DNA methylation promotes the expression of PPARγ transcript 1 at least in part by preventing NRF1 binding to the promoter P1 of chicken PPARγ gene

Peroxisome proliferator-activated receptor gamma (PPARγ) is a master regulator of adipogenesis. Our previous study revealed that chicken PPARγ has 3 alternative promoters named as P1, P2, and P3, and the DNA methylation of promoter P3 was negatively associated with PPARγ mRNA expression in abdominal adipose tissue (AAT). However, the methylation status of promoters P1 and P2 is unclear. Here we assessed promoter P1 methylation status in AAT of Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF). The results showed that promoter P1 methylation differed in AAT between the lean and fat lines of NEAUHLF at 7 wk of age (p < 0.05), and AAT expression of PPARγ transcript 1 (PPARγ1), which was derived from the promoter P1, was greatly higher in fat line than in lean line at 2 and 7 wk of age. The results of the correlation analysis showed that P1 methylation was positively correlated with PPARγ1 expression at 7 wk of age (Pearson's r = 0.356, p = 0.0242), suggesting P1 methylation promotes PPARγ1 expression. To explore the underlying molecular mechanism of P1 methylation on PPARγ1 expression, bioinformatics analysis, dual-luciferase reporter assay, pyrosequencing, and electrophoresis mobility shift assay (EMSA) were performed. The results showed that transcription factor NRF1 repressed the promoter activity of the unmethylated P1, but not the methylated P1. Of all the 4 CpGs (CpG48, CpG49, CpG50, and CpG51), which reside within or nearby the NRF1 binding sites of the P1, only CpG49 methylation in AAT was remarkably higher in the fat line than in lean line at 7 wk of age (3.18 to 0.57, p < 0.05), and CpG49 methylation was positively correlated with PPARγ1 expression (Pearson's r = 0.3716, p = 0.0432). Furthermore, EMSA showed that CpG49 methylation reduced the binding of NRF1 to the P1. Taken together, our findings illustrate that P1 methylation promotes PPARγ1 expression at least in part by preventing NRF1 from binding to the promoter P1.

[Evaluate the prevalence of trachoma in high risk area of China]

OBJECTIVE

To determine the prevalence of trachoma in urban and rural area in China. To provide the data evidence for the strategies of eliminating trachoma in China.

METHODS

Survey was conducted in 13 suspect trachoma high prevalence provinces according to the World Health Organization trachoma grading system and Trachoma Rapid Assessment(TRA).

RESULTS

From 2004 to 2007, a total number of examined children which were younger than 10 years old was 59 630. The prevalence of TF was 0.94%. To sum up the data of 2004 and 2005, the prevalence of active trachoma was 1.71% for children.TT and CO was not reported. The results for subjects older than 50 years old showed that the prevalence of TT was 0.34%. We examined 26 857 adults in both 2004 and 2005.The prevalence of TF, TI, TS and CO was 0.03%,0.08%,0.88% and 0.05% respectively.

CONCLUSIONS

The prevalence of active trachoma of younger children was under 5%. However,the prevalence of TT of the adults was not reached the target.