Search Results (62)

Cardiovascular disease causes the largest number of deaths across the world. The weak regenerative ability of adult hearts originates from limited cell proliferation and polyploidization of postnatal cardiomyocytes, which severely hinders tissue repair after myocardial injury. Fetal development represents a critical window during which maternal physiological and metabolic status can shape long-term offspring cardiac structure and function. Maternal exercise represents a safe nonpharmacological prenatal intervention that confers long-term benefits to offspring health. Available evidence indicates that maternal exercise enhances placental apelin secretion and elevates α-ketoglutarate (α-KG) levels in fetal brown adipose tissue, liver, and skeletal muscle. The apelin and α-KG signaling cascade participates in epigenetic regulation and confers protective effects on offspring metabolic health. Independent animal experiments have further validated that supplementation with either apelin or α-KG alleviates myocardial infarction (MI)-induced cardiac injury in adult mice, with α-KG showing direct evidence of reactivating cardiomyocyte proliferation. Nevertheless, it remains poorly elucidated whether maternal exercise could modulate fetal cardiomyocyte proliferative capacity in offspring through apelin- or α-KG-associated signaling. This narrative review integrates current evidence and proposes a testable framework in which maternal exercise influences fetal cardiac growth and regenerative potential through placental, metabolic, and epigenetic signaling. Because direct evidence remains limited, this model should be regarded as a hypothesis that requires further experimental validation. Full article

Glutamate dehydrogenase (GLUD1) links glutamine metabolism and redox regulation, yet its prognostic and functional relevance across different glioma subtypes warrants further study. Here, we show that GLUD1 expression was inversely associated with tumor grade and positively associated with survival across glioma subtypes, a relationship not fully recapitulated by broader glutaminolysis-related gene signatures. To investigate the consequences of GLUD1 inhibition, we treated endogenous IDH-mutant and IDH-wildtype glioma cell lines with the reported GLUD1 inhibitor R162. GLUD1 inhibition reduced viability in all cell lines tested. This effect was not rescued by α-ketoglutarate (α-KG) supplementation, indicating that impaired tricarboxylic acid (TCA) cycle anaplerosis was not the primary mechanism underlying GLUD1 dependency. Instead, GLUD1 inhibition caused intracellular glutamate accumulation, increased reactive oxygen species (ROS), γ-H2AX induction, and elevated intracellular calcium, while complementary in silico analyses predicted disruption of mitochondrial membrane potential following R162 exposure. Together, these findings indicate that GLUD1 inhibition induces metabolic and redox stress associated with disrupted glutamate and calcium homeostasis and DNA damage. Our findings distinguish the favorable prognostic value of GLUD1 expression from the cellular vulnerability revealed by its inhibition, supporting further investigations of GLUD1 as both a prognostic biomarker and potential therapeutic target in glioma. Full article

Statins are widely used lipid-lowering agents for the prevention and treatment of cardiovascular disease. Atorvastatin, one of the most frequently used statins, was reported to influence mitochondrial function, including the regulation of mitochondrial enzyme activity. Our recent study demonstrated that short-term treatment with atorvastatin effectively counteracted the alterations in α-ketoglutarate dehydrogenase (α-KGDH) induced by a high-cholesterol diet. Since α-KGDH and isocitrate dehydrogenase (IDH) together with glutamate dehydrogenase (GDH) are functionally interconnected, we hypothesized that atorvastatin modulates their activity in the brain. The study aimed to evaluate the effect of short-term atorvastatin treatment on cerebral mitochondrial dehydrogenases α-KGDH, IDH and GDH in hypercholesterolemic rats. Atorvastatin at dose 20 mg/kg b·wt/day (HC+A, n = 8) or vehicle (HC, n = 8) were administered to HC rats for 3 weeks. The control group was fed a standard diet (ST, n = 8). α-KGDH activity and relative protein abundance of its subunits were evaluated. Similarly, IDH and GDH activities as well as their relative protein levels were determined. In addition, the level of cerebral glutamate was measured. The study showed that hypercholesterolemia induced elevation of α-KGDH and IDH activities and reduction in GDH activity and glutamate level. Treatment with atorvastatin mitigated these metabolic disturbances, highlighting its potentially favorable effect in the brain. Full article

