bims-mepmim 2024-09-08 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2024–09–08
33 papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

MOF-mediated PRDX1 acetylation regulates inflammatory macrophage activation.
A 2-hydroxybutyrate-mediated feedback loop regulates muscular fatigue.
Global 13C tracing and metabolic flux analysis of intact human liver tissue ex vivo.
Perturbations in mitochondrial metabolism associated with defective cardiolipin biosynthesis: An in-organello real-time NMR study.
Molecular insights into human phosphatidylserine synthase 1 reveal its inhibition promotes LDL uptake.
Mitochondrial transplants to treat mitochondrial dysfunction.
PD-1 signaling limits expression of phospholipid phosphatase 1 and promotes intratumoral CD8+ T cell ferroptosis.
Succinate activates UCP2 to suppress neuroinflammation and confer protection following intracerebral hemorrhage.
Foxk1 promotes bone formation through inducing aerobic glycolysis.
Retinal perivascular macrophages regulate immune cell infiltration during neuroinflammation in mouse models of ocular disease.
Identification of SLC25A46 interaction interfaces with mitochondrial membrane fusogens Opa1 and Mfn2.
Metabolic immaturity and breastmilk bile acid metabolites are central determinants of heightened newborn vulnerability to norovirus diarrhea.
Lipidomics of infant mesenchymal stem cells associate with the maternal milieu and child adiposity.
Aldehydes alter TGF-β signaling and induce obesity and cancer.
Combinatorial targeting of glutamine metabolism and lysosomal-based lipid metabolism effectively suppresses glioblastoma.
Alternating high-fat diet enhances atherosclerosis by neutrophil reprogramming.
Early intermittent hyperlipidaemia alters tissue macrophages to fuel atherosclerosis.
Biosynthesis of resolvin D1, resolvin D2, and RCTR1 from 7,8(S,S)-epoxytetraene in human neutrophils and macrophages.
Inhibitory co-receptor Lag3 supports Foxp3+ regulatory T cell function by restraining Myc-dependent metabolic programming.
Pharmacologic LDH inhibition redirects intratumoral glucose uptake and improves antitumor immunity in solid tumor models.
α-Ketoglutarate promotes cardiomyocyte proliferation and heart regeneration after myocardial infarction.
Modification in mitochondrial function is associated with the FADS1 variant and its interaction with alpha-linolenic acid-enriched diet - an exploratory study.
In vivo CRISPR screens identify a dual function of MEN1 in regulating tumor-microenvironment interactions.
Spatially structured exchange of metabolites enhances bacterial survival and resilience in biofilms.
Adipocyte deletion of the oxygen-sensor PHD2 sustains elevated energy expenditure at thermoneutrality.
The prognostic effect of infiltrating immune cells is shaped by proximal M2 macrophages in lung adenocarcinoma.
EPAS1 Attenuates Atherosclerosis Initiation at Disturbed Flow Sites Through Endothelial Fatty Acid Uptake.
Hepatocyte-derived tissue extracellular vesicles safeguard liver regeneration and support regenerative therapy.
Phospholipid scrambling induced by an ion channel/metabolite transporter complex.
SDHAF2 facilitates mitochondrial respiration through stabilizing succinate dehydrogenase and cytochrome c oxidase assemblies.
SREBP-dependent regulation of lipid homeostasis is required for progression and growth of pancreatic ductal adenocarcinoma.
Spatially resolved analysis of pancreatic cancer identifies therapy-associated remodeling of the tumor microenvironment.
Structural insight into synergistic activation of human 3-methylcrotonyl-CoA carboxylase.

Cell Rep. 2024 Aug 28. pii: S2211-1247(24)01033-7. [Epub ahead of print]43(9): 114682

MOF-mediated PRDX1 acetylation regulates inflammatory macrophage activation.

Hui-Ru Chen, Yidan Sun, Gerhard Mittler, Tobias Rumpf, Maria Shvedunova, Rudolf Grosschedl, Asifa Akhtar.

  Signaling-dependent changes in protein phosphorylation are critical to enable coordination of transcription and metabolism during macrophage activation. However, the role of acetylation in signal transduction during macrophage activation remains obscure. Here, we identify the redox signaling regulator peroxiredoxin 1 (PRDX1) as a substrate of the lysine acetyltransferase MOF. MOF acetylates PRDX1 at lysine 197, preventing hyperoxidation and thus maintaining its activity under stress. PRDX1 K197ac responds to inflammatory signals, decreasing rapidly in mouse macrophages stimulated with bacterial lipopolysaccharides (LPSs) but not with interleukin (IL)-4 or IL-10. The LPS-induced decrease of PRDX1 K197ac elevates cellular hydrogen peroxide accumulation and augments ERK1/2, but not p38 or AKT, phosphorylation. Concomitantly, diminished PRDX1 K197ac stimulates glycolysis, potentiates H3 serine 28 phosphorylation, and ultimately enhances the production of pro-inflammatory mediators such as IL-6. Our work reveals a regulatory role for redox protein acetylation in signal transduction and coordinating metabolic and transcriptional programs during inflammatory macrophage activation.

Keywords:  CP: Immunology; CP: Molecular biology; ERK1/2; MAPK; glycolytic metabolism; histone H3 serine 28 phosphorylation; lysine acetyltransferase MOF; macrophage activation; peroxiredoxin; protein acetylation; redox signaling; signal transduction

DOI:  https://doi.org/10.1016/j.celrep.2024.114682
Elife. 2024 Sep 03. pii: RP92707. [Epub ahead of print]12

A 2-hydroxybutyrate-mediated feedback loop regulates muscular fatigue.

Brennan J Wadsworth, Marina Leiwe, Eleanor A Minogue, Pedro P Cunha, Viktor Engman, Carolin Brombach, Christos Asvestis, Shiv K Sah-Teli, Emilia Marklund, Peppi Karppinen, Jorge L Ruas, Helene Rundqvist, Johanna T Lanner, Randall S Johnson.

  Several metabolites have been shown to have independent and at times unexpected biological effects outside of their metabolic pathways. These include succinate, lactate, fumarate, and 2-hydroxyglutarate. 2-Hydroxybutyrate (2HB) is a byproduct of endogenous cysteine synthesis, produced during periods of cellular stress. 2HB rises acutely after exercise; it also rises during infection and is also chronically increased in a number of metabolic disorders. We show here that 2HB inhibits branched-chain aminotransferase enzymes, which in turn triggers a SIRT4-dependent shift in the compartmental abundance of protein ADP-ribosylation. The 2HB-induced decrease in nuclear protein ADP-ribosylation leads to a C/EBPβ-mediated transcriptional response in the branched-chain amino acid degradation pathway. This response to 2HB exposure leads to an improved oxidative capacity in vitro. We found that repeated injection with 2HB can replicate the improvement to oxidative capacity that occurs following exercise training. Together, we show that 2-HB regulates fundamental aspects of skeletal muscle metabolism.

Keywords:  Exercise; biochemistry; chemical biology; metabolite; mouse; muscle fiber

DOI:  https://doi.org/10.7554/eLife.92707
Nat Metab. 2024 Aug 29.

Global 13C tracing and metabolic flux analysis of intact human liver tissue ex vivo.

Nina Grankvist, Cecilia Jönsson, Karin Hedin, Nicolas Sundqvist, Per Sandström, Bergthor Björnsson, Arjana Begzati, Evgeniya Mickols, Per Artursson, Mohit Jain, Gunnar Cedersund, Roland Nilsson.

Liver metabolism is central to human physiology and influences the pathogenesis of common metabolic diseases. Yet, our understanding of human liver metabolism remains incomplete, with much of current knowledge based on animal or cell culture models that do not fully recapitulate human physiology. Here, we perform in-depth measurement of metabolism in intact human liver tissue ex vivo using global 13C tracing, non-targeted mass spectrometry and model-based metabolic flux analysis. Isotope tracing allowed qualitative assessment of a wide range of metabolic pathways within a single experiment, confirming well-known features of liver metabolism but also revealing unexpected metabolic activities such as de novo creatine synthesis and branched-chain amino acid transamination, where human liver appears to differ from rodent models. Glucose production ex vivo correlated with donor plasma glucose, suggesting that cultured liver tissue retains individual metabolic phenotypes, and could be suppressed by postprandial levels of nutrients and insulin, and also by pharmacological inhibition of glycogen utilization. Isotope tracing ex vivo allows measuring human liver metabolism with great depth and resolution in an experimentally tractable system.

