NMDA-induced potentiation of mGluR5 is mediated by activation of protein phosphatase 2B/calcineurin

• Published in: Neuropharmacology 2005, Vol.49 (1), p.135-145
• Main Authors: Alagarsamy, Sudar, Saugstad, Julie, Warren, Lee, Mansuy, Isabelle M., Gereau, Robert W., Conn, P. Jeffrey
• Format: Article
• Language: English
• Subjects: Animals; Autoradiography - methods; Brain - drug effects; Brain - enzymology; Calcineurin - metabolism; Calcineurin - pharmacology; CHO Cells - drug effects; CHO Cells - enzymology; Cricetinae; Cricetulus; Dose-Response Relationship, Drug; Drug Synergism; Electric Stimulation - methods; Enzyme Activation - drug effects; Enzyme Inhibitors - pharmacology; Excitatory Amino Acid Agonists - pharmacology; Glutamate; Glutamic Acid - pharmacology; Glutathione Transferase; Hydroxylation - drug effects; Immunoblotting - methods; Immunoprecipitation - methods; LTD; LTP; Membrane Potentials - drug effects; Membrane Potentials - physiology; Membrane Potentials - radiation effects; Metabotropic; Methoxyhydroxyphenylglycol - analogs & derivatives; Methoxyhydroxyphenylglycol - pharmacology; Mutagenesis - physiology; N-Methylaspartate - pharmacology; Okadaic Acid - pharmacology; Oocytes - drug effects; Oocytes - enzymology; Patch-Clamp Techniques - methods; Phosphatidylinositols - metabolism; PKC; Plasticity; Protein Kinase C - pharmacology; Rats; Receptor, Metabotropic Glutamate 5; Receptors, Metabotropic Glutamate - drug effects; Receptors, Metabotropic Glutamate - genetics; Receptors, Metabotropic Glutamate - metabolism; Transfection; Xenopus
• ISSN: 0028-3908; 1873-7064
• DOI: 10.1016/j.neuropharm.2005.05.005

Previous reports have shown that activation of N-methyl- d-aspartate (NMDA) receptors potentiates responses to activation of the group I metabotropic glutamate receptor mGluR5 by reversing PKC-mediated desensitization of this receptor. NMDA-induced reversal of mGluR5 desensitization is dependent on activation of protein phosphatases. However, the specific protein phosphatase involved and the precise mechanism by which NMDA receptor activation reduces mGluR desensitization are not known. We have performed a series of molecular, biochemical, and genetic studies to show that NMDA-induced regulation of mGluR5 is dependent on activation of calcium-dependent protein phosphatase 2B/calcineurin (PP2B/CaN). Furthermore, we report that purified calcineurin directly dephosphorylates the C-terminal tail of mGluR5 at sites that are phosphorylated by PKC. Finally, immunoprecipitation and GST fusion protein pull-down experiments reveal that calcineurin interacts with mGluR5, suggesting that these proteins could be colocalized in a signaling complex. Taken together with previous studies, these data suggest that activation of NMDA receptors leads to activation of calcineurin and that calcineurin modulates mGluR5 function by directly dephosphorylating mGluR5 at PKC sites that are involved in desensitization of this receptor.