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Antagonistic effects of TrkB and p75 NTR on NMDA receptor currents in post‐synaptic densities transplanted into Xenopus oocytes
Author(s) -
Sandoval Mauricio,
Sandoval Rodrigo,
Thomas Ulrich,
Spilker Christina,
Smalla KarlHeinz,
Falcon Romina,
Marengo Juan José,
Calderón Rodrigo,
Saavedra Verónica,
Heumann Rolf,
Bronfman Francisca,
Garner Craig C.,
Gundelfinger Eckart D.,
Wyneken Ursula
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.04519.x
Subject(s) - tropomyosin receptor kinase b , long term potentiation , nmda receptor , neurotrophin , synaptic plasticity , biology , neuroscience , brain derived neurotrophic factor , low affinity nerve growth factor receptor , neurotrophic factors , microbiology and biotechnology , forebrain , chemistry , receptor , central nervous system , biochemistry
Brain‐derived neurotrophic factor (BDNF) and its receptor TrkB are essential regulators of synaptic function in the adult CNS. A TrkB‐mediated effect at excitatory synapses is enhancement of NMDA receptor (NMDA‐R)‐mediated currents. Recently, opposing effects of TrkB and the pan‐neurotrophin receptor p75 NTR on long‐term synaptic depression and long‐term potentiation have been reported in the hippocampus. To further study the regulation of NMDA‐Rs by neurotrophin receptors in their native protein environment, we micro‐transplanted rat forebrain post‐synaptic densities (PSDs) into Xenopus oocytes. One‐minute incubations of oocytes with BDNF led to dual effects on NMDA‐R currents: either TrkB‐dependent potentiation or TrkB‐independent inhibition were observed. Pro‐nerve growth factor, a ligand for p75 NTR but not for TrkB, produced a reversible, dose‐dependent, TrkB‐independent and p75 NTR ‐dependent inhibition of NMDA‐Rs. Fractionation experiments showed that p75 NTR is highly enriched in the PSD protein fraction. Immunoprecipitation and pull‐down experiments further revealed that p75 NTR is a core component of the PSD, where it interacts with the PDZ3 domain of the scaffolding protein SAP90/PSD‐95. Our data provide striking evidence for a rapid inhibitory effect of p75 NTR on NMDA‐R currents that antagonizes TrkB‐mediated NMDA‐R potentiation. These opposing mechanisms might be present in a large proportion of forebrain synapses and may contribute importantly to synaptic plasticity.