分子生物學英文版課件：The signal transduction of extracellular information

ThesignaltransductionofextracellularinformationInallmulticellularorganisms,survivaldependsonanintercellularcommunicationnetworkthatcoordinatesthegrowth,differentiationandmetabolismofcellsindiversetissuesandorgans.SectionISignalmoleculesIntercellularsignalingmoleculesIntracellularsignalingmoleculesIIntercellularsignalingmolecules

Basedonthechemicalnature:–proteinsandpeptides(growthfactor,insulin)–aminoacidsandaminoacidderivatives(thyroxine,甲狀腺素)–derivativesoffattyacids(prostaglandin,前列腺素)–steroids(sexhormone）

–smallinorganicmolecules,nitricoxide(NO),monoxidecarbon(CO)

Basedontheactionmanner:1.Neurotransmitter(acetylcholine,norepinephrine)2.Endocrinesignals(hormone:insulin,glucagon,thyroxin,epinephrine,sexhormone)3.Localchemicalmessengersorparacrinesignals(growthfactor,prostaglandin)4.Autocrinesignal:oncoproteinEndocrinesignals–Signalsexerttheireffectsbybindingtoacell-surfacereceptorandinitiatingacascadeofsignalingevents.–Signalsthatgointothecell,bindtointernalreceptors,andexerttheireffects.Steroidhormones,vitaminD,thyroxinAlloftheintracellularreceptorsultimatelyactivatethetranscriptionofregulatedgenes.ReceptorsonmembraneReceptorsincytosolIIIntracellularsignalingmoleculesSmallmoleculeInorganicion(Ca2+)Lipids(diacylglycerol,DAG)Inositoltriphosphate(IP3)Nucleotide(cAMP,cGMP)Protein(Ras)Substrateenzymes(Jak)Transcriptionfactors

SecondarymessengerSmallsignalingmoleculesthataregeneratedinthecellinresponsetoextracellularsignals.Theycanactivatemanyotherdownstreamcomponents.Themostimportantsecondmessengersare:Ca2+,cAMP,cGMP,DAG,IP3,etc.Effectsofsignals:regulateenzymeactivity.open/closeionchannelinthecellmembrane.regulategenetranscriptionwhichultimatelycontrolscellmetabolism,growth,developmentanddifferentiation,etc.

SectionIIReceptorsProteins(orglycoproteins,glycolipoproteins)OnthemembraneorinsidethecellMembranereceptorIntracellularreceptorRecognizeandbindtoaspecificextracellularsignalmolecule(ligand)Receptor-ligandinducesacellularresponse1.Ion-channelreceptorsLigand:neurotransmitterAchreceptorIMembranereceptors

2.G-Proteincoupledreceptors

(GPCRs)Thelargestclassofcellsurfacereceptorsligand:hormonesandneurotransmitterInvolvedinvision,taste,olfaction,metabolism,transcription,cellproliferationSinglepolypeptidechain,glycoproteins

Gprotein,guanosinenucleotide-bindingprotein

G-proteinsareafamilyofGTP-bindingproteinsamembrane-associatedproteinconsistofα,β,andγsubunitstheαsubunitoftheG-proteinbindsGTPorGDP,GTPaseactivity.theβγ

subunitsareaninseparablepairthatbindstotheαsubunitwhenGDPispresent.WhentheαsubunithasGTPbound,theβγ-subunitleave.Gproteinactivation.ActivateAC,PLC(PhospholipaseC)

andinducebio-effects.GproteinfunctionGs(ubiquitous)Adenylcyclase↑Ca2+channels↑Gi(ubiquitous)Adenylcyclase↓Ca2+channels↓Gq(ubiquitous)PhospholipaseC↑Go(brain)Ca2+channels↓K+channels↑GT(transducin,轉(zhuǎn)導素)(retina,視網(wǎng)膜)cGMPspecificphosphodiesterase↑ClassificationofGproteinsaccordingtotheα

subunitsSignaltransductionmediatebyG-proteincoupledreceptors

Hormone→Receptor→Gprotein→Enzyme→Secondmessenger→Proteinkinase→Effectors→Response(metabolism,geneexpression)G-ProteinEffectors

Includeenzymes(adenylatecyclase,phospholipase,phosphodiesterase,kinase)andionchannels.TransmembranereceptorspossessintrinsictyrosinekinaseactivityOuterside--ligandbindingdomainLigand:insulin,EGF,NGF,FGF

(fibroblastgrowthfactor,成纖維細胞生長因子)Innerside--proteinkinasedomainProteinkinasedomainactingonspecificTyrresidues.3ReceptorswithIntrinsicTyrosineKinaseActivity

