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Saidoune F, Even G, Escoubet B, Chezel J, Charles N, Nicoletti A, Papo T, Sacré K. Effet JANUS de la neutralisation de BAFF sur la progression de la maladie athéromateuse associée au lupus. Rev Med Interne 2020. [DOI: 10.1016/j.revmed.2020.10.091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Saidoune F, Charles N, Chezel J, Escoubet B, Papo T, Nicoletti A, Sacre K. AB0140 BAFF NEUTRALIZATION HAS JANUS-FACED EFFECT ON ATHEROSCLEROSIS ASSOCIATED WITH SYSTEMIC LUPUS ERYTHEMATOSUS. Ann Rheum Dis 2020. [DOI: 10.1136/annrheumdis-2020-eular.988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Background:Cardiovascular diseases (CVD) are the leading cause of death in systemic lupus erythematosus (SLE). B cells play a key role in the pathogenesis of lupus and anti-BAFF therapy has been approved in SLE. Since mature B cells also promote atherosclerosis, BAFF neutralization is expected to have an atheroprotective effect in SLE.Objectives:The aim of our study was to test this hypothesis using a new mouse model with a mix susceptibility to lupus and atherosclerosis that received or not an anti-BAFF treatment, and in a cohort of SLE patients in whom we monitored carotid plaques, the B cell compartment and BAFF levels.Methods:The effect of BAFF on atherosclerosis associated with lupus was investigated in the atherosclerosis- and lupus-proneApoe°D227Kmouse model and in a cohort of SLE patients. Mice were treated with a blocking anti-BAFF monoclonal antibody (Ab), while fed with a standard chow diet. Carotid plaque and carotid intima media thickness were assessed by ultrasound at baseline and during follow-up in SLE patients asymptomatic for CVD.Results:Anti-BAFF Ab inApoe°D227Kmice i/ induced a B cell depletion, ii/ efficiently treated lupus, iii/improved atherosclerosis lesions in mice that had low plasma cholesterol levels but worsened the lesions in mice with high cholesterol levels. In that case, the atheroprotective effect of the BAFF-BAFFR signaling inhibition on B cells was counterbalanced by the proatherogenic effect of the BAFF-TACI signaling inhibition on macrophages. In SLE patients, BAFF blood levels were associated with subclinical atherosclerosis. Anti-BAFF Ab treatment had a differential effect on the intima media thickness progression in SLE patients depending on the body mass indexConclusion:Depending on the balance between metabolic- and B cell-induced proatherogenic conditions, anti-BAFF could be respectively detrimental or beneficial on atherosclerosis development in SLEAcknowledgments:Guillaume Even, Yasmine Lamri, Anh-Thu Gaston,Disclosure of Interests:Fanny Saidoune Grant/research support from: supported by a research partnerships between the academic and GlaxoSmithKline France.Anti-BAFF mAb (IgG1, clone 10F4B) in mice was provided by Glaxosmithkline, Nicolas Charles: None declared, Julie Chezel: None declared, Brigitte Escoubet: None declared, Thomas Papo: None declared, Antonino Nicoletti: None declared, karim sacre: None declared
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David C, Divard G, Abbas R, Escoubet B, Chezel J, Chauveheid MP, Rouzaud D, Boutten A, Papo T, Dehoux M, Sacre K. Soluble CD163 is a biomarker for accelerated atherosclerosis in systemic lupus erythematosus patients at apparent low risk for cardiovascular disease. Scand J Rheumatol 2019; 49:33-37. [PMID: 31161842 DOI: 10.1080/03009742.2019.1614213] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Objective: This study aimed to determine whether sCD163, a soluble macrophage marker up-regulated in numerous inflammatory disorders, is predictive of accelerated atherosclerosis associated with systemic lupus erythematosus (SLE).Methods: Carotid ultrasound was prospectively performed, at baseline and during follow-up, in 63 consecutive SLE patients asymptomatic for cardiovascular disease (CVD) and 18 volunteer health workers. Serum sCD163 level was determined at baseline using enzyme-linked immunosorbent assay. The primary outcome was the presence of a carotid plaque. Factors associated with carotid plaques were identified through multivariate analysis.Results: Despite a low risk for cardiovascular events according to Framingham score in both groups (2.1 ± 3.8% in SLE vs 2.1 ± 2.9% in controls; p = 0.416), ultrasound at baseline showed a carotid plaque in 23 SLE patients (36.5%) and two controls (11.1%) (p = 0.039). Multivariate analysis showed that SLE status increased the risk for carotid plaque by a factor of 9 (p = 0.017). In SLE patients, sCD163 level was high (483.7 ± 260.8 ng/mL vs 282.1 ± 97.5 ng/mL in controls; p < 0.001) and independently associated with carotid plaques, as assessed by stratification based on sCD163 quartile values (p = 0.009), receiver operating characteristics (p = 0.001), and multivariate analysis (p = 0.015). sCD163 at baseline was associated with the onset of carotid plaque during follow-up (3 ± 1.4 years) in SLE patients who had no carotid plaque at the first evaluation (p = 0.041).Conclusion: sCD163 is associated with progressing carotid plaque in SLE and may be a useful biomarker for accelerated atherosclerosis in SLE patients at apparent low risk for CVD.
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Affiliation(s)
- C David
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - G Divard
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - R Abbas
- Department of Epidemiology and Clinical Research, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - B Escoubet
- Departement of Physiology, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, INSERM, Paris, France
| | - J Chezel
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - M P Chauveheid
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - D Rouzaud
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - A Boutten
- Department of Metabolic and Cellular Biochemistry, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - T Papo
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France.,INSERM U1149 (French Institute of Health and Medical Research), University of Paris Diderot, Paris, France.,Hospital-University Department of Fibrosis, Inflammation and Remodelling in Renal and Respiratory Diseases, FIRE, Paris, France
| | - M Dehoux
- Department of Metabolic and Cellular Biochemistry, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France
| | - K Sacre
- Departement of Internal Medicine, Bichat Hospital, University of Paris Diderot, PRES Sorbonne Paris Cité, APHP, Public Hospitals of Paris, Paris, France.,INSERM U1149 (French Institute of Health and Medical Research), University of Paris Diderot, Paris, France.,Hospital-University Department of Fibrosis, Inflammation and Remodelling in Renal and Respiratory Diseases, FIRE, Paris, France
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David C, Divard G, Abbas R, Escoubet B, Chezel J, Chauveheid M, Rouzaud D, Boutten A, Leçon-Malas V, Papo T, Dehoux M, Sacre K. Soluble CD163 is a biomarker for accelerated atherosclerosis in systemic lupus erythematosus patients at apparent low risk for cardiovascular disease. Clin Chim Acta 2019. [DOI: 10.1016/j.cca.2019.04.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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David C, Escoubet B, Abbas R, Chezel J, Chauveheid M, Papo T, Dehoux M, Sacré K. CD163 soluble est un marqueur d’athérome accéléré chez les patients lupiques à faible risque cardiovasculaire apparent. Rev Med Interne 2018. [DOI: 10.1016/j.revmed.2018.10.265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Moussaoui A, Bouleti C, Flamant M, Escoubet B, Arnoult F, Milleron O, Vidal-Petiot E, Langeois M, Ou P, Vrtovsnik F, Jondeau G. Increased risk of aortic root aneurism in patient with autosomal dominant polycystic kidney disease. Archives of Cardiovascular Diseases Supplements 2018. [DOI: 10.1016/j.acvdsp.2018.02.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Syvannarath V, Delbosc S, Escoubet B, Le Borgne-Moynnier M, Laschet J, Morvan M, Even G, Journee C, Nicoletti A, Caligiuri G. Treatment with a CD31 agonist peptide improves the outcome of experimental heart failure with either reduced or preserved ejection fraction. Archives of Cardiovascular Diseases Supplements 2018. [DOI: 10.1016/j.acvdsp.2018.02.058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Syvannarath V, Delbosc S, Escoubet B, Le Borgne-Moynier M, Khallou-Laschet J, Morvan M, Even G, Journee C, Nicoletti A, Caligiuri G. P126The administration of a CD31 agonist peptide exerts a beneficial effect in experimental heart failure with both reduced and preserved ejection fraction. Cardiovasc Res 2018. [DOI: 10.1093/cvr/cvy060.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | | | - B Escoubet
