Transgenic Humanized AHR Mouse Reveals Differences between Human and Mouse AHR Ligand Selectivity

Differences in how species respond to environmental chemicals remain a major challenge in toxicology. The AHR plays a central role in mediating responses to many industrial pollutants. While much is known about mouse AHR function, human AHR behavior is less well characterized. Mouse AHR(b) shows higher ligand affinity than its human counterpart. This discrepancy raises questions about how well mouse models predict human responses. Researchers have long noted species-specific differences in TCDD sensitivity. These differences are linked to AHR ligand binding affinity variations. No prior work had resolved the full extent of human-mouse AHR ligand selectivity. This gap motivated the development of a humanized mouse model to directly compare AHR function.

This research aimed to clarify differences between human and mouse AHR ligand selectivity. The study focused on how these receptors respond to various environmental chemicals. Researchers wanted to determine if human AHR has distinct ligand preferences. They used a transgenic mouse model to express human AHR in the liver. This approach allowed direct comparison of ligand binding and activation. The goal was to identify ligands where human AHR shows higher affinity. Understanding these differences could improve risk assessment for environmental toxins. The study sought to expand knowledge of AHR function in human physiology.

Scientists created a transgenic mouse model expressing human AHR in the liver. They used molecular biology techniques to introduce the human AHR gene. The model allowed liver-specific expression of the human receptor. Researchers tested multiple ligands to compare binding affinities. They measured ligand-induced gene expression as a response indicator. The study focused on both synthetic and natural chemical compounds. Indirubin was selected as a test ligand due to its known activity. The model enabled side-by-side comparisons between human and mouse AHR function.

Human AHR showed higher relative ligand binding affinity for indirubin. The human receptor exhibited greater responsiveness to this compound. Mouse AHR(b) had lower affinity for the same ligand. These differences were observed in liver-specific expression systems. The study confirmed species-specific variations in AHR ligand selectivity. The humanized model revealed distinct activation patterns for certain ligands. Researchers measured gene expression changes following ligand exposure. The results suggest human AHR may have unique endogenous ligand interactions.

The study demonstrated clear differences in AHR ligand selectivity between species. Human AHR showed higher affinity for indirubin compared to mouse AHR(b). These findings highlight the limitations of using mouse models for human risk assessment. The humanized mouse model proved effective for direct AHR comparisons. The results may guide future searches for endogenous hAHR ligands. The study supports the idea that human AHR has distinct functional characteristics. Researchers propose that these differences could influence physiological roles. The findings suggest the need for species-specific approaches in AHR research.