College of Bioresource Sciences, Nihon University, Fujisawa-shi, Kanagawa 252-0880, Japan
College of Bioresource Sciences, Nihon University, Fujisawa-shi, Kanagawa 252-0880, Japan.
Immunohorizons. 2020 Apr 15;4(4):178-190. doi: 10.4049/immunohorizons.1900086.
A huge number of commensal bacteria inhabit the intestine, which is equipped with the largest immune system in the body. Recently, the regulation of various physiological functions of the host by these bacteria has attracted attention. In this study, the effects of commensal bacteria on gene expression in colonic epithelial cells (CoECs) were investigated with focus on regulation of DNA methylation. RNA sequencing analyses of CoECs from conventional, germ-free, and MyD88 mice indicated that, out of the genes affected by commensal bacteria, those downregulated in a MyD88-independent manner were most frequently observed. Furthermore, when the 5' regions of genes downregulated by commensal bacteria in CoECs were captured using a customized array and immunoprecipitated with the anti-methyl cytosine Ab, a certain population of these genes was found to be highly methylated. Comprehensive analysis of DNA methylation in the 5' regions of genes in CoECs from conventional and germ-free mice upon pull-down assay with methyl-CpG-binding domain protein 2 directly demonstrated that DNA methylation in these regions was influenced by commensal bacteria. Actually, commensal bacteria were shown to control expression of , which encodes a retinoic acid-producing enzyme and plays an important role in the maintenance of intestinal homeostasis via DNA methylation in the overlapping 5' region of and genes in CoECs. Collectively, it can be concluded that regulation of DNA methylation in the 5' regions of a specific population of genes in CoECs acts as a mechanism by which commensal bacteria have physiological effects on the host.
大量共生菌栖息在肠道中，肠道拥有人体最大的免疫系统。最近，这些细菌对宿主各种生理功能的调节引起了人们的关注。在这项研究中，我们关注 DNA 甲基化，研究了共生菌对结肠上皮细胞 (CoEC) 中基因表达的调控作用。对常规、无菌和 MyD88 小鼠的 CoECs 的 RNA 测序分析表明，在受共生菌影响的基因中，以 MyD88 非依赖性方式下调的基因最为常见。此外，当使用定制的阵列捕获受共生菌下调的 CoECs 中基因的 5' 区域，并使用抗甲基胞嘧啶 Ab 进行免疫沉淀时，发现这些基因的某些群体高度甲基化。通过甲基化 CpG 结合域蛋白 2 在 pull-down 测定中对常规和无菌小鼠 CoECs 中 5' 区域基因的 DNA 甲基化进行综合分析，直接证明了这些区域的 DNA 甲基化受共生菌的影响。实际上，共生菌控制了 基因的表达，该基因编码一种产生视黄酸的酶，通过 CoECs 中 基因和 基因重叠 5' 区域的 DNA 甲基化，在维持肠道内稳态方面发挥着重要作用。综上所述，可以得出结论，共生菌对 CoECs 中特定基因群体的 5' 区域 DNA 甲基化的调控作用是其对宿主产生生理影响的一种机制。
