DNAsensorinvirusinfection脱氧核糖核酸识别受体及病毒感染文档格式.docx
《DNAsensorinvirusinfection脱氧核糖核酸识别受体及病毒感染文档格式.docx》由会员分享,可在线阅读,更多相关《DNAsensorinvirusinfection脱氧核糖核酸识别受体及病毒感染文档格式.docx(32页珍藏版)》请在冰点文库上搜索。
Inordertoprotecthostfrominfectionofvirus,innateimmunehasdevelopedmechanismsofhowtodetectvirustotriggerimmuneresponse.Recently,DNAsensorhasbeenfoundasanoveltooltodetectvirus.Toll-likereceptor(TLR)9,retinoicacid-induciblegeneI(RIG-I)-likereceptors(RLRs)includingRIG-I,melanomadifferentiation-associatedgene-5(MDA5),DNA-dependentRNApolymeraseIII(Pol-III),DNAbindingprotein1(ZBP1)orDNA-dependentactivatorofIFN-regulatoryfactor(DAI),IFN-induciblep200-proteinincludingp202,absentinmelanoma2(AIM2),interferon-inducibleprotein16(IFI16)havebeenidentifiedasDNAsensor[1-5].What’smore,DExDchelicaseDDX41,DHX36andDHX9,Leucine-richrepeatflightless-interactingprotein1(LRRFIP1),Ku70wererecentlyfoundtobenovelDNAsensors[6-9].Table1showsDNAsensorsthathavebeendiscoveredsofarandwhichkindofDNAtheyrecognize.
Table1DNAsensorsandDNA
Family
DNAsensor
DNAbesensed
Reference
TLRs
TLR9
DNAwithoutmethylationatCpGmotifs
[10]
Helicase
DDX41
cytosolicDNA
[6]
DHX36
CpG-ADNA
[7]
DHX9
CpG-BDNA
RLRs
RIG-1
[3,11]
MDA5
[3]
p200-protein
p202
cytosolicdsDNA
[5]
AIM2
[12]
IFI16
cytosolicaswellasnucleardsDNA
[13]
Others
Ku70
[9]
Pol-III
cytosolicpoly(dA-dT)DNA
[2]
LRRFIP1
dsDNA
[8]
DAI(ZBP1)
CytosolicdsDNA
[4]
DNAsensorswereabletoinducetheproductionofcytokinessuchasIFNs,interleukins(ILs)andtumornecrosisfactor(TNF)topromotedefenseresponseagainstmicrobialinfection.Ofthese,typesIIFNsplayedapivotalroleinantiviralimmuneresponse.Sofar,fivesubtypesofthetypeIIFNhavebeenidentified:
IFN-α,IFN-β,IFN-δ,IFN-ω,andIFN-τ[14].Ofthese,IFN-δandIFN-τwerenotfoundinhumans.FourmaineffectorpathwaysoftheIFN-mediatedantiviralresponse:
①theMxGTPasepathway,②the2'
5'
-oligoadenylate-synthetase-directedribonucleaseLpathway,③theproteinkinaseRpathway,④theISG15ubiquitin-likepathway,whichindividuallyblockviraltranscription,degradeviralRNA,inhibittranslationandmodifyproteinfunctiontocontrolallstepsofviralreplication[15].Theywerealsopositivelylinkedtotheactivationandexpansionoflymphocytesthatwereimportantforcontrollingintracellularinfections[16].TypeIIIIFNs,includingIFN-λ1,functionallyresembledtypeIIFNsandplayedanimportantroleinantiviralresponseaswell[17].ButthetypeIandtypeIIIIFNantiviralsystemsdidnotmerelyduplicateeachotherfordifferentantiviralpotency,patternoftheirinductionanddifferentialtissueexpressionoftheircorrespondingreceptorsubunits[17].ILsinducedbyDNAsensorincludedIL-1β,IL-6,IL-12[18,19].IL-1βcontributedtohostdefenseagainstinfectionbyaugmentingantimicrobialpropertiesofphagocytessuchasmonocytes,macrophages,andneutrophilsandinitiatingTh1andTh17adaptiveimmuneresponses[20].IL-6notonlywascharacterizedasaBcellgrowthfactorandinducerofantibodyproduction,butalsoinducedneutrophilapoptosisandsubstantiallycontributedtotheresolutionofacuteneutrophilinfiltrationandtheCD4Tcelldifferentiation[21,22],suggestingthatIL-6playedapivotalroleduringthetransitionfrominnatetoacquiredimmunity.IL-12wasakeycytokineinthedevelopmentofTh1cellpolarizationandhasbeenshowntohavepotentimmunomodulatory,antitumor,andanti-infectionactivityinvitroandinvivo[23].Finally,TNFplayedanimportantroleinthedefenseagainstvirus,whichsubvertedtheelectrontransportsystemorthemitochondriaintoproductionofoxygenradicalsandkilledthemalignantcellsthatdidnotcontainorproduceprotectiveenzymes[24].ThushowDNAsensorstriggerallthesecytokineswillbediscussedinthisreview.What’smore,thisreviewwillsummarizeDNAsensorsthathavebeendiscoveredandtheirinteractionwithvirus.Besidesthese,howviruscounteractandhowhostnegativelyregulatetheeffectofDNAsensorswillbealsoconsideredinthisarticle.
2.DNAsensors
2.1.TLR9
TLRswereonekindofpatternrecognitionreceptor,whichplaysacriticalroleininnateimmune.Amongthem,TLR9hasbeenidentifiedasaDNAsensor.AsthereceptorforCpGcontainingbacterialandviralDNA,TLR9wasretainedintheendoplasmicreticulum(ER)[25-27].ItwasfoundbyBrinkmannMMetalthattheinteractionbetweentheERmembraneproteinUNC93BandTLR9
wascrucialforTLR9signaling[28].What’smore,ithasbeenreportedthatintracellularlocalizationofTLR9preventedrecognitionofselfDNAbutfacilitatedaccesstoviralDNA[29].
2.1.1DNAstructure
TLR9recognizedviralorbacterialDNAwithoutmethylationatCpGmotifs[10].Inwildtype(WT)mice,CpG-oligodeoxynucleotide(ODN)inducedastrongactivationofpulmonaryNF-κBaswellasasignificantincreaseinpulmonaryTNF-αandIL-1βmRNA/proteinwhiletheCpG-ODN-inducedinflammatoryresponsewasabolishedinTLR9-deficientmice[30].InthestudybyHaas,Tetal,theDNAsugarbackbonehomopolymeric,base-freephosphodiester(PD)2'
deoxyriboseactedasabasalTLR9agonistasitboundtoandactivatedTLR9,indicatingthatthePD2'
deoxyribosebackboneasanimportantdeterminantofTLR9activationbynaturalDNA[31].CpGDNAmovedintoearlyendosomesandwassubsequentlytransportedtoatubularlysosomalcompartment[26].AndYasuda,KetalfoundthatmacrophageactivationbyaDNA/cationicliposomecomplexrequiredendosomalacidification[32].ConcurrentwiththemovementofCpGDNAincells,TLR9redistributedfromtheERtoCpGDNA-containingstructuresthroughamodelwherebymodificationofthecytosolictailofTLR9,whichalsoaccumulatedmyeloiddifferentiationprimaryresponsegene88(MyD88)[25-27].
2.1.2Adenoviral(Ad)vector
Advector,aDNAvirus,hasbeenwidelyusedforgenetherapyapplicationsandasvaccinevehiclesfortreatinginfectiousdiseases.
ItwasreportedthatAdvectorelicitedinnateimmuneresponsesviaTLR9andinducedIL-6andIL-12secretioninprimarymacrophagesanddendriticcells[19,33].TLR9deficiencyattenuatedtheinnateimmuneresponsetoAd,whereasTLR9blockadereducedtheacuteinflammatoryresponseafterintravenousinjectionofthevector[19,33].Interestingly,AdupregulatedTLR9geneexpressionindependentofTLR9functionfortheintravenousinjectionofluciferase-expressingAdvectorsintoMyD88-orTLR9-deficientmiceresultedinalmostcomparablelevelsofIL-6andIL-12productionandluciferaseexpressionwithwild-typemice,suggestingthatadditionalinnatesignalingpathwaysworkcooperativelywithTLR9[19,33].
CelltypehadaneffectontheimmuneresponseinducedbyTLR9afterAdinjection.Plasmacytoiddendriticcells(pDCs)recognitionofadenoviruswasmediatedbyTLR9anddependentonMyD88,whichinducedproductionoftypeIIFNswhileNon-pDCrecognitionofadenoviruswasTLRindependent[34,35].
2.1.3Baculovirus(BV)
Autographacalifornicanucleopolyhedrovirus(AcNPV),awell-characterizedbaculoviruswasfoundtoactivateTLR9.TheinternalizationofviralDNAviamembranefusionmediatedbytheviralenvelopeglycoprotein,aswellasendosomalmaturation,whichreleasedtheviralgenomeintoTLR9-expressingcellularcompartments,wasnecessaryfortheinductionoftheinnateimmuneresponsebyAcNPV[1].MiceinoculatedintranasallywithAcNPVwereprotectedfromalethalchallengebyinfluenzavirus,whichmightbeduetotheinnateimmuneresponseactivatedbyTLR9.Itwasfoundthat①highlevelsofTNF-αandIL-6productionweredetectedinRAW264.7cellstreatedwithAcNPV;
②monocytesconsistingofmacrophageswerestronglyinducedbypreinoculationwithAcNPVandtheseactivatedimmunocompetentcellssuppressedthespreadoftheinfluenzavirusinfectioninlung
tissue[36].
2.1.4Myxomavirus(MV)
Themyxomavirus-inducedinnateimmuneresponserequiredtheendosomalDNAsensorTLR9anditsadaptorMyD88,transcriptionfactorsIFN-regulatoryfactor(IRF)5andIRF7,andthetypeIIFNpositive-feedbackloopmediatedbythetypeIIFNreceptor(IFNAR1),whichledtotheproductionofIFN-α,IFN-β,TNF,andIL-12p70[37].ThisimmuneresponsewasindependentofthecytosolicRNAsensingpathwaymediatedbymitochondrialantiviralsignalingprotein(MAVS),theTLR3adaptorToll/IL-1receptordomain-containingadaptor-inducingIFN-beta(TRIF),orthetranscriptionfactorIRF3[37].
2.1.5Kilhamratvirus(KRV)
TLR9signalingpathwaysmightbeinvolvedinmediatingautoimmunediabetes.KRV,anssDNAparvovirus,induceddiabetesinlessthan