bims-mepmim 2024-03-17 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2024–03–17
23 papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Hepatic danger signaling triggers TREM2+ macrophage induction and drives steatohepatitis via MS4A7-dependent inflammasome activation.
Inhibition of 7-dehydrocholesterol reductase prevents hepatic ferroptosis under an active state of sterol synthesis.
Wnt5 controls splenic myelopoiesis and neutrophil functional ambivalency during DSS-induced colitis.
Mechanosensing regulates tissue repair program in macrophages.
H2S preconditioning induces long-lived perturbations in O2 metabolism.
Mitochondrial complex I activity in microglia sustains neuroinflammation.
Metabolic regulation of type I interferon production.
Fatty acid oxidation drives mitochondrial hydrogen peroxide production by α-ketoglutarate dehydrogenase.
Mitochondrial metabolism sustains CD8+ T cell migration for an efficient infiltration into solid tumors.
Quantitative proteomics reveals tissue-specific, infection-induced and species-specific neutrophil protein signatures.
Molecular imaging of tumor metabolism: Insight from pyruvate- and glucose-based deuterium MRI studies.
13 C-SpaceM: Spatial single-cell isotope tracing reveals heterogeneity of de novo fatty acid synthesis in cancer.
G protein-coupled receptor 84 gene expression is regulated by the ER stress response in the liver.
Bile acids modified by the intestinal microbiota promote colorectal cancer growth by suppressing CD8+ T cell effector functions.
ACSL4-mediated membrane phospholipid remodeling induces integrin β1 activation to facilitate triple-negative breast cancer metastasis.
m6A RNA methylation regulates mitochondrial function.
A proximity labeling-based orthogonal trap strategy identifies HDAC8 promotes cell motility by modulating cortactin acetylation.
Rapid unleashing of macrophage efferocytic capacity via transcriptional pause release.
Ex vivo activation of the GCN2 pathway metabolically reprograms T cells, leading to enhanced adoptive cell therapy.
TGF-β controls alveolar type 1 epithelial cell plasticity and alveolar matrisome gene transcription in mice.
Biopterin metabolism and nitric oxide recoupling in cancer.
The Integrated Stress Response in metabolic adaptation.
FASN Inhibition Decreases MHC-I Degradation and Synergizes with PD-L1 Checkpoint Blockade in Hepatocellular Carcinoma.

Sci Transl Med. 2024 Mar 13. 16(738): eadk1866

Hepatic danger signaling triggers TREM2+ macrophage induction and drives steatohepatitis via MS4A7-dependent inflammasome activation.

Linkang Zhou, Xiaoxue Qiu, Ziyi Meng, Tongyu Liu, Zhimin Chen, Peng Zhang, Henry Kuang, Tong Pan, You Lu, Ling Qi, David P Olson, X Z Shawn Xu, Y Eugene Chen, Siming Li, Jiandie D Lin.

Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (NASH), is an advanced stage of metabolic fatty liver disease. The pathogenic mechanisms of MASH center on hepatocyte injury and the ensuing immune response within the liver microenvironment. Recent work has implicated TREM2+ macrophages in various disease conditions, and substantial induction of TREM2+ NASH-associated macrophages (NAMs) serves as a hallmark of metabolic liver disease. Despite this, the mechanisms through which NAMs contribute to MASH pathogenesis remain poorly understood. Here, we identify membrane-spanning 4-domains a7 (MS4A7) as a NAM-specific pathogenic factor that exacerbates MASH progression in mice. Hepatic MS4A7 expression was strongly induced in mouse and human MASH and associated with the severity of liver injury. Whole-body and myeloid-specific ablation of Ms4a7 alleviated diet-induced MASH pathologies in male mice. We demonstrate that exposure to lipid droplets (LDs), released upon injury of steatotic hepatocytes, triggered NAM induction and exacerbated MASH-associated liver injury in an MS4A7-dependent manner. Mechanistically, MS4A7 drove NLRP3 inflammasome activation via direct physical interaction and shaped disease-associated cell states within the liver microenvironment. This work reveals the LD-MS4A7-NLRP3 inflammasome axis as a pathogenic driver of MASH progression and provides insights into the role of TREM2+ macrophages in disease pathogenesis.

DOI: https://doi.org/10.1126/scitranslmed.adk1866
Nat Commun. 2024 Mar 12. 15(1): 2195

Inhibition of 7-dehydrocholesterol reductase prevents hepatic ferroptosis under an active state of sterol synthesis.

Naoya Yamada, Tadayoshi Karasawa, Junya Ito, Daisuke Yamamuro, Kazushi Morimoto, Toshitaka Nakamura, Takanori Komada, Chintogtokh Baatarjav, Yuma Saimoto, Yuka Jinnouchi, Kazuhisa Watanabe, Kouichi Miura, Naoya Yahagi, Kiyotaka Nakagawa, Takayoshi Matsumura, Ken-Ichi Yamada, Shun Ishibashi, Naohiro Sata, Marcus Conrad, Masafumi Takahashi.

