Differential expression of HNF4alpha isoforms in liver stem cells and hepatocytes.

The hepatocyte nuclear factor (HNF4alpha) has been implicated in liver development and hepatocellular differentiation. The HNF4alpha expression in liver stem cells has not yet been fully investigated. Here, we describe the expression characterization of HNF4alpha in liver stem cells isolated from 2-acetylaminofluorene/partial hepatectomy (AAF/PH) rat model by a combination of density-gradient centrifugation and selective enzymatic digestion. The obtained cells were identified by flow cytometry (FCM) immediately and then by immunocytochemisty and reverse transcription-polymerase chain reaction (RT-PCR) after 5 d culture. The cultured stem cells were subjected to analysis of the expression of various HNF4alpha isoforms using RT-PCR, Western blotting, and electrophoretic mobility shift assay (EMSA). Results showed that HNF4alpha isoforms, alpha1, alpha2, alpha7, and alpha8 were present in liver stem cells, which contrasted with only alpha1 and alpha2 expression in hepatocytes. The distinct expression patterns of HNF4alpha isoforms in liver stem cells may contribute to maintain the "stemness" of these cells.