Enhancing m^(6)A modification in the motor cortex facilitates corticospinal tract remodeling after spinal cord injury

Spinal cord injury typically causes corticospinal tract disruption. Although the disrupted corticospinal tract can self-regenerate to a certain degree, the underlying mechanism of this process is still unclear. N6-methyladenosine(m^(6)A) modifications are the most common form of epigenetic regulation at the RNA level and play an essential role in biological processes. However, whether m^(6)A modifications participate in corticospinal tract regeneration after spinal cord injury remains unknown. We found that expression of methyltransferase 14 protein(METTL14) in the locomotor cortex was high after spinal cord injury and accompanied by elevated m^(6)A levels. Knockdown of Mettl14 in the locomotor cortex was not favorable for corticospinal tract regeneration and neurological recovery after spinal cord injury. Through bioinformatics analysis and methylated RNA immunoprecipitation-quantitative polymerase chain reaction, we found that METTL14 regulated Trib2 expression in an m^(6)A-regulated manner, thereby activating the mitogen-activated protein kinase pathway and promoting corticospinal tract regeneration. Finally, we administered syringin, a stabilizer of METTL14, using molecular docking. Results confirmed that syringin can promote corticospinal tract regeneration and facilitate neurological recovery by stabilizing METTL14. Findings from this study reveal that m^(6)A modification is involved in the regulation of corticospinal tract regeneration after spinal cord injury.

m^(6)A修饰对药物代谢酶和药物转运体的调控作用

m^(6)A修饰是RNA甲基化修饰中最丰富的一种修饰,受甲基转移酶和去甲基化酶的动态调控,被m^(6)A识别蛋白识别并结合后可影响mRNA的剪切、稳定性和翻译等生物学过程来调控靶基因的表达。最近的研究发现,m^(6)A修饰可通过多种途径来调控药物代谢酶和药物转运体表达,进而影响机体对药物的代谢速率或影响细胞中的药物浓度,最终导致药物治疗效果发生变化。该文综述了m^(6)A修饰调控药物代谢酶和药物转运体分子机制的研究进展,以期为临床上的合理用药、个体化用药提供新思路。

Aberrant expression of enzymes regulating m^6A mRNA methylation: implication in cancer

N^6-methyladenosine(m^6 A) is an essential RNA modification that regulates key cellular processes, including stem cell renewal,cellular differentiation, and response to DNA damage. Unsurprisingly, aberrant m^6 A methylation has been implicated in the development and maintenance of diverse human cancers. Altered m^6 A levels affect RNA processing, mRNA degradation, and translation of mRNAs into proteins, thereby disrupting gene expression regulation and promoting tumorigenesis. Recent studies have reported that the abnormal expression of m^6 A regulatory enzymes affects m^6 A abundance and consequently dysregulates the expression of tumor suppressor genes and oncogenes, including MYC, SOCS2, ADAM19, and PTEN. In this review, we discuss the specific roles of m^6 A missing space "writers", "erasers", and "readers" in normal physiology and how their altered expression promotes tumorigenesis. We also describe the potential of exploiting the aberrant expression of these enzymes for cancer diagnosis, prognosis, and the development of novel therapies.

N^(6)-methyladenosine(m^(6)A)RNA modification in tumor immunity

Growing evidence supports that cancer progression is closely associated with the tumor microenvironment and immune evasion.Importantly,recent studies have revealed the crucial roles of epigenetic regulators in shaping the tumor microenvironment and restoring immune recognition.N^(6)-methyladenosine(m^(6)A)modification,the most prevalent epigenetic modification of mammalian mRNAs,has essential functions in regulating the processing and metabolism of its targeted RNAs,and therefore affects various biological processes including tumorigenesis and progression.Recent studies have demonstrated the critical functions and molecular mechanisms underlying abnormal m^(6)A modification in the regulation of tumor immunity.In this review,we summarize recent research progress in the potential roles of m^(6)A modification in tumor immunoregulation,with a special focus on the anti-tumor processes of immune cells and involvement in immune-associated molecules and pathways.Furthermore,we review current knowledge regarding the close correlation between m6A-related risk signatures and the tumor immune microenvironment landscape,and we discuss the prognostic value and therapeutic efficacy of m^(6)A regulators in a variety of cancer types.

