H2O2-Induced Tyrosine Phosphorylation of Protein Kinase Cδ by a Mechanism Independent of Inhibition of Protein-Tyrosine Phosphatase in CHO and COS-7 Cells

• DOI: 10.1006/bbrc.2000.3048
• Publication Date: 2002-09-16T14:49:19Z
• Authors: Toshiyoshi Yamamoto; Hidenori Matsuzaki; Hiroaki Konishi; Yoshitaka Ono; Ushio Kikkawa
• Keywords: 0303 health sciences; 3T3 Cells; CHO Cells; Hydrogen Peroxide; Enzyme Activation; Isoenzymes; Mice; Protein Kinase C-delta; 03 medical and health sciences; Cricetinae; COS Cells; Animals; Tyrosine; Mitogen-Activated Protein Kinases; Phosphorylation; Protein Tyrosine Phosphatases; Protein Kinase C

It has been proposed that H(2)O(2) increases tyrosine phosphorylation of cellular proteins by inhibiting protein-tyrosine phosphatase through oxidation of the cysteine residue of the enzyme essential for its catalytic activity. Tyrosine phosphorylation of the delta isoform of protein kinase C (PKC) was induced by H(2)O(2) in CHO and COS-7 cells. H(2)O(2) also induced activation of mitogen-activated protein kinase. Vanadate and molybdate, which inhibit protein-tyrosine phosphatase by binding to its active site, did not induce tyrosine phosphorylation of PKCdelta, but enhanced H(2)O(2)-induced tyrosine phosphorylation of PKCdelta in the cell. The oxoanions, however, generated the active form of mitogen-activated protein kinase. Another protein-tyrosine phosphatase inhibitor, phenylarsine oxide, which bridges the thiol residues of the enzyme, induced tyrosine phosphorylation of PKCdelta, and the reaction was enhanced by vanadate. These results suggest that inhibition of protein-tyrosine phosphatase is insufficient for induction of tyrosine phosphorylation of PKCdelta in the cells, and that presumably activation of protein-tyrosine kinase may be essential for tyrosine phosphorylation of the PKC isoform.