哺乳动物肠上皮屏障中非编码RNAs的调控作用

哺乳动物肠上皮是一种拥有快速自我更新能力的组织,在维持机体免疫稳态与肠道应激后的损伤修复中发挥重要作用。源于隐窝底部的多能肠干细胞不断进行增殖、迁移与分化,并沿隐窝 绒毛轴向上移动,从而维持肠上皮完整性。该过程受严格而复杂的基因调控网络参与。越来越多的数据表明,肠上皮完整性受到广泛的非编码RNA的调控,主要包括肠黏膜再生、保护与上皮屏障功能等方面。本文重点讨论了两类非编码RNA(包括microRNAs和lncRNAs)转录后调控肠上皮屏障功能的研究进展。其中,miR-503、miR-146和lnc-uc.173、lnc-SPRY4-IT1、lnc-plncRNA1、lnc-Gata6等,能够促进肠黏膜的更新,增强上皮屏障功能;相反,miR-222、miR-29b、miR-195和lnc-H19与lnc-BC012900等,抑制肠上皮再生并破坏肠上皮屏障功能。miRNAs、mRNAs与lncRNAs间构成复杂的分子网络,共同调控肠上皮稳态。深入研究与肠上皮相关的miRNAs和IncRNAs分子及其作用机制,探寻引起肠黏膜炎症的关键分子靶标,为肠道炎症临床诊治提供新方向与新方法。     

RNA结合蛋白HuR对肠道上皮稳态的转录后调控（英文）

哺乳动物的肠上皮组织具备快速和强大的自我更新能力,以适应与肠内容物中众多有害物质和微生物的直接接触。基因的转录后调控是肠上皮组织维持稳态的重要机制之一。RNA结合蛋白HuR在细胞中的主要功能是调节靶向基因转录本的稳定性和翻译,密切参与肠道黏膜病理生理调节。本综述将重点介绍HuR在维持肠上皮完整性方面的生物学作用,尤其是HuR在调节肠上皮细胞更新、肠道黏膜修复以及肠壁通透性方面的最新发现和研究进展;并深入分析HuR与其它RNA结合蛋白以及非编码RNA (包含微小RNA和长链非编码RNA)之间的相互作用在肠上皮稳态调节中的共同作用。随着RNA结合蛋白和非编码RNA研究领域的不断深入,肠上皮组织稳态的转录后调控将为如何在特定病理条件下保护肠上皮的治疗提供新的线索。     

肠道菌群影响黏膜屏障结构与功能的研究进展

肠道黏膜屏障具有防止致病性抗原侵入、维护肠道健康的功能。而肠道菌群是肠道黏膜屏障的重要构成部分,肠道菌群失调会导致肠道黏膜屏障的损伤,引起炎性肠病、肠易激综合征及肝、肾等多种疾病的发生发展。因此,本文从肠道黏膜的结构与功能及肠道菌群对其的影响等方面归纳总结肠道菌群对屏障系统的调控作用,从调节肠道微生态平衡、促进黏液分泌、影响紧密连接和肠道上皮通透性、激发肠黏膜免疫、调控肠上皮凋亡、影响肠上皮DNA稳定性及产生特殊代谢产物等方面阐述其作用机制,为临床胃肠道疾病及其并发症的治疗提供新的思路和方法。     

肠上皮干细胞研究进展

肠上皮是人体更新最快的组织,位于其底部隐窝结构中的干细胞是它快速更新的驱动力所在.Lgr5+细胞是最主要的肠上皮干细胞类群,它可以分化产生所有的肠上皮细胞类群.Lgr5+肠干细胞的命运受Wnt,BMP,Notch,EGF和Hippo等生长发育信号通路的调控,以及肠道微生物和人体代谢水平的影响.肠上皮干细胞的稳态维持与肠道疾病发生紧密相关,其功能缺失会引起消化吸收功能下降、炎症发生,而其过度激活导致的增生又会诱发肿瘤,形成结直肠癌.对肠上皮干细胞的研究既可以加深对于肠上皮快速更新机制的了解,又可以为治疗结直肠癌等肠道疾病提供新的启示.     

