细胞生物学细胞信号转导PPT课件.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,细胞生物学,细胞信号转导,一、细胞膜受体的结构和特性,膜受体,（,membrane receptor,）是可选择性地识别和结合外来信号，并引起相应的细胞生物效应的一类膜蛋白。其化学成分多为跨膜糖蛋白，约占膜总蛋白的。不同的受体有不同的结构，一般包括三个部分：,、,识别部,（,discriminator,）也称调节亚单位，是受体蛋白的胞外部分。依赖其糖链的多样性，识别不同的化学信号。,、,效应部,（,effector,）或称催化亚单位。是受体的膜内胞质部分，通常具有酶活性。在受体与化学信号结合后被激活，产生相应的生物学效应。,、,转化部,（,transducer,）亦称之为传导部（,inducer,），是受体与效应部之间的偶联成分。它可将识别部所接受的信息经过转换传递给效应部。,细胞生物学,细胞信号转导,二、膜受体的特性,识别外来信号并通过构象变化引发胞内继发效应是受体的两个基本作用。它一般具有以下特性：,、,特异性,受体与化学信号的专一性结合是依靠分子之间的立体构象互补的非共价键结合。这种特异性结合不是绝对的。,、,可饱和性,一个细胞或一定量组织内受体数目是有限的，各类细胞中不同受体的浓度是相对恒定的。因此，受体与配体的结合有一个饱和度。,、,高亲和性,受体与配体具有很强的亲和力，表现为：当溶液中只有相当低浓度的配体时，就足以使二者结合达到饱和。,细胞生物学,细胞信号转导,、,可逆性,由于受体与配体之间属于非共价键结合，所以，分子间的识别反应往往是可逆的。当结合引发出生物效应后，受体配体复合物便解离，受体又恢复到原来状态，能再与配体结合。,、,特定的组织定位,受体的分布，无论在种类，还是数量上，均呈现特定的模式，即受体之存在于靶细胞。,细胞生物学,细胞信号转导,三、膜受体类型,根据膜受体蛋白的类型及相应的信号转导机制之不同，可将膜受体归纳为以下三种类型：,离子通道偶联受体,G,蛋白偶联受体,酶偶联受体,核受体,细胞生物学,细胞信号转导,离子通道型受体,离子通道型受体是一类自身为离子通道的受体，即配体门通道（,ligand-gated channel,）。主要存在于神经、肌肉等可兴奋细胞，其信号分子为神经递质。,离子通道型受体分为阳离子通道，如乙酰胆碱、谷氨酸和五羟色胺的受体，和阴离子通道，如甘氨酸和,氨基丁酸的受体。,细胞生物学,细胞信号转导,G,蛋白耦联型受体,三聚体,GTP,结合调节蛋白（,trimeric GTP-binding regulatory protein,）简称,G,蛋白，位于质膜胞质侧，由,、,、,三个亚基组成，,和,亚基通过共价结合的脂肪酸链尾结合在膜上，,G,蛋白在信号转导过程中起着分子开关的作用，当,亚基与,GDP,结合时处于关闭状态，与,GTP,结合时处于开启状态，,亚基具有,GTP,酶活性，能催化所结合的,ATP,水解，恢复无活性的三聚体状态，其,GTP,酶的活性能被,RGS,（,regulator of G protein signaling,）增强。,RGS,也属于,GAP,（,GTPase activating protein,）。,细胞生物学,细胞信号转导,G,Effector,Signal,细胞生物学,细胞信号转导,Extracellular,Cytoplasmic,COOH,-,-NH2,i1,i2,i3,e1,e2,e3,TM1,TM2,TM3,TM4,TM5,TM6,TM7,-S-S-,Binding of ligands,Location of G,细胞生物学,细胞信号转导,4 superfamilies,binds GTP,Three subunits,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,cAMP,信号通路,cAMP,信号通路的组成：,膜刺激型受体（,stimulatary receptor,，,Rs,）；,抑制型受体（,inhibitory receptor,，,Ri,）；,刺激型调节蛋白（,sitimulatary regulatory protein,，,Gs,）；,抑制型调节蛋白（,inhibitory regulatory protein,，,Gi,）；,腺苷酸环化酶（adenylate cyclase,，,AC,）；,蛋白激酶,A,（,protein Kinase A,，,PKA,）；,环腺苷酸磷酸二酯酶（,cAMP phosphodieste-rase,）。,细胞生物学,细胞信号转导,腺苷酸环化酶,细胞生物学,细胞信号转导,蛋白激酶,A,细胞生物学,细胞信号转导,环腺苷酸磷酸二酯酶,细胞生物学,细胞信号转导,cAMP,信号通路的传递过程,Gs,调节模型,配体（信号分子）受体,G,蛋白环化酶,cAMP,（第二信使）蛋白激酶,A,（,protein kinase A,PKA,）基因调控蛋白基因转录。,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,Effects of PKA,Ser/Thr,残基磷酸化,（,1,）对代谢的调节作用,肾上腺素调节糖原分解,（,2,）对基因表达的调节作用,cAMP,应答元件（,CRE,）基因调控区,cAMP,应答元件结合蛋白（,CREB,）反式作用因子,PKA,的催化亚基进入细胞后使,CERB,特定的,Ser/Thr,磷酸化，形成同源二聚体，结合,DNA,，,激活转录,细胞生物学,细胞信号转导,cAMP,信号通路的传递过程,Gi,调节模型,细胞生物学,细胞信号转导,磷脂酰肌醇信号通路,胞外信号分子与细胞表面,G,蛋白耦联型受体结合，激活质膜上的,磷脂酶,C,（PLC-,），使质膜上,4,，,5-,二磷酸磷脂酰肌醇（,PIP,2,）水解成,1,，,4,，,5-,三磷酸肌醇,（,IP,3,）和,二酰基甘油,（,DG,）两个第二信使，胞外信号转换为胞内信号。