mA readers ECT2/ECT3/ECT4 enhance mRNA stability through direct recruitment of the poly(A) binding proteins in Arabidopsis.

BACKGROUND

RNA N-methyladenosine (mA) modification is critical for plant growth and crop yield. mA reader proteins can recognize mA modifications to facilitate the functions of mA in gene regulation. ECT2, ECT3, and ECT4 are mA readers that are known to redundantly regulate trichome branching and leaf growth, but their molecular functions remain unclear.

RESULTS

Here, we show that ECT2, ECT3, and ECT4 directly interact with each other in the cytoplasm and perform genetically redundant functions in abscisic acid (ABA) response regulation during seed germination and post-germination growth. We reveal that ECT2/ECT3/ECT4 promote the stabilization of their targeted mA-modified mRNAs, but have no function in alternative polyadenylation and translation. We find that ECT2 directly interacts with the poly(A) binding proteins, PAB2 and PAB4, and maintains the stabilization of mA-modified mRNAs. Disruption of ECT2/ECT3/ECT4 destabilizes mRNAs of ABA signaling-related genes, thereby promoting the accumulation of ABI5 and leading to ABA hypersensitivity.

CONCLUSION

Our study reveals a unified functional model of mA mediated by mA readers in plants. In this model, ECT2/ECT3/ECT4 promote stabilization of their target mRNAs in the cytoplasm.