Gene-silencing activity of small RNAs controlled by TRMT6/61A-dependent base methylation
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE171040 | GEO | 2022/02/09
REPOSITORIES: GEO
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Project description:Gene expression can be post-transcriptionally regulated via dynamic and reversible RNA modifications. N1-methyladenosine (m1A) is a recently identified mRNA modification; however, little is known about its precise location, regulation and function. Here, we develop a single-nucleotide resolution m1A profiling method, based on m1A-induced misincorporation during reverse transcription, and report distinct classes of m1A methylome in the human transcriptome. m1A in the 5’-untranslated region, particularly those located exactly at the first nucleotide of mRNA transcripts, associates with increased translation efficiency. A different subset of m1A sites exhibit a GUUCRA tRNA-like motif, are evenly distributed in the transcriptome and are dependent on the methyltransferase complex TRMT6/61A. Additionally, we show for the first time that m1A is prevalent in the mitochondrial-encoded transcripts. Manipulation of m1A level via TRMT61B, a mitochondria-localizing m1A methyltransferase, demonstrates that m1A in mitochondrial mRNA interferes with translation. Collectively, our approaches reveal distinct classes of m1A methylome and provide a resource for functional studies of m1A-mediated epitranscriptomic regulation.
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Project description:Increased protein translation plays a critical role in cancer development and treatment1,2. However, the molecular mechanism that is involved in this process remains poorly understood. N1-methyladenosine (m1A) methylation in RNA accounts for regulating mRNA translation in a post-transcriptional manner3,4. Here we show that m1A methylation levels are remarkably elevated in hepatocellular carcinoma (HCC) patient tumor tissues, especially in patients with microscopic vascular invasion (MVI). Moreover, m1A methylation signals are increased in liver cancer stem cells (CSCs) and are negatively correlated with HCC patient survival. Consistently, TRMT6 and TRMT61A, forming m1A methyltransferase complex, are highly expressed in advanced HCC tumors and are negatively correlated with HCC survival. TRMT6/TRMT61A-mediated m1A methylations are required for self-renewal of liver CSCs and tumorigenesis. Mechanistically, TRMT6/TRMT61A-dependent m1A in tRNA boost PPARδ expression, which triggers cholesterol synthesis to activate Hedgehog signaling, driving self-renewal of liver CSCs and tumorigenesis. For potential therapeutic benefit, we further identify a specific inhibitor against TRMT6/TRMT61A complex that exerts effective therapeutic effect on liver cancer with high m1A methylations. Our findings provide novel insights into the function and molecular mechanism of m1A modifications underlying liver tumorigenesis and drug target, which will serve as a new biomarker for HCC and pave a new way to develop more effective therapeutic strategies for HCC patients.
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Project description:N1-methyladenosine (m1A) is an abundant post-transcriptional RNA modification, yet little is known about its prevalence, topology and dynamics in mRNA. Here, we show that m1A is abundant in human mRNA, with an m1A/A ratio of ~0.02%. We develop m1A-ID-Seq, based on m1A immunoprecipitation and the inherent property of m1A to stall reverse transcription, for the transcriptome-wide m1A analysis. m1A-ID-Seq identifies 901 m1A peaks (from 583 genes) in mRNA and ncRNA, and reveals a prominent feature of enrichment in the 5â-untranslated region of mRNA transcripts, distinct from that of N6-methyladenosine, the most abundant internal mammalian mRNA modification. m1A in mRNA is also reversible by ALKBH3, a known DNA/RNA demethylase. Lastly, m1A responds dynamically to stimuli and hundreds of stress-induced m1A sites are identified. Collectively, our approaches allow comprehensive analysis of m1A methylation and provide an important tool for functional studies of potential epigenetic regulation via the reversible and dynamic m1A methylation. Identification of m1A sites in human embryonic kidney cells. Comparisons of m1A profiles of wild type HEK293T with ALKBH3 knock out cell line reveals the ALKBH3 specific sites. Stress inducible m1A sites are also identified by comparing the profiles of untreated cells with stress treated cells.
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Project description:N1-Methyladenosine (m1A) is a prevalent post-transcriptional RNA modification, yet little is known about its abundance, topol- ogy and dynamics in mRNA. Here, we show that m1A is prevalent in Homo sapiens mRNA, which shows an m1A/A ratio of ~0.02%. We develop the m1A-ID-seq technique, based on m1A immunoprecipitation and the inherent ability of m1A to stall reverse tran- scription, as a means for transcriptome-wide m1A profiling. m1A-ID-seq identifies 901 m1A peaks (from 600 genes) in mRNA and noncoding RNA and reveals a prominent feature, enrichment in the 5' untranslated region of mRNA transcripts, that is dis- tinct from the pattern for N6-methyladenosine, the most abundant internal mammalian mRNA modification. Moreover, m1A in mRNA is reversible by ALKBH3, a known DNA/RNA demethylase. Lastly, we show that m1A methylation responds dynamically to stimuli, and we identify hundreds of stress-induced m1A sites. Collectively, our approaches allow comprehensive analysis of m1A modification and provide tools for functional studies of potential epigenetic regulation via the reversible and dynamic m1A methylation.
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