Recent evidence indicates ferroptosis is implicated in the pathophysiology of various liver diseases; however, the organ-specific regulation mechanism is poorly understood. Here, we demonstrate 7-dehydrocholesterol reductase (DHCR7), the terminal enzyme of cholesterol biosynthesis, as a regulator of ferroptosis in hepatocytes. Genetic and pharmacological inhibition (with AY9944) of DHCR7 suppress ferroptosis in human hepatocellular carcinoma Huh-7 cells. DHCR7 inhibition increases its substrate, 7-dehydrocholesterol (7-DHC). Furthermore, exogenous 7-DHC supplementation using hydroxypropyl β-cyclodextrin suppresses ferroptosis. A 7-DHC-derived oxysterol metabolite, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), is increased by the ferroptosis-inducer RSL-3 in DHCR7-deficient cells, suggesting that the ferroptosis-suppressive effect of DHCR7 inhibition is associated with the oxidation of 7-DHC. Electron spin resonance analysis reveals that 7-DHC functions as a radical trapping agent, thus protecting cells from ferroptosis. We further show that AY9944 inhibits hepatic ischemia-reperfusion injury, and genetic ablation of Dhcr7 prevents acetaminophen-induced acute liver failure in mice. These findings provide new insights into the regulatory mechanism of liver ferroptosis and suggest a potential therapeutic option for ferroptosis-related liver diseases.

DOI: https://doi.org/10.1038/s41467-024-46386-6
Cell Rep. 2024 Mar 08. pii: S2211-1247(24)00262-6. [Epub ahead of print]43(3): 113934

Wnt5 controls splenic myelopoiesis and neutrophil functional ambivalency during DSS-induced colitis.

Yi Luan, Jiajia Hu, Qijun Wang, Xujun Wang, Wenxue Li, Rihao Qu, Chuan Yang, Barani Kumar Rajendran, Hongyue Zhou, Peng Liu, Ningning Zhang, Yu Shi, Yansheng Liu, Wenwen Tang, Jun Lu, Dianqing Wu.

  Neutrophils are important innate immune cells with plasticity, heterogenicity, and functional ambivalency. While bone marrow is often regarded as the primary source of neutrophil production, the roles of extramedullary production in regulating neutrophil plasticity and heterogenicity in autoimmune diseases remain poorly understood. Here, we report that the lack of wingless-type MMTV integration site family member 5 (WNT5) unleashes anti-inflammatory protection against colitis in mice, accompanied by reduced colonic CD8+ T cell activation and enhanced splenic extramedullary myelopoiesis. In addition, colitis upregulates WNT5 expression in splenic stromal cells. The ablation of WNT5 leads to increased splenic production of hematopoietic niche factors, as well as elevated numbers of splenic neutrophils with heightened CD8+ T cell suppressive capability, in part due to elevated CD101 expression and attenuated pro-inflammatory activities. Thus, our study reveals a mechanism by which neutrophil plasticity and heterogenicity are regulated in colitis through WNT5 and highlights the role of splenic neutrophil production in shaping inflammatory outcomes.

Keywords:  CD101; CP: Immunology; Wnt signaling; colitis; extramedullary hematopoiesis; granulopoiesis; immune suppression; neutrophil

DOI:  https://doi.org/10.1016/j.celrep.2024.113934
Sci Adv. 2024 Mar 15. 10(11): eadk6906

Mechanosensing regulates tissue repair program in macrophages.

Matthew L Meizlish, Yoshitaka Kimura, Scott D Pope, Rita Matta, Catherine Kim, Naomi H Philip, Linde Meyaard, Anjelica Gonzalez, Ruslan Medzhitov.

Tissue-resident macrophages play important roles in tissue homeostasis and repair. However, how macrophages monitor and maintain tissue integrity is not well understood. The extracellular matrix (ECM) is a key structural and organizational component of all tissues. Here, we find that macrophages sense the mechanical properties of the ECM to regulate a specific tissue repair program. We show that macrophage mechanosensing is mediated by cytoskeletal remodeling and can be performed in three-dimensional environments through a noncanonical, integrin-independent mechanism analogous to amoeboid migration. We find that these cytoskeletal dynamics also integrate biochemical signaling by colony-stimulating factor 1 and ultimately regulate chromatin accessibility to control the mechanosensitive gene expression program. This study identifies an "amoeboid" mode of ECM mechanosensing through which macrophages may regulate tissue repair and fibrosis.

DOI: https://doi.org/10.1126/sciadv.adk6906
Proc Natl Acad Sci U S A. 2024 Mar 19. 121(12): e2319473121

H2S preconditioning induces long-lived perturbations in O2 metabolism.

David A Hanna, Jutta Diessl, Arkajit Guha, Roshan Kumar, Anthony Andren, Costas Lyssiotis, Ruma Banerjee.

  Hydrogen sulfide exposure in moderate doses can induce profound but reversible hypometabolism in mammals. At a cellular level, H2S inhibits the electron transport chain (ETC), augments aerobic glycolysis, and glutamine-dependent carbon utilization via reductive carboxylation; however, the durability of these changes is unknown. We report that despite its volatility, H2S preconditioning increases P50(O2), the O2 pressure for half-maximal cellular respiration, and has pleiotropic effects on oxidative metabolism that persist up to 24 to 48 h later. Notably, cyanide, another complex IV inhibitor, does not induce this type of metabolic memory. Sulfide-mediated prolonged fractional inhibition of complex IV by H2S is modulated by sulfide quinone oxidoreductase, which commits sulfide to oxidative catabolism. Since induced hypometabolism can be beneficial in disease settings that involve insufficient or interrupted blood flow, our study has important implications for attenuating reperfusion-induced ischemic injury and/or prolonging the shelf life of biologics like platelets.

