Analysis of the MTHFD1 promoter and risk of neural tube defects

Abstract

Genetic variants in MTHFD1 (5,10-methylenetetrahydrofolate dehydrogenase/ 5,10-methenyltetrahydrofolate cyclohydrolase/ 10-formyltetrahydrofolate synthetase), an important folate metabolic enzyme, are associated with a number of common diseases, including neural tube defects (NTDs). This study investigates the promoter of the human MTHFD1 gene in a bid to understand how this gene is controlled and regulated. Following a combination of in silico and molecular approaches, we report that MTHFD1 expression is controlled by a TATA-less, Initiatorless promoter and transcription is initiated at multiple start sites over a 126bp region. We confirmed the presence of three database polymorphisms (dbSNP) by direct sequencing of the upstream region (rs1076991 C>T, rs8010584 G>A, rs4243628 G>T), with a fourth (dbSNP rs746488 A>T) not found to be polymorphic in our population and no novel polymorphisms identified. We demonstrate that a common SNP rs1076991 C>T within the window of transcriptional initiation exerts a significant effect on promoter activity in vitro. We investigated this SNP as a potential risk factor for NTDs in a large homogenous Irish population and determined that it is not an independent risk factor, but, it does increase both case (χ 2 = 11.06, P = 0.001) and maternal (χ 2 = 6.68, P = 0.01) risk when allele frequencies were analysed in combination with the previously identified disease-associated p.R653Q (c.1958 G>A; dbSNP rs2236225) polymorphism. These results provide the first insight into how MTHFD1 is regulated and further emphasise its importance during embryonic development.

Association between MTHFD1 polymorphisms and neural tube defect susceptibility

“…Furthermore, MTHFD1 SNP 1958GN A is a functional exonic SNP that has been studied in several populations, and the previous studies that indicate the genetic variants of MTHFD1 can result in some kind of diseases [3,[23][24][25][26][27][28][29][30]. In Carroll N's analysis, he revealed that MTHFD1 SNP 1958G N A (R653Q) has a highly significant association with NTD risk in both case (genotype and allele frequencies) and maternal (allele frequencies only) groups [16]. And in the study of Ridgely F.G., the cause of NTD was considered to be consistent with both genetic and epigenetic mechanisms contributing to the increased risk of NTD and overall birth defect risk in the maternal lineage which had a higher number of genotypes associated with lower folate metabolism than paternal relatives [31].…”

“…In our meta-analysis, we extracted data from 9 relevant articles [1,[8][9][10][15][16][17][18][19]; they were all selected through a pre-specified search strategy. Quality assessment for the overall studies was shown with a bar graph according to the Newcastle-Ottawa Scale tool in Fig.…”

The Interplay between DNA Methylation, Folate and Neurocognitive Development

“…Finally, knockout of MTHFD1, a gene required for purine biosynthesis, resulted in abnormal neural tube closure and premature death around embryonic day 10.5 (e10.5) [28]. In human, SNPs existing within the promoter region of MTHFD1, have been associated with increased NTD risk [29].…”

Methylenetetrahydrofolate Dehydrogenase 1 Polymorphisms Modify the Associations of Plasma Glycine and Serine With Risk of Acute Myocardial Infarction in Patients With Stable Angina Pectoris in WENBIT (Western Norway B Vitamin Intervention Trial)

“…On the contrary, the T-allele of rs1076991 polymorphism has been suggested to decrease the MTHFD1 promoter activity by nearly 70%, 11 which may reduce the MTHFD1 flux. Meanwhile, increased intracellular glycine was associated with impaired 5,10-methylenetetrahydrofolate, possibly because of reverse flux through serine hydroxymethyltransferase.…”

“…The minor A allele of rs2236225 has been shown to decrease de novo purine synthesis rate, 10 while the minor T allele of rs1076991 has been associated with nearly 70% decrease of MTHFD1 promoter activity. 11 We, therefore, assessed whether associations of plasma serine and glycine with risk of AMI were influenced by the MTHFD1 polymorphisms among SAP patients included in the WENBIT (Western Norway B Vitamin Intervention Trial).…”