m6A mRNA Research Articles

Epitranscriptomic regulation of cardiac fibrosis via YTHDF1-dependent PIEZO2 mRNA m6A modification.

Mechanosensitive ion channels play a key role in heart development, physiology, and disease. However, little is known about the molecular mechanisms of the mechanosensitive nonselective cationic channel Piezo family in cardiac fibrosis. Mice were treated with ISO/Ang-II/TAC to induce cardiac fibrosis. AAV9 carrying POSTN promoter-driven small hairpin RNA targeting YTHDF1, and Piezo2 were administered to ISO mice to investigate their roles in cardiac fibrosis. RNA-seq, single-cell sequencing, and histological and biochemical analyses were performed to determine the mechanism by which YTHDF1 regulates Piezo2 expression in cardiac fibrosis. Piezo2 was reconstituted in YTHDF1-deficient cardiac fibroblasts and mouse hearts to study its effects on cardiac fibroblast autophagy and fibrosis. Piezo2 but not Piezo1 expression increased in experimental cardiac fibrosis and TGF-β1-induced cardiac fibroblasts. Fibroblast-specific Piezo2 deficiency ameliorated fibroblast activation and autophagy and inhibited cardiac fibrosis. Mechanistically, Piezo2 upregulation was associated with elevated m6A mRNA levels. Site-specific m6A modifications at peak_26355 were crucial for regulating the binding of YTHDF1 to Piezo2 mRNA and inducing Piezo2 translation. Notably, Piezo2 epitranscriptomic repression ameliorated experimental cardiac fibrosis. We demonstrated a novel epitranscriptomic mechanism through which YTHDF1 recognizes Piezo2 and controls cardiac fibroblast autophagy and fibrosis through m6A-dependent modulation. Our findings provide new insights for the development of preventive measures for cardiac fibrosis.

RNA modification in normal hematopoiesis and hematologic malignancies.

N6-methyladenosine (m6A) is the most abundant RNA modification in eukaryotic cells. Previous studies have shown that m6A plays a critical role under both normal physiological and pathological conditions. Hematopoiesis and differentiation are highly regulated processes, and recent studies on m6A mRNA methylation have revealed how this modification controls cell fate in both normal and malignant hematopoietic states. However, despite these insights, a comprehensive understanding of its complex roles between normal hematopoietic development and malignant hematopoietic diseases remains elusive. This review first provides an overview of the components and biological functions of m6A modification regulators. Additionally, it highlights the origin, differentiation process, biological characteristics, and regulatory mechanisms of hematopoietic stem cells, as well as the features, immune properties, and self-renewal pathways of leukemia stem cells. Last, the article systematically reviews the latest research advancements on the roles and mechanisms of m6A regulatory factors in normal hematopoiesis and related malignant diseases. More importantly, this review explores how targeting m6A regulators and various signaling pathways could effectively intervene in the development of leukemia, providing new insights and potential therapeutic targets. Targeting m6A modification may hold promise for achieving more precise and effective leukemia treatments.

Systematic perturbation screens identify regulators of inflammatory macrophage states and a role for TNF mRNA m6A modification.

Macrophages exhibit remarkable functional plasticity, a requirement for their central role in tissue homeostasis. During chronic inflammation, macrophages acquire sustained inflammatory 'states' that contribute to disease, but there is limited understanding of the regulatory mechanisms that drive their generation. Here we describe a systematic functional genomics approach that combines genome-wide phenotypic screening in primary murine macrophages with transcriptional and cytokine profiling of genetic perturbations in primary human macrophages to uncover regulatory circuits of inflammatory states. This process identifies regulators of five distinct states associated with key features of macrophage function. Among these regulators, loss of the N6-methyladenosine (m6A) writer components abolishes m6A modification of TNF transcripts, thereby enhancing mRNA stability and TNF production associated with multiple inflammatory pathologies. Thus, phenotypic characterization of primary murine and human macrophages describes the regulatory circuits underlying distinct inflammatory states, revealing post-transcriptional control of TNF mRNA stability as an immunosuppressive mechanism in innate immunity.

Hepatitis B Virus X Protein Contributes to Hepatocellular Carcinoma via Upregulation of KIAA1429 Methyltransferase and mRNA m6A Hypermethylation of HSPG2/Perlecan.

Chronic hepatitis B virus (HBV) remains to be the most common risk factor of hepatocellular carcinoma (HCC). While previous work has primarily focussed on understanding the direct and indirect mechanisms of Hepatitis B virus X protein (HBx)-mediated hepatocarcinogenesis, from genetic and epigenetic perspectives, its influence on RNA modification mediated onset of liver malignancies is less well understood. This study explored the role of HBV-encoded HBx in altering the m6A methylome profile and its implications on the pathogenesis of HCC. We established HBx-expressing stable HCC cell lines, Huh7-HBx and HepG2-HBx, and explored the transcriptomic and epitranscriptomic profiles by RNA-seq and MeRIP-seq, respectively. Preliminary results suggest that HBx promotes liver cell proliferation, migration, survival and overall m6A methylation in HCC cells and is involved in modulating the extracellular matrix. We show that HBx mediates liver cell transformation by upregulating KIAA1429 methyltransferase. HBx also drives the expression and hypermethylation of the extracellular matrix protein HSPG2/Perlecan and promotes tumourigenesis. Furthermore, we observed a potential interaction between KIAA1429 and HSPG2 in HCC liver cancer cells and demands further investigation.

3-Deazaneplanocin A (DZNep): A Drug That Deserves a Second Look.

The emerging data compiled during the past five years on 3-deazaneplanocin (DZNep) provide compelling evidence to reevaluate this drug as a better alternative over the specific catalytic inhibitors of histone methyl transferases (HTMs). The indirect mechanism of DZNep via inhibition of AdoHcy-ase, once considered a liability due to possible side effects, has now shown to be rather beneficial as additional pathways targeted by DZNep are important contributors to its superior anticancer properties. Furthermore, DZNep has demonstrated the ability to induce proteasomal degradation of its target and reduce toxicity in combination with well-established antitumor therapies in animal models. In addition, DZNep has shown important effects in suppressing fibrosis and inflammation in liver, kidney, peritoneum, and airways. Finally, inhibition of mRNA m6A methylation by DZNep suppresses the synthesis of the viral genome in SARS-Cov-2 infection and promises to have important therapeutic value when combined with its potent antiviral efficacy and anti-inflammatory effects.

RNA m6A methyltransferase activator affects anxiety-related behaviours, monoamines and striatal gene expression in the rat.

Modification of mRNA by methylation is involved in post-transcriptional regulation of gene expression by affecting the splicing, transport, stability and translation of mRNA. Methylation of adenosine at N6 (m6A) is one of the most common and important cellular modification occurring in the mRNA of eukaryotes. Evidence that m6A mRNA methylation is involved in regulation of stress response and that its dysregulation may contribute to the pathogenesis of neuropsychiatric disorders is accumulating. We have examined the acute and subchronic (up to 18 days once per day intraperitoneally) effect of the first METTL3/METTL14 activator compound CHMA1004 (methyl-piperazine-2-carboxylate) at two doses (1 and 5 mg/kg) in male and female rats. CHMA1004 had a locomotor activating and anxiolytic-like profile in open field and elevated zero-maze tests. In female rats sucrose consumption and swimming in Porsolt's test were increased. Nevertheless, CHMA1004 did not exhibit strong psychostimulant-like properties: CHMA1004 had no effect on 50-kHz ultrasonic vocalizations except that it reduced the baseline difference between male and female animals, and acute drug treatment had no effect on extracellular dopamine levels in striatum. Subchronic CHMA1004 altered ex vivo catecholamine levels in several brain regions. RNA sequencing of female rat striata after subchronic CHMA1004 treatment revealed changes in the expression of a number of genes linked to dopamine neuron viability, neurodegeneration, depression, anxiety and stress response. Conclusively, the first-in-class METTL3/METTL14 activator compound CHMA1004 increased locomotor activity and elicited anxiolytic-like effects after systemic administration, demonstrating that pharmacological activation of RNA m6A methylation has potential for neuropsychiatric drug development.

