cis-Acting elements and transcription factors involved in the intestinal specific expression of the rat calbindin-D9k gene. Binding of the intestine-specific transcription factor Cdx-2 to the TATA box

摘要: The calbindin-D9K (CaBP9k) gene is mainly expressed in differentiated duodenal epithelial cells and used as a model for studying the molecular mechanisms of intestine-specific transcription. has been cloned, two major DNase-I-hypersensitive sites duodenum have described, vitamin-D-response element identified. We now analysed transcription factors regulatory sequences involved CaBP9k intestine ex vivo vitro experiments. Transfection experiments intestinal (CaCo-2) non-intestinal (HeLa) cell lines defined regions 5'-flanking rat gene. A minimal proximal region (-117 to +20) promoted both expressing non-expressing lines. Tissue specificity was conferred by situated further upstream, which are responsible complete repression cells. Intestinal specified region, containing specialized TATA box, distal contains previously described site. In DNase I footprinting, electrophoretic mobility shift assays antibody supershift were examine bound promoter (-800 +80 bp). Rat nuclear extracts protected 12 sites. Some them appear be binding ubiquitous (nuclear factor 1) or hepatic-enriched (hepatocyte 1 4, enhancer protein alpha beta factors. DNA studies transfection indicated that an factor, caudal homeobox-2, binds box These data contribute our understanding control demonstrate several trans-acting factors, other than vitamin D receptor, may expression.