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Updated: Dec 25, 2025
In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila
Published on: August 20, 2019
Identification of functional mutations at FOXP3 binding site within BIC gene that alter the expression of miR-155 in
Daoyuan Wang1, Wei Zhang1, Jingying Guo1
1Key Lab of Agricultural Animal Genetics, Breeding, and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China.
Abstract:
MiR-155 is an immune microRNA encoded within the BIC gene. Dozens of researches have uncovered the importance of high expression of miR-155 in promoting the development of immune organs and strengthening immune response and inflammatory response. Some natural mutations located in the miR-155/BIC region were revealed to disturb the expression level of miR-155 in several mammalian species, and our previous study also identified several mutations occurring near the miR-155/BIC region in pigs. However, the consequences of BIC locus-harbored mutations in pig genome remain unclear. In this study, we used Chinese Meishan and British Large White pigs to identify mutations within the miR-155/BIC region, and explore whether there are effects on expressions of miR-155 and its target genes. Target sequencing identified six potential FOXP3 protein binding sites (AAACA) in the BIC gene, among which there were two A/C mutations (AAACC) at the -108 bp and -305 bp upstream of the miR-155 precursors in Meishan pigs, but not in Large White pigs. A series of experiments confirmed that the FOXP3 protein mainly binds to the -305 bp position, and the binding efficiency of the CC haplotype to FOXP3 protein was higher than that of the wild type, resulting in increased expression of miR-155, and consequentially decreased the expressions of its target genes. Our newly identified mutations are functional, which explain partial reasons for the difference in immunity between Meishan and Large White pigs, and provide potential molecular markers to genetically improve the disease resistance in the pig breeding practice.
Insights
New mutations in the miR-155/BIC region of pigs affect microRNA expression and immune response. These findings offer potential genetic markers for enhancing disease resistance in livestock breeding.
Area of Science:
- Genetics and Genomics
- Immunology
- Molecular Biology
Background:
- MicroRNA-155 (miR-155) is crucial for immune and inflammatory responses.
- Mutations in the miR-155/BIC region can alter miR-155 expression.
- Previous studies identified mutations near the miR-155/BIC region in pigs, but their functional impact was unknown.
Purpose of the Study:
- To identify mutations within the miR-155/BIC region in Chinese Meishan and British Large White pigs.
- To investigate the functional consequences of these mutations on miR-155 expression and its target genes.
- To explore the role of these mutations in the immune differences between pig breeds.
Main Methods:
- Target sequencing to identify mutations in the BIC gene and potential FOXP3 binding sites.
- Experimental validation of FOXP3 protein binding to specific DNA sequences.
- Quantitative analysis of miR-155 and its target gene expression levels.
Main Results:
- Two specific A/C mutations (AAACC) were identified in the miR-155 precursor region in Meishan pigs.
- FOXP3 protein preferentially binds to the -305 bp position, with higher efficiency for the CC haplotype.
- This increased binding leads to elevated miR-155 expression and consequently reduced expression of its target genes.
Conclusions:
- The identified mutations within the BIC locus are functional and impact miR-155 regulation.
- These genetic variations contribute to the observed differences in immune responses between Meishan and Large White pigs.
- The discovered mutations serve as potential molecular markers for improving disease resistance in pig breeding programs.
