Functional regulation of metabotropic glutamate receptor type 1c: a role for phosphorylation in the desensitization of the receptor

Ciruela, Francisco; Giacometti, A.; McIlhinney, R. A. Jeffrey

doi:10.1016/s0014-5793(99)01547-1

Cited by 19 publications

(24 citation statements)

References 32 publications

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“…PKC is an important modulator of mGluR function (10,(13)(14)(15)(16)(17); however, the biochemical analyses characterizing the direct phosphorylation of mGluRs by PKC have been lacking. Therefore, we began to characterize the mGluR5 C terminus as the region most likely to contain PKC phosphorylation sites.…”

Section: Resultsmentioning

confidence: 99%

Protein Kinase C Phosphorylation of the Metabotropic Glutamate ReceptormGluR5 on Serine 839 Regulates Ca2+Oscillations

Kim

Braud

Isaac

et al. 2005

Journal of Biological Chemistry

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The activation of Group 1 metabotropic glutamate receptors, mGluR5 and mGluR1␣, triggers intracellular calcium release; however, mGluR5 activation is unique in that it elicits Ca 2؉ oscillations. A short region of the mGluR5 C terminus is the critical determinant and differs from the analogous region of mGluR1␣ by a single amino acid residue, Thr-840, which is an aspartic acid (Asp-854) in mGluR1␣. Previous studies show that mGluR5-elicited Ca 2؉ oscillations require protein kinase C (PKC)-dependent phosphorylation and identify Thr-840 as the phosphorylation site. However, direct phosphorylation of mGluR5 has not been studied in detail. We have used biochemical analyses to directly investigate the phosphorylation of the mGluR5 C terminus. We showed that Ser-839 on mGluR5 is directly phosphorylated by PKC, whereas Thr-840 plays a permissive role. Although Ser-839 is conserved in mGluR1␣ (Ser-853), it is not phosphorylated, as the adjacent residue (Asp-854) is not permissive; however, mutagenesis of Asp-854 to a permissive alanine residue allows phosphorylation of Ser-853 on mGluR1␣. We investigated the physiological consequences of mGluR5 Ser-839 phosphorylation using Ca 2؉ imaging. Mutations that eliminate Ser-839 phosphorylation prevent the characteristic mGluR5-dependent Ca 2؉ oscillations. However, mutation of Thr-840 to alanine, which prevents potential Thr-840 phosphorylation but is still permissive for Ser-839 phosphorylation, has no effect on Ca 2؉ oscillations. Thus, we showed that it is phosphorylation of Ser-839, not Thr-840, that is absolutely required for the unique Ca 2؉ oscillations produced by mGluR5 activation. The Thr-840 residue is important only in that it is permissive for the PKC-dependent phosphorylation of Ser-839. Metabotropic glutamate receptors (mGluRs)1 play important roles throughout the nervous system, including the activation of ion channels and the regulation of synaptic plasticity (1). In addition, they have been implicated in a variety of neurological diseases (2-5). There are eight different mGluRs, and these are subdivided into three groups based on sequence identity and pharmacological properties. Group 1 mGluRs (mGluR1 and mGluR5) are linked to phospholipase C, whereas Group 2 mGluRs (mGluR2 and mGluR3) and Group 3 mGluRs (mGluR4, mGluR6, mGluR7, and mGluR8) are negatively linked to adenylate cyclase. Activation of Group 1 mGluRs triggers phospholipase C, resulting in increases in IP 3 and diacylglycerol production and the concomitant release of intracellular Ca 2ϩ and activation of protein kinase C (PKC) (6). Group 1 mGluR-elicited Ca 2ϩ release stimulates PKC translocation to the plasma membrane and oscillations of both PKC activation and IP 3 production (7, 8).Although both mGluR1 and mGluR5 stimulate intracellular Ca 2ϩ release, they differ in that mGluR5 activation results in Ca 2ϩ oscillations, whereas mGluR1 activation results in a single Ca 2ϩ transient with or without subsequent low frequency oscillations (9, 10). A previous study (10) demonstrated that a short stret...

