Document Detail


Increased responsiveness to JNK1/2 mediates the enhanced H2O2-induced stimulation of Cl-/HCO3- exchanger activity in immortalized renal proximal tubular epithelial cells from the SHR.
MedLine Citation:
PMID:  20493825     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We have previously demonstrated that exogenous H2O2 stimulates Cl(-)/HCO3(-) exchanger activity in immortalized renal proximal tubular epithelial (PTE) cells from both the Wistar-Kyoto (WKY) rat and the spontaneously hypertensive rat (SHR), this effect being more pronounced in SHR cells. The aim of the present study was to examine the mechanism of H2O2-induced stimulation of Cl(-)/HCO3(-) exchanger activity in WKY and SHR cells. It is now reported that the SHR PTE cells were endowed with an enhanced capacity to produce H2O2, comparatively with WKY cells and this was accompanied by a decreased expression of SOD2, SOD3, and catalase in SHR PTE cells. The stimulatory effect of H2O2 on the exchanger activity was blocked by SP600125 (JNK inhibitor), but not by U0126 (MEK1/2 inhibitor) or SB203580 (p38 inhibitor) in both cell lines. Basal JNK1 and JNK2 protein expression was higher in SHR PTE cells than in WKY PTE cells. H2O2 had no effect on p-JNK1/2 in WKY PTE cells over time. By contrast, H2O2 treatment resulted in a rapid and sustained increase in JNK1/2 phosphorylation in SHR PTE cells, which was completely abolished by apocynin. Treatment of SHR PTE cells with apocynin significantly decreased the H2O2-induced stimulation of Cl(-)/HCO3(-) exchanger activity. It is concluded that H2O2-induced stimulation of Cl(-)/HCO3(-) exchanger activity is regulated by JNK1/2, particularly by JNK2, in SHR PTE cells. The imbalance between oxidant and antioxidant mechanisms in SHR PTE cells enhances the response of JNK1/2 to H2O2, which contributes to their increased sensitivity to H2O2.
Authors:
S Simão; P Gomes; P A Jose; P Soares-da-Silva
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-05-21
Journal Detail:
Title:  Biochemical pharmacology     Volume:  80     ISSN:  1873-2968     ISO Abbreviation:  Biochem. Pharmacol.     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-07-19     Completed Date:  2010-08-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0101032     Medline TA:  Biochem Pharmacol     Country:  England    
Other Details:
Languages:  eng     Pagination:  913-9     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier Inc. All rights reserved.
Affiliation:
Institute of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Line, Transformed
Chloride-Bicarbonate Antiporters / metabolism*
Epithelial Cells / drug effects,  metabolism*
Hydrogen Peroxide / pharmacology*
Hypertension / enzymology,  metabolism
Kidney Tubules, Proximal / drug effects,  metabolism*
Mitogen-Activated Protein Kinase 8 / physiology*
Mitogen-Activated Protein Kinase 9 / physiology*
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Chemical
Reg. No./Substance:
0/Chloride-Bicarbonate Antiporters; 7722-84-1/Hydrogen Peroxide; EC 2.7.1.24/Mitogen-Activated Protein Kinase 9; EC 2.7.11.24/Mitogen-Activated Protein Kinase 8

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