PKC‐ɛ pseudosubstrate and catalytic activity are necessary for membrane delivery during IgG‐mediated phagocytosis

[摘要] InRAW264.7cells[1],PKC‐ɛregulatesFcγR‐mediatedphagocytosis.BMDMbehavesimilarly;PKC‐ɛconcentratesatphagosomesandinternalizationarereducedinPKC‐ɛ−/−cells.Twoquestionswereasked:whatistheroleofPKC‐ɛ?andwhatdomainsarenecessaryforPKC‐ɛconcentration?FunctionwasstudiedusingBMDMandfrustratedphagocytosis.OnIgGsurfaces,PKC‐ɛ−/−macrophagesspreadlessthanWT.Patch‐clampingrevealedthatthespreadingdefectisaresultofthefailureofPKC‐ɛ−/−macrophagestoaddmembrane.ThedefectisspecificforFcγRligationandcanbereversedbyexpressionoffull‐length(butnottheisolatedRD)PKC‐ɛinPKC‐ɛ−/−BMDM.Thus,PKC‐ɛfunctioninphagocytosisrequirestranslocationtophagosomesandthecatalyticdomain.TheexpressionofchimericPKCmoleculesinRAWcellsidentifiedtheɛPSasnecessaryforPKC‐ɛtargeting.Whenplacedinto(nonlocalizing)PKC‐δ,ɛPSwassufficientforconcentration,albeittoalesserdegreethanintactPKC‐ɛ.Incontrast,translocationofδ(ɛPSC1B)resembledthatofWTPKC‐ɛ.Thus,ɛPSandɛC1Bcooperateforoptimalphagosometargeting.Finally,cellsexpressingɛK437WweresignificantlylessphagocyticthantheirPKC‐ɛ‐expressingcounterparts,blockedatthepseudopod‐extensionphase.Insummary,wehaveshownthatɛPSandɛC1BarenecessaryandsufficientfortargetingPKC‐ɛtophagosomes,whereitscatalyticactivityisrequiredformembranedeliveryandpseudopodextension...

[学科分类] 生理学

[关键词] patch‐clamping;membrane fusion;macrophages;FcγR