1. The essential role of H2O2 in the regulation of intracellular Ca2+ by epidermal growth factor in Rat-2 fibroblasts
- Author
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Jae Hong Kim, Kwon-Soo Ha, Young Mok Park, Soo Jung Kim, Soo-Mi Kweon, Chaejoon Cheong, and Zee Won Lee
- Subjects
Botulinum Toxins ,RHOA ,Gene Expression ,Cell Line ,chemistry.chemical_compound ,Epidermal growth factor ,Lysophosphatidic acid ,Extracellular ,Animals ,Inositol ,Calcium Signaling ,ADP Ribose Transferases ,Epidermal Growth Factor ,biology ,Chemistry ,Free Radical Scavengers ,Hydrogen Peroxide ,Receptor Cross-Talk ,Cell Biology ,Phosphatidic acid ,Fibroblasts ,Catalase ,Oxidants ,Molecular biology ,Acetylcysteine ,Rats ,rac GTP-Binding Proteins ,EGTA ,biology.protein ,Calcium ,Lysophospholipids ,rhoA GTP-Binding Protein ,hormones, hormone substitutes, and hormone antagonists ,Intracellular - Abstract
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).
- Published
- 2000