Comparison of the patterns of expression of rat intestinal fatty acid binding protein/human growth hormone fusion genes in cultured intestinal epithelial cell lines and in the gut epithelium of transgenic mice.
The intestinal fatty acid binding protein gene (Fabpi) provides a good model system for studying how gene transcription is regulated in enterocytes as a function of their differentiation program and location along the duodenal-to-colonic axis. We have compared and contrasted the transcriptional activity of four fusion genes composed of elements from the 5'-nontranscribed domain of rat Fabpi linked to the human growth hormone gene (I-FABP/hGH) in transgenic mice and in five primate epithelial cell lines derived from intestine, liver, kidney, and cervix. Nucleotides -103 to +28 of rat Fabpi are able to direct appropriate lineage-specific and geographic patterns of hGH expression in transgenic mice. I-FABP-103 to +28/hGH is preferentially expressed in Caco-2 cells, which emulate some of the features of differentiated small intestinal enterocytes after they reach confluence. However, other I-FABP/hGH fusion genes that exhibit differentiation-dependent changes in their expression along the crypt-to-villus axis do not manifest the same pattern of differentiation-dependent change in activity in this cell line. Correlation of their patterns of expression in vivo and ex vivo suggest that nonproliferating Caco-2 cells mimic some of the features of the transcriptional regulatory environment of enterocytes located in the upper crypt. Nucleotides -103 to +28 of rat Fabpi contain one copy of a repeated 14-base pair element that is conserved in the orthologous mouse and human genes and represented in several other homologous and nonhomologous genes, which are expressed in villus-associated enterocytes. This element binds to two members of the steroid hormone receptor superfamily of transcription factors produced in enterocytes and Caco-2 cells: hepatic nuclear factor-4 (HNF-4) and apolipoprotein regulatory protein-1 (ARP-1). Co-transfection studies performed in Caco-2 cells and in a monkey kidney cell line (CV-1) that lacks endogenous pools of ARP-1 and HNF-4 suggest that ARP-1 and HNF-4 can function to activate I-FABP-103 to +28/hGH+3 through their interactions with the 14-base pair element. This activation appears to be affected by elements located between nucleotides -277 and -104 and other transcription factors.
Department of Molecular Biology and Pharmacology, St. Louis, Missouri 63110.
J N
JN
Rottman
J I
JI
Gordon
D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004274:DNA, Recombinant / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D015870:Gene Expression; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D008745:Methylation; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D051381:Rats; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
D002352:Carrier Proteins; D004274:DNA, Recombinant; C107608:FABP7 protein, human; C082667:Fabp5 protein, mouse; C086936:Fabp7 protein, mouse; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009838:Oligodeoxyribonucleotides; D025521:Tumor Suppressor Proteins; D013006:Growth Hormone; D004247:DNA