Identification of differential RNA modifications from nanopore direct RNA sequencing with xPore

Recent advances in sequencing technologies promise ultra-long reads of ∼100 kb in average, full-length mRNA or cDNA reads in high throughput and genomic contigs over 100 Mb in length. Existing alignment programs are unable or inefficient to process such data at scale, which presses for the development of new alignment algorithms. Show more

An extensive repertoire of modifications is known to underlie the versatile coding, structural and catalytic functions of RNA, but it remains largely uncharted territory. Although biochemical studies indicate that N(6)-methyladenosine (m(6)A) is the most prevalent internal modification in messenger RNA, an in-depth study of its distribution and functions has been impeded by a lack of robust analytical methods. Here we present the human and mouse m(6)A modification landscape in a transcriptome-wide manner, using a novel approach, m(6)A-seq, based on antibody-mediated capture and massively parallel sequencing. We identify over 12,000 m(6)A sites characterized by a typical consensus in the transcripts of more than 7,000 human genes. Sites preferentially appear in two distinct landmarks--around stop codons and within long internal exons--and are highly conserved between human and mouse. Although most sites are well preserved across normal and cancerous tissues and in response to various stimuli, a subset of stimulus-dependent, dynamically modulated sites is identified. Silencing the m(6)A methyltransferase significantly affects gene expression and alternative splicing patterns, resulting in modulation of the p53 (also known as TP53) signalling pathway and apoptosis. Our findings therefore suggest that RNA decoration by m(6)A has a fundamental role in regulation of gene expression. Show more

N6 -methyladenosine (m6A) is the most prevalent internal (non-cap) modification present in the messenger RNA (mRNA) of all higher eukaryotes 1,2 . Although essential to cell viability and development 3–5 , the exact role of m6A modification remains to be determined. The recent discovery of two m6A demethylases in mammalian cells highlighted the importance of m6A in basic biological functions and disease 6–8 . Here we show that m6A is selectively recognized by the human YTH domain family 2 (YTHDF2) protein to regulate mRNA degradation. We identified over 3,000 cellular RNA targets of YTHDF2, most of which are mRNAs, but which also include non-coding RNAs, with a conserved core motif of G(m6A)C. We further establish the role of YTHDF2 in RNA metabolism, showing that binding of YTHDF2 results in the localization of bound mRNA from the translatable pool to mRNA decay sites, such as processing bodies 9 . The C-terminal domain of YTHDF2 selectively binds to m6A-containing mRNA whereas the N-terminal domain is responsible for the localization of the YTHDF2-mRNA complex to cellular RNA decay sites. Our results indicate that the dynamic m6A modification is recognized by selective-binding proteins to affect the translation status and lifetime of mRNA. Show more