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Cell Metabolism Sep 2023Neddylation is a post-translational mechanism that adds a ubiquitin-like protein, namely neural precursor cell expressed developmentally downregulated protein 8 (NEDD8)....
Neddylation is a post-translational mechanism that adds a ubiquitin-like protein, namely neural precursor cell expressed developmentally downregulated protein 8 (NEDD8). Here, we show that neddylation in mouse liver is modulated by nutrient availability. Inhibition of neddylation in mouse liver reduces gluconeogenic capacity and the hyperglycemic actions of counter-regulatory hormones. Furthermore, people with type 2 diabetes display elevated hepatic neddylation levels. Mechanistically, fasting or caloric restriction of mice leads to neddylation of phosphoenolpyruvate carboxykinase 1 (PCK1) at three lysine residues-K278, K342, and K387. We find that mutating the three PCK1 lysines that are neddylated reduces their gluconeogenic activity rate. Molecular dynamics simulations show that neddylation of PCK1 could re-position two loops surrounding the catalytic center into an open configuration, rendering the catalytic center more accessible. Our study reveals that neddylation of PCK1 provides a finely tuned mechanism of controlling glucose metabolism by linking whole nutrient availability to metabolic homeostasis.
Topics: Mice; Animals; Phosphoenolpyruvate; Diabetes Mellitus, Type 2; Proteins; Liver; Lysine; Glucose
PubMed: 37541251
DOI: 10.1016/j.cmet.2023.07.003 -
The Journal of Clinical Investigation Jul 2023Deciphering the crosstalk between metabolic reprogramming and epigenetic regulation is a promising strategy for cancer therapy. In this study, we discovered that the...
Deciphering the crosstalk between metabolic reprogramming and epigenetic regulation is a promising strategy for cancer therapy. In this study, we discovered that the gluconeogenic enzyme PCK1 fueled the generation of S-adenosylmethionine (SAM) through the serine synthesis pathway. The methyltransferase SUV39H1 catalyzed SAM, which served as a methyl donor to support H3K9me3 modification, leading to the suppression of the oncogene S100A11. Mechanistically, PCK1 deficiency-induced oncogenic activation of S100A11 was due to its interaction with AKT1, which upregulated PI3K/AKT signaling. Intriguingly, the progression of hepatocellular carcinoma (HCC) driven by PCK1 deficiency was suppressed by SAM supplement or S100A11 KO in vivo and in vitro. These findings reveal the availability of the key metabolite SAM as a bridge connecting the gluconeogenic enzyme PCK1 and H3K9 trimethylation in attenuating HCC progression, thus suggesting a potential therapeutic strategy against HCC.
Topics: Humans; Carcinoma, Hepatocellular; S-Adenosylmethionine; Liver Neoplasms; Phosphatidylinositol 3-Kinases; Epigenesis, Genetic; Phosphoenolpyruvate Carboxykinase (GTP); Intracellular Signaling Peptides and Proteins
PubMed: 37166978
DOI: 10.1172/JCI161713 -
Plant Communications Sep 2023JUJUNCAO (Cenchrus fungigraminus; 2n = 4x = 28) is a Cenchrus grass with the highest biomass production among cultivated plants, and it can be used for mushroom...
JUJUNCAO (Cenchrus fungigraminus; 2n = 4x = 28) is a Cenchrus grass with the highest biomass production among cultivated plants, and it can be used for mushroom cultivation, animal feed, and biofuel production. Here, we report a nearly complete genome assembly of JUJUNCAO and reveal that JUJUNCAO is an allopolyploid that originated ∼2.7 million years ago (mya). Its genome consists of two subgenomes, and subgenome A shares high collinear synteny with pearl millet. We also investigated the genome evolution of JUJUNCAO and suggest that the ancestral karyotype of Cenchrus split into the A and B ancestral karyotypes of JUJUNCAO. Comparative transcriptome and DNA methylome analyses revealed functional divergence of homeologous gene pairs between the two subgenomes, which was a further indication of asymmetric DNA methylation. The three types of centromeric repeat in the JUJUNCAO genome (CEN137, CEN148, and CEN156) may have evolved independently within each subgenome, with some introgressions of CEN156 from the B to the A subgenome. We investigated the photosynthetic characteristics of JUJUNCAO, revealing its typical C Kranz anatomy and high photosynthetic efficiency. NADP-ME and PEPCK appear to cooperate in the major C decarboxylation reaction of JUJUNCAO, which is different from other C photosynthetic subtypes and may contribute to its high photosynthetic efficiency and biomass yield. Taken together, our results provide insights into the highly efficient photosynthetic mechanism of JUJUNCAO and provide a valuable reference genome for future genetic and evolutionary studies, as well as genetic improvement of Cenchrus grasses.
