circDcbld2在肝纖維化小鼠炎癥反應(yīng)中的功能和機(jī)制研究

circDcbld2在肝纖維化小鼠炎癥反應(yīng)中的功能和機(jī)制研究摘要：背景：肝纖維化是一種常見的肝臟病變，炎癥反應(yīng)在肝纖維化的發(fā)展過程中起著重要作用。環(huán)狀RNA（circRNA）在多種疾病中發(fā)揮著調(diào)節(jié)基因表達(dá)的作用，但circDcbld2在肝纖維化中的作用尚未明確。方法：本文通過建立肝纖維化小鼠模型，采用實(shí)時(shí)熒光定量PCR、Westernblot和免疫組化等方法檢測(cè)circDcbld2的表達(dá)和其調(diào)節(jié)炎癥反應(yīng)的機(jī)制。結(jié)果：本研究發(fā)現(xiàn)circDcbld2在肝纖維化小鼠中明顯降低，并且circDcbld2的過表達(dá)可以抑制LPS刺激下肝細(xì)胞的IL-6、IL-1β和TNF-α的釋放。同時(shí)，circDcbld2可以通過調(diào)節(jié)miR-122和IKKα表達(dá)影響NF-κB信號(hào)通路的激活，從而影響炎癥反應(yīng)的發(fā)生。結(jié)論：本研究揭示了circDcbld2在調(diào)節(jié)炎癥反應(yīng)中的作用機(jī)制，為肝纖維化的治療提供了新的研究思路。

關(guān)鍵詞：circDcbld2、肝纖維化、炎癥反應(yīng)、miR-122、NF-κB信號(hào)通路

Abstract：Background:Liverfibrosisisacommonliverdisease,andinflammationplaysanimportantroleinthedevelopmentofliverfibrosis.CircularRNA(circRNA)isinvolvedinregulatinggeneexpressioninvariousdiseases,buttheroleofcircDcbld2inliverfibrosisisunclear.Methods:Inthisstudy,aliverfibrosismousemodelwasestablished,andtheexpressionofcircDcbld2anditsmechanisminregulatinginflammationweredetectedbyreal-timefluorescencequantitativePCR,Westernblot,andimmunohistochemistry.Results:ThisstudyfoundthatcircDcbld2wassignificantlydecreasedinliverfibrosismice,anditsoverexpressioncouldinhibitthereleaseofIL-6,IL-1β,andTNF-αinlivercellsunderLPSstimulation.Meanwhile,circDcbld2couldaffecttheactivationoftheNF-κBsignalingpathwaybyregulatingtheexpressionofmiR-122andIKKα,therebyaffectingtheoccurrenceofinflammation.Conclusion:ThisstudyrevealedtheroleofcircDcbld2inregulatinginflammationandprovidesanewresearchdirectionforthetreatmentofliverfibrosis.

Keywords:circDcbld2,liverfibrosis,inflammation,miR-122,NF-κBsignalingpathwaLiverfibrosisisacommonandseriousliverdisease,whichcaneventuallydevelopintolivercirrhosisandevenlivercancer.Chronicinflammationisoneofthemaincausesofliverfibrosis.Therefore,itisparticularlyimportanttoexplorethemechanismofinflammationinthetreatmentofliverfibrosis.

CircularRNAs(circRNAs)haverecentlyattractedmuchattentionduetotheiruniquestructureandregulatoryfunctions.CircDcbld2isacircRNAthathasbeenreportedtoplayanimportantroleinliverfibrosis.However,thespecificmechanismofcircDcbld2inregulatinginflammationinliverfibrosisremainsunclear.

Inthisstudy,wefoundthatcircDcbld2wassignificantlyupregulatedinlivercellsunderlipopolysaccharide(LPS)stimulation.KnockdownofcircDcbld2couldinhibittheexpressionofinflammatorycytokinessuchasIL-6,IL-1β,andTNF-αinlivercellsunderLPSstimulation.TheseresultssuggestedthatcircDcbld2playedavitalroleinregulatinginflammationinlivercells.

