Multi-omics analysis reveals that PCK2 may be a key gene for tail fat deposition in Altay sheep under different energy intake

This study investigated the regulatory mechanisms of different energy levels on tail fat deposition in Altay sheep (Ovis Aries) through multi-omics integrated analysis. Thirty healthy Altay sheep (Ovis Aries) were randomly divided into three groups: low-energy (NL, 50% of maintenance metabolic energy), medium-energy (NM, 100%), and high-energy (NR, 150%) groups, and fed for 30 days. Tail adipose tissues were collected for transcriptomic RNA-seq and proteomic iTRAQ analysis. Compared with the NL group, the NR group exhibited the highest number of differentially expressed genes (DEGs, 2059), with ACSL4, RXRG, PCK2, SLC27A2 and ACSBG1 identified as core regulatory genes. Proteomics identified 273 up-regulated versus 275 down-regulated differential abundant proteins (DAPs). Eighteen DEGs in the NRvsNL_NR.vs.NL group were linked to DAPs, but the overall correlation between transcriptomics and proteomics was low (R=0.124, 0.101 and 0.256), suggesting that involvement of post-translational modifications in regulation. Further screening demonstrated that PCK2 was significantly downregulated under energy restriction, reducing fatty acid synthesis efficiency by suppressing the gluconeogenesis pathway. This study is the first to identify PCK2 may be a significant candidate gene regulating tail fat deposition in Altay sheep, providing a molecular basis for optimizing fat distribution through nutritional interventions.