bims-mepmim 2023-04-02 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2023–04–02
thirty-two papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Mapping the Metabolic Niche of Citrate Metabolism and SLC13A5.
The mitochondrial protease OMA1 acts as a metabolic safeguard upon nuclear DNA damage.
Defective Muscle Ketone Body Oxidation Disrupts BCAA Catabolism by Altering Mitochondrial Branched-Chain Aminotransferase.
Decoding the crosstalk between mevalonate metabolism and T cell function.
Immunogenetic metabolomics revealed key enzymes that modulate CAR-T metabolism and function.
Ornithine aminotransferase supports polyamine synthesis in pancreatic cancer.
Ferroptosis and Neurodegenerative Diseases: Insights into the Regulatory Roles of SLC7A11.
NO binds to the distal site of haem in the fully activated soluble guanylate cyclase.
Dynamic regulation of ferroptosis by lipid metabolism.
Cytosolic and mitochondrial NADPH fluxes are independently regulated.
Cross-Regulation of the Cellular Redox System, Oxygen, and Sphingolipid Signalling.
Time-of-day defines NAD+ efficacy to treat diet-induced metabolic disease by synchronizing the hepatic clock in mice.
Mass Spectrometry Imaging for Single-Cell or Subcellular Lipidomics: A Review of Recent Advancements and Future Development.
Tuft cell-derived acetylcholine regulates epithelial fluid secretion.
G protein-coupled receptor 35 attenuates nonalcoholic steatohepatitis by reprogramming cholesterol homeostasis in hepatocytes.
Early infiltration of innate immune cells to the liver depletes HNF4a and promotes extra-hepatic carcinogenesis.
Temporal inhibition of the electron transport chain attenuates stress-induced cellular senescence by prolonged disturbance of proteostasis in human fibroblasts.
Lipid rafts, Rab GTPases, and a late endosomal checkpoint for plasma membrane recycling.
Enhanced Ca2+-channeling complex formation at the ER-mitochondria interface underlies the pathogenesis of alcohol-associated liver disease.
Membrane phospholipid remodeling modulates nonalcoholic steatohepatitis progression by regulating mitochondrial homeostasis.
Phagocytosis increases an oxidative metabolic and immune suppressive signature in tumor macrophages.
FASN-deficiency induces a cytosol-to-mitochondria citrate flux to mitigate detachment-induced oxidative stress.
Resting natural killer cell homeostasis relies on tryptophan/NAD+ metabolism and HIF-1α.
Primitive haematopoiesis in the human placenta gives rise to macrophages with epigenetically silenced HLA-DR.
SUCNR1 signaling in adipocytes controls energy metabolism by modulating circadian clock and leptin expression.
NAMPT-dependent NAD+ biosynthesis controls circadian metabolism in a tissue-specific manner.
Large neutral amino acid levels tune perinatal neuronal excitability and survival.
Age-dependent Pdgfrβ signaling drives adipocyte progenitor dysfunction to alter the beige adipogenic niche in male mice.
A neutrophil response linked to tumor control in immunotherapy.
Human inherited complete STAT2 deficiency underlies inflammatory viral diseases.
TFEB-dependent lysosome biogenesis is required for senescence.
PI(4,5)P2-dependent regulation of endothelial tip cell specification contributes to angiogenesis.

Metabolites. 2023 Feb 23. pii: 331. [Epub ahead of print]13(3):

Mapping the Metabolic Niche of Citrate Metabolism and SLC13A5.

Fangfang Chen, Hanna Friederike Willenbockel, Thekla Cordes.

  The small molecule citrate is a key molecule that is synthesized de novo and involved in diverse biochemical pathways influencing cell metabolism and function. Citrate is highly abundant in the circulation, and cells take up extracellular citrate via the sodium-dependent plasma membrane transporter NaCT encoded by the SLC13A5 gene. Citrate is critical to maintaining metabolic homeostasis and impaired NaCT activity is implicated in metabolic disorders. Though citrate is one of the best known and most studied metabolites in humans, little is known about the consequences of altered citrate uptake and metabolism. Here, we review recent findings on SLC13A5, NaCT, and citrate metabolism and discuss the effects on metabolic homeostasis and SLC13A5-dependent phenotypes. We discuss the "multiple-hit theory" and how stress factors induce metabolic reprogramming that may synergize with impaired NaCT activity to alter cell fate and function. Furthermore, we underline how citrate metabolism and compartmentalization can be quantified by combining mass spectrometry and tracing approaches. We also discuss species-specific differences and potential therapeutic implications of SLC13A5 and NaCT. Understanding the synergistic impact of multiple stress factors on citrate metabolism may help to decipher the disease mechanisms associated with SLC13A5 citrate transport disorders.

Keywords:  NaCT; SLC13A5; TCA cycle; citrate metabolism; citrate transport; compartmentalization; mass spectrometry; metabolic niche; mitochondria; tracing

DOI:  https://doi.org/10.3390/metabo13030331
Cell Rep. 2023 Mar 31. pii: S2211-1247(23)00343-1. [Epub ahead of print]42(4): 112332

The mitochondrial protease OMA1 acts as a metabolic safeguard upon nuclear DNA damage.

Pablo Rivera-Mejías, Álvaro Jesús Narbona-Pérez, Lidwina Hasberg, Lara Kroczek, Amir Bahat, Steffen Lawo, Kat Folz-Donahue, Anna-Lena Schumacher, Sofia Ahola, Fiona Carola Mayer, Patrick Giavalisco, Hendrik Nolte, Sergio Lavandero, Thomas Langer.

  The metabolic plasticity of mitochondria ensures cell development, differentiation, and survival. The peptidase OMA1 regulates mitochondrial morphology via OPA1 and stress signaling via DELE1 and orchestrates tumorigenesis and cell survival in a cell- and tissue-specific manner. Here, we use unbiased systems-based approaches to show that OMA1-dependent cell survival depends on metabolic cues. A metabolism-focused CRISPR screen combined with an integrated analysis of human gene expression data found that OMA1 protects against DNA damage. Nucleotide deficiencies induced by chemotherapeutic agents promote p53-dependent apoptosis of cells lacking OMA1. The protective effect of OMA1 does not depend on OMA1 activation or OMA1-mediated OPA1 and DELE1 processing. OMA1-deficient cells show reduced glycolysis and accumulate oxidative phosphorylation (OXPHOS) proteins upon DNA damage. OXPHOS inhibition restores glycolysis and confers resistance against DNA damage. Thus, OMA1 dictates the balance between cell death and survival through the control of glucose metabolism, shedding light on its role in cancerogenesis.

Keywords:  CP: Metabolism; DNA damage; OMA1; OXPHOS; glucose metabolism; mitochondria; nucleotides; p53

DOI:  https://doi.org/10.1016/j.celrep.2023.112332
Am J Physiol Endocrinol Metab. 2023 Mar 29.

Defective Muscle Ketone Body Oxidation Disrupts BCAA Catabolism by Altering Mitochondrial Branched-Chain Aminotransferase.

Hamza Mechchate, Abdualrahman Mohammed Abdualkader, James Bradshaw Bernacchi, Keshav Gopal, S Amirhossein Tabatabaei Dakhili, Kunyan Yang, Amanda A Greenwell, Xingxing Kong, Peter A Crawford, Rami Al Batran.

