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PICK1-mediated glutamate receptor subunit 2 (GluR2) trafficking contributes to cell death in oxygen/glucose-deprived hippocampal neurons.

Dixon RM, Mellor JR, Hanley JG - J. Biol. Chem. (2009)

Bottom Line: Using biochemical and electrophysiological approaches, we show that peptides that interfere with PICK1 PDZ domain interactions block the OGD-induced switch in subunit composition, implicating PICK1 in restricting GluR2 from synapses during OGD.Furthermore, we show that GluR2-lacking AMPARs that arise at synapses during OGD as a result of PICK1 PDZ interactions are involved in OGD-induced delayed cell death.This work demonstrates that PICK1 plays a crucial role in the response to OGD that results in altered synaptic transmission and neuronal death and has implications for our understanding of the molecular mechanisms that underlie cell death during stroke.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council (MRC) Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.

ABSTRACT
Oxygen and glucose deprivation (OGD) induces delayed cell death in hippocampal CA1 neurons via Ca(2+)/Zn(2+)-permeable, GluR2-lacking AMPA receptors (AMPARs). Following OGD, synaptic AMPAR currents in hippocampal neurons show marked inward rectification and increased sensitivity to channel blockers selective for GluR2-lacking AMPARs. This occurs via two mechanisms: a delayed down-regulation of GluR2 mRNA expression and a rapid internalization of GluR2-containing AMPARs during the OGD insult, which are replaced by GluR2-lacking receptors. The mechanisms that underlie this rapid change in subunit composition are unknown. Here, we demonstrate that this trafficking event shares features in common with events that mediate long term depression and long term potentiation and is initiated by the activation of N-methyl-d-aspartic acid receptors. Using biochemical and electrophysiological approaches, we show that peptides that interfere with PICK1 PDZ domain interactions block the OGD-induced switch in subunit composition, implicating PICK1 in restricting GluR2 from synapses during OGD. Furthermore, we show that GluR2-lacking AMPARs that arise at synapses during OGD as a result of PICK1 PDZ interactions are involved in OGD-induced delayed cell death. This work demonstrates that PICK1 plays a crucial role in the response to OGD that results in altered synaptic transmission and neuronal death and has implications for our understanding of the molecular mechanisms that underlie cell death during stroke.

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OGD-induced increase in AMPA receptor rectification is blocked by inhibiting PICK1 PDZ domain interactions. Top panels, example traces recorded at –70 mV and +40 mV pre-OGD (black) and post-OGD (red). Post-OGD traces are scaled so that –70 mV peaks are identical. Bottom panels, average change in rectification (n = 7) with individual experiments represented by circles. A, control peptide pep2-SVKE has no effect on the OGD-induced decrease in the rectification index. **, p < 0.005. B, PICK1-specific peptide pep2-EVKI completely blocks the OGD-induced change in the rectification index. C, PICK1 and ABP/GRIP-blocking peptide pep2-SVKI does not completely block OGD-induced change in the rectification index. *, p < 0.05.
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fig2: OGD-induced increase in AMPA receptor rectification is blocked by inhibiting PICK1 PDZ domain interactions. Top panels, example traces recorded at –70 mV and +40 mV pre-OGD (black) and post-OGD (red). Post-OGD traces are scaled so that –70 mV peaks are identical. Bottom panels, average change in rectification (n = 7) with individual experiments represented by circles. A, control peptide pep2-SVKE has no effect on the OGD-induced decrease in the rectification index. **, p < 0.005. B, PICK1-specific peptide pep2-EVKI completely blocks the OGD-induced change in the rectification index. C, PICK1 and ABP/GRIP-blocking peptide pep2-SVKI does not completely block OGD-induced change in the rectification index. *, p < 0.05.

Mentions: The OGD-induced Change in AMPAR-EPSC Rectification Is PICK1-dependent—The increase in rectification following OGD suggests a rapid decrease in the proportion of synaptic GluR2-containing AMPARs relative to GluR2-lacking AMPARs during the OGD insult. Because PDZ domain interactions with GluR2 are known to regulate AMPAR trafficking (19, 26, 27), we carried out experiments to determine the role of such interactions during OGD using peptides corresponding to the C terminus of GluR2 to block interactions with the PDZ domains of PICK1 or of ABP and GRIP1 (hereafter referred to as ABP/GRIP). The wild-type sequence pep2-SVKI blocks PICK1 and ABP/GRIP PDZ domains, pep2-EVKI specifically blocks PICK1, and pep2-SVKE is an inactive control peptide (28). These peptides were included separately in our recording solution and diffused into the cell during the experiment. As expected, inclusion of the control peptide pep2-SVKE had no effect on the change in the rectification index induced by OGD (Fig. 2A, pre-OGD = 0.4 ± 0.04, post-OGD = 0.3 ± 0.03, n = 7, p < 0.005). However, the PICK1-specific pep2-EVKI completely blocked the decrease in the rectification index (Fig. 2B, pre-OGD = 0.33 ± 0.02, post-OGD = 0.36 ± 0.02, n = 6, p = 0.46). Surprisingly, pep2-SVKI, which blocks both PICK1 and ABP/GRIP PDZ domains, did not completely block the decrease in the rectification index (Fig. 2C, pre-OGD = 0.42 ± 0.04, post-OGD = 0.37 ± 0.03, n = 6, p < 0.05).


