Isolation and characterization of the human sucrase-isomaltase gene and demonstration of intestine-specific transcriptional elements.
The molecular mechanisms that regulate intestine-specific gene expression and the transition from proliferating, undifferentiated crypt cells to nonproliferating, differentiated villus cells are unknown. Sucrase-isomaltase is an apical membrane disaccharidase that is found exclusively in enterocytes of adult intestine and is expressed in a complex pattern along the intestinal crypt-villus axis. To investigate the regulation of sucrase-isomaltase, we have cloned and sequenced 3.6 kilobases of the 5'-flanking region of the human sucrase-isomaltase gene. The transcriptional start site was mapped in human small intestine and in a colonic adenocarcinoma cell line (Caco-2) using an anchored polymerase chain reaction, primer extension, and RNase protection assays. The 5'-flanking DNA of the gene was linked to either chloramphenicol acetyltransferase or luciferase reporter genes and used for transfection into Caco-2, HeLa, and HepG2 cells. This analysis demonstrated that intestine-specific transcription of the sucrase-isomaltase gene involves both proximal and distal regulatory elements. Use of sucrase-isomaltase as a model gene will allow investigation of the mechanisms that regulate transcription of enterocyte-specific genes, developmental gene expression in the small intestine and colon, and the process of differentiation as epithelial cells migrate from intestinal crypts onto the villus in adult intestine.
Wu
G D
GD
Department of Internal Medicine, University of Michigan Medical School, Ann Arbor.
Wang
W
W
Traber
P G
PG
D000230:Adenocarcinoma / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003001:Cloning, Molecular; D003110:Colonic Neoplasms / Q000378:metabolism; D004247:DNA; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D007421:Intestine, Small / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D013394:Sucrase-Isomaltase Complex / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D004247:DNA; D008156:Luciferases; D015500:Chloramphenicol O-Acetyltransferase; D013394:Sucrase-Isomaltase Complex