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Sleep deprivation (SD) impairs learning and memory. Investigating the role of epigenetic modifications, such as 5-methylcytosine (m 5 C), in SD is crucial. This study established an SD mouse model and assessed the mRNA levels of m 5 C-related genes in brain tissue to identify potential candidates. Results indicated a significant elevation of NSUN2 in the SD group. Behavioral assessments using the Morris water maze test revealed cognitive impairments. Notably, inhibiting NSUN2 markedly alleviated these cognitive deficits and reduced autophagy in SD mice. Mechanistically, NSUN2 inhibition led to a pronounced decrease in PTEN levels, and the m 5 C modification of PTEN, which was increased by SD, was significantly reduced following NSUN2 knockdown. It was found that NSUN2 stabilizes PTEN mRNA through methylation. In the SD group, PTEN protein levels were elevated, and this increase was counteracted by NSUN2 inhibition. Collectively, the upregulation of PTEN may diminish the beneficial effects of NSUN2 inhibition on cognitive function and autophagy in SD mice. This study suggests that targeting NSUN2 and PTEN could be a novel therapeutic approach to ameliorate cognitive impairments and autophagy associated with SD, offering a promising strategy for the clinical management of SD-related cognitive deficits., Competing Interests: Declarations. Competing interests: The authors declare no competing interests. Ethical Approval: The study was approved by the Ethics Committee of Puren Hospital Affliated to Wuhan University of Science and Technology. All experiments were performed in accordance with the ARRIVE guidelines., (© 2025. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

R-loops are critical structures that play pivotal roles in regulating genomic stability and modulating gene expression. This study investigates the interactions between the 5-methylcytosine (m 5 C) methyltransferase NOP2/Sun RNA methyltransferase 2 (NSUN2) and R-loops in the transcriptional dynamics and damage repair process of bladder cancer (BCa) cells. We observed markedly elevated levels of R-loops in BCa cells relative to normal urothelial cells. NSUN2 was identified as a regulator of R-loops, acting to bind and stabilize their structure through a process dependent on its m 5 C catalytic activity. The histone methyltransferase Enhancer of Zeste Homolog 2 (EZH2) was found to interact with NSUN2. Our results demonstrated that NSUN2 facilitates the epigenetic silencing of the tumor suppressor gene PR Domain Zinc Finger Protein 11 (PRDM11) by recruiting EZH2, thereby advancing the progression of BCa. Furthermore, NSUN2 knockdown sensitizes tumors to cisplatin, resulting in reduced tumor growth and increased DNA damage levels, which was associated with reduced recruitment of MRE11 to damage sites, thereby impairing homologous recombination repair. These findings enhance our understanding of BCa pathogenesis and identify new potential targets for therapeutic intervention., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Glioma, particularly glioblastoma, is the most common and aggressive primary brain tumor, with poor prognosis due to its metabolic heterogeneity. NSUN2, an m5C RNA methyltransferase and direct glucose sensor, has been implicated in various malignancies, but its role in glioma remains unclear., Methods: Bioinformatic analysis was performed on multiple public databases and our glioma dataset from West China Hospital (WCH). In vitro experiments were conducted to assess the effects of NSUN2 knockdown on glioma cell proliferation, migration, and chemotherapeutic sensitivity. Transcriptomic analysis was employed to obtain mechanistic insights., Results: NSUN2 expression was significantly upregulated in gliomas and correlated with higher tumor grade and poor prognosis. NSUN2 knockdown reduced glioma cell proliferation, migration, and increased sensitivity to temozolomide. Transcriptomic analysis revealed that NSUN2 knockdown downregulated key genes involved in glioma progression. Mechanistically, NSUN2 positively regulates the activity of mTORC1 signaling, as indicated by phosphorylated S6 ribosomal protein and 4EBP1. Moreover, NSUN2 overexpression reciprocally increased tumor volume compared with controls, indicating NSUN2 promoting glioma cell proliferation in vivo., Conclusions: Our findings highlight NSUN2 as a critical regulator of glioma malignancy. Targeting NSUN2 disrupts key pathways in glioma progression, suggesting it as a promising therapeutic target. Our work underscores the potential of NSUN2 inhibition to enhance treatment efficacy and improve patient outcomes in glioma., (© 2024 John Wiley & Sons Ltd.)

Background/objectives: Head and neck squamous cell carcinoma (HNSCC) is a prevalent and aggressive cancer with high rates of metastasis and poor prognosis. Recent research highlights the role of 5-methylcytosine (m 5 C) in cancer progression. NSUN2, an m 5 C methyltransferase, has been implicated in various cancers, but its role in HNSCC remains elusive., Methods: NSUN2 expression and its impact on HNSCC were analyzed by using clinical samples and bioinformatic analysis. m 5 C-Bis-Seq was used to assess changes in mRNA m 5 C modification and identify downstream targets. Both in vitro and vivo studies were performed to evaluate the impact of NSUN2 manipulation on tumor growth and metastasis., Results: Results indicated that NSUN2 was significantly upregulated in HNSCC tissues compared to normal tissues and was associated with poor prognosis. NSUN2 knockdown led to decreased cell proliferation, migration, and invasion in vitro and reduced tumorigenicity and lymph node metastasis in vivo. m 5 C-Bis-Seq revealed altered m 5 C-modification patterns upon NSUN2 knockdown, with LAMC2 identified as a key downstream target., Conclusions: NSUN2-mediated m 5 C-modification enhanced LAMC2 stability, promoting epithelial-mesenchymal transition (EMT) signaling pathways. These findings demonstrate that NSUN2 promotes the initiation and progression of HNSCC by stabilizing the LAMC2 transcript through m 5 C-dependent mechanisms, offering a promising epitranscriptomic-targeted therapeutic approach for HNSCC.

Cancer remains a leading cause of morbidity and mortality worldwide, necessitating the ongoing investigation of molecular targets for improved diagnosis, prognosis, and therapy. Among these targets, RNA modifications, particularly N5-methylcytosine (m5C) in RNA, have emerged as critical regulators of gene expression and cellular functions. NOP2/Sun RNA methyltransferase family member 2 (NSUN2) is a key enzyme in m5C modification, significantly influencing various biological processes and tumorigenesis. NSUN2 methylates multiple RNA species, including transfer RNAs (tRNAs), messenger RNAs (mRNAs), and non-coding RNAs, impacting RNA stability, translation efficiency, and cellular stress responses. These modifications, in turn, affect cell proliferation, differentiation, and survival. In cancer, NSUN2 is frequently upregulated, associated with aggressive tumor phenotypes, poor prognosis, and therapy resistance. Its role in oncogenic signaling pathways further underscores its importance in cancer biology. This review offers a comprehensive overview of NSUN2's role in cancer, focusing on its involvement in RNA methylation and its implications for tumor initiation and progression. Additionally, we explore the potential of NSUN2 as a biomarker for cancer diagnosis and prognosis, and its promise as a therapeutic target., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

Lactate-mediated lactylation on target proteins is recently identified as the novel posttranslational modification with profound biological functions. RNA 5-methylcytosine (m 5 C) modification possesses dynamic and reversible nature, suggesting that activity of its methyltransferase NSUN2 is actively regulated. However, how NSUN2 activity is response to acidic condition in tumor microenvironment and then regulates cancer cell survival remain to be clarified. Here, we demonstrate that NSUN2 activity is enhanced by lactate-mediated lactylation at lysine 508, which then targets glutamate-cysteine ligase catalytic subunit (GCLC) mRNA to facilitates GCLC m 5 C formation and mRNA stabilization. The activated GCLC induces higher level of intracellular GSH accompanied by decreased lipid peroxidation and resistant phenotype to ferroptosis induction by doxorubicin (Dox) in gastric cancer cells. Specifically, the effect of NSUN2 lactylation-GCLC-GSH pathway is nearly lost when NSUN2 K508R or GCLC C-A mutant (five cytosine sites) was introduced into the cancer cells. We further identify the catalytic subunit N-α-acetyltransferase 10 (NAA10) as the lactytransferase of NSUN2, and lactate treatment substantially enhances their association and consequent NSUN2 activation. Taken together, our findings convincingly elucidate the signaling axis of NAA10-NSUN2-GCLC that potently antagonizes the ferroptosis under acidic condition, and therefore, targeting NSUN2 lactylation might be an effective strategy in improving the prognosis of cancer patients., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Dysregulation of cholesterol metabolism is an important feature of cancer development. There are limited reports on the involvement of lncRNAs in hepatocellular carcinoma (HCC) progression via the cholesterol metabolism pathway. The present study explored the effect of LINC00618 on HCC growth and metastasis, and elucidated the underlying mechanisms involved in cholesterol metabolism. Here, we found that LINC00618 expression was upregulated in cancerous tissues from 30 patients with HCC compared to that in adjacent normal tissues. High expression of LINC00618 was detected in metastatic HCC tissues. LINC00618 is predominantly localized in the nucleus and overexpression of LINC00618 facilitated HCC cell proliferation, migration and EMT progression by promoting cholesterol biosynthesis. Mechanistically, the 1-101nt region of LINC00618 bound to NSUN2. LINC00618 inhibited ubiquitin-proteasome pathway-induced NSUN2 degradation. NSUN2 stabilized by LINC00618 increased m5C modification of SREBP2 and promoted SREBP2 mRNA stability in a YBX1-dependent manner, thereby promoting cholesterol biosynthesis in HCC cells. Moreover, mouse HCC xenograft and lung metastasis models were established by subcutaneous and tail vein injections of MHCC97 cells transfected with or without sh-LINC00618. Silencing LINC00618 impeded HCC growth and metastasis. In conclusion, LINC00618 promoted HCC growth and metastasis by elevating cholesterol synthesis by stabilizing NSUN2 to enhance SREBP2 mRNA stability in an m5C-dependent manner., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: N5-methylcytosine (m5C) methylation is involved in various disease progression; however, its role in diabetic nephropathy (DN) has not been studied. The aim of this study was to investigate the role of NSUN2 in DN and the underlying mechanism., Methods: Streptozotocin-induced experimental mouse model was generated to analyze the role of NSUN2 in vivo, and high glucose (HG)-treated Raw264.7 cells were used to assess the effect of NSUN2 on macrophage infiltration in vitro. The regulation of NSUN2 on SOCS1 m5C methylation was evaluated using m5C methylated RNA immunoprecipitation, luciferase reporter analysis, and RNA stability determination assay., Results: The results indicated that NSUN2 was highly expressed in the blood and kidney of DN mice. Knockdown of NSUN2 alleviated kidney damage, reduced blood glucose and urine albumin, and suppressed macrophage infiltration in DN mice. Moreover, NSUN2 interacted with SOCS1, and silenced NSUN2 inhibited m5C levels of SOCS1 to reduce SOCS1 mRNA stability. Additionally, interference with NSUN2 suppressed macrophage migration, invasion, and infiltration by positively regulating SOCS1 expression under HG conditions., Conclusion: In conclusion, silencing of NSUN2 inhibits macrophage infiltration by reducing m5C modification of SOCS1, and thereby attenuates renal injury. The findings suggest a novel regulatory mechanism between NSUN2-mediated m5C modification and DN., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