FTO/IGF2BP2-mediated N6 methyladenosine modification in invasion and metastasis of thyroid carcinoma via CDH12.

Epigenetic reprogramming plays a critical role in cancer progression of cancer, and N6-methyladenosine (m6A) is the most common RNA modification in eukaryotes. The purpose of this study was to explore the related modification mode of m6A regulator construction and evaluate the invasion and migration of thyroid cancer. Our results showed that m6A levels were significantly increased in papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC) samples, which may have been induced by the down-regulation of demethylase fat mass and obesity-associated gene (FTO). Moreover, FTO inhibited PTC and ATC invasion and metastasis through the epithelial-to-mesenchymal transition (EMT) pathway in vivo and in vitro. Mechanistically, an m6A-mRNA epitranscriptomic microarray showed that Cadherin 12 (CDH12) is the key target gene mediated by FTO in an m6A-dependent manner. CDH12 promotes invasion and metastasis through the EMT pathway in thyroid cancer, both in vivo and in vitro. Furthermore, we found that insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is an important m6A reading protein, that regulates the stability of CDH12 mRNA and mediates EMT progression, thereby promoting the invasion and metastasis of PTC and ATC. Thus, FTO, IGF2BP2 and CDH12 may be effective therapeutic targets for PTC and ATC with significant invasion or distant metastasis. Schematic summary of FTO-IGF2BP2 axis in modulation of CDH12 mRNA m6A and upregulation of CDH12 expression in the invasion and metastasis of thyroid carcinoma.

Comprehensive analysis of the m6A demethylase FTO in endothelial dysfunction by MeRIP sequencing

N6-methyladenosine (m6A) is the most general post-transcriptional modification of eukaryotic mRNAs and long-stranded non-coding RNAs. In this process, It has been shown that FTO associates with the m6A mRNA demethylase and plays a role in diabetic vascular endothelial dysfunction. In the present study, we detected FTO protein expression in HUVECs by Western blot and found that FTO was highly expressed in all disease groups relative to the control group. To explore the mechanism of FTO in T2DM vasculopathy, we performed an analysis by methylated RNA immunoprecipitation sequencing (MeRIP-seq) to elucidate the role of aberrant m6A modification and mRNA expression in endothelial dysfunction. The results showed 202 overlapping genes with varying m6A modifications and varied mRNA expression, and GO and KEGG enrichment analysis revealed that these genes were predominantly enriched in pathways associated with T2DM complications and endothelial dysfunction. By an integrated analysis of MeRIP-seq and RNA-seq results, the IGV plots showed elevated kurtosis of downstream candidate gene modifications, which may be downstream targets for FTO to exercise biological functions. HOXA9 and PLAU mRNA expression levels were significantly down after FTO inhibition. In the current work, we set up a typological profile of the m6A genes among HUVECs as well as uncovered a hidden relationship between RNA methylation modifications for T2DM vasculopathy-associated genes. Taken together, this study indicates that endothelial functional impairment is present in T2DM patients and may be related to aberrant expression of FTO.

MAT2B regulates the protein level of MAT2A to preserve RNA N6-methyladenosine

MAT2B works together with MAT2A to synthesize S-Adenosyl methionine (SAM) as the primary methyl donor. MAT2B, despite lacking catalytic activity, exerts regulatory control over the enzymatic activity of MAT2A. In addition to the enzymatic activity regulation, we find that, in an NADP+-dependent manner, MAT2B binds and stabilizes MAT2A. Disruption of the cellular NADP+ remodels the protein level of MAT2A. The pentose phosphatase pathway regulates the level of MAT2A protein through the interaction of NADP+ with MAT2B. Additionally, MAT2B-MAT2A interaction regulates the mRNA m6A modification and stability. In liver tumors, the Mat2a mRNA level is elevated but the protein level is decreased by the restricted NADP+. Blocking the interaction between MAT2B and MAT2A by the keto diet can suppress liver tumor growth. These findings reveal that MAT2B is essential for regulating the protein levels of MAT2A and connecting SAM synthesis to mRNA m6A.

M6A/YTHDF2-mediated mRNA decay targets TGF-β signaling to suppress the quiescence acquisition of early postnatal mouse hippocampal NSCs.

Quiescence acquisition of proliferating neural stem cells (NSCs) is required to establish the adult NSC pool. The underlying molecular mechanisms are not well understood. Here, we showed that conditional deletion of the m6A reader Ythdf2, which promotes mRNA decay, in proliferating NSCs in the early postnatal mouse hippocampus elevated quiescence acquisition in a cell-autonomous fashion with decreased neurogenesis. Multimodal profiling of m6A modification, YTHDF2 binding, and mRNA decay in hippocampal NSCs identified shared targets in multiple transforming growth factor β (TGF-β)-signaling-pathway components, including TGF-β ligands, maturation factors, receptors, transcription regulators, and signaling regulators. Functionally, Ythdf2 deletion led to TGF-β-signaling activation in NSCs, suppression of which rescued elevated quiescence acquisition of proliferating hippocampal NSCs. Our study reveals the dynamic nature and critical roles of mRNA decay in establishing the quiescent adult hippocampal NSC pool and uncovers a distinct mode of epitranscriptomic control via co-regulation of multiple components of the same signaling pathway.

Progressive polyadenylation and m6A modification of Ighg1 mRNA maintain IgG1 antibody homeostasis in antibody-secreting cells

Antigen-specific antibodies are generated by antibody-secreting cells (ASCs). How RNA post-transcriptional modification affects antibody homeostasis remains unclear. Here, we found that mRNA polyadenylations and N6-methyladenosine (m6A) modifications maintain IgG1 antibody production in ASCs. IgG heavy-chain transcripts (Ighg) possessed a long 3' UTR with m6A sites, targeted by the m6A reader YTHDF1. B cell-specific deficiency of YTHDF1 impaired IgG production upon antigen immunization through reducing Ighg1 mRNA abundance in IgG1+ ASCs. Disrupting either the m6A modification of a nuclear-localized splicing intermediate Ighg1 or the nuclear localization of YTHDF1 reduced Ighg1 transcript stability. Single-cell RNA sequencing identified an ASC subset with excessive YTHDF1 expression in systemic lupus erythematosus patients, which was decreased upon therapy with immunosuppressive drugs. In a lupus mouse model, inhibiting YTHDF1-m6A interactions alleviated symptoms. Thus, we highlight a mechanism in ASCs to sustain the homeostasis of IgG antibody transcripts by integrating Ighg1 mRNA polyadenylation and m6A modification.

ALKBH5 promotes T-cell acute lymphoblastic leukemia growth via m6A-guided epigenetic inhibition of miR-20a-5p

This study investigates the role of ALKBH5-mediated m6A demethylation in T-cell acute lymphoblastic leukemia (T-ALL). T-ALL cell lines (HPB-ALL, MOLT4, Jurkat, CCRF-CEM) and human T cells were analyzed. CCRF-CEM and Jurkat cells were transfected with si-ALKBH5, miR-20a-5p-inhibitor, and pcDNA3.1-DDX5. The expression levels of ALKBH5, miR-20a-5p, and DDX5 in these cells were determined using qRT-PCR and Western blotting. Cell viability, proliferation, colony formation, and apoptosis were assessed using CCK-8, EdU staining, colony formation assay, and flow cytometry. mRNA m6A levels were quantified with an m6A RNA methylation detection reagent, and RNA immunoprecipitation was employed to measure the enrichment of DGCR8 and m6A on the primary transcript pri-miR-20a of miR-20a-5p. Dual-luciferase assay confirmed the binding relationship between miR-20a-5p and DDX5. Results showed that ALKBH5 and DDX5 were upregulated in T-ALL tissues and cells, whereas miR-20a-5p was downregulated. Silencing ALKBH5 inhibited T-ALL cell viability, colony formation, and proliferation, while promoting apoptosis. These effects were reversed by miR-20a-5p inhibition or DDX5 overexpression. ALKBH5 reduced the relative m6A level in T-ALL cells and decreased miR-20a-5p expression by reducing DGCR8 binding to pri-miR-20a-5p. miR-20a-5p suppressed DDX5 transcription. In conclusion, ALKBH5-mediated m6A demethylation decreases DGCR8 binding to pri-miR-20a, thereby repressing miR-20a-5p expression and enhancing DDX5 expression, ultimately inhibiting T-ALL cell apoptosis and promoting proliferation.

N6-Methyladenosine-mediated phase separation suppresses NOTCH1 expression and promotes mitochondrial fission in diabetic cardiac fibrosis.

N6-methyladenosine (m6A) modification of messenger RNA (mRNA) is crucial for liquid-liquid phase separation in mammals. Increasing evidence indicates that liquid-liquid phase separation in proteins and RNAs affects diabetic cardiomyopathy. However, the molecular mechanism by which m6A-mediated phase separation regulates diabetic cardiac fibrosis remains elusive. Leptin receptor-deficient mice (db/db), cardiac fibroblast-specific Notch1 conditional knockout (POSTN-Cre × Notch1flox/flox) mice, and Cre mice were used to induce diabetic cardiac fibrosis. Adeno-associated virus 9 carrying cardiac fibroblast-specific periostin (Postn) promoter-driven small hairpin RNA targeting Alkbh5, Ythdf2, or Notch1, and the phase separation inhibitor 1,6-hexanediol were administered to investigate their roles in diabetic cardiac fibrosis. Histological and biochemical analyses were performed to determine how Alkbh5 and Ythdf2 regulate Notch1 expression in diabetic cardiac fibrosis. NOTCH1 was reconstituted in ALKBH5- and YTHDF2-deficient cardiac fibroblasts and mouse hearts to study its effects on mitochondrial fission and diabetic cardiac fibrosis. Heart tissue samples from patients with diabetic cardiomyopathy were used to validate our findings. In mice with diabetic cardiac fibrosis, decreased Notch1 expression was accompanied by high m6A mRNA levels and mitochondrial fission. Fibroblast-specific deletion of Notch1 enhanced mitochondrial fission and cardiac fibroblast proliferation and induced diabetic cardiac fibrosis in mice. Notch1 downregulation was associated with Alkbh5-mediated m6A demethylation in the 3'UTR of Notch1 mRNA and elevated m6A mRNA levels. These elevated m6A levels in Notch1 mRNA markedly enhanced YTHDF2 phase separation, increased the recognition of m6A residues in Notch1 mRNA by YTHDF2, and induced Notch1 degradation. Conversely, epitranscriptomic downregulation rescues Notch1 expression, resulting in the opposite effects. Human heart tissues from patients with diabetic cardiomyopathy were used to validate the findings in mice with diabetic cardiac fibrosis. We identified a novel epitranscriptomic mechanism by which m6A-mediated phase separation suppresses Notch1 expression, thereby promoting mitochondrial fission in diabetic cardiac fibrosis. Our findings provide new insights for the development of novel treatment approaches for patients with diabetic cardiac fibrosis.

M6A mRNA methylation by METTL14 regulates early pancreatic cell differentiation.

N6-methyladenosine (m6A) is the most abundant chemical modification in mRNA and plays important roles in human and mouse embryonic stem cell pluripotency, maintenance, and differentiation. We have recently reported that m6A is involved in the postnatal control of β-cell function in physiological states and in type 1 and 2 diabetes. However, the precise mechanisms by which m6A acts to regulate the development of human and mouse pancreas are unexplored. Here, we show that the m6A landscape is dynamic during human pancreas development, and that METTL14, one of the m6A writer complex proteins, is essential for the early differentiation of both human and mouse pancreatic cells.

