Inhibition of macropinocytosis increases amylin oligomerization in human islets.

<p>Cells were first treated with macropinocytotic inhibitors (EIPA, CytD or Wort) for 1 hour followed by addition of human amylin (10 µM) either in the absence or presence of MB for 24 hours at 37°C. Dextran was finally added for an additional 30 minutes. (<b>A</b>) Immunoconfocal microscopy revealed a significant increase in the PM accumulation of both amylin oligomers (green), detected with A11 antibody and dextran (red) when treated with these inhibitors as compared to the controls (human amylin-treated cells) (left panel). However, in the presence of MB (100 µM), only dextran but not oligomer accumulation was detected on the PM (right panel). Bar 10µm. Extracellular content of amylin oligomers was analyzed by (<b>B</b>) western blot and (<b>C</b>) densitometry. Inhibition of macropinocytosis stimulated oligomer accumulation in the culturing medium, which was reversed by addition of MB. **P<0.01, hA vs. hA/inhibitors, n = 3, ANOVA followed by Dunnett-Square test and ^##P<0.01, hA/inhibitors vs. hA/inhibitors/MB, n = 3, ANOVA followed by Newman-Keul post hoc test.