RNA Modification in the Immune System.

Characterization of RNA modifications has identified their distribution features and molecular functions. Dynamic changes in RNA modification on various forms of RNA are essential for the development and function of the immune system. In this review, we discuss the value of innovative RNA modification profiling technologies to uncover the function of these diverse, dynamic RNA modifications in various immune cells within healthy and diseased contexts. Further, we explore our current understanding of the mechanisms whereby aberrant RNA modifications modulate the immune milieu of the tumor microenvironment and point out outstanding research questions.

ALKBH1-Mediated tRNA Demethylation Regulates Translation.

tRNA is a central component of protein synthesis and the cell signaling network. One salient feature of tRNA is its heavily modified status, which can critically impact its function. Here, we show that mammalian ALKBH1 is a tRNA demethylase. It mediates the demethylation of N1-methyladenosine (m1A) in tRNAs. The ALKBH1-catalyzed demethylation of the target tRNAs results in attenuated translation initiation and decreased usage of tRNAs in protein synthesis. This process is dynamic and responds to glucose availability to affect translation. Our results uncover reversible methylation of tRNA as a new mechanism of post-transcriptional gene expression regulation.

N(6)-methyladenosine Modulates Messenger RNA Translation Efficiency.

N(6)-methyladenosine (m(6)A) is the most abundant internal modification in mammalian mRNA. This modification is reversible and non-stoichiometric and adds another layer to the dynamic control of mRNA metabolism. The stability of m(6)A-modified mRNA is regulated by an m(6)A reader protein, human YTHDF2, which recognizes m(6)A and reduces the stability of target transcripts. Looking at additional functional roles for the modification, we find that another m(6)A reader protein, human YTHDF1, actively promotes protein synthesis by interacting with translation machinery. In a unified mechanism of m(6)A-based regulation in the cytoplasm, YTHDF2-mediated degradation controls the lifetime of target transcripts, whereas YTHDF1-mediated translation promotion increases translation efficiency, ensuring effective protein production from dynamic transcripts that are marked by m(6)A. Therefore, the m(6)A modification in mRNA endows gene expression with fast responses and controllable protein production through these mechanisms.

N6-methyldeoxyadenosine marks active transcription start sites in Chlamydomonas.

N(6)-methyldeoxyadenosine (6mA or m(6)A) is a DNA modification preserved in prokaryotes to eukaryotes. It is widespread in bacteria and functions in DNA mismatch repair, chromosome segregation, and virulence regulation. In contrast, the distribution and function of 6mA in eukaryotes have been unclear. Here, we present a comprehensive analysis of the 6mA landscape in the genome of Chlamydomonas using new sequencing approaches. We identified the 6mA modification in 84% of genes in Chlamydomonas. We found that 6mA mainly locates at ApT dinucleotides around transcription start sites (TSS) with a bimodal distribution and appears to mark active genes. A periodic pattern of 6mA deposition was also observed at base resolution, which is associated with nucleosome distribution near the TSS, suggesting a possible role in nucleosome positioning. The new genome-wide mapping of 6mA and its unique distribution in the Chlamydomonas genome suggest potential regulatory roles of 6mA in gene expression in eukaryotic organisms.

Dendritic Cells but Not Macrophages Sense Tumor Mitochondrial DNA for Cross-priming through Signal Regulatory Protein α Signaling.

Inhibition of cytosolic DNA sensing represents a strategy that tumor cells use for immune evasion, but the underlying mechanisms are unclear. Here we have shown that CD47-signal regulatory protein α (SIRPα) axis dictates the fate of ingested DNA in DCs for immune evasion. Although macrophages were more potent in uptaking tumor DNA, increase of DNA sensing by blocking the interaction of SIRPα with CD47 preferentially occurred in dendritic cells (DCs) but not in macrophages. Mechanistically, CD47 blockade enabled the activation of NADPH oxidase NOX2 in DCs, which in turn inhibited phagosomal acidification and reduced the degradation of tumor mitochondrial DNA (mtDNA) in DCs. mtDNA was recognized by cyclic-GMP-AMP synthase (cGAS) in the DC cytosol, contributing to type I interferon (IFN) production and antitumor adaptive immunity. Thus, our findings have demonstrated how tumor cells inhibit innate sensing in DCs and suggested that the CD47-SIRPα axis is critical for DC-driven antitumor immunity.