N-acetylornithine aminotransferase (AcOAT) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that catalyzes a key transamination step in arginine biosynthesis. In cyanobacteria, arginine metabolism is closely associated with nitrogen assimilation and storage, yet biochemical information on cyanobacterial AcOATs remains limited. In this study, the AcOAT encoded by the cce_3094 gene from Crocosphaera subtropica ATCC 51142 (CsAcOAT) was cloned, heterologously expressed, purified, and systematically characterized. Recombinant CsAcOAT was obtained as a soluble protein with an apparent molecular mass of approximately 43 kDa. Steady-state kinetic analysis showed that CsAcOAT catalyzed transamination between N-acetylornithine (AcOrn) and α-ketoglutarate (α-KG), with apparent K_M values of 0.17 ± 0.03 mM for AcOrn and 0.020 ± 0.003 mM for α-KG, indicating a higher affinity for α-KG. The enzyme exhibited optimal activity at pH 8.5 and 30 °C, retained relatively high activity over a broad temperature range of 0–50 °C, and was activated by Zn²⁺ and Co²⁺ but inhibited by Ni²⁺. Structural analysis based on homology modeling, molecular docking, and molecular dynamics simulations suggested a conserved PLP-dependent aminotransferase fold and a stable binding mode for the PLP-AcOrn complex in the active-site pocket. Site-directed mutagenesis further demonstrated that Gly114, Asp239, Lys268, and Thr296 are indispensable for catalytic activity, whereas Ser113, Ala115, and Gln242 make important contributions to catalytic turnover and cofactor-assisted catalysis. These results provide biochemical and structural characterization of CsAcOAT, expand current knowledge of cyanobacterial AcOATs, and offer a useful basis for future studies on arginine metabolism and nitrogen storage in diazotrophic cyanobacteria. Full article

This study systematically compared the effects of dietary supplementation with glutamine (Gln) and its precursors, including glutamic acid (GA) and α-ketoglutarate (AKG), on growth performance, serum antioxidant and immune parameters, and multi-region gastrointestinal microbiota in suckling lambs. Forty healthy suckling Hu lambs with similar body weight (7.37 ± 1.18 kg) and age (7 ± 0.8 d) were selected and randomly allocated into four groups (n = 10 per group): a control group (CON, without additive), and three treatment groups (GA, AKG, and Gln), each receiving 2 g per animal per day of the corresponding additive. The experimental period lasted for 42 d. All three additives showed a tendency to increase the final body weight (p = 0.056) and significantly increased the average daily gain (ADG) of lambs (p < 0.05). GA supplementation increased the dry matter intake throughout the entire trial (p < 0.05), whereas the addition of AKG and Gln increased the dry matter intake only during the later period (d 21–42) (p < 0.05). The feed-to-gain ratios did not differ among all groups (p > 0.05). Compared with the CON group, all three treatment groups showed elevated serum activities of catalase, glutathione peroxidase, and total antioxidant capacity, as well as increased IgA and IgG contents (p < 0.05). In addition, malondialdehyde concentration was decreased in all three treatment groups (p < 0.05). Moreover, GA supplementation reduced the ruminal alpha diversity while increasing the abundance of butyrate-producing bacteria (Ruminococcaceae UCG-014) (p < 0.05). All three interventions consistently decreased the abundance of the intestinal pathogen Escherichia-Shigella in the ileum (p < 0.05). Correlation analyses showed that ruminal Treponema 2 abundance was negatively correlated with ADG, whereas jejunal Methylobacterium and ileal [Eubacterium] coprostanoligenes group were positively correlated with final body weight or ADG. In conclusion, glutamine and its precursors play an important role in modulating gastrointestinal bacterial diversity and composition, enhancing antioxidant and immune functions, and improving the growth performance of suckling lambs. Full article

