Polyribonucleotide nucleotidyltransferase 1 (Pnpt1) plays critical roles in mitochondrial homeostasis by controlling mitochondrial RNA (mt-RNA) processing, trafficking and degradation. Pnpt1 deficiency results in mitochondrial dysfunction that triggers a type I interferon response, suggesting a role in inflammation. However, the role of Pnpt1 in inflammasome activation remains largely unknown. In this study, we generated myeloid-specific Pnpt1-knockout mice and demonstrated that Pnpt1 depletion enhanced interleukin-1 beta (IL-1β) and interleukin-18 (IL-18) secretion in a mouse sepsis model. Using cultured peritoneal and bone marrow-derived macrophages, we demonstrated that Pnpt1 regulated NLRP3 inflammasome-dependent IL-1β release in response to lipopolysaccharide (LPS), followed by nigericin, ATP or poly (I:C) treatment. Pnpt1 deficiency in macrophages increased glycolysis after LPS administration and mt-reactive oxygen species (mt-ROS) after NLRP3 inflammasome activation. Pnpt1 activation of the inflammasome was dependent on increased glycolysis and the expression of mitochondrial antiviral-signaling protein (MAVS) but not NF-κB signaling. Collectively, these data suggest that Pnpt1 is an important mediator of inflammation, as shown by activation of the NLRP3 inflammasome in murine sepsis and cultured macrophages.
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All data generated or analyzed during this study are included in this published paper and in its supplementary file.
Timblin GA, Tharp KM, Ford B, Winchester JM, Wang J, Zhu S, et al. Mitohormesis reprogrammes macrophage metabolism to enforce tolerance. Nat Metab. 2021;3:618–35.
Hooftman A, Angiari S, Hester S, Corcoran SE, Runtsch MC, Ling C, et al. The Immunomodulatory Metabolite Itaconate Modifies NLRP3 and Inhibits Inflammasome Activation. Cell Metab. 2020;32:468–78 e7.
Chen HW, Rainey RN, Balatoni CE, Dawson DW, Troke JJ, Wasiak S, et al. Mammalian polynucleotide phosphorylase is an intermembrane space RNase that maintains mitochondrial homeostasis. Mol Cell Biol. 2006;26:8475–87.
Borowski LS, Dziembowski A, Hejnowicz MS, Stepien PP, Szczesny RJ. Human mitochondrial RNA decay mediated by PNPase-hSuv3 complex takes place in distinct foci. Nucleic Acids Res. 2013;41:1223–40.
Slomovic S, Schuster G. Stable PNPase RNAi silencing: its effect on the processing and adenylation of human mitochondrial RNA. Rna 2008;14:310–23.
Wang G, Chen HW, Oktay Y, Zhang J, Allen EL, Smith GM, et al. PNPASE regulates RNA import into mitochondria. Cell 2010;142:456–67.
Bamborschke D, Kreutzer M, Koy A, Koerber F, Lucas N, Huenseler C, et al. PNPT1 mutations may cause Aicardi-Goutieres-Syndrome. Brain Dev. 2021;43:320–4.
von Ameln S, Wang G, Boulouiz R, Rutherford MA, Smith GM, Li Y, et al. A mutation in PNPT1, encoding mitochondrial-RNA-import protein PNPase, causes hereditary hearing loss. Am J Hum Genet. 2012;91:919–27.
Alodaib A, Sobreira N, Gold WA, Riley LG, Van Bergen NJ, Wilson MJ, et al. Whole-exome sequencing identifies novel variants in PNPT1 causing oxidative phosphorylation defects and severe multisystem disease. Eur J Hum Genet. 2016;25:79–84.
Dhir A, Dhir S, Borowski LS, Jimenez L, Teitell M, Rötig A, et al. Mitochondrial double-stranded RNA triggers antiviral signalling in humans. Nature 2018;560:238–42.
Ghosh S, Guimaraes JC, Lanzafame M, Schmidt A, Syed AP, Dimitriades B, et al. Prevention of dsRNA-induced interferon signaling by AGO1x is linked to breast cancer cell proliferation. EMBO J. 2020;39:e103922.
Mangan MSJ, Olhava EJ, Roush WR, Seidel HM, Glick GD, Latz E. Targeting the NLRP3 inflammasome in inflammatory diseases. Nat Rev Drug Discov. 2018;17:688.
Grebe A, Hoss F, Latz E. NLRP3 Inflammasome and the IL-1 Pathway in Atherosclerosis. Circ Res. 2018;122:1722–40.
Duewell P, Kono H, Rayner KJ, Sirois CM, Vladimer G, Bauernfeind FG, et al. NLRP3 inflammasomes are required for atherogenesis and activated by cholesterol crystals. Nature 2010;464:1357–61.
McKee CM, Coll RC. NLRP3 inflammasome priming: A riddle wrapped in a mystery inside an enigma. J Leukoc Biol. 2020;108:937–52.
