Specific expression and promoter analysis of the albumin gene promoter of the duck (Anas platyrhynchos domesticus)

ABSTRACT

1. Albumin (ALB) is a serum protein most highly expressed in liver and regarded as an effective indicator for liver pathologies. The objectives of this study were to determine the expression of duck ALB gene (duALB) in various non-hepatic tissues and identify the potential cis-regulatory elements in the promoter.

2. A model was established to assess duALB promoter activity in different cell lines by construction of a duALB promoter-driven GFP (Green Fluorescent Protein)-expressing vector, which exhibited high expression activity in liver-derived cells and lower expression in other cells. Through the firefly luciferase reporter gene driven by a series of constructs carrying progressive deletions, the core transcriptional regulatory region within the duALB promoter was identified. Mutations in candidate-binding sites were made by site-directed mutagenesis.

3. The core transcriptional regulatory region was located in the −190/−51 bp region. This region contains three potential transcription factor-binding sites, one each for hepatocyte nuclear factor (HNF-3β) (−158/−149), CCAAT/Enhancer-binding protein element (C/EBPα) (−119/−107) and nuclear factor-1 (HNF-1) (−67/−57). Site-directed mutagenesis of HNF-1 and C/EBPα-binding sites resulted in a significant reduction in duALB promoter activity. Two potential cis-regulatory elements (C/EBPα and HNF-1) were responsible for its transcriptional activity in liver-derived cells.

4. These findings contribute to the further understanding of the fundamental mechanisms of ALB gene regulation and the use of tissue-specific gene promoters to regulate tissue-specific expression of exogenous genes in vivo.

KEYWORDS:

• duck
• ALB gene
• transcriptional regulation
• site-directed mutagenesis

Acknowledgements

We thank Xinyu Li, Yiyu Tong and Yang Zhang for help with sample preparation.

Disclosure statement

The authors declare that they have no competing interests.

Additional information

Funding

This study was supported by the Priority Academic Development Programme of Jiangsu Higher Education Institutions: [Grant Number (2011)137] and the Project of Jiangsu Independent Innovative Agricultural Science and Technology: [Grant Number CX(15)1010].