Deoxynivalenol induces m6A-mediated upregulation of p21 and growth arrest of mouse hippocampal neuron cells in vitro.

Hippocampal neurons maintain the ability of proliferation throughout life to support neurogenesis. Deoxynivalenol (DON) is a mycotoxin that exhibits brain toxicity, yet whether and how DON affects hippocampal neurogenesis remains unknown. Here, we use mouse hippocampal neuron cells (HT-22) as a model to illustrate the effects of DON on neuron proliferation and to explore underlying mechanisms. DON exposure significantly inhibits the proliferation of HT-22 cells, which is associated with an up-regulation of cell cycle inhibitor p21 at both mRNA and protein levels. Global and site-specific m⁶A methylation levels on the 3'UTR of p21 mRNA are significantly increased in response to DON treatment, whereas inhibition of m⁶A hypermethylation significantly alleviates DON-induced cell cycle arrest. Further mechanistic studies indicate that the m⁶A readers YTHDF1 and IGF2BP1 are responsible for m⁶A-mediated increase in p21 mRNA stability. Meanwhile, 3'UTR of E3 ubiquitin ligase TRIM21 mRNA is also m⁶A hypermethylated, and another m⁶A reader YTHDF2 binds to the m⁶A sites, leading to decreased TRIM21 mRNA stability. Consequently, TRIM21 suppression impairs ubiquitin-mediated p21 protein degradation. Taken together, m⁶A-mediated upregulation of p21, at both post-transcriptional and post-translational levels, contributes to DON-induced inhibition of hippocampal neuron proliferation. These results may provide new insights for epigenetic therapy of neurodegenerative diseases.