Reduction N6AMT1-mediated 6mA DNA modification promotes tumor progression [MeDIP-seq]
Ontology highlight
ABSTRACT: Background: DNA N6-methyladenosine (6mA) as a novel epigenetic signaling modification in humans and has been implicated in progression and tumorigenesis of several cancers. However, the function and mechanisms of 6mA in breast cancer (BC), the most common cancer among women, are unclear. Methods: The clinical role of 6mA was investigated by immunohistochemical (IHC) staining and Kaplan-Meier analysis of BC and their normal tissues. 6mA immunoprecipitation (IP) sequencing, mRNA sequencing and bioinformatics analysis were used to screen and validate the direct targets of 6mA. Results: Decreases in N6AMT1 correlated with the extent of 6mA in BC tissues and predicted a worse overall survival of BC patients. Knockdown N6AMT1 markedly reduced 6mA in DNA and promoted the proliferation and migration of BC in vivo and in vitro, whereas overexpression of N6AMT1 had the opposite effect, indicating N6AMT1 is a functional methyltransferase for DNA 6mA and relates with gene transcription. Critical negative regulators of the cell cycle, such as RB1, P21, REST and TP53 were identified as targets of N6AMT1 in BC. Conclusion: These results suggest N6AMT1 enhances DNA 6mA levels to repress tumor progression via transcriptional regulation of cell cycle inhibitors.
Project description:Background: DNA N6-methyladenosine (6mA) as a novel epigenetic signaling modification in humans and has been implicated in progression and tumorigenesis of several cancers. However, the function and mechanisms of 6mA in breast cancer (BC), the most common cancer among women, are unclear. Methods: The clinical role of 6mA was investigated by immunohistochemical (IHC) staining and Kaplan-Meier analysis of BC and their normal tissues. 6mA immunoprecipitation (IP) sequencing, mRNA sequencing and bioinformatics analysis were used to screen and validate the direct targets of 6mA. Results: Decreases in N6AMT1 correlated with the extent of 6mA in BC tissues and predicted a worse overall survival of BC patients. Knockdown N6AMT1 markedly reduced 6mA in DNA and promoted the proliferation and migration of BC in vivo and in vitro, whereas overexpression of N6AMT1 had the opposite effect, indicating N6AMT1 is a functional methyltransferase for DNA 6mA and relates with gene transcription. Critical negative regulators of the cell cycle, such as RB1, P21, REST and TP53 were identified as targets of N6AMT1 in BC. Conclusion: These results suggest N6AMT1 enhances DNA 6mA levels to repress tumor progression via transcriptional regulation of cell cycle inhibitors.
Project description:In human cells, 5-methylcytosine (5mC) DNA modification plays an important role in gene regulation. However, N6-methyladenine (6mA) DNA modification, which is predominantly present in prokaryotes, is considered to be absent in human genomic DNA. Here, using single molecule real-time (SMRT) sequencing on human blood, we show that DNA 6mA modification is extensively present in human genome, accounting for ~0.051% of the total adenines. [G/C]AGG[C/T] was the most significant motif associated with 6mA modification. 6mA sites are enriched in the exon coding regions and are associated with transcriptional activation. DNA N6-methyladenine and N6-demethyladenine modification in human are mediated by methyltransferase N6AMT1 and demethylase ALKBH1, respectively. The 6mA abundance is significantly lower in cancer tissues compared to adjacent normal tissues, which is accompanied with decreased N6AMT1 and increased ALKBH1 levels. Decrease of 6mA modification level stimulated tumorigenesis in human. Collectively, our results demonstrate that 6mA DNA modification is present in human tissues, and we describe a potential role of the N6AMT1/ALKBH1-6mA regulatory axis in the progression of human cancer.
Project description:DNA N6-methyldeoxyadenosine (6mA) is a well known prokaryotic DNA modification and has been shown to exist and play epigenetic roles in eukaryotic DNA. Here we report that 6mA accumulates up to 0.1% of total deoxyadenosine during early embryogenesis of vertebates, but diminishes with progression of the embryo development. During this process most 6mA locates in repetitive regions of the genome.
Project description:Mitochondrial biogenesis relies on both the nuclear and mitochondrial genomes, and imbalance in their expression can lead to inborn errors of metabolism, inflammation, and aging. Here, we investigate N6AMT1, a nucleo-cytosolic methyltransferase that exhibits genetic codependency with mitochondria. We determine transcriptional and translational profiles of N6AMT1 and report that it is required for the cytosolic translation of TRMT10C (MRPP1) and PRORP (MRPP3), two subunits of the mitochondrial RNAse P enzyme. In the absence of N6AMT1, or when its catalytic activity is abolished, RNA processing within mitochondria is impaired, leading to the accumulation of unprocessed and double-stranded RNA, thus preventing mitochondrial protein synthesis and oxidative phosphorylation, and leading to an immune response. Our work sheds light on the function of N6AMT1 in protein synthesis and highlights a cytosolic program required for proper mitochondrial biogenesis.
Project description:Mitochondrial biogenesis relies on both the nuclear and mitochondrial genomes, and imbalance in their expression can lead to inborn errors of metabolism, inflammation, and aging. Here, we investigate N6AMT1, a nucleo-cytosolic methyltransferase that exhibits genetic codependency with mitochondria. We determine transcriptional and translational profiles of N6AMT1 and report that it is required for the cytosolic translation of TRMT10C (MRPP1) and PRORP (MRPP3), two subunits of the mitochondrial RNAse P enzyme. In the absence of N6AMT1, or when its catalytic activity is abolished, RNA processing within mitochondria is impaired, leading to the accumulation of unprocessed and double-stranded RNA, thus preventing mitochondrial protein synthesis and oxidative phosphorylation, and leading to an immune response. Our work sheds light on the function of N6AMT1 in protein synthesis and highlights a cytosolic program required for proper mitochondrial biogenesis.
Project description:N6-methyladenine (6mA) DNA modification in eukaryotic genomes has emerged as a potential epigenetic mark. However, little is known about how 6mA epigenetic codes are read and interpreted in higher eukaryotes. Here we investigate 6mA genome-wide distributions in multiple higher eukaryotes. Using Drosophila as a pioneer system, we show that 6mA exhibits defined patterns and preferentially marks zygotic genes in early embryos. Moreover, we identify that the Fox-family protein, Jumu, is a "6mA-DNA reader" and functions in concert with DMAD to contribute to zygotic gene activation. Further methylome analysis reveals that 6mA modification has common features in genomic DNA from mouse, rat and monkey, and that "forkhead-domain-binding motifs" are enriched in 6mA-marked DNA of these genomes, in a way similar to Drosophila. Collectively, our findings identify the 6mA DNA reader protein and suggest a conserved 6mA-based mechanism in higher eukaryotes.
Project description:Mitochondrial biogenesis relies on both the nuclear and the mitochondrial genomes, and the mechanisms that support their coordinated expression are not fully understood. Improper mitochondrial DNA expression can lead to inborn error of metabolism, inflammation, and aging. Here, we investigate N6AMT1, a nucleo-cytosolic multi-substrate methyltransferase. We analyze genetic dependency, transcription, translation, and proteomic profiles of N6AMT1-depleted cells and report that N6AMT1 is necessary for the cytosolic translation of factors involved in mitochondrial RNA metabolism, including subunits of the mitochondrial RNase P. In the absence of N6AMT1, RNA processing and translation within mitochondria are impaired, while double-stranded RNA accumulates in mitochondrial RNA granules causing an interferon response. Our work highlights a cytosolic program required for proper mitochondrial biogenesis, with consequences on innate immunity.