Genetic drivers of m6A methylation in human brain, lung, heart and muscle

The landscape of N6-methyladenosine in localized primary prostate cancer

N6-methyladenosine (m6A), the most abundant internal RNA modification in humans, regulates most aspects of RNA processing. Prostate cancer is characterized by widespread transcriptomic dysregulation; therefore, we characterized the m6A landscape of 162 localized prostate tumors with matched DNA, RNA and protein profiling. m6A abundance varied dramatically across tumors, with global patterns emerging via complex germline-somatic cooperative regulation. Individual germline polymorphisms regulated m6A abundance, cooperating with somatic mutation of cancer driver genes and m6A regulators. The resulting complex patterns were associated with prognostic clinical features and established the biomarker potential of global and locus-specific m6A patterns. Tumor hypoxia dysregulates m6A profiles, bridging prior genomic and proteomic observations. Specific m6A sites, such as those in VCAN, drive disease aggression, associating with poor outcomes, tumor growth and metastasis. m6A dysregulation is thus associated with key events in the natural history of prostate cancer: germline risk, microenvironmental dysregulation, somatic mutation and metastasis.

Rewired m6A methylation of promoter antisense RNAs in Alzheimer's disease regulates global gene transcription in the 3D nucleome

N6-methyladenosine (m6A) is the most prevalent internal RNA modification that can impact mRNA expression post-transcriptionally. Recent progress indicates that m6A also acts on nuclear or chromatin-associated RNAs to impact transcriptional and epigenetic processes. However, the landscapes and functional roles of m6A in human brains and neurodegenerative diseases, including Alzheimer's disease (AD), have been under-explored. Here, we examined RNA m6A methylome using total RNA-seq and meRIP-seq in middle frontal cortex tissues of post-mortem human brains from individuals with AD and age-matched counterparts. Our results revealed AD-associated alteration of m6A methylation on both mRNAs and various noncoding RNAs. Notably, a series of promoter antisense RNAs (paRNAs) displayed cell-type-specific expression and changes in AD, including one produced adjacent to the MAPT locus that encodes the Tau protein. We found that MAPT-paRNA is enriched in neurons, and m6A positively controls its expression. In iPSC-derived human excitatory neurons, MAPT-paRNA promotes expression of hundreds of genes related to neuronal and synaptic functions, including a key AD resilience gene MEF2C, and plays a neuroprotective role against excitotoxicity. By examining RNA-DNA interactome in the three-dimensional (3D) nuclei of human brains, we demonstrated that brain paRNAs can interact with both cis- and trans-chromosomal target genes to impact their transcription. These data together reveal previously unexplored landscapes and functions of noncoding RNAs and m6A methylome in brain gene regulation, neuronal survival and AD pathogenesis.

Allele-specific methylation of SSTR4 associated with aging and cognitive functions in patients with schizophrenia

The co-occurrence of alcohol use disorder (AUD) and schizophrenia is prevalent, with a rate of 33.7%. Previous research has suggested a genetic and epigenetic overlap between these two disorders. SSTR4, a member of the somatostatin receptor family, is implicated in various neurological and psychiatric conditions, including cognitive function, AUD, and schizophrenia. However, the role of genetic-epigenetic interactions involving SSTR4 in patients with schizophrenia remains unexplored. In this study, we conducted an integration of publicly available datasets and identified allele-specific methylation patterns in SSTR4. Additionally, we pinpointed several genetic variants (rs17691954, rs11464356, rs3109190, and rs145879288) that influence the pace of aging and cognitive functions (rs705935) through their quantitative trait loci effects on CpG sites within SSTR4.

Novel Insight of N6-Methyladenosine in Cardiovascular System

N6-methyladenosine (m6A) is the most common and abundant internal co-transcriptional modification in eukaryotic RNAs. This modification is catalyzed by m6A methyltransferases, known as "writers", including METTL3/14 and WTAP, and removed by demethylases, or "erasers", such as FTO and ALKBH5. It is recognized by m6A-binding proteins, or "readers", such as YTHDF1/2/3, YTHDC1/2, IGF2BP1/2/3, and HNRNPA2B1. Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Recent studies indicate that m6A RNA modification plays a critical role in both the physiological and pathological processes involved in the initiation and progression of CVDs. In this review, we will explore how m6A RNA methylation impacts both the normal and disease states of the cardiovascular system. Our focus will be on recent advancements in understanding the biological functions, molecular mechanisms, and regulatory factors of m6A RNA methylation, along with its downstream target genes in various CVDs, such as atherosclerosis, ischemic diseases, metabolic disorders, and heart failure. We propose that the m6A RNA methylation pathway holds promise as a potential therapeutic target in cardiovascular disease.

Epigenetic modifications and emerging therapeutic targets in cardiovascular aging and diseases

The complex mechanisms underlying the development of cardiovascular diseases remain not fully elucidated. Epigenetics, which modulates gene expression without DNA sequence changes, is shedding light on these mechanisms and their heritable effects. This review focus on epigenetic regulation in cardiovascular aging and diseases, detailing specific epigenetic enzymes such as DNA methyltransferases (DNMTs), histone acetyltransferases (HATs), and histone deacetylases (HDACs), which serve as writers or erasers that modify the epigenetic landscape. We also discuss the readers of these modifications, such as the 5-methylcytosine binding domain proteins, and the erasers ten-eleven translocation (TET) proteins. The emerging role of RNA methylation, particularly N6-methyladenosine (m6A), in cardiovascular pathogenesis is also discussed. We summarize potential therapeutic targets, such as key enzymes and their inhibitors, including DNMT inhibitors like 5-azacytidine and decitabine, HDAC inhibitors like belinostat and givinotide, some of which have been approved by the FDA for various malignancies, suggesting their potential in treating cardiovascular diseases. Furthermore, we highlight the role of novel histone modifications and their associated enzymes, which are emerging as potential therapeutic targets in cardiovascular diseases. Thus, by incorporating the recent studies involving patients with cardiovascular aging and diseases, we aim to provide a more detailed and updated review that reflects the advancements in the field of epigenetic modification in cardiovascular diseases.

Altered m6A RNA methylation profiles in depression implicate the dysregulation of discrete cellular functions in males and females

Adverse environmental stress represents a significant risk factor for major depressive disorder (MDD), often resulting in disrupted synaptic connectivity which is known to be partly regulated by epigenetic mechanisms. N6-methyladenosine (m6A), an epitranscriptomic modification, has emerged as a crucial regulator of activity-dependent gene regulation. In this study, we characterized m6A profiles in the ventromedial prefrontal cortex (vmPFC) of individuals with MDD. Using m6A sequencing, we identified a total of 30,279 high-confidence m6A peaks, exhibiting significant enrichment in genes related to neuronal and synaptic function. The m6A peaks between males and females with MDD that passed the significance threshold showed opposite m6A patterns, while the threshold-free m6A patterns were concordant. Distinct m6A profiles were found in MDD for each sex, with dysregulation associated with microtubule movement in males and neuronal projection in females. Our results suggest the potential roles of m6A as part of the dysregulated molecular network in MDD.

Multi-omics integration analysis reveals the role of N6-methyladenosine in lncRNA translation during glioma stem cell differentiation

Glioblastoma is one of the most lethal brain diseases in humans. Although recent studies have shown reciprocal interactions between N6-methyladenosine (m6A) modifications and long noncoding RNAs (lncRNAs) in gliomagenesis and malignant progression, the mechanism of m6A-mediated lncRNA translational regulation in glioblastoma remains unclear. Herein, we profiled the transcriptomes, translatomes, and epitranscriptomics of glioma stem cells and differentiated glioma cells to investigate the role of m6A in lncRNA translation comprehensively. We found that lncRNAs with numerous m6A peaks exhibit reduced translation efficiency. Transcript-level expression analysis demonstrates an enrichment of m6A around short open reading frames (sORFs) of translatable lncRNA transcripts. Further comparison analysis of m6A modifications in different RNA regions indicates that m6A peaks downstream of sORFs inhibit lncRNA translation more than those upstream. Observations in glioma-associated lncRNAs H19, LINC00467, and GAS5 further confirm the negative effect of m6A methylation on lncRNA translation. Overall, these findings elucidate the dynamic profiles of the m6A methylome and enhance the understanding of the complexity of lncRNA translational regulation.

