1
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Cabello AL, Wells K, Peng W, Feng HQ, Wang J, Meyer DF, Noroy C, Zhao ES, Zhang H, Li X, Chang H, Gomez G, Mao Y, Patrick KL, Watson RO, Russell WK, Yu A, Zhong J, Guo F, Li M, Zhou M, Qian X, Kobayashi KS, Song J, Panthee S, Mechref Y, Ficht TA, Qin QM, de Figueiredo P. Brucella-driven host N-glycome remodeling controls infection. Cell Host Microbe 2024; 32:588-605.e9. [PMID: 38531364 DOI: 10.1016/j.chom.2024.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 08/28/2023] [Accepted: 03/06/2024] [Indexed: 03/28/2024]
Abstract
Many powerful methods have been employed to elucidate the global transcriptomic, proteomic, or metabolic responses to pathogen-infected host cells. However, the host glycome responses to bacterial infection remain largely unexplored, and hence, our understanding of the molecular mechanisms by which bacterial pathogens manipulate the host glycome to favor infection remains incomplete. Here, we address this gap by performing a systematic analysis of the host glycome during infection by the bacterial pathogen Brucella spp. that cause brucellosis. We discover, surprisingly, that a Brucella effector protein (EP) Rhg1 induces global reprogramming of the host cell N-glycome by interacting with components of the oligosaccharide transferase complex that controls N-linked protein glycosylation, and Rhg1 regulates Brucella replication and tissue colonization in a mouse model of brucellosis, demonstrating that Brucella exploits the EP Rhg1 to reprogram the host N-glycome and promote bacterial intracellular parasitism, thereby providing a paradigm for bacterial control of host cell infection.
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Affiliation(s)
- Ana-Lucia Cabello
- Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77843, USA; Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Kelsey Wells
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO 65211, USA
| | - Wenjing Peng
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Hui-Qiang Feng
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Junyao Wang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Damien F Meyer
- CIRAD, UMR ASTRE, 97170 Petit-Bourg, Guadeloupe, France; ASTRE, University Montpellier, CIRAD, INRAE, Montpellier, France
| | - Christophe Noroy
- CIRAD, UMR ASTRE, 97170 Petit-Bourg, Guadeloupe, France; ASTRE, University Montpellier, CIRAD, INRAE, Montpellier, France
| | - En-Shuang Zhao
- College of Computer Science and Technology, Jilin University, Changchun 130012, China
| | - Hao Zhang
- College of Computer Science and Technology, Jilin University, Changchun 130012, China
| | - Xueqing Li
- College of Computer Science and Technology, Jilin University, Changchun 130012, China
| | - Haowu Chang
- College of Computer Science and Technology, Jilin University, Changchun 130012, China
| | - Gabriel Gomez
- Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL), Texas A&M University, College Station, TX 77843, USA
| | - Yuxin Mao
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2703, USA
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - William K Russell
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-0635, USA
| | - Aiying Yu
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Jieqiang Zhong
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Fengguang Guo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Mingqian Li
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 78843, USA
| | - Mingyuan Zhou
- Department of Information, Risk, and Operations Management, Department of Statistics and Data Sciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Xiaoning Qian
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 78843, USA; TEES-AgriLife Center for Bioinformatics & Genomic Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Koichi S Kobayashi
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA; Department of Immunology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; Hokkaido University, Institute for Vaccine Research and Development (HU-IVReD), Sapporo 060-8638, Japan
| | - Jianxun Song
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Suresh Panthee
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Yehia Mechref
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA.
| | - Thomas A Ficht
- Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77843, USA.
| | - Qing-Ming Qin
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO 65211, USA.
| | - Paul de Figueiredo
- Christopher S. Bond Life Sciences Center, Department of Molecular Microbiology and Immunology, School of Medicine, The University of Missouri, Columbia, MO 65211, USA; Department of Veterinary Pathobiology, The University of Missouri, Columbia, MO 65211, USA.
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2
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Scott HM, Smith MH, Coleman AK, Armijo KS, Chapman MJ, Apostalo SL, Wagner AR, Watson RO, Patrick KL. Serine/arginine-rich splicing factor 7 promotes the type I interferon response by activating Irf7 transcription. Cell Rep 2024; 43:113816. [PMID: 38393946 PMCID: PMC11056844 DOI: 10.1016/j.celrep.2024.113816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 12/19/2023] [Accepted: 02/02/2024] [Indexed: 02/25/2024] Open
Abstract
Tight regulation of macrophage immune gene expression is required to fight infection without risking harmful inflammation. The contribution of RNA-binding proteins (RBPs) to shaping the macrophage response to pathogens remains poorly understood. Transcriptomic analysis reveals that a member of the serine/arginine-rich (SR) family of mRNA processing factors, SRSF7, is required for optimal expression of a cohort of interferon-stimulated genes in macrophages. Using genetic and biochemical assays, we discover that in addition to its canonical role in regulating alternative splicing, SRSF7 drives transcription of interferon regulatory transcription factor 7 (IRF7) to promote antiviral immunity. At the Irf7 promoter, SRSF7 maximizes STAT1 transcription factor binding and RNA polymerase II elongation via cooperation with the H4K20me1 histone methyltransferase KMT5a (SET8). These studies define a role for an SR protein in activating transcription and reveal an RBP-chromatin network that orchestrates macrophage antiviral gene expression.
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Affiliation(s)
- Haley M Scott
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Mackenzie H Smith
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Aja K Coleman
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Kaitlyn S Armijo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Morgan J Chapman
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Summer L Apostalo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Allison R Wagner
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA.
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3
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Azam S, Armijo KS, Weindel CG, Chapman MJ, Devigne A, Nakagawa S, Hirose T, Carpenter S, Watson RO, Patrick KL. The early macrophage response to pathogens requires dynamic regulation of the nuclear paraspeckle. Proc Natl Acad Sci U S A 2024; 121:e2312587121. [PMID: 38381785 PMCID: PMC10907238 DOI: 10.1073/pnas.2312587121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 01/10/2024] [Indexed: 02/23/2024] Open
Abstract
To ensure a robust immune response to pathogens without risking immunopathology, the kinetics and amplitude of inflammatory gene expression in macrophages need to be exquisitely well controlled. There is a growing appreciation for stress-responsive membraneless organelles (MLOs) regulating various steps of eukaryotic gene expression in response to extrinsic cues. Here, we implicate the nuclear paraspeckle, a highly ordered biomolecular condensate that nucleates on the Neat1 lncRNA, in tuning innate immune gene expression in murine macrophages. In response to a variety of innate agonists, macrophage paraspeckles rapidly aggregate (0.5 h poststimulation) and disaggregate (2 h poststimulation). Paraspeckle maintenance and aggregation require active transcription and MAPK signaling, whereas paraspeckle disaggregation requires degradation of Neat1 via the nuclear RNA exosome. In response to lipopolysaccharide treatment, Neat1 KO macrophages fail to properly express a large cohort of proinflammatory cytokines, chemokines, and antimicrobial mediators. Consequently, Neat1 KO macrophages cannot control replication of Salmonella enterica serovar Typhimurium or vesicular stomatitis virus. These findings highlight a prominent role for MLOs in orchestrating the macrophage response to pathogens and support a model whereby dynamic assembly and disassembly of paraspeckles reorganizes the nuclear landscape to enable inflammatory gene expression following innate stimuli.
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Affiliation(s)
- Sikandar Azam
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, School of Medicine, Bryan, TX77807
| | - Kaitlyn S. Armijo
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, School of Medicine, Bryan, TX77807
| | - Chi G. Weindel
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, School of Medicine, Bryan, TX77807
| | - Morgan J. Chapman
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, School of Medicine, Bryan, TX77807
| | - Alice Devigne
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, CA95064
| | | | - Tetsuro Hirose
- RNA Biofunction Laboratory, Graduate School of Frontier Biosciences, Osaka University, Osaka565-0871, Japan
| | - Susan Carpenter
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, CA95064
| | - Robert O. Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, School of Medicine, Bryan, TX77807
| | - Kristin L. Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, School of Medicine, Bryan, TX77807
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4
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Ellzey LM, Patrick KL, Watson RO. Mitochondrial reactive oxygen species: double agents in Mycobacterium tuberculosis infection. Curr Opin Immunol 2023; 84:102366. [PMID: 37453340 DOI: 10.1016/j.coi.2023.102366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/23/2023] [Accepted: 06/14/2023] [Indexed: 07/18/2023]
Abstract
In addition to housing the major energy-producing pathways in cells, mitochondria are active players in innate immune responses. One critical way mitochondria fulfill this role is by releasing damage-associated molecular patterns (mtDAMPs) that are recognized by innate sensors to activate pathways including, but not limited to, cytokine expression, selective autophagy, and cell death. Mitochondrial reactive oxygen species (mtROS) is a multifunctional mtDAMP linked to pro- and antimicrobial immune outcomes. Formed as a by-product of energy generation, mtROS links mitochondrial metabolism with downstream innate immune responses. As a result, altered cellular metabolism can change mtROS levels and impact downstream antimicrobial responses in a variety of ways. MtROS has emerged as a particularly important mediator of pathogenesis during infection with Mycobacterium tuberculosis (Mtb), an intracellular bacterial pathogen that continues to pose a significant threat to global public health. Here, we will summarize how Mtb modulates mtROS levels in infected macrophages and how mtROS dictates Mtb infection outcomes by controlling inflammation, lipid peroxidation, and cell death. We propose that mtROS may serve as a biomarker to predict tuberculosis patient outcomes and/or a target for host-directed therapeutics.
