Glucose-dependent induction of acetyl-CoA carboxylase in rat hepatocyte cultures

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Abstract
The carbohydrate-dependent long-term regulation of acetyl CoA carboxylase was studied in primary hepatocyte cultures from adult rats. The enzyme activity was increased 2-fold by elevation to the glucose concentration to 20 mM or by enhancement of the insulin concentration to 0.1 .mu.M. Simultaneous increases in glucose and insulin resulted in a 5-fold increase in the enzyme activity. As shown by immunochemical titration, enhancement of the enzyme activity was due to an increase in the enzyme protein. Incorporation of [35S]methionine and immunoprecipitation of the enzyme reavealed that the incrase in enzyme protein was due to an increased rate of enzyme synthesis. The rate of enzyme degradation remained essentially unchanged. The glucose- and insulin-dependent induction of acetyl CoA carboxylase was prevented by the addition of .alpha.-amanitine (10 .mu.M) or cordycepin (10 .mu.M), indicating a transcriptional regulation of the enzyme level. The parallel induction of acetyl CoA carboxylase and of ATP citrate lyase indicates a co-ordinate long-term regulation of lipogenic enzymes.