Severe fever with thrombocytopenia syndrome virus induces lactylation of m6A reader protein YTHDF1 to facilitate viral replication

Severe fever with thrombocytopenia syndrome virus (SFTSV), an emerging infectious pathogen with a high fatality rate, is an enveloped tripartite segmented single-stranded negative-sense RNA virus. SFTSV infection is characterized by suppressed host innate immunity, proinflammatory cytokine storm, failure of B-cell immunity, and robust viral replication. m6A modification has been shown to play a role in viral infections. However, interactions between m6A modification and SFTSV infection remain poorly understood. Through MeRIP-seq, we identify m6A modifications on SFTSV RNA. We show that YTHDF1 can bind to m6A modification sites on SFTSV, decreasing the stability of SFTSV RNA and reducing the translation efficiency of SFTSV proteins. The SFTSV virulence factor NSs increases lactylation of YTHDF1 and YTHDF1 degradation, thus facilitating SFTSV replication. Our findings indicate that the SFTSV protein NSs induce lactylation to inhibit YTHDF1 as a countermeasure to host's YTHDF1-mediated degradation of m6A-marked viral mRNAs.

Genome-wide identification of cell type-specific susceptibility genes for Juvenile dermatomyositis through the analysis of N6-methyladenosine-associated SNPs

Genome-wide association studies (GWASs) have pinpointed genetic loci associated with juvenile dermatomyositis (JDM). Functional genes within the GWAS loci may be cell type-specific, but their identity remains largely unknown. N6-methyladenosine (m6A) plays a pivotal role in regulating various cellular processes and is linked to autoimmune diseases. This study aimed to underscore the potential functional genes within the GWAS loci through the analysis of m6A-associated SNPs (m6A-SNPs), specifically within relevant cell types. JDM-associated m6A-SNPs were identified from the GWAS summary dataset. The correlation between m6A-SNPs and gene expression was assessed through bulk tissue and single-cell eQTL analyses. To further investigate the relationship between gene expression and JDM, Mendelian randomization analysis was employed. Additionally, differential expression analyses were conducted on bulk tissues, as well as single-cell transcriptomic data comprising 6 JDM patients and 11 juvenile controls (99,396 cells). Seven m6A-SNPs associated with JDM were identified. Bulk tissue analysis revealed differential expression of HLA-DPA1, HLA-DPB1, MICB, HLA-A, HLA-F, HLA-DQB2, HLA-DRB5, TAP2, PSMB9, MICA, AIF1, and DDX39B influenced by m6A-SNPs, all showing associations with JDM in both differential expression and Mendelian randomization analyses. In single-cell analysis, the six m6A-SNPs within the HLA locus acted as cell-type-specific eQTLs, correlating with the expression of HLA-A, HLA-B, HLA-C, HLA-DPB1, HLA-DQA1, HLA-DQB1 and HLA-DRB1 in myeloid, T or B cells. Notably, these genes displayed abnormal expression in T, B, and myeloid cells of JDM patients. The present study identified m6A-SNPs within JDM susceptibility genes, shedding light on the intricate interplay between m6A-SNPs, gene expression, and JDM.

N6-methyladenosine RNA modification promotes Severe Fever with Thrombocytopenia Syndrome Virus infection

Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV), a novel bunyavirus primarily transmitted by Haemaphysalis longicornis, induces severe disease with a high mortality rate. N6-methyladenosine (m6A) is a prevalent internal chemical modification in eukaryotic mRNA that has been reported to regulate viral infection. However, the role of m6A modification during SFTSV infection remains elusive. We here reported that SFTSV RNAs bear m6A modification during infection. Manipulating the expressions or activities of host m6A regulators significantly impacted SFTSV infection. Mechanistically, SFTSV recruited m6A regulators through the nucleoprotein to modulate the m6A modification of viral RNA, eventually resulting in enhanced infection by promoting viral mRNA translation efficiency and/or genome RNA stability. m6A mutations in the S genome diminished virus particle production, while m6A mutations in the G transcript impaired the replication of recombinant vesicular stomatitis virus (rVSV) expressing G protein in vitro and in vivo. Interestingly, m6A modification was evolutionarily conserved and facilitated SFTSV infection in primary tick cells. These findings may open an avenue for the development of m6A-targeted anti-SFTSV vaccines, drugs, and innovative strategies for the prevention and control of tick-borne disease.

Genome-Wide Identification of Cell Type-Specific Susceptibility Genes for SLE Through the Analysis of RNA Modification-Associated SNPs

INTRODUCTION

This study aimed to elucidate the functional genes associated with systemic lupus erythematosus (SLE) in various cell types through the utilization of RNAm-SNPs.

METHODS

Utilizing large-scale genetic data, we identified associations between RNAm-SNPs and SLE. The association between RNAm-SNPs and bulk and single-cell mRNA expression (eQTL) and protein levels (pQTL) were examined. Mendelian randomization and differential expression analyses were conducted to explore the links between gene expression, protein levels, and SLE.

RESULTS

We identified 41 RNAm-SNPs that were significantly associated with SLE. The GWAS signals exhibited notable enrichment in m6A-SNPs and m7G-SNPs. These RNAm-SNPs showed both eQTL and pQTL effects. In our single-cell analysis, 16 RNAm-SNPs exhibited associations with gene expression levels across 13 distinct cell types, including HLA-A, HLA-B, HLA-C, HLA-DQA1, HLA-DQB1, HLA-DRB1 and IRF7. We identified 58 noteworthy associations between the expression levels of 20 genes and SLE across 12 distinct immune cell types. Notably, HLA-DQB1, HLA-DRB1 and IRF7 exhibited abnormalities in CD8+ T cells, IRF7 displayed abnormal expression in CD4+ T cells, while HLA-DRB1 and IRF7 were also distinctly perturbed in natural killer cells.

DISCUSSION

This study advances our understanding of the genetic basis of SLE by highlighting the significance of RNAm-SNPs and immune cell gene expression in SLE.

A compendium of genetic variations associated with promoter usage across 49 human tissues

Promoters play a crucial role in regulating gene transcription. However, our understanding of how genetic variants influence alternative promoter selection is still incomplete. In this study, we implement a framework to identify genetic variants that affect the relative usage of alternative promoters, known as promoter usage quantitative trait loci (puQTLs). By constructing an atlas of human puQTLs across 49 different tissues from 838 individuals, we have identified approximately 76,856 independent loci associated with promoter usage, encompassing 602,009 genetic variants. Our study demonstrates that puQTLs represent a distinct type of molecular quantitative trait loci, effectively uncovering regulatory targets and patterns. Furthermore, puQTLs are regulating in a tissue-specific manner and are enriched with binding sites of epigenetic marks and transcription factors, especially those involved in chromatin architecture formation. Notably, we have also found that puQTLs colocalize with complex traits or diseases and contribute to their heritability. Collectively, our findings underscore the significant role of puQTLs in elucidating the molecular mechanisms underlying tissue development and complex diseases.

Smoking-informed methylation and expression QTLs in human brain and colocalization with smoking-associated genetic loci

Smoking is a leading cause of preventable morbidity and mortality. Smoking is heritable, and genome-wide association studies (GWASs) of smoking behaviors have identified hundreds of significant loci. Most GWAS-identified variants are noncoding with unknown neurobiological effects. We used genome-wide genotype, DNA methylation, and RNA sequencing data in postmortem human nucleus accumbens (NAc) to identify cis-methylation/expression quantitative trait loci (meQTLs/eQTLs), investigate variant-by-cigarette smoking interactions across the genome, and overlay QTL evidence at smoking GWAS-identified loci to evaluate their regulatory potential. Active smokers (N = 52) and nonsmokers (N = 171) were defined based on cotinine biomarker levels and next-of-kin reporting. We simultaneously tested variant and variant-by-smoking interaction effects on methylation and expression, separately, adjusting for biological and technical covariates and correcting for multiple testing using a two-stage procedure. We found >2 million significant meQTL variants (padj < 0.05) corresponding to 41,695 unique CpGs. Results were largely driven by main effects, and five meQTLs, mapping to NUDT12, FAM53B, RNF39, and ADRA1B, showed a significant interaction with smoking. We found 57,683 significant eQTL variants for 958 unique eGenes (padj < 0.05) and no smoking interactions. Colocalization analyses identified loci with smoking-associated GWAS variants that overlapped meQTLs/eQTLs, suggesting that these heritable factors may influence smoking behaviors through functional effects on methylation/expression. One locus containing MUSTN1 and ITIH4 colocalized across all data types (GWAS, meQTL, and eQTL). In this first genome-wide meQTL map in the human NAc, the enriched overlap with smoking GWAS-identified genetic loci provides evidence that gene regulation in the brain helps explain the neurobiology of smoking behaviors.

m6A methyltransferase ZC3H13 improves pulmonary fibrosis in mice through regulating Bax expression

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease. N6-methyladenosine (m6A) is a reversible RNA modification that was shown to be associated with IPF development. The present study aimed to explore the function and potential mechanism of the m6A methylation enzyme zinc finger CCCH-type containing 13 (ZC3H13) in IPF. In the study, bioinformatic screening yielded a differentially expressed m6A gene, ZC3H13, which was down-regulated in GEO microarrays, BLM-induced mouse models, and cellular models. Overexpression of ZC3H13 reduced histopathological damage of lung tissues in mice, mitigated fibrosis (including reduced α-SMA, collagen Ⅰ, and Vimentin levels, and elevated E-cadherin levels), decreased lung/body weight ratio and lung hydroxyproline levels, reduced oxidative stress (increased SOD activity and GSH-Px activity and decreased MDA levels), suppressed apoptosis within lung tissues and MLE-12 cells, promoted Bcl-2 expression, and inhibited Bax expression. Bax expression was found to be negatively correlated with ZC3H13 expression by correlation analysis. ZC3H13 could bind Bax mRNA and promote its m6A methylation through reading protein YTHDC1, thereby inhibiting its stability. Bax inhibition ameliorated BLM-induced MLE-12 cell dysfunction and partially abrogated the inhibition of MLE-12 cell function by ZC3H13 downregulation. In conclusion, m6A methyltransferase ZC3H13 impedes lung epithelial cell apoptosis and thus improves pulmonary fibrosis by promoting Bax mRNA m6A methylation and down-regulating Bax expression through reading protein YTHDC1.

Integration of multi-omics summary data reveals the role of N6-methyladenosine in neuropsychiatric disorders

N6-methyladenosine (m6A) methylation regulates gene expression/protein by influencing numerous aspects of mRNA metabolism and contributes to neuropsychiatric diseases. Here, we integrated multi-omics data and genome-wide association study summary data of schizophrenia (SCZ), bipolar disorder (BP), attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), major depressive disorder (MDD), Alzheimer's disease (AD), and Parkinson's disease (PD) to reveal the role of m6A in neuropsychiatric disorders by using transcriptome-wide association study (TWAS) tool and Summary-data-based Mendelian randomization (SMR). Our investigation identified 86 m6A sites associated with seven neuropsychiatric diseases and then revealed 7881 associations between m6A sites and gene expressions. Based on these results, we discovered 916 significant m6A-gene associations involving 82 disease-related m6A sites and 606 genes. Further integrating the 58 disease-related genes from TWAS and SMR analysis, we obtained 61, 8, 7, 3, and 2 associations linking m6A-disease, m6A-gene, and gene-disease for SCZ, BP, AD, MDD, and PD separately. Functional analysis showed the m6A mapped genes were enriched in "response to stimulus" pathway. In addition, we also analyzed the effect of gene expression on m6A and the post-transcription effect of m6A on protein. Our study provided new insights into the genetic component of m6A in neuropsychiatric disorders and unveiled potential pathogenic mechanisms where m6A exerts influences on disease through gene expression/protein regulation.

Expression level of myocardial enzymes in patients with schizophrenia: Predictive value in the occurrence of violence

BACKGROUND

Schizophrenic patients are prone to violence, frequent recurrence, and difficult to predict. Emotional and behavioral abnormalities during the onset of the disease, resulting in active myocardial enzyme spectrum.

AIM

To explored the expression level of myocardial enzymes in patients with schizophrenia and its predictive value in the occurrence of violence.

METHODS

A total of 288 patients with schizophrenia in our hospital from February 2023 to January 2024 were selected as the research object, and 100 healthy people were selected as the control group. Participants' information, clinical data, and laboratory examination data were collected. According to Modified Overt Aggression Scale score, patients were further divided into the violent (123 cases) and non-violent group (165 cases).

RESULTS

The comparative analysis revealed significant differences in serum myocardial enzyme levels between patients with schizophrenia and healthy individuals. In the schizophrenia group, the violent and non-violent groups also exhibited different levels of serum myocardial enzymes. The levels of myocardial enzymes in the non-violent group were lower than those in the violent group, and the patients in the latter also displayed aggressive behavior in the past.

CONCLUSION

Previous aggressive behavior and the level of myocardial enzymes are of great significance for the diagnosis and prognosis analysis of violent behavior in patients with schizophrenia. By detecting changes in these indicators, we can gain a more comprehensive understanding of a patient's condition and treatment.

Genetic effects on the skin methylome in healthy older twins

Whole-skin DNA methylation variation has been implicated in several diseases, including melanoma, but its genetic basis has not yet been fully characterized. Using bulk skin tissue samples from 414 healthy female UK twins, we performed twin-based heritability and methylation quantitative trait loci (meQTL) analyses for >400,000 DNA methylation sites. We find that the human skin DNA methylome is on average less heritable than previously estimated in blood and other tissues (mean heritability: 10.02%). meQTL analysis identified local genetic effects influencing DNA methylation at 18.8% (76,442) of tested CpG sites, as well as 1,775 CpG sites associated with at least one distal genetic variant. As a functional follow-up, we performed skin expression QTL (eQTL) analyses in a partially overlapping sample of 604 female twins. Colocalization analysis identified over 3,500 shared genetic effects affecting thousands of CpG sites (10,067) and genes (4,475). Mediation analysis of putative colocalized gene-CpG pairs identified 114 genes with evidence for eQTL effects being mediated by DNA methylation in skin, including in genes implicating skin disease such as ALOX12 and CSPG4. We further explored the relevance of skin meQTLs to skin disease and found that skin meQTLs and CpGs under genetic influence were enriched for multiple skin-related genome-wide and epigenome-wide association signals, including for melanoma and psoriasis. Our findings give insights into the regulatory landscape of epigenomic variation in skin.

Inhibitor of FTO, Rhein, Restrains the Differentiation of Myoblasts and Delays Skeletal Muscle Regeneration

N6-methyladenosine (m6A) is a crucial RNA modification affecting skeletal muscle development. Rhein, an anti-inflammatory extract, inhibits FTO, a key demethylase in m6A metabolism. Our study showed that during muscle fiber formation, FTO and ALKBH5 expression increased while m6A levels decreased. After muscle injury, FTO and ALKBH5 expression initially rose but later fell, while m6A levels initially dropped and then recovered. Inhibition of FTO by Rhein reduced MyHC and MyoG expression, indicating myoblast differentiation suppression. In a mouse model, Rhein decreased MyHC expression and muscle fiber cross-sectional area, delaying muscle regeneration. Rhein's ability to increase RNA m6A modification delays skeletal muscle remodeling post-injury, suggesting a new medicinal application for this plant extract.