The essential roles of m^(6)A modification in osteogenesis and common bone diseases

N6-methyladenosine(m^(6)A)is the most prevalent modification in the eukaryotic transcriptome and has a wide range of functions in coding and noncoding RNAs.It affects the fate of the modified RNA,including its stability,splicing,and translation,and plays an important role in post-transcriptional regulation.Bones play a key role in supporting and pro-tecting muscles and other organs,facilitating the movement of the organism,ensuring blood production,etc.Bone diseases such as osteoarthritis,osteoporosis,and bone tumors are serious public health problems.The processes of bone development and osteogenic differen-tiation require the precise regulation of gene expression through epigenetic mechanisms including histone,DNA,and RNA modifications.As a reversible dynamic epigenetic mark,m^(6)A modifications affect nearly every important biological process,cellular component,and molecular function,including skeletal development and homeostasis.In recent years,studies have shown that m^(6)A modification is involved in osteogenesis and bone-related diseases.In this review,we summarized the proteins involved in RNA m^(6)A modification and the latest progress in elucidating the regulatory role of m^(6)A modification in bone formation and stem cell direc-tional differentiation.We also discussed the pathological roles and potential molecular mech-anisms of m^(6)A modification in bone-related diseases like osteoporosis and osteosarcoma and suggested potential areas for new strategies that could be used to prevent or treat bone de-fects and bone diseases.

The regulatory role of m^(6)A modification in the maintenance and differentiation of embryonic stem cells

As the most prevalent and reversible internal epigenetic modification in eukaryotic mRNAs,N6-methyladenosine(m^(6)A)post-transcriptionally regulates the processing and metabolism of mRNAs involved in diverse biological processes.m^(6)A modification is regulated by m^(6)A writers,erasers,and readers.Emerging evidence suggests that m^(6)A modification plays essential roles in modulating the cell-fate transition of embryonic stem cells.Mechanistic investigation of embryonic stem cell maintenance and differentiation is critical for understanding early embryonic development,which is also the premise for the application of embryonic stem cells in regenerative medicine.This review highlights the current knowledge of m^(6)A modification and its essential regulatory contribution to the cell fate transition of mouse and human embryonic stem cells.

RNA m^(6)A甲基化修饰参与及调控骨科相关疾病

背景:随着高通量测序技术的发展,研究发现骨髓间充质干细胞、成骨细胞、脂肪细胞、破骨细胞、软骨细胞和骨肉瘤细胞等均可检测到m^(6)A修饰的存在,m^(6)A修饰可通过调控细胞RNA水平的甲基化,影响相关基因的mRNA和(或)非编码RNA的翻译等过程,从而激活细胞信号转导通路,影响细胞的增殖、分化、迁移、侵袭、凋亡及DNA损伤修复等,进而调控骨骼发育、关节退变、骨折愈合及骨肿瘤的发生、发展等生理病理过程。目的:总结近年来m^(6)A修饰在骨质疏松症、骨关节炎等骨科疾病中的最新研究成果和作用机制,为开发骨科相关疾病的新型治疗策略提供启发。方法:以中文关键词“N6-甲基腺嘌呤,骨质疏松症,骨关节炎,骨科疾病”检索CNKI数据库,以英文关键词“m^(6)A,osteoporosis,osteoarthritis,orthopedic disease”检索PubMed数据库,全网检索自建库至2020年6月有关m^(6)A修饰在骨科疾病中研究成果的文献,严格按照纳入和排除标准筛选,最后选定61篇文献进行综述。结果与结论:①在骨质疏松症进展过程中,METTL3/m^(6)A介导的RNA甲基化以及FTO/m^(6)A介导的RNA去甲基化动态调控相关基因的表达,进一步影响相关信号通路的激活,影响骨髓间充质干细胞的成骨及成脂分化;②METTL3/m^(6)A通过调节软骨细胞中的核因子κB信号传导和细胞外基质合成,在骨关节炎进展中“扮演”了重要的角色;③METTL3/m^(6)A通过靶向调控成骨细胞相关的miR-7212-5p来抑制骨折愈合过程中的成骨机制;④METTL3通过调节淋巴增强因子1的m^(6)A水平从而激活Wnt/β-catenin信号以及通过调节ATAD2基因的m^(6)A甲基化来加速骨肉瘤的恶化;⑤在骨质疏松症、骨关节炎等骨科疾病中,m^(6)A修饰均参与了多系统疾病的进程,m^(6)A修饰的深入研究为进一步了解骨科相关疾病的发病机制提供了理论依据,并提供了基于表观遗传学基础的骨科疾病治疗思路以及参考依据。

