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Amplification and bioinformatics analysis of conserved FAD-binding region of L-amino acid oxidase ( LAAO) genes in gastropods compared to other organisms. Comput Struct Biotechnol J 2018; 16:98-107. [PMID: 30591829 PMCID: PMC6303269 DOI: 10.1016/j.csbj.2018.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 02/25/2018] [Accepted: 02/25/2018] [Indexed: 11/24/2022] Open
Abstract
This study aimed to investigate the conserved FAD-binding region of the L-amino acid oxidase (LAAO) genes in twelve gastropod genera commonly found in Thailand compared to those in other organisms using molecular cloning, nucleotide sequencing and bioinformatics analysis. Genomic DNA of gastropods and other invertebrates was extracted and screened using primers specific to the conserved FAD-binding region of LAAO. The amplified 143-bp fragments were cloned and sequenced. The obtained nucleotide sequences of 21 samples were aligned and phylogenetically compared to the LAAO-conserved FAD-binding regions of 210 other organisms from the NCBI database. Translated amino acid sequences of these samples were used in phylogenetics and pattern analyses. The phylogenetic trees showed clear separation of the conserved regions in fungi, invertebrates, and vertebrates. Alignment of the conserved 47-amino-acid FAD-binding region of the LAAOs showed 150 unique sequences among the 231 samples and these patterns were different from those of other flavoproteins in the amine oxidase family. An amino acid pattern analysis of five sub-regions (bFAD, FAD, FAD-GG, GG, and aGG) within the FAD-binding sequence showed high variation at the FAD-GG sub-region. Pattern analysis of secondary structures indicated the aGG sub-region as having the highest structural variation. Cluster analysis of these patterns revealed two major clusters representing the mollusc clade and the vertebrate clade. Thus, molecular phylogenetics and pattern analyses of sequence and structural variations could reflect evolutionary relatedness and possible structural conservation to maintain specific function within the FAD-binding region of the LAAOs in gastropods compared to other organisms.
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Turumin JL, Shanturov VA, Turumina HE. The role of the gallbladder in humans. REVISTA DE GASTROENTEROLOGÍA DE MÉXICO 2013; 78:177-87. [PMID: 23683886 DOI: 10.1016/j.rgmx.2013.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 01/28/2013] [Accepted: 02/18/2013] [Indexed: 12/30/2022]
Abstract
The basic function of the gallbladder in humans is one of protection. The accumulation of the primary bile acids (cholic acid and chenodeoxycholic acid) in the gallbladder reduces the formation of the secondary bile acids (deoxycholic acid and lithocholic acid), thus diminishing their concentration in the so-called gallbladder-independent enterohepatic circulation and protecting the liver, the stomach mucosa, the gallbladder, and the colon from their toxic hydrophobic effects. The presence or absence of the gallbladder in mammals is a determining factor in the synthesis of hydrophobic or hydrophilic bile acids. Because the gallbladder contracts 5-20 min after food is in the stomach and the "gastric chyme" moves from the stomach to the duodenum 1-3 h later, the function of the gallbladder bile in digestion may be insignificant. The aim of this article was to provide a detailed review of the role of the gallbladder and the mechanisms related to bile formation in humans.
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Affiliation(s)
- J L Turumin
- Department of Experimental Surgery, State Establishment Scientific Centre of Reconstructive and Restorative Surgery, Siberian Branch, Russian Academy of Medical Sciences, Irkutsk, Russia.
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Abstract
PURPOSE We investigated the role that the cystic fibrosis transmembrane conductance regulator (CFTR) may play in Cl(-) transport in the acinar and ductal epithelial cells of rabbit lacrimal gland (LG). METHODS Primary cultured LG acinar cells were processed for whole-cell patch-clamp electrophysiological recording of Cl(-) currents by using perfusion media with high and low [Cl(-)], 10 µM forskolin and 100 µM 3-isobutyl-1-methylxanthine (IBMX), the non-specific Cl(-) channel blocker 4,4'-disothiocyanostilbene-2, 2' sulphonic acid (DIDS; 100 µM) and CFTRinh-172 (10 µM), a specific blocker for CFTR. Ex vivo live cell imaging of [Cl(-)] changes in duct cells was performed on freshly dissected LG duct with a multiphoton confocal laser scanning microscope using a Cl(-) sensitive fluorescence dye, N-[ethoxycarbonylmethyl]-6-methoxy-quinolinium bromide. RESULTS Whole-cell patch-clamp studies demonstrated the presence of Cl(-) current in isolated acinar cells and revealed that this Cl(-) current was mediated by CFTR channel. Live cell imaging also showed the presence of CFTR-mediated Cl(-) transport across the plasma membrane of duct cells. CONCLUSIONS Our previous data showed the presence of CFTR in all acinar and duct cells within the rabbit LG, with expression most prominent in the apical membranes of duct cells. The present study demonstrates that CFTR is actively involved in Cl(-) transport in both acinar cells and epithelial cells from duct segments, suggesting that CFTR may play a significant role in LG secretion.
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Affiliation(s)
- Michael Lu
- Department of Cell and Neurobiology, Doheny Eye Institute, University of Southern California, Los Angeles, CA, USA
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Chuanqing Ding
- Department of Cell and Neurobiology, Doheny Eye Institute, University of Southern California, Los Angeles, CA, USA
- Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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Pereira M, Parker J, Stratford F, McPherson M, Dormer R. Activation mechanisms for the cystic fibrosis transmembrane conductance regulator protein involve direct binding of cAMP. Biochem J 2007; 405:181-9. [PMID: 17381427 PMCID: PMC1925253 DOI: 10.1042/bj20061879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 03/23/2007] [Accepted: 03/23/2007] [Indexed: 11/17/2022]
Abstract
The CFTR [CF (cystic fibrosis) transmembrane conductance regulator] chloride channel is activated by cyclic nucleotide-dependent phosphorylation and ATP binding, but also by non-phosphorylation-dependent mechanisms. Other CFTR functions such as regulation of exocytotic protein secretion are also activated by cyclic nucleotide elevating agents. A soluble protein comprising the first NBD (nucleotide-binding domain) and R-domain of CFTR (NBD1-R) was synthesized to determine directly whether CFTR binds cAMP. An equilibrium radioligand-binding assay was developed, firstly to show that, as for full-length CFTR, the NBD1-R protein bound ATP. Half-maximal displacement of [3H]ATP by non-radioactive ATP at 3.5 microM and 3.1 mM was demonstrated. [3H]cAMP bound to the protein with different affinities from ATP (half-maximal displacement by cAMP at 2.6 and 167 microM). Introduction of a mutation (T421A) in a motif predicted to be important for cyclic nucleotide binding decreased the higher affinity binding of cAMP to 9.2 microM. The anti-CFTR antibody (MPNB) that inhibits CFTR-mediated protein secretion also inhibited cAMP binding. Thus binding of cAMP to CFTR is consistent with a role in activation of protein secretion, a process defective in CF gland cells. Furthermore, the binding site may be important in the mechanism by which drugs activate mutant CFTR and correct defective DeltaF508-CFTR trafficking.