- Hospital Bichat-Claude Bernard, Physiology, Paris, France
| | | | | | | | - G Even
- INSERM, U1148, Paris, France
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Bouleti C, Flamant M, Escoubet B, Arnoult F, Milleron O, Vidal-Petiot E, Langeois M, Vrtovsnik F, Jondeau G. P5245Autosomal polycystic kidney disease carries an increased risk of aortic root aneurysm. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx493.p5245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Divard G, Abbas R, Chenevier-Gobeaux C, Escoubet B, Chauveheid M, Dossier A, Dehoux M, Papo T, Sacré K. La troponine C ultrasensible est un biomarqueur d’athérosclérose accélérée chez les sujets lupiques. Rev Med Interne 2016. [DOI: 10.1016/j.revmed.2016.10.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sacre K, Chauchard M, Escoubet B, Francois C, Vanderhaegen MC, Zennaro MC, Chauveheid MP, Papo T. AB0174 Overweight is an Independent Contributor to Atherosclerosis in Systemic Lupus Erythematosus Patients at Low Risk for Cardiovascular Disease: A Cross-Sectional Controlled Study. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-eular.1082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Sacre K, Escoubet B, Chauchard M, Chauveheid MP, Zennaro MC, Papo T. FRI0277 Arterial stiffness in systemic lupus erythematosus (SLE) patients: a controlled study. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2013-eular.1404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Sacre K, Escoubet B, Charles N, Chauveheid MP, Papo T. THU0341 Expansion of CD4+CXCR3+ T Cells in Patients with Systemic Lupus Erythematosus (SLE) Correlates with Subclinical Atherosclerosis. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2013-eular.869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Brihaye B, Lidove O, Sacré K, Laissy JP, Escoubet B, Valla D, Papo T. Diffuse periarterial involvement in systemic fibrosclerosis with Riedel's thyroiditis, sclerosing cholangitis, and retroperitoneal fibrosis. Scand J Rheumatol 2009; 37:490-2. [DOI: 10.1080/03009740802241725] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Sorbets E, Delorme L, Fornasa G, Meilhac O, Escoubet B, Bardon J, Feldman LJ, Caligiuri G. A014 Valeur diagnostique de la fraction tronquée du CD31 plasmatique dans la cardiopathie ischemique. Arch Cardiovasc Dis 2009. [DOI: 10.1016/s1875-2136(09)72147-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Slove S, Pellay FX, Pezet M, Escoubet B, Behmoaras J, Gauguier D, Bujan J, Benecke A, Jacob MP. L010 Synthèse de l’élastine dans l’aorte de rat : étude des gènes régulateurs. Arch Cardiovasc Dis 2009. [DOI: 10.1016/s1875-2136(09)72425-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lasocki S, Escoubet B, Heimburger M, Choqueux C, Mercadier JJ. Administration route allows to distinguish different stages of doxorubicin-induced cardiomyopathy in rats. J Mol Cell Cardiol 2002. [DOI: 10.1016/s0022-2828(02)90876-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Prunier F, Escoubet B, Gaertner R, Choqueux C, Heimburger M, Michel JB, Mercadier JJ. Homogenization of left ventricular SERCA gene expression after myocardial infarction in the rat. J Mol Cell Cardiol 2002. [DOI: 10.1016/s0022-2828(02)90931-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Couloigner V, Fay M, Djelidi S, Farman N, Escoubet B, Runembert I, Sterkers O, Friedlander G, Ferrary E. Location and function of the epithelial Na channel in the cochlea. Am J Physiol Renal Physiol 2001; 280:F214-22. [PMID: 11208596 DOI: 10.1152/ajprenal.2001.280.2.f214] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the cochlea, endolymph is a K-rich and Na-poor fluid. The purpose of the present study was to check the presence and to assess the role of epithelial Na channel (ENaC) in this organ. alpha-, beta-, and gamma-ENaC subunit mRNA, and proteins were detected in rat cochlea by RT-PCR and Western blot. alpha-ENaC subunit mRNA was localized by in situ hybridization in both epithelial (stria vascularis, spiral prominence, spiral limbus) and nonepithelial structures (spiral ligament, spiral ganglion). The alpha-ENaC-positive tissues were also positive for beta-subunit mRNA (except spiral ganglion) or for gamma-subunit mRNA (spiral limbus, spiral ligament, and spiral ganglion), but the signals of beta- and gamma-subunits were weaker than those observed for alpha-subunit. In vivo, the endocochlear potential was recorded in guinea pigs under normoxic and hypoxic conditions after endolymphatic perfusion of ENaC inhibitors (amiloride, benzamil) dissolved either in K-rich or Na-rich solutions. ENaC inhibitors altered the endocochlear potential when Na-rich but not when K-rich solutions were perfused. In conclusion, ENaC subunits are expressed in epithelial and nonepithelial cochlear structures. One of its functions is probably to maintain the low concentration of Na in endolymph.
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Affiliation(s)
- V Couloigner
- Institut National de la Santé et de la Recherche Médicale U-426, Faculté Xavier Bichat, 75870 Paris Cedex 18, France.
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Capurro C, Rivarola V, Kierbel A, Escoubet B, Farman N, Blot-Chabaud M, Parisi M. Vasopressin regulates water flow in a rat cortical collecting duct cell line not containing known aquaporins. J Membr Biol 2001; 179:63-70. [PMID: 11155210 DOI: 10.1007/s002320010037] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Transepithelial water movements and arginine-vasopressin (AVP)-associated ones were studied in a renal cell line established from a rat cortical collecting duct (RCCD(1)). Transepithelial net water fluxes (J(w)) were recorded every minute in RCCD(1) monolayers cultured on permeable supports. Spontaneous net water secretion was observed, which was inhibited by serosal bumetanide (10(-5) m), apical glibenclamide (10(-4) m) and apical BaCl(2) (5 x 10(-3) m). RT-PCR, RNAse protection and/or immunoblotting experiments demonstrated that known renal aquaporins (AQP1, AQP2, AQP3, AQP4, AQP6 and AQP7) were not expressed in RCCD(1) cells. AVP stimulates cAMP production and sodium reabsorption in RCCD(1) cells. We have now observed that AVP significantly reduces the spontaneous water secretory flux. The amiloride-sensitive AVP-induced increase in short-circuit current (I(sc)) was paralleled by a simultaneous modification of the observed J(w): both responses had similar time courses and half-times (about 4 min). On the other hand, AVP did not modify the osmotically driven J(w) induced by serosal hypertonicity. We can conclude that: (i) transepithelial J(w) occurs in RCCD(1) cells in the absence of known renal aquaporins; (ii) the "water secretory component" observed could be linked to Cl- and K = secretion; (iii) the natriferic response to AVP, preserved in RCCD(1) cells, was associated with a change in net water flux, which was even observed in absence of AQP2, AQP3 or AQP4 and (iv) the hydro-osmotic response to AVP was completely lost.
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Affiliation(s)
- C Capurro
- Laboratorio de Biomembranas, Dpto de Fisiologia, Facultad de Medicina, Univ. de Buenos Aires, Argentina
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Couloigner V, Teixeira M, Hulin P, Sterkers O, Bichara M, Escoubet B, Planelles G, Ferrary E. Effect of locally applied drugs on the pH of luminal fluid in the endolymphatic sac of guinea pig. Am J Physiol Regul Integr Comp Physiol 2000; 279:R1695-700. [PMID: 11049851 DOI: 10.1152/ajpregu.2000.279.5.r1695] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of the present work was to assess the effect of various drugs applied locally on the pH of the luminal fluid (pH(lum)) in guinea pig endolymphatic sac. pH(lum) and transepithelial potential, when measured in vivo by means of double-barrelled pH-sensitive microelectrodes, were 7.06 +/- 0.08 and +6.1 +/- 0.34 mV (mean +/- SE; n = 84), respectively, which is consistent with a net acid secretion in the luminal fluid of the endolymphatic sac. Bafilomycin and acetazolamide increased and decreased, respectively, pH(lum). Amiloride, ethylisopropylamiloride, ouabain, and Schering 28080 had no effect on pH(lum). Results obtained with inhibitors of anionic transport systems were inconclusive; e.g., DIDS reduced pH(lum), whereas neither SITS nor triflocin had any effect. We conclude that bafilomycin-sensitive H(+)-ATPase activity accounts for the transepithelial acid gradient measured in the endolymphatic sac and that intracellular and membrane-bound carbonic anhydrase probably participates in regulating endolymphatic sac pH(lum). The relationship between acid pH, endolymph volume, and Ménière's disease remains to be further investigated.
