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Fig. 7 | BMC Biology

Fig. 7

From: Sodium channels enable fast electrical signaling and regulate phagocytosis in the retinal pigment epithelium

Fig. 7

POS phagocytosis assay of hESC-derived RPE with selective Nav blockers. POS phagocytosis assays were performed on mature hESC-derived RPE by incubating the monolayers with purified porcine POS particles with or without Nav blockers (600 nM μ-Conotoxin GIIB, 1 μM A-803467 and 10 μM TTX). a Laser scanning confocal microscopy (LSCM) Z-maximum intensity projections (Z-MIP) and yz and xz cross-sections of the RPE and POS particles (green) with filamentous actin staining (red) after 2 h of phagocytic challenge. Scale bar 10 μm. b Quantification of POS particles from TEM images with immunogold labeled opsin showed a 60% decrease of POS particles/cell in the presence of the blockers. Scale bar 250 nm. c LSCM Z-MIP images of ZO-1 (gray) together with opsin (green). Scale bars 20 μm. d Quantification of control (n = 15) and Nav blocker samples (n = 18) during phagocytosis (2 h +37 °C) showed a 34% reduction in the total number of POS particles in the presence of Nav blockers. e, f Nav channel role in POS binding, internalization and further processing. e LSCM Z-MIP images of phalloidin (red) together with opsin (green) during POS binding and internalization. Scale bars 10 μm. f Quantification of the binding phase (2 h RT, Control n = 15, Nav blockers n = 10) showed no significant reduction in POS numbers due to Nav channel blockers, but a 41% decrease in the internalization phase (2 h RT + 2 h at +37 °C, Control n = 15, Nav blocker n = 15). In control cells, the POS numbers decreased in the processing phase, but not in the presence of Nav channel inhibitors (2 h RT + 5 h at +37 °C, 25% decrease, Control n = 15, Nav blocker n = 15). Center lines show the medians; box limits indicate the 25th and 75th percentiles as determined by R software and whiskers extend to minimum and maximum values

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