bims-mepmim 2023-10-29 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2023–10–29
34 papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency.
Blocking AMPKαS496 phosphorylation improves mitochondrial dynamics and hyperglycemia in aging and obesity.
Lipocalin 2 regulates mitochondrial phospholipidome remodeling, dynamics, and function in brown adipose tissue in male mice.
The glucose transporter 2 regulates CD8+ T cell function via environment sensing.
Nutrient-regulated control of lysosome function by signaling lipid conversion.
Loss of Muscle PDH Induces Lactic Acidosis and Adaptive Anaplerotic Compensation via Pyruvate-Alanine Cycling and Glutaminolysis.
Methionine-CBS axis promotes intracellular ROS levels by reprogramming serine metabolism.
A fingerprint of 2-[18F]FDG radiometabolites - How tissue-specific metabolism beyond 2-[18F]FDG-6-P could affect tracer accumulation.
Organoids transplantation attenuates intestinal ischemia/reperfusion injury in mice through L-Malic acid-mediated M2 macrophage polarization.
Visualization of accessible cholesterol using a GRAM domain-based biosensor.
Systematic P2Y receptor survey identifies P2Y11 as modulator of immune responses and virus replication in macrophages.
Immune synapse formation promotes lipid peroxidation and MHC-I upregulation in licensed dendritic cells for efficient priming of CD8+ T cells.
Cardiomyocyte NOX4 regulates resident macrophage-mediated inflammation and diastolic dysfunction in stress cardiomyopathy.
Developing synthetic tools to decipher the tumor-immune interactome.
Brown adipose tissue-derived metabolites and their role in regulating metabolism.
Tld1 is a regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation.
The mitochondrial fusion protein OPA1 is dispensable in the liver and its absence induces mitohormesis to protect liver from drug-induced injury.
The total mass, number, and distribution of immune cells in the human body.
Manganese regulation of COPII condensation controls circulating lipid homeostasis.
Macrophage and T cell networks in adipose tissue.
MCT4 blockade increases the efficacy of immune checkpoint blockade.
AMPKα1 negatively regulates osteoclastogenesis and mitigate pathological bone loss.
Circadian dysfunction induces NAFLD-related human liver cancer in a mouse model.
Lactate activates the mitochondrial electron transport chain independently of its metabolism.
A Guide to MALDI Imaging Mass Spectrometry for Tissues.
An innate granuloma eradicates an environmental pathogen using Gsdmd and Nos2.
A genetic basis of mitochondrial DNAJA3 in nonalcoholic steatohepatitis-related hepatocellular carcinoma.
Environmental stiffness restores mechanical homeostasis in vimentin-depleted cells.
Human MCTS1-dependent translation of JAK2 is essential for IFN-γ immunity to mycobacteria.
The liver microenvironment orchestrates FGL1-mediated immune escape and progression of metastatic colorectal cancer.
Loss of UCP2 causes mitochondrial fragmentation by OMA1-dependent proteolytic processing of OPA1 in podocytes.
Mitochondrial gene expression is required for platelet function and blood clotting.
A critical role for staphylococcal nitric oxide synthase in controlling flavohemoglobin toxicity.
Formyl-peptide receptor 2 signalling triggers aerobic metabolism of glucose through Nox2-dependent modulation of pyruvate dehydrogenase activity.

Redox Biol. 2023 Oct 17. pii: S2213-2317(23)00333-6. [Epub ahead of print]67 102932

Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency.

Gerardo G Piroli, Allison M Manuel, Richard S McCain, Holland H Smith, Oliver Ozohanics, Sara Mellid, J Hunter Cox, William E Cotham, Michael D Walla, Alberto Cascón, Attila Ambrus, Norma Frizzell.

  The NDUFS4 knockout (KO) mouse phenotype resembles the human Complex I deficiency Leigh Syndrome. The irreversible succination of protein thiols by fumarate is increased in select regions of the NDUFS4 KO brain affected by neurodegeneration. We report that dihydrolipoyllysine-residue succinyltransferase (DLST), a component of the α-ketoglutarate dehydrogenase complex (KGDHC) of the tricarboxylic acid (TCA) cycle, is succinated in the affected regions of the NDUFS4 KO brain. Succination of DLST reduced KGDHC activity in the brainstem (BS) and olfactory bulb (OB) of KO mice. The defective production of KGDHC derived succinyl-CoA resulted in decreased mitochondrial substrate level phosphorylation (SLP), further aggravating the existing oxidative phosphorylation (OXPHOS) ATP deficit. Protein succinylation, an acylation modification that requires succinyl-CoA, was reduced in the KO mice. Modeling succination of a cysteine in the spatial vicinity of the DLST active site or introduction of succinomimetic mutations recapitulates these metabolic deficits. Our data demonstrate that the biochemical deficit extends beyond impaired Complex I assembly and OXPHOS deficiency, functionally impairing select components of the TCA cycle to drive metabolic perturbations in affected neurons.

Keywords:  Alpha-ketoglutarate dehydrogenase; Complex I; Fumarate; Leigh syndrome; Protein succination; Substrate level phosphorylation

DOI:  https://doi.org/10.1016/j.redox.2023.102932
Cell Chem Biol. 2023 Oct 26. pii: S2451-9456(23)00336-7. [Epub ahead of print]

Blocking AMPKαS496 phosphorylation improves mitochondrial dynamics and hyperglycemia in aging and obesity.

Alexia Pearah, Balamurugan Ramatchandirin, Ting Liu, Risa M Wolf, Arisa Ikeda, Sally Radovick, Hiromi Sesaki, Fredric E Wondisford, Brian O'Rourke, Ling He.

  Impaired mitochondrial dynamics causes aging-related or metabolic diseases. Yet, the molecular mechanism responsible for the impairment of mitochondrial dynamics is still not well understood. Here, we report that elevated blood insulin and/or glucagon levels downregulate mitochondrial fission through directly phosphorylating AMPKα at S496 by AKT or PKA, resulting in the impairment of AMPK-MFF-DRP1 signaling and mitochondrial dynamics and activity. Since there are significantly increased AMPKα1 phosphorylation at S496 in the liver of elderly mice, obese mice, and obese patients, we, therefore, designed AMPK-specific targeting peptides (Pa496m and Pa496h) to block AMPKα1S496 phosphorylation and found that these targeting peptides can increase AMPK kinase activity, augment mitochondrial fission and oxidation, and reduce ROS, leading to the rejuvenation of mitochondria. Furthermore, these AMPK targeting peptides robustly suppress liver glucose production in obese mice. Our data suggest these targeting peptides are promising therapeutic agents for improving mitochondrial dynamics and activity and alleviating hyperglycemia in elderly and obese patients.

Keywords:  AKT; AMPK targeting peptides; AMPKαS496 phosphorylation; PKA; hyperglycemia; liver gluconeogenesis; mitochondrial fission

DOI:  https://doi.org/10.1016/j.chembiol.2023.09.017
Nat Commun. 2023 Oct 23. 14(1): 6729

Lipocalin 2 regulates mitochondrial phospholipidome remodeling, dynamics, and function in brown adipose tissue in male mice.

Hongming Su, Hong Guo, Xiaoxue Qiu, Te-Yueh Lin, Chao Qin, Gail Celio, Peter Yong, Mark Senders, Xianlin Han, David A Bernlohr, Xiaoli Chen.

Mitochondrial function is vital for energy metabolism in thermogenic adipocytes. Impaired mitochondrial bioenergetics in brown adipocytes are linked to disrupted thermogenesis and energy balance in obesity and aging. Phospholipid cardiolipin (CL) and phosphatidic acid (PA) jointly regulate mitochondrial membrane architecture and dynamics, with mitochondria-associated endoplasmic reticulum membranes (MAMs) serving as the platform for phospholipid biosynthesis and metabolism. However, little is known about the regulators of MAM phospholipid metabolism and their connection to mitochondrial function. We discover that LCN2 is a PA binding protein recruited to the MAM during inflammation and metabolic stimulation. Lcn2 deficiency disrupts mitochondrial fusion-fission balance and alters the acyl-chain composition of mitochondrial phospholipids in brown adipose tissue (BAT) of male mice. Lcn2 KO male mice exhibit an increase in the levels of CLs containing long-chain polyunsaturated fatty acids (LC-PUFA), a decrease in CLs containing monounsaturated fatty acids, resulting in mitochondrial dysfunction. This dysfunction triggers compensatory activation of peroxisomal function and the biosynthesis of LC-PUFA-containing plasmalogens in BAT. Additionally, Lcn2 deficiency alters PA production, correlating with changes in PA-regulated phospholipid-metabolizing enzymes and the mTOR signaling pathway. In conclusion, LCN2 plays a critical role in the acyl-chain remodeling of phospholipids and mitochondrial bioenergetics by regulating PA production and its function in activating signaling pathways.