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Key Words
- camp
- cyclic nucleotide
- cystic fibrosis transmembrane conductance regulator
- ligand binding
- mutation
- protein secretion
- bca, bicinchoninic acid
- 8-cpt, 8-(4-chlorophenyl)thio
- cf, cystic fibrosis
- cftr, cf transmembrane conductance regulator
- epac, exchange protein directly activated by camp
- gef, guanine exchange factor
- iptg, isopropyl β-d-thiogalactoside
- nbd, nucleotide-binding domain
- ni-nta, ni2+-nitrilotriacetate
- pde, cyclic nucleotide phosphodiesterase
- pka, protein kinase a (or camp-dependent protein kinase)
- pka-i, pka inhibitor peptide
- pka-r, regulatory subunit of pka
- tnp-atp, 2′-o-(trinitrophenyl)-atp
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Affiliation(s)
- Malcolm M. C. Pereira
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff CF14 4XN, U.K
| | - Jody Parker
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff CF14 4XN, U.K
| | - Fiona L. L. Stratford
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff CF14 4XN, U.K
| | - Margaret McPherson
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff CF14 4XN, U.K
| | - Robert L. Dormer
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff CF14 4XN, U.K
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Kuver R, Wong T, Klinkspoor JH, Lee SP. Absence of CFTR is associated with pleiotropic effects on mucins in mouse gallbladder epithelial cells. Am J Physiol Gastrointest Liver Physiol 2006; 291:G1148-54. [PMID: 16825704 DOI: 10.1152/ajpgi.00547.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mucus of cystic fibrosis patients exhibits altered biochemical composition and biophysical behavior, but the causal relationships between altered cystic fibrosis transmembrane conductance regulator (CFTR) function and the abnormal mucus seen in various organ systems remain unclear. We used cultured gallbladder epithelial cells (GBEC) from wild-type and Cftr((-/-)) mice to investigate mucin gene and protein expression, kinetics of postexocytotic mucous granule content expansion, and biochemical and ionic compositions of secreted mucins. Muc1, Muc3, Muc4, Muc5ac, and Muc5b mRNA levels were significantly lower in Cftr((-/-)) GBEC compared with wild-type cells, whereas Muc2 mRNA levels were higher in Cftr((-/-)) cells. Quantitative immunoblotting demonstrated a trend toward lower MUC1, MUC2, MUC3, MUC5AC, and MUC5B mucin levels in Cftr((-/-)) cells compared with cells from wild-type mice. In contrast, the levels of secreted MUC1, MUC3, MUC5B, and MUC6 mucins were significantly higher from Cftr((-/-)) cells; a trend toward higher levels of secreted MUC2 and MUC5AC was also noted from Cftr((-/-)) cells. Cftr((-/-)) cells demonstrated slower postexocytotic mucous granule content expansion. Calcium concentration was significantly elevated in the mucous gel secreted by Cftr((-/-)) cells compared with wild-type cells. Secreted mucins from Cftr((-/-)) cells contained higher sulfate concentrations. Thus absence of CFTR is associated with pleiotropic effects on mucins in murine GBEC.
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Affiliation(s)
- Rahul Kuver
- Division of Gastroenterology, Department of Medicine, University of Washington, Seattle, WA 98195, USA.
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Shen H, Fan Y, Yang X, Burczynski FJ, Li P, Gong Y. Increased expression of cystic fibrosis transmembrane conductance regulator in rat liver after common bile duct ligation. J Cell Physiol 2005; 203:599-603. [PMID: 15605366 DOI: 10.1002/jcp.20259] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Liver disease associated with cystic fibrosis (CF) has been increasingly diagnosed and recognized as one of the major causes of death in CF during recent years. The autosomal-recessive disorder of CF results from mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) that encodes the CFTR protein. Due to its existence and multifunction in biliary epithelial, over- or less-expression of CFTR in the liver may play an important role in the development of CF liver disease (CFLD). The aim of current study is to investigate the expression of CFTR in the liver of common bile duct ligated (BDL) rats. After BDL, there was an increase in the abundance of CFTR mRNA and protein. Immunohistochemical staining also demonstrated an increased intensity of CFTR staining in the liver tissue section. In conclusion, there is an increased expression of CFTR in the liver after common BDL.
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Affiliation(s)
- Hong Shen
- Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada
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Kunzelmann K, Mall M. Pharmacotherapy of the ion transport defect in cystic fibrosis: role of purinergic receptor agonists and other potential therapeutics. ACTA ACUST UNITED AC 2004; 2:299-309. [PMID: 14719996 DOI: 10.1007/bf03256658] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cystic fibrosis (CF), is an autosomal recessive disease frequently seen in the Caucasian population. It is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF is characterized by enhanced airway Na(+) absorption, mediated by epithelial Na(+) channels (ENaC), and deficient Cl(-) transport. In addition, other mechanisms may contribute to the pathophysiological changes in the CF lung, such as defective regulation of HCO(3)(-) secretion. In other epithelial tissues, epithelial Na(+) conductance is either increased (intestine) or decreased (sweat duct) in CF. CFTR is a cyclic AMP-regulated epithelial Cl(-) channel, and appears to control the activity of several other transport proteins. Accordingly, defective epithelial ion transport in CF is likely to be a combination of defective Cl(-) channel function and impaired regulator function of CFTR, which in turn is linked to impaired mucociliary clearance and development of chronic lung disease. As the clinical course of CF is determined primarily by progressive lung disease, novel pharmacological strategies for the treatment of CF focus on correction of the ion transport defect in the airways. In recent years, it has been demonstrated that activation of purinergic receptors in airway epithelia by extracellular nucleotides (adenosine triphosphate/uridine triphosphate) has beneficial effects on mucus clearance in CF. Activation of the dominant class of metabotropic purinergic receptors, P2Y(2) receptors, appears to have a 2-fold benefit on ion transport in CF airways; excessive Na(+) absorption is attenuated, most likely by inhibition of the ENaC and, simultaneously, an alternative Ca(2+)-dependent Cl(-) channel is activated that may compensate for the CFTR Cl(-) channel defect. Thus activation of P2Y(2) receptors is expected to lead to improved hydration of the airway surface liquid in CF. Furthermore, purinergic activation has been shown to promote other components of mucociliary clearance such as ciliary beat frequency and mucus secretion. Clinical trials are under way to test the effect of synthetic purinergic compounds, such as the P2Y(2) receptor agonist INS37217, on the progression of lung disease in patients with CF. Administration of these compounds alone, or in combination with other drugs that inhibit accelerated Na(+) transport and help recover or increase residual activity of mutant CFTR, is most promising as successful therapy to counteract the ion transport defect in the airways of CF patients.
