Physiology Weihenstephan, Technische Universität München, 85354 Freising-Weihenstephan, Germany.
J Steroid Biochem Mol Biol. 2012 May;130(1-2):96-104. doi: 10.1016/j.jsbmb.2012.01.009. Epub 2012 Feb 10.
DNA methylation of the promoter region of estrogen receptor alpha (ESR1) is recognized as an epigenetic mechanism that regulates its mRNA abundance. We questioned whether tissues in male growing piglets were influenced in terms of DNA methylation by the developmentally occurring distinct plasma estradiol-17β (E2) concentrations. Additionally, we aimed at broadening the currently limited understanding of the epigenetic regulation of ESR1 in physiological settings. Three distinct genetic regions of ESR1 were analyzed using a combination of methylation-sensitive high resolution melting (MS-HRM) and pyrosequencing. Unexpectedly, major E2 concentration differences were only marginally associated with minor variations in DNA methylation and mRNA abundance. However, by analyzing two tissues showing the greatest differences in transcript abundance, we were able to find one single CpG site in the +1kb intragenic region of ESR1 strikingly differently methylated between heart vs. epididymis. Interestingly, this single CpG-site was identified as a putative binding site for the transcriptional repressor TG-interacting factor 1 (TGIF) which can recruit histone deacetylase 1 (HDAC1) leading to chromatin condensation. Indeed, chromatin immunoprecipitation confirmed a reduced histone H3 presence at the specific ESR1 location in case of higher DNA methylation. We therefore hypothesize that ESR1 expression may be manifested by a single-CpG-site based methylation difference impairing transcription factor binding.
雌激素受体 alpha（ESR1）启动子区域的 DNA 甲基化被认为是一种调节其 mRNA 丰度的表观遗传机制。我们质疑在雄性生长仔猪中，发育过程中出现的不同血浆雌二醇-17β（E2）浓度是否会影响组织的 DNA 甲基化。此外，我们旨在拓宽目前对生理环境中 ESR1 表观遗传调控的有限认识。使用甲基化敏感高分辨率熔解（MS-HRM）和焦磷酸测序相结合的方法分析了 ESR1 的三个不同遗传区域。出乎意料的是，E2 浓度的主要差异与 DNA 甲基化和 mRNA 丰度的微小变化只有轻微关联。然而，通过分析转录本丰度差异最大的两种组织，我们能够在 ESR1 的+1kb 基因内区域发现一个单 CpG 位点，其在心脏与附睾之间的甲基化程度明显不同。有趣的是，这个单 CpG 位点被鉴定为转录抑制因子 TG 相互作用因子 1（TGIF）的一个潜在结合位点，TGIF 可以募集组蛋白去乙酰化酶 1（HDAC1），导致染色质浓缩。实际上，染色质免疫沉淀证实，在特定 ESR1 位置的组蛋白 H3 存在减少，而在 DNA 甲基化程度较高的情况下。因此，我们假设 ESR1 的表达可能通过单个 CpG 位点的甲基化差异来表现，从而影响转录因子的结合。
