bims-mepmim 2023-02-12 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2023–02–12
33 papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Allosteric regulation of CAD modulates de novo pyrimidine synthesis during the cell cycle.
Oxidative phosphorylation selectively orchestrates tissue macrophage homeostasis.
The helminth derived peptide FhHDM-1 redirects macrophage metabolism towards glutaminolysis to regulate the pro-inflammatory response.
13C-Metabolic flux analysis of 3T3-L1 adipocytes illuminates its core metabolism under hypoxia.
Glutamine synthetase expression rescues human dendritic cell survival in a glutamine-deprived environment.
Contribution of NRF2 to sulfur metabolism and mitochondrial activity.
L-arginine homeostasis governs adult neural stem cell activation by modulating energy metabolism in vivo.
Metabolic Hijacking of Hexose Metabolism to Ascorbate Synthesis Is the Unifying Biochemical Basis of Murine Liver Fibrosis.
Actin cytoskeleton vulnerability to disulfide stress mediates disulfidptosis.
Mitochondrial fusion is a therapeutic vulnerability of acute myeloid leukemia.
Splicing factor SRSF1 deficiency in the liver triggers NASH-like pathology and cell death.
Hippo pathway inhibition promotes metabolic adaptability and antioxidant response in myoblasts.
Retrograde regulation of mitochondrial fission and epithelial to mesenchymal transition in hepatocellular carcinoma by GCN5L1.
Mitochondrial fragmentation and donut formation enhance mitochondrial secretion to promote osteogenesis.
Metabolic individuality: Limitations, challenges, and potential for clinical utility.
Hepatocytes: A key role in liver inflammation.
The cell cycle loops UTP around CAD.
Nitric oxide suppression by secreted frizzled-related protein 2 drives retinoblastoma.
Selective and brain-penetrant lanosterol synthase inhibitors target glioma stem-like cells by inducing 24(S),25-epoxycholesterol production.
Circumvention of luteolysis reveals parturition pathways in mice dependent upon innate type 2 immunity.
Metabolic stress-induced human beta-cell death is mediated by increased intracellular levels of adenosine.
25-hydroxyvitamin D3 generates immunomodulatory plasticity in human periodontal ligament-derived mesenchymal stromal cells that is inflammatory context-dependent.
Dendritic cell phenotype and function in a 3D co-culture model of patient-derived metastatic colorectal cancer organoids.
Hypoxia induced lactate acidosis modulates tumor microenvironment and lipid reprogramming to sustain the cancer cell survival.
Adipose-targeted SWELL1 deletion exacerbates obesity and age-related non-alcoholic fatty liver disease.
Control of immune cell function by the unfolded protein response.
Metabolite asymmetric dimethylarginine (ADMA) functions as a destabilization enhancer of SOX9 mediated by DDAH1 in osteoarthritis.
LAT1 expression influences Paneth cell number and tumor development in ApcMin/+ mice.
GPX8 regulates clear cell renal cell carcinoma tumorigenesis through promoting lipogenesis by NNMT.
Programmed cell death and lipid metabolism of macrophages in NAFLD.
Notch-mediated hepatocyte MCP-1 secretion causes liver fibrosis.
CD206+ macrophages transventricularly infiltrate the early embryonic cerebral wall to differentiate into microglia.
Gut microbiome lipid metabolism and its impact on host physiology.

Nat Metab. 2023 Feb 06.

Allosteric regulation of CAD modulates de novo pyrimidine synthesis during the cell cycle.

Jong Shin, Hannan Mir, Maaz A Khurram, Kenji M Fujihara, Brian D Dynlacht, Timothy J Cardozo, Richard Possemato.

Metabolism is a fundamental cellular process that is coordinated with cell cycle progression. Despite this association, a mechanistic understanding of cell cycle phase-dependent metabolic pathway regulation remains elusive. Here we report the mechanism by which human de novo pyrimidine biosynthesis is allosterically regulated during the cell cycle. Combining traditional synchronization methods and metabolomics, we characterize metabolites by their accumulation pattern during cell cycle phases and identify cell cycle phase-dependent regulation of carbamoyl-phosphate synthetase 2, aspartate transcarbamylase and dihydroorotase (CAD), the first, rate-limiting enzyme in de novo pyrimidine biosynthesis. Through systematic mutational scanning and structural modelling, we find allostery as a major regulatory mechanism that controls the activity change of CAD during the cell cycle. Specifically, we report evidence of two Animalia-specific loops in the CAD allosteric domain that involve sensing and binding of uridine 5'-triphosphate, a CAD allosteric inhibitor. Based on homology with a mitochondrial carbamoyl-phosphate synthetase homologue, we identify a critical role for a signal transmission loop in regulating the formation of a substrate channel, thereby controlling CAD activity.

DOI: https://doi.org/10.1038/s42255-023-00735-9
Immunity. 2023 Jan 31. pii: S1074-7613(23)00021-3. [Epub ahead of print]

Oxidative phosphorylation selectively orchestrates tissue macrophage homeostasis.

Stefanie K Wculek, Ignacio Heras-Murillo, Annalaura Mastrangelo, Diego Mañanes, Miguel Galán, Verónica Miguel, Andrea Curtabbi, Coral Barbas, Navdeep S Chandel, José Antonio Enríquez, Santiago Lamas, David Sancho.

  In vitro studies have associated oxidative phosphorylation (OXPHOS) with anti-inflammatory macrophages, whereas pro-inflammatory macrophages rely on glycolysis. However, the metabolic needs of macrophages in tissues (TMFs) to fulfill their homeostatic activities are incompletely understood. Here, we identified OXPHOS as the highest discriminating process among TMFs from different organs in homeostasis by analysis of RNA-seq data in both humans and mice. Impairing OXPHOS in TMFs via Tfam deletion differentially affected TMF populations. Tfam deletion resulted in reduction of alveolar macrophages (AMs) due to impaired lipid-handling capacity, leading to increased cholesterol content and cellular stress, causing cell-cycle arrest in vivo. In obesity, Tfam depletion selectively ablated pro-inflammatory lipid-handling white adipose tissue macrophages (WAT-MFs), thus preventing insulin resistance and hepatosteatosis. Hence, OXPHOS, rather than glycolysis, distinguishes TMF populations and is critical for the maintenance of TMFs with a high lipid-handling activity, including pro-inflammatory WAT-MFs. This could provide a selective therapeutic targeting tool.

Keywords:  Tfam; cholesterol handling; immunometabolism; obesity; oxidative phosphorylation; pro-inflammatory macrophages; tissue macrophages

DOI:  https://doi.org/10.1016/j.immuni.2023.01.011
Front Immunol. 2023 ;14 1018076

The helminth derived peptide FhHDM-1 redirects macrophage metabolism towards glutaminolysis to regulate the pro-inflammatory response.

Susel Loli Quinteros, Eliana von Krusenstiern, Nathaniel W Snyder, Akane Tanaka, Bronwyn O'Brien, Sheila Donnelly.

