Gene expression profiles of primary myocardial cells treated with LPS and transfected siMETTL3 in rats
Ontology highlight
ABSTRACT: Methyltransferase-like 3 (METTL3) is the m6A methyltransferase which binds to METTL14 and wilms tumour 1-associated protein (WTAP) to form a complex catalyzing the m6A modification, the most abundant epitranscriptomic modification in eukaryotic mRNAs. And it has been demonstrated that m6A methylation mediated by METTL3 to be essential for inflammatory responses. To identify the messenger RNA (mRNA) profile in the primary myocardial cells that were treated with lipopolysaccharide (LPS) and/or small interference siMETTL3, six groups of primary myocardial cells were used for analysis.
Project description:N6-methyladenosine (m6A) methylation of mRNA by the methyltransferase complex (MTC), with core components including METTL3-METTL14 heterodimers and Wilms’ tumor 1-associated protein (WTAP), contributes to breast tumorigenesis, but the mechanism of MTC assembly remains elusive. Here, we identify a novel cleaved form METTL3a (residues 239-580 of METTL3), that is highly expressed in breast cancer. Furthermore, we find that both METTL3a and full-length METTL3 are required for MTC assembly, RNA m6A deposition, as well as cancer cell proliferation. Mechanistically, we find that METTL3a is required for METTL3-METTL3 interaction, which is a prerequisite step for recruitment of WTAP in MTC assembly. Analysis of m6A sequencing data shows that depletion of METTL3a globally disrupts m6A methylation, and METTL3a mediates mTOR activation via m6A-mediated suppression of TMEM127 expression. Consequently, we find that METTL3 cleavage is mediated by proteasome in an mTOR-dependent manner, revealing positive regulatory feedback between METTL3a and mTOR signaling. Our findings reveal METTL3a as an important component for MTC assembly, and suggest the METTL3a-mTOR axis as a potential therapeutic target for breast cancer.
Project description:SETD2 is the specific methyltransferase of H3K36me3, while METTL3, METTL14 and WTAP are the components of m6A methyltransferase complex. To understand the global effect of H3K36me3 on m6A modification, we compared the m6A profiling in SETD2 and METTL3, METTL14 or WTAP knockdown HepG2 cells, and found depletion of H3K36me3 by SETD2 silencing globally reduced m6A in human transcriptome. What’s more, most of the SETD2-dependent hypomethylation sites also responded to knockdown of METTL3, METTL14, or WTAP.
Project description:N6-methyladenosine (m6A) methylation is the most prevalent RNA modification, which plays a critical role in various bioprocesses.1 This modification is predominantly catalyzed by the m6A methyltransferase complex (MTC), consisting of core subunits such as methyltransferase-like 3 (METTL3) and methyltransferase-like 14 (METTL14), along with cofactors like Wilms tumor 1-associated protein (WTAP). We described the development of a first-in-class potent and selective METTL3-targeted degrader, WD6305, which can effectively degrade both METTL3 and its partner protein METTL14. WD6305 showed superior antiproliferative effects in multiple AML cell lines compared to its parent inhibitor, UZH2. Here, we want to compare the changes in genes between the two.
Project description:N6-methyladenosine (m6A) is the most prevalent internal modification found in mammalian messenger and non-coding RNAs. The discoveries of functionally significant demethylases that reverse this methylation as well as the recently revealed m6A distributions in mammalian transcriptomes strongly indicate regulatory functions of this modification. Here we report the identification and characterization of the mammalian nuclear RNA N6-adenosine methyltransferase core (RNMTC) complex. Besides METTL3, a methyltransferase which was the only known component of RNMTC in the past, we discovered that a previously uncharacterized methyltransferase, METTL14, exhibits a N6-adenosine methyltransferase activity higher than METTL3. Together with WTAP, the third component that dramatically affects the cellular m6A level, these three proteins form the core complex that orchestrates m6A deposition on mammalian nuclear RNA. Biochemistry assays, imaging experiments, as well as transcriptome-wide analyses of the binding sites and their effects on m6A methylation support methylation function and reveal new insights of RNMTC. PAR-CLIP and m6A-seq in HeLa cells
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:Chemical modification of RNAs is important for post-transcriptional gene regulation. The METTL3-METTL14 complex generates most N6-methyladenosine (m6A) modifications in mRNAs, and dysregulated methyltransferase expression has been linked to numerous cancers. Here we show that m6A modification location, rather than the overall modification level, can impact oncogenesis. A gain-of-function missense mutation found in cancer patients, METTL14R298P, promotes malignant cell growth in culture and in transgenic mice. The mutant methyltransferase preferentially modifies noncanonical sites and transforms gene expression without increasing global m6A levels in mRNAs. The altered substrate specificity is intrinsic to METTL3-METTL14, helping us to propose a structural model for how the METTL3-METTL14 complex detects RNA sequences. Together, our work highlights that m6A location is important for function and that noncanonical methylation sites may impact aberrant gene expression and oncogenesis.