DOI: https://doi.org/10.1038/s42255-024-01119-3
J Biol Chem. 2024 Sep 03. pii: S0021-9258(24)02247-6. [Epub ahead of print] 107746

Perturbations in mitochondrial metabolism associated with defective cardiolipin biosynthesis: An in-organello real-time NMR study.

Antonio J Rua, Wayne Mitchell, Steven M Claypool, Nathan N Alder, Andrei T Alexandrescu.

  Mitochondria are central to cellular metabolism; hence, their dysfunction contributes to a wide array of human diseases. Cardiolipin, the signature phospholipid of the mitochondrion, affects proper cristae morphology, bioenergetic functions, and metabolic reactions carried out in mitochondrial membranes. To match tissue-specific metabolic demands, cardiolipin typically undergoes an acyl tail remodeling process with the final step carried out by the phospholipid-lysophospholipid transacylase tafazzin. Mutations in tafazzin are the primary cause of Barth syndrome. Here, we investigated how defects in cardiolipin biosynthesis and remodeling impacts metabolic flux through the TCA cycle and associated yeast pathways. Nuclear magnetic resonance was used to monitor in real-time the metabolic fate of 13C3-pyruvate in isolated mitochondria from three isogenic yeast strains. We compared mitochondria from a wild-type strain to mitochondria from a Δtaz1 strain that lacks tafazzin and contains lower amounts of unremodeled cardiolipin, and mitochondria from a Δcrd1 strain that lacks cardiolipin synthase and cannot synthesize cardiolipin. We found that the 13C-label from the pyruvate substrate was distributed through twelve metabolites. Several of the metabolites were specific to yeast pathways including branched chain amino acids and fusel alcohol synthesis. While most metabolites showed similar kinetics amongst the different strains, mevalonate concentrations were significantly increased in Δtaz1 mitochondria. Additionally, the kinetic profiles of α-ketoglutarate, as well as NAD+ and NADH measured in separate experiments, displayed significantly lower concentrations for Δtaz1 and Δcrd1 mitochondria at most time points. Taken together, the results show how cardiolipin remodeling influences pyruvate metabolism, tricarboxylic acid cycle flux, and the levels of mitochondrial nucleotides.

Keywords:  3-methylglutaconic acid (3MGA); Barth syndrome (BTHS); Krebs cycle; adenosine triphosphate (ATP); metabolic disease; mitochondrial respiration; nuclear magnetic resonance (NMR); tricarboxylic acid (TCA) cycle

DOI:  https://doi.org/10.1016/j.jbc.2024.107746
Cell. 2024 Aug 27. pii: S0092-8674(24)00895-X. [Epub ahead of print]

Molecular insights into human phosphatidylserine synthase 1 reveal its inhibition promotes LDL uptake.

Tao Long, Dongyu Li, Goncalo Vale, Yaoyukun Jiang, Philip Schmiege, Zhongyue J Yang, Jeffrey G McDonald, Xiaochun Li.

  In mammalian cells, two phosphatidylserine (PS) synthases drive PS synthesis. Gain-of-function mutations in the Ptdss1 gene lead to heightened PS production, causing Lenz-Majewski syndrome (LMS). Recently, pharmacological inhibition of PSS1 has been shown to suppress tumorigenesis. Here, we report the cryo-EM structures of wild-type human PSS1 (PSS1WT), the LMS-causing Pro269Ser mutant (PSS1P269S), and PSS1WT in complex with its inhibitor DS55980254. PSS1 contains 10 transmembrane helices (TMs), with TMs 4-8 forming a catalytic core in the luminal leaflet. These structures revealed a working mechanism of PSS1 akin to the postulated mechanisms of the membrane-bound O-acyltransferase family. Additionally, we showed that both PS and DS55980254 can allosterically inhibit PSS1 and that inhibition by DS55980254 activates the SREBP pathways, thus enhancing the expression of LDL receptors and increasing cellular LDL uptake. This work uncovers a mechanism of mammalian PS synthesis and suggests that selective PSS1 inhibitors have the potential to lower blood cholesterol levels.

Keywords:  DS55980254; LDL; LDL receptors; MBOAT; PSS1; cholesterol trafficking; phosphatidylserine

DOI:  https://doi.org/10.1016/j.cell.2024.08.004
Nat Metab. 2024 Sep 02.

Mitochondrial transplants to treat mitochondrial dysfunction.

Alessandro Bitto.

DOI: https://doi.org/10.1038/s42255-024-01124-6
Immunity. 2024 Aug 22. pii: S1074-7613(24)00376-5. [Epub ahead of print]

PD-1 signaling limits expression of phospholipid phosphatase 1 and promotes intratumoral CD8+ T cell ferroptosis.

Yu Ping, Jiqi Shan, Haiming Qin, Feng Li, Jiao Qu, Ru Guo, Dong Han, Wei Jing, Yaqing Liu, Jinyan Liu, Zhangnan Liu, Jieyao Li, Dongli Yue, Feng Wang, Liping Wang, Bin Zhang, Bo Huang, Yi Zhang.

  The tumor microenvironment (TME) promotes metabolic reprogramming and dysfunction in immune cells. Here, we examined the impact of the TME on phospholipid metabolism in CD8+ T cells. In lung cancer, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were lower in intratumoral CD8+ T cells than in circulating CD8+ T cells. Intratumoral CD8+ T cells exhibited decreased expression of phospholipid phosphatase 1 (PLPP1), which catalyzes PE and PC synthesis. T cell-specific deletion of Plpp1 impaired antitumor immunity and promoted T cell death by ferroptosis. Unsaturated fatty acids in the TME stimulated ferroptosis of Plpp1-/- CD8+ T cells. Mechanistically, programmed death-1 (PD-1) signaling in CD8+ T cells induced GATA1 binding to the promoter region Plpp1 and thereby suppressed Plpp1 expression. PD-1 blockade increased Plpp1 expression and restored CD8+ T cell antitumor function but did not rescue dysfunction of Plpp1-/- CD8+ T cells. Thus, PD-1 signaling regulates phospholipid metabolism in CD8+ T cells, with therapeutic implications for immunotherapy.

Keywords:  CD8(+) T cell; PD-1 signaling; PLPP1; anti-PD-1 therapy; antitumor immunity; ferroptosis; lipid peroxidation; phospholipid metabolism; tumor microenvironment; unsaturated fatty acid

DOI:  https://doi.org/10.1016/j.immuni.2024.08.003
Antioxid Redox Signal. 2024 Sep 03.

Succinate activates UCP2 to suppress neuroinflammation and confer protection following intracerebral hemorrhage.

Yecheng Wang, Caiyun Huang, Xiaoying Wang, Rong Cheng, Xue Li, Jiahao Wang, Lu Zhang, Fuhao Li, Hao Wang, Xinyu Li, Yi Li, Yiqing Xia, Jian Cheng, Xiaofan Pan, Jia Jia, Guo-Dong Xiao.

AIMS: Succinate, a metabolite in the tricarboxylic acid cycle, is increasingly recognized to play essential roles in inflammation by functioning either as an intracellular or extracellular signaling molecule. However, the role and mechanisms of succinate in inflammation remain elusive. Here, we investigated the mechanism underlying the effects of succinate on neuroinflammation in intracerebral hemorrhage (ICH) models.
RESULTS: We unexpectedly found that succinate robustly inhibited neuroinflammation and conferred protection following ICH. Mechanistically, oxidation of succinate by succinate dehydrogenase (SDH) drove reverse electron transport (RET) at mitochondrial complex I, leading to mitochondrial superoxide production in microglia. Complex I-derived superoxide, in turn, activated uncoupling protein 2 (UCP2). By using mice with specific deletion of UCP2 in microglia/macrophage, we showed that UCP2 was needed for succinate to inhibit neuroinflammation, confer protection, and activate downstream AMP-activated protein kinase (AMPK) following ICH. Moreover, knockdown of SDH, complex I or AMPK abolished the therapeutic effects of succinate following ICH.
INNOVATION AND CONCLUSION: We provide evidence that driving complex I RET to activate UCP2 is a novel mechanism of succinate intracellular signaling and a mechanism underlying the inhibition of neuroinflammation by succinate.
KEY WORDS: succinate; uncoupling protein 2; microglia; neuroinflammation; intracerebral hemorrhage.

