Increase in translatable mRNA for mitochondrial pyruvate carboxylase during differentiation of 3T3 preadipocytes

During differentiation of 3T3 preadipocytes into adipocytes the activity of pyruvate carboxylase, a key lipogenic enzyme, rises about 20-fold. This increase of enzymatic activity is correlated with a comparable rise in the rate of incorporation of ³⁵S]methionine into immunoadsorbable pyruvate carboxylase. Polyadenylated RNA, isolated from differentiated 3T3 adipocytes, directs the synthesis of pyruvate carboxylase in a messenger-dependent reticulocyte lysate translation system at a 18-fold greater rate than that isolated from undifferentiated cells. Thus, it appears that the differentiation-induced rise in the cellular level of pyruvate carboxylase results from an increased rate of carboxylase synthesis due to a rise in the level of translatable carboxylase messenger RNA.