Vangl Gene And Dact1 Of Genes And Neural Tube Defects Related Research

Neural tube defects (NTDs) are caused by a partial or complete failure of the neural tube to close during embryogenesis at any level of the rostrocaudal axis. They include anencephaly, craniorachischisis, encephalocele, iniencephaly and spina bifida that result from the failure of fusion in the cranial and spinal region of the neural tube, respectively. All infants with anencephaly are stillborn or die shortly after birth, whereas many infants with spina bifida now survive but with severe and life-long physical and developmental disabilities and are at risk for psychosocial maladjustment. In addition to the emotional cost of spina bifida, the estimated monetary cost is also staggering.Recently, more and more mouse models of neural-tube defects indicated that nearly all of the genes involved in planar cell polarity (PCP) pathway play an important role in neural tube closure. Among them, VANGL2 is the first reported gene associated with craniorachisis, a serve craninal neural-tube defects. However, no research groups nowadays succeeded to find VANGL2 mutations in human neural-tube defects.This study aimed to investigate whether mutations and polymorphisms in VANGL2, VANGL1, DACT1 are associated with human neural tube defects. We conducted a case-control study in the subjects containing a large number of cranial neural-tube defects, such as anencephaly, craniorachischisis and encephalocele. This study also evaluated the functions of missense mutations and polymorphisms in the promoter by yeast two hybrdization assay (Y2H) and dual-luciferase assay, respectively.Three NTD-specific missense mutations (i. e. S84F, R353C, F437S) in VANGL2 gene were detected in three patients with cranial neural tube defects, respectively. Y2H assays showed that R353C diminished the physical interactions between VANGL2 and Dishevelleds, and F437S abrogated these interactions. These data indicated VANGL2 was associated with human cranial neural tube defects.Eleven variants in VANGL2 promoter were detected in this study. Of them, the major allele frequencies (MAFs) of three (i. e. SNP7:-992T>G, SNP8:-545T>G, SNP9:42G>C) are higher than 10%. Case-control association analysis indicated that the minor allele (42C) of SNP9 was significantly associated with decreased risk for craniorachischisis (OR=0.49,95%CI: 0.21-0.96, p=0.03). Dual-luciferase assays indicated that the minor allele (42C) had a higher transcription activity (1.4 fold of the major allele) (p=0.002)Using cDNA from different tissues of a same individual, we found that the paternal and maternal VANGL2 expression levels were different at the same tissue. The mutated allele (VANGL2c.1057C) was predominant expressed in the pathogenic tissue and the wild-type allele (VANGL2 c.1057T) was predominant in the normal tissue. These allele imbalance expressions were relation to the promoter methylation status. Higher expression level of VANGL2 was correlated with Lower promoter methylation status, but this relation was nonsignificant (p=0.313).Although the associations between VANGL1 mutations and human spinal bifida have already been reported by others, the relationship between VANGL1 mutation and cranial neural-tube defects is still unknown. In this study, two cranial NTD-specific missense mutations (i.e. G39S, N313S) were detected in VANGL1. Y2H assays showed that N313S diminished the interaction between VANGL1 and Dishevelledl and Dishevelled2. These results suggested that VANLG1 was associated with human cranial NTDs.In mouse, about 20% of Dactl mutation homozygouses had spina bifida, and heterozygous mutation of Vangl2rescued recessive Dactl phenotypes, whereas loss of Dactl reciprocally rescued semidominant Vangl2 phenotypes, which is interesting. To date, no study reported that DACT1 was associated with human birth defects. In this study, we sequenced 163 NTDs and 480 controls, and detected five NTD-specific missense mutations. Multiple sequence alignment analysis suggested three of them (i. e. R45W, D142G, N356K) were conserved in evolution. And all the conserved mutations extremely changed the property of the wildtype amino acid residue. It was surprised that all the five mutations were uniformly found in female cases and were completely absent in all of female fetus controls. Although three missense mutations were detected in 192 control women, none of them was conserved through the protein blast analysis. These data demonstrated that DACT1 might be associated with female neural-tube defects.