Identification of a dopaminergic enhancer indicates complexity in vertebrate dopamine neuron phenotype specification

摘要

ThedopaminergicneuronsofthebasalgangliaplaycriticalrolesinCNSfunctionandhumandisease,butspecificationofdopamineneuronphenotypeispoorlyunderstoodinvertebrates.Weperformedaneminvivo/emscreeninzebrafishtoidentifydopaminergicneuronenhancers,inordertofacilitatestudiesonthespecificationofneuronalidentity,connectivity,andfunctioninthebasalganglia.Basedprimarilyonidentificationofconservednon-codingelements,wetested54DNAelementsfromfourspecies(zebrafish,pufferfish,mouse,andrat),thatincluded21geneswithknownorputativerolesindopaminergicneuronspecificationorfunction.MostelementsfailedtodriveCNSexpressionordidnotexpressspecificallyindopaminergicneurons.However,wedidisolateadiscreteenhancerfromtheemotpb/emgenethatdrovespecificexpressionindiencephalicdopaminergicneurons,althoughitdidnotsharesequenceconservationwithregulatoryregionsofemotpa/emorotherdopamine-specificgenes.Fortheemotpb/emenhancer,regulationofexpressionindopamineneuronsrequiresmultipleelementsspreadacrossalargegenomicarea.Inaddition,wecomparedoureminvivo/emtestingwitheminsilico/emanalysisofgenomicregionsforgenesinvolvedindopamineneuronfunction,butfailedtofindconservedregionsthatfunctionedasenhancers.Weconcludethatregulationofdopaminergicneuronphenotypeinvertebratesisregulatedbydispersedregulatoryelements./p/div