Millions of people in various geographical regions, including the US, are exposed to unsafe levels of inorganic arsenic (iAs) in drinking water. The research of the effects of chronic exposure to iAs has commonly focused on its carcinogenic potency. However, epidemiologic studies indicate that iAs exerts other adverse effects that do not involve cancer. Several studies in arseniasis-endemic areas of Taiwan, Bangladesh, and Mexico have linked chronic exposures to high or moderate levels of iAs in drinking water to an increased risk for type 2 diabetes mellitus (T2D). Although results of epidemiologic studies in low-exposure areas or occupational settings have been inconclusive, laboratory research shows that exposures to iAs can produce symptoms that are consistent with T2D. In our preliminary studies, mice chronically exposed to iAs in drinking water developed impaired glucose tolerance. The major fraction of arsenic retained in tissues of these mice, including liver, pancreas, adipose and skeletal muscle tissues, was represented by methylated arsenicals, the products of the methylation of iAs by arsenic (3+ oxidation state) methyltransferase (AS3MT). Our in vitro studies showed that methylated trivalent arsenicals are more potent than iAs as inhibitors of insulin signaling and insulin-stimulated glucose uptake in cultured adipocytes. Notably, concentrations of arsenicals that inhibit glucose uptake by adipocytes and arsenic concentrations in tissues of mice that developed impaired glucose tolerance after exposure to iAs in drinking water are similar to arsenic concentrations in livers of residents in the arseniasis areas of Bangladesh. These results suggest that the formation of methylated trivalent arsenicals in the course of iAs metabolism may be a determining factor for development of T2D in individuals exposed to iAs in drinking water and that insulin-activated signal transduction pathway is the key target for these arsenicals. Based on these findings, we propose a translational research project that will examine diabetogenic effects of iAs in cultured cells, laboratory mice, and in humans. The main goals of this project are (i) to further characterize the association between iAs exposure and T2D, (ii) to identify molecular mechanisms for the diabetogenic effects of iAs exposure, (iii) to evaluate the roles specific metabolites of iAs play in these effects, and (iv) to characterize AS3MT polymorphisms that are associated with the increased production of these metabolites. Results of this project will advance knowledge in the area of environmental toxicology of As that has not been systematically studied, providing novel information that will improve the risk assessment of diabetes in arseniasis-endemic areas and the identification of individuals with increased susceptibility to the diabetogenic effects of chronic exposures to iAs.

Public Health Relevance

Millions of people worldwide are exposed to arsenic in drinking water. Previous epidemiologic studies have linked chronic exposures to arsenic to an increased risk for type 2 diabetes mellitus. We propose a translational research project that will examine diabetogenic effects of arsenic in cultured cells, laboratory mice, and in humans. The goals of this project are to identify mechanisms by which exposures to arsenic induce diabetes and to characterize genetic polymorphisms that are associated with increased risk of diabetes for individuals exposed to arsenic in drinking water.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES015326-02
Application #
7670462
Study Section
Clinical and Integrative Diabetes and Obesity Study Section (CIDO)
Program Officer
Heindel, Jerrold
Project Start
2008-08-07
Project End
2013-05-31
Budget Start
2009-06-01
Budget End
2010-05-31
Support Year
2
Fiscal Year
2009
Total Cost
$415,484
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Nutrition
Type
Schools of Public Health
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Martin, Elizabeth M; Stýblo, Miroslav; Fry, Rebecca C (2017) Genetic and epigenetic mechanisms underlying arsenic-associated diabetes mellitus: a perspective of the current evidence. Epigenomics 9:701-710
Mendez, Michelle A; González-Horta, Carmen; Sánchez-Ramírez, Blanca et al. (2016) Chronic Exposure to Arsenic and Markers of Cardiometabolic Risk: A Cross-Sectional Study in Chihuahua, Mexico. Environ Health Perspect 124:104-11
Rager, Julia E; Tilley, Sloane K; Tulenko, Samantha E et al. (2015) Identification of novel gene targets and putative regulators of arsenic-associated DNA methylation in human urothelial cells and bladder cancer. Chem Res Toxicol 28:1144-55
González-Horta, Carmen; Ballinas-Casarrubias, Lourdes; Sánchez-Ramírez, Blanca et al. (2015) A concurrent exposure to arsenic and fluoride from drinking water in Chihuahua, Mexico. Int J Environ Res Public Health 12:4587-601
Martin, Elizabeth; González-Horta, Carmen; Rager, Julia et al. (2015) Metabolomic characteristics of arsenic-associated diabetes in a prospective cohort in Chihuahua, Mexico. Toxicol Sci 144:338-46
Musil, Stanislav; Matoušek, Tomáš; Currier, Jenna M et al. (2014) Speciation analysis of arsenic by selective hydride generation-cryotrapping-atomic fluorescence spectrometry with flame-in-gas-shield atomizer: achieving extremely low detection limits with inexpensive instrumentation. Anal Chem 86:10422-8
Currier, Jenna M; Ishida, María C; González-Horta, Carmen et al. (2014) Associations between arsenic species in exfoliated urothelial cells and prevalence of diabetes among residents of Chihuahua, Mexico. Environ Health Perspect 122:1088-94
Douillet, Christelle; Currier, Jenna; Saunders, Jesse et al. (2013) Methylated trivalent arsenicals are potent inhibitors of glucose stimulated insulin secretion by murine pancreatic islets. Toxicol Appl Pharmacol 267:11-5
Matoušek, Tomáš; Currier, Jenna M; Trojánková, Nikola et al. (2013) Selective hydride generation- cryotrapping- ICP-MS for arsenic speciation analysis at picogram levels: analysis of river and sea water reference materials and human bladder epithelial cells. J Anal At Spectrom 28:1456-1465
Bailey, Kathryn A; Wu, Michael C; Ward, William O et al. (2013) Arsenic and the epigenome: interindividual differences in arsenic metabolism related to distinct patterns of DNA methylation. J Biochem Mol Toxicol 27:106-15

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