Tachibana Makoto, Ueda Jun, Fukuda Mikiko, Takeda Naoki, Ohta Tsutomu, Iwanari Hiroko, Sakihama Toshiko, Kodama Tatsuhiko, Hamakubo Takao, Shinkai Yoichi
Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
Genes Dev. 2005 Apr 1;19(7):815-26. doi: 10.1101/gad.1284005. Epub 2005 Mar 17.
Histone H3 Lys 9 (H3-K9) methylation is a crucial epigenetic mark for transcriptional silencing. G9a is the major mammalian H3-K9 methyltransferase that targets euchromatic regions and is essential for murine embryogenesis. There is a single G9a-related methyltransferase in mammals, called GLP/Eu-HMTase1. Here we show that GLP is also important for H3-K9 methylation of mouse euchromatin. GLP-deficiency led to embryonic lethality, a severe reduction of H3-K9 mono- and dimethylation, the induction of Mage-a gene expression, and HP1 relocalization in embryonic stem cells, all of which were phenotypes of G9a-deficiency. Furthermore, we show that G9a and GLP formed a stoichiometric heteromeric complex in a wide variety of cell types. Biochemical analyses revealed that formation of the G9a/GLP complex was dependent on their enzymatic SET domains. Taken together, our new findings revealed that G9a and GLP cooperatively exert H3-K9 methyltransferase function in vivo, likely through the formation of higher-order heteromeric complexes.
组蛋白H3赖氨酸9(H3-K9)甲基化是转录沉默的关键表观遗传标记。G9a是主要靶向常染色质区域的哺乳动物H3-K9甲基转移酶,对小鼠胚胎发育至关重要。哺乳动物中有一种与G9a相关的甲基转移酶,称为GLP/Eu-HMTase1。在此我们表明,GLP对小鼠常染色质的H3-K9甲基化也很重要。GLP缺陷导致胚胎致死、H3-K9单甲基化和二甲基化严重减少、Mage-a基因表达的诱导以及胚胎干细胞中HP1重新定位,所有这些都是G9a缺陷的表型。此外,我们表明G9a和GLP在多种细胞类型中形成化学计量异源复合物。生化分析表明,G9a/GLP复合物的形成依赖于它们的酶促SET结构域。综上所述,我们的新发现表明,G9a和GLP可能通过形成高阶异源复合物在体内协同发挥H3-K9甲基转移酶功能。