title: P2Y12 receptor stimulation inhibits beta-adrenergic receptor-induced differentiation by reversing the cyclic AMP-dependent inhibition of protein kinase B.
abstract: Cyclic AMP-dependent induction of differentiation by activation of the beta-adrenergic receptor is correlated with inhibition of protein kinase B activity concomitant with growth arrest and increase in glial fibrillary acidic protein (GFAP) synthesis in rat C6 glioma cells. Costimulation of the beta-adrenergic receptor with purinergic receptors activated by 2-methylthio-adenosine-5'-diphosphate (2MeSADP) increased protein kinase B (PKB) phosphorylation above the level measured in non-stimulated cells and abolished cAMP-dependent differentiation. Transfection of cells with constitutively active PKB confirmed that reactivation of PKB is involved in the 2MeSADP-dependent inhibition of GFAP synthesis. The P2Y(12) and P2Y(13) receptor antagonist AR-C69931MX [N(6)-(2-methylthioethyl)-2-(3,3,3-trifluoropropylthio)-beta,gamma-dichloro-methylene ATP] decreased PKB phosphorylation to the level in non-stimulated cells, whereas the P2Y(13) antagonists pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) and P(1),P(3)-di(adenosine-5') tetraphosphate (Ap(4)A) did not alter the 2MeSADP-induced phosphorylation of PKB, showing that enhanced PKB activity and subsequent phosphorylation of glycogen synthase kinase-3 is due to stimulation of the P2Y(12) receptor. In addition, experiments in the presence of pertussis toxin and phosphatidylinositol 3-kinase (PI 3-K) activity assays demonstrated that the P2Y(12) receptor-mediated increase in PKB phosphorylation is G(i) protein- and PI 3-K-dependent. The presented data demonstrated that a cAMP-dependent inhibition of PKB induces differentiation of C6 glioma cells and that inhibition of adenylate cyclase and reactivation of the PI 3-K/PKB pathway by the P2Y(12) receptor reverses differentiation into enhanced proliferation.
authors.affiliation: Laboratory of Cellular Biochemistry, Department of Biomedical Sciences, University of Antwerp, Wilrijk-Antwerpen, Belgium.
authors.forename: Kristof
authors.initials: K
authors.lastname: Van Kolen
authors.forename: Herman
authors.initials: H
authors.lastname: Slegers
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000187:drug effects / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis; D005910:Glioma / Q000188:drug therapy / Q000378:metabolism*; D008565:Membrane Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058925:Receptors, Purinergic P2Y12; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D000244:Adenosine Diphosphate; D000249:Adenosine Monophosphate; D000067956:Adenylyl Cyclase Inhibitors; D000318:Adrenergic beta-Agonists; D000242:Cyclic AMP; D004791:Enzyme Inhibitors; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D005904:Glial Fibrillary Acidic Protein; D008565:Membrane Proteins; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011943:Receptors, Adrenergic, beta; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D013873:Thionucleotides; C553058:P2ry12 protein, rat; C486690:P2ry13 protein, rat; C002480:methylthio-ADP; C117446:cangrelor