  We have previously identified an immune modulating peptide, termed FhHDM-1, within the secretions of the liver fluke, Fasciola hepatica, which is sufficiently potent to prevent the progression of type 1 diabetes and multiple sclerosis in murine models of disease. Here, we have determined that the FhHDM-1 peptide regulates inflammation by reprogramming macrophage metabolism. Specifically, FhHDM-1 switched macrophage metabolism to a dependence on oxidative phosphorylation fuelled by fatty acids and supported by the induction of glutaminolysis. The catabolism of glutamine also resulted in an accumulation of alpha ketoglutarate (α-KG). These changes in metabolic activity were associated with a concomitant reduction in glycolytic flux, and the subsequent decrease in TNF and IL-6 production at the protein level. Interestingly, FhHDM-1 treated macrophages did not express the characteristic genes of an M2 phenotype, thereby indicating the specific regulation of inflammation, as opposed to the induction of an anti-inflammatory phenotype per se. Use of an inactive derivative of FhHDM-1, which did not modulate macrophage responses, revealed that the regulation of immune responses was dependent on the ability of FhHDM-1 to modulate lysosomal pH. These results identify a novel functional association between the lysosome and mitochondrial metabolism in macrophages, and further highlight the significant therapeutic potential of FhHDM-1 to prevent inflammation.

Keywords:  Fasciola hepatica; alpha-ketoglutarate (α-KG); fatty acid oxidation (FAO); glutaminolysis; helminth defence molecule; immune regulation; immunometabolism; macrophage

DOI:  https://doi.org/10.3389/fimmu.2023.1018076
Metab Eng. 2023 Feb 07. pii: S1096-7176(23)00022-8. [Epub ahead of print]

13C-Metabolic flux analysis of 3T3-L1 adipocytes illuminates its core metabolism under hypoxia.

Eleanor H Oates, Maciek R Antoniewicz.

  Hypoxia has been identified as a major factor in the pathogenesis of adipose tissue inflammation, which is a hallmark of obesity and obesity-linked type 2 diabetes mellitus. In this study, we have investigated the impact of hypoxia (1% oxygen) on the physiology and metabolism of 3T3-L1 adipocytes, a widely used cell culture model of adipose. Specifically, we applied parallel labeling experiments, isotopomer spectral analysis, and 13C-metabolic flux analysis to quantify the impact of hypoxia on adipogenesis, de novo lipogenesis and metabolic flux reprogramming in adipocytes. We found that 3T3-L1 cells can successfully differentiate into lipid-accumulating adipocytes under hypoxia, although the production of lipids was reduced by about 40%. Quantitative flux analysis demonstrated that short-term (1 day) and long-term (7 days) exposure to hypoxia resulted in similar reprogramming of cellular metabolism. Overall, we found that hypoxia: 1) reduced redox and energy generation by more than 2-fold and altered the patterns of metabolic pathway contributions to production and consumption of energy and redox cofactors; 2) redirected glucose metabolism from pentose phosphate pathway and citric acid cycle to lactate production; 3) rewired glutamine metabolism, from net glutamine production to net glutamine catabolism; 4) suppressed branched chain amino acid consumption; and 5) reduced biosynthesis of odd-chain fatty acids and mono-unsaturated fatty acids, while synthesis of saturated even-chain fatty acids was not affected. Together, these results highlight the profound impact of extracellular microenvironment on adipocyte metabolic activity and function.

Keywords:  3T3-L1 cells; Adipocytes; Differentiation; Hypoxia; Metabolism; de novo lipogenesis

DOI:  https://doi.org/10.1016/j.ymben.2023.02.002
Front Oncol. 2023 ;13 1120194

Glutamine synthetase expression rescues human dendritic cell survival in a glutamine-deprived environment.

Robert Schoeppe, Nathalie Babl, Sonja-Maria Decking, Gabriele Schönhammer, Andreas Siegmund, Christina Bruss, Katja Dettmer, Peter J Oefner, Linus Frick, Anna Weigert, Jonathan Jantsch, Wolfgang Herr, Michael Rehli, Kathrin Renner, Marina Kreutz.

   Introduction: Glutamine deficiency is a well-known feature of the tumor environment. Here we analyzed the impact of glutamine deprivation on human myeloid cell survival and function.
Methods: Different types of myeloid cells were cultured in the absence or presence of glutamine and/or with L-methionine-S-sulfoximine (MSO), an irreversible glutamine synthetase (GS) inhibitor. GS expression was analyzed on mRNA and protein level. GS activity and the conversion of glutamate to glutamine by myeloid cells was followed by 13C tracing analyses.
Results: The absence of extracellular glutamine only slightly affected postmitotic human monocyte to dendritic cell (DC) differentiation, function and survival. Similar results were obtained for monocyte-derived macrophages. In contrast, proliferation of the monocytic leukemia cell line THP-1 was significantly suppressed. While macrophages exhibited high constitutive GS expression, glutamine deprivation induced GS in DC and THP-1. Accordingly, proliferation of THP-1 was rescued by addition of the GS substrate glutamate and 13C tracing analyses revealed conversion of glutamate to glutamine. Supplementation with the GS inhibitor MSO reduced the survival of DC and macrophages and counteracted the proliferation rescue of THP-1 by glutamate.
Discussion: Our results show that GS supports myeloid cell survival in a glutamine poor environment. Notably, in addition to suppressing proliferation and survival of tumor cells, the blockade of GS also targets immune cells such as DCs and macrophages.

Keywords:  dendritic cells; glutamate; glutamine; glutamine synthetase; macrophages

DOI:  https://doi.org/10.3389/fonc.2023.1120194
Redox Biol. 2023 Feb 02. pii: S2213-2317(23)00025-3. [Epub ahead of print]60 102624

Contribution of NRF2 to sulfur metabolism and mitochondrial activity.

Md Morshedul Alam, Akihiro Kishino, Eunkyu Sung, Hiroki Sekine, Takaaki Abe, Shohei Murakami, Takaaki Akaike, Hozumi Motohashi.

  NF-E2-related factor 2 (NRF2) plays a crucial role in the maintenance of cellular homeostasis by regulating various enzymes and proteins that are involved in the redox reactions utilizing sulfur. While substantial impacts of NRF2 on mitochondrial activity have been described, the precise mechanism by which NRF2 regulates mitochondrial function is still not fully understood. Here, we demonstrated that NRF2 increased intracellular persulfides by upregulating the cystine transporter xCT encoded by Slc7a11, a well-known NRF2 target gene. Persulfides have been shown to play an important role in mitochondrial function. Supplementation with glutathione trisulfide (GSSSG), which is a form of persulfide, elevated the mitochondrial membrane potential (MMP), increased the oxygen consumption rate (OCR) and promoted ATP production. Persulfide-mediated mitochondrial activation was shown to require the mitochondrial sulfur oxidation pathway, especially sulfide quinone oxidoreductase (SQOR). Consistently, NRF2-mediated mitochondrial activation was also dependent on SQOR activity. This study clarified that the facilitation of persulfide production and sulfur metabolism in mitochondria by increasing cysteine availability is one of the mechanisms for NRF2-dependent mitochondrial activation.

Keywords:  Cysteine; Cystine; Mitochondria; Mitochondrial membrane potential; Persulfide; xCT

DOI:  https://doi.org/10.1016/j.redox.2023.102624
EMBO J. 2023 Feb 06. e112647

L-arginine homeostasis governs adult neural stem cell activation by modulating energy metabolism in vivo.

Mingyue Xu, Ye Guo, Min Wang, Xing Luo, Xuning Shen, Zhimin Li, Lei Wang, Weixiang Guo.

  Neurogenesis in the developing and adult brain is intimately linked to remodeling of cellular metabolism. However, it is still unclear how distinct metabolic programs and energy sources govern neural stem cell (NSC) behavior and subsequent neuronal differentiation. Here, we found that adult mice lacking the mitochondrial urea metabolism enzyme, Arginase-II (Arg-II), exhibited NSC overactivation, thereby leading to accelerated NSC pool depletion and decreased hippocampal neurogenesis over time. Mechanistically, Arg-II deficiency resulted in elevated L-arginine levels and induction of a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) caused by impaired attachment of hexokinase-I to mitochondria. Notably, selective inhibition of OXPHOS ameliorated NSC overactivation and restored abnormal neurogenesis in Arg-II deficient mice. Therefore, Arg-II-mediated intracellular L-arginine homeostasis directly influences the metabolic fitness of neural stem cells that is essential to maintain neurogenesis with age.

