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Siddiq A, Dong G, Balan B, Harrison LG, Jex A, Olivier M, Allain T, Buret AG. A thermo-resistant and RNase-sensitive cargo from Giardia duodenalis extracellular vesicles modifies the behaviour of enterobacteria. JOURNAL OF EXTRACELLULAR BIOLOGY 2023; 2:e109. [PMID: 38938375 PMCID: PMC11080815 DOI: 10.1002/jex2.109] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 08/10/2023] [Accepted: 08/15/2023] [Indexed: 06/29/2024]
Abstract
Extracellular vesicles (EVs) recently emerged as important players in the pathophysiology of parasitic infections. While the protist parasite Giardia duodenalis can produce EVs, their role in giardiasis remains obscure. Giardia can disrupt gut microbiota biofilms and transform commensal bacteria into invasive pathobionts at sites devoid of colonizing trophozoites via unknown mechanisms. We hypothesized that Giardia EVs could modify gut bacterial behaviour via a novel mode of trans-kingdom communication. Our findings indicate that Giardia EVs exert bacteriostatic effects on Escherichia coli HB101 and Enterobacter cloacae TW1, increasing their swimming motility. Giardia EVs also decreased the biofilm-forming ability of E. coli HB101 but not by E. cloacae TW1, supporting the hypothesis that these effects are, at least in part, bacteria-selective. E. coli HB101 and E. cloacae TW1 exhibited increased adhesion/invasion onto small intestine epithelial cells when exposed to Giardia EVs. EVs labelled with PKH67 revealed colocalization with E. coli HB101 and E. cloacae TW1 bacterial cells. Small RNA sequencing revealed a high abundance of ribosomal RNA (rRNA)- and transfer RNA (tRNA)-derived small RNAs, short-interfering RNAs (siRNAs) and micro-RNAs (miRNAs) within Giardia EVs. Proteomic analysis of EVs uncovered the presence of RNA chaperones and heat shock proteins that can facilitate the thermal stability of EVs and its sRNA cargo, as well as protein-modifying enzymes. In vitro, RNase heat-treatment assays showed that total RNAs in EVs, but not proteins, are responsible for modulating bacterial swimming motility and biofilm formation. G. duodenalis small RNAs of EVs, but not proteins, were responsible for the increased bacterial adhesion to intestinal epithelial cells induced upon exposure to Giardia EVs. Together, the findings indicate that Giardia EVs contain a heat-stable, RNase-sensitive cargo that can trigger the development of pathobiont characteristics in Enterobacteria, depicting a novel trans-kingdom cross-talk in the gut.
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Affiliation(s)
- Affan Siddiq
- Department of Biological SciencesUniversity of CalgaryCalgaryAlbertaCanada
- Inflammation Research NetworkUniversity of CalgaryCalgaryAlbertaCanada
- Host‐Parasite InteractionsUniversity of CalgaryCalgaryAlbertaCanada
| | - George Dong
- Department of Microbiology and Immunology, The Research Institute of the McGill University Health Centre, Program in Infectious Diseases and Immunology in Global HeathMontréalQCCanada
| | - Balu Balan
- The Walter and Eliza Hall Institute of Medical ResearchMelbourneAustralia
- The University of MelbourneMelbourneAustralia
| | - Luke G. Harrison
- Department of Biological SciencesUniversity of CalgaryCalgaryAlbertaCanada
- Inflammation Research NetworkUniversity of CalgaryCalgaryAlbertaCanada
- Host‐Parasite InteractionsUniversity of CalgaryCalgaryAlbertaCanada
| | - Aaron Jex
- The Walter and Eliza Hall Institute of Medical ResearchMelbourneAustralia
- The University of MelbourneMelbourneAustralia
| | - Martin Olivier
- Department of Microbiology and Immunology, The Research Institute of the McGill University Health Centre, Program in Infectious Diseases and Immunology in Global HeathMontréalQCCanada
| | - Thibault Allain
- Department of Biological SciencesUniversity of CalgaryCalgaryAlbertaCanada
- Inflammation Research NetworkUniversity of CalgaryCalgaryAlbertaCanada
- Host‐Parasite InteractionsUniversity of CalgaryCalgaryAlbertaCanada
| | - Andre G. Buret
- Department of Biological SciencesUniversity of CalgaryCalgaryAlbertaCanada
- Inflammation Research NetworkUniversity of CalgaryCalgaryAlbertaCanada
- Host‐Parasite InteractionsUniversity of CalgaryCalgaryAlbertaCanada
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High-fat diet increases the severity of Giardia infection in association with low-grade inflammation and gut microbiota dysbiosis. Sci Rep 2021; 11:18842. [PMID: 34552170 PMCID: PMC8458452 DOI: 10.1038/s41598-021-98262-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/01/2021] [Indexed: 12/26/2022] Open
Abstract
Exogenous factors that may influence the pathophysiology of Giardia infection remain incompletely understood. We have investigated the role of dietary fat in the pathogenesis of Giardia infection. Male 3 to 4-week-old C57BL/6 mice were fed either a low fat (LF) or a high fat (HF) diet for 12 days and challenged with G. duodenalis. In infected animals, the trophozoite burden was higher in HF + Giardia mice compared to the LF + Giardia group at day 7 post infection. Fatty acids exerted direct pro-growth effects on Giardia trophozoites. Analysis of disease parameters showed that HF + Giardia mice exhibited more mucosal infiltration by inflammatory cells, decreased villus/crypt ratios, goblet cell hyperplasia, mucus disruption, increased gut motility, and elevated fecal water content compared with LF + Giardia. HF diet-dependent exacerbation of Giardia-induced goblet cell hyperplasia was associated with elevated Atoh1 and Muc2 gene expression. Gut microbiota analysis revealed that the HF diet alone induces a taxonomic shift. HF + Giardia mice exhibited microbiota dysbiosis characterized by an increase of Firmicutes and a decrease of Bacteroidetes and significant changes in α- and β-diversity metrics. Taken together, the findings suggest that a HF diet exacerbates the outcome of Giardia infection. The data demonstrate that elevated dietary fat represents an important exogenous factor promoting the pathophysiology of giardiasis.