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Section: Resultsmentioning

confidence: 99%

Protein Kinase C Phosphorylation of the Metabotropic Glutamate ReceptormGluR5 on Serine 839 Regulates Ca2+Oscillations

Kim

Braud

Isaac

et al. 2005

Journal of Biological Chemistry

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“…For example, activation of PKC by PMA induces a rapid loss of mGluR1a and -1b from the cell surface in BHK cells (Ciruela and McIlhinney, 1997). In addition, mGluR1c desensitizes in response to PKC phosphorylation (Ciruela et al, 1999). An- Fig.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to agonist-specific receptor desensitization, GPCR function can be regulated by agonist-independent heterologous mechanisms. For example, recent studies have demonstrated that protein kinase C (PKC) phosphorylates and regulates the desensitization and internalization of mGluR1a, -1b, and -1c (Ciruela and McIlhinney, 1997;Ciruela et al, 1999).…”

mentioning

confidence: 99%

Metabotropic Glutamate Receptor 1 Internalization Induced by Muscarinic Acetylcholine Receptor Activation: Differential Dependency of Internalization of Splice Variants on Nonvisual Arrestins

et al. 2002

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In this study, we characterized the glutamate-or second-messenger kinase-dependent internalization of the rat metabotropic glutamate receptor 1 (mGluR1) splice variants 1a, 1b, and 1c, and assessed the arrestin and dynamin dependence of these processes. To facilitate this we inserted a hemagglutinin epitope tag in the extracellular N-terminal domain of the splice variants. Quantification of glutamate-induced mGluR1 splice variant internalization provided by enzyme-linked immunosorbent assay and confirmed by immunofluorescent microscopy indicated that each splice variant underwent rapid internalization, which was strongly inhibited by coexpression of dominant-negative mutant (DNM) arrestin or dynamin. In addition glutamate-induced rapid translocation of arrestin-2-green fluorescent protein (GFP) or arrestin-3-GFP from cytosol to membrane was observed in cells expressing mGluR1 splice variants. Glutamate-induced internalization of mGluR1a and mGluR1c was partially blocked by a selective inhibitor of protein kinase C (PKC), 2-[1-(3-dimethylamino-propyl)indol-3-yl]-3-(1H-indol-3-yl)maleimide (GF 109203X), whereas mGluR1b internalization was not significantly affected by this inhibitor. Similarly, inositol phosphate production after glutamate-induced activation of mGluR1a and mGluR1c was increased after PKC inhibition, whereas glutamate-induced mGluR1b stimulation was unaffected. Activation by carbachol of endogenously expressed M 1 muscarinic receptors in human embryonic kidney 293 cells, induced the internalization of mGluR1 splice variants, which was partially blocked by pretreatment with inhibitors of either PKC or Ca 2ϩ calmodulin-dependent kinase II (CaMKII). Expression of DNM-arrestin with mGluR1a or 1c strongly inhibited carbachol-induced internalization. However, coexpression of DNM-arrestin with mGluR1b was less effective in reducing carbachol-induced receptor internalization. In addition, arrestin-2-GFP or arrestin-3-GFP underwent significant carbacholinduced translocation from cytosol to membrane in cells coexpressing mGluR1a or 1c but not in cells coexpressing mGluR1b. This study demonstrates that the internalization of mGluR1 splice variants is subject to PKC and CaMKII regulation. In addition, regulation by these kinases confers differential arrestin dependence.Glutamate is the major excitatory neurotransmitter in the central nervous system and acts through ionotropic and metabotropic glutamate receptors (mGluR). Whereas ionotropic receptors drive fast neurotransmission, the stimulation of mGluRs generates slower and longer lasting changes in the signaling cascades activated in neuronal and glial cells, which may play a critical role in glutamate-mediated neurotransmission and synaptic plasticity events (for review, see Schoepp et al., 1999). Sequence analysis shows that mGluRs are members of a distinct G-protein-coupled receptor (GPCR) superfamily that shows little similarity to classic GPCRs such as rhodopsin and ␤-adrenoceptors. Other members in this subfamily of GPCRs are the ␥-aminobutyric...