This study delves into the molecular intricacies of hypopharyngeal squamous cell carcinoma (HSCC), specifically focusing on the pivotal role played by ETS translocation variant 4 (ETV4) in aerobic glycolysis. The objective is to uncover new targets for early diagnosis and treatment of HSCC. ETV4 expression in HSCC tissues was rigorously examined, revealing its association with patient survival. Through comprehensive experimentation, we demonstrated that ETV4 activation promotes HSCC cell proliferation and invasion while inhibiting apoptosis. Furthermore, in vivo experiments confirmed the tumor-promoting effect of ETV4 activation. The study elucidated the binding of ETV4 to the NSUN2 promoter and its influence on PKM2 expression, thereby regulating glycolysis and cellular functions in HSCC., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The activated form of vitamin D 3 [1,25-dihydroxyvitamin D 3 ; 1,25(OH) 2 D 3 ] is important for various physiological processes, such as bone mineralization and calcium metabolism, and plays an anticancer role in numerous cancers as well. Its role in melanoma cells has yet to be proven. NOP2/Sun RNA methyltransferase 2 (NSUN2) is a typical RNA methyltransferase and is highly expressed in a variety of cancer cells. However, the molecular mechanisms underlying the role of 1,25(OH) 2 D 3 and NSUN2 in melanoma cells remain largely unknown. The current study showed that 1,25(OH) 2 D 3 could significantly and specifically inhibit the proliferation and migration of melanoma B16 cells. 1,25(OH) 2 D 3 enhances vitamin D receptor expression while simultaneously reducing NSUN2 expression in melanoma cells. Subsequently, knockdown of NSUN2 suppressed B16 cell proliferation and migration. RNA-Seq results illuminated that DNA replication, cell proliferation and cell cycle pathways were enriched, and genes promoting these pathways were reduced after knocking down Nsun2. Dual-luciferase reporter assays showed that 1,25(OH) 2 D 3 downregulated reporter gene expression was controlled by the Nsun2 promoter. The results suggest that 1,25(OH) 2 D 3 binds to the vitamin D response element located upstream of the Nsun2 promoter to downregulate Nsun2 transcription activity and then affects the gene expression pattern related to cell proliferation and the cell cycle, thereby restraining B16 cell proliferation and migration., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Hexavalent chromium [Cr(VI)], one common environmental contaminant, has long been recognized as a carcinogen associated with lung cancer, but roles and mechanisms of Cr(VI)-induced epigenetic dysregulations in carcinogenesis remain to be investigated. In this study, we identified that RNA m5C methyltransferase NSUN2 was significantly upregulated in Cr(VI)-transformed cells and lung tissues of Cr(VI)-exposed mice. Inhibition of NSUN2 reduced cell proliferation, migration, colony formation and tube formation abilities. We found NSUN2-mediated m5C modification induced metabolic reprogramming and cell cycle by promoting the mRNA stabilities of ME1, GLUT3 and CDK2. In addition, knockdown of NSUN2 attenuated tumorigenesis and angiogenesis in vivo. RNA m5C reader ALYREF was identified to be involved in NSUN2-mediated m5C modification in Cr (VI)-induced carcinogenesis. Further study showed that EP300 induced NSUN2 upregulation through transcriptional activation by inducing histone modification at H3K27ac site for regulating Cr(VI) carcinogenesis. Our findings demonstrated novel role and mechanism of NSUN2 and epigenetic changes by increasing the RNA m5C modification that are important for Cr (VI)-induced carcinogenesis through NSUN2/ALYREF pathway. NSUN2, ALYREF, ME1, GLUT3 or/and CDK2 may be used as potential new biomarkers or/and therapeutic target(s) in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Tendon-derived stem cells (TDSCs) play a critical role in tendon repair. N5-methylcytosine (m5C) is a key regulator of cellular processes such as differentiation. This study aimed to investigate the impact of m5C on TDSC differentiation and the underlying mechanism., Methods: TDSCs were isolated from rats and identified, and a tendon injury rat model was generated. Tenogenic differentiation in vitro was evaluated using Sirius red staining and quantitative real-time polymerase chain reaction, while that in vivo was assessed using immunohistochemistry and hematoxylin‒eosin staining. m5C methylation was analyzed using methylated RNA immunoprecipitation, dual-luciferase reporter assay, and RNA stability assay., Results: The results showed that m5C levels and NSUN2 expression were increased in TDSCs after tenogenic differentiation. Knockdown of NSUN2 inhibited m5C methylation of KLF2 and decreased its stability, which was recognized by YBX1. Moreover, interfering with KLF2 suppressed tenogenic differentiation of TDSCs, which could be abrogated by KLF2 overexpression. Additionally, TDSCs after NSUN2 overexpression contributed to ameliorating tendon injury in vivo . In conclusion, NSUN2 promotes tenogenic differentiation of TDSCs via m5C methylation of KLF2 and accelerates tendon repair., Conclusions: The findings suggest that overexpression of NSUN2 can stimulate the differentiation ability of TDSCs, which can be used in the treatment of tendinopathy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

Increasing evidences suggest that the methyltransferase NSUN2 catalyzes 5-methylcytosine (m5C) modifications on viral RNAs, which are essential for the replication of various viruses. Despite the function of m5C deposition is well characterized, other potential roles of NSUN2 in regulating viral replication remain largely unknown. In this study, the m5C modified residues catalyzed by NSUN2 on enterovirus 71 (EV71) RNAs were mapped. NSUN2, along with m5C modifications, played multiple roles during the EV71 life cycle. Functional m5C modified nucleotides increased the translational efficiency and stability of EV71 RNAs. Additionally, NSUN2 was found to target the viral protein VP1 for binding and promote its stability by inhibiting the ubiquitination. Furthermore, both viral replication and pathogenicity in mice were largely attenuated when functional m5C residues were mutated. Taken together, this study characterizes distinct pathways mediated by NSUN2 in regulating EV71 replication, and highlights the importance of its catalyzed m5C modifications on EV71 RNAs for the viral replication and pathogenicity., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2024 The Authors. Publishing services by Elsevier B.V. All rights reserved.)

The RNA modification, 5-methylcytosine (m 5 C), has recently gained prominence as a pivotal post-transcriptional regulator of gene expression, intricately intertwined with various tumorigenic processes. However, the exact mechanisms governing m 5 C modifications during the onset and progression of colorectal cancer (CRC) remain unclear. Here, it is determined that the m 5 C methyltransferase NSUN2 exhibits significantly elevated expression and exerts an oncogenic function in CRC. Mechanistically, NSUN2 and YBX1 are identified as the "writer" and "reader" of ENO1, culminating in the reprogramming of the glucose metabolism and increased production of lactic acid in an m 5 C-dependent manner. The accumulation of lactic acid derived from CRC cells, in turn, activates the transcription of NSUN2 through histone H3K18 lactylation (H3K18la), and induces the lactylation of NSUN2 at the Lys356 residue (K356), which is crucial for capturing target RNAs. Together, these findings reveal an intriguing positive feedback loop involving the NSUN2/YBX1/m 5 C-ENO1 signaling axis, thereby bridging the connection between metabolic reprogramming and epigenetic remodeling, which may shed light on the therapeutic potential of combining an NSUN2 inhibitor with immunotherapy for CRC., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