  Ketone bodies are an endogenous fuel source generated primarily by the liver to provide alternative energy for extrahepatic tissues during prolonged fasting and exercise. Skeletal muscle is an important site of ketone body oxidation which occurs through a series of reactions requiring the enzyme succinyl-CoA:3-ketoacid-CoA transferase (SCOT/Oxct1). We have previously shown that deleting SCOT in the skeletal muscle protects against obesity-induced insulin resistance by increasing pyruvate dehydrogenase (PDH) activity, the rate-limiting enzyme of glucose oxidation. However, it remains unclear whether inhibiting muscle ketone body oxidation causes hypoglycemia and affects fuel metabolism in the absence of obesity. Here, we show that lean mice lacking skeletal muscle SCOT (SCOTSkM-/-) exhibited no overt phenotypic differences in glucose and fat metabolism from their human α-skeletal actin-Cre (HSACre) littermates. Of interest, we found that plasma and muscle branched-chain amino acid (BCAA) levels are elevated in SCOTSkM-/- lean mice compared to their HSACre littermates. Interestingly, this alteration in BCAA catabolism was only seen in SCOTSkM-/- mice under low-fat feeding and associated with decreased expression of mitochondrial branched-chain aminotransferases (BCATm/Bcat2), the first enzyme in BCAA catabolic pathway. Loss- and gain-of-function studies in C2C12 myotubes demonstrated that suppressing SCOT markedly diminished BCATm expression, whereas overexpressing SCOT resulted in an opposite effect without influencing BCAA oxidation enzymes. Further, SCOT overexpression in C2C12 myotubes significantly increased luciferase activity driven by a Bcat2 promoter construct. Together, our findings indicate that SCOT regulates the expression of the Bcat2 gene, which, through the abundance of its product BCATm, may influence circulating BCAA concentrations.

Keywords:  BCAAs; BCATm; Ketone body; SCOT; Skeletal Muscle

DOI:  https://doi.org/10.1152/ajpendo.00206.2022
Immunol Rev. 2023 Mar 31.

Decoding the crosstalk between mevalonate metabolism and T cell function.

Kelly T Kennewick, Steven J Bensinger.

  The mevalonate pathway is an essential metabolic pathway in T cells regulating development, proliferation, survival, differentiation, and effector functions. The mevalonate pathway is a complex, branched pathway composed of many enzymes that ultimately generate cholesterol and nonsterol isoprenoids. T cells must tightly control metabolic flux through the branches of the mevalonate pathway to ensure sufficient isoprenoids and cholesterol are available to meet cellular demands. Unbalanced metabolite flux through the sterol or the nonsterol isoprenoid branch is metabolically inefficient and can have deleterious consequences for T cell fate and function. Accordingly, there is tight regulatory control over metabolic flux through the branches of this essential lipid synthetic pathway. In this review we provide an overview of how the branches of the mevalonate pathway are regulated in T cells and discuss our current understanding of the relationship between mevalonate metabolism, cholesterol homeostasis and T cell function.

Keywords:  T cells; cholesterol; isoprenoids; mevalonate pathway; statins

DOI:  https://doi.org/10.1111/imr.13200
bioRxiv. 2023 Mar 15. pii: 2023.03.14.532663. [Epub ahead of print]

Immunogenetic metabolomics revealed key enzymes that modulate CAR-T metabolism and function.

Paul Renauer, Jonathan J Park, Meizhu Bai, Arianny Acosta, Won-Ho Lee, Guang Han Lin, Yueqi Zhang, Xiaoyun Dai, Guangchuan Wang, Youssef Errami, Terence Wu, Paul Clark, Lupeng Ye, Quanjun Yang, Sidi Chen.

Immune evasion is a critical step of cancer progression that remains a major obstacle for current T cell-based immunotherapies. Hence, we seek to genetically reprogram T cells to exploit a common tumor-intrinsic evasion mechanism, whereby cancer cells suppress T cell function by generating a metabolically unfavorable tumor microenvironment (TME). Specifically, we use an in silico screen to identify ADA and PDK1 as metabolic regulators, in which gene overexpression (OE) enhances the cytolysis of CD19-specific CD8 CAR-T cells against cognate leukemia cells, and conversely, ADA or PDK1 deficiency dampens such effect. ADA -OE in CAR-T cells improves cancer cytolysis under high concentrations of adenosine, the ADA substrate and an immunosuppressive metabolite in the TME. High-throughput transcriptomics and metabolomics in these CAR-Ts reveal alterations of global gene expression and metabolic signatures in both ADA- and PDK1- engineered CAR-T cells. Functional and immunological analyses demonstrate that ADA -OE increases proliferation and decreases exhaustion in α-CD19 and α-HER2 CAR-T cells. ADA-OE improves tumor infiltration and clearance by α-HER2 CAR-T cells in an in vivo colorectal cancer model. Collectively, these data unveil systematic knowledge of metabolic reprogramming directly in CAR-T cells, and reveal potential targets for improving CAR-T based cell therapy.
Synopsis: The authors identify the adenosine deaminase gene (ADA) as a regulatory gene that reprograms T cell metabolism. ADA-overexpression (OE) in α-CD19 and α-HER2 CAR-T cells increases proliferation, cytotoxicity, memory, and decreases exhaustion, and ADA-OE α-HER2 CAR-T cells have enhanced clearance of HT29 human colorectal cancer tumors in vivo .

DOI: https://doi.org/10.1101/2023.03.14.532663
Nature. 2023 Mar 29.

Ornithine aminotransferase supports polyamine synthesis in pancreatic cancer.

Min-Sik Lee, Courtney Dennis, Insia Naqvi, Lucas Dailey, Alireza Lorzadeh, George Ye, Tamara Zaytouni, Ashley Adler, Daniel S Hitchcock, Lin Lin, Megan T Hoffman, Aladdin M Bhuiyan, Jaimie L Barth, Miranda E Machacek, Mari Mino-Kenudson, Stephanie K Dougan, Unmesh Jadhav, Clary B Clish, Nada Y Kalaany.

There is a need to develop effective therapies for pancreatic ductal adenocarcinoma (PDA), a highly lethal malignancy with increasing incidence1 and poor prognosis2. Although targeting tumour metabolism has been the focus of intense investigation for more than a decade, tumour metabolic plasticity and high risk of toxicity have limited this anticancer strategy3,4. Here we use genetic and pharmacological approaches in human and mouse in vitro and in vivo models to show that PDA has a distinct dependence on de novo ornithine synthesis from glutamine. We find that this process, which is mediated through ornithine aminotransferase (OAT), supports polyamine synthesis and is required for tumour growth. This directional OAT activity is usually largely restricted to infancy and contrasts with the reliance of most adult normal tissues and other cancer types on arginine-derived ornithine for polyamine synthesis5,6. This dependency associates with arginine depletion in the PDA tumour microenvironment and is driven by mutant KRAS. Activated KRAS induces the expression of OAT and polyamine synthesis enzymes, leading to alterations in the transcriptome and open chromatin landscape in PDA tumour cells. The distinct dependence of PDA, but not normal tissue, on OAT-mediated de novo ornithine synthesis provides an attractive therapeutic window for treating patients with pancreatic cancer with minimal toxicity.

DOI: https://doi.org/10.1038/s41586-023-05891-2
Cell Mol Neurobiol. 2023 Mar 29.

