Changes of liver-enriched nuclear transcription factors for albumin gene in starvation in rats

The regulatory mechanism of albumin gene transcription was examined using male Donryu rats (7 wk old) starved for 1 or 3 d. At the designated times, the rats were sacrificed to harvest the liver and to measure the serum albumin level. Neither the serum albumin nor the albumin messenger RNA (mRNA) level showed a significant change for these starvation periods. Among nuclear factors binding to the D site of albumin gene promoter, the CCAAT/enhancer binding protein α (C/EBP α) mRNA level showed a decrease and the D site binding protein (DBP) mRNA level tended to decrease after 3 d of starvation. In contrast, the C/EBPβ mRNA level showed a significant increase at day 1. As a B site binding nuclear factor, the hepatocyte nuclear factor 1 (HNF-1) mRNA level significantly increased at day 1. Gel mobility-shift analysis combined with Western immunoblotting confirmed the presence of D site binding proteins composed of DBP and C/EBPα and β in both groups subjected to oral feeding and to 3-d starvation, though quantitative analysis could not be done. In conclusion, the nuclear transcription factors binding to the albumin gene promoter undergo regulatory changes during 3 d of starvation, whereas there is no significant decrease in the albumin mRNA level.