Multi-Omics Integration Identifies ABCD4 as a Key Regulator of Backfat Thickness and Lipid Deposition in Pietrain Pigs.

The commercial pork production sector prioritizes genetic improvements in lean meat percentage to enhance profitability and meet consumer preferences. The Pietrain pig, a premier terminal sire breed renowned for its exceptional muscularity and leanness, serves as an ideal model to decipher the genetic underpinnings of these traits. This study investigated two key measures of leanness, backfat thickness and loin muscle depth, in two distinct Pietrain populations to elucidate the genetic architecture underlying these traits. We estimated genetic parameters and performed a meta-analysis of genome-wide association studies, identifying ABCD4, LTBP2, NUMB, and SLC30A9 as candidate genes. To further investigate these associations, we integrated information on molecular quantitative trait loci from the PigGTEx project and single-cell transcriptomic resources. This integrative approach prioritized ABCD4 as a key candidate gene regulating backfat thickness. Functional validation in 3T3-L1 preadipocytes revealed a novel dual regulatory role for ABCD4: its knockdown suppressed cell proliferation while simultaneously stimulating adipogenic differentiation, as demonstrated by the upregulation of key markers. Our findings positioned ABCD4 as a critical modulator of fat deposition, likely through its influence on the core adipogenic transcriptional network. By establishing an analytical framework that integrates large-scale sequencing data from Pietrain pigs with functional validation, our study addresses a key gap in understanding the genetic basis of leanness and provides novel insights for precision breeding.