Differential methylation of the miR-132/212 promoter contributes to PRRSV resistance by targeting FOXA1 and MYD88 in pigs.

Abstract

PRRSV causes substantial economic losses to the global swine industry. Interestingly, Chinese native pig breeds exhibit greater resistant to PRRSV than commercial foreign breeds. To explore the genetic basis of this difference, this study investigated the expression and function of the miR- 132/212 families in Meishan (resistant) and Landrace pigs (susceptible). RT-qPCR analysis revealed significantly higher basal expression of miR-132/212 in Meishan pigs than in Landrace pigs (p&#x202f;<&#x202f;0.05). Upon PRRSV infection in Marc-145&#x202f;cells, the expression of this miRNA family was upregulated at 12&#x202f;h post-infection. The PRRSV - induced miR-132/212 family inhibited viral ORF7 copy number and N protein expression (p&#x202f;<&#x202f;0.01). Further mechanistic studies identified FOXA1 and MYD88 as direct targets of miR-132 and miR-212, respectively, with both miRNAs suppressing the mRNA and protein expression of their targets (p&#x202f;<&#x202f;0.01). - RT-qPCR showed MYD88 was upregulated in Marc-145&#x202f;cells 36&#x202f;h after infection (p&#x202f;<&#x202f;0.01). Overexpression of MYD88 increased PRRSV copy numbers, N protein expression, and N protein - specific green fluorescence intensity. Epigenetic analysis identified three CpG islands in the miR-132/212 promoter region and bisulfite sequencing confirmed lower methylation levels in Meishan pigs compared to Landrace pigs. In summary, differential promoter methylation of the miR-132/212 cluster between the two breeds leads to divergent expression of these miRNAs, which in turn attenuates PRRSV replication by targeting FOXA1 and MYD88, thereby contributing to the natural resistance observed in Chinese native breeds.