Project description:N6-methyladenosine (m6A) methylation of mRNA by the methyltransferase complex (MTC), with core components including METTL3-METTL14 heterodimers and Wilms’ tumor 1-associated protein (WTAP), contributes to breast tumorigenesis, but the mechanism of MTC assembly remains elusive. Here, we identify a novel cleaved form METTL3a (residues 239-580 of METTL3), that is highly expressed in breast cancer. Furthermore, we find that both METTL3a and full-length METTL3 are required for MTC assembly, RNA m6A deposition, as well as cancer cell proliferation. Mechanistically, we find that METTL3a is required for METTL3-METTL3 interaction, which is a prerequisite step for recruitment of WTAP in MTC assembly. Analysis of m6A sequencing data shows that depletion of METTL3a globally disrupts m6A methylation, and METTL3a mediates mTOR activation via m6A-mediated suppression of TMEM127 expression. Consequently, we find that METTL3 cleavage is mediated by proteasome in an mTOR-dependent manner, revealing positive regulatory feedback between METTL3a and mTOR signaling. Our findings reveal METTL3a as an important component for MTC assembly, and suggest the METTL3a-mTOR axis as a potential therapeutic target for breast 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:N6-methyladenosine (m6A) is a common modification of mRNA, with potential roles in fine-tuning the RNA life cycle, but little is known about the pathways regulating this process and its physiological role. Here, we used mass-spectrometry to identify a dense network of proteins physically interacting with METTL3, a core component of the methyltransferase complex, and show that two of them, WTAP and KIAA1429, are required for methylation. Combining high resolution m6A-Seq with knockdown of WTAP allowed us to define accurate maps, at near single-nucleotide resolution, of sites of mRNA methylation across four dynamic programs in human and mouse, including development, differentiation, reprogramming and immune response. Internal WTAP-dependent methylation sites were largely static across the different surveyed conditions and present in the majority of mRNAs. However, methylations were found at much lower levels within highly expressed mRNAs, and methylation is inversely correlated with mRNA stability, consistent with a role in establishing an overall basal, cell-type invariant, distribution of degradation rates. In addition, we identify thousands of WTAP-independent methylation sites at transcription initiation sites, forming part of the mRNA cap structure. We show that the methylations occur at the first transcribed nucleotide, and find that thousands of transcripts are present in different isoforms differing in the methylation state of the first transcribed nucleotide, a previously unappreciated complexity of the transcriptome. Together, our data sheds new light on the proteomic and transcriptional underpinnings of this epitranscriptomic modification in mammals. Examination of m6A methylation across different knockdowns using shRNAs in mouse embryonic fibroblasts, in embyronic and adult brains, and in dendritic cell stimulated with LPS.
Project description:N6-methyladenosine (m6A) has been recently identified as a conserved epitranscriptomic modification of eukaryotic mRNAs, but its features, regulatory mechanisms, and functions in cell reprogramming are largely unknown. Here, we report m6A modification profiles in the mRNA transcriptomes of four cell types with different degrees of pluripotency. Comparative analysis reveals several features of m6A, especially gene- and cell-type-specific m6A mRNA modifications. We also show that microRNAs (miRNAs) regulate m6A modification via a sequence pairing mechanism. Manipulation of miRNA expression or sequences alters m6A modification levels through modulating the binding of METTL3 methyltransferase to mRNAs containing miRNA targeting sites. Increased m6A abundance promotes the reprogramming of mouse embryonic fibroblasts (MEFs) to pluripotent stem cells; conversely, reduced m6A levels impede reprogramming. Our results therefore uncover a role for miRNAs in regulating m6A formation of mRNAs and provide a foundation for future functional studies of m6A modification in cell reprogramming. m6A-seq in ESC, iPSC, NSC and sertoli cells.