bims-mepmim 2023-06-11 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2023‒06‒11
28 papers selected by
Erika Mariana Palmieri
NIH/NCI Laboratory of Cancer ImmunoMetabolism

Loss of the mitochondrial protein Abcb10 results in altered arginine metabolism in MEL and K562 cells and nutrient stress signaling through ATF4.
Roles of malate and aspartate in gluconeogenesis in various physiological and pathological states.
ACL and HAT1 form a nuclear module to acetylate histone H4K5 and promote cell proliferation.
Tumor cell-derived spermidine is an oncometabolite that suppresses TCR clustering for intratumoral CD8+ T cell activation.
Resolving sepsis-induced immunoparalysis via trained immunity by targeting interleukin-4 to myeloid cells.
Metabolomics identifies the intestinal geography of microbial metabolite production.
Hypusination Maintains Intestinal Homeostasis and Prevents Colitis and Carcinogenesis by Enhancing Aldehyde Detoxification.
Expression and subcellular localization of mitochondrial docking protein, syntaphilin, in oligodendrocytes and CNS myelin sheath.
Generation of liver mesenchyme and ductal cell organoid co-culture using cell self-aggregation and droplet microfluidics.
A molecular rotor FLIM probe reveals dynamic coupling between mitochondrial inner membrane fluidity and cellular respiration.
Role of 2-hydroxy acyl-CoA lyase HACL2 in odd-chain fatty acid production via α-oxidation in vivo.
Resolvin D1 reprograms energy metabolism to promote microglia to phagocytize neutrophils after ischemic stroke.
Genetic deletion of skeletal muscle iPLA2γ results in mitochondrial dysfunction, muscle atrophy and alterations in whole-body energy metabolism.
Differentiation tracing identifies hematopoietic regeneration from multipotent progenitors but not stem cells.
ROS signaling-induced mitochondrial Sgk1 expression regulates epithelial cell renewal.
Endogenous PP2A inhibitor CIP2A degradation by chaperone-mediated autophagy contributes to the antitumor effect of mitochondrial complex I inhibition.
Identification of host regulators of Mycobacteriumtuberculosis phenotypes uncovers a role for the MMGT1-GPR156 lipid droplet axis in persistence.
Redundant electrostatic interactions between GATOR1 and the Rag GTPase heterodimer drives efficient amino acid sensing in human cells.
Obesity-induced metabolic imbalance allosterically modulates CtBP2 to inhibit PPAR-alpha transcriptional activity.
Free ferrous ions sustain activity of mammalian stearoyl-CoA desaturase-1.
Fumarate disarms CD8+ T cells against cancer.
Engineering the IL-4/IL-13 axis for targeted immune modulation.
Characterisation of hepatic lipid signature distributed across the liver zonation using mass spectrometry imaging.
De novo pyrimidine biosynthetic complexes support cancer cell proliferation and ferroptosis defence.
Mitochondrial metabolism and dynamics in pancreatic beta cell glucose sensing.
A cytosolic surveillance mechanism activates the mitochondrial UPR.
The incretin co-agonist tirzepatide requires GIPR for hormone secretion from human islets.
Lysophosphatidic acid modulates CD8 T cell immunosurveillance and metabolism to impair anti-tumor immunity.

J Biol Chem. 2023 Jun 01. pii: S0021-9258(23)01905-1. [Epub ahead of print] 104877

Loss of the mitochondrial protein Abcb10 results in altered arginine metabolism in MEL and K562 cells and nutrient stress signaling through ATF4.

Marisa Miljkovic, Alexandra Seguin, Xuan Jia, James E Cox, Jonathan Leon Catrow, Hector Bergonia, John D Phillips, W Zac Stephens, Diane M Ward.

  Abcb10 is a mitochondrial membrane protein involved in hemoglobinization of red cells. Abcb10 topology and ATPase domain localization suggest it exports a substrate, likely biliverdin, out of mitochondria that is necessary for hemoglobinization. In this study we generated Abcb10 deletion cell lines in both mouse murine erythroleukemia (MEL) and human erythroid precursor human myelogenous leukemia (K562) cells to better understand the consequences of Abcb10 loss. Loss of Abcb10 resulted in an inability to hemoglobinize upon differentiation in both K562 and MEL cells with reduced heme and intermediate porphyrins and decreased levels of aminolevulinic acid synthase 2 activity. Metabolomic and transcriptional analyses revealed that Abcb10 loss gave rise to decreased cellular arginine levels, increased transcripts for cationic and neutral amino acid transporters with reduced levels of the citrulline to arginine converting enzymes argininosuccinate synthetase and argininosuccinate lyase. The reduced arginine levels in Abcb10 null cells gave rise to decreased proliferative capacity. Arginine supplementation improved both Abcb10 null proliferation and hemoglobinization upon differentiation. Abcb10 null cells showed increased phosphorylation of Eukaryotic Translation Initiation Factor 2 Subunit Alpha (eIF2A), increased expression of nutrient sensing transcription factor ATF4 and downstream targets DNA damage inducible transcript 3 (Chop), ChaC glutathione specific gamma-glutamylcyclotransferase 1 (Chac1) and arginyl-tRNA synthetase 1 (Rars). These results suggest that when the Abcb10 substrate is trapped in the mitochondria, the nutrient sensing machinery is turned on remodeling transcription to block protein synthesis necessary for proliferation and hemoglobin biosynthesis in erythroid models.

Keywords:  Arginine; differentiation; erythroid; metabolism; nutrient; transporter

DOI:  https://doi.org/10.1016/j.jbc.2023.104877
Metabolism. 2023 Jun 05. pii: S0026-0495(23)00218-4. [Epub ahead of print] 155614

Roles of malate and aspartate in gluconeogenesis in various physiological and pathological states.

Milan Holeček.

  Gluconeogenesis, a pathway for glucose synthesis from non-carbohydrate substances, begins with the synthesis of oxaloacetate (OA) from pyruvate and intermediates of citric acid cycle in hepatocyte mitochondria. The traditional view is that OA does not cross the mitochondrial membrane and must be shuttled to the cytosol, where most enzymes involved in gluconeogenesis are compartmentalized, in the form of malate. Thus, the possibility of transporting OA in the form of aspartate has been ignored. In the article is shown that malate supply to the cytosol increases only when fatty acid oxidation in the liver is activated, such as during starvation or untreated diabetes. Alternatively, aspartate synthesized from OA by mitochondrial aspartate aminotransferase (AST) is transported to the cytosol in exchange for glutamate via the aspartate-glutamate carrier 2 (AGC2). If the main substrate for gluconeogenesis is an amino acid, aspartate is converted to OA via urea cycle, therefore, ammonia detoxification and gluconeogenesis are simultaneously activated. If the main substrate is lactate, OA is synthesized by cytosolic AST, glutamate is transported to the mitochondria through AGC2, and nitrogen is not lost. It is concluded that, compared to malate, aspartate is a more suitable form of OA transport from the mitochondria for gluconeogenesis.

