Mechanism of RNAm6A methylation modification regulating NLRP3 inflammasome activation for hand, foot and mouth disease progression
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ABSTRACT: During the life cycle of Enterovirus 71 (EV71), N6-methyladenosine (m6A) modification has an important impact on viral replication and the cellular response to viral infection, but the effect of m6A modification on cellular RNAs and pathways during infection is still unknown. The purpose of this research was to investigate the role of m6A in regulating host cell inflammatory response and disease progression during EV71 infection. Methylation RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) results show the m6A methylation modification map of control and EV71-infected groups of RD cells. And multilevel validation showed that decreased expression of demethylase FTO (fat mass and obesity-associated protein) was responsible for the elevated total m6A levels in EV71-infected RD cells and that TXNIP may be a target gene for demethylase FTO action. Further functional experiments showed that demethylase FTO silencing promoted TXNIP expression, activation of NLRP3 inflammasome and promoted the release of pro-inflammatory factors in vitro, and demethylase FTO overexpression showed the opposite result. Further tested in an animal model of severe EV71 infection, with results consistent with in vitro. In conclusion, our findings suggested that depletion of demethylase FTO in the presence of EV71 infection increased the m6A level of TXNIP mRNA 3ʹ UTR, increased mRNA stability, and promoted TXNIP expression, which activated the NLRP3 inflammasome and led to the release of pro-inflammatory factors, ultimately promoted HFMD progression. This could help with the development and prevention of m6A modification inhibitor-based drugs for viral-related inflammation and disease.
Project description:Functional CD8+ T cell immune response is critical for immune surveillance and host defense against infection and tumor. Epigenetic mechanisms associated with RNA modification in controlling CD8+ T cell response remain poorly understood. Here, by T cell-specific deletion of fat mass and obesity-associated protein (FTO), a critical N6-methyladenosine (m6A) demethylase, we revealed that FTO was indispensable for sufficient CD8+ T cell immune response and protective function. FTO ablation led to considerable cell death in activated CD8+ T cells, which was attributed to apoptosis. MeRIP-seq analysis identified the upregulated m6A modification on Fas mRNA in FTO deficient CD8+ T cells. Loss of FTO promoted Fas expression via enhancing the Fas mRNA stability dependent on m6A reader IGF2BP3. Mutation of the Fas m6A sites or knockdown IGF2BP3 could rescue the upregulated Fas expression and cell apoptosis caused by FTO ablation in CD8+ T cells. Our findings defined a novel epigenetic regulatory mechanism of FTO-mediated m6A modification in supporting CD8+ T cell immune responses, providing new insights into understanding the post-transcriptional regulation in CD8+ T cell immunological functions.
Project description:The RNA modification N6-methyladenosine (m6A) plays a key role in the life cycles of several RNA viruses. Whether this applies to SARS-CoV-2 and whether m6A affects the outcome of COVID-19 disease is still poorly explored. Here we report that the RNA demethylase FTO strongly affects both m6A marking of SARS-CoV-2 and COVID-19 severity. By m6A profiling of SARS-CoV-2, we confirmed in infected cultured cells and showed for the first time in vivo in hamsters that the regions encoding TRS_L and the nucleocapsid protein are multiply marked by m6A, preferentially within RRACH motifs that are specific to β-coronaviruses and well conserved across SARS-CoV-2 variants. In cells, downregulation of the m6A demethylase FTO, occurring upon SARS-CoV-2 infection, increased m6A marking of SARS-CoV-2 RNA and slightly promoted viral replication. In COVID-19 patients, a negative correlation was found between FTO expression and both SARS-CoV-2 expression and disease severity. FTO emerged as a classifier of disease severity and hence a potential stratifier of COVID-19 patients.
Project description:N6-methyladenosine (m6A) modification is the major post-transcriptional modification present in mammalian mRNA. m6A controls fundamental biological processes including cell proliferation, but the molecular mechanism remains unclear. Herein, we demonstrate that the m6A demethylase fat mass and obesity-associated (FTO) controls the cell cycle by targeting cyclin D1, the key regulator required for G1 phase progression. FTO silencing suppressed cyclin D1 expression and induced G1 arrest. FTO depletion upregulated cyclin D1 m6A modification, which in turn accelerated the degradation of cyclin D1 mRNA. Importantly, m6A modification of cyclin D1 oscillates in a cell cycle-dependent manner; m6A levels were suppressed during the G1 phase and enhanced during other phases. Low m6A levels during G1 were associated with nuclear translocation of FTO from the cytosol. Furthermore, nucleocytoplasmic shuttling of FTO is regulated by Casein Kinase II-mediated phosphorylation at Thr 150 of FTO. Our results highlight the role of m6A in regulating cyclin D1 mRNA stability, and add a new layer of complexity to cell cycle regulation.
