Exposure to Air pollution Disrupts Circadian Rhythm through Alterations in Chromatin Dynamics

Empirical evidence from both animals and humans suggest that PM2.5 (particulate matter < 2.5µm) exposure accelerates a variety of non-communicable diseases (NCDs) including Type 2 diabetes. We investigated whether chronic exposure to ambient air pollution (PM2.5), disrupts circadian rhythm to facilitate metabolic insulin resistance and compared the impact of inhaled ambient PM2.5 alone or in combination with continuous light exposure (LL). Exposure to PM2.5 induced peripheral IR, disrupted circadian steroid release, reduced peak oxygen consumption and altered brown adipose 18Ffluorodeoxyglucose uptake on PET imaging. These findings were identical to that seen with LL with no additive interaction between PM2.5 and LL. Transcriptome profiles in the liver revealed a number of differentially expressed circadian genes Bmal1 (Arntl/Npas2), Period (Per) and Cryptochrome (Cry) in response to PM2.5. Alteration in chromatin accessibility in circadian targets was observed with PM2.5 by Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) while chromatin immunoprecipitation (ChIP) analysis, showed a marked difference in promoter occupancy by p300. Our data suggest a previously unrecognized role of particulate air pollution in promoting circadian disruption and metabolic dysfunction through epigenetic regulation of multiple circadian targets Overall design: RNA Seq (transcriptomes) and ATAC Seq (open chromatin region) (to be submitted) in liver sample from mice exposed with LD-FA, LD-PM2.5, LL-FA, LL-PM2.5 (2 samples from each group) for 30 Weeks