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GAPDH knockdown rescues mesencephalic dopaminergic neurons from MPP+ -induced apoptosis
Y Fukuhara1, T Takeshima, Y Kashiwaya
1Division of Neurology, Institute of Neurological Sciences, Tottori University Faculty of Medicine, 36-1 Nishimachi, Yonago 683-8504, Japan.
Abstract:
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) has a number of diverse functions apart from glycolytic function. We explored the possible involvement of GAPDH in 1-methyl-4-phenylpyridinium (MPP+)-induced death of mesencephalic dopaminergic neurons (MDNs) in culture. MPP+ (10 and 20 microM, 24 h) exposure selectively decreased the survival of tyrosine hydroxylase positive (TH+) MDNs, which manifested apoptotic features including shrinkage of the cell body, chromatin condensation and nuclear fragmentation. Two types of GAPDH antisense oligonucleotides almost completely rescued MDNs from MPP+ toxicity. GAPDH was strongly expressed in apoptotic TH+ neurons, and MPP+ exposure significantly increased the percentage of TH+ neurons in which GAPDH is over-expressed. Confocal microscopic analysis demonstrated the nuclear accumulation of GAPDH in neurons undergoing MPP+-induced apoptosis. These results suggest that MPP+ causes apoptosis of MDNs, concomitant with the over-expression and nuclear accumulation of GAPDH.
Insights
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is involved in the death of mesencephalic dopaminergic neurons induced by MPP+. Inhibiting GAPDH protected these neurons, suggesting its role in neurodegeneration.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has functions beyond glycolysis.
- 1-methyl-4-phenylpyridinium (MPP+) is a neurotoxin that induces cell death.
Purpose of the Study:
- To investigate the role of GAPDH in MPP+-induced death of mesencephalic dopaminergic neurons (MDNs).
Main Methods:
- Primary culture of MDNs exposed to MPP+.
- Assessment of MDN survival and apoptosis.
- Treatment with GAPDH antisense oligonucleotides.
- Analysis of GAPDH expression and localization via confocal microscopy.
Main Results:
- MPP+ selectively reduced the survival of tyrosine hydroxylase-positive (TH+) MDNs, inducing apoptosis.
- GAPDH antisense oligonucleotides significantly protected MDNs from MPP+ toxicity.
- MPP+ exposure increased GAPDH expression and its nuclear accumulation in TH+ neurons undergoing apoptosis.
Conclusions:
- MPP+ induces apoptosis in MDNs.
- GAPDH is over-expressed and accumulates in the nucleus during MPP+-induced MDN apoptosis.
- GAPDH plays a significant role in the neurotoxic effects of MPP+ on MDNs.