Effect of serum and hydrogen peroxide on the Ca2+/calmodulin-dependent phosphorylation of eukaryotic elongation factor 2(eEF-2) in Chinese hamster ovary cells.
- Author:
Kee Ryeon KANG
1
;
So Young LEE
Author Information
1. Department of Biochemistry and Gyeongsang Institute of Health Science, Gyeongsang National University College of Medicine, Chinju, Korea. krkang@gaechuk.gsnu.ac.kr
- Publication Type:Original Article ; Comparative Study
- Keywords:
Ca2+;
CaM;
eEF-2;
eEF-2 kinase
- MeSH:
Animal;
CHO Cells;
Ca(2+)-Calmodulin Dependent Protein Kinase/*metabolism;
Cell Division;
Cells, Cultured;
Comparative Study;
Cytosol/enzymology;
Egtazic Acid/pharmacology;
Hamsters;
Human;
Hydrogen Peroxide/*pharmacology;
Mice;
Okadaic Acid/pharmacology;
Oxidants/*pharmacology;
Peptide Elongation Factors/metabolism;
Phosphoprotein Phosphatase/metabolism;
Phosphorylation;
Polyethylene Glycols/pharmacology;
Trifluoperazine/pharmacology
- From:Experimental & Molecular Medicine
2001;33(4):198-204
- CountryRepublic of Korea
- Language:English
-
Abstract:
Eukaryotic elongation factor eEF-2 mediates regulatory steps important for the overall regulation of mRNA translation in mammalian cells and is activated by variety of cellular conditions and factors. In this study, eEF-2 specific, Ca2+/CaM-dependent protein kinase III (CaM PK III), also called eEF-2 kinase, was examined under oxidative stress and cell proliferation state using CHO cells. The eEF-2 kinase activity was determined in the kinase buffer containing Ca2+ and CaM in the presence of eEF-2 and [gamma-32P] ATP. The eEF-2 kinase activity in cell lysates was completely dependent upon Ca2+ and CaM. Phosphorylation of eEF-2 was clearly identified in proliferating cells, but not detectable in CHO cells arrested in their growth by serum deprivation. The content of the eEF-2 protein, however, was equivalent in both cells. Using a phosphorylation state-specific antibody, we show that oxidant such as H2O2, which triggers a large influx of Ca2+, dramatically enhances the phosphorylation of eEF-2. In addition, H2O2-induced eEF-2 phosphorylation is dependent on Ca2+ and CaM, but independent of protein kinase C. In addition, okadaic acid inhibits phosphoprotein phosphatase 2A(PP2A)-mediated eEF-2 dephosphorylation. These results may provide a possible link between the elevation of intracellular Ca2+ and cell division and suggest that phosphorylation of eEF-2 is sensitive cellular reflex on stimuli that induces intracellular Ca2+ flux.