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Affiliation(s)
- Karl Kunzelmann
- Physiologisches Institut, Universitäts Regensburg, Regensburg, Germany.
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Lee J, Tauscher A, Seo DW, Oram JF, Kuver R. Cultured gallbladder epithelial cells synthesize apolipoproteins A-I and E. Am J Physiol Gastrointest Liver Physiol 2003; 285:G630-41. [PMID: 12773300 DOI: 10.1152/ajpgi.00101.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gallbladder epithelial cells (GBEC) are exposed to high and fluctuating concentrations of biliary cholesterol on their apical (AP) surface. GBEC absorb and efflux cholesterol, but the mechanisms of cholesterol uptake, intracellular trafficking, and efflux in these cells are not known. We previously reported that ATP binding cassette (ABC)A1 mediates basolateral (BL) cholesterol efflux in cultured polarized GBEC. In addition, the nuclear hormone receptors liver X receptor (LXR)alpha and retinoid X receptor (RXR) mediate both AP and BL cholesterol efflux. An interesting finding from our previous study was that apolipoprotein (apo)A-I applied to the AP surfaces of cells elicited BL ABCA1-mediated cholesterol efflux. Because ABCA1-mediated cholesterol efflux requires the presence of a cholesterol acceptor, we hypothesized that GBEC synthesize and secrete endogenous apo into the BL compartment. Here, we demonstrate that cholesterol loading of cells with model bile and AP apoA-I treatment is associated with an increase in the synthesis of apoE mRNA and protein. Furthermore, apoE is secreted into the BL compartment. LXRalpha/RXR ligands stimulate the synthesis of endogenous apoA-I mRNA and protein, as well as apoE mRNA. BL secretion of apoA-I is elicited by LXRalpha/RXR ligands. Therefore, GBEC synthesize apoA-I and -E and efflux cholesterol using ABCA1- and non-ABCA1- mediated pathways. These processes may alter gallbladder biliary cholesterol concentrations and thereby influence gallstone formation.
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Affiliation(s)
- Jin Lee
- Division of Gastroenterology, University of Washington, Seattle, WA 98195, USA
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Affiliation(s)
- Andrew P Feranchak
- Department of Pediatrics, Children's Hospital and the University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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Kim HJ, Lee SK, Kim MH, Son JM, Lee SS, Park JS, Seo DW, Min YI. Cystic fibrosis transmembrane conductance regulators (CFTR) in biliary epithelium of patients with hepatolithiasis. Dig Dis Sci 2002; 47:1758-65. [PMID: 12184527 DOI: 10.1023/a:1016488327019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) has been considered to be involved in the regulatory pathway of biliary mucin secretion. We investigated expression of CFTR protein and mRNA in 24 livers with hepatolithiasis, in 6 with cholangiocarcinoma, and in 12 histologically normal livers. According to the histologic features of chronic proliferative cholangitis, hepatolithiasis was subdivided into inflammatory cell infiltration predominant (N = 14) and fibrosis predominant (N = 10). The mean signal density of CFTR in overall hepatolithiasis and in histologically normal livers was 1.23 +/- 0.15 and 1.01 +/- 0.13, respectively (P > 0.05). The CFTR protein (1.60 +/- 0.18) and mRNA (1.09 +/- 0.15) in inflammatory cell infiltration predominant patients were significantly higher (CFTR protein, 1.01 +/- 0.13; mRNA, 0.75 +/- 0.11) than in control subjects (P < 0.05), whereas those in fibrosis-predominant patients (CFTR protein, 0.72 +/- 0.15; mRNA, 0.55 +/- 0.13) were less than in control subjects (P < 0.05). CFTR protein (1.27 +/- 0.17) in patients with cholangiocarcinoma was not different from that of control subjects (1.01 +/- 0.13). CFTR expression in hepatolithiasis patients was rather heterogeneous but was closely related to the histology of bile ducts.
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Affiliation(s)
- Hong-Ja Kim
- Department of Internal Medicine University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
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Lee J, Shirk A, Oram JF, Lee SP, Kuver R. Polarized cholesterol and phospholipid efflux in cultured gall-bladder epithelial cells: evidence for an ABCA1-mediated pathway. Biochem J 2002; 364:475-84. [PMID: 12023891 PMCID: PMC1222593 DOI: 10.1042/bj20011493] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Gall-bladder epithelial cells (GBEC) are exposed to high concentrations of cholesterol in bile. Whereas cholesterol absorption by GBEC is established, the fate of this absorbed cholesterol is not known. The aim of this study was to determine whether ABCA1 (ATP-binding cassette transporter A1) mediates cholesterol efflux in GBEC. Polarized canine GBEC were cultured on porous membrane filters allowing separate access to apical (AP) and basolateral (BL) compartments. After AP loading of cells with model bile and [14C]cholesterol, cholesterol efflux was measured. Cholesterol loading together with 8-bromo-cAMP treatment, which increased ABCA1 expression, led to a significant increase in cholesterol efflux with apolipoprotein A-I (apoA-I) as the acceptor. Cholesterol efflux was observed predominantly into the BL compartment. Similar results were found for phospholipid efflux. Confocal immunofluorescence microscopy showed a predominantly BL ABCA1 localization. Interestingly, apoA-I added to either the AP or the BL compartments elicited BL lipid efflux with cAMP treatment. No paracellular or transcellular passage of 125I-apoA-I occurred. Ligands for the nuclear hormone receptors liver X receptor alpha (LXRalpha) and retinoid X receptor (RXR) elicited AP and BL cholesterol efflux, suggesting the involvement of both ABCA1- and non-ABCA1-mediated pathways. In summary, BL cholesterol/phospholipid efflux consistent with an ABCA1-mediated mechanism occurs in GBEC. This efflux pathway is stimulated by cAMP and by LXRalpha/RXR ligands, and in the case of the cAMP pathway appears to involve a role for biliary apoA-I.
