Project description:Transfer RNAs (tRNAs) are exceptionally subject to modifications, including methylation. While mRNA methylation is emerging as an important regulator of biological and pathological processes in cancer, how post-transcriptional methylation of tRNAs contributes to cancer is largely unknown. Here we show that the RNA N7-methylguanosine (m7G) methyltransferase METTL1 is highly differentially expressed in prostate cancer compared to non-tumour prostate tissues. METTL1 expression regulation is mediated under the oncogenic PI3K-PTEN pathway. Knockdown of METTL1 dramatically inhibits prostate cancer cell growth and tumour progression in vivo. In contrast, overexpression of the wild type but not the catalytically inactive METTL1 potentiates cell growth. Thus, METTL1-mediated methylation is important for prostate tumorigenesis. Mechanistically we find that METTL1 depletion causes loss of m7G tRNA methylation and increases endonucleolytic cleavage of tRNA leading to an accumulation of 5′ tRNA-derived small RNA fragments. 5′ tRNA-derived fragments steer translation control to favour synthesis of key regulators of tumour growth suppression and immune rejection. In summary, our findings uncover a critical function of m7G tRNA methylation in directing translation control in cancer cells with important implications for tumour growth and unveil METTL1 inhibition as a promising anti-cancer therapeutic strategy.
Project description:Stable expression of tRNA-Glu(UUC) and tRNA-Arg(CCG) followed by whole-genome transcript stability measurements using a-amanitin mediated inhibition of RNA Pol II.
Project description:Abstract Transfer RNAs (tRNAs) are exceptionally subject to modifications, including methylation. While mRNA methylation is emerging as an important regulator of biological and pathological processes in cancer, how post-transcriptional methylation of tRNAs contributes to cancer is largely unknown. Here we show that the RNA N7-methylguanosine (m7G) methyltransferase METTL1 is highly differentially expressed in prostate cancer compared to non-tumour prostate tissues. METTL1 expression regulation is mediated by the oncogenic regulator PI3K, which is altered in most advanced prostate tumours. Knockdown of METTL1 dramatically inhibits prostate cancer cell growth and tumour progression in vivo. In contrast, overexpression of the wild type but not the catalytically inactive METTL1 potentiates cell growth. Thus, METTL1-mediated methylation is important for prostate tumorigenesis. Mechanistically we find that METTL1 depletion causes loss of m7G tRNA methylation and increases endonucleolytic cleavage of Cysteine tRNA leading to an accumulation of 5′ tRNA-derived small RNA fragments. 5′ tRNA-derived fragments steer translation control to favour synthesis of key regulators of tumour growth suppression and immune rejection. In summary, our findings uncover a critical function of m7G tRNA methylation in directing translation control in cancer cells with important implications for tumour growth and unveil METTL1 inhibition as a promising anti-cancer therapeutic strategy. induction and maintenance of naïve human pluripotency are governed by distinct signaling requirements. tRNAs from WT and METTL1 KO cells were subjected to NaBH4-Aniline treatment followed by RNA-seq to unveil methylation of guanosine-7 in tRNA with nucleotie resolution. RNA-seq libraries were also analysed to unveil tRNA stability or processing into tRNA-derived fragments in METTL1 KO cells.
Project description:As 5-15% of higher eukaryotes genes are transcription factors (TFs), the lack of transcription factor binding site (TFBS) information for most factors in most organisms limits the study of gene regulation. Here we describe a next-generation sequencing method, DNA affinity purification (DAP-Seq), an in vitro gDNA/TF interaction assay that produces whole-genome TFBS annotation for any factor from any organism. Like ChIP-Seq, DAP-Seq resolves TFBS as discrete peaks at genomic locations which allows for accurate motif prediction direct assignment of functionally relevant target genes, and shows better overlap with ChIP-Seq peaks than indirect motif assignment approaches. We applied DAP-Seq to a set of 50 transcription factors in eight Arabidopsis thaliana and one Zea Mays families to gain novel biological insight into TFBS architectures, functions, evolution and methylation-sensitivity. Overall, DAP-Seq offers a low-cost high-throughput approach to identify TFBS in native sequence context for any organism complete with all DNA chemical modifications.
Project description:Purpose: High-throughput RNA sequencing has accelerated discovery of the complex regulatory roles of small RNAs, such those derived from tRNAs. Also recent advances in high-throughput RNA sequencing has revealed the complex RNA modification landscape and the complex role these nucleosides modifactions have in cell signalling, stem cell biology, development and cancer. The goal of this study is to establish how m5C-tRNA methylation and tRNA-derived small RNAs can affect stem cell fucntion in cancer. Methods: four replicates of tRNAs and RNA buisulphite sequencing of wild-type (WT) and NSun2 -/- mouse skin squamous tumours were generated by deep sequencing, using Illumina HiSeq platform. Results: Our analyses reveal that inhibition of post-transcriptional cytosine-5 methylation locks stem cells in this distinct translational inhibition programme that results in tumour progression but that also sentizes cancer cells to genotoxic stress. Transfer RNA (tRNA) sequencing and RNA Bisulphite sequencing of wild-type (WT) and NSun2 -/- mouse skin squamous tumours
Project description:We generated a SNORD71 KO chondrocyte cell pool using CRISPR/Cas9 gene editing. A CRISPR control cell line was generated and used as a control. Levels of 2’-O-methylation of human rRNAs in SNORD71 KO cell pool and CRISPR control cells were evaluated by RiboMethSeq.
Project description:In this study, we use DNA affinity purification sequencing to identiy genome-wide binding of LFY transcription factor, a master regulator of flower development in Arabidopsis. We generated two sets of data, one using genomic DNA from plant tissue, thus retain DNA methylation, as probe for DNA affinity purification (DAP-seq dataset), and the other using PCR amplified genomic DNA (without DNA methylation; AmpDAP-seq dataset).