Keywords:  Adult neurogenesis; Arginase-II; Hexokinase; L-arginine; NSC pool

DOI:  https://doi.org/10.15252/embj.2022112647
Cells. 2023 Feb 02. pii: 485. [Epub ahead of print]12(3):

Metabolic Hijacking of Hexose Metabolism to Ascorbate Synthesis Is the Unifying Biochemical Basis of Murine Liver Fibrosis.

Diren Beyoğlu, Pinzhu Huang, Disha Skelton-Badlani, Christine Zong, Yury V Popov, Jeffrey R Idle.

  We wished to understand the metabolic reprogramming underlying liver fibrosis progression in mice. Administration to male C57BL/6J mice of the hepatotoxins carbon tetrachloride (CCl4), thioacetamide (TAA), or a 60% high-fat diet, choline-deficient, amino-acid-defined diet (HF-CDAA) was conducted using standard protocols. Livers collected at different times were analyzed by gas chromatography-mass spectrometry-based metabolomics. RNA was extracted from liver and assayed by qRT-PCR for mRNA expression of 11 genes potentially involved in the synthesis of ascorbic acid from hexoses, Gck, Adpgk, Hk1, Hk2, Ugp2, Ugdh, Ugt1a1, Akr1a4, Akr1b3, Rgn and Gulo. All hepatotoxins resulted in similar metabolic changes during active fibrogenesis, despite different etiology and resultant scarring pattern. Diminished hepatic glucose, galactose, fructose, pentose phosphate pathway intermediates, glucuronic acid and long-chain fatty acids were compensated by elevated ascorbate and the product of collagen prolyl 4-hydroxylase, succinate and its downstream metabolites fumarate and malate. Recovery from the HF-CDAA diet challenge (F2 stage fibrosis) after switching to normal chow was accompanied by increased glucose, galactose, fructose, ribulose 5-phosphate, glucuronic acid, the ascorbate metabolite threonate and diminished ascorbate. During the administration of CCl4, TAA and HF-CDAA, aldose reductase Akr1b3 transcription was induced six- to eightfold, indicating increased conversion of glucuronic acid to gulonic acid, a precursor of ascorbate synthesis. Triggering hepatic fibrosis by three independent mechanisms led to the hijacking of glucose and galactose metabolism towards ascorbate synthesis, to satisfy the increased demand for ascorbate as a cofactor for prolyl 4-hydroxylase for mature collagen production. This metabolic reprogramming and causal gene expression changes were reversible. The increased flux in this pathway was mediated predominantly by increased transcription of aldose reductase Akr1b3.

Keywords:  aldose reductase; ascorbate; collagen; fibrosis; galactose; glucose; liver; metabolic reprogramming; metabolomics; mouse model

DOI:  https://doi.org/10.3390/cells12030485
Nat Cell Biol. 2023 Feb 06.

Actin cytoskeleton vulnerability to disulfide stress mediates disulfidptosis.

Xiaoguang Liu, Litong Nie, Yilei Zhang, Yuelong Yan, Chao Wang, Medina Colic, Kellen Olszewski, Amber Horbath, Xiong Chen, Guang Lei, Chao Mao, Shiqi Wu, Li Zhuang, Masha V Poyurovsky, M James You, Traver Hart, Daniel D Billadeau, Junjie Chen, Boyi Gan.

SLC7A11-mediated cystine uptake suppresses ferroptosis yet promotes cell death under glucose starvation; the nature of the latter cell death remains unknown. Here we show that aberrant accumulation of intracellular disulfides in SLC7A11high cells under glucose starvation induces a previously uncharacterized form of cell death distinct from apoptosis and ferroptosis. We term this cell death disulfidptosis. Chemical proteomics and cell biological analyses showed that glucose starvation in SLC7A11high cells induces aberrant disulfide bonds in actin cytoskeleton proteins and F-actin collapse in a SLC7A11-dependent manner. CRISPR screens and functional studies revealed that inactivation of the WAVE regulatory complex (which promotes actin polymerization and lamellipodia formation) suppresses disulfidptosis, whereas constitutive activation of Rac promotes disulfidptosis. We further show that glucose transporter inhibitors induce disulfidptosis in SLC7A11high cancer cells and suppress SLC7A11high tumour growth. Our results reveal that the susceptibility of the actin cytoskeleton to disulfide stress mediates disulfidptosis and suggest a therapeutic strategy to target disulfidptosis in cancer treatment.

DOI: https://doi.org/10.1038/s41556-023-01091-2
Leukemia. 2023 Feb 04.

Mitochondrial fusion is a therapeutic vulnerability of acute myeloid leukemia.

Clement Larrue, Sarah Mouche, Shan Lin, Federico Simonetta, Nastassja K Scheidegger, Laury Poulain, Rudy Birsen, Jean-Emmanuel Sarry, Kimberly Stegmaier, Jerome Tamburini.

Mitochondrial metabolism recently emerged as a critical dependency in acute myeloid leukemia (AML). The shape of mitochondria is tightly regulated by dynamin GTPase proteins, which drive opposing fusion and fission forces to consistently adapt bioenergetics to the cellular context. Here, we showed that targeting mitochondrial fusion was a new vulnerability of AML cells, when assayed in patient-derived xenograft (PDX) models. Genetic depletion of mitofusin 2 (MFN2) or optic atrophy 1 (OPA1) or pharmacological inhibition of OPA1 (MYLS22) blocked mitochondrial fusion and had significant anti-leukemic activity, while having limited impact on normal hematopoietic cells ex vivo and in vivo. Mechanistically, inhibition of mitochondrial fusion disrupted mitochondrial respiration and reactive oxygen species production, leading to cell cycle arrest at the G0/G1 transition. These results nominate the inhibition of mitochondrial fusion as a promising therapeutic approach for AML.

DOI: https://doi.org/10.1038/s41375-023-01835-x
Nat Commun. 2023 Feb 09. 14(1): 551

Splicing factor SRSF1 deficiency in the liver triggers NASH-like pathology and cell death.

Waqar Arif, Bhoomika Mathur, Michael F Saikali, Ullas V Chembazhi, Katelyn Toohill, You Jin Song, Qinyu Hao, Saman Karimi, Steven M Blue, Brian A Yee, Eric L Van Nostrand, Sushant Bangru, Grace Guzman, Gene W Yeo, Kannanganattu V Prasanth, Sayeepriyadarshini Anakk, Carolyn L Cummins, Auinash Kalsotra.

Regulation of RNA processing contributes profoundly to tissue development and physiology. Here, we report that serine-arginine-rich splicing factor 1 (SRSF1) is essential for hepatocyte function and survival. Although SRSF1 is mainly known for its many roles in mRNA metabolism, it is also crucial for maintaining genome stability. We show that acute liver damage in the setting of targeted SRSF1 deletion in mice is associated with the excessive formation of deleterious RNA-DNA hybrids (R-loops), which induce DNA damage. Combining hepatocyte-specific transcriptome, proteome, and RNA binding analyses, we demonstrate that widespread genotoxic stress following SRSF1 depletion results in global inhibition of mRNA transcription and protein synthesis, leading to impaired metabolism and trafficking of lipids. Lipid accumulation in SRSF1-deficient hepatocytes is followed by necroptotic cell death, inflammation, and fibrosis, resulting in NASH-like liver pathology. Importantly, SRSF1-depleted human liver cancer cells recapitulate this pathogenesis, illustrating a conserved and fundamental role for SRSF1 in preserving genome integrity and tissue homeostasis. Thus, our study uncovers how the accumulation of detrimental R-loops impedes hepatocellular gene expression, triggering metabolic derangements and liver damage.

