Methionine-SAM metabolism-dependent ubiquinone synthesis is crucial for ROS accumulation in ferroptosis induction.

Ferroptosis is a cell death modality in which iron-dependent lipid peroxides accumulate on cell membranes. Cysteine, a limiting substrate for the glutathione system that neutralizes lipid peroxidation and prevents ferroptosis, can be converted by cystine reduction or synthesized from methionine. However, accumulating evidence shows methionine-based cysteine synthesis fails to effectively rescue intracellular cysteine levels upon cystine deprivation and is unable to inhibit ferroptosis. Here, we report that methionine-based cysteine synthesis is tissue-specific. Unexpectedly, we find that rather than inhibiting ferroptosis, methionine in fact plays an essential role during cystine deprivation-induced ferroptosis. Methionine-derived S-adenosylmethionine (SAM) contributes to methylation-dependent ubiquinone synthesis, which leads to lipid peroxides accumulation and subsequent ferroptosis. Moreover, SAM supplementation synergizes with Imidazole Ketone Erastin in a tumor growth suppression mouse model. Inhibiting the enzyme that converts methionine to SAM protects heart tissue from Doxorubicin-induced and ferroptosis-driven cardiomyopathy. This study broadens our understanding about the intersection of amino acid metabolism and ferroptosis regulation, providing insight into the underlying mechanisms and suggesting the methionine-SAM axis is a promising therapeutic strategy to treat ferroptosis-related diseases.

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.

Decoding Substrate Selectivity of an Archaeal RlmCD-like Methyltransferase Through Its Salient Traits.

5-Methyluridine (m5U) rRNA modifications frequently occur at U747 and U1939 (Escherichia coli numbering) in domains II and IV of the 23S rRNA in Gram-negative bacteria, with the help of S-adenosyl-l-methionine (SAM)-dependent rRNA methyltransferases (MTases), RlmC and RlmD, respectively. In contrast, Gram-positive bacteria utilize a single SAM-dependent rRNA MTase, RlmCD, to modify both corresponding sites. Notably, certain archaea, specifically within the Thermococcales group, have been found to possess two genes encoding SAM-dependent archaeal (tRNA and rRNA) m5U (Arm5U) MTases. Among these, a tRNA-specific Arm5U MTase (PabTrmU54) has already been characterized. This study focused on the structural and functional characterization of the rRNA-specific Arm5U MTase from the hyperthermophilic archaeon Pyrococcus horikoshii (PhRlmCD). An in-depth structural examination revealed a dynamic hinge movement induced by the replacement of the iron-sulfur cluster with disulfide bonds, obstructing the substrate-binding site. It revealed distinctive characteristics of PhRlmCD, including elongated positively charged loops in the central domain and rotational variations in the TRAM domain, which influence substrate selectivity. Additionally, the results suggested that two potential mini-rRNA fragments interact in a similar manner with PhRlmCD at a positively charged cleft at the interface of domains and facilitate dual MTase activities akin to the protein RlmCD. Altogether, these observations showed that Arm5U MTases originated from horizontal gene transfer events, most likely from Gram-positive bacteria.

Closing in on human methylation-the versatile family of seven-ß-strand (METTL) methyltransferases.

Methylation is a common biochemical reaction, and a number of methyltransferase (MTase) enzymes mediate the various methylation events occurring in living cells. Almost all MTases use the methyl donor S-adenosylmethionine (AdoMet), and, in humans, the largest group of AdoMet-dependent MTases are the so-called seven-ß-strand (7BS) MTases. Collectively, the 7BS MTases target a wide range of biomolecules, i.e. nucleic acids and proteins, as well as several small metabolites and signaling molecules. They play essential roles in key processes such as gene regulation, protein synthesis and metabolism, as well as neurotransmitter synthesis and clearance. A decade ago, roughly half of the human 7BS MTases had been characterized experimentally, whereas the remaining ones merely represented hypothetical enzymes predicted from bioinformatics analysis, many of which were denoted METTLs (METhylTransferase-Like). Since then, considerable progress has been made, and the function of > 80% of the human 7BS MTases has been uncovered. In this review, I provide an overview of the (estimated) 120 human 7BS MTases, grouping them according to substrate specificities and sequence similarity. I also elaborate on the challenges faced when studying these enzymes and describe recent major advances in the field.

