NADPH production by the oxidative pentose-phosphate pathway supports folate metabolism

MTHFD2-mediated redox homeostasis promotes gastric cancer progression under hypoxic conditions

OBJECTIVES

Cancer cells undergo metabolic reprogramming to adapt to high oxidative stress, but little is known about how metabolic remodeling enables gastric cancer cells to survive stress associated with aberrant reactive oxygen species (ROS) production. Here, we aimed to identify the key metabolic enzymes that protect gastric cancer (GC) cells from oxidative stress.

METHODS

ROS level was detected by DCFH-DA probes. Multiple cell biological studies were performed to identify the underlying mechanisms. Furthermore, cell-based xenograft and patient-derived xenograft (PDX) model were performed to evaluate the role of MTHFD2 in vivo.

RESULTS

We found that overexpression of MTHFD2, but not MTHFD1, is associated with reduced overall and disease-free survival in gastric cancer. In addition, MTHFD2 knockdown reduces the cellular NADPH/NADP+ ratio, colony formation and mitochondrial function, increases cellular ROS and cleaved PARP levels and induces in cell death under hypoxia, a hallmark of solid cancers and a common inducer of oxidative stress. Moreover, genetic or pharmacological inhibition of MTHFD2 reduces tumor burden in both tumor cell lines and patient-derived xenograft-based models.

DISCUSSION

our study highlights the crucial role of MTHFD2 in redox regulation and tumor progression, demonstrating the therapeutic potential of targeting MTHFD2.

Compensatory activity of the PC-ME1 metabolic axis underlies differential sensitivity to mitochondrial complex I inhibition

Deficiencies in the electron transport chain (ETC) lead to mitochondrial diseases. While mutations are distributed across the organism, cell and tissue sensitivity to ETC disruption varies, and the molecular mechanisms underlying this variability remain poorly understood. Here we show that, upon ETC inhibition, a non-canonical tricarboxylic acid (TCA) cycle upregulates to maintain malate levels and concomitant production of NADPH. Our findings indicate that the adverse effects observed upon CI inhibition primarily stem from reduced NADPH levels, rather than ATP depletion. Furthermore, we find that Pyruvate carboxylase (PC) and ME1, the key mediators orchestrating this metabolic reprogramming, are selectively expressed in astrocytes compared to neurons and underlie their differential sensitivity to ETC inhibition. Augmenting ME1 levels in the brain alleviates neuroinflammation and corrects motor function and coordination in a preclinical mouse model of CI deficiency. These studies may explain why different brain cells vary in their sensitivity to ETC inhibition, which could impact mitochondrial disease management.

Conditional lethality profiling reveals anticancer mechanisms of action and drug-nutrient interactions

Chemical screens across hundreds of cell lines have shown that the drug sensitivities of human cancers can vary by genotype or lineage. However, most drug discovery studies have relied on culture media that poorly reflect metabolite levels in human blood. Here, we perform drug screens in traditional and Human Plasma-Like Medium (HPLM). Sets of compounds that show conditional anticancer activity span different phases of global development and include non-oncology drugs. Comparisons of the synthetic and serum-derived components that comprise typical media trace sets of conditional phenotypes to nucleotide synthesis substrates. We also characterize a unique dual mechanism for brivudine, a compound approved for antiviral use. Brivudine selectively impairs cell growth in low folate conditions by targeting two enzymes involved in one-carbon metabolism. Cataloged gene essentiality data further suggest that conditional phenotypes for other compounds are linked to off-target effects. Our findings establish general strategies for identifying drug-nutrient interactions and mechanisms of action by exploiting conditional lethality in cancer cells.

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.

6-Phosphogluconate dehydrogenase promotes glycolysis and fatty acid synthesis by inhibiting the AMPK pathway in lung adenocarcinoma cells

Abnormal metabolism has emerged as a prominent hallmark of cancer and plays a pivotal role in carcinogenesis and progression of lung adenocarcinoma (LUAD). In this study, single-cell sequencing revealed that the metabolic enzyme 6-phosphogluconate dehydrogenase (PGD), which is a critical regulator of the pentose phosphate pathway (PPP), is significantly upregulated in the malignant epithelial cell subpopulation during malignant progression. However, the precise functional significance of PGD in LUAD and its underlying mechanisms remain elusive. Through the integration of TCGA database analysis and LUAD tissue microarray data, it was found that PGD expression was significantly upregulated in LUAD and closely correlated with a poor prognosis in LUAD patients. Moreover, in vitro and in vivo analyses demonstrated that PGD knockout and inhibition of its activity mitigated the proliferation, migration, and invasion of LUAD cells. Mechanistically, immunoprecipitation-mass spectrometry (IP-MS) revealed for the first time that IQGAP1 is a robust novel interacting protein of PGD. PGD decreased p-AMPK levels by competitively interacting with the IQ domain of the known AMPKα binding partner IQGAP1, which promoted glycolysis and fatty acid synthesis in LUAD cells. Furthermore, we demonstrated that the combination of Physcion (a PGD-specific inhibitor) and metformin (an AMPK agonist) could inhibit tumor growth more effectively both in vivo and in vitro. Collectively, these findings suggest that PGD is a potential prognostic biomarker and therapeutic target for LUAD.

Mechanisms and therapeutic potential of disulphidptosis in cancer

SLC7A11 plays a pivotal role in tumour development by facilitating cystine import to enhance glutathione synthesis and counteract oxidative stress. Disulphidptosis, an emerging form of cell death observed in cells with high expression of SLC7A11 under glucose deprivation, is regulated through reduction-oxidation reactions and disulphide bond formation. This process leads to contraction and collapse of the F-actin cytoskeleton from the plasma membrane, ultimately resulting in cellular demise. Compared to other forms of cell death, disulphidptosis exhibits distinctive characteristics and regulatory mechanisms. This mechanism provides novel insights and innovative strategies for cancer treatment while also inspiring potential therapeutic approaches for other diseases. Our review focuses on elucidating the molecular mechanism underlying disulphidptosis and its connection with the actin cytoskeleton, identifying alternative metabolic forms of cell death, as well as offering insights into disulphidptosis-based cancer therapy. A comprehensive understanding of disulphidptosis will contribute to our knowledge about fundamental cellular homeostasis and facilitate the development of groundbreaking therapies for disease treatment.

Glutamine promotes the proliferation of intestinal stem cells via inhibition of TP53-induced glycolysis and apoptosis regulator promoter methylation in burned mice

Background

Intestinal stem cells (ISCs) play a pivotal role in maintaining intestinal homeostasis and facilitating the restoration of intestinal mucosal barrier integrity. Glutamine (Gln) is a crucial energy substrate in the intestine, promoting the proliferation of ISCs and mitigating damage to the intestinal mucosal barrier after burn injury. However, the underlying mechanism has not yet been fully elucidated. The objective of this study was to explore the mechanism by which Gln facilitates the proliferation of ISCs.

Methods

A mouse burn model was established to investigate the impact of Gln on intestinal function. Subsequently, crypts were isolated, and changes in TP53-induced glycolysis and apoptosis regulator (TIGAR) expression were assessed using real-time quantitative polymerase chain reaction (RT-qPCR), western blotting, immunohistochemistry, and immunofluorescence. The effects of TIGAR on cell proliferation were validated through CCK-8, EdU, and clonogenicity assays. Furthermore, the effect of TIGAR on Yes-associated protein (YAP) nuclear translocation and ferroptosis was examined by western blotting and immunofluorescence staining. Finally, dot blot analysis and methylation-specific PCR were performed to evaluate the effect of Gln on TIGAR promoter methylation.

Results

The mRNA and protein levels of TIGAR decreased after burn injury, and supplementation with Gln increased the expression of TIGAR. TIGAR accelerates the nuclear translocation of YAP, thereby increasing the proliferation of ISCs. Concurrently, TIGAR promotes the synthesis of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione to suppress ferroptosis in ISCs. Subsequent investigations demonstrated that Gln inhibits TIGAR promoter methylation by increasing the expression of the demethylase ten-eleven translocation. This change increased TIGAR transcription, increased NADPH synthesis, and reduced oxidative stress, thereby facilitating the restoration of intestinal mucosal barrier integrity post-burn injury.

Conclusions

Our data confirmed the inhibitory effect of Gln on TIGAR promoter methylation, which facilitates YAP translocation into the nucleus and suppresses ferroptosis, ultimately promoting the proliferation of ISCs.

