ABSTRACT

This chapter suggests that expression of genes encoding some of the inducible enzymes is regulated by nutritional and hormonal stimuli via common mechanisms. It discusses the regulation of expression of genes for three enzymes participating in fatty acid and fat synthesis such as liver phosphofructokinase, fatty acid synthase and p90. With the cloned cDNA sequences, the chapter examines expression of the nutritionally regulated genes at the pretranslational level. It analyses the effect of cyclic adenosine monophosphate (cAMP) on fatty acid synthase and p90 gene transcription. Mature 3T3-L1 adipocytes, which acquire responsiveness to lipolytic and lipogenic hormones during the differentiation process, were utilized to determine independent hormone effects on gene expression. The in vivo and in vitro experiments conclude that mammalian fatty acid synthase and p90 genes are under transcriptional control by insulin and cAMP, and that insulin upregulates and cAMP down-regulates these genes.