DOI: https://doi.org/10.1038/s41467-023-35932-3
Sci Rep. 2023 Feb 08. 13(1): 2232

Hippo pathway inhibition promotes metabolic adaptability and antioxidant response in myoblasts.

Qi Liu, Su Pan, Pengyang Li, Richard A F Dixon.

Metabolic plasticity in a hostile environment ensures cell survival. We investigated whether Hippo pathway inhibition contributed to cell adaptations under challenging conditions. We examined metabolic profiles and fuel substrate choices and preferences in C2C12 myoblasts after Hippo pathway inhibition via Salvador knockdown (SAV1 KD). SAV1 KD induced higher ATP production and a more energetic phenotype. Bioenergetic profiling showed enhanced key mitochondrial parameters including spare respiratory capacity. SAV1 KD cells showed markedly elevated glycolysis and glycolytic reserves; blocking other fuel-oxidation pathways enhanced mitochondrial flexibility of glucose oxidation. Under limited glucose, endogenous fatty acid oxidation increased to cope with bioenergetic stress. Gene expression patterns after SAV1 KD suggested transcriptional upregulation of key metabolic network regulators to promote energy production and free radical scavenging that may prevent impaired lipid and glucose metabolism. In SAV1 KD cells, sirtuin signaling was the top enriched canonical pathway linked with enhanced mitochondrial ATP production. Collectively, we demonstrated that Hippo pathway inhibition in SAV1 KD cells induces multiple metabolic properties, including enhancing mitochondrial spare respiratory capacity or glycolytic reserve to cope with stress and upregulating metabolic pathways supporting elevated ATP demand, bioenergetics, and glycolysis and counteracting oxidative stress. In response to metabolic challenges, SAV1 KD cells can increase fatty acid oxidation or glucose-coupled oxidative phosphorylation capacity to compensate for substrate limitations or alternative fuel oxidation pathway inhibition.

DOI: https://doi.org/10.1038/s41598-023-29372-8
Oncogene. 2023 Feb 09.

Retrograde regulation of mitochondrial fission and epithelial to mesenchymal transition in hepatocellular carcinoma by GCN5L1.

Linmeng Han, Chunyu Zhang, Danni Wang, Jiaqi Zhang, Qiqi Tang, Mulin Jun Li, Michael N Sack, Lingdi Wang, Lu Zhu.

Metabolic reprogram is crucial to support cancer cell growth and movement as well as determine cell fate. Mitochondrial protein acetylation regulates mitochondrial metabolism, which is relevant to cancer cell migration and invasion. The functional role of mitochondrial protein acetylation on cancer cell migration remains unclear. General control of amino acid synthesis 5 like-1(GCN5L1), as the regulator of mitochondrial protein acetylation, functions on metabolic reprogramming in mouse livers. In this study, we find that GCN5L1 expression is significantly decreased in metastatic HCC tissues. Loss of GCN5L1 promotes reactive oxygen species (ROS) generation through enhanced fatty acid oxidation (FAO), followed by activation of cellular ERK and DRP1 to promote mitochondrial fission and epithelia to mesenchymal transition (EMT) to boost cell migration. Moreover, palmitate and carnitine-stimulated FAO promotes mitochondrial fission and EMT gene expression to activate HCC cell migration. On the other hand, increased cellular acetyl-CoA level, the product of FAO, enhances HCC cell migration. Taken together, our finding uncovers the metastasis suppressor role as well as the underlying mechanism of GCN5L1 in HCC and also provides evidence of FAO retrograde control of HCC metastasis.

DOI: https://doi.org/10.1038/s41388-023-02621-w
Cell Metab. 2023 Feb 07. pii: S1550-4131(23)00003-7. [Epub ahead of print]35(2): 345-360.e7

Mitochondrial fragmentation and donut formation enhance mitochondrial secretion to promote osteogenesis.

Joonho Suh, Na-Kyung Kim, Wonn Shim, Seung-Hoon Lee, Hyo-Jeong Kim, Eunyoung Moon, Hiromi Sesaki, Jae Hyuck Jang, Jung-Eun Kim, Yun-Sil Lee.

  Mitochondrial components have been abundantly detected in bone matrix, implying that they are somehow transported extracellularly to regulate osteogenesis. Here, we demonstrate that mitochondria and mitochondrial-derived vesicles (MDVs) are secreted from mature osteoblasts to promote differentiation of osteoprogenitors. We show that osteogenic induction stimulates mitochondrial fragmentation, donut formation, and secretion of mitochondria through CD38/cADPR signaling. Enhancing mitochondrial fission and donut formation through Opa1 knockdown or Fis1 overexpression increases mitochondrial secretion and accelerates osteogenesis. We also show that mitochondrial fusion promoter M1, which induces Opa1 expression, impedes osteogenesis, whereas osteoblast-specific Opa1 deletion increases bone mass. We further demonstrate that secreted mitochondria and MDVs enhance bone regeneration in vivo. Our findings suggest that mitochondrial morphology in mature osteoblasts is adapted for extracellular secretion, and secreted mitochondria and MDVs are critical promoters of osteogenesis.

Keywords:  FIS1; M1; OPA1; donut mitochondria; mitochondria; mitochondrial secretion; mitochondrial transplantation; mitochondrial-derived vesicles; osteoblasts; osteogenesis

DOI:  https://doi.org/10.1016/j.cmet.2023.01.003
Cell Metab. 2023 Feb 07. pii: S1550-4131(23)00007-4. [Epub ahead of print]35(2): 233-235

Metabolic individuality: Limitations, challenges, and potential for clinical utility.

Sarah H Elsea, Jennifer E Posey.

In Nature Medicine, Surendran and colleagues recently reported the analysis of human plasma metabolomic data for 913 metabolites in ∼20,000 individuals, identifying 2,599 metabolite-genetic variant associations and >400 metabolite signatures comprised of jointly regulated metabolites. This extensive atlas of variant-metabolite relationships reveals novel genomic mechanisms driving metabolic phenotypes.

DOI: https://doi.org/10.1016/j.cmet.2023.01.007
Front Immunol. 2022 ;13 1083780

Hepatocytes: A key role in liver inflammation.

Jin Gong, Wei Tu, Jingmei Liu, Dean Tian.

  Hepatocytes, the major parenchymal cells in the liver, are responsible for a variety of cellular functions including carbohydrate, lipid and protein metabolism, detoxification and immune cell activation to maintain liver homeotasis. Recent studies show hepatocytes play a pivotal role in liver inflammation. After receiving liver insults and inflammatory signals, hepatocytes may undergo organelle damage, and further respond by releasing mediators and expressing molecules that can act in the microenvironment as well as initiate a robust inflammatory response. In this review, we summarize how the hepatic organelle damage link to liver inflammation and introduce numerous hepatocyte-derived pro-inflammatory factors in response to chronic liver injury.

Keywords:  cytokines; extracellular vesicles; hepatic inflammation; hepatocyte; organelle damage

DOI:  https://doi.org/10.3389/fimmu.2022.1083780
Nat Metab. 2023 Feb 06.

The cell cycle loops UTP around CAD.

Umakant Sahu, Issam Ben-Sahra.

