Barrett's esophagus (BE) and gastric intestinal metaplasia are related premalignant conditions in which areas of human stomach epithelium express mixed gastric and intestinal features. Intestinal transcription factors (TFs) are expressed in both conditions, with unclear causal roles and cis-regulatory mechanisms. Ectopic CDX2 reprogrammed isogenic mouse stomach organoid lines to a hybrid stomach–intestinal state transcriptionally similar to clinical metaplasia; squamous esophageal organoids resisted this CDX2-mediated effect. Reprogramming was associated with induced activity at thousands of previously inaccessible intestine-restricted enhancers, where CDX2 occupied DNA directly. HNF4A, a TF recently implicated in BE pathogenesis, induced weaker intestinalization by binding a novel shadow Cdx2 enhancer and hence activating Cdx2 expression. CRISPR/Cas9-mediated germline deletion of that cis-element demonstrated its requirement in Cdx2 induction and in the resulting activation of intestinal genes in stomach cells. dCas9-conjugated KRAB repression mapped this activity to the shadow enhancer's HNF4A binding site. Altogether, we show extensive but selective recruitment of intestinal enhancers by CDX2 in gastric cells and that HNF4A-mediated ectopic CDX2 expression in the stomach occurs through a conserved shadow cis-element. These findings identify mechanisms for TF-driven intestinal metaplasia and a likely pathogenic TF hierarchy.

中文翻译：

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转录因子介导的肠化生和阴影增强剂的作用

巴雷特食管 (BE) 和胃肠上皮化生是相关的癌前病变，其中人胃上皮区域表现出混合的胃和肠特征。肠道转录因子 (TF) 在两种情况下均有表达，其因果作用和顺式调节机制尚不清楚。异位 CDX2 将同基因小鼠胃类器官系重编程为与临床化生转录相似的混合胃-肠状态；鳞状食管类器官抵抗这种 CDX2 介导的作用。重编程与数千个以前无法进入的肠道限制增强子的诱导活性有关，其中 CDX2 直接占据 DNA。HNF4A，一种最近与 BE 发病机制有关的 TF，通过结合一种新的阴影Cdx2诱导较弱的肠道化增强子，从而激活Cdx2表达。CRISPR/Cas9 介导的该cis元件的种系缺失证明了它在Cdx2诱导和由此产生的胃细胞中肠道基因激活中的需要。dCas9 共轭 KRAB 抑制将此活动映射到阴影增强剂的 HNF4A 结合位点。总而言之，我们展示了 CDX2 在胃细胞中广泛但选择性地募集肠道增强剂，并且 HNF4A 介导的胃中异位 CDX2 表达通过保守的影子顺式元件发生。这些发现确定了 TF 驱动的肠化生的机制和可能的致病性 TF 等级。