HNF factors form a network to regulate liver-enriched genes in zebrafish.

Area of Science:

• Developmental biology
• Genetics
• Molecular biology

Background:

• Defects in mammalian liver-enriched genes cause liver and blood diseases.
• Mammalian embryogenesis occurs internally, limiting study of liver-enriched genes during organ development.
• Zebrafish offer external embryogenesis and established gene knockdown techniques for studying liver development.

Purpose of the Study:

• To identify and characterize liver-enriched genes in adult zebrafish.
• To investigate the role of these genes during embryonic liver development.
• To explore the regulatory network of liver-enriched transcription factors.

Main Methods:

• Identification of 129 liver-enriched genes in adult zebrafish.
• Whole-mount in situ hybridization to detect gene enrichment in embryonic zebrafish livers.
• Morpholino-mediated gene knockdown to assess gene function during liver development.
• Bioinformatic analysis of promoter regions for transcription factor binding sites (Hnf1, Hnf3, Hnf4, Hnf6).

Main Results:

• 69 out of 129 identified liver-enriched genes were also enriched in embryonic zebrafish liver.
• Knockdown of a novel liver-enriched gene, leg1, impaired liver expansion growth.
• Promoter regions of most analyzed liver-enriched genes contained binding sites for multiple HNF transcription factors.

Conclusions:

• Zebrafish are a valuable model for studying liver organogenesis and the function of liver-enriched genes.
• The liver-enriched gene leg1 is crucial for embryonic liver growth.
• A network of HNF transcription factors likely co-regulates liver-specific gene expression.