The localization, trafficking and retrograde transport of BDNF bound to p75NTR in sympathetic neurons.
BDNF, through p75NTR, promotes apoptosis and inhibits axonal growth of sympathetic neurons, antagonizing the pro-survival and axon growth-promoting actions of NGF through TrkA. While the trafficking of the TrkA:NGF complex is well characterized, little is known about p75NTR:BDNF trafficking in these neurons. Here we show that BDNF binds to and appears inside sympathetic neurons relatively slowly, although the temperature-sensitive internalization step itself is rapid. P75NTR internalization is partially sensitive to disruption of clathrin- or raft-mediated internalization, while that of TrkA is entirely clathrin-mediated. P75NTR, but not Trk, associates with neurotrophins in lipid rafts and coimmunoprecipitates with the truncated beta-caveolin-1 isoform. Finally, we directly visualize the retrograde transport of p75NTR ligands to cell bodies, which is insensitive to inhibitors of Trk retrograde transport, suggesting mechanistic differences. We postulate that beta-caveolin-1-containing lipid rafts and possibly intracellular endosomes might be compartments to which p75NTR:BDNF complexes are trafficked separately from Trk.
Hibbert
Andrew P
AP
Cancer Research and Developmental Biology Programs, Hospital for Sick Children, Toronto, Ontario, and Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4.
Kramer
Bianca M R
BM
Miller
Freda D
FD
Kaplan
David R
DR
D000818:Animals; D000831:Animals, Newborn; D019921:Biotinylation / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D002478:Cells, Cultured; D004347:Drug Interactions; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D049452:Green Fluorescent Proteins / Q000378:metabolism; D047468:Immunoprecipitation / Q000379:methods; D007476:Ionophores / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009761:Nystatin / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D051381:Rats; D020800:Receptor, Nerve Growth Factor / Q000378:metabolism*; D020813:Receptor, trkB / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000166:cytology*; D014162:Transfection / Q000379:methods
D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D007476:Ionophores; D020800:Receptor, Nerve Growth Factor; D009761:Nystatin; D049452:Green Fluorescent Proteins; D013395:Sucrose; D020813:Receptor, trkB