Project description:Both mRNA and proteins can be modified through addition of methyl groups. For example, addition of N6-methyladenosine (m6A) to mRNAs is critical for human development and health. Post-translational methylation of proteins can impact the dynamic regulation of enzymatic activity. Here we sought to explore the nexus of transcriptional and post-translational methylation by studying the role of methylation of the core methyltransferase METTL3/METTL14 in m6A regulation. We found by mass spectrometry that METTL14 arginine 255 (R255) is methylated (R255me). Global mRNA m6A levels were greatly decreased in METTL14 R255K mutant mouse embryonic stem cells (mESCs). We further found that R255me greatly enhances the interaction of METTL3/METTL14 with WTAP and promotes the binding of the complex to substrate RNA.
Project description:The N6-methyladenosine (m6A) RNA modification serves crucial functions in RNA metabolism; however, the molecular mechanisms underlying the regulation of m6A are not well understood. Here, we establish arginine methylation of METTL14, a component of the m6A methyltransferase complex, as a novel pathway that controls the function of m6A in DNA repair. Specifically, protein arginine methyltransferase 1 (PRMT1) interacts with and methylates the intrinsically disordered C-terminus of METTL14, which promotes its interaction with RNA substrates, enhances its RNA methylation activity, and is crucial for its interaction with RNAPII. Mouse embryonic stem cells (mESCs) expressing arginine methylation-deficient METTL14 exhibit dramatically reduced global m6A levels. Transcriptome-wide m6A analysis reveals that arginine methylation-dependent m6A enhances the translation of genes essential for the repair of DNA interstrand crosslinks; thus, METTL14 arginine methylation-deficient mESCs are hypersensitive to DNA crosslinking agents. Collectively, these findings reveal important aspects of m6A regulation that could have broad implications in normal development and in diseases such as cancer.
Project description:We show that N6-methyladenosine (m6A), the most abundant internal modification in mRNA/lncRNA with still poorly characterized function, alters RNA structure to facilitate the access of RBM for heterogeneous nuclear ribonucleoprotein C (hnRNP C). We term this mechanism m6A-switch. Through combining PAR-CLIP with Me-RIP, we identify 39,060 m6A-switches among hnRNP C binding sites transcriptome-wide. We show that m6A-methyltransferases METTL3 or METTL14 knockdown decreases hnRNP C binding at 16,582 m6A-switches. Taken together, 2,798 m6A-switches of high confidence are identified to mediate RNA-hnRNP C interactions and affect diverse biological processes including cell cycle regulation. These findings reveal the biological importance of m6A and provide insights into the sophisticated regulation of RNA-RBP interactions through m6A-induced RNA structural remodeling. Measure the m6A methylated hnRNP C binding sites transcriptome-wide by PARCLIP-MeRIP; measure the differential hnRNP C occupancies upon METTL3/METTL14 knockdown by PAR-CLIP; measure RNA abundance and splicing level changes upon HNRNPC, METTL3 and METTL14 knockdown
Project description:Spermatogenesis is precisely controlled at the transcriptional, posttranscriptional, and translational levels. Here we report that N6-methyladenosine (m6A), an epitranscriptomic mark regulating gene expression, plays essential roles during spermatogenesis. We present comprehensive m6A mRNA methylomes of mouse spermatogenic cells from five developmental stages: undifferentiated spermatogonia, type A1 spermatogonia, preleptotene spermatocytes, pachytene/diplotene spermatocytes, and round spermatids. Germ cell-specific inactiva- tion of the m6A RNA methyltransferase Mettl3 or Mettl14 with Vasa-Cre causes loss of m6A and depletion of SSCs. m6A depletion dysregulates translation of transcripts that are required for SSC proliferation/differentiation. Com- bined deletion of Mettl3 and Mettl14 in advanced germ cells with Stra8-GFPCre disrupts spermiogenesis, whereas mice with single deletion of either Mettl3 or Mettl14 in advanced germ cells show normal spermatogenesis. The sper- matids from double-mutant mice exhibit impaired translation of haploid-specific genes that are essential for spermio- genesis. This study highlights crucial roles of mRNA m6A modification in germline development, potentially ensuring coordinated translation at different stages of spermatogenesis.
Project description:Non-small cell lung cancer (NSCLC) is a common type of lung cancer, characterized by a poor prognosis. N6-methyladenosine (m6A) emerges as one of the most important modification of RNA, and m6A modifier METTL14 were reported to play pivotal role in multiple cancer types. However, there are limited number of studies of METTL14 in lung cancer and there still lacks systematic investigation of the function, clinical significance and targets of METTL14 in NSCLC. Here, we first conducted comprehensive N6-methyladenosine profiling of non-small cell lung cancer patients, and acquired m6A RNA modification atlas and differentially methylated RNAs in non-small cell lung cancer patients. Then we focused on RNA methyl-transferase METTL14, and investigated its clinical significance and function in NSCLC. As a result, METTL14 was correlated with clinical pathological parameters of differentiation and M stage. Addionally, METTL14 promotes NSCLC growth, induces cell death, and enhances cell migration and invasion, in vitro. Finally, to identify potential targets of METTL14, RNA sequencing, METTL14 RIP-Sequencing, and METTL14 MeRIP-Sequencing were conducted. Five genes were commonly identified, including four protein coding genes (PPIEL, AKR1C1, SARS2 and CSF1R) and one lncRNA ASAP1-IT2. After validation with TCGA dataset, Colony Stimulating Factor 1 Receptor (CSF1R) showed significant positive coefficient with METTL14, and was presumed to be the target of METTl14 in lung cancer. In conclusion, this study, uncovered an m6A RNA modification atlas, and revealed the clinical significance, in vitro function and molecular targets CSF1R of METTL14 in NSCLC.
