Abstract
Background: Podocytes play a critical role in the pathogenesis of glomerulosclerosis. Increasing evidence suggests that aldosterone (ALD) is involved in the initiation and progression of glomerular damage. It is, however, unknown whether there is a direct injurious effect of ALD on podocytes. Therefore, in the present study, we evaluated the effect of ALD on podocyte apoptosis and studied the role of phosphatidylinositol 3-kinase/Akt (PI3-K/Akt) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways in this process. Methods: Podocytes were incubated in media containing either buffer or increasing concentrations of ALD (10–9∼10–5M) for variable time periods. The cells were also treated with either wortmannin (inhibitor of PI3-K, 100 nM), SB202190 (SB20, inhibitor of p38MAPK, 10 μM) or buffer. All treatments were performed with or without ALD (10–7M) for 24 h. At the end of the incubation period, apoptosis was evaluated by cell nucleus staining and flow cytometric analyses. Activation of PI3-K/Akt and p38MAPK phosphorylation of cultured rat podocytes was evaluated by performing Akt kinase assay and Western blot, respectively. Results: Apoptosis of cultured rat podocytes was induced by ALD in a dose- and time-dependent manner. ALD inhibited the activity of PI3-K/Akt and increased the activation of p38MAPK. PI3-K/Akt activity was further inhibited by the addition of wortmannin to the cells in the presence of ALD. This was accompanied by a significant increase in apoptosis. ALD-induced p38MAPK phosphorylation and apoptosis were inhibited when the cells were pretreated with SB20. Furthermore, treatment with spironolactone not only attenuated the proapoptotic effect of ALD, but also significantly reversed its effects on PI3-K/Akt and p38MAPK signaling pathways. Conclusion: ALD induces apoptosis in rat podocytes through inhibition of PI3-K/Akt and stimulation of p38 MAPK signaling pathways. Spironolactone attenuates ALD-induced podocyte apoptosis, thereby positioning this compound as a potential promising target of intervention in human renal damage.
Journal Section:
Original Paper
References
1.
Espiner E, Nicholls M: The Renin Angiotensin System. London, Gower Medical Publishing, 2002, pp 1–33.
2.
Brown NJ: Aldosterone and end-organ damage. Curr Opin Nephrol Hypertens 2005;14:235–241.
[PubMed]
3.
Miric G, Dallemagne C, Endre Z, et al: Reversal of cardiac and renal fibrosis by pirfenidone and spironolactone in streptozotocin-diabetic rats. Br J Pharmacol 2001;133:687–694.
[PubMed]
4.
Rocha R, Chander PN, Zuckerman A, et al: Role of aldosterone in renal vascular injury in stroke-prone hypertensive rats. Hypertension 1999;33:232–237.
[PubMed]
5.
Sun Y, Zhang J, Lu L, et al: Aldosterone-induced inflammation in the rat heart: role of oxidative stress. Am J Pathol 2002;161:1773–1781.
[PubMed]
6.
Furukawa T, Ohno S, Oguchi H, et al: Morphometric study of glomerular slit diaphragms fixed by rapid-freezing and freeze-substitution. Kidney Int 1991;40:621–624.
[PubMed]
7.
Aldigier JC, Kanjanbuch T, Ma LJ, et al: Regression of existing glomerulosclerosis by inhibition of aldosterone. J Am Soc Nephrol 2005;16:3306–3314.
[PubMed]
8.
Rocha R, Stier CT Jr, Kifor I, et al: Aldosterone: a mediator of myocardial necrosis and renal arteriopathy. Endocrinology 2000;141:3871–3878.
[PubMed]
9.
Boldyreff B, Wehling M: Non-genomic actions of aldosterone: mechanisms and consequences in kidney cells. Nephrol Dial Transplant 2003;18:1693–1695.
[PubMed]
10.
Haseroth K, Gerdes D, Berger S, et al: Rapid nongenomic effects of aldosterone in mineralocorticoid-receptor-knockout mice. Biochem Biophys Res Commun 1999;266:257–261.
[PubMed]
11.
Kriz W, Gretz N, Lemley KV: Progression of glomerular diseases: is the podocyte the culprit? Kidney Int 1998;54:687–697.
[PubMed]
12.
Schiffer M, Bitzer M, Roberts IS, et al: Apoptosis in podocytes induced by TGF-beta and Smad7. J Clin Invest 2001;108:807–816.
[PubMed]
13.
Ding G, Reddy K, Kapasi AA, et al: Angiotensin II induces apoptosis in rat glomerular epithelial cells. Am J Physiol Renal Physiol 2002;283:F173–F180.
[PubMed]
14.
Wada T, Pippin JW, Marshall CB, et al: Dexamethasone prevents podocyte apoptosis induced by puromycin aminonucleoside: role of p53 and Bcl-2-related family proteins. J Am Soc Nephrol 2005;16:2615–2625.
[PubMed]
15.
Susztak K, Raff AC, Schiffer M, et al: Glucose-induced reactive oxygen species cause apoptosis of podocytes and podocyte depletion at the onset of diabetic nephropathy. Diabetes 2006;55:225–233.
[PubMed]
16.
Burniston JG, Saini A, Tan LB, et al: Aldosterone induces myocyte apoptosis in the heart and skeletal muscles of rats in vivo. J Mol Cell Cardiol 2005;39:395–399.