Project description:Despite advances in clinical diagnosis and treatment, the prognosis of patients with osteosarcoma (OS) remains poor, and the treatment efficacy has plateaued. Therefore, it is important to identify new therapeutic targets for OS. N6-methyladenosine (m6A) modification has been reported to participate in tumor malignancy. In this study, functional screening found that the m6A demethylase FTO could be a candidate therapeutic target for OS. Upregulated FTO in OS could predict a poorer prognosis. FTO promoted the growth and metastasis of OS in vitro and in vivo. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were performed to identify DACT1 as a potential target of FTO. In vitro assays demonstrated that FTO could reduce the mRNA stability of DACT1 via m6A demethylation, which decreased DACT1 expression and further activated the Wnt signaling pathway. The oncogenic effect of FTO on OS was dependent on DACT1. In addition, the m6A reader IGF2BP1 was validated to participate in the regulation of DACT1. Entacapone, a conventional drug for Parkinson's disease, was confirmed to suppress OS via m6A-mediated regulation through the FTO/DACT1 axis. Our findings demonstrate that FTO may be a novel therapeutic target and that entacapone has the preclinical value to be repurposed for OS.
Project description:Despite advances in clinical diagnosis and treatment, the prognosis of patients with osteosarcoma (OS) remains poor, and the treatment efficacy has plateaued. Therefore, it is important to identify new therapeutic targets for OS. N6-methyladenosine (m6A) modification has been reported to participate in tumor malignancy. In this study, functional screening found that the m6A demethylase FTO could be a candidate therapeutic target for OS. Upregulated FTO in OS could predict a poorer prognosis. FTO promoted the growth and metastasis of OS in vitro and in vivo. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were performed to identify DACT1 as a potential target of FTO. In vitro assays demonstrated that FTO could reduce the mRNA stability of DACT1 via m6A demethylation, which decreased DACT1 expression and further activated the Wnt signaling pathway. The oncogenic effect of FTO on OS was dependent on DACT1. In addition, the m6A reader IGF2BP1 was validated to participate in the regulation of DACT1. Entacapone, a conventional drug for Parkinson's disease, was confirmed to suppress OS via m6A-mediated regulation through the FTO/DACT1 axis. Our findings demonstrate that FTO may be a novel therapeutic target and that entacapone has the preclinical value to be repurposed for OS.
Project description:Diabetic retinopathy (DR), a leading cause of irreversible vision loss in the working-age population, is an inflammatory, neuro-vascular complication of diabetes with poorly understood mechanism. N6-methyladenosine (m6A) modification plays crucial roles in biological and pathological events, while its role in DR remain elusive. Herein, we identified the pathological involvement of m6A demethylase FTO in DR. FTO expression was elevated in proliferative membranes of DR patients, endothelial cells (EC) under diabetic stress, and retinal vessels of diabetic murine models. FTO overexpression in EC promoted EC cycle progression and tip cell formation to facilitate angiogenesis in vitro, in mice and in zebrafish. FTO also regulated EC-pericyte crosstalk to trigger diabetes-induced microvascular leakage, and mediated EC-microglia crosstalk to induce retinal inflammation and subsequent neurodegeneration in vivo and in vitro. Mechanistically, FTO regulated EC features depending on its demethylation activity via modulating CDK2 mRNA stability with YTHDF2 as the reader. Moreover, FTO up-regulation in EC under diabetic conditions was driven by lactic acid mediated histone lactylation. FB23-2, which inhibits FTO’s m6A demethylase activity, suppressed diabetes associated endothelial phenotypes in vitro and in vivo. Noteworthy, we developed a novel macrophage membrane coated and PLGA-Dil based nanoplatform encapsulating FB23-2 for systemic administration, and confirmed its targeting and therapeutic efficacy in mice. Collectively, our study demonstrated an FTO-mediated regulatory network that coordinates EC biology and retinal homeostasis in DR, providing a promising nanotherapeutic approach for DR treatment. Diabetic retinopathy (DR), a leading cause of irreversible vision loss in the working-age population, is an inflammatory, neuro-vascular complication of diabetes with poorly understood mechanism. N6-methyladenosine (m6A) modification plays crucial roles in biological and pathological events, while its role in DR remain elusive. Herein, we identified the pathological involvement of m6A demethylase FTO in DR. FTO expression was elevated in proliferative membranes of DR patients, endothelial cells (EC) under diabetic stress, and retinal vessels of diabetic murine models. FTO overexpression in EC promoted EC cycle progression and tip cell formation to facilitate angiogenesis in vitro, in mice and in zebrafish. FTO also regulated EC-pericyte crosstalk to trigger diabetes-induced microvascular leakage, and mediated EC-microglia crosstalk to induce retinal inflammation and subsequent neurodegeneration in vivo and in vitro. Mechanistically, FTO regulated EC features depending on its demethylation activity via modulating CDK2 mRNA stability with YTHDF2 as the reader. Moreover, FTO up-regulation in EC under diabetic conditions was driven by lactic acid mediated histone lactylation. FB23-2, which inhibits FTO’s m6A demethylase activity, suppressed diabetes associated endothelial phenotypes in vitro and in vivo. Noteworthy, we developed a novel macrophage membrane coated and PLGA-Dil based nanoplatform encapsulating FB23-2 for systemic administration, and confirmed its targeting and therapeutic efficacy in mice. Collectively, our study demonstrated an FTO-mediated regulatory network that coordinates EC biology and retinal homeostasis in DR, providing a promising nanotherapeutic approach for DR treatment.