DOI: https://doi.org/10.1089/ars.2024.0573
Cell Death Differ. 2024 Sep 05.

Foxk1 promotes bone formation through inducing aerobic glycolysis.

Chungeng Liu, Naibo Feng, Zhenmin Wang, Kangyan Zheng, Yongheng Xie, Hongyu Wang, Houqing Long, Songlin Peng.

Transcription factor Foxk1 can regulate cell proliferation, differentiation, metabolism, and promote skeletal muscle regeneration and cardiogenesis. However, the roles of Foxk1 in bone formation is unknown. Here, we found that Foxk1 expression decreased in the bone tissue of aged mice and osteoporosis patients. Knockdown of Foxk1 in primary murine calvarial osteoblasts suppressed osteoblast differentiation and proliferation. Conditional knockout of Foxk1 in preosteoblasts and mature osteoblasts in mice exhibited decreased bone mass and mechanical strength due to reduced bone formation. Mechanistically, we identified Foxk1 targeted the promoter region of many genes of glycolytic enzyme by CUT&Tag analysis. Lacking of Foxk1 in primary murine calvarial osteoblasts resulted in reducing aerobic glycolysis. Inhibition of glycolysis by 2DG hindered osteoblast differentiation and proliferation induced by Foxk1 overexpression. Finally, specific overexpression of Foxk1 in preosteoblasts, driven by a preosteoblast specific osterix promoter, increased bone mass and bone mechanical strength of aged mice, which could be suppressed by inhibiting glycolysis. In summary, these findings reveal that Foxk1 plays a vital role in the osteoblast metabolism regulation and bone formation stimulation, offering a promising approach for preventing age-related bone loss.

DOI: https://doi.org/10.1038/s41418-024-01371-w
J Clin Invest. 2024 Aug 29. pii: e180904. [Epub ahead of print]

Retinal perivascular macrophages regulate immune cell infiltration during neuroinflammation in mouse models of ocular disease.

Jacob K Sterling, Amrita Rajesh, Steven Droho, Joyce Gong, Andrew L Wang, Andrew P Voigt, C Elysse Brookins, Jeremy A Lavine.

  The blood-retina barrier (BRB), which is disrupted in diabetic retinopathy (DR) and uveitis, is an important anatomical characteristic of the retina, regulating nutrient, waste, water, protein, and immune cell flux. The BRB is composed of endothelial cell tight junctions, pericytes, astrocyte end feet, a collagen basement membrane, and perivascular macrophages. Despite the importance of the BRB, retinal perivascular macrophage function remains unknown. We found that retinal perivascular macrophages reside on post-capillary venules in the superficial vascular plexus and express MHCII. Using single-cell RNA-sequencing, we found that perivascular macrophages express a pro-chemotactic transcriptome and identified Pf4/CXCL4 as a perivascular macrophage marker. We used Pf4Cre mice to specifically deplete perivascular macrophages. To model retinal inflammation, we performed intraocular CCL2 injections. Ly6C+ monocytes crossed the BRB proximal to perivascular macrophages. Depletion of perivascular macrophages severely hampered Ly6C+ monocyte infiltration. These data suggest that retinal perivascular macrophages orchestrate immune cell migration across the BRB, with implications for inflammatory ocular diseases including DR and uveitis.

Keywords:  Macrophages; Monocytes; Ophthalmology; Retinopathy

DOI:  https://doi.org/10.1172/JCI180904
J Biol Chem. 2024 Aug 31. pii: S0021-9258(24)02241-5. [Epub ahead of print] 107740

Identification of SLC25A46 interaction interfaces with mitochondrial membrane fusogens Opa1 and Mfn2.

Sivakumar Boopathy, Bridget E Luce, Camila Makhlouta Lugo, Pusparanee Hakim, Julie McDonald, Ha Lin Kim, Jackeline Ponce, Beatrix M Ueberheide, Luke H Chao.

  Mitochondrial fusion requires the sequential merger of four bilayers to two. The outer-membrane solute carrier protein SLC25A46 interacts with both the outer and inner-membrane dynamin family GTPases Mfn1/2 and Opa1. While SLC25A46 levels are known to affect mitochondrial morphology, how SLC25A46 interacts with Mfn1/2 and Opa1 to regulate membrane fusion is not understood. In this study, we use crosslinking mass-spectrometry and AlphaFold 2 modeling to identify interfaces mediating a SLC25A46 interactions with Opa1 and Mfn2. We reveal that the bundle signaling element of Opa1 interacts with SLC25A46, and present evidence of a Mfn2 interaction involving the SLC25A46 cytosolic face. We validate these newly identified interaction interfaces and show that they play a role in mitochondrial network maintenance.

Keywords:  GTPase; Mass spectrometry; Membrane fusion; Mitochondria; Mitochondrial solute carrier; Protein cross-linking; Protein-protein interaction; Structural model

DOI:  https://doi.org/10.1016/j.jbc.2024.107740
Cell Host Microbe. 2024 Aug 21. pii: S1931-3128(24)00290-7. [Epub ahead of print]

Metabolic immaturity and breastmilk bile acid metabolites are central determinants of heightened newborn vulnerability to norovirus diarrhea.

Amy M Peiper, Joyce Morales Aparicio, Zhengzheng Hu, Lufuno Phophi, Emily W Helm, Rebecca J Rubinstein, Matthew Phillips, Caroline G Williams, Saravanan Subramanian, Michael Cross, Neha Iyer, Quyen Nguyen, Rachel Newsome, Christian Jobin, Stephanie N Langel, Filemon Bucardo, Sylvia Becker-Dreps, Xiao-Di Tan, Paul A Dawson, Stephanie M Karst.

  The pathogenic outcome of enteric virus infections is governed by a complex interplay between the virus, intestinal microbiota, and host immune factors, with metabolites serving as a key mediator. Noroviruses bind bile acid metabolites, which are produced by the host and then modified by commensal bacteria. Paradoxically, bile acids can have both proviral and antiviral roles during norovirus infections. Working in an infant mouse model of norovirus infection, we demonstrate that microbiota and their bile acid metabolites protect from norovirus diarrhea, whereas host bile acids promote disease. We also find that maternal bile acid metabolism determines the susceptibility of newborn mice to norovirus diarrhea during breastfeeding. Finally, targeting maternal and neonatal bile acid metabolism can protect newborn mice from norovirus disease. In summary, neonatal metabolic immaturity and breastmilk bile acids are central determinants of heightened newborn vulnerability to norovirus disease.

Keywords:  ASBT; bile acids; breastmilk metabolites; enteromammary; gut-mammary; microbial metabolites; microbiota; neonatal infections; newborn infections; norovirus

DOI:  https://doi.org/10.1016/j.chom.2024.08.003
JCI Insight. 2024 Sep 03. pii: e180016. [Epub ahead of print]

Lipidomics of infant mesenchymal stem cells associate with the maternal milieu and child adiposity.

Lauren E Gyllenhammer, Vincent Zaegel, Allison M Duensing, Manoel Lixandrao, Dana Dabelea, Bryan C Bergman, Kristen E Boyle.

  Our objective was to interrogate infant mesenchymal stem cell (MSC) lipid metabolism and gestational exposures that may contribute to child obesity risk. MSCs were cultured from term infants of mothers with obesity (n=16) or normal-weight (n=15). In MSCs undergoing myogenesis in vitro, we used lipidomics to distinguish phenotypes by unbiased cluster analysis and lipid challenge (24h excess fatty acid, 24hFA). We measured MSC AMP-activated protein kinase (AMPK) activity and fatty acid oxidation (FAO), and a composite index of maternal glucose, insulin, triglycerides, free fatty acids, tumor necrosis factor-α, high density lipoprotein- and total- cholesterol in fasting blood from mid- and late-gestation (~17, ~27wks). We measured child adiposity at birth (n=29), 4-6m (n=29), and 4-6y (n=13). Three MSC clusters were distinguished by triacylglycerol (TAG) stores, with greatest TAGs in Cluster-2. All Clusters increased acylcarnitines and TAGs with 24hFA, though Cluster-2 was more pronounced and corresponded to AMPK activation and FAO. Maternal metabolic markers predicted MSC Clusters and child adiposity at 4-6y (both highest in Cluster-3). Our data supports that MSC phenotypes are predicted by comprehensive maternal metabolic milieu exposures, independent of maternal BMI, and suggest utility as an at-birth predictor for child adiposity, though validation with larger longitudinal samples is warranted.

