N 6 -methyladenosine is required for the hypoxic stabilization of specific mRNAs.

Post-transcriptional regulation of mRNA during oxygen deprivation, or hypoxia, can affect the survivability of cells. Hypoxia has been shown to increase stability of a subset of ischemia-related mRNAs, including VEGF. RNA binding proteins and miRNAs have been identified as important for post-transcriptional regulation of individual mRNAs, but corresponding mechanisms that regulate global stability are not well understood. Recently, mRNA modification by N 6 -methyladenosine (m6 A) has been shown to be involved in post-transcriptional regulation processes including mRNA stability and promotion of translation, but the role of m6 A in the hypoxia response is unknown. In this study, we investigate the effect of hypoxia on RNA modifications including m6 A. Our results show hypoxia increases m6 A content of poly(A)+ messenger RNA (mRNA), but not in total or ribosomal RNA in HEK293T cells. Using m6 A mRNA immunoprecipitation, we identify specific hypoxia-modified mRNAs, including glucose transporter 1 (Glut1) and c-Myc, which show increased m6 A levels under hypoxic conditions. Many of these mRNAs also exhibit increased stability, which was blocked by knockdown of m6 A-specific methyltransferases METTL3/14. However, the increase in mRNA stability did not correlate with a change in translational efficiency or the steady-state amount of their proteins. Knockdown of METTL3/14 did reveal that m6 A is involved in recovery of translational efficiency after hypoxic stress. Therefore, our results suggest that an increase in m6 A mRNA during hypoxic exposure leads to post-transcriptional stabilization of specific mRNAs and contributes to the recovery of translational efficiency after hypoxic stress.