| 1. |
- Lotharius, J, et al.
(författare)
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Progressive degeneration of human mesencephalic neuron-derived cells triggered by dopamine-dependent oxidative stress is dependent on the mixed-lineage kinase pathway
- 2005
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 25:27, s. 6329-6342
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- O'Malley, KL, et al.
(författare)
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Targeted expression of BCL-2 attenuates MPP+ but not 6-OHDA induced cell death in dopaminergic neurons
- 2003
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Ingår i: Neurobiology of Disease. - 0969-9961. ; 14:1, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- Neurodegenerative diseases such as Parkinson's disease exhibit complex features of cell death reflecting both the primary lesion as well as surrounding interconnected events. Because Bcl-2 family members are intimately involved in cell death processes, the present Study used dopaminergic cultures from control, Bcl-2-overexpressing, or Bax-deficient genetically modified animals to determine the in situ effects of parkinsonism-inducing toxins. MPP+-mediated cell death was attenuated by Bcl-2 but did not require Bax. Accordingly, mutations or deletions within Bax heterodimerization domains, BH1, BH2, or BH3 had no effect on Bcl-2's ability to prevent cell death. whereas the cell-death suppressing BH4 domain did. Although both staurosporine and 6-OHDA induced apoptosis, overexpression of Bcl-2 only rescued cells from programmed cell death induced by staurosporine. Thus, differential cell death pathways are associated with these cytotoxic signals in primary models of Parkinson's disease. (C) 2003 Elsevier Science (USA). All rights reserved.
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