RNautophagy调控DNMT3a介导DNA甲基化的机制及其意义

细胞感知环境信号重构表观遗传密码而形成 “retrograde信号通路”的具体机制目前仍知之甚少。在前期研究中，我们发现：细胞自噬可抑制甲基转移酶DNMT3a表达而重塑DNA甲基化；linc00942可促进DNMT3a mRNA的m6A修饰而上调其表达；自噬可降解linc00942而抑制其表达。因此，自噬可能通过降解linc00942而抑制DNMT3a mRNA的m6A修饰，下调DNMT3a mRNA稳定性以降低其表达，从而重塑DNA甲基化谱。我们将在本项目中重点解析linc00942发生细胞自噬依赖性降解的调控机制，探索linc00942对DNMT3a mRNA m6a修饰及其稳定性的调控作用及其机制，阐明DNMT3a在建立细胞自噬等特征性DNA甲基化中的作用及其临床意义，从而揭示RNautophagy和RNA m6A修饰在retrograde信号通路重塑表观遗传密码中的作用及其意义。

In response to dynamic changes in the microenvironment, cells can epigenetically reprogram gene expression through retrograde signaling. In the preliminary exploration for this proposed study, we found that upon autophagy activation, DNA methylation was greatly impaired and DNMT3a expression was decreased, which can be rescued by autophagy inhibitor CQ (Chloroquine). Interestingly, DNMT3a expression seems to be affected by linc00942 which was highly upregulated in chemoresistant cells. Linc00942 knock-down not only reduced DNMT3a expression and DNA methylation, but also restored sensitivity to chemotherapy. Moreover, linc00942 seems to be degraded via RNautophagy and it can stabilize DNMT3a mRNA by enhancing its m6A modification. Therefore, we hypothesized that autophagy degrades linc00942 to abrogate m6A modification of DNMT3a mRNA, thus destabilizing DNMT3a mRNA to remodel DNA methylome. In chemoresistant cancer cells, autophagy is inactivated so that linc00942 is accumulated to stabilize DNMT3a and targeting linc00942 or DNMT3a can reverse chemoresistance. In this proposed study, we will try to explore the degradation of linc00942 via RNautophagy, the effect of linc00942 on m6A modification and stability of DNMT3a mRNA and the biological relevance of DNMT3a upregulation resulted from autophagy inhibition. By doing so, this study might be.valuable to clarify the regulation of DNA methylation by autophagy and provide novel insights to develop effective approaches for disorders related with aberrant DNA methylation.