Lower activity of CCAAT/enhancer-binding protein and expression of cyclin E, but not cyclin D1, activating protein-1 and p21(WAF1), after partial hepatectomy in obstructive jaundice

CCAAT/enhancer-binding protein (C/EBP)-alpha stabilizes p21(WAF1), whereas activating protein-1 (AP-1) and C/EBP-beta enhance cyclin D1 and cyclin E e xpression, respectively, during the progress of liver regeneration. In this study, we investigated the differences in the transcription factors and ce ll cycle regulators between obstructive jaundiced and control rats before a nd after hepatectomy accompanied with a release of biliary obstruction by i nternal biliary drainage. The expressions and activities of C/EBP-alpha and -beta were significantly decreased in the jaundiced group concomitant with the significantly lower cyclin E expression after hepatectomy than in the controls. The activities of AP-1, cyclin D1 and p21(WAF1) were not signific antly different between the two groups. These results suggest that obstruct ive jaundice inhibits hepatic expression and activity of C/EBP, resulting i n the impaired cyclin E expression that is partly responsible for the cell cycle dysfunction after hepatectomy. (C) 2001 Academic Press