Project description:Non-small cell lung cancer (NSCLC) is a common type of lung cancer, characterized by a poor prognosis. N6-methyladenosine (m6A) emerges as one of the most important modification of RNA, and m6A modifier METTL14 were reported to play pivotal role in multiple cancer types. However, there are limited number of studies of METTL14 in lung cancer and there still lacks systematic investigation of the function, clinical significance and targets of METTL14 in NSCLC. Here, we first conducted comprehensive N6-methyladenosine profiling of non-small cell lung cancer patients, and acquired m6A RNA modification atlas and differentially methylated RNAs in non-small cell lung cancer patients. Then we focused on RNA methyl-transferase METTL14, and investigated its clinical significance and function in NSCLC. As a result, METTL14 was correlated with clinical pathological parameters of differentiation and M stage. Addionally, METTL14 promotes NSCLC growth, induces cell death, and enhances cell migration and invasion, in vitro. Finally, to identify potential targets of METTL14, RNA sequencing, METTL14 RIP-Sequencing, and METTL14 MeRIP-Sequencing were conducted. Five genes were commonly identified, including four protein coding genes (PPIEL, AKR1C1, SARS2 and CSF1R) and one lncRNA ASAP1-IT2. After validation with TCGA dataset, Colony Stimulating Factor 1 Receptor (CSF1R) showed significant positive coefficient with METTL14, and was presumed to be the target of METTl14 in lung cancer. In conclusion, this study, uncovered an m6A RNA modification atlas, and revealed the clinical significance, in vitro function and molecular targets CSF1R of METTL14 in NSCLC.
Project description:N6-methyladenosine (m6A) is the most abundant internal modification in the messenger RNA (mRNA) of all higher eukaryotes. This modification has been shown to be reversible in mammals; it is installed by a methyltransferase heterodimer complex of METTL3 and METTL14 bound with WTAP, and reversed by iron(II)- and α-ketoglutarate-dependent demethylases FTO and ALKBH5. This modification exhibits significant functional roles in various biological processes. The m6A modification as a RNA mark is recognized by reader proteins, such as YTH domain family proteins and HNRNPA2B1; m6A can also act as a structure switch to affect RNA-protein interactions for biological regulation. In Arabidopsis thaliana, the methyltransferase subunit MTA (the plant orthologue of human METTL3, encoded by At4g10760) was well characterized and FIP37 (the plant orthologue of human WTAP) was first identified as the interacting partner of MTA. Here we report the discovery and characterization of reversible m6A methylation mediated by AtALKBH10B (encoded by At4g02940) in A. thaliana, and noticeable roles of this RNA demethylase in affecting plant development and floral transition. Our findings reveal potential broad functions of reversible mRNA methylation in plants. m6A peaks were identified from wild type Columbia-0 and atalkbh10b-1 mutant in two biological replicates
Project description:N6-methyladenosine (m6A) is the most abundant internal mRNA modification in eukaryotes and is related to stability, localization, or translation efficiency in tumorigenesis. Autophagy plays an important role in the occurrence and development of tumours. However, the relationship between m6A and autophagy remains unclear. In this study, we used a rapamycin-induced autophagy model of oral squamous cell carcinoma (OSCC) cells, and observed increased m6A RNA methylation. When autophagy was activated, the methyltransferase-like 14 (METTL14) expression was upregulated and influenced the proliferation, migration, and invasiveness of OSCC cells. Through meRIP-seq and RNA-seq analysis, we found that METTL14 directly combined with eukaryotic translation initiation factor gamma 1 (eIF4G1) mRNA and decreased its RNA stability. According to the dual-luciferase reporter and mutagenesis assay, the mutated site 1 of exon 11 of eIF4G1 is the key target of METTL14. Knockdown of the main m6A binding protein YTHDF2 may rescue the shortened half-life of eIF4G1 mRNA induced by METTL14 overexpression. Furthermore, an in vivo tumour xenograft model confirmed that a high METTL14 expression can effectively reduce OSCC growth. Additionally, using clinical samples, we found that patients with advanced or moderately/poorly differentiated tumours exhibited lower METTL14 levels. Taken together, our results revealed that METTL14 mediated eIF4G1 expression via m6A modification and regulated autophagy levels and biological functions in OSCC. Our findings not only expand our understanding of the correlation between autophagy and RNA methylation in tumorigenesis but also present an opportunity to develop new therapeutic options.