Inhibition of PKB/Akt1 by C2-ceramide involves activation of ceramide-activated protein phosphatase in PC12 cells

Mol Cell Neurosci. 2000 Feb;15(2):156-69. doi: 10.1006/mcne.1999.0813.

Abstract

Accumulation of ceramide has been reported in stress- and receptor-induced apoptosis in the nervous system. However, its role in apoptosis signaling remains elusive. We describe here the inhibition of the NGF-activated phosphoinositide 3-kinase (PI3K)-PKB/Akt1 survival pathway by the cell permeable analog C2-ceramide. C2-ceramide did not inhibit ERK, PI3K, or PDK1 activities and did not alter the translocation of PDK1 and Akt1 to the plasma membrane, but blocked nuclear translocation of Akt1. Down-regulation of the Akt pathway was due to enhanced dephosphorylation of Akt1 at residues T308 and S473. Moreover, Akt1 was dephosphorylated in vitro by a cation-independent phosphatase involving ceramide-activated protein phosphatase (CAPP). Membrane-anchored Akt1 was more resistant to dephosphorylation/inactivation by C2-ceramide than wild-type Akt1. Consistently, N-myristylated-Akt1 conferred resistance to the apoptosis induced by C2-ceramide in PC12 cells. These results provide a novel mechanism for induction of apoptosis by ceramide in nerve-derived cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androstadienes / pharmacology
  • Animals
  • Cell Nucleus / drug effects
  • Cell Nucleus / physiology
  • Enzyme Activation / drug effects
  • Kinetics
  • Mice
  • Nerve Growth Factor / pharmacology
  • PC12 Cells
  • Phosphoprotein Phosphatases / metabolism*
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins*
  • Rats
  • Recombinant Fusion Proteins / antagonists & inhibitors
  • Recombinant Fusion Proteins / metabolism
  • Sphingosine / analogs & derivatives*
  • Sphingosine / pharmacology
  • Transfection
  • Wortmannin

Substances

  • Androstadienes
  • N-acetylsphingosine
  • Proto-Oncogene Proteins
  • Recombinant Fusion Proteins
  • Nerve Growth Factor
  • Akt1 protein, rat
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Phosphoprotein Phosphatases
  • Sphingosine
  • Wortmannin