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Affiliation(s)
- Jin Lee
- Division of Gastroenterology, Box 356424, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA
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Kunzelmann K, Mall M. Electrolyte transport in the mammalian colon: mechanisms and implications for disease. Physiol Rev 2002; 82:245-89. [PMID: 11773614 DOI: 10.1152/physrev.00026.2001] [Citation(s) in RCA: 449] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The colonic epithelium has both absorptive and secretory functions. The transport is characterized by a net absorption of NaCl, short-chain fatty acids (SCFA), and water, allowing extrusion of a feces with very little water and salt content. In addition, the epithelium does secret mucus, bicarbonate, and KCl. Polarized distribution of transport proteins in both luminal and basolateral membranes enables efficient salt transport in both directions, probably even within an individual cell. Meanwhile, most of the participating transport proteins have been identified, and their function has been studied in detail. Absorption of NaCl is a rather steady process that is controlled by steroid hormones regulating the expression of epithelial Na(+) channels (ENaC), the Na(+)-K(+)-ATPase, and additional modulating factors such as the serum- and glucocorticoid-regulated kinase SGK. Acute regulation of absorption may occur by a Na(+) feedback mechanism and the cystic fibrosis transmembrane conductance regulator (CFTR). Cl(-) secretion in the adult colon relies on luminal CFTR, which is a cAMP-regulated Cl(-) channel and a regulator of other transport proteins. As a consequence, mutations in CFTR result in both impaired Cl(-) secretion and enhanced Na(+) absorption in the colon of cystic fibrosis (CF) patients. Ca(2+)- and cAMP-activated basolateral K(+) channels support both secretion and absorption of electrolytes and work in concert with additional regulatory proteins, which determine their functional and pharmacological profile. Knowledge of the mechanisms of electrolyte transport in the colon enables the development of new strategies for the treatment of CF and secretory diarrhea. It will also lead to a better understanding of the pathophysiological events during inflammatory bowel disease and development of colonic carcinoma.
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Affiliation(s)
- Karl Kunzelmann
- Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Queensland, Brisbane, Australia.
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Mailleau C, Paul A, Colin M, Xing PX, Guernier C, Bernaudin JF, Capeau J, Brahimi-Horn MC. Glycoconjugate metabolism in a cystic fibrosis knockout mouse model. Mol Genet Metab 2001; 72:122-31. [PMID: 11161838 DOI: 10.1006/mgme.2000.3131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cystic fibrosis knockout mice (cftr(-/-)) die prematurely of obstruction of the intestine which may result from accumulation of dehydrated glycoconjugate-containing mucus. We noted an increase in the specific activity of [(14)C]glucosamine-labeled high-molecular weight glycoconjugates, probably mucin, in the lumen of the intestine of cftr(-/-) (homozygous) mice compared to cftr(+/+) (wild-type) and cftr(+/-) (heterozygous) mice and a decrease in the turnover of glycoconjugates of several organs of the cftr(-/-) mice. No difference in the anionic composition of secreted intestinal glycoconjugates was detected and no difference in the amount of mucin 1 (Muc1) was found in the small intestine, colon, pancreas, and lungs of the different genotypes. In addition, the spleen of the cftr(-/-) mice was significantly smaller than that of control mice and the small intestine and colon were, respectively, longer and shorter compared to control mice. These results indicate modified glycoconjugate metabolism in cystic fibrosis knockout mice and morphologic changes to the spleen and intestine where the latter modifications are possibly related to the intestinal malabsorption associated with cystic fibrosis.
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Affiliation(s)
- C Mailleau
- Institut National de la Santé et de la Recherche Médicale U 402, Faculté de Médecine Saint-Antoine, University Paris VI, Paris, France
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Kunzelmann K, Nitschke R. Defects in processing and trafficking of cystic fibrosis transmembrane conductance regulator. EXPERIMENTAL NEPHROLOGY 2000; 8:332-42. [PMID: 11014930 DOI: 10.1159/000020687] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In most epithelial tissues Cl(-) transport relies on the cystic fibrosis transmembrane conductance regulator (CFTR) which has dual function as a Cl(-) channel and as a regulator of other ion channels. More than 900 different mutations in the CFTR gene are the cause for defective transport of Cl(-) and Na(+) and impaired secretion or absorption of electrolytes in cystic fibrosis. However, the CFTR mutation delta F508 is the most common reason for the frequently inherited disease among the Caucasian population. Maturation and processing of delta F508-CFTR is defective which leads to expression of only very little but functional CFTR in the cell membrane. Understanding the processing and trafficking of CFTR may give a clue to the question as to how the expression and residual function of delta F508-CFTR can be enhanced, and may lead to the development of new pharmacological tools for the treatment of cystic fibrosis.
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Affiliation(s)
- K Kunzelmann
- Department of Physiology and Pharmacology, University of Queensland, St. Lucia, Brisbane, Australia.
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Seppen J, Barry SC, Klinkspoor JH, Katen LJ, Lee SP, Garcia JV, Osborne WR. Apical gene transfer into quiescent human and canine polarized intestinal epithelial cells by lentivirus vectors. J Virol 2000; 74:7642-5. [PMID: 10906219 PMCID: PMC112286 DOI: 10.1128/jvi.74.16.7642-7645.2000] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intestinal epithelial cells secrete a protective luminal mucus barrier inhibiting viral gene transfer. Quiescent, polarized monolayers of primary epithelial cells from dog gallbladder and human colon are efficiently transduced through the apical mucus side by lentivirus vectors, suggesting their application to intestinal gene therapy.
