Regulation of Specific Developmental Fates of Larval- and Adult-Type Muscles during Metamorphosis of the Frog Xenopus

Developmental Biology

Akio Nishikawa¹  Masaaki Kuroda¹  Aya Takei¹  Keiko Shimizu-Nishikawa¹  Yoko Shibota¹ 

[1] Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane, 690-8504, Japan

关键词: myoblast;    myotube;    thyroid hormone (3;    3′;    5-triiodo-l;    differentiation;    programmed cell death (apoptosis);    heterokaryon;    metamorphosis;    anuran;    Xenopus laevis;    Xenopus borealis;   

DOI  :  10.1006/dbio.2002.0800

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Duringanuranmetamorphosis,larval-typemyotubesinbothtrunkandtailareremovedbyapoptosis,andonlytrunkmusclesarereplacedbynewlyformedadult-typemyotubes.Inthepresentstudy,weclarifiedtheregulatorymechanismsforspecificdevelopmentalfatesofadultandlarvalmuscles.Twodistinct(adultandlarval)typesofmyoblastswerefoundtoexistinthetrunk,butnoorveryfewadultmyoblastswerefoundinthetail.Eachtypeofmyoblastrespondeddifferentlytometamorphictrigger,3,3′,5-triiodo-l-thyronine(T3)invitro.T3-inducedcelldeathwasobservedinlarvalmyoblastsbutnotinadultmyoblasts.Theseresultssuggestthatthefates(lifeordeath)oftrunkandtailmusclesaredeterminedprimarilybythedifferentialdistributionofadultmyoblastswithinthemuscles.However,atransplantationstudyclarifiedthateachlarvalandadultmyoblastwasnotcommittedtofuseintoparticularmyotubetypes,andtheycouldformheterokaryonmyotubesinvivo.Cellcultureexperimentssuggestedthatthefollowingtwomechanismsareinvolvedinthespecificationofmyotubefate:(1)HeterokaryonmyotubescouldescapeT3-induceddeathonlywhentheproportionofadultnucleinumberwashigherthan70%inthemyotubes.Apoptosiswasnotobservedinanylarvalnucleiwithinthesurvivingheterokaryonmyotubes,suggestingtheconversionoflarvalnucleifate.(2)Differentiationofadultmyoblastswaspromotedbythefactor(s)releasedfromlarvalmyoblastsinacelltype-specificmanner.Takentogether,thedevelopmentalfateofmyotubesisdeterminedbytheratioofnucleitypes,andtheformationofadultnuclei-richmyotubeswasspecificallyenhancedbylarvalmyoblastfactor(s).

【 授权许可】

Unknown