DOI: https://doi.org/10.1038/s42255-023-00737-7
Cell Rep. 2023 Feb 10. pii: S2211-1247(23)00114-6. [Epub ahead of print]42(2): 112103

Nitric oxide suppression by secreted frizzled-related protein 2 drives retinoblastoma.

Panneerselvam Jayabal, Fuchun Zhou, Xiuye Ma, Kathryn M Bondra, Barron Blackman, Susan T Weintraub, Yidong Chen, Patricia Chévez-Barrios, Peter J Houghton, Brenda Gallie, Yuzuru Shiio.

  Retinoblastoma is a cancer of the infant retina primarily driven by loss of the Rb tumor suppressor gene, which is undruggable. Here, we report an autocrine signaling, mediated by secreted frizzled-related protein 2 (SFRP2), which suppresses nitric oxide and enables retinoblastoma growth. We show that coxsackievirus and adenovirus receptor (CXADR) is the cell-surface receptor for SFRP2 in retinoblastoma cells; that CXADR functions as a "dependence receptor," transmitting a growth-inhibitory signal in the absence of SFRP2; and that the balance between SFRP2 and CXADR determines nitric oxide production. Accordingly, high SFRP2 RNA expression correlates with high-risk histopathologic features in retinoblastoma. Targeting SFRP2 signaling by SFRP2-binding peptides or by a pharmacological inhibitor rapidly induces nitric oxide and profoundly inhibits retinoblastoma growth in orthotopic xenograft models. These results reveal a cytokine signaling pathway that regulates nitric oxide production and retinoblastoma cell proliferation and is amenable to therapeutic intervention.

Keywords:  CP: Cancer; CXADR; SFRP2; cell-surface proteome; nitric oxide; proteomics; retinoblastoma; secretome; signaling

DOI:  https://doi.org/10.1016/j.celrep.2023.112103
Cell Chem Biol. 2023 Feb 07. pii: S2451-9456(23)00028-4. [Epub ahead of print]

Selective and brain-penetrant lanosterol synthase inhibitors target glioma stem-like cells by inducing 24(S),25-epoxycholesterol production.

Thu P Nguyen, Wentian Wang, Alex C Sternisha, Chase D Corley, Hua-Yu Leo Wang, Xiaoyu Wang, Francisco Ortiz, Sang-Kyun Lim, Kalil G Abdullah, Luis F Parada, Noelle S Williams, Samuel K McBrayer, Jeffrey G McDonald, Jef K De Brabander, Deepak Nijhawan.

  Glioblastoma (GBM) is an aggressive adult brain cancer with few treatment options due in part to the challenges of identifying brain-penetrant drugs. Here, we investigated the mechanism of MM0299, a tetracyclic dicarboximide with anti-glioblastoma activity. MM0299 inhibits lanosterol synthase (LSS) and diverts sterol flux away from cholesterol into a "shunt" pathway that culminates in 24(S),25-epoxycholesterol (EPC). EPC synthesis following MM0299 treatment is both necessary and sufficient to block the growth of mouse and human glioma stem-like cells by depleting cellular cholesterol. MM0299 exhibits superior selectivity for LSS over other sterol biosynthetic enzymes. Critical for its application in the brain, we report an MM0299 derivative that is orally bioavailable, brain-penetrant, and induces the production of EPC in orthotopic GBM tumors but not normal mouse brain. These studies have implications for the development of an LSS inhibitor to treat GBM or other neurologic indications.

Keywords:  LSS; epoxycholesterol; glioblastoma; lanosterol synthase inhibitors; shunt pathway

DOI:  https://doi.org/10.1016/j.chembiol.2023.01.005
Immunity. 2023 Jan 24. pii: S1074-7613(23)00015-8. [Epub ahead of print]

Circumvention of luteolysis reveals parturition pathways in mice dependent upon innate type 2 immunity.

Johan Siewiera, Tara I McIntyre, Kelly M Cautivo, Karim Mahiddine, Damon Rideaux, Ari B Molofsky, Adrian Erlebacher.

  Although mice normally enter labor when their ovaries stop producing progesterone (luteolysis), parturition can also be triggered in this species through uterus-intrinsic pathways potentially analogous to the ones that trigger parturition in humans. Such pathways, however, remain largely undefined in both species. Here, we report that mice deficient in innate type 2 immunity experienced profound parturition delays when manipulated endocrinologically to circumvent luteolysis, thus obliging them to enter labor through uterus-intrinsic pathways. We found that these pathways were in part driven by the alarmin IL-33 produced by uterine interstitial fibroblasts. We also implicated important roles for uterine group 2 innate lymphoid cells, which demonstrated IL-33-dependent activation prior to labor onset, and eosinophils, which displayed evidence of elevated turnover in the prepartum uterus. These findings reveal a role for innate type 2 immunity in controlling the timing of labor onset through a cascade potentially relevant to human parturition.

Keywords:  IL-33; eosinophils; group 2 innate lymphoid cells; myometrium; parturition; preterm labor

DOI:  https://doi.org/10.1016/j.immuni.2023.01.005
Front Endocrinol (Lausanne). 2023 ;14 1060675

Metabolic stress-induced human beta-cell death is mediated by increased intracellular levels of adenosine.

Anongnad Ngamjariyawat, Jing Cen, Romain Said, Ceren Incedal, Olof Idevall-Hagren, Nils Welsh.

   Introduction: High intracellular concentrations of adenosine and 2'-deoxyadenosine have been suggested to be an important mediator of cell death. The aim of the present study was to characterize adenosine-induced death in insulin-producing beta-cells, at control and high glucose + palmitate-induced stress conditions.
Methods: Human insulin-producing EndoC-betaH1 cells were treated with adenosine, 2'-deoxyadenosine, inosine and high glucose + sodium palmitate, and death rates using flow cytometry were studied.
Results: We observed that adenosine and the non-receptor-activating analogue 2-deoxyadenosine, but not the adenosine deamination product inosine, promoted beta-cell apoptosis at concentrations exceeding maximal adenosine-receptor stimulating concentrations. Both adenosine and inosine were efficiently taken up by EndoC-betaH1 cells, and inosine counteracted the cell death promoting effect of adenosine by competing with adenosine for uptake. Both adenosine and 2'-deoxyadenosine promptly reduced insulin-stimulated production of plasma membrane PI(3,4,5)P3, an effect that was reversed upon wash out of adenosine. In line with this, adenosine, but not inosine, rapidly diminished Akt phosphorylation. Both pharmacological Bax inhibition and Akt activation blocked adenosine-induced beta-cell apoptosis, indicating that adenosine/2'-deoxyadenosine inhibits the PI3K/Akt/BAD anti-apoptotic pathway. High glucose + palmitate-induced cell death was paralleled by increased intracellular adenosine and inosine levels. Overexpression of adenosine deaminase-1 (ADA1) in EndoC-betaH1 cells, which increased Akt phosphorylation, prevented both adenosine-induced apoptosis and high glucose + palmitate-induced necrosis. ADA2 overexpression not only failed to protect against adenosine and high glucose + palmitate-activated cell death, but instead potentiated the apoptosis-stimulating effect of adenosine. In line with this, ADA1 overexpression increased inosine production from adenosine-exposed cells, whereas ADA2 did not. Knockdown of ADA1 resulted in increased cell death rates in response to both adenosine and high glucose + palmitate. Inhibition of miR-30e-3p binding to the ADA1 mRNA 3'-UTR promoted the opposite effects on cell death rates and reduced intracellular adenosine contents.
Discussion: It is concluded that intracellular adenosine/2'-deoxyadenosine regulates negatively the PI3K pathway and is therefore an important mediator of beta-cell apoptosis. Adenosine levels are controlled, at least in part, by ADA1, and strategies to upregulate ADA1 activity, during conditions of metabolic stress, could be useful in attempts to preserve beta-cell mass in diabetes.

