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:The RNA methyltransferase METTL1 catalyzes the N7-methylguanosine (m7G) modification of certain tRNAs, mRNAs, and miRNA precursors. However, the role of METTL1 and its cofactor WDR4 in cancer remains largely unexplored. Here we reveal the oncogenic role of METTL1/WDR4. METTL1 is frequently amplified and overexpressed in cancers and correlates with poor patient survival. METTL1 depletion in human cancer cells causes decreased abundance of m7G-modified tRNAs, altered cell cycle, and inhibits oncogenicity. Strikingly, METTL1/WDR4 overexpression induces oncogenic transformation and carcinogenesis. Mechanistically, we find increased abundance of a subset of m7G-modified tRNAs including tRNA-Arg(TCT), and increased translation of mRNAs enriched in the corresponding AGA codon including cell cycle regulators. Accordingly, expression of tRNA-Arg(TCT) is significantly elevated in many cancer types, correlates with patient survival, and overexpression of this tRNA enhances reporter gene expression and cell transformation. Thus, METTL1/WDR4-mediated m7G tRNA modification drives oncogenic transformation, thereby highlighting METTL1 as a promising cancer therapeutic target.
Project description:Reprogramming of mRNA translation drives malignant transformation and cancer development. Recently, increasing studies have demonstrated that tRNA modification emerges as a critical regulator of translational reprogramming; however, its function in cancers remains largely elusive. Herein, we identify the oncogenic role of tRNA N1-methyladenosine (m1A) modification in colorectal cancer (CRC). Targeting m1A methyltransferase TRMT6 in CRC cells decreases the abundance of a specific subset of tRNAs (e.g., tRNA-Arg-ACG-1-1, tRNA-Lys-TTT-1-1) and impairs histone mRNA translation in a codon-biased manner, thus restricting histone biosynthesis and cell cycle progression. We further demonstrate that the combination of TRMT6 inhibition and CDK4/6 inhibition shows a stronger anti-cancer effect on CRC cells by synergistically inhibit histone biosynthesis. Collectively, our study reveals that tRNA m1A modification acts as a translational checkpoint of histone biosynthesis and promotes CRC progression, providing new insights for the development of efficient therapeutic strategies against CRC.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:The RNA methyltransferase METTL1 catalyzes the N7-methylguanosine (m7G) modification of certain tRNAs, mRNAs, and miRNA precursors. However, the role of METTL1 and its cofactor WDR4 in cancer remains largely unexplored. Here we reveal the oncogenic role of METTL1/WDR4. METTL1 is frequently amplified and overexpressed in cancers and correlates with poor patient survival. METTL1 depletion in human cancer cells causes decreased abundance of m7G-modified tRNAs, altered cell cycle, and inhibits oncogenicity. Strikingly, METTL1/WDR4 overexpression induces oncogenic transformation and carcinogenesis. Mechanistically, we find increased abundance of a subset of m7G-modified tRNAs including tRNA-Arg(TCT), and increased translation of mRNAs enriched in the corresponding AGA codon including cell cycle regulators. Accordingly, expression of tRNA-Arg(TCT) is significantly elevated in many cancer types, correlates with patient survival, and overexpression of this tRNA enhances reporter gene expression and cell transformation. Thus, METTL1/WDR4-mediated m7G tRNA modification drives oncogenic transformation, thereby highlighting METTL1 as a promising cancer therapeutic target.
Project description:The RNA methyltransferase METTL1 catalyzes the N7-methylguanosine (m7G) modification of certain tRNAs, mRNAs, and miRNA precursors. However, the role of METTL1 and its cofactor WDR4 in cancer remains largely unexplored. Here we reveal the oncogenic role of METTL1/WDR4. METTL1 is frequently amplified and overexpressed in cancers and correlates with poor patient survival. METTL1 depletion in human cancer cells causes decreased abundance of m7G-modified tRNAs, altered cell cycle, and inhibits oncogenicity. Strikingly, METTL1/WDR4 overexpression induces oncogenic transformation and carcinogenesis. Mechanistically, we find increased abundance of a subset of m7G-modified tRNAs including tRNA-Arg(TCT), and increased translation of mRNAs enriched in the corresponding AGA codon including cell cycle regulators. Accordingly, expression of tRNA-Arg(TCT) is significantly elevated in many cancer types, correlates with patient survival, and overexpression of this tRNA enhances reporter gene expression and cell transformation. Thus, METTL1/WDR4-mediated m7G tRNA modification drives oncogenic transformation, thereby highlighting METTL1 as a promising cancer therapeutic target.