PICK1-mediated glutamate receptor subunit 2 (GluR2) trafficking contributes to cell death in oxygen/glucose-deprived hippocampal neurons.

Dixon RM, Mellor JR, Hanley JG - J. Biol. Chem. (2009)

OGD-induced increase in AMPA receptor rectification is blocked by inhibiting PICK1 PDZ domain interactions. Top panels, example traces recorded at –70 mV and +40 mV pre-OGD (black) and post-OGD (red). Post-OGD traces are scaled so that –70 mV peaks are identical. Bottom panels, average change in rectification (n = 7) with individual experiments represented by circles. A, control peptide pep2-SVKE has no effect on the OGD-induced decrease in the rectification index. **, p < 0.005. B, PICK1-specific peptide pep2-EVKI completely blocks the OGD-induced change in the rectification index. C, PICK1 and ABP/GRIP-blocking peptide pep2-SVKI does not completely block OGD-induced change in the rectification index. *, p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2682871&req=5

fig2: OGD-induced increase in AMPA receptor rectification is blocked by inhibiting PICK1 PDZ domain interactions. Top panels, example traces recorded at –70 mV and +40 mV pre-OGD (black) and post-OGD (red). Post-OGD traces are scaled so that –70 mV peaks are identical. Bottom panels, average change in rectification (n = 7) with individual experiments represented by circles. A, control peptide pep2-SVKE has no effect on the OGD-induced decrease in the rectification index. **, p < 0.005. B, PICK1-specific peptide pep2-EVKI completely blocks the OGD-induced change in the rectification index. C, PICK1 and ABP/GRIP-blocking peptide pep2-SVKI does not completely block OGD-induced change in the rectification index. *, p < 0.05.
Mentions: The OGD-induced Change in AMPAR-EPSC Rectification Is PICK1-dependent—The increase in rectification following OGD suggests a rapid decrease in the proportion of synaptic GluR2-containing AMPARs relative to GluR2-lacking AMPARs during the OGD insult. Because PDZ domain interactions with GluR2 are known to regulate AMPAR trafficking (19, 26, 27), we carried out experiments to determine the role of such interactions during OGD using peptides corresponding to the C terminus of GluR2 to block interactions with the PDZ domains of PICK1 or of ABP and GRIP1 (hereafter referred to as ABP/GRIP). The wild-type sequence pep2-SVKI blocks PICK1 and ABP/GRIP PDZ domains, pep2-EVKI specifically blocks PICK1, and pep2-SVKE is an inactive control peptide (28). These peptides were included separately in our recording solution and diffused into the cell during the experiment. As expected, inclusion of the control peptide pep2-SVKE had no effect on the change in the rectification index induced by OGD (Fig. 2A, pre-OGD = 0.4 ± 0.04, post-OGD = 0.3 ± 0.03, n = 7, p < 0.005). However, the PICK1-specific pep2-EVKI completely blocked the decrease in the rectification index (Fig. 2B, pre-OGD = 0.33 ± 0.02, post-OGD = 0.36 ± 0.02, n = 6, p = 0.46). Surprisingly, pep2-SVKI, which blocks both PICK1 and ABP/GRIP PDZ domains, did not completely block the decrease in the rectification index (Fig. 2C, pre-OGD = 0.42 ± 0.04, post-OGD = 0.37 ± 0.03, n = 6, p < 0.05).

Bottom Line: Using biochemical and electrophysiological approaches, we show that peptides that interfere with PICK1 PDZ domain interactions block the OGD-induced switch in subunit composition, implicating PICK1 in restricting GluR2 from synapses during OGD.Furthermore, we show that GluR2-lacking AMPARs that arise at synapses during OGD as a result of PICK1 PDZ interactions are involved in OGD-induced delayed cell death.This work demonstrates that PICK1 plays a crucial role in the response to OGD that results in altered synaptic transmission and neuronal death and has implications for our understanding of the molecular mechanisms that underlie cell death during stroke.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council (MRC) Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.

ABSTRACT
Oxygen and glucose deprivation (OGD) induces delayed cell death in hippocampal CA1 neurons via Ca(2+)/Zn(2+)-permeable, GluR2-lacking AMPA receptors (AMPARs). Following OGD, synaptic AMPAR currents in hippocampal neurons show marked inward rectification and increased sensitivity to channel blockers selective for GluR2-lacking AMPARs. This occurs via two mechanisms: a delayed down-regulation of GluR2 mRNA expression and a rapid internalization of GluR2-containing AMPARs during the OGD insult, which are replaced by GluR2-lacking receptors. The mechanisms that underlie this rapid change in subunit composition are unknown. Here, we demonstrate that this trafficking event shares features in common with events that mediate long term depression and long term potentiation and is initiated by the activation of N-methyl-d-aspartic acid receptors. Using biochemical and electrophysiological approaches, we show that peptides that interfere with PICK1 PDZ domain interactions block the OGD-induced switch in subunit composition, implicating PICK1 in restricting GluR2 from synapses during OGD. Furthermore, we show that GluR2-lacking AMPARs that arise at synapses during OGD as a result of PICK1 PDZ interactions are involved in OGD-induced delayed cell death. This work demonstrates that PICK1 plays a crucial role in the response to OGD that results in altered synaptic transmission and neuronal death and has implications for our understanding of the molecular mechanisms that underlie cell death during stroke.

Show MeSH
Related in: MedlinePlus