Crosstalk between epitranscriptomic and epigenomic modifications and its implication in human diseases

Crosstalk between N6-methyladenosine (m6A) and epigenomes is crucial for gene regulation, but its regulatory directionality and disease significance remain unclear. Here, we utilize quantitative trait loci (QTLs) as genetic instruments to delineate directional maps of crosstalk between m6A and two epigenomic traits, DNA methylation (DNAme) and H3K27ac. We identify 47 m6A-to-H3K27ac and 4,733 m6A-to-DNAme and, in the reverse direction, 106 H3K27ac-to-m6A and 61,775 DNAme-to-m6A regulatory loci, with differential genomic location preference observed for different regulatory directions. Integrating these maps with complex diseases, we prioritize 20 genome-wide association study (GWAS) loci for neuroticism, depression, and narcolepsy in brain; 1,767 variants for asthma and expiratory flow traits in lung; and 249 for coronary artery disease, blood pressure, and pulse rate in muscle. This study establishes disease regulatory paths, such as rs3768410-DNAme-m6A-asthma and rs56104944-m6A-DNAme-hypertension, uncovering locus-specific crosstalk between m6A and epigenomic layers and offering insights into regulatory circuits underlying human diseases.

Genetic regulation of m6A RNA methylation and its contribution in human complex diseases

N6-methyladenosine (m6A) has been established as the most prevalent chemical modification in message RNA (mRNA), playing an essential role in determining the fate of RNA molecules. Dysregulation of m6A has been revealed to lead to abnormal physiological conditions and cause various types of human diseases. Recent studies have delineated the genetic regulatory maps for m6A methylation by mapping the quantitative trait loci of m6A (m6A-QTLs), thereby building up the regulatory circuits linking genetic variants, m6A, and human complex traits. Here, we review the recent discoveries concerning the genetic regulatory maps of m6A, describing the methodological and technical details of m6A-QTL identification, and introducing the key findings of the cis- and trans-acting drivers of m6A. We further delve into the tissue- and ethnicity-specificity of m6A-QTL, the association with other molecular phenotypes in light of genetic regulation, the regulators underlying m6A genetics, and importantly, the functional roles of m6A in mediating human complex diseases. Lastly, we discuss potential research avenues that can accelerate the translation of m6A genetics studies toward the development of therapies for human genetic diseases.

Role and regulators of N6-methyladenosine (m6A) RNA methylation in inflammatory subtypes of asthma: a comprehensive review

Asthma is a common chronic inflammatory disease of the lungs and airway, yet its inflammatory subtypes and potential pathogenesis have not been completely elucidated and require further study. With advances in epigenetic development, methylation has emerged as a new direction for identifying and decoding the occurrence and subtype manifestations of asthma. N6-methyladenosine (m6A), an RNA methylation modification occurring in the N6-position of adenosine, is a prevalent epigenetic modification observed in eukaryotes. It exerts significant control over mRNA metabolism by regulating alternative splicing, stability, export, and translation. The dynamic process of m6A methylation plays a crucial role in the pathogenesis of asthma and is tightly regulated by three types of regulators: writers, readers, and erasers. This article provides a comprehensive review of the association between m6A regulators and the pathogenesis of inflammatory subtypes of asthma, such as involvement of inflammatory cells and related inflammatory response. Furthermore, the findings presented herein provide new insights and a solid foundation for further research on m6A mRNA methylation as biomarkers for the diagnosis and development of personalized treatment for different subtypes of asthma, particularly neutrophilic asthma and eosinophilic asthma.

Global DNA and RNA Methylation Signature in Response to Antipsychotic Treatment in First-Episode Schizophrenia Patients

Background

Schizophrenia is a heterogeneous chronic psychiatric disorder influenced by genetic and environmental factors. Environmental factors can alter epigenetic marks, which regulate gene expression and cause an array of systemic changes. Several studies have demonstrated the association of epigenetic modulations in schizophrenia, which can influence clinical course, symptoms, and even treatment. Based on this, we have examined the global DNA methylation patterns, namely the 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC); and the global RNA modification N6-methyladenosine (m6A) RNA methylation status in peripheral blood cells. First-Episode Psychosis (FEP) patients who were diagnosed with Schizophrenia (SCZ) and undergoing treatment were stratified as Treatment-Responsive (TR) and Treatment-Non-Responsive (TNR). Age- and sex-matched healthy subjects served as controls.

Results

The methylation pattern of 5mC and 5hmC showed significant increases in patients in comparison to controls. Further, when patients were classified based on their response to treatment, there was a statistically significant increase in methylation patterns in the treatment non-responder group. 5fC and m6A levels did not show any statistical significance across the groups. Further, gender-based stratification did not yield any significant difference for the markers.

Conclusion

The study highlights the increased global methylation pattern in SCZ patients and a significant difference between the TR versus TNR groups. Global 5mC and 5hmC epigenetic marks suggest their potential roles in schizophrenia pathology, and also in the treatment response to antipsychotics. Since not many studies were available on the treatment response, further validation and the use of more sensitive techniques to study methylation status could unravel the potential of these epigenetic modifications as biomarkers for SCZ as well as distinguishing the antipsychotic treatment response in patients.

Fat mass and obesity-associated protein regulates RNA methylation associated with spatial cognitive dysfunction after chronic cerebral hypoperfusion

RNA methylation can epigenetically regulate learning and memory. However, it is unclear whether RNA methylation plays a critical role in the pathophysiology of Vascular dementia (VD). Here, we report that expression of the fat mass and obesity associated gene (FTO), an RNA demethylase, is downregulated in the hippocampus in models of VD. Through prediction and dual-luciferase reporters validation studies, we observed that miRNA-711 was upregulated after VD and could bind to the 3'-untranslated region of FTO mRNA and regulate its expression in vitro. Methylated RNA immunoprecipitation (MeRIP)-qPCR assay and functional study confirmed that Syn1 was an important target gene of FTO. This suggests that FTO is an important regulator of Syn1. FTO upregulation by inhibition of miR-711 in the hippocampus relieves synaptic association protein and synapse deterioration in vivo, whereas FTO downregulation by miR-711 agomir in the hippocampus leads to aggravate the synapse deterioration. FTO upregulation by inhibition of miR-711 relieves cognitive impairment of rats VD model, whereas FTO downregulation by miR-711 deteriorate cognitive impairment. Our findings suggest that FTO is a regulator of a mechanism underlying RNA methylation associated with spatial cognitive dysfunction after chronic cerebral hypoperfusion.

An association study of m6A methylation with major depressive disorder

OBJECTIVE

To find the relationship between N6-methyladenosine (m6A) genes and Major Depressive Disorder (MDD).

METHODS

Differential expression of m6A associated genes between normal and MDD samples was initially identified. Subsequent analysis was conducted on the functions of these genes and the pathways they may affect. A diagnostic model was constructed using the expression matrix of these differential genes, and visualized using a nomogram. Simultaneously, an unsupervised classification method was employed to classify all patients based on the expression of these m6A associated genes. Following this, common differential genes among different clusters were computed. By analyzing the functions of the common differential expressed genes among clusters, the role of m6A-related genes in the pathogenesis of MDD patients was elucidated.

RESULTS

Differential expression was observed in ELAVL1 and YTHDC2 between the MDD group and the control group. ELAVL1 was associated with comorbid anxiety in MDD patients. A linear regression model based on these two genes could accurately predict whether patients in the GSE98793 dataset had MDD and could provide a net benefit for clinical decision-making. Based on the expression matrix of ELAVL1 and YTHDC2, MDD patients were classified into three clusters. Among these clusters, there were 937 common differential genes. Enrichment analysis was also performed on these genes. The ssGSEA method was applied to predict the content of 23 immune cells in the GSE98793 dataset samples. The relationship between these immune cells and ELAVL1, YTHDC2, and different clusters was analyzed.

CONCLUSION

Among all the m6A genes, ELAVL1 and YTHDC2 are closely associated with MDD, ELAVL1 is related to comorbid anxiety in MDD. ELAVL1 and YTHDC2 have opposite associations with immune cells in MDD.

Identification and characterization of whole blood gene expression and splicing quantitative trait loci during early to mid-lactation of dairy cattle

BACKGROUND

Characterization of regulatory variants (e.g., gene expression quantitative trait loci, eQTL; gene splicing QTL, sQTL) is crucial for biologically interpreting molecular mechanisms underlying loci associated with complex traits. However, regulatory variants in dairy cattle, particularly in specific biological contexts (e.g., distinct lactation stages), remain largely unknown. In this study, we explored regulatory variants in whole blood samples collected during early to mid-lactation (22-150 days after calving) of 101 Holstein cows and analyzed them to decipher the regulatory mechanisms underlying complex traits in dairy cattle.

RESULTS

We identified 14,303 genes and 227,705 intron clusters expressed in the white blood cells of 101 cattle. The average heritability of gene expression and intron excision ratio explained by cis-SNPs is 0.28 ± 0.13 and 0.25 ± 0.13, respectively. We identified 23,485 SNP-gene expression pairs and 18,166 SNP-intron cluster pairs in dairy cattle during early to mid-lactation. Compared with the 2,380,457 cis-eQTLs reported to be present in blood in the Cattle Genotype-Tissue Expression atlas (CattleGTEx), only 6,114 cis-eQTLs (P < 0.05) were detected in the present study. By conducting colocalization analysis between cis-e/sQTL and the results of genome-wide association studies (GWAS) from four traits, we identified a cis-e/sQTL (rs109421300) of the DGAT1 gene that might be a key marker in early to mid-lactation for milk yield, fat yield, protein yield, and somatic cell score (PP4 > 0.6). Finally, transcriptome-wide association studies (TWAS) revealed certain genes (e.g., FAM83H and TBC1D17) whose expression in white blood cells was significantly (P < 0.05) associated with complex traits.

CONCLUSIONS

This study investigated the genetic regulation of gene expression and alternative splicing in dairy cows during early to mid-lactation and provided new insights into the regulatory mechanisms underlying complex traits of economic importance.

Maternal prednisone exposure during pregnancy elevates susceptibility to osteoporosis in female offspring: The role of mitophagy/FNDC5 alteration in skeletal muscle

Maternal exposure to glucocorticoids has been associated with adverse outcomes in offspring. However, the consequences and mechanisms of gestational exposure to prednisone on susceptibility to osteoporosis in the offspring remain unclear. Here, we found that gestational prednisone exposure enhanced susceptibility to osteoporosis in adult mouse offspring. In a further exploration of myogenic mechanisms, results showed that gestational prednisone exposure down-regulated FNDC5/irisin protein expression and activation of OPTN-dependent mitophagy in skeletal muscle of adult offspring. Additional experiments elucidated that activated mitophagy significantly inhibited the expression of FNDC5/irisin in skeletal muscle cells. Likewise, we observed delayed fetal bone development, downregulated FNDC5/irisin expression, and activated mitophagy in fetal skeletal muscle upon gestational prednisone exposure. In addition, an elevated total m6A level was observed in fetal skeletal muscle after gestational prednisone exposure. Finally, gestational supplementation with S-adenosylhomocysteine (SAH), an inhibitor of m6A activity, attenuated mitophagy and restored FNDC5/irisin expression in fetal skeletal muscle, which in turn reversed fetal bone development. Overall, these data indicate that gestational prednisone exposure increases m6A modification, activates mitophagy, and decreases FNDC5/irisin expression in skeletal muscle, thus elevating osteoporosis susceptibility in adult offspring. Our results provide a new perspective on the earlier prevention and treatment of fetal-derived osteoporosis.

xWAS analysis in neuropsychiatric disorders by integrating multi-molecular phenotype quantitative trait loci and GWAS summary data

BACKGROUND

Integrating quantitative trait loci (QTL) data related to molecular phenotypes with genome-wide association study (GWAS) data is an important post-GWAS strategic approach employed to identify disease-associated molecular features. Various types of molecular phenotypes have been investigated in neuropsychiatric disorders. However, these findings pertaining to distinct molecular features are often independent of each other, posing challenges for having an overview of the mapped genes.

METHODS

In this study, we comprehensively summarized published analyses focusing on four types of risk-related molecular features (gene expression, splicing transcriptome, protein abundance, and DNA methylation) across five common neuropsychiatric disorders. Subsequently, we conducted supplementary analyses with the latest GWAS dataset and corresponding deficient molecular phenotypes using Functional Summary-based Imputation (FUSION) and summary data-based Mendelian randomization (SMR). Based on the curated and supplemented results, novel reliable genes and their functions were explored.

RESULTS

Our findings revealed that eQTL exhibited superior ability in prioritizing risk genes compared to the other QTL, followed by sQTL. Approximately half of the genes associated with splicing transcriptome, protein abundance, and DNA methylation were successfully replicated by eQTL-associated genes across all five disorders. Furthermore, we identified 436 novel reliable genes, which enriched in pathways related with neurotransmitter transportation such as synaptic, dendrite, vesicles, axon along with correlations with other neuropsychiatric disorders. Finally, we identified ten multiple molecular involved regulation patterns (MMRP), which may provide valuable insights into understanding the contribution of molecular regulation network targeting these disease-associated genes.

CONCLUSIONS

The analyses prioritized novel and reliable gene sets related with five molecular features based on published and supplementary results for five common neuropsychiatric disorders, which were missed in the original GWAS analysis. Besides, the involved MMRP behind these genes could be given priority for further investigation to elucidate the pathogenic molecular mechanisms underlying neuropsychiatric disorders in future studies.

Epigenetic mechanisms in depression: Implications for pathogenesis and treatment

The risk of depression is influenced by both genetic and environmental factors. It has been suggested that epigenetic mechanisms may mediate the risk of depression following exposure to adverse life events. Epigenetics encompasses stable alterations in gene expression that are controlled through transcriptional, post-transcriptional, translational, or post-translational processes, including DNA modifications, chromatin remodeling, histone modifications, RNA modifications, and non-coding RNA (ncRNA) regulation, without any changes in the DNA sequence. In this review, we explore recent research advancements in the realm of epigenetics concerning depression. Furthermore, we evaluate the potential of epigenetic changes as diagnostic and therapeutic biomarkers for depression.

Dysregulated N6-methyladenosine modification in peripheral immune cells contributes to the pathogenesis of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurogenerative disorder with uncertain origins. Emerging evidence implicates N6-methyladenosine (m6A) modification in ALS pathogenesis. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and liquid chromatography-mass spectrometry were utilized for m6A profiling in peripheral immune cells and serum proteome analysis, respectively, in patients with ALS (n = 16) and controls (n = 6). The single-cell transcriptomic dataset (GSE174332) of primary motor cortex was further analyzed to illuminate the biological implications of differentially methylated genes and cell communication changes. Analysis of peripheral immune cells revealed extensive RNA hypermethylation, highlighting candidate genes with differential m6A modification and expression, including C-X3-C motif chemokine receptor 1 (CX3CR1). In RAW264.7 macrophages, disrupted CX3CR1 signaling affected chemotaxis, potentially influencing immune cell migration in ALS. Serum proteome analysis demonstrated the role of dysregulated immune cell migration in ALS. Cell type-specific expression variations of these genes in the central nervous system (CNS), particularly microglia, were observed. Intercellular communication between neurons and glial cells was selectively altered in ALS CNS. This integrated approach underscores m6A dysregulation in immune cells as a potential ALS contributor.

Regulatory role of m6A epitranscriptomic modifications in normal development and congenital malformations during embryogenesis

The discovery of N6-methyladenosine (m6A) methylation and its role in translation has led to the emergence of a new field of research. Despite accumulating evidence suggesting that m6A methylation is essential for the pathogenesis of cancers and aging diseases by influencing RNA stability, localization, transformation, and translation efficiency, its role in normal and abnormal embryonic development remains unclear. An increasing number of studies are addressing the development of the nervous and gonadal systems during embryonic development, but only few are assessing that of the immune, hematopoietic, urinary, and respiratory systems. Additionally, these studies are limited by the requirement for reliable embryonic animal models and the difficulty in collecting tissue samples of fetuses during development. Multiple studies on the function of m6A methylation have used suitable cell lines to mimic the complex biological processes of fetal development or the early postnatal phase; hence, the research is still in the primary stage. Herein, we discuss current advances in the extensive biological functions of m6A methylation in the development and maldevelopment of embryos/fetuses and conclude that m6A modification occurs extensively during fetal development. Aberrant expression of m6A regulators is probably correlated with single or multiple defects in organogenesis during the intrauterine life. This comprehensive review will enhance our understanding of the pivotal role of m6A modifications involved in fetal development and examine future research directions in embryogenesis.

