NMDA antagonists exacerbate neuronal death caused by proteasome inhibition in cultured cortical and striatal neurons.
The proteasome is involved in multiple cellular processes including control of the cell cycle, apoptosis and intracellular signalling; loss of proteasome function has been postulated to participate in the pathogenesis of triplet repeat diseases. We examined the vulnerability of central neurons to proteasome inhibition and tested the ability of anti-excitotoxic and anti-apoptotic treatments to attenuate proteasome inhibition-induced neuronal death. Exposure of murine neocortical cultures to proteasome inhibitors (0.1-10 microm clasto-lactacystin beta-lactone or MG-132) for 48 h resulted in widespread neuronal death associated with a reduction in intracellular free calcium; higher inhibitor concentrations killed astrocytes. Cultured striatal neurons were more vulnerable than cortical neurons. Within each population, the NADPH diaphorase-positive neuronal subpopulation was more vulnerable than the general neuronal population. Enhancing calcium entry with S(-)BayK8644 or kainate, or blocking apoptosis with cycloheximide, actinomycin D or Z-VAD.FMK attenuated neuronal death, whereas, reducing calcium entry with NMDA antagonists or R(+)BayK8644 potentiated neuronal death. These findings suggest that proteasome inhibition can induce selective neuronal apoptosis associated with intracellular calcium starvation, and point to manipulation of intracellular calcium as a specific therapeutic strategy. In particular, concern is raised that glutamate receptor antagonists might exacerbate, rather than attenuate, proteasome inhibition-induced neuronal death.
Snider
B Joy
BJ
Center for the Study of Nervous System Injury and Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA. sniderj@neuro.wustl.edu
Tee
Lee Y
LY
Canzoniero
Lorella M T
LM
Babcock
Debra J
DJ
Choi
Dennis W
DW
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D061945:Caspase Inhibitors; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000633:toxicity; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005260:Female; D051379:Mice; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019636:Neurodegenerative Diseases / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D046988:Proteasome Endopeptidase Complex; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013687:Telencephalon / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D019680:Trinucleotide Repeat Expansion / Q000235:genetics
D002120:Calcium Channel Agonists; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D009097:Multienzyme Complexes; D016194:Receptors, N-Methyl-D-Aspartate; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D002118:Calcium