信号通路和肿瘤

细胞信号转导与肿瘤——中山大学2005级《分子医学》博士生课程第四讲2005年9月27日黎孟枫医学博士中山大学基础医学院微生物学教研室[e-mail]•引言：细胞信号转导与生命过程——问题的提出和理论的产生•细胞信号转导理论概述•信号转导研究中的重大理论问题及热点领域•信号转导的研究方法与工具•信号转导理论研究及应用举例：在肿瘤发生发展中的信号转导的意义•信号转导与肿瘤临床：诊断和治疗•细胞信号转导经典文献举例引言信号转导与生命过程——问题的提出和理论的产生细胞信号转导理论建立以前的细胞生物学•细胞的显微结构（胞膜、胞浆、胞核）•细胞的生理功能（生存、“活性”、分裂增殖、胞间连接、吞饮、分泌、迁移、死亡……)•细胞组分的生物化学（脂、糖、核酸、蛋白）•细胞的超微结构和亚细胞结构（脂质双层膜结构、细胞器……)组织生长需要细胞分裂增殖细胞生长因子病原体侵入抗感染状态细胞抗原细胞过度生长细胞死亡细胞死亡因子细胞骨架蛋白表达、激活牵动细胞移动(Cellmovement)趋化因子细胞粘附细胞存活(Survival)抗凋亡因子表达、激活胞外信号信号作用于细胞基因表达改变细胞表型改变细胞信号转导理论概述胞外信号分子(可溶性分子、细胞表面分子、组织基质分子)靶细胞跨膜分子(狭义受体如EGFR或广义受体如Integrin)靶细胞受体（胞内段）化学变化（如磷酸化、二聚体形成）靶细胞内信号转导分子化学变化与激活（如磷酸化、去磷酸化、聚体形成）激活的信号转导分子进入胞核进入胞核的转导分子作用于基因转录调控区基因表达改变ExtracellularSignalMolecules1.GrowthFactorsPDGF(Platelet-DerivedGrowthFactor),EGF(EpidermalGrowthFactor),TGF-(TransformingGrowthFactor-),EPO(Erythropoietin),NGF(NerveGrowthFactor),IGF(Insulin-likeGrowthFactor),TPO(Thrombopoietin)2.CytokinesIFN-(Interferon-),IFN-(Interferon-),TNF(TumorNecrosisFactor),Interleukins(1,2,3,4…)3.DeathmoleculesFas4.AdhesionmoleculesCadherins,Adhesin…5.HormoneInsulin6.StressSignalTransducingReceptors1.Transmembranereceptorsthathaveintrinsicenzymaticactivity.——Autophosphorylation——PhosphorylationofothersubstratesA)Tyrosinekinases:PDGF-R,insulin-R,EGFRandFGF-RB)Tyrosinephosphatases:e.g.CD45C)Guanylatecyclases:e.g.natriureticpeptidereceptors)D)Serine/Threoninekinases:activinandTGF-receptors2.Receptorsthatarecoupled,insidethecell,toGTP-bindingandhydrolyzingproteins(G-proteins).e.g.,adrenergicreceptors,odorantreceptors,andcertainhormonereceptors(e.g.glucagon,angiotensin,vasopressinandbradykinin).3.Receptorsthatarefoundintracellularlyanduponligandbindingmigratetothenucleuswheretheligand-receptorcomplexdirectlyaffectsgenetranscriptione.g.,STAT1,3,4,5,6…(Signaltransducerandactivatoroftranscription)4.Simplereceptors:e.g.,ion-channelsthatleadtochangesinmembraneelectricpotential信号转导过程中的生物化学•磷酸化反应（酪氨酸激酶、丝/苏氨酸激酶）蛋白质构象改变•去磷酸化反应（磷酸酶）•受体或其他信号转导分子的聚体化SignalTransducers•ReceptorTyrosineKinases(RTKs)contains:•Anextracellularligandbindingdomain.•Anintracellulartyrosinekinasedomain.•Anintracellularregulatorydomain.•Atransmembranedomain.TyrosinephosphorylationInteractwithandphosphorylateSrchomologydomain2(SH2)-containingproteins(e.g.,PLC-,Ras,PI-3K,etc)Phosphorylateotherkinasesphosphorylateproteins,whichuponphosphorylated,canenterthenuclearandbindDNAregulatoryregions.ClassExamplesStructuralFeaturesofClassIEGFreceptor,NEU/HER2,HER3cysteine-richsequencesIIinsulinreceptor,IGF-1receptorcysteine