Author Correction: Anti-tumour immunity controlled through mRNA m6A methylation and YTHDF1 in dendritic cells.

In this Letter, a citation to 'Fig. 1e' has been corrected to 'Fig. 1d' in the sentence starting "By contrast, the anti-tumour response…". This has been corrected online.

Anti-tumour immunity controlled through mRNA m6A methylation and YTHDF1 in dendritic cells.

There is growing evidence that tumour neoantigens have important roles in generating spontaneous antitumour immune responses and predicting clinical responses to immunotherapies1,2. Despite the presence of numerous neoantigens in patients, complete tumour elimination is rare, owing to failures in mounting a sufficient and lasting antitumour immune response3,4. Here we show that durable neoantigen-specific immunity is regulated by mRNA N6-methyadenosine (m6A) methylation through the m6A-binding protein YTHDF15. In contrast to wild-type mice, Ythdf1-deficient mice show an elevated antigen-specific CD8+ T cell antitumour response. Loss of YTHDF1 in classical dendritic cells enhanced the cross-presentation of tumour antigens and the cross-priming of CD8+ T cells in vivo. Mechanistically, transcripts encoding lysosomal proteases are marked by m6A and recognized by YTHDF1. Binding of YTHDF1 to these transcripts increases the translation of lysosomal cathepsins in dendritic cells, and inhibition of cathepsins markedly enhances cross-presentation of wild-type dendritic cells. Furthermore, the therapeutic efficacy of PD-L1 checkpoint blockade is enhanced in Ythdf1-/- mice, implicating YTHDF1 as a potential therapeutic target in anticancer immunotherapy.

A Highly Sensitive and Robust Method for Genome-wide 5hmC Profiling of Rare Cell Populations.

We present a highly sensitive and selective chemical labeling and capture approach for genome-wide profiling of 5-hydroxylmethylcytosine (5hmC) using DNA isolated from ∼1,000 cells (nano-hmC-Seal). Using this technology, we assessed 5hmC occupancy and dynamics across different stages of hematopoietic differentiation. Nano-hmC-Seal profiling of purified Tet2-mutant acute myeloid leukemia (AML) murine stem cells allowed us to identify leukemia-specific, differentially hydroxymethylated regions that harbor known and candidate disease-specific target genes with differential 5hmC peaks compared to normal stem cells. The change of 5hmC patterns in AML strongly correlates with differential gene expression, demonstrating the importance of dynamic alterations of 5hmC in regulating transcription in AML. Together, covalent 5hmC labeling offers an effective approach to study and detect DNA methylation dynamics in in vivo disease models and in limited clinical samples.

Knockdown of AMIGO2 suppresses proliferation and migration through regulating PPAR-γ in bladder cancer.

PURPOSE: This study aims to reveal the relationship between AMIGO2 and proliferation, migration and tumorigenicity of bladder cancer, and explore the potential molecular mechanisms. METHODS: The expression level of AMIGO2 is measured by qRT-PCR and immunohistochemistry (IHC). Stable AMIGO2 knockdown cell lines T24 and 5637 were established by lentivirus transfection. Cell Counting Kit (CCK-8 assay) was produced to determine cell proliferation, flow cytometry analysis was utilized to detect cell cycle, and wound healing assay was proceeded to test migration ability of bladder cancer cells. Xenograft mouse model was established for investigating the effect of AMIGO2 on tumor formation in vivo. The RNA Sequencing technology was applied to explore the underlying mechanisms. The expression level of PPAR-γ was measured by Western Blot. RESULTS: AMIGO2 was upregulated in bladder cancer cells and tissues. Inhibited expression of AMIGO2 suppresses cell proliferation and migration. Low AMIGO2 expression inhibited tumorigenicity of 5637 in nude mice. According to RNA-Seq and bioinformatics analysis, 917 DEGs were identified. The DEGs were mainly enriched in cell-cell adhesion, peroxisome proliferators-activated receptors (PPARs) signaling pathway and some other pathways. PPAR-γ is highly expressed in bladder cancer cell lines T24 and 5637, but when AMIGO2 is knocked down in T24 and 5637, the expression level of PPAR-γ is also decreased, and overexpression of PPAR-γ could reverse the suppression effect of cell proliferation and migration caused by the inhibition of AMIGO2. CONCLUSION: AMIGO2 is overexpressed in bladder cancer cells and tissues. Knockdown of AMIGO2 suppresses bladder cancer cell proliferation and migration. These processes might be regulated by PPAR-γ signaling pathway.

