| Autor: |
Mundell SJ; Department of Pharmacology, School of Medical Sciences, University of Bristol, Bristol, United Kingdom., Pula G, More JC, Jane DE, Roberts PJ, Kelly E |
| Jazyk: |
angličtina |
| Zdroj: |
Molecular pharmacology [Mol Pharmacol] 2004 Jun; Vol. 65 (6), pp. 1507-16. |
| DOI: |
10.1124/mol.65.6.1507 |
| Abstrakt: |
In this study, we characterized the effects of activation of cyclic AMP-dependent protein kinase (PKA) on the internalization and functional coupling of the metabotropic glutamate receptor (mGluR1) splice variants mGluR1a and mGluR1b. Using an enzyme-linked immunosorbent assay technique to assess receptor internalization, we found that the glutamate-induced internalization of mGluR1a or mGluR1b transiently expressed in human embryonic kidney (HEK) 293 cells was inhibited by coactivation of endogenous beta2-adrenoceptors with isoprenaline or by direct activation of adenylyl cyclase with forskolin. The PKA inhibitor N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide hydrochloride (H89) blocked the effects of both isoprenaline and forskolin. The heterologous internalization of the mGluR1 splice variants triggered by carbachol was also inhibited by isoprenaline and forskolin in a PKA-sensitive fashion, whereas the constitutive (agonist-independent) internalization of mGluR1a was inhibited only modestly by PKA activation. Using inositol phosphate (IP) accumulation in cells prelabeled with [3H]inositol to assess receptor coupling, PKA activation increased basal IP accumulation in mGluR1a receptor-expressing cells and also increased glutamate-stimulated IP accumulation in both mGluR1a- and mGluR1b-expressing cells, but only at short times of glutamate addition. Furthermore, PKA activation completely blocked the carbachol-induced heterologous desensitization of glutamate-stimulated IP accumulation in both mGluR1a- and mGluR1b-expressing cells. In coimmunoprecipitation experiments, the ability of glutamate to increase association of GRK2 and arrestin-2 with mGluR1a and mGluR1b was inhibited by PKA activation with forskolin. Together, these results indicate that PKA activation inhibits the agonist-induced internalization and desensitization of mGluR1a and mGluR1b, probably by reducing their interaction with GRK2 and nonvisual arrestins. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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