Journal-club-文献报告

1Heregulin,anewregulatoroftelomerelengthinhumancells2016-1-11JournalclubOncotarget,Vol.6,No.372Technologiesrelatedtothispaper1.Telomerelengthdetectionmethod-SouthernBlotL=Σ(ODi•Li)/Σ(ODi)Equation132.Telomeraseactivitydetectionmethod-TRAP43.Telomerebindingproteins--Shelterin5BackgroundHeregulin(HRG,调蛋白)isacombinatorialligandoftheepidermalgrowthfactor(EGF)family.SeveralisoformsofHRG,alsocalledneuregulins(NRGs),areproducedbyalternativesplicing.Theisoformβ2oftheHRGfamilyofgrowthfactors(HRGβ2)isatumor-promotinggrowthfactorconventionallydescribedasanindirectactivatorofHER2(erbB2)oncogene-drivensignalingviaitsabilitytobindHER3(erbB3)andHER4(erbB4).67BackgroundHRGβ2ForcedexpressionIncreasethesensitivityofBCcellstodoxorubicinConferresistancetocisplatinOverexpressionChemosensitivityCarcinogenesHER2dependentmannerHER2independentmannerTelomere？8MaterialsandmethodsMaterials1.AntibodiesandprobesAntibodiesagainstTRF2，TRF1，RAP1;TTAGGGprobes2.CelllinesBreastcancercelllinesMCF7，MDA-MB-231，Hs578HandhumanepidermoidcarcinomacellsA4313.VectorEukaryoticexpressionvectorpRC/CMV，pRC/CMV-HRGbeta2，antisense-HRGbeta24.ChemicalGeneticinG4189Figure1:HRGβ2regulatestelomerelengthinhumanbreastcancercells.Results10Figure1:HRGβ2regulatestelomerelengthinhumanbreastcancercells.11Figure2:HRGβ2doesnotmodifytelomeraseactivityinbreastcancercells.12Figure3:HRGβ2regulatesTRF2expressioninbreastcancercells.13Figure3:HRGβ2regulatesTRF2expressioninbreastcancercells.14Figure4:A.Retrovirally-inducedHRGβ2regulatesTRF2andRAP1expressionandtelomerelengthinMCF-7breastcancercells15Figure4:B.HRGknockdownreducesthepresenceofTRF2andRAP1ontelomeresandpromotestelomerelengthening.16Figure5:TelomericlocalizationofHRGβ2inhumancancercells.A.SubnuclearlocalizationofHRGβ2anditsrelationshipwithtelomericloci17Figure5:TelomericlocalizationofHRGβ2inhumancancercells.18DiscussionsAsweknow，thereareseveralfactorsinfluenttelomerelength,suchastheactivityoftelomerase,therateoftelomereshortening,andthelevelsoftelomerelengthcontrollingfactors.Inthisstudy,theauthorsfailedtodetectanysignificantchangeintelomeraseactivityinresponsetochangesinHRGβ2expression.Fortunately,TheyfoundthatHRGβ2couldregulatetheexpressionofnativeTRF2andRAP1proteins.19DiscussionsThetelomereregulator,RAP1,wasidentifiedasaproteinthatnegativelyregulatestelomerelengthbyspecificallyinteractingwithTRF2whilefunctioningasaproteinadaptorthatbringsdifferentfactorsintothetelomericcomplex.TheTTAGGGrepeatsofhumantelomericDNArecruittelomerespecificproteins,amongthemtheclassicaltelomererepeatbindingproteinsTRF1andTRF2.WhereastelomeraseitselfseemstobethetargetofTRF1-drivenregulationoftelomerelength,TRF2targetingandtelomeraseinhibitionhavebeenshowntoinduceadditiveeffectsontelomerelength,thussuggestingthatTRF2canexclusivelyactivateatelomericdegradationpathway.20DiscussionsAlthoughtheprecisemechanismresponsiblefortheHRGβ2-drivenregulationofnativeTRF2andRAP1remainstobeelucidated,itisreasonabletopostulatethatalteredpost-translationalmodificationsand,mostlikely,protein-proteininteractions,mightunderlietheabilityofHRGβ2toregulatetheTRF2/RAP1complex.Consistentwiththisnotion,HRGβ2significantlyco-localizedwithTRF2andRAP1atthetelomerecomplex,whileco-immunoprecipitationassaysrevealedthatHRGβ2coulddirectlyinteractwithTRF2.21ConclusionAuthersherepresentthefirstevidencethatHRGβ2,amemberoftheHRGfamilyofgrowthfactors,isanovelregulatoroftelomerelengthinhumancells.OurfindingsclearlyshowthatHRGβ2mightnegativelyregulatetelomerelengthbydeterminingtheabilityofthetelomere-bindingproteinsTRF2andRAP1tostablylocalizeatchromosomeends.22Whatcancanwelearnfromthispaper?1.AuthorsselectedhumanepidermoidcarcinomacellsA431toconfirmthefunctionofHRGβ2isnotbreastcancerspecific.2.Co-immunoprecipitationassaysrevealedthatHRGβ2coulddirectlyinteractwithTRF2.3.Someskillsonwriting.23Whatcanweimproveonthispaper?MeasurethechangeoftelomerelengthinMDA-MB-231cellstreatedwithknockdownofthetelomerebindingproteinsTRF2andRAP1,andprovideadirectlyfactthatwhetherHRGβ2regulatetelomerelengthviaTRF2andRAP1.24THANKYOUFORYOURLISTENING252627