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Affiliation(s)
- V Couloigner
- Institut National de la Santé et de la Recherche Médicale U.426, Faculté Xavier Bichat, Université Paris 7, 75870 Paris Cedex 18, France
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Silvestre JS, Robert V, Escoubet B, Heymes C, Oubénaïssa A, Desopper C, Swynghedauw B, Delcayre C. Different regulation of cardiac and renal corticosteroid receptors in aldosterone-salt treated rats: effect of hypertension and glucocorticoids. J Mol Cell Cardiol 2000; 32:1249-63. [PMID: 10860767 DOI: 10.1006/jmcc.2000.1159] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study analysed the regulation of cardiac mineraloreceptor (MR) and glucoreceptor (GR) in aldosterone-salt treatment (AST). AST causes hypertension, left ventricle (LV) hypertrophy and decreases plasma corticosterone level. Ribonuclease protection assay and Western blot analysis showed a rise of MR mRNA (1.5- and 1.4-fold at day 15 and 30, respectively) and protein levels (1.8- and 4.1-fold at day 30 and 60, respectively) in the LV, but not in either the right ventricle (RV) or in kidney of treated rats. Addition of MR antagonist spironolactone (20 mg/kg/day) for 30 days failed to prevent these changes but was able to reduce AST-induced cardiac fibrosis. Similar hypertension-induced MR upregulations were observed in the LV of AngII-hypertensive rats and of 12-week-old SHR when compared to 4-week-old prehypertensive SHR. AST also enhanced left ventricular GR mRNA (2.0- and 3.0-fold at day 7 and 15, respectively) and protein contents (2.0- and 1.7-fold at day 30 and 60, respectively). In contrast to MR, GR levels were also upregulated in both RV and kidney. Such an upregulation was equally observed at mRNA and protein levels in LV, RV and kidney after adrenalectomy (15 days) and was prevented in both tissues after glucocorticoid replacement (adrenalectomy + dexamethasone at 100 micro g/kg/day for 15 days). Therefore, MR level may be controlled by hemodynamical factors whereas that of GR depends upon glucocorticoids level.
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Affiliation(s)
- J S Silvestre
- INSERM U127, Hôpital Lariboisière, IFR circulation, Université Paris 7-Denis Diderot, Paris cedex 10, 75475, France
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Abstract
Previous investigations have reported the presence of uridine 5'-triphosphate (UTP) and adenosine 5'-triphosphate (ATP) receptors triggering phospholipase C (PLC) activation in the frog semicircular canal. The aim of this work was to characterize the molecular subtypes of these nucleotide receptors. Due to the lack of molecular tools for purinoceptors in amphibia, this study was performed on the rat. The stria vascularis, organ of Corti and spiral ligament were microdissected from Long Evans rat cochlea. RNA was extracted from four cochleas and polymerase chain reaction (PCR) was performed after reverse transcription (RT) using oligonucleotides for sequences of P2Y1, P2Y2, P2Y4 and P2Y6 receptors. Various tissues were used as negative controls (testis for P2Y1 and P2Y6 receptors, brain for P2Y2 and P2Y4 receptors and liver for P2Y4 receptors). Data show the expression of the four transcripts in the stria vascularis, organ of Corti and spiral ligament. When results were normalized to the signal obtained with S14 mRNA, a ribosomal protein used as an internal standard, expressions were similar in the three structures. In conclusion, these results demonstrate the mRNA expression of the three UTP receptors (P2Y2, P2Y4 and P2Y6) and of the P2Y1 ATP receptor in both sensory and secretory structures of the rat inner ear. Their functional roles remain to be defined.
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Affiliation(s)
- M Teixeira
- INSERM U.426, Faculté de Médecine Xavier Bichat, Paris, France
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Bellocq A, Doublier S, Suberville S, Perez J, Escoubet B, Fouqueray B, Puyol DR, Baud L. Somatostatin increases glucocorticoid binding and signaling in macrophages by blocking the calpain-specific cleavage of Hsp 90. J Biol Chem 1999; 274:36891-6. [PMID: 10601241 DOI: 10.1074/jbc.274.52.36891] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Somatostatin has direct anti-inflammatory actions and participates in the anti-inflammatory actions of glucocorticoids, but the mechanisms underlying this regulation remain poorly understood. The objective of this study was to evaluate whether somatostatin increases glucocorticoid responsiveness by up-regulating glucocorticoid receptor (GR) expression and signaling. Somatostatin promoted a time- and dose-dependent increase in [(3)H]dexamethasone binding to RAW 264.7 macrophages. Cell exposure to 10 nM somatostatin for 18 h promoted a 2-fold increase in the number of GR sites per cell without significant modification of the affinity. Analysis of GR heterocomplex components demonstrated that somatostatin increased the level of heat shock protein (Hsp) 90, whereas the level of GR remained almost unchanged. The increase in Hsp 90 was associated with a decrease in the cleavage of its carboxyl-terminal domain. Evidence for the involvement of calpain inhibition in this process was obtained by the demonstration that 1) somatostatin induced a dose-dependent decrease in calpain activity and 2) calpain inhibitors, calpain inhibitor I and calpeptin, both abolished the cleavage of Hsp 90 and induced a dose-dependent increase in [(3)H]dexamethasone binding. Increases in glucocorticoid binding after somatostatin treatment were associated with similar increases in the ability of GR to transactivate a minimal promoter containing two glucocorticoid response elements (GRE) and to interfere with the activation of nuclear factor-kappaB (NF-kappaB). Thus, the present findings indicate that somatostatin increases glucocorticoid binding and signaling by limiting the calpain-specific cleavage of GR-associated Hsp 90. This mechanism may represent a novel target for intervention to increase glucocorticoid responsiveness.
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Affiliation(s)
- A Bellocq
- Unité INSERM 489, Hôpital Tenon, Paris, France
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Escoubet B, Planès C, Clerici C. Hypoxia increases glyceraldehyde-3-phosphate dehydrogenase transcription in rat alveolar epithelial cells. Biochem Biophys Res Commun 1999; 266:156-61. [PMID: 10581182 DOI: 10.1006/bbrc.1999.1798] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alveolar epithelial type II (ATII) cells are particularly hypoxia-tolerant in vitro. As one of the mechanisms of hypoxia tolerance is the induction of certain proteins, one of which is glyceraldehyde-3-phosphate dehydrogenase (GAPDH), we investigated whether hypoxia modified GAPDH expression in ATII cells. Hypoxia induced a time- and O(2) concentration-dependent accumulation of GAPDH mRNA in cultured rat ATII cells (2- to 3-fold the normoxic value after 18 h in 0% O(2)), an effect completely reversed by reoxygenation. GAPDH mRNA induction was accounted for by an increase in GAPDH gene transcription during hypoxia with no change in mRNA stability. GAPDH protein synthesis increased 3- to 4-fold after 18 h of 0% O(2), while the GAPDH protein steady-state level rose by 75%. GAPDH enzymatic activity in hypoxic cell homogenates increased by 45%. These results indicate that hypoxia induces GAPDH expression in ATII cells through an increase in transcription.
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Affiliation(s)
- B Escoubet
- Department of Physiology, INSERM U 426, Faculté de Médecine Xavier Bichat, Université Paris 7, Paris, 75018, France
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Portier F, van den Abbeele T, Lecain E, Sauvaget E, Escoubet B, Huy PT, Herman P. Oxygen modulates Na+ absorption in middle ear epithelium. Am J Physiol 1999; 276:C312-7. [PMID: 9950758 DOI: 10.1152/ajpcell.1999.276.2.c312] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The physiology of the middle ear is primarily concerned with keeping the cavities air filled and fluid free to allow transmission of the sound vibrations from the eardrum to the inner ear. Middle ear epithelial cells are thought to play a key role in this process, since they actively transport Na+ and water. The PO2 of the middle ear cavities varies from 44 to 54 mmHg in healthy human ears but may be lower in the course of secretory otitis media. The effect of chronic hypoxia on ion transport was investigated on a middle ear cell line using the short-circuit current technique. Chronic hypoxia reversibly decreased the rate of Na+ absorption across the MESV cell line. Although a decrease in cellular ATP content was observed, the decrease of Na+ absorption seemed related to a primary modulation of apical Na+ entry. As revealed by RNase protection assay, the decrease in the rate of apical Na+ entry strictly paralleled the decrease in the expression of transcripts encoding the alpha-subunit of the epithelial Na+ channel. This effect of oxygen on Na+ absorption might account for 1) the presence of fluid in the middle ear in the course of secretory otitis media and 2) the beneficial effect of the ventilation tube in treating otitis media that allows the PO2 to rise and restores the fluid clearance.
