Diarrhea and edematous disease are two major causes of mortality in postweaning piglets, and these conditions lead to huge economic losses in the swine industry. E. coli F18 is the primary causative agent of these two diseases. Bactericidal/permeability-increasing protein (BPI) plays an important role in the natural defense of the host. The aim of this study was to determine the correlation between BPI gene upstream CpG island methylation and mRNA expression. In this study, bisulfite sequencing PCR (BSP) was used to detect the methylation status of the BPI gene upstream CpG island and fluorescence quantitative PCR was used to detect BPI expression in the duodenum of piglets from birth to weaning age. BPI upstream CpG islands were shown to have many putative transcription factor binding sites, 10 CpG sites and every CpG site was methylated. The CpG island methylation level was lowest in 30-day piglets and was significantly lower than levels in 8-day piglets (p < 0.05). BPI mRNA expression was significantly higher in 30-day piglets than at any other age (p < 0.05). Pearson’s correlation analysis showed that the methylation status of the CpG island was negatively correlated with BPI mRNA expression. Statistical significances were found in CpG_1, CpG_3, CpG_4, CpG_7 and CpG_10 (p < 0.05). The data indicate that BPI expression is improved by demethylation of the BPI gene upstream CpG island. Furthermore, CpG_1, CpG_3, CpG_4, CpG_7 and CpG_10 may be critical sites in the regulation of BPI gene expression.

This study aims to provide a theoretical basis on the regulatory mechanism of the α-l,2-fucosyltransferase (FUT1) gene in pigs by analyzing the transcriptional activity of its promoter region. On the basis of the previously obtained promoter sequence, primers upstream and downstream of the gene were designed using the restriction endonucleases KpnI and HindIII respectively, and the recombinant plasmids of the pGL3-promoter were constructed by inserting promoter sequences with partially missing regions. The resultant mutants were observed by transient transfection assay into HEK293 cells, and the transcriptional activity of the promoter region was determined by luciferase activity. The 5'-flanking region of the FUT1 gene (−1150 to +50 bp) exhibited promoter activity. The −1150-bp to −849-bp region showed negative regulation of the gene. The recombinant plasmid pGL3-898 showed the strongest luciferase activity, and the activity showed a decreasing trend when the deleted region was increased. Recombinant plasmids were successfully constructed, verified, and the positive and negative regulation areas and core promoter region were detected, providing a deeper insight into the transcriptional regulatory mechanism of the FUT1 gene.