Department of Life Science, University of Seoul, Seoul 02504, Republic of Korea.
Korea Brain Bank, Korea Brain Research Institute, Daegu 41062, Republic of Korea.
Biochim Biophys Acta Gene Regul Mech. 2020 Nov;1863(11):194643. doi: 10.1016/j.bbagrm.2020.194643. Epub 2020 Oct 7.
H19 is a maternally-expressed imprinted gene that encodes long non-coding RNA. Chromatin immunoprecipitation (ChIP)-sequencing analyses of human adipose-derived stem cells (hADSCs) showed that hypoxia induced trimethylation of 4th lysine residue of histone 3 (H3K4me3) in the H19 gene, among the 40 known human imprinted genes, to the greatest extent. We investigated whether hypoxia changed the DNA and histone methylation levels of the imprinted H19 gene in an allele-specific (AS) manner. Using AS primer sets for the human H19 gene, we conducted ChIP-quantitative polymerase chain reaction, which revealed that hypoxia increased the active histone marks, H3K4me3 and H3K9/14Ac, in one allele (named B allele) but not in the other allele (named A allele). In contrast, hypoxia did not change the H3K9me3 levels in either allele. Hypoxia-inducible factor 1 (HIF-1) directly bound to the H19 promoter only in the B allele. HIF-1α knock-down prevented the increase in the active histone modification and mRNA expression of the B allele under hypoxia, indicating that HIF-1α caused AS changes in the histone modification of the H19 gene. Long-term hypoxia did not change the AS DNA methylation throughout the cell cycle. Thus, hypoxia changed the histone modification of the active allele in an HIF-1α-dependent manner, without changing the imprinted status of the H19 gene.
H19 是一种母系表达的印记基因，编码长非编码 RNA。对人脂肪干细胞（hADSCs）的染色质免疫沉淀（ChIP）-测序分析表明，在 40 个已知的人类印记基因中，缺氧最显著地诱导 H19 基因第 4 赖氨酸残基的三甲基化（H3K4me3）。我们研究了缺氧是否以等位基因特异性（AS）的方式改变印记 H19 基因的 DNA 和组蛋白甲基化水平。我们使用人类 H19 基因的 AS 引物组进行 ChIP-定量聚合酶链反应，结果表明，缺氧增加了一个等位基因（称为 B 等位基因）的活性组蛋白标记 H3K4me3 和 H3K9/14Ac，但不增加另一个等位基因（称为 A 等位基因）的活性组蛋白标记。相比之下，缺氧不会改变两个等位基因的 H3K9me3 水平。缺氧诱导因子 1（HIF-1）仅在 B 等位基因上直接结合到 H19 启动子。HIF-1α 敲低可防止缺氧下 B 等位基因的活性组蛋白修饰和 mRNA 表达增加，表明 HIF-1α 导致 H19 基因组蛋白修饰的 AS 变化。长期缺氧不会改变整个细胞周期中 B 等位基因的 AS DNA 甲基化。因此，缺氧以 HIF-1α 依赖的方式改变活性等位基因的组蛋白修饰，而不改变 H19 基因的印记状态。