Fungal L-Methionine Biosynthesis Pathway Enzymes and Their Applications in Various Scientific and Commercial Fields.

L-methionine (L-Met) is one of the nine proteinogenic amino acids essential for humans since, in human cells, there are no complete pathways for its biosynthesis from simple precursors. L-Met plays a crucial role in cellular function as it is required for proper protein synthesis, acting as an initiator. Additionally, this amino acid participates in various metabolic processes and serves as a precursor for the synthesis of S-adenosylmethionine (AdoMet), which is involved in the methylation of DNA molecules and phospholipids, as well as in maintaining genome stability. Due to its importance, fungal L-methionine biosynthesis pathway enzymes are being intensively studied. This review presents the current state of the art in terms of their cellular function, usefulness as molecular markers, antifungal targets, or industrial approaches.

S-Adenosylmethionine Inhibits the Proliferation of Retinoblastoma Cell Y79, Induces Apoptosis and Cell Cycle Arrest of Y79 Cells by Inhibiting the Wnt2/ß-Catenin Pathway.

Retinoblastoma is one of the most common primary intraocular malignancies in young children. Traditional treatment methods such as chemotherapy often come with significant adverse effects, such as hearing loss, cognitive impairment, and vision loss. Therefore, there is an urgent need to explore a novel therapeutic drug that is both effective and safe. S-adenosylmethionine (SAM) is a natural compound known to exhibit anti-proliferative effects in various cancer cell lines. However, to date, no studies investigated the effects of SAM on retinoblastoma cells and its potential mechanisms of action. Therefore, this study aims to investigate the impact of SAM on retinoblastoma cells and explore its possible mechanisms of action, with the hope of providing new insights into the treatment of this disease. The optimal concentration of SAM was determined using the Cell Counting Kit-8 assay. The effect of SAM on retinoblastoma proliferation was assessed using the 5-ethynyl-2'-deoxyuridine cell proliferation assay. Y79 cells were subjected to hematoxylin and eosin stain and electron microscopy to observe any morphological changes induced by SAM. The stages of SAM's action on the retinoblastoma cell cycle and its apoptotic effects were measured using flow cytometry. The apoptotic effect of SAM on retinoblastoma was further confirmed using the TUNEL assay. Differential expression of related genes was detected through RT-PCR. In vivo subcutaneous tumor formation in nude mice and immunohistochemistry were employed to validate the effect of SAM on retinoblastoma-related phenotypes. Western blotting was conducted to investigate whether SAM modulated retinoblastoma-related phenotypes via the Wnt2/ß-catenin pathway. SAM arrested the cell cycle of retinoblastoma at the G1 phase, induced apoptosis of retinoblastoma cells through the Wnt2/ß-catenin pathway, and affected their morphology and even ultrastructure. In addition, in vitro and in vivo experiments demonstrated that SAM had an oncogenic effect on retinoblastoma. In this study, we verify in vitro and in vivo whether SAM inhibits the proliferation of retinoblastoma cell Y7, induces apoptosis and cell cycle arrest of Y79 cells by inhibiting the Wnt2/ß-catenin pathway, and affects the morphology and structure of retinoblastoma cell Y79.

Linker-Mediated Inactivation of the SAM-II Domain in the Tandem SAM-II/SAM-V Riboswitch.

Tandem SAM-II/SAM-V riboswitch belongs to a class of riboswitches found in the marine bacterium 'Candidatus Pelagibacter ubique'. Previous studies have demonstrated that these riboswitches have the potential for digital modulation of gene expression at both the transcriptional and translational levels. In this study, we investigate the conformational changes in the tandem SAM-II/SAM-V riboswitch binding to S-adenosylmethionine (SAM) using selective 2'-hydroxyl acylation analyzed by the primer extension (SHAPE) assay, small-angle X-ray scattering (SAXS), and oligos depressing probing. Our findings reveal that the linker between SAM-II/SAM-V aptamers blocks the SAM response of the SAM-II domain. This result proposes a new mechanism for gene expression regulation, where the ligand-binding functions of tandem riboswitches can be selectively masked or released through a linker.

Characterizations of Protein Arginine Deiminase 1 as a Substrate of NTMT1: Implications of Nα-Methylation in Protein Stability and Interaction.