-richsequences;characterizedbydisulfide-linkedheterotetramersIIIPDGFreceptors,c-Kitcontain5immunoglobulin-likedomains;containthekinaseinsertIVFGFreceptorscontain3immunoglobulin-likedomainsaswellasthekinaseinsert;acidicdomainVvascularendothelialgrowthfactor(VEGF)receptorcontain7immunoglobulin-likedomainsaswellasthekinaseinsertdomainVIhepatocytegrowthfactor(HGF)andscatterfactor(SC)receptorsheterodimericliketheclassIIreceptorsexceptthatoneofthetwoproteinsubunitsiscompletelyextracellular.TheHGFreceptorisaproto-oncogenethatwasoriginallyidentifiedastheMetoncogeneVIIneurotrophinreceptorfamily(trkA,trkB,trkC)andNGFreceptorcontainnoorfewcysteine-richdomains;NGFRhasleucinerichdomainCharacteristicsoftheCommonClassesofRTKsNon-ReceptorProteinTyrosineKinases(PTKs)Twonon-receptorPTKfamilies:1)ThearchetypaplPTKfamilty:Src-relatedproteins2)Januskinase(Jak)familyMostnon-receptorPTKscoupletocellularreceptorsthatlackenzymaticactivitythemselves(e.g.,CD4,CD8,TCRandallcytokinereceptorssuchasIL-2RReceptorSerine/ThreonineKinases(RSTKs)•Typicalexample:ReceptorsfortheTGF-superfamilyofligands•TheTGF-superfamilyinclude30multifunctionalproteins,e.g.,activins,inhibinsandthebonemorphogeneticproteins(BMPs).•17RSTKsisolatedarein2subfamilies:typeIandtypeIIreceptors.•NuclearproteinsrespondingtoTGF-activationincludec-MycandSmadLigandsbindtothetypeIIreceptorsComplexedwithtypeIreceptorsTypeIIRphosphorylatestypeIreceptorInitiationofsignalingcascade•Non-ReceptorSerine/ThreonineKinases1)cAMP-dependentproteinkinase(PKA)2)ProteinkinaseC(PKC)3)Mitogenactivatedproteinkinases(MAPKorERK)(requiringphosphorylationofbothtyrosineandthreonine)•G-ProteinCoupledReceptors1.1000GPCRs,mostofwhichareorphanreceptors)2.ThreedifferentclassesofGPCR:1)GPCRsthatmodulateadenylatecyclaseactivityandproducecAMP2)GPCRsthatactivatePLC-gleadingtohydrolysisofpolyphosphoinositides:angiotensin,bradykininandvasopressinreceptors.3)Photoreceptor•IntracellularHormoneReceptors1.Residingwithinthecytoplasm.2.Thesteroid/thyroidhormonereceptorsuperfamily(e.g.glucocorticoid,vitaminD,retinoicacidandthyroidhormonereceptors):bindsteroid/thyroidhormone,translocatetonuclearandbindspecificDNAsequenceshormoneresponseelements(HREs).•*PhosphatasesinSignalTransduction1.TransmembranePTPs:e.g.,CD45.2.IntracellularPTPs.胞外信号分子(可溶性分子、细胞表面分子、组织基质分子)靶细胞跨膜分子(狭义受体如EGFR或广义受体如Integrin)靶细胞受体（胞内段）化学变化（如磷酸化、二聚体形成）靶细胞内信号转导分子化学变化与激活（如磷酸化、去磷酸化、聚体形成）激活的信号转导分子进入胞核进入胞核的转导分子作用于基因转录调控区基因表达改变信号转导研究中的重大理论问题及热点领域信号转导通路的调控•磷酸化—去磷酸化调控•信号转导分子消长的调控（分子半衰期）•不同通路之间的效应调控