Keywords:  PIP3K-signaling; adenosine; apoptosis; beta-cells; metabolic stress; sodium palmitate

DOI:  https://doi.org/10.3389/fendo.2023.1060675
Front Immunol. 2023 ;14 1100041

25-hydroxyvitamin D3 generates immunomodulatory plasticity in human periodontal ligament-derived mesenchymal stromal cells that is inflammatory context-dependent.

Christian Behm, Alice Blufstein, Johannes Gahn, Andreas Moritz, Xiaohui Rausch-Fan, Oleh Andrukhov.

   Introduction: Human periodontal ligament-derived mesenchymal stromal cells (hPDL-MSCs) exhibit a tight bi-directional interaction with CD4+ T lymphocytes. The hPDL-MSCs' immunomodulatory abilities are drastically enhanced by pro-inflammatory cytokines via boosting the expression of various immunomediators. 25-hydroxyvitamin D3 (25(OH)D3), the major metabolite of vitamin D3 in the blood, affects both hPDL-MSCs and CD4+ T lymphocytes, but its influence on their interaction is unknown.
Methods: Therefore, primary hPDL-MSCs were stimulated in vitro with tumor necrosis factor (TNF)-α a or interleukin (IL)-1β in the absence and presence of 25(OH)D3 followed by an indirect co-culture with phytohemagglutinin-activated CD4+ T lymphocytes. The CD4+ T lymphocyte proliferation, viability, and cytokine secretion were analyzed. Additionally, the expression of various immunomediators in hPDL-MSCs was investigated, and their implication was verified by using pharmacological inhibitors.
Results: 25(OH)D3 significantly counteracted the suppressive effects of IL-1β-treated hPDL-MSCs on CD4+ T lymphocyte proliferation, whereas no effects were observed in the presence of TNF-α. Additionally, 25(OH)D3 significantly increased the percentage of viable CD4+ T lymphocytes via TNF-α- or IL-1β-treated hPDL-MSCs. It also caused a significant decrease in interferon-γ, IL-17A, and transforming growth factor-β productions, which were triggered by TNF-α-treated hPDL-MSCs. 25(OH)D3 significantly decreased the production of various immunomediators in hPDL-MSCs. Inhibition of two of them, prostaglandin E2 and indoleamine-2,3-dioxygenase-1, partially abolished some of the hPDL-MSCs-mediated effects of 25(OH)D3 on CD4+ T lymphocytes.
Conclusion: These data indicate that 25(OH)D3 influences the immunomodulatory activities of hPDL-MSCs. This modulatory potential seems to have high plasticity depending on the local cytokine conditions and may be involved in regulating periodontal tissue inflammatory processes.

Keywords:  25-hydroxyvitamin D3; immunomodulation; interleukin-1 beta; mesenchymal stromal cells; periodontal ligament; tumor necrosis factor alpha

DOI:  https://doi.org/10.3389/fimmu.2023.1100041
Front Immunol. 2023 ;14 1105244

Dendritic cell phenotype and function in a 3D co-culture model of patient-derived metastatic colorectal cancer organoids.

Beatriz Subtil, Kirti K Iyer, Dennis Poel, Lotte Bakkerus, Mark A J Gorris, Jorge Cuenca Escalona, Koen van den Dries, Alessandra Cambi, Henk M W Verheul, I Jolanda M de Vries, Daniele V F Tauriello.

  Colorectal cancer (CRC) remains one of the most aggressive and lethal cancers, with metastasis accounting for most deaths. As such, there is an unmet need for improved therapies for metastatic CRC (mCRC). Currently, the research focus is shifting towards the reciprocal interactions within the tumor microenvironment (TME), which prevent tumor clearance by the immune system. Dendritic cells (DCs) play a key role in the initiation and amplification of anti-tumor immune responses and in driving the clinical success of immunotherapies. Dissecting the interactions between DCs and CRC cells may open doors to identifying key mediators in tumor progression, and possible therapeutic targets. This requires representative, robust and versatile models and tools. Currently, there is a shortage of such in vitro systems to model the CRC TME and its tumor-immune cell interactions. Here we develop and establish a dynamic organotypic 3D co-culture system to recapitulate and untangle the interactions between DCs and patient-derived mCRC tumor organoids. To our knowledge, this is the first study investigating human DCs in co-culture with tumor organoids in a 3D, organotypic setting. This system reveals how mCRC organoids modulate and shape monocyte-derived DCs (MoDCs) behavior, phenotype, and function, within a collagen matrix, using techniques such as brightfield and fluorescence microscopy, flow cytometry, and fluorescence-activated cell sorting. Our 3D co-culture model shows high viability and extensive interaction between DCs and tumor organoids, and its structure resembles patient tissue sections. Furthermore, it is possible to retrieve DCs from the co-cultures and characterize their phenotypic and functional profile. In our study, the expression of activation markers in both mature and immature DCs and their ability to activate T cells were impacted by co-culture with tumor organoids. In the future, this direct co-culture platform can be adapted and exploited to study the CRC-DC interplay in more detail, enabling novel and broader insights into CRC-driven DC (dys)function.

Keywords:  3D co-culture; dendritic cell dysfunction; human dendritic cells; immunosuppression; metastatic colorectal cancer; patient-derived tumor organoids; tumor microenvironment

DOI:  https://doi.org/10.3389/fimmu.2023.1105244
Front Oncol. 2023 ;13 1034205

Hypoxia induced lactate acidosis modulates tumor microenvironment and lipid reprogramming to sustain the cancer cell survival.

Lakhveer Singh, Lakshmi Nair, Dinesh Kumar, Mandeep Kumar Arora, Sakshi Bajaj, Manoj Gadewar, Shashank Shekher Mishra, Santosh Kumar Rath, Amit Kumar Dubey, Gaurav Kaithwas, Manjusha Choudhary, Manjari Singh.

  It is well known that solid hypoxic tumour cells oxidise glucose through glycolysis, and the end product of this pathway is fermented into lactate which accumulates in the tumour microenvironment (TME). Initially, it was proclaimed that cancer cells cannot use lactate; therefore, they dump it into the TME and subsequently augment the acidity of the tumour milieu. Furthermore, the TME acts as a lactate sink with stope variable amount of lactate in different pathophysiological condition. Regardless of the amount of lactate pumped out within TME, it disappears immediately which still remains an unresolved puzzle. Recent findings have paved pathway in exploring the main role of lactate acidosis in TME. Cancer cells utilise lactate in the de novo fatty acid synthesis pathway to initiate angiogenesis and invasiveness, and lactate also plays a crucial role in the suppression of immunity. Furthermore, lactate re-programme the lipid biosynthetic pathway to develop a metabolic symbiosis in normoxic, moderately hypoxic and severely hypoxic cancer cells. For instance: severely hypoxic cancer cells enable to synthesizing poly unsaturated fatty acids (PUFA) in oxygen scarcity secretes excess of lactate in TME. Lactate from TME is taken up by the normoxic cancer cells whereas it is converted back to PUFAs after a sequence of reactions and then liberated in the TME to be utilized in the severely hypoxic cancer cells. Although much is known about the role of lactate in these biological processes, the exact molecular pathways that are involved remain unclear. This review attempts to understand the molecular pathways exploited by lactate to initiate angiogenesis, invasiveness, suppression of immunity and cause re-programming of lipid synthesis. This review will help the researchers to develop proper understanding of lactate associated bimodal regulations of TME.

