Epigenetic modifications and metabolic memory in diabetic retinopathy:beyond the surface

Epigenetics focuses on DNA methylation,histone modification,chromatin remodeling,noncoding RNAs,and other gene regulation mechanisms beyond the DNA sequence.In the past decade,epigenetic modifications have drawn more attention as they participate in the development and progression of diabetic retinopathy despite tight control of glucose levels.The underlying mechanisms of epigenetic modifications in diabetic retinopathy still urgently need to be elucidated.The diabetic condition facilitates epigenetic changes and influences target gene expression.In this review,we summarize the involvement of epigenetic modifications and metabolic memory in the development and progression of diabetic retinopathy and propose novel insights into the treatment of diabetic retinopathy.

Recent progress in N6-methyladenosine modification in ocular surface diseases

N6-methyladenosine(m6A)modification is a reversible process promoted by“writers”,inhibited by“erasers”,and processed by“readers”.During the last decade,increasing emphasis has been placed on the underlying roles of m6A modification owing to their great importance in biological significance.The abnormal regulation of m6A modification will lead to aberrant cellular behavior and various diseases.Recently,studies have demonstrated that m6A modification is closely associated with the genesis and progression of ocular surface diseases(OSDs).This review focus on the role of m6A modification and research progress in OSDs including fungal keratitis,herpes simplex keratitis,immunerelated keratoconjunctival diseases,pterygium,ocular chemical burns,and Graves’ophthalmopathy,which may provide new insights into and prospective applications for OSDs.

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.

Effect of demethyltransferase FTO on tumor progression

N6-methyladenosine(m6A)modification is the most widespread and conserved internal mRNA modification in mammalian cells.It greatly affects genetic regulation by enhancing the involvement of diverse cellular enzymes and thus,plays a significant role in basic life processes.Numerous studies on m6A modification identified FTO as a crucial demethylase that participates in various biological processes.Not only does FTO play a pivotal role in obesity-related conditions,but it also influences the occurrence,development,and prognosis of several cancers,such as acute myeloid leukemia,breast cancer,liver cancer,and lung cancer.Moreover,FTO also shows a close association with immunity and viral infections.This article summarized the molecular mechanism of FTO in tumorigenesis and tumor progression.

Emerging applications of catalytically inactive CRISPR-Cas13 system in mRNA engineering

Posttranscriptional regulations of different types of RNA,including rRNA,tRNA,mRNA and ncRNA are widely involved in normal physiology and diseases.m RNA,as the intermediary product between gene and protein,whose posttranscriptional regulations such as alternative splicing,alternative polyadenylation and modifications impact its coded protein expression and functions.However,the functional significance and therapeutic potential of RNA posttranscriptional regulations are not well studied due to the lack of suitable RNA engineering platforms.The discovery of a novel CRISPR-Cas system termed CRISPR-Cas13 in 2015 that specifically targets RNA templates brought a new role to CRISPR to target and edit RNA with high specificity,which opened a new era of RNA manipulations to some degree.This review will summarize the emerging applications of the catalytically inactive CRISPR-Cas13 system(CRISPR-dCas13)in mRNA engineering and highlight the prospection of the CRISPR-dCas13 system for other RNA modification regulations and its therapeutic potential.

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.

Targeting m6A modification inhibits herpes virus 1 infection

The latent infection by herpes virus type 1(HSV-1)may be lifelong in trigeminal ganglia and a suspected cause of Alzheimer's Disease(AD)and Amyotrophic lateral sclerosis(ALS).Whether and how N6-methyladenosine(m6A)modification of viral RNAs affects virus infection are poorly understood.Here,we report that HSV-1 infection enhanced the expression of m6A writers(METTL3,METTL14)and readers(YTHDF1/2/3)at the early infection stage and decreased their expression later on,while suppressed the erasers'(FTO,ALBKH5)expression immediately upon infection to facilitate viral replication.Inhibiting m6A modification by 3-deazaadenosine(DAA)significantly decreased viral replication and reduced viral reproduction over 1000 folds.More interestingly,depleting the writers and readers by siRNAs inhibited virus replication and reproduction;whereas depleting the erasers promoted viral replication and reproduction.Silencing YTHDF3 strikingly decreased viral replication by up to 90%,leading to reduction of up to 10-fold viral replication and over 100-fold virus reproduction,respectively.Depletion of m6A initiator METTL3(by 60%–70%)by siRNA correlatedly decreased viral replication 60%–70%,and reduced virus yield over 30-fold.Consistently,ectopic expression of METTL3 largely increased virus yield.METTL3 knockdown suppressed the HSV-1 intermediate early and early genes(ICP0,ICP8 and UL23)and late genes(VP16,UL44,UL49 and ICP47);while ectopic expression of METTL3 upregulated these gene expression.Results from our study shed the lights on the importance for m6A modification to initiate HSV-1 early replication.The components of m6A modification machinery,particularly m6A initiator METTL3 and reader YTHDF3,would be potential important targets for combating HSV-1 infections.