Keywords:  AGC2; Citrin; Mitochondrial carriers; Oxaloacetate; Urea cycle

DOI:  https://doi.org/10.1016/j.metabol.2023.155614
Nat Commun. 2023 Jun 05. 14(1): 3265

ACL and HAT1 form a nuclear module to acetylate histone H4K5 and promote cell proliferation.

Qiutao Xu, Yaping Yue, Biao Liu, Zhengting Chen, Xuan Ma, Jing Wang, Yu Zhao, Dao-Xiu Zhou.

Acetyl-CoA utilized by histone acetyltransferases (HAT) for chromatin modification is mainly generated by ATP-citrate lyase (ACL) from glucose sources. How ACL locally establishes acetyl-CoA production for histone acetylation remains unclear. Here we show that ACL subunit A2 (ACLA2) is present in nuclear condensates, is required for nuclear acetyl-CoA accumulation and acetylation of specific histone lysine residues, and interacts with Histone AcetylTransferase1 (HAT1) in rice. The rice HAT1 acetylates histone H4K5 and H4K16 and its activity on H4K5 requires ACLA2. Mutations of rice ACLA2 and HAT1 (HAG704) genes impair cell division in developing endosperm, result in decreases of H4K5 acetylation at largely the same genomic regions, affect the expression of similar sets of genes, and lead to cell cycle S phase stagnation in the endosperm dividing nuclei. These results indicate that the HAT1-ACLA2 module selectively promotes histone lysine acetylation in specific genomic regions and unravel a mechanism of local acetyl-CoA production which couples energy metabolism with cell division.

DOI: https://doi.org/10.1038/s41467-023-39101-4
Proc Natl Acad Sci U S A. 2023 Jun 13. 120(24): e2305245120

Tumor cell-derived spermidine is an oncometabolite that suppresses TCR clustering for intratumoral CD8+ T cell activation.

Sana Hibino, Shotaro Eto, Sho Hangai, Keiko Endo, Sanae Ashitani, Maki Sugaya, Tsuyoshi Osawa, Tomoyoshi Soga, Tadatsugu Taniguchi, Hideyuki Yanai.

  The activation and expansion of T cells that recognize cancer cells is an essential aspect to antitumor immunity. Tumors may escape destruction by the immune system through ectopic expression of inhibitory immune ligands typically exemplified by the PD-L1/PD-1 pathway. Here, we reveal another facet of tumor evasion from T cell surveillance. By secretome profiling of necrotic tumor cells, we identified an oncometabolite spermidine as a unique inhibitor of T cell receptor (TCR) signaling. Mechanistically, spermidine causes the downregulation of the plasma membrane cholesterol levels, resulting in the suppression of TCR clustering. Using syngeneic mouse models, we show that spermidine is abundantly detected in the tumor immune microenvironment (TIME) and that administration of the polyamine synthesis inhibitor effectively enhanced CD8+ T cell-dependent antitumor responses. Further, the combination of the polyamine synthesis inhibitor with anti-PD-1 immune checkpoint antibody resulted in a much stronger antitumor immune response. This study reveals an aspect of immunosuppressive TIME, wherein spermidine functions as a metabolic T cell checkpoint that may offer a unique approach for promoting tumor immunotherapy.

Keywords:  T cell; cancer immunotherapy; cell death; oncometabolite; spermidine

DOI:  https://doi.org/10.1073/pnas.2305245120
Nat Biomed Eng. 2023 Jun 08.

Resolving sepsis-induced immunoparalysis via trained immunity by targeting interleukin-4 to myeloid cells.

David P Schrijver, Rutger J Röring, Jeroen Deckers, Anne de Dreu, Yohana C Toner, Geoffrey Prevot, Bram Priem, Jazz Munitz, Eveline G Nugraha, Yuri van Elsas, Anthony Azzun, Tom Anbergen, Laszlo A Groh, Anouk M D Becker, Carlos Pérez-Medina, Roderick S Oosterwijk, Boris Novakovic, Simone J C F M Moorlag, Aron Jansen, Peter Pickkers, Matthijs Kox, Thijs J Beldman, Ewelina Kluza, Mandy M T van Leent, Abraham J P Teunissen, Roy van der Meel, Zahi A Fayad, Leo A B Joosten, Edward A Fisher, Maarten Merkx, Mihai G Netea, Willem J M Mulder.

Immunoparalysis is a compensatory and persistent anti-inflammatory response to trauma, sepsis or another serious insult, which increases the risk of opportunistic infections, morbidity and mortality. Here, we show that in cultured primary human monocytes, interleukin-4 (IL4) inhibits acute inflammation, while simultaneously inducing a long-lasting innate immune memory named trained immunity. To take advantage of this paradoxical IL4 feature in vivo, we developed a fusion protein of apolipoprotein A1 (apoA1) and IL4, which integrates into a lipid nanoparticle. In mice and non-human primates, an intravenously injected apoA1-IL4-embedding nanoparticle targets myeloid-cell-rich haematopoietic organs, in particular, the spleen and bone marrow. We subsequently demonstrate that IL4 nanotherapy resolved immunoparalysis in mice with lipopolysaccharide-induced hyperinflammation, as well as in ex vivo human sepsis models and in experimental endotoxemia. Our findings support the translational development of nanoparticle formulations of apoA1-IL4 for the treatment of patients with sepsis at risk of immunoparalysis-induced complications.

DOI: https://doi.org/10.1038/s41551-023-01050-0
Nat Metab. 2023 Jun 05.

Metabolomics identifies the intestinal geography of microbial metabolite production.

DOI: https://doi.org/10.1038/s42255-023-00805-y
Gastroenterology. 2023 Jun 02. pii: S0016-5085(23)00814-4. [Epub ahead of print]

Hypusination Maintains Intestinal Homeostasis and Prevents Colitis and Carcinogenesis by Enhancing Aldehyde Detoxification.

