The essential role of H2O2 in the regulation of intracellular Ca2+ by epidermal growth factor in rat-2 fibroblasts.
We have investigated a new mechanism by which epidermal growth factor (EGF) increases intracellular Ca(2+) ([Ca(2+)](i)) in Rat-2 fibroblasts. EGF induced a transient increase of [Ca(2+)](i), and sustained Ca(2+) increase disappeared in the absence of extracellular Ca(2+). However, EGF had no effect on the formation of inositol phosphates. Expression of N17Rac or scrape-loading of C3 transferase blocked the elevation of [Ca(2+)](i) by EGF, but not by lysophosphatidic acid (LPA). EGF increased intracellular H(2)O(2), with a maximal increase at 5 min, which was blocked by catalase, scrape-loading of C3 transferase, or expression of N17Rac. H(2)O(2) scavengers, catalase and N-acetyl-L-cysteine, also blocked the Ca(2+) response to EGF, but not to LPA. In the presence of EGTA, preincubation with EGF completely inhibited subsequent Ca(2+) response to extracellular H(2)O(2) and vice versa. Incubation with EGF or phosphatidic acid abolished subsequent elevation of [Ca(2+)](i) by phosphatidic acid or EGF, respectively. Furthermore, preincubation with LPA inhibited the subsequent Ca(2+) response to EGF, but not vice versa. These results suggested that intracellular H(2)O(2) regulated by Rac and RhoA, but not inositol phosphates, was responsible for the EGF-stimulated elevation of [Ca(2+)](i). It was also suggested that EGF cross talked with LPA in the regulation of [Ca(2+)](i) by producing intracellular H(2)O(2).
Lee
Z W
ZW
Biomolecule Research Group, Korea Basic Science Institute, Taejon, South Korea.
Kweon
S M
SM
Kim
S J
SJ
Kim
J H
JH
Cheong
C
C
Park
Y M
YM
Ha
K S
KS
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D001905:Botulinum Toxins; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002374:Catalase / Q000494:pharmacology; D002460:Cell Line; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005347:Fibroblasts / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D051381:Rats; D020239:Receptor Cross-Talk / Q000502:physiology; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D016166:Free Radical Scavengers; D008246:Lysophospholipids; D016877:Oxidants; D004815:Epidermal Growth Factor; D006861:Hydrogen Peroxide; D002374:Catalase; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D002118:Calcium; D000111:Acetylcysteine