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Ma L, Jüttner M, Kullak-Ublick GA, Eloranta JJ. Regulation of the gene encoding the intestinal bile acid transporter ASBT by the caudal-type homeobox proteins CDX1 and CDX2. Am J Physiol Gastrointest Liver Physiol 2012; 302:G123-33. [PMID: 22016432 DOI: 10.1152/ajpgi.00102.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The apical sodium-dependent bile acid transporter (ASBT) is expressed abundantly in the ileum and mediates bile acid absorption across the apical membranes. Caudal-type homeobox proteins CDX1 and CDX2 are transcription factors that regulate genes involved in intestinal epithelial differentiation and proliferation. Aberrant expression of both ASBT and CDXs in Barrett's esophagus (BE) prompted us to study, whether the expression of the ASBT gene is regulated by CDXs. Short interfering RNA-mediated knockdown of CDXs resulted in reduced ASBT mRNA expression in intestinal cells. CDXs strongly induced the activity of the ASBT promoter in reporter assays in esophageal and intestinal cells. Nine CDX binding sites were predicted in silico within the ASBT promoter, and binding of CDXs to six of them was verified in vitro and within living cells by electrophoretic mobility shift assays and chromatin immunoprecipitation assays, respectively. RNAs were extracted from esophageal biopsies from 20 BE patients and analyzed by real-time PCR. Correlation with ASBT expression was found for CDX1, CDX2, and HNF-1α in BE biopsies. In conclusion, the human ASBT promoter is activated transcriptionally by CDX1 and CDX2. Our finding provides a possible explanation for the reported observation that ASBT is aberrantly expressed in esophageal metaplasia that also expresses CDX transcription factors.
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Affiliation(s)
- Li Ma
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, Zurich, Switzerland
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Chen H, Fang Y, Tevebaugh W, Orlando RC, Shaheen NJ, Chen X. Molecular mechanisms of Barrett's esophagus. Dig Dis Sci 2011; 56:3405-20. [PMID: 21984436 PMCID: PMC3750118 DOI: 10.1007/s10620-011-1885-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 08/16/2011] [Indexed: 12/11/2022]
Abstract
Barrett's esophagus (BE) is defined as the metaplastic conversion of esophageal squamous epithelium to intestinalized columnar epithelium. As a premalignant lesion of esophageal adenocarcinoma (EAC), BE develops as a result of chronic gastroesophageal reflux disease (GERD). Many studies have been conducted to understand the molecular mechanisms of this disease. This review summarizes recent results involving squamous and intestinal transcription factors, signaling pathways, stromal factors, microRNAs, and other factors in the development of BE. A conceptual framework is proposed to guide future studies. We expect elucidation of the molecular mechanisms of BE to help in the development of improved management of GERD, BE, and EAC.
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Affiliation(s)
- Hao Chen
- Cancer Research Program, JLC-BBRI, North Carolina Central University, Durham, NC 27707, USA
| | - Yu Fang
- Cancer Research Program, JLC-BBRI, North Carolina Central University, Durham, NC 27707, USA
| | - Whitney Tevebaugh
- Cancer Research Program, JLC-BBRI, North Carolina Central University, Durham, NC 27707, USA
| | - Roy C. Orlando
- Center for Esophageal Diseases and Swallowing, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7080, USA
| | - Nicholas J. Shaheen
- Center for Esophageal Diseases and Swallowing, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7080, USA
| | - Xiaoxin Chen
- Cancer Research Program, JLC-BBRI, North Carolina Central University, Durham, NC 27707, USA,Center for Esophageal Diseases and Swallowing, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7080, USA,Corresponding authors: Xiaoxin Luke Chen, MD, PhD, Cancer Research Program, Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707, USA. Tel: 919-530-6425; Fax: 919-530-7780;
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Abstract
Barrett's esophagus is an epithelial metaplasia associated with an increased risk for cancer, but its underlying mechanisms have been debated. Now Wang et al. (2011) suggest an intriguing explanation for this puzzle: a population of residual embryonic cells, lacking the transcription factor p63, migrates and repopulates a normal tissue damaged by inflammation or gastroesophageal reflux.
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Affiliation(s)
- Karine Lefort
- Department of Biochemistry, University of Lausanne, Epalinges CH-1066, Switzerland
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