Distribution of Microtubule-Associated Proteins (MAPs) in Adult and Embryonic Mouse Retinal Explants: Presence of the Embryonic Map, MAP5/1B, in Regenerating Adult Retinal Axons

摘要

Microtubule-associatedproteins(MAPs)aredevelopmentallyregulatedproteinsinvolvedinmicrotubulepolymerizationandstabilization.WehaveaskedwhetherMAPsinregeneratingadultmouseretinalganglioncellaxonsrecapitulatethepatternofMAPsseenduringdevelopment.AdultandEmbryonicDay15(E15)mouseretinalsegmentswereexplantedontolaminin-coatedcoverslipsandallowedtoextendneuritesinserum-freemedium.Usingavarietyofmonoclonalantibodies(Mabs),westainedadultandE15explantculturesforearly(MAP5)andlate(MAP1,MAP2,MAP2a+b,tau)MAPs.OpticneuritesgrowingfromE15explantswerestronglyimmunoreactiveforMAPS.LabelingwasabsentforMAP1andMAP2a+b.MabstoMAP2andtaulightlystainedaxonsandcellbodies,probablyduetoMAP2candjuveniletauwhicharefoundindevelopingneurons.Inadultexplantcultures,bothperikaryaandaxonswereimmunoreactiveforMAP1.MAP2andMAP2a+blabeledperikaryaandfiberswithintheexplant,andtaustainedaxonsonthesubstrate.MAP5immunoreactivitywasintenseintheadultexplantcultures,labelingaxonsextendingoverthesubstrateandperikaryaanddendritesintheexplantinapatternsimilartothatseeninE15explants.Insummary,adultretinalexplantsmaintaintheiradultcomplementofMAPs,inshowinghighlevelsofMAP1,tauimmunoreactivityrestrictedtoneuritesonthesubstrate,andMAP2segregatedintoneuritesandperikaryawithintheexplant.TheexceptionisMAP5forwhichthepatternofimmunoreactivityissimilarinadultandE15retinalexplants.