Project description:N6-methyladenosine (m6A) is the most abundant modification of RNA in eukaryotic cells and play critical roles in cancer. While most related studies focus on m6A modifications in linear RNA, transcriptome-wide profiling and exploration of m6A modification in circular RNAs in cancer is still lacking. Here, we proposed a high-performance tools named Circm6A for the detection of m6A-circRNAs. Based on Circm6A results, we revealed the m6A-circRNAs genomic landscape of PDAC for the first time and shed new light on the regulatory aspect of circRNAs at the RNA epigenetic level.
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 one of the most abundant modifications in eukaryotic RNA. Recent mapping of m6A methylomes in mammals, yeast, and plants as well as characterization of m6A methyltransferases, demethylases, and binding proteins have revealed regulatory functions of this dynamic RNA modification. In bacteria, although m6A is present in ribosomal RNA (rRNA), its occurrence in messenger RNA (mRNA) still remains elusive. Here, we used liquid chromatography-mass spectrometry (LC-MS) to calculate the m6A/A ratio in mRNA from a wide range of bacterial species, which demonstrates that m6A is an abundant mRNA modification in tested bacteria. Subsequent transcriptome-wide m6A profiling in Escherichia coli and Pseudomonas aeruginosa revealed a conserved distinct m6A pattern that is significantly different from that in eukaryotes. Most m6A peaks are located inside open reading frames (ORF), and carry a unique consensus motif (GCCAU). Functional enrichment analysis of bacterial m6A peaks indicates that the majority of m6A-modified transcripts are associated with respiration, amino acids metabolism, stress response, and small RNAs genes, suggesting potential regulatory roles of m6A in these pathways. m6A profiling in E.coli and P.aeruginosa mRNA
Project description:N6-methyladenosine (m6A) is a widespread reversible chemical modification of RNAs, implicated in many aspects of RNA metabolism. Little quantitative information exists as to either how many transcript copies of particular genes are m6A modified (âm6A levelsâ), or the relationship of m6A modification(s) to alternative RNA isoforms. To deconvolute the m6A epitranscriptome, we developed m6A level and isoform-characterization sequencing (m6A-LAIC-seq). We found that cells exhibit a broad range of non-stoichiometric m6A levels with cell type specificity. At the level of isoform characterization, we discovered widespread differences in use of tandem alternative polyadenylation (APA) sites by methylated and nonmethylated transcript isoforms of individual genes. Strikingly, there is a strong bias for methylated transcripts to be coupled with proximal APA sites, resulting in shortened 3â untranslated regions (3â-UTRs), while nonmethylated transcript isoforms tend to use distal APA sites. m6A-LAIC-seq yields a new perspective on transcriptome complexity and links APA usage to m6A modifications. m6A-LAIC-seq of H1-ESC and GM12878 cell lines, each cell line has two replicates
Project description:<p>Despite the nuclear localization of the m6A machinery, the genomes of multiple exclusively-cytoplasmic RNA viruses, such as chikungunya (CHIKV) and dengue (DENV), are reported to be extensively m6A-modified. However, these findings are mostly based on m6A-seq, an antibody-dependent technique with a high rate of false positives. Here, we addressed the presence of m6A in CHIKV and DENV RNAs. For this, we combined m6A-seq and the antibody-independent SELECT and nanopore direct RNA sequencing techniques with functional, molecular, and mutagenesis studies. Following this comprehensive analysis, we found no evidence of m6A modification in CHIKV or DENV transcripts. Furthermore, depletion of key components of the host m6A machinery did not affect CHIKV or DENV infection. Moreover, CHIKV or DENV infection had no effect on the m6A machinery’s localization. Our results challenge the prevailing notion that m6A modification is a general feature of cytoplasmic RNA viruses and underscore the importance of validating RNA modifications with orthogonal approaches.</p>
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.
Project description:Serine/arginine-rich splicing factor 3 (SRSF3) functions to regulate mRNA alternative splicing, a molecular mechanism to process more than 90% of the protein-coding genes and provides an essential source for the biological versatility and targeting of SRSF3 could be a novel approach for cancer therapy. This study identify that SRSF3 expression was upregulated in pancreatic cancer tissues and associated with drug resistance and poor prognosis. Thus, we found that SRSF3 regulated ANRIL splicing and modified m6A modification of ANRIL in pancreatic cancer cells. More importantly, we demonstrated that the m6A methylation on lncRNA-ANRIL was essential for splicing process. Meanwhile, we also found that the different isoforms of ANRIL were differentially expressed in drug-resistant pancreatic cancer cell lines, and SRSF3 promotes gemcitabine resistance by regulating the expression of ANRIL-208. In addition, ANRIL-208 regulated pancreatic cancer cell chemoresistance by forming a complex with Ring1b and EZH2 and enhanced DNA homologous recombination repair (HR) capacity. In conclusion, the current study first established the link among SRSF3, m6A modification, lncRNA splicing, and DNA HR repair in pancreatic cancer, and first demonstrated that abnormal alternative splicing and m6A modification are closely related to chemotherapy resistance in pancreatic cancer.
Project description:Serine/arginine-rich splicing factor 3 (SRSF3) functions to regulate mRNA alternative splicing, a molecular mechanism to process more than 90% of the protein-coding genes and provides an essential source for the biological versatility and targeting of SRSF3 could be a novel approach for cancer therapy. This study identify that SRSF3 expression was upregulated in pancreatic cancer tissues and associated with drug resistance and poor prognosis. Thus, we found that SRSF3 regulated ANRIL splicing and modified m6A modification of ANRIL in pancreatic cancer cells. More importantly, we demonstrated that the m6A methylation on lncRNA-ANRIL was essential for splicing process. Meanwhile, we also found that the different isoforms of ANRIL were differentially expressed in drug-resistant pancreatic cancer cell lines, and SRSF3 promotes gemcitabine resistance by regulating the expression of ANRIL-208. In addition, ANRIL-208 regulated pancreatic cancer cell chemoresistance by forming a complex with Ring1b and EZH2 and enhanced DNA homologous recombination repair (HR) capacity. In conclusion, the current study first established the link among SRSF3, m6A modification, lncRNA splicing, and DNA HR repair in pancreatic cancer, and first demonstrated that abnormal alternative splicing and m6A modification are closely related to chemotherapy resistance in pancreatic cancer.
Project description:N6-methyladenosine (m6A) is one of the most popular RNA modifications, which is widely found in messenger RNAs (mRNAs) and non-coding RNA like long no-coding RNA (lncRNAs) and circular RNA (circRNAs).In our study,we provide m6A landscape of human ameloblastoma, which expands the understanding of m6A modifications and uncovers regulation of lncRNAs and circRNAs through m6A modification in ameloblastoma.