Project description:N6-methyladenosine (m6A) is the most abundant internal messenger (mRNA) modification in mammalian mRNA. This modification is reversible and non-stoichiometric, which potentially adds an additional layer of variety and dynamic control of mRNA metabolism. The m6A-modified mRNA can be selectively recognized by the YTH family “reader” proteins. The preferential binding of m6A-containing mRNA by YTHDF2 is known to reduce the stability of the target transcripts; however, the exact effects of m6A on translation has yet to be elucidated. Here we show that another m6A reader protein, YTHDF1, promotes ribosome loading of its target transcripts. YTHDF1 forms a complex with translation initiation factors to elevate the translation efficiency of its bound mRNA. In a unified mechanism of translation control through m6A, the YTHDF2-mediated decay controls the lifetime of target transcripts; whereas, the YTHDF1-based translation promotion increases the translation efficiency to ensure effective protein production from relatively short-lived transcripts that are marked by m6A. PAR-CLIP and RIP was used to identify YTHDF1 binding sites followed by ribosome profling and RNA seq to assess the consequences of YTHDF1 siRNA knock-down
Project description:N6-methyladenosine (m6A), the most abundant messenger RNA (mRNA) modification, has emerged as a critical post-transcriptional mechanism that regulates various aspect of mRNA metabolism including pre-mRNA processing, mRNA export, mRNA stability and translation efficiency. However the genetics basis of m6A is largely unexplored. In this work, we mapped m6A-QTLs in 60 LCLs and used the resulting tens of thousands of QTLs to provide insights to m6A biology and its contribution to human complex trait.
Project description:Cellular RNAs are covalently modified and these modifications can impact on all biological processes and hence are implicated in different types of diseases. Amongst RNA modifications, N6-methyladenosine (m6A) is one of the most widespread and has been found on messenger (mRNA), ribosomal (rRNA), non-coding and spliceosomal RNAs. We undertook a systematic screen to uncover new RNA-methyltransferases. We demonstrate that the methyltransferase-like 5 protein (METTL5) is an 18S rRNA specific methyltransferase and interacts specifically with Trmt122.
Project description:N6-methyladenosine (m6A) is the most abundant internal messenger (mRNA) modification in mammalian mRNA. This modification is reversible and non-stoichiometric, which potentially adds an additional layer of variety and dynamic control of mRNA metabolism. The m6A-modified mRNA can be selectively recognized by the YTH family “reader” proteins. The preferential binding of m6A-containing mRNA by YTHDF2 is known to reduce the stability of the target transcripts; however, the exact effects of m6A on translation has yet to be elucidated. Here we show that another m6A reader protein, YTHDF1, promotes ribosome loading of its target transcripts. YTHDF1 forms a complex with translation initiation factors to elevate the translation efficiency of its bound mRNA. In a unified mechanism of translation control through m6A, the YTHDF2-mediated decay controls the lifetime of target transcripts; whereas, the YTHDF1-based translation promotion increases the translation efficiency to ensure effective protein production from relatively short-lived transcripts that are marked by m6A.
Project description:N6-methyladenosine (m6A) plays critical roles in a wide range of physiological and pathological processes, and m6A methyltransferases are still being discovered for different RNA species in mammals. Here report a new m6A methyltransferase ZCCHC4 that methylates ribosomal RNA (rRNA) and interacts with messenger RNA (mRNA), ZCCHC4 has methylation activity on rRNA with a preference for AAC consensus sequence. ZCCHC4 can affect global translation through m6A methylation, mostly on 28S rRNA.
Project description:N6-methyladenosine (m6A), a major modification of messenger RNAs (mRNAs), plays critical roles in RNA metabolism and function. In addition to the internal m6A, N6, 2'-O-dimethyladenosine (m6Am) is present at the transcription start nucleotide of capped mRNAs in vertebrates. However, its biogenesis and functional role remain elusive. Using a reverse genetics approach, we identified PCIF1, a factor that interacts with the serine-5-phosphorylated carboxyl-terminal domain of RNA polymerase II, as a cap-specific adenosine methyltransferase (CAPAM) responsible for N6-methylation of m6Am. The crystal structure of CAPAM in complex with substrates revealed the molecular basis of cap-specific m6A formation. A transcriptome-wide analysis revealed that N6-methylation of m6Am promotes the translation of capped mRNAs. Thus, a cap-specific m6A writer promotes translation of mRNAs starting from m6Am.
Project description:N6-methyladenosine (m6A) is the most prevalent messenger RNA modification in eukaryotes, but the potential roles of m6A methylated mRNA in trophoblast upon hypoxia remain elusive.