Associations of smoking and air pollution with peripheral blood RNA N-6-methyladenosine in the Beijing truck driver air pollution study

Abstract

Background: Post-transcriptional modifications of RNA constitute fundamental mechanisms of gene regulation. N-6-methyladenosine (m(6)A) is critical for health and disease and is modulated by cellular stressors. However, associations between environmental exposures and m(6)A have not been studied in humans. We aimed to examine associations between tobacco smoking and particulate air pollution with m(6)A and mRNA expression levels of its reader, writer and eraser (RWE) genes in blood. Methods: Using the Beijing Truck Driver Air Pollution Study, we investigated global m(6)A in RNA from peripheral blood collected from 106 human subjects in Beijing, China, in 2008. We measured m(6)A with nano-flow liquid chromatography-tandem mass spectrometry and investigated gene expression of six m(6)A RWEs with real-time-quantitative PCR. Using linear models, we examined associations with smoking status, pack-years, and smoking on day of visit in men, and with environmental tobacco smoke in nonsmokers. We also examined associations with ambient PM10 (particulate matter <= 10 mu m in diameter), and personal black carbon (BC) and PM2.5 measured with a portable monitor. Results: Smoking in men was significantly associated with a relative 10.7% decrease in global m(6)A levels in comparison to nonsmokers (p= 0.02). In men, smoking greater than 3.8 pack-years was associated with a 14.9% lower m(6)A than in nonsmokers. BC exposure trended towards positive associations with m(6)A (5.95% per 10 mu g/m(3) increase in BC; 95% CI: -0.96, 13.3). Global m(6)A levels were not correlated with RWE gene expression levels. No associations were detected between smoking or air pollutants and m(6)A RWE gene expression. Discussion: m(6)A was negatively associated with long-term smoking, yet positively associated with short-term BC exposure. These results indicate variable m(6)A responses to environmental stressors, providing early evidence into the impacts of toxicants on RNA modifications and suggesting potential for m(6)A as a biomarker or mechanism in environmental health research.