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Jex AR, Svärd S, Hagen KD, Starcevich H, Emery-Corbin SJ, Balan B, Nosala C, Dawson SC. Recent advances in functional research in Giardia intestinalis. ADVANCES IN PARASITOLOGY 2020; 107:97-137. [PMID: 32122532 PMCID: PMC7878119 DOI: 10.1016/bs.apar.2019.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This review considers current advances in tools to investigate the functional biology of Giardia, it's coding and non-coding genes, features and cellular and molecular biology. We consider major gaps in current knowledge of the parasite and discuss the present state-of-the-art in its in vivo and in vitro cultivation. Advances in in silico tools, including for the modelling non-coding RNAs and genomic elements, as well as detailed exploration of coding genes through inferred homology to model organisms, have provided significant, primary level insight. Improved methods to model the three-dimensional structure of proteins offer new insights into their function, and binding interactions with ligands, other proteins or precursor drugs, and offer substantial opportunities to prioritise proteins for further study and experimentation. These approaches can be supplemented by the growing and highly accessible arsenal of systems-based methods now being applied to Giardia, led by genomic, transcriptomic and proteomic methods, but rapidly incorporating advanced tools for detection of real-time transcription, evaluation of chromatin states and direct measurement of macromolecular complexes. Methods to directly interrogate and perturb gene function have made major leaps in recent years, with CRISPr-interference now available. These approaches, coupled with protein over-expression, fluorescent labelling and in vitro and in vivo imaging, are set to revolutionize the field and herald an exciting time during which the field may finally realise Giardia's long proposed potential as a model parasite and eukaryote.
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Affiliation(s)
- Aaron R Jex
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, VIC, Australia; Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia.
| | - Staffan Svärd
- Centre for Biomedicine, Uppsala University, Uppsala, Sweden
| | - Kari D Hagen
- College of Biological Sciences, University of California-Davis, Davis, CA, United States
| | - Hannah Starcevich
- College of Biological Sciences, University of California-Davis, Davis, CA, United States
| | - Samantha J Emery-Corbin
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, VIC, Australia
| | - Balu Balan
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, VIC, Australia
| | - Chris Nosala
- College of Biological Sciences, University of California-Davis, Davis, CA, United States
| | - Scott C Dawson
- College of Biological Sciences, University of California-Davis, Davis, CA, United States
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Du C, Chen S, Wan H, Chen L, Li L, Guo H, Tuo B, Dong H. Different functional roles for K + channel subtypes in regulating small intestinal glucose and ion transport. Biol Open 2019; 8:bio.042200. [PMID: 31243019 PMCID: PMC6679390 DOI: 10.1242/bio.042200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Although K+ channels are important in mediating the driving force for colonic ion transport, their role in small intestinal transport is poorly understood. To investigate this, small intestinal short circuit currents (Isc ) and HCO3 - secretion were measured in mice, and intracellular pH (pHi) was measured in small intestinal epithelial SCBN cells. The expression and location of Kv subtypes were verified by RT-PCR, western blotting and immunohistochemistry. Diabetic mice were also used to investigate the role of Kv subtypes in regulating intestinal glucose absorption. We found that KV7.1 is not involved in duodenal ion transport, while KCa3.1 selectively regulates duodenal Isc and HCO3 - secretion in a Ca2+-mediated but not cAMP-mediated manner. Blockade of KCa3.1 increased the rate of HCO3 - fluxes via cystic fibrosis transmembrane conductance regulator (CFTR) channels in SCBN cells. Jejunal Isc was significantly stimulated by glucose, but markedly inhibited by 4-aminopyridine (4-AP) and tetraethylammonium (TEA). Moreover, both Kv1.1 and Kv1.3 were expressed in jejunal mucosae. Finally, 4-AP significantly attenuated weight gain of normal and diabetic mice, and both 4-AP and TEA significantly lowered blood glucose of diabetic mice. This study not only examines the contribution of various K+ channel subtypes to small intestinal epithelial ion transport and glucose absorption, but also proposes a novel concept for developing specific K+ channel blockers to reduce weight gain and lower blood glucose in diabetes mellitus.
