Tomita Tatsunosuke, Kurita Ryoji, Onishi Yoshiaki
Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), DBT-AIST International Laboratory for Advanced Biomedicine (DAILAB), Higashi 1-1-1, Tsukuba 305-8566, Japan.
Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), DBT-AIST International Laboratory for Advanced Biomedicine (DAILAB), Higashi 1-1-1, Tsukuba 305-8566, Japan
Biosci Rep. 2017 May 19;37(3). doi: 10.1042/BSR20170053. Print 2017 Jun 30.
We have been investigating transcriptional regulation of the gene, a critical component of the mammalian clock system including DNA methylation. Here, a more detailed analysis of the regulation of DNA methylation of proceeded in RPMI8402 lymphoma cells. We found that CpG islands in the and the promoters were hyper- and hypomethylated, respectively and that 5-aza-2'-deoxycytidine (aza-dC) not only enhanced gene expression but also oscillation within 24 h in RPMI8402 cells. That is, such hypermethylation of CpG islands in the promoter restricted expression which was recovered by aza-dC within 1 day in these cells. These results suggest that the circadian clock system can be recovered through expression induced by aza-dC within a day. The promoter of RPMI8402 cells, which is a methylation hotspot in lymphoblastic leukemia, was also hypermethylated and aza-dC gradually recovered expression in 3 days. In addition, methylation-specific PCR revealed a different degree of aza-dC-induced methylation release between and These results suggest that the aza-dC-induced recovery of gene expression from DNA methylation is dependent on a gene, for example the rapid response to demethylation by the circadian system, and thus, is of importance to clinical strategies for treating cancer.
我们一直在研究该基因的转录调控，它是包括DNA甲基化在内的哺乳动物生物钟系统的关键组成部分。在此，我们对RPMI8402淋巴瘤细胞中该基因DNA甲基化的调控进行了更详细的分析。我们发现，该基因启动子和另一启动子中的CpG岛分别发生了高甲基化和低甲基化，并且5-氮杂-2'-脱氧胞苷（aza-dC）不仅增强了该基因的表达，还使RPMI8402细胞在24小时内的表达出现振荡。也就是说，该基因启动子中CpG岛的这种高甲基化限制了其表达，而在这些细胞中，aza-dC在1天内使其表达得以恢复。这些结果表明，昼夜节律系统可通过aza-dC在一天内诱导的表达得以恢复。RPMI8402细胞的该基因启动子是淋巴细胞白血病中的甲基化热点，也发生了高甲基化，aza-dC在3天内逐渐恢复了其表达。此外，甲基化特异性PCR显示，该基因和另一基因之间aza-dC诱导的甲基化释放程度不同。这些结果表明，aza-dC诱导的基因表达从DNA甲基化中的恢复取决于基因，例如昼夜节律系统对去甲基化的快速反应，因此，这对癌症治疗的临床策略具有重要意义。
