PEPCK gene as model of inhibitory effects of insulin on gene transcription.

Regulation of gene transcription is a major action of insulin. Most of the greater than 20 examples of this effect involve the stimulation of transcription, but a few involve an inhibition. The inhibition of transcription of the phosphoenolpyruvate carboxykinase (PEPCK) gene has been studied in detail. Most of this effect is exerted at the level of transcription initiation. Hormone effects on transcription are thought to be mediated through cis-acting DNA sequences located in the 5'-flanking sequence adjacent to the transcription initiation site. The techniques of transient and stable transfection of fusion genes containing various segments of the PEPCK-gene promoter are being used to locate the insulin-responsive sequences.