Degradation Of α-Synuclein In Parkinson’s Disease Model And Its Mechanism By Compound TM

Objective: The present study was conducted to observe the effect of compound TM on the degradation of α-synuclein(α-syn)and to explore its possible mechanism.Methods: PC12/α-syn-A53 T cell line was cultured in vitro.Established Parkinson’s disease in vitro model by overexpression of α-synuclein which induced by tetracycline.Cells were treated with different concentrations of compound TM or in combination with lysosomal inhibitor(CQ)and proteasome inhibitor(MG132)for 24 h.The protein expression levels of α-synuclein,autophagic marker protein LC3 and immunoglobulin subunit β5i(LMP7)were detected by Western blotting,the activity of chymotrypsin-like protein after TM treatment was detected by fluorimetry.A53 T mutant alpha-synuclein transgenic mice was used as an in vivo model of Parkinson’s disease,TM(10mg/kg)were given by gavage once a day for 4 weeks.After the last administration,the behavioral changes of animals were examined by grasping experiments and roller experiments,the changes of α-synuclein in striatum were detected by Western blotting.Results: PC12 / α-syn-A53 T cell line can stably overexpress the mutated alpha-synuclein(A53T)after induced by tetracycline,Western blotting analysis showed that TM was effective in degrading α-synuclein with a time-dependent and dose-dependent manner;the protein level of α-synuclein in the TM combined with lysosomal inhibitor(CQ)group was lower than that in the CQ group.TM up-regulated the m RNA and protein expression of immunoglobulin subunit β5i(LMP7),increased the activity of chymotrypsin-like protein,but did not affect the autophagic marker protein LC3.After 4 weeks of treating by TM(10mg/kg)with intragastric administration,the level of α-synuclein in the striatum of α-syn-A53 T transfected mice was significantly lower than that in the control group.Conclusion: Compound TM degrades the α-synuclein by proteasome pathway,the mechanism of this action may be through upregulating the expression of LMP7 protein and activating the activity of proteasome.