Brain-derived neurotrophic factor regulates surface expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptors by enhancing the N-ethylmaleimide-sensitive factor/GluR2 interaction in developing neocortical neurons.
In hippocampal neurons, the exocytotic process of alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA)-type glutamate receptors is known to depend on activation of N-methyl-d-aspartate channels and its resultant Ca(2+) influx from extracellular spaces. Here we found that brain-derived neurotrophic factor (BDNF) induced a rapid surface translocation of AMPA receptors in an activity-independent manner in developing neocortical neurons. The receptor translocation became evident within hours as monitored by [(3)H]AMPA binding and was resistant against ionotropic glutamate receptor antagonists as evidenced with surface biotinylation assay. This process required intracellular Ca(2+) and was inhibited by the blockers of conventional exocytosis, brefeldin A, botulinum toxin B, and N-ethylmaleimide. To explore the translocation mechanism of individual AMPA receptor subunits, we utilized the human embryonic kidney (HEK) 293 cells carrying the BDNF receptor TrkB. After the single transfection of GluR2 cDNA or GluR1 cDNA into HEK/TrkB cells, BDNF triggered the translocation of GluR2 but not that of GluR1. Subsequent mutation analysis of GluR2 carboxyl-terminal region indicated that the translocation of GluR2 subunit in HEK293 cells involved its N-ethylmaleimide-sensitive factor-binding domain but not its PDZ-interacting site. Following co-transfection of GluR1 and GluR2 cDNAs, solid phase cell sorting revealed that GluR1 subunits were also able to translocate to the cell surface in response to BDNF. An immunoprecipitation assay confirmed that BDNF stimulation can enhance the interaction of GluR2 with N-ethylmaleimide-sensitive factor. These results reveal a novel role of BDNF in regulating the surface expression of AMPA receptors through a GluR2-NSF interaction.
Narisawa-Saito
Mako
M
Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan.
Iwakura
Yuriko
Y
Kawamura
Meiko
M
Araki
Kazuaki
K
Kozaki
Shunji
S
Takei
Nobuyuki
N
Nawa
Hiroyuki
H
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005089:Exocytosis; D006801:Humans; D052066:N-Ethylmaleimide-Sensitive Proteins; D019579:Neocortex / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D033921:Vesicular Transport Proteins
D019208:Brain-Derived Neurotrophic Factor; D002352:Carrier Proteins; D018091:Receptors, AMPA; D033921:Vesicular Transport Proteins; D052066:N-Ethylmaleimide-Sensitive Proteins; C498737:Nsf protein, rat; C104722:glutamate receptor ionotropic, AMPA 2