DNA Methylation of Pig FUT3 Promoter Alters mRNA Expression to Regulate E. coli F18 Susceptibility

Post-weaning diarrhea (PWD) is frequently associated with E. coli F18 infections in piglets. However, the underlying molecular mechanism concerning the resistance of E. coli F18 in local weaned piglets in China is not clearly understood. In the present study, by a comparative analysis of the transcriptome, a-1,3-fucosyltransferase (FUT3) was evaluated as a key candidate correlated with resistance to E. coli F18 in Sutai and Meishan piglets. Functional analysis demonstrated that FUT3 acts as a key positive regulator of E. coli F18 susceptibility in newly food accustomed piglets. However, the core promoter of FUT3 was present at −500–(−206) bp (chr.2: g.73171117–g.73171616), comprising of 9 methylated CpG sites. Among these, the methylation levels of the two CpG sites (mC-3, mC-5) located in HIF1A and Sp1 transcription factor (TF) considerably associated with mRNA expression of FUT3 (p < 0.05). Our findings indicated that the methylation of mC-3 and mC-5 sites has certain inhibitory effect on FUT3 expression and promotes the resistance of E. coli F18 in piglets. The underlined study may explore FUT3 as a new candidate target in E. coli F18 infection in Chinese local weaned piglets.