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Affiliation(s)
- Lily M Ellzey
- Interdiscplinary Graduate Program in Genetics and Genomics, Texas A&M University, United States; Department of Microbial Pathogenesis and Immunology, Texas A&M University School of Medicine, United States
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M University School of Medicine, United States
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M University School of Medicine, United States.
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5
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Weindel CG, Ellzey LM, Martinez EL, Watson RO, Patrick KL. Gasdermins gone wild: new roles for GSDMs in regulating cellular homeostasis. Trends Cell Biol 2023; 33:773-787. [PMID: 37062616 PMCID: PMC10611448 DOI: 10.1016/j.tcb.2023.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 02/13/2023] [Accepted: 02/24/2023] [Indexed: 04/18/2023]
Abstract
Since their discovery, members of the gasdermin (GSDM) family of proteins have been firmly established as executors of pyroptosis, with the N-terminal fragment of most GSDMs capable of forming pores in the plasma membrane. More recent findings suggest that some GSDMs can drive additional cell death pathways, such as apoptosis and necroptosis, through mechanisms independent of plasma membrane perforation. There is also emerging evidence that by associating with cellular compartments such as mitochondria, peroxisomes, endosomes, and the nucleus, GSDMs regulate cell death-independent aspects of cellular homeostasis. Here, we review the diversity of GSDM function across several cell types and explore how various cellular stresses can promote relocalization - and thus refunctionalization - of GSDMs.
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Affiliation(s)
- Chi G Weindel
- Texas A&M University School of Medicine, Bryan, TX, USA
| | - Lily M Ellzey
- Texas A&M University School of Medicine, Bryan, TX, USA
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6
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Scott HM, Smith MH, Coleman AK, Apostalo SL, Wagner AR, Watson RO, Patrick KL. Serine arginine-rich splicing factor (SRSF7) cooperates with the histone methyltransferase KMT5a to promote the type I interferon response via transcriptional activation of IRF7. bioRxiv 2023:2023.05.09.540055. [PMID: 37503164 PMCID: PMC10369877 DOI: 10.1101/2023.05.09.540055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Tight regulation of macrophage immune gene expression is required to fight infection without risking harmful inflammation. The contribution of RNA binding proteins (RBPs) to shaping the macrophage response to pathogens remains poorly understood. Transcriptomic analysis revealed that a member of the serine/arginine-rich (SR) family of mRNA processing factors, SRSF7, is required for optimal expression of a cohort of interferon stimulated genes (ISGs) in macrophages. Using genetic and biochemical assays, we discovered that in addition to its canonical role in regulating alternative splicing, SRSF7 drives transcription of interferon regulatory transcription factor 7 (IRF7) to promote antiviral immunity. At the Irf7 promoter, SRSF7 maximizes STAT1 transcription factor binding and RNA polymerase II elongation via cooperation with the H4K20me1 histone methyltransferase KMT5a (SET8). These studies define an unorthodox role for an SR protein in activating transcription and reveal an unappreciated RNA binding protein-chromatin network that orchestrates macrophage antiviral gene expression.
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7
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Morrison HM, Craft J, Rivera-Lugo R, Johnson JR, Golovkine GR, Bell SL, Dodd CE, Van Dis E, Beatty WL, Margolis SR, Repasy T, Shaker I, Lee AY, Vance RE, Stanley SA, Watson RO, Krogan NJ, Portnoy DA, Penn BH, Cox JS. Deficiency in Galectin-3, -8, and -9 impairs immunity to chronic Mycobacterium tuberculosis infection but not acute infection with multiple intracellular pathogens. PLoS Pathog 2023; 19:e1011088. [PMID: 37352334 PMCID: PMC10325092 DOI: 10.1371/journal.ppat.1011088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 07/06/2023] [Accepted: 05/01/2023] [Indexed: 06/25/2023] Open
Abstract
Macrophages employ an array of pattern recognition receptors to detect and eliminate intracellular pathogens that access the cytosol. The cytosolic carbohydrate sensors Galectin-3, -8, and -9 (Gal-3, Gal-8, and Gal-9) recognize damaged pathogen-containing phagosomes, and Gal-3 and Gal-8 are reported to restrict bacterial growth via autophagy in cultured cells. However, the contribution of these galectins to host resistance during bacterial infection in vivo remains unclear. We found that Gal-9 binds directly to Mycobacterium tuberculosis (Mtb) and Salmonella enterica serovar Typhimurium (Stm) and localizes to Mtb in macrophages. To determine the combined contribution of membrane damage-sensing galectins to immunity, we generated Gal-3, -8, and -9 triple knockout (TKO) mice. Mtb infection of primary macrophages from TKO mice resulted in defective autophagic flux but normal bacterial replication. Surprisingly, these mice had no discernable defect in resistance to acute infection with Mtb, Stm or Listeria monocytogenes, and had only modest impairments in bacterial growth restriction and CD4 T cell activation during chronic Mtb infection. Collectively, these findings indicate that while Gal-3, -8, and -9 respond to an array of intracellular pathogens, together these membrane damage-sensing galectins play a limited role in host resistance to bacterial infection.
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Affiliation(s)
- Huntly M. Morrison
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Julia Craft
- Department of Internal Medicine, Division of Infectious Diseases, University of California, Davis, Davis, California, United States of America
| | - Rafael Rivera-Lugo
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Jeffery R. Johnson
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco; Quantitative Biosciences Institute (QBI), University of California, San Francisco; Gladstone Institutes, San Francisco, California, United States of America
| | - Guillaume R. Golovkine
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Samantha L. Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of Medicine, Bryan, Texas, United States of America
| | - Claire E. Dodd
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Erik Van Dis
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Wandy L. Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Shally R. Margolis
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Teresa Repasy
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Isaac Shaker
- Department of Internal Medicine, Division of Infectious Diseases, University of California, Davis, Davis, California, United States of America
| | - Angus Y. Lee
- Cancer Research Laboratory, University of California, Berkeley, Berkeley, California, United States of America
| | - Russell E. Vance
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Sarah A. Stanley
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
- School of Public Health, Division of Infectious Diseases and Vaccinology, University of California, Berkeley, Berkeley, California, United States of America
| | - Robert O. Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of Medicine, Bryan, Texas, United States of America
| | - Nevan J. Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco; Quantitative Biosciences Institute (QBI), University of California, San Francisco; Gladstone Institutes, San Francisco, California, United States of America
| | - Daniel A. Portnoy
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
| | - Bennett H. Penn
- Department of Internal Medicine, Division of Infectious Diseases, University of California, Davis, Davis, California, United States of America
| | - Jeffery S. Cox
- Department of Molecular and Cell Biology, Division of Immunology and Molecular Medicine, University of California, Berkeley, Berkeley, California, United States of America
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8
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Wagner AR, Weindel CG, West KO, Scott HM, Watson RO, Patrick KL. SRSF6 balances mitochondrial-driven innate immune outcomes through alternative splicing of BAX. eLife 2022; 11:e82244. [PMID: 36409059 PMCID: PMC9718523 DOI: 10.7554/elife.82244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 11/20/2022] [Indexed: 11/23/2022] Open
Abstract
To mount a protective response to infection while preventing hyperinflammation, gene expression in innate immune cells must be tightly regulated. Despite the importance of pre-mRNA splicing in shaping the proteome, its role in balancing immune outcomes remains understudied. Transcriptomic analysis of murine macrophage cell lines identified Serine/Arginine Rich Splicing factor 6 (SRSF6) as a gatekeeper of mitochondrial homeostasis. SRSF6-dependent orchestration of mitochondrial health is directed in large part by alternative splicing of the pro-apoptosis pore-forming protein BAX. Loss of SRSF6 promotes accumulation of BAX-κ, a variant that sensitizes macrophages to undergo cell death and triggers upregulation of interferon stimulated genes through cGAS sensing of cytosolic mitochondrial DNA. Upon pathogen sensing, macrophages regulate SRSF6 expression to control the liberation of immunogenic mtDNA and adjust the threshold for entry into programmed cell death. This work defines BAX alternative splicing by SRSF6 as a critical node not only in mitochondrial homeostasis but also in the macrophage's response to pathogens.
