Progressive degeneration of human mesencephalic neuron-derived cells triggered by dopamine-dependent oxidative stress is dependent on the mixed-lineage kinase pathway.
Models of Parkinson's disease (PD) based on selective neuronal death have been used to study pathogenic mechanisms underlying nigral cell death and in some instances to develop symptomatic therapies. For validation of putative neuroprotectants, a model is desirable in which the events leading to neurodegeneration replicate those occurring in the disease. We developed a human in vitro model of PD based on the assumption that dysregulated cytoplasmic dopamine levels trigger cell loss in this disorder. Differentiated human mesencephalic neuron-derived cells were exposed to methamphetamine (METH) to promote cytoplasmic dopamine accumulation. In the presence of elevated iron concentrations, as observed in PD, increased cytosolic dopamine led to oxidative stress, c-Jun N-terminal kinase (JNK) pathway activation, neurite degeneration, and eventually apoptosis. We examined the role of the mixed-lineage kinases (MLKs) in this complex degenerative cascade by using the potent inhibitor 3,9-bis[(ethylthio)methyl]-K-252a (CEP1347). Inhibition of MLKs not only prevented FeCl2+/METH-induced JNK activation and apoptosis but also early events such as neurite degeneration and oxidative stress. This broad neuroprotective action of CEP1347 was associated with increased expression of an oxidative stress-response modulator, activating transcription factor 4. As a functional consequence, transcription of the cystine/glutamate and glycine transporters, cellular cystine uptake and intracellular levels of the redox buffer glutathione were augmented. In conclusion, this new human model of parkinsonian neurodegeneration has the potential to yield new insights into neurorestorative therapeutics and suggests that enhancement of cytoprotective mechanisms, in addition to blockade of apoptosis, may be essential for disease modulation.
Department of Disease Biology, H. Lundbeck A/S, 2500 Valby, Denmark. mjl@lundbeck.com
Julie
J
Lotharius
Jeppe
J
Falsig
Johan
J
van Beek
Sarah
S
Payne
Ralf
R
Dringen
Patrik
P
Brundin
Marcel
M
Leist
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D003553:Cystine / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004298:Dopamine / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D005296:Ferrous Compounds / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D015227:Lipid Peroxidation; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008636:Mesencephalon / Q000166:cytology*; D008694:Methamphetamine / Q000494:pharmacology / Q000633:toxicity; D009410:Nerve Degeneration / Q000201:enzymology* / Q000473:pathology; D016501:Neurites / Q000473:pathology; D009474:Neurons / Q000201:enzymology / Q000473:pathology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010300:Parkinson Disease / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000032:analysis; D051381:Rats; D013481:Superoxides / Q000378:metabolism
D002227:Carbazoles; D005296:Ferrous Compounds; D007211:Indoles; D047428:Protein Kinase Inhibitors; D013481:Superoxides; C106592:3,9-bis((ethylthio)methyl)-K-252a; D008694:Methamphetamine; D003553:Cystine; D006861:Hydrogen Peroxide; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D005978:Glutathione; C029451:ferrous chloride; D004298:Dopamine