Ferroptosis and Neurodegenerative Diseases: Insights into the Regulatory Roles of SLC7A11.

Chen Wang, Haihui Liu, Si Xu, Yu Deng, Bin Xu, Tianyao Yang, Wei Liu.

  Programed cell death plays a key role in promoting human development and maintaining homeostasis. Ferroptosis is a recently identified pattern of programmed cell death that is closely associated with the onset and progression of neurodegenerative diseases. Ferroptosis is mainly caused by the intracellular accumulation of iron-dependent lipid peroxides. The cysteine/glutamate antibody Solute carrier family 7 member 11 (SLC7A11, also known as xCT) functions to import cysteine for glutathione biosynthesis and antioxidant defense. SLC7A11 has a significant impact on ferroptosis, and inhibition of SLC7A11 expression promotes ferroptosis. Moreover, SLC7A11 is also closely associated with neurodegenerative diseases. In this paper, we summarize the relationship between ferroptosis and neurodegenerative diseases and the role of SLC7A11 during this process. The various regulatory mechanisms of SLC7A11 are also discussed. In conclusion, we are looking forward to a theoretical basis for further understanding the occurrence and development of ferroptosis in SLC7A11 and neurodegenerative diseases, and to seek new clues for the treatment of neurodegenerative diseases.

Keywords:  Cysteine; Ferroptosis; Lipid peroxidation; Neurodegenerative diseases; SLC7A11; System Xc

DOI:  https://doi.org/10.1007/s10571-023-01343-7
Nitric Oxide. 2023 Mar 25. pii: S1089-8603(23)00031-9. [Epub ahead of print]134-135 17-22

NO binds to the distal site of haem in the fully activated soluble guanylate cyclase.

Rui Liu, Yunlu Kang, Lei Chen.

  Soluble guanylate cyclase (sGC) is the primary receptor for nitric oxide (NO). The binding of NO to the haem of sGC induces a large conformational change in the enzyme and activates its cyclase activity. However, whether NO binds to the proximal site or the distal site of haem in the fully activated state remains under debate. Here, we present cryo-EM maps of sGC in the NO-activated state at high resolutions, allowing the observation of the density of NO. These cryo-EM maps show the binding of NO to the distal site of haem in the NO-activated state.

Keywords:  Haem; Nitric oxide; cGMP; sGC

DOI:  https://doi.org/10.1016/j.niox.2023.03.002
Antioxid Redox Signal. 2023 Mar 27.

Dynamic regulation of ferroptosis by lipid metabolism.

Yilong Zou, Nathchar Naowarojna, Tianshu William Wu, Zijian Pan, Mengyu Li, Jingrong Regina Han.

SIGNIFICANCE: Ferroptosis is featured by the accumulation of polyunsaturated-lipid peroxidation on cellular membranes in an iron-dependent manner. Ferroptosis has been implicated in various pathophysiological processes including cancer, neurodegeneration, and ischemia-reperfusion tissue injury. However, our understanding about the dynamic and context-specific regulation of ferroptosis remains incomplete.
RECENT ADVANCES: As the major substrate for peroxidation, the cellular lipidome regulates ferroptosis sensitivity and execution by controlling the abundance and availability of polyunsaturated-lipids for peroxidative modifications. In turn, the cellular lipidome is regulated by a complex network of enzymes and transporters, as well as upstream layers of receptors, kinases and transcription factors. A number of research has shed light on the link between lipid metabolism and ferroptosis. Here we summarize our current knowledge on the role of the lipidome and associated protein regulators in various stages of ferroptosis, ranging from initiation, execution to cell death evasion by cells experiencing ferroptotic stress.
CRITICAL ISSUES: This review provides an overview of the mechanisms underlying lipid peroxidation and ferroptosis by discussing the lipid species that directly contribute to lipid peroxidation and ferroptosis, how cells regulate the abundances of these pro-ferroptosis lipids, how lipid peroxidation causes cell death, and how cells prevent and repair membrane lipid damage under ferroptotic conditions.
FUTURE DIRECTIONS: Cell fate regulation in vivo could be different from in vitro culture settings. We envision that a comprehensive and detailed understanding about these important questions in the dynamic regulation of ferroptosis in vivo will accelerate our development of ferroptosis-targeted therapies to improve human health.

DOI: https://doi.org/10.1089/ars.2023.0278
Nat Chem Biol. 2023 Mar 27.

Cytosolic and mitochondrial NADPH fluxes are independently regulated.

Xiangfeng Niu, Ethan Stancliffe, Susan J Gelman, Lingjue Wang, Michaela Schwaiger-Haber, Joe L Rowles, Leah P Shriver, Gary J Patti.

Although nicotinamide adenine dinucleotide phosphate (NADPH) is produced and consumed in both the cytosol and mitochondria, the relationship between NADPH fluxes in each compartment has been difficult to assess due to technological limitations. Here we introduce an approach to resolve cytosolic and mitochondrial NADPH fluxes that relies on tracing deuterium from glucose to metabolites of proline biosynthesis localized to either the cytosol or mitochondria. We introduced NADPH challenges in either the cytosol or mitochondria of cells by using isocitrate dehydrogenase mutations, administering chemotherapeutics or with genetically encoded NADPH oxidase. We found that cytosolic challenges influenced NADPH fluxes in the cytosol but not NADPH fluxes in mitochondria, and vice versa. This work highlights the value of using proline labeling as a reporter system to study compartmentalized metabolism and reveals that NADPH homeostasis in the cytosolic and mitochondrial locations of a cell are independently regulated, with no evidence for NADPH shuttle activity.

DOI: https://doi.org/10.1038/s41589-023-01283-9
Metabolites. 2023 Mar 14. pii: 426. [Epub ahead of print]13(3):

Cross-Regulation of the Cellular Redox System, Oxygen, and Sphingolipid Signalling.

Andrea Huwiler, Karl-Friedrich Beck, Josef Pfeilschifter.

  Redox-active mediators are now appreciated as powerful molecules to regulate cellular dynamics such as viability, proliferation, migration, cell contraction, and relaxation, as well as gene expression under physiological and pathophysiological conditions. These molecules include the various reactive oxygen species (ROS), and the gasotransmitters nitric oxide (NO∙), carbon monoxide (CO), and hydrogen sulfide (H2S). For each of these molecules, direct targets have been identified which transmit the signal from the cellular redox state to a cellular response. Besides these redox mediators, various sphingolipid species have turned out as highly bioactive with strong signalling potential. Recent data suggest that there is a cross-regulation existing between the redox mediators and sphingolipid molecules that have a fundamental impact on a cell's fate and organ function. This review will summarize the effects of the different redox-active mediators on sphingolipid signalling and metabolism, and the impact of this cross-talk on pathophysiological processes. The relevance of therapeutic approaches will be highlighted.

Keywords:  hydrogen sulfide; hypoxia; nitric oxide; reactive oxygen species; redox; sphingolipids

DOI:  https://doi.org/10.3390/metabo13030426
Nat Commun. 2023 Mar 27. 14(1): 1685

Time-of-day defines NAD+ efficacy to treat diet-induced metabolic disease by synchronizing the hepatic clock in mice.

Quetzalcoatl Escalante-Covarrubias, Lucía Mendoza-Viveros, Mirna González-Suárez, Román Sitten-Olea, Laura A Velázquez-Villegas, Fernando Becerril-Pérez, Ignacio Pacheco-Bernal, Erick Carreño-Vázquez, Paola Mass-Sánchez, Marcia Bustamante-Zepeda, Ricardo Orozco-Solís, Lorena Aguilar-Arnal.