Alain P Gobert, Thaddeus M Smith, Yvonne L Latour, Mohammad Asim, Daniel P Barry, Margaret M Allaman, Kamery J Williams, Kara M McNamara, Alberto G Delgado, Sarah P Short, Raghavendra G Mirmira, Kristie L Rose, Kevin L Schey, Irene Zagol-Ikapitte, Jeremy S Coleman, Olivier Boutaud, Shilin Zhao, M Blanca Piazuelo, M Kay Washington, Lori A Coburn, Keith T Wilson.

  BACKGROUND & AIMS: The amino acid hypusine, synthesized from the polyamine spermidine by the enzyme deoxyhypusine synthase (DHPS), is essential for the activity of eukaryotic translation initiation factor 5A (EIF5A). The role of hypusinated EIF5A (EIF5AHyp) remains unknown in intestinal homeostasis. Our aim was to investigate EIF5AHyp in the gut epithelium in inflammation and carcinogenesis.METHODS: We utilized human colon tissue mRNA samples and publicly-available transcriptomic datasets, tissue microarrays, and patient-derived colon organoids. Mice with intestinal epithelial-specific deletion of Dhps were investigated at baseline and in models of colitis and colon carcinogenesis.
RESULTS: We found that patients with ulcerative colitis and Crohn's disease exhibit reduced colon levels of DHPS mRNA and DHPS protein, and reduced levels of EIF5AHyp. Similarly, colonic organoids from colitis patients also show downregulated DHPS expression. Mice with intestinal epithelial-specific deletion of Dhps develop spontaneous colon hyperplasia, epithelial proliferation, crypt distortion, and inflammation. Furthermore, these mice are highly susceptible to experimental colitis and show exacerbated colon tumorigenesis when treated with a carcinogen. Transcriptomic and proteomic analysis on colonic epithelial cells demonstrated that loss of hypusination induces multiple pathways related to cancer and immune response. Moreover, we found that hypusination enhances translation of numerous enzymes involved in aldehyde detoxification, including glutathione S-transferases and aldehyde dehydrogenases. Accordingly, hypusination-deficient mice exhibit increased levels of aldehyde adducts in the colon, and their treatment with a scavenger of electrophiles reduces colitis.
CONCLUSIONS: Hypusination in intestinal epithelial cells has a key role in prevention of colitis and colorectal cancer, and enhancement of this pathway via supplementation of spermidine could have therapeutic impact.

Keywords:  Colon cancer; Hypusine; Inflammation; Intestinal epithelial cells

DOI:  https://doi.org/10.1053/j.gastro.2023.05.041
Glia. 2023 Jun 05.

Expression and subcellular localization of mitochondrial docking protein, syntaphilin, in oligodendrocytes and CNS myelin sheath.

Diane S Nakamura, Jean-David M Gothié, Samantha F Kornfeld, Rashmi Kothary, Timothy E Kennedy.

  Oligodendrocytes produce lipid-rich myelin sheaths that provide metabolic support to the underlying axon and facilitate saltatory conduction. Oligodendrocyte mitochondria supply the bulk of energy and carbon-chain backbones required for lipid synthesis. The sparsity of mitochondria in the myelin sheath suggests that tight regulation of mitochondrial trafficking is crucial for their efficient distribution in the cell. In particular, retention of mitochondria at axoglial junctions would support local lipid synthesis and membrane remodeling during myelination. How mitochondrial docking in oligodendrocytes is regulated is not known. Our findings indicate that syntaphilin (SNPH), a mitochondrial docking protein that has been characterized in neurons, is expressed by oligodendrocyte precursor cells (OPCs) and mature oligodendrocytes in vitro and present in the myelin sheath in vivo. We have previously reported that bath application of netrin-1 promotes the elaboration of myelin basic protein-positive membranes, and that localized presentation of a netrin-1 coated microbead results in rapid accumulation of mitochondria at the site of oligodendrocyte-bead adhesion. Here we show that netrin-1 increases the redistribution of SNPH to oligodendrocyte processes during the expansion of myelin basic protein-positive membranes and that SNPH clusters at the oligodendrocyte plasma membrane at sites of adhesion with netrin-1-coated beads where mitochondria are retained. These findings suggest roles for SNPH in oligodendrocytes regulating netrin-1-mediated mitochondrial docking and myelin membrane expansion.

Keywords:  docking; mitochondria; myelin; netrin; oligodendrocyte; syntaphilin; trafficking

DOI:  https://doi.org/10.1002/glia.24425
STAR Protoc. 2023 Jun 02. pii: S2666-1667(23)00300-3. [Epub ahead of print]4(2): 102333

Generation of liver mesenchyme and ductal cell organoid co-culture using cell self-aggregation and droplet microfluidics.

Anna M Dowbaj, Timo N Kohler, Lucía Cordero-Espinoza, Florian Hollfelder, Meritxell Huch.

  Within the peri-portal region of the adult liver, portal fibroblasts exist in close proximity to epithelial ductal/cholangiocyte cells. However, the cellular interactions between them are poorly understood. Here, we provide two co-culture techniques to incorporate liver portal mesenchyme into ductal cell organoids, which recapitulate aspects of their cellular interactions in vitro. We integrate several techniques from mesenchyme isolation and expansion to co-culture by microfluidic cell co-encapsulation or 2D-Matrigel layer. The protocol is easily adaptable to other cells from other organs. For complete information on the generation and use of this protocol, please refer to Cordero-Espinoza et al.1.

Keywords:  Cell Biology; Organoids; Stem Cells

DOI:  https://doi.org/10.1016/j.xpro.2023.102333
Proc Natl Acad Sci U S A. 2023 Jun 13. 120(24): e2213241120

A molecular rotor FLIM probe reveals dynamic coupling between mitochondrial inner membrane fluidity and cellular respiration.

Gaurav Singh, Geen George, Sufi O Raja, Ponnuvel Kandaswamy, Manoj Kumar, Shashi Thutupalli, Sunil Laxman, Akash Gulyani.

  The inner mitochondrial membrane (IMM), housing components of the electron transport chain (ETC), is the site for respiration. The ETC relies on mobile carriers; therefore, it has long been argued that the fluidity of the densely packed IMM can potentially influence ETC flux and cell physiology. However, it is unclear if cells temporally modulate IMM fluidity upon metabolic or other stimulation. Using a photostable, red-shifted, cell-permeable molecular-rotor, Mitorotor-1, we present a multiplexed approach for quantitatively mapping IMM fluidity in living cells. This reveals IMM fluidity to be linked to cellular-respiration and responsive to stimuli. Multiple approaches combining in vitro experiments and live-cell fluorescence (FLIM) lifetime imaging microscopy (FLIM) show Mitorotor-1 to robustly report IMM 'microviscosity'/fluidity through changes in molecular free volume. Interestingly, external osmotic stimuli cause controlled swelling/compaction of mitochondria, thereby revealing a graded Mitorotor-1 response to IMM microviscosity. Lateral diffusion measurements of IMM correlate with microviscosity reported via Mitorotor-1 FLIM-lifetime, showing convergence of independent approaches for measuring IMM local-order. Mitorotor-1 FLIM reveals mitochondrial heterogeneity in IMM fluidity; between-and-within cells and across single mitochondrion. Multiplexed FLIM lifetime imaging of Mitorotor-1 and NADH autofluorescence reveals that IMM fluidity positively correlates with respiration, across individual cells. Remarkably, we find that stimulating respiration, through nutrient deprivation or chemically, also leads to increase in IMM fluidity. These data suggest that modulating IMM fluidity supports enhanced respiratory flux. Our study presents a robust method for measuring IMM fluidity and suggests a dynamic regulatory paradigm of modulating IMM local order on changing metabolic demand.

Keywords:  fluidity; fluorescence lifetime; fluorescent probe; metabolism; mitochondria

DOI:  https://doi.org/10.1073/pnas.2213241120
Mol Biol Cell. 2023 Jun 07. mbcE23020042

Role of 2-hydroxy acyl-CoA lyase HACL2 in odd-chain fatty acid production via α-oxidation in vivo.

Keisuke Mori, Tatsuro Naganuma, Akio Kihara.

Although most fatty acids (FAs) are even chain, certain tissues, including brain, contain relatively large quantities of odd-chain FAs in their sphingolipids. One of the pathways producing odd-chain FAs is the α-oxidation of 2-hydroxy (2-OH) FAs, where 2-OH acyl-CoA lyases (HACL1 and HACL2) catalyze the key cleavage reaction. However, the contribution of each HACL to odd-chain FA production in vivo remains unknown. Here, we found that HACL2 and HACL1 play major roles in the α-oxidation of 2-OH FAs (especially very-long-chain types) and 3-methyl FAs (other α-oxidation substrates), respectively, using ectopic expression systems of human HACL2 and HACL1 in yeast and analyzing Hacl1 and/or Hacl2 knockout (KO) CHO-K1 cells. We then generated Hacl2 KO mice and measured the quantities of odd-chain and 2-OH lipids (free FAs and sphingolipids [ceramides, sphingomyelins, and monohexosylceramides]) in 17 tissues. We observed fewer odd-chain lipids and more 2-OH lipids in many tissues of Hacl2 KO mice than in wild-type mice, and of these differences the reductions were most prominent for odd-chain monohexosylceramides in the brain and ceramides in the stomach. These results indicate that HACL2-involved α-oxidation of 2-OH FAs is mainly responsible for odd-chain FA production in the brain and stomach.

DOI: https://doi.org/10.1091/mbc.E23-02-0042
Cell Rep. 2023 Jun 06. pii: S2211-1247(23)00628-9. [Epub ahead of print]42(6): 112617

Resolvin D1 reprograms energy metabolism to promote microglia to phagocytize neutrophils after ischemic stroke.

Lei Li, Shu-Qi Cheng, Yu-Qin Sun, Jian-Bing Yu, Xin-Xin Huang, Yin-Feng Dong, Juan Ji, Xi-Yue Zhang, Gang Hu, Xiu-Lan Sun.

  Neutrophil aggregation and clearance are important factors affecting neuroinflammatory injury during acute ischemic stroke. Emerging evidence suggests that energy metabolism is essential for microglial functions, especially microglial phagocytosis, which determines the degree of brain injury. Here, we demonstrate that Resolvin D1 (RvD1), a lipid mediator derived from docosahexaenic acid (DHA), promotes the phagocytosis of neutrophils by microglia, thereby reducing neutrophil accumulation in the brain and alleviating neuroinflammation in the ischemic brain. Further studies reveal that RvD1 reprograms energy metabolism from glycolysis to oxidative phosphorylation (OXPHOS), providing sufficient energy for microglial phagocytosis. Moreover, RvD1 enhances microglial glutamine uptake and stimulates glutaminolysis to support OXPHOS to boost ATP production depending on adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) activation. Overall, our results reveal that RvD1 reprograms energy metabolism to promote the microglial phagocytosis of neutrophils after ischemic stroke. These findings may guide perspectives for stroke therapy from modulating microglial immunometabolism.

Keywords:  CP: Immunology; Resolvin D1; immunometabolism; ischemic stroke; microglia; neutrophil; phagocytosis; reprogram energy metabolism

DOI:  https://doi.org/10.1016/j.celrep.2023.112617
iScience. 2023 Jun 16. 26(6): 106895

Genetic deletion of skeletal muscle iPLA2γ results in mitochondrial dysfunction, muscle atrophy and alterations in whole-body energy metabolism.

Sung Ho Moon, Beverly Gibson Dilthey, Shaoping Guan, Harold F Sims, Sara K Pittman, Amy L Keith, Christopher M Jenkins, Conrad C Weihl, Richard W Gross.

  Skeletal muscle is the major site of glucose utilization in mammals integrating serum glucose clearance with mitochondrial respiration. To mechanistically elucidate the roles of iPLA2γ in skeletal muscle mitochondria, we generated a skeletal muscle-specific calcium-independent phospholipase A2γ knockout (SKMiPLA2γKO) mouse. Genetic ablation of skeletal muscle iPLA2γ resulted in pronounced muscle weakness, muscle atrophy, and increased blood lactate resulting from defects in mitochondrial function impairing metabolic processing of pyruvate and resultant bioenergetic inefficiency. Mitochondria from SKMiPLA2γKO mice were dysmorphic displaying marked changes in size, shape, and interfibrillar juxtaposition. Mitochondrial respirometry demonstrated a marked impairment in respiratory efficiency with decreases in the mass and function of oxidative phosphorylation complexes and cytochrome c. Further, a pronounced decrease in mitochondrial membrane potential and remodeling of cardiolipin molecular species were prominent. Collectively, these alterations prevented body weight gain during high-fat feeding through enhanced glucose disposal without efficient capture of chemical energy thereby altering whole-body bioenergetics.

Keywords:  Cell biology; Cellular physiology; Physiology

DOI:  https://doi.org/10.1016/j.isci.2023.106895
Cells Dev. 2023 Jun 05. pii: S2667-2901(23)00037-2. [Epub ahead of print] 203861

Differentiation tracing identifies hematopoietic regeneration from multipotent progenitors but not stem cells.