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Affiliation(s)
- F Portier
- Laboratoire d'Otologie Expérimentale, Faculté Lariboisière-St-Louis, Institut National de la Santé et de la Recherche Médicale Unité 426, Faculté Xavier Bichat, Université Paris VII, 75010 Paris, France
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Farman N, Djelidi S, Brouard M, Escoubet B, Blot-Chabaud M, Bonvalet J. Chapter 4 Cell-Specific Expression of ENaC and its Regulation by Aldosterone and Vasopressin in Kidney and Colon. CURRENT TOPICS IN MEMBRANES 1999. [DOI: 10.1016/s0070-2161(08)60952-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2023]
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Cluzeaud F, Reyes R, Escoubet B, Fay M, Lazdunski M, Bonvalet JP, Lesage F, Farman N. Expression of TWIK-1, a novel weakly inward rectifying potassium channel in rat kidney. Am J Physiol 1998; 275:C1602-9. [PMID: 9843722 DOI: 10.1152/ajpcell.1998.275.6.c1602] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several K+ conductances have been identified in the kidney, with specific properties and localization in distinct cell types and membrane domains. On the other hand, several K+ channels have been characterized at the molecular level. By immunolocalization, we show that a new inward rectifying K+ channel, TWIK-1, is specifically expressed in distinct tubular segments and cell types of the rat kidney. In the proximal tubule, TWIK-1 prevails in the initial portions (convoluted part), where it is restricted to the apical (brush-border) membrane. In the collecting duct, immunofluorescence was intracellular or confined to the apical membrane and restricted to intercalated cells, i.e., in cells lacking aquaporin-2, as shown by double immunofluorescence. TWIK was also expressed in medullary and cortical parts of the thick limb of the loop of Henle, identified with an anti-Tamm-Horsfall protein antibody (double immunofluorescence). The intensity of TWIK-1 immunolabeling was unchanged in rats fed a low-Na+ or a low-K+ diet. Because TWIK-1 shares common properties with the low-conductance apical K+ channel of the collecting duct, we propose that it could play a role in K+ secretion, complementary to ROMK, another recently characterized K+ channel located in principal cells of the cortical collecting duct and in the loop of Henle.
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Affiliation(s)
- F Cluzeaud
- Unité 478, Institut National de la Santé et de la Recherche Médicale, Faculté de Médecine X. Bichat, F-75870 Paris cedex 18, France
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29
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Essig M, Nguyen G, Prié D, Escoubet B, Sraer JD, Friedlander G. 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors increase fibrinolytic activity in rat aortic endothelial cells. Role of geranylgeranylation and Rho proteins. Circ Res 1998; 83:683-90. [PMID: 9758637 DOI: 10.1161/01.res.83.7.683] [Citation(s) in RCA: 218] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (HRIs) have been recently shown to prevent atherosclerosis progression. Clinical benefit results from combined actions on various components of the atherosclerotic lesion. This study was designed to identify the effects of HRI on one of these components, the endothelial fibrinolytic system. Aortas isolated from rats treated for 2 days with lovastatin (4 mg/kg body wt per day) showed a 3-fold increase in tissue plasminogen activator (tPA) activity. In a rat aortic endothelial cell line (SVARECs) and in human nontransformed endothelial cells (HUVECs), HRI induced an increase in tPA activity and antigen in a time- and concentration-dependent manner. In SVARECs, the maximal response was observed when cells were incubated for 48 hours with 50 micromol/L HRI. An increase of tPA mRNA was also in evidence. In contrast, HRI inhibited plasminogen activator inhibitor-1 activity and mRNA. The effects of HRI were reversed by mevalonate and geranylgeranyl pyrophosphate, but not by LDL cholesterol and farnesyl pyrophosphate, and were not induced by alpha-hydroxyfarnesyl phosphonic acid, an inhibitor of protein farnesyl transferase. C3 exoenzyme, an inhibitor of the geranylgeranylated-activated Rho protein, reproduced the effect of lovastatin on tPA and plasminogen activator inhibitor-1 activity and blocked its reversal by geranylgeranyl pyrophosphate. The effect of HRI was associated with a disruption of cellular actin filaments without modification of microtubules. A disrupter of actin filaments, cytochalasin D, induced the same effect as lovastatin on tPA, whereas a disrupter of microtubules, nocodazole, did not. In conclusion, HRI can modify the fibrinolytic potential of endothelial cells, likely via inhibition of geranylgeranylated Rho protein and disruption of the actin filaments. The resulting increase of fibrinolytic activity of endothelial cells may contribute to the beneficial effects of HRI in the progression of atherosclerosis.
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Affiliation(s)
- M Essig
- INSERM U 426 and the Department of Physiology, Faculté de Médecine Xavier Bichat, Université Denis Diderot, Paris, France
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Herman P, Tan CT, Portier F, Clerici C, Escoubet B, Friedlander G, Tran Ba Huy P. Ion transports in the middle ear epithelium. Kidney Int Suppl 1998; 65:S94-7. [PMID: 9551440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ion transports in the middle ear epithelium have been recently characterized. Experimental data using cell culture have found the existence of a sodium transepithelial transport that drives a water flow. This is thought to play a key role in the maintain of air-filled and fluid-free cavities. Impairment of this process is involved in the pathogenesis of secretory otitis media, which is the main cause of acquired hearing loss. Several modulations of this transport have been evidenced: (i) reactive oxygen species induced an endogenous synthesis of prostaglandin E2 (PGE2), which in turn increased the cAMP level and modulated ion transport rate; (ii) steroids increased the expression of the alpha subunit sodium channel mRNA, which changes paralleled the modulation of ion transport in the middle ear epithelium; (iii) moderate hypoxia selectively and reversibly decreased the rate of sodium transport, as a result of a parallel decrease in alpha epithelial sodium channel subunit mRNA level. These modulations may explain the course of middle ear pathology. However, the development of an in vivo model has become mandatory to assess the relevance of these data in the pathophysiology of the middle ear.
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Affiliation(s)
- P Herman
- Laboratoire d'Otologie Expérimentale, Faculté Lariboisière-St-Louis, Université Paris VII, Paris, France
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Djelidi S, Fay M, Cluzeaud F, Escoubet B, Eugene E, Capurro C, Bonvalet JP, Farman N, Blot-Chabaud M. Transcriptional regulation of sodium transport by vasopressin in renal cells. J Biol Chem 1997; 272:32919-24. [PMID: 9407070 DOI: 10.1074/jbc.272.52.32919] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have examined whether arginine vasopressin (AVP) can induce a long-term modulation of transepithelial ion transport in addition to its well known short-term effect. In the RCCD1 rat cortical collecting duct cell line, an increase in both short-circuit current and 22Na transport was observed after several hours of 10(-8) M AVP treatment (a concentration above the in vivo physiological range). This delayed effect was partially prevented by apical addition of 10(-5) M amiloride and was blocked by 10(-6) M actinomycin D and 2 x 10(-6) M cycloheximide. The amounts of mRNA encoding the alpha1 (not beta1) subunit of Na+/K+-ATPase and the beta and gamma (not alpha) subunits of the amiloride-sensitive epithelial Na+ channel were significantly increased by AVP treatment. The increase in mRNA was blocked by actinomycin D, not by amiloride, suggesting a Na+-independent increase in the rate of transcription of these subunits. The translation rates of the alpha1 subunit of Na+/K+-ATPase and the beta and gamma subunits of the rat epithelial sodium channel increased significantly, whereas the translation rates of the other subunits remained unchanged. Finally, the number of Na+ channels present in the apical membrane of the cells increased, as demonstrated by enhanced specific [3H]phenamil binding.
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Affiliation(s)
- S Djelidi
- INSERM, Institut Fédératif de Recherches "Cellules Epithéliales," Faculté de Médecine Xavier Bichat, 16, rue Henri Huchard, 75870 Paris Cedex 18, France
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32
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Affiliation(s)
- C Capurro
- Institut National de la Santé et de la Recherche Médicale U246, Paris, France.
