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BDNF-induced recruitment of TrkB receptor into neuronal lipid rafts: roles in synaptic modulation.

Suzuki S, Numakawa T, Shimazu K, Koshimizu H, Hara T, Hatanaka H, Mei L, Lu B, Kojima M - J. Cell Biol. (2004)

Bottom Line: Moreover, disruption of lipid rafts prevented potentiating effects of BDNF on transmitter release in cultured neurons and synaptic response to tetanus in hippocampal slices.In contrast, lipid rafts are not required for BDNF regulation of neuronal survival.Thus, ligand-induced TrkB translocation into lipid rafts may represent a signaling mechanism selective for synaptic modulation by BDNF in the central nervous system.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Cell Engineering, National Institute for Advanced Industrial Science and Technology, Ikeda, Osaka, Japan.

ABSTRACT
Brain-derived neurotrophic factor (BDNF) plays an important role in synaptic plasticity but the underlying signaling mechanisms remain unknown. Here, we show that BDNF rapidly recruits full-length TrkB (TrkB-FL) receptor into cholesterol-rich lipid rafts from nonraft regions of neuronal plasma membranes. Translocation of TrkB-FL was blocked by Trk inhibitors, suggesting a role of TrkB tyrosine kinase in the translocation. Disruption of lipid rafts by depleting cholesterol from cell surface blocked the ligand-induced translocation. Moreover, disruption of lipid rafts prevented potentiating effects of BDNF on transmitter release in cultured neurons and synaptic response to tetanus in hippocampal slices. In contrast, lipid rafts are not required for BDNF regulation of neuronal survival. Thus, ligand-induced TrkB translocation into lipid rafts may represent a signaling mechanism selective for synaptic modulation by BDNF in the central nervous system.

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Inhibition of BDNF-induced TrkB translocation by p75NTR. Cultured cortical neurons were infected with adenovirus expressing p75NTR or lacZ as described in Materials and methods. Cells were treated without or with 200 ng/ml BDNF for 30 min. The fractions of rafts and nonrafts were immunoblotted for the indicated proteins. (Top) BDNF-induced translocation and activation of TrkB-FL is inhibited by p75NTR expression. (Bottom) The location and activation of TrkB-FL in nonrafts are not influenced by p75NTR expression. BDNF did not affect the distribution of p75NTR in rafts and nonrafts. Similar results were obtained from two separate experiments.
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fig3: Inhibition of BDNF-induced TrkB translocation by p75NTR. Cultured cortical neurons were infected with adenovirus expressing p75NTR or lacZ as described in Materials and methods. Cells were treated without or with 200 ng/ml BDNF for 30 min. The fractions of rafts and nonrafts were immunoblotted for the indicated proteins. (Top) BDNF-induced translocation and activation of TrkB-FL is inhibited by p75NTR expression. (Bottom) The location and activation of TrkB-FL in nonrafts are not influenced by p75NTR expression. BDNF did not affect the distribution of p75NTR in rafts and nonrafts. Similar results were obtained from two separate experiments.

Mentions: How is BDNF-dependent translocation of TrkB-FL into rafts regulated? Given that the pan-neurotrophin receptor, p75NTR associates with lipid rafts (Higuchi et al., 2003) and forms a heterodimer with Trk family receptors (Hempstead, 2002), p75NTR may facilitate BDNF-dependent association of TrkB with rafts. To test this, we introduced p75NTR or lacZ into cortical neurons using adenovirus-mediated gene transfer. In cortical neurons expressing lacZ, p75NTR was not detectable both in raft fraction and nonraft fraction (Fig. 3, lacZ). Infection of cortical neurons with p75NTR adenovirus resulted in the expression of the 75-kD p75NTR (Fig. 3, p75). The p75NTR did not interfere with basal association of TrkB with rafts or TrkB phosphorylation outside rafts. Interestingly, the expression of exogenous p75NTR in cortical neurons markedly inhibited BDNF-dependent translocation of TrkB-FL into lipid rafts (Fig. 3, TrkB-FLrafts). Consequently, phosphorylated TrkB-FL was not detected in the rafts (Fig. 3, pTrkBrafts). Moreover, application of BDNF did not increase the amount of p75NTR in the rafts (Fig. 3, p75rafts). Together, these data suggest that a lipid raft-associated pan-neurotrophin receptor p75NTR has an inhibitory role in BDNF-dependent translocation of TrkB-FL into rafts.