The circadian clock is an endogenous time-tracking system that anticipates daily environmental changes. Misalignment of the clock can cause obesity, which is accompanied by reduced levels of the clock-controlled, rhythmic metabolite NAD+. Increasing NAD+ is becoming a therapy for metabolic dysfunction; however, the impact of daily NAD+ fluctuations remains unknown. Here, we demonstrate that time-of-day determines the efficacy of NAD+ treatment for diet-induced metabolic disease in mice. Increasing NAD+ prior to the active phase in obese male mice ameliorated metabolic markers including body weight, glucose and insulin tolerance, hepatic inflammation and nutrient sensing pathways. However, raising NAD+ immediately before the rest phase selectively compromised these responses. Remarkably, timed NAD+ adjusted circadian oscillations of the liver clock until completely inverting its oscillatory phase when increased just before the rest period, resulting in misaligned molecular and behavioral rhythms in male and female mice. Our findings unveil the time-of-day dependence of NAD+-based therapies and support a chronobiology-based approach.

DOI: https://doi.org/10.1038/s41467-023-37286-2
Molecules. 2023 Mar 17. pii: 2712. [Epub ahead of print]28(6):

Mass Spectrometry Imaging for Single-Cell or Subcellular Lipidomics: A Review of Recent Advancements and Future Development.

Dan Li, Zheng Ouyang, Xiaoxiao Ma.

  Mass Spectrometry Imaging (MSI) has emerged as a powerful imaging technique for the analysis of biological samples, providing valuable insights into the spatial distribution and structural characterization of lipids. The advancements in high-resolution MSI have made it an indispensable tool for single-cell or subcellular lipidomics. By preserving both intracellular and intercellular information, MSI enables a comprehensive analysis of lipidomics in individual cells and organelles. This enables researchers to delve deeper into the diversity of lipids within cells and to understand the role of lipids in shaping cell behavior. In this review, we aim to provide a comprehensive overview of recent advancements and future prospects of MSI for cellular/subcellular lipidomics. By keeping abreast of the cutting-edge studies in this field, we will continue to push the boundaries of the understanding of lipid metabolism and the impact of lipids on cellular behavior.

Keywords:  data analysis; deep learning; lipidomics; mass spectrometry imaging; matrix-assisted laser desorption ionization (MALDI); multimodal imaging; organelle; secondary ion mass spectrometry (SIMS); single-cell

DOI:  https://doi.org/10.3390/molecules28062712
bioRxiv. 2023 Mar 22. pii: 2023.03.17.533208. [Epub ahead of print]

Tuft cell-derived acetylcholine regulates epithelial fluid secretion.

Tyler E Billipp, Connie Fung, Lily M Webeck, Derek B Sargent, Matthew B Gologorsky, Margaret M McDaniel, Darshan N Kasal, John W McGinty, Kaitlyn A Barrow, Lucille M Rich, Alessio Barilli, Mark Sabat, Jason S Debley, Richard Myers, Michael R Howitt, Jakob von Moltke.

Tuft cells are solitary chemosensory epithelial cells that can sense lumenal stimuli at mucosal barriers and secrete effector molecules to regulate the physiology and immune state of their surrounding tissue. In the small intestine, tuft cells detect parasitic worms (helminths) and microbe-derived succinate, and signal to immune cells to trigger a Type 2 immune response that leads to extensive epithelial remodeling spanning several days. Acetylcholine (ACh) from airway tuft cells has been shown to stimulate acute changes in breathing and mucocilliary clearance, but its function in the intestine is unknown. Here we show that tuft cell chemosensing in the intestine leads to release of ACh, but that this does not contribute to immune cell activation or associated tissue remodeling. Instead, tuft cell-derived ACh triggers immediate fluid secretion from neighboring epithelial cells into the intestinal lumen. This tuft cell-regulated fluid secretion is amplified during Type 2 inflammation, and helminth clearance is delayed in mice lacking tuft cell ACh. The coupling of the chemosensory function of tuft cells with fluid secretion creates an epithelium-intrinsic response unit that effects a physiological change within seconds of activation. This response mechanism is shared by tuft cells across tissues, and serves to regulate the epithelial secretion that is both a hallmark of Type 2 immunity and an essential component of homeostatic maintenance at mucosal barriers.

DOI: https://doi.org/10.1101/2023.03.17.533208
Acta Pharm Sin B. 2023 Mar;13(3): 1128-1144

G protein-coupled receptor 35 attenuates nonalcoholic steatohepatitis by reprogramming cholesterol homeostasis in hepatocytes.

Xiaoli Wei, Fan Yin, Miaomiao Wu, Qianqian Xie, Xueqin Zhao, Cheng Zhu, Ruiqian Xie, Chongqing Chen, Menghua Liu, Xueying Wang, Ruixue Ren, Guijie Kang, Chenwen Zhu, Jingjing Cong, Hua Wang, Xuefu Wang.

  Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Fat accumulation "sensitizes" the liver to insult and leads to nonalcoholic steatohepatitis (NASH). G protein-coupled receptor 35 (GPR35) is involved in metabolic stresses, but its role in NAFLD is unknown. We report that hepatocyte GPR35 mitigates NASH by regulating hepatic cholesterol homeostasis. Specifically, we found that GPR35 overexpression in hepatocytes protected against high-fat/cholesterol/fructose (HFCF) diet-induced steatohepatitis, whereas loss of GPR35 had the opposite effect. Administration of the GPR35 agonist kynurenic acid (Kyna) suppressed HFCF diet-induced steatohepatitis in mice. Kyna/GPR35 induced expression of StAR-related lipid transfer protein 4 (STARD4) through the ERK1/2 signaling pathway, ultimately resulting in hepatic cholesterol esterification and bile acid synthesis (BAS). The overexpression of STARD4 increased the expression of the BAS rate-limiting enzymes cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and CYP8B1, promoting the conversion of cholesterol to bile acid. The protective effect induced by GPR35 overexpression in hepatocytes disappeared in hepatocyte STARD4-knockdown mice. STARD4 overexpression in hepatocytes reversed the aggravation of HFCF diet-induced steatohepatitis caused by the loss of GPR35 expression in hepatocytes in mice. Our findings indicate that the GPR35-STARD4 axis is a promising therapeutic target for NAFLD.

Keywords:  ACAT2; Bile acid; CYP7A1; Cholesterol; G protein-coupled receptor 35; Kynurenic acid; STARD4; Steatohepatitis

DOI:  https://doi.org/10.1016/j.apsb.2022.10.011
Cancer Discov. 2023 Mar 27. pii: CD-22-1062. [Epub ahead of print]

Early infiltration of innate immune cells to the liver depletes HNF4a and promotes extra-hepatic carcinogenesis.

Omer Goldman, Lital N Adler, Emma Hajaj, Tommaso Croese, Naama Darzi, Sivan Galai, Hila Tishler, Yarden Ariav, Dor Lavie, Liat Fellus-Alyagor, Roni Oren, Yuri Kuznetsov, Eyal David, Rami Jaschek, Chani Stossel, Oded Singer, Sergey Malitsky, Renana Barak, Rony Seger, Neta Erez, Ido Amit, Amos Tanay, Ann Saada, Talia Golan, Tamar Rubinek, Joo Sang Lee, Shay Ben-Shachar, Ido Wolf, Ayelet Erez.