The mitochondrial fusion-associated protein MFN2 can be used as a novel prognostic molecule for clear cell renal cell carcinoma.

BACKGROUND: Mitofusin 2 (MFN2) plays an important role in many tumors, but how its role in renal clear cell carcinoma needs further research. METHODS: In this study, we analyzed the expression of MFN2 in renal clear cell carcinoma tissues and normal kidney tissues through the Cancer Genome Atlas (TCGA) database and our clinical samples.Enrichment analysis was performed to determine MFN2-related pathways and biological functions. The correlation of MFN2 expression with immune cells was analyzed.The correlation of the expression of methylation and the methylation sites of MFN2 were analyzed by UALCAN and TCGA databases. Univariate / multivariate COX risk regression and Kaplan-Meier methods were used to determine the prognostic value of MFN2.Nomograms were drawn to predict overall survival (OS) at 1,3, and 5 years. We investigated the role of MFN2 in renal cancer cells using CCK 8, clone formation, wound healing assay, and methylase qPCR experiments. RESULTS: MFN2 is poorly expressed in renal clear cell carcinoma compared to normal kidney tissue,and is significantly negatively associated with TNM stage, histological grade and pathological stage.MFN2 was directly associated with OS after multivariate Cox regression analysis.MFN2 shows a hypomethylation state and shows a positive correlation with multiple methylation sites.Signaling pathways through functional enrichment to B-cell receptors and oxidative stress-induced senescence.Moreover, the low expression of MFN2 was positively correlated with the degree of immune cell infiltration in a variety of immune cells.In vitro experiments showed that overexpression of MFN2 significantly inhibited the proliferation and migration of renal clear cells and promoted methylation. CONCLUSIONS: In conclusion, MFN2 can be used as a novel prognostic marker for renal clear cell carcinoma and requires further investigation of its role in tumor development.

Clinical application and efficacy analysis of partial cystectomy combined with intravesical chemotherapy in muscle-invasive bladder cancer.