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Affiliation(s)
- J Seppen
- Department of Pediatrics, School of Medicine, University of Washington, Washington, USA
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Mak GZ, Harberg FJ, Hiatt P, Deaton A, Calhoon R, Brandt ML. T-tube ileostomy for meconium ileus: four decades of experience. J Pediatr Surg 2000; 35:349-52. [PMID: 10693694 DOI: 10.1016/s0022-3468(00)90038-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND/PURPOSE The T-tube ileostomy was first used at Texas Children's Hospital in 1959. The purpose of this study is to update the experience since the initial report of this technique in 1981. METHODS A database of 448 patients with cystic fibrosis (CF) seen in the authors' institution was used to identify 83 patients (18.5%) who presented with meconium ileus. The clinic and hospital charts of these patients were reviewed retrospectively to identify patients who had undergone placement of a T-tube ileostomy. RESULTS Surgery was performed in 60 of 83 patients for complications of meconium ileus or failure to evacuate the meconium after a contrast enema. Of these patients, 21 of 60 (35%) underwent placement of a T-tube ileostomy. An additional 8 patients were identified who underwent placement of a T-tube ileostomy but were not included in the CF database, for a total of 29 patients who have been treated with T-tube ileostomy since 1959 at Texas Children's Hospital. Five patients were excluded from analysis because of insufficient data or misdiagnosis. One of the 24 patients in the series died of complications of prematurity. A total of 20 of 23 patients had resolution of their meconium ileus after T-tube irrigation with n-acetylcysteine or pancreatic enzymes. Three patients required additional surgery to relieve persistent bowel obstruction. All patients had the T-tube removed within the first 8 weeks after surgery. Two patients required subsequent repair of an incisional hernia. There were otherwise no complications of this procedure, with an average follow-up of 11.5 years. CONCLUSION In patients with uncomplicated meconium ileus unrelieved by contrast enema, the T-tube ileostomy is an effective and safe treatment.
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Affiliation(s)
- G Z Mak
- Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
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17
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Moser AJ, Abedin MZ, Morgenstern KE, Abedin ZR, Roslyn JJ. Endogenous prostaglandins modulate chloride secretion by prairie dog gallbladder. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 2000; 135:82-8. [PMID: 10638698 DOI: 10.1016/s0022-2143(00)70024-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In addition to concentrating bile, the gallbladder secretes chloride (Cl-) and mucus into its lumen. We recently observed that gallbladder Cl- secretion is increased in prairie dogs during the formation of cholesterol crystals, a period of altered mucosal prostaglandin synthesis. Pathologic Cl- secretion is characteristic of other epithelial disorders such as cystic fibrosis and hypercalciuric nephrolithiasis and may be important in gallstone pathogenesis. We hypothesized that concentrations of endogenous prostaglandin E2 (PGE2) found during experimental gallstone formation may mediate increased Cl- secretion by prairie dog gallbladder. Prairie dog gallbladders were harvested by cholecystectomy and mounted in Ussing chambers. Unidirectional transepithelial Cl-, Na+, and H20 fluxes were measured before and after inhibition of endogenous prostaglandin synthesis with 10 micromol/L indomethacin. Gallbladders were then exposed to increasing concentrations of PGE2 to a maximal dose of 1 micromol/L, as found in animals with gallstones. Standard electrophysiologic parameters were recorded simultaneously. Indomethacin increased mucosal resistance and stimulated gallbladder Na+ and Cl- absorption. These effects were rapidly reversed by PGE2. PGE2 promoted Cl- secretion and decreased mucosal Na+ absorption at concentrations found in the gallbladder bile of animals with gallstones. Endogenous prostaglandin metabolism modulates gallbladder Cl- secretion and may promote changes in Cl- transport associated with cholelithiasis.
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Affiliation(s)
- A J Moser
- Department of Surgery, University of Pittsburgh School of Medicine, Pennsylvania 15213, USA
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18
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Schwiehert EM, Rozmahel R. Chapter 6 The cystic fibrosis transmembrane conductance regulator in the gastrointestinal system. CURRENT TOPICS IN MEMBRANES 2000. [DOI: 10.1016/s1063-5823(00)50008-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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McPherson MA, Pereira MM, Lloyd Mills C, Murray KJ, Dormer RL. A cyclic nucleotide PDE5 inhibitor corrects defective mucin secretion in submandibular cells containing antibody directed against the cystic fibrosis transmembrane conductance regulator protein. FEBS Lett 1999; 464:48-52. [PMID: 10611481 DOI: 10.1016/s0014-5793(99)01672-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A selective cyclic nucleotide PDE5 inhibitor corrected the defective mucin secretion response to the beta-agonist isoproterenol in submandibular acinar cells inhibited by antibody directed against the cystic fibrosis transmembrane conductance regulator. The PDE5 inhibitor was as effective as cpt-cyclic AMP or a selective PDE4 inhibitor. However, the PDE5 inhibitor had no effect on basal or isoproterenol-stimulated cyclic AMP levels and did not stimulate mucin secretion. The results showing, for the first time, correction of the CFTR mucin secretion defect by a PDE5 inhibitor, which may involve cyclic GMP, will have a major impact in development of a rational drug treatment for cystic fibrosis.
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Affiliation(s)
- M A McPherson
- Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff, UK
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20
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Abstract
Cystic fibrosis (CF) is a common genetic disease for which the gene was identified within the last decade. Pulmonary disease predominates in this ultimately fatal disease and current therapy only slows the progression. CF transmembrane regulator (CFTR), the gene product, is an integral membrane glycoprotein that normally functions as a chloride channel in epithelial cells. The most common mutation, deltaF508, results in mislocalization and altered glycosylation of CFTR. Altered fucosylation and sialylation are hallmarks of both membrane and secreted glycoproteins in CF and the focus here is on these investigations. Oligosaccharides from CF membrane glycoproteins have the Lewis x, selectin ligand in terminal positions. In addition, two major bacterial pathogens in CF, Pseudomonas aeruginosa and Haemophilus influenzae, have binding proteins, which recognize fucose in alpha1,3 linkage and asialoglycoconjugates. We speculate that the altered terminal glycosylation of airway epithelial glycoproteins in CF contributes to the chronic infection and robust inflammatory response in the CF lung. Understanding the effects of mutant CFTR on glycosylation may provide further insight into the regulation of glycoconjugate processing as well as therapy for CF.
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Affiliation(s)
- T F Scanlin
- Cystic Fibrosis Center, Children's Hospital of Philadelphia, PA 19104-4318, USA
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21
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Kälin N, Claass A, Sommer M, Puchelle E, Tümmler B. DeltaF508 CFTR protein expression in tissues from patients with cystic fibrosis. J Clin Invest 1999; 103:1379-89. [PMID: 10330420 PMCID: PMC408454 DOI: 10.1172/jci5731] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Heterologous expression of the cystic fibrosis transmembrane conductance regulator (CFTR) provided evidence that the major cystic fibrosis (CF) mutation DeltaF508 leads to defective protein folding in the endoplasmic reticulum, which prevents its processing and targeting to the cell surface. In this study, we investigated endogenous CFTR expression in skin biopsies and respiratory and intestinal tissue specimens from DeltaF508 homozygous and non-CF patients, using immunohistochemical and immunoblot analyses with a panel of CFTR antibodies. CFTR expression was detected at the luminal surface of reabsorptive sweat ducts and airway submucosal glands, at the apex of ciliated cells in pseudostratified respiratory epithelia and of isolated cells of the villi of duodenum and jejunum, and within intracellular compartments of intestinal goblet cells. In DeltaF508 homozygous patients, expression of the mutant protein proved to be tissue specific. Whereas DeltaF508 CFTR was undetectable in sweat glands, the expression in the respiratory and intestinal tracts could not be distinguished from the wild-type by signal intensity or localization. The tissue-specific variation of DeltaF508 CFTR expression from null to apparently normal amounts indicates that DeltaF508 CFTR maturation can be modulated and suggests that determinants other than CFTR mislocalization should play a role in DeltaF508 CF respiratory and intestinal disease.
