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    Environmental epitranscriptomics
    (Academic Press Inc Elsevier Science, 2020) Cayir, Akin; Byun, Hyang-Min; Barrow, Timothy M.
    Chemical modifications of RNA molecules have gained increasing attention since evidence emerged for their substantive roles in a range of biological processes, such as the stability and translation of mRNA transcripts. More than 150 modifications have been identified in different organisms to date, collectively known as the 'epitranscriptome', with 6-methyladenosine (m(6)A), 5-methylcytidine (m(5)C), pseudouridine and N1-methyladenosine (m(1)A) the most extensively investigated. Although we are just beginning to elucidate the roles of these modifications in cellular functions, there is already evidence for their dysregulation in diseases such as cancer and neumdevelopmental disorders. There is currently more limited knowledge regarding how environmental exposures affect the epitranscriptome and how this may mediate disease risk, but evidence is beginning to emerge. Here, we review the current evidence for the impact of environmental exposures such as benzo[a]pyrene, bisphenol A, pesticides, metals and nanoparticles upon RNA modifications and the expression of their 'writers' (methyl transferases), 'erasers' (demethylases) and `readers'. We discuss future directions of the field and identify areas of particular promise and consider the technical challenges that are faced.
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    Exposure to environmental toxicants reduces global N6-methyladenosine RNA methylation and alters expression of RNA methylation modulator genes
    (Academic Press Inc Elsevier Science, 2019) Cayir, Akin; Barrow, Timothy M.; Guo, Liqiong; Byun, Hyang-Min
    The epitranscriptome comprises more than 100 forms of RNA modifications. Of these, N6-methyladenosine (m(6)A) is the most abundant form of RNA methylation, with roles in modulating mRNA transcript processing and regulation. The aims of the study were to examine changes inm(6)A RNA methylation in A549 lung epithelial cells in response to environmental toxicants, and differential gene expression of m(6)A modulator genes ('readers', 'writers' and 'erasers') in human subjects exposed to particulate matter (PM) and in lung cancer tissue using publicly-available microarray datasets. Global m(6)A methylation levels were measured in total RNA after exposure to two carcinogens (PM and sodium arsenite) for 24- and 48-h, and to two endocrine disruptors (bisphenol A and vinclozolin)for 24-h. Global m(6)A methylation level significantly decreased with exposure to > 62 mu g/mlPM, > 1 mu M sodium arsenite, > 1 mu M bisphenol A (BPA), and 0.1 mu M vinclozolin. In an analysis of a published dataset derived from a population study, we observed that m(6)A writers (METTL3 and WTAP), erasers (FTO and ALKBH5) and readers (HNRPC) showed significantly higher expression among participants in the high-PM2.5 exposure group compared to those in the low-exposure control group (all p < 0.05). Further, the m(6)A writer METTL3 shows reduced expression in lung tumors in comparison to normal lung epithelia (p < 0.0001). Our findings reveal that m(6)A RNA methylation can be modified by exposure to environmental toxicants, and exposure to particulate matter is associated with differential expression level of m(6)A RNA methylation modification machinery.
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    Öğe
    Occupational noise exposure is associated with hypertension in China: Results from project ELEFANT
    (Public Library Science, 2018) Cayir, Akin; Barrow, Timothy M.; Wang, Hao; Liu, Hongbin; Li, Changping; Ding, Ning; Li, Yan
    Objectives We investigated the association between occupational noise exposure and the risk of elevated blood pressure and hypertension by stage in young adults. Methods We utilized 124,286 young adults (18-40 years) from the Project ELEFANT study. We categorized occupational noise exposure as high (75 dBA noise exposure for more than 4 hours per day) or low, and measured blood pressure (mmHg) and categorized participants by hypertension stage (normal, elevated, Stage 1, Stage 2). We applied adjusted logistic regression models to identify associations with hypertension risk, and we further examined the noise-BMI, noise-gender, and noise-residence interactions on hypertension risk in separate models. Results High occupational noise exposure was associated with increases in blood pressure among participants with elevated blood pressure (Estimate = 0.23, 95% CI: 1.09, 1.46, p = 0.0009), in Stage 1 hypertension (Estimate = 0.15, 95% CI: 1.06, 1.25, p = 0.0008), and in Stage 2 hypertension (Estimate = 0.41 95% CI: 1.31, 1.73, p<0.0001). Likewise, noise exposure BMI interaction was consistently positively associated with increases in blood pressure in participants with elevated blood pressure (Estimate = 0.71, 95% CI: 1.55, 2.69, p<0.0001), in Stage 1 hypertension (Estimate = 0.78, 95% CI: 1.82, 2.61, p<0.0001), and in Stage 2 hypertension (Estimate = 2.06, 95% CI: 5.64, 10.81, p<0.0001). The noise exposure-male interaction showed higher risk for hypertension compared to the noise exposure-female interaction in participants with elevated blood pressure (Estimate = 1.24, 95% CI: 2.56, 4.71, p<0.0001), Stage 1 (Estimate = 1.67, 95% CI: 4.34, 6.42, p<0.0001) and Stage 2 hypertension (Estimate = 1.70, 95% CI: 3.86, 7.77, p<0.0001). Finally, we found that noise exposure-urban interaction was consistently associated with an increase in blood pressure in elevated blood pressure (Estimate = 0.32, 95% CI: 1.19, 1.62, p<0.0001) and in Stage 2 hypertension (Estimate = 0.44, 95% CI: 1.31, 1.80, p<0.0001).