In recent years, in the development of emerging immunotherapy, B7-H3 is also termed as CD276 and has become a novel chimeric antigen receptor (CAR)-T target against glioma and other tumours, and aroused extensive attention. However, B7-H3 has three isoforms (2, 3 and 4Ig) with the controversial expression and elusive function in tumour especially glioma. The current study mainly focuses on the regulatory factors and related mechanisms of generation of different B7-H3 isoforms. First, we have determined that 2Ig is dominant in glioma with high malignancy, and 4Ig is widely expressed, whereas 3Ig shows negative expression in all glioma. Next, we have further found that RNA binding protein annexin A2 (ANXA2) is essential for B7-H3 isoform maintenance, but fail to determine the choice of 4Ig or 2Ig. RNA methyltransferase NOP2/Sun RNA methyltransferase 2 (NSUN2) and 5-methylcytosine reader Y-box binding protein 1 (YBX1) facilitate the production of 2Ig. Our findings have uncovered a series of factors (ANXA2/NSUN2/YBX1) that can determine the alternative generation of different isoforms of B7-H3 in glioma. Our result aims to help peers gain a clearer understanding of the expression and regulatory mechanisms of B7H3 in tumour patients, and to provide better strategies for designing B7H3 as a target in immunotherapy., (© 2024 The Author(s). Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

The significance of NSUN2 in carcinogenesis is gradually being recognized, yet a comprehensive analysis across pan-cancer remains a pivotal void in existing research. In our investigation, we capitalized on the UCSC Xena platform to evaluate NSUN2 expression levels and their prognostic implications across a range of cancer types. Furthermore, we employed the cBioPortal database to delve into the genomic variations of NSUN2 within human cancers. Our study encompassed the use of molecular docking, genomic tumor profiling, and an assessment of the gene's responsiveness to pharmacological treatments. Additionally, we utilized algorithmic techniques to measure the relationship between NSUN2 expression and key clinical biomarkers, such as microsatellite instability (MSI), tumor mutational burden (TMB), and immune cell infiltration. Our results have established a notable association between NSUN2 and endometrial cancer (UCEC), thereby confirming its clinical significance through an analysis of tumoral expression patterns, mutational spectra, methylation profiles, and drug sensitivity. Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) were crucial tools in elucidating the biological roles of NSUN2 in endometrial cancer. Consistently, elevated NSUN2 expression was associated with unfavorable clinical outcomes and was primarily observed in the context of genetic amplifications. Across 22 distinct tumor types, our analysis revealed a notable correlation between NSUN2 expression and various metrics related to immune cell infiltration, tumor stroma, and immune scores. Notably, higher levels of NSUN2 expression have been linked to a reduced response to certain chemotherapeutic agents, including PHA-793887. In UCEC, a positive correlation between NSUN2 methylation and gene expression hints at a potential epigenetic regulatory mechanism underlying cancer progression. Our study highlights the potential of NSUN2 as a key oncogene and its promising role as a therapeutic target as well as a prognostic biomarker for endometrial cancer. This underscores its potential importance in predicting responses to immunotherapy., (© 2024. The Author(s), under exclusive licence to Society for Reproductive Investigation.)

Epitranscriptomic RNA modifications have emerged as important regulators of the fate and function of viral RNAs. One prominent modification, the cytidine methylation 5-methylcytidine (m 5 C), is found on the RNA of HIV-1, where m 5 C enhances the translation of HIV-1 RNA. However, whether m 5 C functionally enhances the RNA of other pathogenic viruses remains elusive. Here, we surveyed a panel of commonly found RNA modifications on the RNA of hepatitis B virus (HBV) and found that HBV RNA is enriched with m 5 C as well as ten other modifications, at stoichiometries much higher than host messenger RNA (mRNA). Intriguingly, m 5 C is mostly found on the epsilon hairpin, an RNA element required for viral RNA encapsidation and reverse transcription, with these m 5 C mainly deposited by the cellular methyltransferase NSUN2. Loss of m 5 C from HBV RNA due to NSUN2 depletion resulted in a partial decrease in viral core protein (HBc) production, accompanied by a near-complete loss of the reverse transcribed viral DNA. Similarly, mutations introduced to remove the methylated cytidines resulted in a loss of HBc production and reverse transcription. Furthermore, pharmacological disruption of m 5 C deposition led to a significant decrease in HBV replication. Thus, our data indicate m 5 C methylations as a critical mediator of the epsilon elements' function in HBV virion production and reverse transcription, suggesting the therapeutic potential of targeting the m 5 C methyltransfer process on HBV epsilon as an antiviral strategy., Competing Interests: Competing interests statement:The authors declare no competing interest.

Background: RNA m 5 C methylation has been extensively implicated in the occurrence and development of tumors. As the main methyltransferase, NSUN2 plays a crucial regulatory role across diverse tumor types. However, the precise impact of NSUN2-mediated m 5 C modification on breast cancer (BC) remains unclear. Our study aims to elucidate the molecular mechanism underlying how NSUN2 regulates the target gene HGH1 (also known as FAM203) through m 5 C modification, thereby promoting BC progression. Additionally, this study targets at preliminarily clarifying the biological roles of NSUN2 and HGH1 in BC., Methods: Tumor and adjacent tissues from 5 BC patients were collected, and the m 5 C modification target HGH1 in BC was screened through RNA sequencing (RNA-seq) and single-base resolution m 5 C methylation sequencing (RNA-BisSeq). Methylation RNA immunoprecipitation-qPCR (MeRIP-qPCR) and RNA-binding protein immunoprecipitation-qPCR (RIP-qPCR) confirmed that the methylation molecules NSUN2 and YBX1 specifically recognized and bound to HGH1 through m 5 C modification. In addition, proteomics, co-immunoprecipitation (co-IP), and Ribosome sequencing (Ribo-Seq) were used to explore the biological role of HGH1 in BC., Results: As the main m 5 C methylation molecule, NSUN2 is abnormally overexpressed in BC and increases the overall level of RNA m 5 C. Knocking down NSUN2 can inhibit BC progression in vitro or in vivo. Combined RNA-seq and RNA-BisSeq analysis identified HGH1 as a potential target of abnormal m 5 C modifications. We clarified the mechanism by which NSUN2 regulates HGH1 expression through m 5 C modification, a process that involves interactions with the YBX1 protein, which collectively impacts mRNA stability and protein synthesis. Furthermore, this study is the first to reveal the binding interaction between HGH1 and the translation elongation factor EEF2, providing a comprehensive understanding of its ability to regulate transcript translation efficiency and protein synthesis in BC cells., Conclusions: This study preliminarily clarifies the regulatory role of the NSUN2-YBX1-m 5 C-HGH1 axis from post-transcriptional modification to protein translation, revealing the key role of abnormal RNA m 5 C modification in BC and suggesting that HGH1 may be a new epigenetic biomarker and potential therapeutic target for BC., (© 2024. The Author(s).)

Background: Diabetic retinopathy (DR) is the leading cause of blinding eye disease among working adults and is primarily attributed to the excessive proliferation of microvessels, which leads to vitreous hemorrhage and retinal traction, thereby significantly impairing patient vision. NSUN2-mediated RNA m 5 C methylation is implicated in various diseases, and in this investigation, we focused on elucidating the impact of NSUN2 on the regulation of the expression of the downstream gene MUC1, specifically through RNA m 5 C methylation, on the progression of DR., Method: Utilizing Microarray analysis, we examined patient vitreous fluid to pinpoint potential therapeutic targets for DR. Differential expression of NSUN2 was validated through qRT-PCR, Western blot, and immunofluorescence in human tissue, animal tissue, and cell model of DR. The relationship between NSUN2 and DR was explored in vitro and in vivo through gene knockdown and overexpression. Various techniques, such as MeRIP-qPCR and dot blot, were applied to reveal the downstream targets and mechanism of action of NSUN2., Results: The levels of both NSUN2 and RNA m 5 C methylation were significantly elevated in the DR model. Knockdown of NSUN2 mitigated DR lesion formation both in vitro and in vivo. Mechanistically, NSUN2 promoted MUC1 expression by binding to the RNA m 5 C reader ALYREF. Knockdown of ALYREF resulted in DR lesion alterations similar to those observed with NSUN2 knockdown. Moreover, MUC1 overexpression successfully reversed a series of DR alterations induced by NSUN2 silencing., Conclusions: NSUN2 regulates the expression of MUC1 through ALYREF-mediated RNA m 5 C methylation, thereby regulating the progression of DR and providing a new option for the treatment of DR in the future., (© 2024. The Author(s).)

