Transcriptome analysis of Brg1 deficient small intestinal epithelium in the context of normal and aberrant Wnt signalling

Brg1 has been reported to act as a trans-activator for the Wnt pathway by interacting with beta-catenin. Given this interaction and the crucial role Wnt signalling plays in the intestinal homeostasis, we aimed to investigate the effect of Brg1 loss on gene expression in normal and Wnt activated small intestinal epithelium. We used VillinCreERT2 Cre recombinase and loxP targeted allels of Brg1 and Apc to generate 4 cohorts of conditional knock-out mice: Cre-negative controls (n=4), Brg1 deficient (n=4), Apc deficient (n=3) and double Brg1-Apc deficient (n=4). All mice were induced by 4x80mg/kg daily injections of Tamoxifen. Epithelium enriched (gut scrapes) samples of small intestine (jejunum) were collected at day 4 post induction. Loss of Brg1 expression in the small intestinal epithelium at this time point was confirmed by immunohistochemistry.

已有研究表明，Brg1可通过与β-连环蛋白（beta-catenin）相互作用，作为Wnt信号通路（Wnt pathway）的反式激活因子。鉴于二者的相互作用，以及Wnt信号在肠道稳态中发挥的关键作用，本研究旨在探究Brg1缺失对正常及Wnt激活的小肠上皮基因表达的影响。我们使用VillinCreERT2重组酶（Cre recombinase）系统，以及Brg1与Apc的loxP靶向等位基因，构建了4组条件性基因敲除小鼠：Cre阴性对照组（n=4）、Brg1缺陷型小鼠（n=4）、Apc缺陷型小鼠（n=3）以及Brg1-Apc双缺陷型小鼠（n=4）。所有小鼠均通过每日注射他莫昔芬（Tamoxifen）进行诱导，给药剂量为80mg/kg，连续给药4次。于诱导后第4天，收集小肠（空肠（jejunum））的肠上皮富集样本（肠道刮取物，gut scrapes）。本研究通过免疫组织化学（immunohistochemistry）验证，该时间点小肠上皮中Brg1的表达已发生缺失。