Nerve growth factor-induced down-regulation of calmodulin-dependent protein kinase III in PC12 cells involves cyclic AMP-dependent protein kinase

J Neurochem. 1990 Mar;54(3):1034-9. doi: 10.1111/j.1471-4159.1990.tb02354.x.


Treatment of PC12 cells with nerve growth factor (NGF), epidermal growth factor (EGF), or agents that raise intracellular cyclic AMP (cAMP) levels (e.g., forskolin) reduces the activity of calmodulin-dependent protein kinase III (CaM-PK III) over a period of 8 h. The mechanism of this effect of NGF has now been examined in more detail, making use of a mutant PC12 cell line (A126-1B2) that is deficient in cAMP-dependent protein kinase activity. Control experiments showed that A126-1B2 cells retain other NGF-mediated responses (e.g., the induction of ornithine decarboxylase, a cAMP-independent event) and contain a complement of CaM-PK III and its substrate, elongation factor-2, comparable to that of wild-type cells. The ability of NGF or forskolin, but not of EGF, to down-regulate CaM-PK III was markedly attenuated in A126-1B2 compared to wild-type cells. Treatment of wild-type cells with the cAMP phosphodiesterase inhibitor, isobutylmethylxanthine, enhanced the effects of NGF, but not of EGF. The possibility that NGF led to a stimulation of cAMP-dependent protein kinase activity in wild-type cells was assessed by measurement of the "activation ratio" (-cAMP/+cAMP) of this enzyme before and at various times after NGF addition. A small, but significant, increase in the activation ratio from 0.3 to 0.48 was observed, reaching a peak 5 min after NGF treatment. EGF had no effect on the activation ratio in wild-type cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Calcium-Calmodulin-Dependent Protein Kinases*
  • Down-Regulation / drug effects
  • Elongation Factor 2 Kinase
  • Enzyme Activation
  • Nerve Growth Factors / pharmacology*
  • Pheochromocytoma / metabolism*
  • Pheochromocytoma / pathology
  • Protein Kinases / deficiency
  • Protein Kinases / metabolism*
  • Protein Kinases / physiology*
  • Tumor Cells, Cultured


  • Nerve Growth Factors
  • Protein Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Elongation Factor 2 Kinase
  • 1-Methyl-3-isobutylxanthine