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Affiliation(s)
- Allison R Wagner
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of MedicineBryanUnited States
| | - Chi G Weindel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of MedicineBryanUnited States
| | - Kelsi O West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of MedicineBryanUnited States
| | - Haley M Scott
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of MedicineBryanUnited States
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of MedicineBryanUnited States
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, School of MedicineBryanUnited States
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9
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Weindel CG, Martinez EL, Zhao X, Mabry CJ, Bell SL, Vail KJ, Coleman AK, VanPortfliet JJ, Zhao B, Wagner AR, Azam S, Scott HM, Li P, West AP, Karpac J, Patrick KL, Watson RO. Mitochondrial ROS promotes susceptibility to infection via gasdermin D-mediated necroptosis. Cell 2022; 185:3214-3231.e23. [PMID: 35907404 PMCID: PMC9531054 DOI: 10.1016/j.cell.2022.06.038] [Citation(s) in RCA: 94] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 04/05/2022] [Accepted: 06/18/2022] [Indexed: 10/16/2022]
Abstract
Although mutations in mitochondrial-associated genes are linked to inflammation and susceptibility to infection, their mechanistic contributions to immune outcomes remain ill-defined. We discovered that the disease-associated gain-of-function allele Lrrk2G2019S (leucine-rich repeat kinase 2) perturbs mitochondrial homeostasis and reprograms cell death pathways in macrophages. When the inflammasome is activated in Lrrk2G2019S macrophages, elevated mitochondrial ROS (mtROS) directs association of the pore-forming protein gasdermin D (GSDMD) to mitochondrial membranes. Mitochondrial GSDMD pore formation then releases mtROS, promoting a switch to RIPK1/RIPK3/MLKL-dependent necroptosis. Consistent with enhanced necroptosis, infection of Lrrk2G2019S mice with Mycobacterium tuberculosis elicits hyperinflammation and severe immunopathology. Our findings suggest a pivotal role for GSDMD as an executer of multiple cell death pathways and demonstrate that mitochondrial dysfunction can direct immune outcomes via cell death modality switching. This work provides insights into how LRRK2 mutations manifest or exacerbate human diseases and identifies GSDMD-dependent necroptosis as a potential target to limit Lrrk2G2019S-mediated immunopathology.
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Affiliation(s)
- Chi G Weindel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Eduardo L Martinez
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Xiao Zhao
- Department of Molecular and Cellular Medicine, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Cory J Mabry
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA; Department of Microbiology, Biochemistry & Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - Krystal J Vail
- Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Division of Comparative Pathology, Tulane National Primate Research Center, Covington, LA 70433, USA
| | - Aja K Coleman
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Jordyn J VanPortfliet
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Baoyu Zhao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Allison R Wagner
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Sikandar Azam
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Haley M Scott
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Jason Karpac
- Department of Molecular and Cellular Medicine, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA.
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, TX 77807, USA.
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10
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Weindel CG, Zhao X, Martinez E, Bell SL, Vail KJ, Coleman AK, VanPortfliet JJ, Mabry CJ, Li P, West AP, Karpac J, Patrick KL, Watson RO. Gasdermin D promotes hyperinflammation by triggering necroptosis in the presence of mitochondrial stress. The Journal of Immunology 2022. [DOI: 10.4049/jimmunol.208.supp.52.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Human genetic variants associated with mitochondrial dysfunction have been linked to chronic inflammatory diseases as well as susceptibility to infection. However, the mechanistic impact that these variants have on the immune system is poorly understood. We have discovered that macrophages harboring the common Parkinson’s disease associated variant, Lrrk2G2019S are more prone to cell death in response to both Mycobacterium tuberculosis (Mtb) infection and AIM2 inflammasome activation. Unexpectedly, the enhanced cell death in Lrrk2G2019S macrophages is driven by increased susceptibility to gasdermin D (GSDMD)-mediated mitochondrial pore formation, which releases accumulated mitochondrial ROS and pushes Lrrk2G2019S cells to undergo RIPK3-mediated necroptosis. Consistent with elevated necroptotic cell death, infection of Lrrk2G2019S mice with Mtb elicits dramatic hyperinflammation and exacerbated pathogenesis via enhanced neutrophil infiltration. Remarkably, expression of hLRRK2G2019S in Drosophila melanogaster recapitulates a similar phenotype, suggesting that Lrrk2G2019S plays an evolutionarily conserved role in regulating innate immunity. Our findings demonstrate that altered mitochondrial function can reprogram canonical innate immune and cell death pathways to elicit distinct immune outcomes, providing mechanistic insights into why mutations in LRRK2 are associated with susceptibility to chronic inflammatory and infectious diseases.
Supported by grants from the Parkinson's Foundation (PF-FBS-1932), NIH (R01 AI125512), Michael J. Fox Foundation (grant 12185), and the Texas A&M Clinical Science and Translational Research (CSTR) Pilot Grant Program.
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Affiliation(s)
- Chi Gidley Weindel
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
| | - Xiao Zhao
- 2Department of Molecular and Cellular Medicine, Texas A&M Univ., Col. of Med
| | - Eduardo Martinez
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
| | - Samantha L. Bell
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
- 3Department of Microbiology, Biochemistry & Molecular Genetics, Rutgers New Jersey Med. Sch
| | - Krystal J. Vail
- 4Department of Veterinary Pathobiology, Texas A&M University College of Veterinary Medicine and Biomedical Sciences, Texas A&M Univ., Col. of Med
- 5Division of Comparative Pathology, Tulane Natl. Primate Res. Ctr
| | - Aja K. Coleman
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
| | | | - Cory J. Mabry
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
| | - Pingwei Li
- 6Department of Biochemistry and Biophysics, Texas A&M Univ., Col. of Med
| | - A. Phillip West
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
| | - Jason Karpac
- 2Department of Molecular and Cellular Medicine, Texas A&M Univ., Col. of Med
| | - Kristin L. Patrick
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
| | - Robert O. Watson
- 1Department of Microbial Pathogenesis and Immunology, Texas A&M Univ., Col. of Med
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11
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Cossu D, Watson RO, Farina C. Editorial: A Microbial View of Central Nervous System Disorders: Interplay Between Microorganisms, Neuroinflammation and Behaviour. Front Immunol 2021; 12:816227. [PMID: 34975927 PMCID: PMC8716445 DOI: 10.3389/fimmu.2021.816227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Davide Cossu
- Department of Neurology, Juntendo University, Tokyo, Japan
- Department of Biomedical Sciences, Sassari University, Sassari, Italy
| | - Robert O. Watson
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas Agricultural and Mechanical (A&M) Health Science Center, Bryan, TX, United States
| | - Cinthia Farina
- Institute of Experimental Neurology and Division of Neuroscience, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Scientific Institute, Milan, Italy
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12
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Vail KJ, da Silveira BP, Bell SL, Cohen ND, Bordin AI, Patrick KL, Watson RO. The opportunistic intracellular bacterial pathogen Rhodococcus equi elicits type I interferon by engaging cytosolic DNA sensing in macrophages. PLoS Pathog 2021; 17:e1009888. [PMID: 34473814 PMCID: PMC8443056 DOI: 10.1371/journal.ppat.1009888] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/15/2021] [Accepted: 08/12/2021] [Indexed: 11/18/2022] Open
Abstract
Rhodococcus equi is a major cause of foal pneumonia and an opportunistic pathogen in immunocompromised humans. While alveolar macrophages constitute the primary replicative niche for R. equi, little is known about how intracellular R. equi is sensed by macrophages. Here, we discovered that in addition to previously characterized pro-inflammatory cytokines (e.g., Tnfa, Il6, Il1b), macrophages infected with R. equi induce a robust type I IFN response, including Ifnb and interferon-stimulated genes (ISGs), similar to the evolutionarily related pathogen, Mycobacterium tuberculosis. Follow up studies using a combination of mammalian and bacterial genetics demonstrated that induction of this type I IFN expression program is largely dependent on the cGAS/STING/TBK1 axis of the cytosolic DNA sensing pathway, suggesting that R. equi perturbs the phagosomal membrane and causes DNA release into the cytosol following phagocytosis. Consistent with this, we found that a population of ~12% of R. equi phagosomes recruits the galectin-3,-8 and -9 danger receptors. Interestingly, neither phagosomal damage nor induction of type I IFN require the R. equi’s virulence-associated plasmid. Importantly, R. equi infection of both mice and foals stimulates ISG expression, in organs (mice) and circulating monocytes (foals). By demonstrating that R. equi activates cytosolic DNA sensing in macrophages and elicits type I IFN responses in animal models, our work provides novel insights into how R. equi engages the innate immune system and furthers our understanding how this zoonotic pathogen causes inflammation and disease. Rhodococcus equi is a facultative intracellular bacterial pathogen of horses and other domestic animals, as well as an opportunistic pathogen of humans. In human patients, Rhodococcus pneumonia bears some pathological similarities to pulmonary tuberculosis, and poses a risk for misdiagnosis. In horses, R. equi infection has a major detrimental impact on the equine breeding industry due to a lack of an efficacious vaccine and its ubiquitous distribution in soil. Given the prevalence of subclinical infection and high false positive rate in current screening methods, there exists a critical need to identify factors contributing to host susceptibility. Here, we use a combination of bacterial genetics and animal models to investigate innate immune responses during R. equi infection. We found that R. equi modulates host immune sensing to elicit a type I interferon response in a manner resembling that of M. tuberculosis. We also found that the danger sensors galectin-3, -8, and -9 are recruited to a population of R. equi-containing vacuoles, independent of expression of VapA. Our research identifies innate immune sensing events and immune transcriptional signatures that may lead to biomarkers for clinical disease, more accurate screening methods, and insight into susceptibility to infection.