DOI: https://doi.org/10.1038/s41467-023-42473-2
Nat Metab. 2023 Oct 26.

The glucose transporter 2 regulates CD8+ T cell function via environment sensing.

Hongmei Fu, Juho Vuononvirta, Silvia Fanti, Fabrizia Bonacina, Antonio D'Amati, Guosu Wang, Thanushiyan Poobalasingam, Maria Fankhaenel, Davide Lucchesi, Rachel Coleby, David Tarussio, Bernard Thorens, Robert J Hearnden, M Paula Longhi, Paul Grevitt, Madeeha H Sheikh, Egle Solito, Susana A Godinho, Michele Bombardieri, David M Smith, Dianne Cooper, Asif J Iqbal, Jeffrey C Rathmell, Samuel Schaefer, Valle Morales, Katiuscia Bianchi, Giuseppe Danilo Norata, Federica M Marelli-Berg.

T cell activation is associated with a profound and rapid metabolic response to meet increased energy demands for cell division, differentiation and development of effector function. Glucose uptake and engagement of the glycolytic pathway are major checkpoints for this event. Here we show that the low-affinity, concentration-dependent glucose transporter 2 (Glut2) regulates the development of CD8+ T cell effector responses in mice by promoting glucose uptake, glycolysis and glucose storage. Expression of Glut2 is modulated by environmental factors including glucose and oxygen availability and extracellular acidification. Glut2 is highly expressed by circulating, recently primed T cells, allowing efficient glucose uptake and storage. In glucose-deprived inflammatory environments, Glut2 becomes downregulated, thus preventing passive loss of intracellular glucose. Mechanistically, Glut2 expression is regulated by a combination of molecular interactions involving hypoxia-inducible factor-1 alpha, galectin-9 and stomatin. Finally, we show that human T cells also rely on this glucose transporter, thus providing a potential target for therapeutic immunomodulation.

DOI: https://doi.org/10.1038/s42255-023-00913-9
Cell. 2023 Oct 18. pii: S0092-8674(23)01081-4. [Epub ahead of print]

Nutrient-regulated control of lysosome function by signaling lipid conversion.

Michael Ebner, Dmytro Puchkov, Orestes López-Ortega, Pathma Muthukottiappan, Yanwei Su, Christopher Schmied, Silke Zillmann, Iryna Nikonenko, Jochen Koddebusch, Gillian L Dornan, Max T Lucht, Vonda Koka, Wonyul Jang, Philipp Alexander Koch, Alexander Wallroth, Martin Lehmann, Britta Brügger, Mario Pende, Dominic Winter, Volker Haucke.

  Lysosomes serve dual antagonistic functions in cells by mediating anabolic growth signaling and the catabolic turnover of macromolecules. How these janus-faced activities are regulated in response to cellular nutrient status is poorly understood. We show here that lysosome morphology and function are reversibly controlled by a nutrient-regulated signaling lipid switch that triggers the conversion between peripheral motile mTOR complex 1 (mTORC1) signaling-active and static mTORC1-inactive degradative lysosomes clustered at the cell center. Starvation-triggered relocalization of phosphatidylinositol 4-phosphate (PI(4)P)-metabolizing enzymes reshapes the lysosomal surface proteome to facilitate lysosomal proteolysis and to repress mTORC1 signaling. Concomitantly, lysosomal phosphatidylinositol 3-phosphate (PI(3)P), which marks motile signaling-active lysosomes in the cell periphery, is erased. Interference with this PI(3)P/PI(4)P lipid switch module impairs the adaptive response of cells to altering nutrient supply. Our data unravel a key function for lysosomal phosphoinositide metabolism in rewiring organellar membrane dynamics in response to cellular nutrient status.

Keywords:  catabolism; functional proteomics; live correlative light and electron microscopy; lysosomes; mTOR; myotubularin; nutrient signaling; nutrients; phosphoinositides

DOI:  https://doi.org/10.1016/j.cell.2023.09.027
J Biol Chem. 2023 Oct 19. pii: S0021-9258(23)02403-1. [Epub ahead of print] 105375

Loss of Muscle PDH Induces Lactic Acidosis and Adaptive Anaplerotic Compensation via Pyruvate-Alanine Cycling and Glutaminolysis.

Keshav Gopal, Abdualrahman Mohammed Abdualkader, Xiaobei Li, Amanda A Greenwell, Qutuba G Karwi, Tariq R Altamimi, Christina Saed, Golam M Uddin, Ahmed M Darwesh, K Lockhart Jamieson, Ryekjang Kim, Farah Eaton, John M Seubert, Gary D Lopaschuk, John R Ussher, Rami Al Batran.

  Pyruvate dehydrogenase (PDH) is the rate-limiting enzyme for glucose oxidation that links glycolysis-derived pyruvate with the tricarboxylic acid (TCA) cycle. Although skeletal muscle is a significant site for glucose oxidation and is closely linked with metabolic flexibility, the importance of muscle PDH during rest and exercise has yet to be fully elucidated. Here, we demonstrate that mice with muscle-specific deletion of PDH exhibit rapid weight loss and suffer from severe lactic acidosis, ultimately leading to early mortality under low-fat diet provision. Furthermore, loss of muscle PDH induces adaptive anaplerotic compensation by increasing pyruvate-alanine cycling and glutaminolysis. Interestingly, high-fat diet supplementation effectively abolishes the early mortality and rescues the overt metabolic phenotype induced by muscle PDH deficiency. Despite increased reliance on fatty acid oxidation during high-fat diet provision, loss of muscle PDH worsens exercise performance and induces lactic acidosis. These observations illustrate the importance of muscle PDH in maintaining metabolic flexibility and preventing the development of metabolic disorders.

Keywords:  Alanine Cycling; Fatty Acid Oxidation; Glucose Oxidation; Glutaminolysis; Glycolysis

DOI:  https://doi.org/10.1016/j.jbc.2023.105375
FASEB J. 2023 Dec;37(12): e23268

Methionine-CBS axis promotes intracellular ROS levels by reprogramming serine metabolism.

Jingyun Chen, Xiangyan Cui, Ning Fang, Yu Wu, Shujian Yu, Dong Xiao.

  As a non-essential amino acid, cysteine could be obtained through both exogenous uptake and endogenous de novo synthesis pathways. Research has demonstrated that restricting the uptake of cystine could result in a depletion of intracellular cysteine and glutathione, ultimately leading to an increase in intracellular reactive oxygen species (ROS) levels. However, the role of methionine in regulating intracellular ROS levels is currently unclear. Here, we want to explore the role of methionine in regulating intracellular ROS levels. We found that methionine restriction could lead to a decrease in intracellular ROS levels, while supplementation with SAM can restore these levels through flow cytometry. Mechanically, we found that the methionine-SAM axis relies on CBS when regulating intracellular ROS levels. Furthermore, we speculate and prove that the methionine-SAM-CBS axis alters the metabolism of serine, thereby reducing intracellular reductive power, therefore promoting intracellular ROS levels through changing metabolite levels and genetic methods. Finally, our study revealed that high expression of CBS in tumor cells could lead to increased intracellular ROS levels, ultimately resulting in faster proliferation rates. Together, our study confirmed that methionine plays a promoting role in the regulation of intracellular ROS levels.

Keywords:  CBS; ROS; SAM; methionine; serine

DOI:  https://doi.org/10.1096/fj.202300804RRRR
iScience. 2023 Nov 17. 26(11): 108137

A fingerprint of 2-[18F]FDG radiometabolites - How tissue-specific metabolism beyond 2-[18F]FDG-6-P could affect tracer accumulation.

Eva-Maria Patronas, Theresa Balber, Anne Miller, Barbara Katharina Geist, Antje Michligk, Chrysoula Vraka, Maximilian Krisch, Nataliya Rohr-Udilova, Arvand Haschemi, Helmut Viernstein, Marcus Hacker, Markus Mitterhauser.

  Studies indicate that the radiotracer 2-[18F]fluoro-2-deoxy-D-glucose (2-[18F]FDG) can be metabolized beyond 2-[18F]FDG-6-phosphate (2-[18F]FDG-6-P), but its metabolism is incompletely understood. Most importantly, it remains unclear whether downstream metabolism affects tracer accumulation in vivo. Here we present a fingerprint of 2-[18F]FDG radiometabolites over time in cancer cells, corresponding tumor xenografts and murine organs. Strikingly, radiometabolites representing glycogen metabolism or the oxPPP correlated inversely with tracer accumulation across all examined tissues. Recent studies suggest that not only hexokinase, but also hexose-6-phosphate dehydrogenase (H6PD), an enzyme of the oxidative pentose phosphate pathway (oxPPP), determines 2-[18F]FDG accumulation. However, little is known about the corresponding enzyme glucose-6-phosphate dehydrogenase (G6PD). Our mechanistic in vitro experiments on the role of the oxPPP propose that 2-[18F]FDG can be metabolized via both G6PD and H6PD, but data from separate enzyme knockdown suggest diverging roles in downstream tracer metabolism. Overall, we propose that tissue-specific metabolism beyond 2-[18F]FDG-6-P could matter for imaging.

Keywords:  cancer; nuclear medicine; radiochemicals

DOI:  https://doi.org/10.1016/j.isci.2023.108137
Nat Commun. 2023 Oct 25. 14(1): 6779

Organoids transplantation attenuates intestinal ischemia/reperfusion injury in mice through L-Malic acid-mediated M2 macrophage polarization.

Fang-Ling Zhang, Zhen Hu, Yi-Fan Wang, Wen-Juan Zhang, Bo-Wei Zhou, Qi-Shun Sun, Ze-Bin Lin, Ke-Xuan Liu.

Intestinal organoid transplantation is a promising therapy for the treatment of mucosal injury. However, how the transplanted organoids regulate the immune microenvironment of recipient mice and their role in treating intestinal ischemia-reperfusion (I/R) injury remains unclear. Here, we establish a method for transplanting intestinal organoids into intestinal I/R mice. We find that transplantation improve mouse survival, promote self-renewal of intestinal stem cells and regulate the immune microenvironment after intestinal I/R, depending on the enhanced ability of macrophages polarized to an anti-inflammatory M2 phenotype. Specifically, we report that L-Malic acid (MA) is highly expressed and enriched in the organoids-derived conditioned medium and cecal contents of transplanted mice, demonstrating that organoids secrete MA during engraftment. Both in vivo and in vitro experiments demonstrate that MA induces M2 macrophage polarization and restores interleukin-10 levels in a SOCS2-dependent manner. This study provides a therapeutic strategy for intestinal I/R injury.

DOI: https://doi.org/10.1038/s41467-023-42502-0
Nat Commun. 2023 Oct 25. 14(1): 6773

Visualization of accessible cholesterol using a GRAM domain-based biosensor.

Dylan Hong Zheng Koh, Tomoki Naito, Minyoung Na, Yee Jie Yeap, Pritisha Rozario, Franklin L Zhong, Kah-Leong Lim, Yasunori Saheki.

Cholesterol is important for membrane integrity and cell signaling, and dysregulation of the distribution of cellular cholesterol is associated with numerous diseases, including neurodegenerative disorders. While regulated transport of a specific pool of cholesterol, known as "accessible cholesterol", contributes to the maintenance of cellular cholesterol distribution and homeostasis, tools to monitor accessible cholesterol in live cells remain limited. Here, we engineer a highly sensitive accessible cholesterol biosensor by taking advantage of the cholesterol-sensing element (the GRAM domain) of an evolutionarily conserved lipid transfer protein, GRAMD1b. Using this cholesterol biosensor, which we call GRAM-W, we successfully visualize in real time the distribution of accessible cholesterol in many different cell types, including human keratinocytes and iPSC-derived neurons, and show differential dependencies on cholesterol biosynthesis and uptake for maintaining levels of accessible cholesterol. Furthermore, we combine GRAM-W with a dimerization-dependent fluorescent protein (ddFP) and establish a strategy for the ultrasensitive detection of accessible plasma membrane cholesterol. These tools will allow us to obtain important insights into the molecular mechanisms by which the distribution of cellular cholesterol is regulated.

DOI: https://doi.org/10.1038/s41467-023-42498-7
EMBO J. 2023 Oct 26. e113279

Systematic P2Y receptor survey identifies P2Y11 as modulator of immune responses and virus replication in macrophages.

Line Lykke Andersen, Yiqi Huang, Christian Urban, Lila Oubraham, Elena Winheim, Che Stafford, Dennis Nagl, Fionan O'Duill, Thomas Ebert, Thomas Engleitner, Søren Riis Paludan, Anne Krug, Roland Rad, Veit Hornung, Andreas Pichlmair.

  The immune system is in place to assist in ensuring tissue homeostasis, which can be easily perturbed by invading pathogens or nonpathogenic stressors causing tissue damage. Extracellular nucleotides are well known to contribute to innate immune signaling specificity and strength, but how their signaling is relayed downstream of cell surface receptors and how this translates into antiviral immunity is only partially understood. Here, we systematically investigated the responses of human macrophages to extracellular nucleotides, focusing on the nucleotide-sensing GPRC receptors of the P2Y family. Time-resolved transcriptomic analysis showed that adenine- and uridine-based nucleotides induce a specific, immediate, and transient cytokine response through the MAPK signaling pathway that regulates transcriptional activation by AP-1. Using receptor trans-complementation, we identified a subset of P2Ys (P2Y1, P2Y2, P2Y6, and P2Y11) that govern inflammatory responses via cytokine induction, while others (P2Y4, P2Y11, P2Y12, P2Y13, and P2Y14) directly induce antiviral responses. Notably, P2Y11 combined both activities, and depletion or inhibition of this receptor in macrophages impaired both inflammatory and antiviral responses. Collectively, these results highlight the underappreciated functions of P2Y receptors in innate immune processes.

Keywords:  P2YR; antiviral immunity; cytokine induction; innate immunity; nucleotide sensing

DOI:  https://doi.org/10.15252/embj.2022113279
Nat Commun. 2023 Oct 25. 14(1): 6772

Immune synapse formation promotes lipid peroxidation and MHC-I upregulation in licensed dendritic cells for efficient priming of CD8+ T cells.

Diego Calzada-Fraile, Salvador Iborra, Marta Ramírez-Huesca, Inmaculada Jorge, Enrico Dotta, Elena Hernández-García, Noa Martín-Cófreces, Estanislao Nistal-Villán, Esteban Veiga, Jesús Vázquez, Giulia Pasqual, Francisco Sánchez-Madrid.

Antigen cognate dendritic cell (DC)-T cell synaptic interactions drive activation of T cells and instruct DCs. Upon receiving CD4+ T cell help, post-synaptic DCs (psDCs) are licensed to generate CD8+ T cell responses. However, the cellular and molecular mechanisms that enable psDCs licensing remain unclear. Here, we describe that antigen presentation induces an upregulation of MHC-I protein molecules and increased lipid peroxidation on psDCs in vitro and in vivo. We also show that these events mediate DC licensing. In addition, psDC adoptive transfer enhances pathogen-specific CD8+ T responses and protects mice from infection in a CD8+ T cell-dependent manner. Conversely, depletion of psDCs in vivo abrogates antigen-specific CD8+ T cell responses during immunization. Together, our data show that psDCs enable CD8+ T cell responses in vivo during vaccination and reveal crucial molecular events underlying psDC licensing.

DOI: https://doi.org/10.1038/s41467-023-42480-3
Redox Biol. 2023 Oct 19. pii: S2213-2317(23)00338-5. [Epub ahead of print]67 102937

Cardiomyocyte NOX4 regulates resident macrophage-mediated inflammation and diastolic dysfunction in stress cardiomyopathy.

Aleksandr E Vendrov, Han Xiao, Andrey Lozhkin, Takayuki Hayami, Guomin Hu, Matthew J Brody, Junichi Sadoshima, You-Yi Zhang, Marschall S Runge, Nageswara R Madamanchi.

  In acute sympathetic stress, catecholamine overload can lead to stress cardiomyopathy. We tested the hypothesis that cardiomyocyte NOX4 (NADPH oxidase 4)-dependent mitochondrial oxidative stress mediates inflammation and diastolic dysfunction in stress cardiomyopathy. Isoproterenol (ISO; 5 mg/kg) injection induced sympathetic stress in wild-type and cardiomyocyte (CM)-specific Nox4 knockout (Nox4CM-/-) mice. Wild-type mice treated with ISO showed higher CM NOX4 expression, H2O2 levels, inflammasome activation, and IL18, IL6, CCL2, and TNFα levels than Nox4CM-/- mice. Spectral flow cytometry and t-SNE analysis of cardiac cell suspensions showed significant increases in pro-inflammatory and pro-fibrotic embryonic-derived resident (CCR2-MHCIIhiCX3CR1hi) macrophages in wild-type mice 3 days after ISO treatment, whereas Nox4CM-/- mice had a higher proportion of embryonic-derived resident tissue-repair (CCR2-MHCIIloCX3CR1lo) macrophages. A significant increase in cardiac fibroblast activation and interstitial collagen deposition and a restrictive pattern of diastolic dysfunction with increased filling pressure was observed in wild-type hearts compared with Nox4CM-/- 7 days post-ISO. A selective NOX4 inhibitor, GKT137831, reduced myocardial mitochondrial ROS, macrophage infiltration, and fibrosis in ISO-injected wild-type mice, and preserved diastolic function. Our data suggest sympathetic overstimulation induces resident macrophage (CCR2-MHCII+) activation and myocardial inflammation, resulting in fibrosis and impaired diastolic function mediated by CM NOX4-dependent ROS.

Keywords:  Cardiac fibroblasts; Cardiomyocyte mitochondria; Cardiomyopathy; Diastolic dysfunction; NADPH oxidase 4; Resident macrophages

DOI:  https://doi.org/10.1016/j.redox.2023.102937
Proc Natl Acad Sci U S A. 2023 Oct 31. 120(44): e2306632120

Developing synthetic tools to decipher the tumor-immune interactome.

Orr-El Weizman, Sophia Luyten, Peiwen Lu, Eric Song, Kai Qin, Darius Mostaghimi, Aaron M Ring, Akiko Iwasaki.

  The ability of immune cells to directly interact with transformed cells is an essential component of immune surveillance and critical for optimal tissue function. The tumor-immune interactome (the collective cellular interactions between oncogenic cells and immune cells) is distinct and varied based on the tissue location and immunogenicity of tumor subtypes. However, comprehensive landscape and the consequences of tumor-interacting immune cells in the tumor microenvironment are not well understood. Current tools are limited in their ability to identify and record interactors in vivo or be utilized for downstream analysis. Here, we describe the development and validation of a technology leveraging synthetic Notch receptors reporting physical tumor cell-immune cell contact in vivo in order to decipher the tumor-immune interactome. We call this approach, Tumor-Immune Interactome Non-biased Discovery Retroviral Reporter or TIINDRR. Using TIINDRR, we identify the tumor-immune interactomes that define immunological refractory and sensitive tumors and how different immunotherapies alter these interactions. Thus, TIINDRR provides a flexible and versatile tool for studying in-vivo tumor-immune cell interactions, aiding in the identification of biologically relevant information needed for the rational design of immune-based therapies.

Keywords:  T cells; cancer immunology; immunotherapy; myeloid cells; surveillance

DOI:  https://doi.org/10.1073/pnas.2306632120
Metabolism. 2023 Oct 20. pii: S0026-0495(23)00313-X. [Epub ahead of print] 155709

Brown adipose tissue-derived metabolites and their role in regulating metabolism.

Khanyisani Ziqubu, Phiwayinkosi V Dludla, Sihle E Mabhida, Babalwa U Jack, Susanne Keipert, Martin Jastroch, Sithandiwe E Mazibuko-Mbeje.

  The discovery and rejuvenation of metabolically active brown adipose tissue (BAT) in adult humans have offered a new approach to treating obesity and metabolic diseases. Beyond an accomplished role in adaptive thermogenesis, BAT secretes signaling molecules known as "batokines", which are instrumental in regulating whole-body metabolism via autocrine, paracrine, and endocrine action. In addition to the intrinsic BAT metabolite-oxidizing activity, the endocrine functions of these molecules may help to explain the association between BAT activity and a healthy systemic metabolic profile. Herein, we review the evidence that underscores the significance of BAT-derived metabolites, especially highlighting their role in controlling physiological and metabolic processes involving thermogenesis, substrate metabolism, and other essential biological processes. The conversation extends to their capacity to enhance energy expenditure and mitigate features of obesity and its related metabolic complications. Thus, metabolites derived from BAT may provide new avenues for the discovery of metabolic health-promoting drugs with far-reaching impacts. This review aims to dissect the complexities of the secretory role of BAT in modulating local and systemic metabolism in metabolic health and disease.

Keywords:  Batokines; Brown adipose tissue; Metabolic diseases; Metabolism; Metabolites; Obesity; Secretome

DOI:  https://doi.org/10.1016/j.metabol.2023.155709
J Cell Biol. 2024 Jan 01. pii: e202303026. [Epub ahead of print]223(1):

Tld1 is a regulator of triglyceride lipolysis that demarcates a lipid droplet subpopulation.

Natalie Ortiz Speer, R Jay Braun, Emma Grace Reynolds, Alicja Brudnicka, Jessica M J Swanson, W Mike Henne.

Cells store lipids in the form of triglyceride (TG) and sterol ester (SE) in lipid droplets (LDs). Distinct pools of LDs exist, but a pervasive question is how proteins localize to and convey functions to LD subsets. Here, we show that the yeast protein YDR275W/Tld1 (for TG-associated LD protein 1) localizes to a subset of TG-containing LDs and reveal it negatively regulates lipolysis. Mechanistically, Tld1 LD targeting requires TG, and it is mediated by two distinct hydrophobic regions (HRs). Molecular dynamics simulations reveal that Tld1's HRs interact with TG on LDs and adopt specific conformations on TG-rich LDs versus SE-rich LDs in yeast and human cells. Tld1-deficient yeast display no defect in LD biogenesis but exhibit elevated TG lipolysis dependent on lipase Tgl3. Remarkably, overexpression of Tld1, but not LD protein Pln1/Pet10, promotes TG accumulation without altering SE pools. Finally, we find that Tld1-deficient cells display altered LD mobilization during extended yeast starvation. We propose that Tld1 senses TG-rich LDs and regulates lipolysis on LD subpopulations.

DOI: https://doi.org/10.1083/jcb.202303026
Nat Commun. 2023 Oct 23. 14(1): 6721

The mitochondrial fusion protein OPA1 is dispensable in the liver and its absence induces mitohormesis to protect liver from drug-induced injury.

Hakjoo Lee, Tae Jin Lee, Chad A Galloway, Wenbo Zhi, Wei Xiao, Karen L de Mesy Bentley, Ashok Sharma, Yong Teng, Hiromi Sesaki, Yisang Yoon.

Mitochondria are critical for metabolic homeostasis of the liver, and their dysfunction is a major cause of liver diseases. Optic atrophy 1 (OPA1) is a mitochondrial fusion protein with a role in cristae shaping. Disruption of OPA1 causes mitochondrial dysfunction. However, the role of OPA1 in liver function is poorly understood. In this study, we delete OPA1 in the fully developed liver of male mice. Unexpectedly, OPA1 liver knockout (LKO) mice are healthy with unaffected mitochondrial respiration, despite disrupted cristae morphology. OPA1 LKO induces a stress response that establishes a new homeostatic state for sustained liver function. Our data show that OPA1 is required for proper complex V assembly and that OPA1 LKO protects the liver from drug toxicity. Mechanistically, OPA1 LKO decreases toxic drug metabolism and confers resistance to the mitochondrial permeability transition. This study demonstrates that OPA1 is dispensable in the liver, and that the mitohormesis induced by OPA1 LKO prevents liver injury and contributes to liver resiliency.

DOI: https://doi.org/10.1038/s41467-023-42564-0
Proc Natl Acad Sci U S A. 2023 Oct 31. 120(44): e2308511120

The total mass, number, and distribution of immune cells in the human body.

Ron Sender, Yarden Weiss, Yoav Navon, Idan Milo, Nofar Azulay, Leeat Keren, Shai Fuchs, Danny Ben-Zvi, Elad Noor, Ron Milo.

  The immune system is a complex network of cells with critical functions in health and disease. However, a comprehensive census of the cells comprising the immune system is lacking. Here, we estimated the abundance of the primary immune cell types throughout all tissues in the human body. We conducted a literature survey and integrated data from multiplexed imaging and methylome-based deconvolution. We also considered cellular mass to determine the distribution of immune cells in terms of both number and total mass. Our results indicate that the immune system of a reference 73 kg man consists of 1.8 × 1012 cells (95% CI 1.5-2.3 × 1012), weighing 1.2 kg (95% CI 0.8-1.9). Lymphocytes constitute 40% of the total number of immune cells and 15% of the mass and are mainly located in the lymph nodes and spleen. Neutrophils account for similar proportions of both the number and total mass of immune cells, with most neutrophils residing in the bone marrow. Macrophages, present in most tissues, account for 10% of immune cells but contribute nearly 50% of the total cellular mass due to their large size. The quantification of immune cells within the human body presented here can serve to understand the immune function better and facilitate quantitative modeling of this vital system.

Keywords:  distribution; immune cells; lymphocyte; macrophage; total mass

DOI:  https://doi.org/10.1073/pnas.2308511120
Nat Cell Biol. 2023 Oct 26.

Manganese regulation of COPII condensation controls circulating lipid homeostasis.

Xiao Wang, Runze Huang, Yawei Wang, Wenjing Zhou, Yating Hu, Yuanhang Yao, Kunlun Cheng, Xin Li, Bolin Xu, Jie Zhang, Yaowen Xu, Fanxin Zeng, Yuangang Zhu, Xiao-Wei Chen.

Precise control of circulating lipids is instrumental in health and disease. Bulk lipids, carried by specialized lipoproteins, are secreted into the circulation, initially via the coat protein complex II (COPII). How the universal COPII machinery accommodates the abundant yet unconventional lipoproteins remains unclear, let alone its therapeutic translation. Here we report that COPII uses manganese-tuning, self-constrained condensation to selectively drive lipoprotein delivery and set lipid homeostasis in vivo. Serendipitously, adenovirus hijacks the condensation-based transport mechanism, thus enabling the identification of cytosolic manganese as an unexpected control signal. Manganese directly binds the inner COPII coat and enhances its condensation, thereby shifting the assembly-versus-dynamics balance of the transport machinery. Manganese can be mobilized from mitochondria stores to signal COPII, and selectively controls lipoprotein secretion with a distinctive, bell-shaped function. Consequently, dietary titration of manganese enables tailored lipid management that counters pathological dyslipidaemia and atherosclerosis, implicating a condensation-targeting strategy with broad therapeutic potential for cardio-metabolic health.

DOI: https://doi.org/10.1038/s41556-023-01260-3
Nat Rev Endocrinol. 2023 Oct 23.

Macrophage and T cell networks in adipose tissue.

Ramiah D Jacks, Carey N Lumeng.

The signals and structure of the tissues in which leukocytes reside critically mould leukocyte function and development and have challenged our fundamental understanding of how to define and categorize tissue-resident immune cells. One specialized tissue niche that has a powerful effect on immune cell function is adipose tissue. The field of adipose tissue leukocyte biology has expanded dramatically and has revealed how tissue niches can shape immune cell function and reshape them in a setting of metabolic stress, such as obesity. Most notably, adipose tissue macrophages and T cells are under intense investigation due to their contributions to adipose tissue in the lean and obese states. Both adipose tissue macrophages and T cells have features associated with the metabolic function of adipose tissue that are distinct from features of macrophages and T cells that are classically characterized in other tissues. This Review provides state-of-the-art understanding of adipose tissue macrophages and T cells and discusses how their unique niche can help us to better understand diversity in leukocyte responses.

DOI: https://doi.org/10.1038/s41574-023-00908-2
J Immunother Cancer. 2023 Oct;pii: e007349. [Epub ahead of print]11(10):

MCT4 blockade increases the efficacy of immune checkpoint blockade.

Nathalie Babl, Sonja-Maria Decking, Florian Voll, Michael Althammer, Ada Sala-Hojman, Roberta Ferretti, Clarissa Korf, Christian Schmidl, Lisa Schmidleithner, Benedikt Nerb, Carina Matos, Gudrun E Koehl, Peter Siska, Christina Bruss, Fabian Kellermeier, Katja Dettmer, Peter J Oefner, Marvin Wichland, Ines Ugele, Christopher Bohr, Wolfgang Herr, Shivapriya Ramaswamy, Timo Heinrich, Christian Herhaus, Marina Kreutz, Kathrin Renner.

   BACKGROUND & AIMS: Intratumoral lactate accumulation and acidosis impair T-cell function and antitumor immunity. Interestingly, expression of the lactate transporter monocarboxylate transporter (MCT) 4, but not MCT1, turned out to be prognostic for the survival of patients with rectal cancer, indicating that single MCT4 blockade might be a promising strategy to overcome glycolysis-related therapy resistance.
METHODS: To determine whether blockade of MCT4 alone is sufficient to improve the efficacy of immune checkpoint blockade (ICB) therapy, we examined the effects of the selective MCT1 inhibitor AZD3965 and a novel MCT4 inhibitor in a colorectal carcinoma (CRC) tumor spheroid model co-cultured with blood leukocytes in vitro and the MC38 murine CRC model in vivo in combination with an antibody against programmed cell death ligand-1(PD-L1).
RESULTS: Inhibition of MCT4 was sufficient to reduce lactate efflux in three-dimensional (3D) CRC spheroids but not in two-dimensional cell-cultures. Co-administration of the MCT4 inhibitor and ICB augmented immune cell infiltration, T-cell function and decreased CRC spheroid viability in a 3D co-culture model of human CRC spheroids with blood leukocytes. Accordingly, combination of MCT4 and ICB increased intratumoral pH, improved leukocyte infiltration and T-cell activation, delayed tumor growth, and prolonged survival in vivo. MCT1 inhibition exerted no further beneficial impact.
CONCLUSIONS: These findings demonstrate that single MCT4 inhibition represents a novel therapeutic approach to reverse lactic-acid driven immunosuppression and might be suitable to improve ICB efficacy.

Keywords:  Drug Therapy, Combination; Immune Checkpoint Inhibitors; Immunologic Surveillance; Lymphocytes, Tumor-Infiltrating; Metabolism; Tumor Microenvironment

DOI:  https://doi.org/10.1136/jitc-2023-007349
J Biol Chem. 2023 Oct 21. pii: S0021-9258(23)02407-9. [Epub ahead of print] 105379

AMPKα1 negatively regulates osteoclastogenesis and mitigate pathological bone loss.

Mariana S P Ribeiro, Lucas G R Venturini, Cesar A Speck-Hernandez, Paulo V G Alabarse, Thais Xavier, Thaise M Taira, Letícia F D Rodrigues, Fernando Q Cunha, Sandra Y Fukada.

