Visualization of vesicle transport along and between distinct pathways in neurites of living cells

Abstract

Trafficking of secretory vesicles along neurites of PC12 cells was visualized by 2D and 3D real-time imaging using fluorescence microscopy. Vesicle motion along distinct pathways was directly seen. From an overlay of individual pathways, the underlying cytoskeletal filament could be imaged at a subwavelength resolution. Continuous vesicle transport was interrupted by periods of diffusive motion with concomitant pathway changes. Statistical analysis shows that such interruptions were distributed stochastically along the filament, indicating a limited processivity of motor proteins also in a cellular context. Periods of diffusive motion facilitated the interaction with actively transported vesicles. Frequent associations and dissociations of vesicles have been ob- served consistently, pointing to a functional relevance of vesicle cotransport. Microsc. Res. Tech. 63: 159 -167, 2004. © 2004 Wiley-Liss, Inc.