Activation of distinct P2Y receptor subtypes stimulates insulin secretion in MIN6 mouse pancreatic β cells

Extracellular nucleotides and their receptor antagonists have therapeutic potential in disorders such as inflammation, brain disorders, and cardiovascular diseases. Pancreatic β 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 β cells. Expression of P2Y1 and P2Y6 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 P2Y1 and P2Y6 agonists, 2-MeSADP and Up3U, respectively. Both the agonists increased insulin secretion with EC50 values of 44.6 ± 7.0 nM and 30.7 ± 12.7 nM respectively. The insulin secretion by P2Y1 and P2Y6 agonists was blocked by their selective antagonists MRS2179 and MRS2578, respectively. Binding of the selective P2Y1 receptor antagonist radioligand [125I]MRS2500 in MIN6 cell membranes was saturable (KD 4.74 ± 0.47 nM), and known P2Y1 ligands competed with high affinities. Inflammation and glucose toxicity lead to pancreatic β cell death in diabetes. Flow cytometric analysis revealed that Up3U but not 2-MeSADP protected MIN6 cells against TNF-α induced apoptosis. Overall, the results demonstrate that selective stimulation of P2Y1 and P2Y6 receptors increases insulin secretion that accompanies intracellular calcium release, suggesting potential application of P2Y receptor ligands in the treatment of diabetes.

Activation of P2Y1 and P2Y6 receptors as targets for therapeutic intervention for diabetes.Figure optionsDownload as PowerPoint slide