In our experiments we are using normal and transformed cells in tissue culture. Our research goal is to elucidate the regulation and expression of the mammalian liver tissue transglutaminase gene. While many different transglutaminases have been described in cells and body fluids, their structure and physiological roles are poorly understood. The transglutaminases are a family of enzymes that catalyze an acyl transfer reaction in which g-carboxamide of peptide bound glutamine residues act as acyl donors. Molecular weights of transglutaminases range from 50 kD for epidermal transglutaminase to 300 kD for plasma transglutaminase.
Mammalian liver contains large amounts of transglutaminase.
To identify the location of the enzyme in normal and transformed cells in tissue culture we will use antibodies prepared against liver tissue transglutaminase employing immunofluorescence techniques. We will study the activity of the enzyme in these cells and correlate the location to the activity of the enzyme under different experimental conditions. Since retinoic acid induces expression of tissue transglutaminase, we will explore the effect of retinoic acid induction on normal and transformed cells with these cytological techniques and enzyme activity measurements. We find that activity of tissue transglutaminase is lower in transformed cells than in the normal cell line, but after induction with retinoic acid we observe that the activity of transglutaminase in transformed cells surpasses that of the induced normal cells. In another ongoing project students are studying the role that tissue transglutaminase plays in the programmed cell death.