1
|
Dargham T, Mallick I, Kremer L, Santucci P, Canaan S. Intrabacterial lipid inclusion-associated proteins: a core machinery conserved from saprophyte Actinobacteria to the human pathogen Mycobacterium tuberculosis. FEBS Open Bio 2023; 13:2306-2323. [PMID: 37872001 PMCID: PMC10699116 DOI: 10.1002/2211-5463.13721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/02/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb), the aetiologic agent of tuberculosis (TB), stores triacylglycerol (TAG) in the form of intrabacterial lipid inclusions (ILI) to survive and chronically persist within its host. These highly energetic molecules represent a major source of carbon to support bacterial persistence and reactivation, thus playing a leading role in TB pathogenesis. However, despite its physiological and clinical relevance, ILI metabolism in Mtb remains poorly understood. Recent discoveries have suggested that several ILI-associated proteins might be widely conserved across TAG-producing prokaryotes, but still very little is known regarding the nature and the biological functions of these proteins. Herein, we performed an in silico analysis of three independent ILI-associated proteomes previously reported to computationally define a potential core ILI-associated proteome, referred to as ILIome. Our investigation revealed the presence of 70 orthologous proteins that were strictly conserved, thereby defining a minimal ILIome core. We further narrowed our analysis to proteins involved in lipid metabolism and discuss here their putative biological functions, along with their molecular interactions and dynamics at the surface of these bacterial organelles. We also highlight the experimental limitations of the original proteomic investigations and of the present bioinformatic analysis, while describing new technological approaches and presenting biological perspectives in the field. The in silico investigation presented here aims at providing useful datasets that could constitute a scientific resource of broad interest for the mycobacterial community, with the ultimate goal of enlightening ILI metabolism in prokaryotes with a special emphasis on Mtb pathogenesis.
Collapse
Affiliation(s)
- Tonia Dargham
- Aix‐Marseille Univ, CNRS, LISM UMR 7255, IMM FR3479, IM2BFrance
- IHU Méditerranée InfectionAix‐Marseille Univ.France
| | - Ivy Mallick
- Aix‐Marseille Univ, CNRS, LISM UMR 7255, IMM FR3479, IM2BFrance
| | - Laurent Kremer
- Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM)Université de MontpellierFrance
- INSERM, Institut de Recherche en Infectiologie de MontpellierFrance
| | - Pierre Santucci
- Aix‐Marseille Univ, CNRS, LISM UMR 7255, IMM FR3479, IM2BFrance
| | - Stéphane Canaan
- Aix‐Marseille Univ, CNRS, LISM UMR 7255, IMM FR3479, IM2BFrance
| |
Collapse
|
2
|
Dominguez J, Mendes AI, Pacheco AR, Peixoto MJ, Pedrosa J, Fraga AG. Repurposing of statins for Buruli Ulcer treatment: antimicrobial activity against Mycobacterium ulcerans. Front Microbiol 2023; 14:1266261. [PMID: 37840746 PMCID: PMC10570734 DOI: 10.3389/fmicb.2023.1266261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Mycobacterium ulcerans causes Buruli Ulcer, a neglected infectious skin disease that typically progresses from an early non-ulcerative lesion to an ulcer with undermined edges. If not promptly treated, these lesions can lead to severe disfigurement and disability. The standard antibiotic regimen for Buruli Ulcer treatment has been oral rifampicin combined with intramuscular streptomycin administered daily for 8 weeks. However, there has been a recent shift toward replacing streptomycin with oral clarithromycin. Despite the advantages of this antibiotic regimen, it is limited by low compliance, associated side effects, and refractory efficacy for severe ulcerative lesions. Therefore, new drug candidates with a safer pharmacological spectrum and easier mode of administration are needed. Statins are lipid-lowering drugs broadly used for dyslipidemia treatment but have also been reported to have several pleiotropic effects, including antimicrobial activity against fungi, parasites, and bacteria. In the present study, we tested the susceptibility of M. ulcerans to several statins, namely atorvastatin, simvastatin, lovastatin and fluvastatin. Using broth microdilution assays and cultures of M. ulcerans-infected macrophages, we found that atorvastatin, simvastatin and fluvastatin had antimicrobial activity against M. ulcerans. Furthermore, when using the in vitro checkerboard assay, the combinatory additive effect of atorvastatin and fluvastatin with the standard antibiotics used for Buruli Ulcer treatment highlighted the potential of statins as adjuvant drugs. In conclusion, statins hold promise as potential treatment options for Buruli Ulcer. Further studies are necessary to validate their effectiveness and understand the mechanism of action of statins against M. ulcerans.