防御素在肠黏膜屏障功能中的作用

肠黏膜不仅有消化和吸收功能,而且还具有重要的防御性屏障功能,它可以使机体的内环境保持相对稳定以维持机体的正常生命活动。当肠黏膜屏障受到损伤时,肠道中的微生物和毒素会突破肠黏膜屏障,进入门静脉和淋巴系统从而引起细菌移位,甚至发展为全身性的炎症反应综合征（systemic inflammatory response syndrome,SIRS）以及多器官功能衰竭综合征（multiple organs defic iency syndrome,MODS）。     

肠黏膜屏障与肠道菌群的相互关系

摘要：人类肠道中微生物群与肠道环境相互作用以维持机体健康。肠黏膜屏障主要由黏液层、肠道菌群、肠道免疫系统和肠上皮细胞本身的完整性等构成。肠道作为直接与大量菌群接触的器官,其屏障功能在肠道健康中的作用尤为显著。肠道菌群与肠道屏障相互作用,保持肠道菌群与肠道屏障相对稳定,肠道菌群参与肠道免疫反应的建立,共同建立机体天然防御系统,在保持肠道免疫的动态平衡中具有重要作用。当两者之间的平衡被打破时,可诱发功能性胃肠病（如肠易激综合征）及免疫相关性疾病（如炎症性肠病）。本文主要阐述肠黏膜屏障与肠道菌群之间的相互关系以及与肠道屏障功能障碍相关的肠道疾病。     

肠上皮与肠道微生物相互作用研究进展

肠道不仅是消化和吸收的主要场所,也是机体重要的免疫器官。人类肠道中存在着超过百万亿的微生物,其在漫长的自然选择及共同进化中与宿主形成了紧密的共生关系。肠上皮是先天免疫的一个组成部分,通过各种黏膜保护屏障将肠腔内容物与机体内环境分隔开。各种肠上皮细胞相互协调维持肠道内稳态,并与肠道微生物、肠黏膜免疫系统共同形成抵御肠腔内有害抗原的第一道防线。肠上皮作为肠道微生物和肠黏膜免疫系统相互作用的枢纽,在黏膜免疫防御体系中具有重要作用,本文就肠上皮与肠道微生物之间的相互作用进行综述,旨在深入理解肠上皮,为探索肠道相关疾病的治疗提供新思路。     

综述与专论: 肠神经胶质细胞在维持肠黏膜稳态与调控炎症中的作用

肠神经胶质细胞分布于消化道黏膜层、黏膜下层和肌层,其具有广泛的异质性和可塑性。黏膜层最靠近肠腔,易受病原体侵袭和炎症影响,因此黏膜稳态备受关注。肠黏膜神经胶质细胞（mucosal enteric glial cells,mEGCs）与肠上皮细胞、血管内皮细胞、免疫细胞等非神经元细胞具有复杂的相互作用关系。从结构和功能的角度来看,mEGCs可能处于中心调控位置。最近研究不断揭示mEGCs的亚型和新功能,表明mEGCs在病理条件下存在功能改变。了解mEGCs如何引起黏膜功能障碍及其在疾病发展中的作用至关重要。本文将总结mEGCs在维持粘膜内环境稳定和调节炎症方面的作用。     

潘氏细胞在肠道稳态中的作用

肠道稳态对维持肠道正常生理功能具有重要意义。位于肠道上皮隐窝的潘氏细胞是肠道上皮屏障的重要组成部分,它们分泌大量生物效应分子,为小肠干细胞提供小生境以及调控肠道菌群。炎症性肠炎克罗恩病经常伴随潘氏细胞功能异常,Nod2、Xbp-1、Atg16L1、KCNN4等克罗恩病的易感基因在潘氏细胞中高表达,并调控潘氏细胞的重要生理活动。对潘氏细胞的研究有望揭示维持肠道稳态的生理机制,攻克炎症性肠炎等疾病的难关。     

肠道黏膜受损及保护机制的研究进展

正常肠道屏障功能依赖于肠黏膜上皮屏障,肠道免疫系统以及肠道的正常微生物的平衡。一些常见肠道疾病是通过破坏肠道黏膜的正常结构和功能,导致其病理和生理的变化而发病。本文就肠道黏膜的受损及保护机制作一综述。     