Curcumin suppresses colorectal tumorigenesis through restoring the gut microbiota and metabolites

BACKGROUND

Curcumin has been reported to have activity for prevention and therapy of CRC, yet its underlying mechanisms remain largely unknown. Recently, emerging evidence suggests that the gut microbiota and its metabolites contribute to the causation and progression of Colorectal cancer (CRC). In this study, we aimed to investigate if curcumin affects the tumorigenesis of CRC by modulating gut microbiota and its metabolites.

METHODS

Forty male C57BL/6JGpt mice were randomly divided into four groups: negative control (NC), curcumin control, CRC model, and curcumin treatment (CRC-Cur) groups. CRC mouse model was induced by using azoxymethane (AOM) and dextran sodium sulfate (DSS), and the mice in CRC model and curcumin treatment groups received oral PBS or curcumin (150 mg/kg/day), respectively. Additionally, fecal samples were collected. 16 S rRNA sequencing and Liquid Chromatography Mass Spectrometry (LC-MS)-based untargeted metabolomics were used to observe the changes of intestinal flora and intestinal metabolites.

RESULTS

Curcumin treatment restored colon length and structural morphology, and significantly inhibited tumor formation in AOM/DSS-induced CRC model mice. The 16S rRNA sequencing analysis indicated that the diversity and richness of core and total species of intestinal microflora in the CRC group were significantly lower than those in the NC group, which were substantially restored in the curcumin treatment group. Curcumin reduced harmful bacteria, including Ileibacterium, Monoglobus and Desulfovibrio, which were elevated in CRC model mice. Moreover, curcumin increased the abundance of Clostridia_UCG-014, Bifidobacterium and Lactobacillus, which were decreased in CRC model mice. In addition, 13 different metabolites were identified. Compared to the NC group, ethosuximide, xanthosine, and 17-beta-estradiol 3-sulfate-17-(beta-D-glucuronide) were elevated in the CRC model group, whereas curcumin treatment significantly reduced their levels. Conversely, glutamylleucine, gamma-Glutamylleucine, liquiritin, ubenimex, 5'-deoxy-5'-fluorouridine, 7,8-Dihydropteroic acid, neobyakangelicol, libenzapril, xenognosin A, and 7,4'-dihydroxy-8-methylflavan were decreased in the CRC group but notably upregulated by curcumin. Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis revealed enrichment in seven pathways, including folate biosynthesis (P < 0.05).

CONCLUSIONS

The gut microecological balance was disrupted in AOM/DSS-induced CRC mice, accompanied by metabolite dysbiosis. Curcumin restored the equilibrium of the microbiota and regulated metabolites, highly indicating that curcumin may alleviate the development of AOM/DSS induced colorectal cancer in mice by regulating intestinal flora homeostasis and intestinal metabolites.

Tumor suppressor BAP1 suppresses disulfidptosis through the regulation of SLC7A11 and NADPH levels

BAP1, BRCA1-Associated Protein 1, serves as a novel tumor suppressor through the deubiquitination of monoubiquitination of H2A and subsequent gene transcriptional regulation. Regulated cell death like apoptosis or ferroptosis is considered an essential mechanism mediating tumor suppression. Previous reports, including ours, have demonstrated that BAP1 could promote apoptosis and ferroptosis to inhibit tumor development. Whether BAP1 regulated additional types of cell death remains unclear. Disulfidptosis is a recently identified novel cell death mode characterized by aberrant accumulation of intracellular disulfide (e.g., cystine) and depletion of NADPH. In this study, we first demonstrated that BAP1 could significantly protect disulfidptosis induced by glucose starvation, which is validated by various cell death inhibitors and the accumulation of disulfide bonds in the cytoskeleton proteins. BAP1 is known to inhibit SLC7A11 expression. We found that the protective effect of BAP1 against disulfidptosis was counteracted when overexpressing SLC7A11 or adding additional cystine. Conversely, BAP1-mediated suppression of disulfidptosis was largely abrogated when SLC7A11-mediated cystine uptake was inhibited by the knockout of SLC7A11 or erastin treatment. Besides, high BAP1 expression showed lower NADP+/NADPH levels, which might confer resistance to disulfidptosis. Consistent with these observations, the expression level of BAP1 was also positively correlated with NADPH-related genes in KIRC patients, though the underlying mechanism mediating NADPH regulation remains further investigation. In summary, our results revealed the role of BAP1 in the regulation disulfidptosis and provided new insights into the understanding of disulfidptosis in tumor development.

SLC7A11-mediated cystine import protects against NDUFS7 deficiency-induced cell death in HEK293T cells

Cell models of mitochondrial complex Ⅰ (CⅠ) deficiency display significant elevations in reactive oxygen species (ROS) levels and an increase in cellular apoptosis. However, the underlying mechanisms governing anti-apoptotic processes in CⅠ-deficient cells remain elusive. Here, we introduced a mutation in NDUFS7, a crucial subunit of CI, in HEK293T cells and found that the absence of NDUFS7 resulted in reduced cell proliferation, elevated cell death, and increased susceptibility to oxidative stress. Mechanismly, we revealed that the upregulation of SLC7A11 played a crucial role in mitigating cell death resulting from NDUFS7 deficiency. Specifically, the increased expression of SLC7A11 enhanced cystine import, which subsequently reduced cell death by promoting the biosynthesis of reduced glutathione (GSH). Collectively, our findings suggest that SLC7A11-mediated cystine import, representing a novel pathway independent of NADPH production, plays a vital role in protection against NDUFS7 deficiency-induced cell death. This novel pathway provides potential insights into the understanding of pathogenic mechanisms and the therapeutic management of mitochondrial disorders associated with CⅠ deficiency.

Metabolic cell death in cancer: ferroptosis, cuproptosis, disulfidptosis, and beyond

Cell death resistance represents a hallmark of cancer. Recent studies have identified metabolic cell death as unique forms of regulated cell death resulting from an imbalance in the cellular metabolism. This review discusses the mechanisms of metabolic cell death-ferroptosis, cuproptosis, disulfidptosis, lysozincrosis, and alkaliptosis-and explores their potential in cancer therapy. Our review underscores the complexity of the metabolic cell death pathways and offers insights into innovative therapeutic avenues for cancer treatment.

Homeostatic regulation of NAD(H) and NADP(H) in cells

Nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) and nicotinamide adenine dinucleotide phosphate (NADP+)/reduced NADP+ (NADPH) are essential metabolites involved in multiple metabolic pathways and cellular processes. NAD+ and NADH redox couple plays a vital role in catabolic redox reactions, while NADPH is crucial for cellular anabolism and antioxidant responses. Maintaining NAD(H) and NADP(H) homeostasis is crucial for normal physiological activity and is tightly regulated through various mechanisms, such as biosynthesis, consumption, recycling, and conversion between NAD(H) and NADP(H). The conversions between NAD(H) and NADP(H) are controlled by NAD kinases (NADKs) and NADP(H) phosphatases [specifically, metazoan SpoT homolog-1 (MESH1) and nocturnin (NOCT)]. NADKs facilitate the synthesis of NADP+ from NAD+, while MESH1 and NOCT convert NADP(H) into NAD(H). In this review, we summarize the physiological roles of NAD(H) and NADP(H) and discuss the regulatory mechanisms governing NAD(H) and NADP(H) homeostasis in three key aspects: the transcriptional and posttranslational regulation of NADKs, the role of MESH1 and NOCT in maintaining NAD(H) and NADP(H) homeostasis, and the influence of the circadian clock on NAD(H) and NADP(H) homeostasis. In conclusion, NADKs, MESH1, and NOCT are integral to various cellular processes, regulating NAD(H) and NADP(H) homeostasis. Dysregulation of these enzymes results in various human diseases, such as cancers and metabolic disorders. Hence, strategies aiming to restore NAD(H) and NADP(H) homeostasis hold promise as novel therapeutic approaches for these diseases.

