The oxysterol sulfate, 25-hydroxycholesterol 3-sulfate (25HC3S), has been shown to play an important role in lipid metabolism, inflammatory response, and cell survival. However, the mechanism(s) of its function in global regulation is unknown. The current study investigates the molecular mechanism by which 25HC3S functions as an endogenous epigenetic regulator. To study the effects of oxysterols/sterol sulfates on epigenetic modulators, twelve recombinant epigenetic enzymes were used to determine whether 25HC3S acts as their endogenous ligand. The enzyme kinetic study demonstrated that 25HC3S specifically inhibited DNA methyltransferases, DNMT1, DNMT3a, and DNMT3b with IC50= 4.04, 3.03, and 9.05 x 10^-6 M, respectively. In human hepatocytes, high glucose induces lipid accumulation by increasing promoter CpG methylation of key genes involved in development of non-alcoholic fatty liver diseases (NAFLD). Using this model, whole genome bisulfate sequencing (WGBS) analysis demonstrated that 25HC3S converts the ^5mCpG to CpG in the promoter regions of 1074 genes. Additionally, we observed increased expression of the demethylated genes, which are involved in the master signaling pathways, including MAPK-ERK, calcium-AMPK, and type II diabetes mellitus pathways. Messenger RNA array analysis showed that the upregulated genes encoded for key elements of cell survival; conversely, downregulated genes encoded for key enzymes that decrease lipid biosynthesis. Taken together, our results indicate that the expression of these key elements and enzymes are regulated by the demethylated signaling pathways, and that 25HC3S DNA demethylation of ^5mCpG in promoter regions is a potent regulatory mechanism.

中文翻译：

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25-hydroxycholesterol 3-sulfate 是肝细胞中 DNA 甲基转移酶的内源性配体。

氧甾醇硫酸盐、25-羟基胆固醇 3-硫酸盐 (25HC3S) 已被证明在脂质代谢、炎症反应和细胞存活中发挥重要作用。然而，其在全球监管中的作用机制尚不清楚。目前的研究调查了 25HC3S 作为内源性表观遗传调节剂发挥作用的分子机制。为了研究氧甾醇/硫酸甾醇对表观遗传调节剂的影响，使用了 12 种重组表观遗传酶来确定 25HC3S 是否充当其内源配体。酶动力学研究表明，25HC3S 特异性抑制 DNA 甲基转移酶、DNMT1、DNMT3a 和 DNMT3b，IC50= 4.04、3.03 和 9.05 x 10 ^-6M，分别。在人类肝细胞中，高葡萄糖通过增加参与非酒精性脂肪肝疾病 (NAFLD) 发展的关键基因的启动子 CpG 甲基化来诱导脂质积累。使用该模型，全基因组硫酸氢盐测序 (WGBS) 分析表明 25HC3S 将^5mCpG 到 CpG 在 1074 个基因的启动子区域。此外，我们观察到去甲基化基因的表达增加，这些基因参与主要信号通路，包括 MAPK-ERK、钙-AMPK 和 II 型糖尿病通路。信使 RNA 阵列分析表明，上调的基因编码了细胞存活的关键要素；相反，编码减少脂质生物合成的关键酶的基因下调。总之，我们的结果表明这些关键元件和酶的表达受去甲基化信号通路的调节，启动子区域^{5m CpG 的 25HC3S DNA 去甲基化是一种有效的调节机制。}