Keywords:  HIF-1α; Immunity; Lipid reprogramming ; angiogenesis; hypoxia; invasiveness; lactate; resistance

DOI:  https://doi.org/10.3389/fonc.2023.1034205
JCI Insight. 2023 Feb 07. pii: e154940. [Epub ahead of print]

Adipose-targeted SWELL1 deletion exacerbates obesity and age-related non-alcoholic fatty liver disease.

Susheel K Gunasekar, John Heebink, Danielle H Carpenter, Ashutosh Kumar, Litao Xie, Haixia Zhang, Joel D Schilling, Rajan Sah.

  Healthy expansion of adipose tissue is critical for the maintenance of metabolic health - providing an optimized reservoir for energy storage in the form of triacylglycerol-rich lipoproteins. Dysfunctional adipocytes that are unable to efficiently store lipid can result in lipodystrophy and contribute to nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome. LRRC8a/SWELL1 functionally encodes the volume-regulated anion channel (VRAC) complex in adipocytes, is induced in early obesity, and required for normal adipocyte expansion during high-fat feeding. Adipose-specific SWELL1 ablation (Adipo KO) leads to insulin resistance and hyperglycemia during caloric excess, both of which are associated with NAFLD. Here, we show that Adipo KO mice exhibit impaired adipose depot expansion and excess lipolysis when raised on a variety of high-fat diets, resulting in increased diacylglycerides and hepatic steatosis thereby driving liver injury. Liver lipidomic analysis revealed increases in oleic acid containing hepatic triacylglycerides and injurious hepatic diacylglyceride species, with reductions in hepatocyte protective phospholipids, and anti-inflammatory free fatty acids. Aged Adipo KO mice develop hepatic steatosis on a regular chow diet, and Adipo KO male mice develop spontaneous, aggressive hepatocellular carcinomas (HCC). These data highlight the importance of adipocyte SWELL1 for healthy adipocyte expansion to protect against NAFLD and HCC in the setting of over nutrition and with aging.

Keywords:  Adipose tissue; Glucose metabolism; Hepatology; Liver cancer; Metabolism

DOI:  https://doi.org/10.1172/jci.insight.154940
Nat Rev Immunol. 2023 Feb 08.

Control of immune cell function by the unfolded protein response.

Giusy Di Conza, Ping-Chih Ho, Juan R Cubillos-Ruiz, Stanley Ching-Cheng Huang.

Initiating and maintaining optimal immune responses requires high levels of protein synthesis, folding, modification and trafficking in leukocytes, which are processes orchestrated by the endoplasmic reticulum. Importantly, diverse extracellular and intracellular conditions can compromise the protein-handling capacity of this organelle, inducing a state of 'endoplasmic reticulum stress' that activates the unfolded protein response (UPR). Emerging evidence shows that physiological or pathological activation of the UPR can have effects on immune cell survival, metabolism, function and fate. In this Review, we discuss the canonical role of the adaptive UPR in immune cells and how dysregulation of this pathway in leukocytes contributes to diverse pathologies such as cancer, autoimmunity and metabolic disorders. Furthermore, we provide an overview as to how pharmacological approaches that modulate the UPR could be harnessed to control or activate immune cell function in disease.

DOI: https://doi.org/10.1038/s41577-023-00838-0
Sci Adv. 2023 Feb 10. 9(6): eade5584

Metabolite asymmetric dimethylarginine (ADMA) functions as a destabilization enhancer of SOX9 mediated by DDAH1 in osteoarthritis.

Yizheng Wu, Shuying Shen, Jiaxin Chen, Weiyu Ni, Qinxin Wang, Hongyi Zhou, Junxin Chen, Haitao Zhang, Zixuan Mei, Xuewu Sun, Panyang Shen, Zhiwei Jie, Wenbin Xu, Zhenghua Hong, Yan Ma, Kefan Wang, Shuanglin Wan, Hongfei Wu, Ziang Xie, An Qin, Shunwu Fan.

Osteoarthritis (OA) is a degenerative disease with a series of metabolic changes accompanied by many altered enzymes. Here, we report that the down-regulated dimethylarginine dimethylaminohydrolase-1 (DDAH1) is accompanied by increased asymmetric dimethylarginine (ADMA) in degenerated chondrocytes and in OA samples. Global or chondrocyte-conditional knockout of ADMA hydrolase DDAH1 accelerated OA development in mice. ADMA induces the degeneration and senescence of chondrocytes and reduces the extracellular matrix deposition, thereby accelerating OA progression. ADMA simultaneously binds to SOX9 and its deubiquitinating enzyme USP7, blocking the deubiquitination effects of USP7 on SOX9 and therefore leads to SOX9 degradation. The ADMA level in synovial fluids of patients with OA is increased and has predictive value for OA diagnosis with good sensitivity and specificity. Therefore, activating DDAH1 to reduce ADMA level might be a potential therapeutic strategy for OA treatment.

DOI: https://doi.org/10.1126/sciadv.ade5584
J Gastroenterol. 2023 Feb 05.

LAT1 expression influences Paneth cell number and tumor development in ApcMin/+ mice.

Yunlong Sui, Namiko Hoshi, Ryuichi Ohgaki, Lingling Kong, Ryutaro Yoshida, Norihiro Okamoto, Masato Kinoshita, Haruka Miyazaki, Yuna Ku, Eri Tokunaga, Yuki Ito, Daisuke Watanabe, Makoto Ooi, Masakazu Shinohara, Kengo Sasaki, Yoh Zen, Takenori Kotani, Takashi Matozaki, Zibin Tian, Yoshikatsu Kanai, Yuzo Kodama.

   BACKGROUND: Amino acid transporters play an important role in supplying nutrition to cells and are associated with cell proliferation. L-type amino acid transporter 1 (LAT1) is highly expressed in many types of cancers and promotes tumor growth; however, how LAT1 affects tumor development is not fully understood.
METHODS: To investigate the role of LAT1 in intestinal tumorigenesis, mice carrying LAT1 floxed alleles that also expressed Cre recombinase from the promoter of gene encoding Villin were crossed to an ApcMin/+ background (LAT1fl/fl; vil-cre; ApcMin/+), which were subject to analysis; organoids derived from those mice were also analyzed.
RESULTS: This study showed that LAT1 was constitutively expressed in normal crypt base cells, and its conditional deletion in the intestinal epithelium resulted in fewer Paneth cells. LAT1 deletion reduced tumor size and number in the small intestine of ApcMin/+ mice. Organoids derived from LAT1-deleted ApcMin/+ intestinal crypts displayed fewer spherical organoids with reduced Wnt/β-catenin target gene expression, suggesting a low tumor-initiation capacity. Wnt3 expression was decreased in the absence of LAT1 in the intestinal epithelium, suggesting that loss of Paneth cells due to LAT1 deficiency reduced the risk of tumor initiation by decreasing Wnt3 production.
CONCLUSIONS: LAT1 affects intestinal tumor development in a cell-extrinsic manner through reduced Wnt3 expression in Paneth cells. Our findings may partly explain how nutrient availability can affect the risk of tumor development in the intestines.

Keywords:  Cancer; L-type amino acid transporter 1; Paneth cells; Wnt3; mTORC1

DOI:  https://doi.org/10.1007/s00535-023-01960-5
J Exp Clin Cancer Res. 2023 Feb 07. 42(1): 42

GPX8 regulates clear cell renal cell carcinoma tumorigenesis through promoting lipogenesis by NNMT.

Tin Tin Manh Nguyen, Thi Ha Nguyen, Han Sun Kim, Thien T P Dao, Yechan Moon, Munjun Seo, Sunmi Kang, Van-Hieu Mai, Yong Jin An, Cho-Rok Jung, Jin-Mo Kim, Sunghyouk Park.

   BACKGROUND: Clear cell renal cell carcinoma (ccRCC), with its hallmark phenotype of high cytosolic lipid content, is considered a metabolic cancer. Despite the implication of this lipid-rich phenotype in ccRCC tumorigenesis, the roles and regulators of de novo lipid synthesis (DNL) in ccRCC remain largely unexplained.
METHODS: Our bioinformatic screening focused on ccRCC-lipid phenotypes identified glutathione peroxidase 8 (GPX8), as a clinically relevant upstream regulator of DNL. GPX8 genetic silencing was performed with CRISPR-Cas9 or shRNA in ccRCC cell lines to dissect its roles. Untargeted metabolomics, RNA-seq analyses, and other biochemical assays (e.g., lipid droplets staining, fatty acid uptake, cell proliferation, xenograft, etc.) were carried out to investigate the GPX8's involvement in lipid metabolism and tumorigenesis in ccRCC. The lipid metabolic function of GPX8 and its downstream were also measured by isotope-tracing-based DNL flux measurement.
RESULTS: GPX8 knockout or downregulation substantially reduced lipid droplet levels (independent of lipid uptake), fatty acid de novo synthesis, triglyceride esterification in vitro, and tumor growth in vivo. The downstream regulator was identified as nicotinamide N-methyltransferase (NNMT): its knockdown phenocopied, and its expression rescued, GPX8 silencing both in vitro and in vivo. Mechanically, GPX8 regulated NNMT via IL6-STAT3 signaling, and blocking this axis suppressed ccRCC survival by activating AMPK. Notably, neither the GPX8-NNMT axis nor the DNL flux was affected by the von Hippel Lindau (VHL) status, the conventional regulator of ccRCC high lipid content.
CONCLUSIONS: Taken together, our findings unravel the roles of the VHL-independent GPX8-NNMT axis in ccRCC lipid metabolism as related to the phenotypes and growth of ccRCC, which may be targeted for therapeutic purposes.

Keywords:  AMPK; Clear cell renal cell carcinoma (ccRCC); De novo lipogenesis (DNL); GPX8; NNMT

DOI:  https://doi.org/10.1186/s13046-023-02607-2
Front Immunol. 2023 ;14 1118449

Programmed cell death and lipid metabolism of macrophages in NAFLD.

Zhun Xiao, Minghao Liu, Fangming Yang, Guangwei Liu, Jiangkai Liu, Wenxia Zhao, Suping Ma, Zhongping Duan.

  Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored.

Keywords:  inflammation; lipid metabolism; macrophages; non-alcoholic fatty liver disease; programmed cell death

DOI:  https://doi.org/10.3389/fimmu.2023.1118449
JCI Insight. 2023 Feb 08. pii: e165369. [Epub ahead of print]8(3):

Notch-mediated hepatocyte MCP-1 secretion causes liver fibrosis.

Jinku Kang, Jorge Postigo-Fernandez, KyeongJin Kim, Changyu Zhu, Junjie Yu, Marica Meroni, Brent Mayfield, Alberto Bartolomé, Dianne H Dapito, Anthony W Ferrante, Paola Dongiovanni, Luca Valenti, Remi J Creusot, Utpal B Pajvani.

  Patients with nonalcoholic steatohepatitis (NASH) have increased expression of liver monocyte chemoattractant protein-1 (MCP-1), but its cellular source and contribution to various aspects of NASH pathophysiology remain debated. We demonstrated increased liver CCL2 (which encodes MCP-1) expression in patients with NASH, and commensurately, a 100-fold increase in hepatocyte Ccl2 expression in a mouse model of NASH, accompanied by increased liver monocyte-derived macrophage (MoMF) infiltrate and liver fibrosis. To test repercussions of increased hepatocyte-derived MCP-1, we generated hepatocyte-specific Ccl2-knockout mice, which showed reduced liver MoMF infiltrate as well as decreased liver fibrosis. Forced hepatocyte MCP-1 expression provoked the opposite phenotype in chow-fed wild-type mice. Consistent with increased hepatocyte Notch signaling in NASH, we observed a close correlation between markers of Notch activation and CCL2 expression in patients with NASH. We found that an evolutionarily conserved Notch/recombination signal binding protein for immunoglobulin kappa J region binding site in the Ccl2 promoter mediated transactivation of the Ccl2 promoter in NASH diet-fed mice. Increased liver MoMF infiltrate and liver fibrosis seen in opposite gain-of-function mice was ameliorated with concomitant hepatocyte Ccl2 knockout or CCR2 inhibitor treatment. Hepatocyte Notch activation prompts MCP-1-dependent increase in liver MoMF infiltration and fibrosis.

Keywords:  Chemokines; Fibrosis; Gastroenterology; Metabolism

DOI:  https://doi.org/10.1172/jci.insight.165369
Cell Rep. 2023 Feb 07. pii: S2211-1247(23)00103-1. [Epub ahead of print]42(2): 112092

CD206+ macrophages transventricularly infiltrate the early embryonic cerebral wall to differentiate into microglia.

Yuki Hattori, Daisuke Kato, Futoshi Murayama, Sota Koike, Hisa Asai, Ayato Yamasaki, Yu Naito, Ayano Kawaguchi, Hiroyuki Konishi, Marco Prinz, Takahiro Masuda, Hiroaki Wake, Takaki Miyata.

  The relationships between tissue-resident microglia and early macrophages, especially their lineage segregation outside the yolk sac, have been recently explored, providing a model in which a conversion from macrophages seeds microglia during brain development. However, spatiotemporal evidence to support such microglial seeding in situ and to explain how it occurs has not been obtained. By cell tracking via slice culture, intravital imaging, and Flash tag-mediated or genetic labeling, we find that intraventricular CD206+ macrophages, which are abundantly observed along the inner surface of the mouse cerebral wall, frequently enter the pallium at embryonic day 12. Immunofluorescence of the tracked cells show that postinfiltrative macrophages in the pallium acquire microglial properties while losing the CD206+ macrophage phenotype. We also find that intraventricular macrophages are supplied transepithelially from the roof plate. This study demonstrates that the "roof plate→ventricle→pallium" route is an essential path for microglial colonization into the embryonic mouse brain.

Keywords:  CP: Developmental biology; CP: Immunology; brain; cerebrum; cortex; developing brain; live imaging; macrophage; microglia; two-photon microscopy; ventricle

DOI:  https://doi.org/10.1016/j.celrep.2023.112092
Cell Host Microbe. 2023 Feb 08. pii: S1931-3128(23)00034-3. [Epub ahead of print]31(2): 173-186

Gut microbiome lipid metabolism and its impact on host physiology.

Eric M Brown, Jon Clardy, Ramnik J Xavier.

  Metabolites produced by commensal gut microbes impact host health through their recognition by the immune system and their influence on numerous metabolic pathways. Notably, the gut microbiota can both transform and synthesize lipids as well as break down dietary lipids to generate secondary metabolites with host modulatory properties. Although lipids have largely been consigned to structural roles, particularly in cell membranes, recent research has led to an increased appreciation of their signaling activities, with potential impacts on host health and physiology. This review focuses on studies that highlight the functions of bioactive lipids in mammalian physiology, with a special emphasis on immunity and metabolism.

Keywords:  PUFAs; autoimmune disease; bacteria; cholesterol; diet; inflammation; innate immunity; lipids; metabolism; microbiome; phospholipids; sphingolipids

DOI:  https://doi.org/10.1016/j.chom.2023.01.009