Department of Neurology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing 100700, PR China.
Department of Gastroenterology, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing 100700, PR China.
Cell Signal. 2020 Sep;73:109674. doi: 10.1016/j.cellsig.2020.109674. Epub 2020 May 21.
Diarrhea-predominant irritable bowel syndrome (IBS-D) is a prevalent gastrointestinal disorder with a high incidence in children. The role of long non-coding RNAs (lncRNAs) in gastrointestinal diseases has been previously highlighted. Nevertheless, the underlying regulatory mechanism of lncRNA X inactivate-specific transcript (XIST) in IBS-D requires further studies. Thus, the present study was conducted with the main objective of elucidating the underlying mechanism of lncRNA XIST in visceral hypersensitivity in IBS-D. An in vivo mouse model of IBS-D was constructed via rectal perfusion of acetic acid. Next, in order to evaluate the effect of lncRNA XIST on the development of visceral hypersensitivity in IBS-D, different vector plasmids were injected into mice along with rectal mucosal epithelial cells, followed by the measurement of abdominal withdrawal reflex (AWR) score, counts of peristaltic wave, abdominal wall contraction and defecation particles. Furthermore, luciferase reporter assay, FISH, RIP and ChIP assays were conducted to determine the interactions between lncRNA XIST and SERT. Subsequently, MS-PCR was adopted to test the methylation level of SERT promoter. 5-hydroxytrytophan (HT) content in rectal tissues was detected using immunohistochemistry. The IBS-D mouse models presented with a high expression of lncRNA XIST along with low expression of SERT. LncRNA XIST was observed to recruit methylase DNMT1, DNMT3A and DNMT3B to promote SERT promoter methylation, reducing its expression. Restoration of lncRNA XIST resulted in increased AWR score, counts of peristaltic wave, abdominal wall contraction and defecation particles along with stimulated 5-HT expression and SERT methylation level, while downregulation of lncRNA XIST reversed these effects. In conclusion, the key findings from our study indicated that lncRNA XIST acts as a regulator in 5-HT-induced visceral hypersensitivity in mice with IBS-D, providing a new insight into the regulatory effect of lncRNA XIST and its epigenetic diagnostic and therapeutic properties in IBS-D.
腹泻型肠易激综合征（IBS-D）是一种常见的胃肠道疾病，在儿童中的发病率较高。长链非编码 RNA（lncRNA）在胃肠道疾病中的作用已被先前强调。然而，lncRNA X 灭活特异性转录物（XIST）在 IBS-D 中的潜在调节机制仍需要进一步研究。因此，本研究的主要目的是阐明 lncRNA XIST 在 IBS-D 内脏敏感性中的潜在机制。通过直肠灌注乙酸构建 IBS-D 的体内小鼠模型。接下来，为了评估 lncRNA XIST 对 IBS-D 内脏敏感性发展的影响，将不同的载体质粒与直肠黏膜上皮细胞一起注入小鼠体内，然后测量腹壁反射（AWR）评分、蠕动波计数、腹壁收缩和排便颗粒数。此外，进行了荧光素酶报告基因测定、FISH、RIP 和 ChIP 测定以确定 lncRNA XIST 和 SERT 之间的相互作用。随后，采用 MS-PCR 测试 SERT 启动子的甲基化水平。通过免疫组织化学检测直肠组织中的 5-羟色氨酸（HT）含量。IBS-D 小鼠模型表现出高表达的 lncRNA XIST 伴随着低表达的 SERT。观察到 lncRNA XIST 招募甲基转移酶 DNMT1、DNMT3A 和 DNMT3B 以促进 SERT 启动子甲基化，降低其表达。lncRNA XIST 的恢复导致 AWR 评分、蠕动波计数、腹壁收缩和排便颗粒增加以及刺激 5-HT 表达和 SERT 甲基化水平增加，而 lncRNA XIST 的下调则逆转了这些效应。总之，本研究的关键发现表明，lncRNA XIST 作为 5-HT 诱导的 IBS-D 小鼠内脏敏感性的调节剂发挥作用，为 lncRNA XIST 的调节作用及其在 IBS-D 中的表观遗传诊断和治疗特性提供了新的见解。
