c-myb基因启动子的表观遗传学修饰对c-myb基因表达的影响

Epigenetic Modification of the c-myb Promoter Regulates c-myb Expression

转录因子c-Myb是造血过程中重要的调节因子,然而在白血病中c-Myb常常出现异常激活。尽管已有大量关于c-myb表达调控机制的研究,但仍有很多疑问尚未解开。本研究在人类红白血病细胞系K562中,研究了位于人类6号染色体上的c-myb基因启动子区域的表观修饰对基因转录调控的影响,分别检测了K562细胞在铁血红素(Hemin)诱导分化前后c-myb启动子的的表观修饰,同时构建靶向c-myb启动子的g RNA,利用CRISP/Cas9系统携带相应的表观修饰酶类对启动子区域进行表观修饰,检测激活和抑制性表观修饰对c-myb表达的影响。结果显示,K562细胞分化后c-myb启动子的组蛋白修饰H3K27ac,H3K4me1的水平降低,同时c-myb水平降低。dCas9-p300靶向c-myb启动子可以提高该区域H3K27ac并激活c-myb基因的表达,而dCas9-DNMT3A则提高DNA甲基化水平并抑制该基因的表达。本研究显示c-myb启动子区域表观遗传学修饰和c-myb的表达水平相关,通过改变c-myb启动子的表观遗传学修饰水平可以控制c-myb的表达水平,为进一步研究白血病提供了新的突破点。

Transcription factor c-Myb plays important roles in hematopoiesis,dysregulation of c-myb has been implicated in leukemia.Despite that regulation of c-myb has been widely studied,the detailed mechanism is still unclear.In this study,the K562 human hematopoietic cell line was used to study the transcriptional mechanism of the c-myb promoter region on human chromosome 6,we detected the change of epigenetic modification of the c-myb promoter in Hemin-induced K562 cells,in the meantime we constructed c-myb promoter g RNA to disturb c-myb expression by CRISP/Cas9 activation and inhibition system.The result indicated that the enrichment of histone modification H3 K27 ac and H3 K4 me1 was decreased during differentiation of K562 cells.In the promoter region,the dCas9-p300 acetyltransferase increased H3 K27 ac level and activated the expression of c-myb,while the dCas9 DNMT3 A methyltransferase increased DNA methylation level and inhibited the expression of this gene.The present data showed that epigenetic modification of the c-myb promoter is associated with c-myb expression and is a target for c-myb regulation,meanwhile provided a new idea for the research on human leukemia and other cancers.