Developmental regulation of beta-galactoside alpha 2,6-sialyltransferase in small intestine epithelium.
A striking biochemical alteration to the epithelium of the small intestine upon weaning is the loss of microvillar sialic acids. Antibody and cDNA probes to the beta-galactoside alpha 2,6-sialyltransferase (SiaT-1, EC 2.4.99.1) were used to characterize the expression of this sialyltransferase in the small intestine of suckling rats. SiaT-1 mRNA and protein in the intestinal epithelium are rapidly lost upon weaning, in agreement with the loss of mucosal sialic acids and general sialyltransferase activity. Developmental repression of SiaT-1 is manifested in a proximal to distal gradient; SiaT-1 mRNA and protein are lost first from the duodenum and persist the longest in the ileum. We have previously documented that SiaT-1 gene expression can be transcriptionally initiated from a number of distinct tissue-specific promoter regions. Here, by criteria of mRNA mobility on agarose gels, primer extension analysis, and differential Northern hybridization, we show that the promoter previously considered to be liver-specific is operative in SiaT-1 expression in the small intestine of suckling animals. Comparison of this SiaT-1 promoter region with promoter regions of other genes exhibiting dual intestine-hepatic tissue specificity revealed a number of striking sequence similarities. Regulatory implications and consequences of small intestinal SiaT-1 expression in suckling but not in weaned animals are discussed.
Vertino-Bell
A
A
Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, New York 14263.
Ren
J
J
Black
J D
JD
Lau
J T
JT
D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D004247:DNA; D004848:Epithelium / Q000201:enzymology / Q000254:growth & development; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D007421:Intestine, Small / Q000201:enzymology* / Q000254:growth & development; D008099:Liver / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012689:Sequence Homology, Nucleic Acid; D012799:Sialyltransferases / Q000096:biosynthesis / Q000235:genetics*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D015703:Antigens, CD; D012333:RNA, Messenger; D004247:DNA; D012799:Sialyltransferases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase