HIV-1 Vpr Induces Adipose Dysfunction in Vivo Through Recipr(5)

elsofPPARg,adiponectin,andmitochon-(P=0.001)andAp2(P=0.01)werelower,andthatofHsl(P=0.004)washigher,inVprcomparedtocontrol

(rtTA)condition.Off-targetDNAsequences~2kbupstreamofthePPARg/GR-bindingsiteswereamplifiedasdrialoxidativeenzymegenesarereducednegativecontrols(NC).3T3-L1,nolentivirus;rtTA,infectedwithcontrolvirus;Vpr,infectedwithWT-Vprvirus;insubcutaneousadiposetissueofHIVpa-tients(9).PPARgpositivelyregulatestheseVpr-R80A,infectedwithVpr-R80Amutantvirus.Valuesaremeans±SE.*P<0.05,**P<0.01,***P<0.001.

genes,indicatingthatHIV-1infectionperseinducesadiposedefectsviaPPARgrepres-sion,consistentwithaVpreffect.SimilargeneexpressiondefectsoccurDISCUSSION

infattissuesofHIV-infected,untreatedlong-termnonprogressors

VprcirculatesinthebloodofHIVpatientsevenafterviral-suppressive(10)andinmiceexpressinga7.7-kbHIV-1construct(30).

ConsistentwithvaryingexpressionofadipokinegenesindifferenttreatmentwithART,anditspresenceinthecirculationofmiceissuf-ficienttorecapitulatethecharacteristicfeaturesofadiposeandhepatichumanadiposedepots(31)andregionaldifferencesinglucocorticoid

metabolicdefectsobservedinHIVpatients:acceleratedlipolysis(17–19),sensitivity(32),repressionofPPARg-regulatedgeneswasless,whereasdiminishedfatmass(7,28),hepatosteatosis(20),insulinresistance,activationofGR-regulatedlipolyticgenes(bothAtglandHsl)wasandhyperglycemia(29).InhibitionofPPAR-regulatedsignalingingreaterinPGF(analogoustohumanvisceralfat)thaninIF(analo-fatandliverisakeymechanisminvivobecauseVpr(i)repressesgoustohumansubcutaneousfat).Inobesehumans,lipolysisishigherPPARg-regulatedgenesresponsibleforadipocytedifferentiation,fattyinvisceralthaninsubcutaneousfat(33),andthefluxoffattyacidsacidtransport,andinsulinsensitization;(ii)repressesPPARa-regulatedfromthisdepotdirectlyintothelivercoulddrivehepatosteatosis.

GRsignaling,whichprofoundlyenhancesATGLexpression(34),genesofhepaticfatoxidationandVLDL-triglycerideexport;and(iii)

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lowersadiponectin,leadingtodecreasedliverAMPK-Thrphospho-wouldincreaseATGLactivityandacceleratelipolysisinVpr-TgPGF.

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HIV-1 Vpr Induces Adipose Dysfunction in Vivo Through Reciprocal Effects on PPAR/GR Co-Regulation

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comparedtoWT(n=4)liver(P=0.05).(H)Increasedliver

mass(normalizedtobodyweight)inVpr-Tg(n=4per

group;P=0.05).(I)IncreasedOilRedOstaininginliverofsVpr-treatedmice(n=6pergroup;P=0.0001).(J)Increasedlivermass(normalizedtobodyweight)insVpr-treatedmice(n=8pergroup;P=0.004).(K)ReducedratioofphosphorylatedAMPKtototalAMPKinVpr-Tg(n=5)comparedtoWT(n=4)liver(P=0.01).(L)DecreasedPepck(P=0.001),Pgc1a(P=0.04),andMtp(P=0.008)mRNAinliverofVpr-Tgmice(n=8pergroup).Valuesaremeans±SE.*P<0.05,**P<0.01,***P<0.001.

ProteinkinaseAactivatesHSLviaSer563phosphorylation,whichwaselevatedinPGFbutreducedinIFofVpr-Tgmice.Glucocorticoidsalsoup-regulateHSLexpression(35).Inmice,expressionofATGL[responsibleforbasallipolysis(36)]isincreasedbyfasting,whereasthatofHSLisnot.ThecoordinateincreaseinbothATGLproteinandphospho-HSL(Ser563)inPGFofVprmiceisexplainedbyen-hancedglucocorticoidsensitization(12).

Adiposemassisregulatedbyturnoverofpreadipocytesthroughproliferation,differentiation,andapoptosis(37).Vprexpressionin3T3-L1preadipocytesblockeddifferentiation,withdown-regulationofgenesoftherelevanttranscriptionfactors.CellcyclearrestatG2-M,associatedwithcontinuouslyelevatedexpressionofcyclinD1[whichinterfereswithPPARg-mediatedadipogenesis(38)],wasakeymech-anismofthedifferentiationblock.ExpressionofthedifferentiationgeneswasnotfullynormalizedbyVpr-R80A;hence,itispossiblethat

mitochondria-dependentapoptosisbyVpr(39),whichisalsomiti-gatedbytheR80Amutation(40),contributestothedifferentiationblock.ExpressionofVprindifferentiatedadipocytesincreasedlipol-ysisandreciprocallyalteredregulationofPPARgandGRtargetgenesinvolvedininsulinsensitivityandlipolysis.DiminishedWATmassalsooccurredwithoutincreaseinoxidativedisposaloffatover24hours,indicatingthatacceleratedlipolysiscausesectopicfatdepositioninnon-adiposeorgans,asiswelldescribedinHIVpatients(41–43).Thus,mul-tipleVprmechanismsproducelipoatrophyandhyperlipolysis.

VprincreasedmacrophagenumberandCLSsinadiposetissueafterexposuretocirculatingVprforonly2weeks.Adiposetissuemacrophagesarederivedfromcirculatingmonocytes;becauseFFAsarepotentmonocytechemoattractants(44),Vpr-inducedhyperlipol-ysiscoulddirectlypromotemacrophageaccumulationinadiposedepots.

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HIV-1 Vpr Induces Adipose Dysfunction in Vivo Through Reciprocal Effects on PPAR/GR Co-Regulation

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Fig.8.Vpr-mediatedpathogenesisofHIV-associatedmetabolicde-fects.HIVpersistingintissuemacrophagesorsequesteredTcellsafterARTreleasesVprthattransducesandaffectspreadipocytes,adipocytes,andhepatocytes.(A)Inpreadipocytes,VprblocksthecellcycleatG2-M,bluntingturnoveranddifferentiationintoadipocytes.(B)Inmatureadipo-cytes,Vprco-repressesPPARg-regulatedgenesandcoactivatesGR-regulatedgenes,leadingtolipolysis,defectivefattyacidstorageandmetabolism,anddiminishedsecretionofadiponectin.(C)Inhepatocytes,Vprco-repressesPPARa,leadingtodefectivefatoxidationandbluntedVLDL-triglyceridepackagingandexport.HepaticconsequencessecondarytoVpr’sadipocyteeffectsincludeincreasedfattyacidfluxandbluntedactivationofAMPKbecauseofdecreasedadiponectin,leadi …… 此处隐藏：5925字，全部文档内容请下载后查看。喜欢就下载吧 ……