Huang Y, Xu W, Zhou R. NLRP3 inflammasome activation and cell death. Cell Mol Immunol. 2021;18:2114–27.
He WT, Wan H, Hu L, Chen P, Wang X, Huang Z, et al. Gasdermin D is an executor of pyroptosis and required for interleukin-1beta secretion. Cell Res. 2015;25:1285–98.
Kayagaki N, Stowe IB, Lee BL, O’Rourke K, Anderson K, Warming S, et al. Caspase-11 cleaves gasdermin D for non-canonical inflammasome signalling. Nature 2015;526:666–71.
Shi J, Zhao Y, Wang K, Shi X, Wang Y, Huang H, et al. Cleavage of GSDMD by inflammatory caspases determines pyroptotic cell death. Nature 2015;526:660–5.
Zhong Z, Liang S, Sanchez-Lopez E, He F, Shalapour S, Lin XJ, et al. New mitochondrial DNA synthesis enables NLRP3 inflammasome activation. Nature 2018;560:198–203.
Subramanian N, Natarajan K, Clatworthy MR, Wang Z, Germain RN. The adaptor MAVS promotes NLRP3 mitochondrial localization and inflammasome activation. Cell 2013;153:348–61.
Evavold CL, Hafner-Bratkovic I, Devant P, D’Andrea JM, Ngwa EM, Borsic E, et al. Control of gasdermin D oligomerization and pyroptosis by the Ragulator-Rag-mTORC1 pathway. Cell 2021;184:4495–511 e19.
Dominic A, Le NT, Takahashi M. Loop Between NLRP3 Inflammasome and Reactive Oxygen Species. Antioxid Redox Signal. 2022;36:784–96.
Zhou R, Yazdi AS, Menu P, Tschopp J. A role for mitochondria in NLRP3 inflammasome activation. Nature 2011;469:221–5.
Rajan JV, Warren SE, Miao EA, Aderem A. Activation of the NLRP3 inflammasome by intracellular poly I:C. FEBS Lett. 2010;584:4627–32.
Kanneganti TD, Body-Malapel M, Amer A, Park JH, Whitfield J, Franchi L, et al. Critical role for Cryopyrin/Nalp3 in activation of caspase-1 in response to viral infection and double-stranded RNA. J Biol Chem. 2006;281:36560–8.
Seth RB, Sun L, Ea CK, Chen ZJ. Identification and characterization of MAVS, a mitochondrial antiviral signaling protein that activates NF-kappaB and IRF 3. Cell 2005;122:669–82.
McGettrick AF, O’Neill LAJ. The Role of HIF in Immunity and Inflammation. Cell Metab. 2020;32:524–36.
Hughes MM, O’Neill LAJ. Metabolic regulation of NLRP3. Immunol Rev. 2018;281:88–98.
Tannahill GM, Curtis AM, Adamik J, Palsson-McDermott EM, McGettrick AF, Goel G, et al. Succinate is an inflammatory signal that induces IL-1beta through HIF-1alpha. Nature 2013;496:238–42.
Wculek SK, Dunphy G, Heras-Murillo I, Mastrangelo A, Sancho D. Metabolism of tissue macrophages in homeostasis and pathology. Cell Mol Immunol. 2022;19:384–408.
Virag L, Jaen RI, Regdon Z, Bosca L, Prieto P. Self-defense of macrophages against oxidative injury: Fighting for their own survival. Redox Biol. 2019;26:101261.
Hughes MM, Hooftman A, Angiari S, Tummala P, Zaslona Z, Runtsch MC, et al. Glutathione Transferase Omega-1 Regulates NLRP3 Inflammasome Activation through NEK7 Deglutathionylation. Cell Rep. 2019;29:151–61 e5.
Zhang T, Tsutsuki H, Islam W, Ono K, Takeda K, Akaike T, et al. ATP exposure stimulates glutathione efflux as a necessary switch for NLRP3 inflammasome activation. Redox Biol. 2021;41:101930.
Zhang Z, Xu X, Ma J, Wu J, Wang Y, Zhou R, et al. Gene deletion of Gabarap enhances Nlrp3 inflammasome-dependent inflammatory responses. J Immunol. 2013;190:3517–24.
Fleischmann C, Scherag A, Adhikari NK, Hartog CS, Tsaganos T, Schlattmann P, et al. Assessment of Global Incidence and Mortality of Hospital-treated Sepsis. Current Estimates and Limitations. Am J Respir Crit Care Med. 2016;193:259–72.
Hsu CG, Chavez CL, Zhang C, Sowden M, Yan C, Berk BC. The lipid peroxidation product 4-hydroxynonenal inhibits NLRP3 inflammasome activation and macrophage pyroptosis. Cell Death Differ. 2022;29:1790–803.
Griffiths RJ, Stam EJ, Downs JT, Otterness IG. ATP induces the release of IL-1 from LPS-primed cells in vivo. J Immunol. 1995;154:2821–8.
Chi H. Immunometabolism at the intersection of metabolic signaling, cell fate, and systems immunology. Cell Mol Immunol. 2022;19:299–302.
Paik S, Kim JK, Silwal P, Sasakawa C, Jo EK. An update on the regulatory mechanisms of NLRP3 inflammasome activation. Cell Mol Immunol. 2021;18:1141–60.
Shimada E, Ahsan FM, Nili M, Huang D, Atamdede S, TeSlaa T, et al. PNPase knockout results in mtDNA loss and an altered metabolic gene expression program. PLoS ONE. 2018;13:e0200925.
Freemerman AJ, Johnson AR, Sacks GN, Milner JJ, Kirk EL, Troester MA, et al. Metabolic reprogramming of macrophages: glucose transporter 1 (GLUT1)-mediated glucose metabolism drives a proinflammatory phenotype. J Biol Chem. 2014;289:7884–96.
Zhang W, Wang G, Xu ZG, Tu H, Hu F, Dai J, et al. Lactate Is a Natural Suppressor of RLR Signaling by Targeting MAVS. Cell 2019;178:176–89 e15.
Lepelley A, Wai T, Crow YJ. Mitochondrial Nucleic Acid as a Driver of Pathogenic Type I Interferon Induction in Mendelian Disease. Front Immunol. 2021;12:729763.
Franchi L, Eigenbrod T, Munoz-Planillo R, Ozkurede U, Kim YG, Arindam C, et al. Cytosolic double-stranded RNA activates the NLRP3 inflammasome via MAVS-induced membrane permeabilization and K+ efflux. J Immunol. 2014;193:4214–22.
Buskiewicz IA, Montgomery T, Yasewicz EC, Huber SA, Murphy MP, Hartley RC, et al. Reactive oxygen species induce virus-independent MAVS oligomerization in systemic lupus erythematosus. Sci Signal. 2016;9:ra115.
O’Neill LA, Hardie DG. Metabolism of inflammation limited by AMPK and pseudo-starvation. Nature 2013;493:346–55.
Nishimura K, Aizawa S, Nugroho FL, Shiomitsu E, Tran YTH, Bui PL, et al. A Role for KLF4 in Promoting the Metabolic Shift via TCL1 during Induced Pluripotent Stem Cell Generation. Stem Cell Rep. 2017;8:787–801.
Grochowska J, Czerwinska J, Borowski LS, Szczesny RJ. Mitochondrial RNA, a new trigger of the innate immune system. Wiley Interdiscip Rev RNA. 2022;13:e1690.
Park S, Juliana C, Hong S, Datta P, Hwang I, Fernandes-Alnemri T, et al. The mitochondrial antiviral protein MAVS associates with NLRP3 and regulates its inflammasome activity. J Immunol. 2013;191:4358–66.
Jo EK, Kim JK, Shin DM, Sasakawa C. Molecular mechanisms regulating NLRP3 inflammasome activation. Cell Mol Immunol. 2016;13:148–59.
Falchi FA, Pizzoccheri R, Briani F. Activity and Function in Human Cells of the Evolutionary Conserved Exonuclease Polynucleotide Phosphorylase. Int J Mol Sci. 2022;23:1652.
Yin L, Li W, Xu A, Shi H, Wang K, Yang H, et al. SH3BGRL2 inhibits growth and metastasis in clear cell renal cell carcinoma via activating hippo/TEAD1-Twist1 pathway. EBioMedicine 2020;51:102596.
Hsu CG, Fazal F, Rahman A, Berk BC, Yan C. Phosphodiesterase 10A Is a Key Mediator of Lung Inflammation. J Immunol. 2021;206:3010–20.
Tweedell RE, Malireddi RKS, Kanneganti TD. A comprehensive guide to studying inflammasome activation and cell death. Nat Protoc. 2020;15:3284–333.
Zhang C, Hsu CG, Mohan A, Shi H, Li D, Yan C. Vinpocetine protects against the development of experimental abdominal aortic aneurysms. Clin Sci (Lond). 2020;134:2959–76.
We thank Amanda Pereira and Sharon Senchanthisai for assistance with the maintenance and breeding of mice.
This work was financially supported by the National Institute of Health (HL140958 to BCB), the Department of Defense (DM190884 to BCB), New York State Department of Health (C34726GG to BCB and CGH), University of Rochester Environmental Health Sciences Center (P30 ES001247 to BCB), and the National Natural Science Foundation of China (No. 82200268 to WJL).
The authors declare no competing interests.
All of the experiments were approved by the University Committee on Animal Use for Research (UCAR) at the University of Rochester and followed the National Institutes of Health guidelines for experimental procedures on mice.
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Hsu, C.G., Li, W., Sowden, M. et al. Pnpt1 mediates NLRP3 inflammasome activation by MAVS and metabolic reprogramming in macrophages. Cell Mol Immunol 20, 131–142 (2023). https://doi.org/10.1038/s41423-022-00962-2