Agaricus bisporus (A. bisporus) is susceptible to rapid postharvest deterioration. Although elevated CO₂ (6%) delays senescence, the metabolic mechanisms remain unclear. In this study, untargeted and targeted metabolomic analyses were employed to explore these pathways in A. bisporus. The results revealed that elevated CO₂ treatment promoted glycolysis by upregulating Hexokinase (HK), Phosphofructokinase (PFK), and Pyruvate Kinase (PK), accumulating Glucose-6-phosphate (G-6-P) and Fructose-6-phosphate (F-6-P). Concurrently, elevated CO₂ treatment upregulated the expression of genes associated with the tricarboxylic acid (TCA) cycle and increased the enzymatic activities of Malate Dehydrogenase (MDH) and Fumarate hydratase (FUM). These changes led to the rapid consumption of key intermediate metabolites (Fumarate (Fum), Malate (Mal), and α-Ketoglutarate (α-KG)), collectively enhancing the efficiency of the TCA cycle. Furthermore, elevated CO₂ treatment significantly suppressed the activities of Glutamine Synthetase (GS) and Xanthine Oxidase (XOD), inhibiting the synthesis of Glutamine (Gln) and Pyroglutamate (pGlu) while promoting the accumulation of Hypoxanthine (Hx). This coordinated reprogramming of amino acid metabolism and purine metabolism contributed to improved energy efficiency and enhanced cellular integrity in postharvest A. bisporus. This study elucidates the specific mechanism by which elevated CO₂ levels regulate the postharvest energy metabolism of A. bisporus from a metabolomics perspective, providing a theoretical basis for developing strategies to control its postharvest quality. Full article

Carnitine plays an essential role in fatty acid metabolism, and its biosynthesis is tightly regulated by γ-butyrobetaine hydroxylase (BBOX), an Fe(II)/α-ketoglutarate-dependent dioxygenase. BBOX is the target of mildronate (THP), a clinically used drug for treating ischemic heart diseases. However, the detailed mechanisms of BBOX-catalyzed hydroxylation and the atypical oxidative rearrangement underlying THP inhibition remain elusive. In this study, we employed combined quantum mechanics/molecular mechanics (QM/MM) methods to systematically elucidate these mechanisms at the atomic level. Our calculations reveal that the hydroxylation of γBB proceeds via a classical three-step mechanism in the quintet state, with hydrogen atom abstraction as the rate-determining step. Remarkably, substitution of the C4 methylene group in γBB with an amino group in THP redirects the reaction pathway, as the lone pair electrons on the adjacent nitrogen atom render N-N bond cleavage kinetically favored over hydroxyl rebound, thereby blocking carnitine synthesis. Through systematic evaluation of possible rearrangement pathways, we rule out the previously proposed direct 1,2-H migration and suggest a revised mechanism featuring imine-mediated hydrogen transfer, hydroxyl rebound preceding C-C bond formation, and final radical coupling. This work provides a detailed atomic-level understanding of both the catalytic and inhibitory mechanisms of BBOX, revealing how substrate electronic effects dictate reaction outcomes. The elucidated mechanistic insights offer a theoretical foundation for understanding the catalytic versatility of the αKG-dependent dioxygenase family and provide valuable guidance for the rational design of novel BBOX inhibitors. Full article

