| Abstract: | Addition of retinoic acid to human promyelocytic leukemia cells results in a dramatic increase in cellular transglutaminase activity. This increase is due to the induction of a specific intracellular transglutaminase, tissue transglutaminase. Retinoic acid-induced expression of tissue transglutaminase is potentiated by analogues of cyclic AMP. The induction of the enzyme can be detected within 6 h of the addition of the retinoid to the cell and results in increases of the enzyme of at least 50-fold. The induction of HL-60 transglutaminase is a specific response of the cells to retinoic acid and is not seen with other agents that induce HL-60 differentiation. We believe that the induction of tissue transglutaminase is a useful index of the early events in retinoid-regulated gene expression in both normal and transformed cells. |
