DOT1L Activity Promotes Proliferation and Protects Cortical Neural Stem Cells from Activation of ATF4-DDIT3-Mediated ER Stress In Vitro
DOT1L Activity Promotes Proliferation and Protects Cortical Neural Stem Cells from Activation of ATF4-DDIT3-Mediated ER Stress In Vitro
复制标题
DOI：
10.1002/stem.2187
复制
发表时间：
2016-01-01
期刊：
影响因子：
5.2
通讯作者：
Vogel, Tanja
中科院分区：
文献类型：
--
作者：
Roidl, Deborah;Hellbach, Nicole;Vogel, Tanja
越来越多的证据表明，赖氨酸甲基转移酶DOT1L/KMT4在干细胞的增殖、存活和分化中起着重要的作用。我们研究了DOT1L在大脑皮质神经干细胞(NSCs)中的功能。药物抑制和shRNA介导的DOT1L基因敲除可损害神经干细胞的增殖和存活。DOT1L抑制特异性地诱导内质网(ER)中在未折叠蛋白反应(UPR)过程中被激活的基因。染色质免疫沉淀分析显示，编码参与内质网应激反应的中心分子的两个基因，ATF4和Ddit3(CHOP)，被标记为H3K79甲基化。对DOT1L活性的干扰导致两个基因的转录激活，并伴随着H3K79二甲基化水平的降低。尽管UPR的下游效应物，如Ppp1r15a/Gadd34、ATF3和TNFRSF10B/Dr5也在转录上被激活，但这很可能是对ATF4表达增加的反应，而不是H3K79甲基化改变的直接结果。虽然干细胞特别容易受到压力的影响，但UPR和内质网应激在这些细胞中还没有得到广泛的研究。由于内质网应激程序的激活也与引导干细胞分化或维持增殖状态有关，因此必须严格调控UPR。我们和已发表的数据表明，包括H3K4me3、H3K14ac和H3K79me2在内的组蛋白修饰参与了内质网应激基因转录激活的控制。在这种背景下，在ATF4和Ddit3启动子上丢失H3K79me2似乎标志着激活NSCs死亡计划的不返回点。
Growing evidence suggests that the lysine methyltransferase DOT1L/KMT4 has important roles in proliferation, survival, and differentiation of stem cells in development and in disease. We investigated the function of DOT1L in neural stem cells (NSCs) of the cerebral cortex. The pharmacological inhibition and shRNA-mediated knockdown of DOT1L impaired proliferation and survival of NSCs. DOT1L inhibition specifically induced genes that are activated during the unfolded protein response (UPR) in the endoplasmic reticulum (ER). Chromatin-immunoprecipitation analyses revealed that two genes encoding for central molecules involved in the ER stress response, Atf4 and Ddit3 (Chop), are marked with H3K79 methylation. Interference with DOT1L activity resulted in transcriptional activation of both genes accompanied by decreased levels of H3K79 dimethylation. Although downstream effectors of the UPR, such as Ppp1r15a/Gadd34, Atf3, and Tnfrsf10b/Dr5 were also transcriptionally activated, this most likely occurred in response to increased ATF4 expression rather than as a direct consequence of altered H3K79 methylation. While stem cells are particularly vulnerable to stress, the UPR and ER stress have not been extensively studied in these cells yet. Since activation of the ER stress program is also implicated in directing stem cells into differentiation or to maintain a proliferative status, the UPR must be tightly regulated. Our and published data suggest that histone modifications, including H3K4me3, H3K14ac, and H3K79me2, are implicated in the control of transcriptional activation of ER stress genes. In this context, the loss of H3K79me2 at the Atf4- and Ddit3-promoters appears to mark a point-of-no-return that activates the death program in NSCs.