Background/Objectives: Chondrosarcoma, glioblastoma, acute myeloid leukemia, chronic lymphocytic leukemia, and cholangiocarcinoma cancers all contain mutations in the gene isocitrate dehydrogenase 2 (IDH2). The mutant IDH2 enzyme metabolizes alpha-ketoglutarate (αKG) into the potent oncometabolite D-2-hydroxyglutarate (D2HG) in the mitochondria of these cancers, leading to altered cellular metabolism. Emerging evidence suggests that mitochondrial transfer between cancer and recipient cells represents an important form of intercellular communication that may influence cellular metabolism. The presence of intercellular TNTs between IDH2-mutant chondrosarcoma cells motivated an investigation into mitochondria-associated physiological changes occurring during an intercellular exchange with immune cells. A mitochondrial transfer is a two-way process, and we hypothesized that mitochondria-associated material derived from IDH2-mutant chondrosarcoma cells is exchanged with normal cells through TNTs. We further hypothesized that disruption of the actin cytoskeleton will inhibit this transfer. Accordingly, our objectives were to (1) quantify the extent and directionality of the mitochondrial exchange between IDH2-mutant cells and wild-type cells and to modulate this process via cytoskeletal inhibitors, and (2) measure the metabolic changes associated with the coculture and mitochondrial exchange. Methods: IDH2-mutant chondrosarcoma cells were cocultured with immune cells in vitro to quantify the extent and directionality of the mitochondrial exchange, and cytochalasin B was used as a cytoskeletal inhibitor to disrupt actin-dependent transfer. Metabolic changes associated with coculture and mitochondrial exchange were assessed using Seahorse extracellular flux analysis. Results: The experimental data presented here demonstrate a bidirectional exchange of mitochondria-associated material between IDH2-mutant chondrosarcoma cells and immune cells in vitro, accompanied by metabolic alterations in both cell types. Conclusions: These findings advance our understanding of intercellular communication in the tumor microenvironment and provide a foundation for future studies examining the functional and therapeutic relevance of a mitochondrial exchange in IDH2-mutant cancers. Full article

Periodontal disease is a chronic inflammatory condition that destroys tooth-supporting tissues, particularly the alveolar bone and the periodontal ligament, and effective regenerative therapies remain limited. While the role of metabolic–epigenomic crosstalk in determining cell fate is well established, the specific mechanism by which a tricarboxylic acid (TCA) cycle metabolite can modulate chromatin regulation to promote periodontal regeneration remains to be elucidated. The impact of one TCA cycle metabolite, alpha-ketoglutarate (α-KG), was examined in human periodontal ligament fibroblasts cultured under osteogenic induction and profiled by ALP assays, RT-qPCR, analyses of multiple histone modifications, ATAC-seq, and RNA-seq. α-KG increased ALP activity and upregulated genes associated with osteogenesis and the extracellular matrix (ECM). ATAC-seq revealed minimal genome-wide accessibility changes, whereas histone analyses showed reduced H3K27me3, consistent with an epigenetic mechanism that does not require extensive chromatin opening. The RNA-seq identified 14 upregulated α-KG-induced genes, including multiple components of the OGN-OMD-PLAP1/ASPN-ECM2 loci, supporting an osteogenic/ECM transcriptional program. In a mouse periodontal regeneration model, oral administration of α-KG enhanced alveolar bone regeneration and reduced H3K27me3 signals and collagen-rich tissue organization within the periodontal ligament space. These findings identify α-KG as a metabolite-driven epigenetic modulator that alleviates H3K27me3-mediated repression and supports periodontal regeneration. Full article

Glutamine is a known regulator of vascular smooth muscle cell (VSMC) function, but the molecular pathways underlying this response remain incompletely understood. This study investigated how glutamine metabolism influences VSMC behavior and identified the responsible enzymes and metabolites. Glutamine deprivation markedly reduced VSMC proliferation, migration, and collagen synthesis, while modestly decreasing viability. Pharmacological inhibition of glutaminase-1 (GLS1) or aminotransferases (AT) similarly suppressed these cellular functions, whereas inhibiting glutamate dehydrogenase 1 (GLUD1) had no effect. Metabolite analysis revealed that glutamine deprivation or AT inhibition, but not GLUD1 inhibition, reduced intracellular α-ketoglutarate (αKG) concentrations, establishing AT as the primary enzyme converting glutamine-derived glutamate to αKG. To identify which metabolite drives VSMC responses, glutamine-starved cells were supplemented with various glutamine-derived molecules. The cell-permeable αKG analog dimethyl-αKG significantly restored VSMC proliferation, migration, collagen synthesis, and survival, while ammonia only enhanced viability, demonstrating αKG’s primary role in mediating glutamine-dependent functions. These findings establish that glutamine metabolism via the GLS1-AT-αKG pathway is a critical driver of VSMC activation and survival. Targeting this glutamine-αKG metabolic axis through GLS1 inhibition, AT blockade, or downstream αKG disruption offers a compelling therapeutic strategy for ameliorating fibroproliferative vascular diseases, including atherosclerosis, post-angioplasty restenosis, and pulmonary hypertension. Full article