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Affiliation(s)
- Krystal J. Vail
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
- Department of Veterinary Pathology, Texas A&M University, College Station, Texas, United States of America
| | - Bibiana Petri da Silveira
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Samantha L. Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
| | - Noah D. Cohen
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Angela I. Bordin
- Department of Large Animal Clinical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Kristin L. Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
| | - Robert O. Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, Texas, United States of America
- * E-mail:
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13
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Bell SL, Lopez KL, Cox JS, Patrick KL, Watson RO. Galectin-8 Senses Phagosomal Damage and Recruits Selective Autophagy Adapter TAX1BP1 To Control Mycobacterium tuberculosis Infection in Macrophages. mBio 2021; 12:e0187120. [PMID: 34225486 PMCID: PMC8406326 DOI: 10.1128/mbio.01871-20] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 06/03/2021] [Indexed: 12/26/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) causes one of the deadliest infectious diseases worldwide. Upon infection, Mtb is phagocytosed by macrophages and uses its virulence-associated ESX-1 secretion system to modulate the host cell. We showed previously that the ESX-1 secretion system perturbs the Mtb-containing phagosome, and a population (∼30%) of intracellular Mtb is tagged with ubiquitin and targeted to selective autophagy. However, our understanding of how macrophages sense and respond to damaged Mtb-containing phagosomes remains incomplete. Here, we demonstrate that several cytosolic glycan-binding proteins called galectins recognize Mtb-containing phagosomes; in macrophage cell lines and in primary macrophages, galectin-3, -8, and -9 are all recruited to the same Mtb population that colocalizes with selective autophagy markers (ubiquitin, p62, and LC3). To test whether galectins are required for controlling Mtb replication in macrophages, we generated CRISPR/Cas9 knockouts and found that galectin-8-/- and galectin-3/8/9-/- macrophages were similarly defective in targeting Mtb to selective autophagy and controlling replication. This suggests galectin-8 plays a unique role in anti-Mtb autophagy. In investigating galectin-8's role, we identified a novel and specific interaction between galectin-8 and the selective autophagy adapter TAX1BP1 and found that this galectin-8/TAX1BP1 interaction was necessary for macrophages to efficiently target Mtb to selective autophagy. Remarkably, overexpressing galectin-8 increased targeting of Mtb to autophagy and limited Mtb replication. Taken together, these data demonstrate that while several galectins are capable of recognizing damaged Mtb-containing phagosomes, galectin-8 plays a privileged role in recruiting downstream autophagy machinery and may represent a promising target for host-directed tuberculosis therapies. IMPORTANCE Mycobacterium tuberculosis (Mtb) infects one-quarter of the global population and causes one of the deadliest infectious diseases worldwide. Macrophages are the first line of defense against Mtb infection and are typically incredibly efficient at destroying intracellular pathogens, but Mtb has evolved to survive and replicate in this harsh environment. Previous work has found that a portion of intracellular Mtb bacilli damage their phagosomes, leaving them vulnerable to detection by the host and delivery to an antibacterial pathway called selective autophagy. Here, we show that in macrophages, galectin-8 recognizes damaged Mtb-containing phagosomes and targets Mtb to selective autophagy; we found that galectin-8, unlike other highly similar and closely related galectins, is required for targeting and controlling Mtb in macrophages. The specific role for galectin-8 appears to stem from its interaction with TAX1BP1, a selective autophagy adapter protein. Interestingly, overexpressing galectin-8 helps macrophages target and control Mtb, highlighting the importance of galectin-8 in the innate immune response to Mtb.
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Affiliation(s)
- Samantha L. Bell
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Kayla L. Lopez
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Jeffery S. Cox
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Kristin L. Patrick
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Bryan, Texas, USA
| | - Robert O. Watson
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health Science Center, Bryan, Texas, USA
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14
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Wagner AR, Scott HM, West KO, Vail KJ, Fitzsimons TC, Coleman AK, Carter KE, Watson RO, Patrick KL. Global Transcriptomics Uncovers Distinct Contributions From Splicing Regulatory Proteins to the Macrophage Innate Immune Response. Front Immunol 2021; 12:656885. [PMID: 34305890 PMCID: PMC8299563 DOI: 10.3389/fimmu.2021.656885] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 06/01/2021] [Indexed: 12/12/2022] Open
Abstract
Pathogen sensing via pattern recognition receptors triggers massive reprogramming of macrophage gene expression. While the signaling cascades and transcription factors that activate these responses are well-known, the role of post-transcriptional RNA processing in modulating innate immune gene expression remains understudied. Given their crucial role in regulating pre-mRNA splicing and other RNA processing steps, we hypothesized that members of the SR/hnRNP protein families regulate innate immune gene expression in distinct ways. We analyzed steady state gene expression and alternatively spliced isoform production in ten SR/hnRNP knockdown RAW 264.7 macrophage-like cell lines following infection with the bacterial pathogen Salmonella enterica serovar Typhimurium (Salmonella). We identified thousands of transcripts whose abundance is increased or decreased by SR/hnRNP knockdown in macrophages. Notably, we observed that SR and hnRNP proteins influence expression of different genes in uninfected versus Salmonella-infected macrophages, suggesting functionalization of these proteins upon pathogen sensing. Likewise, we found that knockdown of SR/hnRNPs promoted differential isoform usage (DIU) for thousands of macrophage transcripts and that these alternative splicing changes were distinct in uninfected and Salmonella-infected macrophages. Finally, having observed a surprising degree of similarity between the differentially expressed genes (DEGs) and DIUs in hnRNP K and U knockdown macrophages, we found that hnRNP K and U knockdown macrophages are both more restrictive to Vesicular Stomatitis Virus (VSV), while hnRNP K knockdown macrophages are more permissive to Salmonella Typhimurium. Based on these findings, we conclude that many innate immune genes evolved to rely on one or more SR/hnRNPs to ensure the proper magnitude of their induction, supporting a model wherein pre-mRNA splicing is critical for regulating innate immune gene expression and controlling infection outcomes in macrophages ex vivo.
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Affiliation(s)
- Allison R Wagner
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Haley M Scott
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Kelsi O West
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Krystal J Vail
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States.,Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, United States
| | - Timothy C Fitzsimons
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Aja K Coleman
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Kaitlyn E Carter
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M Health, Bryan, TX, United States
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15
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Lei Y, Guerra Martinez C, Torres-Odio S, Bell SL, Birdwell CE, Bryant JD, Tong CW, Watson RO, West LC, West AP. Elevated type I interferon responses potentiate metabolic dysfunction, inflammation, and accelerated aging in mtDNA mutator mice. Sci Adv 2021; 7:eabe7548. [PMID: 34039599 PMCID: PMC8153723 DOI: 10.1126/sciadv.abe7548] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 04/08/2021] [Indexed: 05/30/2023]
Abstract
Mitochondrial dysfunction is a key driver of inflammatory responses in human disease. However, it remains unclear whether alterations in mitochondria-innate immune cross-talk contribute to the pathobiology of mitochondrial disorders and aging. Using the polymerase gamma (POLG) mutator model of mitochondrial DNA instability, we report that aberrant activation of the type I interferon (IFN-I) innate immune axis potentiates immunometabolic dysfunction, reduces health span, and accelerates aging in mutator mice. Mechanistically, elevated IFN-I signaling suppresses activation of nuclear factor erythroid 2-related factor 2 (NRF2), which increases oxidative stress, enhances proinflammatory cytokine responses, and accelerates metabolic dysfunction. Ablation of IFN-I signaling attenuates hyperinflammatory phenotypes by restoring NRF2 activity and reducing aerobic glycolysis, which combine to lessen cardiovascular and myeloid dysfunction in aged mutator mice. These findings further advance our knowledge of how mitochondrial dysfunction shapes innate immune responses and provide a framework for understanding mitochondria-driven immunopathology in POLG-related disorders and aging.
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Affiliation(s)
- Yuanjiu Lei
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Camila Guerra Martinez
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Sylvia Torres-Odio
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Christine E Birdwell
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Joshua D Bryant
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Carl W Tong
- Department of Medical Physiology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - Laura Ciaccia West
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, USA.