Keywords:  Development; Fatty acid oxidation; Human stem cells; Metabolism; Obesity

DOI:  https://doi.org/10.1172/jci.insight.180016
Cell Rep. 2024 Aug 31. pii: S2211-1247(24)01027-1. [Epub ahead of print]43(9): 114676

Aldehydes alter TGF-β signaling and induce obesity and cancer.

Xiaochun Yang, Krishanu Bhowmick, Shuyun Rao, Xiyan Xiang, Kazufumi Ohshiro, Richard L Amdur, Md Imtaiyaz Hassan, Taj Mohammad, Keith Crandall, Paolo Cifani, Kirti Shetty, Scott K Lyons, Joseph R Merrill, Anil K Vegesna, Sahara John, Patricia S Latham, James M Crawford, Bibhuti Mishra, Srinivasan Dasarathy, Xin Wei Wang, Herbert Yu, Zhanwei Wang, Hai Huang, Adrian R Krainer, Lopa Mishra.

  Obesity and fatty liver diseases-metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH)-affect over one-third of the global population and are exacerbated in individuals with reduced functional aldehyde dehydrogenase 2 (ALDH2), observed in approximately 560 million people. Current treatment to prevent disease progression to cancer remains inadequate, requiring innovative approaches. We observe that Aldh2-/- and Aldh2-/-Sptbn1+/- mice develop phenotypes of human metabolic syndrome (MetS) and MASH with accumulation of endogenous aldehydes such as 4-hydroxynonenal (4-HNE). Mechanistic studies demonstrate aberrant transforming growth factor β (TGF-β) signaling through 4-HNE modification of the SMAD3 adaptor SPTBN1 (β2-spectrin) to pro-fibrotic and pro-oncogenic phenotypes, which is restored to normal SMAD3 signaling by targeting SPTBN1 with small interfering RNA (siRNA). Significantly, therapeutic inhibition of SPTBN1 blocks MASH and fibrosis in a human model and, additionally, improves glucose handling in Aldh2-/- and Aldh2-/-Sptbn1+/- mice. This study identifies SPTBN1 as a critical regulator of the functional phenotype of toxic aldehyde-induced MASH and a potential therapeutic target.

Keywords:  ALDH2; CP: Cancer; CP: Metabolism; HCC; MASH; SMAD3; SPTBN1; TGF-β; cancer; liver disease; metabolic syndrome; reactive aldehydes

DOI:  https://doi.org/10.1016/j.celrep.2024.114676
Cell Rep Med. 2024 Aug 28. pii: S2666-3791(24)00427-0. [Epub ahead of print] 101706

Combinatorial targeting of glutamine metabolism and lysosomal-based lipid metabolism effectively suppresses glioblastoma.

Yaogang Zhong, Feng Geng, Logan Mazik, Xinmin Yin, Aline Paixao Becker, Shabber Mohammed, Huali Su, Enming Xing, Yongjun Kou, Cheng-Yao Chiang, Yunzhou Fan, Yongchen Guo, Qiang Wang, Pui-Kai Li, Xiaokui Mo, Etienne Lefai, Liqing He, Xiaolin Cheng, Xiang Zhang, Arnab Chakravarti, Deliang Guo.

  Antipsychotic drugs have been shown to have antitumor effects but have had limited potency in the clinic. Here, we unveil that pimozide inhibits lysosome hydrolytic function to suppress fatty acid and cholesterol release in glioblastoma (GBM), the most lethal brain tumor. Unexpectedly, GBM develops resistance to pimozide by boosting glutamine consumption and lipogenesis. These elevations are driven by SREBP-1, which we find upregulates the expression of ASCT2, a key glutamine transporter. Glutamine, in turn, intensifies SREBP-1 activation through the release of ammonia, creating a feedforward loop that amplifies both glutamine metabolism and lipid synthesis, leading to drug resistance. Disrupting this loop via pharmacological targeting of ASCT2 or glutaminase, in combination with pimozide, induces remarkable mitochondrial damage and oxidative stress, leading to GBM cell death in vitro and in vivo. Our findings underscore the promising therapeutic potential of effectively targeting GBM by combining glutamine metabolism inhibition with lysosome suppression.

Keywords:  ASCT2; GLS; SREBP-1; cholesterol; fatty acids; glioblastoma; glutamine; lipid droplets; lysosome; pimozide

DOI:  https://doi.org/10.1016/j.xcrm.2024.101706
Nature. 2024 Sep 04.

Alternating high-fat diet enhances atherosclerosis by neutrophil reprogramming.

Jean-Rémi Lavillegrand, Rida Al-Rifai, Sara Thietart, Théo Guyon, Marie Vandestienne, Raphael Cohen, Vincent Duval, Xiaodan Zhong, Daniel Yen, Mumin Ozturk, Yutaka Negishi, Joanne Konkel, Emmanuel Pinteaux, Olivia Lenoir, Jose Vilar, Ludivine Laurans, Bruno Esposito, Marius Bredon, Harry Sokol, Marc Diedisheim, Antoine-Emmanuel Saliba, Alma Zernecke, Clément Cochain, Jessica Haub, Alain Tedgui, Nancy A Speck, Soraya Taleb, Musa M Mhlanga, Andreas Schlitzer, Niels P Riksen, Hafid Ait-Oufella.

Systemic immune responses caused by chronic hypercholesterolaemia contribute to atherosclerosis initiation, progression and complications1. However, individuals often change their dietary habits over time2, and the effects of an alternating high-fat diet (HFD) on atherosclerosis remain unclear. Here, to address this relevant issue, we developed a protocol using atherosclerosis-prone mice to compare an alternating versus continuous HFD while maintaining similar overall exposure periods. We found that an alternating HFD accelerated atherosclerosis in Ldlr-/- and Apoe-/- mice compared with a continuous HFD. This pro-atherogenic effect of the alternating HFD was also observed in Apoe-/-Rag2-/- mice lacking T, B and natural killer T cells, ruling out the role of the adaptive immune system in the observed phenotype. Discontinuing the HFD in the alternating HFD group downregulated RUNX13, promoting inflammatory signalling in bone marrow myeloid progenitors. After re-exposure to an HFD, these cells produced IL-1β, leading to emergency myelopoiesis and increased neutrophil levels in blood. Neutrophils infiltrated plaques and released neutrophil extracellular traps, exacerbating atherosclerosis. Specific depletion of neutrophils or inhibition of IL-1β pathways abolished emergency myelopoiesis and reversed the pro-atherogenic effects of the alternating HFD. This study highlights the role of IL-1β-dependent neutrophil progenitor reprogramming in accelerated atherosclerosis induced by alternating HFD.

DOI: https://doi.org/10.1038/s41586-024-07693-6
Nature. 2024 Sep 04.

Early intermittent hyperlipidaemia alters tissue macrophages to fuel atherosclerosis.

Minoru Takaoka, Xiaohui Zhao, Hwee Ying Lim, Costan G Magnussen, Owen Ang, Nadine Suffee, Patricia R Schrank, Wei Siong Ong, Dimitrios Tsiantoulas, Felix Sommer, Sarajo K Mohanta, James Harrison, Yaxing Meng, Ludivine Laurans, Feitong Wu, Yuning Lu, Leanne Masters, Stephen A Newland, Laura Denti, Mingyang Hong, Mouna Chajadine, Markus Juonala, Juhani S Koskinen, Mika Kähönen, Katja Pahkala, Suvi P Rovio, Juha Mykkänen, Russell Thomson, Tsuneyasu Kaisho, Andreas J R Habenicht, Marc Clement, Alain Tedgui, Hafid Ait-Oufella, Tian X Zhao, Meritxell Nus, Christiana Ruhrberg, Soraya Taleb, Jesse W Williams, Olli T Raitakari, Véronique Angeli, Ziad Mallat.