Proteintyrosinekinase,PTK

Ligandsbindingtotheligand-bindingdomainarecoupledwithstimulationoftyrosinekinaseactivitybyphosphorylatingtyrlocalizedonitsowncytoplasmicreceptordomain.SH2:bindtophosphorylatedtyrosineinaparticularpeptidesequenceonactivatedreceptorsorintracellularsignalingproteinsSH3:bindtoaparticularpeptidesequenceprolineinrichPH:bindtophosphorylatedserineandthreonineinashortpeptidesequence4TransmembraneReceptorswithAssociated

TyrosineKinaseActivity(Tyrosinekinase–linkedreceptors)--lackintrinsiccatalyticactivity--ligandbindingstimulatesformationofadimericreceptorthatinteractswithandactivatesoneormorecytosolictyrosineproteinkinases--thereceptorsofcytokines,interferons,andhumangrowthhormoneareofthistype

IIIntracellularreceptorsIntracellularreceptorsarereceptorslocatedinsidethecell.Examplesaretheclassofnuclearreceptors

locatedinthecellnucleusandcytoplasmandtheIP3receptor

locatedontheendoplasmicreticulum.Theligandsthatbindtothemareusuallyintracellularsecondmessengerslikeinositoltrisphosphate

(IP3)andextracellularlipophilichormones

likesteroidhormones.Someintracrine(胞內(nèi)分泌)peptidehormonesalsohaveintracellularreceptors.SectionIIISignalTransductionPathways

Cell-surfacereceptorsmediatedsignaltransduction―cAMP-PKApathway―Ca2+-dependentPKpathway―cGMP-PKGpathway―TyrPKpathway―Nuclearfactor-κBpathway―TGF-βpathwayIntracellularreceptorpathway

IcAMP-PKApathwayGlucagons,epinephrine,corticotropin(促腎上腺皮質(zhì)激素),etc.Function:metabolism,transcription,taste,olfaction

1.cAMP:—cAMPisasecondmessengerintheactionofmanyhormones—cAMPissynthesizedbyadenylatecyclaseanddegradedbyphosphodiesterase.2.PKA(proteinkinaseA)

Aheterotetramericmolecule2regulatorysubunits(R),2catalyticsubunits(C)

R2C2isinactiveformcAMPbindingtoRsubunitscausesdissociationofC

subunitsC2isactiveformwhichcanphosphorylatespecificsubstrateproteins(Ser/Thr).ActivationofPKA

FunctionofPKA—RegulatingmetabolismRegulatingmetabolismofglycogen—RegulationofgeneexpressioncAMPresponseelementbindingprotein(CREB)andcAMPresponseelement(CRE)C2phosphorylates

Ser/ThrofCREB,CREB-CREBcanbindCREinDNA—OthersHistone,acidicprotein,ribosomalprotein，membraneprotein,microtubulin,receptor,etcPKAregulatesgenetranscriptionCREBbindingprotein，CBP轉(zhuǎn)錄輔激活子transcriptionalcoactivator

IICa2+-dependent

proteinkinasepathwayCa2+(calciumion)isanimportantregulatorofavarietyofcellularprocesses?Ca2+-phospholipidsdependentproteinkinasepathway?Ca2+-calmodulin(CaM)dependentpathway

1.Ca2+/PL-dependentproteinkinasepathway

angiotensinII(血管緊張素),Norepinephrine,antidiuretichormone(抗利尿激素,ADH),etc.

Hormone→receptor→Gprotein(Gq)→PI-PLCMembranePIP2DAG+IP3

SecondmessengerPI–PLC:

phosphatidylinositolspecificphospholipaseC

磷脂酰肌醇特異性磷脂酶Cphosphatidylinositolbiphosphate磷脂酰肌醇-4,5-二磷酸IP3→bindswithIP3receptor(Ca2+channel)inthemembraneofendoplasmicreticulum(ER)andsarcoplasmicreticulum(SR,肌漿網(wǎng)

)→stored

Ca2+released.DAG→remainsassociatedwiththemembrane,canactivatePKCinthepresenceofphosphatidylserine(PS)andCa2+.

