FIG. 5.

Morphology of islets, β-cell size, and insulin granule density are not noticeably different in PI4P5Kα KO mice, but distance of granules from cortex is. A: Confocal microscopy image of WT and KO islets stained with anti-insulin and antiglucagon primary antibodies to visualize β-cells and α-cells, respectively. B: Quantitation of WT and KO β-cell size using transmission electron microscopy. C: Quantitation of the number of insulin granules contained in WT and KO islets normalized for the size of the each islet. D: Transmission electron microscopy images of WT and KO islets. KO β-cells show less insulin vesicles docked at the plasma membrane in comparison with WT β-cells (magnified lower panels; bar, 500 nm). Asterisks indicate boundaries between adjacent β-cells. E: Distance of subgranular pools of insulin to the plasma membrane in WT and KO cells under basal conditions. Insulin granules were grouped into three categories with respect to distance from plasma membrane: <50, 50–300, and >300 nm. Granules located with 50 nm from plasma membrane were considered to be docked granules. Granules were tabulated from 10 sections for each genotype. Data are presented as mean ± SEM. (A high-quality color representation of this figure is available in the online issue.)