Mapping of liver-enriched transcription factors in the human intestine.
OBJECTIVE
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 HNF4alpha 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 HNF4alpha 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.


CONCLUSIONS
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.
Lehner
Frank
F
Drug Research and Medical Biotechnology, Fraunhofer Institute of Toxicology and Experimental Medicine, Nikolai-Fuchs-Strasse, Hannover, Germany.
Kulik
Ulf
U
Klempnauer
Juergen
J
Borlak
Juergen
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000444:Aldehyde Dehydrogenase / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D015153:Blotting, Western; D018938:Caco-2 Cells; D003106:Colon / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D050991:GATA4 Transcription Factor / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D051542:Hepatocyte Nuclear Factor 3-beta / Q000378:metabolism; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism; D051559:Hepatocyte Nuclear Factor 6 / Q000378:metabolism; D006801:Humans; D007082:Ileum / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D000444:Aldehyde Dehydrogenase; D051792:Basic Helix-Loop-Helix Proteins; D004247:DNA; D050991:GATA4 Transcription Factor; D051542:Hepatocyte Nuclear Factor 3-beta; D051557:Hepatocyte Nuclear Factor 4; D051559:Hepatocyte Nuclear Factor 6; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C496502:FOXA2 protein, human; C484170:GATA4 protein, human; C496592:HNF4A protein, human; C498695:NEUROG3 protein, human; C480021:ALDH3A1 protein, human