Keywords:  bioenergetics; electron transport chain; hydrogen sulfide; oxygen metabolism

DOI:  https://doi.org/10.1073/pnas.2319473121
Nature. 2024 Mar 13.

Mitochondrial complex I activity in microglia sustains neuroinflammation.

L Peruzzotti-Jametti, C M Willis, G Krzak, R Hamel, L Pirvan, R-B Ionescu, J A Reisz, H A Prag, M E Garcia-Segura, V Wu, Y Xiang, B Barlas, A M Casey, A M R van den Bosch, A M Nicaise, L Roth, G R Bates, H Huang, P Prasad, A E Vincent, C Frezza, C Viscomi, G Balmus, Z Takats, J C Marioni, A D'Alessandro, M P Murphy, I Mohorianu, S Pluchino.

Sustained smouldering, or low-grade activation, of myeloid cells is a common hallmark of several chronic neurological diseases, including multiple sclerosis1. Distinct metabolic and mitochondrial features guide the activation and the diverse functional states of myeloid cells2. However, how these metabolic features act to perpetuate inflammation of the central nervous system is unclear. Here, using a multiomics approach, we identify a molecular signature that sustains the activation of microglia through mitochondrial complex I activity driving reverse electron transport and the production of reactive oxygen species. Mechanistically, blocking complex I in pro-inflammatory microglia protects the central nervous system against neurotoxic damage and improves functional outcomes in an animal disease model in vivo. Complex I activity in microglia is a potential therapeutic target to foster neuroprotection in chronic inflammatory disorders of the central nervous system3.

DOI: https://doi.org/10.1038/s41586-024-07167-9
Immunol Rev. 2024 Mar 11.

Metabolic regulation of type I interferon production.

Shane M O'Carroll, Fiona D R Henkel, Luke A J O'Neill.

  Over the past decade, there has been a surge in discoveries of how metabolic pathways regulate immune cell function in health and disease, establishing the field of immunometabolism. Specifically, pathways such as glycolysis, the tricarboxylic acid (TCA) cycle, and those involving lipid metabolism have been implicated in regulating immune cell function. Viral infections cause immunometabolic changes which lead to antiviral immunity, but little is known about how metabolic changes regulate interferon responses. Interferons are critical cytokines in host defense, rapidly induced upon pathogen recognition, but are also involved in autoimmune diseases. This review summarizes how metabolic change impacts interferon production. We describe how glycolysis, lipid metabolism (specifically involving eicosanoids and cholesterol), and the TCA cycle-linked intermediates itaconate and fumarate impact type I interferons. Targeting these metabolic changes presents new therapeutic possibilities to modulate type I interferons during host defense or autoimmune disorders.

Keywords:  Immunometabolism; interferons; macrophage; metabolism

DOI:  https://doi.org/10.1111/imr.13318
J Biol Chem. 2024 Mar 11. pii: S0021-9258(24)01654-5. [Epub ahead of print] 107159

Fatty acid oxidation drives mitochondrial hydrogen peroxide production by α-ketoglutarate dehydrogenase.

Cathryn Grayson, Ben Faerman, Olivia Koufos, Ryan J Mailloux.

In the present study, we examined the mitochondrial hydrogen peroxide (mH2O2) generating capacity of α-ketoglutarate dehydrogenase (KGDH) and compared it to components of the electron transport chain (ETC) using liver mitochondria isolated from male and female C57BL6N mice. We show for the first time there are some sex dimorphisms in the production of mH2O2 by ETC complexes I and III when mitochondria are fueled with different substrates. However, in our investigations into these sex effects, we made the unexpected discovery that: 1. KGDH serves as a major mH2O2 supplier in male and female liver mitochondria and 2. KGDH can form mH2O2 when mitochondria are energized with fatty acids, but only when malate is used to prime the Krebs cycle. Surprisingly, 2-keto-3-methylvaleric acid (KMV), a site-specific inhibitor for KGDH, nearly abolished mH2O2 generation in both male and female liver mitochondria oxidizing palmitoyl-carnitine. KMV inhibited mH2O2 production in liver mitochondria from male and female mice oxidizing myristoyl-, octanoyl-, or butyryl-carnitine. S1QEL 1.1 (S1) and S3QEL 2 (S3), compounds that inhibit reactive oxygen species (ROS) generation by complexes I and III, respectively, without interfering with OxPhos, had a negligible effect on the rate of mH2O2 production when pyruvate or acyl-carnitines were used as fuels. However, inclusion of KMV in reaction mixtures containing S1 and/or S3 almost abolished mH2O2 generation. Together, our findings suggest KGDH is the main mH2O2 generator in liver mitochondria, even when fatty acids are used as fuel.

DOI: https://doi.org/10.1016/j.jbc.2024.107159
Nat Commun. 2024 Mar 11. 15(1): 2203

Mitochondrial metabolism sustains CD8+ T cell migration for an efficient infiltration into solid tumors.

