Figure 7.

NGF internalization is blocked by Dctn 1 knockdown. A, Fluorescent microscopy of NGF trafficking using Cy3 labeled NGF. DRG neurons (DIV14) were infected with lentiviruses expressing either Luciferase (Luc) or Dctn1 siRNA for 7 d. Neurons were deprived of NGF for 16 h then Cy3 labeled NGF was added to the medium. After 4 h, Cy3 labeled NGF appeared in the cell bodies of control neurons (Luc siRNA); however, no Cy3 NGF was observed in the neuronal soma after Dctn1 knockdown (Dctn1 siRNA). B, The percentage of neurons containing Cy3-labeled NGF in the cell body was determined. Note the normal level of internalized NGF in neurons expressing Dctn1-3 siRNA that produces poor knockdown and no axonal degeneration. A total of 400 neurons were analyzed and the experiments were repeated 3 times. Significantly different (*p < 0.001, Student's t test) from Luciferase siRNA infected neurons.