Induction of cellular transglutaminase biosynthesis by sodium butyrate

Cellular transglutaminase activity was induced in simian virus-transformed human embryonic lung fibroblasts (WI-38 VA13A) by sodium butyrate. The level of enzyme activity approached a maximum by 6 days; 9–11-fold higher in the presence of sodium butyrate (1 mM) than in its absence. The observed increases in cellular transglutaminase activity could be entirely accounted for by equivalent increases in the levels of enzyme protein measured by inhibition enzyme-linked immunosorbent assay. Sodium butyrate also increased the rate of enzyme synthesis, but had no effect on the rate of cellular transglutaminase degradation. The increase in the rate of enzyme synthesis was matched by an increased level of translatable transglutaminase mRNA as measured in a cell-free translation system. Our results suggest that sodium butyrate regulates cellular transglutaminase at the pretranslational level.