Comparative analysis of transcriptomic liberality in 2,3,7,8-tetrachlorodibenzo- p -dioxin–exposed mouse liver RNA-Seq datasets

Omics methods have been envisioned to complement traditional toxicological testing for chemical risk assessment, in which identifying adverse effects is a critical step. However, the high dimensionality of transcriptomic data has historically led to reliance on context-dependent analysis. Liberality is a quantitative index that reduces genome-scale data dimensionality, with its changes reflecting underlying biological phenomena. In this study, we measured liberality in mouse liver RNA sequencing (RNA-Seq) datasets from studies in which mice were exposed to the environmental contaminant 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) every 4 days for 28 or 92 days, comparing dose–liberality relationships. Both 28- and 92-day TCDD treatments increased liberality but exhibited different dose–liberality relationships. Analysis of genes contributing to liberality revealed that longer exposure duration induced more extensive alterations in transcriptomic architecture. These findings suggest that liberality may serve as an unbiased metric to assess the extent of treatment-induced transcriptome perturbation.