Project description:N6-methyladenosine (m6A) is the most abundant internal modification in the messenger RNA (mRNA) of all higher eukaryotes. This modification has been shown to be reversible in mammals; it is installed by a methyltransferase heterodimer complex of METTL3 and METTL14 bound with WTAP, and reversed by iron(II)- and α-ketoglutarate-dependent demethylases FTO and ALKBH5. This modification exhibits significant functional roles in various biological processes. The m6A modification as a RNA mark is recognized by reader proteins, such as YTH domain family proteins and HNRNPA2B1; m6A can also act as a structure switch to affect RNA-protein interactions for biological regulation. In Arabidopsis thaliana, the methyltransferase subunit MTA (the plant orthologue of human METTL3, encoded by At4g10760) was well characterized and FIP37 (the plant orthologue of human WTAP) was first identified as the interacting partner of MTA. Here we report the discovery and characterization of reversible m6A methylation mediated by AtALKBH10B (encoded by At4g02940) in A. thaliana, and noticeable roles of this RNA demethylase in affecting plant development and floral transition. Our findings reveal potential broad functions of reversible mRNA methylation in plants. m6A peaks were identified from wild type Columbia-0 and atalkbh10b-1 mutant in two biological replicates
Project description:N6-methyladenosine (m6A) RNA methylation is the most abundant internal chemical modifications in eukaryotic messenger RNA (mRNA) as well as long non-coding RNA (lncRNA). Recently, m6A RNA methylation research was revived by the discovery of the fat mass- and obesity-associated protein (FTO) as the first RNA demethylase, implicating that m6A RNA methylation is a reversible and dynamic modification and may have critical biological functions. Emerging evidence has shown that m6A modifications in mRNAs and lncRNAs play crucial roles in regulating RNA fate and function in biological processes in the past several years. As the first identified RNA demethylase that regulates the demethylation of target mRNAs, FTO has been reported to play an oncogenic role in leukemia and glioblastoma stem cells. To identify the target genes of FTO in melanoma cells, we used m6A IP seq coupled with RNA seq to determine the potential demethylation and gene targets across the whole transcriptome for FTO, and identified more than 1,000 genes.
Project description:Enterovirus 71 (EV71) is one of the leading causes of hand, foot and mouth disease with neurological complications in some cases. To study the pathogenesis of EV71 infection, large scale analyses of EV71 infected cells have been performed. However, most of these studies employed rhabdomyosarcoma (RD) cells or used transcriptomic strategy. Here, we performed SILAC-based quantitative proteomic analysis of EV71-infected U251 cells, a human glioma cell line. A total of 3,125 host proteins were quantified, 451 of which were differentially regulated as a result of EV71 infection at 8 hpi or 20 hpi or both.
Project description:The discovery of activating mutations in receptor tyrosine kinases (RTKs) leads to clinical testing of RTK inhibitors (TKIs). However, the rapid acquisition of resistance limits TKI effectiveness. Here we establish TKI-resistant cells that propagate in the absence of RTK signaling. Relative to sensitive cells, TKI-resistant cells display decreased N6-methyladenosine (m6A), a ubiquitous and reversible modification on RNA, but upregulated fat mass and obesity-associated gene (FTO), an m6A demethylase. Notably, the naïve leukemia cell populations are heterogeneous with respect to FTO levels. Cells with higher intrinsic and transient FTO expression demonstrate reduction of m6A methylation and TKI sensitivity with higher tumorigenic. Genetic or pharmacological dysfunction of FTO increases m6A abundance sensitizing resistant cells to TKIs. Mechanistically, FTO-mediated m6A demethylation promotes mRNA stability and protein translation rate, upregulating oncogenes that are indispensable for survival and proliferation. Our findings therefore establish a role of FTO-dependent m6A demethylation for TKI-resistance, offering a therapeutic window for incorporating m6A modulators in counteracting acquired TKI resistance.