第十一章-细胞核-北大陈建国细胞生物学

NucleusandChromosomesChapter11:MolecularBiologyoftheCell(©GarlandScience2008)张传茂[e-mail](1)Atypicalnon-mitoticnucleusincludesseveralmajorcomponents.(2)Nuclearenvelopeandnuclearporecomplex.(3)Thecomponentsofchromatinandpackagingofchromosome.(4)Nucleolus.(5)Functionalstatesofthenucleiindifferentcellsmaybedifferent1.Atypicalnon-mitoticnucleusincludesseveralmajorcomponentsHistologicalsectionoftheGastrointestinalTract://://://核质2.TheNuclearenvelopeandNPCsA.Structure:Double-membranenuclearenvelopesurroundsthenucleus图11-1细胞核截面图A.细胞核结构组成示意图。B.透射电镜图片显示胰腺细胞核：Nu，核仁；NPC，核孔复合体；Chr，染色质；NE，核被膜。（B图由梁凤霞博士惠赠）Qi,et.al.,SCIENTIASINICAVitae,201316SEMCytoplasmicfaceGoldbergandAllenNucleoplasmicfaceGoldbergandAllen图11-2用高分辨率扫描电镜（上）和冷冻蚀刻电镜技术（左）显示的核孔复合体（NPC）。(上图由HasRis博士惠赠；左图由Basera博士惠赠）NPCByBoZhangByMGoldbergTheNuclearEnvelopeunderTEMandSEMTheNuclearLaminaB.ThenuclearenvelopeconsistsoftwomembranesbyaperinuclearspaceTheinnersurfaceofthenuclearenvelopeislinedbythenuclearlaminaThenuclearlaminasupportsthenuclearenvelope:Givesshapeandstabilityofnuclearenvelope;ProvidesastructurelinkbetweenchromatinandnuclearenvelopeThenuclearlaminaiscomposedoflamins.Theintegrityofthenuclearlaminaisregulatedbyphosphorylationanddephosphorylation.TheINMProteinsC.TheNuclearEnvelopeDynamicsduringtheCellCycleBreakdownandreformationofnuclearenvelopeduringmitosisForbesetal,Cell1983FateofLambdaDNAinjectedintoXenopuseggsLSSEggscollection＋chromatinorDNAnucleiNuclearassemblyincell-freesystemsFormationinvitroofspermpronucleiandmitoticchromosomesinducedbyamphibianooplasmiccomponents.LohkaMJ,MasuiYScience,1983Nuclearreconstitutioninvitro:stagesofassemblyaroundprotein-freeDNA.NewportJ.Cell1987Nuclearreconstitutioninvitro:stagesofassemblyaroundprotein-freeDNA.(NewportJ.Cell1987)distinctvesiclepopulationtargetsmembranesandporecomplexestothenuclearenvelopeinXenopuseggsVigersGP,LohkaMJ.,JCellBiol.1991AmodelforNEassembly.VigersandLohka,1991D.Nuclearporecomplex(NPC)TEMGoldbergandAllen,1992,JCBCytoplasmicRingNuclearRingSummaryofvertebratenucleoporins(Antoninetal.,2008)E.MoleculesenterandexitthenucleusthroughnuclearporecomplexBidirectionaltrafficPassivetransport—passivelydiffuse3000-4000NPC/cell(mammalian);Toimportabout106histone/3mins.(DNA-sythesizingcell)=100histone/min/NPCEachNPCcontainsoneormoreopenaqueouschannels:9nmindiameterand15nmlongTheeffectivesizeofthesechannelshasbeendeterminedbyinjectingvarioussizesofcolloidalgoldparticlesandexaminedbyelectronmicroscopy.10nmindiameter60kdglobularproteinAbletoenterthenucleusActivetransportTransportoflargeproteinsintonucleusneedsnuclearlocalizationsignal(NLS)NLSarepresentonlyinnuclearproteinsAtypicalNLScontainsseveralconsecutivebasicaminoacids(thepositivelychargedAa:Lys,Arg)Normalpyruvatekinase:incytosolChimericpyruvatekinasecontainingSV40NLS:innucleusHaraguchietal,2000TheNuclearProteinImportWild-type:T-antigeninnucleusMutant-type:T-antigenincytosolSamplesoftheNuclearLocalisationSequences(NLS)PKKKRKV132PAAKRVKLD328QRKRQK372NF-KBp50HRIEEKRKRTYETFKSI345NF-KBp65SV40T-agC-mycKRKRRP508,PKKNRLRRK615BRCA1KR-10aa-KKKL171NucleoplasminKR-11aa-KKLR877RBKR-12aa-KKk321p53Mdm2RKRRR182LaminTKKRKLEGNYNNQNQSSNFGPMKGGNFGGRS-SGPYGGGGQYFAKPRNQGGYGGS308hnRNPA1M9NuclearimportandexportNuclearimportreceptorsbindNLSandNucleoporinsTheRanGTPasedrivesdirectionaltransportthroughNPCThecompartmentalizationofRan-GDPandRan-GTPandthenucleartransportPaulClarkeandChuanmaoZhang,2008.NRMCBhnRNPproteinscontainanuclear-exportsignal(NES)Reference:Cell92:327,1998Nuclearexportworkslikenuclearimport,butinreverseToyoshima,…andNishida.NuclearexportofcyclinB1anditspossibleroleintheDNAdamage-inducedG2checkpoint.EMBOJ.17:2728–2735,1997DLCQAFSDVILAYLCQAFSDVILAYLCQAFSDVILAELCQAFSDVLIHhumanmouseratXenopusDLQKKLEELELDELALKLAGLDINLQLPPLERLTLDMAPKKPKIRevNESCyclinB1NES141152ExamplesoftheNuclearExportSequences(NES)AfterNishidaandCo.AmodelforhowGTPhydrolysisbyRanprovidesdirectionalityfornucleartransportTerry,Shows,andWente,SCIENCEVOL31830NOVEMBER2007Thephosphorylationoflaminstriggersthedisassemblyofthenuclearlamina,whichinturncausesthenuclearenvelopebrokendownintovesicles.Dephosphorylationoflaminsreversesthisprocess.Becausethenewnuclearenvelopeissoclosetothesurfaceofchromosomes,itexcludesalloftheproteinsinthecellexceptthoseboundtothechromosomes.Oldnuclearenvelopereformsnewnuclearenvelope.Nuclearlocalizationorexportsignalsarenotcleavedoffaftertransportintothenucleus.ByDSpector,JCSTheGeneralStructureoftheNucleus3.ChromatinandchromosomesChromatin:(Interphase)Fibers,10-30nmindiameter,Dispersedthroughthenucleus.DNA+Proteins+RNA.Chromosomes:(Mphase)Celldivision,thesefibers