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Planès C, Escoubet B, Blot-Chabaud M, Friedlander G, Farman N, Clerici C. Hypoxia downregulates expression and activity of epithelial sodium channels in rat alveolar epithelial cells. Am J Respir Cell Mol Biol 1997; 17:508-18. [PMID: 9376126 DOI: 10.1165/ajrcmb.17.4.2680] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Decrease in alveolar oxygen tension may induce acute lung injury with pulmonary edema. We investigated whether, in alveolar epithelial cells, expression and activity of epithelial sodium (Na) channels and Na,K-adenosine triphosphatase, the major components of transepithelial Na transport, were regulated by hypoxia. Exposure of cultured rat alveolar cells to 3% and 0% O2 for 18 h reduced Na channel activity estimated by amiloride-sensitive 22Na influx by 32% and 67%, respectively, whereas 5% O2 was without effect. The decrease in Na channel activity induced by 0% O2 was time-dependent, significant at 3 h of exposure and maximal at 12 and 18 h. It was associated with a time-dependent decline in the amount of mRNAs encoding the alpha-, beta-, and gamma-subunits of the rat epithelial Na channel (rENaC) and with a 42% decrease in alpha-rENaC protein synthesis as evaluated by immunoprecipitation after 18 h of exposure. The 0% O2 hypoxia also caused a time-dependent decrease in (1) ouabain-sensitive 86Rubidium influx in intact cells, (2) the maximal velocity of Na,K-ATPase on crude homogenates, and (3) alpha1- and beta1-Na,K-ATPase mRNA levels. Levels of rENaC and alpha1-Na,K-ATPase mRNA returned to control values within 48 h of reoxygenation, and this was associated with complete functional recovery. We conclude that hypoxia induced a downregulation of expression and activity of epithelial Na channels and Na,K-ATPase in alveolar cells. Subsequent decrease in Na reabsorption by alveolar epithelium could participate in the maintenance of hypoxia-induced alveolar edema.
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Affiliation(s)
- C Planès
- Department of Physiology, INSERM U 426, Faculté de Médecine Xavier Bichat, Université Paris 7, France
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Escoubet B, Coureau C, Bonvalet JP, Farman N. Noncoordinate regulation of epithelial Na channel and Na pump subunit mRNAs in kidney and colon by aldosterone. Am J Physiol 1997; 272:C1482-91. [PMID: 9176138 DOI: 10.1152/ajpcell.1997.272.5.c1482] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Distal colon and renal cortical collecting ducts are major effectors of aldosterone-dependent Na homeostasis. Na is absorbed by entry through an apical amiloride-sensitive Na channel and extruded by Na-K-ATPase at the basolateral membrane. Using a ribonuclease protection assay, we studied, in vivo, aldosterone regulation of alpha-, beta-, gamma-subunits of the rat epithelial Na channel (rENaC) and alpha 1- and beta 1-subunits of Na-K-ATPase. In the kidney, Na-K-ATPase mRNAs were also assayed over discrete tubular segments by in situ hybridization. In rat colon, all three rENaC mRNAs were decreased by adrenalectomy, with a major effect on beta- and gamma-subunits, and were restored with 7 days, but not 2 days, of aldosterone treatment; in the kidney, however, only alpha-transcripts varied. Na-K-ATPase alpha 1- and beta 1-subunit mRNAs in both organs were not (in the case of the beta 1-subunit) or were mildly (in the case of the alpha 1-subunit) affected after adrenalectomy. Our conclusions are as follows: 1) Transcripts of rENaC and Na-K-ATPase subunits are not coordinately regulated by aldosterone in vivo; i.e., modulation involves mainly the Na channel, not Na-K-ATPase; the effect is not of comparable magnitude on each subunit mRNA and differs between tissues. 2) The delay of the aldosterone effect on transcripts is much longer than that required to restore normal Na transport in adrenalectomized rats, indicating that rENaC and Na-K-ATPase subunit transcript levels may depend on unidentified early aldosterone-induced proteins.
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Affiliation(s)
- B Escoubet
- Institut Fédératif de Recherche Cellules Epithéliales, Institut National de la Santé et de la Recherche Médicale, Paris, France
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Tan CT, Escoubet B, Van den Abbeele T, Friedlander G, Tran Ba Huy P, Herman P. Modulation of middle ear epithelial function by steroids: clinical relevance. Acta Otolaryngol 1997; 117:284-8. [PMID: 9105467 DOI: 10.3109/00016489709117788] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The efficacy of steroid therapy for the treatment of otitis media in children remains controversial, and a putative modulation of the middle ear epithelial function has to be demonstrated. Using the MESV cell line, short-circuit current (ISC) technique was used to evaluate changes in ion transport induced by glucocorticoids. Dexamethasone (DXM) produced a dose- and time-dependent increase in ISC in MESV cells. This effect was inhibited by specific glucocorticoid antagonist (RU-38486) and was related to a sodium transport, since the DXM-induced increase in ISC could be prevented or abolished i) by apical addition of the specific Na+ channel inhibitor benzamil; or ii) by substitution of sodium with N-Methyl-glucamine in the incubation medium. RNase protection assay revealed that DXM increased the expression of the alpha subunit sodium channel mRNA, which changes paralleled the modulation of ion transport. These data demonstrate that steroids up-regulate the trans-epithelial sodium transport in the middle ear epithelium. As far as these experimental data can be extrapolated to the in vivo situation, a component of the beneficial effect of steroid therapy for the treatment of otitis media may result from a corticosteroid-induced improvement in fluid clearance from the middle ear.
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Affiliation(s)
- C T Tan
- Laboratoire d'Otologie Expérimentale, Faculté Lariboisière-St-Louis, Université Paris VII, France
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Herman P, Tan CT, van den Abbeele T, Escoubet B, Friedlander G, Huy PT. Glucocorticosteroids increase sodium transport in middle ear epithelium. Am J Physiol 1997; 272:C184-90. [PMID: 9038824 DOI: 10.1152/ajpcell.1997.272.1.c184] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effect of glucocorticosteroids on ion transport was investigated on a middle ear cell line with the short-circuit current (Isc) technique. Dexamethasone (DXM) produced a dose- and time-dependent increase in Isc. Concentration of half-maximal stimulation was 2.68 x 10(-8) M. This effect was blunted by the glucocorticoid antagonist RU-38486 and was related to Na+ transport, as evidenced by the inhibition induced by 1) apical addition of the Na+ channel inhibitor benzamil (10(-6) M) or 2) substitution of Na+ with N-methylglucamine in the incubation medium. The increase in Na+ transport resulted from a primary modulation of apical Na+ entry, since 1) the Na(+)-K(+)-ATPase activity of cellular homogenates was not modified by corticosteroids and 2) the DXM-induced increase in the ouabain-sensitive uptake of 86Rb was blunted by benzamil. Ribonuclease protection assay revealed 1) a constitutive expression of the mRNA encoding the alpha-subunit of the epithelial Na+ channel and 2) that DXM increased the expression of this transcript. This increase was dose dependent and paralleled changes in transepithelial Na+ transport. This study suggests that a component of the beneficial effect of steroid therapy for the treatment of otitis media might be related to increased fluid clearance.
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Affiliation(s)
- P Herman
- Laboratoire d'Otologie Expérimentale, Faculté Lariboisiere, St. Louis, Université Paris VII, France
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Abstract
Culture of primary alveolar type II cells has been widely used to investigate the Na+ transport characteristics of alveolar epithelium. However, this model was restricted by early morphological and physiological dedifferentiation in culture. Recently, a cell line has been obtained by transfection of neonatal type II cells with the simian virus SV40 large T antigen gene (SV40-T2). SV40-T2 cells have retained proliferative characteristics of the primary type II cells (Clement et al., 1991, Exp. Cell Res., 196:198-205.) In the present study, we have characterized Na+ transport pathways in SV40-T2 cells. SV40-T2 cells retained most cardinal properties of the original alveolar epithelial cells. Na+ entry occurred, as in primary cultures, through both Na(+)-cotransporters and amiloride-sensitive Na+ channels. SV40-T2 cells expressed Na(+)-phosphate. Na(+)-amino acid and Na(+)-K(+)-Cl cotransports which are quantitatively similar to that of primary cultures. The existence of amiloride-sensitive Na+ channels was supported by molecular and functional data. SV40-T2 expressed the cloned alpha- and gamma-mRNAs for the rat epithelial Na+ channel (rENaC), whereas beta subunit was not detected, and 22Na+ influx was significantly inhibited by 10 microM amiloride. Na+, which enters SV40-T2 cells, is extruded through a Na+, K(+)-ATPase: mRNA for alpha 1 and beta 1 isoforms of Na+, K(+)-ATPase were present and Na+, K(+)-ATPase activity was evidenced either on intact cells by the presence of a ouabain-sensitive component of 86Rb+ influx or on cell homogenates by the measurement of ouabain-inhibitable ATP hydrolysis. These results indicate that SV40-T2 cell line displays most of the Na+ transport characteristics of well-differentiated primary cells in the first days of culture. We conclude that the SV40-T2 cell line provides a model of differentiated alveolar type II cells and may be a powerful tool to study, in vitro, the modulation of Na+ transport in pathophysiological conditions.
