Mettl14-dependent m6A modification controls iNKT cells development and function

Abstract

Abstract N6-Methyladenosine (m6A), the most common form of RNA modification, controls CD4+ T cell homeostasis by targeting the IL-7/STAT5/SOCS signaling pathways. The role of m6A modification in unconventional T cell development remains unknown. Using mice with T cell-specific deletion of RNA methyltransferase METTL14 (T-Mettl14 −/−), we demonstrated that m6A modification was indispensable for iNKT cell homeostasis. Loss of METTL14-dependent m6A modification led to the upregulation of p53-mediated apoptosis in double positive thymocytes, which in turn decreased distal Va-Ja gene rearrangements, including the invariant Va14-Ja18 TCR, resulting in a drastic reduction of iNKT numbers in the thymus and periphery. Residual T-Mettl14−/− iNKT cells exhibited increased apoptosis, impaired maturation, and decreased responsiveness to IL-2/IL-15 and TCR stimulation. Furthermore, METTL14 knockdown in mature iNKT cells diminished their cytokine production, correlating with increased Cish expression and decreased TCR signaling. Collectively, our study highlights a critical role for METTL14-dependent-m6A modification in iNKT cell development and function. This work was supported by NIH grants R01 AI41083 and R01 AI057460 to C.-R.W.