Hyperlipidaemia is a major risk factor of atherosclerotic cardiovascular disease (ASCVD). Risk of cardiovascular events depends on cumulative lifetime exposure to low-density lipoprotein cholesterol (LDL-C) and, independently, on the time course of exposure to LDL-C, with early exposure being associated with a higher risk1. Furthermore, LDL-C fluctuations are associated with ASCVD outcomes2-4. However, the precise mechanisms behind this increased ASCVD risk are not understood. Here, we make the unexpected observation that early intermittent feeding of mice with a high-cholesterol Western-type diet (WD) accelerates atherosclerosis compared with late continuous exposure to WD, despite similar cumulative circulating LDL-C levels. We find that early intermittent hyperlipidaemia alters the number and homeostatic phenotype of resident-like arterial macrophages. Macrophage genes with altered expression are enriched for genes linked to human ASCVD in genome-wide association studies. We show that LYVE1+ resident macrophages are atheroprotective, and identify new biological pathways, related to actin filament organisation, whose alteration accelerates atherosclerosis. Using the Young Finns Study, we show that exposure to cholesterol early in life is significantly associated with the incidence and size of carotid atherosclerotic plaques in mid-adulthood. In summary, our results identify early intermittent exposure to cholesterol as a strong determinant of accelerated atherosclerosis, highlighting the importance of optimal control of hyperlipidaemia early in life, and providing insight into the underlying biological mechanisms. This knowledge will be essential to designing effective therapeutic strategies to combat atherosclerotic cardiovascular disease.

DOI: https://doi.org/10.1038/s41586-024-07993-x
Proc Natl Acad Sci U S A. 2024 Sep 10. 121(37): e2405821121

Biosynthesis of resolvin D1, resolvin D2, and RCTR1 from 7,8(S,S)-epoxytetraene in human neutrophils and macrophages.

Robert Nshimiyimana, Mélissa Simard, Tarvi Teder, Ana R Rodriguez, Bernd W Spur, Jesper Z Haeggström, Charles N Serhan.

  While the acute inflammatory response to harmful stimuli is protective, unrestrained neutrophil swarming drives collateral tissue damage and inflammation. Biosynthesized from omega-3 essential polyunsaturated fatty acids, resolvins are a family of signaling molecules produced by immune cells within the resolution phase to orchestrate return to homeostasis. Understanding the mechanisms that govern biosynthesis of these potent molecules gives insight into stimulating endogenous resolution and offers fresh opportunities for preventing and treating excessive inflammation. In this report, using materials prepared by total synthesis and liquid chromatography and tandem mass spectrometry-based matching studies, we established the role of 7,8(S,S)-epoxytetraene intermediate in the biosynthesis of resolvin D1, resolvin D2, and the resolvin conjugate in tissue regeneration (RCTR1) by human phagocytes. We demonstrated that this 7,8(S,S)-epoxy-containing intermediate is directly converted to resolvin D2 by human M2-like macrophages and to resolvin D1 and RCTR1 by human macrophages, neutrophils, and peripheral blood mononuclear cells. In addition, both human recombinant soluble epoxide hydrolase (sEH) and the glutathione S-transferase leukotriene C4 synthase (LTC4S) each catalyze conversion of this epoxide to resolvin D1 and RCTR1, respectively. MS3 ion-trap scans and isotope incorporation of 18O from H218O with sEH indicated that the oxygen atom at C-8 in resolvin D1 is derived from water. Results from molecular docking simulations with biosynthetic precursor 17S-hydroperoxy-4,7,10,13,19-cis-15-trans-docosahexaenoic acid and the epoxy intermediate were consistent with 5-lipoxygenase production of resolvin D1. Together, these results give direct evidence for the role of resolvin 7,8(S,S)-epoxytetraene intermediate in the endogenous formation of resolution-phase mediators resolvin D1, resolvin D2, and RCTR1 by human phagocytes.

Keywords:  inflammation resolution; innate immunity; lipid mediators; macrophages

DOI:  https://doi.org/10.1073/pnas.2405821121
Immunity. 2024 Aug 23. pii: S1074-7613(24)00407-2. [Epub ahead of print]

Inhibitory co-receptor Lag3 supports Foxp3+ regulatory T cell function by restraining Myc-dependent metabolic programming.

Dongkyun Kim, Giha Kim, Rongzhen Yu, Juyeun Lee, Sohee Kim, Mia R Gleason, Kevin Qiu, Elena Montauti, Li Lily Wang, Deyu Fang, Jaehyuk Choi, Navdeep S Chandel, Samuel Weinberg, Booki Min.

  Lymphocyte activation gene 3 (Lag3) is an inhibitory co-receptor expressed on activated T cells and has been proposed to regulate regulatory T (Treg) cell function. However, its precise modality and mechanisms remain elusive. We generated Treg cell-specific Lag3-mutant mouse models and found that Lag3 was essential for Treg cell control of autoimmunity. RNA sequencing analysis revealed that Lag3 mutation altered genes associated with metabolic processes, especially Myc target genes. Myc expression in Lag3-mutant Treg cells was increased to the level seen in conventional T helper (Th)1-type effector cells and directly correlated with their metabolic profiles and in vivo suppressive functions. The phosphatidylinositol 3-kinase (PI3K)-Akt-Rictor pathway was activated in Lag3-mutant Treg cells, and inhibiting PI3K, Rictor, or lactate dehydrogenase A (Ldha), a key Myc target enzyme converting pyruvate to lactate, was sufficient to restore normal metabolism and suppressive function in Lag3-mutant Treg cells. These findings indicate that Lag3 supports Treg cell suppression partly by tuning Myc-dependent metabolic programming.

Keywords:  Lag3; Myc; Treg cells; autoimmunity; metabolism

DOI:  https://doi.org/10.1016/j.immuni.2024.08.008
J Clin Invest. 2024 Sep 03. pii: e177606. [Epub ahead of print]134(17):

Pharmacologic LDH inhibition redirects intratumoral glucose uptake and improves antitumor immunity in solid tumor models.

Svena Verma, Sadna Budhu, Inna Serganova, Lauren Dong, Levi M Mangarin, Jonathan F Khan, Mamadou A Bah, Anais Assouvie, Yacine Marouf, Isabell Schulze, Roberta Zappasodi, Jedd D Wolchok, Taha Merghoub.

  Tumor reliance on glycolysis is a hallmark of cancer. Immunotherapy is more effective in controlling glycolysis-low tumors lacking lactate dehydrogenase (LDH) due to reduced tumor lactate efflux and enhanced glucose availability within the tumor microenvironment (TME). LDH inhibitors (LDHi) reduce glucose uptake and tumor growth in preclinical models, but their impact on tumor-infiltrating T cells is not fully elucidated. Tumor cells have higher basal LDH expression and glycolysis levels compared with infiltrating T cells, creating a therapeutic opportunity for tumor-specific targeting of glycolysis. We demonstrate that LDHi treatment (a) decreases tumor cell glucose uptake, expression of the glucose transporter GLUT1, and tumor cell proliferation while (b) increasing glucose uptake, GLUT1 expression, and proliferation of tumor-infiltrating T cells. Accordingly, increasing glucose availability in the microenvironment via LDH inhibition leads to improved tumor-killing T cell function and impaired Treg immunosuppressive activity in vitro. Moreover, combining LDH inhibition with immune checkpoint blockade therapy effectively controls murine melanoma and colon cancer progression by promoting effector T cell infiltration and activation while destabilizing Tregs. Our results establish LDH inhibition as an effective strategy for rebalancing glucose availability for T cells within the TME, which can enhance T cell function and antitumor immunity.

Keywords:  Cancer immunotherapy; Glucose metabolism; Immunology; Metabolism; Pharmacology

DOI:  https://doi.org/10.1172/JCI177606
Nat Cardiovasc Res. 2024 Sep 02.

α-Ketoglutarate promotes cardiomyocyte proliferation and heart regeneration after myocardial infarction.

Yu Shi, Miao Tian, Xiaofang Zhao, Luxun Tang, Feng Wang, Hao Wu, Qiao Liao, Hongmei Ren, Wenbin Fu, Shuo Zheng, Pedro A Jose, Liangpeng Li, Chunyu Zeng.

