Metabolism
Abstract
Brown adipose tissue (BAT), a crucial heat-generating organ, regulate whole-body energy metabolism by mediating thermogenesis. BAT inflammation is implicated in the pathogenesis of mitochondrial dysfunction and impaired thermogenesis. However, the link between BAT inflammation and systematic metabolism remains unclear. Herein, we use mice with BAT deficiency of thioredoxin-2 (TRX2), a protein that scavenges mitochondrial reactive oxygen species (ROS), to evaluate the impact of BAT inflammation on metabolism and thermogenesis and its underlying mechanism. Our results describe that BAT-specific TRX2 ablation improves systematic metabolic performance via enhancing lipid uptake, which protects mice from diet-induced obesity, hypertriglyceridemia, and insulin resistance. TRX2 deficiency impairs adaptive thermogenesis by suppressing fatty acid oxidation. Mechanistically, loss of TRX2 induces excessive mitochondrial ROS, mitochondrial integrity disruption, and cytosolic release of mitochondrial DNA, which in turn activate aberrant innate immune responses in BAT, including the cGAS-STING and the NLRP3 inflammasome pathways. We identify NLRP3 as a key converging point, as its inhibition reverses both the thermogenesis defect and the metabolic benefits seen under nutrient overload in BAT-specific Trx2-deficient mice. In conclusion, we identify TRX2 as a critical hub integrating oxidative stress, inflammation, and lipid metabolism in BAT; uncovering an adaptive mechanism underlying the link between BAT inflammation and systematic metabolism.
Authors
Yanrui Huang, Jenny H. Zhou, Haifeng Zhang, Alberto Canfrán-Duque, Abhishek K. Singh, Rachel J. Perry, Gerald Shulman, Carlos Fernandez-Hernando, Wang Min
Abstract
CD8+ T cell longevity regulated by metabolic activity plays important roles in cancer immunotherapy. Although in vitro polarized, transferred IL-9-secreting CD8+ Tc9 cells exert greater persistence and antitumor efficacy than Tc1/CTL cells, the underlying mechanism remains unclear. Here, we show that tumor-infiltrating Tc9 cells display significantly lower lipid peroxidation than Tc1 cells in several mouse models, which is strongly correlated with their persistence. Using RNA-sequence and functional validation, we found that Tc9 cells exhibited unique lipid metabolic programs. Tc9 cell-derived IL-9 activated STAT3, upregulated fatty acid oxidation and mitochondrial activity, and rendered Tc9 cells with reduced lipid peroxidation and resistant to tumor or ROS induced ferroptosis in TME. IL-9 signal deficiency, inhibiting STAT3 or fatty acid oxidation increased lipid peroxidation and ferroptosis of Tc9 cells, resulting in impaired longevity and antitumor ability. Similarly, human Tc9 cells also possessed lower lipid peroxidation than Tc1 cells and tumor-infiltrating CD8+ T cells expressed lower IL-9 and higher lipid peroxidation- and ferroptosis-related genes than circulating CD8+ T cells in melanoma patients. This study indicates that lipid peroxidation regulates Tc9-cell longevity and antitumor effects via IL-9-STAT3-fatty acid oxidation pathway and regulating T-cell lipid peroxidation can be used to enhance T-cell based immunotherapy in human cancer.
Authors
Liuling Xiao, Xingzhe Ma, Lingqun Ye, Pan Su, Wei Xiong, Enguang Bi, Qiang Wang, Miao Xian, Maojie Yang, Jianfei Qian, Qing Yi
Abstract
The functional integrity of CD8+ T cells is tightly coupled to metabolic reprogramming, but how oxidative stress directs CD8+ T cell metabolic fitness in the tumor microenvironment (TME) remains elusive. Here, we report that SUMO-specific protease 7 (SENP7) senses oxidative stress to maintain the CD8+ T cell metabolic state and antitumor functions. SENP7-deficient CD8+ T cells exhibited decreased glycolysis and oxidative phosphorylation, resulting in attenuated proliferation in vitro and dampened antitumor functions in vivo. Mechanistically, CD8+ T cell-derived reactive oxygen species (ROS) triggered cytosolic SENP7-mediated PTEN deSUMOylation, thereby promoting PTEN degradation and preventing PTEN-dependent metabolic defects. Importantly, lowering T cell-intrinsic ROS restricted SENP7 cytosolic translocation and repressed CD8+ T cell metabolic and functional activity in human colorectal cancer samples. Our findings reveal that SENP7, as an oxidative stress sensor, sustains CD8+ T cell metabolic fitness and effector functions and unveil an oxidative stress-sensing machinery in tumor-infiltrating CD8+ T cells.
