Cyanate attenuates insulin secretion in cultured pancreatic β cells

Abstract

Abstract. The vast majority of long-term complications in transplanted patients are associated with cardiovascular disease. Previously, an alternative and dominant mechanism for cyanate formation in atherosclerotic lesions has been discovered. This study was designed to determine the effect of cyanate on insulin secretion in cultured pancreatic β cells (INS-1 cells). The cytotoxicity of cyanate was determined by 3-(4,5-Desethyithiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Insulin secretion was measured by ELISA in cyanatetreated INS-1 cells. Reactive oxygen species (ROS) generation was also determined by measuring the fluorescent oxidized product of 2,7-dichlorefluorescein in cyanate-treated INS-1 cells. FACS analysis was carried out to determine the effect of cyanate on the apoptosis of INS-1 cells. Firstly, we found that cyanate, within concentration ranges in which no cytotoxic effect was observed (0.01, 0.1 and 1.0 mM), decreased insulin secretion dose-dependently in both non-glucose-stimulated and glucose-stimulated INS-1 cells. Cyanate at a 1.0 mM concentration inhibited insulin secretion by more than 50% in non-glucose-stimulated cells and glucose (5 and 10 mM)-stimulated cells. Cyanate, however, did not affect ROS generation. Furthermore, no pro-or anti-apoptotic effect was observed in cyanate-treated INS-1 cells. The results in this study suggest the possible inhibitory effect of cyanate on insulin secretion in INS-1 pancreatic β cells. The inhibitory effect was not mediated either by ROS generation or by apoptosis. Further studies to determine the underlying mechanisms will be of benefit.

Carbamylated low-density lipoprotein attenuates glucose uptake via a nitric oxide-mediated pathway in rat L6 skeletal muscle cells

“…Carbamylation is a posttranslational modification of proteins induced by cyanate in human blood plasma (1). The active form of cyanate, isocyanic acid, reacts irreversibly with the amino-or thiol groups of amino acids in proteins.…”

“…Carbamylation of low-density lipoprotein (LDL) has thus far been investigated predominantly in the context of uremia (7,8) as urea spontaneously converts to cyanate and ammonia in aqueous solutions (1). However, a recent study demonstrated that thiocyanate, elevated by smoking and diet, is changed into cyanate in human blood plasma (9).…”