Dynamin1 long- and short-tail isoforms exploit distinct recruitment and spatial patterns to form endocytic nanoclusters

Abstract

Abstract Endocytosis requires a coordinated framework of molecular interactions that ultimately lead to the fission of nascent endosomes. How cytosolic proteins, such as dynamin, timely concentrate at discrete sites that are sparsely distributed across the plasma membrane remains poorly understood. Two dynamin 1 (Dyn1) major splice variants differ by the length of their C-terminal proline-rich region (short-tail and long-tail). Using sptPALM in PC12 cells, neurons and MEF cells, we demonstrate that short-tail Dyn1 isoforms Dyn1ab and Dyn1bb display an activity-dependent recruitment to the membrane, promptly followed by concentration into nanoclusters. These nanoclusters were sensitive to both Calcineurin and Dyn1 GTPase inhibitors, and were larger, denser, and more numerous than that of long-tail isoform Dyn1aa. Spatiotemporal modelling confirmed that Dyn1 isoforms perform distinct search patterns and undergo dimensional reduction to generate endocytic nanoclusters, with short-tail isoforms more robustly exploiting lateral trapping in the generation of nanoclusters compared to long-tail isoform Dyn1aa.