Regulation of intestinal uroguanylin/guanylin receptor-mediated responses by mucosal acidity

F. Kent Hamra, Sammy L. Eber, David T. Chin, Mark G. Currie, Leonard R. Forte

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

Guanylin and uroguanylin are intestinal peptides that stimulate chloride secretion by activating a common set of receptor-guanylate cyclase signaling molecules located on the mucosal surface of enterocytes. High mucosal acidity, similar to the pH occurring within the fluid microclimate domain at the mucosal surface of the intestine, markedly enhances the cGMP accumulation responses of T84 human intestinal cells to uroguanylin. In contrast, a mucosal acidity of pH 5.0 renders guanylin essentially inactive. T84 cells were used as a model epithelium to further explore the concept that mucosal acidity imposes agonist selectivity for activation of the intestinal receptors for uroguanylin and guanylin, thus providing a rationale for the evolution of these related peptides. At an acidic mucosal pH of 5.0, uroguanylin is 100-fold more potent than guanylin, but at an alkaline pH of 8.0 guanylin is more potent than uroguanylin in stimulating intracellular cGMP accumulation and transepithelial chloride secretion. The relative affinities of uroguanylin and guanylin for binding to receptors on the mucosal surface of T84 cells is influenced dramatically by mucosal acidity, which explains the strong pH dependency of the cGMP and chloride secretion responses to these peptides. The guanylin-binding affinities for peptide- receptor interaction were reduced by 100-fold at pH 5 versus pH 8, whereas the affinities of uroguanylin for these receptors were increased 10-fold by acidic pH conditions. Deletion of the N-terminal acidic amino acids in uroguanylin demonstrated that these residues are responsible for the increase in binding affinities that are observed for uroguanylin at acidic pH. We conclude that guanylin and uroguanylin evolved distinctly different structures, which enables both peptides to regulate, in a pH-dependent fashion, the activity of receptors that control intestinal salt and water transport via cGMP.

Original languageEnglish (US)
Pages (from-to)2705-2710
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume94
Issue number6
DOIs
StatePublished - Mar 18 1997

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Chlorides
Peptides
enterotoxin receptor
Microclimate
Acidic Amino Acids
uroguanylin
Peptide Receptors
Enterocytes
Guanylate Cyclase
guanylin
Intestines
Epithelium
Salts
Water

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Regulation of intestinal uroguanylin/guanylin receptor-mediated responses by mucosal acidity. / Kent Hamra, F.; Eber, Sammy L.; Chin, David T.; Currie, Mark G.; Forte, Leonard R.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 94, No. 6, 18.03.1997, p. 2705-2710.

Research output: Contribution to journalArticle

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abstract = "Guanylin and uroguanylin are intestinal peptides that stimulate chloride secretion by activating a common set of receptor-guanylate cyclase signaling molecules located on the mucosal surface of enterocytes. High mucosal acidity, similar to the pH occurring within the fluid microclimate domain at the mucosal surface of the intestine, markedly enhances the cGMP accumulation responses of T84 human intestinal cells to uroguanylin. In contrast, a mucosal acidity of pH 5.0 renders guanylin essentially inactive. T84 cells were used as a model epithelium to further explore the concept that mucosal acidity imposes agonist selectivity for activation of the intestinal receptors for uroguanylin and guanylin, thus providing a rationale for the evolution of these related peptides. At an acidic mucosal pH of 5.0, uroguanylin is 100-fold more potent than guanylin, but at an alkaline pH of 8.0 guanylin is more potent than uroguanylin in stimulating intracellular cGMP accumulation and transepithelial chloride secretion. The relative affinities of uroguanylin and guanylin for binding to receptors on the mucosal surface of T84 cells is influenced dramatically by mucosal acidity, which explains the strong pH dependency of the cGMP and chloride secretion responses to these peptides. The guanylin-binding affinities for peptide- receptor interaction were reduced by 100-fold at pH 5 versus pH 8, whereas the affinities of uroguanylin for these receptors were increased 10-fold by acidic pH conditions. Deletion of the N-terminal acidic amino acids in uroguanylin demonstrated that these residues are responsible for the increase in binding affinities that are observed for uroguanylin at acidic pH. We conclude that guanylin and uroguanylin evolved distinctly different structures, which enables both peptides to regulate, in a pH-dependent fashion, the activity of receptors that control intestinal salt and water transport via cGMP.",
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