Glutamine Metabolism and Prostate Cancer

Glutamine (Gln) is a non-essential amino acid that is involved in the development and progression of several malignancies, including prostate cancer (PCa). While Gln is non-essential for non-malignant prostate epithelial cells, PCa cells become highly dependent on an exogenous source of Gln. The Gln metabolism in PCa is tightly controlled by well-described oncogenes such as MYC, AR, and mTOR. These oncogenes contribute to therapy resistance and progression to the aggressive castration-resistant PCa. Inhibition of Gln catabolism impedes PCa growth, survival, and tumor-initiating potential while sensitizing the cells to radiotherapy. Therefore, given its significant role in tumor growth, targeting Gln metabolism is a promising approach for developing new therapeutic strategies. Ongoing clinical trials evaluate the safety and efficacy of Gln catabolism inhibitors in combination with conventional and targeted therapies in patients with various solid tumors, including PCa. Further understanding of how PCa cells metabolically interact with their microenvironment will facilitate the clinical translation of Gln inhibitors and help improve therapeutic outcomes. This review focuses on the role of Gln in PCa progression and therapy resistance and provides insights into current clinical trials.

Cyclic fasting-mimicking diet in cancer treatment: Preclinical and clinical evidence

In preclinical tumor models, cyclic fasting and fasting-mimicking diets (FMDs) produce antitumor effects that become synergistic when combined with a wide range of standard anticancer treatments while protecting normal tissues from treatment-induced adverse events. More recently, results of phase 1/2 clinical trials showed that cyclic FMD is safe, feasible, and associated with positive metabolic and immunomodulatory effects in patients with different tumor types, thus paving the way for larger clinical trials to investigate FMD anticancer activity in different clinical contexts. Here, we review the tumor-cell-autonomous and immune-system-mediated mechanisms of fasting/FMD antitumor effects, and we critically discuss new metabolic interventions that could synergize with nutrient starvation to boost its anticancer activity and prevent or reverse tumor resistance while minimizing toxicity to patients. Finally, we highlight potential future applications of FMD approaches in combination with standard anticancer strategies as well as strategies to implement the design and conduction of clinical trials.

Dynamic and Static Regulation of Nicotinamide Adenine Dinucleotide Phosphate: Strategies, Challenges, and Future Directions in Metabolic Engineering

Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is a crucial cofactor in metabolic networks. The efficient regeneration of NADPH is one of the limiting factors for productivity in biotransformation processes. To date, many metabolic engineering tools and static regulation strategies have been developed to regulate NADPH regeneration. However, traditional static regulation methods often lead to the NADPH/NADP+ imbalance, causing disruptions in cell growth and production. These methods also fail to provide real-time monitoring of intracellular NADP(H) or NADPH/NADP+ levels. In recent years, various biosensors have been developed for the detection, monitoring, and dynamic regulate of the intracellular NADP(H) levels or the NADPH/NADP+ balance. These NADPH-related biosensors are mainly used in the cofactor engineering of bacteria, yeast, and mammalian cells. This review analyzes and summarizes the NADPH metabolic regulation strategies from both static and dynamic perspectives, highlighting current challenges and potential solutions, and discusses future directions for the advanced regulation of the NADPH/NADP+ balance.

Emerging mechanisms and promising approaches in pancreatic cancer metabolism

Pancreatic cancer is an aggressive cancer with a poor prognosis. Metabolic abnormalities are one of the hallmarks of pancreatic cancer, and pancreatic cancer cells can adapt to biosynthesis, energy intake, and redox needs through metabolic reprogramming to tolerate nutrient deficiency and hypoxic microenvironments. Pancreatic cancer cells can use glucose, amino acids, and lipids as energy to maintain malignant growth. Moreover, they also metabolically interact with cells in the tumour microenvironment to change cell fate, promote tumour progression, and even affect immune responses. Importantly, metabolic changes at the body level deserve more attention. Basic research and clinical trials based on targeted metabolic therapy or in combination with other treatments are in full swing. A more comprehensive and in-depth understanding of the metabolic regulation of pancreatic cancer cells will not only enrich the understanding of the mechanisms of disease progression but also provide inspiration for new diagnostic and therapeutic approaches.

Engineering Gluconbacter oxydans with efficient co-utilization of glucose and sorbitol for one-step biosynthesis of 2-keto-L-gulonic

As the highest-demand vitamin, the development of a one-step vitamin C synthesis process has been slow for a long time. In previous research, a Gluconobacter oxydans strain (GKLG9) was constructed that can directly synthesize 2-keto-L-gulonic acid (2-KLG) from glucose, but carbon source utilization remained low. Therefore, this study first identified the gene 4kas (4-keto-D-arabate synthase) to reduce the loss of extracellular carbon and inhibit the browning of fermentation broth. Then, promoter engineering was conducted to enhance the intracellular glucose transport pathway and concentrate intracellular glucose metabolism on the pentose phosphate pathway to provide more reducing power. Finally, by introducing the D-sorbitol pathway, the titer of 2-KLG was increased to 38.6 g/L within 60 h in a 5-L bioreactor, with a glucose-to-2-KLG conversion rate of about 46 %. This study is an important step in the development of single-bacterial one-step fermentation to produce 2-KLG.

Metabolism and HSC fate: what NADPH is made for

Mitochondrial metabolism plays a central role in the regulation of hematopoietic stem cell (HSC) biology. Mitochondrial fatty acid oxidation (FAO) is pivotal in controlling HSC self-renewal and differentiation. Herein, we discuss recent evidence suggesting that NADPH generated in the mitochondria can influence the fate of HSCs. Although NADPH has multiple functions, HSCs show high levels of NADPH that are preferentially used for cholesterol biosynthesis. Endogenous cholesterol supports the biogenesis of extracellular vesicles (EVs), which are essential for maintaining HSC properties. We also highlight the significance of EVs in hematopoiesis through autocrine signaling. Elucidating the mitochondrial NADPH-cholesterol axis as part of the metabolic requirements of healthy HSCs will facilitate the development of new therapies for hematological disorders.

Glucose-6-phosphate dehydrogenase maintains redox homeostasis and biosynthesis in LKB1-deficient KRAS-driven lung cancer

Cancer cells depend on nicotinamide adenine dinucleotide phosphate (NADPH) to combat oxidative stress and support reductive biosynthesis. One major NADPH production route is the oxidative pentose phosphate pathway (committed step: glucose-6-phosphate dehydrogenase, G6PD). Alternatives exist and can compensate in some tumors. Here, using genetically-engineered lung cancer mouse models, we show that G6PD ablation significantly suppresses KrasG12D/+;Lkb1-/- (KL) but not KrasG12D/+;P53-/- (KP) lung tumorigenesis. In vivo isotope tracing and metabolomics reveal that G6PD ablation significantly impairs NADPH generation, redox balance, and de novo lipogenesis in KL but not KP lung tumors. Mechanistically, in KL tumors, G6PD ablation activates p53, suppressing tumor growth. As tumors progress, G6PD-deficient KL tumors increase an alternative NADPH source from serine-driven one carbon metabolism, rendering associated tumor-derived cell lines sensitive to serine/glycine depletion. Thus, oncogenic driver mutations determine lung cancer dependence on G6PD, whose targeting is a potential therapeutic strategy for tumors harboring KRAS and LKB1 co-mutations.

Central carbon metabolism exhibits unique characteristics during the handling of fungal patterns by monocyte-derived dendritic cells

Monocyte-derived dendritic cells (MDDCs) are key players in the defense against fungal infection because of their outstanding capacity for non-opsonic phagocytosis and phenotypic plasticity. Accordingly, MDDCs rewire metabolism to meet the energetic demands for microbial killing and biomass synthesis required to restore homeostasis. It has been commonplace considering the metabolic reprogramming a mimicry of the Warburg effect observed in tumor cells. However, this may be an oversimplification since the offshoots of glycolysis and the tricarboxylic acid (TCA) cycle are connected in central carbon metabolism. Zymosan, the external wall of Saccharomyces cerevisiae, contains β-glucan and α-mannan chains that engage the C-type lectin receptors dectin-1/2 and Toll-like receptors. This makes it an optimal fungal surrogate for experimental research. Using real-time bioenergetic assays and [U-13C]glucose labeling, central hubs connected to cytokine expression were identified. The pentose phosphate pathway (PPP) exhibited a more relevant capacity to yield ribose-5-phosphate than reducing equivalents of NADPH, as judged from the high levels of isotopologues showing 13C-labeling in the ribose moiety and the limited contribution of the oxidative arm of the PPP to the production of ROS by NADPH oxidases (NOX). The finding of 13C-label in the purine ring and in glutathione unveiled the contribution of serine-derived glycine to purine ring and glutathione synthesis. Serine synthesis also supported the TCA cycle. Zymosan exhausted NAD+ and ATP, consistent with intracellular consumption and/or extracellular export. Poly-ADP-ribosylated proteins detected in the nuclear fractions of MDDCs did not show major changes upon zymosan stimulation, which suggests its dependence on constitutive Fe(II)/2-oxoglutarate-dependent demethylation of 5-methylcytosine by TET translocases and/or demethylation of histone H3 lysine 27 by JMJD demethylases rather than on NOX activities. These results disclose a unique pattern of central carbon metabolism following fungal challenge, characterized by the leverage of glycolysis offshoots and an extensive recycling of NAD+ and poly(ADP-ribose).