Luca Simula, Mattia Fumagalli, Lene Vimeux, Irena Rajnpreht, Philippe Icard, Gary Birsen, Dongjie An, Frédéric Pendino, Adrien Rouault, Nadège Bercovici, Diane Damotte, Audrey Lupo-Mansuet, Marco Alifano, Marie-Clotilde Alves-Guerra, Emmanuel Donnadieu.

The ability of CD8+ T cells to infiltrate solid tumors and reach cancer cells is associated with improved patient survival and responses to immunotherapy. Thus, identifying the factors controlling T cell migration in tumors is critical, so that strategies to intervene on these targets can be developed. Although interstitial motility is a highly energy-demanding process, the metabolic requirements of CD8+ T cells migrating in a 3D environment remain unclear. Here, we demonstrate that the tricarboxylic acid (TCA) cycle is the main metabolic pathway sustaining human CD8+ T cell motility in 3D collagen gels and tumor slices while glycolysis plays a more minor role. Using pharmacological and genetic approaches, we report that CD8+ T cell migration depends on the mitochondrial oxidation of glucose and glutamine, but not fatty acids, and both ATP and ROS produced by mitochondria are required for T cells to migrate. Pharmacological interventions to increase mitochondrial activity improve CD8+ T cell intratumoral migration and CAR T cell recruitment into tumor islets leading to better control of tumor growth in human xenograft models. Our study highlights the rationale of targeting mitochondrial metabolism to enhance the migration and antitumor efficacy of CAR T cells in treating solid tumors.

DOI: https://doi.org/10.1038/s41467-024-46377-7
Sci Rep. 2024 03 12. 14(1): 5966

Quantitative proteomics reveals tissue-specific, infection-induced and species-specific neutrophil protein signatures.

Gabriel Sollberger, Alejandro J Brenes, Jordan Warner, J Simon C Arthur, Andrew J M Howden.

Neutrophils are one of the first responders to infection and are a key component of the innate immune system through their ability to phagocytose and kill invading pathogens, secrete antimicrobial molecules and produce extracellular traps. Neutrophils are produced in the bone marrow, circulate within the blood and upon immune challenge migrate to the site of infection. We wanted to understand whether this transition shapes the mouse neutrophil protein landscape, how the mouse neutrophil proteome is impacted by systemic infection and perform a comparative analysis of human and mouse neutrophils. Using quantitative mass spectrometry we reveal tissue-specific, infection-induced and species-specific neutrophil protein signatures. We show a high degree of proteomic conservation between mouse bone marrow, blood and peritoneal neutrophils, but also identify key differences in the molecules that these cells express for sensing and responding to their environment. Systemic infection triggers a change in the bone marrow neutrophil population with considerable impact on the core machinery for protein synthesis and DNA replication along with environmental sensors. We also reveal profound differences in mouse and human blood neutrophils, particularly their granule contents. Our proteomics data provides a valuable resource for understanding neutrophil function and phenotypes across species and model systems.

DOI: https://doi.org/10.1038/s41598-024-56163-6
Sci Adv. 2024 Mar 15. 10(11): eadm8600

Molecular imaging of tumor metabolism: Insight from pyruvate- and glucose-based deuterium MRI studies.

Elton T Montrazi, Keren Sasson, Lilach Agemy, Avigdor Scherz, Lucio Frydman.

Cancer diagnosis by metabolic MRI proposes to follow the fate of glycolytic precursors such as pyruvate or glucose, and their in vivo conversion into lactate. This study compares the 2H MRI outlooks afforded by these metabolites when targeting a pancreatic cancer model. Exogenously injected [3,3',3″-2H3]-pyruvate was visible only briefly; it generated a deuterated lactate signal throughout the body that faded after ~5 min, showing a minor concentration bias at the rims of the tumors. [6,6'-2H2]-glucose by contrast originated a lactate signal that localized clearly within the tumors, persisting for over an hour. Investigations alternating deuterated and nondeuterated glucose injections revealed correlations between the lactate generation and the glucose available at the tumor, evidencing a continuous and avid glucose consumption generating well-localized lactate signatures as driven by the Warburg effect. This is by contrast to the transient and more promiscuous pyruvate-to-lactate transformation, which seemed subject to transporter and kinetics effects. The consequences of these observations within metabolic MRI are briefly discussed.

DOI: https://doi.org/10.1126/sciadv.adm8600
bioRxiv. 2024 Feb 28. pii: 2023.08.18.553810. [Epub ahead of print]

13 C-SpaceM: Spatial single-cell isotope tracing reveals heterogeneity of de novo fatty acid synthesis in cancer.

Elena Buglakova, Måns Ekelöf, Michaela Schwaiger-Haber, Lisa Schlicker, Martijn R Molenaar, Shahraz Mohammed, Lachlan Stuart, Andreas Eisenbarth, Volker Hilsenstein, Gary J Patti, Almut Schulze, Marteinn T Snaebjornsson, Theodore Alexandrov.

