title: Viral-mediated temporally controlled dopamine production in a rat model of Parkinson disease.
abstract: Regulation of gene expression is necessary to avoid possible adverse effects of gene therapy due to excess synthesis of transgene products. To reduce transgene expression, we developed a viral vector-mediated somatic regulation system using inducible Cre recombinase. A recombinant adeno-associated virus (AAV) vector expressing Cre recombinase fused to a mutated ligand-binding domain of the estrogen receptor alpha (CreER(T2)) was delivered along with AAV vectors expressing dopamine-synthesizing enzymes to rats of a Parkinson disease model. Treatment with 4-hydroxytamoxifen, a synthetic estrogen receptor modulator, activated Cre recombinase within the transduced neurons and induced selective excision of the tyrosine hydroxylase (TH) coding sequence flanked by loxP sites, leading to a reduction in transgene-mediated dopamine synthesis. Using this strategy, aromatic L-amino acid decarboxylase (AADC) activity was retained so that l-3,4-dihydroxyphenylalanine (L-dopa), a substrate for AADC, could be converted to dopamine in the striatum and the therapeutic effects of L-dopa preserved, even after reduction of TH expression in the case of dopamine overproduction. Our data demonstrate that viral vector-mediated inducible Cre recombinase can serve as an in vivo molecular switch, allowing spatial and temporal control of transgene expression, thereby potentially increasing the safety of gene therapy.
authors.affiliation: Division of Neurology, Department of Medicine, Center for Molecular Medicine, Jichi Medical School, Tochigi 329-0498, Japan.
authors.forename: Xiao-Gang
authors.initials: XG
authors.lastname: Li
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.forename: Mika
authors.initials: M
authors.lastname: Kodera
authors.forename: Yuko
authors.initials: Y
authors.lastname: Nara
authors.forename: Naomi
authors.initials: N
authors.lastname: Takino
authors.forename: Chieko
authors.initials: C
authors.lastname: Muramatsu
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Ikeguchi
authors.forename: Fumi
authors.initials: F
authors.lastname: Urano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ichinose
authors.forename: Daniel
authors.initials: D
authors.lastname: Metzger
authors.forename: Pierre
authors.initials: P
authors.lastname: Chambon
authors.forename: Imaharu
authors.initials: I
authors.lastname: Nakano
authors.forename: Keiya
authors.initials: K
authors.lastname: Ozawa
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Muramatsu
mesh_terms: D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism; D002460:Cell Line; D003342:Corpus Striatum / Q000201:enzymology; D000229:Dependovirus / Q000235:genetics*; D004195:Disease Models, Animal; D004298:Dopamine / Q000096:biosynthesis*; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D019426:Integrases / Q000096:biosynthesis / Q000235:genetics; D007980:Levodopa / Q000378:metabolism; D008297:Male; D051379:Mice; D009474:Neurons / Q000201:enzymology; D010300:Parkinson Disease / Q000378:metabolism / Q000628:therapy*; D051381:Rats; D017208:Rats, Wistar; D011995:Recombination, Genetic; D013239:Stereotyped Behavior; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis / Q000235:genetics; D014764:Viral Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D020847:Estrogen Receptor Modulators; D047628:Estrogen Receptor alpha; D014764:Viral Proteins; D013629:Tamoxifen; C016601:afimoxifene; D007980:Levodopa; D014446:Tyrosine 3-Monooxygenase; C045073:Cre recombinase; D019426:Integrases; D001142:Aromatic-L-Amino-Acid Decarboxylases; D004298:Dopamine