Breast cancer (BC) is the most prevalent malignant tumor in women worldwide with high morbidity and mortality. NSUN2, a crucial RNA methyltransferase, plays a pivotal role in regulating the proliferation and metastasis of tumor cells. Our study demonstrated that NSUN2 is upregulated in BC tissues and cell lines, and its high expression is associated with a poor prognosis in BC patients. Knockout of NSUN2 exerted inhibitory effects on the proliferation and migration of BC cells in vitro and in vivo. Mechanistic investigations revealed that the RNA-binding protein ELAVL1 can bind to NSUN2 mRNA and increase its stability. Additionally, we identified HOST2, a long non-coding RNA, as a key player in blocking the ubiquitin-dependent proteasomal degradation of ELAVL1, thereby influencing the stability of NSUN2 mRNA. In conclusion, this study revealed for the first time that HOST2 maintains NSUN2 mRNA stability by blocking ubiquitin-dependent degradation of ELAVL1, which in turn affects BC progression. HOST2/ELAVL1/NSUN2 oncogenic cascade has the potential to be a novel therapeutic target for BC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

It is well known that 5-methylcytosine (m 5 C) is involved in variety of crucial biological processes in cancers. However, its biological roles in lung adenocarcinoma (LAUD) remain to be determined. The LUAD samples were used to assess the clinical value of NOP2/Sun RNA Methyltransferase 2 (NSUN2). Dot blot was used to determine global m 5 C levels. ChIP and dual-luciferase assays were performed to investigate the MYC-associated zinc finger protein (MAZ)-binding sites in NSUN2 promoter. RNA-seq was used to explore the downstream molecular mechanisms of NSUN2. Dual luciferase reporter assay, m 5 C-RIP-qPCR, and mRNA stability assay were conducted to explore the effect of NSUN2-depletion on target genes. Cell viability, transwell, and xenograft mouse model were designed to demonstrate the characteristic of NSUN2 in promoting LUAD progression. The m 5 C methyltransferase NSUN2 was highly expressed and caused elevated m 5 C methylation in LUAD samples. Mechanistically, MAZ positively regulated the transcription of NSUN2 and was related to poor survival of LUAD patients. Silencing NSUN2 decreased the global m 5 C levels, suppressed proliferation, migration and invasion, and inhibited activation of PI3K-AKT signaling in A549 and SPAC-1 cells. Phosphoinositide-3-Kinase Regulatory Subunit 2 (PIK3R2) was upregulated by NSUN2-mediated m 5 C methylation by enhancing its mRNA stabilization and activated the phosphorylation of the PI3K-AKT signaling. The present study explored the underlying mechanism and biological function of NSUN2-meditated m 5 C RNA methylation in LUAD. NSUN2 was discovered to facilitate the malignancy progression of LUAD through regulating m 5 C modifications to stabilize PIK3R2 activating the PI3K-AKT signaling, suggesting that NSUN2 could be a novel biomarker and promising therapeutic target for LUAD patients., (© 2024 Wiley Periodicals LLC.)

Background: Doxorubicin (Dox) is associated with various liver injuries, limiting its clinical utility. This study investigates whether NSUN2 participates in Dox-induced liver injury and the associated molecular mechanism., Methods: In vivo and in vitro liver cell injury models were constructed based on Dox therapy. The protein levels of NSUN2 and oxidative stress indicators Nrf2, HO-1, and NQO1 were evaluated by Western blot. The RNA binding potential was detected by RNA methylation immunoprecipitation (RIP). Additionally, the effect of NSUN2 on Nrf2 mRNA synthesis and localization was evaluated using an RNA fluorescence probe., Results: NSUN2 was downregulated, and liver tissue suffered significant pathological damage in the Dox group. The levels of ALT and AST significantly increased. NSUN2 interference exacerbated Dox-induced liver cell damage, which was reversed by NSUN2 overexpression. RIP demonstrated that NSUN2 recognized and bound to Nrf2 mRNA. Western blot analysis showed the protein level of Nrf2 in the NSUN2-WT group was significantly higher than that of the control group, whereas there was no significant change in Nrf2 level in the mutant NSUN2 group. Luciferase analysis demonstrated that NSUN2 could recognize and activate the Nrf2 5'UTR region of LO2 cells. In addition, RIP analysis revealed that ALYREF could recognize and bind to Nrf2 mRNA and that ALYREF controls the regulatory effect of NSUN2 on Nrf2., Conclusion: NSUN2 regulates Dox-induced liver cell damage by increasing Nrf2 mRNA m5C methylation to inhibit inhibiting antioxidant stress. The regulatory effect of NSUN2 on Nrf2 depends on ALYREF., (© 2024. The Author(s).)

The Corona Virus Disease (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has quickly spread worldwide and resulted in significant morbidity and mortality. Although most infections are mild, some patients can also develop severe and fatal myocarditis. In eukaryotic RNAs, 5-methylcytosine (m5C) is a common kind of post-transcriptional modification, which is involved in regulating various biological processes (such as RNA export, translation, and stability maintenance). With the rapid development of m5C modification detection technology, studies related to viral m5C modification are ever-increasing. These studies have revealed that m5C modification plays an important role in various stages of viral replication, including transcription and translation. According to recent studies, m5C methylation modification can regulate SARS-CoV-2 infection by modulating innate immune signaling pathways. However, the specific role of m5C modification in SARS-CoV-2-induced myocarditis remains unclear. Therefore, this review aims to provide insights into the molecular mechanisms of m5C methylation in SARS-CoV-2 infection. Moreover, the regulatory role of NSUN2 in viral infection and host innate immune response was also highlighted. This review may provide new directions for developing therapeutic strategies for SARS-CoV-2-associated myocarditis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Xiong, Li, Qian and Zhang.)

RNA 5-methylcytosine (m5C) is an abundant chemical modification in mammalian RNAs and plays crucial roles in regulating vital physiological and pathological processes, especially in cancer. However, the dysregulation of m5C and its underlying mechanisms in non-small cell lung cancer (NSCLC) remain unclear. Here we identified that NSUN2, a key RNA m5C methyltransferase, is highly expressed in NSCLC tumor tissue. We found elevated NSUN2 expression levels strongly correlate with tumor grade and size, predicting poor outcomes for NSCLC patients. Furthermore, RNA-seq and subsequent confirmation studies revealed the antioxidant-promoting transcription factor NRF2 is a target of NSUN2, and depleting NSUN2 decreases the expression of NRF2 and increases the sensitivity of NSCLC cells to ferroptosis activators both in vitro and in vivo. Intriguingly, the methylated-RIP-qPCR assay results indicated that NRF2 mRNA has a higher m5C level when NSUN2 is overexpressed in NSCLC cells but shows no significant changes in the NSUN2 methyltransferase-deficient group. Mechanistically, we confirmed that NSUN2 upregulates the expression of NRF2 by enhancing the stability of NRF2 mRNA through the m5C modification within its 5'UTR region recognized by the specific m5C reader protein YBX1, rather than influencing its translation. In subsequent rescue experiments, we show knocking down NRF2 diminished the proliferation, migration, and ferroptosis tolerance mediated by NSUN2 overexpression. In conclusion, our study unveils a novel regulatory mechanism in which NSUN2 sustains NRF2 expression through an m5C-YBX1-axis, suggesting that targeting NSUN2 and its regulated ferroptosis pathway might offer promising therapeutic strategies for NSCLC patients., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interests with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Impaired endometrial decidualization is the primary cause of recurrent implantation failure (RIF). RNA methylation modification, especially NSUN family mediated m 5 C, is crucial for various physiological events, such as maternal-to-zygotic transition, gametogenesis, embryonic development, organismal lifespan, and cell cycle. However, the regulatory mechanisms between NSUN family mediated m 5 C modification and RIF remain unknown. We acquired NSUN2 expression data of 15 human endometrium samples at proliferative and secretory stages from reproductive cell atlas. The overall pattern of m 5 C sites and genes was elucidated through m 5 C-BS-seq, whereas the overall m 5 C levels in different groups were revealed by dot blot assay. BrdU and western blotting assays were carried out to evaluate the role of NSUN2 in proliferation and autophagy. The effects of NSUN2-mediated m 5 C modification on embryo attachment were evaluated by an in vitro model of a confluent monolayer of Ishikawa cells cocultured with BeWo spheroids, and its downstream targets were evaluated by real-time reverse-transcription PCR and western blotting in Ishikawa cells. The molecular mechanism for NSUN2 regulating its downstream targets' expression was determined by Cut&Tag and coimmunoprecipitation assays. NSUN2 was increased in SOX9 + cells and widespread in epithelial cell type at the proliferative stage by previous single-cell RNA sequencing data. NSUN2 overexpression (NSUN2 OE ) in the Ishikawa cell line elevated m 5 C levels and promoted cell proliferation and autophagy. NSUN2 OE reduced attachment efficiency of BeWo cell spheres. Overexpressed NSUN2 was found to increase STAT1 and MMP14 mRNA expressions by inducing exon skipping. NSUN2 interacted with CLDN4 through m 5 C modification, and NSUN2 OE or NSUN2 knockdown resulted in a similar variation tendency of CLDN4. Overexpression of NSUN2 increased CLDN4 H3K9ac modification by downregulating SIRT4 expression at the protein level, leading to the upregulation of CLDN4 mRNA expression. Our results uncovered a novel intricate regulatory mechanism between NSUN2-mediated m 5 C and RIF and suggested a potential new therapeutic strategy for RIF., (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study is to investigate whether fat mass and obesity-associated protein (FTO) and NOL1/NOP2/Sun domain family member 2 (NSUN2) mediated RNA methylation is associated with RA pathology., Methods: We studied the anti-rheumatoid arthritis (RA) mechanism mediated by FTO and NSUN2 in RA samples and collagen-induced arthritis (CIA) rats using real time qPCR (RT-qPCR), western blot, immunofluorescence, and other methods., Key Findings: The expression of NSUN2 was significantly increased in both RA patients and CIA rats compared with normal controls. Knockdown of NSUN2 blocked the Wnt/β-catenin signaling pathway and inhibited RA pathological factors such as MMP3, fibronectin, and interleukins. FTO overexpression inhibited RA by inhibiting the expression of NSUN2, up-regulating the level of SFRP1 protein, and blocking the Wnt/β-catenin signaling pathway. NSUN2 overexpression interfered with the inhibitory effects of FTO on the Wnt/β-catenin signaling pathway and RA pathology, which further verified that FTO inhibited RA through the NSUN2/SFRP1/Wnt/β-catenin signal axis., Conclusions: FTO and NSUN2 are important factors of RA, and this work provides new potential diagnostic biomarkers and therapeutic targets for RA. We also reveal a gene expression regulation pattern of the interaction between m6A and m5C. revealing the pathogenesis of RA from the perspective of RNA methylation., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: NOP2/Sun domain 2 (NSUN2) is one of the important RNA methyltransferases catalyzing 5-methylcytosine (m5C) formation and participates in many critical bioprocesses. However, the roles and underlying molecular mechanisms of NSUN2-mediated m5C modification in colorectal cancer (CRC) remain unclear., Methods: To explore the NSUN2 expression in CRC, fresh tissue samples were collected and Nsun2 knockout mouse was constructed. In vitro and in vivo functional assays were conducted to assess the role of NSUN2. RNA array and bisulfite sequencing were used to investigate the potential targets. The mechanisms of NSUN2 function on SKIL were identified by m5C-methylated-RNA immunoprecipitation and RNA stability assays. Additionally, tissue microarray analysis was conducted and patient-derived tumour xenograft mouse (PDX) models were used to define the potential therapeutic targets., Results: NSUN2 was highly expressed in CRC and correlated with poor CRC patient survival. Moreover, silencing NSUN2 suppressed CRC tumourigenesis and progression in Nsun2 knockout mouse models. In vitro and in vivo studies suggested that NSUN2 promoted colorectal cancer cell growth. Mechanistically, SKI-like proto-oncogene (SKIL) is positively regulated by NSUN2, and the NSUN2-SKIL axis is clinically relevant to CRC. NSUN2 induced m5C modification of SKIL and stabilized its mRNA, which was mediated by Y-box binding protein 1 (YBX1). Elevated SKIL levels increased transcriptional coactivator with PDZ-binding motif (TAZ) activation., Conclusions: Our findings highlight the importance of NSUN2 in the initiation and progression of CRC via m5C-YBX1-dependent stabilization of the SKIL transcript, providing a promising targeted therapeutic strategy for CRC., (© 2024 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Angiogenesis plays a major role in tumor initiation, progression, and metastasis. This is why finding antiangiogenic targets is essential in the treatment of gliomas. In this study, NSUN2 and LINC00324 were significantly upregulated in conditionally cultured glioblastoma endothelial cells (GECs). Knockdown of NSUN2 or LINC00324 inhibits GECs angiogenesis. NSUN2 increased the stability of LINC00324 by m5C modification and upregulated LINC00324 expression. LINC00324 competes with the 3'UTR of CBX3 mRNA to bind to AUH protein, reducing the degradation of CBX3 mRNA. In addition, CBX3 directly binds to the promoter region of VEGFR2, enhances VEGFR2 transcription, and promotes GECs angiogenesis. These findings demonstrated NSUN2/LINC00324/CBX3 axis plays a crucial role in regulating glioma angiogenesis, which provides new strategies for glioma therapy., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2023. Published by Elsevier B.V.)

