244. New Gene Therapy for Parkinson's Disease by Down Regulation of α-Synuclein

Abstract

Parkinson's disease (PD) is characterized by selective degeneration of substantia nigra dopamine neurons and abnormal cytoplasmic aggregates of |[alpha]|-synuclein. There is substantial evidence from molecular genetics, transgenic animal studies, and aggregation/toxicity studies with recombinant |[alpha]|-synuclein to suggest that conversion of this protein from soluble monomers to aggregated insoluble forms in the brain is a key event in the pathogenesis of PD. In the present study, adeno-associated virus (AAV) vector delivery of |[alpha]|-synuclein ribozyme was tested for its silencing effect on degenerating nigrostriatal neurons in MPP+ model of PD. We designed |[alpha]|-synuclein ribozyme against human |[alpha]|-synuclein gene expression and constructed |[alpha]|-synuclein ribozyme carried rAAV vector (designated rAAV-SynRz). Co-transfection of rAAV-SynRz and rAAV-|[alpha]|- synuclein into HEK293 cells resulted down regulating |[alpha]|-synuclein protein expression in vitro. Then, rAAV-SynRz was injected into SN of the MPP+-treated rats. Cell counts of TH-positive neurons in the substantia nigra revealed that rAAV-SynRz protected a significant number of TH positive cells when compared with cell counts of rAAV-EGFP or no rAAV injected rats. In close agreement, 56.2% of TH-positive cells remained in the nigral rAAV-SynRz group vs only 30.9% of in the EGFP group or 31.8% of no-rAAV treatment. These data indicated that using of rAAV-SynRz could survive more TH-positive neuron in SN in MPP+ model. Down regulation of |[alpha]|-synuclein expression might be a possible therapeutic tool for gene therapy of PD.