HNF6 and HNF3beta in Liverspecific Transcription Factor Networks

Observations that HNF-6 contributes to control of the expression of transcription factors and is expressed in early stages of liver, pancreas, and neuronal differentiation suggest that HNF-6 participates in several developmental programs (Landry et al., 1997). HNF-6 recognizes the -138 to -126 region of the HNF-3beta promoter. Site-directed mutagenesis of this HNF-6 site diminishes reporter gene expression, suggesting that HNF-6 activates transcription ofthis promoter and may thus play a role in epithelial cell differentiation of gut endoderm via regulation of HNF-3beta (Sama-dani and Costa, 1996). Later, it was recognized that HNF-6 is required for HNF-3beta promoter activity and that HNF-6 also recognizes the regulatory region of numerous liver-specific genes (Rausa et al., 1997). In-situ hybridization studies of staged specific embryos demonstrate that HNF-6 and its potential target gene, HNF-3beta, are coexpressed in the pancreatic and hepatic diverticulum. More detailed analysis of the developmental expression patterns of HNF-6 and HNF-3beta provides evidence of colocalization in hepatocytes, intestinal epithelial, pancreatic ductal epithelial, and exocrine acinar cells. The expression patterns of these two transcription factors do not overlap in other endoderm-derived tissues or in the neurotube (Rausa et al., 1997).

0 0

Post a comment