Ferroptosis:a critical mechanism of N^(6)-methyladenosine modification involved in carcinogenesis and tumor progression

Ferroptosis is an iron-dependent regulatory cell necrosis induced by iron overload and lipid peroxidation.It occurs when multiple redoxactive enzymes are ectopically expressed or show abnormal function.Hence,the precise regulation of ferroptosis-related molecules is mediated across multiple levels,including transcriptional,posttranscriptional,translational,and epigenetic levels.N^(6)-methyladenosine(m^(6)A)is a highly evolutionarily conserved epigenetic modification in mammals.The m^(6)A modification is commonly linked to tumor proliferation,progression,and therapy resistance because it is involved in RNA metabolic processes.Intriguingly,accumulating evidence suggests that dysregulated ferroptosis caused by the m^(6)A modification drives tumor development.In this review,we summarized the roles of m^(6)A regulators in ferroptosis-mediated malignant tumor progression and outlined the m^(6)A regulatory mechanism involved in ferroptosis pathways.We also analyzed the potential value and application strategies of targeting m^(6)A/ferroptosis pathway in the clinical diagnosis and therapy of tumors.

The landscape of epigenetic regulation and therapeutic application of N^(6)-methyladenosine modifications in non-coding RNAs

RNA N^(6)-methyladenosine(m^(6)A)methylation is the most abundant and conserved RNA modification in eukaryotes.It participates in the regulation of RNA metabolism and various pathophysiological processes.Non-coding RNAs(ncRNAs)are defined as small or long transcripts which do not encode proteins and display numerous biological regulatory functions.Similar to mRNAs,m^(6)A deposition is observed in ncRNAs.Studying RNA m^(6)A modifications on ncRNAs is of great importance specifically to deepen our understanding of their biological roles and clinical implications.In this review,we summarized the recent research findings regarding the mutual regulation between RNA m^(6)A modification and ncRNAs(with a specific focus on microRNAs,long non-coding RNAs,and circular RNAs)and their functions.We also discussed the challenges of m^(6)A-containing ncRNAs and RNA m^(6)A as therapeutic targets in human diseases and their future perspective in translational roles.

m^(6)A mRNA modification potentiates Th17 functions to inflame autoimmunity

N6-methyladenosine(m^(6)A),the most common and abundant epigenetic RNA modification,governs mRNA metabolism to determine cell differentiation,proliferation and response to stimulation.m^(6)A methyltransferase METTL3 has been reported to control T cell homeostasis and sustain the suppressive function of regulatory T cells(Tregs).However,the role of m^(6)A methyltransferase in other subtypes of T cells remains unknown.T helper cells 17(Th17)play a pivotal role in host defense and autoimmunity.Here,we found that the loss of METTL3 in T cells caused serious defect of Th17 cell differentiation,and impeded the development of experimental autoimmune encephalomyelitis(EAE).We generated Mettl3f/fIl17aCre mice and observed that METTL3 deficiency in Th17 cells significantly suppressed the development of EAE and displayed less Th17 cell infiltration into central nervous system(CNS).Importantly,we demonstrated that depletion of METTL3 attenuated IL-17A and CCR5 expression by facilitating SOCS3 mRNA stability in Th17 cells,leading to disrupted Th17 cell differentiation and infiltration,and eventually attenuating the process of EAE.Collectively,our results highlight that m^(6)A modification sustains Th17 cell function,which provides new insights into the regulatory network of Th17 cells,and also implies a potential therapeutic target for Th17 cell mediated autoimmune disease.

