Induction and activation of tissue transglutaminase during programmed cell death.

During the involution of lead nitrate-induced hyperplasia in rat liver a significant increase of transglutaminase activity, enzyme concentration, transglutaminase messenger RNA and protein-bound epsilon-(gamma-glutamyl)lysine (product of transglutaminase action) coincided with programmed death (apoptosis) of hepatocytes. Immunohistochemical examination showed the appearance of transglutaminase in apoptotic hepatocytes. An increased transglutaminase level was also detected during glucocorticoid-induced apoptosis of rat thymocytes.