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Affiliation(s)
- N Kälin
- Klinische Forschergruppe Molekulare Pathologie der Mukoviszidose, Medizinische Hochschule Hannover, D-30623 Hannover, Germany.
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22
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Choi J, Klinkspoor JH, Yoshida T, Lee SP. Lipopolysaccharide from Escherichia coli stimulates mucin secretion by cultured dog gallbladder epithelial cells. Hepatology 1999; 29:1352-7. [PMID: 10216115 DOI: 10.1002/hep.510290515] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Biliary infection is associated with mucin hypersecretion by the biliary epithelium. Mucins have been identified as potent pronucleators of cholesterol in bile. The aim of the present study was to determine whether lipopolysaccharides (LPS) from different bacteria are capable of stimulating mucin secretion by cultured dog gallbladder epithelial (DGBE) cells, and to investigate the mechanism by which LPS stimulate mucin secretion. Mucin secretion by confluent monolayers of DGBE cells was quantified by measuring the secretion of [3H]-N-acetyl-D-glucosamine-labeled glycoproteins. Cell viability was evaluated by measuring the leakage of the enzyme, lactate dehydrogenase (LDH), into the culture medium. LPS, derived from Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa (200 microg/mL), all caused an increase in mucin secretion by the DGBE cells, without causing concomitant cell lysis. LPS from E. coli was found to be the most potent stimulator of mucin secretion, and increased mucin secretion by the DGBE cells to 252% +/- 14% of control. LPS from E. coli had no effect on intracellular cyclic adenosine monophosphate (cAMP) levels in the DGBE cells. Addition of the nitric oxide (NO)-releasing compound, NOR-4 (0.125-1 mmol/L), to the cells did not result in increased mucin secretion, and the NO synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME) (4 or 10 mmol/L), did not inhibit the LPS-stimulated mucin secretion. Exogenous tumor necrosis factor alpha (TNF-alpha) (1-10 ng/mL) did cause a minor increase in mucin secretion by the DGBE cells, but the effect of LPS from E. coli on mucin secretion could not be inhibited by preincubation with a TNF-alpha antibody (10 microg/mL). We conclude that LPS stimulates mucin secretion by the gallbladder epithelium. Whether this stimulation is mediated by TNF-alpha remains to be determined.
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Affiliation(s)
- J Choi
- Department of Surgery, Chungbuk National University Hospital, Seoul, South Korea
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23
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Kunzelmann K. The cystic fibrosis transmembrane conductance regulator and its function in epithelial transport. Rev Physiol Biochem Pharmacol 1999; 137:1-70. [PMID: 10207304 DOI: 10.1007/3-540-65362-7_4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
CF is a well characterized disease affecting a variety of epithelial tissues. Impaired function of the cAMP activated CFTR Cl- channel appears to be the basic defect detectable in epithelial and non-epithelial cells derived from CF patients. Apart from cAMP-dependent Cl- channels also Ca2+ and volume activated Cl- currents may be changed in the presence of CFTR mutations. This is supported by recent additional findings showing that different intracellular messengers converge on the CFTR Cl- channel. Analysis of the ion transport in CF airways and intestinal epithelium identified additional defects in Na+ transport. It became clear recently that mutations of CFTR may also affect the activity of other membrane conductances including epithelial Na+ channels, KvLQT-1 K+ channels and aquaporins (Fig. 7). Several additional, initially unexpected effects of CFTR on cellular functions, such as exocytosis, mucin secretion and regulation of the intracellular pH were reported during the past. Taken together, these results clearly indicate that CFTR not only acts as a cAMP regulated Cl- channel, but may fulfill several other cellular functions, particularly by regulating other membrane conductances. Failure in CFTR dependent regulation of these membrane conductances is likely to contribute to the defects observed in CF. Currently, no general concept is available that can explain how CFTR controls this variety of cellular functions. Further studies will have to verify whether direct protein interaction, specific effects on membrane turnover, changes of the intracellular ion concentration or additional proteins are involved in these regulatory loops. At the end of this review one cannot share the provocative and reassuring title "CFTR!" of a review written a few years ago [114]. Today one might rather finish with the statement "CFTR?".
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Affiliation(s)
- K Kunzelmann
- Physiologisches Institut, Albert-Ludwigs-Universität Freiburg, Germany
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24
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Shoda J, Kano M, Asano T, Irimura T, Ueda T, Iwasaki R, Furukawa M, Kamiya J, Nimura Y, Todoroki T, Matsuzaki Y, Tanaka N. Secretory low-molecular-weight phospholipases A2 and their specific receptor in bile ducts of patients with intrahepatic calculi: factors of chronic proliferative cholangitis. Hepatology 1999; 29:1026-36. [PMID: 10094942 DOI: 10.1002/hep.510290440] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Intrahepatic calculi is characterized by an intractable course and frequent recurrences, requiring multiple operative interventions. Chronic proliferative cholangitis, an active and long-standing inflammation of the stone-containing bile ducts with the hyperplasia of epithelia and the proliferation of the duct-associated mucus glands, may underlie the complex nature of the disease. In terms of the pathophysiology, interest has been focused on the role of secretory low-molecular-weight phospholipases A2 (sPLA2s) as inflammatory mediators or factors modulating cell functions via their specific sPLA2-receptor, and also on the production and secretion of altered mucin molecules from the inflamed bile ducts. In search of factors involving chronic proliferative cholangitis, the sPLA2 isoforms in the bile such as the pancreatic-type sPLA2 (group IB sPLA2) and the arthritic-type sPLA2 (group IIA sPLA2), were assayed to correlate protein masses of the sPLA2s with alterations in biliary composition. Furthermore, the steady-state messenger RNA (mRNA) levels of the sPLA2s, the membrane-bound sPLA2-receptor, cystic fibrosis transmembrane conductance regulator (CFTR), and mucin core polypeptide (MUC) genes in the bile ducts were assayed by reverse- transcriptase polymerase chain reaction (RT-PCR). Immunoreactive sPLA2-IB and sPLA2-IIA levels were significantly higher in the bile from the stone-containing hepatic ducts (2315 +/- 677 for sPLA2-IB; 281 +/- 42 for sPLA2-IIA ng/dL, mean +/- SEM; n = 20) than in the ductal bile from gallbladder stone patients (609 +/- 92, P <.01; 22 +/- 2, P <.01; n = 24). The increased sPLA2 levels were associated with a concomitant increase in lysophosphatidylcholine, prostaglandin E2 (PGE2), and total mucin concentrations. The affected bile ducts showed an increased mRNA level of sPLA2-IB and sPLA2-IIA compared with the ducts from control subjects, in whom the mRNAs of the sPLA2-receptor and other sPLA2 isoforms, such as groups V and X sPLA2s, were coincidently expressed. Reflecting the increased amounts of total biliary mucins, the affected ducts showed an increase in mRNA levels of CFTR as well as MUC2, MUC3, MUC5AC, MUC5B, and MUC6 compared with the ducts from control subjects. In intrahepatic calculi, an enhanced expression of the sPLA2s and their possible cross-talk via sPLA2-receptor may be of pathophysiological significance for the chronic proliferative cholangitis, in association with the enhanced CFTR expression and the alterations in mucin gene expression in the bile ducts, probably through potentiating arachidonate metabolism with associated biliary alterations favoring growth of preexisting stones and even further progressions.
