Fig. 2. Accumulation of cytoplasmic proinsulin granules in β-cells during chronic ER stress is conserved in rat and human species.
Fluorescence immunocytochemistry of MIN6 (a), INS1E (d), mouse islets (g) and EndoC βH3 (f), cells treated with CPA for 6 h and 18 h (MIN6), 6 h (INS1E) 18 h (mouse islets) and 72 h (EndoC βH3) for the indicated (color-coded) proteins. Boxes indicated the enlarged regions of images below each panel. b Quantitative analysis of the proinsulin puncta subcellular localization in the indicated treatments of MIN6 cells. c Fluorescence immunocytochemistry of MIN6 cells for the indicated proteins and treatments. e Reconstruction of stacking images represented by the box in d. h Schematic representation of the non-canonical exit of proinsulin from the ER. n, indicates number if cells from 3 independent experiments. The % of cells for the indicated phenotype are given in 2b in colored boxes and columns. Scale bar, 10 μm (a), 20 μm (c, d, f), 50 μm (g).