J Park1, S Schulz, S A Waldman. 1. Division of Clinical Pharmacology, Department of Medicine and Biochemistry, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Abstract
BACKGROUND & AIMS: The heat-stable enterotoxin receptor, guanylyl cyclase C, exhibits an intestine-specific pattern of expression. The aim of this study was to identify the transcriptional activator that mediates intestine-specific expression of guanylyl cyclase C. METHODS: Fragments of the promoter were assayed to isolate regions directing intestine-specific gene activation. Deoxyribonuclease I footprinting was used to identify a site of intestine-specific protection. Electrophoretic mobility shift assays (EMSAs) and supershift analyses were used to characterize the protein that bound to the protected site. The protected site was mutated to analyze its role in promoter activity. RESULTS: Reporter gene assays revealed that intestine-specific expression of guanylyl cyclase C is directed by the proximal promoter. Deoxyribonuclease I footprinting identified a specific site in the proximal promoter that exhibited intestine-specific protection. EMSAs and supershift analyses revealed that the transcription factor Cdx2 bound to an intestine-specific site of protection. Mutation of the Cdx2-protected site of the promoter eliminated binding of Cdx2 and reduced reporter gene activity to the level of extraintestinal cells. CONCLUSIONS: These data show that Cdx2 and its consensus-binding site in the promoter are required for intestine-specific expression of the guanylyl cyclase C gene.
BACKGROUND & AIMS: The heat-stable enterotoxin receptor, guanylyl cyclase C, exhibits an intestine-specific pattern of expression. The aim of this study was to identify the transcriptional activator that mediates intestine-specific expression of guanylyl cyclase C. METHODS: Fragments of the promoter were assayed to isolate regions directing intestine-specific gene activation. Deoxyribonuclease I footprinting was used to identify a site of intestine-specific protection. Electrophoretic mobility shift assays (EMSAs) and supershift analyses were used to characterize the protein that bound to the protected site. The protected site was mutated to analyze its role in promoter activity. RESULTS: Reporter gene assays revealed that intestine-specific expression of guanylyl cyclase C is directed by the proximal promoter. Deoxyribonuclease I footprinting identified a specific site in the proximal promoter that exhibited intestine-specific protection. EMSAs and supershift analyses revealed that the transcription factor Cdx2 bound to an intestine-specific site of protection. Mutation of the Cdx2-protected site of the promoter eliminated binding of Cdx2 and reduced reporter gene activity to the level of extraintestinal cells. CONCLUSIONS: These data show that Cdx2 and its consensus-binding site in the promoter are required for intestine-specific expression of the guanylyl cyclase C gene.
Authors: Alan B R Thomson; Laurie Drozdowski; Claudiu Iordache; Ben K A Thomson; Severine Vermeire; M Tom Clandinin; Gary Wild Journal: Dig Dis Sci Date: 2003-08 Impact factor: 3.199
Authors: Alan B R Thomson; Laurie Drozdowski; Claudiu Iordache; Ben K A Thomson; Severine Vermeire; M Tom Clandinin; Gary Wild Journal: Dig Dis Sci Date: 2003-08 Impact factor: 3.199
Authors: Babar Bashir; Dante J Merlino; Jeffrey A Rappaport; Esteban Gnass; Juan P Palazzo; Ying Feng; Eric R Fearon; Adam E Snook; Scott A Waldman Journal: Hum Pathol Date: 2019-02-02 Impact factor: 3.466