Endometrial cancer (EC) is a prevalent gynecological malignancy worldwide, and 5-methylcytosine (m 5 C) modification of mRNA is a crucial epigenetic modification associated with the development and occurrence of several cancers. However, the precise function of m 5 C modification in EC remains elusive. This study aimed to investigate the expression and clinical significance of the primary m 5 C modification writer, NSUN2, in EC. Our findings indicated that NSUN2 exhibited a substantial up-regulation in EC as a result of an epigenetic augmentation in H3K4me3 levels within the promoter region, which was triggered by the down-regulation of KDM5A. Moreover, gain- and loss-of-function experiments revealed the role of NSUN2 in enhancing m 5 C modification of mRNA, thereby promoting EC cell proliferation. RNA bisulfite sequencing and transcriptomic sequencing were employed to elucidate the involvement of NSUN2 in the regulation of ferroptosis. Subsequent in vitro experiments confirmed that the knockdown of NSUN2 significantly up-regulated the levels of lipid peroxides and lipid ROS in EC cells, thereby augmenting the susceptibility of EC to ferroptosis. Mechanistically, NSUN2 stimulated the m 5 C modification of SLC7A11 mRNA, and the m 5 C reader YBX1 exhibited direct recognition and binding to the m 5 C sites on SLC7A11 mRNA via its internal cold shock domain (CSD), leading to an increase in SLC7A11 mRNA stability and elevated levels of SLC7A11. Additionally, rescue experiments showed that NSUN2 functioned as a suppressor of ferroptosis, which was dependent on SLC7A11. Overall, targeting the NSUN2/SLC7A11 axis inhibited tumor growth by increasing lipid peroxidation and ferroptosis of EC cells both in vitro and in vivo. Therefore, our study provides new insight into the role of NSUN2, suggesting that NSUN2 may serve as a prognostic biomarker and therapeutic target in patients with EC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

NSUN2 is a critical methyltransferase for adding m5C to RNA. Its upregulation promotes the growth and metastasis of several tumors including gastric cancer (GC). However, it is unclear if NSUN2 can improve the chemosensitivity of GC to treatment with therapeutic agents such as cisplatin (CDDP) and 5-fluorouracil (5-FU). Flow cytometry was used to measure the effects of knocked-down NSUN2 expression on GC cell apoptosis and cell cycle progression. Western blot analysis examined specific signaling pathways through which NSUN2 mediates control of responses underlying the GC tumorous phenotype. NSUN2 expression was upregulated in GC tissues and its levels of rises were related to the extent of lymph node metastasis and increases in Ki67 proliferative marker expression. NSUN2 shRNA transfection suppressed rises in ERK1/2 phosphorylation status and downregulated anti-apoptosis protein Bcl-2 and upregulated pro-apoptosis protein Bax. Overall, the results reveal that NSUN2 downregulation promotes the GC chemosensitivity to inverse modulation by chemotherapeutic agents of Bcl-2 and Bax expression levels and declines in ERK1/2-induced proliferation. Our results indicate that inhibition of NSUN2 activation may be an effective procedure to enhance the efficacy of chemotherapeutic agents used to clinically treat GC., Competing Interests: Declaration of Competing Interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

