In vitro apolipoprotein B mRNA editing activity can be modulated by fasting and refeeding rats with a high carbohydrate diet.

Apolipoprotein B mRNA editing in vivo is subject to tissue specific, developmental and metabolic regulation. We demonstrate for the first time that the metabolic modulation of apo B mRNA editing activity can be assayed in vitro using rat liver extracts. The editing activity in extracts from 48h-fasted rats was suppressed relative to that of normal chow-fed rats. Refeeding with a high-sucrose fat-free chow for 48h stimulated liver in vitro editing activity to approximately three times that of control liver extracts. The physical properties of editosomes assembled in extracts from fasted/refed rats differed from those assembled in control or fasted rat liver extracts. Polypeptide analysis revealed quantitative alterations of several proteins in each treatment group suggesting a complex regulatory process. The data corroborate those from in vivo studies and suggest the potential of the in vitro system in studying factors responsible for metabolic regulation of apo B mRNA editing.