Glucose metabolism in B cell malignancies: a focus on glycolysis branching pathways

Glucose catabolism, one of the essential pathways sustaining cellular bioenergetics, has been widely studied in the context of tumors. Nevertheless, the function of various branches of glucose metabolism that stem from 'classical' glycolysis have only been partially explored. This review focuses on discussing general mechanisms and pathological implications of glycolysis and its branching pathways in the biology of B cell malignancies. We summarize here what is known regarding pentose phosphate, hexosamine, serine biosynthesis, and glycogen synthesis pathways in this group of tumors. Despite most findings have been based on malignant B cells themselves, we also discuss the role of glucose metabolism in the tumor microenvironment, with a focus on T cells. Understanding the contribution of glycolysis branching pathways and how they are hijacked in B cell malignancies will help to dissect the role they have in sustaining the dissemination and proliferation of tumor B cells and regulating immune responses within these tumors. Ultimately, this should lead to deciphering associated vulnerabilities and improve current therapeutic schedules.

System Xc- exacerbates metabolic stress under glucose depletion in oral squamous cell carcinoma

OBJECTIVE

Emerging evidence suggests that glucose depletion (GD)-induced cell death depends on system Xc-, a glutamate/cystine antiporter extensively studied in ferroptosis. However, the underlying mechanism remains debated. Our study confirmed the correlation between system Xc- and GD-induced cell death and provided a strategic treatment for oral squamous cell carcinoma (OSCC).

METHODS

qPCR and Western blotting were performed to detect changes in xCT and CD98 expression after glucose withdrawal. Then, the cell viability of OSCCs under the indicated conditions was measured. To identify the GD-responsible transcriptional factors of SLC7A11, we performed a luciferase reporter assay and a ChIP assay. Further, metabolomics was conducted to identify changes in metabolites. Finally, mitochondrial function and ATP production were evaluated using the seahorse assay, and NADP+/NADPH dynamics were measured using a NADP+/NADPH kit.

RESULTS

In OSCCs, system Xc- promoted GD-induced cell death by increasing glutamate consumption, which promoted NADPH exhaustion and TCA blockade. Moreover, GD-induced xCT upregulation was governed by the p-eIF2α/ATF4 axis.

CONCLUSIONS

System Xc- overexpression compromised the metabolic flexibility of OSCC under GD conditions, and thus, glucose starvation therapy is effective for killing OSCC cells.

G6PD and ACSL3 are synthetic lethal partners of NF2 in Schwann cells

Neurofibromatosis Type II (NFII) is a genetic condition caused by loss of the NF2 gene, resulting in activation of the YAP/TAZ pathway and recurrent Schwann cell tumors, as well as meningiomas and ependymomas. Unfortunately, few pharmacological options are available for NFII. Here, we undertake a genome-wide CRISPR/Cas9 screen to search for synthetic-lethal genes that, when inhibited, cause death of NF2 mutant Schwann cells but not NF2 wildtype cells. We identify ACSL3 and G6PD as two synthetic-lethal partners for NF2, both involved in lipid biogenesis and cellular redox. We find that NF2 mutant Schwann cells are more oxidized than control cells, in part due to reduced expression of genes involved in NADPH generation such as ME1. Since G6PD and ME1 redundantly generate cytosolic NADPH, lack of either one is compatible with cell viability, but not down-regulation of both. Since genetic deficiency for G6PD is tolerated in the human population, G6PD could be a good pharmacological target for NFII.

PCK1-mediated glycogenolysis facilitates ROS clearance and chemotherapy resistance in cervical cancer stem cells

Cervical cancer, one of the most common gynecological cancers, is primarily caused by human papillomavirus (HPV) infection. The development of resistance to chemotherapy is a significant hurdle in treatment. In this study, we investigated the mechanisms underlying chemoresistance in cervical cancer by focusing on the roles of glycogen metabolism and the pentose phosphate pathway (PPP). We employed the cervical cancer cell lines HCC94 and CaSki by manipulating the expression of key enzymes PCK1, PYGL, and GYS1, which are involved in glycogen metabolism, through siRNA transfection. Our analysis included measuring glycogen levels, intermediates of PPP, NADPH/NADP+ ratio, and the ability of cells to clear reactive oxygen species (ROS) using biochemical assays and liquid chromatography-mass spectrometry (LC-MS). Furthermore, we assessed chemoresistance by evaluating cell viability and tumor growth in NSG mice. Our findings revealed that in drug-resistant tumor stem cells, the enzyme PCK1 enhances the phosphorylation of PYGL, leading to increased glycogen breakdown. This process shifts glucose metabolism towards PPP, generating NADPH. This, in turn, facilitates ROS clearance, promotes cell survival, and contributes to the development of chemoresistance. These insights suggest that targeting aberrant glycogen metabolism or PPP could be a promising strategy for overcoming chemoresistance in cervical cancer. Understanding these molecular mechanisms opens new avenues for the development of more effective treatments for this challenging malignancy.

Ultrasensitive Proteomics of Trace Cardiac Tissues with Anchor-Nanoparticles

Pathological cardiac hypertrophy is a complex process that often leads to heart failure. Label-free proteomics has emerged as an important platform to reveal protein variations and to elucidate the mechanisms of cardiac hypertrophy. Endomyocardial biopsy is a minimally invasive technique for sampling cardiac tissue, but it yields only limited amounts of an ethically permissible specimen. After regular pathological examination, the remaining trace samples pose significant challenges for effective protein extraction and mass spectrometry analysis. Herein, we developed trace cardiac tissue proteomics based on the anchor-nanoparticles (TCPA) method. We identified an average of 6666 protein groups using ∼50 μg of myocardial interventricular septum samples by TCPA. We then applied TCPA to acquire proteomics from patients' cardiac samples both diagnosed as hypertrophic hearts and myocarditis controls and identified significant alterations in pathways such as regulation of actin cytoskeleton, oxidative phosphorylation, and cGMP-PKG signaling pathway. Moreover, we found multiple lipid metabolic pathways to be dysregulated in transthyretin cardiac amyloidosis compared to other types of cardiac hypertrophy. TCPA offers a new technique for studying pathological cardiac hypertrophy and can serve as a platform toolbox for proteomic research in other cardiac diseases.

The cell biology of ferroptosis

Ferroptosis is a non-apoptotic cell death mechanism characterized by iron-dependent membrane lipid peroxidation. Here, we review what is known about the cellular mechanisms mediating the execution and regulation of ferroptosis. We first consider how the accumulation of membrane lipid peroxides leads to the execution of ferroptosis by altering ion transport across the plasma membrane. We then discuss how metabolites and enzymes that are distributed in different compartments and organelles throughout the cell can regulate sensitivity to ferroptosis by impinging upon iron, lipid and redox metabolism. Indeed, metabolic pathways that reside in the mitochondria, endoplasmic reticulum, lipid droplets, peroxisomes and other organelles all contribute to the regulation of ferroptosis sensitivity. We note how the regulation of ferroptosis sensitivity by these different organelles and pathways seems to vary between different cells and death-inducing conditions. We also highlight transcriptional master regulators that integrate the functions of different pathways and organelles to modulate ferroptosis sensitivity globally. Throughout this Review, we highlight open questions and areas in which progress is needed to better understand the cell biology of ferroptosis.

Proteomic and metabolomic analysis of GH deficiency-induced NAFLD in hypopituitarism: insights into oxidative stress

Objective

Individuals with hypopituitarism (HPs) have an increased risk of developing non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) due to growth hormone deficiency (GHD). We aimed to investigate the possible mechanisms underlying the relationship between GHD and NAFLD using proteomic and metabolomic insights.

Methods

Serum metabolic alternations were assessed in male HPs using untargeted metabolomics. A rat model of HP was established through hypophysectomy, followed by recombinant human growth hormone (rhGH) intervention. The mechanisms underlying GHD-mediated NAFLD were elucidated through the application of label-free proteomics and phosphorylation proteomics.

Results

Metabolomic analysis revealed that biomarkers of mitochondrial dysfunction and oxidative stress, such as alanine, lactate, and creatine, were significantly elevated in HPs compared to age-matched controls. In rats, hypophysectomy led to marked hepatic steatosis, lipid peroxidation, and reduced glutathione (GSH), which were subsequently modulated by rhGH replacement. Proteomic analysis identified cytochrome P450s, mitochondrial translation elongation, and PPARA activating genes as the major distinguishing pathways in hypophysectomized rats. The processes of fatty acid transport, synthesis, oxidation, and NADP metabolism were tightly described. An enhanced regulation of peroxisome β-oxidation and ω-oxidation, together with a decreased NADPH regeneration, may exacerbate oxidative stress. Phosphoproteome data showed downregulation of JAK2-STAT5B and upregulation of mTOR signaling pathway.

Conclusions

This study identified proteo-metabolomic signatures associated with the development of NAFLD in pituitary GHD. Evidence was found of oxidative stress imbalance resulting from abnormal fatty acid oxidation and NADPH regeneration, highlighting the role of GH deficiency in the development of NAFLD.

Effect of folA gene in human breast milk-derived Limosilactobacillus reuteri on its folate biosynthesis

Introduction

Folate supplementation is crucial for the human body, and the chemically synthesized folic acid might have undesirable side effects. The use of molecular breeding methods to modify the genes related to the biosynthesis of folate by probiotics to increase folate production is currently a focus of research.

Methods

In this study, the folate-producing strain of Limosilactobacillus reuteri B1-28 was isolated from human breast milk, and the difference between B1-28 and folA gene deletion strain ΔFolA was investigated by phenotyping, in vitro probiotic evaluation, metabolism and transcriptome analysis.

Results

The results showed that the folate producted by the ΔFolA was 2-3 folds that of the B1-28. Scanning electron microscope showed that ΔFolA had rougher surface, and the acid-producing capacity (p = 0.0008) and adhesion properties (p = 0.0096) were significantly enhanced than B1-28. Transcriptomic analysis revealed that differentially expressed genes were mainly involved in three pathways, among which the biosynthesis of ribosome and aminoacyl-tRNA occurred in the key metabolic pathways. Metabolomics analysis showed that folA affected 5 metabolic pathways, involving 89 different metabolites.

Discussion

In conclusion, the editing of a key gene of folA in folate biosynthesis pathway provides a feasible pathway to improve folate biosynthesis in breast milk-derived probiotics.

mTORC1 regulates cell survival under glucose starvation through 4EBP1/2-mediated translational reprogramming of fatty acid metabolism

Energetic stress compels cells to evolve adaptive mechanisms to adjust their metabolism. Inhibition of mTOR kinase complex 1 (mTORC1) is essential for cell survival during glucose starvation. How mTORC1 controls cell viability during glucose starvation is not well understood. Here we show that the mTORC1 effectors eukaryotic initiation factor 4E binding proteins 1/2 (4EBP1/2) confer protection to mammalian cells and budding yeast under glucose starvation. Mechanistically, 4EBP1/2 promote NADPH homeostasis by preventing NADPH-consuming fatty acid synthesis via translational repression of Acetyl-CoA Carboxylase 1 (ACC1), thereby mitigating oxidative stress. This has important relevance for cancer, as oncogene-transformed cells and glioma cells exploit the 4EBP1/2 regulation of ACC1 expression and redox balance to combat energetic stress, thereby supporting transformation and tumorigenicity in vitro and in vivo. Clinically, high EIF4EBP1 expression is associated with poor outcomes in several cancer types. Our data reveal that the mTORC1-4EBP1/2 axis provokes a metabolic switch essential for survival during glucose starvation which is exploited by transformed and tumor cells.

Disulfidptosis, A Novel Cell Death Pathway: Molecular Landscape and Therapeutic Implications

Programmed cell death is pivotal for several physiological processes, including immune defense. Further, it has been implicated in the pathogenesis of developmental disorders and the onset of numerous diseases. Multiple modes of programmed cell death, including apoptosis, pyroptosis, necroptosis, and ferroptosis, have been identified, each with their own unique characteristics and biological implications. In February 2023, Liu Xiaoguang and his team discovered "disulfidptosis," a novel pathway of programmed cell death. Their findings demonstrated that disulfidptosis is triggered in glucose-starved cells exhibiting high expression of a protein called SLC7A11. Furthermore, disulfidptosis is marked by a drastic imbalance in the NADPH/NADP+ ratio and the abnormal accumulation of disulfides like cystine. These changes ultimately lead to the destabilization of the F-actin network, causing cell death. Given that high SLC7A11 expression is a key feature of certain cancers, these findings indicate that disulfidptosis could serve as the basis of innovative anti-cancer therapies. Hence, this review delves into the discovery of disulfidptosis, its underlying molecular mechanisms and metabolic regulation, and its prospective applications in disease treatment.

Engineering Redox Cofactor Balance for Improved 5-Methyltetrahydrofolate Production in Escherichia coli

5-Methyltetrahydrofolate (5-MTHF) is the sole active form of folate functioning in the human body and is widely used as a nutraceutical. Unlike the pollution from chemical synthesis, microbial synthesis enables green production of 5-MTHF. In this study, Escherichia coli BL21 (DE3) was selected as the host. Initially, by deleting 6-phosphofructokinase 1 and overexpressing glucose-6-phosphate 1-dehydrogenase and 6-phosphogluconate dehydrogenase, the glycolysis pathway flux decreased, while the pentose phosphate pathway flux enhanced. The ratios of NADH/NAD+ and NADPH/NADP+ increased, indicating elevated NAD(P)H supply. This led to more folate being reduced and the successful accumulation of 5-MTHF to 44.57 μg/L. Subsequently, formate dehydrogenases from Candida boidinii and Candida dubliniensis were expressed, which were capable of catalyzing the reaction of sodium formate oxidation for NAD(P)H regeneration. This further increased the NAD(P)H supply, leading to a rise in 5-MTHF production to 247.36 μg/L. Moreover, to maintain the balance between NADH and NADPH, pntAB and sthA, encoding transhydrogenase, were overexpressed. Finally, by overexpressing six key enzymes in the folate to 5-MTHF pathway and employing fed-batch cultivation in a 3 L fermenter, strain Z13 attained a peak 5-MTHF titer of 3009.03 μg/L, the highest level reported in E. coli so far. This research is a significant step toward industrial-scale microbial 5-MTHF production.

Further delineation of the phenotypic and metabolomic profile of ALDH1L2-related neurodevelopmental disorder

ALDH1L2, a mitochondrial enzyme in folate metabolism, converts 10-formyl-THF (10-formyltetrahydrofolate) to THF (tetrahydrofolate) and CO2. At the cellular level, deficiency of this NADP+-dependent reaction results in marked reduction in NADPH/NADP+ ratio and reduced mitochondrial ATP. Thus far, a single patient with biallelic ALDH1L2 variants and the phenotype of a neurodevelopmental disorder has been reported. Here, we describe another patient with a neurodevelopmental disorder associated with a novel homozygous missense variant in ALDH1L2, Pro133His. The variant caused marked reduction in the ALDH1L2 enzyme activity in skin fibroblasts derived from the patient as probed by 10-FDDF, a stable synthetic analog of 10-formyl-THF. Additional associated abnormalities in these fibroblasts include reduced NADPH/NADP+ ratio and pool of mitochondrial ATP, upregulated autophagy and dramatically altered metabolomic profile. Overall, our study further supports a link between ALDH1L2 deficiency and abnormal neurodevelopment in humans.

