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Primary Culture of Mouse Dopaminergic Neurons
Published on: September 8, 2014
Parkin attenuates manganese-induced dopaminergic cell death
Youichirou Higashi1, Masato Asanuma, Ikuko Miyazaki
1Department of Brain Science, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
Abstract:
Manganese as environmental factor is considered to cause parkinsonism and induce endoplasmic reticulum stress-mediated dopaminergic cell death. We examined the effects of manganese on parkin, identified as the gene responsible for familial Parkinson's disease, and the role of parkin in manganese-induced neuronal cell death. Manganese dose-dependently induced cell death of dopaminergic SH-SY5Y and CATH.a cells and cholinergic Neuro-2a cells, and that the former two cell types were more sensitive to manganese toxicity than Neuro-2a cells. Moreover, manganese increased the expression of endoplasmic reticulum stress-associated genes, including parkin, in SH-SY5Y cells and CATH.a cells, but not in Neuro-2a cells. Treatment with manganese resulted in accumulation of parkin protein in SH-SY5Y cells and its redistribution to the perinuclear region, especially aggregated Golgi complex, while in Neuro-2a cells neither expression nor redistribution of parkin was noted. Manganese showed no changes in proteasome activities in either cell. Transient transfection of parkin gene inhibited manganese- or manganese plus dopamine-induced cell death of SH-SY5Y cells, but not of Neuro-2a cells. Our results suggest that the attenuating effects of parkin against manganese- or manganese plus dopamine-induced cell death are dopaminergic cell-specific compensatory reactions associated with its accumulation and redistribution to perinuclear regions but not with proteasome system.
Insights
Manganese exposure causes parkinsonism by inducing endoplasmic reticulum stress and dopaminergic cell death. Parkin, a Parkinson
Area of Science:
- Neuroscience
- Environmental Toxicology
- Molecular Biology
Background:
- Manganese is an environmental factor linked to parkinsonism.
- Endoplasmic reticulum stress is a key mechanism in manganese-induced neurotoxicity.
- Parkin gene mutations are responsible for familial Parkinson's disease.
Purpose of the Study:
- To investigate the effects of manganese on parkin expression and function.
- To elucidate the role of parkin in manganese-induced neuronal cell death.
- To determine the cell-specific mechanisms of manganese neurotoxicity.
Main Methods:
- Dose-dependent cell death assays using dopaminergic (SH-SY5Y, CATH.a) and cholinergic (Neuro-2a) cell lines.
- Analysis of endoplasmic reticulum stress-associated gene expression, including parkin.
- Western blot analysis to assess parkin protein accumulation and redistribution.
- Proteasome activity assays.
- Transient transfection with parkin gene to evaluate its protective effects.
Main Results:
- Manganese induced dose-dependent cell death in dopaminergic cells, with higher sensitivity compared to cholinergic cells.
- Manganese increased parkin expression and protein accumulation, with redistribution to perinuclear regions in dopaminergic cells.
- Parkin gene transfection conferred protection against manganese-induced cell death specifically in dopaminergic cells.
- Manganese did not affect proteasome activity in either cell type.
Conclusions:
- Parkin plays a cell-specific, compensatory role in attenuating manganese-induced dopaminergic neurotoxicity.
- Parkin's protective effects involve its accumulation and redistribution, not alterations in proteasome activity.
- These findings highlight the intricate relationship between environmental toxins, genetic factors, and neurodegenerative disease mechanisms.
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