Project description:Autosomal-recessive loss of the NSUN2 gene has been recently identified as a causative link to intellectual disability disorders in humans. NSun2 is an RNA methyltransferase modifying cytosine-5 in transfer RNAs (tRNA). Whether NSun2 methylates additional RNA species is currently debated. Here, we adapted the individual-nucleotide resolution UV cross-linking and immunoprecipitation method (iCLIP) to identify NSun2-mediated methylation in RNA transcriptome. We confirm site-specific methylation in tRNA and identify messenger and non-coding RNAs as potential methylation targets for NSun2. Using RNA bisulfite sequencing we establish Vault non-coding RNAs as novel substrates for NSun2 and identified six cytosine-5 methylated sites. Furthermore, we show that loss of cytosine-5 methylation in Vault RNAs causes aberrant processing into argonaute-associating small RNA fragments (svRNA). Thus, impaired Vault non-coding RNA processing may be an important contributor to the etiology of NSUN2-deficieny human disorders. mRNA-seq in Embryonic kidney (HEK293) cells transfected with siRNA against Nsun2 vs control
Project description:Mutations in the cytosine-5 RNA methyltransferase NSun2 can cause Intellectual Disability (ID) and symptoms commonly found in patients with Dubowitz syndrome. By analysing gene expression data with the global cytosine-5 RNA methylome in NSun2-deficient mice, we find that loss of cytosine-5 RNA methylation increases the fragmentation of transfer RNAs (tRNA) leading to an accumulation of 5M-bM-^@M-^Y halves. Cleavage of tRNAs by Angiogenin is a common cellular stress response to silence translational programmes, and we show that Angiogenin binds tRNAs lacking site-specific NSun2-methylation with higher affinity. Furthermore, cells lacking functional NSun2 up-regulate stress markers, and deletion of NSun2 compromises cellular survival in response stress stimuli including UV-light and oxidative stress. The decreased tolerance of NSun2 null cells towards oxidative stress can be rescued through inhibition of Angiogenin. In conclusion, cytosine-5 RNA methylation is an essential post-transcriptional mechanism during cellular stress responses and NSun2-mediated tRNA methylation protects from Angiogenin-dependent stress-induced RNA cleavage. RNA Methylation profiling by high throughput sequencing small non-coding RNA profiling by high throughput sequencing Pol III Chromatin-IP profiling by high throughput sequencing
Project description:Background: As a widespread post-transcriptional RNA modification, N5-methylcytosine (m5C) is implicated in a variety of cellular responses and processes that regulate RNA metabolism. Despite this, a clear understanding of m5C modification’s role and mechanism in angiogenesis is still lacking. Methods: Single-cell RNA sequencing data was analyzed to determine expression of m5C methylase NSUN2. m5C levels were determined by mRNA isolation and anti-m5C dot blot in both hypoxia-induced endothelial cells (ECs) and laser-induced choroidal neovascularization (CNV). In addition, endothelial cell and endothelium‐specific NSUN2‐knockout mouse model were used to investigate the effect of NSUN2 silence on angiogenic phenotype. Genome-wide multiomics analyses were performed to identify the functional target of NSUN2, including proteomic analysis, transcriptome screening and m5C-methylated RNA immunoprecipitation sequencing (m5C-meRIP-seq). CUT&Tag sequencing was performed to test the histone lactylation signal in the promoter region of NSUN2. Finally, AAV-mediated short hairpin RNAi knockdown of NSUN2 gene expression (AAV-shNSUN2) was constructed to investigate the effect of inhibiting CNV. Results: First, we discovered that m5C methylase NSUN2 expression level and mRNA m5C level were significantly higher in CNV-ECs than in normal ECs. NSUN2 knockdown in ECs inhibited proliferative, migration, and tube formation activities of ECs. Moreover, compared with EC NSUN2flox/flox mice, EC-specific NSUN2-deficient (EC NSUN2-/-) mice displayed less retinal vascular leakage after laser induction. Through multiomics analyses, we subsequently identified A-kinase anchoring protein 2 (AKAP2), a scaffolding protein which isolate Protein kinase A (PKA) to specific subcellular locations through binding to its regulatory subunit, as a downstream candidate target of NSUN2 in ECs. Overexpression of exogenous AKAP2 markedly reversed the inhibitory phenotypes in NSUN2-deficient ECs. Interestingly, laser induced NSUN2 up-regulation was driven by lactate-mediated lactylation on histone H3K18. In CNV models, AAV-mediated repression of NSUN2 modulated highly retinal vascular leakage and choroidal thickness. Conclusion: Overall, our findings indicate that NSUN2 is a novel therapeutic target for choroidal neovascularization.
Project description:Mutations in the cytosine-5 RNA methyltransferase NSun2 can cause Intellectual Disability (ID) and symptoms commonly found in patients with Dubowitz syndrome. By analysing gene expression data with the global cytosine-5 RNA methylome in NSun2-deficient mice, we find that loss of cytosine-5 RNA methylation increases the fragmentation of transfer RNAs (tRNA) leading to an accumulation of 5’ halves. Cleavage of tRNAs by Angiogenin is a common cellular stress response to silence translational programmes, and we show that Angiogenin binds tRNAs lacking site-specific NSun2-methylation with higher affinity. Furthermore, cells lacking functional NSun2 up-regulate stress markers, and deletion of NSun2 compromises cellular survival in response stress stimuli including UV-light and oxidative stress. The decreased tolerance of NSun2 null cells towards oxidative stress can be rescued through inhibition of Angiogenin. In conclusion, cytosine-5 RNA methylation is an essential post-transcriptional mechanism during cellular stress responses and NSun2-mediated tRNA methylation protects from Angiogenin-dependent stress-induced RNA cleavage.
Project description:Autosomal-recessive loss of the NSUN2 gene has been recently identified as a causative link to intellectual disability disorders in humans. NSun2 is an RNA methyltransferase modifying cytosine-5 in transfer RNAs (tRNA). Whether NSun2 methylates additional RNA species is currently debated. Here, we adapted the individual-nucleotide resolution UV cross-linking and immunoprecipitation method (iCLIP) to identify NSun2-mediated methylation in RNA transcriptome. We confirm site-specific methylation in tRNA and identify messenger and non-coding RNAs as potential methylation targets for NSun2. Using RNA bisulfite sequencing we establish Vault non-coding RNAs as novel substrates for NSun2 and identified six cytosine-5 methylated sites. Furthermore, we show that loss of cytosine-5 methylation in Vault RNAs causes aberrant processing into argonaute-associating small RNA fragments (svRNA). Thus, impaired Vault non-coding RNA processing may be an important contributor to the etiology of NSUN2-deficieny human disorders. Identification of Nsun2 targets by miCLIP in Embryonic kidney (HEK293) cells
Project description:We perfomed RNA-seq analysis using HPV16-postive CaSki and SiHa cells and HPV18-postive HeLa cells for HPV integration and gene expression analyses