简介:ToclarifytheroleofAPOBEC3G(A3G)incellulardefenseagainsthepatitisBvirus(HBV),theexpressionofA3GinnormalhumanliverandtheregulationoftheA3Gexpressioninhep-atomacellline(HuH-7)wereinvestigated.ExpressionlevelofAPOBEC3smRNAinhumanliverwasdeterminedbyRT-PCR.HuH-7andHepG2cellsweretreatedwithvariousconcentrationsofIFN-α(0U/ml,100U/ml,500U/ml,1000U/ml)for12h.ThemRNAlevelsweremeasuredbyaquantitativeRT-PCR,theresultswerenormalizedrelativetothespecimenswithoutIFN-αstimulation.TotalproteinofHuH-7cellstreatedwithvariousconcentrationsofIFN-αfor48hwassubjectedtoWesternblotanalysis.Forreportergeneassay,HuH-7cellsweretransfectedwiththereporterplasmidscontainingIRF-Esitesanditsmutantswithdifferentlengths.Thenthecellsweretreatedwithorwithout1200U/mlIFN-aforadditional12h(1000U/ml)after24hoftransfection,andthecelllysatewaspreparedandassayedforluciferaseactivity.ItwasfoundthatnormalhumanliverexpressedthemRNAofA3G.A3GmRNAexpressioninHuH-7andHepG2cellswereup-regulatedbyIFN-αstimulationinadose-depen-dentmanner.WesternblotanalysisindicatedthatA3GproteinexpressionwasalsoenhancedbyIFN-αstimulation.SequenceanalysisshowedtheexistenceofputativesitesofIFNregulatoryfactorelement(IRF-E)in5'regionofA3Ggeneupstreamtheinitiationcodon.IFN-αstimulationresultsin6-to8-foldincreaseinluciferaseactivityincellstransfectedwiththeplasmidcontainingIRF-Esitesofthe5'upstreamsequences,whereasluciferaseactivitydidnotchangeincellstransfectedwiththeplasmidcontainingmutantIRF-EsitesorwithoutIRF-Esites.Asaconclusion,A3Gareexpressedinnormalhumanliver.A3Gexpressionwasup-regulatedbyIFN-αstimulationinhepatomacellsandcouldbeinvolvedinhostdefensemechanismsagainstHBV.ERF-Esitein5'regionofAP0BEC3Ggeneupstreamtheinitiationcodonplaysanimportantroleinthisp