Topics: Cenchrus; Plant Leaves; Photosynthesis; Poaceae; Phosphoenolpyruvate Carboxylase
PubMed: 37271992
DOI: 10.1016/j.xplc.2023.100633 -
Nature Communications Jul 2023Neutrophils rely predominantly on glycolytic metabolism for their biological functions, including reactive oxygen species (ROS) production. Although pyruvate kinase M2...
Neutrophils rely predominantly on glycolytic metabolism for their biological functions, including reactive oxygen species (ROS) production. Although pyruvate kinase M2 (PKM2) is a glycolytic enzyme known to be involved in metabolic reprogramming and gene transcription in many immune cell types, its role in neutrophils remains poorly understood. Here, we report that PKM2 regulates ROS production and microbial killing by neutrophils. Zymosan-activated neutrophils showed increased cytoplasmic expression of PKM2. Pharmacological inhibition or genetic deficiency of PKM2 in neutrophils reduced ROS production and Staphylococcus aureus killing in vitro. In addition, this also resulted in phosphoenolpyruvate (PEP) accumulation and decreased dihydroxyacetone phosphate (DHAP) production, which is required for de novo synthesis of diacylglycerol (DAG) from glycolysis. In vivo, PKM2 deficiency in myeloid cells impaired the control of infection with Staphylococcus aureus. Our results fill the gap in the current knowledge of the importance of lower glycolysis for ROS production in neutrophils, highlighting the role of PKM2 in regulating the DHAP and DAG synthesis to promote ROS production in neutrophils.
Topics: Pyruvate Kinase; Reactive Oxygen Species; Neutrophils; Phosphorylation; Glycolysis
PubMed: 37460614
DOI: 10.1038/s41467-023-40021-6 -
Molecular Therapy Oncolytics Dec 2023Aerobic glycolysis is a hallmark property of cancer metabolism. Enolase is a glycolytic enzyme that catalyzes the conversion of 2-phosphoglycerate into... (Review)
Review
Aerobic glycolysis is a hallmark property of cancer metabolism. Enolase is a glycolytic enzyme that catalyzes the conversion of 2-phosphoglycerate into phosphoenolpyruvate. In mammals, enolases exist in three isoforms, encoded by the genes , , and . The altered expression of enolases is a common occurrence in various types of cancer. Although most published studies on enolases have predominantly focused on the role of ENO1 in cancer, ENO2 and ENO3 have recently emerged as crucial regulatory molecules in cancer development. Significant progress has been made in understanding their multifaceted roles in oncogenesis. In this comprehensive review, we provide an overview of the structure, subcellular localization, diagnostic and prognostic significance, biological functions, and molecular mechanisms of ENO2 and ENO3 in cancer progression. The importance of enolase in cancer development makes it a novel therapeutic target for clinical applications. Furthermore, we discuss anticancer agents designed to target enolases and summarize their anticancer efficacy in both and studies.
PubMed: 38075246
DOI: 10.1016/j.omto.2023.100750 -
Advanced Biology Jul 2023Certain metabolic interventions such as caloric restriction, fasting, exercise, and a ketogenic diet extend lifespan and/or health span. However, their benefits are... (Review)
Review
Certain metabolic interventions such as caloric restriction, fasting, exercise, and a ketogenic diet extend lifespan and/or health span. However, their benefits are limited and their connections to the underlying mechanisms of aging are not fully clear. Here, these connections are explored in terms of the tricarboxylic acid (TCA) cycle (Krebs cycle, citric acid cycle) to suggest reasons for the loss of effectiveness and ways of overcoming it. Specifically, the metabolic interventions deplete acetate and likely reduce the conversion of oxaloacetate to aspartate, thereby inhibiting the mammalian target of rapamycin (mTOR) and upregulating autophagy. Synthesis of glutathione may provide a high-capacity sink for amine groups, facilitating autophagy, and prevent buildup of alpha-ketoglutarate, supporting stem cell maintenance. Metabolic interventions also prevent the accumulation of succinate, thereby slowing DNA hypermethylation, facilitating the repair of DNA double-strand breaks, reducing inflammatory and hypoxic signaling, and lowering reliance on glycolysis. In part through these mechanisms, metabolic interventions may decelerate aging, extending lifespan. Conversely, with overnutrition or oxidative stress, these processes function in reverse, accelerating aging and impairing longevity. Progressive damage to aconitase, inhibition of succinate dehydrogenase, and downregulation of hypoxia-inducible factor-1α, and phosphoenolpyruvate carboxykinase (PEPCK) emerge as potentially modifiable reasons for the loss of effectiveness of metabolic interventions.