[PubMed]
17.
De Angelis N, Fiordaliso F, Latini R, et al: Appraisal of the role of angiotensin II and aldosterone in ventricular myocyte apoptosis in adult normotensive rat. J Mol Cell Cardiol 2002;34:1655–1665.
[PubMed]
18.
Ding G, van Goor H, Ricardo SD, et al: Oxidized LDL stimulates the expression of TGF-beta and fibronectin in human glomerular epithelial cells. Kidney Int 1997;51:147–154.
[PubMed]
19.
Lecoeur H, Prevost MC, Gougeon ML: Oncosis is associated with exposure of phosphatidylserine residues on the outside layer of the plasma membrane: a reconsideration of the specificity of the annexin V/propidium iodide assay. Cytometry 2001;44:65–72.
[PubMed]
20.
Ding G, Franki N, Kapasi AA, et al: Tubular cell senescence and expression of TGF-beta1 and p21(WAF1/CIP1) in tubulointerstitial fibrosis of aging rats. Exp Mol Pathol 2001;70:43–53.
[PubMed]
21.
Furukawa T, Ohno S, Oguchi H, et al: Morphometric study of glomerular slit diaphragms fixed by rapid-freezing and freeze-substitution. Kidney Int 1991;40:621–624.
[PubMed]
22.
Griendling KK, Harrison DG: Dual role of reactive oxygen species in vascular growth. Circ Res 1999;85:562–563.
[PubMed]
23.
Lodha S, Dani D, Mehta R, et al: Angiotensin II-induced mesangial cell apoptosis: role of oxidative stress. Mol Med 2002;8:830–840.
[PubMed]
24.
Blasi ER, Rocha R, Rudolph AE, et al: Aldosterone/salt induces renal inflammation and fibrosis in hypertensive rats. Kidney Int 2003;63:1791–1800.
[PubMed]
25.
Nagase M, Shibata S, Yoshida S, et al: Podocyte injury underlies the glomerulopathy of Dahl salt-hypertensive rats and is reversed by aldosterone blocker. Hypertension 2006;47:1084–1093.
[PubMed]
26.
Nagase M, Fujita T: Aldosterone and glomerular podocyte injury. Clin Exp Nephrol 2008;12:233–242.
[PubMed]
27.
Lawlor MA, Alessi DR: PKB/Akt: a key mediator of cell proliferation, survival and insulin responses. J Cell Sci 2001;114:2903–2910.
[PubMed]
28.
Widmann C, Gibson S, Jarpe MB, et al: Mitogen-activated protein kinase: conservation of a three-kinase module from yeast to human. Physiol Rev 1999;79:143–180.
[PubMed]
29.
Alvarado-Kristensson M, Porn-Ares MI, Grethe S, et al: p38 Mitogen-activated protein kinase and phosphatidylinositol 3-kinase activities have opposite effects on human neutrophil apoptosis. FASEB J 2002;16:129–131.
[PubMed]
30.
Foster RR, Saleem MA, Mathieson PW, et al: Vascular endothelial growth factor and nephrin interact and reduce apoptosis in human podocytes. Am J Physiol Renal Physiol 2005;288:F48–F57.
[PubMed]
31.
Saldeen J, Lee JC, Welsh N: Role of p38 mitogen-activated protein kinase (p38 MAPK) in cytokine-induced rat islet cell apoptosis. Biochem Pharmacol 2001;61:1561–1569.
[PubMed]
32.
Cross DA, Alessi DR, Cohen P, et al: Inhibition of glycogen synthase kinase-3 by insulin mediated by protein kinase B. Nature 1995;378:785–789.
[PubMed]
33.
Carpenter CL, Duckworth BC, Auger KR, et al: Purification and characterization of phosphoinositide 3-kinase from rat liver. J Biol Chem 1990;265:19704–19711.
[PubMed]
34.
Mano A, Tatsumi T, Shiraishi J, et al: Aldosterone directly induces myocyte apoptosis through calcineurin-dependent pathways. Circulation 2004;110:317–323.
[PubMed]
35.
Lai XX, Ding GH, Huang CX, et al: Angiotensin II-induced podocyte apoptosis: role of the MAPK subtypes. Beijing Da Xue Xue Bao 2004;36:131–134.
[PubMed]
36.
Pitt B, Zannad F, Remme WJ, et al: The effect of spironolactone on morbidity and mortality in patients with severe heart failure. Randomized Aldosterone Evaluation Study Investigators. N Engl J Med 1999;341:709–717.
[PubMed]
37.
Pitt B, Leopold JA: A role for mineralocorticoid receptor blockade in the prevention of apoptosis. J Mol Cell Cardiol 2005;39:415–417.
[PubMed]
38.
Williams TA, Verhovez A, Milan A, et al: Protective effect of spironolactone on endothelial cell apoptosis. Endocrinology 2006;147:2496–2505.
[PubMed]
39.
Lee YS, Kim JA, Kim KL, et al: Aldosterone upregulates connective tissue growth factor gene expression via p38 MAPK pathway and mineralocorticoid receptor in ventricular myocytes. J Korean Med Sci 2004;19:805–811.
[PubMed]
© 2009 S. Karger AG, Basel
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
2009
You do not currently have access to this content.