The neonatal mammalian heart can regenerate following injury through cardiomyocyte proliferation but loses this potential by postnatal day 7. Stimulating adult cardiomyocytes to reenter the cell cycle remains unclear. Here we show that cardiomyocyte proliferation depends on its metabolic state. Given the connection between the tricarboxylic acid cycle and cell proliferation, we analyzed these metabolites in mouse hearts from postnatal day 0.5 to day 7 and found that α-ketoglutarate ranked highest among the decreased metabolites. Injection of α-ketoglutarate extended the window of cardiomyocyte proliferation during heart development and promoted heart regeneration after myocardial infarction by inducing adult cardiomyocyte proliferation. This was confirmed in Ogdh-siRNA-treated mice with increased α-ketoglutarate levels. Mechanistically, α-ketoglutarate decreases H3K27me3 deposition at the promoters of cell cycle genes in cardiomyocytes. Thus, α-ketoglutarate promotes cardiomyocyte proliferation through JMJD3-dependent demethylation, offering a potential approach for treating myocardial infarction.

DOI: https://doi.org/10.1038/s44161-024-00531-y
J Lipid Res. 2024 Aug 30. pii: S0022-2275(24)00143-3. [Epub ahead of print] 100638

Modification in mitochondrial function is associated with the FADS1 variant and its interaction with alpha-linolenic acid-enriched diet - an exploratory study.

Maija Vaittinen, Mariana Ilha, Ratika Sehgal, Maria A Lankinen, Jyrki Ågren, Pirjo Käkelä, Kirsi A Virtanen, Markku Laakso, Ursula Schwab, Jussi Pihlajamäki.

  Fatty acid desaturase (FADS1) variant-rs174550 strongly regulates polyunsaturated fatty acid (PUFA) biosynthesis. Additionally, the FADS1 has been shown to be related to mitochondrial function. Thus, we investigated whether changes in mitochondrial function are associated with the genetic variation in FADS1 (rs174550) in human adipocytes isolated from individuals consuming diets enriched with either dietary alpha-linolenic (ALA) or linoleic acid (LA). Two cohorts of men homozygous for the genotype of FADS1 (rs174550) were studied: FADSDIET2 dietary intervention study with ALA- and LA-enriched diets and Kuopio Obesity Surgery study (KOBS), respectively. We could demonstrate that differentiated human adipose-derived stromal cells from subjects with the TT genotype had higher mitochondrial metabolism compared with subjects with the CC genotype of FADS1-rs174550 in the FADSDIET2. Responses to PUFA-enriched diets differed between the genotypes of FADS1-rs174550, showing that ALA, but not LA, -enriched diet stimulated mitochondrial metabolism more in subjects with the CC genotype when compared with subjects with the TT genotype. ALA, but not LA, proportion in plasma phospholipid fraction correlated positively with adipose tissue mitochondrial-DNA amount in subjects with the CC genotype of FADS1-rs174550 in the KOBS. These findings demonstrate that the FADS1-rs174550 is associated with modification in mitochondrial function in human adipocytes. Additionally, subjects with the CC genotype, when compared with the TT genotype, benefit more from the ALA-enriched diet, leading to enhanced energy metabolism in human adipocytes. Altogether, the FADS1-rs174550 could be a genetic marker to identify subjects who are most suitable to receive dietary PUFA supplementation, establishing also a personalized therapeutic strategy to improve mitochondrial function in metabolic diseases.

Keywords:  Adipocytes; Alpha-linolenic acid; Dietary fat; FADS1; Fatty acid oxidation; Human adipose-derived stromal cell; Lipids/oxidation; Mitochondria; Omega-3 fatty acids; Polyunsaturated fatty acid

DOI:  https://doi.org/10.1016/j.jlr.2024.100638
Nat Genet. 2024 Sep 03.

In vivo CRISPR screens identify a dual function of MEN1 in regulating tumor-microenvironment interactions.

Peiran Su, Yin Liu, Tianyi Chen, Yibo Xue, Yong Zeng, Guanghui Zhu, Sujun Chen, Mona Teng, Xinpei Ci, Mengdi Guo, Michael Y He, Jun Hao, Vivian Chu, Wenxi Xu, Shiyan Wang, Parinaz Mehdipour, Xin Xu, Sajid A Marhon, Fraser Soares, Nhu-An Pham, Bell Xi Wu, Peter Hyunwuk Her, Shengrui Feng, Najd Alshamlan, Maryam Khalil, Rehna Krishnan, Fangyou Yu, Chang Chen, Francis Burrows, Razqallah Hakem, Mathieu Lupien, Shane Harding, Benjamin H Lok, Catherine O'Brien, Alejandro Berlin, Daniel D De Carvalho, David G Brooks, Daniel Schramek, Ming-Sound Tsao, Housheng Hansen He.

Functional genomic screens in two-dimensional cell culture models are limited in identifying therapeutic targets that influence the tumor microenvironment. By comparing targeted CRISPR-Cas9 screens in a two-dimensional culture with xenografts derived from the same cell line, we identified MEN1 as the top hit that confers differential dropout effects in vitro and in vivo. MEN1 knockout in multiple solid cancer types does not impact cell proliferation in vitro but significantly promotes or inhibits tumor growth in immunodeficient or immunocompetent mice, respectively. Mechanistically, MEN1 knockout redistributes MLL1 chromatin occupancy, increasing H3K4me3 at repetitive genomic regions, activating double-stranded RNA expression and increasing neutrophil and CD8+ T cell infiltration in immunodeficient and immunocompetent mice, respectively. Pharmacological inhibition of the menin-MLL interaction reduces tumor growth in a CD8+ T cell-dependent manner. These findings reveal tumor microenvironment-dependent oncogenic and tumor-suppressive functions of MEN1 and provide a rationale for targeting MEN1 in solid cancers.

DOI: https://doi.org/10.1038/s41588-024-01874-9
Nat Commun. 2024 Aug 31. 15(1): 7575

Spatially structured exchange of metabolites enhances bacterial survival and resilience in biofilms.

Yuzhen Zhang, Yukmi Cai, Bing Zhang, Yi-Heng P Job Zhang.

Biofilm formation enhances bacterial survival and antibiotic tolerance, but the underlying mechanisms are incompletely understood. Here, we show that biofilm growth is accompanied by a reduction in bacterial energy metabolism and membrane potential, together with metabolic exchanges between the inner and outer regions in biofilms. More specifically, nutrient-starved cells in the interior supply amino acids to cells in the periphery, while peripheral cells experience a decrease in membrane potential and provide fatty acids to interior cells. Fatty acids facilitate the repair of starvation-induced membrane damage in inner cells and enhance their survival in the presence of antibiotics. Thus, metabolic exchanges between inner and outer cells contribute to survival of the nutrient-starved inner cells and contribute to antibiotic tolerance within the biofilm.

DOI: https://doi.org/10.1038/s41467-024-51940-3
Nat Commun. 2024 Aug 29. 15(1): 7483

Adipocyte deletion of the oxygen-sensor PHD2 sustains elevated energy expenditure at thermoneutrality.

Rongling Wang, Mario Gomez Salazar, Iris Pruñonosa Cervera, Amanda Coutts, Karen French, Marlene Magalhaes Pinto, Sabrina Gohlke, Ruben García-Martín, Matthias Blüher, Christopher J Schofield, Ioannis Kourtzelis, Roland H Stimson, Cécile Bénézech, Mark Christian, Tim J Schulz, Elias F Gudmundsson, Lori L Jennings, Vilmundur G Gudnason, Triantafyllos Chavakis, Nicholas M Morton, Valur Emilsson, Zoi Michailidou.

