IdentificationofaDNADamage–InducedAlternativeSplicingPathwayThatRegulatesp53andCellularSenescenceMarkersJingChen1,2,JohnCrutchley1,2,DadongZhang2,KourosOwzar2,3,andMichaelB.Kastan1,2ReseaRchaRticleCancerResearch.onDecember27,2018.©2017AmericanAssociationforcancerdiscovery.aacrjournals.orgDownloadedfromPublishedOnlineFirstMarch13,2017;DOI:10.1158/2159-8290.CD-16-0908July2017CANCERDISCOVERY|767aBstRactCellularresponsestoDNAdamagearecriticaldeterminantsofcancerdevelopmentandaging-associatedpathogenesis.Here,weidentifyandcharacterizeaDNA-damageresponse(DDR)pathwaythatregulatesalternativesplicingofnumerousgeneproducts,includingthehumantumorsuppressorTP53,andcontrolsDNAdamage–inducedcellularsenescence.Inbrief,ionizingradiation(IR)inhibitstheactivityofSMG1,aphosphoinositide-3-kinase-likekinasefamilymember,reducingthebindingofSMG1toaspecificregionnearexon9ofp53precursormRNAandpromotingthebindingofribosomalproteinL26(RPL26)top53pre-mRNA.RPL26,inturn,isrequiredfortherecruitmentoftheserine/arginine-richsplicingfactorSRSF7top53pre-mRNAandgenera-tionofalternativelysplicedp53βRNA.Disruptionofthispathwayviaselectiveknockoutofp53βbyCRISPR/Cas9ordownregulationofpathwayconstituentssignificantlyreducesIR-inducedsenescencemarkers,andcellslackingp53βexpressionfailtotranscriptionallyrepressnegativeregulatorsofcellularsenescenceandaging.SIGNIFICANCE:WeidentifiedanewcomponentoftheDDRpathwaythatregulatesalternativesplicingofmessengerRNAs,includinghumanTP53mRNA.ModulationofthisregulatorypathwayaffectsDNA-damageinductionofcellularsenescencemarkers.CancerDiscov;7(7);766–81.©2017AACR.1DepartmentofPharmacologyandCancerBiology,DukeUniversitySchoolofMedicine,Durham,NorthCarolina.2DukeCancerInstitute,DukeUniver-sity,Durham,NorthCarolina.3DepartmentofBiostatisticsandBioinfor-matics,DukeUniversity,Durham,NorthCarolina.Note:SupplementarydataforthisarticleareavailableatCancerDiscoveryOnline(http://cancerdiscovery.aacrjournals.org/).CorrespondingAuthor:MichaelB.Kastan,DukeUniversitySchoolofMe...