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Affiliation(s)
- J Shoda
- Department of Gastroenterology, Institute of Clinical Medicine, The University of Tsukuba, Ibaraki, Japan.
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25
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Abstract
Role of CFTR in Airway Disease. Physiol. Rev. 79, Suppl.: S215-S255, 1999. - Cystic fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR), which accounts for the cAMP-regulated chloride conductance of airway epithelial cells. Lung disease is the chief cause of morbidity and mortality in CF patients. This review focuses on mechanisms whereby the deletion or impairment of CFTR chloride channel function produces lung disease. It examines the major themes of the channel hypothesis of CF, which involve impaired regulation of airway surface fluid volume or composition. Available evidence indicates that the effect of CFTR deletion alters physiological functions of both surface and submucosal gland epithelia. At the airway surface, deletion of CFTR causes hyperabsorption of sodium chloride and a reduction in the periciliary salt and water content, which impairs mucociliary clearance. In submucosal glands, loss of CFTR-mediated salt and water secretion compromises the clearance of mucins and a variety of defense substances onto the airway surface. Impaired mucociliary clearance, together with CFTR-related changes in the airway surface microenvironment, leads to a progressive cycle of infection, inflammation, and declining lung function. Here, we provide the details of this pathophysiological cascade in the hope that its understanding will promote the development of new therapies for CF.
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Affiliation(s)
- J M Pilewski
- Departments of Medicine and of Cell Biology and Physiology, University of Pittsburgh, Pennsylvania, USA
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26
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Pereira MM, Lloyd Mills C, Dormer RL, McPherson MA. Actions of adenosine A1 and A2 receptor antagonists on CFTR antibody-inhibited beta-adrenergic mucin secretion response. Br J Pharmacol 1998; 125:697-704. [PMID: 9831904 PMCID: PMC1571032 DOI: 10.1038/sj.bjp.0702128] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The cystic fibrosis gene protein, the cystic fibrosis transmembrane conductance regulator (CFTR) acts as a chloride channel and is a key regulator of mucin secretion. The mechanism by which 3-isobutyl-1-methylxanthine (IBMX) corrects the defect in CFTR mediated beta-adrenergic stimulation of mucin secretion has not been determined. The present study has investigated the actions of adenosine A1 and A2 receptor antagonists to determine whether ability to stimulate mucin secretion correlates with correction of CFTR antibody inhibited beta-adrenergic response and whether excessive cyclic AMP rise is required. 2. CFTR antibodies were introduced into living rat submandibular acini by hypotonic swelling. Following recovery, mucin secretion in response to isoproterenol was measured. 3. The adenosine A1 receptor antagonist, 8 cyclopentyltheophylline (CPT) was a less potent stimulator of mucin secretion than was the A2 receptor antagonist dimethylpropargylxanthine (DMPX). A concentration of CPT close to the Ki for A1 receptor antagonism (10 nM) did not stimulate mucin secretion. 4. DMPX, although a potent stimulator of mucin secretion, did not correct CFTR antibody inhibited mucin secretion. 5. CPT corrected defective CFTR antibody inhibited mucin secretion at a high (1 mM) concentration, suggesting a mechanism other than adenosine receptor antagonism. 6. DMPX potentiated the isoproterenol induced cyclic AMP rise, whereas CPT did not. 7. Correction of the defective CFTR mucin secretion response did not correlate with ability to stimulate mucin secretion and did not require potentiation of beta-adrenergic induced increases in cyclic AMP. This affords real promise for the development of a selective drug treatment for cystic fibrosis.
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Affiliation(s)
- M M Pereira
- Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff
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27
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Short DB, Trotter KW, Reczek D, Kreda SM, Bretscher A, Boucher RC, Stutts MJ, Milgram SL. An apical PDZ protein anchors the cystic fibrosis transmembrane conductance regulator to the cytoskeleton. J Biol Chem 1998; 273:19797-801. [PMID: 9677412 DOI: 10.1074/jbc.273.31.19797] [Citation(s) in RCA: 358] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The function of the cystic fibrosis transmembrane conductance regulator (CFTR) as a Cl- channel in the apical membrane of epithelial cells is extensively documented. However, less is known about the molecular determinants of CFTR residence in the apical membrane, basal regulation of its Cl- channel activity, and its reported effects on the function of other transporters. These aspects of CFTR function likely require specific interactions between CFTR and unknown proteins in the apical compartment of epithelial cells. Here we report that CFTR interacts with the recently discovered protein, EBP50 (ERM-binding phosphoprotein 50). EBP50 is concentrated at the apical membrane in human airway epithelial cells, in vivo, and CFTR and EBP50 associate in in vitro binding assays. The CFTR-EBP50 interaction requires the COOH-terminal DTRL sequence of CFTR and utilizes either PDZ1 or PDZ2 of EBP50, although binding to PDZ1 is of greater affinity. Through formation of a complex, the interaction between CFTR and EBP50 may influence the stability and/or regulation of CFTR Cl- channel function in the cell membrane and provides a potential mechanism through which CFTR can affect the activity of other apical membrane proteins.
