3′-Terminal 2′-O-methylation of lung cancer miR-21-5p enhances its stability and association with Argonaute 2

作者：Hongwei Liang, Zichen Jiao, Weiwei Rong, Shuang Qu, Zhicong Liao, Xinlei Sun, Wei Yao, Quan Zhao, Jun Wang, Yuan Liu, Xi Chen, Tao Wang, Chen‐Yu Zhang, Ke Zen · 发表于：Nucleic Acids Research · 年份：2020 · DOI：10.1093/nar/gkaa504 · 被引用次数：76 · 研究领域：MicroRNA in disease regulation、RNA modifications and cancer、Epigenetics and DNA Methylation

Methylation of miRNAs at the 2'-hydroxyl group on the ribose at 3'-end (2'-O-methylation, 2'Ome) is critical for miRNA function in plants and Drosophila. Whether this methylation phenomenon exists for mammalian miRNA remains unknown. Through LC-MS/MS analysis, we discover that majority of miR-21-5p isolated from human non-small cell lung cancer (NSCLC) tissue possesses 3'-terminal 2'Ome. Predominant 3'-terminal 2'Ome of miR-21-5p in cancer tissue is confirmed by qRT-PCR and northern blot after oxidation/β-elimination procedure. Cancerous and the paired non-cancerous lung tissue miRNAs display different pattern of 3'-terminal 2'Ome. We further identify HENMT1 as the methyltransferase responsible for 3'-terminal 2'Ome of mammalian miRNAs. Compared to non-methylated miR-21-5p, methylated miR-21-5p is more resistant to digestion by 3'→5' exoribonuclease polyribonucleotide nucleotidyltransferase 1 (PNPT1) and has higher affinity to Argonaute-2, which may contribute to its higher stability and stronger inhibition on programmed cell death protein 4 (PDCD4) translation, respectively. Our findings reveal HENMT1-mediated 3'-terminal 2'Ome of mammalian miRNAs and highlight its role in enhancing miRNA's stability and function.