The association of desmin with the developing myofibrils of cultured embryonic rat heart myocytes☆

[摘要] Theassociationofdesmin,a55,000-daltonintermediate-filamentprotein,withthedevelopingcardiacmyofibrilwasstudiedbyimmunocytochemicalmethodsinprimaryculturedmyocytesisolatedfromembyronicratheartsatdifferentages.Intheearliestcontractilemyocytesobtainedfrom10-day-oldembryonichearts,desminexistsasanextensivecytoskeletalnetworkwithlittleornoassociationwiththemyofibrils.Astheheartdevelopsthecytoskeletaldesminundergoesthemyofibrils.Initially,thecytoskeletaldesminappearstooutlinethedevelopingmyofibrilasshort,discontinuousfilaments.Atintermediatestagesofheartdevelopment,desminfilamentsin12-to16-day-oldembryonicmyocytescontinuetooutlinetheformingmyofibrils.AssociatedwiththesefilamentsarecrossbridgesandfociofdesminspacedatafrequencyequaltothatoftheZ-linespacing.Desminbecomesprogressivelyassociatedwiththemyofibrilfromthecentralregionofthecelltowardthecellmargin.Desminfilamentsatthisstagebegintocoalesceintheregionoftheintercalateddisk.Intheearlyneonatalheart,desminoftheZlinesbecomescontinuousacrossthesarcomereandappearstointegratethemyofibrilsintoaunit.Theseobservationssuggestthatdesminisnotrequiredintheearlystagesofmammalianheartdevelopmentfortheinitialassemblyofcardiacsarcomeresortheinitiationofcardiacmyofibrillarcontractions.Inlaterstagesofmammalianheartdevelopment,desminisfoundassociatedwiththecardiacmyofibrilsinsuchamannerastostablyintegratetheseelementsintothecytoplasm.Additionally,desmin,intheZlinesofthemorematuremyocytesappearstomaintainthemyofibrilsincloseregistrytoeachotherandtotheintercalateddisk.

[学科分类] 生物科学（综合）