The Step-Wise Assembly of a Functional Nucleolus in Preimplantation Mouse Embryos Involves the Cajal (Coiled) Body☆

Developmental Biology

Pascale Debey¹  Christine Baly¹  Martine Chebrout¹  Olga Zatsepina¹ 

[1] A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992, Moscow, Russia

关键词: Cajal body;    development;    mouse preimplantation embryos;    nucleologenesis;    nucleolus precursor body;    polymerase I;   

DOI  :  10.1006/dbio.2002.0865

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Afterfertilization,ribosomalRNAsynthesisissilencedduringaperiodwhichdependsonthespecies.Dataconcerningthereassemblyofafunctionalnucleolusremainscarce.Wehaveexaminedbyimmunocytochemistry,Westernblots,andBrUTPmicroinjectionthedynamicsofmajornucleolarproteinsduringthefirstcyclesofmouseembryogenesis,inrelationtorDNAtranscriptionsitesandcoilin,amarkerofCajalbodies.Weshowthat:(1)thereinitiationofrDNAtranscriptionoccursatthetwo-cellstage,44–45hafterhCGinjection(hphCG),atthesurfaceofthenucleolarprecursorbodies(NPBs),wheretheRNApolymeraseI(polI)transcriptioncomplexisrecruited4–5hbefore;(2)theNPBsarenotequalintheirabilitytosupportrecruitmentofpolIandrDNAtranscription;(3)maternallyinheritedfibrillarinundergoesadynamicredistributionduringthesecondcellstage,togetherwithcoilin,leadingtotheassemblyoftheCajalbodyaround40hphCG;and(4)thepolIcomplexisfirstrecruitedtotheCajalbodybeforereachingitsrDNAtemplate.WealsofindthatfibrillarinandB23arebothdirectlyassembledaroundNPBspriortoongoingpre-rRNAsynthesis.Altogether,ourresultsrevealaroleoftheCajalbodiesinthebuildingofafunctionalnucleolus.

【 授权许可】

Unknown