Role for dynamin in late endosome dynamics and trafficking of the cation-independent mannose 6-phosphate receptor

• Published in: Molecular biology of the cell Vol. 11; no. 2; pp. 481 - 495
• Main Authors: Nicoziani, P, Vilhardt, F, Llorente, A, Hilout, L, Courtoy, P J, Sandvig, K, van Deurs, B
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 01.02.2000
• Subjects: Amino Acid Substitution; Antigens, CD - analysis; Biological Transport; Cathepsin D - chemistry; Cathepsin D - metabolism; Cations - metabolism; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cytoplasm - metabolism; Dynamin I; Dynamins; Endocytosis; Endosomes - metabolism; Endosomes - ultrastructure; Genes, Dominant - genetics; Golgi Apparatus - metabolism; Golgi Apparatus - ultrastructure; GTP Phosphohydrolases - genetics; GTP Phosphohydrolases - metabolism; HeLa Cells; Humans; Lysosomal Membrane Proteins; Lysosomes - metabolism; Lysosomes - ultrastructure; Membrane Glycoproteins - analysis; Microscopy, Confocal; Microscopy, Electron; Molecular Weight; Mutation - genetics; Protein Processing, Post-Translational; Receptor, IGF Type 2 - metabolism
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.11.2.481

It is well established that dynamin is involved in clathrin-dependent endocytosis, but relatively little is known about possible intracellular functions of this GTPase. Using confocal imaging, we found that endogenous dynamin was associated with the plasma membrane, the trans-Golgi network, and a perinuclear cluster of cation-independent mannose 6-phosphate receptor (CI-MPR)-containing structures. By electron microscopy (EM), it was shown that these structures were late endosomes and that the endogenous dynamin was preferentially localized to tubulo-vesicular appendices on these late endosomes. Upon induction of the dominant-negative dynK44A mutant, confocal microscopy demonstrated a redistribution of the CI-MPR in mutant-expressing cells. Quantitative EM analysis of the ratio of CI-MPR to lysosome-associated membrane protein-1 in endosome profiles revealed a higher colocalization of the two markers in dynK44A-expressing cells than in control cells. Western blot analysis showed that dynK44A-expressing cells had an increased cellular procathepsin D content. Finally, EM revealed that in dynK44A-expressing cells, endosomal tubules containing CI-MPR were formed. These results are in contrast to recent reports that dynamin-2 is exclusively associated with endocytic structures at the plasma membrane. They suggest instead that endogenous dynamin also plays an important role in the molecular machinery behind the recycling of the CI-MPR from endosomes to the trans-Golgi network, and we propose that dynamin is required for the final scission of vesicles budding from endosome tubules.