GPX8 inhibits myogenic differentiation and promotes slow myofiber formation of porcine skeletal muscle satellite cells.

Glutathione peroxidase 8(GPX8) is a key member of the glutathione peroxidase family. Genome-wide association studies (GWAS) have indicated that GPX8 is highly associated with growth and carcass traits of pigs. Using porcine skeletal muscle satellite cells, this study explored the effects of GPX8 on myogenic differentiation and myofiber type switching through GPX8 knockdown and overexpression, combined with analyses involving immunofluorescence staining, qRT-PCR, and Western blotting. The results demonstrated that GPX8 knockdown significantly increased the myogenic differentiation index (P<0.01) and promoted both mRNA and protein levels of the myogenic marker genes MyHC and MyoG (P<0.05). Conversely, GPX8 overexpression exhibited the opposite effects. GPX8 knockdown significantly reduced the mRNA level of MYH7 (P<0.01) and protein level of slow-twitch MyHC (slow-MyHC)(P<0.05), while suppressing mitochondrial biogenesis. In contrast, GPX8 overexpression exhibited opposing results. Integrated multi-omics data from GWAS analyses were employed to identify expression quantitative trait locus (eQTLs) regulating GPX8 expression. The effects of candidate SNPs on GPX8 promoter activity were further validated using dual-luciferase reporter assays. Five candidate SNPs (rs335618489, rs325233940, rs32989756, rs322106839, and rs701033890) were identified within the GPX8 promoter region. Among these, rs335618489-T, rs325233940-G, rs32989756-T, and rs322106839-G significantly upregulated GPX8 expression level by altering promoter activity (P<0.01), thereby influencing porcine muscle development traits. In summary, this study demonstrates that GPX8 inhibits the myogenic differentiation of porcine skeletal muscle satellite cells and promotes the transition from fast-twitch to slow-twitch myofibers. Functional SNPs in the GPX8 promoter region influence porcine muscle development by modulating GPX8 expression, thereby providing valuable breeding targets for improving pork production.