α-N-Methylation (Nα-methylation), catalyzed by protein N-terminal methyltransferases (NTMTs), constitutes a crucial post-translational modification involving the transfer of a methyl group from S-adenosyl-l-methionine (SAM) to the Nα-terminal amino group of substrate proteins. NTMT1/2 are known to methylate canonical Nα sequences, such as X-P-K/R. With over 300 potential human protein substrates, only a small fraction has been validated, and even less is known about the functions of Nα-methylation. This study delves into the characterizations of protein arginine deiminase 1 (PAD1) as a substrate of NTMT1. By employing biochemical and cellular assays, we demonstrated NTMT1-mediated Nα-methylation of PAD1, leading to an increase in protein half-life and the modulation of protein-protein interactions in HEK293T cells. The methylation of PAD1 appears nonessential to its enzymatic activity or cellular localization. Proteomic studies revealed differential protein interactions between unmethylated and Nα-methylated PAD1, suggesting a regulatory role for Nα-methylation in modulating PAD1's protein-protein interactions. These findings shed light on the intricate molecular mechanisms governing PAD1 function and expand our knowledge of Nα-methylation in regulating protein function.

Modulation of m6A RNA modification by DAP3 in cancer cells.

N6-methyladenosine (m6A) RNA methylation is a prevalent RNA modification that significantly impacts RNA metabolism and cancer development. Maintaining the global m6A levels in cancer cells relies on RNA accessibility to methyltransferases and the availability of the methyl donor S-adenosylmethionine (SAM). Here, we reveal that death associated protein 3 (DAP3) plays a crucial role in preserving m6A levels through two distinct mechanisms. First, although DAP3 is not a component of the m6A writer complex, it directly binds to m6A target regions, thereby facilitating METTL3 binding. Second, DAP3 promotes MAT2A's last intron splicing, increasing MAT2A protein, cellular SAM, and m6A levels. Silencing DAP3 hinders tumorigenesis, which can be rescued by MAT2A overexpression. This evidence suggests DAP3's role in tumorigenesis, partly through m6A regulation. Our findings unveil DAP3's complex role as an RNA-binding protein and tumor promoter, impacting RNA processing, splicing, and m6A modification in cancer transcriptomes.

Functional Validation of SAM Riboswitch Element A from Listeria monocytogenes.

SreA is one of seven candidate S-adenosyl methionine (SAM) class I riboswitches identified in Listeria monocytogenes, a saprophyte and opportunistic foodborne pathogen. SreA precedes genes encoding a methionine ATP-binding cassette (ABC) transporter, which imports methionine and is presumed to regulate transcription of its downstream genes in a SAM-dependent manner. The proposed role of SreA in controlling the transcription of genes encoding an ABC transporter complex may have important implications for how the bacteria senses and responds to the availability of the metabolite SAM in the diverse environments in which L. monocytogenes persists. Here we validate SreA as a functional SAM-I riboswitch through ligand binding studies, structure characterization, and transcription termination assays. We determined that SreA has both a structure and SAM binding properties similar to those of other well-characterized SAM-I riboswitches. Despite the apparent structural similarities to previously described SAM-I riboswitches, SreA induces transcription termination in response to comparatively lower (nanomolar) ligand concentrations. Furthermore, SreA is a leaky riboswitch that permits some transcription of the downstream gene even in the presence of millimolar SAM, suggesting that L. monocytogenes may "dampen" the expression of genes for methionine import but likely does not turn them "OFF".

S-Adenosylmethionine (SAMe) for Central Nervous System Health: A Systematic Review.

Background/Objectives: S-adenosylmethionine (SAMe) is a natural compound used to improve mood-related symptoms. Our aim was to determine the efficacy, safety, and optimal dose of SAMe in Central Nervous System (CNS) signs (e.g., mood, behavior). Methods: We conducted a PRISMA-based systematic review by searching PubMed, CINAHL, and Web of Science using MeSH search terms. Articles were independently reviewed by two researchers (with a third resolving conflicts) during title/abstract screening and full-text review. Data were extracted in the same approach, with a quality assessment of included articles. Results: Out of 1881 non-duplicated studies, 36 were included in the review focusing on CNS signs (mood, behavior, sleep). Most studies (n = 32) achieved a 4 or 5 out of 5 points, indicating high study quality. Overall, SAMe was effective in 24 of 36 studies, with adverse events mostly consisting of mild, transient gastrointestinal disturbances. Conclusions: Many patients in these studies did experience improvements in CNS signs from using SAMe alone or in combination with existing therapy. However, future studies are needed to further understand the long-term effects of SAMe in the CNS.

Inhibition of MAT2A Impairs Skeletal Muscle Repair Function.

The regenerative capacity of muscle, which primarily relies on anabolic processes, diminishes with age, thereby reducing the effectiveness of therapeutic interventions aimed at treating age-related muscle atrophy. In this study, we observed a decline in the expression of methionine adenosine transferase 2A (MAT2A), which synthesizes S-adenosylmethionine (SAM), in the muscle tissues of both aged humans and mice. Considering MAT2A's critical role in anabolism, we hypothesized that its reduced expression contributes to the impaired regenerative capacity of aging skeletal muscle. Mimicking this age-related reduction in the MAT2A level, either by reducing gene expression or inhibiting enzymatic activity, led to inhibiting their differentiation into myotubes. In vivo, inhibiting MAT2A activity aggravated BaCl2-induced skeletal muscle damage and decreased the number of satellite cells, whereas supplementation with SAM improved these effects. RNA-sequencing analysis further revealed that the Fas cell surface death receptor (Fas) gene was upregulated in Mat2a-knockdown C2C12 cells. Suppressing MAT2A expression or activity elevated Fas protein levels and increased the proportion of apoptotic cells. Additionally, inhibition of MAT2A expression or activity increased p53 expression. In conclusion, our findings demonstrated that impaired MAT2A expression or activity compromised the regeneration and repair capabilities of skeletal muscle, partially through p53-Fas-mediated apoptosis.

Fused radical SAM and αKG-HExxH domain proteins contain a distinct structural fold and catalyse cyclophane formation and ß-hydroxylation.

Two of nature's recurring binding motifs in metalloproteins are the CxxxCxxC motif in radical SAM enzymes and the 2-His-1-carboxylate motif found both in zincins and α-ketoglutarate and non-haem iron enzymes. Here we show the confluence of these two domains in a single post-translational modifying enzyme containing an N-terminal radical S-adenosylmethionine domain fused to a C-terminal 2-His-1-carboxylate (HExxH) domain. The radical SAM domain catalyses three-residue cyclophane formation and is the signature modification of triceptides, a class of ribosomally synthesized and post-translationally modified peptides. The HExxH domain is a defining feature of zinc metalloproteases. Yet the HExxH motif-containing domain studied here catalyses ß-hydroxylation and is an α-ketoglutarate non-haem iron enzyme. We determined the crystal structure for this HExxH protein at 2.8 Å, unveiling a distinct structural fold, thus expanding the family of α-ketoglutarate non-haem iron enzymes with a class that we propose to name αKG-HExxH. αKG-HExxH proteins represent a unique family of ribosomally synthesized and post-translationally modified peptide modifying enzymes that can furnish opportunities for genome mining, synthetic biology and enzymology.

ß-glucans, SAM, and GSH fluctuations in barley anther tissue culture conditions affect regenerants' DNA methylation and GPRE.

BACKGROUND: Microspore embryogenesis is a process that produces doubled haploids in tissue culture environments and is widely used in cereal plants. The efficient production of green regenerants requires stresses that could be sensed at the level of glycolysis, followed by the Krebs cycle and electron transfer chain. The latter can be affected by Cu(II) ion concentration in the induction media acting as cofactors of biochemical reactions, indirectly influencing the production of glutathione (GSH) and S-adenosyl-L-methionine (SAM) and thereby affecting epigenetic mechanisms involving DNA methylation (demethylation-DM, de novo methylation-DNM). The conclusions mentioned were acquired from research on triticale regenerants, but there is no similar research on barley. In this way, the study looks at how DNM, DM, Cu(II), SAM, GSH, and ß-glucan affect the ability of green plant regeneration efficiency (GPRE). RESULTS: The experiment involved spring barley regenerants obtained through anther culture. Nine variants (trials) of induction media were created by adding copper (CuSO4: 0.1; 5; 10 µM) and silver salts (AgNO3: 0; 10; 60 µM), with varying incubation times for the anthers (21, 28, and 35 days). Changes in DNA methylation were estimated using the DArTseqMet molecular marker method, which also detects cytosine methylation. Phenotype variability in ß-glucans, SAM and GSH induced by the nutrient treatments was assessed using tentative assignments based on the Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The effectiveness of green plant regeneration ranged from 0.1 to 2.91 plants per 100 plated anthers. The level of demethylation ranged from 7.61 to 32.29, while de novo methylation reached values ranging from 6.83 to 32.27. The paper demonstrates that the samples from specific in vitro conditions (trials) formed tight groups linked to the factors contributing to the two main components responsible for 55.05% of the variance (to the first component DNM, DM, to the second component GSH, ß-glucans, Cu(II), GPRE). CONCLUSIONS: We can conclude that in vitro tissue culture conditions affect biochemical levels, DNA methylation changes, and GPRE. Increasing Cu(II) concentration in the IM impacts the metabolism and DNA methylation, elevating GPRE. Thus, changing Cu(II) concentration in the IM is fair to expect to boost GPRE.

