IMMUNOLOGYESCRT-dependentmembranerepairnegativelyregulatespyroptosisdownstreamofGSDMDactivationSebastianRühl1,2,KaterynaShkarina3*,BenjaminDemarco3*,RosalieHeilig3*,JoséCarlosSantos3*,PetrBroz1,3†Pyroptosisisalyticformofcelldeaththatisinducedbyinflammatorycaspasesuponactivationofthecanonicalornoncanonicalinflammasomepathways.ThesecaspasescleavegasderminD(GSDMD)togenerateanN-terminalGSDMDfragment,whichexecutespyroptosisbyformingmembranepores.WefoundthatcalciuminfluxthroughGSDMDporesservesasasignalforcellstoinitiatemembranerepairbyrecruitingtheendosomalsortingcomplexesrequiredfortransport(ESCRT)machinerytodamagedmembraneareas,suchastheplasmamembrane.InhibitionoftheESCRT-IIImachinerystronglyenhancespyroptosisandinterleukin-1breleaseinbothhumanandmurinecellsaftercanonicalornoncanonicalinflammasomeactivation.Theseresultsnotonlyattributeananti-inflammatoryroletomembranerepairbytheESCRT-IIIsystembutalsoprovideinsightintogeneralcellularsurvivalmechanismsduringpyroptosis.GasderminD(GSDMD)isapore-formingproteinthatinducespyroptosis,anecroticformofcelldeaththatisinitiatedafterin-flammasomeactivation(1–3).Thedetec-tionofpathogen-orhost-deriveddangersignalsbyinflammasomestriggerstheactivationofinflammatorycaspases(caspase-1and-11inmiceandcaspase-1and-4inhumans),whichcleaveGSDMDtoreleaseautoinhibitiononitsN-terminaldomain(GSDMDNT)(1,2).TheGSDMDNTtar-getstheplasmamembraneandorganelles,whereitformslargeporestoinitiatepyroptosis(4–7).Damagetotheplasmamembranedoesnotneces-sarilyresultincelldeath,asithasbeenobservedthattheinfluxofCa2+ionsfromtheextracel-lularmilieutriggersrepairprogramsinvolvingeithertheendocytosisofadamagedmembraneoritssheddingintheformofectosomes(8–11).Thislattermechanismreliesoncomponentsofendosomalsortingcomplexesrequiredfortrans-port(ESCRT-0and-IIIandassociatedfactorsthatcontrolESCRTrecruitmentanddisassembly)andhasbeenspecificallyimplicatedintheres-torationofplasmamembraneintegrityduringnecroptosis(12)oruponchemical-orlaser-induceddamage(10,11).Toinvesti...
