CpG site DNA methylation of the CCAAT/enhancer-binding protein, alpha promoter in chicken lines divergently selected for fatness

CCAAT/enhancer-binding protein (C/EBP), alpha (CEBPA) is a master regulator of adipogenesis and, together with peroxisome proliferator-activated receptor gamma (PPARG), plays a critical role in adipocyte differentiation. Previous studies have demonstrated that CEBPA is regulated by DNA methylation and involved in the osteogenesis and adipogenesis of mouse C3H10T1/2 and bone marrow stromal cells. However, it is unclear whether CEBPA is regulated by DNA methylation in adipose tissues. Thus, the objectives of the present study were to investigate CpG site methylation in a 357-bp CEBPA promoter region and to assess the correlation between promoter CpG site methylation and CEBPA gene expression in the abdominal adipose tissues of Northeast Agricultural University broiler lines divergently selected for abdominal fat content. The results showed that the methylation percentage of the analyzed CEBPA promoter region was significantly higher in lean broilers than in fat broilers at 2 weeks (80.3% vs. 43.4%, P < 0.0001), 3 weeks (95.4% vs. 74.0%, P < 0.0001) and 7 weeks of age (82.6% vs. 57.2%, P < 0.0001). Real-time quantitative RT-PCR analysis showed that CEBPA expression was significantly higher in the fat vs. the lean line at 2 weeks of age (P = 0.0013) but not at 3 or 7 weeks of age. The correlation analysis showed that only at 2 weeks of age was the methylation percentage negatively correlated with CEBPA expression (Pearson's r = -0.8312, P = 0.0029). Of all seven tested CpGs, only two, the CpGs at -1494 and -1478 bp, displayed a significantly negative correlation with CEBPA mRNA expression. These results suggest that the CEBPA is methylated in adipose tissue and may regulate chicken early adipose development.