Selective vulnerability of neurons to acute toxicity after proteasome inhibitor treatment: implications for oxidative stress and insolubility of newly synthesized proteins.
Maintaining protein homeostasis is vital to cell viability, with numerous studies demonstrating a role for proteasome inhibition occurring during the aging of a variety of tissues and, presumably, contributing to the disruption of cellular homeostasis during aging. In this study we sought to elucidate the differences between neurons and astrocytes in regard to basal levels of protein synthesis, proteasome-mediated protein degradation, and sensitivity to cytotoxicity after proteasome inhibitor treatment. In these studies we demonstrate that neurons have an increased vulnerability, compared to astrocyte cultures, to proteasome-inhibitor-induced cytotoxicity. No significant difference was observed between these two cell types in regard to the basal rates of protein synthesis, or basal rates of protein degradation, in the pool of short-lived proteins. After proteasome inhibitor treatment neuronal crude lysates were observed to undergo greater increases in the levels of ubiquitinated and oxidized proteins and selectively exhibited increased levels of newly synthesized proteins accumulating within the insoluble protein pool, compared to astrocytes. Together, these data suggest a role for increased oxidized proteins and sequestration of newly synthesized proteins in the insoluble protein pool, as potential mediators of the selective neurotoxicity after proteasome inhibitor treatment. The implications for neurons exhibiting increased sensitivity to acute proteasome inhibitor exposure, and the corresponding changes in protein homeostasis observed after proteasome inhibition, are discussed in the context of both aging and age-related disorders of the nervous system.
Dasuri
Kalavathi
K
Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808-4124, USA.
Ebenezer
Philip J
PJ
Zhang
Le
L
Fernandez-Kim
Sun Ok
SO
Uranga
Romina M
RM
Gavilán
Elena
E
Di Blasio
Alessia
A
Keller
Jeffrey N
JN
D000375:Aging / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002457:Cell Extracts; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007976:Leupeptins / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020258:Neurotoxicity Syndromes / Q000209:etiology / Q000517:prevention & control; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress; D061988:Proteasome Inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility / Q000187:drug effects; D054875:Ubiquitination / Q000187:drug effects
D002457:Cell Extracts; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D061988:Proteasome Inhibitors; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde