linc01515 regulates PM-induced oxidative stress via targeting NRF2 in airway epithelial cells.

Dysregulation of long non-coding RNAs (lncRNAs) is involved in the adverse effects caused by fine particulate matter (PM). However, the molecular mechanism is not fully clarified. In this study, we performed lncRNA sequencing on PM-treated human bronchial epithelial (HBE) cells to identify vital lncRNAs, and verified the differential expression of the lncRNAs by RT-qPCR in HBE and human normal lung epithelial (BEAS-2B) cells. A total of 657 and 652 lncRNAs were dysregulated after exposure to 125 and 250 μg/mL of PM, respectively. Of these, lncRNA linc01515 was upregulated in HBE and BEAS-2B cells with PM treatment. Subcellular localization experiments showed that linc01515 was mostly localized in the nucleus. Functionally, we downregulated the expression of linc01515 in HBE and BEAS-2B cells before PM treatment, which can decrease malonydialdehyde (MDA) and reactive oxygen species (ROS) levels, and improve superoxide dismutase (SOD) activity. Correspondingly, linc01515 overexpression enhanced PM-induced oxidative injury in airway epithelial cells. Mechanistically, N-methyladenosine RNA binding protein immunoprecipitation (MeRIP) assay showed that the enrichment level of mA on linc01515 was increased after PM treatment, and the mA modification level and expression of linc01515 was decreased in the HBE cells with 3-deazaadenosine (DAA) treatment or knockdown of METTL3 to inhibit the RNA methylation level. Western blot found that NRF2, a vital transcription factor, was enhanced remarkably in linc01515-silenced cells and decreased in linc01515-overexpressed cells. Furthermore, inhibition of NRF2 activity significantly rescued effect of downregulated linc01515 expression on PM-induced cytotoxicity. In addition, we observed the similar effect when downregulating linc01515 and NRF2 expression in HBE and BEAS-2B cells before PM treatment. Taken together, our findings demonstrated that PM treatment may upregulate the expression of linc01515 by enhancing its mA modification, and then regulate NRF2 to induce oxidative damage of airway epithelial cells.