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1、Varied surface and interior structuresciliaflagellumA fibroblast in culture (attached); the red labels microfilamentsMovements of cellscrawlChemotaxis(video)A neutrophil in culture (semi-attached) CytoskeletonRef: Essential cell biology Chpt.17医学细胞生物学 第五章第八节1.structure2.organization3.protein compone
2、nts and 4.functionsCytoskeleton in a cultured fibroblast (microtubules) A supportive networkArsenic oxide + Emodin treatment6h3h9h12h0hOxidative stress caused by emodin in combination with arsenic altered assembly of F-actin (confocal microscopy). Bar=10m. （Neoplasia. 2008, 10(1):41-51 ）Cytoskeleton
3、 in dying cells (microfilaments)Changes in cell shape and attachmentTopic 1. Introduce the definition of cytoskeleton. Compare briefly the size and structure of microtubule, microfilament and intermediate filament? (10 min)Topic 2. Because the organelles and vesicles in the cells are transported as
4、the cargos along the microtubules, the microtubule is called “highways in cells”. After learning the ways that the microtubule functions, give your comments to this metaphor, either supportive or opposite. (10 min)The cytoskeleton filaments are comprised of smaller protein subunits？Protofilaments co
5、nsist filaments.Fixed highway or changing ant trail?Changes of length and location：Assembly and disassembly（microtubules & microfilaments）The microfilaments in a deformed cellRearrangement=Disassembly- reassemblyinterphasemitosisThe microtubules in cells of interphase and mitosisRearrangement=Disass
6、embly- reassemblyMonomers PolymerenergyMonomersThe non-covalent bonds connects the monomers;Easy to form and break!解聚（depolymerization）聚合（polymerization）The monomer has the head and the tail; polymerization of the monomers makes the structural polarity of the polymers冰糖葫芦: 山楂 or 梨Nucleation=普通聚合预加“核
7、”后聚合Nucleation is a speed-limited event for assemblyMonomers -oligomers -filament growingThe plus end grows faster than the minus endDynamic instability= switching back and forth between polymerization and depolymerizationThe fibers are growing then suddenly shrunkDynamic instabilityl Unlike our own
8、 bony skeleton, the cytoskeleton is a highly dynamic structure that is continuously reorganized as a cell changes shape, divides and responds to its environment.Topic 3. l List the major chemical components (the names of proteins) of, and the ways they are organized into, the microtubule, microfilam
9、ent and intermediate filament. (10 min)l How would you explain that the monomers of proteins that comprise the microtubules and microfilaments are global, but those comprise the intermediate filaments are linear? The proteins that comprise the microtubule:Tubulin (微管蛋白微管蛋白) ) （1）-tubulin heterodimer
10、 （2）-tubulinu the monomer of microtubule polymer （3）-tubulin （only 1）-tubulin nucleationnucleationthe -tubulin ring complex，TuRCu每分子每分子-tubulin-tubulin和和 tubulintubulin各含有各含有一个一个GTP/GDT GTP/GDT 结合位结合位点点( (GTPGTP水解供应水解供应能量能量) )u异二聚体及其组成异二聚体及其组成的原纤维有的原纤维有极性极性-tubulin-tubulin-tubulin-tubulin每根原纤维由每根原纤维
11、由-tubulin-tubulin -tubulin -tubulin组成的异二聚体组成的异二聚体相接而成相接而成( (极性极性) )每根微管单管由每根微管单管由1313根原纤维围成根原纤维围成The forms of the microtubule:Cytoplasmic microtubulescentrolesCilium microtubulesnucleusThe centrosome decides the location and growing direction of the microtubule:The functions of the microtubuleTopic
12、4. l Take 3 examples respectively to illustrate the functions of microtubules and microfilaments. (20 min)In sciatic nerve:Microtubules & intermediate filamentTransverse sectionlongitudinal sectionmovie1. Cell shape2. centrosome, spindle, basal body, cilia and flagellum3.Tracks of transport and anch