  Osteoclasts are specialized cells in the human body responsible for bone resorption, a highly energy-demanding process. Focus on osteoclast metabolism could be a key for the treatment of osteolytic diseases including osteoporosis. In this context, AMPKα1, an energy sensor highly expressed in osteoclasts, participates in the metabolic reconfiguration during osteoclast differentiation and activation. This study aimed to elucidate the role of AMPKα1 during osteoclastogenesis in vitro and its impact in bone loss in vivo. Using LysMcre/0AMPK⍺1f/f animals, and their respective LysMcre/0 controls we evaluated how AMPKα1 interferes with osteoclastogenesis and bone resorption activity in vitro. We found that AMPKα1 is highly expressed in the early stages of osteoclastogenesis. Genetic deletion of AMPKα1 leads to increased gene expression of osteoclast differentiation and fusion markers such as Nfatc1, Dcstamp. In addition, LysMcre/0AMPK⍺1f/f mice had an increased number and size of differentiated osteoclast. Accordingly, our data suggest that AMPKα1 negatively regulates bone resorption in vitro, as evidenced by the elevated expression of Ctsk and Mmp9 along with an increase in the area of bone resorption in LysMcre/0AMPK⍺1f/f osteoclasts. Our data further demonstrated that AMPKα1 regulates mitochondrial fusion and fission markers upregulating Mfn2 and downregulating DRP1, and that Ctskcre/0AMPK⍺1f/f osteoclasts ultimately leading to an increase in the number of mitochondria in AMPK⍺1 deficient osteoclast. In our in vivo study, femurs from Ctskcre/0AMPK⍺1f/f animals exhibited bone loss associated with the increased number of osteoclasts. Interestingly, in the ovariectomy model, no significant difference in bone loss was observed between Ctskcre/0AMPK⍺1f/f ovariectomized and Sham groups. Our data suggest that AMPKα1 act as a negative regulator of osteoclastogenesis, and the depletion of AMPKα1 in osteoclast leads to a bone loss state similar to that observed after ovariectomy.

Keywords:  AMPK; metabolism; osteoclast; osteoclastogenesis; osteoporosis

DOI:  https://doi.org/10.1016/j.jbc.2023.105379
J Hepatol. 2023 Oct 25. pii: S0168-8278(23)05184-X. [Epub ahead of print]

Circadian dysfunction induces NAFLD-related human liver cancer in a mouse model.

Jennifer Padilla, Noha M Osman, Beatrice Bissig-Choisat, Sandra L Grimm, Xuan Qin, Angela M Major, Li Yang, Dolores Lopez-Terrada, Cristian Coarfa, Feng Li, Karl-Dimiter Bissig, David D Moore, Loning Fu.

   BACKGROUND & AIMS: Chronic circadian dysfunction increases the risk of nonalcoholic fatty liver disease (NAFLD)-related hepatocellular carcinoma (HCC) but the underlying mechanisms and direct relevance to human HCC are not established. This study is to determine whether chronic circadian dysregulation can drive NAFLD-related carcinogenesis from human hepatocytes and human HCC progression.
METHODS: Chronic jet lag of mice with humanized livers induces spontaneous NAFLD-related HCCs from human hepatocytes. The clinical relevance of humanized HCC was analyzed by biomarker, pathological/histological, genetic, RNAseq, metabolomic, and integrated bioinformatic analyses.
RESULTS: Circadian dysfunction induces glucose intolerance, NAFLD-associated human HCCs, and human HCC metastasis independent of diet choice in a humanized mouse model. The deregulated transcriptomes in necrotic-inflammatory humanized livers and HCCs bear striking resemblances to those of human non-alcoholic steatohepatitis (NASH), cirrhosis, and HCCs. Stable circadian entrainment of hosts rhythmically paces NASH and HCC transcriptomes to decrease HCC incidence and prevent HCC metastasis. Circadian disruption directly reprograms NASH and HCC transcriptomes to drive a rapid progression from hepatocarcinogenesis to HCC metastasis. Human hepatocyte and tumour transcripts are clearly distinguishable from mouse transcripts in non-parenchymal cells and tumour stroma and display dynamic changes in metabolism, inflammation, angiogenesis, and oncogenic signaling in NASH, progressing to hepatocyte malignant transformation and immunosuppressive tumour stroma in HCCs. Metabolomic analysis defines specific bile acids as prognostic biomarkers that change dynamically during hepatocarcinogenesis and in response to circadian disruption at all disease stages.
CONCLUSION: Chronic circadian dysfunction is an independent carcinogen to human hepatocytes. Mice with humanized livers provide a powerful preclinical model for studying the impact of the necrotic-inflammatory liver environment and neuroendocrine circadian dysfunction in hepatocarcinogenesis and anti-HCC therapy. IMPACT AND IMPLICATIONS-2: Human epidemiological studies have linked chronic circadian dysfunction to increased HCC risk, but direct evidence that circadian dysfunction is a human carcinogen has not been established. Here we show that circadian dysfunction induces nonalcoholic steatohepatitis (NASH)-related carcinogenesis from human hepatocytes in a murine humanized liver model following the same molecular and pathologic pathways observed in human patients. The gene expression signatures of humanized HCC transcriptomes from circadian disrupted mice closely match those of human HCC with the poorest prognostic outcomes, while those from stably circadian entrained mice match those from human HCC with the best prognostic outcomes. Our studies open a new model for defining to the mechanism of NASH-related HCC and highlight the importance of circadian biology in HCC prevention and treatment.

Keywords:  Cirrhosis; Hepatocellular carcinoma; Non-alcoholic steatohepatitis (NASH); circadian disruption; circadian transcriptomes

DOI:  https://doi.org/10.1016/j.jhep.2023.10.018
Mol Cell. 2023 Oct 20. pii: S1097-2765(23)00800-6. [Epub ahead of print]

Lactate activates the mitochondrial electron transport chain independently of its metabolism.

Xin Cai, Charles P Ng, Olivia Jones, Tak Shun Fung, Keun Woo Ryu, Dayi Li, Craig B Thompson.

  Lactate has long been considered a cellular waste product. However, we found that as extracellular lactate accumulates, it also enters the mitochondrial matrix and stimulates mitochondrial electron transport chain (ETC) activity. The resulting increase in mitochondrial ATP synthesis suppresses glycolysis and increases the utilization of pyruvate and/or alternative respiratory substrates. The ability of lactate to increase oxidative phosphorylation does not depend on its metabolism. Both L- and D-lactate are effective at enhancing ETC activity and suppressing glycolysis. Furthermore, the selective induction of mitochondrial oxidative phosphorylation by unmetabolized D-lactate reversibly suppressed aerobic glycolysis in both cancer cell lines and proliferating primary cells in an ATP-dependent manner and enabled cell growth on respiratory-dependent bioenergetic substrates. In primary T cells, D-lactate enhanced cell proliferation and effector function. Together, these findings demonstrate that lactate is a critical regulator of the ability of mitochondrial oxidative phosphorylation to suppress glucose fermentation.

Keywords:  TCA cycle; electron transport chain; glycolysis; lactate; mitochondria; oxidative phosphorylation

DOI:  https://doi.org/10.1016/j.molcel.2023.09.034
J Proteome Res. 2023 Oct 25.

A Guide to MALDI Imaging Mass Spectrometry for Tissues.

Jessica L Moore, Georgia Charkoftaki.

  Imaging mass spectrometry is a well-established technology that can easily and succinctly communicate the spatial localization of molecules within samples. This review communicates the recent advances in the field, with a specific focus on matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) applied on tissues. The general sample preparation strategies for different analyte classes are explored, including special considerations for sample types (fresh frozen or formalin-fixed,) strategies for various analytes (lipids, metabolites, proteins, peptides, and glycans) and how multimodal imaging strategies can leverage the strengths of each approach is mentioned. This work explores appropriate experimental design approaches and standardization of processes needed for successful studies, as well as the various data analysis platforms available to analyze data and their strengths. The review concludes with applications of imaging mass spectrometry in various fields, with a focus on medical research, and some examples from plant biology and microbe metabolism are mentioned, to illustrate the breadth and depth of MALDI IMS.

Keywords:  MALDI; imaging mass spectrometry; spatialomics; tissues

DOI:  https://doi.org/10.1021/acs.jproteome.3c00167
Nat Commun. 2023 Oct 21. 14(1): 6686

An innate granuloma eradicates an environmental pathogen using Gsdmd and Nos2.

Carissa K Harvest, Taylor J Abele, Chen Yu, Cole J Beatty, Megan E Amason, Zachary P Billman, Morgan A DePrizio, Fernando W Souza, Carolyn A Lacey, Vivien I Maltez, Heather N Larson, Benjamin D McGlaughon, Daniel R Saban, Stephanie A Montgomery, Edward A Miao.

Granulomas often form around pathogens that cause chronic infections. Here, we discover an innate granuloma model in mice with an environmental bacterium called Chromobacterium violaceum. Granuloma formation not only successfully walls off, but also clears, the infection. The infected lesion can arise from a single bacterium that replicates despite the presence of a neutrophil swarm. Bacterial replication ceases when macrophages organize around the infection and form a granuloma. This granuloma response is accomplished independently of adaptive immunity that is typically required to organize granulomas. The C. violaceum-induced granuloma requires at least two separate defense pathways, gasdermin D and iNOS, to maintain the integrity of the granuloma architecture. This innate granuloma successfully eradicates C. violaceum infection. Therefore, this C. violaceum-induced granuloma model demonstrates that innate immune cells successfully organize a granuloma and thereby resolve infection by an environmental pathogen.

DOI: https://doi.org/10.1038/s41467-023-42218-1
Hepatology. 2023 Oct 23.

A genetic basis of mitochondrial DNAJA3 in nonalcoholic steatohepatitis-related hepatocellular carcinoma.

Ching-Wen Chang, Yu-Syuan Chen, Chen-Hua Huang, Chao-Hsiung Lin, Wailap Victor Ng, Lichieh Julie Chu, Eric Trépo, Jessica Zucman-Rossi, Kevin Siao, Jacquelyn J Maher, Men Yee Chiew, Chih-Hung Chou, Hsien-Da Huang, Wan-Huai Teo, I-Shan Lee, Jeng-Fan Lo, Xin Wei Wang.

BACKGROUND AIMS: Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver disease worldwide but only a subset of NAFLD individuals may progress to nonalcoholic steatohepatitis (NASH). While NASH is an important etiology of hepatocellular carcinoma (HCC), the underlying mechanisms responsible for conversion of NAFLD to NASH, and then to HCC are poorly understood. We aimed to identify genetic risk genes that drive NASH and NASH-related HCC.
APPROACH AND RESULTS: We searched genetic alleles among the 24 most significant alleles associated with body fat distribution from a genome-wide association study of 344,369 individuals and validated the top allele in three independent cohorts of American and European patients (N=1,380) with NAFLD/NASH/HCC. We identified a rs3747579-TT variant significantly associated with NASH-related HCC and demonstrated that rs3747579 is eQTL of a mitochondrial DNAJA3. We also found that rs3747579-TT and a previously identified PNPLA3 as a functional variant of NAFLD to have a significant additional interactions with NASH/HCC risk. HCC patients with rs3747579-TT had a reduced expression of DNAJA3 and had an unfavorable prognosis. Furthermore, mice with hepatocyte-specific Dnaja3 depletion developed NASH-dependent HCC either spontaneously under a normal diet or enhanced by diethylnitrosamine. Dnaja3-deficient mice developed NASH/HCC characterized by significant mitochondrial dysfunction, which was accompanied by excessive lipid accumulation and inflammatory responses. The molecular features of NASH/HCC in the Dnaja3 deficient mice were closely associated with human NASH/HCC.
CONCLUSION: We uncovered a genetic basis of DNAJA3 as a key player of NASH-related HCC.

DOI: https://doi.org/10.1097/HEP.0000000000000637
Sci Rep. 2023 Oct 26. 13(1): 18374

Environmental stiffness restores mechanical homeostasis in vimentin-depleted cells.

Janine Grolleman, Nicole C A van Engeland, Minahil Raza, Sepinoud Azimi, Vito Conte, Cecilia M Sahlgren, Carlijn V C Bouten.

Recent experimental evidence indicates a role for the intermediate filament vimentin in regulating cellular mechanical homeostasis, but its precise contribution remains to be discovered. Mechanical homeostasis requires a balanced bi-directional interplay between the cell's microenvironment and the cellular morphological and mechanical state-this balance being regulated via processes of mechanotransduction and mechanoresponse, commonly referred to as mechanoreciprocity. Here, we systematically analyze vimentin-expressing and vimentin-depleted cells in a swatch of in vitro cellular microenvironments varying in stiffness and/or ECM density. We find that vimentin-expressing cells maintain mechanical homeostasis by adapting cellular morphology and mechanics to micromechanical changes in the microenvironment. However, vimentin-depleted cells lose this mechanoresponse ability on short timescales, only to reacquire it on longer time scales. Indeed, we find that the morphology and mechanics of vimentin-depleted cell in stiffened microenvironmental conditions can get restored to the homeostatic levels of vimentin-expressing cells. Additionally, we observed vimentin-depleted cells increasing collagen matrix synthesis and its crosslinking, a phenomenon which is known to increase matrix stiffness, and which we now hypothesize to be a cellular compensation mechanism for the loss of vimentin. Taken together, our findings provide further insight in the regulating role of intermediate filament vimentin in mediating mechanoreciprocity and mechanical homeostasis.

DOI: https://doi.org/10.1038/s41598-023-44835-8
Cell. 2023 Oct 18. pii: S0092-8674(23)01078-4. [Epub ahead of print]

Human MCTS1-dependent translation of JAK2 is essential for IFN-γ immunity to mycobacteria.

Jonathan Bohlen, Qinhua Zhou, Quentin Philippot, Masato Ogishi, Darawan Rinchai, Tea Nieminen, Simin Seyedpour, Nima Parvaneh, Nima Rezaei, Niloufar Yazdanpanah, Mana Momenilandi, Clément Conil, Anna-Lena Neehus, Carltin Schmidt, Carlos A Arango-Franco, Tom Le Voyer, Taushif Khan, Rui Yang, Julia Puchan, Lucia Erazo, Mykola Roiuk, Taja Vatovec, Zarah Janda, Ivan Bagarić, Marie Materna, Adrian Gervais, Hailun Li, Jérémie Rosain, Jessica N Peel, Yoann Seeleuthner, Ji Eun Han, Anne-Sophie L'Honneur, Marcela Moncada-Vélez, Marta Martin-Fernandez, Michael E Horesh, Tatiana Kochetkov, Monika Schmidt, Mohammed A AlShehri, Eeva Salo, Harri Saxen, Gehad ElGhazali, Ahmad Yatim, Camille Soudée, Federica Sallusto, Armin Ensser, Nico Marr, Peng Zhang, Dusan Bogunovic, Aurélie Cobat, Mohammad Shahrooei, Vivien Béziat, Laurent Abel, Xiaochuan Wang, Stéphanie Boisson-Dupuis, Aurelio A Teleman, Jacinta Bustamante, Qian Zhang, Jean-Laurent Casanova.

  Human inherited disorders of interferon-gamma (IFN-γ) immunity underlie severe mycobacterial diseases. We report X-linked recessive MCTS1 deficiency in men with mycobacterial disease from kindreds of different ancestries (from China, Finland, Iran, and Saudi Arabia). Complete deficiency of this translation re-initiation factor impairs the translation of a subset of proteins, including the kinase JAK2 in all cell types tested, including T lymphocytes and phagocytes. JAK2 expression is sufficiently low to impair cellular responses to interleukin-23 (IL-23) and partially IL-12, but not other JAK2-dependent cytokines. Defective responses to IL-23 preferentially impair the production of IFN-γ by innate-like adaptive mucosal-associated invariant T cells (MAIT) and γδ T lymphocytes upon mycobacterial challenge. Surprisingly, the lack of MCTS1-dependent translation re-initiation and ribosome recycling seems to be otherwise physiologically redundant in these patients. These findings suggest that X-linked recessive human MCTS1 deficiency underlies isolated mycobacterial disease by impairing JAK2 translation in innate-like adaptive T lymphocytes, thereby impairing the IL-23-dependent induction of IFN-γ.

Keywords:  IL-23; JAK2; MCTS1; MSMD; X-linked disease; inborn error of immunity; mycobacterium; translation re-initiation

DOI:  https://doi.org/10.1016/j.cell.2023.09.024
Nat Commun. 2023 Oct 23. 14(1): 6690

The liver microenvironment orchestrates FGL1-mediated immune escape and progression of metastatic colorectal cancer.

Jia-Jun Li, Jin-Hong Wang, Tian Tian, Jia Liu, Yong-Qiang Zheng, Hai-Yu Mo, Hui Sheng, Yan-Xing Chen, Qi-Nian Wu, Yi Han, Kun Liao, Yi-Qian Pan, Zhao-Lei Zeng, Ze-Xian Liu, Wei Yang, Rui-Hua Xu, Huai-Qiang Ju.

Colorectal cancer (CRC) patients with liver metastases usually obtain less benefit from immunotherapy, and the underlying mechanisms remain understudied. Here, we identify that fibrinogen-like protein 1 (FGL1), secreted from cancer cells and hepatocytes, facilitates the progression of CRC in an intraportal injection model by reducing the infiltration of T cells. Mechanistically, tumor-associated macrophages (TAMs) activate NF-ĸB by secreting TNFα/IL-1β in the liver microenvironment and transcriptionally upregulate OTU deubiquitinase 1 (OTUD1) expression, which enhances FGL1 stability via deubiquitination. Disrupting the TAM-OTUD1-FGL1 axis inhibits metastatic tumor progression and synergizes with immune checkpoint blockade (ICB) therapy. Clinically, high plasma FGL1 levels predict poor outcomes and reduced ICB therapy benefits. Benzethonium chloride, an FDA-approved antiseptics, curbs FGL1 secretion, thereby inhibiting liver metastatic tumor growth. Overall, this study uncovers the critical roles and posttranslational regulatory mechanism of FGL1 in promoting metastatic tumor progression, highlighting the TAM-OTUD1-FGL1 axis as a potential target for cancer immunotherapy.

DOI: https://doi.org/10.1038/s41467-023-42332-0
FASEB J. 2023 11;37(11): e23265

Loss of UCP2 causes mitochondrial fragmentation by OMA1-dependent proteolytic processing of OPA1 in podocytes.

Qianqian Yang, Lulu Wang, Yuehong Liang, Qingyu He, Qi Sun, Jing Luo, Hongdi Cao, Yi Fang, Yang Zhou, Junwei Yang, Ping Wen, Lei Jiang.

  Mitochondrial dysfunction plays an important role in the onset and progression of podocyte injury and proteinuria. However, the process by which the change in the podocyte mitochondria occurs is not well understood. Uncoupling protein 2 (UCP2) is a mitochondrial anion carrier protein, which is located in the mitochondrial inner membrane. Here, we reported that mice with podocyte-specific Ucp2 deficiency developed podocytopathy with proteinuria with aging. Furthermore, those mice exhibited increased proteinuria in experimental models evoked by Adriamycin. Our findings suggest that UCP2 mediates mitochondrial dysfunction by regulating mitochondrial dynamic balance. Ucp2-deleted podocytes exhibited increased mitochondrial fission and deficient in ATP production. Mechanistically, opacity protein 1 (OPA1), a key protein in fusion of mitochondrial inner membrane, was regulated by UCP2. Ucp2 deficiency promoted proteolysis of OPA1 by activation OMA1 which belongs to mitochondrial inner membrane zinc metalloprotease. Those finding demonstrate the role of UCP2 in mitochondrial dynamics in podocytes and provide new insights into pathogenesis associated with podocyte injury and proteinuria.

Keywords:  OMA1; OPA1; UCP2; mitochondria; podocyte injury

DOI:  https://doi.org/10.1096/fj.202301055R
Cell Rep. 2023 Oct 25. pii: S2211-1247(23)01324-4. [Epub ahead of print]42(11): 113312

Mitochondrial gene expression is required for platelet function and blood clotting.

Tara R Richman, Judith A Ermer, Jessica Baker, Stefan J Siira, Benjamin T Kile, Matthew D Linden, Oliver Rackham, Aleksandra Filipovska.

  Platelets are anucleate blood cells that contain mitochondria and regulate blood clotting in response to injury. Mitochondria contain their own gene expression machinery that relies on nuclear-encoded factors for the biogenesis of the oxidative phosphorylation system to produce energy required for thrombosis. The autonomy of the mitochondrial gene expression machinery from the nucleus is unclear, and platelets provide a valuable model to understand its importance in anucleate cells. Here, we conditionally delete Elac2, Ptcd1, or Mtif3 in platelets, which are essential for mitochondrial gene expression at the level of RNA processing, stability, or translation, respectively. Loss of ELAC2, PTCD1, or MTIF3 leads to increased megakaryocyte ploidy, elevated circulating levels of reticulated platelets, thrombocytopenia, and consequent extended bleeding time. Impaired mitochondrial gene expression reduces agonist-induced platelet activation. Transcriptomic and proteomic analyses show that mitochondrial gene expression is required for fibrinolysis, hemostasis, and blood coagulation in response to injury.

Keywords:  CP: Immunology; megakaryocytes; mitochondria; mitochondrial gene expression; platelets; translation

DOI:  https://doi.org/10.1016/j.celrep.2023.113312
Redox Biol. 2023 Oct 16. pii: S2213-2317(23)00336-1. [Epub ahead of print]67 102935

A critical role for staphylococcal nitric oxide synthase in controlling flavohemoglobin toxicity.

Ryan M Singh, Sujata S Chaudhari, Sasmita Panda, Elizabeth H Hutfless, Cortney E Heim, Dhananjay Shinde, Abdulelah A Alqarzaee, Margaret Sladek, Vineet Kumar, Matthew C Zimmerman, Paul D Fey, Tammy Kielian, Vinai C Thomas.

  Most coagulase-negative staphylococcal species, including the opportunistic pathogen Staphylococcus epidermidis, struggle to maintain redox homeostasis and grow under nitrosative stress. Under these conditions, growth can only resume once nitric oxide (NO) is detoxified by the flavohemoglobin Hmp. Paradoxically, S. epidermidis produces endogenous NO through its genetically encoded nitric oxide synthase (seNOS) and heavily relies on its activity for growth. In this study, we investigate the basis of the growth advantage attributed to seNOS activity. Our findings reveal that seNOS supports growth by countering Hmp toxicity. S. epidermidis relies on Hmp activity for its survival in the host under NO stress. However, in the absence of nitrosative stress, Hmp generates significant amounts of the harmful superoxide radical (O2•-) from its heme prosthetic group which impedes growth. To limit Hmp toxicity, nitrite (NO2-) derived from seNOS promotes CymR-CysK regulatory complex activity, which typically regulates cysteine metabolism, but we now demonstrate to also repress hmp transcription. These findings reveal a critical mechanism through which the bacterial NOS-Hmp axis drives staphylococcal fitness.

Keywords:  Bacterial nitric oxide synthase; Flavohemoglobin; Respiration; Staphylococcus epidermidis; Superoxide

DOI:  https://doi.org/10.1016/j.redox.2023.102935
Open Biol. 2023 Oct;13(10): 230336

Formyl-peptide receptor 2 signalling triggers aerobic metabolism of glucose through Nox2-dependent modulation of pyruvate dehydrogenase activity.

Tiziana Pecchillo Cimmino, Ester Pagano, Mariano Stornaiuolo, Gabriella Esposito, Rosario Ammendola, Fabio Cattaneo.

  The human formyl-peptide receptor 2 (FPR2) is activated by an array of ligands. By phospho-proteomic analysis we proved that FPR2 stimulation induces redox-regulated phosphorylation of many proteins involved in cellular metabolic processes. In this study, we investigated metabolic pathways activated in FPR2-stimulated CaLu-6 cells. The results showed an increased concentration of metabolites involved in glucose metabolism, and an enhanced uptake of glucose mediated by GLUT4, the insulin-regulated member of GLUT family. Accordingly, we observed that FPR2 transactivated IGF-IRβ/IRβ through a molecular mechanism that requires Nox2 activity. Since cancer cells support their metabolism via glycolysis, we analysed glucose oxidation and proved that FPR2 signalling promoted kinase activity of the bifunctional enzyme PFKFB2 through FGFR1/FRS2- and Akt-dependent phosphorylation. Furthermore, FPR2 stimulation induced IGF-IRβ/IRβ-, PI3K/Akt- and Nox-dependent inhibition of pyruvate dehydrogenase activity, thus preventing the entry of pyruvate in the tricarboxylic acid cycle. Consequently, we observed an enhanced FGFR-dependent lactate dehydrogenase (LDH) activity and lactate production in FPR2-stimulated cells. As LDH expression is transcriptionally regulated by c-Myc and HIF-1, we demonstrated that FPR2 signalling promoted c-Myc phosphorylation and Nox-dependent HIF-1α stabilization. These results strongly indicate that FPR2-dependent signalling can be explored as a new therapeutic target in treatment of human cancers.

Keywords:  NADPH oxidase; Warburg effect; formyl peptide receptors; glucose metabolism; reactive oxygen species; tyrosine kinase receptor transactivation

DOI:  https://doi.org/10.1098/rsob.230336