Metabolism has emerged as a key factor in homeostasis and disease including cancer. Yet, little is known about the heterogeneity of metabolic activity of cancer cells due to the lack of tools to directly probe it. Here, we present a novel method, 13 C-SpaceM for spatial single-cell isotope tracing of glucose-dependent de novo lipogenesis. The method combines imaging mass spectrometry for spatially-resolved detection of 13 C 6 -glucose-derived 13 C label incorporated into esterified fatty acids with microscopy and computational methods for data integration and analysis. We validated 13 C-SpaceM on a spatially-heterogeneous normoxia-hypoxia model of liver cancer cells. Investigating cultured cells, we revealed single-cell heterogeneity of lipogenic acetyl-CoA pool labelling degree upon ACLY knockdown that is hidden in the bulk analysis and its effect on synthesis of individual fatty acids. Next, we adapted 13 C-SpaceM to analyze tissue sections of mice harboring isocitrate dehydrogenase (IDH)-mutant gliomas. We found a strong induction of de novo fatty acid synthesis in the tumor tissue compared to the surrounding brain. Comparison of fatty acid isotopologue patterns revealed elevated uptake of mono-unsaturated and essential fatty acids in the tumor. Furthermore, our analysis uncovered substantial spatial heterogeneity in the labelling of the lipogenic acetyl-CoA pool indicative of metabolic reprogramming during microenvironmental adaptation. Overall, 13 C-SpaceM enables novel ways for spatial probing of metabolic activity at the single cell level. Additionally, this methodology provides unprecedented insight into fatty acid uptake, synthesis and modification in normal and cancerous tissues.

DOI: https://doi.org/10.1101/2023.08.18.553810
J Biochem. 2024 Mar 12. pii: mvae027. [Epub ahead of print]

G protein-coupled receptor 84 gene expression is regulated by the ER stress response in the liver.

Soshi Kanemoto.

  G protein-coupled receptor 84 (Gpr84) is reportedly activated by medium-chain fatty acids and is involved in the pathology of liver fibrosis. Inflammatory stimulants such as lipopolysaccharide and tumor necrosis factor-α upregulate Gpr84 expression. However, the detailed molecular mechanism by which Gpr84 is induced remains unknown. Inflammatory stimulation also evokes endoplasmic reticulum (ER) stress, but there has been no direct evidence to link Gpr84 expression and the ER stress response. Administration of tunicamycin (Tm) provokes ER stress and acute steatosis in the liver tissue of mice. Here, in situ hybridization analysis revealed that induction of Gpr84 expression occurred in parenchymal cells in the liver tissue following Tm administration. Gene expression analysis using a reporter assay showed that the intron 1 region of Gpr84 was involved in induction of the gene under ER stress conditions. Furthermore, Tm-dependent upregulation of Gpr84 was blocked by the small chemical compound AEBSF, an inhibitor of ER stress transducers, in vitro and in vivo. In conclusion, the current study marks the discovery that the ER stress agent Tm induces the expression of Gpr84.

Keywords:  Creb3 family; Endoplasmic reticulum stress; G protein-coupled receptor 84; Liver; Tunicamycin

DOI:  https://doi.org/10.1093/jb/mvae027
Immunity. 2024 Mar 06. pii: S1074-7613(24)00090-6. [Epub ahead of print]

Bile acids modified by the intestinal microbiota promote colorectal cancer growth by suppressing CD8+ T cell effector functions.

Jingjing Cong, Pianpian Liu, Zili Han, Wei Ying, Chaoliang Li, Yifei Yang, Shuling Wang, Jianbo Yang, Fei Cao, Juntao Shen, Yu Zeng, Yu Bai, Congzhao Zhou, Lilin Ye, Rongbin Zhou, Chunjun Guo, Chunlei Cang, Dennis L Kasper, Xinyang Song, Lei Dai, Linfeng Sun, Wen Pan, Shu Zhu.

  Concentrations of the secondary bile acid, deoxycholic acid (DCA), are aberrantly elevated in colorectal cancer (CRC) patients, but the consequences remain poorly understood. Here, we screened a library of gut microbiota-derived metabolites and identified DCA as a negative regulator for CD8+ T cell effector function. Mechanistically, DCA suppressed CD8+ T cell responses by targeting plasma membrane Ca2+ ATPase (PMCA) to inhibit Ca2+-nuclear factor of activated T cells (NFAT)2 signaling. In CRC patients, CD8+ T cell effector function negatively correlated with both DCA concentration and expression of a bacterial DCA biosynthetic gene. Bacteria harboring DCA biosynthetic genes suppressed CD8+ T cells effector function and promoted tumor growth in mice. This effect was abolished by disrupting bile acid metabolism via bile acid chelation, genetic ablation of bacterial DCA biosynthetic pathway, or specific bacteriophage. Our study demonstrated causation between microbial DCA metabolism and anti-tumor CD8+ T cell response in CRC, suggesting potential directions for anti-tumor therapy.

Keywords:  CD8(+) T cell; anti-tumor immunity; deoxycholic acid; effector function; microbiota

DOI:  https://doi.org/10.1016/j.immuni.2024.02.014
Cancer Res. 2024 Mar 12.

ACSL4-mediated membrane phospholipid remodeling induces integrin β1 activation to facilitate triple-negative breast cancer metastasis.