13、orage of organellesuTo maintain the shape and the organelle location of cells in interphase;uTo form the spindle to mediate cell division in mitosis1. To support and maintain cell shape2. To form centrosome, spindle, basal body, cilia and flagellum微管微管高尔基体高尔基体中心体中心体细胞核细胞核电镜下的中心粒：电镜下的中心粒：9 9组三联微管组三联微
14、管centrosome（中心体）（中心体）= a pair of centriols（中心粒（中心粒 ）spindle（纺锤体）（纺锤体）& poles（极）（极）movie=Oviduct under Scanning EMbasal body, cilium & flagellum基粒、纤毛和鞭毛基粒、纤毛和鞭毛 basal body, cilium & flagellum (基粒、纤毛和鞭毛基粒、纤毛和鞭毛基粒、纤毛和鞭毛基粒、纤毛和鞭毛 )Motor proteins3. To provide tracks of transport and anchorage of organelle
15、sMotor proteins decide the directions of the vesicle transport 驱动蛋白驱动蛋白kinesinkinesin : toward the : toward the plus endplus end 动力蛋白动力蛋白dynein dynein : toward the : toward the minus endminus end卡通Motor proteins decide the directions of the vesicle transport 驱动蛋白驱动蛋白kinesinkinesin : toward the : tow
16、ard the plus endplus end 动力蛋白动力蛋白dynein dynein : toward the : toward the minus endminus endmicrotubulesERGolgi apparatuscentrosomenucleus3. To provide tracks of transport and anchorage of organellesorganellesmicrotubulesERGolgi apparatusTopic 5. Decipher the following micrograph (5 min) depolymeriza
17、tion polymerizationTaxol binds with microtubulesBlockage of depolymerizationColchicine, nocodazolevinblastin bind with tubulinsBlockage of polymerizationAbnormality in microtubule formationTaxol binds with microtubulesBlockage of depolymerizationAbnormality in microtubule formationCancer cell divisi
18、onThe proteins that comprise the microfilament:Actin (肌动蛋白肌动蛋白)Microfilaments = actin filaments每分子每分子actinactin含有一含有一个个ATP/ADT ATP/ADT 结合位点结合位点( (ATPATP水解供应能量水解供应能量) )The functions of the microfilamentThe functions of the microfilament1.To support the plasma membrane and surface structures 2.To medi
19、ate cell movements Actin-associated proteins (MAP) regulate actin polymerization and organizationFor the actin cytoskeleton to drive motility, the cell must be able to regulate actin polymerization and depolymerization.Actin-associated proteins:associate with monomers or filaments influence the orga
20、nization of actin filaments in cellsStress fibers of fibroblasts成纤维细胞中的应力纤维成纤维细胞中的应力纤维Microvilli (微绒毛微绒毛)in the epithelial cells of intestineCell crawling卡 通movieContractile ring in cell divisionMuscle contraction= movement of myosin II= movement of myosin IIattachedreleasedcockedforce generatingatt
21、achedMuscle contractionmyosin II & actin filamentsmyosin II (肌球蛋白肌球蛋白 2): MAP in muscle cellsMyofibril & scromere (肌丝与肌节肌丝与肌节)Figure 17-42 Essential Cell Biology ( Garland Science 2010)Myosin II movement & shortness of scomereMyosin II movement & shortness of scomere肌球蛋白移动与肌节缩短肌球蛋白移动与肌节缩短肌球蛋白移动与肌节缩短
22、肌球蛋白移动与肌节缩短解聚（depolymerization）聚合（polymerization）F-actinG-actinG-actinPhalloidin binds with actin filamentsBlockage of depolymerizationlatrunclin bind with actinsBlockage of polymerizationAbnormality in microtubule formationThe two cytoskeletal systems can be bound together by linker proteins that a
23、ttach microtubules to actin filaments.Interactions between microtubules and actin filamentsThe proteins that comprise the intermediate filament:Varied typesl Karatin l Vimentinl Laminl NFl Tissue specificityFigure 17-3 Essential Cell Biology ( Garland Science 2010)Ropelike filament, dont assemble/di