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16
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Abstract
Within the last decade, we have learned that damaged mitochondria activate many of the same innate immune pathways that evolved to sense and respond to intracellular pathogens. These shared responses include cytosolic nucleic acid sensing and type I interferon (IFN) expression, inflammasome activation that leads to pyroptosis, and selective autophagy (called mitophagy when mitochondria are the cargo). Because mitochondria were once bacteria, parallels between how cells respond to mitochondrial and bacterial ligands are not altogether surprising. However, the potential for cross talk or synergy between bacterium- and mitochondrion-driven innate immune responses during infection remains poorly understood. This interplay is particularly striking, and intriguing, in the context of infection with the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb). Multiple studies point to a role for Mtb infection and/or specific Mtb virulence factors in disrupting the mitochondrial network in macrophages, leading to metabolic changes and triggering potent innate immune responses. Research from our laboratories and others argues that mutations in mitochondrial genes can exacerbate mycobacterial disease severity by hyperactivating innate responses or activating them at the wrong time. Indeed, growing evidence supports a model whereby different mitochondrial defects or mutations alter Mtb infection outcomes in distinct ways. By synthesizing the current literature in this minireview, we hope to gain insight into the molecular mechanisms driving, and consequences of, mitochondrion-dependent immune polarization so that we might better predict tuberculosis patient outcomes and develop host-directed therapeutics designed to correct these imbalances.
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Affiliation(s)
- Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, Texas, USA
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health, College of Medicine, Bryan, Texas, USA
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17
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Ding S, Yang J, Feng X, Pandey A, Barhoumi R, Zhang D, Bell SL, Liu Y, da Costa LF, Rice-Ficht A, Watson RO, Patrick KL, Qin QM, Ficht TA, de Figueiredo P. Interactions between fungal hyaluronic acid and host CD44 promote internalization by recruiting host autophagy proteins to forming phagosomes. iScience 2021; 24:102192. [PMID: 33718841 PMCID: PMC7920835 DOI: 10.1016/j.isci.2021.102192] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 01/06/2021] [Accepted: 02/09/2021] [Indexed: 01/22/2023] Open
Abstract
Phagocytosis and autophagy play critical roles in immune defense. The human fungal pathogen Cryptococcus neoformans (Cn) subverts host autophagy-initiation complex (AIC)-related proteins, to promote its phagocytosis and intracellular parasitism of host cells. The mechanisms by which the pathogen engages host AIC-related proteins remain obscure. Here, we show that the recruitment of host AIC proteins to forming phagosomes is dependent upon the activity of CD44, a host cell surface receptor that engages fungal hyaluronic acid (HA). This interaction elevates intracellular Ca2+ concentrations and activates CaMKKβ and its downstream target AMPKα, which results in activation of ULK1 and the recruitment of AIC components. Moreover, we demonstrate that HA-coated beads efficiently recruit AIC components to phagosomes and CD44 interacts with AIC components. Taken together, these findings show that fungal HA plays a critical role in directing the internalization and productive intracellular membrane trafficking of a fungal pathogen of global importance. Fungal HA drives non-canonical and ligand-induced autophagy in phagocytic cells Cn recruits host CD44 to forming phagocytic cups to initiate fungal internalization Fungal HA-CD44 interactions elevate intracellular Ca2+ levels and activate CaMKKβ A Ca2+-CaMKKβ-AMPK-ULK1 signaling axis is involved in HA-CD44 induced autophagy
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Affiliation(s)
- Shengli Ding
- College of Plant Sciences & Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, Jilin 130062, China.,Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA.,Department of Plant Pathology, College of Plant Protection, Henan Agricultural University, Zhengzhou, Henan 450002, China
| | - Jing Yang
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Xuehuan Feng
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Aseem Pandey
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA.,Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77843, USA
| | - Rola Barhoumi
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843-4458, USA
| | - Dongmei Zhang
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Yue Liu
- College of Plant Sciences & Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, Jilin 130062, China
| | - Luciana Fachini da Costa
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA.,Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA
| | - Allison Rice-Ficht
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Qing-Ming Qin
- College of Plant Sciences & Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, Jilin 130062, China.,Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Thomas A Ficht
- Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77843, USA
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA.,Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 77843, USA
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18
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West KO, Scott HM, Torres-Odio S, West AP, Patrick KL, Watson RO. The Splicing Factor hnRNP M Is a Critical Regulator of Innate Immune Gene Expression in Macrophages. Cell Rep 2020; 29:1594-1609.e5. [PMID: 31693898 PMCID: PMC6981299 DOI: 10.1016/j.celrep.2019.09.078] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/13/2019] [Accepted: 09/26/2019] [Indexed: 12/16/2022] Open
Abstract
While transcriptional control of innate immune gene expression is well characterized, almost nothing is known about how pre-mRNA splicing decisions influence, or are influenced by, macrophage activation. Here, we demonstrate that the splicing factor hnRNP M is a critical repressor of innate immune gene expression and that its function is regulated by pathogen sensing cascades. Loss of hnRNP M led to hyperinduction of a unique regulon of inflammatory and antimicrobial genes following diverse innate immune stimuli. While mutating specific serines on hnRNP M had little effect on its ability to control pre-mRNA splicing or transcript levels of housekeeping genes in resting macrophages, it greatly impacted the protein’s ability to dampen induction of specific innate immune transcripts following pathogen sensing. These data reveal a previously unappreciated role for pattern recognition receptor signaling in controlling splicing factor phosphorylation and establish pre-mRNA splicing as a critical regulatory node in defining innate immune outcomes. West et al. report that hnRNP M represses expression of a cohort of innate immune transcripts in infected macrophages. IL6 splicing repression is relieved when hnRNP M is phosphorylated at specific residues, demonstrating that post-translational modification of splicing factors downstream of pathogen sensing can control maturation of innate immune mRNAs.
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Affiliation(s)
- Kelsi O West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Haley M Scott
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Sylvia Torres-Odio
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA.
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807, USA.
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19
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Hoffpauir CT, Bell SL, West KO, Jing T, Wagner AR, Torres-Odio S, Cox JS, West AP, Li P, Patrick KL, Watson RO. TRIM14 Is a Key Regulator of the Type I IFN Response during Mycobacterium tuberculosis Infection. J Immunol 2020; 205:153-167. [PMID: 32404352 DOI: 10.4049/jimmunol.1901511] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/20/2020] [Indexed: 01/05/2023]
Abstract
Tripartite motif-containing proteins (TRIMs) play a variety of recently described roles in innate immunity. Although many TRIMs regulate type I IFN expression following cytosolic nucleic acid sensing of viruses, their contribution to innate immune signaling and gene expression during bacterial infection remains largely unknown. Because Mycobacterium tuberculosis is an activator of cGAS-dependent cytosolic DNA sensing, we set out to investigate a role for TRIM proteins in regulating macrophage responses to M. tuberculosis In this study, we demonstrate that TRIM14, a noncanonical TRIM that lacks an E3 ubiquitin ligase RING domain, is a critical negative regulator of the type I IFN response in Mus musculus macrophages. We show that TRIM14 interacts with both cGAS and TBK1 and that macrophages lacking TRIM14 dramatically hyperinduce IFN stimulated gene (ISG) expression following M. tuberculosis infection, cytosolic nucleic acid transfection, and IFN-β treatment. Consistent with a defect in resolution of the type I IFN response, Trim14 knockout macrophages have more phospho-Ser754 STAT3 relative to phospho-Ser727 and fail to upregulate the STAT3 target Socs3, which is required to turn off IFNAR signaling. These data support a model whereby TRIM14 acts as a scaffold between TBK1 and STAT3 to promote phosphorylation of STAT3 at Ser727 and resolve ISG expression. Remarkably, Trim14 knockout macrophages hyperinduce expression of antimicrobial genes like Nos2 and are significantly better than control cells at limiting M. tuberculosis replication. Collectively, these data reveal an unappreciated role for TRIM14 in resolving type I IFN responses and controlling M. tuberculosis infection.
