Agonist occupancy is essential for forward trafficking of AMPA receptors

Sarah Kate Coleman, Tommi Möykkynen, Annukka Jouppila, Susanna Koskelainen, Claudio Rivera, Esa R Korpi, Kari Keinänen

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Regulated trafficking of AMPA receptors to cell surface and to synapses is an important determinant of neuronal excitability. In the present study, we have addressed the role of agonist binding and desensitization in the early trafficking of glutamate receptor-D (GluR-D) AMPA receptors. Analysis of point-mutated GluR-D receptors, via electrophysiology and immunofluorescence, revealed that agonist-binding activity is essential for efficient delivery to cell surface in transfected cell lines and in neurons. Cotransfection with stargazin could fully rescue the surface expression of nonbinding mutant receptors in cell lines, indicating that stargazin is able to interact with and promote exit of AMPA receptors from endoplasmic reticulum ( ER) independently of agonist binding. Secretion of separately expressed ligand-binding domain constructs showed a similar dependency of agonist binding to that observed with full-length GluR-D, supporting the idea that glutamate-induced closure of the binding site cleft is registered by ER quality control as a necessary priming step for transport competence. In contrast to agonist binding, the ability of the receptor to undergo desensitization had only a minor influence on trafficking. Our results are consistent with the hypothesis that AMPA receptors are synthesized as intrinsically unstable molecules, which require glutamate binding for structural stability and for transport-competence.
Original languageEnglish
JournalJournal of Neuroscience
Volume29
Issue number2
Pages (from-to)303-312
Number of pages10
ISSN0270-6474
DOIs
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 311 Basic medicine

Cite this

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title = "Agonist occupancy is essential for forward trafficking of AMPA receptors",
abstract = "Regulated trafficking of AMPA receptors to cell surface and to synapses is an important determinant of neuronal excitability. In the present study, we have addressed the role of agonist binding and desensitization in the early trafficking of glutamate receptor-D (GluR-D) AMPA receptors. Analysis of point-mutated GluR-D receptors, via electrophysiology and immunofluorescence, revealed that agonist-binding activity is essential for efficient delivery to cell surface in transfected cell lines and in neurons. Cotransfection with stargazin could fully rescue the surface expression of nonbinding mutant receptors in cell lines, indicating that stargazin is able to interact with and promote exit of AMPA receptors from endoplasmic reticulum ( ER) independently of agonist binding. Secretion of separately expressed ligand-binding domain constructs showed a similar dependency of agonist binding to that observed with full-length GluR-D, supporting the idea that glutamate-induced closure of the binding site cleft is registered by ER quality control as a necessary priming step for transport competence. In contrast to agonist binding, the ability of the receptor to undergo desensitization had only a minor influence on trafficking. Our results are consistent with the hypothesis that AMPA receptors are synthesized as intrinsically unstable molecules, which require glutamate binding for structural stability and for transport-competence.",
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author = "Coleman, {Sarah Kate} and Tommi M{\"o}ykkynen and Annukka Jouppila and Susanna Koskelainen and Claudio Rivera and Korpi, {Esa R} and Kari Kein{\"a}nen",
year = "2009",
doi = "10.1523/JNEUROSCI.3953-08.2009",
language = "English",
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Agonist occupancy is essential for forward trafficking of AMPA receptors. / Coleman, Sarah Kate; Möykkynen, Tommi; Jouppila, Annukka; Koskelainen, Susanna; Rivera, Claudio; Korpi, Esa R; Keinänen, Kari.

In: Journal of Neuroscience, Vol. 29, No. 2, 2009, p. 303-312.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Agonist occupancy is essential for forward trafficking of AMPA receptors

AU - Coleman, Sarah Kate

AU - Möykkynen, Tommi

AU - Jouppila, Annukka

AU - Koskelainen, Susanna

AU - Rivera, Claudio

AU - Korpi, Esa R

AU - Keinänen, Kari

PY - 2009

Y1 - 2009

N2 - Regulated trafficking of AMPA receptors to cell surface and to synapses is an important determinant of neuronal excitability. In the present study, we have addressed the role of agonist binding and desensitization in the early trafficking of glutamate receptor-D (GluR-D) AMPA receptors. Analysis of point-mutated GluR-D receptors, via electrophysiology and immunofluorescence, revealed that agonist-binding activity is essential for efficient delivery to cell surface in transfected cell lines and in neurons. Cotransfection with stargazin could fully rescue the surface expression of nonbinding mutant receptors in cell lines, indicating that stargazin is able to interact with and promote exit of AMPA receptors from endoplasmic reticulum ( ER) independently of agonist binding. Secretion of separately expressed ligand-binding domain constructs showed a similar dependency of agonist binding to that observed with full-length GluR-D, supporting the idea that glutamate-induced closure of the binding site cleft is registered by ER quality control as a necessary priming step for transport competence. In contrast to agonist binding, the ability of the receptor to undergo desensitization had only a minor influence on trafficking. Our results are consistent with the hypothesis that AMPA receptors are synthesized as intrinsically unstable molecules, which require glutamate binding for structural stability and for transport-competence.

AB - Regulated trafficking of AMPA receptors to cell surface and to synapses is an important determinant of neuronal excitability. In the present study, we have addressed the role of agonist binding and desensitization in the early trafficking of glutamate receptor-D (GluR-D) AMPA receptors. Analysis of point-mutated GluR-D receptors, via electrophysiology and immunofluorescence, revealed that agonist-binding activity is essential for efficient delivery to cell surface in transfected cell lines and in neurons. Cotransfection with stargazin could fully rescue the surface expression of nonbinding mutant receptors in cell lines, indicating that stargazin is able to interact with and promote exit of AMPA receptors from endoplasmic reticulum ( ER) independently of agonist binding. Secretion of separately expressed ligand-binding domain constructs showed a similar dependency of agonist binding to that observed with full-length GluR-D, supporting the idea that glutamate-induced closure of the binding site cleft is registered by ER quality control as a necessary priming step for transport competence. In contrast to agonist binding, the ability of the receptor to undergo desensitization had only a minor influence on trafficking. Our results are consistent with the hypothesis that AMPA receptors are synthesized as intrinsically unstable molecules, which require glutamate binding for structural stability and for transport-competence.

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