细胞生物学第9讲 细胞骨架

Variedshapesofcellsfibroblastsneutrophilssperm&eggredbloodcellsneurons1Variedsurfaceandinteriorstructuresciliaflagellum2Afibroblastinculture(attached);theredlabelsmicrofilamentsMovementsofcellscrawlChemotaxis(video)Aneutrophilinculture(semi-attached)3Cytoskeleton

Ref:EssentialcellbiologyChpt.17医学细胞生物学第五章第八节structureorganizationproteincomponentsandfunctions45Cytoskeletoninaculturedfibroblast(microtubules)Asupportivenetwork6Arsenicoxide+Emodintreatment6h3h9h12h0hOxidativestresscausedbyemodinincombinationwitharsenicalteredassemblyofF-actin(confocalmicroscopy).Bar=10µm.（Neoplasia.2008,10(1):41-51

）Cytoskeletonindyingcells(microfilaments)Changesincellshapeandattachment7Likeourownbonyskeleton,thecytoskeletongivescellitsshapeandallowsthecelltoorganizeitsinternalcomponentsandtomoveGreen:microtubulesRed:microfilamentsBlue:DNA8Topic1.Introducethedefinitionofcytoskeleton.Comparebrieflythesizeandstructureofmicrotubule,microfilamentandintermediatefilament?(10min)9Topic2.Becausetheorganellesandvesiclesinthecellsaretransportedasthecargosalongthemicrotubules,themicrotubuleiscalled“highwaysincells”.Afterlearningthewaysthatthemicrotubulefunctions,giveyourcommentstothismetaphor,eithersupportiveoropposite.(10min)10Thecytoskeletonfilamentsarecomprisedofsmallerproteinsubunits？Protofilamentsconsistfilaments.11Fixedhighwayorchanginganttrail?Changesoflengthandlocation：Assemblyanddisassembly（microtubulesµfilaments）12ThemicrofilamentsinadeformedcellRearrangement=Disassembly--reassembly13interphasemitosisThemicrotubulesincellsofinterphaseandmitosisRearrangement=Disassembly--reassembly14MonomersPolymerenergyMonomersThenon-covalentbondsconnectsthemonomers;Easytoformandbreak!解聚（depolymerization）聚合（polymerization）15Themonomerhastheheadandthetail;polymerizationofthemonomersmakesthestructuralpolarityofthepolymers冰糖葫芦:

山楂or梨16Nucleation=普通聚合预加“核”后聚合Nucleationisaspeed-limitedeventforassemblyMonomers---oligomers---filamentgrowing17Theplusendgrowsfasterthan

theminusend18Dynamicinstability=switchingbackandforthbetweenpolymerizationanddepolymerizationThefibersaregrowingthensuddenlyshrunk19DynamicinstabilityUnlikeourownbonyskeleton,thecytoskeletonisahighlydynamicstructurethatiscontinuouslyreorganizedasacellchangesshape,dividesandrespondstoitsenvironment.20Topic3.

Listthemajorchemicalcomponents(thenamesofproteins)of,andthewaystheyareorganizedinto,themicrotubule,microfilamentandintermediatefilament.

(10min)

Howwouldyouexplainthatthemonomersofproteinsthatcomprisethemicrotubulesandmicrofilamentsareglobal,butthosecomprisetheintermediatefilamentsarelinear?

21Theproteinsthatcomprisethemicrotubule:Tubulin(微管蛋白)（1）α-tubulin

heterodimer（2）β-tubulinthemonomerofmicrotubulepolymer

（3）γ-tubulin（only1％）22γ-tubulin

nucleationtheγ-tubulinringcomplex，γTuRC23每分子α-tubulin和β–tubulin各含有一个GTP/GDT结合位点(GTP水解供应能量)异二聚体及其组成的原纤维有极性24α-tubulinβ-tubulin每根原纤维由α-tubulinβ-tubulin组成的异二聚体相接而成(极性)每根微管单管由13根原纤维围成25Theformsofthemicrotubule:26CytoplasmicmicrotubulescentrolesCiliummicrotubulesnucleus27Thecentrosomedecidesthelocationandgrowingdirectionofthemicrotubule:2829Thefunctionsofthemicrotubule30Topic4.

Take3examplesrespectivelytoillustratethefunctionsofmicrotubulesandmicrofilaments.(20min)31Insciaticnerve:Microtubules&intermediatefilamentTransversesectionlongitudinalsection32movie331.Cellshape2.centrosome,spindle,basalbody,ciliaandflagellum3.TracksoftransportandanchorageoforganellesTomaintaintheshapeandtheorganellelocationofcellsininterphase;Toformthespindletomediatecelldivisioninmitosis341.Tosupportandmaintaincellshape352.Toformcentrosome,spindle,basalbody,ciliaandflagellum微管高尔基体中心体细胞核电镜下的中心粒：9组三联微管36centrosome（中心体）=apairof

centriols（中心粒）37spindle（纺锤体）&poles（极）38movie=39OviductunderScanningEMbasalbody,cilium&flagellum基粒、纤毛和鞭毛40basalbody,cilium&flagellum(基粒、纤毛和鞭毛

)41Motorproteins3.Toprovidetracksoftransportandanchorageoforganelles42Motorproteinsdecidethedirectionsofthevesicletransport

驱动蛋白kinesin

:towardtheplusend

动力蛋白dynein:towardtheminusend43卡通Motorproteinsdecidethedirectionsofthevesicletransport