24、ssemble frequently The functions of the intermediate filament1.Cell shape2.Nuclear envelope 2）Cell junction and tissue integrityTo support plasma membrane and cell junctionmicrotubuleIFSimilar orientation with microtubulesInteraction with microtubulesFigure 17-7a Essential Cell Biology ( Garland Sci
25、ence 2010)Figure 17-2 Essential Cell Biology ( Garland Science 2010)IF: to maintain cell junction and tissue integrityIntermediate filamentsCell junction: desmosomeTissue specificityThree cytoskeleton proteins are stained in a fibroblast Tubulin and Actin are highly conserved during eucaryotic evolu
26、tion and existed in all eucaryotic cell types.Monomer: global Intermediate filament proteins are not existed in all metazoans, not all cell type either. (Cell specific)Monomer: elongated Topic 3. l List the major chemical components (the names of proteins) of, and the ways they are organized into, t
27、he microtubule, microfilament and intermediate filament. l How would you explain that the monomers of proteins that comprise the microtubules and microfilaments are global, but those comprise the intermediate filaments are linear? (10 min)Topic 6. Decipher the following cartoon about 3 types of cyto
28、skeleton, as a summary. (10 min)细胞质骨架与疾病细胞质骨架与疾病 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。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。紫杉醇、长春花碱、秋水仙素。)细胞质骨架细胞质骨架( (微管微管) )与疾病与疾病Nerve degenerative diseases微管相关蛋
29、白tau磷酸化异常（微管组装异常）： -老年痴呆(Alzheimer disease)体外培养细胞过度表达MAP2或 tau对微管束结构的影响细胞质骨架细胞质骨架( (微丝微丝) )与疾病与疾病Heart diseases-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：小鼠心脏：左正常左正常6月月右右myosin基因突变基因突变Arg403-Gln 心房肥大，通常生后数周死亡心房肥大，通常生后数周死亡细胞质骨架细胞质骨架( (中间丝中间丝) )与疾病与疾病Skin diseases -角蛋白基因突变: 单纯性大泡性表皮松懈症Nerve degenerat
30、ive diseases-运动神经元中神经丝组装异常：肌萎缩性侧索硬化症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）。的中间丝？（与微丝的提供细胞机械强度功能有关）。 A. A.大变形虫大变形虫 B.B.皮肤的上皮细胞皮肤的上皮细胞 C.C.植物细胞植物细胞 D. D.大肠杆菌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。秋水仙素具于细胞时，造成更多的游离微管蛋白组装成微
31、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，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？的？Microtubules are polarized polymers. The plus end is crowned by -tubulin and assembles faster. The minus end is crowned by -tub
32、ulin and assembles slower.结构结构： 碱性微管结合区域碱性微管结合区域 酸性突出区域酸性突出区域微管结合蛋白（微管结合蛋白（MAPMAP）体外培养细胞过度表达MAP2或 tau对微管束结构的影响微微丝丝装装配配中中的的成成核核作作用用q 与微管装配需要与微管装配需要TuRCTuRC成核作用类似，微丝装成核作用类似，微丝装配需要配需要ARP complex的成核作用的成核作用微丝的装配微丝的装配卡通q 与微管成核作用发生在与微管成核作用发生在细胞中央（中心体）细胞中央（中心体）不不同，微丝成核作用发生在同，微丝成核作用发生在质膜下区域质膜下区域q ARP复合体可以附着于
33、质膜，或附着于已形成复合体可以附着于质膜，或附着于已形成的微丝纤维形成树状结构的微丝纤维形成树状结构微丝的装配微丝的装配伪足形成和前行时微丝结构的移动方向：向前伪足形成和前行时微丝结构的移动方向：向前前方聚合大于解聚前方聚合大于解聚后方解聚大于聚合后方解聚大于聚合 Myosin-II functions in muscle contractionMyosin-II is the motor that powers muscle contraction.Actin and myosin-II are the major components of the sarcomere.The sarcom
34、ere is the fundamental contractile unit of striated muscle.Figure 17-46 Essential Cell Biology ( Garland Science 2010)肌球蛋白移动是钙离子结合启动的肌球蛋白移动是钙离子结合启动的Figure 17-44 Essential Cell Biology ( Garland Science 2010)触发钙离子浓度升高的原因：电压门控钙通道开放触发钙离子浓度升高的原因：电压门控钙通道开放（1）角蛋白角蛋白: : 角蛋白纤维（角蛋白纤维（keratin filament） （2）神经丝
35、蛋白：神经丝神经丝蛋白：神经丝（neurofilament） （3）波形蛋白等：波形蛋白样纤维（波形蛋白等：波形蛋白样纤维（vimentin-like filaments） （4）核纤层蛋白（核纤层蛋白（lamin） （5）巢蛋白（巢蛋白（nestin） （6）未归类的蛋白质未归类的蛋白质 中间丝的化学组成中间丝的化学组成成分复杂，组织特异性综合细胞骨架的功能综合细胞骨架的功能shape, mobility and strength 形状：形状： 微管微管- 总支架、纤毛等表面结构总支架、纤毛等表面结构 微丝微丝- 微绒毛微绒毛 中间丝中间丝- 支撑支撑运动：运动： 微管微管- 膜泡运输、纤毛摆动、细胞器移动膜泡运输、纤毛摆动、细胞器移动 微丝微丝- 变形、爬行、游走变形、爬行、游走强度：强度： 微管微管- 细胞器定位细胞器定位 微丝微丝- 应力纤维、连接应力纤维、连接 中间丝中间丝- 支撑、连接支撑、连接
