ABSTRACT
Objective:To identify the effect of ?-synuclein overexpression on mitochondrial membrane structure with atomic force microscopy. Methods:?-syn expression was mediated by AAV (adeno-associated viral vector) and Recombinant AAV/?-syn and AAV/LacZ viral particles were stereotaxically injected in the left side of rat substantia nigra (SN) for rat model of ?-synuclein overexpression. Mitochondria were isolated from rats SN of Brain. Mitochondria were analysis with JC-1 staining,atomic force microscopy and Western blot. Results:By 16 weeks post-infection of AAV-?-syn,the level of ?-syn increased about 2 times in mitochondrial fraction with Western blot and mitochondrial membrane potential (??) decreased with JC-1 staining. Furthermore,mitochondria swelling and porous like structure formed on the mitochondrial membrane with atomic force microscopy. Conclusion:The data suggested that ?-syn could accumulate in mitochondria,might form mitochondrial membrane pores and lead to ?? decreases. ?-syn might lead to mitochondrial dysfunction in Parkinson's disease.
ABSTRACT
Mitochondrial dysfunction has been implicated in the aetiology of sporadic Parkinson's disease but its role in the disease mechanism remains unclear.To investigate the effect of synuclein on mitochondrial dysfunction induced by rotenone.The human dopaminergic SH-SY5Y cells were used as a cell model.The cells over-expressed the wild-type ?-synuclein were treated with complex I inhibitor rotenone.The cell viability,complex I activity,Mitochondrial swelling and O2-content were tested at different time point-1w,2w,4w after rotenone treated.CCK-8 test results showed that the cell viability of overexpressed ?-synuclein(SH-SY5Y-Syn)was much lower than the control group(SH-SY5Y-Ctr).After administrating with rotenone about 1w or 2w the cell viability of SH-SY5Y-Syn became higher than that of SH-SY5Y-Ctr.On the 4th week the results were contrary to the first 2 weeks.Similar results were got when test the mitochondrial function.In the first 2 weeks after roteoone administrating,the mitochondrial function of SH-SY5Y-Syn was better than that of SH-SY5Y-Ctr.This suggest that the ?-synuclein could protect the mitochondrial against the injury induced by rotenone in the early stage-1w,2w,while this effect disappeared in the final stage-4w.
ABSTRACT
Both genetic and environmental factors are involved in the pathogenesis of Parkinsonos disease (PD). Epidemiological studies showed that environmental factors shared with the common mechanisms of resulting in alpha-synuclein aggregation by inhibiting complex I of mitochondria and leading to oxidative stress. To investigate the relationship between alpha-synuclein and oxidative stress, we used human dopaminergic SH-SY5Y cells transfected with alpha-synuclein-enhanced green fluorescent protein (EGFP). alpha-synuclein gene expression was determined by immunocytochemistry and real-time quantitative PCR. Both SH-SY5Y and alpha-synuclein overexpressed SH-SY5Y (SH-SY5Y/Syn) cells were treated with various concentrations of rotenone for different time. Cell viability and oxidative stress were detected by MTT assay and DCF assay. Superoxide dismutase (SOD) activity was assessed with xanthine peroxidase method. Cell apoptosis was detected with flow cytometry. Results showed that alpha-synuclein gene was constantly overexpressed in SH-SY5Y/Syn cells. After treatment with rotenone, both cell viability and complex I activity in these cells were reduced in a concentration-dependent manner. Oxidative stress was also found in these cells. Compared with SH-SY5Y cells, SOD activity in SH-SY5Y/Syn cells was increased distinctly (P<0.05) and alpha-synuclein significantly attenuated rotenone-induced cell apoptosis. These results suggest that the alpha-synuclein overexpression in SH-SY5Y cells has a tendency to partially resist oxidative stress induced by rotenone and this response may assist cell survival.
Subject(s)
Humans , Apoptosis , Cell Line , Cell Survival , Cytoprotection , Dose-Response Relationship, Drug , Electron Transport Complex I , Metabolism , Oxidative Stress , Rotenone , Toxicity , Superoxide Dismutase , Metabolism , Superoxides , Metabolism , alpha-Synuclein , Genetics , PhysiologyABSTRACT
The direct effects of glutamate and dizocilpine maleate (MK-801, non-competitive N-Methyl-D-aspartate glutamate receptor antagonist) on the metabolism of dopamine were investigated in the striatum of normal and parkinsonian rats. L-dopa, L-glutamic acid and MK-801 were administered in the striatum locally by microdialysis. 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were simultaneously sampled by microdialysis. The concentrations of DOPAC and HVA were assayed by high performance liquid chromatography with electrochemical detection (HPLC-ECD). L-dopa increased the concentrations of DOPAC and HVA in the striatum of normal and parkinsonian rats. L-glutamic acid decreased the concentrations of DOPAC and HVA in striatum of normal rats but not parkinsonian rats. MK-801 increased the concentrations of DOPAC and HVA in the striatum of normal rats but not parkinsonian rats. MK-801 prevented the L-glutamic acid-induced decrease of DOPAC and HVA in the striatum of normal rats. Our results indicate that glutamate modulates the metabolism of dopamine (DA) through NMDA receptors and that the improvement of PD by MK-801 is not through improving the metabolism of DA.
Subject(s)
Animals , Female , Rats , Corpus Striatum , Metabolism , Dizocilpine Maleate , Pharmacology , Dopamine , Metabolism , Glutamic Acid , Physiology , Microdialysis , Parkinson Disease , Metabolism , Rats, Sprague-Dawley , Receptors, N-Methyl-D-Aspartate , PhysiologyABSTRACT
The characteristic pathological changes of Parkinson s disease (PD) include a severe loss of dopamine neurons in the substantia nigra and a severe decrease in dopamine in the striatum. Since the expression of tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC) in the biosynthetic pathway for dopamine are low, a promising approach to the gene therapy of PD is to augment the gene expression of the enzymes in the biosynthetic pathway for dopamine. In the present study, human TH and AADC genes were reconstructed into retrovirous vectors pLHCX and pLNCX(2) respectively. Then pLHCX/TH and pLNCX(2)/AADC were transfected into packaging cell line PA317 with liposome. PA317/TH and PA317/AADC were selected by different antibiotics. Gene expression was examined by methods of immunohistochemistry and in situ hybridization. The catalytic activity of two cloned gene enzymes was assessed in vitro by HPLC-EC. Immunocytochemical staining showed that TH and AADC were expressed efficiently in vitro. Both TH and AADC mRNA were transcripted in PA317 cell lines by using in situ hybridazation. HPLC-EC experiments revealed that the transfected cells produced a significantly higher level of dopamine and L-dopa than the untransfected cells. The two genetically modified cells could improve the production of L-dopa and dopamine in response to suitable substrate. The present results suggest that not only recombinant TH and AADC genes are successfully expressed in vitro, but also the enzymes have respective functional activities. These results have set up a way for in vivo gene therapy of PD with TH and AADC genes.