Laminin-rich extracellular matrix maintains high level of hepatocyte nuclear factor 4 in rat hepatocyte culture.

Laminin-rich extracellular matrix, EHS-gel, has been demonstrated to keep a high level of liver-specific gene expression in cultured rat hepatocytes. To obtain information about the effect of EHS-gel on liver-specific functions, gene expression of liver-enriched transcription factors in rat hepatocytes was investigated. The apolipoprotein A-I and albumin mRNA levels were higher in hepatocytes cultured on EHS-gel than in those cultured on type I collagen (TIC). The levels of mRNA for HNF-4, C/EBP alpha and C/EBP beta were also higher on EHS-gel than on TIC. The level of HNF-4 mRNA in hepatocytes on EHS-gel was almost comparable to that in liver. The HNF-3 alpha mRNA level was lower on EHS-gel than on TIC. C/EBP beta mRNA was induced by dexamethasone in both EHS-gel and TIC. The induction of C/EBP alpha and HNF-4 by dexamethasone was observed only on TIC. These data suggest that EHS-gel leads hepatocytes to keep the phenotypic expression through high expression of liver-enriched transcription factors, such as HNF-4.