Enhancing thermogenic brown adipose tissue (BAT) function is a promising therapeutic strategy for metabolic disease. However, predominantly thermoneutral modern human living conditions deactivate BAT. We demonstrate that selective adipocyte deficiency of the oxygen-sensor HIF-prolyl hydroxylase (PHD2) gene overcomes BAT dormancy at thermoneutrality. Adipocyte-PHD2-deficient mice maintain higher energy expenditure having greater BAT thermogenic capacity. In human and murine adipocytes, a PHD inhibitor increases Ucp1 levels. In murine brown adipocytes, antagonising the major PHD2 target, hypoxia-inducible factor-(HIF)-2a abolishes Ucp1 that cannot be rescued by PHD inhibition. Mechanistically, PHD2 deficiency leads to HIF2 stabilisation and binding of HIF2 to the Ucp1 promoter, thus enhancing its expression in brown adipocytes. Serum proteomics analysis of 5457 participants in the deeply phenotyped Age, Gene and Environment Study reveal that serum PHD2 associates with increased risk of metabolic disease. Here we show that adipose-PHD2-inhibition is a therapeutic strategy for metabolic disease and identify serum PHD2 as a disease biomarker.

DOI: https://doi.org/10.1038/s41467-024-51718-7
Mol Cancer. 2024 Sep 04. 23(1): 185

The prognostic effect of infiltrating immune cells is shaped by proximal M2 macrophages in lung adenocarcinoma.

Jian-Rong Li, Vikram Shaw, Yupei Lin, Xiang Wang, Muhammad Aminu, Yong Li, Jia Wu, Jianjun Zhang, Christopher I Amos, Chao Cheng.

The spatial arrangement of immune cells within the tumor microenvironment (TME) and their interactions play critical roles in the initiation and development of cancer. Several advanced technologies such as imaging mass cytometry (IMC) providing the immunological landscape of the TME with single-cell resolution. In this study, we develop a new method to quantify the spatial proximity between different cell types based on single-cell spatial data. Using this method on IMC data from 416 lung adenocarcinoma patients, we show that the proximity between different cell types is more correlated with patient prognosis compared to the traditional features such immune cell density and fractions. Consistent with previous reports, our results validate that proximity of T helper (Th) and B cells to cancer cells is associated with survival benefits. More importantly, we discover that the proximity of M2 macrophages to multiple immune cells is associated with poor prognosis. When Th/B cells are stratified into M2-distal and M2-proximal, the abundance of the former but not the latter category of Th/B cells is correlated with enhanced patient survival. Additionally, the abundance of M2-distal and M2-proximal cytotoxic T cells (Tc) is respectively associated with good and poor prognosis. Our results indicate that the prognostic effect of Th, Tc, and B cells in the tumor microenvironment is modulated by the nearby M2 macrophages. The proposed new method proposed can be readily applied to all single-cell spatial data for revealing functional impact of immune cell interactions.

DOI: https://doi.org/10.1186/s12943-024-02080-1
Circ Res. 2024 Sep 05.

EPAS1 Attenuates Atherosclerosis Initiation at Disturbed Flow Sites Through Endothelial Fatty Acid Uptake.

Daniela Pirri, Siyu Tian, Blanca Tardajos-Ayllon, Sophie Irving, Francesco Donati, Scott P Allen, Tadanori Mammoto, Gemma Vilahur, Lida Kabir, Jane Bennett, Yasmin Rasool, Charis Pericleous, Guianfranco Mazzei, Liam McAllan, William R Scott, Thomas Koestler, Urs Zingg, Graeme Birdsey, Clint Miller, Torsten Schenkel, Emily V Chambers, Mark Dunning, Jovana Serbanovic-Canic, Francesco Botrè, Akiko Mammoto, Suowen Xu, Elena Osto, Weiping Han, Maria Fragiadaki, Paul C Evans.

   BACKGROUND: Atherosclerotic plaques form unevenly due to disturbed blood flow, causing localized endothelial cell (EC) dysfunction. Obesity exacerbates this process, but the underlying molecular mechanisms are unclear. The transcription factor EPAS1 (HIF2A) has regulatory roles in endothelium, but its involvement in atherosclerosis remains unexplored. This study investigates the potential interplay between EPAS1, obesity, and atherosclerosis.
METHODS: Responses to shear stress were analyzed using cultured porcine aortic EC exposed to flow in vitro coupled with metabolic and molecular analyses and by en face immunostaining of murine aortic EC exposed to disturbed flow in vivo. Obesity and dyslipidemia were induced in mice via exposure to a high-fat diet or through Leptin gene deletion. The role of Epas1 in atherosclerosis was evaluated by inducible endothelial Epas1 deletion, followed by hypercholesterolemia induction (adeno-associated virus-PCSK9 [proprotein convertase subtilisin/kexin type 9]; high-fat diet).
RESULTS: En face staining revealed EPAS1 enrichment at sites of disturbed blood flow that are prone to atherosclerosis initiation. Obese mice exhibited substantial reduction in endothelial EPAS1 expression. Sulforaphane, a compound with known atheroprotective effects, restored EPAS1 expression and concurrently reduced plasma triglyceride levels in obese mice. Consistently, triglyceride derivatives (free fatty acids) suppressed EPAS1 in cultured EC by upregulating the negative regulator PHD2. Clinical observations revealed that reduced serum EPAS1 correlated with increased endothelial PHD2 and PHD3 in obese individuals. Functionally, endothelial EPAS1 deletion increased lesion formation in hypercholesterolemic mice, indicating an atheroprotective function. Mechanistic insights revealed that EPAS1 protects arteries by maintaining endothelial proliferation by positively regulating the expression of the fatty acid-handling molecules CD36 and LIPG to increase fatty acid beta-oxidation.
CONCLUSIONS: Endothelial EPAS1 attenuates atherosclerosis at sites of disturbed flow by maintaining EC proliferation via fatty acid uptake and metabolism. This endothelial repair pathway is inhibited in obesity, suggesting a novel triglyceride-PHD2 modulation pathway suppressing EPAS1 expression. These findings have implications for therapeutic strategies addressing vascular dysfunction in obesity.

Keywords:  atherosclerosis; diet, high-fat; endothelial cells; obesity; plaque, atherosclerotic

DOI:  https://doi.org/10.1161/CIRCRESAHA.123.324054
J Nanobiotechnology. 2024 Aug 30. 22(1): 521

Hepatocyte-derived tissue extracellular vesicles safeguard liver regeneration and support regenerative therapy.

Si-Qi Ying, Yuan Cao, Ze-Kai Zhou, Xin-Yan Luo, Xiao-Hui Zhang, Ke Shi, Ji-Yu Qiu, Shu-Juan Xing, Yuan-Yuan Li, Kai Zhang, Fang Jin, Chen-Xi Zheng, Yan Jin, Bing-Dong Sui.

  Tissue-derived extracellular vesicles (EVs) are emerging as pivotal players to maintain organ homeostasis, which show promise as a next-generation candidate for medical use with extensive source. However, the detailed function and therapeutic potential of tissue EVs remain insufficiently studied. Here, through bulk and single-cell RNA sequencing analyses combined with ultrastructural tissue examinations, we first reveal that in situ liver tissue EVs (LT-EVs) contribute to the intricate liver regenerative process after partial hepatectomy (PHx), and that hepatocytes are the primary source of tissue EVs in the regenerating liver. Nanoscale and proteomic profiling further identify that the hepatocyte-specific tissue EVs (Hep-EVs) are strengthened to release with carrying proliferative messages after PHx. Moreover, targeted inhibition of Hep-EV release via AAV-shRab27a in vivo confirms that Hep-EVs are required to orchestrate liver regeneration. Mechanistically, Hep-EVs from the regenerating liver reciprocally stimulate hepatocyte proliferation by promoting cell cycle progression through Cyclin-dependent kinase 1 (Cdk1) activity. Notably, supplementing with Hep-EVs from the regenerating liver demonstrates translational potential and ameliorates insufficient liver regeneration. This study provides a functional and mechanistic framework showing that the release of regenerative Hep-EVs governs rapid liver regeneration, thereby enriching our understanding of physiological and endogenous tissue EVs in organ regeneration and therapy.

Keywords:  Cell cycle; Extracellular vesicles; Hepatocytes; Liver regeneration; Partial hepatectomy

DOI:  https://doi.org/10.1186/s12951-024-02790-0
Nat Commun. 2024 Aug 31. 15(1): 7566

Phospholipid scrambling induced by an ion channel/metabolite transporter complex.

Han Niu, Masahiro Maruoka, Yuki Noguchi, Hidetaka Kosako, Jun Suzuki.