Collapse
Affiliation(s)
- Juan Dominguez
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Ana I. Mendes
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Ana R. Pacheco
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Maria J. Peixoto
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Jorge Pedrosa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Alexandra G. Fraga
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| |
Collapse
|
3
|
Kawashima A, Kiriya M, En J, Tanigawa K, Nakamura Y, Fujiwara Y, Luo Y, Maruyama K, Watanabe S, Goto M, Suzuki K. Genome-wide screening identified SEC61A1 as an essential factor for mycolactone-dependent apoptosis in human premonocytic THP-1 cells. PLoS Negl Trop Dis 2022; 16:e0010672. [PMID: 35939511 PMCID: PMC9387930 DOI: 10.1371/journal.pntd.0010672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/18/2022] [Accepted: 07/18/2022] [Indexed: 11/21/2022] Open
Abstract
Buruli ulcer is a chronic skin disease caused by a toxic lipid mycolactone produced by Mycobacterium ulcerans, which induces local skin tissue destruction and analgesia. However, the cytotoxicity pathway induced by mycolactone remains largely unknown. Here we investigated the mycolactone-induced cell death pathway by screening host factors using a genome-scale lenti-CRISPR mutagenesis assay in human premonocytic THP-1 cells. As a result, 884 genes were identified as candidates causing mycolactone-induced cell death, among which SEC61A1, the α-subunit of the Sec61 translocon complex, was the highest scoring. CRISPR/Cas9 genome editing of SEC61A1 in THP-1 cells suppressed mycolactone-induced endoplasmic reticulum stress, especially eIF2α phosphorylation, and caspase-dependent apoptosis. Although previous studies have reported that mycolactone targets SEC61A1 based on mutation screening and structural analysis in several cell lines, we have reconfirmed that SEC61A1 is a mycolactone target by genome-wide screening in THP-1 cells. These results shed light on the cytotoxicity of mycolactone and suggest that the inhibition of mycolactone activity or SEC61A1 downstream cascades will be a novel therapeutic modality to eliminate the harmful effects of mycolactone in addition to the 8-week antibiotic regimen of rifampicin and clarithromycin. Buruli ulcer is a chronic skin disease caused by the bacterium Mycobacterium ulcerans. The disease mainly affects children in West Africa, and the skin ulcers are induced by mycolactone, a toxin produced by the bacteria. The mycolactone diffuses through the skin, killing cells, creating irreversible ulceration, and weakening host immune defenses. However, the cytotoxic pathway induced by mycolactone remains largely unknown. We evaluated the mycolactone-induced cell death pathway by screening host factors using a genome-scale knockout assay in human premonocytic THP-1 cells. We identified 884 genes that are potentially involved in mycolactone-induced cell death, of which SEC61A1, the α-subunit of the Sec61 translocon complex, was the highest ranking. Knockout of SEC61A1 in THP-1 cells resulted in suppression of endoplasmic reticulum stress and caspase-dependent apoptosis induced by mycolactone. These results suggest that SEC61A1 is an essential mediator of mycolactone-induced cell death.