Integrative analyses of N6-methyladenosine-associated single-nucleotide polymorphisms (m6A-SNPs) identify tumor suppressor gene AK9 in lung cancer

N6 -methyladenosine (m6 A) modification has been identified as one of the most important epigenetic regulation mechanisms in the development of human cancers. However, the association between m6 A-associated single-nucleotide polymorphisms (m6 A-SNPs) and lung cancer risk remains largely unknown. Here, we identified m6 A-SNPs and examined the association of these m6 A-SNPs with lung cancer risk in 13,793 lung cancer cases and 14,027 controls. In silico functional annotation was used to identify causal m6 A-SNPs and target genes. Furthermore, methylated RNA immunoprecipitation and quantitative real-time polymerase chain reaction (MeRIP-qPCR) assay was performed to assess the m6 A modification level of different genotypes of the causal SNP. In vitro assays were performed to validate the potential role of the target gene in lung cancer. A total of 8794 m6 A-SNPs were detected, among which 397 SNPs in nine susceptibility loci were associated with lung cancer risk, including six novel loci. Bioinformatics analyses indicated that rs1321328 in 6q21 was located around the m6 A modification site of AK9 and significantly reduced AK9 expression (β = -0.15, p = 2.78 × 10-8 ). Moreover, AK9 was significantly downregulated in lung cancer tissues than that in adjacent normal tissues of samples from the Cancer Genome Atlas and Nanjing Lung Cancer Cohort. MeRIP-qPCR assay suggested that C allele of rs1321328 could significantly decrease the m6 A modification level of AK9 compared with G allele. In vitro assays verified the tumor-suppressing role of AK9 in lung cancer. These findings shed light on the pathogenic mechanism of lung cancer susceptibility loci linked with m6 A modification.

NIPBL-mediated RAD21 facilitates tumorigenicity by the PI3K pathway in non-small-cell lung cancer

It is urgent to identify novel early diagnostic markers and therapeutic targets for non-small-cell lung cancer (NSCLC), which accounts for 85% of lung cancer cases and has a 5-year survival rate of 4-17%. Here, chromatin immunoprecipitation (ChIP) was used to identify DNA‒protein interactions, RNA methylation was determined by methylated RNA immunoprecipitation (MeRIP), RNA stability was tested by an RNA decay assay. We showed that RAD21, a member of the cohesin complex, is upregulated in NSCLC tissues and cell lines and found to be an independent prognostic factor for overall survival (OS) of NSCLC patients. Mechanistically, the cohesin loading factor Nipped-B-Like Protein (NIPBL) promoted RAD21 gene transcription by enhancing histone H3 lysine 27 (H3K27) demethylation via recruiting lysine demethylase 6B (KDM6B) to the RAD21 gene promoter. RAD21 enhanced phosphatidylinositol 3-kinase (PI3K) gene transcription, and NIPBL reversed the effect of enhancer of zeste 2; catalytic subunit of polycomb repressive complex 2 (EZH2) on RAD21-mediated PI3K gene transcription by disrupting the association between EZH2 and RAD21. Moreover, NIPBL level was increased by stabilization of its transcripts through mRNA methylation. These findings highlight the oncogenic role of RAD21 in NSCLC and suggest its use as a potential diagnostic marker and therapeutic target for NSCLC.

Dissecting the sequence and structural determinants guiding m6A deposition and evolution via inter- and intra-species hybrids

BACKGROUND

N6-methyladenosine (m6A) is the most abundant mRNA modification, and controls mRNA stability. m6A distribution varies considerably between and within species. Yet, it is unclear to what extent this variability is driven by changes in genetic sequences ('cis') or cellular environments ('trans') and via which mechanisms.

RESULTS

Here we dissect the determinants governing RNA methylation via interspecies and intraspecies hybrids in yeast and mammalian systems, coupled with massively parallel reporter assays and m6A-QTL reanalysis. We find that m6A evolution and variability is driven primarily in 'cis', via two mechanisms: (1) variations altering m6A consensus motifs, and (2) variation impacting mRNA secondary structure. We establish that mutations impacting RNA structure - even when distant from an m6A consensus motif - causally dictate methylation propensity. Finally, we demonstrate that allele-specific differences in m6A levels lead to allele-specific changes in gene expression.

CONCLUSIONS

Our findings define the determinants governing m6A evolution and diversity and characterize the consequences thereof on gene expression regulation.

Chemically Modified Platforms for Better RNA Therapeutics

RNA-based therapies have catalyzed a revolutionary transformation in the biomedical landscape, offering unprecedented potential in disease prevention and treatment. However, despite their remarkable achievements, these therapies encounter substantial challenges including low stability, susceptibility to degradation by nucleases, and a prominent negative charge, thereby hindering further development. Chemically modified platforms have emerged as a strategic innovation, focusing on precise alterations either on the RNA moieties or their associated delivery vectors. This comprehensive review delves into these platforms, underscoring their significance in augmenting the performance and translational prospects of RNA-based therapeutics. It encompasses an in-depth analysis of various chemically modified delivery platforms that have been instrumental in propelling RNA therapeutics toward clinical utility. Moreover, the review scrutinizes the rationale behind diverse chemical modification techniques aiming at optimizing the therapeutic efficacy of RNA molecules, thereby facilitating robust disease management. Recent empirical studies corroborating the efficacy enhancement of RNA therapeutics through chemical modifications are highlighted. Conclusively, we offer profound insights into the transformative impact of chemical modifications on RNA drugs and delineates prospective trajectories for their future development and clinical integration.

Comparison of transcriptome-wide N6-methyladenosine profiles from healthy trio families reveals regulator-mediated methylation alterations

The N6-methyladenosine (m6A) modification is a highly conserved RNA modification found in eukaryotic messenger RNAs (mRNAs). It plays a vital role in regulating various biological processes. Dysregulation of m6A modifications has been linked to a range of complex genetic diseases in humans. However, there has been a lack of comprehensive characterization and comparison of m6A modifications at the transcriptome-wide level within families. To address this gap, we profiled transcriptome-wide m6A methylation in 18 individuals across 6 Yoruba trio families. The m6A methylomes of these 18 individuals revealed that m6A modifications in children showed greater similarity to each other than to their parents. This suggests that m6A modifications are influenced by multiple factors rather than solely determined by genetic factors. Additionally, we found that mRNAs exhibiting m6A modifications specific to children were enriched in cell cycle control processes, while those with m6A modifications specific to parents were associated with chromatin modifications. Furthermore, our analysis on the interactions between differentially expressed m6A-related regulatory genes and age-related genes suggested that age might be one of the factors influencing m6A modifications. In summary, our study provided a valuable dataset that highlighted the differences and functional diversity of m6A modifications within and between trio families.

The Inflammatory Puzzle: Piecing together the Links between Neuroinflammation and Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that has a complex genetic basis. Through advancements in genetic screening, researchers have identified more than 40 mutant genes associated with ALS, some of which impact immune function. Neuroinflammation, with abnormal activation of immune cells and excessive production of inflammatory cytokines in the central nervous system, significantly contributes to the pathophysiology of ALS. In this review, we examine recent evidence on the involvement of ALS-associated mutant genes in immune dysregulation, with a specific focus on the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway and N6-methyladenosine (m6A)-mediated immune regulation in the context of neurodegeneration. We also discuss the perturbation of immune cell homeostasis in both the central nervous system and peripheral tissues in ALS. Furthermore, we explore the advancements made in the emerging genetic and cell-based therapies for ALS. This review underscores the complex relationship between ALS and neuroinflammation, highlighting the potential to identify modifiable factors for therapeutic intervention. A deeper understanding of the connection between neuroinflammation and the risk of ALS is crucial for advancing effective treatments for this debilitating disorder.

