Humanized mouse models for arsenic toxicology

项目总结 饮用水和食品被无机砷污染(IAS)是#年的主要公共健康风险。 美国和世界各地。暴露于IAS与癌症、糖尿病、心血管、呼吸系统和 神经系统疾病。 人类和大多数其他哺乳动物物种已经形成了IAS的解毒机制，这涉及到 IAS向甲基AS(MAS)和二甲基AS(DMAS)的两步转化和甲基化产物的排泄 尿液中的代谢物。在哺乳动物中，IAS甲基化是由单一酶砷的同源酶催化的 甲基转移酶(AS3MT)。甲基化IAS的能力受损，例如，由于AS3MT多态，有 与暴露于IAS相关的疾病风险增加有关。 暴露于ias的不良影响的潜在机制已在实验室中进行了广泛研究。 模特们。然而，由于实验动物之间的巨大差异，实验室研究一直受到阻碍。 以及人类代谢IAS的能力。特别是，实验室小鼠已被证明甲基化。 与人类相比，IAS的解毒效率要高得多，这使得它很难在老鼠身上复制一些不利的 人群研究中报告的表型，特别是癌症和糖尿病。建议的最终目标是 研究目的是开发新的小鼠模型，在这种模型中，ias的代谢与人类相似，而且 与IAS相关的疾病可以在与环境有关的IAS暴露水平上进行研究。 我们最近创造了一种新的小鼠品系，其中Borcs7/AS3MT基因座被Syntenic人源化 替补。AS3MT在人源化(HS/HS)小鼠组织中的表达与人类组织中的表达相似 与小鼠AS3MT的表达不同：AS3MT在肝脏中的表达较低，在肾上腺中的表达较高。 值得注意的是，在HS/HS小鼠组织中AS3MT表达的不同模式与低效率有关 IAS解毒和IAS及其甲基化代谢物在组织和排泄物中的分布 与在人类身上报道的一致。 该项目的目标是：(1)表征HS/HS小鼠对IAS暴露不良影响的敏感性， 着眼于糖尿病的作用，(2)产生一种新的表达AS3MT单倍型的小鼠品系，该单倍型具有 在人类队列中与IAS甲基化受损和IAS诱发疾病的风险有关，以及(3)探索 肾上腺AS3MT表达与肾上腺功能的关系 这项拟议的研究将产生并验证IAS毒理学的独特小鼠模型。这些型号将 使在与环境有关的暴露水平和在以下情况下研究IAS的不利影响成为可能 IAS和AS3MT基因的类人化代谢。使用这些模型将显著改善 侧重于IAS引起的疾病的实验室研究的可译性和影响。

PROJECT SUMMARY Contamination of drinking water and foods with inorganic arsenic (iAs) represents a major public health risk in the U.S. and worldwide. Exposure to iAs has been linked to cancer, diabetes, cardiovascular, respiratory and neurological diseases. Humans and most other mammalian species have developed mechanism for detoxification of iAs, which involves a two-step conversion of iAs to methyl-As (MAs) and dimethyl-As (DMAs) and excretion of the methylated metabolites in urine. In mammals, iAs methylation is catalyzed by orthologs of a single enzyme, arsenic methyltransferase (AS3MT). An impaired capacity to methylate iAs, e.g., due to AS3MT polymorphism, has been linked to increased risk of diseases associated with iAs exposure. Mechanisms underlying the adverse effects of iAs exposure have been extensively studied using laboratory models. However, laboratory research has been hindered by substantial differences between laboratory animals and humans in their capacity to metabolize iAs. In particular, laboratory mice have been shown to methylate and detoxify iAs much more efficiently than humans, making it difficult to reproduce in mice some of the adverse phenotypes reported in population studies, specifically cancer and diabetes. The ultimate goal of the proposed research is to develop novel mouse models, in which iAs metabolism resembles that in humans and in which iAs-associated diseases can be studied at environmentally relevant iAs exposure levels. We have recently generated a new mouse strain in which the Borcs7/As3mt locus was humanized by syntenic replacement. AS3MT expression in tissues of the humanized (Hs/Hs) mice resembles that in human tissues and differs from expression of mouse As3mt: AS3MT expression is lower in livers and much higher in adrenals. Notably, the different pattern of AS3MT expression in tissues of Hs/Hs mice is associated with low efficiency of iAs detoxification and with the profiles for iAs and its methylated metabolites in tissues and excreta that are consistent with those reported in humans. The goals of this project are: (1) To characterize susceptibility of Hs/Hs mice to adverse effects of iAs exposure, focusing on the diabetogenic effects, (2) to generate a new mouse strain expressing AS3MT haplotype that has been linked to impaired iAs methylation and risk of iAs-induced diseases in human cohorts, and (3) to explore association between AS3MT expression in adrenals and adrenal function. The proposed research will generate and validate unique mouse models for iAs toxicology. These models will make it possible to study adverse effects of iAs at environmentally relevant exposure levels and in context with human-like metabolism of iAs and AS3MT polymorphism. Using these models will markedly improve translatability and impact of laboratory studies focusing on iAs induced diseases.