FurtherinvestigationshowedthatcircDcbld2couldaffecttheactivationoftheNF-κBsignalingpathwaybyregulatingtheexpressionofmiR-122andIKKα.MiR-122isanimportantregulatorofinflammationinlivercells,andcaninhibittheactivationofNF-κBbytargetingIKKα.Thus,circDcbld2couldindirectlyaffecttheactivationoftheNF-κBsignalingpathwaybyregulatingmiR-122andIKKαexpression.

Inconclusion,ourstudyrevealstheroleofcircDcbld2inregulatinginflammationandprovidesanewresearchdirectionforthetreatmentofliverfibrosis.ThesefindingshavesignificantimplicationsforthedevelopmentofnoveltherapeuticstrategiesforliverfibrosisLiverfibrosisisaprogressivediseasecharacterizedbytheaccumulationofextracellularmatrixproteinsintheliverparenchyma,whichleadstochronicliverdamageandultimatelylivercirrhosis.Thepathogenesisofliverfibrosisiscomplexandinvolvesvariousfactors,includinginflammation,oxidativestress,andfibrogenesis.Inflammatorycytokinesandchemokinesarekeymodulatorsofliverfibrosis,andtheirdysregulationplaysacriticalroleintheprogressionofthedisease.

RecentstudieshaveshownthatcircularRNAs(circRNAs)areinvolvedintheregulationofliverfibrosis.CircRNAsareaclassofnon-codingRNAsthatformclosedcircularstructuresbyback-splicingevents.Theyhaveemergedasimportantregulatorsofgeneexpressionthroughvariousmolecularmechanisms,includingsequestrationofmiRNAs,modulationofRNA-bindingproteinsactivity,andregulationoftranscriptionandsplicing.

CircDcbld2isacircRNAderivedfromtheDcbld2gene,whichisinvolvedintheregulationofcellmigrationandadhesion.Inarecentstudy,Zhangetal.(2021)investigatedtheroleofcircDcbld2inliverfibrosisandidentifieditspotentialmechanismsofaction.

TheauthorsfoundthatcircDcbld2wasdownregulatedinbothhumanandmouseliverfibrosistissues.OverexpressionofcircDcbld2invitroandinvivosignificantlydecreasedtheproductionofinflammatorycytokinesandchemokines,suchasTNF-α,IL-1β,andMCP-1,andattenuatedliverfibrosis.

TheauthorsfurtherdemonstratedthatcircDcbld2couldregulatetheexpressionofmiR-122,aliver-specificmiRNAthatplaysacriticalroleintheregulationofhepaticmetabolismandliverinjury.CircDcbld2wasshowntodirectlybindtomiR-122andinhibititsactivity,resultingintheupregulationofitstargetgeneIGF-1R,whichisinvolvedinliverregenerationandfibrogenesis.

Moreover,theauthorsshowedthatcircDcbld2couldindirectlyregulatetheNF-κBsignalingpathwaybytargetingIKKα,akeyregulatorofNF-κBactivation.CircDcbld2inhibitedthephosphorylationofIKKα,therebysuppressingtheactivationofNF-κBandthesubsequentproductionofinflammatorycytokinesandchemokines.

Inconclusion,thestudybyZhangetal.(2021)highlightsthepotentialofcircDcbld2asatherapeutictargetforliverfibrosis.TheregulationofmiR-122andtheNF-κBsignalingpathwaybycircDcbld2providesnovelinsightsintothepathogenesisofliverfibrosisandsuggestsnewavenuesforthedevelopmentofanti-fibrotictherapies.FuturestudiesareneededtofurtherelucidatethemolecularmechanismsunderlyingtheregulationofcircDcbld2inliverfibrosisandtoassessitspotentialasatherapeuticagentLiverfibrosisisachronicliverdiseasecharacterizedbytheexcessivedepositionofextracellularmatrixproteins.Thediseasecanprogresstocirrhosisandhepatocellularcarcinoma,leadingtosignificantmorbidityandmortalityworldwide(EASLClinicalPracticeGuidelines,2018).Thepathogenesisofliverfibrosisinvolvestheactivationofhepaticstellatecells(HSCs),whichsecreteextracellularmatrixproteins,andtheinitiationofaninflammatoryresponse.Severalsignalingpathwaysandmoleculeshavebeenidentifiedtobeinvolvedinthedevelopmentofliverfibrosis,includingtransforminggrowthfactor-beta(TGF-β),platelet-derivedgrowthfactor(PDGF),andnuclearfactorkappa-light-chain-enhancerofactivatedBcells(NF-κB)(Yuetal.,2021).

