More than 170 post-transcriptional RNA modifications regulate the localization, processing and function of cellular RNAs, and aberrant RNA modifications have been linked to a range of human diseases. The RNA modification landscape in atherosclerosis, the main underlying cause of cardiovascular diseases, is still largely unknown. We used mass spectrometry to analyse a selection of RNA-modifying enzymes and the N6-methyladenosine (m6A) in carotid atherosclerotic lesion samples representing early

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... nd advanced stages of atherosclerosis as compared to non-atherosclerotic arteries from healthy controls. (i) the detection of different levels of several enzymes involved in methylations occurring in rRNA and mRNA; (ii) these findings included changes in the levels of methyltransferases ('writers'), binding proteins ('readers') and demethylases ('erasers') during atherosclerosis as compared to non-atherosclerotic control arteries, with generally the most prominent differences in samples from early atherosclerotic lesions; and (iii) these changes were accompanied by a marked downregulation of m6A in rRNA, the most abundant and well-studied modification in mRNA with a wide range of effects on cell biology. We show for the first time that RNA-modifying enzymes and the well-studied RNA modification m6A are differentially regulated in atherosclerotic lesions, which potentially could help creating new prognostic and treatment strategies.