5-Methylcytosine (m 5 C) is an RNA modification prevalent on tRNAs, where it can protect tRNAs from endonucleolytic cleavage to maintain protein synthesis. The NSUN family (NSUN1-7 in humans) of RNA methyltransferases are capable of installing the methyl group onto the C 5 position of cytosines in RNA. NSUNs are implicated in a wide range of (patho)physiological processes, but selective and cell-active inhibitors of these enzymes are lacking. Here, we use cysteine-directed activity-based protein profiling (ABPP) to discover azetidine acrylamides that act as stereoselective covalent inhibitors of human NSUN2. Despite targeting a conserved catalytic cysteine in the NSUN family, the NSUN2 inhibitors show negligible cross-reactivity with other human NSUNs and exhibit good proteome-wide selectivity. We verify that the azetidine acrylamides inhibit the catalytic activity of recombinant NSUN2, but not NSUN6, and demonstrate that these compounds stereoselectively disrupt NSUN2-tRNA interactions in cancer cells, leading to a global reduction in tRNA m 5 C content. Our findings thus highlight the potential to create isotype-selective and cell-active inhibitors of NSUN2 with covalent chemistry targeting a conserved catalytic cysteine., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A common mRNA modification is 5-methylcytosine (m 5 C), whose role in gene-transcript processing and cancer remains unclear. Here, we identify serine/arginine-rich splicing factor 2 (SRSF2) as a reader of m 5 C and impaired SRSF2 m 5 C binding as a potential contributor to leukemogenesis. Structurally, we identify residues involved in m 5 C recognition and the impact of the prevalent leukemia-associated mutation SRSF2 P95H . We show that SRSF2 binding and m 5 C colocalize within transcripts. Furthermore, knocking down the m 5 C writer NSUN2 decreases mRNA m 5 C, reduces SRSF2 binding, and alters RNA splicing. We also show that the SRSF2 P95H mutation impairs the ability of the protein to read m 5 C-marked mRNA, notably reducing its binding to key leukemia-related transcripts in leukemic cells. In leukemia patients, low NSUN2 expression leads to mRNA m 5 C hypomethylation and, combined with SRSF2 P95H , predicts poor outcomes. Altogether, we highlight an unrecognized mechanistic link between epitranscriptomics and a key oncogenesis driver., Competing Interests: Declaration of interests F.F. is a co-founder of Epics Therapeutics (Gosselies, Belgium)., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Cellular apoptosis is a central mechanism leveraged by chemotherapy to treat human cancers. 5-Methylcytosine (m5C) modifications installed on both DNA and mRNA are documented to regulate apoptosis independently. However, the interplay or crosstalk between them in cellular apoptosis has not yet been explored. Here, we reported that promoter methylation by DNMT1 coordinated with mRNA methylation by NSun2 to regulate osteosarcoma cell apoptosis. DNMT1 was induced during osteosarcoma cell apoptosis triggered by chemotherapeutic drugs, whereas NSun2 expression was suppressed. DNMT1 was found to repress NSun2 expression by methylating the NSun2 promoter. Moreover, DNMT1 and NSun2 regulate the anti-apoptotic genes AXL, NOTCH2, and YAP1 through DNA and mRNA methylation, respectively. Upon exposure to cisplatin or doxorubicin, DNMT1 elevation drastically reduced the expression of these anti-apoptotic genes via enhanced promoter methylation coupled with NSun2 ablation-mediated attenuation of mRNA methylation, thus rendering osteosarcoma cells to apoptosis. Collectively, our findings establish crosstalk of importance between DNA and RNA cytosine methylations in determining osteosarcoma resistance to apoptosis during chemotherapy, shedding new light on future treatment of osteosarcoma, and adding additional layers to the control of gene expression at different epigenetic levels., (© 2023 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Background: Translation dysregulation plays a crucial role in tumourigenesis and cancer progression. Oncogenic translation relies on the stability and availability of tRNAs for protein synthesis, making them potential targets for cancer therapy., Methods: This study performed immunohistochemistry analysis to assess NSUN2 levels in thyroid cancer. Furthermore, to elucidate the impact of NSUN2 on anaplastic thyroid cancer (ATC) malignancy, phenotypic assays were conducted. Drug inhibition and time-dependent plots were employed to analyse drug resistance. Liquid chromatography-mass spectrometry and bisulphite sequencing were used to investigate the m 5 C methylation of tRNA at both global and single-base levels. Puromycin intake and high-frequency codon reporter assays verified the protein translation level. By combining mRNA and ribosome profiling, a series of downstream proteins and codon usage bias were identified. The acquired data were further validated by tRNA sequencing., Results: This study observed that the tRNA m 5 C methyltransferase NSUN2 was up-regulated in ATC and is associated with dedifferentiation. Furthermore, NSUN2 knockdown repressed ATC formation, proliferation, invasion and migration both in vivo and in vitro. Moreover, NSUN2 repression enhanced the sensitivity of ATC to genotoxic drugs. Mechanically, NSUN2 catalyses tRNA structure-related m 5 C modification, stabilising tRNA that maintains homeostasis and rapidly transports amino acids, particularly leucine. This stable tRNA has a substantially increased efficiency necessary to support a pro-cancer translation program including c-Myc, BCL2, RAB31, JUNB and TRAF2. Additionally, the NSUN2-mediated variations in m5C levels and different tRNA Leu iso-decoder families, partially contribute to a codon-dependent translation bias. Surprisingly, targeting NSUN2 disrupted the c-Myc to NSUN2 cycle in ATC., Conclusions: This research revealed that a pro-tumour m5C methyltransferase, dynamic tRNA stability regulation and downstream oncogenes, c-Myc, elicits a codon-dependent oncogenic translation network that enhances ATC growth and formation. Furthermore, it provides new opportunities for targeting translation reprogramming in cancer cells., (© 2023 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Glucose metabolism is known to orchestrate oncogenesis. Whether glucose serves as a signaling molecule directly regulating oncoprotein activity for tumorigenesis remains elusive. Here, we report that glucose is a cofactor binding to methyltransferase NSUN2 at amino acid 1-28 to promote NSUN2 oligomerization and activation. NSUN2 activation maintains global m 5 C RNA methylation, including TREX2, and stabilizes TREX2 to restrict cytosolic dsDNA accumulation and cGAS/STING activation for promoting tumorigenesis and anti-PD-L1 immunotherapy resistance. An NSUN2 mutant defective in glucose binding or disrupting glucose/NSUN2 interaction abolishes NSUN2 activity and TREX2 induction leading to cGAS/STING activation for oncogenic suppression. Strikingly, genetic deletion of the glucose/NSUN2/TREX2 axis suppresses tumorigenesis and overcomes anti-PD-L1 immunotherapy resistance in those cold tumors through cGAS/STING activation to facilitate apoptosis and CD8 + T cell infiltration. Our study identifies NSUN2 as a direct glucose sensor whose activation by glucose drives tumorigenesis and immunotherapy resistance by maintaining TREX2 expression for cGAS/STING inactivation., Competing Interests: Declaration of interests H.-K.L. is a consultant for Stablix, Inc., (Copyright © 2023 Elsevier Inc. All rights reserved.)

RNA modifications affect many biological processes and physiological diseases. The 5-methylcytosine (m 5 C) modification regulates the progression of multiple tumors. However, its characteristics and functions in hepatocellular carcinoma (HCC) remain largely unknown. Here, we found that HCC tissues had a higher m 5 C methylation level than the adjacent normal tissues. Transcriptome analysis revealed that the hypermethylated genes mainly participated in the phosphokinase signaling pathways, such as the Ras and PI3K-Akt pathways. The m 5 C methyltransferase NSUN2 was highly expressed in HCC tissues. Interestingly, the expression of many genes was positively correlated with the expression of NSUN2, including GRB2, RNF115, AATF, ADAM15, RTN3, and HDGF. Real-time PCR assays further revealed that the expression of the mRNAs of GRB2, RNF115, and AATF decreased significantly with the down-regulation of NSUN2 expression in HCC cells. Furthermore, NSUN2 could regulate the cellular sensitivity of HCC cells to sorafenib via modulating the Ras signaling pathway. Moreover, knocking down NSUN2 caused cell cycle arrest. Taken together, our study demonstrates the vital role of NSUN2 in the progression of HCC., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: RNA 5-methylcytosine (m 5 C) modification plays critical roles in the pathogenesis of various tumors. However, the function and molecular mechanism of RNA m 5 C modification in tumor drug resistance remain unclear., Methods: The correlation between RNA m 5 C methylation, m 5 C writer NOP2/Sun RNA methyltransferase family member 2 (NSUN2) and EGFR-TKIs resistance was determined in non-small-cell lung cancer (NSCLC) cell lines and patient samples. The effects of NSUN2 on EGFR-TKIs resistance were investigated by gain- and loss-of-function assays in vitro and in vivo. RNA-sequencing (RNA-seq), RNA bisulfite sequencing (RNA-BisSeq) and m 5 C methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR) were performed to identify the target gene of NSUN2 involved in EGFR-TKIs resistance. Furthermore, the regulatory mechanism of NSUN2 modulating the target gene expression was investigated by functional rescue and puromycin incorporation assays., Results: RNA m 5 C hypermethylation and NSUN2 were significantly correlated with intrinsic resistance to EGFR-TKIs. Overexpression of NSUN2 resulted in gefitinib resistance and tumor recurrence, while genetic inhibition of NSUN2 led to tumor regression and overcame intrinsic resistance to gefitinib in vitro and in vivo. Integrated RNA-seq and m 5 C-BisSeq analyses identified quiescin sulfhydryl oxidase 1 (QSOX1) as a potential target of aberrant m 5 C modification. NSUN2 methylated QSOX1 coding sequence region, leading to enhanced QSOX1 translation through m 5 C reader Y-box binding protein 1 (YBX1)., Conclusions: Our study reveals a critical function of aberrant RNA m 5 C modification via the NSUN2-YBX1-QSOX1 axis in mediating intrinsic resistance to gefitinib in EGFR-mutant NSCLC., (© 2023. The Author(s).)

Background: The precise temporal and spatial regulation of N 5 -methylcytosine (m 5 C) RNA modification plays essential roles in RNA metabolism, and is necessary for the maintenance of epigenome homeostasis. Howbeit, the mechanism underlying the m 5 C modification in carcinogenesis remains to be fully addressed., Methods: Global and mRNA m 5 C levels were determined by mRNA isolation and anti-m 5 C dot blot in both retinoblastoma (RB) cells and clinical samples. Orthotopic intraocular xenografts were established to examine the oncogenic behaviours of RB. Genome-wide multiomics analyses were performed to identify the functional target of NSUN2, including proteomic analysis, transcriptome screening and m 5 C-methylated RNA immunoprecipitation sequencing (m 5 C-meRIP-seq). Organoid-based single-cell analysis and gene-correlation analysis were performed to verify the NSUN2/ALYREF/m 5 C-PFAS oncogenic cascade., Results: Herein, we report that NSUN2-mediated m 5 C RNA methylation fuels purine biosynthesis during the oncogenic progression of RB. First, we discovered that global and mRNA m 5 C levels were significantly enriched in RBs compared to normal retinas. In addition, tumour-specific NSUN2 expression was noted in RB samples and cell lines. Therapeutically, targeted correction of NSUN2 exhibited efficient therapeutic efficacy in RB both in vitro and in vivo. Through multiomics analyses, we subsequently identified phosphoribosylformylglycinamidine synthase (PFAS), a vital enzyme in purine biosynthesis, as a downstream candidate target of NSUN2. The reintroduction of PFAS largely reversed the inhibitory phenotypes in NSUN2-deficient RB cells, indicating that PFAS was a functional downstream target of NSUN2. Mechanistically, we found that the m 5 C reader protein ALYREF was responsible for the recognition of the m 5 C modification of PFAS, increasing its expression by enhancing its RNA stability., Conclusions: Conclusively, we initially demonstrated that NSUN2 is necessary for oncogenic gene activation in RB, expanding the current understanding of dynamic m 5 C function during tumour progression. As the NSUN2/ALYREF/m 5 C-PFAS oncogenic cascade is an important RB trigger, our study suggests that a targeted m 5 C reprogramming therapeutic strategy may be a novel and efficient anti-tumour therapy approach., (© 2023 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