Intestinal epithelial cells related lncRNA and mRNA expression profiles in dextran sulphate sodium-induced colitis

Intestinal epithelial barrier damage caused by intestinal epithelial cells (IECs) dysfunction plays a crucial role in the pathogenesis and development of inflammatory bowel disease (IBD). Recently, some studies have suggested the emerging role of long non-coding RNAs (lncRNAs) in IBD. The aim of this study was to reveal lncRNAs and mRNA expression profiles in IECs from a mouse model of colitis and to expand our understanding in the intestinal epithelial barrier regulation. IECs from the colons of wild-type mice and dextran sulphate sodium (DSS)-induced mice were isolated for high-throughput RNA-sequencing. A total of 254 up-regulated and 1013 down-regulated mRNAs and 542 up-regulated and 766 down-regulated lncRNAs were detected in the DSS group compared with the Control group. Four mRNAs and six lncRNAs were validated by real-time quantitative PCR. Function analysis showed that dysregulated mRNAs participated in TLR7 signalling pathway, IL-1 receptor activity, BMP receptor binding and IL-17 signalling pathway. Furthermore, the possibility of indirect interactions between differentially expressed mRNAs and lncRNAs was illustrated by the competing endogenous RNA (ceRNA) network. LncRNA ENSMUST00000128026 was predicted to bind to mmu-miR-6899-3p, regulating Dnmbp expression. LncRNA NONMMUT143162.1 was predicted to competitively bind to mmu-miR-6899-3p, regulating Tnip3 expression. Finally, the protein-protein interaction (PPI) network analysis was constructed with 311 nodes and 563 edges. And the highest connectivity degrees were Mmp9, Fpr2 and Ccl3. These results provide novel insights into the functions of lncRNAs and mRNAs involved in the regulation of the intestinal epithelial barrier.     

Modulation of stem cell fate in intestinal homeostasis,injury and repair

The mammalian intestinal epithelium constitutes the largest barrier against the external environment and makes flexible responses to various types of stimuli. Epithelial cells are fast-renewed to counteract constant damage and disrupted barrier function to maintain their integrity. The homeostatic repair and regeneration of the intestinal epithelium are governed by the Lgr5⁺ intestinal stem cells (ISCs) located at the base of crypts, which fuel rapid renewal and give rise to the different epithelial cell types. Protracted biological and physicochemical stress may challenge epithelial integrity and the function of ISCs. The field of ISCs is thus of interest for complete mucosal healing, given its relevance to diseases of intestinal injury and inflammation such as inflammatory bowel diseases. Here, we review the current understanding of the signals and mechanisms that control homeostasis and regeneration of the intestinal epithelium. We focus on recent insights into the intrinsic and extrinsic elements involved in the process of intestinal homeostasis, injury, and repair, which fine-tune the balance between self-renewal and cell fate specification in ISCs. Deciphering the regulatory machinery that modulates stem cell fate would aid in the development of novel therapeutics that facilitate mucosal healing and restore epithelial barrier function.     

MicroRNA-193a-3p Reduces Intestinal Inflammation in Response to Microbiota via Down-regulation of Colonic PepT1

Intestinal inflammation is characterized by epithelial disruption, leading to the loss of barrier function, recruitment of immune cells, and host immune responses to gut microbiota. PepT1, a di/tripeptide transporter that uptakes bacterial products, is up-regulated in inflamed colon tissue, which implies its role in bacterium-associated intestinal inflammation. Although microRNA (miRNA)-mediated gene regulation has been found to be involved in various processes of inflammatory bowel disease (IBD), the biological function of miRNAs in the pathogenesis of IBD remains to be explored. In this study we detected miRNA expression patterns in colon tissues during colitis and investigated the mechanism underlying the regulation of colonic PepT1 by miRNAs. We observed an inverse correlation between PepT1 and miR-193a-3p in inflamed colon tissues with active ulcerative colitis, and we further demonstrated that miR-193a-3p reduced PepT1 expression and activity as a target gene and subsequently suppressed the NF-κB pathway. Intracolonic delivery of miR-193a-3p significantly ameliorated dextran sodium sulfate-induced colitis, whereas the overexpression of colonic PepT1 via PepT1 3′-untranslated region mutant lentivirus vector abolished the anti-inflammatory effect of miR-193a-3p. Furthermore, antibiotic treatment eliminated the difference in the dextran sodium sulfate-induced inflammation between the presence and absence of miR-193a-3p. These findings suggest that miR-193a-3p regulation of PepT1 mediates the uptake of bacterial products and is a potent mechanism during the colonic inflammation process. Overall, we believe miR-193a-3p may be a potent regulator of colonic PepT1 for maintaining intestinal homeostasis.     