Tamar Nizharadze, Katrin Busch, Ann-Kathrin Fanti, Hans-Reimer Rodewald, Thomas Höfer.

  Hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) generate the immune system in development, and contribute to its maintenance under steady state conditions. How stem and progenitor cells respond to increased demand for mature cells upon injury is a fundamental question of stem cell biology. Several studies of murine hematopoiesis have reported increased proliferation of HSCs in situ when exposed to inflammatory stimuli, which has been taken as a proxy for increased HSC differentiation. Such surplus generation of HSC may fuel enhanced HSC differentiation or, alternatively, maintain HSC cellularity in the face of increased cell death without enhanced HSC differentiation. This key question calls for direct measurements of HSC differentiation in their natural niches in vivo. Here, we review work that quantifies native HSC differentiation by fate mapping and mathematical inference. Recent differentiation tracing studies show that HSC do not increase their differentiation rate upon a wide range of challenges, including systemic bacterial infection (sepsis), blood loss, and transient or persistent ablation of specific mature immune cells. By contrast, MPPs differentiate more rapidly in response to systemic infection to accelerate the production of myeloid cells. These new in vivo data identify MPPs as a major source of hematopoietic regeneration while HSCs might not contribute to regeneration while remaining protected.

Keywords:  Differentiation rate; Fate mapping; Hematopoiesis; Mathematical modeling; Stress; sepsis

DOI:  https://doi.org/10.1016/j.cdev.2023.203861
Proc Natl Acad Sci U S A. 2023 Jun 13. 120(24): e2216310120

ROS signaling-induced mitochondrial Sgk1 expression regulates epithelial cell renewal.

Yingxiang Li, Chengdong Liu, Luke Rolling, Veronica Sikora, Zhimin Chen, Jack Gurwin, Caroline Barabell, Jiandie Lin, Cunming Duan.

  Many types of differentiated cells can reenter the cell cycle upon injury or stress. The underlying mechanisms are still poorly understood. Here, we investigated how quiescent cells are reactivated using a zebrafish model, in which a population of differentiated epithelial cells are reactivated under a physiological context. A robust and sustained increase in mitochondrial membrane potential was observed in the reactivated cells. Genetic and pharmacological perturbations show that elevated mitochondrial metabolism and ATP synthesis are critical for cell reactivation. Further analyses showed that elevated mitochondrial metabolism increases mitochondrial ROS levels, which induces Sgk1 expression in the mitochondria. Genetic deletion and inhibition of Sgk1 in zebrafish abolished epithelial cell reactivation. Similarly, ROS-dependent mitochondrial expression of SGK1 promotes S phase entry in human breast cancer cells. Mechanistically, SGK1 coordinates mitochondrial activity with ATP synthesis by phosphorylating F1Fo-ATP synthase. These findings suggest a conserved intramitochondrial signaling loop regulating epithelial cell renewal.

Keywords:  F1Fo-ATP synthase; IGF/insulin signaling; mitochondrial membrane potential; reactive oxygen species; serum- and glucocorticoid-regulated kinase 1

DOI:  https://doi.org/10.1073/pnas.2216310120
Cell Rep. 2023 Jun 07. pii: S2211-1247(23)00627-7. [Epub ahead of print]42(6): 112616

Endogenous PP2A inhibitor CIP2A degradation by chaperone-mediated autophagy contributes to the antitumor effect of mitochondrial complex I inhibition.

Riccardo Cazzoli, Francesco Romeo, Isabella Pallavicini, Sebastiano Peri, Mauro Romanenghi, Juan Alberto Pérez-Valencia, Eman Hagag, Filippo Ferrucci, Mohamed Elgendy, Orazio Vittorio, Salvatore Pece, Marco Foiani, Jukka Westermarck, Saverio Minucci.

  Combined inhibition of oxidative phosphorylation (OXPHOS) and glycolysis has been shown to activate a PP2A-dependent signaling pathway, leading to tumor cell death. Here, we analyze highly selective mitochondrial complex I or III inhibitors in vitro and in vivo to elucidate the molecular mechanisms leading to cell death following OXPHOS inhibition. We show that IACS-010759 treatment (complex I inhibitor) induces a reactive oxygen species (ROS)-dependent dissociation of CIP2A from PP2A, leading to its destabilization and degradation through chaperone-mediated autophagy. Mitochondrial complex III inhibition has analogous effects. We establish that activation of the PP2A holoenzyme containing B56δ regulatory subunit selectively mediates tumor cell death, while the arrest in proliferation that is observed upon IACS-010759 treatment does not depend on the PP2A-B56δ complex. These studies provide a molecular characterization of the events subsequent to the alteration of critical bioenergetic pathways and help to refine clinical studies aimed to exploit metabolic vulnerabilities of tumor cells.

Keywords:  CIP2A; CP: Cancer; CP: Molecular biology; OXPHOS; PP2A; cancer; chaperone-mediated autophagy; fasting; glycolysis; metabolism

DOI:  https://doi.org/10.1016/j.celrep.2023.112616
Cell Host Microbe. 2023 May 29. pii: S1931-3128(23)00201-9. [Epub ahead of print]

Identification of host regulators of Mycobacteriumtuberculosis phenotypes uncovers a role for the MMGT1-GPR156 lipid droplet axis in persistence.

Haroon Kalam, Chih-Hung Chou, Motohiko Kadoki, Daniel B Graham, Jacques Deguine, Deborah T Hung, Ramnik J Xavier.

  The ability of Mycobacterium tuberculosis (Mtb) to establish latency affects disease and response to treatment. The host factors that influence the establishment of latency remain elusive. We engineered a multi-fluorescent Mtb strain that reports survival, active replication, and stressed non-replication states and determined the host transcriptome of the infected macrophages in these states. Additionally, we conducted a genome-wide CRISPR screen to identify host factors that modulated the phenotypic state of Mtb. We validated hits in a phenotype-specific manner and prioritized membrane magnesium transporter 1 (MMGT1) for a detailed mechanistic investigation. Mtb infection of MMGT1-deficient macrophages promoted a switch to persistence, upregulated lipid metabolism genes, and accumulated lipid droplets during infection. Targeting triacylglycerol synthesis reduced both droplet formation and Mtb persistence. The orphan G protein-coupled receptor GPR156 is a key inducer of droplet accumulation in ΔMMGT1 cells. Our work uncovers the role of MMGT1-GPR156-lipid droplets in the induction of Mtb persistence.

