C/EBPβ contributes to hepatocyte growth factor-induced replication of rodent hepatocytes

Background/Aims:Hepatocyte replication can be induced in vivo by hepatocyte growth factor (HGF), which might be used for gene therapy or to promote liver regeneration. However, the biochemical steps critical for this process are not clear. C/EBP beta and C/EBP alpha are liver-enriched transcription factors that induce and inhibit hepatocyte replication, respectively. Because of their role in hepatocyte replication, this study examined the effect of HGF upon C/EBP proteins in vivo. Methods: Rats were treated with HGF, and the effect upon C/EBPs was evaluated in liver extracts. Normal or C/EBP beta-deficient mice were treated with HGF, and the effect upon hepatocyte replication was determined. Results: HGF had no effect in rat liver upon C/EBP alpha or C/EBP beta mRNA, nuclear protein, or nuclear DNA binding activity. However, HGF increased phosphorylated p90-RSK and ERK to18- and 3-fold normal, respectively. These kinases phosphorylate C/EBP beta and increase its transcriptional activity. The percentage of hepatocytes that replicated in C/EBP beta-deficient mice after HGF administration was only 1.1%, which was lower than the value of 6.6% for hepatocytes from HGF-treated normal mice (P=0.005). Conclusions: C/EBPP contributes to the induction of hepatocyte replication in response to HGF in rodents, which is likely due to post-translational modifications. (c) 2005 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.