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Affiliation(s)
- Chao Du
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.,Department of Gastroenterology and Hepatology, Chengdu Military General Hospital, Sichuan Province, Chengdu 610000, China
| | - Siyuan Chen
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Lihong Chen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Lingyu Li
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Hong Guo
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China .,Department of Medicine, School of Medicine, University of California, San Diego, CA 92093, USA
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Giardipain-1, a protease secreted by Giardia duodenalis trophozoites, causes junctional, barrier and apoptotic damage in epithelial cell monolayers. Int J Parasitol 2018; 48:621-639. [DOI: 10.1016/j.ijpara.2018.01.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/23/2017] [Accepted: 01/01/2018] [Indexed: 12/11/2022]
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Ronaghan NJ, Shang J, Iablokov V, Zaheer R, Colarusso P, Dion S, Désilets A, Leduc R, Turner JR, MacNaughton WK. The serine protease-mediated increase in intestinal epithelial barrier function is dependent on occludin and requires an intact tight junction. Am J Physiol Gastrointest Liver Physiol 2016; 311:G466-79. [PMID: 27492333 PMCID: PMC5076006 DOI: 10.1152/ajpgi.00441.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 07/28/2016] [Indexed: 01/31/2023]
Abstract
Barrier dysfunction is a characteristic of the inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Understanding how the tight junction is modified to maintain barrier function may provide avenues for treatment of IBD. We have previously shown that the apical addition of serine proteases to intestinal epithelial cell lines causes a rapid and sustained increase in transepithelial electrical resistance (TER), but the mechanisms are unknown. We hypothesized that serine proteases increase barrier function through trafficking and insertion of tight junction proteins into the membrane, and this could enhance recovery of a disrupted monolayer after calcium switch or cytokine treatment. In the canine epithelial cell line, SCBN, we showed that matriptase, an endogenous serine protease, could potently increase TER. Using detergent solubility-based cell fractionation, we found that neither trypsin nor matriptase treatment changed levels of tight junction proteins at the membrane. In a fast calcium switch assay, serine proteases did not enhance the rate of recovery of the junction. In addition, serine proteases could not reverse barrier disruption induced by IFNγ and TNFα. We knocked down occludin in our cells using siRNA and found this prevented the serine protease-induced increase in TER. Using fluorescence recovery after photobleaching (FRAP), we found serine proteases induce a greater mobile fraction of occludin in the membrane. These data suggest that a functional tight junction is needed for serine proteases to have an effect on TER, and that occludin is a crucial tight junction protein in this mechanism.
