REGULATION OF ATP-CITRATE LYASE AT TRANSCRIPTIONAL AND POSTTRANSCRIPTIONAL LEVELS IN RAT-LIVER

The amounts of ATP-citrate lyase in liver cytosol began to increase at 12 hours after refeeding a high-carbohydrate diet and further increased until 48 hours. The amounts of the ATP-citrate lyase mRNA began to increase at 6 hours and reached to a maximum level at 12 hours, followed by decrease to a very low level until 48 hours. The elevated amount of the ATP-citrate lyase mRNA reflected on the increase of ATP-citrate lyase content in the first 24 hours, but these two parameters were not paralleled thereafter. The transcriptional activity of ATP-citrate lyase gene in nuclei of rat liver began to increase at 4 hours and further increased to reach a maximum level of 24 fold at 12 hours, maintaining a high level of 17 fold until 48 hours. The elevation of transcriptional activity of ATP-citrate lyase gene preceded the increase of ATP-citrate lyase mRNA content in the liver cytosol by 2 hours, and its increasing pattern was similar to changes of mRNA content until 12 hours. However, while the transcriptional activity remained at a high level until 48 hours, the ATP-citrate lyase mRNA concentration in the cytosol decreased after 12 hours. © 1992.