title: Optimization of continuous in vivo DOPA production and studies on ectopic DA synthesis using rAAV5 vectors in Parkinsonian rats.
abstract: Viral vector-mediated gene transfer is emerging as a novel therapeutic approach with clinical utility in treatment of Parkinson's disease. Recombinant adeno-associated viral (rAAV) vector in particular has been utilized for continuous l-3,4 dihydroxyphenylalanine (DOPA) delivery by expressing the tyrosine hydroxylase (TH) and GTP cyclohydrolase 1 (GCH1) genes which are necessary and sufficient for efficient synthesis of DOPA from dietary tyrosine. The present study was designed to determine the optimal stoichiometric relationship between TH and GCH1 genes for ectopic DOPA production and the cellular machinery involved in its synthesis, storage, and metabolism. For this purpose, we injected a fixed amount of rAAV5-TH vector and increasing amounts of rAAV5-GCH1 into the striatum of rats with complete unilateral dopamine lesion. After 7 weeks the animals were killed for either biochemical or histological analysis. We show that increasing the availability of 5,6,7,8-tetrahydro-l-biopterin (BH4) in the same cellular compartment as the TH enzyme resulted in better efficiency in DOPA synthesis, most likely by hindering inactivation of the enzyme and increasing its stability. Importantly, the BH4 synthesis from ectopic GCH1 expression was saturable, yielding optimal TH enzyme functionality between GCH1 : TH ratios of 1 : 3 and 1 : 7.
authors.affiliation: Department of Experimental Medical Science, Lund University, Brain Repair and Imaging in Neural Systems, Lund, Sweden. tomas.bjorklund@med.lu.se
authors.forename: Tomas
authors.initials: T
authors.lastname: Björklund
authors.forename: Hélène
authors.initials: H
authors.lastname: Hall
authors.forename: Nathalie
authors.initials: N
authors.lastname: Breysse
authors.forename: Charlotte
authors.initials: C
authors.lastname: Soneson
authors.forename: Thomas
authors.initials: T
authors.lastname: Carlsson
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Mandel
authors.forename: Manolo
authors.initials: M
authors.lastname: Carta
authors.forename: Deniz
authors.initials: D
authors.lastname: Kirik
mesh_terms: D000818:Animals; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism / Q000473:pathology; D000229:Dependovirus / Q000235:genetics; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004298:Dopamine / Q000096:biosynthesis* / Q000378:metabolism; D005260:Female; D006136:GTP Cyclohydrolase / Q000235:genetics* / Q000378:metabolism; D015316:Genetic Therapy / Q000379:methods*; D007150:Immunohistochemistry; D016627:Oxidopamine; D020734:Parkinsonian Disorders / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013565:Sympatholytics; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics* / Q000378:metabolism
chemical_list: D013565:Sympatholytics; D001708:Biopterins; D004295:Dihydroxyphenylalanine; D016627:Oxidopamine; D014446:Tyrosine 3-Monooxygenase; D006136:GTP Cyclohydrolase; C003402:sapropterin; D004298:Dopamine