BACKGROUND:GenetherapyforParkinson'sdiseaseisbeingexploredasaneffectivestrategytorestoreandprotectthefunctionofneuronalcellsinthesubstantianigra.Regulationofgeneexpressionisnecessaryforgenetherapytoavoidadverseeffectsduetoexcessivesynthesisoftransgeneproducts.OBJECTIVE:Herewedevelopedrecombinantadeno-associatedvirus(AAV)asaviralvector-mediatedgeneregulationsystembasedonCrerecombinasefusedtothemutatedligand-bindingdomainoftheestrogenreceptor(CreERT2)+inducingagenttamoxifen.InducibleCrerecombinasewasusedtoreducetyrosinehydroxylasegeneexpressionandtopreventtheexcessiveincreaseindopamine.DESIGN,TIMEANDSETTING:Ageneticengineeringinvitrocomparativestudyandrandomizedcontrolledanimalexperiment.ThisstudywasconductedattheGeneTherapyCenter,JichiMedicalSchool,JapanfromJune2002toJune2004.METHODS:ToconstructarecombinantAAVvectorcarryingadopaminesynthasegene.ThetyrosinehydroxylasegenewasinsertedusingaloxPfragmentthatcouldberegulatedbyCrerecombinase.TherecombinantAAVvectorcarryingtheCreERT2genewasco-transducedwithHEK293cellsandthecorpusstriatuminaratmodelofParkinson'sdisease,withinducingagenttamoxifentoregulategeneexpression.MAINOUTCOMEMEASURES:ThelevelsofdopamineandaromaticL-aminoaciddecarboxylase(AADC)activityweredetectedinHEK293cellmediumandinthecorpusstriatuminaratmodelofParkinson'sdiseaseusinghigh-performanceliquidchromatography.ImmunofluorescencedoublestainingwasusedtoobservetyrosinehydroxylaseandCreorAADCco-expressioninHEK293cellmedium.ImmunohistochemicalstainingwasemployedtoobservetyrosinehydroxylaseandAADCexpressionandbehavioralchangesweremeasuredinParkinson'srats.RESULTS:TransfectedAAV-CreERT2andAAVexpressingdopaminesynthesisenzymescouldincreasethesynthesisofdopamineinHEK293mediumandParkinson'sratstriatum(P<0.01)andimprovetherotationalbehaviorofParkin