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Affiliation(s)
- P Michaut
- Department of Physiology, Faculté de Médecine Xavier Bichat, Université Denis Diderot, Paris, France
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Abstract
Channel inducing factor (CHIF) is a novel cDNA recently cloned from a rat distal colon cDNA library of dexamethasone-treated animals. While its expression in Xenopus oocytes evokes a potassium channel activity similar to that induced by Isk (minK), its cellular role is not clear. CHIF exhibits significant homologies with proteins that are putatively regulatory (phospholemman, gamma-subunit of Na(+)-K(+)-ATPase, Mat-8) while it differs from the small-conductance potassium channel Isk. We have studied the tissue specificity of CHIF expression in rat by in situ hybridization. CHIF is selectively present in the distal parts of the nephron (medullary and papillary collecting ducts and end portions of cortical collecting tubule) and in the epithelial cells of the distal colon. No expression of CHIF was found in renal proximal tubule, loop of Henle and distal tubule, proximal colon, small intestine, lung, choroid plexus, salivary glands, or brain. To gain some insight into CHIF function, we have investigated, using in situ hybridization and ribonuclease protection assay, whether CHIF mRNA expression could be altered in some situations. In the distal colon, corticosteroid hormones, sodium restriction, low-potassium diet, and metabolic acidosis significantly increased CHIF mRNA expression. In the kidney, metabolic acidosis was the only condition that showed an increase in CHIF mRNA expression. Some of these treatments also altered the expression of the colonic H(+)-K(+)-ATPase mRNA. In summary, CHIF mRNA is selectively expressed in the medullary collecting duct of the kidney and in the epithelium of the distal colon; its expression varies differently in these two target tissues after alterations in corticosteroid status, potassium depletion, and metabolic acidosis. The precise cell-specific functions of CHIF remain to be established.
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Affiliation(s)
- C Capurro
- Institut National de la Santé et de la Recherche Médicale U. 246, Paris, France
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Escoubet B, Coureau C, Blot-Chabaud M, Bonvalet JP, Farman N. Corticosteroid receptor mRNA expression is unaffected by corticosteroids in rat kidney, heart, and colon. Am J Physiol 1996; 270:C1343-53. [PMID: 8967434 DOI: 10.1152/ajpcell.1996.270.5.c1343] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hormones can regulate the expression of their own receptor. We have examined whether adrenalectomy (ADX) and hormone replacement by physiological doses of aldosterone or dexamethasone could modulate the expression of glucocorticoid receptor (GR) or mineralocorticoid receptor (MR) at the mRNA level in the rat kidney, distal colon, and heart. Adult rats were adrenalectomized and received or did not receive an infusion of aldosterone (5 micrograms.100 g-1.day-1) or dexamethasone (10 micrograms.100 g-1.day-1). No significant change in steady-state levels of both MR and GR mRNA was detectable by using ribonuclease (RNase) protection assay (RPA) after either ADX or hormone replacement. Because the kidney is heterogeneous with regard to MR expression, RPA was adapted for measurements on microdissected nephron segments. GR mRNA is expressed at comparable levels all along the nephron, whereas MR mRNA is restricted to the distal nephron. No effect of ADX or GR and MR mRNA levels was detected in any nephron segment that was either aldosterone sensitive or insensitive. In situ hybridization confirmed the absence of corticosteroid-dependent modulation of MR mRNA in all kidney cell types. We conclude that variations of corticosteroid status do not affect MR and GR mRNA steady-state levels in heart, colon, and kidney and thus do not participate to the functional adaptations that are known to depend on hormonal status.
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Affiliation(s)
- B Escoubet
- Institut National de la Santé et de la Recherche Médicale U246, Faculté de Médecine Xavier Bichat, Paris, France
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40
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Roudier-Pujol C, Rochat A, Escoubet B, Eugène E, Barrandon Y, Bonvalet JP, Farman N. Differential expression of epithelial sodium channel subunit mRNAs in rat skin. J Cell Sci 1996; 109 ( Pt 2):379-85. [PMID: 8838661 DOI: 10.1242/jcs.109.2.379] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Three subunits (alpha, beta, gamma) of the amiloride-sensitive epithelial sodium channel have been recently characterized. The channel subunits have significant homologies with the Caenorhabditis elegans mec-4, mec-10 and deg-1 genes, which are involved in control of cell volume and mecanotransduction. These subunits are coexpressed at equivalent levels in the renal collecting duct and the distal colon epithelium which are high resistance sodium transporting epithelia. We have investigated whether these subunits were expressed, at the mRNA level, in transporting as well as non transporting epithelial cells of rat skin. In full-thickness abdominal skin only alpha and gamma subunit mRNAs were detected, while all three subunit mRNAs were present in sole skin, as demonstrated by RNase-protection assay. Furthermore, the level of expression of each subunit varied with the epithelial cell type as demonstrated by in situ hybridization: epidermal and follicular keratinocytes express mostly alpha and gamma subunits (while beta was low); a prevalence of beta and gamma was observed in sweat glands. Thus, it appeared that two out of the three subunit mRNAs predominated in each epithelial structure. In addition, mRNAs of the alpha, beta and gamma subunits of the amiloride-sensitive sodium channel were expressed at a higher level in large suprabasal epidermal keratinocytes (which undergo terminal differentiation) than in small proliferative basal keratinocytes.
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Affiliation(s)
- C Roudier-Pujol
- INSERM U246, Institut Fédératif de Recherche Cellules Epithéliales, Paris, France
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41
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Jaisser F, Escoubet B, Coutry N, Eugene E, Bonvalet JP, Farman N. Differential regulation of putative K(+)-ATPase by low-K+ diet and corticosteroids in rat distal colon and kidney. Am J Physiol 1996; 270:C679-87. [PMID: 8779935 DOI: 10.1152/ajpcell.1996.270.2.c679] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
K+ homeostasis depends on K+ absorption in digestive and renal epithelia. Recently, a cDNA encoding for a putative K(+)-adenosinetriphosphatase (ATPase) alpha-subunit has been characterized. We studied its expression by ribonuclease protection assay and in situ hybridization in the distal colon and the kidney of rats in various physiological states. In the distal colon of control rats, high expression of the colonic putative K(+)-ATPase mRNA was restricted to the surface epithelial cells. A low-K+ diet did not modify this expression, adrenalectomy decreased it, and aldosterone or dexamethasone treatment for 2 days restored normal levels. In the kidney of control rats, levels of K(+)-ATPase mRNA were very low. A low-K+ diet revealed a clear mRNA expression, which is consistent with a recent report [J.A. Kraut, F. Starr, G. Sachs, and M. Reuben. Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F581-F587, 1995]. This expression was restricted to the outer medullary collecting duct, presumably in principal cells. Changes in corticosteroid status did not influence the renal expression. Our results, together with previous studies on K+ absorption and K(+)-ATPase activity, suggest that more than a single molecular form of K(+)-ATPase is likely to be responsible for the regulation of K+ absorption in the colon and distal nephron.
