title: Expression of purinergic P2Y receptor subtypes by INS-1 insulinoma beta-cells: a molecular and binding characterization.
abstract: Purinergic P2Y-receptor agonists amplify glucose-induced insulin secretion from pancreatic beta-cells, thus offering new opportunities for the treatment of type 2 diabetes. However, little is known about which subtypes of purinergic P2Y receptors are expressed in these cells. The INS-1 beta-cell line is used as a model of pancreatic beta-cells, expressing most of their properties. Therefore, we investigated the expression of different molecular subtypes in this cell line by means of real time Polymerase Chain Reaction and Western blot. We also performed a characterization of the binding of a prototypic purinergic P2Y agonist, Adenosine-5'-O-(1-[(35)S]thiotriphosphate) (ATP-alpha-[(35)S]), to cell membrane homogenates. The molecular analysis evidenced the presence of five different purinergic P2Y receptor subtypes (P2Y(1), P2Y(2), P2Y(4), P2Y(6) and P2Y(12)), which were expressed at similar levels. The Western blot analysis allowed detecting corresponding proteins. The binding assay demonstrated a specific ATP-alpha-[(35)S] interaction on high (40%) and low (60%) affinity components. The analysis of ATP-alpha-[(35)S] pharmacological profile on both sites permitted to classify the high affinity binding site as representative of the purinergic P2Y(1) receptor subtype and the low affinity binding site of the P2Y(4) and/or P2Y(6) receptor subtypes. ATP-alpha-S and Adenosine-5'-O-(2-thiodiphosphate) (ADP-beta-S) exhibited opposite selectivity on high and low affinity binding sites. Although purinergic P2Y(1) receptor, or a P2Y(1)-like subtype, has been generally considered as that implicated in the modulation of glucose-induced insulin release, the present data show that the beta-cell expresses a complex profile of purinergic P2Y receptor subtypes, the functional implication of which remains to be fully elucidated.
authors.affiliation: Montpellier I University and CNRS UMR 5232, Centre for Pharmacology and Innovation in Diabetes, Montpellier, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Lugo-Garcia
authors.forename: Romain
authors.initials: R
authors.lastname: Filhol
authors.forename: Anne-Dominique
authors.initials: AD
authors.lastname: Lajoix
authors.forename: René
authors.initials: R
authors.lastname: Gross
authors.forename: Pierre
authors.initials: P
authors.lastname: Petit
authors.forename: Jacques
authors.initials: J
authors.lastname: Vignon
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007340:Insulinoma / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D013873:Thionucleotides / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; C017817:adenosine 5'-(1-thio)triphosphate; C030812:adenosine 5'-O-(2-thiodiphosphate); D000244:Adenosine Diphosphate