Activation of distinct P2Y receptor subtypes stimulates insulin secretion in MIN6 mouse pancreatic beta cells.
Extracellular nucleotides and their receptor antagonists have therapeutic potential in disorders such as inflammation, brain disorders, and cardiovascular diseases. Pancreatic beta cells express several purinergic receptors, and reported nucleotide effects on insulin secretion are contradictory. We studied the effect of P2Y receptors on insulin secretion and cell death in MIN6, mouse pancreatic beta cells. Expression of P2Y(1) and P2Y(6) receptors was revealed by total mRNA analysis using RT-PCR. MIN6 cells were stimulated in the presence of 16.7 mM glucose with or without P2Y(1) and P2Y(6) agonists, 2-MeSADP and Up(3)U, respectively. Both the agonists increased insulin secretion with EC(50) values of 44.6+/-7.0 nM and 30.7+/-12.7 nM respectively. The insulin secretion by P2Y(1) and P2Y(6) agonists was blocked by their selective antagonists MRS2179 and MRS2578, respectively. Binding of the selective P2Y(1) receptor antagonist radioligand [125I]MRS2500 in MIN6 cell membranes was saturable (K(D) 4.74+/-0.47 nM), and known P2Y(1) ligands competed with high affinities. Inflammation and glucose toxicity lead to pancreatic beta cell death in diabetes. Flow cytometric analysis revealed that Up(3)U but not 2-MeSADP protected MIN6 cells against TNF-alpha induced apoptosis. Overall, the results demonstrate that selective stimulation of P2Y(1) and P2Y(6) receptors increases insulin secretion that accompanies intracellular calcium release, suggesting potential application of P2Y receptor ligands in the treatment of diabetes.
Balasubramanian
Ramachandran
R
Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8A, Rm. B1A-19, Bethesda, MD, USA.
Ruiz de Azua
Inigo
I
Wess
Jürgen
J
Jacobson
Kenneth A
KA
D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D015394:Molecular Structure; D009711:Nucleotides / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000737:chemistry; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2 / Q000235:genetics; D013329:Structure-Activity Relationship
D007328:Insulin; D009711:Nucleotides; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D002118:Calcium