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bioRxiv · 10.1101/223719

Fast voltage sensitivity in retinal pigment epithelium: sodium channels and their novel role in phagocytosis

Johansson, J. K.·Ihalainen, T. O.·Skottman, H.·Nymark, S.
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Abstract

Despite the discoveries of voltage-gated sodium channels (Nav) from a number of non-excitable cell types, the presence of Nav-mediated currents in cells of the retinal pigment epithelium (RPE) has been dismissed as a cell culture artifact. Here, we challenge this notion by demonstrating functional Nav1.4-Nav1.6 and Nav1.8 channels in human embryonic stem cell derived and mouse RPE. Importantly, we show that Navs are involved in photoreceptor outer segment phagocytosis: blocking their activity significantly reduces the efficiency of this process. Consistent with this role, Nav1.8 co-localizes with the endosomal marker Rab7 and, during phagocytosis, with opsin. Nav1.4 localizes strongly to the cell-cell junctions together with the gap junction protein Connexin 43. During phagocytosis, both are localized to the phagosomes with a concurrent decrease in the junctional localization. Our study demonstrates that Navs give the capacity of fast electrical signaling to RPE and that Navs play a novel role in photoreceptor outer segment phagocytosis.

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Johansson, J. K., Ihalainen, T. O., Skottman, H., Nymark, S.. 2017-11-22. Fast voltage sensitivity in retinal pigment epithelium: sodium channels and their novel role in phagocytosis. https://doi.org/10.1101/223719

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