Figure 7. The dendritic trafficking pathway of Homer1b/c is distinct from the PSD95 and secretory trafficking pathways.
(A) TIR-FM of hippocampal neurons transfected with PSD95-RFP expressing construct. Left panel: still image of the last frame of time lapse imaging. Arrowheads mark the final positions of two motile puncta. Center panels: confocal images of retrospective staining of endogenous SNX6 and Homer1b/c after live imaging. Right panels: enlargement of arrowhead-indicated, numbered puncta in the center panels. 1 and 2: motile PSD95 puncta lacking both SNX6 and Homer1b/c; 3: vesicle containing endogenous SNX6 and Homer1b/c, but not PSD95; 4: an immobile PSD95 punctum that contacts with SNX6 signal. 5: an immobile PSD95 punctum that colocalizes with Homer1b/c. 6: an immobile PSD95 punctum that colocalizes with both Homer1b/c and SNX6. (B) DIV14 hippocampal neurons were transfected with construct overexpressing PKD-KD and immunostained with antibodies to Homer1b/c on DIV16. Shown are representative confocal images. (C) Quantification of the mean intensity of Homer1b/c signals in the cell body and dendrites in (B) (mean ± SEM, n = 30, N = 3). (D) The effect of PKD-KD overexpression on the distribution of Homer1b/c in dendrites and spines. (E) Quantification of Homer1b/c distribution in (D) (mean ± SEM, n = 30, N = 3). Bars: 1 μm in (A), 20 μm in (B), 2 μm in (D).