The crucial roles of m^(6)A RNA modifications in cutaneous cancers:Implications in pathogenesis,metastasis,drug resistance,and targeted therapies

N6-methyladenosine(m^(6)A)is the most abundant internal modification on RNA.It is a dynamical and reversible process,which is regulated by m^(6)A methyltransferase and m^(6)A demethylase.The m^(6)A modified RNA can be specifically recognized by the m^(6)A reader,leading to RNA splicing,maturation,degradation or translation.The abnormality of m^(6)A RNA modification is closely related to a variety of biological processes,especially the occurrence and development of tumors.Recent studies have shown that m^(6)A RNA modification is involved in the pathogenesis of skin cancers.However,the precise molecular mechanisms of m^(6)A-mediated cutaneous tumorigenesis have not been fully elucidated.Therefore,this review will summarize the biological characteristics of m^(6)A modification,its regulatory role and mechanism in skin cancers,and the recent research progress of m^(6)A-related molecular drugs,aiming to provide new ideas for clinical diagnosis and targeted therapy of cutaneous cancers.

Decoding m^(6)A mRNA methylation by reader proteins in liver diseases

N6-methyladenosine(m^(6)A)is a dynamic and reversible epigenetic regulation.As the most prevalent internal post-transcriptional modification in eukaryotic RNA,it participates in the regulation of gene expression through various mechanisms,such as mRNA splicing,nuclear export,localization,translation efficiency,mRNA stability,and structural transformation.The involvement of m^(6)A in the regulation of gene expression depends on the specific recognition of m^(6)A-modified RNA by reader proteins.In the pathogenesis and treatment of liver disease,studies have found that the expression levels of key genes that promote or inhibit the development of liver disease are regulated by m^(6)A modification,in which abnormal expression of reader proteins determines the fate of these gene transcripts.In this review,we introduce m^(6)A readers,summarize the recognition and regulatory mechanisms of m^(6)A readers on mRNA,and focus on the biological functions and mechanisms of m^(6)A readers in liver cancer,viral hepatitis,non-alcoholic fatty liver disease(NAFLD),hepatic fibrosis(HF),acute liver injury(ALI),and other liver diseases.This information is expected to be of high value to researchers deciphering the links between m^(6)A readers and human liver diseases.

The RNA m^(6)A demethylase ALKBH5 drives emergency granulopoiesis and neutrophil mobilization by upregulating G-CSFR expression

Emergency granulopoiesis and neutrophil mobilization that can be triggered by granulocyte colony-stimulating factor(G-CSF)through its receptor G-CSFR are essential for antibacterial innate defense.However,the epigenetic modifiers crucial for intrinsically regulating G-CSFR expression and the antibacterial response of neutrophils remain largely unclear.N6-methyladenosine(m^(6)A)RNA modification and the related demethylase alkB homolog 5(ALKBH5)are key epigenetic regulators of immunity and inflammation,but their roles in neutrophil production and mobilization are still unknown.We used cecal ligation and puncture(CLP)-induced polymicrobial sepsis to model systemic bacterial infection,and we report that ALKBH5 is required for emergency granulopoiesis and neutrophil mobilization.ALKBH5 depletion significantly impaired the production of immature neutrophils in the bone marrow of septic mice.In addition,Alkbh5-deficient septic mice exhibited higher retention of mature neutrophils in the bone marrow and defective neutrophil release into the circulation,which led to fewer neutrophils at the infection site than in their wild-type littermates.During bacterial infection,ALKBH5 imprinted production-and mobilization-promoting transcriptome signatures in both mouse and human neutrophils.Mechanistically,ALKBH5 erased m^(6)A methylation on the CSF3R mRNA to increase the mRNA stability and protein expression of G-CSFR,consequently upregulating cell surface G-CSFR expression and downstream STAT3 signaling in neutrophils.The RIP-qPCR results confirmed the direct binding of ALKBH5 to the CSF3R mRNA,and the binding strength declined upon bacterial infection,accounting for the decrease in G-CSFR expression on bacteria-infected neutrophils.Considering these results collectively,we define a new role of ALKBH5 in intrinsically driving neutrophil production and mobilization through m^(6)A demethylation-dependent posttranscriptional regulation,indicating that m^(6)A RNA modification in neutrophils is a potential target for treating bacterial infections and neutropenia.

