Fig. 2
From: The interplay between m6A RNA methylation and noncoding RNA in cancer
Regulation of miRNAs by m6A modifications. Maturation of miRNA occurs in the nucleus and cytoplasm. Ι In the nucleus, the intranuclear enzyme Drosha, an RNase III endonuclease, cleaves primary microRNA (pri-miRNA) to precursor microRNA (pre-miRNA). In addition to Drosha, DGCR8 has also been shown to be critical for miRNA maturation. METTL3-methylated pri-miRNA is recognized and processed by DGCR8. Meanwhile, HNRNPA2B1 recognizes m6A methylation sites. In conclusion, m6A modifications assist DGCR8 in targeting pri-miRNA and promote pre-miRNA formation. II Dicer, another RNase III enzyme, cleaves pre-miRNA into mature miRNA after pre-miRNA is transported into the cytoplasm. Then, RISC integrates the mature miRNA and is guided to m6A methylation regulator mRNAs, resulting in disruption of translation by target mRNA cleavage