Dong Xu-Yang, Wu Mei-Xu, Zhang Hui-Min, Lyu Hong, Qian Jia-Ming, Yang Hong
Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
Gastroenterol Rep (Oxf). 2019 Oct 29;8(1):66-75. doi: 10.1093/gastro/goz038. eCollection 2020 Feb.
Matrix Gla protein (MGP) is a secreted protein contributed to the immunomodulatory functions of mesenchymal stromal cells. Microarray profiling found a significantly higher expression level of the extracellular matrix gene MGP in patients with ulcerative colitis (UC). However, little is known about the role of MGP in UC and its upstream signaling regulation. This study aimed to identify the expression of MGP in UC and its upstream regulator mechanism.
Colonic mucosa biopsies were obtained from patients with UC and healthy controls. DNA microarray profiling was used to explore underlying genes correlating with UC development. Mice were fed with water containing different concentrations of dextran sodium sulfate (DSS) to induce an experimental colitis model. Colonic tissues were collected and evaluated using immunohistochemistry, immunoblot, real-time polymerase chain reaction, and chromatin immunoprecipitation assay. Bioinformatics analysis was performed to identify candidate MGP gene-promoter sequence and transcription-initiation sites. Luciferase-reporter gene assay was conducted to examine the potential transcription factor of MGP gene expression.
The expression of MGP was significantly increased in colonic tissues from UC patients and DSS-induced colitis models, and was positively correlated with disease severity. Bioinformatics analysis showed a conserved binding site for Egr-1 in the upstream region of human MGP gene. The significantly higher level of Egr-1 gene expression was found in UC patients than in healthy controls. The activity of luciferase was significantly enhanced in the Egr-1 expression plasmid co-transfected group than in the control group and was further inhibited when co-transfected with the Egr-1 binding-site mutated MGP promoter.
Up-regulated expression of MGP was found in UC patients and DSS-induced colitis. The expression of MGP can be regulated by Egr-1.
基质γ-羧基谷氨酸蛋白（MGP）是一种分泌蛋白，有助于间充质基质细胞的免疫调节功能。基因芯片分析发现，溃疡性结肠炎（UC）患者细胞外基质基因MGP的表达水平显著升高。然而，关于MGP在UC中的作用及其上游信号调节知之甚少。本研究旨在确定MGP在UC中的表达及其上游调节机制。
从UC患者和健康对照者获取结肠黏膜活检组织。采用DNA芯片分析探索与UC发生相关的潜在基因。给小鼠喂食含不同浓度葡聚糖硫酸钠（DSS）的水以诱导实验性结肠炎模型。收集结肠组织，采用免疫组织化学、免疫印迹、实时聚合酶链反应和染色质免疫沉淀分析进行评估。进行生物信息学分析以鉴定候选MGP基因启动子序列和转录起始位点。进行荧光素酶报告基因检测以检查MGP基因表达的潜在转录因子。
UC患者和DSS诱导的结肠炎模型的结肠组织中MGP表达显著增加，且与疾病严重程度呈正相关。生物信息学分析显示人MGP基因上游区域存在Egr-1的保守结合位点。UC患者中Egr-1基因表达水平显著高于健康对照者。与对照组相比，Egr-1表达质粒共转染组的荧光素酶活性显著增强，而与Egr-1结合位点突变的MGP启动子共转染时荧光素酶活性进一步受到抑制。
在UC患者和DSS诱导的结肠炎中发现MGP表达上调。MGP的表达可受Egr-1调节。