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Affiliation(s)
- Caitlyn T Hoffpauir
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Kelsi O West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Tao Jing
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77807; and
| | - Allison R Wagner
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Sylvia Torres-Odio
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Jeffery S Cox
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77807; and
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX 77807;
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Weindel CG, Bell SL, Vail KJ, West KO, Patrick KL, Watson RO. LRRK2 maintains mitochondrial homeostasis and regulates innate immune responses to Mycobacterium tuberculosis. eLife 2020; 9:51071. [PMID: 32057291 PMCID: PMC7159881 DOI: 10.7554/elife.51071] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 02/14/2020] [Indexed: 12/11/2022] Open
Abstract
The Parkinson’s disease (PD)-associated gene leucine-rich repeat kinase 2 (LRRK2) has been studied extensively in the brain. However, several studies have established that mutations in LRRK2 confer susceptibility to mycobacterial infection, suggesting LRRK2 also controls immunity. We demonstrate that loss of LRRK2 in macrophages induces elevated basal levels of type I interferon (IFN) and interferon stimulated genes (ISGs) and causes blunted interferon responses to mycobacterial pathogens and cytosolic nucleic acid agonists. Altered innate immune gene expression in Lrrk2 knockout (KO) macrophages is driven by a combination of mitochondrial stresses, including oxidative stress from low levels of purine metabolites and DRP1-dependent mitochondrial fragmentation. Together, these defects promote mtDNA leakage into the cytosol and chronic cGAS engagement. While Lrrk2 KO mice can control Mycobacterium tuberculosis (Mtb) replication, they have exacerbated inflammation and lower ISG expression in the lungs. These results demonstrate previously unappreciated consequences of LRRK2-dependent mitochondrial defects in controlling innate immune outcomes. Parkinson’s disease is a progressive nervous system disorder that causes tremors, slow movements, and stiff and inflexible muscles. The symptoms are caused by the loss of cells known as neurons in a specific part of the brain that helps to regulate how the body moves. Researchers have identified mutations in several genes that are associated with an increased risk of developing Parkinson’s. The most common of these mutations occur in a gene called LRRK2. This gene produces a protein that has been shown to be important for maintaining cellular compartments known as mitochondria, which play a crucial role in generating energy. It remains unclear how these mutations lead to the death of neurons. Mutations in LRRK2 have also been shown to make individuals more susceptible to bacterial infections, suggesting that the protein that LRRK2 codes for may help our immune system. Weindel, Bell et al. set out to understand how this protein works in immune cells called macrophages, which ‘eat’ invading bacteria and produce type I interferons, molecules that promote immune responses. Mouse cells were used to measure the ability of normal macrophages and macrophages that lack the mouse equivalent to LRRK2 (referred to as Lrrk2 knockout macrophages) to make type I interferons. The experiments showed that the Lrrk2 knockout macrophages made type I interferons even when they were not infected with bacteria, suggesting they are subject to stress that triggers immune responses. It was possible to correct the behavior of the Lrrk2 knockout macrophages by repairing their mitochondria. When mice missing the gene equivalent to LRRK2 were infected with the bacterium that causes tuberculosis, they experienced more severe disease. The protein encoded by the LRRK2 gene is considered a potential target for therapies to treat Parkinson’s disease, and several drugs that inhibit this protein are being tested in clinical trials. The findings of Weindel, Bell et al. suggest that these drugs may have unintended negative effects on a patient’s ability to fight infection. This work also indicates that LRRK2 mutations may disrupt immune responses in the brain, where macrophage-like cells called microglia play a crucial role in maintaining healthy neurons. Future studies that examine how mutations in LRRK2 affect microglia may help us understand how Parkinson’s disease develops.
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Affiliation(s)
- Chi G Weindel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, United States
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, United States
| | - Krystal J Vail
- Department of Veterinary Pathobiology, Texas A&M University College of Veterinary Medicine and Biomedical Sciences, College Station, United States
| | - Kelsi O West
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, United States
| | - Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, United States
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, United States
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Patrick KL, Bell SL, Weindel CG, Watson RO. Exploring the "Multiple-Hit Hypothesis" of Neurodegenerative Disease: Bacterial Infection Comes Up to Bat. Front Cell Infect Microbiol 2019; 9:138. [PMID: 31192157 PMCID: PMC6546885 DOI: 10.3389/fcimb.2019.00138] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 04/16/2019] [Indexed: 12/23/2022] Open
Abstract
Despite major strides in personalized genomics, it remains poorly understood why neurodegenerative diseases occur in only a fraction of individuals with a genetic predisposition and conversely, why individuals with no genetic risk of a disorder develop one. Chronic diseases like Alzheimer's, Parkinson's, and Multiple sclerosis are speculated to result from a combination of genetic and environmental factors, a concept commonly referred to as the “multiple hit hypothesis.” A number of bacterial infections have been linked to increased risk of neurodegeneration, and in some cases, clearance of bacterial pathogens has been correlated with amelioration of central nervous system (CNS) deficits. Additionally, mutations in several genes known to contribute to CNS disorders like Parkinson's Disease have repeatedly been implicated in susceptibility to intracellular bacterial infection. Recent data has begun to demonstrate roles for these genes (PARK2, PINK1, and LRRK2) in modulating innate immune outcomes, suggesting that immune dysregulation may play an even more important role in neurodegeneration than previously appreciated. This review will broadly explore the connections between bacterial infection, immune dysregulation, and CNS disorders. Understanding this interplay and how bacterial pathogenesis contributes to the “multiple-hit hypothesis” of neurodegeneration will be crucial to develop therapeutics to effectively treat both neurodegeneration and infection.
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Affiliation(s)
- Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX, United States
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX, United States
| | - Chi G Weindel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX, United States
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, TX, United States
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Zhao B, Du F, Xu P, Shu C, Sankaran B, Bell SL, Liu M, Lei Y, Gao X, Fu X, Zhu F, Liu Y, Laganowsky A, Zheng X, Ji JY, West AP, Watson RO, Li P. A conserved PLPLRT/SD motif of STING mediates the recruitment and activation of TBK1. Nature 2019; 569:718-722. [PMID: 31118511 PMCID: PMC6596994 DOI: 10.1038/s41586-019-1228-x] [Citation(s) in RCA: 193] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 04/26/2019] [Indexed: 01/09/2023]
Abstract
Nucleic acids from bacteria or viruses induce potent immune responses in infected cells1-4. The detection of pathogen-derived nucleic acids is a central strategy by which the host senses infection and initiates protective immune responses5,6. Cyclic GMP-AMP synthase (cGAS) is a double-stranded DNA sensor7,8. It catalyses the synthesis of cyclic GMP-AMP (cGAMP)9-12, which stimulates the induction of type I interferons through the STING-TBK1-IRF-3 signalling axis13-15. STING oligomerizes after binding of cGAMP, leading to the recruitment and activation of the TBK1 kinase8,16. The IRF-3 transcription factor is then recruited to the signalling complex and activated by TBK18,17-20. Phosphorylated IRF-3 translocates to the nucleus and initiates the expression of type I interferons21. However, the precise mechanisms that govern activation of STING by cGAMP and subsequent activation of TBK1 by STING remain unclear. Here we show that a conserved PLPLRT/SD motif within the C-terminal tail of STING mediates the recruitment and activation of TBK1. Crystal structures of TBK1 bound to STING reveal that the PLPLRT/SD motif binds to the dimer interface of TBK1. Cell-based studies confirm that the direct interaction between TBK1 and STING is essential for induction of IFNβ after cGAMP stimulation. Moreover, we show that full-length STING oligomerizes after it binds cGAMP, and highlight this as an essential step in the activation of STING-mediated signalling. These findings provide a structural basis for the development of STING agonists and antagonists for the treatment of cancer and autoimmune disorders.
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Affiliation(s)
- Baoyu Zhao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Fenglei Du
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Pengbiao Xu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Chang Shu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Banumathi Sankaran
- Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, USA
| | - Mengmeng Liu
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University Health Science Center, College Station, TX, USA
| | - Yuanjiu Lei
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, USA
| | - Xinsheng Gao
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University Health Science Center, College Station, TX, USA
| | - Xiaofeng Fu
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Fanxiu Zhu
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Yang Liu
- Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Xueyun Zheng
- Department of Chemistry, Texas A&M University, College Station, TX, USA
| | - Jun-Yuan Ji
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University Health Science Center, College Station, TX, USA
| | - A Phillip West
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, USA
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, TX, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA.
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23
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Patrick KL, Wojcechowskyj JA, Bell SL, Riba MN, Jing T, Talmage S, Xu P, Cabello AL, Xu J, Shales M, Jimenez-Morales D, Ficht TA, de Figueiredo P, Samuel JE, Li P, Krogan NJ, Watson RO. Quantitative Yeast Genetic Interaction Profiling of Bacterial Effector Proteins Uncovers a Role for the Human Retromer in Salmonella Infection. Cell Syst 2018; 7:323-338.e6. [PMID: 30077634 DOI: 10.1016/j.cels.2018.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/21/2018] [Accepted: 06/21/2018] [Indexed: 11/26/2022]
Abstract
Intracellular bacterial pathogens secrete a repertoire of effector proteins into host cells that are required to hijack cellular pathways and cause disease. Despite decades of research, the molecular functions of most bacterial effectors remain unclear. To address this gap, we generated quantitative genetic interaction profiles between 36 validated and putative effectors from three evolutionarily divergent human bacterial pathogens and 4,190 yeast deletion strains. Correlating effector-generated profiles with those of yeast mutants, we recapitulated known biology for several effectors with remarkable specificity and predicted previously unknown functions for others. Biochemical and functional validation in human cells revealed a role for an uncharacterized component of the Salmonella SPI-2 translocon, SseC, in regulating maintenance of the Salmonella vacuole through interactions with components of the host retromer complex. These results exhibit the power of genetic interaction profiling to discover and dissect complex biology at the host-pathogen interface.
