Abstract
Background. In the renal proximal tubule, chronic acidosis causes increases in apical membrane NHE3 activity, which serve to increase transepithelial H+ secretion and return systemic pH to normal levels. Incubation of cultured renal epithelial cells in acid media activates c-Src. Methods. OKP cells were incubated in control (pH 7.4) or acid (7.0) media, and NHE3 activity measured as cytoplasmic pH (pHi) recovery from an acid load using BCECF. c-Src, ERK, and JNK kinase activities were measured by immune complex kinase assays with enolase, MBP, and GST-c-Jun, respectively, as substrates in the in vitro assays. To determine the role of c-Src in acid-induced NHE3 activation, cells were transfected with vector alone or a dominant negative c-Src (c-SrcK295M). Results. Expression of dominant negative c-srcK295M in OKP cells prevented acid-induced activation of NHE3. Incubation of OKP cells in acid media increased ERK activity and c-fos expression, but did not increase JNK activity. Acidosis in vivo also activated renal cortical c-Src and ERK kinases, whereas incubation of 3T3 cells in acid media activated c-Src but not ERK kinase. Expression of c-srcK295M did not affect ERK or c-fos activation by acid incubation. Inhibition of MEK with PD98059 inhibited activation of NHE3 by acid incubation. Conclusions. These studies suggest that acidosis activates c-Src and MEK/ERK/c-fos. While both pathways are necessary for activation of NHE3, they are activated independently.
Original language | English (US) |
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Pages (from-to) | 41-50 |
Number of pages | 10 |
Journal | Kidney international |
Volume | 62 |
Issue number | 1 |
DOIs | |
State | Published - 2002 |
Keywords
- JNK
- MAP kinase
- NIH 3T3 cells
- Na/H antiporter
- OKP cells
- PD98059
- Renal acidification
- Src kinase
- c-fos
ASJC Scopus subject areas
- Nephrology