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Affiliation(s)
- F Jaisser
- Institut National de la Santé et de la Recherche Médicale, U246, Faculté de Médecine Xavier Bichat, Paris, France
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42
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Turner G, Coureau C, Rabin MR, Escoubet B, Hruby M, Walrant O, Silve C. Parathyroid hormone (PTH)/PTH-related protein receptor messenger ribonucleic acid expression and PTH response in a rat model of secondary hyperparathyroidism associated with vitamin D deficiency. Endocrinology 1995; 136:3751-8. [PMID: 7649081 DOI: 10.1210/endo.136.9.7649081] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of the present work was to characterize at the molecular level the mechanism of PTH resistance in a rat model of secondary hyperparathyroidism resulting from vitamin D deprivation. PTH/PTH-related protein (PTHrp) receptor messenger RNA (mRNA) expression, assayed by ribonuclease protection analysis, was studied in the kidney, femoral epi/metaphysis, and diaphysis. In addition, in the kidney, PTH/PTHrp receptor mRNA expression was correlated to receptor function by measuring adenyl cyclase activity in crude renal membranes after stimulation by PTH (10(-10) - 10(-6) M), forskolin (0.1 and 0.2 mM), NaF (5 and 10 mM), and isoproterenol (1 and 10 microM). Four groups of rats were studied to investigate the effects of calcium, PTH, and/or vitamin D status. The first group received a control diet (D+D+). The second group received a diet deficient in vitamin D until death (D-D-). In the two other groups that also received a vitamin D-deficient diet, the hypocalcemia and the hyperparathyroidism were later corrected, by either vitamin D supplementation (D-D+) or lactose and high calcium diet (D-Ca+), 1 week before death. The results revealed a 2-fold decrease in the PTH-induced adenyl cyclase activity of the renal membranes in the D-D- rats compared to those in the three other groups. There was no significant difference in the four groups in adenyl cyclase activity stimulated by forskolin, NaF, and isoproterenol. The decrease in PTH-induced adenyl cyclase activity was associated with an approximately 2-fold increase in PTH/PTHrp receptor mRNA expression in the kidneys of the D-D- rats compared to controls. Normalization of PTH/PTHrp receptor mRNA expression was observed after vitamin D supplementation (D-D+ rats), but not after correction of the hypocalcemia and secondary hyperparathyroidism by oral lactose and calcium supplementation. In the epi/metaphysis, an approximately 2-fold increase in PTH/PTHrp receptor mRNA was also observed in the D-D- rats compared to the controls; this increase was partially corrected upon normalization of the calcemia and PTH levels with either vitamin D (D-D+ group) or lactose/calcium (D-Ca+ group). In the diaphysis, no change in the expression of PTH/PTHrp receptor mRNA was observed in any group.(ABSTRACT TRUNCATED AT 400 WORDS)
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MESH Headings
- Adenylyl Cyclases/analysis
- Adenylyl Cyclases/physiology
- Animals
- Calcium/blood
- Calcium/metabolism
- Calcium/pharmacology
- Cell Membrane/chemistry
- Cell Membrane/ultrastructure
- Colforsin/pharmacology
- Diaphyses/chemistry
- Diaphyses/metabolism
- Diaphyses/ultrastructure
- Disease Models, Animal
- Femur/chemistry
- Femur/metabolism
- Femur/ultrastructure
- Food, Fortified
- Hyperparathyroidism, Secondary/blood
- Hyperparathyroidism, Secondary/etiology
- Hyperparathyroidism, Secondary/metabolism
- Isoproterenol/pharmacology
- Kidney/chemistry
- Kidney/ultrastructure
- Lactose/pharmacology
- Male
- Parathyroid Hormone/blood
- Parathyroid Hormone/metabolism
- Phosphates/blood
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- Rats
- Rats, Wistar
- Receptor, Parathyroid Hormone, Type 1
- Receptors, Parathyroid Hormone/genetics
- Receptors, Parathyroid Hormone/metabolism
- Sodium Fluoride/pharmacology
- Vitamin D/pharmacology
- Vitamin D Deficiency/complications
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Affiliation(s)
- G Turner
- INSERM U-426, Faculté de Médecine Xavier Bichat, Paris, France
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Ernest S, Coureau C, Escoubet B. Deprivation of phosphate increases IGF-II mRNA in MDCK cells but IGFs are not involved in phosphate transport adaptation to phosphate deprivation. J Endocrinol 1995; 145:325-31. [PMID: 7616166 DOI: 10.1677/joe.0.1450325] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Phosphate (Pi) deprivation and IGFs stimulate renal Pi reabsorption. We studied the involvement of IGFs in the adaptation of Pi transport to Pi deprivation in MDCK cells. Deprivation of Pi for 15 h increased the steady-state content of IGF-II mRNA (77 +/- 12%) whereas IGF-I mRNA was not detectable in MDCK cells in either control or Pi-deprived cells. IGF-II (10(-7) M) and IGF-I (10(-8) M) stimulated the Na-dependent Pi uptake (1.23- and 1.3-fold increase at 15 h respectively). The effect of IGF-I appeared after 15 h and increased up to 40 h of treatment (2.15-fold increase). In contrast, Pi uptake was increased by Pi deprivation as early as 8 h (1.5-fold) and up to 40 h of Pi deprivation (1.9-fold increase). IGF-II mRNA was not increased before 15 h of Pi deprivation and returned to control at 40 h. The combination of IGF-I and Pi deprivation had a more than additive effect on Pi transport (fivefold increase) (P < 0.001). At variance with Pi deprivation, high concentrations of insulin stimulated Na-coupled alanine transport (6 +/- 2% and 16 +/- 4% in Pi-treated and Pi-depleted cells respectively). Pi deprivation and high concentrations of insulin decreased Na,K-ATPase activity (-48 and -64% respectively) and these effects were not additive.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Ernest
- Institut National de la Santé et de la Recherche Médicale U 251, Faculté de Médecine Xavier Bichat, Université Denis Diderot Paris, France
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Suarez F, Lebrun JJ, Lecossier D, Escoubet B, Coureau C, Silve C. Expression and modulation of the parathyroid hormone (PTH)/PTH-related peptide receptor messenger ribonucleic acid in skin fibroblasts from patients with type Ib pseudohypoparathyroidism. J Clin Endocrinol Metab 1995; 80:965-70. [PMID: 7883858 DOI: 10.1210/jcem.80.3.7883858] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To explore the possibility that defects in the regulation of expression of the messenger ribonucleic acid (mRNA) coding for the PTH receptor could be involved in pseudohypoparathyroidism type Ib (PHP-Ib), PTH-induced cAMP production and PTH/PTH-related peptide (PTH-rp) receptor mRNA expression, measured using a ribonuclease protection assay, were compared in untreated and dexamethasone (dexa)-pretreated (5 x 10(-7) mol/L; 7 days) cultured skin fibroblasts from controls (n = 4) and patients with PHP-Ib (n = 6). In control fibroblasts, stimulation of cAMP production by PTH and expression of PTH/PTH-rp receptor mRNA were easily detectable and were not significantly affected by dexa pretreatment. In fibroblasts from three PHP-Ib patients demonstrating reduced PTH-induced cAMP production that was reversed by dexa, the level of basal PTH/PTH-rp receptor mRNA was also reduced, but increased to levels similar to those in control cells after dexa pretreatment. In fibroblasts from a patient with resistance to PTH not reversed by dexa, PTH/PTH-rp receptor mRNA expression was also significantly lower than that in control cells (18 +/- 13%; P < 0.001) and remained only 30 +/- 15% of that observed in control cells after dexa pretreatment (P < 0.001). In fibroblasts from two PHP-Ib patients expressing normal cAMP responsiveness to PTH before and after dexa treatment, the level of PTH/PTH-rp receptor mRNA was not different from that in control cells before or after dexa treatment. Thus, in all conditions where PTH-induced cAMP production by PHP-Ib fibroblasts was reduced, the abnormality could be explained by the reduced level of PTH/PTH-rp receptor mRNA in these cells. These results suggest that defects in the regulation of expression of the PTH/PTH-rp receptor mRNA, not structural defects in the receptor itself, explain the PTH resistance in PHP-Ib in the patients evaluated, but several different defects must exist.
