Mechanism of action of Escherichia coli heat stable enterotoxin in a human colonic cell line.

Huott, P. A.; Liu, W; McRoberts, James A.; Giannella, Ralph A.; Dharmsathaphorn, Kiertisin

doi:10.1172/jci113626

Cited by 111 publications

(94 citation statements)

References 27 publications

(29 reference statements)

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“…The signals for short circuit current (Isc) and potential difference across the epithelium were measured every 20 sec, digitized with an ADC-1 data recording system (Remote Measurement Systems, Seattle) and stored for later analysis. The Isc observed with T84 cells cultured on permeable filters has been shown to be caused by the net secretion of chloride across T84 cell monolayers when cells were treated with various chloride secretogogues, including guanylin, uroguanylin, and Escherichia coli ST (1,2,15,26).…”

Section: Methodsmentioning

confidence: 99%

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

Hamra¹,

Eber²,

Chin³

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

104

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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 f luid 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 inf luenced 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 pHdependent fashion, the activity of receptors that control intestinal salt and water transport via cGMP.Guanylin and uroguanylin are structurally related peptides that were isolated from intestinal mucosa and urine (1-5). A receptor for guanylin and uroguanylin that has been identified at the molecular level is a transmembrane form of guanylate cyclase, termed GC-C (6). This membrane protein was originally discovered as an intestinal receptor for the heat-stable toxin (ST) peptides, which are secreted intraluminally by enteric bacteria that cause traveler's diarrhea (7). Bacterial ST peptides are related in primary structure to uroguanylin and guanylin, thus acting as molecular mimics of the enteric peptide hormones (reviewed in refs. 8 and 9). Membrane receptor-guanylate cyclases are found on the luminal surface of enterocytes throughout the small and large intestine and in other epithelia (10-13). Binding of peptide agonists to an extracellular domain of the receptor activates the intracellular catalytic domain producing the second messenger cGMP within target enterocytes (1-6). Intracellular cGMP stimulates transepithelial chloride secretion by regulating the phosphorylation state and chloride channel activit...

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Section: Methodsmentioning

confidence: 99%

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

Hamra¹,

Eber²,

Chin³

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

104

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“…We chose to test the acetylcholine analog carbachol since it was known that T84 cells respond to carbachol with a rise in intracellular calcium, an intracellular messenger which can potentiate the activation of protein kinase C. Huott et al had previously examined the cyclic GMP response of T84 cells to STavs STa plus carbachol for 15 min and did not note an increase in cyclic GMP with the addition of carbachol [5]. Based on our data, however, 15 min is too early to see an effect of carbachol ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The small peptide toxin STa, the heatstable toxin of E. coli, binds with high affinity to a receptor apparently distinct from particulate guanylate cyclase (GTP pyrophosphate lyase [cyclizing], EC 4.6.1.2) and stimulates the latter enzyme [2,3]. The T84 cell line is a human colon carcinoma cell line which responds to STa with a rise in cyclic GMP and to carbachol with a rise in intracellular calcium; both secretagogues result in chloride secretion [4][5][6][7]. Weikel et al recently showed that phorbol esters, which alone have no effect on cyclic GMP levels, enhanced STastimulated cyclic GMP levels by 1.6-2.4-fold [8].…”

Section: Introductionmentioning

confidence: 99%

Carbachol mimics phorbol esters in its ability to enhance cyclic GMP production by STa, the heat‐stable toxin of Escherichia coli

et al. 1990

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STa, the heat-stable enterotoxin of Escherichia coli, stimulates membrane-bound guanylate cyclase in enterocytes, elevates cyclic GMP, and results in intestinal secretion of ions and fluid. Using the T84 colon carcinoma cell line as a model, Weikel et al. reported that phorbol esters enhance STa-stimulated cyclic GMP production by 61%140% ) Infect. Immun. 58, 1402 1407. In the present report we demonstrate that the acetylcholine analog carbachol enhanced toxin-stimulated cyclic GMP accumulation in intact T84 cells by 50-100% and that this effect was blocked by 10 /~M atropine and 10/IM sphingosine. Pertussis toxin treatment of the T84 cells did not affect the subsequent response to carbachol. Carbachol, which elevates intracellular calcium in these cells, may act through protein kinase C to enhance cyclic GMP production.

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“…Le site de phosphorylation serait la sérine en position 1029 du GC-C pour la PKC [25]. Ainsi, suite à l'attachement de STa, une production de GMPc est déclenchée, qui conduit à l'augmentation de la sécrétion intestinale de chlore et à l'inhibition de l'absorption de sodium [39,42,57,68,118] (pour illustration voir [33]). …”

Section: Activation De La Guanylate Cyclaseunclassified

Les récepteurs des entérotoxines bactériennes

Rousset

2000

Vet. Res.

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-Bacterial enterotoxin receptors. Enteric bacterial toxins display a great diversity in their structure, molecular weight and mechanism of action. The interaction of enterotoxins with the intestinal mucosa either leads to a direct effect on the cell membrane or an effect on signal transduction within eukaryotic cells. However, before a toxin can affect a cell, it must after its secretion by a microorganism, recognise and bind to a specific surface molecule, its receptor. Membrane receptors of bacterial enterotoxins have been identified as protein, glycoprotein or glycolipid in nature. The chemical nature of the molecules acting as receptors is crucial and during evolution they have been carefully selected. Some toxins, after their interaction with a receptor molecule, will transduce a signal across the cell membrane while remaining at the cell surface. Other toxins, after this initial binding step with a receptor, will be internalised. Others can form pores leading to leakage of cellular components and cell lysis. Receptors that have been identified often comprise a saccharidic chain that is directly involved in the recognition and binding of the toxin. Today, models explaining toxin-receptor interactions are more complex, including multistep events. This review summarises the knowledge of the interactions between bacterial toxins and membrane receptors present on intestinal mucosa. receptor / intestine / enterotoxin / binding epitope / glycosphingolipidRésumé -Les toxines bactériennes entériques présentent une grande diversité autant dans leur structure que dans leur poids moléculaire et leur mécanisme d'action. L'interaction des entérotoxines avec la muqueuse intestinale conduit soit à un effet direct sur la paroi cellulaire de la cellule hôte, soit à un dérèglement des voies de signalisation de celle-ci. Toutefois, avant même d'affecter la cellule cible, la toxine sécrétée par le micro-organisme devra reconnaître et s'attacher à une molécule présente à la surface cellulaire, son récepteur. Les récepteurs membranaires des entérotoxines bactériennes peuvent être de nature protéique, glycoprotéique ou glycolipidique. La nature chimique de ces récepteurs, sur laquelle repose la spécificité, est primordiale et au cours de l'évolution ceuxci ont été soigneusement sélectionnés. Certaines toxines, une fois en contact avec leur récepteur, envoient un signal à l'intérieur de la cellule tout en demeurant à la surface alors que d'autres toxines sont internalisées. Enfin, certaines toxines bactériennes peuvent former des pores dans la membrane Vet. Res. 31 (2000)

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Mechanism of action of Escherichia coli heat stable enterotoxin in a human colonic cell line.

Cited by 111 publications

References 27 publications

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

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

Carbachol mimics phorbol esters in its ability to enhance cyclic GMP production by STa, the heat‐stable toxin of Escherichia coli

Les récepteurs des entérotoxines bactériennes

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