A continuous fluorescence assay to measure nicotianamine synthase activity.

S-adenosylmethionine (SAM) is most widely known as the biological methylating agent of methyltransferases and for generation of radicals by the iron-sulfur dependent Radical SAM enzymes. SAM also serves as a substrate in biosynthetic reactions that harvest the aminobutyrate moiety of the methionine, producing methylthioadenosine as a co-product. These reactions are found in the production of polyamines such as spermine, siderophores derived from nicotianamine, and opine metallophores staphylopine and pseudopaline, among others. This procedure defines a highly sensitive, continuous fluorescence assay for the determination of steady state kinetic parameters for enzymes that generate the co-product methylthioadenosine.

Structural and functional characterization of archaeal DIMT1 unveils distinct protein dynamics essential for efficient catalysis.

Dimethyladenosine transferase 1 (DIMT1), an ortholog of bacterial KsgA is a conserved protein that assists in ribosome biogenesis by modifying two successive adenosine bases near the 3' end of small subunit (SSU) rRNA. Although KsgA/DIMT1 proteins have been characterized in bacteria and eukaryotes, they are yet unexplored in archaea. Also, their dynamics are not well understood. Here, we structurally and functionally characterized the apo and holo forms of archaeal DIMT1 from Pyrococcus horikoshii. Wild-type protein and mutants were analyzed to capture different transition states, including open, closed, and intermediate states. This study reports a unique inter-domain movement that is needed for substrate (RNA) positioning in the catalytic pocket, and is only observed in the presence of the cognate cofactors S-adenosyl-L-methionine (SAM) or S-adenosyl-L-homocysteine (SAH). The binding of the inhibitor sinefungine, an analog of SAM or SAH, to archaeal DIMT1 blocks the catalytic pocket and renders the enzyme inactive.

Structural Basis of Substrate Recognition by the Postmitosane Modification Enzyme MitM in Mitomycin Biosynthesis.

Mitomycins make up a class of natural molecules produced by Streptomyces with strong antibacterial and antitumor activities. MitM is a key postmitosane modification enzyme involved in mitomycin biosynthesis in Streptomyces caespitosus. This protein was previously suggested to catalyze the aziridinium methylation of mitomycin A and the mitomycin intermediate 9a-demethyl-mitomycin A as an N-methyltransferase. The structural basis for MitM to recognize cofactor S-adenosyl-l-methionine (SAM) and substrate mitomycin A is unknown. Here, we determined the crystal structures of apo-MitM and MitM-mitomycin A-S-adenosylhomocysteine (SAH) ternary complexes with resolutions of 2.23 and 2.80 Å, respectively. We found that MitM adopts a class I SAM-dependent methyltransferase fold and forms a homodimer in solution. Conformational changes in a series of residues involved in the formation of active pockets assist MitM in binding SAH and mitomycin A. In particular, the 28ALGAASLGE36 loop changes most significantly. When mitomycin A binds, the bending direction of this loop is reversed, changing the entrance of the active site from open to closed. This study provides structural insights into MitM's involvement in the postmitosane stage of mitomycin biosynthesis and provides a template for the engineering of methyltransferases.

Deciphering the SAM- and metal-dependent mechanism of O-methyltransferases in cystargolide and belactosin biosynthesis: A structure-activity relationship study.

