Distribution of Escherichia coli heat-stable enterotoxin/guanylin/uroguanylin receptors in the avian intestinal tract

W. J. Krause, R. H. Freeman, S. L. Eber, F. K. Hamra, K. F. Fok, M. G. Currie, L. R. Forte

Research output: Contribution to journalArticle

Abstract

Pathogenic strains of enteric bacteria secrete small heat-stable toxins (STs) that activate membrane guanylyl cyclase receptors found in the intestine. The intestinal peptide agonists, guanylin and uroguanylin, are structurally related to STs. Receptors for 125I-ST were found throughout the entire length of the intestinal tract of all the birds examined. These receptors were restricted to intestinal epithelial cells covering villi and forming intestinal glands and were not observed in other strata of the gut wall. The most intense labeling of receptors by 125I-ST occurred in the region of the microvillus border of individual enterocytes. There appeared to be a decrease in receptor density distally along the length of the small intestine, although labeling of receptors by 125I-ST was observed throughout the small intestine and colon. Cellular cGMP accumulation responses to Escherichia coli ST and rat guanylin in the domestic turkey and duck were greater in the proximal small intestine compared to the distal small intestine or colon. Brush border membranes (BBM) isolated from the mucosa of proximal small intestine of turkeys exhibited agonist-stimulated guanylyl cyclase activity. The rank order potency for enzyme activation was E. coli ST > uroguanylin > guanylin. Competitive radioligand binding assays using 125I-ST and turkey intestine BBM revealed a similar rank order affinity for the receptors that was exemplified by the K(d) values of ST 2.5 nM, uroguanylin 80 nM and guanylin 2.6 μM. It may be concluded that functional receptors for the endogenous peptides, guanylin and uroguanylin, occur in the apical membranes of enterocytes throughout the avian intestine. The receptor-guanylyl cyclase(s) of proximal small intestine were preferentially activated by uroguanylin relative to guanylin, but both endogenous peptides were less potent than their molecular mimic, E. coli ST.

Original languageEnglish (US)
Pages (from-to)210-219
Number of pages10
JournalActa Anatomica
Volume153
Issue number3
StatePublished - 1995

Fingerprint

Small Intestine
Hot Temperature
Escherichia coli
Guanylate Cyclase-Coupled Receptors
Microvilli
Intestines
Membranes
Enterocytes
Colon
Radioligand Assay
Peptides
Enzyme Activation
Competitive Binding
Peptide Receptors
Ducks
Guanylate Cyclase
Enterobacteriaceae
Intestinal Mucosa
Birds
enterotoxin receptor

Keywords

  • Avian species
  • Cyclic GMP
  • Enterocytes
  • Guanylyl cyclase

ASJC Scopus subject areas

  • Anatomy

Cite this

Krause, W. J., Freeman, R. H., Eber, S. L., Hamra, F. K., Fok, K. F., Currie, M. G., & Forte, L. R. (1995). Distribution of Escherichia coli heat-stable enterotoxin/guanylin/uroguanylin receptors in the avian intestinal tract. Acta Anatomica, 153(3), 210-219.

Distribution of Escherichia coli heat-stable enterotoxin/guanylin/uroguanylin receptors in the avian intestinal tract. / Krause, W. J.; Freeman, R. H.; Eber, S. L.; Hamra, F. K.; Fok, K. F.; Currie, M. G.; Forte, L. R.

In: Acta Anatomica, Vol. 153, No. 3, 1995, p. 210-219.

Research output: Contribution to journalArticle

Krause, WJ, Freeman, RH, Eber, SL, Hamra, FK, Fok, KF, Currie, MG & Forte, LR 1995, 'Distribution of Escherichia coli heat-stable enterotoxin/guanylin/uroguanylin receptors in the avian intestinal tract', Acta Anatomica, vol. 153, no. 3, pp. 210-219.
Krause, W. J. ; Freeman, R. H. ; Eber, S. L. ; Hamra, F. K. ; Fok, K. F. ; Currie, M. G. ; Forte, L. R. / Distribution of Escherichia coli heat-stable enterotoxin/guanylin/uroguanylin receptors in the avian intestinal tract. In: Acta Anatomica. 1995 ; Vol. 153, No. 3. pp. 210-219.
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abstract = "Pathogenic strains of enteric bacteria secrete small heat-stable toxins (STs) that activate membrane guanylyl cyclase receptors found in the intestine. The intestinal peptide agonists, guanylin and uroguanylin, are structurally related to STs. Receptors for 125I-ST were found throughout the entire length of the intestinal tract of all the birds examined. These receptors were restricted to intestinal epithelial cells covering villi and forming intestinal glands and were not observed in other strata of the gut wall. The most intense labeling of receptors by 125I-ST occurred in the region of the microvillus border of individual enterocytes. There appeared to be a decrease in receptor density distally along the length of the small intestine, although labeling of receptors by 125I-ST was observed throughout the small intestine and colon. Cellular cGMP accumulation responses to Escherichia coli ST and rat guanylin in the domestic turkey and duck were greater in the proximal small intestine compared to the distal small intestine or colon. Brush border membranes (BBM) isolated from the mucosa of proximal small intestine of turkeys exhibited agonist-stimulated guanylyl cyclase activity. The rank order potency for enzyme activation was E. coli ST > uroguanylin > guanylin. Competitive radioligand binding assays using 125I-ST and turkey intestine BBM revealed a similar rank order affinity for the receptors that was exemplified by the K(d) values of ST 2.5 nM, uroguanylin 80 nM and guanylin 2.6 μM. It may be concluded that functional receptors for the endogenous peptides, guanylin and uroguanylin, occur in the apical membranes of enterocytes throughout the avian intestine. The receptor-guanylyl cyclase(s) of proximal small intestine were preferentially activated by uroguanylin relative to guanylin, but both endogenous peptides were less potent than their molecular mimic, E. coli ST.",
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