Background: Colorectal cancer (CRC) is a harmful cancer with high morbidity and poor prognosis. There is growing evidence that RNA methylation is closely related to the occurrence of cancer and its malignant biological behavior. N6-methyladenosine (m 6 A) methylation is the most common RNA modification in eukaryotes, and its multiple regulatory mechanisms in CRC have been elucidated from multiple perspectives. At the same time, the role of 5-methylcytosine (m5C), another important and widely distributed methylation modification, in CRC is far from being elucidated. Methods: In this study, we used RNA immunoprecipitation sequencing combined with bioinformatics methods to identify the m5C peaks on messenger RNA (mRNA) in HCT15 cells and sh-NSUN2 HCT15 cells, understand which transcripts are modified by m5C, and characterize the distribution of m5C modifications. In addition, we performed further bioinformatics analysis of the detected data to initially clarify the potential function of these m5C-modified transcripts. Results: We found significant differences in the distribution of m5C between HCT15 cells and sh-NSUN2 HCT15 cells, suggesting that m5C is likely to play a key role in the occurrence and development of CRC. Furthermore, Gene Ontology (GO) enrichment analysis showed that genes altered by m5C were mainly enriched in phylogeny, synaptic membrane, and transcription factor binding. The Kyoto Encyclopedia of Genes and Genomes (KEGG)pathway analysis showed that the genes altered by m5C are enriched in ECM receptor interaction pathway, the circadian pathway, and the cAMP signaling pathway. Conclusion: Here, our study preliminarily revealed the different distribution patterns of m5C between HCT15 cell and sh-NSUN2 HCT15 cell. Our results open a new window to understand the role of m5C RNA methylation of mRNA in the development of CRC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Lin, Zhao, Nie, Huang, Cai, Wang, Wang, Huang and Bai.)

Neuroblastoma is the most common tumor in infants. RNA m5C modification regulates the survival, differentiation, and migration of cells affecting RNA function. However, the effects of the m5C modification methyltransferase gene NSUN2 polymorphism on neuroblastoma susceptibility have not been reported. TaqMan method was used to determine genotypes of four NSUN2 polymorphisms (rs4702373 C>T, rs13181449 C>T, rs166049 T>G, and rs8192120 A>C) in 402 patients with neuroblastoma and 473 cancer-free controls from Jiangsu province, China. Odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the association of NSUN2 polymorphisms with neuroblastoma susceptibility. The association was also further assessed in subgroups stratified by age, sex, tumor origin, and stage. GTEx was used to analyze the effect of these polymorphisms on NSUN2 expression. We found the rs13181449 C>T was significantly associated with reduced neuroblastoma risk (CT vs. CC: adjusted OR = 0.68, 95% CI = 0.51-0.92, P = 0.012; CT/TT vs. CC: adjusted OR = 0.70, 95% CI = 0.53-0.92, P = 0.010). Compared with 0-2 protective genotypes, those with 3-4 protective genotypes could significantly reduce the neuroblastoma risk (adjusted OR = 0.68, 95% CI = 0.52 to 0.90, P = 0.006). Stratification analysis showed that the protective effect of rs13181449 polymorphism remained significant in children with age >18 months, boys, and those with early INSS stages. Moreover, children with more protective genotypes in the same subgroups also exhibited significantly reduced neuroblastoma risk. GTEx analysis showed that the rs13181449 T genotype was related with decreased NSUN2 gene expression. In conclusions, NSUN2 rs13181449 polymorphism is associated with decreased neuroblastoma risk, and the underlying mechanism in neuroblastoma needs further study., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Epitranscriptomic regulation adds a layer of post-transcriptional control to brain function during development and adulthood. The identification of RNA-modifying enzymes has opened the possibility of investigating the role epitranscriptomic changes play in the disease process. NOP2/Sun RNA methyltransferase 2 (NSun2) is one of the few known brain-enriched methyltransferases able to methylate mammalian non-coding RNAs. NSun2 loss of function due to autosomal-recessive mutations has been associated with neurological abnormalities in humans. Here, we show NSun2 is expressed in adult human neurons in the hippocampal formation and prefrontal cortex. Strikingly, we unravel decreased NSun2 protein expression and an increased ratio of pTau/NSun2 in the brains of patients with Alzheimer's disease (AD) as demonstrated by Western blotting and immunostaining, respectively. In a well-established Drosophila melanogaster model of tau-induced toxicity, reduction of NSun2 exacerbated tau toxicity, while overexpression of NSun2 partially abrogated the toxic effects. Conditional ablation of NSun2 in the mouse brain promoted a decrease in the miR-125b m6A levels and tau hyperphosphorylation. Utilizing human induced pluripotent stem cell (iPSC)-derived neuronal cultures, we confirmed NSun2 deficiency results in tau hyperphosphorylation. We also found that neuronal NSun2 levels decrease in response to amyloid-beta oligomers (AβO). Notably, AβO-induced tau phosphorylation and cell toxicity in human neurons could be rescued by overexpression of NSun2. Altogether, these results indicate that neuronal NSun2 deficiency promotes dysregulation of miR-125b and tau phosphorylation in AD and highlights a novel avenue for therapeutic targeting., (© 2022. The Author(s).)

Background: Prostate cancer (PCa) is a major type of cancer in man worldwide. Androgen deprivation therapy (ADT) and the next-generation androgen receptor (AR) pathway inhibitors have acquired great success in treating PCa. However, patients treated with ADT or AR targeted therapy are inevitably developing into castration-resistant prostate cancer (CRPC) or becoming drug resistance. The role of mRNA 5-methylcytosine (m5C) modification in cancers is largely unknown. This study aimed to explore the role of the m5C methyltransferase NSUN2 in Prostate cancer (PCa)., Methods: The expression of NSUN2 and its clinicopathological impact were evaluated in PCa cohorts. The effect of NSUN2 on the biological characteristics of PCa cells was investigated on the basis of gain-offunction and loss-of-function analyses. Subcutaneous models further uncovered the role of NSUN2 in tumor growth. Epi-transcriptome assays with RNA bisulfite sequencing (RNA-BisSeq) analysis and in vitro enzyme reaction assays were performed to validate the targeted effect of NSUN2 on AR. AR-binding sites in the NSUN2 promoter were investigated by ChIP and luciferase assays to uncover the interplay between NSUN2 and AR signaling. RIP-qPCR and EMSA methods were performed to confirm that YBX1 binds to AR m 5 C sites., Results: NSUN2 is highly expressed in PCa and predicts poor outcome. NSUN2 plays roles as a PCa oncogene both in vitro and in vivo. Depletion of NSUN2 results in decreased expression and activities of AR, including AR-V7. Mechanistically, NSUN2 posttranscriptionally stabilized AR by cluster m 5 C modification in a m5CYBX1-dependent manner. Strikingly, treatment with enzalutamide, an effective AR inhibitor, reduces NSUN2 expression and decreases the m5C modification level in prostate cancer cells. Finally, we found that AR transcriptionally regulates NSUN2., Conclusion: NSUN2 stabilizes AR mRNA through cluster 5-methylcytosine modification and activates a positive feedback loop to promote prostate cancer., (© 2022 The Authors. Clinical and Translational Medicine published by John Wiley & Sons Australia, Ltd on behalf of Shanghai Institute of Clinical Bioinformatics.)

RNA 5-methylcytosine (m 5 C) is a widespread post-transcriptional modification involved in diverse biological processes through controlling RNA metabolism. However, its roles in uveal melanoma (UM) remain unknown. Here, we describe the biological roles and regulatory mechanisms of RNA m 5 C in UM. Initially, we identified significantly elevated global RNA m 5 C levels in both UM cells and tissue specimens using ELISA assay and dot blot analysis. Meanwhile, NOP2/Sun RNA methyltransferase family member 2 (NSUN2) was upregulated in both types of these samples, whereas NSUN2 knockdown significantly decreased RNA m 5 C level. Such declines inhibited UM cell migration and suppressed cell proliferation through cell cycle G1 arrest. Furthermore, bioinformatic analyses, m 5 C-RIP-qPCR, and luciferase assay identified β-Catenin (CTNNB1) as a direct target of NSUN2-mediated m 5 C modification in UM cells. Additionally, overexpression of miR-124a in UM cells diminished NSUN2 expression levels indicating that it is an upstream regulator of this response. Our study suggests that NSUN2-mediated RNA m 5 C methylation provides a potential novel target to improve the therapeutic management of UM pathogenesis.