Glioblastoma (GBM) is characterized by its unique molecular features, such as self-renewal and tumorigenicity of glioma stem cells that promote resistance, largely resulting in treatment failure. Among the molecular alterations significant to GBM biology and treatment, mutations in isocitrate dehydrogenase (IDH) have assumed particular relevance. IDH-mutant and IDH-wild-type tumors exhibit significantly different metabolic characteristics, clinical behavior, and therapeutic sensitivities, making IDH status a critical determinant in determining prognosis and treatment strategies for GBM. In the context of cancer, chaperones were shown to promote tumor progression by supporting malignant cells over healthy ones. While heat shock proteins (HSPs) have long been implicated in the molecular mechanisms of tumor phenotype progression, recent attention has turned to CCT (chaperonin containing TCP1), orchestrating proteostasis. The chaperonin CCT is being explored as a diagnostic and therapeutic target in many cancers, including GBM, owing to its involvement in key oncogenic signaling pathways such as Wnt, VEGF, EGFR, and PI3K/AKT/mTOR. However, its role in the GBM-tricarboxylic acid (TCA) cycle cascade is still not well understood. Therefore, the present review highlights the potential role of the CCT complex in regulating hypoxia-inducible factor (HIF) activation by modulating enzymes responsive to metabolites derived from glucose metabolism and the TCA cycle in a manner dependent on oxygen availability and IDH mutation status. Full article

Background/Objectives: Plasma glutamine levels in skeletal muscle change in response to exercise intensity and duration, both in physiological and pathological states. Glutamine contributes to muscle differentiation and regeneration; however, the mechanisms underlying this process remain unclear. This study investigated the role of glutamine glutaminolysis in myogenic differentiation, with a focus on epigenetic regulation of myogenin gene expression. Methods: C2C12 myoblasts were differentiated into myotubes using media containing various concentrations of glutamine, glutamate, or dimethyl 2-oxoglutarate (DM-α-KG), a cell-permeable analog of α-ketoglutarate. Results: Glutamine, glutamate, and DM-α-KG promoted C2C12 myoblast differentiation in a concentration-dependent manner, whereas the glutaminase inhibitor CB-839 suppressed differentiation. 4 mM glutamine increased myogenin mRNA expression by about 5-fold. CB-839 also inhibited glutamine-induced expression of myogenin but did not influence the effects of glutamate or DM-α-KG. Furthermore, glutamine increased histone H3 lysine 27 acetylation (H3K27ac) by about two-fold, whereas CB-839 (200 nM) and A-485 (10 µM), a CBP/p300 histone acetyltransferase inhibitor, reduced H3K27ac levels by about half. These results indicate that glutamine not only serves as a structural amino acid for muscle formation but also enhances myogenin transcription through epigenetic mechanisms. Conclusions: This report demonstrates glutaminolysis-dependent histone H3 acetylation, which induces myogenin transcription in myoblasts. These results, connecting glutamine supplementation during resistance training, may make it an effective strategy to accelerate muscle regeneration. Full article

