A gradient in expression of the Escherichia coli heat-stable enterotoxin receptor exists along the villus-to-crypt axis of rat small intestine.
Binding of Escherichia coli heat-stable enterotoxin to its receptor is critical to the initiation of toxin-induced secretion and diarrheal disease; it is also likely, however, that this receptor binds an endogenous ligand. In order to characterize the expression of the heat-stable enterotoxin receptor in the small intestine, we isolated epithelial cells from villus tip to crypt in rat jejunum and ileum. Binding of radiolabeled toxin was maximal in the villus preparations and gradually decreased along the villus-to-crypt axis, paralleling the decline of sucrase activity. Northern blots of total RNA identified a single heat stable enterotoxin receptor transcript (3.8 kb), predominantly in the villus cell fractions. In situ hybridization demonstrated clear signal in the villus cells with no apparent signal in the crypt cells, lamina propria or muscularis. Expression of this receptor was greatest after enterocytes leave the proliferative cycle and enter villi. This pattern of gene and protein expression may reflect a role of this receptor in binding endogenous ligands which in turn may regulate intestinal ion flux along the villus-to-crypt axis.
Cohen
M B
MB
Children's Hospital Medical Center, Cincinnati, OH 45229.
Mann
E A
EA
Lau
C
C
Henning
S J
SJ
Giannella
R A
RA
D000818:Animals; D016375:Antisense Elements (Genetics); D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D015342:DNA Probes; D004768:Enterotoxins / Q000235:genetics* / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D006162:Guanylate Cyclase / Q000235:genetics* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism*; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D018000:Receptors, Peptide; D013393:Sucrase / Q000378:metabolism; D014158:Transcription, Genetic
D016375:Antisense Elements (Genetics); D001427:Bacterial Toxins; D015342:DNA Probes; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D009838:Oligodeoxyribonucleotides; D011956:Receptors, Cell Surface; D018000:Receptors, Peptide; C034151:heat stable toxin (E coli); D012313:RNA; D013393:Sucrase; D006162:Guanylate Cyclase; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled