Desensitization and Internalization of Metabotropic Glutamate Receptor 1a Following Activation of Heterologous Gq/11-Coupled Receptors

Stuart J Mundell, Giordano Pula, R A Jeffrey McIlhinney, Peter J Roberts, Eamonn Kelly

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Abstract

In this study we characterized the heterologous desensitization and internalization of the metabotropic glutamate receptor 1 (mGluR1) splice variants mGluR1a and mGluR1b following activation of endogenous Gq/11-coupled receptors in HEK293 cells. Agonist activation of M1 muscarinic acetylcholine or P2Y1 purinergic receptors triggered the PKC- and CaMKII-dependent internalization of mGluR1a. In co-immunoprecipitation studies, both glutamate and carbachol increased the association of GRK2 with mGluR1a. Co-addition of the protein kinase C (PKC) inhibitor GF109203X and the Ca2+ calmodulin-dependent kinase II (CaMKII) inhibitor KN-93 blocked the ability of glutamate and carbachol to increase the association of GRK2 with mGluR1a. Glutamate also increased the association of GRK2 with mGluR1b, whereas carbachol did not. However, unlike mGluR1a, glutamate-stimulated association of GRK2 with mGluR1b was not reduced by PKC/CaMKII inhibition. Pretreatment of cells expressing mGluR1a or mGluR1b with carbachol rapidly desensitized subsequent glutamate-stimulated inositol phosphate accumulation. The carbachol-induced heterologous desensitization and internalization of mGluR1a was blocked by LY367385, an mGluR1a antagonist with inverse agonist activity. Furthermore, LY367385 blocked the ability of carbachol to increase the association of GRK2 with mGluR1a. On the other hand, LY367385 had no effect on the carbachol-induced desensitization and internalization of the nonconstitutively active mGluR1b splice variant. These results demonstrate that the internalization of mGluR1a, triggered homologously by glutamate or heterologously by carbachol, is PKC/CaMKII-, GRK2-, arrestin-, and clathrin-dependent and that PKC/CaMKII activation appears to be necessary for GRK2 to associate with mGluR1a. Furthermore, the heterologous desensitization of mGluR1a is dependent upon the splice variant being in an active conformation.
Original languageEnglish
Pages (from-to)7541-7551
Number of pages11
JournalBiochemistry
Volume43
Issue number23
DOIs
Publication statusPublished - 2004

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Metabotropic Glutamate Receptors
Chemical activation
Carbachol
Calcium-Calmodulin-Dependent Protein Kinases
alpha-methyl-4-carboxyphenylglycine
Calmodulin
Glutamic Acid
Protein Kinase C
Phosphotransferases
Association reactions
metabotropic glutamate receptor type 1
Purinergic P2Y1 Receptors
Arrestin
Clathrin
Inositol Phosphates
Protein C Inhibitor
HEK293 Cells
Protein Kinase Inhibitors
Immunoprecipitation
Cholinergic Agents

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Desensitization and Internalization of Metabotropic Glutamate Receptor 1a Following Activation of Heterologous Gq/11-Coupled Receptors. / Mundell, Stuart J; Pula, Giordano; McIlhinney, R A Jeffrey; Roberts, Peter J; Kelly, Eamonn.

In: Biochemistry, Vol. 43, No. 23, 2004, p. 7541-7551.

Research output: Contribution to journalArticle

Mundell, Stuart J ; Pula, Giordano ; McIlhinney, R A Jeffrey ; Roberts, Peter J ; Kelly, Eamonn. / Desensitization and Internalization of Metabotropic Glutamate Receptor 1a Following Activation of Heterologous Gq/11-Coupled Receptors. In: Biochemistry. 2004 ; Vol. 43, No. 23. pp. 7541-7551.
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T1 - Desensitization and Internalization of Metabotropic Glutamate Receptor 1a Following Activation of Heterologous Gq/11-Coupled Receptors