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Section: Introductionmentioning

confidence: 99%

“…This event seems to include a rapid component that may involve activation of protein kinase C (Catania et al, 1991;Thomsen et al, 1993;Alaluf et al, 1995;Ciruela et al, 1999a) and receptor internalization (Ciruela and McIlhinney, 1997;Doherty et al, 1999) and a slower, protein kinase C-independent component (Catania et al, 1991;Desai et al, 1996). Down-regulation of receptor protein expression has been suggested to play a role in the latter process, because in cultured cerebellar granule cells, desensitization of the mGlu1 receptor has been shown to result in reduced levels of mGlu1 receptor mRNA upon exposure to glutamate or quisqualate or in the presence of high K ϩ concentration (Favaron et al, 1992;Aronica et al, 1993;Bessho et al, 1993).…”

mentioning

confidence: 99%

Supersensitivity of Human Metabotropic Glutamate 1a Receptor Signaling in L929sA Cells

Lavreysen¹,

Poul²,

Gompel³

et al. 2002

Mol Pharmacol

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The effect of antagonist pretreatment on the signaling properties of the human metabotropic glutamate 1a (hmGlu1a) receptor was examined in stably transfected L929sA cells. Pre-exposure of hmGlu1a receptor-expressing cells to the mGlu1 receptor antagonists (S)-4-carboxy-3-hydroxyphenylglycine and 7-(hydroxyimino)cyclo-propa[b]chromen-1a-carboxylate ethyl ester dramatically enhanced subsequent glutamate-induced phosphoinositide hydrolysis and intracellular [Ca 2ϩ ] rise. We found clear indications that the antagonist-mediated enhancement of glutamate-evoked mGlu1a receptor signaling is caused by the development of mGlu1a receptor supersensitivity: the potency of glutamate was increased by 3-fold after 24 h antagonist pretreatment and the potency of the antagonists was significantly decreased in antagonist-pretreated cells. The kinetic profile of the antagonist-mediated enhancement showed that the maximal increase in intracellular [Ca 2ϩ ] was already reached after 30-min pretreatment, suggesting that de novo receptor synthesis is not involved in the process of mGlu1a receptor supersensitization. Glutamate-mediated phosphoinositide hydrolysis increased up to 24 h after antagonist treatment. Although it seemed likely that the hmGlu1a receptor could desensitize after activation by endogenously present glutamate, removal of glutamate from the extracellular medium with GPT resulted in a much smaller enhancement of glutamate responsiveness. Moreover, the magnitude of antagonist-mediated receptor supersensitivity was much larger than the magnitude of agonist-induced receptor desensitization. These results suggest that antagonist-evoked mGlu1 receptor supersensitivity is not merely the result of a blockade of agonist-induced desensitization. Finally, we found that antagonist pretreatment doubled the amount of receptors at the cell surface. Our findings are the first lines of evidence that prolonged antagonist treatment can supersensitize the hmGlu1a receptor. In view of the potential therapeutic application of mGlu1 receptor antagonists, it will be important to know whether these phenomena occur in vivo.So far, eight subtypes of the family of mGlu receptors have been cloned (mGlu1 to mGlu8 receptors). These receptors can be further subdivided into three groups based on their amino acid sequence homology, signal transduction mechanisms, and pharmacological profiles. Group I mGlu receptors consist of subtypes 1 and 5. Splice variants have been found for both the mGlu1 receptor (mGlu1a to mGlu1f receptor) and mGlu5 receptor (mGlu5a, mGlu5b, and mGlu5d receptors). Stimulation of group I mGlu receptors activates phosphoinositide hydrolysis, giving rise to the generation of the intracellular messengers diacylglycerol and inositol trisphosphate. This coupling in turn results in protein kinase C activation and Ca 2ϩ mobilization from the endoplasmic reticulum (Aramori and Nakanishi, 1992). Group II (mGlu2 and mGlu3 receptor) and group III mGlu receptors (mGlu4, -6, -7, and -8 receptors) both inhibit adenylate cyclase...

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Functional regulation of metabotropic glutamate receptor type 1c: a role for phosphorylation in the desensitization of the receptor

Cited by 19 publications

References 32 publications

Protein Kinase C Phosphorylation of the Metabotropic Glutamate ReceptormGluR5 on Serine 839 Regulates Ca2+Oscillations

Protein Kinase C Phosphorylation of the Metabotropic Glutamate ReceptormGluR5 on Serine 839 Regulates Ca2+Oscillations

Metabotropic Glutamate Receptor 1 Internalization Induced by Muscarinic Acetylcholine Receptor Activation: Differential Dependency of Internalization of Splice Variants on Nonvisual Arrestins

Supersensitivity of Human Metabotropic Glutamate 1a Receptor Signaling in L929sA Cells

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