Background: Prostate cancer is the most common tumor in men worldwide, seriously threatening the health of older men, and 5-methylcytosine (m5C) RNA modification has been shown to have a significant impact on the development and progression of various tumors. However, as the most critical methyltransferase for m5c RNA modification, the role of the NSUN members (NSUN1-7) in prostate cancer is unclear., Methods: We obtained sequencing data of genes and related clinical data of prostate cancer from The Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus (GEO) database and analyzed the correlation between NSUN members' expression and prognosis. we found that NSUN2 was closely implicated in the prognosis of prostate cancer, then verified the expression of NSUN2 in clinical samples, and obtained the correlation between NSUN2 and immune cell infiltration through CIBERSORT algorithm and ESTIMATE method. The relationship between NSUN2 copy number variation and immune cell infiltration was further analyzed in the TIMER database and identified signaling pathways associated with NSUN2 expression by GO, KEGG, and GSEA analysis. Finally, we verified the expression of NSUN2 in prostate cancer cell lines and confirmed the role of NSUN2 on the biological behavior of prostate cancer cells by proliferation and migration-related assays., Results: NOP2 and NSUN2 were upregulated in prostate tumor tissues. NSUN2 expression is closely associated with tumor prognosis. NSUN2 high expression implies poor clinical features, and the NSUN family is significantly associated with tumor stromal score and immune score. Besides, NSUN2 is associated with a variety of immune infiltrating cells (B cells memory, T cells CD4 memory resting, T cells CD4 memory activated, NK cells resting, and so on). High NSUN2 expression lowers the sensitivity of many chemotherapy drugs, such as docetaxel, doxorubicin, fluorouracil, cisplatin, and etoposide. In prostate cancer, the most common type of mutation in NSUN2 is amplification, and NSUN2 copy number variation is closely associated with NSUN2 expression and immune cell infiltration. GSEA analysis showed that the related genes were mainly enriched in ubiquitin-mediated protein hydrolysis, cell cycle, RNA degradation, endometrial cancer, prostate cancer, p53 signaling pathway, and NSUN2 potentiated the proliferation and migration of prostate cancer cells., Conclusions: NSUN2 is highly expressed in prostate cancer, which contributes to the progression of prostate cancer, and is closely implicated in immune cell infiltration and chemotherapy drugs. NSUN2 is expected to be a prospective marker and a new treatment target for prostate cancer., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sun, Ma, Zheng, Wang, Chen, Chang, Liang, Jiang, Xu and Liu.)

Cholangiocarcinoma (CCA) is a severe malignancy originating from the bile duct and the second most common primary liver cancer. NF-kappa B interacting lncRNA (NKILA) is a functional lncRNA, which play important role in human cancers. However, the role and underlying mechanism of NKILA in CCA remains largely unknown. Here, our study demonstrated that NKILA was significantly upregulated in CCA tissues and cells. Overexpression of NKILA is associated with advanced TNM stage, lymph node and distant metastasis, and also indicated poor prognosis in CCA patients. Functionally, NKILA facilitated CCA growth and metastasis in vitro and in vivo. The 5-methylcytosine (m 5 C) methyltransferase NSUN2 interacts with NKILA, increasing its m 5 C level and promoting its interaction with YBX1. Moreover, NKILA physically interacted with and suppressed miR-582-3p, which was regulated by METTL3-mediated N 6 -methyladenosine (m 6 A) modification. Finally, we showed that YAP1 was a target of NKILA via miR-582-3p and NKILA functioned partially via YAP1 in CCA. Taken together, our findings indicate a novel regulatory mechanism of NKILA for promoting CCA progression and that NKILA may be a promising target for CCA treatment., (© 2022 John Wiley & Sons A/S . Published by John Wiley & Sons Ltd.)

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in the head and neck with a complex etiology, such as environmental factors, genetic factors, and Epstein-Barr virus infection. The NOP2/Sun domain family, member 2 (NSUN2) is a methyltransferase of m5C methylation modification that has been reported to be involved in the occurrence and progression of various tumors, but its role in NPC remains unclear. In this study, we found that NSUN2 was upregulated in NPC and predicted a poor prognosis for NPC patients in both GEO datasets and our tissue microarrays containing 125 NPC tissues. Next, we demonstrated that NSUN2 promoted the proliferation, migration, and invasion of NPC cells in vitro . Additionally, the differential expression genes between NSUN2-high and low expression patients were mainly enriched in multi-immune cell activation and proliferation. Furthermore, NSUN2 negatively regulates immune cell infiltration in the tumor microenvironment (TME) of NPC, which indicates that the NSUN2 level may be negatively correlated with the sensitivity of immunotherapy and chemotherapy. In conclusion, our findings highlight that NSUN2 might act as an important oncogene involved in NPC progression and serve as a potential biomarker to predict poor prognosis and drug sensitivity of NPC patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Tong, Xiang, Hu, Hu, Li, Wang, Zhao, Xue and Zhu.)

Cellular senescence severely limits the research and the application of dental pulp stem cells (DPSCs). A previous study conducted by our research group revealed a close implication of ROR2 in DPSC senescence, although the mechanism underlying the regulation of ROR2 in DPSCs remains poorly understood so far. In the present study, it was revealed that the expression of the ROR2-interacting transcription factor MSX2 was increased in aging DPSCs. It was demonstrated that the depletion of MSX2 inhibits the senescence of DPSCs and restores their self-renewal capacity, and the simultaneous overexpression of ROR2 enhanced this effect. Moreover, MSX2 knockdown suppressed the transcription of NOP2/Sun domain family member 2 (NSUN2), which regulates the expression of p21 by binding to and causing the 5-methylcytidine methylation of the 3'- untranslated region of p21 mRNA. Interestingly, ROR2 downregulation elevated the levels of MSX2 protein, and not the MSX2 mRNA expression, by reducing the phosphorylation level of MSX2 and inhibiting the RNF34-mediated MSX2 ubiquitination degradation. The results of the present study demonstrated the vital role of the ROR2/MSX2/NSUN2 axis in the regulation of DPSC senescence, thereby revealing a potential target for antagonizing DPSC aging., (© The Author(s) 2022. Published by Oxford University Press.)

RNA methylation has recently emerged as an important category of epigenetic modifications, which plays diverse physiopathological roles in various cancers. Recent studies have confirmed the presence of 5-methylcytosine (m 5 C) modification on mammalian mRNAs, mainly modified by NOP2/Sun RNA methyltransferase family member 2 (NSUN2), but little is known about the underlying functions of m 5 C. Gynecologic cancers are malignancies starting from women's reproductive organs. The prevalence of gynecologic cancers leads to a massive economic burden and public health concern. In this study, we investigated the potential biological functions of NSUN2 in common gynecologic cancers including cervical cancer, ovarian cancer, and endometrial cancer. Remarkably, distinct scenarios were found. The levels of NSUN2 did not show alteration in endometrial cancer, and in ovarian cancer, depletion of upregulated NSUN2 did not reduce carcinogenesis in cancer cells, suggesting that the upregulated NSUN2 might be an incidental effect. On the contrary, NSUN2 played a role in tumorigenesis of cervical cancer; depletion of upregulated NSUN2 notably inhibited migration and invasion of cancer cells, and only wild-type but not catalytically inactive NSUN2 rescued these malignant phenotypes of cancer cells. Mechanistically, NSUN2 promoted migration and invasion by leading to m 5 C methylation on keratin 13 ( KRT13 ) transcripts, and methylated KRT13 transcripts would be recognized and stabilized by an m 5 C reader, Y-box binding protein 1 (YBX1). Collectively, these results not only displayed the nature of diversity among human malignancies, but also demonstrated a novel NSUN2-dependent m 5 C-YBX1-KRT13 oncogenic regulatory pathway., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer [QG] declared a shared affiliation with one of the authors [SL] to the handling editor at time of review., (Copyright © 2022 Wang, Zhang, Su, Maimaitiyiming, Yang, Shen, Lin, Shen, Zhan, Wang, Hsu and Cheng.)

Biallelic loss-of-function NSUN2 mutations have recently been associated with cases of Autism Spectrum Condition (ASC), and NSun2-deficiency was also previously shown to cause a severe autosomal recessive intellectually disability disorder syndrome in which patients can sometimes display autistic behaviour. It has been demonstrated that NSUN2 can control protein synthesis rates via direct regulation of RNA methylation, and it is therefore of interest that other studies have suggested protein synthesis-dependent synaptic plasticity dysregulation as a mechanism for learning difficulties in various other autism-expressing conditions and disorders. Here we investigated NMDAR-LTP in a murine transgenic model harbouring loss-of-function mutation in the NSun2 gene and find an impairment of a protein synthesis-dependent form of this synaptic plasticity pathway. Our findings support the idea that NMDAR-LTP mis-regulation may represent a previously underappreciated mechanism associated with autism phenotypes., (Copyright © 2021. Published by Elsevier Inc.)

The NSUN2 -intellectual disability syndrome is a rare disorder of the cellular transcriptome that prevents proper t-RNA splicing. This disorder interrupts cellular function and leads to an accumulation of RNA fragments, producing a constellation of symptoms including dysmorphic facies, hypotonia, microcephaly, and short stature. Eye manifestations have been reported but not well characterized. Our study presents a new case involving a 4-year-old boy with novel NSUN2 variants and clinical features consistent with the syndrome. In addition, through a systemic review, we discuss the 24 previously reported cases of the syndrome with an emphasis on the eye and ocular adnexa clinical features., Competing Interests: We report that Dr. Couser is on the Patient-Centered Outcomes Research Institute (PCORI) Advisory Panel on Rare Disease and is involved in a clinical trial with Retrophin, Inc./Travere Therapeutics, Inc. Dr. Couser is also involved in a clinical trial with the National Cancer Institute/Children’s Oncology Group and is a book editor for Elsevier. Dr. Harper is involved in VCU contracted clinical trials with the CDC, NIH, Vertex Pharmaceuticals, Muscular Dystrophy Association, Fulcrum Therapeutics, Astellas Pharma, Reveragen, ML Biosolutions, Italafarmaco, and Novartis Gene Therapies. Additional research funding from Children’s Hospital Research Grand and the VCU Center for Clinical and Translational Research. She is a chapter author for Elsevier. The authors note no other conflicts of interest and are solely responsible for the content and writing of this paper., (IJMEG Copyright © 2021.)