Keywords:  CRISPR screen; Mycobacterium tuberculosis; RNA-seq; fatty acid biosynthesis; host response to infection; lipid droplets; macrophages; phenotype switching; phenotypic states

DOI:  https://doi.org/10.1016/j.chom.2023.05.009
J Biol Chem. 2023 Jun 01. pii: S0021-9258(23)01908-7. [Epub ahead of print] 104880

Redundant electrostatic interactions between GATOR1 and the Rag GTPase heterodimer drives efficient amino acid sensing in human cells.

Dylan D Doxsey, Steven D Tettoni, Shawn B Egri, Kuang Shen.

  Cells need to coordinate nutrient availability with their growth and proliferation. In eukaryotic cells, this coordination is mediated by the mechanistic target of rapamycin complex 1 (mTORC1) pathway. mTORC1 activation is regulated by two GTPase units, the Rag GTPase heterodimer and the Rheb GTPase. The RagA-RagC heterodimer controls the subcellular localization of mTORC1, and its nucleotide loading states are strictly controlled by upstream regulators including amino acid sensors. A critical negative regulator of the Rag GTPase heterodimer is GATOR1. In the absence of amino acids, GATOR1 stimulates GTP hydrolysis by the RagA subunit to turn off mTORC1 signaling. Despite the enzymatic specificity of GATOR1 to RagA, a recent cryo-EM structural model of the human GATOR1-Rag-Ragulator complex reveals an unexpected interface between Depdc5, a subunit of GATOR1, and RagC. Currently, there is no functional characterization of this interface, nor do we know its biological relevance. Here, combining structure-function analysis, enzymatic kinetic measurements, and cell-based signaling assays, we identified a critical electrostatic interaction between Depdc5 and RagC. This interaction is mediated by the positively charged Arg-1407 residue on Depdc5, and a patch of negatively charged residues on the lateral side of RagC. Abrogating this interaction impairs the GAP activity of GATOR1 and cellular response to amino acid withdrawal. Our results reveal how GATOR1 coordinates the nucleotide loading states of the Rag GTPase heterodimer, and thus precisely controls cellular behavior in the absence of amino acids.

Keywords:  GATOR1; GTPase Activating Protein; Metabolism; Rag GTPase; mTOR complex 1 (mTORC1)

DOI:  https://doi.org/10.1016/j.jbc.2023.104880
J Biol Chem. 2023 Jun 05. pii: S0021-9258(23)01918-X. [Epub ahead of print] 104890

Obesity-induced metabolic imbalance allosterically modulates CtBP2 to inhibit PPAR-alpha transcriptional activity.

Kenji Saito, Motohiro Sekiya, Kenta Kainoh, Ryunosuke Yoshino, Akio Hayashi, Song-Iee Han, Masaya Araki, Hiroshi Ohno, Yoshinori Takeuchi, Tomomi Tsuyuzaki, Daichi Yamazaki, Chen Wanpei, Lisa Hada, Sho Watanabe, Putu Indah Paramita Adi Putri, Yuki Murayama, Yoko Sugano, Yoshinori Osaki, Hitoshi Iwasaki, Naoya Yahagi, Hiroaki Suzuki, Takafumi Miyamoto, Takashi Matsuzaka, Hitoshi Shimano.

  Maintenance of metabolic homeostasis is secured by metabolite-sensing systems, which can be overwhelmed by constant macronutrient surplus in obesity. Not only the uptake processes but also the consumption of energy substrates determine the cellular metabolic burden. We herein describe a novel transcriptional system in this context comprised of peroxisome proliferator-activated receptor alpha (PPARα), a master regulator for fatty acid oxidation, and C-terminal binding protein 2 (CtBP2), a metabolite-sensing transcriptional co-repressor. CtBP2 interacts with PPARα to repress its activity, and the interaction is enhanced upon binding to malonyl-CoA, a metabolic intermediate increased in tissues in obesity and reported to suppress fatty acid oxidation through inhibition of carnitine palmitoyltransferase 1 (CPT1). In line with our preceding observations that CtBP2 adopts a monomeric configuration upon binding to acyl-CoAs, we determined that mutations in CtBP2 that shift the conformational equilibrium toward monomers increase the interaction between CtBP2 and PPARα. In contrast, metabolic manipulations that reduce malonyl-CoA decreased the formation of the CtBP2/PPARα complex. Consistent with these in vitro findings, we found that the CtBP2/PPARα interaction is accelerated in obese livers while genetic deletion of CtBP2 in the liver causes derepression of PPARα target genes. These findings support our model where CtBP2 exists primarily as a monomer in the metabolic milieu of obesity to repress PPARα, representing a liability in metabolic diseases that can be exploited to develop therapeutic approaches.

Keywords:  CtBP2; PPARα; fatty acid oxidation; malonyl-CoA; metabolite sensor

DOI:  https://doi.org/10.1016/j.jbc.2023.104890
J Biol Chem. 2023 Jun 06. pii: S0021-9258(23)01925-7. [Epub ahead of print] 104897

Free ferrous ions sustain activity of mammalian stearoyl-CoA desaturase-1.

Jiemin Shen, Gang Wu, Brad S Pierce, Ah-Lim Tsai, Ming Zhou.

  Mammalian stearoyl-CoA desaturase-1 (SCD1) introduces a double-bond to a saturated long-chain fatty acid in a reaction catalyzed by a diiron center. The diiron center is well-coordinated by conserved histidine residues and is thought to remain with the enzyme. However, we find here that SCD1 progressively loses its activity during catalysis and becomes fully inactive after nine turnovers. Further studies show that the inactivation of SCD1 is due to the loss of an iron (Fe) ion in the diiron center, and that the addition of free ferrous ions (Fe2+) sustains the enzymatic activity. Using SCD1 labeled with Fe isotope, we further show that free Fe2+ is incorporated into the diiron center only during catalysis. We also discover that the diiron center in SCD1 has prominent electron paramagnetic resonance signals in its diferric state, indicative of distinct coupling between the two ferric ions. These results reveal that the diiron center in SCD1 is structurally dynamic during catalysis and that labile Fe2+ in cells could regulate SCD1 activity, and hence lipid metabolism.

Keywords:  diiron; electron paramagnetic resonance (EPR); labile iron; lipid desaturation; metalloenzyme; stearoyl-CoA desaturase (SCD)

DOI:  https://doi.org/10.1016/j.jbc.2023.104897
Cell Metab. 2023 Jun 06. pii: S1550-4131(23)00182-1. [Epub ahead of print]35(6): 907-909

Fumarate disarms CD8+ T cells against cancer.

