Activation of casein kinase II in response to insulin and to epidermal growth factor.
- 1 December 1987
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 84 (24), 8834-8838
- https://doi.org/10.1073/pnas.84.24.8834
Abstract
Insulin treatment enhances casein kinase II (CKII) activity in 3T3-L1 mouse adipocytes and H4-IIE rat hepatoma cells, the magnitude of the activation varying from 30% to 150%. Activation of CKII was apparent after 5 min of exposure of 3T3-L1 cells to insulin, was maximal by 10 min, and persisted through 90 min. The insulin-stimulated activity was inhibited by low concentrations of heparin and was stimulated by spermine. Activation of CKII was effected by physiological concentrations of insulin (EC50 = 0.15 nM), suggesting that the effect is a true insulin response and not one mediated through insulin-like growth factor receptors. Epidermal growth factor (100 ng/ml for 10 min) also activated CKII in A431 human carcinoma cells, which is consistent with other observations that insulin and epidermal growth factor may have some common effects. Insulin stimulation of CKII activity was due to an increase in the maximal velocity of the kinase; the apparent Km for peptide substrate was not altered. Enhanced activity did not appear to result from increased synthesis of CKII protein, because cycloheximide did not block the effect and because an immunoblot developed with antiserum to CKII showed no effect of insulin on the cytosolic concentration of CKII. Because insulin-stimulated CKII activity was maintained after chromatography of cell extracts on Sephadex G-25, it is unlikely that the effect is mediated by a low-molecular-weight activator of the kinase. Rather, the results are consistent with the possibility that insulin activates CKII by promoting a covalent modification of the kinase.Keywords
This publication has 31 references indexed in Scilit:
- Amino acid sequence of the beta subunit of bovine lung casein kinase II.Proceedings of the National Academy of Sciences, 1987
- Insulin and growth factor effects on c-fos expression in normal and protein kinase C-deficient 3T3-L1 fibroblasts and adipocytes.Proceedings of the National Academy of Sciences, 1986
- Insulin stimulates the generation from hepatic plasma membranes of modulators derived from an inositol glycolipid.Proceedings of the National Academy of Sciences, 1986
- Activation of S6 kinase activity in 3T3-L1 cells by insulin and phorbol ester.Proceedings of the National Academy of Sciences, 1985
- Epidermal growth factor stimulates glycogen synthase activity in cultured cells.Proceedings of the National Academy of Sciences, 1985
- Phosphorylation of DNA topoisomerase II by casein kinase II: modulation of eukaryotic topoisomerase II activity in vitro.Proceedings of the National Academy of Sciences, 1985
- A synthetic peptide substrate specific for casein kinase II.Proceedings of the National Academy of Sciences, 1985
- Multisite phosphorylation of glycogen synthase from rabbit skeletal muscleFEBS Letters, 1982
- Phosphorylation of the Type‐II Regulatory Subunit of Cyclic‐AMP‐Dependent Protein Kinase by Glycogen Synthase Kinase 3 and Glycogen Synthase Kinase 5European Journal of Biochemistry, 1982
- In vitro phosphorylation and inactivation of rat liver acetyl-CoA carboxylase purified by avidin affinity chromatographyBiochimica et Biophysica Acta (BBA) - General Subjects, 1982