Brief Article
Copyright ©2010 Baishideng. All rights reserved.
World J Gastroenterol. Aug 21, 2010; 16(31): 3919-3927
Published online Aug 21, 2010. doi: 10.3748/wjg.v16.i31.3919
Mapping of liver-enriched transcription factors in the human intestine
Frank Lehner, Ulf Kulik, Juergen Klempnauer, Juergen Borlak
Frank Lehner, Ulf Kulik, Juergen Klempnauer, Department of General, Visceral and Transplantation Surgery, Hanover Medical School, 30625 Hanover, Germany
Juergen Borlak, Molecular Medicine and Medical Biotechnology, Fraunhofer Institute of Toxicology and Experimental Medicine, 30625 Hannover, Germany; Center of Pharmacology and Toxicology, Hanover Medical School, 30625 Hanover, Germany
Author contributions: Lehner F and Kulik U performed the majority of the experiments; Klempnauer J was involved in editing the manuscript and provided the collection of the human material; Borlak J designed the study; Borlak J and Lehner F wrote the manuscript.
Supported by (in part) Novartis Pharma GmbH, Germany, BU Transplantation and Immunology (to Lehner F) and by the Lower Saxony Ministry of Culture and Sciences and the Volkswagen foundation, Germany, Grant No. 25A.5-7251-99-3/00
Correspondence to: Juergen Borlak, Professor, Drug Research and Medical Biotechnology, Fraunhofer Institute of Toxicology and Experimental Medicine, Nikolai-Fuchs-Strasse, 30625 Hannover, Germany. juergen.borlak@item.fraunhofer.de
Telephone: +49-511-5350559 Fax: +49-511-5350155
Received: February 23, 2010
Revised: April 13, 2010
Accepted: April 20, 2010
Published online: August 21, 2010
Abstract

AIM: To investigate the gene expression pattern of hepatocyte nuclear factor 6 (HNF6) and other liver-enriched transcription factors in various segments of the human intestine to better understand the differentiation of the gut epithelium.

METHODS: Samples of healthy duodenum and jejunum were obtained from patients with pancreatic cancer whereas ileum and colon was obtained from patients undergoing right or left hemicolectomy or (recto)sigmoid or rectal resection. All surgical specimens were subjected to histopathology. Excised tissue was shock-frozen and analyzed for gene expression of liver-enriched transcription factors by semiquantitative reverse transcription polymerase chain and compared to the human colon carcinoma cell line Caco-2. Protein expression of major liver-enriched transcription factors was determined by Western blotting while the DNA binding of HNF6 was investigated by electromobility shift assays.

RESULTS: The gene expression patterning of liver-enriched transcription factors differed in the various segments of the human intestine with HNF6 gene expression being most abundant in the duodenum (P < 0.05) whereas expression of the zinc finger protein GATA4 and of the HNF6 target gene ALDH3A1 was most abundant in the jejunum (P < 0.05). Likewise, expression of FOXA2 and the splice variants 2 and 4 of HNF4α were most abundantly expressed in the jejunum (P < 0.05). Essentially, expression of transcription factors declined from the duodenum towards the colon with the most abundant expression in the jejunum and less in the ileum. The expression of HNF6 and of genes targeted by this factor, i.e. neurogenin 3 (NGN3) was most abundant in the jejunum followed by the ileum and the colon while DNA binding activity of HNF4α and of NGN3 was confirmed by electromobility shift assays to an optimized probe. Furthermore, Western blotting provided evidence of the expression of several liver-enriched transcription factors in cultures of colon epithelial cells, albeit at different levels.

CONCLUSION: We describe significant local and segmental differences in the expression of liver-enriched transcription factors in the human intestine which impact epithelial cell biology of the gut.

Keywords: Liver-enriched transcription factors; Human intestine; Caco-2; Gene expression