Yuxiang Qiu, Xing Wang, Yan Sun, Ting Jin, Rui Tang, Xinyue Zhou, Ming Xu, Yubi Gan, Rui Wang, Haojun Luo, Manran Liu, Xi Tang.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer and has a poor prognosis and a high propensity to metastasize. Lipid metabolism has emerged as a critical regulator of tumor progression and metastasis in other cancer types. Characterization of the lipid metabolic features of TNBC could provide important insights into the drivers of TNBC metastasis. Here, we showed that metastatic TNBC tumors harbor more unsaturated phospholipids, especially long-chain polyunsaturated fatty acids, at the sn-2 position of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) compared to primary tumors. Metastatic TNBC tumors upregulated ACSL4, a long-chain polyunsaturated acyl-CoA synthetase that drives the preferential incorporation of polyunsaturated fatty acids into phospholipids, resulting in the alteration of membrane phospholipid composition and properties. Moreover, ACSL4-mediated phospholipid remodeling of the cell membrane induced lipid-raft localization and activation of integrin β1 in a CD47-dependent manner, which led to downstream focal adhesion kinase (FAK) phosphorylation that promoted metastasis. Importantly, pharmacological inhibition of ACSL4 suppressed tumor growth and metastasis and increased chemosensitivity in TNBC models in vivo. These findings indicate that ACSL4-mediated phospholipid remodeling enables TNBC metastasis and can be inhibited as a potential strategy to improve the efficacy of chemotherapy in TNBC.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-2491
Hum Mol Genet. 2024 Mar 14. pii: ddae029. [Epub ahead of print]

m6A RNA methylation regulates mitochondrial function.

Michael Kahl, Zhaofa Xu, Saravanan Arumugam, Brittany Edens, Mariafausta Fischietti, Allen C Zhu, Leonidas C Platanias, Chuan He, Xiaoxi Zhuang, Yongchao C Ma.

  RNA methylation of N6-methyladenosine (m6A) is emerging as a fundamental regulator of every aspect of RNA biology. RNA methylation directly impacts protein production to achieve quick modulation of dynamic biological processes. However, whether RNA methylation regulates mitochondrial function is not known, especially in neuronal cells which require a high energy supply and quick reactive responses. Here we show that m6A RNA methylation regulates mitochondrial function through promoting nuclear-encoded mitochondrial complex subunit RNA translation. Conditional genetic knockout of m6A RNA methyltransferase Mettl14 (Methyltransferase like 14) by Nestin-Cre together with metabolomic analysis reveals that Mettl14 knockout-induced m6A depletion significantly downregulates metabolites related to energy metabolism. Furthermore, transcriptome-wide RNA methylation profiling of wild type and Mettl14 knockout mouse brains by m6A-Seq shows enrichment of methylation on mitochondria-related RNA. Importantly, loss of m6A leads to a significant reduction in mitochondrial respiratory capacity and membrane potential. These functional defects are paralleled by the reduced expression of mitochondrial electron transport chain complexes, as well as decreased mitochondrial super-complex assembly and activity. Mechanistically, m6A depletion decreases the translational efficiency of methylated RNA encoding mitochondrial complex subunits through reducing their association with polysomes, while not affecting RNA stability. Together, these findings reveal a novel role for RNA methylation in regulating mitochondrial function. Given that mitochondrial dysfunction and RNA methylation have been increasingly implicate in neurodegenerative disorders, our findings not only provide insights into fundamental mechanisms regulating mitochondrial function, but also open up new avenues for understanding the pathogenesis of neurological diseases.

Keywords:  m6A RNA methylation; metabolomics; mitochondria; neurological disease; transcriptomics

DOI:  https://doi.org/10.1093/hmg/ddae029
Cell Chem Biol. 2024 Mar 06. pii: S2451-9456(24)00077-1. [Epub ahead of print]

A proximity labeling-based orthogonal trap strategy identifies HDAC8 promotes cell motility by modulating cortactin acetylation.

Yepei Huang, Guijin Zhai, Yun Fu, Yanan Li, Yong Zang, Yu Lin, Kai Zhang.

  It is a challenge for the traditional affinity methods to capture transient interactions of enzyme-post-translational modification (PTM) substrates in vivo. Herein we presented a strategy termed proximity labeling-based orthogonal trap approach (ProLORT), relying upon APEX2-catalysed proximity labeling and an orthogonal trap pipeline as well as quantitative proteomics to directly investigate the transient interactome of enzyme-PTM substrates in living cells. As a proof of concept, ProLORT allows for robust evaluation of a known HDAC8 substrate, histone H3K9ac. By leveraging this approach, we identified numerous of putative acetylated proteins targeted by HDAC8, and further confirmed CTTN as a bona fide substrate in vivo. Next, we demonstrated that HDAC8 facilitates cell motility via deacetylation of CTTN at lysine 144 that attenuates its interaction with F-actin, expanding the underlying regulatory mechanisms of HDAC8. We developed a general strategy to profile the transient enzyme-substrate interactions mediated by PTMs, providing a powerful tool for identifying the spatiotemporal PTM-network regulated by enzymes in living cells.

Keywords:  HDAC8; cell motilit; enzyme-substrate interactions; lysine acetylation; orthogonal trap; proximity labeling

DOI:  https://doi.org/10.1016/j.chembiol.2024.02.003
Nature. 2024 Mar 13.

Rapid unleashing of macrophage efferocytic capacity via transcriptional pause release.

