Preliminary Analysis of Placental DNA Methylation Profiles in Piglets with Extreme Birth Weight Variations

Adequate birth weight is essential for animal survival and subsequent growth. However, the mechanism by which placental DNA methylation influences fetal growth remains incompletely understood. This study employed whole-genome bi-sulfite sequencing (WGBS) and RNA sequencing to analyze placental tissues from two weak piglets and two normal piglets born to the same sow. Transcriptome analysis identified 1989 differentially expressed genes (DEGs) enriched in blood/immune processes. Additionally, differentially methylated regions linked to DEG repression were enriched in extracellular matrix (ECM) receptors and angiogenesis pathways. To investigate the role of DNA methylation in gene regulation, porcine trophoblast cells (PTr2) were treated with either DMSO (control) or the DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza). Real-time quantitative PCR (RT-qPCR) analysis demonstrated significant upregulation of PACC1, SLC7A1, and PKP1 gene expression in the 5-Aza-treated group compared to controls (p < 0.05). Furthermore, methylation-specific PCR (MS-PCR) assays confirmed that the transcriptional activity of these genes is directly modulated by DNA methylation. These findings suggest that the dynamic regulation of DNA methylation in gene promoters may influence variations in placental morphology and birth weight in piglets, offering new insights into epigenetic regulation of fetal development, though larger studies are needed for validation.