Epigenetic analysis of mPer1 promoter in peripheral tissues

Abstract

E-boxes targeted by BMAL1-CLOCK dimers are crucial for the rhythmic expression of mPer1. We investigated whether DNA methylation, especially E-box CpG methylation, plays a role in the regulation of mPer1 oscillations in mice. E-box-containing amplicons were examined in liver, thymus and testis around-the-clock using bisulfite sequencing, combined bisulfite restriction analysis (COBRA) and bisulfite pyrosequencing. Results indicated that mPer1 E-boxes were only hypomethylated in all tissues at all circadian stages, suggesting that E-boxes are open to BMAL1-CLOCK dimers at all times, and thus E-box methylation is most likely not involved in global regulation of the mPer1 rhythm. In addition, low but noticeable methylation of E-box 3 and/or 4 and a sub-group of CpGs nearby were identified in all three tissues, indicating this region as area of preferred methylation, and may have a role in silencing mPer1 transcription.

Keywords:

• mPer1
• promoter
• methylation
• E-box
• peripheral tissues
• rhythm

Acknowledgements

We thank Jingyan Song for helpful discussions. Research support for YC, SL, NL, YG and PC was provided by the National Natural Science Foundation of China (30400148, 30430280); The National Basic Research Program of China (2006CB500701, 2006CB943703); The National 863 Project grant of China (2006AA02A408); Scientific project of Beijing municipal science and technology commission (D07050701350703); The Natural Sciences Foundation of Beijing (5063042); and New Century Excellent Talents in University (2007), and for RBS, in part, by financial support from Jane and Mike Popovich.