Luigi Nezi, Teresa Manzo.

The composition of nutrients in the tumor microenvironment is a key determinant of anti-tumor CD8+ T cell response. In this issue of Cell Metabolism, Jiang and colleagues unveil that tumor-derived fumarate dampens TCR signaling in CD8+ T cells, resulting in defective activation, loss of effector functions, and associated failure of tumor control.

DOI: https://doi.org/10.1016/j.cmet.2023.05.005
Immunol Rev. 2023 Jun 07.

Engineering the IL-4/IL-13 axis for targeted immune modulation.

Zachary J Bernstein, Anjali Shenoy, Amy Chen, Nicola M Heller, Jamie B Spangler.

  The structurally and functionally related interleukin-4 (IL-4) and IL-13 cytokines play pivotal roles in shaping immune activity. The IL-4/IL-13 axis is best known for its critical role in T helper 2 (Th2) cell-mediated Type 2 inflammation, which protects the host from large multicellular pathogens, such as parasitic helminth worms, and regulates immune responses to allergens. In addition, IL-4 and IL-13 stimulate a wide range of innate and adaptive immune cells, as well as non-hematopoietic cells, to coordinate various functions, including immune regulation, antibody production, and fibrosis. Due to its importance for a broad spectrum of physiological activities, the IL-4/IL-13 network has been targeted through a variety of molecular engineering and synthetic biology approaches to modulate immune behavior and develop novel therapeutics. Here, we review ongoing efforts to manipulate the IL-4/IL-13 axis, including cytokine engineering strategies, formulation of fusion proteins, antagonist development, cell engineering approaches, and biosensor design. We discuss how these strategies have been employed to dissect IL-4 and IL-13 pathways, as well as to discover new immunotherapies targeting allergy, autoimmune diseases, and cancer. Looking ahead, emerging bioengineering tools promise to continue advancing fundamental understanding of IL-4/IL-13 biology and enabling researchers to exploit these insights to develop effective interventions.

Keywords:  T cells; allergy; antibody; autoimmune disease; cell therapy; cytokine; dupilumab; interleukin-13; interleukin-4; protein engineering

DOI:  https://doi.org/10.1111/imr.13230
JHEP Rep. 2023 Jun;5(6): 100725

Characterisation of hepatic lipid signature distributed across the liver zonation using mass spectrometry imaging.

Patcharamon Seubnooch, Matteo Montani, Sofia Tsouka, Emmanuelle Claude, Umara Rafiqi, Aurel Perren, Jean-Francois Dufour, Mojgan Masoodi.

  Background & Aims: Lipid metabolism plays an important role in liver pathophysiology. The liver lobule asymmetrically distributes oxygen and nutrition, resulting in heterogeneous metabolic functions. Periportal and pericentral hepatocytes have different metabolic functions, which lead to generating liver zonation. We developed spatial metabolic imaging using desorption electrospray ionisation mass spectrometry to investigate lipid distribution across liver zonation with high reproducibility and accuracy.Methods: Fresh frozen livers from healthy mice with control diet were analysed using desorption electrospray ionisation mass spectrometry imaging. Imaging was performed at 50 μm × 50 μm pixel size. Regions of interest (ROIs) were manually created by co-registering with histological data to determine the spatial hepatic lipids across liver zonation. The ROIs were confirmed by double immunofluorescence. The mass list of specific ROIs was automatically created, and univariate and multivariate statistical analysis were performed to identify statistically significant lipids across liver zonation.
Results: A wide range of lipid species was identified, including fatty acids, phospholipids, triacylglycerols, diacylglycerols, ceramides, and sphingolipids. We characterised hepatic lipid signatures in three different liver zones (periportal zone, midzone, and pericentral zone) and validated the reproducibility of our method for measuring a wide range of lipids. Fatty acids were predominantly detected in the periportal region, whereas phospholipids were distributed in both the periportal and pericentral zones. Interestingly, phosphatidylinositols, PI(36:2), PI(36:3), PI(36:4), PI(38:5), and PI(40:6) were located predominantly in the midzone (zone 2). Triacylglycerols and diacylglycerols were detected mainly in the pericentral region. De novo triacylglycerol biosynthesis appeared to be the most influenced pathway across the three zones.
Conclusions: The ability to accurately assess zone-specific hepatic lipid distribution in the liver could lead to a better understanding of lipid metabolism during the progression of liver disease.
Impact and Implications: Zone-specific hepatic lipid metabolism could play an important role in lipid homoeostasis during disease progression. Herein, we defined the zone-specific references of hepatic lipid species in the three liver zones using molecular imaging. The de novo triacylglycerol biosynthesis was highlighted as the most influenced pathway across the three zones.

Keywords:  De novo triacylglycerol biosynthesis; Hepatic lipid distribution; Lipid metabolism; Liver; Liver zonation; Pathway analysis

DOI:  https://doi.org/10.1016/j.jhepr.2023.100725
Nat Cell Biol. 2023 Jun 08.

De novo pyrimidine biosynthetic complexes support cancer cell proliferation and ferroptosis defence.

Chuanzhen Yang, Yiliang Zhao, Liao Wang, Zihao Guo, Lingdi Ma, Ronghui Yang, Ying Wu, Xuexue Li, Jing Niu, Qiaoyun Chu, Yanxia Fu, Binghui Li.

De novo pyrimidine biosynthesis is achieved by cytosolic carbamoyl-phosphate synthetase II, aspartate transcarbamylase and dihydroorotase (CAD) and uridine 5'-monophosphate synthase (UMPS), and mitochondrial dihydroorotate dehydrogenase (DHODH). However, how these enzymes are orchestrated remains enigmatical. Here we show that cytosolic glutamate oxaloacetate transaminase 1 clusters with CAD and UMPS, and this complex then connects with DHODH, which is mediated by the mitochondrial outer membrane protein voltage-dependent anion-selective channel protein 3. Therefore, these proteins form a multi-enzyme complex, named 'pyrimidinosome', involving AMP-activated protein kinase (AMPK) as a regulator. Activated AMPK dissociates from the complex to enhance pyrimidinosome assembly but inactivated UMPS, which promotes DHODH-mediated ferroptosis defence. Meanwhile, cancer cells with lower expression of AMPK are more reliant on pyrimidinosome-mediated UMP biosynthesis and more vulnerable to its inhibition. Our findings reveal the role of pyrimidinosome in regulating pyrimidine flux and ferroptosis, and suggest a pharmaceutical strategy of targeting pyrimidinosome in cancer treatment.