OBJECTIVES: Comparing the long-term tumor control results of partial cystectomy(PC)and radical cystectomy(RC)in the treatment of muscle-invasive bladder cancer, and to explore the feasible method of bladder preservation therapy (BPT)in patients with MIBC. METHODS: We retrospectively analyzed the clinical data of 102 patients with muscle-invasive bladder cancer in our hospital between January 2012 and December 2018, of whom 32 cases in the partial cystectomy group and 70 cases in the radical cystectomy group. We performed a comparative analysis of patient general information, perioperative-related indicators and postoperative follow-up data, comparing OS, PFS, and DSS at 1, 2, 3, 4, and 5 years in both groups, and comparing tumour recurrence and metastasis in postoperative patients. RESULTS: All the 102 cases in this study were successfully completed. Partial cystectomy group and Radical cystectomy group median operating time (169.50(130.00 ~ 225.25) min and 420.00(343.75 ~ 483.75) min, p < 0.001), median intraoperative blood loss was (100(50 ~ 100)ml and 400(200 ~ 1000)ml, p < 0.001), median perioperative blood transfusion volume (0(0 ~ 0)ml and 600(150.00 ~ 906.25)ml, p < 0.001), median total hospital stay (18(14.25 ~ 20.00) and 24.5(20.00 ~ 34.25) days, p < 0.001), median preoperative preparation time (7(4.25 ~ 8.00) and 10(8.00 ~ 13.00) days, p < 0.001), median postoperative hospital stay (9(8.00 ~ 13.50) and 14(11.00 ~ 21.25) days, p < 0.001), the incidence of perioperative blood transfusion was (15.6% and 75.7%, p < 0.001), the incidence of surgical complications was(28.1%(9/32) and 50.0%(35/70), p = 0.033), average hospitalization cost ((26435.76 ± 9877.82) yuan and (58464.36 ± 19753.13) yuan, p < 0.001), the differences were statistically significant (p < 0.05). Perioperative mortality (0 vs. 2.9%(2/70), p = 1), and OS at 1, 2, 3, 4, and 5 years after surgery were (80.0%, 59.8%, 56.1%, 51.0%, 44.6% vs. 76.5%, 67.4%, 64.9%, 57.9%, 52.6%, p = 0.524), PFS (68.2%, 64.6%, 60.3%, 54.8%, 54.8% vs. 82.7%, 78.3%, 75.4%, 67.3%, 62.1%, p = 0.259). DSS (89.9%, 72.4%, 68.6%, 68.6%, 62.4% vs. 87.3%, 83.4%, 80.9%, 73.6%, 68.0%, p = 0.424), and the incidence of tumor recurrence or metastasis was (40.0%(12/30) vs. 25.4%(16/63), p = 0.151), the differences were not statistically significant (p > 0.05). CONCLUSION: In patients with limited solitary T2N0M0 and T3N0M0 muscle-invasive bladder cancer, partial cystectomy plus bladder instillations treatment can achieve comparable tumour control to radical cystectomy. However, patients in the PC group have significant advantages in terms of operative time, intraoperative bleeding, intraoperative and postoperative blood transfusion, preoperative preparation time, total hospital stay, postoperative recovery time, operative costs and operative complications. This option may be considered for such patients with a need for bladder preservation.

TAGLN2 Promotes the Proliferation, Migration, Invasion, and EMT of Clear Cell Renal Cell Carcinoma Through the PI3K/Akt Signaling Pathway.

The effect of Transgelin 2 (TAGLN2) on clear cell renal cell carcinoma (ccRCC) is unknown. This study explored the potential role and mechanism of ccRCC. The expression of TAGLN2 in Pan-cancers was analyzed using the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases. TCGA-KIRC database was used to analyze subsequent prognostic survival, pathway enrichment, and immune infiltration. Relevant experimental methods could explain the effect of TAGLN2 expression on tumor cell proliferation, migration, invasion, and apoptosis. Apoptosis, proliferation, Epithelial-to-Mesenchymal Transition (EMT), and PI3K/AKT signaling pathway-related protein expression were determined through western blotting. In the TCGA + GTEx database, mRNA-TAGLN2 expression was clearly increased in pan-cancer tissues, and the same result was found in ccRCC patients based on KIRC analysis results. In addition, TAGLN2 was associated with poor clinical stage, pathological grade, and survival prognosis. TAGLN2 is highly expressed in ccRCC tissues and in vitro TAGLN2 silencing of cells inhibits the proliferation, migration, invasion, and EMT of ccRCC cancer cells. Furthermore, TAGLN2-related differential genes enriched in the PI3K/AKT signaling pathway were negatively regulated after TAGLN2 silencing. Moreover, TAGLN2 may promote tumor immune escape and increase the risk of distant metastasis in immune infiltration-related analyses. TAGLN2 can be used as a single indicator to explain the survival probability of patients with ccRCC. In vitro TAGLN2 silencing inhibited the malignant properties of ccRCC by blocking the PI3K/AKT signaling pathway. In addition, TAGLN2 contributes to tumor immune escape and may be a potential therapeutic target for ccRCC.

Identification of stemness index-related long noncoding RNA SNHG12 in human bladder cancer based on WGCNA.

