The Role And Underlying Mechanisms Of Serum Responsefactor In The Pathogenesis Of Parkinson’s Disease

ObjectiveTo investigate the level of serum response factor in Rotenone-induced Parkinson model and PD patients, and to explore the potential role and underlyingmechanisms of SRFin α-synuclein clearance and Parkinson’s disease pathogenesis.Methods:Both in vivoand in vitro PD models wereinduced by the neurotoxins rotenone. continuous subcutaneous rotenone injection was employed to construct Lewis rat model of Parkinson’s disease. The co-localization of TH and SRF in SN of Lewis rat model was detected by immunofluorescence staining and DAB staining Western blot was used to evaluate the protein expressions of TH and SRF. Rotenone treated PD model in vitro was established in PC12 cells, and western blot was applied to examine the level of SRF, as well as autophagic markers LC3-II and p62 in different time point.The small interfering RNA(si RNA)targetingrat SRF and p CGN-SRF plasmidwas applied to knockdown and overexpression SRFin PC12 cells. Proteins associated to the formation of autophagy such as Beclin 1 and LC3-II were examined by western blot. CCK-8 was used to detect cell viabilityafter exposure to 100 n M rotenone,24 h, and the expression of SRF, α-synuclein,LC3-II and P62 were also measured.SRF overexpression model was established by transfecting plasmid into both of wild-type and Atg5 knock down MEF cells, and further rotenone treatment was followed by measuring the cell viability.The level of SRF in the peripheral blood of Parkinson’s disease patients and health donors were measured by ELISA.Result:In rotenone-intoxicated Lewis rat SN and PC12 cells, SRF was decreased, at the same time TH declined in Lewis rat SN, and autophagic markers LC3-II and p62 upregulated in PC12 cells. Knock-down model ofSRF show a increased sensitive to neurotoxin rotenone, compared with the ns RNA-transfected cells, accompanied by the decrease of Beclin 1 and LC3-II. Conversely,the SRF overexpression cell show a less susceptibility to rotenonecompared with vector control transfected cells group, and leads to the elevated of Beclin 1 and LC3-II. In Atg-5 stably knockout MEF cell line, cell viability was measured after being transfected with plasmid transient overexpressing SRF, which is followed by treated with rotenone. The protective effect of SRF in rotenone-induced PD model in vitro is eliminated, when the autophagy is defected.To validate the hypothesis that SRF participating in the clearness ofα-synuclein mediated by autophagy in rotenone model and exerts a protective role, we continued to apply a rotenone-induced cellular model of PD in PC12 cells, which use transient transfection to knockdown or overexpress SRF. In the absence of SRF, the promotion ofα-synucleinas well as p62 level induced by rotenone was aggravated. While the increased lever of LC3-II induced by rotenone is downward by SRF knockdown. Contrarily, overexpression of SRF reverse rotenone induced accumulation of α-synuclein and P62.Simultaneously the elevation of LC3-II levelexacerbated, supporting our suppose that SRF might participate in the formation of autophagosome and contributions to the degradation of α-synuclein.A decreased level of SRF in the serum of Parkinson’s patients was detected by ELISA, compared with normal group, which consistent with the result in rotenone-treated PD model in vivo and in vitro. Conclusion:Models of Parkinson’s disease induced by environmental toxins rotenone in vivo and vitro, as well as PD patient, show a decreased level of SRF. SRF enhance the degradation of α-synuclein through the Autophagosome-Lysosome Pathway and execute protective effect in PD model...