Spliceosomal vulnerability of MYCN-amplified neuroblastoma is contingent on PRMT5-mediated regulation of epitranscriptomic and metabolomic pathways

Approximately 50 % of poor prognosis neuroblastomas arise due to MYCN over-expression. We previously demonstrated that MYCN and PRMT5 proteins interact and PRMT5 knockdown led to apoptosis of MYCN-amplified (MNA) neuroblastoma. Here we evaluate the highly selective first-in-class PRMT5 inhibitor GSK3203591 and its in vivo analogue GSK3326593 as targeted therapeutics for MNA neuroblastoma. Cell-line analyses show MYCN-dependent growth inhibition and apoptosis, with approximately 200-fold greater sensitivity of MNA neuroblastoma lines. RNA sequencing of three MNA neuroblastoma lines treated with GSK3203591 reveal deregulated MYCN transcriptional programmes and altered mRNA splicing, converging on key regulatory pathways such as DNA damage response, epitranscriptomics and cellular metabolism. Stable isotope labelling experiments in the same cell lines demonstrate that glutamine metabolism is impeded following GSK3203591 treatment, linking with disruption of the MLX/Mondo nutrient sensors via intron retention of MLX mRNA. Interestingly, glutaminase (GLS) protein decreases after GSK3203591 treatment despite unchanged transcript levels. We demonstrate that the RNA methyltransferase METTL3 and cognate reader YTHDF3 proteins are lowered following their mRNAs undergoing GSK3203591-induced splicing alterations, indicating epitranscriptomic regulation of GLS; accordingly, we observe decreases of GLS mRNA m6A methylation following GSK3203591 treatment, and decreased GLS protein following YTHDF3 knockdown. In vivo efficacy of GSK3326593 is confirmed by increased survival of Th-MYCN mice, with drug treatment triggering splicing events and protein decreases consistent with in vitro data. Together our study demonstrates the PRMT5-dependent spliceosomal vulnerability of MNA neuroblastoma and identifies the epitranscriptome and glutamine metabolism as critical determinants of this sensitivity.

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.

Virtual Screening and Molecular Dynamics Simulation to Identify Inhibitors of the m6A-RNA Reader Protein YTHDC1

YTHDC1 (YTH domain containing 1), a crucial reader protein of N6-methyladenosine (m6A) mRNA, plays a critical role in various cellular functions and is considered a promising target for therapeutic intervention in acute myeloid leukemia and other cancers. In this study, we identified orthosteric small-molecule ligands for YTHDC1. Using a molecular docking approach, we screened the eMolecules database and recognized 15 top-ranked ligands. Subsequently, molecular dynamics simulations and MM/PBSA analysis were used to assess the stability and binding free energy of these potential hit compounds in complex with YTHDC1. Notably, five compounds with IDs of ZINC82121447, ZINC02170552, ZINC65274016, ZINC10763862, and ZINC02412146 exhibited high binding affinities and favorable binding free energies. The results also showed that these compounds formed strong hydrogen bonds with residues SER378, ASN363, and ASN367 and interacted with the aromatic cage of the YTHDC1 reader protein through TRP377, TRP428, and hydrophobic residue LEU439. To assess their viability as lead compounds, we conducted absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies to reveal promising features for these identified small molecules, shedding light on their pharmacokinetic and safety profiles.

The m6A writer KIAA1429 regulates photoaging progression via MFAP4-dependent collagen synthesis