BACKGROUND: Cancer stem cells (CSCs) have an key role in the beginning, progression and treatment of bladder cancer. In the current study, our target was to identify CSCS-related genes in bladder cancer. METHODS: Bladder cancer (BLCA) transcriptome data were acquired from The Cancer Genome Atlas (TCGA) database. WGCNA was used to screen genes connected with the mRNA expression-based stemness index (mRNAsi).Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were used to analyze the biological function of mRNAsi-related genes. Univariate Cox regression and LASSO Cox regression algorithms were applied to build a risk score model. Additionally, a ceRNA regulatory netwok based on key mRNAsi-related genes was established via TargetScan, miRDB, miRTarBas and miRcode database,and lncRNA SNHG12 was selected for further in vitro and invivo functional assays. RESULTS: Between BLCA and normal samples were identified 1560 differentially expressed genes (DEGs).845 DEGs were most significantly associated with mRNAsi according to WGCNA analysis, which were mainly enriched in GO terms and KEGG pathways related to cell proliferation. Univariate Cox regression and LASSO Cox regression algorithms screened 25 mRNAsi-related genes to construct the risk score model with the significant ability to estimate prognosis of BLCA patients. A ceRNA network, including 8 lncRNA, 11 miRNA and 9 mRNAsi-related mRNA, was constructed.We found that lncRNAs ADAMTS9-AS1 and SNHG12 were observably related to the survival of BLCA patients. To verify this finding, we selected SNHG12 for further study. RT-PCR experiments revealed that SNHG12 was high expression in both bladder cancer tissues and cells.SNHG12 promoted proliferation, invasion, migration, apoptosis and stemness of bladder cancer cells in vitro and tumour proliferation in vivo. CONCLUSION: Our study identified 25 biomarkers associated with stemness indices in BLCA and established a ceRNA network based on key mRNAsi-related genes.SNHG12 promoted BLCA proliferation, invasion, migration, apoptosis and stemness in vitro. It was also showed that SNHG12 promoted tumour growth.

The dynamic N(1)-methyladenosine methylome in eukaryotic messenger RNA.

Gene expression can be regulated post-transcriptionally through dynamic and reversible RNA modifications. A recent noteworthy example is N(6)-methyladenosine (m(6)A), which affects messenger RNA (mRNA) localization, stability, translation and splicing. Here we report on a new mRNA modification, N(1)-methyladenosine (m(1)A), that occurs on thousands of different gene transcripts in eukaryotic cells, from yeast to mammals, at an estimated average transcript stoichiometry of 20% in humans. Employing newly developed sequencing approaches, we show that m(1)A is enriched around the start codon upstream of the first splice site: it preferentially decorates more structured regions around canonical and alternative translation initiation sites, is dynamic in response to physiological conditions, and correlates positively with protein production. These unique features are highly conserved in mouse and human cells, strongly indicating a functional role for m(1)A in promoting translation of methylated mRNA.

Photo-Facilitated Detection and Sequencing of 5-Formylcytidine RNA.

5-Formylcytidine (f5 C) is one of the epigenetic nucleotides in tRNA. Despite the evident importance of f5 C in gene expression regulation, little is known about its exact amount and position. To capture this information, we developed a modification-specific functionalization with a semi-stabilized ylide. The chemical labelling exhibited a high selectivity towards f5 C and allowed distinction from similar 5-formyluridine. We realized a detection strategy based on the fluorescence signal of the cyclization product 4,5-pyridin-2-amine-cytidine paC, which exhibited a high quantum yield. The results clearly identified f5 C with a limit of detection at 0.58 nM. This method altered the hydrogen bonding activities of f5 C and modulated its reverse transcription signature in its sequencing profile. We showed that f5 C can be detected from tRNA segments with a single-base resolution. Taken together, this approach is a sensitive, antibody-free, and applicable detection and sequencing method for f5 C-containing RNA.

Nm-seq maps 2'-O-methylation sites in human mRNA with base precision.

The ribose of RNA nucleotides can be 2'-O-methylated (Nm). Despite advances in high-throughput detection, the inert chemical nature of Nm still limits sensitivity and precludes mapping in mRNA. We leveraged the differential reactivity of 2'-O-methylated and 2'-hydroxylated nucleosides to periodate oxidation to develop Nm-seq, a sensitive method for transcriptome-wide mapping of Nm with base precision. Nm-seq uncovered thousands of Nm sites in human mRNA with features suggesting functional roles.