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Affiliation(s)
- Natalie J. Ronaghan
- 1Department of Physiology and Pharmacology and Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada;
| | - Judie Shang
- 1Department of Physiology and Pharmacology and Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada;
| | - Vadim Iablokov
- 1Department of Physiology and Pharmacology and Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada;
| | - Raza Zaheer
- 1Department of Physiology and Pharmacology and Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada;
| | - Pina Colarusso
- 1Department of Physiology and Pharmacology and Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada;
| | - Sébastien Dion
- 2Département de Pharmacologie-Physiologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada; and
| | - Antoine Désilets
- 2Département de Pharmacologie-Physiologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada; and
| | - Richard Leduc
- 2Département de Pharmacologie-Physiologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada; and
| | - Jerrold R. Turner
- 3Departments of Pathology and Medicine (GI), Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Wallace K. MacNaughton
- 1Department of Physiology and Pharmacology and Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada;
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Xie R, Dong X, Wong C, Vallon V, Tang B, Sun J, Yang S, Dong H. Molecular mechanisms of calcium-sensing receptor-mediated calcium signaling in the modulation of epithelial ion transport and bicarbonate secretion. J Biol Chem 2014; 289:34642-53. [PMID: 25331955 DOI: 10.1074/jbc.m114.592774] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Epithelial ion transport is mainly under the control of intracellular cAMP and Ca(2+) signaling. Although the molecular mechanisms of cAMP-induced epithelial ion secretion are well defined, those induced by Ca(2+) signaling remain poorly understood. Because calcium-sensing receptor (CaSR) activation results in an increase in cytosolic Ca(2+) ([Ca(2+)]cyt) but a decrease in cAMP levels, it is a suitable receptor for elucidating the mechanisms of [Ca(2+)]cyt-mediated epithelial ion transport and duodenal bicarbonate secretion (DBS). CaSR proteins have been detected in mouse duodenal mucosae and human intestinal epithelial cells. Spermine and Gd(3+), two CaSR activators, markedly stimulated DBS without altering duodenal short circuit currents in wild-type mice but did not affect DBS and duodenal short circuit currents in cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice. Clotrimazole, a selective blocker of intermediate conductance Ca(2+)-activated K(+) channels but not chromanol 293B, a selective blocker of cAMP-activated K(+) channels (KCNQ1), significantly inhibited CaSR activator-induced DBS, which was similar in wild-type and KCNQ1 knockout mice. HCO3 (-) fluxes across epithelial cells were activated by a CFTR activator, but blocked by a CFTR inhibitor. CaSR activators induced HCO3 (-) fluxes, which were inhibited by a receptor-operated channel (ROC) blocker. Moreover, CaSR activators dose-dependently raised cellular [Ca(2+)]cyt, which was abolished in Ca(2+)-free solutions and inhibited markedly by selective CaSR antagonist calhex 231, and ROC blocker in both animal and human intestinal epithelial cells. Taken together, CaSR activation triggers Ca(2+)-dependent DBS, likely through the ROC, intermediate conductance Ca(2+)-activated K(+) channels, and CFTR channels. This study not only reveals that [Ca(2+)]cyt signaling is critical to modulate DBS but also provides novel insights into the molecular mechanisms of CaSR-mediated Ca(2+)-induced DBS.
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Affiliation(s)
- Rui Xie
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China, the Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi 563003, China, and
| | - Xiao Dong
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Chase Wong
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Volker Vallon
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093, the Veterans Affairs San Diego Healthcare System, La Jolla, California 92161
| | - Bo Tang
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Jun Sun
- the Departments of Biochemistry, Internal Medicine (GI), and Microbiology/Immunology, Rush University, Chicago, Illinois 60612
| | - Shiming Yang
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China,
| | - Hui Dong
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China, the Department of Medicine, University of California, San Diego, La Jolla, California 92093,
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Helicobacter pylori activates calpain via toll-like receptor 2 to disrupt adherens junctions in human gastric epithelial cells. Infect Immun 2011; 79:3887-94. [PMID: 21825064 DOI: 10.1128/iai.05109-11] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Helicobacter pylori is a risk factor for the development of gastritis, gastroduodenal ulcers, and gastric adenocarcinoma. H. pylori-induced disruption of epithelial adherens junctions (AJs) is thought to promote the development of severe disease; however, the mechanisms whereby H. pylori alters AJ structure remain incompletely understood. The present study demonstrates that H. pylori infection in human patients is associated with elevated serum levels of an 80-kDa E-cadherin ectodomain, whose presence is independent of the presence of serum antibodies against CagA. In vitro, a heat-labile H. pylori surface component activates the host protease calpain in human gastric MKN45 cells independently of the virulence factors CagA and VacA. H. pylori-induced calpain activation results in cleavage of E-cadherin to produce a 100-kDa truncated form and induce relocalization of E-cadherin and β-catenin. Stimulation of MKN45 cells with the toll-like receptor 2 (TLR2) ligand P3C activated calpain and disrupted E-cadherin and β-catenin in a pattern similar to that induced by H. pylori. Inhibition of TLR2 prevented H. pylori-induced calpain activation and AJ disassembly. Together, these findings identify a novel pathway whereby H. pylori activates calpain via TLR2 to disrupt gastric epithelial AJ structure.
