Proteolysis of oxidized proteins after oxygen-glucose deprivation in rat cortical neurons is mediated by the proteasome.
Oxidative injury contributes to cellular damage during and after cerebral ischemia. However, the downstream catabolic pathways of damaged cellular components in neurons are largely unknown. In the current study, the authors examined the formation of oxidized proteins and their active degradation by the proteasome. In near-pure rat primary cortical neurons, it was found that protein-bound carbonyls as markers for oxidized proteins are increased after oxygen-glucose deprivation (OGD). During and after OGD, degradation of proteins metabolically radiolabeled before OGD increases two-to threefold compared with the normal protein turnover. Proteolysis after reoxygenation was attenuated by the presence of dimethylthiourea, a radical scavenger, and was blocked by lactacystin, a specific proteasome inhibitor. Lactacystin also increased the amount of protein carbonyls formed. In contrast, the activity of the proteasome complex itself after OGD was not different from sham-washed controls. The authors suggest that oxygen-glucose deprivation increases free radicals, which, in turn, oxidize proteins that are recognized and actively degraded by the proteasome complex. This protease itself is relatively resistant against oxidative injury. The authors conclude that the proteasome may be an active part of the cellular defense system against oxidative stress after cerebral ischemia.
Weih
M
M
Department of Neurology, Charité Hospital, Humboldt University, Berlin, Germany.
Schmitt
M
M
Gieche
J
J
Harms
C
C
Ruscher
K
K
Dirnagl
U
U
Grune
T
T
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000201:enzymology*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism
D015853:Cysteine Proteinase Inhibitors; D009097:Multienzyme Complexes; D009419:Nerve Tissue Proteins; D017382:Reactive Oxygen Species; C067713:lactacystin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D005947:Glucose; D010100:Oxygen; D000111:Acetylcysteine