RUNX2 interacts with BRG1 to target CD44 for promoting invasion and migration of colorectal cancer cells.

BACKGROUND: Cancer stem cells (CSCs) play an important role in tumor invasion and metastasis. CD44 is the most commonly used marker of CSCs, with the potential to act as a determinant against the invasion and migration of CSCs and as the key factor in epithelial-mesenchymal transition (EMT)-like changes that occur in colorectal cancer (CRC). Runt-related transcription factor-2 (RUNX2) is a mesenchymal stem marker for cancer that is involved in stem cell biology and tumorigenesis. However, whether RUNX2 is involved in CSC and in inducing EMT-like changes in CRC remains uncertain, warranting further investigation. METHODS: We evaluated the role of RUNX2 in the invasion and migration of CRC cells as a promoter of CD44-induced stem cell- and EMT-like modifications. For this purpose, western blotting was employed to analyze the expression of differential proteins in CRC cells. We conducted sphere formation, wound healing, and transwell assays to investigate the biological functions of RUNX2 in CRC cells. Cellular immunofluorescence and coimmunoprecipitation (co-IP) assays were performed to study the relationship between RUNX2 and BRG1. Real-time quantitative PCR (RT-qPCR) and immunohistochemistry (IHC) were performed to analyze the expressions of RUNX2, BRG1, and CD44 in the CRC tissues. RESULTS: We found that RUNX2 could markedly induce the CRC cell sphere-forming ability and EMT. Interestingly, the RUNX2-mediated EMT in CRC cell may be associated with the activation of CD44. Furthermore, RUNX2 was found to interact with BRG1 to promote the recruitment of RUNX2 to the CD44 promoter. CONCLUSIONS: Our cumulative findings suggest that RUNX2 and BRG1 can form a compact complex to regulate the transcription and expression of CD44, which has possible involvement in the invasion and migration of CRC cells.

Systemic In Silico Screening in Drug Discovery for Coronavirus Disease (COVID-19) with an Online Interactive Web Server.

The emergence of the new coronavirus (nCoV-19) has impacted human health on a global scale, while the interaction between the virus and the host is the foundation of the disease. The viral genome codes a cluster of proteins, each with a unique function in the event of host invasion or viral development. Under the current adverse situation, we employ virtual screening tools in searching for drugs and natural products which have been already deposited in DrugBank in an attempt to accelerate the drug discovery process. This study provides an initial evaluation of current drug candidates from various reports using our systemic in silico drug screening based on structures of viral proteins and human ACE2 receptor. Additionally, we have built an interactive online platform (https://shennongproject.ai/) for browsing these results with the visual display of a small molecule docked on its potential target protein, without installing any specialized structural software. With continuous maintenance and incorporation of data from laboratory work, it may serve not only as the assessment tool for the new drug discovery but also an educational web site for the public.

N6-methyladenosine-dependent regulation of messenger RNA stability.

N(6)-methyladenosine (m(6)A) is the most prevalent internal (non-cap) modification present in the messenger RNA of all higher eukaryotes. Although essential to cell viability and development, the exact role of m(6)A modification remains to be determined. The recent discovery of two m(6)A demethylases in mammalian cells highlighted the importance of m(6)A in basic biological functions and disease. Here we show that m(6)A is selectively recognized by the human YTH domain family 2 (YTHDF2) 'reader' protein to regulate mRNA degradation. We identified over 3,000 cellular RNA targets of YTHDF2, most of which are mRNAs, but which also include non-coding RNAs, with a conserved core motif of G(m(6)A)C. We further establish the role of YTHDF2 in RNA metabolism, showing that binding of YTHDF2 results in the localization of bound mRNA from the translatable pool to mRNA decay sites, such as processing bodies. The carboxy-terminal domain of YTHDF2 selectively binds to m(6)A-containing mRNA, whereas the amino-terminal domain is responsible for the localization of the YTHDF2-mRNA complex to cellular RNA decay sites. Our results indicate that the dynamic m(6)A modification is recognized by selectively binding proteins to affect the translation status and lifetime of mRNA.