DOI: https://doi.org/10.1038/s41556-023-01146-4
Biochem J. 2023 Jun 15. 480(11): 773-789

Mitochondrial metabolism and dynamics in pancreatic beta cell glucose sensing.

Guy A Rutter, Vaibhav Sidarala, Brett A Kaufman, Scott A Soleimanpour.

  Glucose-regulated insulin secretion becomes defective in all forms of diabetes. The signaling mechanisms through which the sugar acts on the ensemble of beta cells within the islet remain a vigorous area of research after more than 60 years. Here, we focus firstly on the role that the privileged oxidative metabolism of glucose plays in glucose detection, discussing the importance of 'disallowing' in the beta cell the expression of genes including Lactate dehydrogenase (Ldha) and the lactate transporter Mct1/Slc16a1 to restrict other metabolic fates for glucose. We next explore the regulation of mitochondrial metabolism by Ca2+ and its possible role in sustaining glucose signaling towards insulin secretion. Finally, we discuss in depth the importance of mitochondrial structure and dynamics in the beta cell, and their potential for therapeutic targeting by incretin hormones or direct regulators of mitochondrial fusion. This review, and the 2023 Sir Philip Randle Lecture which GAR will give at the Islet Study Group meeting in Vancouver, Canada in June 2023, honor the foundational, and sometimes under-appreciated, contributions made by Professor Randle and his colleagues towards our understanding of the regulation of insulin secretion.

Keywords:  diabetes; glucose homeostasis; hormone secretion; insulin; mitochondria; pancreatic beta cell

DOI:  https://doi.org/10.1042/BCJ20230167
Nature. 2023 Jun 07.

A cytosolic surveillance mechanism activates the mitochondrial UPR.

F X Reymond Sutandy, Ines Gößner, Georg Tascher, Christian Münch.

The mitochondrial unfolded protein response (UPRmt) is essential to safeguard mitochondria from proteotoxic damage by activating a dedicated transcriptional response in the nucleus to restore proteostasis1,2. Yet, it remains unclear how the information on mitochondria misfolding stress (MMS) is signalled to the nucleus as part of the human UPRmt (refs. 3,4). Here, we show that UPRmt signalling is driven by the release of two individual signals in the cytosol-mitochondrial reactive oxygen species (mtROS) and accumulation of mitochondrial protein precursors in the cytosol (c-mtProt). Combining proteomics and genetic approaches, we identified that MMS causes the release of mtROS into the cytosol. In parallel, MMS leads to mitochondrial protein import defects causing c-mtProt accumulation. Both signals integrate to activate the UPRmt; released mtROS oxidize the cytosolic HSP40 protein DNAJA1, which leads to enhanced recruitment of cytosolic HSP70 to c-mtProt. Consequently, HSP70 releases HSF1, which translocates to the nucleus and activates transcription of UPRmt genes. Together, we identify a highly controlled cytosolic surveillance mechanism that integrates independent mitochondrial stress signals to initiate the UPRmt. These observations reveal a link between mitochondrial and cytosolic proteostasis and provide molecular insight into UPRmt signalling in human cells.

DOI: https://doi.org/10.1038/s41586-023-06142-0
Nat Metab. 2023 Jun 05.

The incretin co-agonist tirzepatide requires GIPR for hormone secretion from human islets.

Kimberley El, Jonathan D Douros, Francis S Willard, Aaron Novikoff, Ashot Sargsyan, Diego Perez-Tilve, David B Wainscott, Bin Yang, Alex Chen, Donald Wothe, Callum Coupland, Mattias H Tschöp, Brian Finan, David A D'Alessio, Kyle W Sloop, Timo D Müller, Jonathan E Campbell.

The incretins glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) mediate insulin responses that are proportionate to nutrient intake to facilitate glucose tolerance1. The GLP-1 receptor (GLP-1R) is an established drug target for the treatment of diabetes and obesity2, whereas the therapeutic potential of the GIP receptor (GIPR) is a subject of debate. Tirzepatide is an agonist at both the GIPR and GLP-1R and is a highly effective treatment for type 2 diabetes and obesity3,4. However, although tirzepatide activates GIPR in cell lines and mouse models, it is not clear whether or how dual agonism contributes to its therapeutic benefit. Islet beta cells express both the GLP-1R and the GIPR, and insulin secretion is an established mechanism by which incretin agonists improve glycemic control5. Here, we show that in mouse islets, tirzepatide stimulates insulin secretion predominantly through the GLP-1R, owing to reduced potency at the mouse GIPR. However, in human islets, antagonizing GIPR activity consistently decreases the insulin response to tirzepatide. Moreover, tirzepatide enhances glucagon secretion and somatostatin secretion in human islets. These data demonstrate that tirzepatide stimulates islet hormone secretion from human islets through both incretin receptors.

DOI: https://doi.org/10.1038/s42255-023-00811-0
Nat Commun. 2023 Jun 03. 14(1): 3214

Lysophosphatidic acid modulates CD8 T cell immunosurveillance and metabolism to impair anti-tumor immunity.

Jacqueline A Turner, Malia A Fredrickson, Marc D'Antonio, Elizabeth Katsnelson, Morgan MacBeth, Robert Van Gulick, Tugs-Saikhan Chimed, Martin McCarter, Angelo D'Alessandro, William A Robinson, Kasey L Couts, Roberta Pelanda, Jared Klarquist, Richard P Tobin, Raul M Torres.

Lysophosphatidic acid (LPA) is a bioactive lipid which increases in concentration locally and systemically across different cancer types. Yet, the exact mechanism(s) of how LPA affects CD8 T cell immunosurveillance during tumor progression remain unknown. We show LPA receptor (LPAR) signaling by CD8 T cells promotes tolerogenic states via metabolic reprogramming and potentiating exhaustive-like differentiation to modulate anti-tumor immunity. We found LPA levels predict response to immunotherapy and Lpar5 signaling promotes cellular states associated with exhausted phenotypes on CD8 T cells. Importantly, we show that Lpar5 regulates CD8 T cell respiration, proton leak, and reactive oxygen species. Together, our findings reveal that LPA serves as a lipid-regulated immune checkpoint by modulating metabolic efficiency through LPAR5 signaling on CD8 T cells. Our study offers key insights into the mechanisms governing adaptive anti-tumor immunity and demonstrates LPA could be exploited as a T cell directed therapy to improve dysfunctional anti-tumor immunity.

DOI: https://doi.org/10.1038/s41467-023-38933-4