BackgroundN6-Methyladenosine (m6A) methylation, a common form of RNA modification, play an important role in the pathogenesis of various diseases and in the ontogeny of organisms. Nevertheless, the precise function of m6A methylation in photoaging remains unknown.ObjectivesThis study aims to investigate the biological role and underlying mechanism of m6A methylation in photoaging.Methodsm6A dot blot, Real-time quantitative PCR (RT-qPCR), western blot and immunohistochemical (IHC) assays were employed to detect the m6A level and specific m6A methylase in ultraviolet ray (UVR)-induced photoaging tissue. The profile of m6A-tagged mRNA was identified by methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-seq analysis. Finally, we investigated the regulatory mechanism of KIAA1429 by MeRIP-qPCR, RNA knockdown and immunofluorescence assay.Resultsm6A levels were increased in photoaging and were closely associated with the upregulation of KIAA1429 expression. 1331 differentially m6A methylated genes were identified in the UVR group compared with the control group, of which 1192 (90%) were hypermethylated. Gene ontology analysis showed that genes with m6A hypermethylation and mRNA downregulation were mainly involved in extracellular matrix metabolism and collagen metabolism-related processes. Furthermore, KIAA1429 knockdown abolished the downregulation of TGF-bRII and upregulation of MMP1 in UVR-irradiated human dermal fibroblasts (HDFs). Mechanically, we identified MFAP4 as a target of KIAA1429-mediated m6A modification and KIAA1429 might suppress collagen synthesis through an m6A-MFAP4-mediated process.ConclusionsThe increased expression of KIAA1429 hinders collagen synthesis during UVR-induced photoaging, suggesting that KIAA1429 represents a potential candidate for targeted therapy to mitigate UVR-driven photoaging.

M6A mRNA methylation in brown fat regulates systemic insulin sensitivity via an inter-organ prostaglandin signaling axis independent of UCP1

Brown adipose tissue (BAT) regulates systemic metabolism by releasing signaling lipids. N6-methyladenosine (m6A) is the most prevalent and abundant post-transcriptional mRNA modification and has been reported to regulate BAT adipogenesis and energy expenditure. Here, we demonstrate that the absence of m6A methyltransferase-like 14 (METTL14) modifies the BAT secretome to improve systemic insulin sensitivity independent of UCP1. Using lipidomics, we identify prostaglandin E2 (PGE2) and prostaglandin F2a (PGF2a) as BAT-secreted insulin sensitizers. PGE2 and PGF2a inversely correlate with insulin sensitivity in humans and protect mice from high-fat-diet-induced insulin resistance by suppressing specific AKT phosphatases. Mechanistically, METTL14-mediated m6A promotes the decay of PTGES2 and CBR1, the genes encoding PGE2 and PGF2a biosynthesis enzymes, in brown adipocytes via YTHDF2/3. Consistently, BAT-specific knockdown of Ptges2 or Cbr1 reverses the insulin-sensitizing effects in M14KO mice. Overall, these findings reveal a novel biological mechanism through which m6A-dependent regulation of the BAT secretome regulates systemic insulin sensitivity.

Epitranscriptomic regulation of lipid oxidation and liver fibrosis via ENPP1 mRNA m6A modification

BackgroundDysregulated lipid oxidation occurs in several pathological processes characterized by cell proliferation and migration. Nonetheless, the molecular mechanism of lipid oxidation is not well appreciated in liver fibrosis, which is accompanied by enhanced fibroblast proliferation and migration.MethodsWe investigated the causes and consequences of lipid oxidation in liver fibrosis using cultured cells, animal models, and clinical samples.ResultsIncreased ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP1) expression caused increased lipid oxidation, resulting in the proliferation and migration of hepatic stellate cells (HSCs) that lead to liver fibrosis, whereas fibroblast-specific ENPP1 knockout reversing these results. Elevated ENPP1 and N6-methyladenosine (m6A) levels were associated with high expression of Wilms tumor 1 associated protein (WTAP). Mechanistically, WTAP-mediated m6A methylation of the 3'UTR of ENPP1 mRNA and induces its translation dependent of YTH domain family proteins 1 (YTHDF1). Additionally, ENPP1 could interact with hypoxia inducible lipid droplet associated (HILPDA) directly; overexpression of ENPP1 further recruits HILPDA-mediated lipid oxidation, thereby promotes HSCs proliferation and migration, while inhibition of ENPP1 expression produced the opposite effect. Clinically, increased expression of WTAP, YTHDF1, ENPP1, and HILPDA, and increased m6A mRNA content, enhanced lipid oxidation, and increased collagen deposition in human liver fibrosis tissues.ConclusionsWe describe a novel mechanism in which WTAP catalyzes m6A methylation of ENPP1 in a YTHDF1-dependent manner to enhance lipid oxidation, promoting HSCs proliferation and migration and liver fibrosis.Graphical abstract