Integrated analysis of lactylation modification and proteomics revealed potential epigenetic regulation in intramuscular fat deposition of Xidu black pigs.

BACKGROUND: Pork serves as a significant meat commodity, with intramuscular fat (IMF) content being a critical determinant of its quality. However, the epigenetic mechanism of porcine IMF deposition is still unclear. This study integrated proteomics and lactylation profiles from the longissimus thoracis (LT) muscles of pigs with extremely high (IMF_H) and extremely low (IMF_L) IMF content to clarify the association between lactylation and porcine fat deposition. Furthermore, an intramuscular preadipocyte induction and differentiation model was conducted to elucidate the changes in lactylation during adipocyte differentiation. Finally, the regulatory role of lactylation in adipocyte differentiation was explored by modulating lactate production during the induction and differentiation of preadipocytes. RESULTS: Proteomic analysis revealed significantly increased expression of key lipid metabolism related proteins (FASN, APOA4, FABP4, ACLY, PLIN1) in IMF_H pig muscle tissues compared with IMF_L tissues, along with substantial activation of lipid metabolism pathways. Lactylation profiling identified 95 differential lysine sites across 56 proteins, with most showing lower lactylation levels in the IMF_H group. The integrative omics analysis revealed differences in lactylation profiles in porcine LT tissues with varying efficiencies of IMF deposition, highlighted PGK1, PKM, and PYGM as central lactylation-modified proteins in porcine fat deposition regulation. Further in vitro study proved that lactate-mediated lactylation inhibited adipogenic differentiation of porcine intramuscular preadipocytes through PPARγ signaling pathway. CONCLUSION: This study clarified the changes in the lactylation profile in porcine LT tissues with varying efficiencies of IMF deposition, and demonstrated that lactate-mediated lactylation inhibits the PPARγ signaling pathway and the adipogenic differentiation of porcine intramuscular preadipocyte. This study provided a new insight to understanding the epigenetic regulation mechanisms of lipid deposition in pigs.