FunctionsofPKCRegulatesthemetabolismsandfunctionsinvariouscelltypesbyphosphorylatingspecificSer/Thrresiduesonreceptors,ionchannelsandenzymes.Regulatesgenetranscriptionbyphosphorylatingtrans-actingfactorsInvolvedincelldifferentiation,proliferation,secretion,musclecontraction.Immediate-earlygene,立早基因lateresponsegenes,延遲反應基因PKC對基因的早期活化和晚期活化2.Ca2+-calmodulin(CaM)pathwayCalmodulin(鈣調(diào)蛋白)isasmallcytosolprotein,singlepolypeptide1CaMbinds4Ca2+ions,bindingofCa2+causesCaMtoundergoaconformationalchange

Ca2+-CaMregulatestheCa2+-CaMdependentPKactivityCa2+-CaM-PKphosphorylatesSer/ThrresiduesofmanyproteinsActivatingadenylatecyclaseandphosphodiesteraseinPKAactivationandinhibitionActivatingPTKofinsulinreceptorsActivatingmanykeyenzymesCalmodulin,themediatorofmanyCa2+-stimulatedenzymaticreactions,containsfourhigh-affinityCa2+-bindingsites.

IIIcGMP-PKGpathwaycGMPinducedbyANPandnitricoxideLikecAMP,GTP→cGMP→GMPPeptidehormones,NO→guanylatecyclase(GC)→cGMP→PKG→Ser/Thrphosphorylation→biologicalresponseANP,atrialnatriureticpeptide,心房利鈉肽GuanylylcyclasesareafamilyofenzymesthatcatalyzetheconversionofGTPtocGMP.Thefamilycomprisesbothmembrane-boundandsolubleisoformsthatareexpressedinnearlyallcelltypes.PKGPKGisasinglepolypeptide,1PKGbinds1cGMPcGMP-dependentproteinkinase(PKG)phopshorylatesspecificproteinsonserineorthreonine.smoothmusclerelaxation,plateletfunction,spermmetabolism,celldivision,andnucleicacidsynthesis.

精氨酸瓜氨酸一氧化氮合酶NitricoxidesynthaseIVRas-MAPKpathwayEGF→Receptordimerizationandautophosphorylation→GRB-2-SOS→Ras→Raf(MAPKKK)→MAPKK→MAPK→targetprotein→responseGRB-2--growthfactorreceptorboundprotein2,adaptorprotein,SH2andSH3domainSOS--guaninenucleotideexchangefactor,SH2andSH3domainActivationofRasfollowingbindingofahormone(e.g.EGF)Rasprotein1polypeptide,codingbyrasgene,21kD(P21proteinorsmallGprotein)GTP-bindingmembraneprotein,functioningasGαofGprotein,alternatesbetweenanactiveonstatewithaboundGTPandaninactiveoffstatewithaboundGDP.Ithasimportantfunctionincellsignaltransduction,andmutantRasplaysaroleintumorigenesis.Rafkinases(MAPKKK)areafamilyofthreeserine/threonine-specificproteinkinases.ThethreeRAFkinasefamilymembersare:A-Raf,B-Raf,C-Raf(Raf-1).RafkinasesparticipateintheRAS-RAF-MEK-ERKsignaltransductioncascade,alsoreferredtoasthemitogen(有絲分裂原)-activatedproteinkinase(MAPK)cascade.ActivationofRAFkinasesrequiresinteractionwithRAS-GTPases.Mitogen-activatedproteinkinasekinase(alsoknownasMAP2K,MEK,MAPKK,絲裂原活化蛋白激酶激酶)isakinasewhichphosphorylatesmitogen-activatedproteinkinase(MAPK,).MAPKK是一種具雙重特異的蛋白激酶，它能磷酸化MAPK的蘇氨酸和酪氨酸殘基使之激活。Mitogen-activatedproteinkinasesalsoknownasMAPkinasesareserine/threonine/tyrosine-specificproteinkinases.

MAPKsregulateproliferation,geneexpression,differentiation,mitosis,cellsurvival,andapoptosis.VJAKs-STATpathwayLigand:cytokines,growthhormone,interferons,interleukin(IL),etc.Pathway:receptor→JAK(januskinase)→STAT(signaltransducerandactivatoroftranscription)→regulatingtargetgeneJAKs

tyrosinekinases

activateSTAT

JAKkinasefamily:JAK1,2,3,andTyk2STAT:agroupofDNAbindingproteinsJAK將STAT磷酸化，使其產(chǎn)生SH2結合位點，磷酸化的STAT分子彼此間通過SH2結合位點和SH2結構域結合而二聚化。NF-κB(nuclearfactorkappaB)isaproteincomplexthatcontrolsthetranscriptionofDNA.NF-κBisinvolvedincellularresponsestostimulisuchasstress,cytokines,freeradicals,ultravioletirradiation,oxidizedLDL,andbacterialorviralantigens.NF-κBplaysakeyroleinregulatingtheimmuneresponsetoinfection.IncorrectregulationofNF-κBhasbeenlinkedtocancer,inflammatoryandautoimmunediseases,viralinfection,andimproperimmunedevelopment.VINF-κBpathwayIκB，inhibitorofNF-κB,NF-κB抑制蛋白IκB激酶MAPKpat