Regulation of the renal Na-HCO(3) cotransporter. XI. Signal transduction underlying CO(2) stimulation.
We have previously shown that CO(2) stimulation of the renal Na-HCO(3) cotransporter (NBC) activity is abrogated by general inhibitors of protein tyrosine kinases. The more selective inhibitor herbimycin also blocked this effect at concentrations known to preferentially inhibit Src family kinases (SFKs). We therefore examined a role for SFKs in CO(2)-stimulated NBC activity. To this end, we engineered OK cells to express the COOH-terminal Src kinase (Csk), a negative regulator of SFKs. CO(2) stimulated NBC activity normally in beta-galactosidase-expressing and untransfected control cells. In contrast, Csk-expressing cells had normal baseline NBC activity that was not stimulated by CO(2). CO(2) stimulation increased both total SFK activity and specific tyrosine phosphorylation of Src. The specific MEK1/2 inhibitor PD-98059 completely inhibited the CO(2) stimulation of NBC activity as well as the accompanying phosphorylation and activation of ERK1/2. Our data suggest the involvement of both SFKs, probably Src, and the "classic" MAPK pathway in mediating CO(2)-stimulated NBC activity in renal epithelial cells.
Ruiz
O S
OS
University of Illinois at Chicago, West Side Division, Chicago, Illinois 60612-7315, USA. osruiz@uic.edu
Robey
R B
RB
Qiu
Y Y
YY
Wang
L J
LJ
Li
C J
CJ
Ma
J
J
Arruda
J A
JA
D000818:Animals; D016227:Benzoquinones; D000081247:CSK Tyrosine-Protein Kinase; D002245:Carbon Dioxide / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism; D047029:Lactams, Macrocyclic; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009893:Opossums; D011505:Protein-Tyrosine Kinases; D011809:Quinones / Q000494:pharmacology; D011817:Rabbits; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000502:physiology*; D027982:Sodium-Bicarbonate Symporters; D019061:src-Family Kinases / Q000378:metabolism
D016227:Benzoquinones; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D047029:Lactams, Macrocyclic; D011809:Quinones; D027982:Sodium-Bicarbonate Symporters; D002245:Carbon Dioxide; D017828:Rifabutin; C020754:herbimycin; D003907:Dexamethasone; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases