Fig. 8.

Cx43 HC activity is regulated by intracellular redox state. (A) HLE-B3 cells were treated with or without 63 mJ/cm² UVB radiation and followed by a dye uptake assay with EtBr and FITC-Dextran. Cells were pre-treated with GSH or DTT (indicated as pre-GSH or pre-DTT) for 20 min and followed by replacing with culture medium collected from parallel cells cultured for the same time periods immediately before UVB radiation (indicated as rm-GSH or rm-DTT). After UVB radiation, 1 mM GSH or DTT (indicated as GSH or DTT) were added and incubated for 10 min before EtBr uptake assay. Scale bar: 50 μm. (B) HeLa cells expressing WT Cx43 or various Cx43 cysteine mutants and treated with or without 108 mJ/cm² UVB radiation, were incubated with DAPI and rhodamine-dextran for 5 min then immunostained with anti-Cx43CT (purple) antibody. Scale bar: 20 μm. Membrane extracts were prepared and then immunoblotted with anti-Cx43 antibody (upper right panel). At least three microphotographs of fluorescence fields were taken under a microscope (Keyence BZ-X710) with 20X objective and TxRed, Cy5 or DAPI filters. The average pixel density of 30 random cells was measured by using ImageJ software. The data are presented as the mean ± SEM. (n = 3). *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 (Two-way ANOVA). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)