Protein kinase C (PKC) changes its localization upon various stimuli and exerts its function at the localized sites, which is called PKC translocation. We have previously shown that propofol, an intravenous anesthetic, induces PKC translocation and activates PKC. In this study, we attempted to further analyze propofol-induced PKC translocation and visualize PKC activation sites in cells to elucidate the mechanism of propofol-induced PKC translocation.
We selected PKCα of conventional PKC, PKCδ of novel PKC, and PKCζ of atypical PKC. We transiently expressed GFP-tagged PKCs in HeLa cells and HUVEC. Propofol-induced PKC translocation was observed by time-lapse imaging. Local intracellular PKC activation was analyzed in HeLa cells expressing C kinase activity reporter (CKAR) based on the temporal changes of FRET ratio.
Administration of propofol at 100 μM or higher induced translocation of PKC-GFP. PKCα and PKCδ were significantly translocated to the plasma membrane (PM), and PKCδ was also translocated to Golgi apparatus. PKCζ was translocated into nucleus. Under Ca²⁺ -depleted conditions, the calcium-sensitive PKCα was translocated into the nucleus rather than the PM. These results reveal that propofol-induced translocation is PKC subtypes specific, and has a mechanism for translocation of PKC into nucleus, unlike receptor mediated-translocation. FRET analysis using CKAR showed that PKC was activated at the PM and Golgi. These results suggest that propofol permeates into cells and activates PKC locally, which may be involved in the effects of propofol.