Quantum Dot Probes for Tracking Nerve Growth Factor Ligand-Receptor Dynamics in Live Neurons

摘要

The mechanisms by which cell-surface receptors interact with their specific ligands to initiate signaling cascades is a dynamic process which involves ligand-receptor binding, transport, and clearance across and within the cell plasma membrane. Nerve growth factor (NGF) is a neurotrophin that plays a significant role in neural survival, growth and regeneration. The spatial and temporal dynamics of NGF-TrkA receptor binding has been shown to be important in regulating different aspects of neurotrophin signal transduction. However, the process by which growth factor-receptor complexes are shuttled from distal axons to neuronal cell bodies is still unclear and an active area of investigation. Organic fluorophores currently used for locating receptors on neurons suffer from the drawbacks of limited spatial resolution and photobleaching. Nanometer sized, photostable quantum dots (QDs) offer the potential to track NGF-TrkA dynamics with high-resolution (molecular detection) over long periods of time. Antibody conjugated QDs have been used for labeling and tracking single receptors. In addition, ligand-conjugated QDs retain their activity and bind to receptors. In this study we employ anti-TrkA-QD antibody conjugates to visualize TrkA receptor spatio-temporal dynamics in the neuronal PC12 cell line.