Ecdysone-dependent and ecdysone-independent programmed cell death in the developing optic lobe of Drosophila

摘要

TheadultopticlobeofemDrosophila/emdevelopsfromtheprimordiumduringmetamorphosisfrommid-3rdlarvalstagetoadult.Manycellsdieduringdevelopmentoftheopticlobewithapeakofthenumberofdyingcellsat24#xA0;hafterpupariumformation(hAPF).Dyingcellswereobservedinspatio-temporalspecificclusters.Here,weanalyzedthefunctionofacomponentoftheinsectsteroidhormonereceptor,EcR,inthiscelldeath.WeexaminedexpressionpatternsoftwoEcRisoforms,EcR-AandEcR-B1,intheopticlobe.Expressionofeachisoformalteredduringdevelopmentinisoform-specificmanner.EcR-B1wasnotexpressedinopticlobeneuronsfrom0to6#xA0;hAPF,butwasexpressedbetween9and48#xA0;hAPFandthendisappearedby60#xA0;hAPF.Ineachcortex,itsexpressionwasstrongerinolderglia-ensheathedneuronsthaninyoungerones.EcR-B1wasalsoexpressedinsometypesofglia.EcR-Awasexpressedinopticlobeneuronsandmanytypesofgliafrom0to60#xA0;hAPFinadifferentpatternfromEcR-B1.Then,wegeneticallyanalyzedEcRfunctionintheopticlobecelldeath.At0#xA0;hAPF,theopticlobecelldeathwasindependentofanyEcRisoforms.Incontrast,EcR-B1wasrequiredformostopticlobecelldeathafter24#xA0;hAPF.Itwassuggestedthatcelldeathcell-autonomouslyrequiredEcR-B1expressedafterpupariumformation.βFTZ-F1wasalsoinvolvedincelldeathinmanydying-cellclusters,butnotinsomeofthemat24#xA0;hAPF.Altogether,theopticlobecelldeathoccurredinecdysone-independentmanneratprepupalstageandecdysone-dependentmannerafter24#xA0;hAPF.Theacquisitionofecdysone-dependencewasnotdirectlycorrelatedwiththeinitiationorincreaseofEcR-B1expression./p/div