肿瘤发生过程中miRNA与lncRNA的相互作用

非编码RNA(non-coding RNA,ncRNA)是生物体内普遍存在,且对生命活动具有重要调控作用的生物分子.以微RNA（microRNA,miRNA）和长链非编码RNA（long non coding RNA,lncRNA）为代表的ncRNA分子在肿瘤发生和发展过程中都有重要的作用.越来越多研究发现,miRNA和lncRNA之间的关系是非常密切的,某些lncRNA(如H19和BIC)可以作为miRNA的前体,通过加工成miRNA而发挥作用.有些miRNA通过作用于lncRNA影响肿瘤的发生(如：miR-129与MEG3,let-7与H19);同样地,有些lncRNA通过作用于miRNA影响肿瘤的发生(如：HULC与miR-372,PTCSC3与miR-574-5p,ciRS-7与miR-7,Sry与miR-138).miRNA与lncRNA之间既可以直接相互作用,也可以通过其它分子（特别是蛋白质或蛋白质复合物）间接地影响着肿瘤的发生和发展.揭示miRNA和lncRNA相互作用在肿瘤发生中的作用可以为肿瘤的诊断和治疗提供新思路.     

长链非编码RNA的微RNA海绵作用与呼吸系统疾病

长链非编码RNA（long non-coding RNAs, lncRNAs）是一类由长度大于200个核苷酸组成的长链非编码序列。lncRNAs具有较长的序列,使得lncRNAs具有复杂的二级及三级结构,这也是lncRNAs结合DNA、RNA和蛋白质及其行使复杂功能的结构基础。MicroRNA（miRNAs)是长度在19到25个核苷酸之间的非编码单链RNA分子,是目前研究最多的小分子非编码RNA。而lncRNAs通过结合或者螯合miRNA来调节miRNA丰度,发挥lncRNA的“海绵”作用,从而调控一系列的病理生理过程。lncRNAs及miRNA在呼吸系统疾病的发生、发展、治疗和预后起重要作用。本文就lncRNAs及其“海绵”作用对呼吸系统疾病的影响及可能的机制进行综述。     

LncRNA DANCR improves the dysfunction of the intestinal barrier and alleviates epithelial injury by targeting the miR-1306-5p/PLK1 axis in sepsis

Intestinal barrier dysfunction often occurs in various acute or chronic pathological conditions and has been identified as an important clinical problem. Herein, we explored the biological role and molecular mechanism of Polo-like kinase 1 (PLK1) and differentiation antagonizing non-protein coding RNA (DANCR) in intestinal barrier dysfunction caused by sepsis. RT-qPCR analysis was used to examine PLK1, miR-1306-5p, and DANCR expression in NCM460 cells after LPS treatment. TUNEL assay and Western blot analysis were performed to explore PLK1 function in cell apoptosis and intestinal barrier in vitro. Hematoxylin and eosin staining, Western blot analysis, and TUNEL assay were used to investigate DANCR function in the intestinal barrier and cell apoptosis in vivo. The interaction between miR-1306-5p and PLK1 (or DANCR) was validated by luciferase reporter assay. As a result, PLK1 overexpression decreased cell apoptosis and promoted intestinal barrier function. Moreover, DANCR was validated as a sponge of miR-1306-5p to target PLK1. In addition, we found that DANCR overexpression decreased intestinal mucosal permeability and colon mucosa epithelial cell apoptosis in vivo. Conclusively, DANCR improved intestinal barrier dysfunction and alleviated epithelial injury by targeting the miR-1306-5p/PLK1 axis in sepsis.     