Metabolic reprogramming of the retinal pigment epithelium by cytokines associated with age-related macular degeneration

The complex metabolic relationship between the retinal pigment epithelium (RPE) and photoreceptors is essential for maintaining retinal health. Recent evidence indicates the RPE acts as an adjacent lactate sink, suppressing glycolysis in the epithelium in order to maximize glycolysis in the photoreceptors. Dysregulated metabolism within the RPE has been implicated in the pathogenesis of age-related macular degeneration (AMD), a leading cause of vision loss. In the present study, we investigate the effects of four cytokines associated with AMD, TNFα, TGF-β2, IL-6, and IL-1β, as well as a cocktail containing all four cytokines, on RPE metabolism using ARPE-19 cells, primary human RPE cells, and ex vivo rat eyecups. Strikingly, we found cytokine-specific changes in numerous metabolic markers including lactate production, glucose consumption, extracellular acidification rate, and oxygen consumption rate accompanied by increases in total mitochondrial volume and ATP production. Together, all four cytokines could potently override the constitutive suppression of glycolysis in the RPE, through a mechanism independent of PI3K/AKT, MEK/ERK, or NF-κB. Finally, we observed changes in glycolytic gene expression with cytokine treatment, including in lactate dehydrogenase subunit and glucose transporter expression. Our findings provide new insights into the metabolic changes in the RPE under inflammatory conditions and highlight potential therapeutic targets for AMD.

Comparative Transcriptomic Analysis of Gossypium hirsutum Fiber Development in Mutant Materials (xin w 139) Provides New Insights into Cotton Fiber Development

Cotton is the most widely planted fiber crop in the world, and improving cotton fiber quality has long been a research hotspot. The development of cotton fibers is a complex process that includes four consecutive and overlapping stages, and although many studies on cotton fiber development have been reported, most of the studies have been based on cultivars that are promoted in production or based on lines that are used in breeding. Here, we report a phenotypic evaluation of Gossypium hirsutum based on immature fiber mutant (xin w 139) and wild-type (Xin W 139) lines and a comparative transcriptomic study at seven time points during fiber development. The results of the two-year study showed that the fiber length, fiber strength, single-boll weight and lint percentage of xin w 139 were significantly lower than those of Xin W 139, and there were no significant differences in the other traits. Principal component analysis (PCA) and cluster analysis of the RNA-sequencing (RNA-seq) data revealed that these seven time points could be clearly divided into three different groups corresponding to the initiation, elongation and secondary cell wall (SCW) synthesis stages of fiber development, and the differences in fiber development between the two lines were mainly due to developmental differences after twenty days post anthesis (DPA). Differential expression analysis revealed a total of 5131 unique differentially expressed genes (DEGs), including 290 transcription factors (TFs), between the 2 lines. These DEGs were divided into five clusters. Each cluster functional category was annotated based on the KEGG database, and different clusters could describe different stages of fiber development. In addition, we constructed a gene regulatory network by weighted correlation network analysis (WGCNA) and identified 15 key genes that determined the differences in fiber development between the 2 lines. We also screened seven candidate genes related to cotton fiber development through comparative sequence analysis and qRT-PCR; these genes included three TFs (GH_A08G1821 (bHLH), GH_D05G3074 (Dof), and GH_D13G0161 (C3H)). These results provide a theoretical basis for obtaining an in-depth understanding of the molecular mechanism of cotton fiber development and provide new genetic resources for cotton fiber research.

Disulfidptosis: disulfide stress-induced cell death

The cystine transporter solute carrier family 7 member 11 (SLC7A11) (also known as xCT) promotes glutathione synthesis and counters oxidative stress-induced cell death, including ferroptosis, by importing cystine. Also, SLC7A11 plays a crucial role in tumor development. However, recent studies have uncovered an unexpected role of SLC7A11 in promoting disulfidptosis, a novel form of regulated cell death induced by disulfide stress. In this review, we examine the opposing roles of SLC7A11 in regulating redox homeostasis and cell survival/death, summarize current knowledge on disulfidptosis, and explore its potential in disease treatment. A deeper understanding of disulfidptosis will offer new insights into fundamental cellular homeostasis and facilitate the development of innovative therapies for disease treatment.

A three-level regulatory mechanism of the aldo-keto reductase subfamily AKR12D

Modulation of protein function through allosteric regulation is central in biology, but biomacromolecular systems involving multiple subunits and ligands may exhibit complex regulatory mechanisms at different levels, which remain poorly understood. Here, we discover an aldo-keto reductase termed AKRtyl and present its three-level regulatory mechanism. Specifically, by combining steady-state and transient kinetics, X-ray crystallography and molecular dynamics simulation, we demonstrate that AKRtyl exhibits a positive synergy mediated by an unusual Monod-Wyman-Changeux (MWC) paradigm of allosteric regulation at low concentrations of the cofactor NADPH, but an inhibitory effect at high concentrations is observed. While the substrate tylosin binds at a remote allosteric site with positive cooperativity. We further reveal that these regulatory mechanisms are conserved in AKR12D subfamily, and that substrate cooperativity is common in AKRs across three kingdoms of life. This work provides an intriguing example for understanding complex allosteric regulatory networks.

Real-time resolution studies of the regulation of lactate production by hexokinases binding to mitochondria in single cells

During hypoxia accumulation of lactate may be a key factor in acidosis-induced tissue damage. Binding of hexokinase (HK) to the outer membrane of mitochondria may have a protective effect under these conditions. We have investigated the regulation of lactate metabolism by hexokinases (HKs), using HEK293 cells in which the endogenous hexokinases have been knocked down to enable overexpression of wild type and mutant HKs. To assess the real-time changes in intracellular lactate levels the cells were also transfected with a lactate specific FRET probe. In the HKI/HKII double knockdown HEK cells, addition of extracellular pyruvate caused a large and sustained decrease in lactate. Upon inhibition of the mitochondrial electron transfer chain by NaCN this effect was reversed as a rapid increase in lactate developed which was followed by a slow and sustained increase in the continued presence of the inhibitor. Incubation of the HKI/HKII double knockdown HEK cells with the inhibitor of the malic enzyme, ME1*, blocked the delayed accumulation of lactate evoked by NaCN. With replacement by overexpression of HKI or HKII the accumulation of intracellular lactate evoked by NaCN was prevented. Blockage of the pentose phosphate pathway with the inhibitor 6-aminonicotinamide (6-AN) abolished the protective effect of HK expression, with NaCN causing again a sustained increase in lactate. The effect of HK was dependent on HK's catalytic activity and interaction with the mitochondrial outer membrane (MOM). Based on these data we propose that transformation of glucose into G6P by HK activates the pentose phosphate pathway which increases the production of NADPH, which then blocks the activity of the malic enzyme to transform malate into pyruvate and lactate.

RIOK3 sustains colorectal cancer cell survival under glucose deprivation via an HSP90α-dependent pathway

Glucose oxidation via the pentose phosphate pathway serves as the primary cellular mechanism for generating nicotinamide adenine dinucleotide phosphate (NADPH). The central regions of solid tumors typically experience glucose deficiency, emphasizing the need for sustained NADPH production crucial to tumor cell survival. This study highlights the crucial role of RIOK3 in maintaining NADPH production and colorectal cancer (CRC) cell survival during glucose deficiency. Our findings revealed upregulated RIOK3 expression upon glucose deprivation, with RIOK3 knockout significantly reducing cancer cell survival. Mechanistically, RIOK3 interacts with heat shock protein 90α (HSP90α), a chaperone integral to various cellular processes, thereby facilitating HSP90α binding to isocitrate dehydrogenase 1 (IDH1). This interaction further upregulates IDH1 expression, enhancing NADPH production and preserving redox balance. Furthermore, RIOK3 inhibition had no discernible effect on intracellular NADPH levels and cell death rates in HSP90α-knockdown cells. Collectively, our findings suggest that RIOK3 sustains colon cancer cell survival in low-glucose environments through an HSP90α-dependent pathway. This highlights the significance of the RIOK3-HSP90α-IDH1 cascade, providing insights into potential targeted therapeutic strategies for CRC in metabolic stress conditions.