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Affiliation(s)
- F Suarez
- CNRS URA583, Hôpital Necker Enfants Malades, Faculté de Médecine, Paris, France
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Suarez F, Lebrun J, Lecossier D, Escoubet B, Coureau C, Silve C. Expression de l'ARNm du récepteur de la parathormone dans les fibroblastes cutanés de malades avec pseudohypoparathyroïdie de type 1b. Arch Pediatr 1995. [DOI: 10.1016/0929-693x(95)90157-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
The events accounting for the adaptation of the sodium-dependent phosphate cotransport (Na-Pi) to phosphate deprivation other than genomic regulation remain unknown. The involvement of changes in intracellular calcium concentration was investigated in Madin-Darby canine kidney (MDCK) cells. Calcium concentration was decreased by 15 h of phosphate deprivation (-24 to -35%) or low-calcium medium (calcium deprivation) (-45%), or 8-(N,N'-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB8) (-32%). Calcium deprivation stimulated Na-Pi (2-fold at 1 h and up to 15 h) by increasing the affinity for phosphate. Combined calcium and phosphate deprivation had more than additive effects on phosphate uptake. The effect of a 15-h calcium deprivation, but not of a 2-h one, was dependent on gene transcription and protein synthesis. TMB8 stimulated phosphate uptake similarly to phosphate deprivation (increase in maximum velocity dependent on gene transcription). The ionophore A23187 decreased basal Na-Pi as well as its stimulation by phosphate or calcium deprivation or by TMB8. Calcium deprivation stimulated (3.2-fold increase) the sodium-coupled alanine transport, whereas phosphate deprivation and TMB8 did not. We conclude that 1) phosphate deprivation decreases intracellular calcium concentration, 2) low intracellular calcium concentration is instrumental in the stimulation by prolonged calcium or phosphate deprivation of Na-Pi, and 3) phosphate or calcium deprivation modulates Na-Pi through different cellular pathways.
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Affiliation(s)
- B Escoubet
- Department of Physiology, Faculté de Médecine X Bichat, Université Paris, France
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47
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Abstract
It is accepted that renal phosphate wasting is the basis of hypophosphataemia in vitamin D-resistant hypophosphataemic rickets (VDRR). Abnormal renal adaptation to phosphate deprivation has also been reported in these patients. We studied sodium-dependent phosphate transport and its modulation by phosphate deprivation in skin fibroblasts cultured from healthy subjects and patients with VDRR. Control fibroblasts exhibited high-affinity sodium-dependent phosphate transport (77 +/- 12 mumol/l) which resembled the ubiquitous transport of renal and non-renal cells. Phosphate deprivation (incubation in low phosphate medium) increased the maximal velocity (Vmax) of the transport by 2.7-fold after 24 h, with no change in the affinity. The increase in Vmax was dependent on gene transcription and protein synthesis. The sodium-dependent phosphate transport exhibited in fibroblasts from VDRR patients did not significantly differ from that of control subjects, except that the Vmax of the phosphate transport was higher in cells from patients with VDRR under normal and phosphate-deprivation conditions, although the difference was significant only after 24 h of phosphate deprivation (Vmax: 22.6 +/- 2.4 pmol/mg protein per s in VDRR vs 16 +/- 3.6 pmol/mg protein per s in controls, P less than 0.05). These data demonstrate that sodium-coupled phosphate transport in human skin fibroblasts has the properties of ubiquitous sodium-phosphate co-transport and show that this transport is not deficient in patients with VDRR. Indeed paradoxically the Vmax was 40% higher in VDRR than in control subjects after 24 h of phosphate deprivation. The transport must be either different from that of kidney cells responsible for the phosphate leak, or differently modulated.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- B Escoubet
- INSERM U251, Faculté de Médecine X Bichat, Université Paris 7, France
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48
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Escoubet B, Garestier MC, Cherqui G, Amiel C. PKC and Pi deprivation modulate differently the ubiquitous Na-dependent Pi uptake in MDCK cells. Am J Physiol 1991; 260:F235-42. [PMID: 1996673 DOI: 10.1152/ajprenal.1991.260.2.f235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The role of protein kinase C (PKC) in the modulation of the ubiquitous sodium-dependent phosphate transport and in adaptation of that transport to phosphate deprivation was investigated in MDCK cells. Phorbol myristate acetate (PMA) had a biphasic effect on sodium-dependent phosphate uptake characterized by early inhibition (-25% at 1 h) followed by late stimulation (2.3-fold at 15 h). Late stimulation was related to a decreased apparent affinity (Km) with unchanged maximal velocity (Vmax). The 15-h stimulation of phosphate uptake was also induced by an initial 1-h PMA treatment followed by a 14-h washout of PMA or by R59 022. The stimulation was inhibited by PKC downregulation. PMA stimulation was dependent on protein synthesis but not on transcription, as shown by the respective effects of cycloheximide, 3'-deoxyadenosine, and actinomycin D. In phosphate-deprived cells PMA had also a biphasic effect. A potentiation of PMA stimulation of phosphate uptake with phosphate deprivation was observed. Adaptation to phosphate deprivation was not prevented by PKC downregulation. Cytosolic and membranous PKC activities were not changed by 15-h phosphate deprivation. We conclude that 1) PKC modulates sodium-dependent phosphate uptake in MDCK cells, and 2) phosphate deprivation and PKC modulation of sodium-dependent phosphate uptake involve different cellular pathways; that is, phosphate deprivation acts through gene regulation, and PKC acts through translation regulation.
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Affiliation(s)
- B Escoubet
- Department of Physiology, Faculté de Médecine X. Bichat, Institut National de la Santé et de la Recherche Médicale Unité 251, Paris, France
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Roux S, Escoubet B, Friedlander G, Le Grimellec C, Bertrand I, Amiel C. Effects of lidocaine on sarcolemmal fluidity and cellular cAMP in rat cardiomyocytes. Am J Physiol 1989; 256:H422-7. [PMID: 2537034 DOI: 10.1152/ajpheart.1989.256.2.h422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Antiarrhythmic drugs with local anesthetic properties modify the physical state of membrane phospholipids and could change adenylate cyclase activity and, thus, influence cardiac ischemic arrhythmias. Adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in cardiomyocytes cultured from newborn rat and fluorescence anisotropy of sarcolemma-enriched membranes were investigated in the presence of a neutral anesthetic drug benzyl alcohol and of a cationic anesthetic drug lidocaine. Benzyl alcohol increased in a dose-dependent manner both sarcolemma fluidity and isoproterenol- or cholera toxin-stimulated cAMP accumulation. In contrast, benzyl alcohol inhibited cAMP accumulation in forskolin-stimulated cells. Lidocaine induced a dose-related inhibition of isoproterenol-, forskolin-, and cholera toxin-stimulated cAMP accumulation without eliciting any change in sarcolemma fluidity. The inhibitory effect of lidocaine on isoproterenol-stimulated cAMP accumulation was reversed when cells were pretreated with pertussis toxin. These data suggest that the inhibitory effect of lidocaine on cAMP synthesis might involve a polar interaction with the Gi regulatory subunit of adenylate cyclase. Such an effect could contribute, in vivo, to both the antiarrhythmic and the negative inotropic effect of lidocaine.
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Affiliation(s)
- S Roux
- U. 251, Département de Physiologie, Faculté de Médecine X. Bichat, Université Paris VII, France
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50
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Abstract
Phosphate enters kidney proximal tubular cells through an apical sodium-phosphate cotransport; this activity (Vmax) increases during phosphate deprivation (Kidney Int. 18: 36-47, 1980). This study investigated the mechanism of phosphate uptake and its adaptation to phosphate deprivation in cultured cells from different origins (kidney, LLC-PK1 and MDCK cells; liver, Fao cells; heart, myocyte primary cultures). All cells exhibited a sodium-dependent phosphate uptake that was reduced (greater than 75%) by external sodium substitution and inhibited by ouabain (35%) and 2,4-dinitrophenol or KCN (80%). Phosphate deprivation (exposure to phosphate-free medium) increased sodium-dependent phosphate uptake by 1.8- to 5.8-fold and decreased cell inorganic phosphate and ATP contents (70-80 and 17-30%, respectively). The stimulation of phosphate uptake resulted from an increase in Vmax without change in Km and was dependent on gene transcription and protein synthesis because it was inhibited by cycloheximide and 3-deoxyadenosine. Thus a deprivation-stimulated, sodium-dependent phosphate transport was demonstrated in cells originating from distal kidney tubules, liver, and heart. The findings suggest that in hypophosphatemic diseases, impairment of renal proximal phosphate reabsorption might be only one expression of a widespread alteration of cell phosphate regulation.
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Affiliation(s)
- B Escoubet
- Institut National de la Santé et de la Recherche Médicale U. 251, Département de Physiologie, Faculté de Médecine X. Bichat, Université Paris 7, France
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