| Acid increases NHE8 surface expression and activity in NRK cells. | |
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MedLine Citation:
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PMID: 22088432 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We previously demonstrated that there is a paucity of brush-border membrane NHE3 in neonates, the predominant Na(+)/H(+) exchanger in the adult proximal tubule, while NHE8 is relatively highly expressed in neonates compared with adults. We recently showed that metabolic acidosis in neonatal rodents can increase brush-border membrane NHE8 protein expression and Na(+)/H(+) exchange activity. To further examine the regulation of NHE8 by acid, we incubated NRK cells, which express NHE8 but not NHE3, with either acid or control media (6.6 vs. 7.4). There was an increase in Na(+)/H(+) exchanger activity within 6 h of incubation with acid media assessed as the rate of sodium-dependent recovery of pH from an acid load (dpH(i)/dt). The acid stimulation persisted for at least 24 h. The increase in Na(+)/H(+) exchange activity was paralleled by an increase in surface expression of NHE8, assessed by surface biotinylation and streptavidin precipitation. The increase in both apical membrane NHE8 protein expression and Na(+)/H(+) exchange activity with pH 6.6 media compared with 7.4 media was not affected by actinomycin D or cycloheximide consistent with an increase in surface expression independent of mRNA or protein synthesis. Furthermore, there was no increase in total cellular NHE8 protein abundance or mRNA abundance with acid media. Finally, we demonstrate that the increase in surface expression of NHE8 with acid media was blocked by colchicine and cytochalasin D and mediated by acid increasing the rate of exocytosis. In conclusion, NHE8 surface expression and activity are regulated by acid media by increasing the rate of trafficking to the apical membrane. |
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Authors:
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Catherine Joseph; Katherine Twombley; Jyothsna Gattineni; Qiuyu Zhang; Vangipuram Dwarakanath; Michel Baum |
Publication Detail:
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Type: Journal Article Date: 2011-11-16 |
Journal Detail:
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Title: American journal of physiology. Renal physiology Volume: 302 ISSN: 1522-1466 ISO Abbreviation: Am. J. Physiol. Renal Physiol. Publication Date: 2012 Feb |
Date Detail:
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Created Date: 2012-02-08 Completed Date: 2012-04-23 Revised Date: 2013-04-12 |
Medline Journal Info:
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Nlm Unique ID: 100901990 Medline TA: Am J Physiol Renal Physiol Country: United States |
Other Details:
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Languages: eng Pagination: F495-503 Citation Subset: IM |
Affiliation:
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Dept. of Pediatrics, U.T. Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9063, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cell Line Cells, Cultured Hydrogen-Ion Concentration Kidney Tubules, Proximal / cytology, metabolism* Microvilli / metabolism Rats Sodium-Hydrogen Antiporter / genetics, metabolism* |
| Chemical | |
Reg. No./Substance:
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0/NHE8 protein, rat; 0/Sodium-Hydrogen Antiporter |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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