Long noncoding RNA SPRY4-IT1 regulates intestinal epithelial barrier function by modulating the expression levels of tight junction proteins

Epithelial cells line the intestinal mucosa and form an important barrier to a wide array of noxious substances in the lumen. Disruption of the barrier integrity occurs commonly in various pathologies. Long noncoding RNAs (lncRNAs) control diverse biological processes, but little is known about the role of lncRNAs in regulation of the gut permeability. Here we show that the lncRNA SPRY4-IT1 regulates the intestinal epithelial barrier function by altering expression of tight junction (TJ) proteins. SPRY4-IT1 silencing led to dysfunction of the epithelial barrier in cultured cells by decreasing the stability of mRNAs encoding TJ proteins claudin-1, claudin-3, occludin, and JAM-1 and repressing their translation. In contrast, increasing the levels of SPRY4-IT1 in the intestinal mucosa protected the gut barrier in mice exposed to septic stress by increasing the abundance of TJ proteins. SPRY4-IT1 directly interacted with TJ mRNAs, and this process was enhanced through the association with the RNA-binding protein HuR. Of interest, the intestinal mucosa from patients with increased gut permeability exhibited a decrease in the levels of SPRY4-IT1. These findings highlight a novel role for SPRY4-IT1 in controlling the intestinal epithelial barrier and define a mechanism by which SPRY4-IT1 modulates TJ expression by altering the stability and translation of TJ mRNAs.     

Transgenic Expression of miR-222 Disrupts Intestinal Epithelial Regeneration by Targeting Multiple Genes Including Frizzled-7

Defects in intestinal epithelial integrity occur commonly in various pathologies. miR-222 is implicated in many aspects of cellular function and plays an important role in several diseases, but its exact biological function in the intestinal epithelium is underexplored. We generated mice with intestinal epithelial tissue-specific overexpression of miR-222 to investigate the function of miR-222 in intestinal physiology and diseases in vivo. Transgenic expression of miR-222 inhibited mucosal growth and increased susceptibility to apoptosis in the small intestine, thus leading to mucosal atrophy. The miR-222–elevated intestinal epithelium was vulnerable to pathological stress, since local overexpression of miR-222 not only delayed mucosal repair after ischemia/reperfusion-induced injury, but also exacerbated gut barrier dysfunction induced by exposure to cecal ligation and puncture. miR-222 overexpression also decreased expression of the Wnt receptor Frizzled-7 (FZD7), cyclin-dependent kinase 4 and tight junctions in the mucosal tissue. Mechanistically, we identified the Fzd7 messenger ribonucleic acid (mRNA) as a novel target of miR-222 and found that [miR-222/Fzd7 mRNA] association repressed Fzd7 mRNA translation. These results implicate miR-222 as a negative regulator of normal intestinal epithelial regeneration and protection by downregulating expression of multiple genes including the Fzd7. Our findings also suggest a novel role of increased miR-222 in the pathogenesis of mucosal growth inhibition, delayed healing and barrier dysfunction.     

Innate immune signalling at the intestinal epithelium in homeostasis and disease

The intestinal epithelium-which constitutes the interface between the enteric microbiota and host tissues-actively contributes to the maintenance of mucosal homeostasis and defends against pathogenic microbes. The recognition of conserved microbial products by cytosolic or transmembrane pattern recognition receptors in epithelial cells initiates signal transduction and influences effector cell function. However, the signalling pathways, effector molecules and regulatory mechanisms involved are not yet fully understood, and the functional outcome is poorly defined. This review analyses the complex and dynamic role of intestinal epithelial innate immune recognition and signalling, on the basis of results in intestinal epithelial cell-specific transgene or gene-deficient animals. This approach identifies specific epithelial cell functions within the diverse cellular composition of the mucosal tissue, in the presence of the complex and dynamic gut microbiota. These insights have thus provided a more comprehensive understanding of the role of the intestinal epithelium in innate immunity during homeostasis and disease.