Multiple studies identified metabolic changes within the tumor and its microenvironment during carcinogenesis. Yet, the mechanisms by which tumors affect the host metabolism are unclear. We find that systemic inflammation induced by the cancer leads to liver infiltration of myeloid cells at early extrahepatic carcinogenesis. The infiltrating immune cells via IL-6-pSTAT3 immune-hepatocyte crosstalk cause the depletion of a master metabolic regulator, HNF4a, consequently leading to systemic metabolic changes that promote breast and pancreatic cancer proliferation and a worse outcome. Preserving HNF4 levels maintains liver metabolism and restricts carcinogenesis. Standard liver biochemical tests can identify early metabolic changes and predict patients' outcomes and weight loss. Thus, the tumor induces early metabolic changes in its macro-environment with diagnostic and potentially therapeutic implications for the host.

DOI: https://doi.org/10.1158/2159-8290.CD-22-1062
FEBS J. 2023 Apr 01.

Temporal inhibition of the electron transport chain attenuates stress-induced cellular senescence by prolonged disturbance of proteostasis in human fibroblasts.

Yasuhiro Takenaka, Ikuo Inoue, Masataka Hirasaki, Masaaki Ikeda, Yoshihiko Kakinuma.

  We previously developed a stress-induced premature senescence (SIPS) model in which normal human fibroblast MRC-5 cells were treated with either the proteasome inhibitor MG132 or the vacuolar-type ATPase (V-ATPase) inhibitor bafilomycin A1 (BAFA1). To clarify the involvement of mitochondrial function in our SIPS model, MRC-5 cells were treated with MG132 or BAFA1 along with an inhibitor targeting either the electron transport chain (ETC) complex I or complex III, or with a mitochondrial uncoupler. SIPS induced by MG132 or BAFA1 was significantly attenuated by short-term co-treatment with the complex III inhibitor, antimycin A (AA), but not the complex I inhibitor, rotenone, or the mitochondrial uncoupler, carbonyl cyanide 3-chlorophenylhydrazone (CCCP). By co-treatment with AA, mitochondrial and intracellular reactive oxygen species (ROS) levels, accumulation of protein aggregates, and mitochondrial unfolded protein responses (UPRmt ) were remarkably suppressed. Furthermore, AA co-treatment suppressed the hyperpolarization of the mitochondrial membrane and the induction of mitophagy observed in MG132-treated cells, and enhanced mitochondrial biogenesis. These findings provide evidence that the temporal inhibition of mitochondrial respiration exerts protective effects against the progression of premature senescence caused by impaired proteostasis.

Keywords:  MG132; mitochondria; oxidative phosphorylation; proteostasis; senescence; unfolded protein response

DOI:  https://doi.org/10.1111/febs.16785
Proc Natl Acad Sci U S A. 2023 Apr 04. 120(14): e2302320120

Lipid rafts, Rab GTPases, and a late endosomal checkpoint for plasma membrane recycling.

Ilsa-Maria Daumann, P Robin Hiesinger.

DOI: https://doi.org/10.1073/pnas.2302320120
Nat Commun. 2023 Mar 27. 14(1): 1703

Enhanced Ca2+-channeling complex formation at the ER-mitochondria interface underlies the pathogenesis of alcohol-associated liver disease.

Themis Thoudam, Dipanjan Chanda, Jung Yi Lee, Min-Kyo Jung, Ibotombi Singh Sinam, Byung-Gyu Kim, Bo-Yoon Park, Woong Hee Kwon, Hyo-Jeong Kim, Myeongjin Kim, Chae Won Lim, Hoyul Lee, Yang Hoon Huh, Caroline A Miller, Romil Saxena, Nicholas J Skill, Nazmul Huda, Praveen Kusumanchi, Jing Ma, Zhihong Yang, Min-Ji Kim, Ji Young Mun, Robert A Harris, Jae-Han Jeon, Suthat Liangpunsakul, In-Kyu Lee.

Ca2+ overload-induced mitochondrial dysfunction is considered as a major contributing factor in the pathogenesis of alcohol-associated liver disease (ALD). However, the initiating factors that drive mitochondrial Ca2+ accumulation in ALD remain elusive. Here, we demonstrate that an aberrant increase in hepatic GRP75-mediated mitochondria-associated ER membrane (MAM) Ca2+-channeling (MCC) complex formation promotes mitochondrial dysfunction in vitro and in male mouse model of ALD. Unbiased transcriptomic analysis reveals PDK4 as a prominently inducible MAM kinase in ALD. Analysis of human ALD cohorts further corroborate these findings. Additional mass spectrometry analysis unveils GRP75 as a downstream phosphorylation target of PDK4. Conversely, non-phosphorylatable GRP75 mutation or genetic ablation of PDK4 prevents alcohol-induced MCC complex formation and subsequent mitochondrial Ca2+ accumulation and dysfunction. Finally, ectopic induction of MAM formation reverses the protective effect of PDK4 deficiency in alcohol-induced liver injury. Together, our study defines a mediatory role of PDK4 in promoting mitochondrial dysfunction in ALD.

DOI: https://doi.org/10.1038/s41467-023-37214-4
Hepatology. 2023 Apr 03.

Membrane phospholipid remodeling modulates nonalcoholic steatohepatitis progression by regulating mitochondrial homeostasis.

Ye Tian, Matthew J Jellinek, Kritika Mehta, Sun Mi Seok, Shanny Hsuan Kuo, Wei Lu, Ruicheng Shi, Richard Lee, Gee W Lau, Jongsook Kim Kemper, Kai Zhang, David A Ford, Bo Wang.

BACKGROUND AIMS: Nonalcoholic steatohepatitis (NASH), characterized by inflammation and fibrosis, is emerging as a leading etiology of hepatocellular carcinoma (HCC). Lipidomics analyses in the liver have shown that the levels of polyunsaturated phosphatidylcholine (PC) are decreased in NASH patients, but the roles of membrane PC composition in the pathogenesis of NASH has not been investigated. Lysophosphatidylcholine acyltransferase 3 (LPCAT3), a phospholipid (PL) remodeling enzyme that produces polyunsaturated PLs, is a major determinant of membrane PC content in the liver.
APPROACH RESULTS: The expression of LPCAT3 and the correlation between its expression and NASH severity were analyzed in human patient samples. We examined the effect of Lpcat3 deficiency on NASH progression using Lpcat3 liver specific knockout mice (LKO). RNA sequencing, lipidomics, and metabolomics were performed in liver samples. Primary hepatocytes and hepatic cell lines were used for in vitro analyses. We show that LPCAT3 is dramatically suppressed in human NASH livers, and its expression is inversely correlated with NAFLD activity score and fibrosis stage. Loss of Lpcat3 in mouse liver promotes both spontaneous and diet-induced NASH/HCC. Mechanistically, Lpcat3 deficiency enhances reactive oxygen species production due to impaired mitochondrial homeostasis. Loss of Lpcat3 increases inner mitochondrial membrane PL saturation and elevates stress-induced autophagy, resulting in reduced mitochondrial content and increased fragmentation. Furthermore, overexpressing Lpcat3 in the liver ameliorates inflammation and fibrosis of NASH.
CONCLUSIONS: These results demonstrate that membrane PL composition modulates the progression of NASH and that manipulating LPCAT3 expression could be an effective therapeutic for NASH.

DOI: https://doi.org/10.1097/HEP.0000000000000375
J Exp Med. 2023 Jun 05. pii: e20221472. [Epub ahead of print]220(6):

Phagocytosis increases an oxidative metabolic and immune suppressive signature in tumor macrophages.

Michael A Gonzalez, Daniel R Lu, Maryam Yousefi, Ashley Kroll, Chen Hao Lo, Carlos G Briseño, J E Vivienne Watson, Sergey Novitskiy, Vanessa Arias, Hong Zhou, Andres Plata Stapper, Min K Tsai, Emily L Ashkin, Christopher W Murray, Chi-Ming Li, Monte M Winslow, Kristin V Tarbell.

Phagocytosis is a key macrophage function, but how phagocytosis shapes tumor-associated macrophage (TAM) phenotypes and heterogeneity in solid tumors remains unclear. Here, we utilized both syngeneic and novel autochthonous lung tumor models in which neoplastic cells express the fluorophore tdTomato (tdTom) to identify TAMs that have phagocytosed neoplastic cells in vivo. Phagocytic tdTompos TAMs upregulated antigen presentation and anti-inflammatory proteins, but downregulated classic proinflammatory effectors compared to tdTomneg TAMs. Single-cell transcriptomic profiling identified TAM subset-specific and common gene expression changes associated with phagocytosis. We uncover a phagocytic signature that is predominated by oxidative phosphorylation (OXPHOS), ribosomal, and metabolic genes, and this signature correlates with worse clinical outcome in human lung cancer. Expression of OXPHOS proteins, mitochondrial content, and functional utilization of OXPHOS were increased in tdTompos TAMs. tdTompos tumor dendritic cells also display similar metabolic changes. Our identification of phagocytic TAMs as a distinct myeloid cell state links phagocytosis of neoplastic cells in vivo with OXPHOS and tumor-promoting phenotypes.

DOI: https://doi.org/10.1084/jem.20221472
bioRxiv. 2023 Mar 15. pii: 2023.03.14.532533. [Epub ahead of print]

FASN-deficiency induces a cytosol-to-mitochondria citrate flux to mitigate detachment-induced oxidative stress.

Wenting Dai, Zhichao Wang, Guan Wang, Qiong A Wang, Ralph DeBerardinis, Lei Jiang.

Fatty acid synthase (FASN) maintains de novo lipogenesis (DNL) to support rapid growth in most proliferating cancer cells. Lipogenic acetyl-CoA is primarily produced from carbohydrates but can arise from glutamine-dependent reductive carboxylation under hypoxia. Here we show that reductive carboxylation also occurs in the absence of DNL in cells with defective FASN. In this state, reductive carboxylation was mainly catalyzed by isocitrate dehydrogenase-1 (IDH1) in the cytosol, but IDH1-generated citrate was not used for DNL. Metabolic flux analysis (MFA) revealed that FASN-deficiency induced a net cytosol-to-mitochondria citrate flux through citrate transport protein (CTP). A similar pathway was previously shown to mitigate detachment-induced mitochondrial reactive oxygen species (mtROS) in anchorage-independent tumor spheroids. We further demonstrate that FASN-deficient cells acquire resistance to oxidative stress in a CTP- and IDH1-dependent manner. Together with the reduced FASN activity in tumor spheroids, these data indicate that anchorage-independent malignant cells trade FASN-supported rapid growth for a cytosol-to-mitochondria citrate flux to gain redox capacity against detachment-induced oxidative stress.

DOI: https://doi.org/10.1101/2023.03.14.532533
EMBO Rep. 2023 Mar 29. e56156

Resting natural killer cell homeostasis relies on tryptophan/NAD+ metabolism and HIF-1α.

Abigaelle Pelletier, Eric Nelius, Zheng Fan, Ekaterina Khatchatourova, Abdiel Alvarado-Diaz, Jingyi He, Ewelina Krzywinska, Michal Sobecki, Shunmugam Nagarajan, Yann Kerdiles, Joachim Fandrey, Dagmar Gotthardt, Veronika Sexl, Katrien de Bock, Christian Stockmann.

  Natural killer (NK) cells are forced to cope with different oxygen environments even under resting conditions. The adaptation to low oxygen is regulated by oxygen-sensitive transcription factors, the hypoxia-inducible factors (HIFs). The function of HIFs for NK cell activation and metabolic rewiring remains controversial. Activated NK cells are predominantly glycolytic, but the metabolic programs that ensure the maintenance of resting NK cells are enigmatic. By combining in situ metabolomic and transcriptomic analyses in resting murine NK cells, our study defines HIF-1α as a regulator of tryptophan metabolism and cellular nicotinamide adenine dinucleotide (NAD+ ) levels. The HIF-1α/NAD+ axis prevents ROS production during oxidative phosphorylation (OxPhos) and thereby blocks DNA damage and NK cell apoptosis under steady-state conditions. In contrast, in activated NK cells under hypoxia, HIF-1α is required for glycolysis, and forced HIF-1α expression boosts glycolysis and NK cell performance in vitro and in vivo. Our data highlight two distinct pathways by which HIF-1α interferes with NK cell metabolism. While HIF-1α-driven glycolysis is essential for NK cell activation, resting NK cell homeostasis relies on HIF-1α-dependent tryptophan/NAD+ metabolism.

Keywords:  HIF; immunometabolism; natural killer cells; nicotinamide adenine dinucleotide; tryptophan

DOI:  https://doi.org/10.15252/embr.202256156
Nat Commun. 2023 Mar 30. 14(1): 1764

Primitive haematopoiesis in the human placenta gives rise to macrophages with epigenetically silenced HLA-DR.

Jake R Thomas, Anna Appios, Emily F Calderbank, Nagisa Yoshida, Xiaohui Zhao, Russell S Hamilton, Ashley Moffett, Andrew Sharkey, Elisa Laurenti, Courtney W Hanna, Naomi McGovern.

The earliest macrophages are generated during embryonic development from erythro-myeloid progenitors (EMPs) via primitive haematopoiesis. Although this process is thought to be spatially restricted to the yolk sac in the mouse, in humans, it remains poorly understood. Human foetal placental macrophages, or Hofbauer cells (HBC), arise during the primitive haematopoietic wave ~18 days post conception and lack expression of human leukocyte antigen (HLA) class II. Here, we identify a population of placental erythro-myeloid progenitors (PEMPs) in the early human placenta that have conserved features of primitive yolk sac EMPs, including the lack of HLF expression. Using in vitro culture experiments we demonstrate that PEMP generate HBC-like cells lacking HLA-DR expression. We find the absence of HLA-DR in primitive macrophages is mediated via epigenetic silencing of class II transactivator, CIITA, the master regulator of HLA class II gene expression. These findings establish the human placenta as an additional site of primitive haematopoiesis.

DOI: https://doi.org/10.1038/s41467-023-37383-2
Cell Metab. 2023 Mar 21. pii: S1550-4131(23)00082-7. [Epub ahead of print]

SUCNR1 signaling in adipocytes controls energy metabolism by modulating circadian clock and leptin expression.