BDNF-induced recruitment of TrkB receptor into neuronal lipid rafts: roles in synaptic modulation.

Suzuki S, Numakawa T, Shimazu K, Koshimizu H, Hara T, Hatanaka H, Mei L, Lu B, Kojima M - J. Cell Biol. (2004)

Inhibition of BDNF-induced TrkB translocation by p75NTR. Cultured cortical neurons were infected with adenovirus expressing p75NTR or lacZ as described in Materials and methods. Cells were treated without or with 200 ng/ml BDNF for 30 min. The fractions of rafts and nonrafts were immunoblotted for the indicated proteins. (Top) BDNF-induced translocation and activation of TrkB-FL is inhibited by p75NTR expression. (Bottom) The location and activation of TrkB-FL in nonrafts are not influenced by p75NTR expression. BDNF did not affect the distribution of p75NTR in rafts and nonrafts. Similar results were obtained from two separate experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172613&req=5

fig3: Inhibition of BDNF-induced TrkB translocation by p75NTR. Cultured cortical neurons were infected with adenovirus expressing p75NTR or lacZ as described in Materials and methods. Cells were treated without or with 200 ng/ml BDNF for 30 min. The fractions of rafts and nonrafts were immunoblotted for the indicated proteins. (Top) BDNF-induced translocation and activation of TrkB-FL is inhibited by p75NTR expression. (Bottom) The location and activation of TrkB-FL in nonrafts are not influenced by p75NTR expression. BDNF did not affect the distribution of p75NTR in rafts and nonrafts. Similar results were obtained from two separate experiments.
Mentions: How is BDNF-dependent translocation of TrkB-FL into rafts regulated? Given that the pan-neurotrophin receptor, p75NTR associates with lipid rafts (Higuchi et al., 2003) and forms a heterodimer with Trk family receptors (Hempstead, 2002), p75NTR may facilitate BDNF-dependent association of TrkB with rafts. To test this, we introduced p75NTR or lacZ into cortical neurons using adenovirus-mediated gene transfer. In cortical neurons expressing lacZ, p75NTR was not detectable both in raft fraction and nonraft fraction (Fig. 3, lacZ). Infection of cortical neurons with p75NTR adenovirus resulted in the expression of the 75-kD p75NTR (Fig. 3, p75). The p75NTR did not interfere with basal association of TrkB with rafts or TrkB phosphorylation outside rafts. Interestingly, the expression of exogenous p75NTR in cortical neurons markedly inhibited BDNF-dependent translocation of TrkB-FL into lipid rafts (Fig. 3, TrkB-FLrafts). Consequently, phosphorylated TrkB-FL was not detected in the rafts (Fig. 3, pTrkBrafts). Moreover, application of BDNF did not increase the amount of p75NTR in the rafts (Fig. 3, p75rafts). Together, these data suggest that a lipid raft-associated pan-neurotrophin receptor p75NTR has an inhibitory role in BDNF-dependent translocation of TrkB-FL into rafts.

Bottom Line: Moreover, disruption of lipid rafts prevented potentiating effects of BDNF on transmitter release in cultured neurons and synaptic response to tetanus in hippocampal slices.In contrast, lipid rafts are not required for BDNF regulation of neuronal survival.Thus, ligand-induced TrkB translocation into lipid rafts may represent a signaling mechanism selective for synaptic modulation by BDNF in the central nervous system.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Cell Engineering, National Institute for Advanced Industrial Science and Technology, Ikeda, Osaka, Japan.

ABSTRACT
Brain-derived neurotrophic factor (BDNF) plays an important role in synaptic plasticity but the underlying signaling mechanisms remain unknown. Here, we show that BDNF rapidly recruits full-length TrkB (TrkB-FL) receptor into cholesterol-rich lipid rafts from nonraft regions of neuronal plasma membranes. Translocation of TrkB-FL was blocked by Trk inhibitors, suggesting a role of TrkB tyrosine kinase in the translocation. Disruption of lipid rafts by depleting cholesterol from cell surface blocked the ligand-induced translocation. Moreover, disruption of lipid rafts prevented potentiating effects of BDNF on transmitter release in cultured neurons and synaptic response to tetanus in hippocampal slices. In contrast, lipid rafts are not required for BDNF regulation of neuronal survival. Thus, ligand-induced TrkB translocation into lipid rafts may represent a signaling mechanism selective for synaptic modulation by BDNF in the central nervous system.

Show MeSH
Related in: MedlinePlus