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Mol Cell. 2019 Apr 19. pii: S1097-2765(19)30265-5. doi: 10.1016/j.molcel.2019.03.036. [Epub ahead of print]

Transcriptome-wide Mapping of Internal N7-Methylguanosine Methylome in Mammalian mRNA.

Author information

1
Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, Chicago, IL 60637, USA.
2
Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai 200032, China; Institute of Biomedical Sciences, Fudan University, Shanghai 200032, China.
3
The State Key Laboratory of Biocontrol, MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510060, China.
4
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
5
Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA; Howard Hughes Medical Institute, The University of Chicago, Chicago, IL 60637, USA. Electronic address: chuanhe@uchicago.edu.

Abstract

N7-methylguanosine (m7G) is a positively charged, essential modification at the 5' cap of eukaryotic mRNA, regulating mRNA export, translation, and splicing. m7G also occurs internally within tRNA and rRNA, but its existence and distribution within eukaryotic mRNA remain to be investigated. Here, we show the presence of internal m7G sites within mammalian mRNA. We then performed transcriptome-wide profiling of internal m7G methylome using m7G-MeRIP sequencing (MeRIP-seq). To map this modification at base resolution, we developed a chemical-assisted sequencing approach that selectively converts internal m7G sites into abasic sites, inducing misincorporation at these sites during reverse transcription. This base-resolution m7G-seq enabled transcriptome-wide mapping of m7G in human tRNA and mRNA, revealing distribution features of the internal m7G methylome in human cells. We also identified METTL1 as a methyltransferase that installs a subset of m7G within mRNA and showed that internal m7G methylation could affect mRNA translation.

KEYWORDS:

METTL1; N(7)-methylguanosine; RNA modification; base-resolution; epitranscriptomics; m(7)G; m(7)G-MeRIP-seq; m(7)G-seq; mRNA modification; tRNA modification; translation regulation

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