驱动蛋白kinesin

:towardtheplusend

动力蛋白dynein:towardtheminusend44microtubulesERGolgiapparatuscentrosomenucleus3.Toprovidetracksoftransportandanchorageoforganelles45organellesmicrotubulesERGolgiapparatus46Topic5.Decipherthefollowingmicrograph(5min)47depolymerizationpolymerizationTaxolbindswithmicrotubulesBlockageofdepolymerizationColchicine,nocodazolevinblastinbindwithtubulinsBlockageofpolymerizationAbnormalityinmicrotubuleformation48TaxolbindswithmicrotubulesBlockageofdepolymerizationAbnormalityinmicrotubuleformationCancercelldivision49Theproteinsthatcomprisethemicrofilament:

Actin(肌动蛋白)Microfilaments=actinfilaments5051每分子actin含有一个ATP/ADT结合位点(ATP水解供应能量)52Thefunctionsofthemicrofilament53ThefunctionsofthemicrofilamentTosupporttheplasmamembraneandsurfacestructuresTomediatecellmovements5455Actin-associatedproteins(MAP)regulateactinpolymerizationandorganizationFortheactincytoskeletontodrivemotility,thecellmustbeabletoregulateactinpolymerizationanddepolymerization.Actin-associatedproteins:associatewithmonomersorfilamentsinfluencetheorganizationofactinfilamentsincells56Stressfibersoffibroblasts成纤维细胞中的应力纤维57Microvilli(微绒毛)intheepithelialcellsofintestine58Cellcrawling卡通movie59Contractileringincelldivision60Musclecontraction=movementofmyosinIIattachedreleasedcockedforcegeneratingattachedMusclecontraction61myosinII

&actinfilamentsmyosinII(肌球蛋白2):MAPinmusclecells62Myofibril&scromere(肌丝与肌节)6364Figure17-42EssentialCellBiology(©GarlandScience2010)MyosinIImovement&shortnessofscomere肌球蛋白移动与肌节缩短65解聚（depolymerization）聚合（polymerization）F-actinG-actinG-actinPhalloidinbindswithactinfilamentsBlockageofdepolymerizationlatrunclin

bindwithactinsBlockageofpolymerizationAbnormalityinmicrotubuleformation66Thetwocytoskeletalsystemscanbeboundtogetherbylinkerproteinsthatattachmicrotubulestoactinfilaments.Interactionsbetweenmicrotubulesandactinfilaments67Theproteinsthatcomprisetheintermediatefilament:

VariedtypesKaratinVimentinLaminNF……68Tissuespecificity6970Figure17-3EssentialCellBiology(©GarlandScience2010)Ropelikefilament,don’tassemble/dissemblefrequently

71Thefunctionsoftheintermediatefilament72CellshapeNuclearenvelope2）CelljunctionandtissueintegrityTosupportplasmamembraneandcelljunction73microtubuleIFSimilarorientationwithmicrotubulesInteractionwithmicrotubules74Figure17-7aEssentialCellBiology(©GarlandScience2010)75Figure17-2EssentialCellBiology(©GarlandScience2010)76IF:tomaintaincelljunctionandtissueintegrity77IntermediatefilamentsCelljunction:desmosome78Tissuespecificity79Threecytoskeletonproteinsarestainedinafibroblast80

TubulinandActinarehighlyconservedduringeucaryoticevolutionandexistedinalleucaryoticcelltypes.Monomer:global

Intermediatefilamentproteinsarenotexistedinallmetazoans,notallcelltypeeither.(Cellspecific)Monomer:elongated

81Topic3.

Listthemajorchemicalcomponents(thenamesofproteins)of,andthewaystheyareorganizedinto,themicrotubule,microfilamentandintermediatefilament.

Howwouldyouexplainthatthemonomersofproteinsthatcomprisethemicrotubulesandmicrofilamentsareglobal,butthosecomprisetheintermediatefilamentsarelinear?(10min)8283Topic6.Decipherthefollowingcartoonabout3typesofcytoskeleton,asasummary.(10min)84细胞质骨架与疾病细胞骨架的异常可引起很多疾病，特别是心脏、骨骼肌、神经系统的遗传性疾病等。肿瘤细胞：旺盛的增殖、迁移能力和分化缺陷都与细胞骨架有关干扰细胞骨架组装的药物作为抗癌药(紫杉醇、长春花碱、秋水仙素。。。)85细胞质骨架(微管)与疾病Nervedegenerativediseases微管相关蛋白tau磷酸化异常（微管组装异常）：

--老年痴呆(Alzheimerdisease)86体外培养细胞过度表达MAP2或tau对微管束结构的影响87细胞质骨架(微丝)与疾病Heartdiseases--肌动蛋白基因点突变：扩张性心肌病--微丝相关蛋白基因点突变：家族性肥大性心肌病小鼠心脏：左－正常6月右－myosin基因突变Arg403->Gln

心房肥大，通常生后数周死亡88细胞质骨架(中间丝)与疾病Skindiseases--角蛋白基因突变:单纯性大泡性表皮松懈症Nervedegenerativediseases--运动神经元中神经丝组装异常：肌萎缩性侧索硬化症89思考题在下列各类细胞中你认为哪一种有可能在细胞质中含有大量的中间丝？（与微丝的提供细胞机械强度功能有关）。A.大变形虫B.皮肤的上皮细胞C.植物细胞D.大肠杆菌紫杉醇与微管紧密结合，使之十分稳定，不易解聚。当它作用于细胞时，造成更多的游离微管蛋白组装成微管。秋水仙素具有与紫杉醇相反的作用。紫杉醇和秋水仙素一样对分裂细胞是致命的，两者都用作抗癌药。请根据你对微管动力学的知识，解释为何这两种药物尽管作用机理不同却对分裂细胞都是有毒的？90Microtubulesarepolarizedpolymers.Theplusendiscrownedbyβ-tubulinandassemblesfaster.Theminusendiscrownedbyα-tubulinandassemblesslower.91结构：碱性微管结合区域酸性突出区域