title: Prolonged nuclear retention of activated extracellular signal-regulated protein kinase promotes cell death generated by oxidative toxicity or proteasome inhibition in a neuronal cell line.
abstract: In the HT22 mouse hippocampal cell line and primary immature embryonic rat cortical neurons, glutamate-induced oxidative toxicity is associated with a delayed but chronic activation of extracellular signal-regulated kinase-1/2 (ERK-1/2). ERK-1/2 is also activated in HT22 cells that undergo caspase-dependent cell death upon inhibition of proteasome-dependent protein degradation brought about by MG132 treatment. As in glutamate-treated HT22 cells and primary neurons, inhibition of MEK-1, an upstream activator of ERK-1/2 protects against MG132-induced toxicity. Furthermore, activated ERK-1/2 is retained within the nucleus in glutamate- and MG132-treated HT22 cells. Although previous studies suggested that ERK-1/2 activation was downstream of many cell death-inducing signals in HT22 cells, we show here that cycloheximide, the Z-vad caspase inhibitor, and a nonlethal heat shock protect against glutamate- and MG132-induced toxicity without diminishing ERK-1/2 activation. In these cases, ERK-1/2, although chronically activated, is not retained within the nucleus but accumulates within the cytoplasm. Thus, persistent nuclear retention of activated ERK-1/2 may be a critical factor in eliciting proapoptotic effects in neuronal cells subjected to oxidative stress or proteasome inhibition.
authors.affiliation: Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Madalina
authors.initials: M
authors.lastname: Stanciu
authors.forename: Donald B
authors.initials: DB
authors.lastname: DeFranco
mesh_terms: D000818:Animals; D016923:Cell Death; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D003513:Cycloheximide / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000187:drug effects*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D018869:Heat-Shock Response; D006624:Hippocampus / Q000166:cytology* / Q000201:enzymology; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000187:drug effects*; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D018384:Oxidative Stress; D046988:Proteasome Endopeptidase Complex; D051381:Rats
chemical_list: D015853:Cysteine Proteinase Inhibitors; D009097:Multienzyme Complexes; D018698:Glutamic Acid; D003513:Cycloheximide; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex