bims-mepmim 2024-12-08 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2024–12–08
nineteen papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

An acute microglial metabolic response controls metabolism and improves memory.
Dietary fructose enhances tumour growth indirectly via interorgan lipid transfer.
Mitochondrial respiratory supercomplexes gear up for heat generation in brown adipose tissue.
Metabolic imaging distinguishes ovarian cancer subtypes and detects their early and variable responses to treatment.
Tracking fructose 1,6-bisphosphate dynamics in liver cancer cells using a fluorescent biosensor.
β-hydroxybutyrate is a metabolic regulator of proteostasis in the aged and Alzheimer disease brain.
Glutamine is critical for the maintenance of type 1 conventional dendritic cells in normal tissue and the tumor microenvironment.
A helminth enzyme subverts macrophage-mediated immunity by epigenetic targeting of prostaglandin synthesis.
Mitochondrial calcium uniporter complex controls T-cell-mediated immune responses.
Tumor-Associated Microglia Secrete Extracellular ATP to Support Glioblastoma Progression.
RANK drives structured intestinal epithelial expansion during pregnancy.
Regulation of ROS signaling by TIGAR induces cancer-modulating responses in the tumor microenvironment.
Inhibition of LDHB suppresses the metastatic potential of lung cancer by reducing mitochondrial GSH catabolism.
Skeletal muscle mitochondrial fragmentation predicts age-associated decline in physical capacity.
OPA1 and disease-causing mutants perturb mitochondrial nucleoid distribution.
Cell polarity proteins promote macropinocytosis in response to metabolic stress.
Human airway macrophages are metabolically reprogrammed by IFN-γ resulting in glycolysis-dependent functional plasticity.
YAP1 induces bladder cancer progression and promotes immune evasion through IL-6/ STAT3 pathway and CXCL deregulation.
Inhibition of furin in CAR macrophages directs them toward a proinflammatory phenotype and enhances their antitumor activities.

Elife. 2024 Dec 03. pii: RP87120. [Epub ahead of print]12

An acute microglial metabolic response controls metabolism and improves memory.

Anne Drougard, Eric H Ma, Vanessa Wegert, Ryan Sheldon, Ilaria Panzeri, Naman Vatsa, Stefanos Apostle, Luca Fagnocchi, Judith Schaf, Klaus Gossens, Josephine Völker, Shengru Pang, Anna Bremser, Erez Dror, Francesca Giacona, Sagar Sagar, Michael X Henderson, Marco Prinz, Russell G Jones, John Andrew Pospisilik.

  Chronic high-fat feeding triggers metabolic dysfunction including obesity, insulin resistance, and diabetes. How high-fat intake first triggers these pathophysiological states remains unknown. Here, we identify an acute microglial metabolic response that rapidly translates intake of high-fat diet (HFD) to a surprisingly beneficial effect on metabolism and spatial/learning memory. High-fat intake rapidly increases palmitate levels in cerebrospinal fluid and triggers a wave of microglial metabolic activation characterized by mitochondrial membrane activation and fission as well as metabolic skewing toward aerobic glycolysis. These effects are detectable throughout the brain and can be detected within as little as 12 hr of HFD exposure. In vivo, microglial ablation and conditional DRP1 deletion show that the microglial metabolic response is necessary for the acute effects of HFD. 13C-tracing experiments reveal that in addition to processing via β-oxidation, microglia shunt a substantial fraction of palmitate toward anaplerosis and re-release of bioenergetic carbons into the extracellular milieu in the form of lactate, glutamate, succinate, and intriguingly, the neuroprotective metabolite itaconate. Together, these data identify microglia as a critical nutrient regulatory node in the brain, metabolizing away harmful fatty acids and liberating the same carbons as alternate bioenergetic and protective substrates for surrounding cells. The data identify a surprisingly beneficial effect of short-term HFD on learning and memory.

Keywords:  cell biology; diabetes; inflammation; memory; metabolism; microglia; mitochondria; mouse; neuroscience

DOI:  https://doi.org/10.7554/eLife.87120
Nature. 2024 Dec 04.

Dietary fructose enhances tumour growth indirectly via interorgan lipid transfer.

Ronald Fowle-Grider, Joe L Rowles, Isabel Shen, Yahui Wang, Michaela Schwaiger-Haber, Alden J Dunham, Kay Jayachandran, Matthew Inkman, Michael Zahner, Fuad J Naser, Madelyn M Jackstadt, Jonathan L Spalding, Sarah Chiang, Kyle S McCommis, Roland E Dolle, Eva T Kramer, Sarah M Zimmerman, George P Souroullas, Brian N Finck, Leah P Shriver, Charles K Kaufman, Julie K Schwarz, Jin Zhang, Gary J Patti.

Fructose consumption has increased considerably over the past five decades, largely due to the widespread use of high-fructose corn syrup as a sweetener1. It has been proposed that fructose promotes the growth of some tumours directly by serving as a fuel2,3. Here we show that fructose supplementation enhances tumour growth in animal models of melanoma, breast cancer and cervical cancer without causing weight gain or insulin resistance. The cancer cells themselves were unable to use fructose readily as a nutrient because they did not express ketohexokinase-C (KHK-C). Primary hepatocytes did express KHK-C, resulting in fructolysis and the excretion of a variety of lipid species, including lysophosphatidylcholines (LPCs). In co-culture experiments, hepatocyte-derived LPCs were consumed by cancer cells and used to generate phosphatidylcholines, the major phospholipid of cell membranes. In vivo, supplementation with high-fructose corn syrup increased several LPC species by more than sevenfold in the serum. Administration of LPCs to mice was sufficient to increase tumour growth. Pharmacological inhibition of ketohexokinase had no direct effect on cancer cells, but it decreased circulating LPC levels and prevented fructose-mediated tumour growth in vivo. These findings reveal that fructose supplementation increases circulating nutrients such as LPCs, which can enhance tumour growth through a cell non-autonomous mechanism.

DOI: https://doi.org/10.1038/s41586-024-08258-3
Cell Metab. 2024 Dec 03. pii: S1550-4131(24)00418-2. [Epub ahead of print]36(12): 2491-2492

Mitochondrial respiratory supercomplexes gear up for heat generation in brown adipose tissue.

Andreas Carlström, Martin Ott.

Mitochondrial energy conversion supplies cellular energy but can also provide heat in brown adipose tissue (BAT). In a recent study, Shin and Latorre-Muro et al.1 show that respiratory supercomplexes in BAT are remodeled during cold to provide a tighter coupling, revealing a novel, physiologically important role for these supramolecular assemblies.

DOI: https://doi.org/10.1016/j.cmet.2024.10.022
Oncogene. 2024 Dec 06.

Metabolic imaging distinguishes ovarian cancer subtypes and detects their early and variable responses to treatment.

Ming Li Chia, Flaviu Bulat, Adam Gaunt, Susana Ros, Alan J Wright, Ashley Sawle, Luca Porcu, Maria Vias, James D Brenton, Kevin M Brindle.

High grade serous ovarian cancer displays two metabolic subtypes; a high OXPHOS subtype that shows increased expression of genes encoding electron transport chain components, increased oxygen consumption, and increased chemosensitivity, and a low OXPHOS subtype that exhibits glycolytic metabolism and is more drug resistant. We show here in patient-derived organoids and in the xenografts obtained by their subcutaneous implantation that the low OXPHOS subtype shows higher lactate dehydrogenase activity and monocarboxylate transporter 4 expression than the high OXPHOS subtype and increased lactate labeling in 13C magnetic resonance spectroscopy (MRS) measurements of hyperpolarized [1-13C]pyruvate metabolism. There was no difference between the subtypes in PET measurements of 2-deoxy-2-[fluorine-18]fluoro-D-glucose ([18F]FDG) uptake. Both metabolic imaging techniques could detect the early response to Carboplatin treatment in drug-sensitive high OXPHOS xenografts and no response in drug-resistant in low OXPHOS xenografts. 13C magnetic resonance spectroscopic imaging of hyperpolarized [1-13C]pyruvate metabolism has the potential to be used clinically to distinguish low OXPHOS and high OXPHOS tumor deposits in HGSOC patients and to detect their differential responses to treatment.

DOI: https://doi.org/10.1038/s41388-024-03231-w
iScience. 2024 Dec 20. 27(12): 111336

Tracking fructose 1,6-bisphosphate dynamics in liver cancer cells using a fluorescent biosensor.

Israel Pérez-Chávez, John N Koberstein, Julia Malo Pueyo, Eduardo H Gilglioni, Didier Vertommen, Nicolas Baeyens, Daria Ezeriņa, Esteban N Gurzov, Joris Messens.

  HYlight is a genetically encoded fluorescent biosensor that ratiometrically monitors fructose 1,6-bisphosphate (FBP), a key glycolytic metabolite. Given the role of glucose in liver cancer metabolism, we expressed HYlight in human liver cancer cells and primary mouse hepatocytes. Through in vitro, in silico, and in cellulo experiments, we showed HYlight's ability to monitor FBP changes linked to glycolysis, not gluconeogenesis. HYlight's affinity for FBP was ∼1 μM and stable within physiological pH range. HYlight demonstrated weak binding to dihydroxyacetone phosphate, and its ratiometric response was influenced by both ionic strength and phosphate. Therefore, simulating cytosolic conditions in vitro was necessary to establish a reliable correlation between HYlight's cellular responses and FBP concentrations. FBP concentrations were found to be in the lower micromolar range, far lower than previous millimolar estimates. Altogether, this biosensor approach offers real-time monitoring of FBP concentrations at single-cell resolution, making it an invaluable tool for the understanding of cancer metabolism.

Keywords:  biochemistry methods; cancer; metabolomics

DOI:  https://doi.org/10.1016/j.isci.2024.111336
Cell Chem Biol. 2024 Nov 25. pii: S2451-9456(24)00459-8. [Epub ahead of print]

β-hydroxybutyrate is a metabolic regulator of proteostasis in the aged and Alzheimer disease brain.

Sidharth S Madhavan, Stephanie Roa Diaz, Sawyer Peralta, Mitsunori Nomura, Christina D King, Kaya E Ceyhan, Anwen Lin, Dipa Bhaumik, Anna C Foulger, Samah Shah, Thanh Blade, Wyatt Gray, Manish Chamoli, Brenda Eap, Oishika Panda, Diego Diaz, Thelma Y Garcia, Brianna J Stubbs, Scott M Ulrich, Gordon J Lithgow, Birgit Schilling, Eric Verdin, Asish R Chaudhuri, John C Newman.

  Loss of proteostasis is a hallmark of aging and Alzheimer disease (AD). We identify β-hydroxybutyrate (βHB), a ketone body, as a regulator of protein solubility. βHB primarily provides ATP substrate during periods of reduced glucose availability, and regulates other cellular processes through protein interactions. We demonstrate βHB-induced protein insolubility is not dependent on covalent protein modification, pH, or solute load, and is observable in mouse brain in vivo after delivery of a ketone ester. This mechanism is selective for pathological proteins such as amyloid-β, and exogenous βHB ameliorates pathology in nematode models of amyloid-β aggregation toxicity. We generate libraries of the βHB-induced protein insolublome using mass spectrometry proteomics, and identify common protein domains and upstream regulators. We show enrichment of neurodegeneration-related proteins among βHB targets and the clearance of these targets from mouse brain. These data indicate a metabolically regulated mechanism of proteostasis relevant to aging and AD.

Keywords:  Alzheimer disease; aging; ketone body; neurodegenerative disease; proteostasis

DOI:  https://doi.org/10.1016/j.chembiol.2024.11.001
Proc Natl Acad Sci U S A. 2024 Dec 10. 121(50): e2412157121

Glutamine is critical for the maintenance of type 1 conventional dendritic cells in normal tissue and the tumor microenvironment.

Graham P Lobel, Nanumi Han, William A Molina Arocho, Michal Silber, Jason Shoush, Michael C Noji, Tsun Ki Jerrick To, Li Zhai, Nicholas P Lesner, M Celeste Simon, Malay Haldar.

  Proliferating tumor cells take up glutamine for anabolic processes, engendering glutamine deficiency in the tumor microenvironment. How this might impact immune cells is not well understood. Using multiple mouse models of soft tissue sarcomas, glutamine antagonists, as well as genetic and pharmacological inhibition of glutamine utilization, we found that the number and frequency of conventional dendritic cells (cDCs) is dependent on microenvironmental glutamine levels. cDCs comprise two distinct subsets-cDC1s and cDC2s, with the former subset playing a critical role in antigen cross-presentation and tumor immunity. While both subsets show dependence on glutamine, cDC1s are particularly sensitive. Notably, glutamine antagonism did not reduce the frequency of DC precursors but decreased the proliferation and survival of cDC1s. Further studies suggest a role of the nutrient sensing mechanistic target of rapamycin (mTOR) signaling pathway in this process. Taken together, these findings uncover glutamine dependence of cDC1s that is coopted by tumors to escape immune responses.

Keywords:  dendritic cells; glutamine; tumor microenvironment

DOI:  https://doi.org/10.1073/pnas.2412157121
Sci Immunol. 2024 Dec 06. 9(102): eadl1467

A helminth enzyme subverts macrophage-mediated immunity by epigenetic targeting of prostaglandin synthesis.

Sina Bohnacker, Fiona D R Henkel, Franziska Hartung, Arie Geerlof, Sandra Riemer, Ulrich F Prodjinotho, Eya Ben Salah, André Santos Dias Mourão, Stefan Bohn, Tarvi Teder, Dominique Thomas, Robert Gurke, Christiane Boeckel, Minhaz Ud-Dean, Ann-Christine König, Alessandro Quaranta, Francesca Alessandrini, Antonie Lechner, Benedikt Spitzlberger, Agnieszka M Kabat, Edward Pearce, Jesper Z Haeggström, Stefanie M Hauck, Craig E Wheelock, Per-Johan Jakobsson, Michael Sattler, David Voehringer, Matthias J Feige, Clarissa Prazeres da Costa, Julia Esser-von Bieren.

The molecular mechanisms by which worm parasites evade host immunity are incompletely understood. In a mouse model of intestinal helminth infection using Heligmosomoides polygyrus bakeri (Hpb), we show that helminthic glutamate dehydrogenase (heGDH) drives parasite chronicity by suppressing macrophage-mediated host defense. Combining RNA-seq, ChIP-seq, and targeted lipidomics, we identify prostaglandin E2 (PGE2) as a major immune regulatory mechanism of heGDH. The induction of PGE2 and other immunoregulatory factors, including IL-12 family cytokines and indoleamine 2,3-dioxygenase 1, by heGDH required p300-mediated histone acetylation, whereas the enzyme's catalytic activity suppressed the synthesis of type 2-promoting leukotrienes by macrophages via 2-hydroxyglutarate. By contrast, the induction of immunoregulatory factors involved the heGDH N terminus by potentially mediating interactions with cellular targets (CD64 and GPNMB) identified by proteomics. Type 2 cytokines counteracted suppressive effects of heGDH on host defense, indicating that type 2 immunity can limit helminth-driven immune evasion. Thus, helminths harness a ubiquitous metabolic enzyme to epigenetically target type 2 macrophage activation and establish chronicity.

DOI: https://doi.org/10.1126/sciimmunol.adl1467
EMBO Rep. 2024 Dec 02.

Mitochondrial calcium uniporter complex controls T-cell-mediated immune responses.

Magdalena Shumanska, Dmitri Lodygin, Christine S Gibhardt, Christian Ickes, Ioana Stejerean-Todoran, Lena C M Krause, Kira Pahl, Lianne J H C Jacobs, Andrea Paluschkiwitz, Shuya Liu, Angela Boshnakovska, Niels Voigt, Tobias J Legler, Martin Haubrock, Miso Mitkovski, Gereon Poschmann, Peter Rehling, Sven Dennerlein, Jan Riemer, Alexander Flügel, Ivan Bogeski.

  T-cell receptor (TCR)-induced Ca2+ signals are essential for T-cell activation and function. In this context, mitochondria play an important role and take up Ca2+ to support elevated bioenergetic demands. However, the functional relevance of the mitochondrial-Ca2+-uniporter (MCU) complex in T-cells was not fully understood. Here, we demonstrate that TCR activation causes rapid mitochondrial Ca2+ (mCa2+) uptake in primary naive and effector human CD4+ T-cells. Compared to naive T-cells, effector T-cells display elevated mCa2+ and increased bioenergetic and metabolic output. Transcriptome and proteome analyses reveal molecular determinants involved in the TCR-induced functional reprogramming and identify signalling pathways and cellular functions regulated by MCU. Knockdown of MCUa (MCUaKD), diminishes mCa2+ uptake, mitochondrial respiration and ATP production, as well as T-cell migration and cytokine secretion. Moreover, MCUaKD in rat CD4+ T-cells suppresses autoimmune responses in an experimental autoimmune encephalomyelitis (EAE) multiple sclerosis model. In summary, we demonstrate that mCa2+ uptake through MCU is essential for proper T-cell function and has a crucial role in autoimmunity. T-cell specific MCU inhibition is thus a potential tool for targeting autoimmune disorders.

Keywords:  Autoimmunity; Calcium; MCU; Mitochondria; T-cell

DOI:  https://doi.org/10.1038/s44319-024-00313-4
Cancer Res. 2024 Dec 02. 84(23): 4017-4030

Tumor-Associated Microglia Secrete Extracellular ATP to Support Glioblastoma Progression.

Caren Yu-Ju Wu, Yiyun Chen, Ya-Jui Lin, Kuo-Chen Wei, Kwang-Yu Chang, Li-Ying Feng, Ko-Ting Chen, Gordon Li, Alexander Liang Ren, Ryan Takeo Nitta, Janet Yuling Wu, Kwang Bog Cho, Ayush Pant, John Choi, Crystal L Mackall, Lily H Kim, An-Chih Wu, Jian-Ying Chuang, Chiung-Yin Huang, Christopher M Jackson, Pin-Yuan Chen, Michael Lim.

Glioblastoma (GBM) is a highly aggressive brain tumor with poor prognosis and high recurrence rates. The complex immune microenvironment of GBM is highly infiltrated by tumor-associated microglia and macrophages (TAM). TAMs are known to be heterogeneous in their functional and metabolic states and can transmit either protumoral or antitumoral signals to glioma cells. Here, we performed bulk RNA sequencing and single-cell RNA sequencing on samples from patients with GBM, which revealed increased ATP synthase expression and oxidative phosphorylation activity in TAMs located in the tumor core relative to the tumor periphery. Both in vitro and in vivo models displayed similar trends of augmented TAM mitochondrial activity, along with elevated mitochondrial fission, glucose uptake, mitochondrial membrane potential, and extracellular ATP (eATP) production by TAMs in the presence of GBM cells. Tumor-secreted factors, including GM-CSF, induced the increase in TAM eATP production. Elevated eATP in the GBM microenvironment promoted glioma growth and invasion by activating the P2X purinoceptor 7 (P2X7R) on glioma cells. Inhibition of the eATP-P2X7R axis attenuated tumor cell viability in vitro and reduced tumor size and prolonged survival in glioma-bearing mouse models. Overall, this study revealed elevated TAM-derived eATP in GBM and provided the basis for targeting the eATP-P2X7R signaling axis as a therapeutic strategy in GBM. Significance: Glioblastoma-mediated metabolic reprogramming in tumor-associated microglia increases ATP secretion that supports cancer cell proliferation and invasion by activating P2X7R, which can be inhibited to attenuate tumor growth.

DOI: https://doi.org/10.1158/0008-5472.CAN-24-0018
Nature. 2024 Dec 04.

RANK drives structured intestinal epithelial expansion during pregnancy.

Masahiro Onji, Verena Sigl, Thomas Lendl, Maria Novatchkova, Asier Ullate-Agote, Amanda Andersson-Rolf, Ivona Kozieradzki, Rubina Koglgruber, Tsung-Pin Pai, Dominic Lichtscheidl, Komal Nayak, Matthias Zilbauer, Natalia A Carranza García, Laura Katharina Sievers, Maren Falk-Paulsen, Shane J F Cronin, Astrid Hagelkruys, Shinichiro Sawa, Lisa C Osborne, Philip Rosenstiel, Manolis Pasparakis, Jürgen Ruland, Hiroshi Takayanagi, Hans Clevers, Bon-Kyoung Koo, Josef M Penninger.

During reproduction, multiple species such as insects and all mammals undergo extensive physiological and morphological adaptions to ensure health and survival of the mother and optimal development of the offspring. Here we report that the intestinal epithelium undergoes expansion during pregnancy and lactation in mammals. This enlargement of the intestinal surface area results in a novel geometry of expanded villi. Receptor activator of nuclear factor-κΒ (RANK, encoded by TNFRSF11A) and its ligand RANKL were identified as a molecular pathway involved in this villous expansion of the small intestine in vivo in mice and in intestinal mouse and human organoids. Mechanistically, RANK-RANKL protects gut epithelial cells from cell death and controls the intestinal stem cell niche through BMP receptor signalling, resulting in the elongation of villi and a prominent increase in the intestinal surface. As a transgenerational consequence, babies born to female mice that lack Rank in the intestinal epithelium show reduced weight and develop glucose intolerance after metabolic stress. Whereas gut epithelial remodelling in pregnancy/lactation is reversible, constitutive expression of an active form of RANK is sufficient to drive intestinal expansion followed by loss of villi and stem cells, and prevents the formation of Apcmin-driven small intestinal stem cell tumours. These data identify RANK-RANKL as a pathway that drives intestinal epithelial expansion in pregnancy/lactation, one of the most elusive and fundamental tissue remodelling events in mammalian life history and evolution.

DOI: https://doi.org/10.1038/s41586-024-08284-1
Proc Natl Acad Sci U S A. 2024 Dec 10. 121(50): e2416076121

Regulation of ROS signaling by TIGAR induces cancer-modulating responses in the tumor microenvironment.

Eric C Cheung, Douglas Strathdee, David Stevenson, Jack Coomes, Karen Blyth, Karen H Vousden.

  The consequences of reactive oxygen species (ROS) in cancer cells are complex and have been shown to both promote and retard tumorigenesis in different models. In mouse models of pancreatic ductal adenocarcinoma (PDAC), loss of the antioxidant defense gene Tigar results in both a reduction in the development of early pancreatic intraepithelial neoplasia and an increase in invasive and metastatic capacity, accompanied by decreased survival of mice lacking pancreatic TIGAR. We previously demonstrated that increased ROS following loss of TIGAR promotes various cancer cell-intrinsic changes that contribute to metastatic capacity, including epithelial to mesenchymal transition, enhanced migration and invasion, and an increase in ERK signaling. In this study, we show that pancreatic overexpression of TIGAR decreases metastatic capacity and migratory phenotypes in an aggressive model of PDAC, consistent with the concept that dynamic modulation of TIGAR in PDAC contributes to the development and progression of these tumors. Using TIGAR deficient and overexpressing mouse models, we find that the impact of modulation of TIGAR and ROS in PDAC cells also has a profound effect on the normal stromal cells surrounding the tumor. Loss of TIGAR promotes the production of cytokines by cancer cells that induce changes in the surrounding fibroblasts to adopt a tumor-supportive phenotype. Furthermore, these cytokines also attract macrophages that support PDAC dissemination and metastasis. Taken together our work shows that TIGAR-modulated ROS in PDAC can control cell intrinsic and extrinsic changes to impact tumor aggression.

Keywords:  oxidative stress; pancreatic cancer; tumor microenvironment

DOI:  https://doi.org/10.1073/pnas.2416076121
Cancer Lett. 2024 Nov 28. pii: S0304-3835(24)00748-1. [Epub ahead of print] 217353

Inhibition of LDHB suppresses the metastatic potential of lung cancer by reducing mitochondrial GSH catabolism.

Huixiang Ge, Fatlind Malsiu, Yanyun Gao, Tereza Losmanova, Fabian Blank, Julien Ott, Michaela Medová, Ren-Wang Peng, Haibin Deng, Patrick Dorn, Thomas Michael Marti.

  Metastasis, the leading cause of cancer death, is closely linked to lactate metabolism. Our study aimed to investigate the role of lactate dehydrogenase B (LDHB), which mainly catalyzes the conversion of lactate to pyruvate, in the metastatic potential of lung cancer. We found that LDHB silencing reduced the invasion and migration ability of lung cancer cells in vitro. On the molecular level, LDHB silencing decreased the total intracellular levels of the antioxidant glutathione (GSH). Surprisingly, LDHB silencing did not increase cellular or mitochondrial reactive oxygen species (ROS) levels. Furthermore, supplementation with GSH monoethyl ester (GSH-mee), a cell-permeable derivative of GSH, partially restored the reduced in vitro colony formation capacity, the oxygen consumption rate, and the invasion and migration capacity of lung cancer cells after LDHB silencing. Using metabolic inhibitors, we showed that the rescue of colony formation after silencing LDHB by GSH-mee was due to enhanced GSH catabolism by γ-L-Glutamyl transpeptidase (GGT), which was mainly present in the mitochondrial fraction of lung cancer cells. Furthermore, we observed that high GGT expression was a prerequisite for the rescue of migratory capacity by GSH-mee after LDHB silencing. Finally, our in vivo experiments demonstrated that targeting LDHB reduced the metastasis of human and mouse lung cancer cells in immunodeficient and immunocompetent mouse models, respectively. In conclusion, LDHB silencing decreases GSH catabolism mediated by GGT, which is primarily located in the mitochondria of cancer cells. Therefore, targeting LDHB is a promising therapeutic approach for the prevention and treatment of metastatic lung cancer.

Keywords:  glutathione; lactate dehydrogenase; lung cancer; metastasis; mitochondrial metabolism

DOI:  https://doi.org/10.1016/j.canlet.2024.217353
Aging Cell. 2024 Dec 04. e14386

Skeletal muscle mitochondrial fragmentation predicts age-associated decline in physical capacity.

Richie P Goulding, Braeden T Charlton, Ellen A Breedveld, Matthijs van der Laan, Anne R Strating, Wendy Noort, Aryna Kolodyazhna, Brent Appelman, Michèle van Vugt, Anita E Grootemaat, Nicole N van der Wel, Jos J de Koning, Frank W Bloemers, Rob C I Wüst.

  Ageing substantially impairs skeletal muscle metabolic and physical function. Skeletal muscle mitochondrial health is also impaired with ageing, but the role of skeletal muscle mitochondrial fragmentation in age-related functional decline remains imprecisely characterized. Here, using a cross-sectional study design, we performed a detailed comparison of skeletal muscle mitochondrial characteristics in relation to in vivo markers of exercise capacity between young and middle-aged individuals. Despite similar overall oxidative phosphorylation capacity (young: 99 ± 17 vs. middle-aged: 99 ± 27 pmol O2.s-1.mg-1, p = 0.95) and intermyofibrillar mitochondrial density (young: 5.86 ± 0.57 vs. middle-aged: 5.68 ± 1.48%, p = 0.25), older participants displayed a more fragmented intermyofibrillar mitochondrial network (young: 1.15 ± 0.17 vs. middle-aged: 1.55 ± 0.15 A.U., p < 0.0001), a lower mitochondrial cristae density (young: 23.40 ± 7.12 vs. middle-aged: 13.55 ± 4.10%, p = 0.002) and a reduced subsarcolemmal mitochondrial density (young: 22.39 ± 6.50 vs. middle-aged: 13.92 ± 4.95%, p = 0.005). Linear regression analysis showed that 87% of the variance associated with maximal oxygen uptake could be explained by skeletal muscle mitochondrial fragmentation and cristae density alone, whereas subsarcolemmal mitochondrial density was positively associated with the capacity for oxygen extraction during exercise. Intramuscular lipid accumulation was positively associated with mitochondrial fragmentation and negatively associated with cristae density. Collectively, our work highlights the critical role of skeletal muscle mitochondria in age-associated declines in physical function.

Keywords:  ageing; maximal oxygen uptake; mitochondrial morphology; mitochondrial respiration; skeletal muscle

DOI:  https://doi.org/10.1111/acel.14386
Cell Death Dis. 2024 Nov 30. 15(11): 870

OPA1 and disease-causing mutants perturb mitochondrial nucleoid distribution.

J Macuada, I Molina-Riquelme, G Vidal, N Pérez-Bravo, C Vásquez-Trincado, G Aedo, D Lagos, P Yu-Wai-Man, R Horvath, T J Rudge, B Cartes-Saavedra, V Eisner.

Optic atrophy protein 1 (OPA1) mediates inner mitochondrial membrane (IMM) fusion and cristae organization. Mutations in OPA1 cause autosomal dominant optic atrophy (ADOA), a leading cause of blindness. Cells from ADOA patients show impaired mitochondrial fusion, cristae structure, bioenergetic function, and mitochondrial DNA (mtDNA) integrity. The mtDNA encodes electron transport chain subunits and is packaged into nucleoids spread within the mitochondrial population. Nucleoids interact with the IMM, and their distribution is tightly linked to mitochondrial fusion and cristae shaping. Yet, little is known about the physio-pathological relevance of nucleoid distribution. We studied the effect of OPA1 and ADOA-associated mutants on nucleoid distribution using high-resolution confocal microscopy. We applied a novel model incorporating the mitochondrial context, separating nucleoid distribution into the array in the mitochondrial population and intramitochondrial longitudinal distribution. Opa1-null cells showed decreased mtDNA levels and nucleoid abundance. Also, loss of Opa1 led to an altered distribution of nucleoids in the mitochondrial population, loss of cristae periodicity, and altered nucleoids to cristae proximity partly rescued by OPA1 isoform 1. Overexpression of WT OPA1 or ADOA-causing mutants c.870+5 G > A or c.2713 C > T in WT cells, showed perturbed nucleoid array in the mitochondria population associated with cristae disorganization, which was partly reproduced in Skeletal muscle-derived fibroblasts from ADOA patients harboring the same mutants. Opa1-null and cells overexpressing ADOA mutants accumulated mitochondria without nucleoids. Interestingly, intramitochondrial nucleoid distribution was only altered in Opa1-null cells. Altogether, our results highlight the relevance of OPA1 in nucleoid distribution in the mitochondrial landscape and at a single-organelle level and shed light on new components of ADOA etiology.

DOI: https://doi.org/10.1038/s41419-024-07165-9
Nat Commun. 2024 Dec 03. 15(1): 10541

Cell polarity proteins promote macropinocytosis in response to metabolic stress.

Guillem Lambies, Szu-Wei Lee, Karen Duong-Polk, Pedro Aza-Blanc, Swetha Maganti, Cheska M Galapate, Anagha Deshpande, Aniruddha J Deshpande, David A Scott, David W Dawson, Cosimo Commisso.

Macropinocytosis has emerged as a scavenging pathway that cancer cells exploit to survive in a nutrient-deprived microenvironment. Tumor cells are especially reliant on glutamine for their survival, and in pancreatic ductal adenocarcinoma (PDAC) cells, glutamine deficiency can enhance the stimulation of macropinocytosis. Here, we identify the atypical protein kinase C (aPKC) enzymes, PKCζ and PKCι, as regulators of macropinocytosis. In normal epithelial cells, aPKCs associate with the scaffold proteins Par3 and Par6 to regulate cell polarity, affecting several targets, including the Par1 kinases and we find that each of these proteins is required for macropinocytosis. Mechanistically, aPKCs are regulated by EGFR signaling or by the transcription factor CREM to promote the Par3 relocation to microtubules, facilitating macropinocytosis in a dynein-dependent manner. Importantly, cell fitness impairment caused by aPKC depletion is rescued by the restoration of macropinocytosis and aPKCs support PDAC growth in vivo. Our findings enhance our understanding of the mechanistic underpinnings that control macropinocytic uptake in the context of metabolic stress.

DOI: https://doi.org/10.1038/s41467-024-54788-9
Elife. 2024 Dec 02. pii: RP98449. [Epub ahead of print]13

Human airway macrophages are metabolically reprogrammed by IFN-γ resulting in glycolysis-dependent functional plasticity.

Donal J Cox, Sarah A Connolly, Cilian Ó Maoldomhnaigh, Aenea A I Brugman, Olivia Sandby Thomas, Emily Duffin, Karl M Gogan, Oisin Ó Gallchobhair, Dearbhla M Murphy, Sinead A O'Rourke, Finbarr O'Connell, Parthiban Nadarajan, James J Phelan, Laura E Gleeson, Sharee A Basdeo, Joseph Keane.

  Airway macrophages (AM) are the predominant immune cell in the lung and play a crucial role in preventing infection, making them a target for host directed therapy. Macrophage effector functions are associated with cellular metabolism. A knowledge gap remains in understanding metabolic reprogramming and functional plasticity of distinct human macrophage subpopulations, especially in lung resident AM. We examined tissue-resident AM and monocyte-derived macrophages (MDM; as a model of blood derived macrophages) in their resting state and after priming with IFN-γ or IL-4 to model the Th1/Th2 axis in the lung. Human macrophages, regardless of origin, had a strong induction of glycolysis in response to IFN-γ or upon stimulation. IFN-γ significantly enhanced cellular energetics in both AM and MDM by upregulating both glycolysis and oxidative phosphorylation. Upon stimulation, AM do not decrease oxidative phosphorylation unlike MDM which shift to 'Warburg'-like metabolism. IFN-γ priming promoted cytokine secretion in AM. Blocking glycolysis with 2-deoxyglucose significantly reduced IFN-γ driven cytokine production in AM, indicating that IFN-γ induces functional plasticity in human AM, which is mechanistically mediated by glycolysis. Directly comparing responses between macrophages, AM were more responsive to IFN-γ priming and dependent on glycolysis for cytokine secretion than MDM. Interestingly, TNF production was under the control of glycolysis in AM and not in MDM. MDM exhibited glycolysis-dependent upregulation of HLA-DR and CD40, whereas IFN-γ upregulated HLA-DR and CD40 on AM independently of glycolysis. These data indicate that human AM are functionally plastic and respond to IFN-γ in a manner distinct from MDM. These data provide evidence that human AM are a tractable target for inhalable immunomodulatory therapies for respiratory diseases.

Keywords:  Mycobacterium tuberculosis; airway macrophages; cytokines; human; immunology; inflammation; lipopolysaccharide; metabolism; polarization

DOI:  https://doi.org/10.7554/eLife.98449
J Clin Invest. 2024 Nov 21. pii: e171164. [Epub ahead of print]

YAP1 induces bladder cancer progression and promotes immune evasion through IL-6/ STAT3 pathway and CXCL deregulation.

Pritam Sadhukhan, Mingxiao Feng, Emily J Illingworth, Ido Sloma, Akira Ooki, Andres Matoso, David Sidransky, Burles A Johnson Rd, Luigi Marchionni, Fenna Cm Sillé, Woonyoung Choi, David J McConkey, Mohammad Obaidul Hoque.

  The Hippo signaling pathway plays a key role in tumorigenesis in different cancer types. We investigated the role of the Hippo "effector" YAP1 on the tumor immune microenvironment (TIME) of urothelial carcinoma of bladder (UCB) and evaluated the efficacy of immunotherapy in the context of YAP1 signaling. We performed numerous in vitro and in vivo experiments to determine the role of YAP1 using genetic and pharmacological attenuation of YAP1 activity. Briefly, RNA sequencing was carried out with mice and human cell lines to identify novel YAP1-regulated downstream targets unbiasedly. We then experimentally confirmed that YAP1 regulates the TIME through the IL-6/STAT3 signaling pathway and varied C-X-C motif chemokine regulation. We analyzed several human sample sets to explore the TIME status in the context of YAP1 expression. Our data indicate that YAP1 attenuation decreases M2 macrophages and MDSCs in the TIME compared to YAP1 expressing cells. In summary, this study provides insights on YAP1 signaling as a driver for cancer stemness and an inducer of immunosuppressive TIME. Moreover, the therapeutic efficacy of YAP1 attenuation indicates that combined blockade of YAP1 and immune checkpoints may yield clinical value for treating UCB patients.

Keywords:  Cancer immunotherapy; Oncogenes; Oncology; Therapeutics; Tumor suppressors

DOI:  https://doi.org/10.1172/JCI171164
Cell Death Dis. 2024 Dec 04. 15(12): 879

Inhibition of furin in CAR macrophages directs them toward a proinflammatory phenotype and enhances their antitumor activities.

Lydia Ziane-Chaouche, Antonella Raffo-Romero, Nawale Hajjaji, Firas Kobeissy, Donna Pinheiro, Soulaimane Aboulouard, Adeline Cozzani, Suman Mitra, Isabelle Fournier, Dasa Cizkova, Michel Salzet, Marie Duhamel.

Chimeric antigen receptor (CAR)-T-cell therapy has revolutionized cellular immunotherapy, demonstrating remarkable efficacy in hematological cancers. However, its application in solid tumors faces significant challenges, including limited T-cell infiltration and tumor-induced immunosuppression. Given the prominent role of macrophages in the tumor microenvironment, their phenotypic plasticity and inherent antitumor properties, such as phagocytosis, offer a promising avenue for therapeutic intervention. This study focuses on the development of a second generation of CAR macrophages (CAR-Ms). We elucidated the role of the proprotein convertase furin in macrophages, demonstrating its overexpression in the presence of tumor cells. Importantly, furin inhibition maintains a proinflammatory macrophage phenotype, potentially redirecting them towards an antitumor state. Compared to furin-expressing counterparts, furin-inhibited CAR-Ms exhibited heightened antitumor phagocytic activity against breast cancer cells and ex vivo patient-derived tumoroids. Notably, they sustained a persistent proinflammatory profile, indicative of enhanced tumoricidal potential. Additionally, furin-inhibited CAR-Ms secreted factors that promote T-cell activation, offering a means to modulate the tumor microenvironment. In summary, our work highlights the translational potential of furin-inhibited CAR-Ms as a potent cellular therapy to mitigate macrophage exhaustion within the tumor environment. By capitalizing on macrophage-mediated antitumor responses, these findings pave the way for the development of second-generation CAR-M therapeutic strategies tailored for solid tumors.

DOI: https://doi.org/10.1038/s41419-024-07267-4