Control of differentiation-induced calbindin-D9k gene expression in Caco-2 cells by cdx-2 and HNF-1alpha.
Control of differentiation-induced calbindin-D9k gene expression in Caco-2 cells by cdx-2 and HNF-1alpha.
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cdx-2 和 HNF-1alpha 控制 Caco-2 细胞中分化诱导的 calbindin-D9k 基因表达。
DOI：
10.1152/ajpgi.00121.2004
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Fleet,JamesC
中科院分区：
文献类型：
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作者：
Wang,Liyong;Klopot,Anna;Freund,Jean-Noel;Dowling,LaurenN;Krasinski,StephenD;Fleet,JamesC
钙结合蛋白D9 k（CaBP）对于肠钙吸收至关重要;其在体内的表达限于小肠的分化的肠细胞。我们的目标是确定控制该基因在人类肠道中转录调控的因素。在Caco-2克隆TC 7中，天然基因和4600 bp启动子构建体均受到分化的强烈调控（>100倍），但不受1，25（OH）2维生素D处理（<2倍）的调控。缺失突变研究显示，cdx-2（-3158 bp）和肝细胞核因子（HNF）-1（-3131和-98 bp）的保守启动子序列结合在一起控制分化过程中CaBP的表达。其他假定的反应元件在TC 7细胞中对CaBP调节不重要（CCAAT增强子结合蛋白，胰腺十二指肠同源盒-1（pdx-1），近端cdx-2元件）。远端HNF-1位点突变通过破坏HNF-1α结合对CaBP基因表达影响最大;基础和分化介导的CaBP表达均降低80%。与此相反，突变的远端cdx-2元件减少基础CaBP的表达。尽管HNF-1α基因敲除小鼠十二指肠中CaBP mRNA减少60%证实了HNF-1α对CaBP基因调控的生理重要性，但其他研究表明，最大CaBP表达需要HNF-1α和cdx-2的存在。我们的数据表明cdx-2是影响肠上皮细胞基础CaBP表达的一个允许因子，HNF-1α在细胞分化过程中调节CaBP基因表达。
Calbindin D9k(CaBP) is critical for intestinal calcium absorption; its in vivo expression is restricted to differentiated enterocytes of the small intestine. Our goal was to identify factors controlling the transcriptional regulation of this gene in the human intestine. Both the natural gene and a 4600-bp promoter construct were strongly regulated by differentiation (>100-fold) but not by treatment with 1,25(OH)2vitamin D (<2-fold) in the Caco-2 clone TC7. Deletion-mutation studies revealed that conserved promoter sequences for cdx-2 (at −3158 bp) and hepatocyte nuclear factor (HNF)-1 (at −3131 and at −98 bp) combined to control CaBP expression during differentiation. Other putative response elements were not important for CaBP regulation in TC7 cells (CCAAT enhancer binding protein, pancreatic duodenal homebox-1 (pdx-1), a proximal cdx-2 element). Mutation of the distal HNF-1 site had the greatest impact on CaBP gene expression through disruption of HNF-1α binding; both basal and differentiation-mediated CaBP expression was reduced by 80%. In contrast, mutation of the distal cdx-2 element reduced only basal CaBP expression. Whereas a 60% reduction of CaBP mRNA in the duodenum of HNF-1α null mice confirmed the physiological importance of HNF-1α for CaBP gene regulation, additional studies showed that maximal CaBP expression requires the presence of both HNF-1α and cdx-2. Our data suggest that cdx-2 is a permissive factor that influences basal CaBP expression in enterocytes and that HNF-1α modulates CaBP gene expression during cellular differentiation.