bims-mignad 2024-12-08 papers

Issue of 2024–12–08
four papers selected by
Melisa Emel Ermert, Amsterdam UMC

ASN Neuro. 2024 ;16(1): 2422268

Amino Acid and Glucose Fermentation Maintain ATP Content in Mouse and Human Malignant Glioma Cells.

Derek C Lee, Linh Ta, Purna Mukherjee, Tomas Duraj, Marek Domin, Bennett Greenwood, Srada Karmacharya, Niven R Narain, Michael Kiebish, Christos Chinopoulos, Thomas N Seyfried.

Energy is necessary for tumor cell viability and growth. Aerobic glucose-driven lactic acid fermentation is a common metabolic phenotype seen in most cancers including malignant gliomas. This metabolic phenotype is linked to abnormalities in mitochondrial structure and function. A luciferin-luciferase bioluminescence ATP assay was used to measure the influence of amino acids, glucose, and oxygen on ATP content and viability in mouse (VM-M3 and CT-2A) and human (U-87MG) glioma cells that differed in cell biology, genetic background, and species origin. Oxygen consumption was measured using the Resipher system. Extracellular lactate and succinate were measured as end products of the glycolysis and glutaminolysis pathways, respectively. The results showed that: (1) glutamine was a source of ATP content irrespective of oxygen. No other amino acid could replace glutamine in sustaining ATP content and viability; (2) ATP content persisted in the absence of glucose and under hypoxia, ruling out substantial contribution through either glycolysis or oxidative phosphorylation (OxPhos) under these conditions; (3) Mitochondrial complex IV inhibition showed that oxygen consumption was not an accurate measure for ATP production through OxPhos. The glutaminase inhibitor, 6-diazo-5-oxo-L-norleucine (DON), reduced ATP content and succinate export in cells grown in glutamine. The data suggests that mitochondrial substrate level phosphorylation in the glutamine-driven glutaminolysis pathway contributes to ATP content in these glioma cells. A new model is presented highlighting the synergistic interaction between the high-throughput glycolysis and glutaminolysis pathways that drive malignant glioma growth and maintain ATP content through the aerobic fermentation of both glucose and glutamine.

Keywords: Fermentation; glioblastoma; glutaminolysis; mitochondrial substrate level phosphorylation; succinate

DOI: https://doi.org/10.1080/17590914.2024.2422268

J Agric Food Chem. 2024 Dec 04.

Lactate Dehydrogenase Inhibition Protects against Hepatic Fibrosis by Regulating Metabolic Reprogramming of Hepatic Stellate Cells.

Lisi Li, Qi Lei, Yifan Zhen, Lixue Cao, Yujia Dong, Xifu Liu, Meng Wang.

Hepatic stellate cells (HSCs) activation results in liver fibrosis. When HSCs are activated, metabolism is reprogrammed. However, metabolic alteration in HSCs activation has not been sufficiently addressed. This study aims to investigate the role of lactate dehydrogenase (LDH) inhibition in HSCs activation with an emphasis on the metabolic reprogramming. Mice were subjected to carbon tetrachloride (CCl4) to induce liver injury. In addition, the primary HSCs were isolated for mechanism investigation. Our study demonstrated that LDH inhibition impaired HSCs activation through suppressing the enhanced glycolysis by blocking nicotinamide adenine dinucleotide (NAD+) regeneration. Meanwhile, LDH inhibition also impeded the glutamine metabolism through the lactic acid/histone deacetylase (HDAC)/histone acetylation/cellular-myelocytomatosis viral oncogene (c-Myc) signaling pathway. Our findings demonstrated that LDH inhibition is a potential target for liver fibrosis treatment, which provides new insight into the pathogenesis of liver fibrosis from the aspect of metabolic reprogramming, contributing to the design of a novel therapeutic strategy in the management of liver fibrosis.

Keywords: glutaminolysis; glycolysis; hepatic fibrosis; hepatic stellate cells; lactate dehydrogenase

DOI: https://doi.org/10.1021/acs.jafc.4c08211

Zhongguo Fei Ai Za Zhi. 2024 Oct 20. 27(10): 785-791

[Role of Mitochondria in Ferroptosis and Its Relationship to Tumors].

Zhanrui Zhang, Hongyu Liu, Jun Chen.

Ferroptosis is a recently discovered form of cell death that is distinct from apoptosis, characterized primarily by the accumulation of intracellular iron and increased levels of lipid peroxidation. Resistance of tumor cells to ferroptosis can promote tumorigenesis and tumor progression. Various compounds can influence tumor development by triggering ferroptosis. Ferroptosis involves complex regulatory mechanisms, with mitochondria serving as both an iron storage and metabolic center, playing a crucial regulatory role in ferroptosis. This review discusses ferroptosis and its three stages and the role of ferroptosis in tumorigenesis, progression, and treatment, as well as the regulatory mechanisms of mitochondria in ferroptosis. .

Keywords: Ferroptosis; GPX4; Lipid peroxidation; Mitochondria

DOI: https://doi.org/10.3779/j.issn.1009-3419.2024.102.34

PLoS One. 2024 ;19(12): e0309886

Measuring the rate of NADPH consumption by glutathione reductase in the cytosol and mitochondria.

Kenneth K Y Ting, Eric Floro, Riley Dow, Jenny Jongstra-Bilen, Myron I Cybulsky, Jonathan V Rocheleau.

BACKGROUND: NADPH is an essential co-factor supporting the function of enzymes that participate in both inflammatory and anti-inflammatory pathways in myeloid cells, particularly macrophages. Although individual NADPH-dependent pathways are well characterized, how these opposing pathways are co-regulated to orchestrate an optimized inflammatory response is not well understood. To investigate this, techniques to track the consumption of NADPH need to be applied. Deuterium tracing of NADPH remains the gold standard in the field, yet this setup of mass-spectrometry is technically challenging and not readily available to most research groups. Furthermore, NADPH pools are compartmentalized in various organelles with no known membrane transporters, suggesting that NADPH-dependent pathways are regulated in an organelle-specific manner. Conventional methods such as commercial kits are limited to quantifying NADPH in whole cells and not at the resolution of specific organelles. These limitations reflect the need for a novel assay that can readily measure the consumption rate of NADPH in different organelles.
METHODS: We devised an assay that measures the consumption rate of NADPH by glutathione-disulfide reductase (GSR) in the mitochondria and the cytosol of RAW264.7 macrophage cell lines. RAW264.7 cells were transfected with Apollo-NADP+ sensors targeted to the mitochondria or the cytosol, followed by the treatment of 2-deoxyglucose and diamide. Intravital imaging over time then determined GSR-dependent NADPH consumption in an organelle-specific manner.
DISCUSSION: In lipopolysaccharide (LPS)-stimulated RAW264.7 cells, cytosolic and mitochondrial NADPH was consumed by GSR in a time-dependent manner. This finding was cross validated with a commercially available NADPH kit that detects NADPH in whole cells. Loading of RAW264.7 cells with oxidized low-density lipoprotein followed by LPS stimulation elevated GSR expression, and this correlated with a more rapid drop in cytosolic and mitochondrial NADPH in our assay. The current limitation of our assay is applicability to transfectable cell lines, and higher expression of plasmid-encoded sensors relative to endogenous glucose-6-phosphate dehydrogenase.

DOI: https://doi.org/10.1371/journal.pone.0309886