Topics: Citric Acid Cycle; Aconitate Hydratase; Glycolysis; DNA
PubMed: 37132059
DOI: 10.1002/adbi.202300095 -
Elevated liver glycogenolysis mediates higher blood glucose during acute exercise in Barth syndrome.PloS One 2023Barth syndrome (BTHS) is an X-linked recessive genetic disorder due to mutations in the Tafazzin (TAFAZZIN) gene that lead to cardiac and skeletal muscle mitochondrial...
UNLABELLED
Barth syndrome (BTHS) is an X-linked recessive genetic disorder due to mutations in the Tafazzin (TAFAZZIN) gene that lead to cardiac and skeletal muscle mitochondrial dysfunction. Previous studies in humans with BTHS demonstrate that the defects in muscle mitochondrial oxidative metabolism result in an enhanced reliance on anaerobic metabolism during exercise to meet energy demands of muscular work. During exercise, the liver normally increases glucose production via glycogenolysis and gluconeogenesis to match the elevated rate of muscle glucose uptake and meet the ATP requirements of working muscle. However, the impact of Tafazzin deficiency on hepatic glucose production and the pathways contributing to hepatic glucose production during exercise is unknown. Therefore, the purpose of this study was to quantify in vivo liver gluconeogenesis and glycogenolysis in Tafazzin knockdown mice at rest and during acute exercise.
METHODS
Male TAFAZZIN shRNA transgenic (TG) and wild-type (WT) mice completed exhaustive treadmill running protocols to test exercise tolerance. Mice underwent 2H- and 13C-stable isotope infusions at rest and during a 30-minute treadmill running bout to quantify hepatic glucose production and associated nutrient fluxes under sedentary conditions and during acute exercise. Circulating and tissue (skeletal muscle and liver) samples were obtained during and following exercise to assess static metabolite levels.
RESULTS
TG mice reached exhaustion sooner during exhaustive treadmill running protocols and exhibited higher plasma lactate concentrations after exhaustive exercise compared to WT mice. Arterial glucose levels were comparable between genotypes at rest, but higher in TG mice compared to WT mice during exercise. Consistent with the higher blood glucose, TG mice showed increased endogenous glucose production owing to elevated glycogenolysis compared to WT mice during exercise. Total gluconeogenesis, gluconeogenesis from glycerol, gluconeogenesis from phosphoenolpyruvate, pyruvate cycling, total cataplerosis, and anaplerotic fluxes were similar between TG and WT mice at rest and during exercise. However, lactate dehydrogenase flux and TCA cycle fluxes trended higher in TG mice during exercise. Liver glycogen content in TG was higher in TG vs. controls.
CONCLUSION
Our data in the Tafazzin knockdown mouse suggest that elevated anaerobic metabolism during rest and exercise previously reported in humans with BTHS are supported by the finding of higher hepatic glycogenolysis.
Topics: Humans; Male; Animals; Mice; Glycogenolysis; Blood Glucose; Barth Syndrome; Liver; Hyperglycemia; Glucose; Mice, Transgenic; Genetic Diseases, X-Linked; Muscle, Skeletal
PubMed: 37651450
DOI: 10.1371/journal.pone.0290832 -
Annals of Botany Nov 2023This review summarizes recent advances in our understanding of Crassulacean Acid Metabolism (CAM) by integrating evolutionary, ecological, physiological, metabolic and... (Review)
Review
BACKGROUND AND SCOPE
This review summarizes recent advances in our understanding of Crassulacean Acid Metabolism (CAM) by integrating evolutionary, ecological, physiological, metabolic and molecular perspectives. A number of key control loops which moderate the expression of CAM phases, and their metabolic and molecular control, are explored. These include nocturnal stomatal opening, activation of phosphoenolpyruvate carboxylase by a specific protein kinase, interactions with circadian clock control, as well as daytime decarboxylation and activation of Rubisco. The vacuolar storage and release of malic acid and the interplay between the supply and demand for carbohydrate reserves are also key metabolic control points.
