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. Author manuscript; available in PMC: 2012 Jun 26.
Published in final edited form as: Neuron. 2011 Jun 23;70(6):1085–1099. doi: 10.1016/j.neuron.2011.04.025

Figure 7. Phosphoregulation of dynamin1ab is required for TrkA endocytosis and axon growth.

Figure 7

(A–D) Dynamin1aa isoform (A,B) shows diffuse cytoplasmic localization while dynamin1ab isoform (C,D) shows punctate localization in cell bodies and axons. FLAG immunostaining shows surface FLAG-TrkA receptors in cell bodies (A,C) and in axons (B,D). Scale bar, 10 μm. (E–J) Phosphoregulation of dynamin1aa is not required for NGF-dependent TrkA internalization. Neurons were transfected with FLAG-TrkA and either wild-type dynamin1aa-EGFP (E, F), Ser-Glu 774/778 dynamin1aa-EGFP (G,H), or Ser-Ala 774/778 dynamin1aa-EGFP (I,J). Cell bodies are shown in E, G, I. Axons are shown in F, H, J. Scale bar, 10μm. (K) Quantification of NGF-dependent TrkA internalization in cell bodies and axons. n=3. (L–Q) Phosphomutants of dynamin1ab disrupt NGF-dependent internalization of TrkA. Neurons were transfected with FLAG-TrkA and either wild-type dynamin1ab-EGFP (L,M), Ser-Glu 774/778 dynamin1ab-EGFP (N,O), or Ser-Ala 774/778 dynamin1ab-EGFP (P,Q). Cell bodies are shown in L, N and P. Axons are shown in M, O and Q. Scale bar, 10μm. (R) Quantification of internalized TrkA. *p<0.01, n=3. (S–V) Phosphoregulation of dynamin1ab is required for NGF-, but not NT-3-, dependent axon growth. NGF-mediated growth is blocked in sympathetic neurons expressing dynamin1ab-EGFP Ser-Glu 774/778 (T) as compared to wild-type dynamin1ab-EGFP (S). NT-3-mediated growth was unaffected (U,V). (W) Quantification of neurite length. **p<0.01, n=3. Scale bar: 50 μm.