Chronic allergic asthma alters m6A epitranscriptomic tagging of mRNAs and lncRNAs in the lung

To evaluate the role of m6A methylation of mRNAs and long non-coding RNAs (lncRNAs) in chronic allergic asthma. Transcriptome-wide N6-methyladenosine (m6A) changes in BALB/c mice were profiled using immunoprecipitated methylated RNAs with microarrays in lung with chronic allergic asthma. Gene ontology (GO) and KEGG analyses were conducted. Target genes were verified by methylated RNA immunoprecipitation and real-time polymerase chain reaction (PCR). Specifically, the mRNA levels of m6A writers (METTL3, METTL14, and WTAP), and readers and erasers (FTO and ALKBH5) were estimated by real-time PCR analysis, using the SYBR-green method. IL17RB mRNA was also evaluated by PCR. Hematoxylin and eosin (H&E) staining showed that the airway and lung tissues in mice in the asthma group had extensive infiltration of inflammatory cells around the bronchioles, blood vessels, and alveoli. The lungs of those allergic asthma mice showed altered m6A epitranscriptome, whereby 1369 mRNAs and 176 lncRNAs were hypermethylated, and 197 mRNAs and 30 lncRNAs were hypomethylated (>1.5-fold vs control). Also, compared with the control group, IL17RB mRNA in lung of the asthmatic group was significantly hypermethylated (P<0.01). In the asthma group, the mRNA and the protein level of METTL14 (the key methyltransferase) and ALKBH5 (the major demethyltransferase) were significantly decreased compared with the control group (P<0.01). Chronic allergic asthma alters the lung m6A epitranscriptome, suggesting functional implications in the pathophysiology of refractory asthma. Data support methylated IL17RB mRNA possibly becoming a new therapeutic target for chronic allergic asthma.