AU - Mundell, Stuart J

AU - Pula, Giordano

AU - McIlhinney, R A Jeffrey

AU - Roberts, Peter J

AU - Kelly, Eamonn

PY - 2004

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N2 - In this study we characterized the heterologous desensitization and internalization of the metabotropic glutamate receptor 1 (mGluR1) splice variants mGluR1a and mGluR1b following activation of endogenous Gq/11-coupled receptors in HEK293 cells. Agonist activation of M1 muscarinic acetylcholine or P2Y1 purinergic receptors triggered the PKC- and CaMKII-dependent internalization of mGluR1a. In co-immunoprecipitation studies, both glutamate and carbachol increased the association of GRK2 with mGluR1a. Co-addition of the protein kinase C (PKC) inhibitor GF109203X and the Ca2+ calmodulin-dependent kinase II (CaMKII) inhibitor KN-93 blocked the ability of glutamate and carbachol to increase the association of GRK2 with mGluR1a. Glutamate also increased the association of GRK2 with mGluR1b, whereas carbachol did not. However, unlike mGluR1a, glutamate-stimulated association of GRK2 with mGluR1b was not reduced by PKC/CaMKII inhibition. Pretreatment of cells expressing mGluR1a or mGluR1b with carbachol rapidly desensitized subsequent glutamate-stimulated inositol phosphate accumulation. The carbachol-induced heterologous desensitization and internalization of mGluR1a was blocked by LY367385, an mGluR1a antagonist with inverse agonist activity. Furthermore, LY367385 blocked the ability of carbachol to increase the association of GRK2 with mGluR1a. On the other hand, LY367385 had no effect on the carbachol-induced desensitization and internalization of the nonconstitutively active mGluR1b splice variant. These results demonstrate that the internalization of mGluR1a, triggered homologously by glutamate or heterologously by carbachol, is PKC/CaMKII-, GRK2-, arrestin-, and clathrin-dependent and that PKC/CaMKII activation appears to be necessary for GRK2 to associate with mGluR1a. Furthermore, the heterologous desensitization of mGluR1a is dependent upon the splice variant being in an active conformation.

AB - In this study we characterized the heterologous desensitization and internalization of the metabotropic glutamate receptor 1 (mGluR1) splice variants mGluR1a and mGluR1b following activation of endogenous Gq/11-coupled receptors in HEK293 cells. Agonist activation of M1 muscarinic acetylcholine or P2Y1 purinergic receptors triggered the PKC- and CaMKII-dependent internalization of mGluR1a. In co-immunoprecipitation studies, both glutamate and carbachol increased the association of GRK2 with mGluR1a. Co-addition of the protein kinase C (PKC) inhibitor GF109203X and the Ca2+ calmodulin-dependent kinase II (CaMKII) inhibitor KN-93 blocked the ability of glutamate and carbachol to increase the association of GRK2 with mGluR1a. Glutamate also increased the association of GRK2 with mGluR1b, whereas carbachol did not. However, unlike mGluR1a, glutamate-stimulated association of GRK2 with mGluR1b was not reduced by PKC/CaMKII inhibition. Pretreatment of cells expressing mGluR1a or mGluR1b with carbachol rapidly desensitized subsequent glutamate-stimulated inositol phosphate accumulation. The carbachol-induced heterologous desensitization and internalization of mGluR1a was blocked by LY367385, an mGluR1a antagonist with inverse agonist activity. Furthermore, LY367385 blocked the ability of carbachol to increase the association of GRK2 with mGluR1a. On the other hand, LY367385 had no effect on the carbachol-induced desensitization and internalization of the nonconstitutively active mGluR1b splice variant. These results demonstrate that the internalization of mGluR1a, triggered homologously by glutamate or heterologously by carbachol, is PKC/CaMKII-, GRK2-, arrestin-, and clathrin-dependent and that PKC/CaMKII activation appears to be necessary for GRK2 to associate with mGluR1a. Furthermore, the heterologous desensitization of mGluR1a is dependent upon the splice variant being in an active conformation.

UR - http://dx.doi.org/10.1021/bi0359022

U2 - 10.1021/bi0359022

DO - 10.1021/bi0359022

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VL - 43

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JF - Biochemistry

SN - 0006-2960

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