FUTURE OPPORTUNITIES
We identify open questions and opportunities, with experimentation informed by top-down molecular modelling approaches allied with bottom-up mechanistic modelling systems. For example, mining transcriptomic datasets using high-speed systems approaches will help to identify targets for future genetic manipulation experiments to define the regulation of CAM (whether circadian or metabolic control). We emphasize that inferences arising from computational approaches or advanced nuclear sequencing techniques can identify potential genes and transcription factors as regulatory targets. However, these outputs then require systematic evaluation, using genetic manipulation in key model organisms over a developmental progression, combining gene silencing and metabolic flux analysis and modelling to define functionality across the CAM day-night cycle. From an evolutionary perspective, the origins and function of CAM succulents and responses to water deficits are set against the mesophyll and hydraulic limitations imposed by cell and tissue succulence in contrasting morphological lineages. We highlight the interplay between traits across shoots (3D vein density, mesophyll conductance and cell shrinkage) and roots (xylem embolism and segmentation). Thus, molecular, biophysical and biochemical processes help to curtail water losses and exploit rapid rehydration during restorative rain events. In the face of a changing climate, we hope such approaches will stimulate opportunities for future research.
Topics: Crassulacean Acid Metabolism; Photosynthesis; Phosphoenolpyruvate Carboxylase; Biological Evolution; Water
PubMed: 37742290
DOI: 10.1093/aob/mcad142 -
Experimental & Molecular Medicine Jul 2023Hepatic glucose production by glucagon is crucial for glucose homeostasis during fasting, yet the underlying mechanisms remain incompletely delineated. Although CD38 has...
Hepatic glucose production by glucagon is crucial for glucose homeostasis during fasting, yet the underlying mechanisms remain incompletely delineated. Although CD38 has been detected in the nucleus, its function in this compartment is unknown. Here, we demonstrate that nuclear CD38 (nCD38) controls glucagon-induced gluconeogenesis in primary hepatocytes and liver in a manner distinct from CD38 occurring in the cytoplasm and lysosomal compartments. We found that the localization of CD38 in the nucleus is required for glucose production by glucagon and that nCD38 activation requires NAD supplied by PKCδ-phosphorylated connexin 43. In fasting and diabetes, nCD38 promotes sustained Ca signals via transient receptor potential melastatin 2 (TRPM2) activation by ADP-ribose, which enhances the transcription of glucose-6 phosphatase and phosphoenolpyruvate carboxykinase 1. These findings shed light on the role of nCD38 in glucagon-induced gluconeogenesis and provide insight into nuclear Ca signals that mediate the transcription of key genes in gluconeogenesis under physiological conditions.
Topics: Humans; Gluconeogenesis; Glucagon; Adenosine Diphosphate Ribose; TRPM Cation Channels; Liver; Glucose; Hepatocytes; Fasting; Diabetes Mellitus
PubMed: 37394593
DOI: 10.1038/s12276-023-01034-9 -
USP4 promotes the proliferation and glucose metabolism of gastric cancer cells by upregulating PKM2.PloS One 2023The pyruvate kinase enzyme PKM2 catalyzes the final step in glycolysis and converts phosphoenolpyruvate (PEP) to pyruvate. PKM2 is often overexpressed in cancer and...
BACKGROUND
The pyruvate kinase enzyme PKM2 catalyzes the final step in glycolysis and converts phosphoenolpyruvate (PEP) to pyruvate. PKM2 is often overexpressed in cancer and plays a role in the Warburg effect. The expression of PKM2 can be regulated at different levels. While it has been proven that PKM2 can be regulated by ubiquitination, little is known about its de-ubiquitination regulation.
METHODS
Immunoprecipitation was applied to identify the PKM2 interaction protein and to determine the interaction region between PKM2 and USP4. Immunofluorescence was performed to determine the cellular localization of USP4 and PKM2. The regulation of PKM2 by USP4 was examined by western blot and ubiquitination assay. MTT assays, glucose uptake, and lactate production were performed to analyze the biological effects of USP4 in gastric cancer cells.
RESULTS
USP4 interacts with PKM2 and catalyzes the de-ubiquitination of PKM2. Overexpression of USP4 promotes cell proliferation, glucose uptake, and lactate production in gastric cancer cells. Knockdown of USP4 reduces PKM2 levels and results in a reduction in cell proliferation and the glycolysis rate.
CONCLUSIONS
USP4 plays a tumor-promoting role in gastric cancer cells by regulating PKM2.
Topics: Humans; Stomach Neoplasms; Cell Proliferation; Lactic Acid; Glucose; Ubiquitin-Specific Proteases
PubMed: 37624791
DOI: 10.1371/journal.pone.0290688