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

PKC-ε is required for membrane addition during IgG-mediated phagocytosis; its role in this process is ill-defined. High resolution imaging revealed that PKC-ε exits the Golgi and enters phagosomes on vesicles that then fuse. TNF-α and PKC-α colocalize at the Golgi and on vesicles that enter the phagosome. Loss of PKC-ε and TNF-α delivery upon nocodazole treatment confirmed vesicular transport on microtubules. That TNF-α + vesicles are not delivered in macrophages from PKC-ε null mice, or upon dissociation of the Golgi-associated pool of PKC-ε, implicates Golgi-tethered PKC-ε as a driver of Golgi-to-phagosome trafficking. Finally, we established that PKC-ε’s regulatory domain is sufficient for delivery of TNF-α + vesicles to the phagosome. These studies reveal a novel role for PKC-ε 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. Summary Golgi-tethered PKC-ε regulates vesicle trafficking along phagosomally-directed microtubules and vesicle fusion into forming phagosomes. Unexpectedly, the regulatory domain is sufficient for vesicle delivery. Graphical Abstract PKC-ε is required for Golgi-to-phagosome trafficking. Golgi-tethered PKC-ε + vesicles carry TNF-α to IgG phagosomes. Dissociation of PKC-ε from the Golgi with PIK93 or expression of hSac1-K2A prevents vesicle delivery. The regulatory domain of PKC-ε (εRD) is sufficient for vesicle delivery, but not fusion. Created with BioRender.com