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Affiliation(s)
- Kristin L Patrick
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Jason A Wojcechowskyj
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA
| | - Samantha L Bell
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Morgan N Riba
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Tao Jing
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Sara Talmage
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Pengbiao Xu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Ana L Cabello
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA; Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Norman Borlaug Center, Texas A&M University, College Station, TX 77843, USA
| | - Jiewei Xu
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA
| | - Michael Shales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA
| | - David Jimenez-Morales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA
| | - Thomas A Ficht
- Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA
| | - Paul de Figueiredo
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA; Department of Veterinary Pathobiology, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA; Norman Borlaug Center, Texas A&M University, College Station, TX 77843, USA
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA; J. David Gladstone Institute, San Francisco, CA 94158, USA.
| | - Robert O Watson
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX 77802, USA.
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West K, Patrick KL, Watson RO. Heterogeneous ribonucleoprotein M influences specific cytokine outcomes upon Salmonella Typhimurium infection. The Journal of Immunology 2018. [DOI: 10.4049/jimmunol.200.supp.50.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
A complex and dynamic regulatory system is needed to fight infection while also preventing induction of inflammatory disease. In macrophages, much is known about how pathogens modulate the innate immune transcriptional response. However, the significance of alternative splicing and manipulation of splicing factors upon infection remains unclear. We have identified several splicing factors that are differentially phosphorylated upon Salmonella Typhimurium bacterial infection, strongly suggesting an important role for RNA processing in the regulation of innate immune responses. A major family of identified phosphorylated splicing factors was the hnRNP (heterogeneous ribonucleoprotein) RNA binding factors, which contribute to multiple aspects of nucleic acid metabolism. Upon LPS stimulation and Salmonella Typhimurium infection, we have found that one of these proteins, hnRNPM, modulates expression of an inflammatory cytokine, IL-6. We have also identified hnRNPM binding sites within the introns of IL-6. We are currently investigating how hnRNPM localizes to chromatin, how hnRNPM intron recognition regulates IL-6 transcript levels, and how the phosphorylation of hnRNPM influences these processes.
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Weindel CG, Bell SL, Vail K, West AP, Patrick KL, Watson RO. LRRK2 is required for macrophage homeostasis and the control of type I IFN. The Journal of Immunology 2018. [DOI: 10.4049/jimmunol.200.supp.169.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
The use of genetic association studies has helped us appreciate that inflammation and immune dysfunction play an integral role in the pathology of multiple chronic disorders including cancer, type II diabetes, and neurodegenerative disease. We became interested in Leucine-rich repeat kinase 2 (LRRK2), a multifunctional kinase associated with Parkinson’s disease (PD), when it was revealed that LRRK2 polymorphisms are also associated with bacterial susceptibility to Mycobacterium leprae, a close relative of Mycobacterium tuberculosis, both of whose pathology relies heavily upon type I interferon (IFN), an innate immune response that activates effector cells. The regulation of type I IFN is critical to prevent a systemic inflammatory state and for the maintenance of healthy neurons. We therefore hypothesized that LRRK2 has a role in regulating innate immunity, contributing to both PD pathogenesis and bacterial infection. We found that in the absence of LRRK2 (Lrrk2−/−), macrophages failed to produce type I IFN in response to multiple cellular insults including, bacterial infection, mitochondrial damage, and DNA/RNA transfection. Interestingly the defect in type I IFN was a result of an imbalance at the level of the mitochondria, which altered macrophage homeostasis. These data suggest that LRRK2 is critical component of the innate immune system through its role maintaining mitochondrial health. The fact that LRRK2-deficient cells cannot induce type I IFN has major implications on both the maintenance of a proper cytokine milieu in the brain and management of the body’s immune response to infection.
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Watson RO, Bell SL, MacDuff DA, Kimmey JM, Diner EJ, Olivas J, Vance RE, Stallings CL, Virgin HW, Cox JS. The Cytosolic Sensor cGAS Detects Mycobacterium tuberculosis DNA to Induce Type I Interferons and Activate Autophagy. Cell Host Microbe 2015; 17:811-819. [PMID: 26048136 DOI: 10.1016/j.chom.2015.05.004] [Citation(s) in RCA: 432] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/04/2015] [Accepted: 04/29/2015] [Indexed: 12/13/2022]
Abstract
Type I interferons (IFNs) are critical mediators of antiviral defense, but their elicitation by bacterial pathogens can be detrimental to hosts. Many intracellular bacterial pathogens, including Mycobacterium tuberculosis, induce type I IFNs following phagosomal membrane perturbations. Cytosolic M. tuberculosis DNA has been implicated as a trigger for IFN production, but the mechanisms remain obscure. We report that the cytosolic DNA sensor, cyclic GMP-AMP synthase (cGAS), is required for activating IFN production via the STING/TBK1/IRF3 pathway during M. tuberculosis and L. pneumophila infection of macrophages, whereas L. monocytogenes short-circuits this pathway by producing the STING agonist, c-di-AMP. Upon sensing cytosolic DNA, cGAS also activates cell-intrinsic antibacterial defenses, promoting autophagic targeting of M. tuberculosis. Importantly, we show that cGAS binds M. tuberculosis DNA during infection, providing direct evidence that this unique host-pathogen interaction occurs in vivo. These data uncover a mechanism by which IFN is likely elicited during active human infections.
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Affiliation(s)
- Robert O Watson
- Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Samantha L Bell
- Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Donna A MacDuff
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
| | - Jacqueline M Kimmey
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
| | - Elie J Diner
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, USA
| | - Joanna Olivas
- Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Russell E Vance
- Department of Molecular & Cell Biology, University of California, Berkeley, California 94720, USA.,Howard Hughes Medical Institute, University of California, Berkeley, California 94720
| | - Christina L Stallings
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
| | - Herbert W Virgin
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
| | - Jeffery S Cox
- Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA
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Watson RO, Manzanillo PS, Cox JS. Extracellular M. tuberculosis DNA targets bacteria for autophagy by activating the host DNA-sensing pathway. Cell 2012; 150:803-15. [PMID: 22901810 DOI: 10.1016/j.cell.2012.06.040] [Citation(s) in RCA: 577] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 05/07/2012] [Accepted: 06/08/2012] [Indexed: 12/14/2022]
Abstract
Eukaryotic cells sterilize the cytosol by using autophagy to route invading bacterial pathogens to the lysosome. During macrophage infection with Mycobacterium tuberculosis, a vacuolar pathogen, exogenous induction of autophagy can limit replication, but the mechanism of autophagy targeting and its role in natural infection remain unclear. Here we show that phagosomal permeabilization mediated by the bacterial ESX-1 secretion system allows cytosolic components of the ubiquitin-mediated autophagy pathway access to phagosomal M. tuberculosis. Recognition of extracelluar bacterial DNA by the STING-dependent cytosolic pathway is required for marking bacteria with ubiquitin, and delivery of bacilli to autophagosomes requires the ubiquitin-autophagy receptors p62 and NDP52 and the DNA-responsive kinase TBK1. Remarkably, mice with monocytes incapable of delivering bacilli to the autophagy pathway are extremely susceptible to infection. Our results reveal an unexpected link between DNA sensing, innate immunity, and autophagy and indicate a major role for this autophagy pathway in resistance to M. tuberculosis infection.
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Affiliation(s)
- Robert O Watson
- Department of Microbiology and Immunology, Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, San Francisco, CA 94158, USA
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Abstract
During continuous intraperitoneal passage of liver and spleen suspension in normal stock mice, a syndrome developed which involved ascites and certain other visceral changes but seldom clinical illness and never fatality. From these mice, a chlamydia was established in yolk sacs of chick embryos and in tissue cultures. This agent readily infects mice when inoculated intranasally but is without effect intracerebrally. It has very low pathogenicity for guinea pigs and is resistant to sodium sulfadiazine. These characteristics, together with results of serum neutralization tests, indicate that the agent is different from the Nigg and DeBurgh strains of mouse pneumonitis.
