Dynamin-2 mediates clathrin-dependent endocytosis for amyloid-beta internalization in brain microvascular endothelial cells

Dynamin is recognized as a crucial regulator for membrane fission and has three isoforms in mammals. But the expression patterns of dynamin isoforms and their roles in non-neuronal cells are incompletely understood. In this study, the expression profiles of dynamin isoforms and their roles in endocytosis was investigated in brain endothelial cells. We found that Dyn2 was expressed at highest levels, whereas the expression of Dyn1 and Dyn3 were far less than Dyn2. Live-cell imaging was used to investigate the effects of siRNA-mediated knockdown of individual dynamin isoforms on transferrin uptake, and we found that Dyn2, but not Dyn1 or Dyn3, is required for the endocytosis in brain endothelial cells. Results of dextran uptake assay showed that dynamin isoforms are not involved in the clathrin-independent fluid-phase internalization of brain endothelial cells, suggesting the specificity of the role of Dyn2 in clathrin-dependent endocytosis. Immunofluorescence and electron microscopy analysis showed that Dyn2 co-localizes with clathrin and acts at the late stage of vesicle fission in the process of endocytosis. Further results showed that Dyn2 is necessary for the basolateral-to-apical internalization of amyloid-p into brain endothelial cells. We concluded that Dyn2, but not Dyn1 or Dyn3, mediates the clathrin-dependent endocytosis for amyloid-beta internalization particularly from basolateral to apical side into brain endothelial cells.

Automated summary

This study investigated the expression profiles of dynamin isoforms and their roles in endocytosis in brain endothelial cells. Dyn2 was found to be the highest expressed isoform, and it was necessary for transferrin uptake and played a role in the late stage of vesicle fission during endocytosis. The results suggested that Dyn2 mediates clathrin-dependent endocytosis for amyloid-beta internalization from basolateral to apical side into brain endothelial cells, while Dyn1 and Dyn3 did not have the same role.