Detection,regulation,and functions of RNA N^(6)-methyladenosine modification in plants

N6-Methyladenosine(m^(6)A)is the most abundant internal chemical modification in eukaryotic mRNA and plays important roles in gene expression regulation,including transcriptional and post-transcriptional regulation.m^(6)A is a reversible modification that is installed,removed,and recognized by methyltransferases(writers),demethylases(erasers),and m^(6)A-binding proteins(readers),respectively.Recently,the breadth of research on m^(6)A in plants has expanded,and the vital roles of m^(6)A in plant development,biotic and abiotic stress responses,and crop trait improvement have been investigated.In this review,we discuss recent developments in research on m^(6)A and highlight the detection methods,distribution,regulatory proteins,and molecular and biological functions of m^(6)A in plants.We also offer some perspectives on future investigations,providing direction for subsequent research on m^(6)A in plants.

Multilevel regulation of N^(6)-methyladenosine RNA modifications: Implications in tumorigenesis and therapeutic opportunities

N^(6)-methyladenosine(m^(6)A)RNA modification is widely perceived as the most abundant and common modification in transcripts.This modification is dynamically regulated by specific m^(6)A“writers”,“erasers”and“readers”and is reportedly involved in the occurrence and development of many diseases.Since m^(6)A RNA modification was discovered in the 1970s,with the progress of relevant research technologies,an increasing number of functions of m^(6)A have been reported,and a preliminary understanding of m^(6)A has been obtained.In this review,we summarize the mechanisms through which m^(6)A RNA modification is regulated from the perspectives of expression,posttranslational modification and protein interaction.In addition,we also summarize how external and internal environmental factors affect m^(6)A RNA modification and its functions in tumors.The mechanisms through which m^(6)A methylases,m^(6)A demethylases and m^(6)A-binding proteins are regulated are complicated and have not been fully elucidated.Therefore,we hope to promote further research in this field by summarizing these mechanisms and look forward to the future application of m^(6)A in tumors.

Emerging Regulatory Mechanisms of N6-Methyladenosine Modification in Cancer Metastasis

Cancer metastasis is the major cause of cancer-related deaths and accounts for poor therapeutic outcomes.A metastatic cas-cade is a series of complicated biological processes.N6-methyladenosine(m^(6)A)is the most abundant and conserved epi-transcriptomic modification in eukaryotic cells,which has great impacts on RNA production and metabolism,including RNA splicing,processing,degradation and translation.Accumulating evidence demonstrates that m^(6)A plays a critical role in regulating cancer metastasis.However,there is a lack of studies that review the recent advances of m^(6)A in cancer metastasis.Here,we systematically retrieved the functions and mechanisms of how the m^(6)A axis regulates metastasis,and especially summarized the organ-specific liver,lung and brain metastasis mediated by m^(6)A in various cancers.Moreover,we discussed the potential application of m^(6)A modification in cancer diagnosis and therapy,as well as the present limitations and future perspectives of m^(6)A in cancer metastasis.This review provides a comprehensive knowledge on the m^(6)A-mediated regulation of gene expression,which is helpful to extensively understand the complexity of cancer metastasis from a new epitranscriptomic point of view and shed light on the developing novel strategies to anti-metastasis based on m^(6)A alteration.

RNA m^6A modification and its function in diseases

N^6-methyladenosine （m^6A） is the most common post-transcriptional RNA modification throughout the transcriptome, affecting fundamental aspects of RNA metabolism, m^6A modification could be installed by m^6A ＂writers＂ composed of core catalytic components （METTL3/METTL14/WTAP） and newly defined regulators and removed by m^6A ＂erasers＂ （FTO and ALKBH5）. The function of m^6A is executed by m^6A ＂readers＂ that bind to m^6A directly （YTH domain-containing proteins, eIF3 and IGF2BPs） or indirectly （HNRNPA2B1）. In the past few years, advances in m^6A modulators （＂writers,＂ ＂erasers,＂ and ＂readers＂） have remarkably renewed our understanding of the function and regulation of m^6A in different cells under normal or disease conditions. However, the mechanism and the regulatory network of m^6A are still largely unknown. Moreover, investigations of the m^6A physiological roles in human diseases are limited. In this review, we summarize the recent advances in m^6A research and highlight the functional relevance and importance of m^6A modification in in vitro cell lines, in physiological contexts, and in cancers.

