2,3,7,8-tetrachlorodibenzo-p-dioxin modifies alternative splicing in mouse liver

Alternative splicing is a co-transcriptional mechanism by including or excluding exons in different combinations, thereby expanding the diversity of protein isoforms of a single gene. Abnormalities in this process can result in deleterious effects to human health, and several xenobiotics are known to interfere with splicing regulation through multiple mechanisms. These changes could lead to human diseases such as cancer, neurological disorders, autoimmune diseases, and developmental disorders. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant generated as a byproduct of various industrial activities. Exposure to this dioxin has been linked to a wide range of pathologies through the alteration of multiple cellular processes. However, the effects of TCDD exposure on alternative splicing have not yet been studied. Here, we investigate whether exposure to TCDD influenced hepatic alternative splicing in adult male C57BL/6J mice. We identified several genes whose alternative splicing of precursor messenger RNAs was modified following TCDD exposure. In particular, we demonstrated that alternative splicing of Cyp1a1, Ahrr, and Actn1 was significantly altered after TCDD treatment. These findings show that exposure to TCDD has an impact on alternative splicing, presumably through binding to the aryl hydrocarbon receptor, and suggest a new avenue for AhR-mediated pathogenesis. Adult male C57BL/6 mice were treated by gavage with 0, 5, or 500 µg/kg TCDD dissolved in corn oil vehicle. Mice were euthanized 19 hours following treatment and liver tissue was harvested for analysis. RNA was isolated and the transcriptome for each animal assayed on separate microarrays.