Polymorphisms in Arsenic(+III)methyltransferase (AS3MT) Predict Gene Expression of AS3MT as well as Arsenic Metabolism.
Author
Summary, in English
Background: Arsenic is mono- (MMA) and dimethylated (DMA) in humans and the methylation pattern demonstrates large inter-individual differences. The fraction of urinary MMA is a marker for susceptibility to arsenic-related diseases. Objectives: The impact of polymorphisms in five methyltransferase genes on arsenic metabolism was evaluated in two populations, one in South America, one in southeast Asia. The methyltransferase genes were arsenic(+III)methyltransferase (AS3MT), DNAmethyltransferase 1a and 3b (DNMT1a, DNMT3b), phosphatidylethanolamine Nmethyltransferase (PEMT) and betaine-homocysteine methyltransferase (BHMT). AS3MT expression was analyzed in peripheral blood. Methods: Subjects were women, exposed to arsenic in drinking water in the Argentinean Andes (N=172; median urinary arsenic 200 μg/L) and in rural Bangladesh (N=361; 100 μg/L, all in early pregnancy). Urinary arsenic metabolites were measured by HPLC-ICPMS. Polymorphisms (N=22) were genotyped with Sequenom™. AS3MT expression was measured with qPCR using TaqMan® expression assays. Results: Six AS3MT polymorphisms were significantly associated with arsenic metabolite patterns in both populations (p-values ≤0.01). The most frequent AS3MT haplotype in Bangladesh was associated with higher %MMA, and the most frequent in Argentina with lower %MMA and higher %DMA. Four polymorphisms in the DNMTs were associated with metabolite patterns in Bangladesh. Non-coding AS3MT polymorphisms affected gene expression of AS3MT in peripheral blood, demonstrating that one functional impact of AS3MT polymorphisms may be altering levels of gene expression. Conclusions: Polymorphisms in AS3MT significantly predicted As metabolism across these two very different populations, suggesting that AS3MT may have an impact on As metabolite patterns in populations worldwide.
Publishing year
2011
Language
English
Pages
182-188
Publication/Series
Environmental Health Perspectives
Volume
119
Links
Document type
Journal article
Publisher
National Institute of Environmental Health Sciences
Topic
- Environmental Health and Occupational Health
Keywords
- AS3MT
- arsenic
- BHMT
- DNMT1a
- DNMT3b
- gene expression
- methylation
- one-carbon metabolism
- PEMT
- polymorphism
Status
Published
ISBN/ISSN/Other
- ISSN: 1552-9924