Structural and functional characterization of 6-phosphogluconate dehydrogenase in Plasmodium falciparum (3D7) and identification of its potent inhibitors

The malarial parasite Plasmodium falciparum predominantly causes severe malaria and deaths worldwide. Moreover, resistance developed by P. falciparum to frontline drugs in recent years has markedly increased malaria-related deaths in South Asian Countries. Ribulose 5-phosphate and NADPH synthesized by Pentose Phosphate Pathway (PPP) act as a direct precursor for nucleotide synthesis and P. falciparum survival during oxidative challenges in the intra-erythrocytic growth phase . In the present study, we have elucidated the structure and functional characteristics of 6-phosphogluconate dehydrogenase (6PGD) in P. falciparum and have identified potent hits against 6PGD by pharmacophore-based virtual screening with ZINC and ChemBridge databases. Molecular docking and Molecular dynamics simulation, binding free energies (MMGBSA & MMPBSA), and Density Functional Theory (DFT) calculations were integratively employed to validate and prioritize the most potential hits. The 6PGD structure was found to have an open and closed conformation during MD simulation. The apo form of 6PGD was found to be in closed conformation, while a open conformation attributed to facilitating binding of cofactor. It was also inferred from the conformational analysis that the small domain of 6PGD has a high influence in altering the conformation that may aid in open/closed conformation of 6PGD. The top three hits identified using pharmacophore hypotheses were ChemBridge_11084819, ChemBridge_80178394, and ChemBridge_17912340. Though all three hits scored a high glide score, MMGBSA, and favorable ADMET properties, ChemBridge_11084819 and ChemBrdige_17912340 showed higher stability and binding free energy. Moreover, these hits also featured stable H-bond interactions with the active loop of 6PGD with binding free energy comparable to substrate-bound complex. Therefore, the ChemBridge_11084819 and ChemBridge_17912340 moieties demonstrate to have high therapeutic potential against 6PGD in P. falciparum.Communicated by Ramaswamy H. Sarma.

Mitochondrial isocitrate dehydrogenase impedes CAR T cell function by restraining antioxidant metabolism and histone acetylation

The efficacy of chimeric antigen receptor (CAR) T cell therapy is hampered by relapse in hematologic malignancies and by hyporesponsiveness in solid tumors. Long-lived memory CAR T cells are critical for improving tumor clearance and long-term protection. However, during rapid ex vivo expansion or in vivo tumor eradication, metabolic shifts and inhibitory signals lead to terminal differentiation and exhaustion of CAR T cells. Through a mitochondria-related compound screening, we find that the FDA-approved isocitrate dehydrogenase 2 (IDH2) inhibitor enasidenib enhances memory CAR T cell formation and sustains anti-leukemic cytotoxicity in vivo. Mechanistically, IDH2 impedes metabolic fitness of CAR T cells by restraining glucose utilization via the pentose phosphate pathway, which alleviates oxidative stress, particularly in nutrient-restricted conditions. In addition, IDH2 limits cytosolic acetyl-CoA levels to prevent histone acetylation that promotes memory cell formation. In combination with pharmacological IDH2 inhibition, CAR T cell therapy is demonstrated to have superior efficacy in a pre-clinical model.

Nicotinamide Mononucleotide in the Context of Myocardiocyte Longevity

Cellular and subcellular metabolic activities are crucial processes involved in the regulation of intracellular homeostasis, including cellular and subcellular signaling pathways. Dysregulation of intracellular regulation mechanisms is catastrophic and cumulates into cell death. To overcome the issue of dysregulation of intracellular regulation mechanisms, the preservation of subcellular and extracellular components is essential to maintain healthy cells with increased longevity. Several physiopathological changes occur during cell ageing, one of which is the dysregulation of intracellular physiology of the oxidative phosphorylation process. Nicotinamide mononucleotide (NMN) remains in the debut of anti-aging therapeutic effect. Aged myocardiocyte characterized by disrupted NMN and or its precursors or signaling pathways. Simultaneously, several other pathophysiological occur that collectively impair intracellular homeostasis. The NMN role in the antiaging effect remains unclear and several hypotheses have been introduced into describing the mechanism and the potential outcomes from NMN exogenous supply. Correction of the impaired intracellular homeostasis includes correction to the NMN metabolism. Additionally, autophagy correction, which is the key element in the regulation of intracellular intoxication, including oxidative stress, unfolding protein response, and other degradation of intracellular metabolites. Several signaling pathways are involved in the regulation mechanism of NMN effects on myocardiocyte health and further longevity. NMN protects myocardiocytes from ischemic injury by reducing anabolism and, increasing catabolism and further passing the myocardiocytes into dormant status. NMN applications include ischemic heart, disease, and failed heart, as well as dilated cardiomyopathies. Cytosolic and mitochondrial NADPH are independently functioning and regulating. Each of these plays a role in the determination of the longevity of the myocardiocytes. NMN has a cornerstone in the functionality of Sirtuins, which are an essential anti-senescent intrinsic molecule. The study aims to assess the role of NMN in the longevity and antisenescent of myocardiocytes.

A new mathematical model of folate homeostasis in E. coli highlights the potential importance of the folinic acid futile cycle in cell growth

Folate (vitamin B9) plays a central role in one-carbon metabolism in prokaryotes and eukaryotes. This pathway mediates the transfer of one-carbon units, playing a crucial role in nucleotide synthesis, methylation, and amino acid homeostasis. The folinic acid futile cycle adds a layer of intrigue to this pathway, due to its associations with metabolism, cell growth, and dormancy. It also introduces additional complexity to folate metabolism. A logical way to deal with such complexity is to examine it by using mathematical modelling. This work describes the construction and analysis of a model of folate metabolism, which includes the folinic acid futile cycle. This model was tested under three in silico growth conditions. Model simulations revealed: 1) the folate cycle behaved as a stable biochemical system in three growth states (slow, standard, and rapid); 2) the initial concentration of serine had the greatest impact on metabolite concentrations; 3) 5-formyltetrahydrofolate cyclo-ligase (5-FCL) activity had a significant impact on the levels of the 7 products that carry the one-carbon donated from folates, and the redox couple NADP/NADPH; this was particularly evident in the rapid growth state; 4) 5-FCL may be vital to the survival of the cells by maintaining low levels of homocysteine, as high levels can induce toxicity; and 5) the antifolate therapeutic trimethoprim had a greater impact on folate metabolism with higher nutrient availability. These results highlight the important role of 5-FCL in intracellular folate homeostasis and mass generation under different metabolic scenarios.

Copper homeostasis and copper-induced cell death： Novel targeting for intervention in the pathogenesis of vascular aging

Copper-induced cell death, also known as cuproptosis, is distinct from other types of cell death such as apoptosis, necrosis, and ferroptosis. It can trigger the accumulation of lethal reactive oxygen species, leading to the onset and progression of aging. The significant increases in copper ion levels in the aging populations confirm a close relationship between copper homeostasis and vascular aging. On the other hand, vascular aging is also closely related to the occurrence of various cardiovascular diseases throughout the aging process. However, the specific causes of vascular aging are not clear, and different living environments and stress patterns can lead to individualized vascular aging. By exploring the correlations between copper-induced cell death and vascular aging, we can gain a novel perspective on the pathogenesis of vascular aging and enhance the prognosis of atherosclerosis. This article aims to provide a comprehensive review of the impacts of copper homeostasis on vascular aging, including their effects on endothelial cells, smooth muscle cells, oxidative stress, ferroptosis, intestinal flora, and other related factors. Furthermore, we intend to discuss potential strategies involving cuproptosis and provide new insights for copper-related vascular aging.

NADPH Dynamics: Linking Insulin Resistance and β-Cells Ferroptosis in Diabetes Mellitus

This review offers an in-depth exploration of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) in metabolic health. It delves into how NADPH affects insulin secretion, influences insulin resistance, and plays a role in ferroptosis. NADPH, a critical cofactor in cellular antioxidant systems and lipid synthesis, plays a central role in maintaining metabolic homeostasis. In adipocytes and skeletal muscle, NADPH influences the pathophysiology of insulin resistance, a hallmark of metabolic disorders such as type 2 diabetes and obesity. The review explores the mechanisms by which NADPH contributes to or mitigates insulin resistance, including its role in lipid and reactive oxygen species (ROS) metabolism. Parallelly, the paper investigates the dual nature of NADPH in the context of pancreatic β-cell health, particularly in its relation to ferroptosis, an iron-dependent form of programmed cell death. While NADPH's antioxidative properties are crucial for preventing oxidative damage in β-cells, its involvement in lipid metabolism can potentiate ferroptotic pathways under certain pathological conditions. This complex relationship underscores the delicate balance of NADPH homeostasis in pancreatic health and diabetes pathogenesis. By integrating findings from recent studies, this review aims to illuminate the nuanced roles of NADPH in different tissues and its potential as a therapeutic target. Understanding these dynamics offers vital insights into the development of more effective strategies for managing insulin resistance and preserving pancreatic β-cell function, thereby advancing the treatment of metabolic diseases.