Teresa Villanueva-Carmona, Lídia Cedó, Ana Madeira, Victòria Ceperuelo-Mallafré, M-Mar Rodríguez-Peña, Catalina Núñez-Roa, Elsa Maymó-Masip, Maria Repollés-de-Dalmau, Joan Badia, Noelia Keiran, Mercedes Mirasierra, Carolina Pimenta-Lopes, Joan Sabadell-Basallote, Ramón Bosch, Laura Caubet, Joan Carles Escolà-Gil, José-Manuel Fernández-Real, Nuria Vilarrasa, Francesc Ventura, Mario Vallejo, Joan Vendrell, Sonia Fernández-Veledo.

  Adipose tissue modulates energy homeostasis by secreting leptin, but little is known about the factors governing leptin production. We show that succinate, long perceived as a mediator of immune response and lipolysis, controls leptin expression via its receptor SUCNR1. Adipocyte-specific deletion of Sucnr1 influences metabolic health according to nutritional status. Adipocyte Sucnr1 deficiency impairs leptin response to feeding, whereas oral succinate mimics nutrient-related leptin dynamics via SUCNR1. SUCNR1 activation controls leptin expression via the circadian clock in an AMPK/JNK-C/EBPα-dependent manner. Although the anti-lipolytic role of SUCNR1 prevails in obesity, its function as a regulator of leptin signaling contributes to the metabolically favorable phenotype in adipocyte-specific Sucnr1 knockout mice under standard dietary conditions. Obesity-associated hyperleptinemia in humans is linked to SUCNR1 overexpression in adipocytes, which emerges as the major predictor of adipose tissue leptin expression. Our study establishes the succinate/SUCNR1 axis as a metabolite-sensing pathway mediating nutrient-related leptin dynamics to control whole-body homeostasis.

Keywords:  GPCR; SUCNR1; adipocyte; adipose tissue; circadian clock; leptin; metabolism; metabolite; obesity; succinate

DOI:  https://doi.org/10.1016/j.cmet.2023.03.004
Proc Natl Acad Sci U S A. 2023 Apr 04. 120(14): e2220102120

NAMPT-dependent NAD+ biosynthesis controls circadian metabolism in a tissue-specific manner.

Astrid L Basse, Karen N Nielsen, Iuliia Karavaeva, Lars R Ingerslev, Tao Ma, Jesper F Havelund, Thomas S Nielsen, Mikkel Frost, Julia Peics, Emilie Dalbram, Morten Dall, Juleen R Zierath, Romain Barrès, Nils J Færgeman, Jonas T Treebak, Zachary Gerhart-Hines.

  Molecular clocks in the periphery coordinate tissue-specific daily biorhythms by integrating input from the hypothalamic master clock and intracellular metabolic signals. One such key metabolic signal is the cellular concentration of NAD+, which oscillates along with its biosynthetic enzyme, nicotinamide phosphoribosyltransferase (NAMPT). NAD+ levels feed back into the clock to influence rhythmicity of biological functions, yet whether this metabolic fine-tuning occurs ubiquitously across cell types and is a core clock feature is unknown. Here, we show that NAMPT-dependent control over the molecular clock varies substantially between tissues. Brown adipose tissue (BAT) requires NAMPT to sustain the amplitude of the core clock, whereas rhythmicity in white adipose tissue (WAT) is only moderately dependent on NAD+ biosynthesis, and the skeletal muscle clock is completely refractory to loss of NAMPT. In BAT and WAT, NAMPT differentially orchestrates oscillation of clock-controlled gene networks and the diurnality of metabolite levels. NAMPT coordinates the rhythmicity of TCA cycle intermediates in BAT, but not in WAT, and loss of NAD+ abolishes these oscillations similarly to high-fat diet-induced circadian disruption. Moreover, adipose NAMPT depletion improved the ability of animals to defend body temperature during cold stress but in a time-of-day-independent manner. Thus, our findings reveal that peripheral molecular clocks and metabolic biorhythms are shaped in a highly tissue-specific manner by NAMPT-dependent NAD+ synthesis.

Keywords:  Brown adipose tissue; Circadian metabolism; Clock rhythm; NAD; Skeletal muscle

DOI:  https://doi.org/10.1073/pnas.2220102120
Cell. 2023 Mar 24. pii: S0092-8674(23)00215-5. [Epub ahead of print]

Large neutral amino acid levels tune perinatal neuronal excitability and survival.

Lisa S Knaus, Bernadette Basilico, Daniel Malzl, Maria Gerykova Bujalkova, Mateja Smogavec, Lena A Schwarz, Sarah Gorkiewicz, Nicole Amberg, Florian M Pauler, Christian Knittl-Frank, Marianna Tassinari, Nuno Maulide, Thomas Rülicke, Jörg Menche, Simon Hippenmeyer, Gaia Novarino.

  Little is known about the critical metabolic changes that neural cells have to undergo during development and how temporary shifts in this program can influence brain circuitries and behavior. Inspired by the discovery that mutations in SLC7A5, a transporter of metabolically essential large neutral amino acids (LNAAs), lead to autism, we employed metabolomic profiling to study the metabolic states of the cerebral cortex across different developmental stages. We found that the forebrain undergoes significant metabolic remodeling throughout development, with certain groups of metabolites showing stage-specific changes, but what are the consequences of perturbing this metabolic program? By manipulating Slc7a5 expression in neural cells, we found that the metabolism of LNAAs and lipids are interconnected in the cortex. Deletion of Slc7a5 in neurons affects the postnatal metabolic state, leading to a shift in lipid metabolism. Additionally, it causes stage- and cell-type-specific alterations in neuronal activity patterns, resulting in a long-term circuit dysfunction.

Keywords:  SLC7A5; autism; branched-chain amino acids; lipids; metabolism; microcephaly; neurodevelopment

DOI:  https://doi.org/10.1016/j.cell.2023.02.037
Nat Commun. 2023 Mar 31. 14(1): 1806

Age-dependent Pdgfrβ signaling drives adipocyte progenitor dysfunction to alter the beige adipogenic niche in male mice.

Abigail M Benvie, Derek Lee, Benjamin M Steiner, Siwen Xue, Yuwei Jiang, Daniel C Berry.

Perivascular adipocyte progenitor cells (APCs) can generate cold temperature-induced thermogenic beige adipocytes within white adipose tissue (WAT), an effect that could counteract excess fat mass and metabolic pathologies. Yet, the ability to generate beige adipocytes declines with age, creating a key challenge for their therapeutic potential. Here we show that ageing beige APCs overexpress platelet derived growth factor receptor beta (Pdgfrβ) to prevent beige adipogenesis. We show that genetically deleting Pdgfrβ, in adult male mice, restores beige adipocyte generation whereas activating Pdgfrβ in juvenile mice blocks beige fat formation. Mechanistically, we find that Stat1 phosphorylation mediates Pdgfrβ beige APC signaling to suppress IL-33 induction, which dampens immunological genes such as IL-13 and IL-5. Moreover, pharmacologically targeting Pdgfrβ signaling restores beige adipocyte development by rejuvenating the immunological niche. Thus, targeting Pdgfrβ signaling could be a strategy to restore WAT immune cell function to stimulate beige fat in adult mammals.

DOI: https://doi.org/10.1038/s41467-023-37386-z
Cell. 2023 Mar 30. pii: S0092-8674(23)00210-6. [Epub ahead of print]186(7): 1448-1464.e20

A neutrophil response linked to tumor control in immunotherapy.