,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,G,i/o,G,s,G,q,G,12/13,inhibition of cAMP production,inhibition of Ca,2+,channels,activation of GIRK K,+,channels,G-protein subtypes,increased synthesis of cAMP,activation of Ca,2+,and K,+,channels,activation of PLC,leading to,activation of PKC(DAG),intracellular Ca,2+,release(IP,3,),mediates signalling between GPCRs and RhoA(GTPase),function under investigation,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,Small GTP-binding proteins include,Ras,(growth factor signal cascades).,Rho,(regulation of actin cytoskeleton),Rab,(vesicle targeting and fusion).,ARF,(forming vesicle coatomer coats).,Ran,(transport of proteins into&out of the nucleus).,All GTP-binding proteins differ in conformation depending on whether GDP or GTP is present at their nucleotide binding site.,Generally,GTP,binding induces the,active,state.,细胞生物学,细胞信号转导,Most GTP-binding proteins depend on,helper proteins,GAPs,G,TPase,A,ctivating,P,roteins,promote GTP hydrolysis.,细胞生物学,细胞信号转导,GEFs,G,uanine,N,ucleotide,E,xchange Factors,promote GDP/GTP exchange.,The activated receptor(,GPCR,)serves as,GEF,for a heterotrimeric G protein.,细胞生物学,细胞信号转导,鸟苷酸环化酶（,GC,）,GC,的激活间接地依靠,Ca2+,效应蛋白磷酸化,NO,作用机理：肌肉细胞中激活,GC,蛋白激酶,G,H,R,GC,GTP,cGMP,cGMP-,依赖性蛋白激酶,蛋白激酶,G,（一个,cGMP,结合位点）,cGMP-蛋白激酶途径,细胞生物学,细胞信号转导,Cyclic Nucleotide Metabolism-cGMP,细胞生物学,细胞信号转导,酶偶联受体及其介导的信号转导通路,酶偶联受体的一般特征 酶偶联受体（,enzyme-linked receptor,），又称催化性受体（,catalytic receptor,）。是一大类重要的膜受体家族。其共同的特点是：,该类受体均为一次跨膜肽链，,胞外区,是配体结合位点；,胞内区,是蛋白激酶催化部位。,无需,G,蛋白的介导作用，仅由受体,自身酶蛋白的激活,来直接完成信号的跨膜转导。,受体的,二聚化,（,dimerization,）是该类受体激活的普遍机制。细胞生物学,细胞信号转导,类型,受体酪氨酸激酶,酪氨酸激酶连接的受体,受体酪氨酸磷脂酶,受体丝氨酸,/,苏氨酸激酶,受体鸟苷酸环化酶,组氨酸激酶连接的受体,细胞生物学,细胞信号转导,酪氨酸激酶,THANK YOU,SUCCESS,2025/3/19 周三,45,可编辑,细胞生物学,细胞信号转导,信号转导过程,配体（主要是各种生长因子）与受体结合；,受体胞外区构象变化，聚合成二聚体；,受体胞内区酪氨酸残基自磷酸化（受体激活）；,活化的受体结合，并与胞质中带有蛋白,SH,（,Src homolog region,）或,PH,结构域（,Pleckstrin Homology,）的信号转导分子结合，形成受体胞内信号蛋白复合体；,传递信号并引发细胞相应的生物效应。,细胞生物学,细胞信号转导,SH2,结构域,（,Src Homology 2,结构域）：约,100,个氨基酸组成，介导信号分子与含磷酸酪氨酸的蛋白分子结合。,SH3,结构域,（,Src Homology 3,结构域）：约,50-100,个氨基酸组成，介导信号分子与富含脯氨酸的蛋白分子结合。,PH,结构域,（,Pleckstrin Homology,结构域）：约,100-120,个氨基酸组成，可以与膜上磷脂类分子,PIP,2,、,PIP,3,、,IP,3,等结合，使含,PH,结构域蛋白由细胞质中转位到细胞膜上。,Ligand binds receptor PTK,Ligand binds receptor PTK,Autophosphorylation on tyrosine,P,P,P,P,Ligand binds receptor PTK,Autophosphorylation on tyrosine,GRB2,(a SH2-and SH3-containing protein)binds to the receptor phosphotyrosine motif Y-V/L-N-X via its SH2 domain,P,P,P,P,SH2,SH3,GRB2,SOS,Ligand binds receptor PTK,Autophosphorylation on tyrosine,GRB2,(a SH2-and SH3-containing protein)binds to the receptor phosphotyrosine motif Y-V/L-N-X via its SH2 domain,The SH3 of GRB2 binds constitutively to the proline-rich