the role of cholesterol-derived metabolites in skeletal muscle regeneration. We found a marked upregulation of liver X receptor (LXR) target genes during muscle regeneration, with increased oxysterol levels (4β-hydroxycholesterol and 25-hydroxycholesterol) after injury. LXR activation promotes myogenic differentiation, inhibits LPS-induced inflammation, and enhances protein synthesis through the Akt-mTOR pathway. These results revealed that LXR is a key regulator of muscle regeneration, influencing differentiation, inflammation, and anabolic processes via cholesterol metabolism.