Comparison of the Genome-Wide DNA Methylation Profiles between Fast-Growing and Slow-Growing Broilers

Abstract

<div><p>Introduction</p><p>Growth traits are important in poultry production, however, little is known for its regulatory mechanism at epigenetic level. Therefore, in this study, we aim to compare DNA methylation profiles between fast- and slow-growing broilers in order to identify candidate genes for chicken growth. Methylated DNA immunoprecipitation-sequencing (MeDIP-seq) was used to investigate the genome-wide DNA methylation pattern in high and low tails of Recessive White Rock (WRR_h; WRR_l) and that of Xinhua Chickens (XH_h; XH_l) at 7 weeks of age. The results showed that the average methylation density was the lowest in CGIs followed by promoters. Within the gene body, the methylation density of introns was higher than that of UTRs and exons. Moreover, different methylation levels were observed in different repeat types with the highest in LINE/CR1. Methylated CGIs were prominently distributed in the intergenic regions and were enriched in the size ranging 200–300 bp. In total 13,294 methylated genes were found in four samples, including 4,085 differentially methylated genes of WRR_h Vs. WRR_l, 5,599 of XH_h Vs. XH_l, 4,204 of WRR_h Vs. XH_h, as well as 7,301 of WRR_l Vs. XH_l. Moreover, 132 differentially methylated genes related to growth and metabolism were observed in both inner contrasts (WRR_h Vs. WRR_l and XH_h Vs. XH_l), whereas 129 differentially methylated genes related to growth and metabolism were found in both across-breed contrasts (WRR_h Vs. XH_h and WRR_l Vs. XH_l). Further analysis showed that overall 75 genes exhibited altered DNA methylation in all four contrasts, which included some well-known growth factors of IGF1R, FGF12, FGF14, FGF18, FGFR2, and FGFR3. In addition, we validate the MeDIP-seq results by bisulfite sequencing in some regions.</p> <p>Conclusions</p><p>This study revealed the global DNA methylation pattern of chicken muscle, and identified candidate genes that potentially regulate muscle development at 7 weeks of age at methylation level.</p> </div