Correlation of rare mutation in AXIN2 with human neural tube defects

Abstract

Objective To investigate the correlation between genetic variations in the AXIN2 gene and the development of neural tube defects (NTDs). Methods Bioinformatics analysis was performed on AXIN2 gene variations identified through whole-genome sequencing of muscle tissue samples from 100 fetuses with NTDs collected from June 2004 to December 2013 among 9 hospitals in Shanxi Province. The identified variations were validated using Sanger sequencing. In NE-4C cell lines, wild-type AXIN2 and mutant AXIN2 plasmids were transfected, and gene functionality was assessed through immunofluorescence and Western blot assay. Analysis was also conducted on human NTDs samples carrying AXIN2 variations. Results Five distinct AXIN2 gene variations were detected in the 100 NTDs samples. Functional studies were conducted on three of these variations [c.959A > T (p.D320V), c.1250C > T (p.A417V) and c.1634G > A (p.G545E)]. Western blot assay revealed that, although none of the 3 variations had an impact on the levels of β-catenin protein expression, the D320V (P < 0.05) and G545E (P < 0.001) variations led to downregulation of AXIN2 protein expression. Immunofluorescence assay demonstrated that all 3 variations did not alter the subcellular localization of AXIN2 protein. In embryonic muscle tissues carrying the D320V and G545E variations, AXIN2 protein expression was significantly lower than those in the control group [D320V (P < 0.05), G545E (P < 0.01)]. Conclusion This study identifies AXIN2 gene variations (D320V and G545E) in NTDs samples that result in the downregulation of AXIN2 protein expression. These variations may potentially lead to abnormal activation of the Wnt signaling pathway, thus contributing to the development of neural tube defects.

Keywords

• neural tube defects
• axin2
• gentic variation
• wnt signaling pathway