Integrative Analysis of N6-methyladenosine RNA modifications related genes and their Influences on Immunoreaction or fibrosis in myocardial infarction

Increasing studies have shown that N6-methyladenosine (m6A) modification plays an important role in cardiovascular diseases. In this study, we systematically investigated the regulatory mode of m6A genes in myocardial infarction (MI) by combining bioinformatics analysis of clinical samples with animal experiments. We utilized gene expression data of clinical samples from public databases to examine the expression of m6A genes in heart tissues and found a large difference between the healthy control group and MI group. Subsequently, we established an MI diagnosis model based on the differentially expressed m6A genes using the random forest method. Next, unsupervised clustering method was used to classify all MI samples into two clusters, and the differences in immune infiltration and gene expression between different clusters were compared. We found LRPPRC to be the predominant gene in m6A clustering, and it was negatively correlated with immunoreaction. Through GO enrichment analysis, we found that most differentially expressed genes between the two clusters were profibrotic. By means of WGCNA, we inferred that GJA4 might be a core molecule in the m6A regulatory network of MI. This study demonstrates that m6A regulators probably affects the immune-inflammatory response and fibrosis to regulate the process of MI, which provides a potential therapeutic target.

m6A modification negatively regulates translation by switching mRNA from polysome to P-body via IGF2BP3

In the cytoplasm, mRNAs are dynamically partitioned into translating and non-translating pools, but the mechanism for this regulation has largely remained elusive. Here, we report that m6A regulates mRNA partitioning between polysome and P-body where a pool of non-translating mRNAs resides. By quantifying the m6A level of polysomal and cytoplasmic mRNAs with m6A-LAIC-seq and m6A-LC-MS/MS in HeLa cells, we observed that polysome-associated mRNAs are hypo-m6A-methylated, whereas those enriched in P-body are hyper-m6A-methylated. Downregulation of the m6A writer METTL14 enhances translation by switching originally hyper-m6A-modified mRNAs from P-body to polysome. Conversely, by proteomic analysis, we identify a specific m6A reader IGF2BP3 enriched in P-body, and via knockdown and molecular tethering assays, we demonstrate that IGF2BP3 is both necessary and sufficient to switch target mRNAs from polysome to P-body. These findings suggest a model for the dynamic regulation of mRNA partitioning between the translating and non-translating pools in an m6A-dependent manner.

Altered m6A RNA methylation governs denervation-induced muscle atrophy by regulating ubiquitin proteasome pathway

BACKGROUND

Denervation-induced muscle atrophy is complex disease involving multiple biological processes with unknown mechanisms. N6-methyladenosine (m6A) participates in skeletal muscle physiology by regulating multiple levels of RNA metabolism, but its impact on denervation-induced muscle atrophy is still unclear. Here, we aimed to explore the changes, functions, and molecular mechanisms of m6A RNA methylation during denervation-induced muscle atrophy.

METHODS

During denervation-induced muscle atrophy, the m6A immunoprecipitation sequencing (MeRIP-seq) as well as enzyme-linked immunosorbent assay analysis were used to detect the changes of m6A modified RNAs and the involved biological processes. 3-deazidenosine (Daa) and R-2-hydroxyglutarate (R-2HG) were used to verify the roles of m6A RNA methylation. Through bioinformatics analysis combined with experimental verification, the regulatory roles and mechanisms of m6A RNA methylation had been explored.

RESULTS

There were many m6A modified RNAs with differences during denervation-induced muscle atrophy, and overall, they were mainly downregulated. After 72 h of denervation, the biological processes involved in the altered mRNA with m6A modification were mainly related to zinc ion binding, ubiquitin protein ligase activity, ATP binding and sequence-specific DNA binding and transcription coactivator activity. Daa reduced overall m6A levels in healthy skeletal muscles, which reduced skeletal muscle mass. On the contrary, the increase in m6A levels mediated by R-2HG alleviated denervation induced muscle atrophy. The m6A RNA methylation regulated skeletal muscle mass through ubiquitin-proteasome pathway.

CONCLUSION

This study indicated that decrease in m6A RNA methylation was a new symptom of denervation-induced muscle atrophy, and confirmed that targeting m6A alleviated denervation-induced muscle atrophy.

Leveraging molecular quantitative trait loci to comprehend complex diseases/traits from the omics perspective

Comprehending the molecular basis of quantitative genetic variation is a principal goal for complex diseases or traits. Molecular quantitative trait loci (molQTLs) have made it possible to investigate the effects of genetic variants hiding behind large-scale omics data. A deeper understanding of molQTL is urgently required in light of the multi-dimensionalization of omics data to more fully elucidate the pertinent biological mechanisms. Herein, we reviewed molQTLs with the corresponding resource from the omics perspective and further discussed the integrative strategy of GWAS-molQTL to infer their causal effects. Subsequently, we described the opportunities and challenges encountered by molQTL. The case studies showed that molQTL is essential for complex diseases and traits, whether single- or multi-omics QTLs. Overall, we highlighted the functional significance of genetic variants to employ the discovery of molQTL in complex diseases and traits.

Multitissue H3K27ac profiling of GTEx samples links epigenomic variation to disease

Genetic variants associated with complex traits are primarily noncoding, and their effects on gene-regulatory activity remain largely uncharacterized. To address this, we profile epigenomic variation of histone mark H3K27ac across 387 brain, heart, muscle and lung samples from Genotype-Tissue Expression (GTEx). We annotate 282 k active regulatory elements (AREs) with tissue-specific activity patterns. We identify 2,436 sex-biased AREs and 5,397 genetically influenced AREs associated with 130 k genetic variants (haQTLs) across tissues. We integrate genetic and epigenomic variation to provide mechanistic insights for disease-associated loci from 55 genome-wide association studies (GWAS), by revealing candidate tissues of action, driver SNPs and impacted AREs. Lastly, we build ARE-gene linking scores based on genetics (gLink scores) and demonstrate their unique ability to prioritize SNP-ARE-gene circuits. Overall, our epigenomic datasets, computational integration and mechanistic predictions provide valuable resources and important insights for understanding the molecular basis of human diseases/traits such as schizophrenia.

Regulatory role of N6-methyladenosine in intramuscular fat deposition in chicken

Intramuscular fat (IMF) has a pivotal influence on meat quality, with its deposition being a multifaceted physiological interaction of several regulatory factors. N6-methyladenosine (m6A), the preeminent epigenetic alteration among eukaryotic RNA modifications, holds a crucial role in moderating post-transcriptional gene expression. However, there is a dearth of comprehensive understanding regarding the functional machinery of m6A modification in the context of IMF deposition in poultry. Our current study entails an analysis of the disparities in IMF within the breast and leg of 180-day-old Jingyuan chickens. We implemented methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) to delve into the distribution of m6A and its putative regulatory frameworks on IMF deposition in chickens. The findings demonstrated a markedly higher IMF content in leg relative to breast (P < 0.01). Furthermore, the expression of METTL14, WTAP, FTO, and ALKBH5 was significantly diminished in comparison to that of breast (P < 0.01). The m6A peaks in the breast and leg primarily populated 3'untranslated regions (3'UTR) and coding sequence (CDS) regions. The leg, when juxtaposed with the breast, manifested 176 differentially methylated genes (DMGs), including 151 hyper-methylated DMGs and 25 hypo-methylated DMGs. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed a pronounced enrichment of DMGs in the biosynthesis of amino acids, peroxisome, Fatty acid biosynthesis, fatty acid elongation, and cell adhesion molecules (CAMs) pathways. Key DMGs, namely ECH1, BCAT1, and CYP1B1 were implicated in the regulation of muscle lipid anabolism. Our study offers substantial insight and forms a robust foundation for further exploration of the functional mechanisms of m6A modification in modulating IMF deposition. This holds profound theoretical importance for improving and leveraging meat quality in indigenous chicken breeds.

Epigenomic dissection of Alzheimer's disease pinpoints causal variants and reveals epigenome erosion

Recent work has identified dozens of non-coding loci for Alzheimer's disease (AD) risk, but their mechanisms and AD transcriptional regulatory circuitry are poorly understood. Here, we profile epigenomic and transcriptomic landscapes of 850,000 nuclei from prefrontal cortexes of 92 individuals with and without AD to build a map of the brain regulome, including epigenomic profiles, transcriptional regulators, co-accessibility modules, and peak-to-gene links in a cell-type-specific manner. We develop methods for multimodal integration and detecting regulatory modules using peak-to-gene linking. We show AD risk loci are enriched in microglial enhancers and for specific TFs including SPI1, ELF2, and RUNX1. We detect 9,628 cell-type-specific ATAC-QTL loci, which we integrate alongside peak-to-gene links to prioritize AD variant regulatory circuits. We report differential accessibility of regulatory modules in late AD in glia and in early AD in neurons. Strikingly, late-stage AD brains show global epigenome dysregulation indicative of epigenome erosion and cell identity loss.