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Affiliation(s)
- D B Short
- Department of Physiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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28
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Nguyen TD, Moody MW, Savard CE, Lee SP. Secretory effects of ATP on nontransformed dog pancreatic duct epithelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:G104-13. [PMID: 9655690 DOI: 10.1152/ajpgi.1998.275.1.g104] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Extracellular triphosphate nucleotides, such as ATP, may regulate various cellular functions through specific cell surface receptors. We examine in this report the different secretory effects of ATP and analogs on nontransformed dog pancreatic duct epithelial cells (PDEC). We observed that 1) ATP, UTP, adenosine 5'-O-(3-thiotriphosphate), and, to a lesser extent, beta, gamma-methylene-ATP, but not adenosine, stimulated 125I- efflux from PDEC, suggesting a primary role for P2Y2 receptors, 2) ATP-stimulated 125I- efflux was inhibited by 5-nitro-2-(3-phenylpropylamino)benzoic acid, diphenylamine-2-carboxylate, and DIDS, suggesting mediation through Ca2+-activated Cl- channels, 3) ATP stimulated an 86Rb+ efflux sensitive to BaCl2 and charybdotoxin, thus likely occurring through Ca2+-activated K+ channels, 4) serosal or luminal addition of UTP activated apical Cl- conductance and basolateral K+ conductance when nystatin-permeabilized PDEC were studied in an Ussing chamber, suggesting the expression of P2Y2 receptors on both sides of the cell, 5) ATP stimulated mucin secretion, and 6) ATP increases intracellular Ca2+ concentration ([Ca2+]i). In conclusion, ATP and UTP interact with P2Y2 receptors on nontransformed PDEC to increase [Ca2+]i, stimulate mucin secretion, and activate ion conductances; these findings have implications for pancreatic exocrine function in both health and disease, such as cystic fibrosis.
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Affiliation(s)
- T D Nguyen
- Department of Medicine, University of Washington, and Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA
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29
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Bhaskar KR, Turner BS, Grubman SA, Jefferson DM, LaMont JT. Dysregulation of proteoglycan production by intrahepatic biliary epithelial cells bearing defective (delta-f508) cystic fibrosis transmembrane conductance regulator. Hepatology 1998; 27:7-14. [PMID: 9425910 DOI: 10.1002/hep.510270103] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hepatic dysfunction in cystic fibrosis (CF) has been attributed to accumulation of viscous mucoid secretions in intrahepatic bile ducts. The purpose of our study was to compare glycoconjugate secretion by intrahepatic biliary epithelial (IBE) cells derived from normal livers and livers of CF patients with the delta F508 mutation of the cystic fibrosis transmembrane conductance regulator (CFTR). Confluent cells were incubated with 3H-glucosamine (GlcN) for 16 hours, and radiolabeled macromolecules were analyzed for the amount and type of glycoconjugates. Incorporation of 3H-GlcN into macromolecular glycoconjugates was two- to threefold higher in CF cells versus normals, as was uptake of 3H-Glcn into the cytoplasm of CF cells. Gel exclusion chromatography on Sepharose Cl 4B revealed that the secreted glycoconjugates from CF cells eluted entirely in the excluded fraction (molecular weight > 2 x 10(6)), while, in the normal cells, 60% of the glycoconjugates eluted as lower-molecular-weight species. The high-molecular-weight glycoconjugates in both CF and normal cells were identified as chondroitin sulfates, as evidenced by susceptibility to beta elimination, chondroitinase digestion, and amino acid composition. Western blotting of IBE cell secretions with a polyclonal antibody to chondroitin sulfate revealed proteoglycan bands at 100 and 210 kd. Our results indicate that secretion of chondroitin sulfate is markedly increased in CF biliary epithelium in vitro compared with non-CF cells. Increased uptake of precursor 3H-GlcN may contribute to enhanced glycosylation of chondroitin sulfate in CF cells.
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Affiliation(s)
- K R Bhaskar
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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30
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Kuver R, Savard C, Nguyen TD, Osborne WR, Lee SP. Isolation and long-term culture of gallbladder epithelial cells from wild-type and CF mice. In Vitro Cell Dev Biol Anim 1997; 33:104-9. [PMID: 9081217 DOI: 10.1007/s11626-997-0030-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mice with targeted disruption of the cftr gene show pathophysiologic changes in the gallbladder, which correlate with hepatobiliary disease seen in cystic fibrosis patients. As gallbladder epithelium secretes mucin, and as this epithelium consists of a relatively homogenous cell type, study of CFTR function in these cells would be beneficial to delineate the complex cellular functions of this protein. The size and anatomic location of the murine gallbladder makes such studies difficult in vivo. Therefore, the need exists for in vitro models of gallbladder epithelium. We describe a method to isolate and culture murine gallbladder epithelium from wild-type and CF mice. Cells were grown in a monolayer on porous inserts over a feeder layer of fibroblasts. These nontransformed cells can be successively passaged and maintain a well-differentiated epithelial cell phenotype as shown by morphologic criteria, characterized by polarized columnar epithelial cells with prominent microvilli and intercellular junctions. Organotypic cultures showed columnar cells simulating in vivo morphology. This culture system should be valuable in delineating cellular processes relating to CFTR in gallbladder epithelium.
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Affiliation(s)
- R Kuver
- Department of Medicine, University of Washington, Seattle, USA
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31
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Jilling T, Kirk KL. The biogenesis, traffic, and function of the cystic fibrosis transmembrane conductance regulator. INTERNATIONAL REVIEW OF CYTOLOGY 1997; 172:193-241. [PMID: 9102394 DOI: 10.1016/s0074-7696(08)62361-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic AMP-activated chloride channel that is encoded by the gene that is defective in cystic fibrosis. This ion channel resides at the luminal surfaces and in endosomes of epithelial cells that line the airways, intestine, and a variety of exocrine glands. In this article we discuss current hypotheses regarding how CFTR functions as a regulated ion channel and how CF mutations lead to disease. We also evaluate the emerging notion that CFTR is a multifunctional protein that is capable of regulating epithelial physiology at several levels, including the modulation of other ion channels and the regulation of intracellular membrane traffic. Elucidating the various functions of CFTR should contribute to our understanding of the pathology in cystic fibrosis, the most common lethal genetic disorder among Caucasians.
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Affiliation(s)
- T Jilling
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham 35294, USA
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