Turan Tufan, Gamze Comertpay, Ambra Villani, Geoffrey M Nelson, Marina Terekhova, Shannon Kelley, Pavel Zakharov, Rochelle M Ellison, Oleg Shpynov, Michael Raymond, Jerry Sun, Yitan Chen, Enno Bockelmann, Marta Stremska, Lance W Peterson, Laura Boeckaerts, Seth R Goldman, J Iker Etchegaray, Maxim N Artyomov, Francesca Peri, Kodi S Ravichandran.

During development, inflammation or tissue injury, macrophages may successively engulf and process multiple apoptotic corpses via efferocytosis to achieve tissue homeostasis1. How macrophages may rapidly adapt their transcription to achieve continuous corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved mechanism, in which RNA polymerase (Pol) II initiates transcription for 20-60 nucleotides, is paused for minutes to hours and is then released to make full-length mRNA2. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release to unleash a rapid transcriptional response. For human and mouse macrophages, the Pol II pause/release was required for continuous efferocytosis in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede Fc receptor-mediated phagocytosis, yeast uptake or bacterial phagocytosis. Integration of data from three genomic approaches-precision nuclear run-on sequencing, RNA sequencing, and assay for transposase-accessible chromatin using sequencing (ATAC-seq)-on efferocytic macrophages at different time points revealed that Pol II pause/release controls expression of select transcription factors and downstream target genes. Mechanistic studies on transcription factor EGR3, prominently regulated by pause/release, uncovered EGR3-related reprogramming of other macrophage genes involved in cytoskeleton and corpse processing. Using lysosomal probes and a new genetic fluorescent reporter, we identify a role for pause/release in phagosome acidification during efferocytosis. Furthermore, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing phagosomes, supporting defective corpse processing. Collectively, these data indicate that macrophages use Pol II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpses and for successive efferocytosis.

DOI: https://doi.org/10.1038/s41586-024-07172-y
Cell Rep Med. 2024 Mar 01. pii: S2666-3791(24)00109-5. [Epub ahead of print] 101465

Ex vivo activation of the GCN2 pathway metabolically reprograms T cells, leading to enhanced adoptive cell therapy.

Michael St Paul, Samuel D Saibil, Meghan Kates, SeongJun Han, Scott C Lien, Rob C Laister, Kebria Hezaveh, Andreas Kloetgen, Susanne Penny, Tingxi Guo, Carlos Garcia-Batres, Logan K Smith, Douglas C Chung, Alisha R Elford, Azin Sayad, Devanand Pinto, Tak W Mak, Naoto Hirano, Tracy McGaha, Pamela S Ohashi.

  The manipulation of T cell metabolism to enhance anti-tumor activity is an area of active investigation. Here, we report that activating the amino acid starvation response in effector CD8+ T cells ex vivo using the general control non-depressible 2 (GCN2) agonist halofuginone (halo) enhances oxidative metabolism and effector function. Mechanistically, we identified autophagy coupled with the CD98-mTOR axis as key downstream mediators of the phenotype induced by halo treatment. The adoptive transfer of halo-treated CD8+ T cells into tumor-bearing mice led to robust tumor control and curative responses. Halo-treated T cells synergized in vivo with a 4-1BB agonistic antibody to control tumor growth in a mouse model resistant to immunotherapy. Importantly, treatment of human CD8+ T cells with halo resulted in similar metabolic and functional reprogramming. These findings demonstrate that activating the amino acid starvation response with the GCN2 agonist halo can enhance T cell metabolism and anti-tumor activity.

Keywords:  4-1BB; CD8(+) T cell; GCN2; Halofuginone; adoptive Cell therapy; autophagy; immunometabolism; immunotherapy

DOI:  https://doi.org/10.1016/j.xcrm.2024.101465
J Clin Invest. 2024 Jan 11. pii: e172095. [Epub ahead of print]134(6):

TGF-β controls alveolar type 1 epithelial cell plasticity and alveolar matrisome gene transcription in mice.

Danielle A Callaway, Ian J Penkala, Su Zhou, Jonathan J Knowlton, Fabian Cardenas-Diaz, Apoorva Babu, Michael P Morley, Mariana Lopes, Benjamin A Garcia, Edward E Morrisey.

  Premature birth disrupts normal lung development and places infants at risk for bronchopulmonary dysplasia (BPD), a disease disrupting lung health throughout the life of an individual and that is increasing in incidence. The TGF-β superfamily has been implicated in BPD pathogenesis, however, what cell lineage it impacts remains unclear. We show that TGFbr2 is critical for alveolar epithelial (AT1) cell fate maintenance and function. Loss of TGFbr2 in AT1 cells during late lung development leads to AT1-AT2 cell reprogramming and altered pulmonary architecture, which persists into adulthood. Restriction of fetal lung stretch and associated AT1 cell spreading through a model of oligohydramnios enhances AT1-AT2 reprogramming. Transcriptomic and proteomic analyses reveal the necessity of TGFbr2 expression in AT1 cells for extracellular matrix production. Moreover, TGF-β signaling regulates integrin transcription to alter AT1 cell morphology, which further impacts ECM expression through changes in mechanotransduction. These data reveal the cell intrinsic necessity of TGF-β signaling in maintaining AT1 cell fate and reveal this cell lineage as a major orchestrator of the alveolar matrisome.

