Loss of Wtap results in cerebellar ataxia and degeneration of Purkinje cells.

N-methyladenosine (mA) modification, which is achieved by the METTL3/METTL14/WTAP methyltransferase complex, is the most abundant internal mRNA modification. Although recent evidence indicates that mA can regulate neurodevelopment as well as synaptic function, the roles of mA modification in the cerebellum and related synaptic connections are not well established. Here, we report that Purkinje cell (PC)-specific WTAP knockout mice display early-onset ataxia concomitant with cerebellar atrophy due to extensive PC degeneration and apoptotic cell death. Loss of Wtap also causes the aberrant degradation of multiple PC synapses. WTAP depletion leads to decreased expression levels of METTL3/14 and reduced mA methylation in PCs. Moreover, the expression of GFAP and NF-L in the degenerating cerebellum is increased, suggesting severe neuronal injuries. In conclusion, this study demonstrates the critical role of WTAP-mediated mA modification in cerebellar PCs, thus providing unique insights related to neurodegenerative disorders.