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van der Merwe JQ, Moreau F, MacNaughton WK. Protease-activated receptor-2 stimulates intestinal epithelial chloride transport through activation of PLC and selective PKC isoforms. Am J Physiol Gastrointest Liver Physiol 2009; 296:G1258-66. [PMID: 19359428 DOI: 10.1152/ajpgi.90425.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Serine proteases play important physiological roles through their activity at G protein-coupled protease-activated receptors (PARs). We examined the roles that specific phospholipase (PL) C and protein kinase (PK) C (PKC) isoforms play in the regulation of PAR(2)-stimulated chloride secretion in intestinal epithelial cells. Confluent SCBN epithelial monolayers were grown on Snapwell supports and mounted in modified Ussing chambers. Short-circuit current (I(sc)) responses to basolateral application of the selective PAR(2) activating peptide, SLIGRL-NH(2), were monitored as a measure of net electrogenic ion transport caused by PAR(2) activation. SLIGRL-NH(2) induced a transient I(sc) response that was significantly reduced by inhibitors of PLC (U73122), phosphoinositol-PLC (ET-18), phosphatidylcholine-PLC (D609), and phosphatidylinositol 3-kinase (PI3K; LY294002). Immunoblot analysis revealed the phosphorylation of both PLCbeta and PLCgamma following PAR(2) activation. Pretreatment of the cells with inhibitors of PKC (GF 109203X), PKCalpha/betaI (Gö6976), and PKCdelta (rottlerin), but not PKCzeta (selective pseudosubstrate inhibitor), also attenuated this response. Cellular fractionation and immunoblot analysis, as well as confocal immunocytochemistry, revealed increases of PKCbetaI, PKCdelta, and PKCepsilon, but not PKCalpha or PKCzeta, in membrane fractions following PAR(2) activation. Pretreatment of the cells with U73122, ET-18, or D609 inhibited PKC activation. Inhibition of PI3K activity only prevented PKCdelta translocation. Immunoblots revealed that PAR(2) activation induced phosphorylation of both cRaf and ERK1/2 via PKCdelta. Inhibition of PKCbetaI and PI3K had only a partial effect on this response. We conclude that basolateral PAR(2)-induced chloride secretion involves activation of PKCbetaI and PKCdelta via a PLC-dependent mechanism resulting in the stimulation of cRaf and ERK1/2 signaling.
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van der Merwe JQ, Ohland CL, Hirota CL, MacNaughton WK. Prostaglandin E2 derived from cyclooxygenases 1 and 2 mediates intestinal epithelial ion transport stimulated by the activation of protease-activated receptor 2. J Pharmacol Exp Ther 2009; 329:747-52. [PMID: 19190238 DOI: 10.1124/jpet.108.145466] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proteinase-activated receptor (PAR)(2) is activated by trypsin-like serine proteinases and has been implicated in intestinal inflammation. However, its role in the regulation of intestinal mucosal function remains unclear. Using the intestinal epithelial cell line, SCBN, we have studied the stimulus-secretion coupling mechanisms of PAR(2)-induced epithelial chloride transport, focusing on cyclooxygenase (COX)-1 and COX-2 activities and prostaglandin (PG) E(2) secretion. SCBN monolayers were grown on Snapwell supports, mounted in modified Ussing chambers, and exposed to the activating peptide, SLIGRL-NH(2) (50 microM), to activate PAR(2). Pretreatment with inhibitors of cytosolic PLA(2) (cPLA(2)) (AACOCF3, arachidonyltrifluoromethyl ketone), COX-1 [SC560, 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole], and COX-2 (celecoxib) resulted in a significant concentration-dependent attenuation of PAR(2)-induced changes in short-circuit current. Immunoblot analysis showed a PAR(2)-induced increase in cPLA(2) phosphorylation that was blocked by the mitogen-activated protein kinase kinase inhibitor, PD98059 [2-(2-amino-3methoxyphenyl)-4H-1benzopyran-4-one, C(16)H(13)NO(3)], and the pan-protein kinase C inhibitor, GFX (bisindolylmaleimide). PAR(2) stimulation also resulted in a large increase in the production of PGE(2) as determined by enzyme-linked immunosorbent assay and was also blocked by PD98059 and GFX. Immunofluorescence and immunoblot analysis determined that EP2 and EP4 are expressed at the basolateral membrane of SCBN cells. Through the use of selective inhibitors (EP2, AH6809 [6-isopropoxy-9-oxoxanthene-2-carboxylic acid]; EP4, GW627368X [N-[2[4,9-diethoxy-1-oxo-1,3-dihydro-2H-benzo[f]isoindol-2-yl)phenyl] acetyl]benzene sulphonamide]), it was found that both EP2 and EP4 were involved in mediating the PAR(2)-induced chloride secretory response. We conclude that basolateral PAR(2) activation induces epithelial chloride secretion that is mediated by cPLA(2), COX-1, COX-2, and the subsequent release of PGE(2). The production of PGE(2) results in an autocrine secretory response that is dependent on basolateral EP2 and EP4 receptors.
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