Critical role of protein kinase C alpha and calcium in growth factor induced activation of the Na(+)/H(+) exchanger NHE1.
The ubiquitously expressed Na(+)/H(+) exchanger (NHE1) plays an important role in the regulation of the intracellular pH. Induction of NHE activity by phorbol esters and inhibition of growth factor-mediated stimulation of the NHE by protein kinase C (PKC) inhibitors suggest an implication of PKCs in the regulation of the NHE. Expression of PKC isotype-specific dominant negative and constitutively active mutants or downregulation of PKC by isotype-specific antisense oligonucleotides revealed that stimulation by epidermal growth factor (EGF) or phorbol ester of the NHE in NIH3T3 cells is a PKC(alpha)-specific effect. Elevation of cytoplasmic calcium by a Ca(2+) ionophore or thapsigargin causes a growth factor-independent stimulation of the NHE predominantly mediated by calcium/calmodulin kinase II. It is concluded that in NIH3T3 cells overexpressing the EGF receptor (EGFR6 cells), EGF requires cPKC(alpha) for the activation of the NHE, while calcium/calmodulin-dependent kinases are essential in thapsigargin induced stimulation of the NHE.
Maly
Karl
K
Institute of Medical Chemistry and Biochemistry, University of Innsbruck, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria. karl.maly@uibk.ac.at
Strese
Kukka
K
Kampfer
Sonja
S
Ueberall
Florian
F
Baier
Gottfried
G
Ghaffari-Tabrizi
Nassim
N
Grunicke
Hans H
HH
Leitges
Michael
M
D016475:3T3 Cells; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000096:biosynthesis / Q000502:physiology*; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D017923:Sodium-Hydrogen Exchangers / Q000096:biosynthesis / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D000099221:Protein Kinase C zeta
D002118:Calcium; D004791:Enzyme Inhibitors; D004815:Epidermal Growth Factor; D007527:Isoenzymes; D020928:Mitogen-Activated Protein Kinases; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D017923:Sodium-Hydrogen Exchangers; D019284:Thapsigargin; D000099221:Protein Kinase C zeta; C069139:growth factor-activatable Na-H exchanger NHE-1; C497259:Prkcd protein, mouse; C497256:Prkce protein, mouse; C496630:Prkca protein, mouse