title: Regulation of sucrase-isomaltase gene expression along the crypt-villus axis of rat small intestine.
abstract: The expression of sucrase-isomaltase mRNA was investigated along the crypt-villus axis of rat small intestine using differentially isolated cells and in situ hybridization. A partial rat sucrase-isomaltase cDNA was cloned which coded for a protein that was predicted to be 88% homologous to those encoded by the rabbit and human cDNAs. Southern blot analysis of rat genomic DNA indicated that the cDNA hybridized to a single gene. Northern blots of RNA extracted from subpopulations of intestinal epithelial cells that were isolated from villus and crypt compartments showed that this cDNA hybridized to a 6.5 kb band predominantly in villus RNA. In situ hybridization using 35[S]-labeled RNA probes demonstrated that autoradiographic grains were detected over eptithelial cells located on villi with the greatest number of grains located at the crypt-villus junction and in the lower to mid-villus region; from mid-villus to the villus tip there was a decline in sucrase-isomaltase mRNA. We conclude that expression of sucrase-isomaltase as enterocytes emerge from intestinal crypts is regulated primarily at the level of mRNA accumulation which, most likely, is a result of activation of sucrase-isomaltase gene transcription.
authors: Department of Internal Medicine, University of Michigan Medical School, Ann Arbor.
authors: P G
authors: PG
authors: Traber
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry; D004848:Epithelium / Q000201:enzymology / Q000648:ultrastructure; D005786:Gene Expression Regulation; D007421:Intestine, Small / Q000166:cytology / Q000201:enzymology*; D008297:Male; D008871:Microvilli / Q000201:enzymology*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D013394:Sucrase-Isomaltase Complex / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D004247:DNA; D013394:Sucrase-Isomaltase Complex