Cells establish the asymmetrical distribution of phospholipids and alter their distribution by phospholipid scrambling (PLS) to adapt to environmental changes. Here, we demonstrate that a protein complex, consisting of the ion channel Tmem63b and the thiamine transporter Slc19a2, induces PLS upon calcium (Ca2+) stimulation. Through revival screening using a CRISPR sgRNA library on high PLS cells, we identify Tmem63b as a PLS-inducing factor. Ca2+ stimulation-mediated PLS is suppressed by deletion of Tmem63b, while human disease-related Tmem63b mutants induce constitutive PLS. To search for a molecular link between Ca2+ stimulation and PLS, we perform revival screening on Tmem63b-overexpressing cells, and identify Slc19a2 and the Ca2+-activated K+ channel Kcnn4 as PLS-regulating factors. Deletion of either of these genes decreases PLS activity. Biochemical screening indicates that Tmem63b and Slc19a2 form a heterodimer. These results demonstrate that a Tmem63b/Slc19a2 heterodimer induces PLS upon Ca2+ stimulation, along with Kcnn4 activation.

DOI: https://doi.org/10.1038/s41467-024-51939-w
Mitochondrion. 2024 Sep 03. pii: S1567-7249(24)00110-7. [Epub ahead of print]79 101952

SDHAF2 facilitates mitochondrial respiration through stabilizing succinate dehydrogenase and cytochrome c oxidase assemblies.

Chang-Lin Chen, Takaya Ishihara, Soumyadip Pal, Wei-Ling Huang, Emi Ogasawara, Chuang-Rung Chang, Naotada Ishihara.

  Succinate dehydrogenase (SDH) plays pivotal roles in maintaining cellular metabolism, modulating regulatory control over both the tricarboxylic acid cycle and oxidative phosphorylation to facilitate energy production within mitochondria. Given that SDH malfunction may serve as a hallmark triggering pseudo-hypoxia signaling and promoting tumorigenesis, elucidating the impact of SDH assembly defects on mitochondrial functions and cellular responses is of paramount importance. In this study, we aim to clarify the role of SDHAF2, one assembly factor of SDH, in mitochondrial respiratory activities. To achieve this, we utilize the CRISPR/Cas9 system to generate SDHAF2 knockout in HeLa cells and examine mitochondrial respiratory functions. Our findings demonstrate a substantial reduction in oxygen consumption rate in SDHAF2 knockout cells, akin to cells with inhibited SDH activity. In addition, in our in-gel activity assays reveal a significant decrease not only in SDH activity but also in cytochrome c oxidase (COX) activity in SDHAF2 knockout cells. The reduced COX activity is attributed to the assembly defect and remains independent of SDH inactivation or SDH complex disassembly. Together, our results indicate a critical role of SDHAF2 in regulating respiration by facilitating the assembly of COX.

Keywords:  Cytochrome c oxidase; Oxidative phosphorylation; Succinate dehydrogenase assembly factor 2 (SDHAF2)

DOI:  https://doi.org/10.1016/j.mito.2024.101952
Cancer Res Commun. 2024 Sep 06.

SREBP-dependent regulation of lipid homeostasis is required for progression and growth of pancreatic ductal adenocarcinoma.

Chiaki T Ishida, Stephanie L Myers, Casie S Kubota, Wei Shao, Meredith R McGuire, Chune Liu, Theodore E Ewachiw, Debaditya Mukhopadhyay, Suqi Ke, Hao Wang, Zeshaan A Rasheed, Robert A Anders, Peter J Espenshade.

Solid tumors undergo metabolic reprogramming when growth outstrips local nutrient supply. Lipids such as cholesterol and fatty acids are required for continued tumor cell proliferation, and oncogenic mutations stimulate de novo lipogenesis to support tumor growth. Sterol regulatory element-binding protein (SREBP) transcription factors control lipid homeostasis by activating genes required for lipid synthesis and uptake. SREBPs have been implicated in the progression of brain, breast, colon, liver, and prostate cancers. However, the role of the SREBP pathway and its central regulator SREBP cleavage activating protein (SCAP) in pancreatic ductal adenocarcinoma (PDAC) has not been studied in detail. Here, we demonstrated that pancreas-specific knockout of Scap has no effect on mouse pancreas development or function, allowing for examination of the role of Scap in the murine KPC model of PDAC. Notably, heterozygous loss of Scap prolonged survival in KPC mice, and homozygous loss of Scap impaired PDAC tumor progression. Using xenograft models, we showed that SCAP is required for human PDAC tumor growth. Mechanistically, chemical or genetic inhibition of the SREBP pathway prevented PDAC cell growth under low serum conditions due to a lack of lipid supply. Highlighting its clinical importance, the SREBP pathway is broadly required across cancer cell lines, target genes are upregulated in human PDAC tumors, and increased expression of SREBP targets is associated with poor survival in PDAC patients. Collectively, these results demonstrate that SCAP and SREBP pathway activity are required for PDAC cell and tumor growth, identifying SCAP as a potential therapeutic target for PDAC.

DOI: https://doi.org/10.1158/2767-9764.CRC-24-0120
Nat Genet. 2024 Sep 03.

Spatially resolved analysis of pancreatic cancer identifies therapy-associated remodeling of the tumor microenvironment.

Carina Shiau, Jingyi Cao, Dennis Gong, Mark T Gregory, Nicholas J Caldwell, Xunqin Yin, Jae-Won Cho, Peter L Wang, Jennifer Su, Steven Wang, Jason W Reeves, Tae Kyung Kim, Youngmi Kim, Jimmy A Guo, Nicole A Lester, Jung Woo Bae, Ryan Zhao, Nathan Schurman, Jamie L Barth, Maria L Ganci, Ralph Weissleder, Tyler Jacks, Motaz Qadan, Theodore S Hong, Jennifer Y Wo, Hannah Roberts, Joseph M Beechem, Carlos Fernandez-Del Castillo, Mari Mino-Kenudson, David T Ting, Martin Hemberg, William L Hwang.

In combination with cell-intrinsic properties, interactions in the tumor microenvironment modulate therapeutic response. We leveraged single-cell spatial transcriptomics to dissect the remodeling of multicellular neighborhoods and cell-cell interactions in human pancreatic cancer associated with neoadjuvant chemotherapy and radiotherapy. We developed spatially constrained optimal transport interaction analysis (SCOTIA), an optimal transport model with a cost function that includes both spatial distance and ligand-receptor gene expression. Our results uncovered a marked change in ligand-receptor interactions between cancer-associated fibroblasts and malignant cells in response to treatment, which was supported by orthogonal datasets, including an ex vivo tumoroid coculture system. We identified enrichment in interleukin-6 family signaling that functionally confers resistance to chemotherapy. Overall, this study demonstrates that characterization of the tumor microenvironment using single-cell spatial transcriptomics allows for the identification of molecular interactions that may play a role in the emergence of therapeutic resistance and offers a spatially based analysis framework that can be broadly applied to other contexts.

DOI: https://doi.org/10.1038/s41588-024-01890-9
Nat Struct Mol Biol. 2024 Sep 02.

Structural insight into synergistic activation of human 3-methylcrotonyl-CoA carboxylase.

Jiayue Su, Xuyang Tian, Hang Cheng, Desheng Liu, Ziyi Wang, Shan Sun, Hong-Wei Wang, Sen-Fang Sui.

The enzymes 3-methylcrotonyl-coenzyme A (CoA) carboxylase (MCC), pyruvate carboxylase and propionyl-CoA carboxylase belong to the biotin-dependent carboxylase family located in mitochondria. They participate in various metabolic pathways in human such as amino acid metabolism and tricarboxylic acid cycle. Many human diseases are caused by mutations in those enzymes but their structures have not been fully resolved so far. Here we report an optimized purification strategy to obtain high-resolution structures of intact human endogenous MCC, propionyl-CoA carboxylase and pyruvate carboxylase in different conformational states. We also determine the structures of MCC bound to different substrates. Analysis of MCC structures in different states reveals the mechanism of the substrate-induced, multi-element synergistic activation of MCC. These results provide important insights into the catalytic mechanism of the biotin-dependent carboxylase family and are of great value for the development of new drugs for the treatment of related diseases.

DOI: https://doi.org/10.1038/s41594-024-01379-3