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Activation of a calcium-calmodulin-dependent protein kinase I cascade in PC12 cells.

Abstract
It has been observed that the activity of Ca2+-calmodulin (CaM)-dependent protein kinase I is enhanced up to 50-fold by its phosphorylation in vitro by a distinct CaM kinase I kinase (Lee, J. C., and Edelman, A. M. (1994) J. Biol. Chem. 269, 2158-2164). It has, however, been unclear whether this event represents an acute form of cellular regulation. We demonstrate here the phosphorylation and activation of CaM kinase I in PC12 pheochromocytoma cells in response to elevation of intracellular Ca2+. Treatment of PC12 cells with the Ca2+-ionophore, ionomycin, or with a depolarizing concentration of KCl, led to rapid, biphasic phosphorylation of CaM kinase I and to increases in CaM kinase I activity of 5.1- and 7. 3-fold, respectively. Depolarization-induced activation of CaM kinase I was reduced by approximately 80% by blockade of Ca2+ influx through L-type voltage-dependent Ca2+ channels and completely abolished by removal of extracellular Ca2+. The ability of PC12 cell CaM kinase I to be phosphorylated and activated by purified CaM kinase I kinase in vitro was markedly reduced by prior depolarization of the cells, consistent with intracellular phosphorylation and activation of CaM kinase I by CaM kinase I kinase. These results demonstrate the existence in PC12 cells of a CaM kinase I cascade, the function of which may be to sensitize cells to signal-induced elevations of intracellular Ca2+.
AuthorsJ M Aletta, M A Selbert, A C Nairn, A M Edelman
JournalThe Journal of biological chemistry (J Biol Chem) Vol. 271 Issue 34 Pg. 20930-4 (Aug 23 1996) ISSN: 0021-9258 [Print] United States
PMID8702851 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Calcium Channels
  • Calcium-Calmodulin-Dependent Protein Kinase Type 1
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Camk1 protein, rat
  • Pnck protein, rat
  • Calcium
Topics
  • Animals
  • Calcium (physiology)
  • Calcium Channels (physiology)
  • Calcium-Calmodulin-Dependent Protein Kinase Type 1
  • Calcium-Calmodulin-Dependent Protein Kinases (metabolism)
  • Cytoplasm (physiology)
  • Enzyme Activation
  • Membrane Potentials
  • PC12 Cells
  • Phosphorylation
  • Rats

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