Pharmacological Protein Kinase C (PKC) Isoform Suppression and K (Rb) Transport Changes in a Primary Fetal Human Lens (FHL) Cell Line

Background Staurosporine, through unknown kinases, induces K loss via 4‐amino pyridine‐sensitive K channels preceding apoptosis in human lens epithelial cells (Cell Physiol 223:110–122, 2010). To further elucidate the kinase nature, we explored the effect of PKC depletion by 12‐O‐tetradecanoylphorphol‐13‐acetate ester (TPA) and the selective PKC inhibitor chelerythrine (CE) on PKC isoform protein expression and known K transport in FHL124 cells (Am. J. Cell Physiol. 294: 820–832, 2008). Methods Pro‐ (α and ε) and anti‐ (δ and θ) apoptotic PKC isoforms (Cell. Mol. Life. Sci. 60: 1061–1070, 2003) were characterized by Western blot (WB) and immunofluorescence (IF). Cells were treated with TPA for up to 6 h (Exp. Cell Research 262: 95–103, 2001). The effect of CE on K loss and Rb influx was measured by atomic absorption spectrometry. Results FHL124 expressed the PKC isoforms α, ε, δ and θ by WB and IF. After 3 h exposure to TPA, PKCα, δ and θ disappeared while PKCε still remained visible after 6 h. Exposure to 25–80 μM CE for 30min inhibited Rb influx by 80% but had little effect on K efflux. TPA and CE alone did not alter K loss, however, reduced total Rb influx by inhibiting the Na/K pump and NKCC1, an effect amplified by drug combination. Conclusions FHL124 cells expressed 4 PKC isoforms which functionally play a key role in CE‐sensitive Na/K pump‐ and NKCC1‐mediated K influxes. PKC suppression suggests they likely control Na/K pump and NKCC1 via phosphorylation.