Jeremy Gungabeesoon, Nicolas A Gort-Freitas, Máté Kiss, Evangelia Bolli, Marius Messemaker, Marie Siwicki, Mehdi Hicham, Ruben Bill, Peter Koch, Chiara Cianciaruso, Florent Duval, Christina Pfirschke, Michael Mazzola, Solange Peters, Krisztian Homicsko, Christopher Garris, Ralph Weissleder, Allon M Klein, Mikael J Pittet.

  Neutrophils accumulate in solid tumors, and their abundance correlates with poor prognosis. Neutrophils are not homogeneous, however, and could play different roles in cancer therapy. Here, we investigate the role of neutrophils in immunotherapy, leading to tumor control. We show that successful therapies acutely expanded tumor neutrophil numbers. This expansion could be attributed to a Sellhi state rather than to other neutrophils that accelerate tumor progression. Therapy-elicited neutrophils acquired an interferon gene signature, also seen in human patients, and appeared essential for successful therapy, as loss of the interferon-responsive transcription factor IRF1 in neutrophils led to failure of immunotherapy. The neutrophil response depended on key components of anti-tumor immunity, including BATF3-dependent DCs, IL-12, and IFNγ. In addition, we found that a therapy-elicited systemic neutrophil response positively correlated with disease outcome in lung cancer patients. Thus, we establish a crucial role of a neutrophil state in mediating effective cancer therapy.

Keywords:  IRF1; SiglecF; anti-CD40; anti-PD-1; cancer; immunotherapy; interferon; lung cancer; neutrophil; single-cell RNA-seq

DOI:  https://doi.org/10.1016/j.cell.2023.02.032
J Clin Invest. 2023 Mar 28. pii: e168321. [Epub ahead of print]

Human inherited complete STAT2 deficiency underlies inflammatory viral diseases.

Giorgia Bucciol, Leen Moens, Masato Ogishi, Darawan Rinchai, Daniela Matuozzo, Mana Momenilandi, Nacim Kerrouche, Catherine M Cale, Elsa R Treffeisen, Mohammad Al Salamah, Bandar K Al-Saud, Alain Lachaux, Remi Duclaux-Loras, Marie Meignien, Aziz Bousfiha, Ibtihal Benhsaien, Anna Shcherbina, Anna Roppelt, Florian Gothe, Nadhira Houhou-Fidouh, Scott J Hackett, Lisa M Bartnikas, Michelle C Maciag, Mohammed F Alosaimi, Janet Chou, Reem W Mohammed, Bishara J Freij, Emmanuelle Jouanguy, Shen-Ying Zhang, Stephanie Boisson-Dupuis, Vivien Béziat, Qian Zhang, Christopher Ja Duncan, Sophie Hambleton, Jean-Laurent Casanova, Isabelle Meyts.

  STAT2 is a transcription factor activated by type I and III interferons. We report 23 patients with loss of function variants causing autosomal recessive (AR), complete STAT2 deficiency. Both cells transfected with mutant STAT2 alleles and the patients' cells display impaired expression of interferon stimulated genes and impaired control of in-vitro viral infections. Clinical manifestations from early childhood onward include severe adverse reaction to live attenuated viral vaccines (LAV, 12/17 patients) and severe viral infections (10/23 patients), particularly critical influenza pneumonia (6 patients), critical COVID-19 pneumonia (1 patient), and herpes simplex encephalitis (1 patient). The patients display various types of hyperinflammation, often triggered by viral infection or after LAV administration, which probably attests to unresolved viral infection in the absence of STAT2-dependent type I and III IFN immunity (7 patients). Transcriptomic analysis reveals that circulating monocytes, neutrophils, and CD8 memory T cells contribute to this inflammation. Eight patients died (35%, 2 months-7 years): one of HSV-1 encephalitis, one of fulminant hepatitis, and six of heart failure during a febrile illness with no identified etiology. 15 patients remain alive (5-40 years). AR complete STAT2 deficiency underlies severe viral diseases, with half of the patients surviving into teenage years or adulthood.

Keywords:  Genetic diseases; Immunology; Influenza; Innate immunity

DOI:  https://doi.org/10.1172/JCI168321
EMBO J. 2023 Mar 27. e111241

TFEB-dependent lysosome biogenesis is required for senescence.

Rachel Curnock, Katy Yalci, Johan Palmfeldt, Marja Jäättelä, Bin Liu, Bernadette Carroll.

  The accumulation of senescent cells is recognised as a driver of tissue and organismal ageing. One of the gold-standard hallmarks of a senescent cell is an increase in lysosomal content, as measured by senescence-associated β-galactosidase (Senβ-Gal) activity. The lysosome plays a central role in integrating mitogenic and stress cues to control cell metabolism, which is known to be dysregulated in senescence. Despite this, little is known about the cause and consequence of lysosomal biogenesis in senescence. We find here that lysosomes in senescent cells are dysfunctional; they have higher pH, increased evidence of membrane damage and reduced proteolytic capacity. The significant increase in lysosomal content is however sufficient to maintain degradative capacity of the cell to a level comparable to proliferating control cells. We demonstrate that increased nuclear TFEB/TFE3 supports lysosome biogenesis, is a hallmark of multiple forms of senescence and is required for senescent cell survival. TFEB/TFE3 are hypo-phosphorylated and show constitutive nuclear localisation in senescence. Evidence suggests that several pathways may contribute to TFEB/TFE3 dysregulation in senescence.

Keywords:  TFEB; autophagy; lysosome; senescence

DOI:  https://doi.org/10.15252/embj.2022111241
Sci Adv. 2023 Mar 31. 9(13): eadd6911

PI(4,5)P2-dependent regulation of endothelial tip cell specification contributes to angiogenesis.

Elizabeth M Davies, Rajendra Gurung, Kai Qin Le, Katherine T T Roan, Richard P Harvey, Geraldine M Mitchell, Quenten Schwarz, Christina A Mitchell.

Dynamic positioning of endothelial tip and stalk cells, via the interplay between VEGFR2 and NOTCH signaling, is essential for angiogenesis. VEGFR2 activates PI3K, which phosphorylates PI(4,5)P2 to PI(3,4,5)P3, activating AKT; however, PI3K/AKT does not direct tip cell specification. We report that PI(4,5)P2 hydrolysis by the phosphoinositide-5-phosphatase, INPP5K, contributes to angiogenesis. INPP5K ablation disrupted tip cell specification and impaired embryonic angiogenesis associated with enhanced DLL4/NOTCH signaling. INPP5K degraded a pool of PI(4,5)P2 generated by PIP5K1C phosphorylation of PI(4)P in endothelial cells. INPP5K ablation increased PI(4,5)P2, thereby releasing β-catenin from the plasma membrane, and concurrently increased PI(3,4,5)P3-dependent AKT activation, conditions that licensed DLL4/NOTCH transcription. Suppression of PI(4,5)P2 in INPP5K-siRNA cells by PIP5K1C-siRNA, restored β-catenin membrane localization and normalized AKT signaling. Pharmacological NOTCH or AKT inhibition in vivo or genetic β-catenin attenuation rescued angiogenesis defects in INPP5K-null mice. Therefore, PI(4,5)P2 is critical for β-catenin/DLL4/NOTCH signaling, which governs tip cell specification during angiogenesis.

DOI: https://doi.org/10.1126/sciadv.add6911