PKC-ε Regulates Vesicle Delivery and Focal Exocytosis for Efficient IgG-mediated Phagocytosis

Abstract

PKC-{varepsilon} is required for membrane addition during IgG-mediated phagocytosis; its role in this process is ill-defined. High resolution imaging revealed that PKC-{varepsilon} exits the Golgi and enters phagosomes on vesicles that then fuse. TNF- and PKC- colocalize at the Golgi and on vesicles that enter the phagosome. Loss of PKC-{varepsilon} and TNF- delivery upon nocodazole treatment confirmed vesicular transport on microtubules. That TNF-+ vesicles are not delivered in macrophages from PKC-{varepsilon} null mice, or upon dissociation of the Golgi-associated pool of PKC-{varepsilon}, implicates Golgi-tethered PKC-{varepsilon} as a driver of Golgi-to-phagosome trafficking. Finally, we established that PKC-{varepsilon}s regulatory domain is sufficient for delivery of TNF-+ vesicles to the phagosome. These studies reveal a novel role for PKC-{varepsilon} in focal exocytosis: its regulatory domain drives Golgi-derived vesicles to the phagosome while catalytic activity is required for their fusion. This is one of the first examples of a PKC requirement for vesicular trafficking and describes a novel function for a PKC regulatory domain. SummaryGolgi-tethered PKC-{varepsilon} regulates vesicle trafficking along phagosomally-directed microtubules and vesicle fusion into forming phagosomes. Unexpectedly, the regulatory domain is sufficient for vesicle delivery. Graphical AbstractPKC-{varepsilon} is required for Golgi-to-phagosome trafficking. Golgi-tethered PKC-{varepsilon}+ vesicles carry TNF- to IgG phagosomes. Dissociation of PKC-{varepsilon} from the Golgi with PIK93 or expression of hSac1-K2A prevents vesicle delivery. The regulatory domain of PKC-{varepsilon} ({varepsilon}RD) is sufficient for vesicle delivery, but not fusion. Created with BioRender.com O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/443102v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@197962org.highwire.dtl.DTLVardef@7037f6org.highwire.dtl.DTLVardef@16a0610org.highwire.dtl.DTLVardef@1b40a4a_HPS_FORMAT_FIGEXP M_FIG C_FIG