Smoking-informed methylation and expression QTLs in human brain and colocalization with smoking-associated genetic loci

Smoking is a leading cause of preventable morbidity and mortality. Smoking is heritable, and genome-wide association studies (GWAS) of smoking behaviors have identified hundreds of significant loci. Most GWAS-identified variants are noncoding with unknown neurobiological effects. We used genome-wide genotype, DNA methylation, and RNA sequencing data in postmortem human nucleus accumbens (NAc) to identify cis-methylation/expression quantitative trait loci (meQTLs/eQTLs), investigate variant-by-cigarette smoking interactions across the genome, and overlay QTL evidence at smoking GWAS-identified loci to evaluate their regulatory potential. Active smokers (N=52) and nonsmokers (N=171) were defined based on cotinine biomarker levels and next-of-kin reporting. We simultaneously tested variant and variant-by-smoking interaction effects on methylation and expression, separately, adjusting for biological and technical covariates and using a two-stage multiple testing approach with eigenMT and Bonferroni corrections. We found >2 million significant meQTL variants (padj<0.05) corresponding to 41,695 unique CpGs. Results were largely driven by main effects; five meQTLs, mapping to NUDT12, FAM53B, RNF39, and ADRA1B, showed a significant interaction with smoking. We found 57,683 significant eQTLs for 958 unique eGenes (padj<0.05) and no smoking interactions. Colocalization analyses identified loci with smoking-associated GWAS variants that overlapped meQTLs/eQTLs, suggesting that these heritable factors may influence smoking behaviors through functional effects on methylation/expression. One locus containing MUSTIN1 and ITIH4 colocalized across all data types (GWAS + meQTL + eQTL). In this first genome-wide meQTL map in the human NAc, the enriched overlap with smoking GWAS-identified genetic loci provides evidence that gene regulation in the brain helps explain the neurobiology of smoking behaviors.

METTL3 Promotes the Differentiation of Goat Skeletal Muscle Satellite Cells by Regulating MEF2C mRNA Stability in a m6A-Dependent Manner

The development of mammalian skeletal muscle is a highly complex process involving multiple molecular interactions. As a prevalent RNA modification, N6-methyladenosine (m6A) regulates the expression of target genes to affect mammalian development. Nevertheless, it remains unclear how m6A participates in the development of goat muscle. In this study, methyltransferase 3 (METTL3) was significantly enriched in goat longissimus dorsi (LD) tissue. In addition, the global m6A modification level and differentiation of skeletal muscle satellite cells (MuSCs) were regulated by METTL3. By performing mRNA-seq analysis, 8050 candidate genes exhibited significant changes in expression level after the knockdown of METTL3 in MuSCs. Additionally, methylated RNA immunoprecipitation sequencing (MeRIP-seq) illustrated that myocyte enhancer factor 2c (MEF2C) mRNA contained m6A modification. Further experiments demonstrated that METTL3 enhanced the differentiation of MuSCs by upregulating m6A levels and expression of MEF2C. Moreover, the m6A reader YTH N6-methyladenosine RNA binding protein C1 (YTHDC1) was bound and stabilized to MEF2C mRNA. The present study reveals that METTL3 enhances myogenic differentiation in MuSCs by regulating MEF2C and provides evidence of a post-transcriptional mechanism in the development of goat skeletal muscle.

Dynamic DNA 5-hydroxylmethylcytosine and RNA 5-methycytosine Reprogramming During Early Human Development

After implantation, complex and highly specialized molecular events render functionally distinct organ formation, whereas how the epigenome shapes organ-specific development remains to be fully elucidated. Here, nano-hmC-Seal, RNA bisulfite sequencing (RNA-BisSeq), and RNA sequencing (RNA-Seq) were performed, and the first multilayer landscapes of DNA 5-hydroxymethylcytosine (5hmC) and RNA 5-methylcytosine (m5C) epigenomes were obtained in the heart, kidney, liver, and lung of the human foetuses at 13-28 weeks with 123 samples in total. We identified 70,091 and 503 organ- and stage-specific differentially hydroxymethylated regions (DhMRs) and m5C-modified mRNAs, respectively. The key transcription factors (TFs), T-box transcription factor 20 (TBX20), paired box 8 (PAX8), krueppel-like factor 1 (KLF1), transcription factor 21 (TCF21), and CCAAT enhancer binding protein beta (CEBPB), specifically contribute to the formation of distinct organs at different stages. Additionally, 5hmC-enriched Alu elements may participate in the regulation of expression of TF-targeted genes. Our integrated studies reveal a putative essential link between DNA modification and RNA methylation, and illustrate the epigenetic maps during human foetal organogenesis, which provide a foundation for for an in-depth understanding of the epigenetic mechanisms underlying early development and birth defects.

m6A-TSHub: Unveiling the Context-specific m6A Methylation and m6A-affecting Mutations in 23 Human Tissues

As the most pervasive epigenetic marker present on mRNAs and long non-coding RNAs (lncRNAs), N6-methyladenosine (m6A) RNA methylation has been shown to participate in essential biological processes. Recent studies have revealed the distinct patterns of m6A methylome across human tissues, and a major challenge remains in elucidating the tissue-specific presence and circuitry of m6A methylation. We present here a comprehensive online platform, m6A-TSHub, for unveiling the context-specific m6A methylation and genetic mutations that potentially regulate m6A epigenetic mark. m6A-TSHub consists of four core components, including (1) m6A-TSDB, a comprehensive database of 184,554 functionally annotated m6A sites derived from 23 human tissues and 499,369 m6A sites from 25 tumor conditions, respectively; (2) m6A-TSFinder, a web server for high-accuracy prediction of m6A methylation sites within a specific tissue from RNA sequences, which was constructed using multi-instance deep neural networks with gated attention; (3) m6A-TSVar, a web server for assessing the impact of genetic variants on tissue-specific m6A RNA modifications; and (4) m6A-CAVar, a database of 587,983 The Cancer Genome Atlas (TCGA) cancer mutations (derived from 27 cancer types) that were predicted to affect m6A modifications in the primary tissue of cancers. The database should make a useful resource for studying the m6A methylome and the genetic factors of epitranscriptome disturbance in a specific tissue (or cancer type). m6A-TSHub is accessible at www.xjtlu.edu.cn/biologicalsciences/m6ats.

Allele-specific RNA N 6-methyladenosine modifications reveal functional genetic variants in human tissues

An intricate network of cis- and trans-elements acts on RNA N 6-methyladenosine (m6A), which in turn may affect gene expression and, ultimately, human health. A complete understanding of this network requires new approaches to accurately measure the subtle m6A differences arising from genetic variants, many of which have been associated with common diseases. To address this gap, we developed a method to accurately and sensitively detect transcriptome-wide allele-specific m6A (ASm6A) from MeRIP-seq data and applied it to uncover 12,056 high-confidence ASm6A modifications from 25 human tissues. We also identified 1184 putative functional variants for ASm6A regulation, a subset of which we experimentally validated. Importantly, we found that many of these ASm6A-associated genetic variants were enriched for common disease-associated and complex trait-associated risk loci, and verified that two disease risk variants can change m6A modification status. Together, this work provides a tool to detangle the dynamic network of RNA modifications at the allelic level and highlights the interplay of m6A and genetics in human health and disease.

The more the neuroticism, the more the susceptibility to Alzheimer's disease. What inspiration can neuroticism provide?

Study of neuroticism can provide important insights. Before the inclusion of neuroticism in the study of Alzheimer's disease (AD), clinical and scientific researchers used relatively fixed models to treat AD, such as prescribing fixed doses of drugs and fixed research strategies. However, taking neuroticism into account affects drug use, the direction of scientific research, and even the mental health of the population, which translates into more immediate economic benefits.