Keywords:  Extracellular matrix; Integrins; Pulmonology; Respiration

DOI:  https://doi.org/10.1172/JCI172095
Front Oncol. 2023 ;13 1321326

Biopterin metabolism and nitric oxide recoupling in cancer.

Gene Chatman Clark, Alan Lai, Aashri Agarwal, Zheng Liu, Xiang-Yang Wang.

  Tetrahydrobiopterin is a cofactor necessary for the activity of several enzymes, the most studied of which is nitric oxide synthase. The role of this cofactor-enzyme relationship in vascular biology is well established. Recently, tetrahydrobiopterin metabolism has received increasing attention in the field of cancer immunology and immunotherapy due to its involvement in the cytotoxic T cell response. Past research has demonstrated that when the availability of BH4 is low, as it is in chronic inflammatory conditions and tumors, electron transfer in the active site of nitric oxide synthase becomes uncoupled from the oxidation of arginine. This results in the production of radical species that are capable of a direct attack on tetrahydrobiopterin, further depleting its local availability. This feedforward loop may act like a molecular switch, reinforcing low tetrahydrobiopterin levels leading to altered NO signaling, restrained immune effector activity, and perpetual vascular inflammation within the tumor microenvironment. In this review, we discuss the evidence for this underappreciated mechanism in different aspects of tumor progression and therapeutic responses. Furthermore, we discuss the preclinical evidence supporting a clinical role for tetrahydrobiopterin supplementation to enhance immunotherapy and radiotherapy for solid tumors and the potential safety concerns.

Keywords:  S-nitrosylation; cancer; immunometabolism; immunotherapy; nitric oxide synthase; radiotherapy; tetrahydrobiopterin; vascular normalization

DOI:  https://doi.org/10.3389/fonc.2023.1321326
J Biol Chem. 2024 Mar 08. pii: S0021-9258(24)01646-6. [Epub ahead of print] 107151

The Integrated Stress Response in metabolic adaptation.

Hyung Don Ryoo.

  The Integrated Stress Response (ISR) refers to signaling pathways initiated by stress-activated eIF2‹ kinases. Distinct eIF2‹ kinases respond to different stress signals, including amino acid deprivation and mitochondrial stress. Such stress-induced eIF2‹ phosphorylation attenuates general mRNA translation and, at the same time, stimulates the preferential translation of specific downstream factors to orchestrate an adaptive gene expression program. In recent years, there have been significant new advances in our understanding of ISR during metabolic stress adaptation. Here, I discuss those advances, reviewing among others the ISR activation mechanisms in response to amino acid deprivation and mitochondrial stress. In addition, I review how ISR regulates the amino acid metabolic pathways and how changes in the ISR impact the physiology and pathology of various disease models.

Keywords:  ATF4; GCN1; GCN2; HRI; Integrated Stress Response; amino acid deprivation; cysteine; eIF2‹; glutathione; mitochondrial stress; serine biosynthesis

DOI:  https://doi.org/10.1016/j.jbc.2024.107151
Cancer Res. 2024 Mar 15. 84(6): 855-871

FASN Inhibition Decreases MHC-I Degradation and Synergizes with PD-L1 Checkpoint Blockade in Hepatocellular Carcinoma.

Jiao Huang, Wai Ying Tsang, Xiao-Na Fang, Yu Zhang, Jie Luo, Lan-Qi Gong, Bai-Feng Zhang, Ching Ngar Wong, Zhi-Hong Li, Bei-Lei Liu, Jin-Lin Huang, Yu-Ma Yang, Shan Liu, Liu-Xian Ban, Yiu Hong Chan, Xin-Yuan Guan.

Immune checkpoint inhibitors (ICI) transformed the treatment landscape of hepatocellular carcinoma (HCC). Unfortunately, patients with attenuated MHC-I expression remain refractory to ICIs, and druggable targets for upregulating MHC-I are limited. Here, we found that genetic or pharmacologic inhibition of fatty acid synthase (FASN) increased MHC-I levels in HCC cells, promoting antigen presentation and stimulating antigen-specific CD8+ T-cell cytotoxicity. Mechanistically, FASN inhibition reduced palmitoylation of MHC-I that led to its lysosomal degradation. The palmitoyltransferase DHHC3 directly bound MHC-I and negatively regulated MHC-I protein levels. In an orthotopic HCC mouse model, Fasn deficiency enhanced MHC-I levels and promoted cancer cell killing by tumor-infiltrating CD8+ T cells. Moreover, the combination of two different FASN inhibitors, orlistat and TVB-2640, with anti-PD-L1 antibody robustly suppressed tumor growth in vivo. Multiplex IHC of human HCC samples and bioinformatic analysis of The Cancer Genome Atlas data further illustrated that lower expression of FASN was correlated with a higher percentage of cytotoxic CD8+ T cells. The identification of FASN as a negative regulator of MHC-I provides the rationale for combining FASN inhibitors and immunotherapy for treating HCC.
SIGNIFICANCE: Inhibition of FASN increases MHC-I protein levels by suppressing its palmitoylation and lysosomal degradation, which stimulates immune activity against hepatocellular carcinoma and enhances the efficacy of immune checkpoint inhibition.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-0966