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Affiliation(s)
- R K Gerloff
- U.S. Department of Health, Education, and Welfare, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratory, Hamilton, Montana 59840
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Abstract
Campylobacter jejuni is one of the major causes of infectious diarrhea world-wide, although relatively little is know about its mechanisms of pathogenicity. This bacterium can gain entry into intestinal epithelial cells, which is thought to be important for its ability to persistently infect and cause disease. We found that C. jejuni is able to survive within intestinal epithelial cells. However, recovery of intracellular bacteria required pre-culturing under oxygen-limiting conditions, suggesting that C. jejuni undergoes significant physiological changes within the intracellular environment. We also found that in epithelial cells the C. jejuni–containing vacuole deviates from the canonical endocytic pathway immediately after a unique caveolae-dependent entry pathway, thus avoiding delivery into lysosomes. In contrast, in macrophages, C. jejuni is delivered to lysosomes and consequently is rapidly killed. Taken together, these studies indicate that C. jejuni has evolved specific adaptations to survive within host cells. Campylobacter jejuni is one of the most common causes of food-borne illness in the United States and a major cause of diarrheal disease throughout the world. After infection through the oral route, this bacterium invades the cells of the intestinal epithelium, a property that is important for its ability to cause disease. Usually, bacteria and other material entering the cell move to compartments called lysosomes, where an acidic mix of enzymes breaks it down. This study shows that C. jejuni can survive within intestinal epithelial cells by avoiding delivery to lysosomes. In contrast, in macrophages, which are specialized cells with the capacity to engulf and kill bacteria, C. jejuni cannot avoid delivery into lysosomes and consequently is rapidly killed. These studies help explain an important virulence attribute of C. jejuni.
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Affiliation(s)
- Robert O Watson
- Section of Microbial Pathogenesis, Yale University, School of Medicine, New Haven, Connecticut, United States of America
| | - Jorge E Galán
- Section of Microbial Pathogenesis, Yale University, School of Medicine, New Haven, Connecticut, United States of America
- * To whom correspondence should be addressed. E-mail:
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Watson RO, Novik V, Hofreuter D, Lara-Tejero M, Galán JE. A MyD88-deficient mouse model reveals a role for Nramp1 in Campylobacter jejuni infection. Infect Immun 2006; 75:1994-2003. [PMID: 17194808 PMCID: PMC1865720 DOI: 10.1128/iai.01216-06] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Campylobacter jejuni is a major worldwide cause of enteric illnesses. Adult immunocompetent mice are not susceptible to C. jejuni infection. However, we show here that mice deficient in the adaptor protein myeloid differentiation factor 88 (MyD88), which is required for signaling through most Toll-like receptors, can be stably colonized by C. jejuni but not by isogenic derivatives carrying mutations in known virulence genes. We also found that Nramp1 deficiency increases the mouse susceptibility to C. jejuni infection when administered systemically. These results indicate that MyD88-deficient mice could be a useful model to study C. jejuni colonization and reveal a potential role for Nramp1 in the control of this bacterial pathogen.
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Affiliation(s)
- Robert O Watson
- Section of Microbial Pathogenesis, Yale University, School of Medicine, New Haven, CT 06536, USA
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Hofreuter D, Tsai J, Watson RO, Novik V, Altman B, Benitez M, Clark C, Perbost C, Jarvie T, Du L, Galán JE. Unique features of a highly pathogenic Campylobacter jejuni strain. Infect Immun 2006; 74:4694-707. [PMID: 16861657 PMCID: PMC1539605 DOI: 10.1128/iai.00210-06] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/04/2006] [Accepted: 05/11/2006] [Indexed: 11/20/2022] Open
Abstract
Campylobacter jejuni, a major human enteric pathogen, exhibits significant strain-to-strain differences which result in differences in pathogenic potential. C. jejuni 81-176 is a highly virulent strain that exhibits unique pathogenic features and is used by many research laboratories. We have determined the nucleotide sequence of its genome and compared it to the genomes of other sequenced C. jejuni strains. We identified a number of unique genetic features which may confer specific metabolic and pathogenic properties on this strain. We have also identified regions of the C. jejuni genome that are hot spots for the integration of horizontally acquired genetic material. This information should help the understanding of the pathogenesis of C. jejuni and, in particular, the unique features of this highly pathogenic strain.
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Affiliation(s)
- Dirk Hofreuter
- Section of Microbial Pathogenesis, School of Medicine, Yale University, New Haven, Connecticut 06536, USA
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Abstract
Campylobacter jejuni is the leading cause of food-borne illness in the USA and one of the most common causes of diarrhoea worldwide. Central to its pathogenicity is its ability to induce the production of proinflammatory cytokines such as interleukin (IL)-8 in intestinal epithelial cells. Here, we demonstrated that C. jejuni infection of intestinal epithelial cells results in the activation of the ERK and p38 mitogen-activated protein kinases and that the ERK kinase pathway is essential for IL-8 production. We found that MAP kinase stimulation leading to IL-8 secretion requires C. jejuni gene products whose production is stimulated upon contact with epithelial cells. We also found that C. jejuni flagellin is a very poor stimulator of Toll-like receptor (TLR)-5 and therefore does not play a significant role in the stimulation of cytokine production.
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Affiliation(s)
- Robert O Watson
- Section of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
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Chaussee MS, Sylva GL, Sturdevant DE, Smoot LM, Graham MR, Watson RO, Musser JM. Rgg influences the expression of multiple regulatory loci to coregulate virulence factor expression in Streptococcus pyogenes. Infect Immun 2002; 70:762-70. [PMID: 11796609 PMCID: PMC127716 DOI: 10.1128/iai.70.2.762-770.2002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human pathogen Streptococcus pyogenes secretes many proteins to the cell wall and extracellular environment that contribute to virulence. Rgg regulates the expression of several exoproteins including a cysteine protease (SPE B), a nuclease (MF-1), a putative nuclease (MF-3), and autolysin. The functional heterogeneity of Rgg-regulated exoproteins and the lack of a conserved regulatory motif in the promoter regions of the genes suggested that Rgg interacts with additional regulatory networks to influence gene expression. DNA microarrays were used to test this hypothesis by comparing genomewide transcript profiles of S. pyogenes NZ131 and isogenic derivative NZ131 rgg during the exponential phase of growth. Transcripts of known and putative virulence-associated genes were more abundant in the rgg mutant, including emm, scpA, orfX, scl1, hasAB, slo, sagA, ska, speH, grab, mac, mf-1, and mf-3. Increased transcription of emm, scpA, and orfX in the rgg mutant was associated with increased production of the corresponding proteins. Differences in the expression of virulence-associated genes were associated with changes in the expression of several regulatory genes, including mga, sagA, csrRS, and fasBCA. The results show that Rgg influences the expression of multiple regulatory networks to coregulate virulence factor expression in S. pyogenes.
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Affiliation(s)
- Michael S Chaussee
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA.
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Abstract
Salmonella has evolved an intimate functional interface with its host. Central to this interface is a battery of bacterial proteins delivered into host cells via a specialized organelle termed the type III secretion system. A subset of these bacterial proteins stimulates cellular responses by activating the Rho family GTPases Cdc42 and Rac. Stimulation of these responses leads to actin cytoskeleton reorganization and the activation of cellular transcription factors that result in bacterial uptake and proinflammatory cytokine production. Remarkably, the cellular responses stimulated by Salmonella are quickly reversed by another bacterial protein, SptP, which exerts its function as a GTPase-activating protein (GAP) for Cdc42 and Rac. In addition to its GAP activity located within its amino-terminus, the carboxy-terminal domain of SptP possesses potent tyrosine phosphatase activity. We show here that the tyrosine phosphatase activity of SptP is involved in reversing the MAP kinase activation that results from Salmonella infection. We also demonstrate an important role for tyrosine kinases, including ACK, in the cellular responses induced by Salmonella. We also found that a potential target for the tyrosine phosphatase activity of SptP is the intermediate filament protein vimentin, which is recruited to the membrane ruffles stimulated by Salmonella.
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Affiliation(s)
- S Murli
- Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale School of Medicine, New Haven, CT 06536, USA
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Abstract
Streptococcus pyogenes secretes many proteins that influence host-pathogen interactions. Despite their importance, relatively little is known about the regulation of these proteins. The rgg gene (also known as ropB) is required for the expression of streptococcal erythrogenic toxin B (SPE B), an extracellular cysteine protease that contributes to virulence. Proteomics was used to determine if rgg regulates the expression of additional exoproteins. Exponential- and stationary-phase culture supernatant proteins made by S. pyogenes NZ131 rgg and NZ131 speB were separated by two-dimensional electrophoresis. Differences were identified in supernatant proteins from both exponential- and stationary-phase cultures, although considerably more differences were detected among stationary-phase supernatant proteins. Forty-two proteins were identified by peptide fingerprinting with matrix-assisted laser desorption mass spectrometry. Mitogenic factor, DNA entry nuclease (open reading frame [ORF 226]), and ORF 953, which has no known function, were more abundant in the culture supernatants of the rgg mutant compared to the speB mutant. ClpB, lysozyme, and autolysin were detected in the culture supernatant of the speB mutant but not the rgg mutant. To determine if Rgg affected protein expression at the transcriptional level, real-time (TaqMan) reverse transcription (RT)-PCR was used to quantitate Rgg-regulated transcripts from NZ131 wild-type and speB and rgg mutant strains. The results obtained with RT-PCR correlated with the proteomic data. We conclude that Rgg regulates the transcription of several genes expressed primarily during the stationary phase of growth.
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Affiliation(s)
- M S Chaussee
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA
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