Authors
Zhongqiu Wu, Haiyan Huang, Qiaoqiao Han, Zhilin Hu, Xiao-Lu Teng, Rui Ding, Youqiong Ye, Xiaoyan Yu, Ren Zhao, Zhengting Wang, Qiang Zou
Abstract
Multiple beneficial cardiovascular effects of HDL are dependent on sphingosine-1-phosphate (S1P). S1P associates with HDL by binding to apolipoprotein M (ApoM). Insulin resistance is a major driver of dyslipidemia and cardiovascular risk. However, the mechanisms linking alterations in insulin signaling with plasma lipoprotein metabolism are incompletely understood. The insulin-repressible FoxO transcription factors play a key role in mediating the effects of hepatic insulin action on glucose and lipoprotein metabolism. This work aims to determine whether hepatic insulin signaling regulates HDL-S1P, and the underlying molecular mechanisms.We report that insulin resistant, nondiabetic human subjects in two independent cohorts have decreased HDL-S1P levels, but no change in total plasma S1P. This also occurs in the mouse model of insulin resistance, db/db mice, which have low ApoM and a specific reduction of S1P in the HDL fraction, with no change in total plasma S1P. Using mice with hepatocyte deletion of the three insulin-repressible FoxO transcription factors (L-FoxO1,3,4), we found that hepatic FoxOs are required for ApoM expression and S1P association with HDL, without affecting total plasma S1P. In L-FoxO1,3,4 mice, total plasma S1P levels are similar to controls, but S1P is nearly absent from HDL, and is instead increased in the lipoprotein depleted plasma fraction. This phenotype is restored to normal by rescuing ApoM in L-FoxO1,3,4 mice. Our findings show that insulin resistance in humans and mice is associated with decreased HDL-associated S1P. Hepatic FoxO transcription factors are novel regulators of the ApoM-S1P pathway.
Authors
María Concepción Izquierdo, Niroshan Shanmugarajah, Samuel X. Lee, Michael J. Kraakman, Marit Westerterp, Takumi Kitamoto, Michael Harris, Joshua R. Cook, Galina A. Gusarova, Kendra Zhong, Elijah Marbuary, InSug O-Sullivan, Nikolaus F. Rasmus, Stefania Camastra, Terry G. Unterman, Ele Ferrannini, Barry E. Hurwitz, Rebecca A. Haeusler
Abstract
Bin/amphiphysin/Rvs (BAR) domains are positively charged crescent-shaped modules that shape negatively charged curved lipid membranes during membrane remodeling processes. The BAR domain proteins ICA69, PICK1 and arfaptins have recently been demonstrated to coordinate the budding and formation of immature secretory granules (ISGs) at the trans-Golgi network. Here, we identify four coding variants in the PICK1 gene from a Danish whole-exome screening of diabetic patients, that all involve change of positively charged residues in the PICK1 BAR domain. All four coding variants failed to rescue the insulin content in INS-1E cells upon KD of endogenous PICK1. Moreover, two variants showed dominant negative properties. Interestingly, in vitro assays addressing the BAR domain function suggest that the coding variants accentuated capacity to cause fission of small liposomes. Live confocal microscopy and super-resolution microscopy further revealed that PICK1 resides transiently on ISGs before egress via vesicular budding events. Interestingly, this egress of PICK1 was accelerated in the coding variants. We propose that PICK1 assists or complements the removal of excess membrane and generic membrane trafficking proteins, and possibly also insulin from ISGs during the maturation process and that the coding variants may cause premature budding possibly explaining their dominant negative function.
Authors
Rita C. Andersen, Jan H. Schmidt, Joscha Rombach, Matthew D. Lycas, Nikolaj R. Christensen, Viktor K. Lund, Donald S. Stapleton, Signe S. Pedersen, Mathias A. Olsen, Mikkel Stoklund, Gith Noes-Holt, Tommas T.E. Nielsen, Mark P. Keller, Anna M. Jansen, Rasmus Herlo, Massimo Pietropaolo, Jens B. Simonsen, Ole Kjærulff, Birgitte Holst, Alan D. Attie, Ulrik Gether, Kenneth L. Madsen
Abstract
Inborn errors of nucleic acid metabolism often cause aberrant activation of nucleic acid sensing pathways, leading to autoimmune or autoinflammatory diseases. The SKIV2L RNA exosome is cytoplasmic RNA degradation machinery that was thought to be essential for preventing the self-RNA–mediated interferon (IFN) response. Here, we demonstrate the physiological function of SKIV2L in mammals. We found that Skiv2l deficiency in mice disrupted epidermal and T cell homeostasis in a cell-intrinsic manner independently of IFN. Skiv2l-deficient mice developed skin inflammation and hair abnormality, which were also observed in a SKIV2L-deficient patient. Epidermis-specific deletion of Skiv2l caused hyperproliferation of keratinocytes and disrupted epidermal stratification, leading to impaired skin barrier with no appreciable IFN activation. Moreover, Skiv2l-deficient T cells were chronically hyperactivated and these T cells attacked lesional skin as well as hair follicles. Mechanistically, SKIV2L loss activated the mTORC1 pathway in both keratinocytes and T cells. Both systemic and topical rapamycin treatment of Skiv2l-deficient mice ameliorated epidermal hyperplasia and skin inflammation. Together, we demonstrate that mTORC1, a classical nutrient sensor, also senses cytoplasmic RNA quality control failure and drives autoinflammatory disease. We also propose SKIV2L-associated trichohepatoenteric syndrome (THES) as a new mTORopathy for which sirolimus may be a promising therapy.
