title: Purinergic receptor activation facilitates astrocytic GABAB receptor calcium signalling.
abstract: Gamma-aminobutyric acid B receptors (GABABRs) are heterodimeric G-protein coupled receptors, which mediate slow synaptic inhibition in the brain. Emerging evidence suggests astrocytes also express GABABRs, although their physiological significance remains unknown. To begin addressing this issue, we have used imaging and biochemical analysis to examine the role GABABRs play in regulating astrocytic Ca(2+) signalling. Using live imaging of cultured cortical astrocytes loaded with calcium indicator Fluo-4/AM, we found that astrocytic GABABRs are able to induce astrocytic calcium transients only if they are pre-activated by P2 purinoceptors (P2YRs). The GABABR-mediated calcium transients were attenuated by the removal of extracellular calcium. Furthermore, P2YRs enhance the phosphorylation of astrocytic GABABR R2 subunits on both serine 783 (S783) and serine 892 (S892), two phosphorylation sites that are well known to regulate the activity and the cell surface stability of GABABRs. Collectively these results suggest that P2YR mediated signalling is an important determinant of GABABR activity and phosphorylation in astrocytes.
authors.affiliation: Department of Cell Physiology and Pharmacology, College of Medicine, Biological Sciences and Psychology, University of Leicester, University Road, Leicester LE1 9HN, UK. Electronic address: mt304@leicester.ac.uk.
authors.forename: Miho
authors.initials: M
authors.lastname: Terunuma
authors.affiliation: Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Philip G
authors.initials: PG
authors.lastname: Haydon
authors.affiliation: Innovative Medicines, AstraZeneca, Mereside, Alderley Park, Cheshire SK10 4TG, UK.
authors.forename: Menelas N
authors.initials: MN
authors.lastname: Pangalos
authors.affiliation: Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA; Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, UK. Electronic address: Stephen.Moss@tufts.edu.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Moss
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D001418:Baclofen / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D058786:GABA-B Receptor Agonists / Q000494:pharmacology; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D058919:Purinergic P2 Receptor Antagonists / Q000494:pharmacology; D018080:Receptors, GABA-B / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*
chemical_list: D058786:GABA-B Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018080:Receptors, GABA-B; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D037342:Pertussis Toxin; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D001418:Baclofen; D002118:Calcium
keywords: Astrocytes; Calcium; GABAB receptors; Phosphorylation