Project description:Newly growing evidence highlights the essential role that epitranscriptomic marks play in the development of cancer; however, little is known about the role and implications of altered epitranscriptome deposition in prostate cancer. Here, we show that the transfer RNA N7-methylguanosine (m7G) transferase METTL1 is highly expressed in primary and advanced prostate tumours. Mechanistically, we find that METTL1 depletion causes the loss of m7G tRNA methylation and promotes the biogenesis of a novel class of small non-coding RNAs derived from 5’tRNA fragments. 5′ tRNA-derived small RNAs steer translation control to favour the synthesis of key regulators of tumour growth suppression, interferon pathway, and immune effectors. Knockdown of Mettl1 in prostate cancer preclinical models increases intratumoural infiltration of pro-inflammatory immune cells and enhances responses to immunotherapy, leading to decreased tumour progression. Collectively, our findings reveal a therapeutically actionable role of METTL1-directed m7G tRNA methylation in cancer cell translational control and tumour biology.
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: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:Newly growing evidence highlights the essential role that epitranscriptomic marks play in the development of many cancers; however, little is known about the role and implications of altered epitranscriptome deposition in prostate cancer. Here, we show that the transfer RNA N7-methylguanosine (m7G) transferase METTL1 is highly expressed in primary and advanced prostate tumours. Mechanistically, we find that METTL1 depletion causes the loss of m7G tRNA methylation and promotes the biogenesis of a novel class of small non-coding RNAs derived from 5'tRNA fragments. 5'tRNA-derived small RNAs steer translation control to favour the synthesis of key regulators of tumour growth suppression, interferon pathway, and immune effectors. Knockdown of Mettl1 in prostate cancer preclinical models increases intratumoural infiltration of pro-inflammatory immune cells and enhances responses to immunotherapy. Collectively, our findings reveal a therapeutically actionable role of METTL1-directed m7G tRNA methylation in cancer cell translation control and tumour biology.
Project description:N7-methylguanosine (m7G) modification is one of the most prevalent tRNA modifications in human. The precise function and molecular mechanism of m7G tRNA modification in regulation of cancer remain poorly understood. Here we showed that m7G tRNA modification, METTL1 and WDR4 are elevated in hepatocellular carcinoma (HCC) tissues and associated with HCC patient prognosis. Functionally, silencing METTL1 or WDR4 inhibits HCC cell proliferation, migration and invasion, while forced expression of wild type METTL1 but not its catalytic dead mutant promotes HCC progression. Knockdown of METTL1 reduces m7G tRNA modification and decreases m7G modified tRNA expression. Mechanistically, METTL1 depletion selectively decreases the mRNA translation of a subset of oncogenic genes, especially cell cycle and EGFR pathway genes, in m7G-related codon dependent manner. Moreover, in vivo studies using Mettl1 knock-in and knockout mice reveal a critical function of Mettl1 mediated m7G tRNA modifications in promoting hepatocarcinogenesis in the hydrodynamics transfection HCC model. Our work uncovers the critical functions of tRNA m7G modification in regulating cancer mRNA translation and promoting hepatocarcinogenesis, thus provides new insights into role of the mis-regulated tRNA modifications in cancers.
Project description:N7-methylguanosine (m7G) in variable loop region of tRNA stabilizes target tRNA expression, which is catalyzed by METTL1/WDR4 heterodimer. Here, we unveil essential functions of Mettl1 in Drosophila fertility. Mettl1-knockout (Mettl1-KO) decreases elongated spermatid and mature sperm, which is fully rescued by Mettl1-transgene expression, but not catalytic dead Mettl1-transgene, demonstrating that Mettl1-dependent m7G is required for spermatogenesis. Mettl1-KO shows loss of m7G modification on subset of tRNAs and decreased level of tRNA expression. Strikingly, overexpression of translational elongation factor EF1α that can compete with rapid tRNA decay (RTD) pathway in S. cerevisiae, significantly counteract the sterility in Mettl1-KO male, supporting a critical role of m7G tRNA modification in spermatogenesis. Ribo-seq analysis shows that Mettl1-KO elevates ribosome collisions at codons decoded by reduced tRNAs and significantly reduces translation of genes involved in elongated spermatid formation and sperm stability. These findings reveal a developmental role for m7G tRNA modifications and suggest that m7G modification-dependent tRNA stability differs among tissues.
Project description:The cancer cells selectively promote the translation of oncogenic mRNAs to facilitate cancer progression, while the molecular mechanisms remain unclear. The tRNA N7-methylguanosine (m7G) modification is not essential for yeast growth, but in mammals mis-regulations of tRNA m7G modification cause stem cell defect and developmental disorders. Here we found that tRNA m7G methyltransferase complex components METTL1 and WDR4 are elevated in esophageal squamous cell carcinoma (ESCC) tissues and associated with poor ESCC prognosis. Functionally, depletion of METTL1 or WDR4 suppresses proliferation, migration, and invasion of ESCC cells. In addition, forced expression of METTL1 or WDR4 promotes ESCC progression depending on the tRNA m7G methyltransferase activity. Mechanistically, METTL1 knockdown leads to reduced tRNA m7G modification and decreased expression of m7G-modified tRNAs. Depletion of METTL1 selectively reduces the translation of a subset of oncogenic transcripts, including the genes related to mTOR signaling and autophagy in m7G related codon dependent manner. Rescue assays revealed the essential function of RPTOR/ULK1/autophagy axis in METTL1 driven ESCC progression. Furthermore, ESCC initiation and progression models using Mettl1 conditional knockout and knockin mice uncovered the strong physiological function of Mettl1 in promoting in vivo ESCC tumorigenesis. Our study uncovered a new layer of translation regulation mechanism mediated by tRNA m7G modification, provided strong evidence to support the important physiological function of mis-regulated tRNA modification in cancer, and suggested that targeting METTL1 and its downstream signaling axis could be a promising strategy for ESCC treatment.