Nutrient deprivation causes dedifferentiation in solid tumors, driving an aggressive phenotype. We previously showed that glucose starvation-induced dedifferentiation is driven by epigenetic changes induced by a deficit of alpha-ketoglutarate (α-KG). Deficient activity of α-KG-dependent histone demethylases leads to unbalanced hypermethylation of histone 3 on lysine 27 (H3K27) by methyltransferase EZH2. H3K27 hypermethylation is a key mechanism of starvation-induced dedifferentiation. Here, we investigate a new aspect of this mechanism and show that epitranscriptomic changes are also induced by glucose restriction. Specifically, hypermethylation of select long non-coding RNAs leads to their upregulation under glucose deprivation as a consequence of reduced activity of the RNA demethylase FTO. We identified LINC00662 as an lncRNA required for EZH2 recruitment to target gene promoters induced by low glucose. These findings characterize the epigenetic response to glucose restriction beyond histone methylation, revealing that RNA methylation of lncRNAs such as LINC00662 represents a parallel mechanism converging on EZH2. Full article

Isocitrate dehydrogenase (IDH) catalyzes the conversion of NAD(P)⁺ and isocitrate to NAD(P)H and α-ketoglutarate (αKG). The cytoplasmic enzyme IDH1 is important for producing NADPH for biosynthesis and for protecting against oxidative stress. IDH1 mutants, such as R132H found in glioblastomas and other types of human cancers, have a neomorphic activity that uses NADPH to reduce αKG to 2-hydroxyglutarate (2HG). 2HG interferes with the activity of important enzymes such as histone demethylases and TET demethylases. We hypothesized that Caenorhabditis elegans could be a good model system for studying oncogenic properties of mutant IDH1. To test this, we purified C. elegans cytoplasmic IDH-1 and two mutants, G98N and R133H, which correspond to human IDH1 mutants G97N and R132H, respectively. We found that the wild-type IDH-1 had similar kinetic properties to human IDH1, and it could produce small amounts of 2HG. We also found that the R133H mutant had a lower K_M for αKG than human R132H in steady-state enzyme kinetic experiments, and it produced almost exclusively 2HG in the presence of NADPH and αKG. The G98N mutant had a higher k_cat in the forward direction than the comparable human G97N mutant, and the G98N mutant produced a smaller amount of 2HG compared to the R133H mutant. These results suggest that C. elegans strains with IDH-1 mutations could be a good model system for studying the effects of 2HG in eukaryotic organisms. Full article

Background: Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are enzymes that catalyze the oxidative decarboxylation of isocitrate to alpha-ketoglutarate (α-KG), which is essential for many metabolic processes, including some steps in DNA repair. In tumors, notably in gliomas, IDH1 and IDH2 are frequently mutated. The mutation found in different cancers is functionally active, causing, instead of α-KG, the formation of 2-hydroxyglutarate (2-HG), which inhibits α-KG-dependent enzymes. Gliomas harboring mutated IDH1/2 show a better prognosis than IDH1 wild-type (wt) tumors of the same grade, which might result from the inhibition of DNA repair functions. A DNA repair enzyme dependent on α-KG is alkB homolog 2 (ALKBH2), which removes several lesions from DNA. These findings prompted us to investigate the response of glioma cells to artesunate (ART), a plant ingredient with genotoxic and anticancer activity currently used in several trials. Materials and Methods: We used isogenic glioblastoma cell lines that express IDH1 wild-type or, based on a TET-inducible system, the IDH1 mutant (mt) protein, and treated them with increasing doses of artesunate. We also treated glioblastoma cells with 2-HG, generated ALKBH2 knockout cells, and checked their sensitivity to the cytotoxic effects of artesunate. Results: We show that the cell-killing effect of ART is enhanced if the IDH1 mutant (R132H) is expressed in glioblastoma cells. Further, we show that 2-HG imitates the effect of IDH1mt as 2-HG ameliorates the cytotoxicity of ART. Finally, we demonstrate that the knockout of ALKBH2 causes the sensitization of glioblastoma cells to ART. Conclusions: The data indicate that ALKBH2 protects against the anticancer effect of ART, and the mutation of IDH1/2 commonly occurring in low-grade gliomas sensitizes to ART via an ALKBH2-dependent mechanism. The data support the use of ART in the therapy of IDH1/2-mutated cancers both in combination with chemotherapy and adjuvant treatment. Full article