Specific high-affinity receptors for neurotrophin-3 on sympathetic neurons.
When used at concentrations allowing interactions only with its high-affinity receptors, neurotrophin-3 (NT-3) promotes the survival of sensory neurons isolated from embryonic day 8 (E8) chicks, but not the survival of E11 sympathetic neurons. These sympathetic neurons (which can be rescued by the addition of NGF) display high-affinity receptors for NT-3 (Kd of 1.6 x 10(-11) M) that cannot be distinguished from the high-affinity NT-3 receptors on sensory neurons using equilibrium binding or kinetic criteria. This represents the first example of embryonic neurons that cannot be rescued by the in vitro addition of a neurotrophin in spite of the presence of corresponding neurotrophin high-affinity receptors. At elevated concentrations, beyond the saturation of its high-affinity receptors, NT-3 supports the survival of some E11 sympathetic neurons, an effect that might be mediated by the high-affinity NGF receptor. Using E7 sympathetic neurons, about 40% of the cells initially plated can be rescued in vitro by the addition of low concentrations of NT-3 (but not of NGF) and produce profuse neurites. This indicates that NT-3 may play a role in the early development of some sympathetic neurons.
Department of Neurobiochemistry, Max Planck Institute for Psychiatry, Martinsried, Germany.
G
G
Dechant
A
A
Rodríguez-Tébar
R
R
Kolbeck
Y A
YA
Barde
D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002470:Cell Survival; D002478:Cells, Cultured; D005728:Ganglia, Sympathetic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D020933:Neurotrophin 3; D020812:Receptor, trkC; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism
D008562:Membrane Glycoproteins; D009414:Nerve Growth Factors; D020933:Neurotrophin 3; D017475:Receptors, Nerve Growth Factor; D020812:Receptor, trkC