Molecular and Metabolic Analysis of Arsenic-Exposed Humanized AS3MT Mice
Background: Chronic exposure to inorganic arsenic (iAs) has been associated with type 2 diabetes (T2D). However, potential sex divergence and the underlying mechanisms remain understudied. iAs is not metabolized uniformly across species, which is a limitation of typical exposure studies in rodent models. The development of a new “humanized” mouse model overcomes this limitation. In this study, we leverage this model to study sex differences in the context of iAs exposure. Objectives: The aim of this study iwas to determine if males and females exhibit different liver and adipose molecular profiles and metabolic phenotypes in the context of iAs exposure. Methods: Our study was performed on wild-type (WT) 129S6/SvEvTac and humanized arsenic +3 methyl transferase (human AS3MT) 129S6/SvEvTac mice treated with 400 ppb of iAs via drinking water ad libitum. After 1 month, mice were sacrificed and the liver and epididymales gonadal adipose depot were harvested for iAs quantification as well as sequencing-based microRNA and gene expression analysis. Serum blood was collected for fasting blood glucose, fasting plasma insulin, and HOMA-IR. Results: We detected sex divergence in liver and adipose markers of diabetes (e.g., insulin signaling pathways, fasting blood glucose, fasting plasma insulin, and HOMA-IR) only in humanized (not WT) male mice. In humanized female mice, numerous genes that promote insulin sensitivity and glucose tolerance in both the liver and adipose are elevated compared to humanized male mice. We also identified Klf11 as a putative master regulator of the sex divergence in gene expression in humanized mice. Discussion: Our study underscoreds the importance of future studies leveraging the humanized mouse model to study iAs-associated metabolic disease. The findings also suggest suggested that humanized females are protected  from metabolic dysfunction relative to humanized males in the context of iAs exposure. Future investigations should focus on the detailed mechanisms that underlie the sex divergence, including the potential role of miR-34a and/or Klf11. Overall design: WT mice and mice expressing humanized AS3MT were exposed to  of iAs via drinking water ad libitum. After 1 month, mice were sacrificed and the liver and gonadal adipose depots were harvested for iAs quantification and sequencing-based microRNA and gene expression analysis. Serum blood was collected for fasting blood glucose, fasting plasma insulin, and homeostatic model assessment for insulin resistance (HOMA-IR).