Heterogeneous Intracellular Trafficking Dynamics of Brain-Derived Neurotrophic Factor Complexes in the Neuronal Soma Revealed by Single Quantum Dot Tracking
(A) QD-BDNF-TrkB complexes are visualized as fluorescent puncta (green) on the plasma membrane and within NG neurons. Z-stack projections (neuronal mid-section, 2.7 µm thick). WGA-Ax488 labeled plasma membrane (magenta). (B) Quantitative localization of single QD-BDNF complexes (green) in neuronal somata vs. plasma membrane (magenta) following QD-BDNF stimulation (200 pM, 5 min pulse). Each bar is the average of n = 8–10 cells; ∼30–50 QDs/cell for each time point. (C) Endosomal co-localization of QD-BDNF complexes (green) with anti-EEA1, and anti-LAMP1antibodies (Ax488, magenta) following a 5 min pulse of QD-BDNF (200 pM, green) at t = 20 and 60 min. Yellow insets show magnified co-localization (white). Control shown at topmost right is same as BDNF-QD + endosomal antibody labeling conditions except with omission of primary antibody. WGA-Ax488 labeled plasma membrane (cyan). Collapsed z-stack projections of neuronal mid-section (2.7 µm thick). Scale bars = 10 µm.