Hepatocyte nuclear factor-4α and -1 small interfering RNA inhibits hepatocyte differentiation induced by extracellular matrix

Liver-specific genes and hepatocyte nuclear factor (HNF)-4α and -1 are coordinately regulated by extracellular matrix (ECM). However, still are unclear interactions between liver-specific genes and these liver-enriched transcription factors in the mechanism of hepatocyte differentiation regulated by ECM. To elucidate the relationship, we used small interfering RNA (siRNA), which obtains strong and specific knockdown of gene expression in cell culture. Treatment with siHNF-4α and siHNF-1 declined the expression levels for HNF-4α mRNA and HNF-1 mRNA in primary rat hepatocytes, respectively. The mRNA expressions of albumin, transthyretin, and apolipoproteins that were up-regulated in hepatocytes cultured on a basement membrane matrix, Engelbreth-Holm-Swarm (EHS) gel, were decreased in the presence of siHNF-4α or siHNF-1. Moreover, siHNF-4α and siHNF-1 did not affect the morphology and actin assembly of hepatocytes. These findings demonstrated that HNF-4α and HNF-1 directly regulate liver-specific gene expression and might be downstream of cytoskeletal organization in the mechanism by which the differentiated phenotype of hepatocytes is regulated by EHS gel.