Glucose-induced activation of transglutaminase in pancreatic islets

Transglutaminase activity in rat islet homogenates was increased after preincubation of the islets at high glucose concentration, and severely decreased after preincubation in the presence of either 1,2-bis(2-chloroethyl)-1-nitrosurea or 2-cyclohexene-1-one. The stimulatory action of glucose was still observed when the islets were preincubated in the absence or extracellular Ca2+. The enzymic activity was decreased by NAD+ or NADP+ but not NADH or NADPH, and inhibited by GSSG more than by GSH. These findings suggest that the glucose-induced activation of transglutaminase may be related to induction of a more reduced redox state with subsequent change in thiol-disulfide balance.