2-Deoxyglucose and NMDA inhibit protein synthesis in neurons and regulate phosphorylation of elongation factor-2 by distinct mechanisms.
Cerebral ischaemia is associated with brain damage and inhibition of neuronal protein synthesis. A deficit in neuronal metabolism and altered excitatory amino acid release may both contribute to those phenomena. In the present study, we demonstrate that both NMDA and metabolic impairment by 2-deoxyglucose or inhibitors of mitochondrial respiration inhibit protein synthesis in cortical neurons through the phosphorylation of eukaryotic elongation factor (eEF-2), without any change in phosphorylation of initiation factor eIF-2alpha. eEF-2 kinase may be activated both by Ca(2+)-independent AMP kinase or by an increase in cytosolic Ca2+. Although NMDA decreases ATP levels in neurons, only the effects of 2-deoxyglucose on protein synthesis and phosphorylation of elongation factor eEF-2 were reversed by Na(+) pyruvate. Protein synthesis inhibition by 2-deoxyglucose was not as a result of a secondary release of glutamate from cortical neurons as it was not prevented by the NMDA receptor antagonist 5-methyl-10,11-dihydro-5H-dibenzo-(a,d)-cyclohepten-5,10-imine hydrogen maleate (MK 801), nor to an increase in cytosolic-free Ca2+. Conversely, 2-deoxyglucose likely activates eEF-2 kinase through a process involving phosphorylation by AMP kinase. In conclusion, we provide evidence that protein synthesis can be inhibited by NMDA and metabolic deprivation by two distinct mechanisms involving, respectively, Ca(2+)-dependent and Ca(2+)-independent eEF-2 phosphorylation.
Maus
M
M
Collège de France, INSERM, Paris, France.
Torrens
Y
Y
Gauchy
C
C
Bretin
S
S
Nairn
A C
AC
Glowinski
J
J
Premont
J
J
D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology*; D015153:Blotting, Western / Q000379:methods; D002118:Calcium / Q000378:metabolism; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D003847:Deoxyglucose / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D007476:Ionophores / Q000494:pharmacology; D007930:Leucine / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D016202:N-Methylaspartate / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009840:Oligomycins / Q000494:pharmacology; D020652:Peptide Elongation Factor 2 / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019289:Pyruvic Acid / Q000493:pharmacokinetics; D019810:Sodium Azide / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D013997:Time Factors; D014316:Tritium / Q000378:metabolism
D000963:Antimetabolites; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D007476:Ionophores; D009840:Oligomycins; D020652:Peptide Elongation Factor 2; D011500:Protein Synthesis Inhibitors; D014316:Tritium; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D016202:N-Methylaspartate; D019289:Pyruvic Acid; D019810:Sodium Azide; D003847:Deoxyglucose; D011494:Protein Kinases; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D007930:Leucine; D002118:Calcium