AbstractTranscriptional responses to wildfire smoke, an increasingly important cause of human morbidity, are poorly understood. Here, using a combination of precision nuclear run-on sequencing (PRO-seq) and the assay for transposase-accessible chromatin using sequencing (ATAC-seq), we identify rapid and dynamic changes in transcription and chromatin structure in Beas-2B airway epithelial cells after exposure to wood smoke particles (WSP). By comparing 30 and 120 minutes of WSP exposure, we defined three distinct temporal patterns of transcriptional induction and chromatin responses to WSP. Whereas transcription of canonical targets of the aryl hydrocarbon receptor (AHR), such as CYP1A1 and AHRR, was robustly increased after 30 minutes of WSP exposure, transcription of these genes and associated enhancers returned to near baseline at 120 minutes. ChIP-qPCR assays and AHR knockdown confirmed a role for AHR in regulating these transcriptional responses, and we applied bioinformatics approaches to identify novel AHR-regulated pathways and targets including the DNA methyltransferase, DNMT3L, and its interacting factor, SPOCD1. Our analysis also defined a role for NFkB as a primary transcriptional effector of WSP-induced changes in gene expression. The kinetics of AHR- and NFkB-regulated responses to WSP were distinguishable based on the timing of both transcriptional responses and chromatin remodeling, with induction of several cytokines implicated in maintaining the NFkB response. In aggregate, our data establish a direct and primary role for AHR in mediating airway epithelial responses to WSP and identify crosstalk between AHR and NFkB signaling in controlling pro-inflammatory gene expression.
Novel cDNA sequences of aryl hydrocarbon receptors and gene expression in turtles (Chrysemys picta and Pseudemys scripta) exposed to different environments