Dysregulation and implications of N6-methyladenosine modification in renal cell carcinoma

Increasing evidence indicates that N6-methyladenosine(m6A)methylation modification serves important functions in biological metabolism.Dysregulation of m6A regulators is related to the progression of different malignancies,including renal cell carcinoma(RCC).Recent studies have reported preliminary findings on the influence of m6A regulator dysregulation on RCC tumorigenesis and development.However,no comprehensive review that integrates and analyzes the roles of m6A modification in RCC has been published to date.In this review,we focus on the dysregulation of m6A regulators as it relates to RCC tumorigenesis and development,as well as possible applications of m6A modification in RCC diagnosis and therapeutics.

Studies on the fat mass and obesity-associated(FTO)gene and its impact on obesity-associated diseases

Obesity has become a major health crisis in the past∼50 years.The fat mass and obesity-associated(FTO)gene,identified by genome-wide association studies(GWAS),was first reported to be positively associated with obesity in humans.Mice with more copies of the FTO gene were observed to be obese,while loss of the gene in mice was found to protect from obesity.Later,FTO was found to encode an m6 A RNA demethylase and has a profound effect on many biological and metabolic processes.In this review,we first summarize recent studies that demonstrate the critical roles and regulatory mechanisms of FTO in obesity and metabolic disease.Second,we discuss the ongoing debates concerning the association between FTO polymorphisms and obesity.Third,since several small molecule drugs and micronutrients have been found to regulate metabolic homeostasis through controlling the expression or activity of FTO,we highlight the broad potential of targeting FTO for obesity treatment.Improving our understanding of FTO and the underlying mechanisms may provide new approaches for treating obesity and metabolic diseases.

The FTO/miR-181b-3p/ARL5B signaling pathway regulates cell migration and invasion in breast cancer

Background:N6-methyladenosine(m6A)RNA modification has been demonstrated to be a significant regulatory process in the progression of various tumors,including breast cancer.Fat mass and obesity-associated(FTO)enzyme,initially known as the obesity-related protein,is the first identified m6A demethylase.However,the relationship between FTO and breast cancer remains controversial.In this study,we aimed to elucidate the role and clinical significance of FTO in breast cancer and to explore the underlying mechanism.Methods:We first investigated the expression of FTO in breast cancer cell lines and tissues by quantitative reverse transcription-PCR(qRT-PCR),Western blotting,and immunohistochemistry.Wound healing assay and Transwell assay were performed to determine the migration and invasion abilities of SKBR3 and MDAMB453 cells with either knockdown or overexpression of FTO.RNA sequencing(RNA-seq)was conducted to decipher the downstream targets of FTO.qRT-PCR,luciferase reporter assay,and Western blotting were employed to confirm the existence of the FTO/miR-181b-3p/ARL5B axis.The biological function of ADP ribosylation factor like GTPase 5B(ARL5B)in breast cancer cells was evaluated by wound healing assay and Transwell invasion assay.Results:High FTO expression was observed in human epidermal growth factor receptor 2(HER2)-positive breast cancer,predicting advanced progression(tumor size[P<0.001],nuclear grade[P=0.001],peritumoral lymphovascular invasion[P<0.001),lymph node metastasis[P=0.002],and TNM stage[P=0.001])and poor prognosis.Moreover,FTO promoted cell invasion and migration in vitro.Mechanistically,RNA-seq and further confirmation studies suggested that FTO up-regulated ARL5B by inhibiting miR-181b-3p.We further verified that ARL5B also displayed carcinogenic activity in breast cancer cells.Conclusion:Our work demonstrated the carcinogenic activity of FTO in promoting the invasion and migration of breast cancer cells via the FTO/miR-181b-3p/ARL5B signaling pathway.