Project description:Several studies revealed an underlying disordered m6A regulatory network in human nasopharyngeal carcinoma (NPC). However, the roles of m6A regulators and sequential m6A dysregulation in NPC remain largely unknown. In the present study, we investigated the role of VIRMA and its underlying mechanisms in NPC. We performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) to identify the potential downstream targets of VIRMA that might be essential in NPC using HONE-1 cells with or without VIRMA silenced (two biological replicates).
Project description:N6-methyladenosine (m6A) modification plays crucial roles in tissue development and homeostasis. However, the mechanisms underlying cellular adaptation of m6A modification and their impact on protein synthesis machinery remain unclear. VIRMA, the largest and evolutionarily conserved core of the m6A methyltransferase complex, is highly expressed in the embryonic brain and various cancers. Here, we demonstrate that VIRMA-mediated m6A modification is essential for active ribosome biogenesis. VIRMA depletion destabilizes the entire writer complex and reduces m6A levels, leading to decreased proliferation and increased apoptosis of neural progenitor/stem cells (NPCs), ultimately causing severe forebrain developmental defects. Mechanistically, VIRMA depletion impairs ribosome biogenesis by inhibiting mRNA decay, triggering a p53-dependent stress response and compromising global protein synthesis. Importantly, these findings extend to human cancer cells, suggesting a potential conservation of this mechanism. Overall, our study reveals the critical role of m6A in adapting protein synthesis machinery during brain development and potentially in cancer.
Project description:N6-methyladenosine (m6A) modification plays crucial roles in tissue development and homeostasis. However, the mechanisms underlying cellular adaptation of m6A modification and their impact on protein synthesis machinery remain unclear. VIRMA, the largest and evolutionarily conserved core of the m6A methyltransferase complex, is highly expressed in the embryonic brain and various cancers. Here, we demonstrate that VIRMA-mediated m6A modification is essential for active ribosome biogenesis. VIRMA depletion destabilizes the entire writer complex and reduces m6A levels, leading to decreased proliferation and increased apoptosis of neural progenitor/stem cells (NPCs), ultimately causing severe forebrain developmental defects. Mechanistically, VIRMA depletion impairs ribosome biogenesis by inhibiting mRNA decay, triggering a p53-dependent stress response and compromising global protein synthesis. Importantly, these findings extend to human cancer cells, suggesting a potential conservation of this mechanism. Overall, our study reveals the critical role of m6A in adapting protein synthesis machinery during brain development and potentially in cancer.
Project description:N6-methyladenosine (m6A) is the most abundant internal RNA modification in mRNA molecules and plays important roles in multiple important biological processes including cancer development. KIAA1429/VIRMA is an important component of m6A methyltransferase complex to facilitate depositing m6A modification in RNA molecules. Here we found that KIAA1429/VIRMA was overexpressed in breast cancer patients among other m6A related enzymes. Breast cancer patients with higher KIAA1429 expression have worse survival compared with control group. In addition, KIAA1429/VIRMA protein mislocated in cytosol in breast cancer tissues and cell lines. KIAA1429/VIRMA depletion reduced breast cancer cell proliferation and migration. Mechanism studies showed that cytosolic expressed KIAA1429/VIRMA interacted with m6A reader protein IGF2BP3 and stabilized expression of m6A-modified HAS2 expression. HAS2 is downstream of KIAA1429/VIRMA to mediate breast cancer cell proliferation and migration and has positive correlation with KIAA1429/VIRMA expression in cancer patients.
Project description:N(6)-methyladenosine (m6A) plays an important role in the tumorigenesis and progression of cancers. However, the clinical significance of m6A and their regulatory mechanisms in nasopharyngeal carcinogenesis (NPC) remain largely unknown. In this study, we used the microarray analysis to study WTAP-mediated m6A modification profiles in human nasopharyngeal carcinoma cell line, HONE-1, by comparing 3 pairs of samples with or without WTAP knockdown.
Project description:To identify m6A-regulated mRNA targets affected by VIRMA overexpression we compared m6A peak abundance measured via m6A RNA immunoprecipitation sequenc-ing in SKBR3 cells overexpressing full-length VIRMA and eGFP control
Project description:N6-methyadenosine (m6A) is enriched in 3`UTR (3` untranslated region) and near stop codon of mature polyadenylated mRNAs in mammalian systems and has regulatory roles in eukaryotic mRNA transcriptome switch. Significantly, the mechanism for this modification preference remains unknown, however. Herein we report a characterization of the full m6A methyltransferase complex in HeLa cells identifying METTL3/METTL14/WTAP/VIRMA/HAKAI/ZC3H13 as the key components, and we show that VIRMA mediates preferential mRNA methylation in 3`UTR and near stop codon. Biochemical studies reveal that VIRMA recruits the catalytic core components METTL3/METTL14/WTAP to guide region-selective methylations. Around 60% of VIRMA mRNA immunoprecipitation targets manifest strong m6A enrichment in 3`UTR. Depletions of VIRMA and METTL3 induce 3`UTR lengthening of several hundred mRNAs with over 50% targets in common. VIRMA associates with polyadenylation cleavage factors CPSF5 and CPSF6 in an RNA-dependent manner. Depletion of CPSF5 leads to significant shortening of 3`UTR of over 2,800 mRNAs, 84% of which are modified with m6A. Together our studies provide insights into m6A deposition specificity in 3`UTR and its correlation with alternative polyadenylation.
Project description:Dysregulations of long non-coding RNAs (lncRNA) contribute to tumorigenesis by modulating specific cancer-related pathways, but the roles of m6A-enriched lncRNAs and underlying mechanisms remain elusive in nasopharyngeal carcinoma (NPC). Here, we reanalyzed the previous genome-wide analysis of lncRNA profile, and discerned that an oncogenic m6A-enriched lncRNA, LINC00839, which was substantially upregulated in NPC and correlated with poor clinical prognosis, promoted NPC growth and metastasis in vitro and in vivo. Mechanistically, LINC00839 interacted directly with transcription factor, TATA-box binding protein associated factor (TAF15), and coordinated its recruitment to promoter region of amine oxidase copper-containing 1 (AOC1), thereby activating AOC1 transcription in trans. Ectopic expression of AOC1 partially rescued the inhibitory effect of downregulation of LINC00839 in NPC. Furthermore, silencing vir like m6A methyltransferase associated (VIRMA) and insulin-like growth factor 2 mRNA-binding proteins 1 (IGF2BP1) were found to attenuate the expression level and RNA stability of LINC00839 in an m6A-dependent manner. This study unveils a novel oncogenic VIRMA/IGF2BP1–LINC00839–TAF15–AOC1 axis, and highlights significance and prognostic value of LINC00839 in NPC carcinogenesis.