sequence in the C-terminus of,SOS,(a guanine nucleotide exchange factor for RAS).,P,P,P,P,SH2,SH3,GRB2,SOS,P,P,P,P,SH2,SH3,GRB2,SOS,GRB2,24 kDa adaptor molecule.,Only contains an SH2 domain between two SH3 domains,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAS,Oncogenic forms of RAS often have point mutations that lock RAS in the active GTP-bound form.,Evidence:,C,ells were induced to proliferate by+PDGF and EGF.Microinjection of anti-RAS antibodies into the cells blocked the cell proliferation.Microinjection of a constitutively active mutant of RAS caused cells to proliferate in the absence of PDGF and EGF.,The RAS-GTP effector domain interacts with the N-terminal regulatory region of the,RAF,(serine/threonine protein kinase),hence recruiting RAF to the membrane,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,RAF,RAF is a serine/threonine protein kinase,RAF is a MAPK kinase kinase(MAPKKK).,Can transform cells when constitutively active or when overexpressed.,14-3-3P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,RAF,The 14-3-3 family of scaffold proteins interacts constitutively with RAF via the phosphorylated Ser621 in RAF,B,oth 14-3-3 and RAS may be required for activation of RAF.,14-3-3,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,RAF,RAS recruits RAF to the membrane.Membrane targeting of RAF is necessary to fully activate RAF.,(Expression of mutant RAF that cannot bind RAS,no stimulation of cell proliferation by a constitutively active RAS).,14-3-3,Activation of,RAF,(most likely by phosphorylation of RAF and binding to the scaffold protein 14-3-3),P,P,P,P,SH2,SH3,GRB2SOS,RAS,GTP,RAF,14-3-3,Activated RAF in turn activates,MEK,(also called MAPK kinase)by phosphorylation on two conserved serine residues in MEK.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,14-3-3,Activated RAF in turn activates,MEK,(also called MAPK kinase)by phosphorylation on two conserved serine residues in MEK.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,14-3-3,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MEK,Also called MAPK kinase(MAPKK).,Phosphorylated on Ser218 and Ser222 by activated RAF.,Mutation of MEK that leads to constitutive activity(by replacing the two Ser with glutamic acids or aspartic acids-by mimic phosphorylation),MAPK activation,mitogenicity,and cellular transformation.,14-3-3,Activated MEK activates,MAPK,(a serine/threonine protein kinase)by phosphorylation of conserved threonine and tyrosine residues.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MAPK,P,P,14-3-3Activated MEK activates,MAPK,(a serine/threonine protein kinase)by phosphorylation of conserved threonine and tyrosine residues.