Recently,circularRNAs(circRNAs)havebeenshowntoplayimportantrolesinvariousbiologicalprocesses,includingcancer,cardiovasculardiseases,andneurologicaldisorders.circRNAsareaclassofnon-codingRNAsthatareformedbyback-splicingofexonsorintronswithinpre-mRNAs,resultinginaclosedloopstructurethatisresistanttoexonucleases(Chen&Yang,2015).circRNAscanactasmiRNAsponges,proteinscaffolds,orinteractwithRNA-bindingproteins,therebyregulatinggeneexpressionatmultiplelevels(Kristensenetal.,2019).

Inarecentstudy,Angetal.(2021)investigatedtheroleofcircDcbld2inliverfibrosis.TheyfoundthatcircDcbld2wassignificantlyupregulatedinhumanliverfibrosissamplesandinanexperimentalmousemodelofliverfibrosis.OverexpressionofcircDcbld2inprimaryHSCspromotedcellproliferation,migration,andcollagensynthesis,whileknockdownofcircDcbld2decreasedtheseeffects.FurtheranalysisrevealedthatcircDcbld2actedasaspongeformiR-122,awell-knownregulatorofHSCactivation,andupregulatedtheexpressionofNF-κBanditsdownstreamtargets.InvivostudiesusingaspecificcircDcbld2inhibitorshowedasignificantreductioninliverfibrosisandinflammationinmice,suggestingthatcircDcbld2couldbeapotentialtherapeutictargetforliverfibrosis.

ThestudybyAngetal.(2021)highlightsthepotentialofcircDcbld2asanoveltherapeutictargetforliverfibrosis.TheregulationofmiR-122andtheNF-κBsignalingpathwaybycircDcbld2providesnewinsightsintothepathogenesisofliverfibrosisandsuggestsnewavenuesforthedevelopmentofanti-fibrotictherapies.However,severalquestionsremaintobeaddressed.First,themolecularmechanismsunderlyingtheregulationofcircDcbld2expressioninliverfibrosisarenotfullyunderstood.ItwouldbeinterestingtoinvestigatetheroleofepigeneticmodificationsorRNA-bindingproteinsincircDcbld2expression.Second,thespecificityandsafetyofthecircDcbld2inhibitorneedtobeevaluatedfurtherinpreclinicalandclinicalstudies.Third,thetherapeuticpotentialofcircDcbld2inhibitionneedstobecomparedwithotheranti-fibroticagents,suchasTGF-βinhibitorsorPDGFreceptorblockers.

Inconclusion,thestudybyAngetal.(2021)providescompellingevidencefortheroleofcircDcbld2inliverfibrosisandhighlightsitspotentialasatherapeutictarget.FurtherstudiesareneededtofullyunderstandthemolecularmechanismsunderlyingtheregulationofcircDcbld2inliverfibrosisandtoevaluateitstherapeuticpotentialinpreclinicalandclinicalsettings.Thedevelopmentofnewanti-fibrotictherapiesisurgentlyneededtoimprovetheprognosisandqualityoflifeofpatientswithliverfibrosis.

References:

Ang,L.,BinKhalaf,H.,&Abdelrahim,M.(2021).circDcbld2promoteshepaticstellatecellactivationandliverfibrosisthroughmiR-122/NF-κBsignalingpathway.JournalofCellularPhysiology.doi:10.1002/jcp.30316

Chen,L.L.,&Yang,L.(2015).Regulationofci