Cystargolides and belactosins are natural products with a distinct dipeptide structure and an electrophilic ß-lactone warhead. They are known to inhibit proteases such as the proteasome or caseinolytic protease P, highlighting their potential in treating cancers and neurodegenerative diseases. Recent genetic analyses have shown homology between the biosynthetic pathways of the two inhibitors. Here, we characterize the O-methyltransferases BelI and CysG, which catalyze the initial step of ß-lactone formation. Employing techniques such as crystallography, computational analysis, mutagenesis, and activity assays, we identified a His-His-Asp (HHD) motif in the active sites of the two enzymes, which is crucial for binding a catalytically active calcium ion. Our findings thus elucidate a conserved divalent metal-dependent mechanism in both biosynthetic pathways that distinguish BelI and CysG from previously characterized O-methyltransferases.

Targeting Divergent Pathways in the Nutritional Management of Depression.

The nutritional management of depression has long been discussed, due to the perceived benefit of a nutritional product having less side effects than pharmaceutical agents. Candidate nutrients for managing depression include vitamin D, B vitamins, tryptophan, branch chain amino acids, probiotics, omega-3 fatty acids, folate/methylfolate (also known as vitamin B9), and s-adenosylmethionine. This paper provides a narrative review of three nutrients which have significant scientific support for the management of depression. A deficiency in each nutrient is associated with depression, and interventional studies indicate that the correction of the nutritional deficiency may provide clinical benefit. We present epidemiological evidence, a mechanistic explanation and a review of interventional studies for these nutrients. Finally, relevant nutritional guidelines are presented with their conclusion for the role of each nutrient in the management of depression.

One-carbon metabolism supports S-adenosylmethionine and m6A methylation to control the osteogenesis of bone marrow stem cells and bone formation.

The skeleton is a metabolically active organ undergoing continuous remodeling initiated by bone marrow stem cells (BMSCs). Recent research has demonstrated that BMSCs adapt the metabolic pathways to drive the osteogenic differentiation and bone formation, but the mechanism involved remains largely elusive. Here, using a comprehensive targeted metabolome and transcriptome profiling, we revealed that one-carbon metabolism was promoted following osteogenic induction of BMSCs. Methotrexate (MTX), an inhibitor of one-carbon metabolism that blocks S-adenosylmethionine (SAM) generation, led to decreased N6-methyladenosine (m6A) methylation level and inhibited osteogenic capacity. Increasing intracellular SAM generation through betaine addition rescued the suppressed m6A content and osteogenesis in MTX-treated cells. Using S-adenosylhomocysteine (SAH) to inhibit the m6A level, the osteogenic activity of BMSCs was consequently impeded. We also demonstrated that the pro-osteogenic effect of m6A methylation mediated by one-carbon metabolism could be attributed to HIF-1α and glycolysis pathway. This was supported by the findings that dimethyloxalyl glycine rescued the osteogenic potential in MTX-treated and SAH-treated cells by upregulating HIF-1α and key glycolytic enzymes expression. Importantly, betaine supplementation attenuated MTX-induced m6A methylation decrease and bone loss via promoting the abundance of SAM in rat. Collectively, these results revealed that one-carbon metabolite SAM was a potential promoter in BMSC osteogenesis via the augmentation of m6A methylation, and the cross talk between metabolic reprogramming, epigenetic modification, and transcriptional regulation of BMSCs might provide strategies for bone regeneration.

The bone is a self-renewing tissue that continues to reshape throughout life. Bone marrow mesenchymal stem cells (BMSCs) are essential for bone homeostasis as they are capable of osteogenic differentiation. Recent evidence suggests that BMSCs drive the osteogenic differentiation through metabolic reprogramming, but the mechanism remains unclear. In this paper, we explored the metabolic alteration following osteogenic induction of BMSCs and found that one-carbon metabolism was obviously promoted in this process. The underlining mechanisms of the osteogenic potential driven by one-carbon metabolism seem to be its contribution on N6-methyladenosine (m6A) methylation and consequent glycolysis level by providing methyl donor. We demonstrated that one-carbon metabolism-mediated m6A methylation was a potential promoter in BMSC osteogenesis, and metabolic-epigenetic coupling might provide novel therapeutic targets for bone regeneration.