METTL14-dependent mA modification controls iNKT cell development and function.

N-methyladenosine (mA), the most common form of RNA modification, controls CD4 T cell homeostasis by targeting the IL-7/STAT5/SOCS signaling pathways. The role of mA modification in unconventional T cell development remains unknown. Using mice with T cell-specific deletion of RNA methyltransferase METTL14 (T-Mettl14), we demonstrate that mA modification is indispensable for iNKT cell homeostasis. Loss of METTL14-dependent mA modification leads to the upregulation of apoptosis in double-positive thymocytes, which in turn decreases Vα14-Jα18 gene rearrangements, resulting in drastic reduction of iNKT numbers in the thymus and periphery. Residual T-Mettl14 iNKT cells exhibit increased apoptosis, impaired maturation, and decreased responsiveness to IL-2/IL-15 and TCR stimulation. Furthermore, METTL14 knockdown in mature iNKT cells diminishes their cytokine production, correlating with increased Cish expression and decreased TCR signaling. Collectively, our study highlights a critical role for METTL14-dependent-mA modification in iNKT cell development and function.