Adeno-associated virus vector-mediated triple gene transfer of dopamine synthetic enzymes

Objective To explore triple gene transfer of dopamine synthetic enzymes with separate adeno-associated virus (AAV) vectors. Methods The genes for dopamine synthetic enzymes, tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC), and GTP cyclohydrolase I ( GCH, an enzyme critical for tetrahydrobiopterin synthesis) were cotransduced into 293 cells with separate AAV vectors. Expressions of TH, AADC and GCH were detected by Western blot analysis. Intracellular dopamine level was assayed by highperformance liquid chromatography. Results TH, AADC and GCH were effectively coexpressed in transduced cells with three separate AAV vectors, AAV-TH, AAV-AADC and AAV-GCH. Furthermore, the coexpression resulted in an effectively spontaneous dopamine production in cotransduced cells. Conclusion The triple transduction of TH, AADC and GCH genes with separate AAV vectors is effective, which might be important to gene therapy for Parkinson's disease.