The Emerging Roles of the Metabolic Regulator G6PD in Human Cancers

Metabolic reprogramming, especially reprogrammed glucose metabolism, is a well-known cancer hallmark related to various characteristics of tumor cells, including proliferation, survival, metastasis, and drug resistance. Glucose-6-phosphate dehydrogenase (G6PD) is the first and rate-limiting enzyme of the pentose phosphate pathway (PPP), a branch of glycolysis, that converts glucose-6-phosphate (G6P) into 6-phosphogluconolactone (6PGL). Furthermore, PPP produces ribose-5-phosphate (R5P), which provides sugar-phosphate backbones for nucleotide synthesis as well as nicotinamide adenine dinucleotide phosphate (NADPH), an important cellular reductant. Several studies have shown enhanced G6PD expression and PPP flux in various tumor cells, as well as their correlation with tumor progression through cancer hallmark regulation, especially reprogramming cellular metabolism, sustaining proliferative signaling, resisting cell death, and activating invasion and metastasis. Inhibiting G6PD could suppress tumor cell proliferation, promote cell death, reverse chemoresistance, and inhibit metastasis, suggesting the potential of G6PD as a target for anti-tumor therapeutic strategies. Indeed, while challenges-including side effects-still remain, small-molecule G6PD inhibitors showing potential anti-tumor effect either when used alone or in combination with other anti-tumor drugs have been developed. This review provides an overview of the structural significance of G6PD, its role in and regulation of tumor development and progression, and the strategies explored in relation to G6PD-targeted therapy.

Deeper insight into ferroptosis: association with Alzheimer's, Parkinson's disease, and brain tumors and their possible treatment by nanomaterials induced ferroptosis

Ferroptosis is an emerging and novel type of iron-dependent programmed cell death which is mainly caused by the excessive deposition of free intracellular iron in the brain cells. This deposited free iron exerts a ferroptosis pathway, resulting in lipid peroxidation (LiPr). There are mainly three ferroptosis pathways viz. iron metabolism-mediated cysteine/glutamate, and LiPr-mediated. Iron is required by the brain as a redox metal for several physiological activities. Due to the iron homeostasis balance disruption, the brain gets adversely affected which further causes neurodegenerative diseases (NDDs) like Parkinson's and Alzheimer's disease, strokes, and brain tumors like glioblastoma (GBS), and glioma. Nanotechnology has played an important role in the prevention and treatment of these NDDs. A synergistic effect of nanomaterials and ferroptosis could prove to be an effective and efficient approach in the field of nanomedicine. In the current review, the authors have highlighted all the latest research in the field of ferroptosis, specifically emphasizing on the role of major molecular key players and various mechanisms involved in the ferroptosis pathway. Moreover, here the authors have also addressed the correlation of ferroptosis with the pathophysiology of NDDs and theragnostic effect of ferroptosis and nanomaterials for the prevention and treatment of NDDs.

The ubiquitin-proteasome system links NADPH metabolism to ferroptosis

Ferroptosis is the type of cell death arising from uncontrolled and excessive lipid peroxidation. NADPH is essential for ferroptosis regulation because it supplies reducing equivalents for antioxidant defense systems and contributes to the generation of reactive oxygen species. Moreover, NADPH level serves as a biomarker for predicting the sensitivity of cells to ferroptosis. The ubiquitin-proteasome system governs the stability of many ferroptosis effectors. Recent research has revealed MARCHF6, the endoplasmic reticulum ubiquitin ligase, as an unprecedented NADPH sensor in the ubiquitin system and a critical regulator of ferroptosis involved in tumorigenesis and fetal development. This review summarizes the current understanding of NADPH metabolism and the ubiquitin-proteasome system in regulating ferroptosis and highlights the emerging importance of MARCHF6 as a vital connector between NADPH metabolism and ferroptosis.

Glucose-6-phosphate dehydrogenase deficiency accelerates pancreatic acinar-to-ductal metaplasia

Activating mutations in KRAS extensively reprogram cellular metabolism to support the continuous growth, proliferation, and survival of pancreatic tumors. Targeting these metabolic dependencies are promising approaches for the treatment of established tumors. However, metabolic reprogramming is required early during tumorigenesis to provide transformed cells selective advantage towards malignancy. Acinar cells can give rise to pancreatic tumors through acinar-to-ductal metaplasia (ADM). Dysregulation of pathways that maintain acinar homeostasis accelerate tumorigenesis. During ADM, acinar cells transdifferentiate to duct-like cells, a process driven by oncogenic KRAS. The metabolic reprogramming that is required for the transdifferentiation in ADM is unclear. We performed transcriptomic analysis on mouse acinar cells undergoing ADM and found metabolic programs are globally enhanced, consistent with the transition of a specialized cell to a less differentiated phenotype with proliferative potential. Indeed, we and others have demonstrated how inhibiting metabolic pathways necessary for ADM can prevent transdifferentiation and tumorigenesis. Here, we also find NRF2-target genes are differentially expressed during ADM. Among these, we focused on the increase in the gene coding for NADPH-producing enzyme, Glucose-6-phosphate dehydrogenase (G6PD). Using established mouse models of KrasG12D-driven pancreatic tumorigenesis and G6PD-deficiency, we find that mutant G6pd accelerates ADM and pancreatic intraepithelial neoplasia. Acceleration of cancer initiation with G6PD-deficiency is dependent on its NADPH-generating function in reactive oxygen species (ROS) management, as opposed to other outputs of the pentose phosphate pathway. Together, this work provides new insights into the function of metabolic pathways during early tumorigenesis.

Real-time resolution studies of the regulation of pyruvate-dependent lactate metabolism by hexokinases in single cells

Lactate is a mitochondrial substrate for many tissues including neuron, muscle, skeletal and cardiac, as well as many cancer cells, however little is known about the processes that regulate its utilization in mitochondria. Based on the close association of Hexokinases (HK) with mitochondria, and the known cardio-protective role of HK in cardiac muscle, we have investigated the regulation of lactate and pyruvate metabolism by hexokinases (HKs), utilizing wild-type HEK293 cells and HEK293 cells in which the endogenous HKI and/or HKII have been knocked down to enable overexpression of wild type and mutant HKs. To assess the real-time changes in intracellular lactate levels the cells were transfected with a lactate specific FRET probe. In the HKI/HKII double knockdown cells, addition of extracellular pyruvate caused a large and sustained decrease in lactate. This decrease was rapidly reversed upon inhibition of the malate aspartate shuttle by aminooxyacetate, or inhibition of mitochondrial oxidative respiration by NaCN. These results suggest that in the absence of HKs, pyruvate-dependent activation of the TCA cycle together with the malate aspartate shuttle facilitates lactate transformation into pyruvate and its utilization by mitochondria. With replacement by overexpression of HKI or HKII the cellular response to pyruvate and NaCN was modified. With either hexokinase present, both the decrease in lactate due to the addition of pyruvate and the increase following addition of NaCN were either transient or suppressed altogether. Blockage of the pentose phosphate pathway with the inhibitor 6-aminonicotinamide (6-AN), abolished the effects of HK replacement. These results suggest that blocking of the malate aspartate shuttle by HK may involve activation of the pentose phosphate pathway and increased NADPH production.

Uncovering global lipid accumulation routes towards docosahexaenoic acid (DHA) production in Aurantiochytrium sp. SW1 using integrative proteomic analysis

Aurantiochytrium sp., a marine thraustochytrid possesses a remarkable ability to produce lipid rich in polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Although gene regulation underlying lipid biosynthesis has been previously reported, proteomic analysis is still limited. In this study, high DHA accumulating strain Aurantiochytrium sp. SW1 has been used as a study model to elucidate the alteration in proteome profile under different cultivation phases i.e. growth, nitrogen-limitation and lipid accumulation. Of the total of 5146 identified proteins, 852 proteins were differentially expressed proteins (DEPs). The largest number of DEPs (488 proteins) was found to be uniquely expressed between lipid accumulating phase and growth phase. Interestingly, there were up-regulated proteins involved in glycolysis, glycerolipid, carotenoid and glutathione metabolism which were preferable metabolic routes towards lipid accumulation and DHA production as well as cellular oxidative defence. Integrated proteomic and transcriptomic data were also conducted to comprehend the gene and protein regulation underlying the lipid and DHA biosynthesis. A significant up-regulation of acetyl-CoA synthetase was observed which suggests alternative route of acetate metabolism for acetyl-CoA producer. This study presents the holistic routes underlying lipid accumulation and DHA production in Aurantiochytrium sp. SW1 and other relevant thraustochytrid.