Structural Insights into N^6-methyladenosine (m^6A) Modification in the Transcriptome

More than 100 types of chemical modifications in RNA have been well documented. Recently, several modifications, such as N6-methyladenosine （m^6A）, have been detected in mRNA, opening the window into the realm of epitranscriptomies. The m^6A modification is the most abundant modification in mRNA and non-coding RNA （ncRNA）. At the molecular level, m^6A affects almost all aspects of mRNA metabolism, including splicing, translation, and stability, as well as microRNA （miRNA） maturation, playing essential roles in a range of cellular processes. The m^6A modification is regulated by three classes of proteins generally referred to as the ＂writer＂ （adenosine methyltransferase）, ＂eraser＂ （m^6A demethylating enzyme）, and ＂reader＂ （m^6A-binding protein）. The m^6A modification is reversibly installed and removed by writers and erasers, respectively. Readers, which are members of the YT521-B homology （YTH） family proteins, selectively bind to RNA and affect its fate in an m^6A-dependent manner. In this review, we summarize the structures of the functional proteins that modulate the m^6A modification, and provide our insights into the m^6A-mediated gene regulation.

CPSF30-L-mediated recognition of mRNA m^(6)A modification controls alternative polyadenylation of nitrate signaling-related gene transcripts in Arabidopsis

N6-methyladenosine(m^(6)A),a ubiquitous internal modification of eukaryotic mRNAs,plays a vital role in almost every aspect of mRNA metabolism.However,there is little evidence documenting the role of m^(6)A in regulating alternative polyadenylation(APA)in plants.APA is controlled by a large protein-RNA complex with many components,including CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR30(CPSF30).In Arabidopsis,CPSF30 has two isoforms and the longer isoform(CPSF30-L)contains a YT512-B Homology(YTH)domain,which is unique to plants.In this study,we showed that CPSF30-L YTH domain binds to m^(6)A in v itro.In the cpsf30-2 mutant,the transcripts of many genes including several important nitrate signaling-related genes had shifts in polyadenylation sites that were correlated with m^(6)A peaks,indicating that these gene transcripts carrying m^(6)A tend to be regulated by APA.Wild-type CPSF30-L could rescue the defects in APA and nitrate metabolism in cpsf30-2,but m^(6)A-binding-defective mutants of CPSF30-L could not.Taken together,our results demonstrated that m^(6)A modification regulates APA in Arabidops is and revealed that the m^(6)A reader CPSF30-L affects nitrate signaling by controlling APA,shedding new light on the roles of the m^(6)A modification during RNA 3-end processing in nitrate metabolism.

RNA m^(6) A modification: Mapping methods, roles, and mechanisms in acute myeloid leukemia

N^(6)-Methyladenosine(m^(6)A)is the most abundant modification in eukaryotic mRNA,and plays important biological functions via regulating RNA fate determination.Recent studies have shown that m^(6)A modification plays a key role in hematologic malignancies,including acute myeloid leukemia.The current growth of epitranscriptomic research mainly benefits from technological progress in detecting RNA m^(6)A modification in a transcriptome-wide manner.In this review,we first briefly summarize the latest advances in RNA m^(6)A biology by focusing on writers,readers,and erasers of m^(6)A modification,and describe the development of high-throughput methods for RNA m^(6)A mapping.We further discuss the important roles of m^(6)A modifiers in acute myeloid leukemia,and highlight the identification of potential inhibitors for AML treatment by targeting of m^(6)A modifiers.Overall,this review provides a comprehensive summary of RNA m^(6)A biology in acute myeloid leukemia.