Authors
Kun Yang, Jie Han, Mayumi Asada, Jennifer G. Gill, Jason Y. Park, Meghana N. Sathe, Jyothsna Gattineni, Tracey Wright, Christian A. Wysocki, M. Teresa de la Morena, Luis A. Garza, Nan Yan
Abstract
BACKGROUND. Fasting and NAD+-boosting compounds including NAD+ precursor nicotinamide riboside (NR) confer anti-inflammatory effects. However, the underlying mechanisms and therapeutic potential are incompletely defined. METHODS. We explored the underlying biology in myeloid cells from healthy volunteers following in-vivo placebo or NR administration and subsequently tested the findings in-vitro in monocytes extracted from subjects with systemic lupus erythematosus (SLE). RESULTS. RNA sequencing of unstimulated and lipopolysaccharide (LPS)-activated monocytes implicate NR in the regulation of autophagy and type I interferon signaling. In primary monocytes NR blunts LPS-induced IFNβ production and genetic or pharmacologic disruption of autophagy phenocopies this effect. Given NAD+ is a co-enzyme in oxidoreductive reactions, metabolomics was performed and identified that NR increased inosine level. Inosine supplementation similarly blunts autophagy and IFNβrelease. Finally, as SLE exhibits type I interferon dysregulation, we assessed the NR effect on SLE patient monocytes and found that NR reduces autophagy and interferon-β release. CONCLUSION. We conclude that NR, in an NAD+-dependent manner and in part via inosine-signaling, mediates suppression of autophagy and attenuates type I interferon in myeloid cells and identifies NR as a potential adjunct for SLE management. TRIAL REGISTRATION. ClinicalTrails.gov registration numbers: NCT02812238, NCT00001846 and NCT00001372. FUNDING. This work was supported by the NHLBI and NIAMS Divisions of Intramural Research.
Authors
Jing Wu, Komudi Singh, Amy Lin, Allison M. Meadows, Kaiyuan Wu, Vivian Shing, Maximilian Bley, Shahin Hassanzadeh, Rebecca D. Huffstutler, Mark S. Schmidt, Luz P. Blanco, Rong Tian, Charles Brenner, Mehdi Pirooznia, Mariana J. Kaplan, Michael N. Sack
Abstract
Authors
George Kunos, Tony Jourdan, Joseph Tam
Abstract
Authors
Simeng Wang, Qingzhang Zhu, Guosheng Liang, Tania Franks, Magalie Boucher, Kendra K. Bence, Mingjian Lu, Carlos M. Castorena, Shangang Zhao, Joel K. Elmquist, Philipp E. Scherer, Jay D. Horton
Abstract
BACKGROUND. Care management of Parkinson’s disease (PD) patients currently remains symptomatic, mainly because diagnosis relying on the expression of the cardinal motor symptoms is made too late. Earlier detecting PD therefore represents a key step for developing therapies able to delay or slow down its progression. METHODS. We investigated metabolic markers in three different animal models of PD, mimicking different phases of the disease assessed by behavioral and histological evaluation, and in 3 cohorts of de novo PD patients and matched controls (n = 129). Serum and brain tissue samples were analyzed by nuclear magnetic resonance spectroscopy and data submitted to advanced multivariate statistics. RESULTS. Our translational strategy reveals common metabolic dysregulations in serum of the different animal models and PD patients. Some of them were mirrored in the tissue samples, possibly reflecting pathophysiological mechanisms associated with PD development. Interestingly, some metabolic dysregulations appeared before motor symptom emergence, and could represent early biomarkers of PD. Finally, we built a composite biomarker with a combination of 6 metabolites. This biomarker discriminated animals mimicking PD from controls, even from the first, non-motor signs and very interestingly, also discriminated PD patients from healthy subjects. CONCLUSION. From our translational study which included three animal models and three de novo PD patient cohorts, we propose a promising biomarker exhibiting a high accuracy for de novo PD diagnosis and may possibly predict early PD development, before motor symptoms appearance. FUNDINGS. ANR, DOPALCOMP, Institut National de la Santé et de la Recherche Médicale, Université Grenoble Alpes.
Authors
David Mallet, Thibault Dufourd, Mélina Decourt, Carole Carcenac, Paola Bossù, Laure Verlin, Pierre-Olivier Fernagut, Marianne Benoit-Marand, Gianfranco Spalletta, Emmanuel L. Barbier, Sebastien Carnicella, Véronique Sgambato, Florence Fauvelle, Sabrina Boulet
Copyright © 2022 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)