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MAPK,P,P,14-3-3,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MAPK,P,P,MAPK,Five isoforms of ERK have been identified,but ERK1 and ERK2 have been most studied.,14-3-3,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MAPK,P,P,MAPK,MAPK activation is biphasic:a transient peak within 5-10 min,and a sustained peak lasting several hours.The different activation kinetics,different cellular response,(EGF induces only the transient response and stimulate cell growth;but NGF(nerve growth factor)induces the sustained response and stimulate differentiation).,14-3-3,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MAPK,P,P,MAPK,Inactivation of MAPK is achieved by several,phosphatases,:the serine/threonine phosphatase PP2A,14-3-3,Activated MAPK,phosphorylates a number of substrates,in the,cytoplasm,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,MAPK,P,P,Substrates,Substrates,P,P,14-3-3,Activated MAPK,phosphorylates a number of substrates,in the cytoplasm,it also translocated into the nucleus(within min)where it phosphorylates nuclear transcription factors.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,Substrates,MAPK,P,P,MAPK,P,P,14-3-3,Activated MAPK,phosphorylates a number of substrates,in the cytoplasm,it also translocated into the nucleus(within min)where it phosphorylates nuclear transcription factors.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,Substrates,MAPK,P,P,MAPK,P,P,14-3-3,Activated MAPK,phosphorylates a number of substrates,in the cytoplasm,it also translocated into the nucleus(within min)where it phosphorylates nuclear transcription factors.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,Substrates,MAPK,P,P,MAPK,P,P,P,14-3-3,Activated MAPK,phosphorylates a number of substrates,in the cytoplasm,it also translocated into the nucleus(within minutes)where it phosphorylates nuclear transcription factors.,Transcription of genes important for cell proliferation.,P,P,P,P,SH2,SH3,GRB2,SOS,RAS,GTP,RAF,MEK,P,P,Substrates,MAPK,P,P,MAPK,P,P,P,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,Transcription Factor Regulation(CREB,Elk-1 and c-Fos),The transcription factor,CREB,binds to the,cAMP response element(CRE),and activates gene transcription in response to a wide variety of extracellular signals(including,growth factors,hormones,and neurotransmitters,).Transcriptional activation of,CREB,is controlled through phosphorylation at Ser,133,by,p90,Rsk,and the p44/42 MAP kinase,.The transcriptional activity of the proto-oncogene,c-Fos,has been implicated in cell growth,differentiation,and development.,Fos,is induced by many stimuli,ranging from mitogens to pharmacological agents.,c-Fos,has been shown to be associated with another proto-oncogene,c-Jun,and together they bind to the,AP-1,binding site to regulate gene transcription.Like CREB,c-Fos is regulated by p90,Rsk,.,Elk-1,is a transcription factor that is activated by theMAP kinase-mediated,phosphorylation of a Ser/Thr cluster at the carboxyl terminus.Activated,Elk-1,binds to the,serum response element,(SRE)to induce gene transcription in response to serum and growth factors.Recent studies have also demonstrated that Elk-1 is a target for the stress-activated kinase SAPK/JNK.,细胞生物学,细胞信号转导,JNK pathway,JNK,translocation into the nucleus,phosphorylation of the transcription factor,c-JUN,at the N-terminal residues(Ser63 and Ser73),activation of transcription by c-JUN,Rac1/Cdc42,GTP,STRESS,PAK,MEKK1-3,P,P,MEK4,P,P,JNK,P,P,c-JUN,P,Rac1/Cdc42,GTP,STRESS,PAK,MEKK1-3,P,P,14-3-3,P,P,P,P,SH2,SH3,Grb2,Sos,Ras,GTP,Raf,MEK4,P,P,MEK,P,P,JNK,P,P,MAPK,P,P,细胞生物学,细胞信号转导,Specificity of MAP kinase pathways,When cells are treated with mitogenic agents(e.g.growth factors),MAPK(ERK)become strongly activated but JNK is poorly activated.,Conversely,when cells are challenged with stress,JNK is activated but MAPK(ERK)is only weakly activated.,细胞生物学,细胞信号转导,JAK,(just another kinase,Janus protein tyrosine kinase)-,STAT,(signal transducer and activator of transcription),GF,、,IFN,、,EPO,、,G-CSF,、,IL-2,、,IL-6,其受体分子缺乏酪氨酸蛋白激酶活性，借助细胞内的一类具有激酶结构的连接蛋白,JAKs,完成信息转导,配体与非催化型受体结合后，能活化各自的,JAKs再通过激活信号转导子和转录激动子（,STAT,）而影响基因的转录调节,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,Nuclear Receptor Superfamily,信息分子：糖皮质激素、盐皮质激素、雄激素、孕激素、,雌激素、甲状腺素、,1,，,25-(OH)2-D3,核内受体：雄激素、孕激素、雌激素、甲状腺素,胞浆受体：糖皮质激素,细胞生物学,细胞信号转导,细胞内受体的本质是激素激活的基因调控蛋白。,细胞内受体与抑制性蛋白（如,Hsp90,）结合形成复合物，处于非活化状态。配体（如皮质醇）与受体结合，导致抑制性蛋白从复合物上解离下来，从而受体通过暴露它的,DNA,结合位点而被激活。,受体结合的,DNA,序列是受体依赖的转录增强子。,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,甾类激素,甾类激素分子相对质量为,300Da,左右，这类激素通常表现为影响细胞分化等长期的生物学效应。,甾类激素诱导的基因活化分为两个阶段：,直接活化少数基因转录的初级反应阶段，发生迅速。,初级反应的基因产物再活化其他基因，产生延迟的次级反应，对初级反应起放大作用。,个别的亲脂性小分子，如前列腺素，其受体在细胞膜上。,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,NO,NO,可快速扩散透过细胞膜，作用于邻近细胞。,血管内皮细胞和神经细胞是,NO,的生成细胞，,NO,的生成由一氧化氮合酶（,nitric oxide synthase,，,NOS,）催化，以,L,精氨酸为底物，以,NADPH,作为电子供体，生成,NO,和,L,瓜氨酸。,NO,没有专门的储存及释放调节机制，靶细胞上,NO,的多少直接与,NO,的合成有关。,NO,的作用机理：,乙酰胆碱血管内皮,Ca,2+,浓度升高一氧化氮合酶,NO,平滑肌细胞鸟苷酸环化酶,cGMP,血管平滑肌细胞的,Ca,2+,离子浓度下降平滑肌舒张血管扩张、血流通畅。,硝酸甘油治疗心绞痛具有百年的历史，其作用机理是在体内转化为,NO,，可舒张血管，减轻心脏负荷和心肌的需氧量。,细胞生物学,细胞信号转导,细胞生物学,细胞信号转导,Guanylate cyclase,THANK YOU,SUCCESS,2025/3/19 周三,89,可编辑,