Collapse
Affiliation(s)
- Akira Kawashima
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
| | - Mitsuo Kiriya
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
| | - Junichiro En
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
- Department of Occupational Therapy, School of Health Science, International University of Health and Welfare, Narita, Japan
| | - Kazunari Tanigawa
- Department of Molecular Pharmaceutics, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Yasuhiro Nakamura
- Center for Promotion of Pharmaceutical Education & Research, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Yoko Fujiwara
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
| | - Yuqian Luo
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
- Department of Laboratory Medicine, Nanjing Drum Tower Hospital and Jiangsu Key Laboratory for Molecular Medicine, Nanjing University Medical School, Nanjing, China
| | - Keiji Maruyama
- Center for Promotion of Pharmaceutical Education & Research, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Shigekazu Watanabe
- Center for Promotion of Pharmaceutical Education & Research, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Masamichi Goto
- Department of Pathology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Koichi Suzuki
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
- * E-mail:
| |
Collapse
|
4
|
Strong E, Hart B, Wang J, Orozco MG, Lee S. Induced Synthesis of Mycolactone Restores the Pathogenesis of Mycobacterium ulcerans In Vitro and In Vivo. Front Immunol 2022; 13:750643. [PMID: 35401531 PMCID: PMC8988146 DOI: 10.3389/fimmu.2022.750643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 02/22/2022] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU), the third most common mycobacterial infection. Virulent M. ulcerans secretes mycolactone, a polyketide toxin. Most observations of M. ulcerans infection are described as an extracellular milieu in the form of a necrotic ulcer. While some evidence exists of an intracellular life cycle for M. ulcerans during infection, the exact role that mycolactone plays in this process is poorly understood. Many previous studies have relied upon the addition of purified mycolactone to cell-culture systems to study its role in M. ulcerans pathogenesis and host-response modulation. However, this sterile system drastically simplifies the M. ulcerans infection model and assumes that mycolactone is the only relevant virulence factor expressed by M. ulcerans. Here we show that the addition of purified mycolactone to macrophages during M. ulcerans infection overcomes the bacterial activation of the mechanistic target of rapamycin (mTOR) signaling pathway that plays a substantial role in regulating different cellular processes, including autophagy and apoptosis. To further study the role of mycolactone during M. ulcerans infection, we have developed an inducible mycolactone expression system. Utilizing the mycolactone-deficient Mul::Tn118 strain that contains a transposon insertion in the putative beta-ketoacyl transferase (mup045), we have successfully restored mycolactone production by expressing mup045 in a tetracycline-inducible vector system, which overcomes in-vitro growth defects associated with constitutive complementation. The inducible mycolactone-expressing bacteria resulted in the establishment of infection in a murine footpad model of BU similar to that observed during the infection with wild-type M. ulcerans. This mycolactone inducible system will allow for further analysis of the roles and functions of mycolactone during M. ulcerans infection.
Collapse
Affiliation(s)
- Emily Strong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Bryan Hart
- Human Vaccine Institute, Duke University, Durham, NC, United States
| | - Jia Wang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Maria Gonzalez Orozco
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Sunhee Lee
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Human Vaccine Institute, Duke University, Durham, NC, United States
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC, United States
| |
Collapse
|
5
|
Hall BS, Hsieh LTH, Sacre S, Simmonds RE. The One That Got Away: How Macrophage-Derived IL-1β Escapes the Mycolactone-Dependent Sec61 Blockade in Buruli Ulcer. Front Immunol 2022; 12:788146. [PMID: 35154073 PMCID: PMC8826060 DOI: 10.3389/fimmu.2021.788146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
Buruli ulcer (BU), caused by Mycobacterium ulcerans, is a devastating necrotizing skin disease. Key to its pathogenesis is mycolactone, the exotoxin virulence factor that is both immunosuppressive and cytotoxic. The discovery that the essential Sec61 translocon is the major cellular target of mycolactone explains much of the disease pathology, including the immune blockade. Sec61 inhibition leads to a loss in production of nearly all cytokines from monocytes, macrophages, dendritic cells and T cells, as well as antigen presentation pathway proteins and costimulatory molecules. However, there has long been evidence that the immune system is not completely incapable of responding to M. ulcerans infection. In particular, IL-1β was recently shown to be present in BU lesions, and to be induced from M. ulcerans-exposed macrophages in a mycolactone-dependent manner. This has important implications for our understanding of BU, showing that mycolactone can act as the "second signal" for IL-1β production without inhibiting the pathways of unconventional secretion it uses for cellular release. In this Perspective article, we validate and discuss this recent advance, which is entirely in-line with our understanding of mycolactone's inhibition of the Sec61 translocon. However, we also show that the IL-1 receptor, which uses the conventional secretory pathway, is sensitive to mycolactone blockade at Sec61. Hence, a more complete understanding of the mechanisms regulating IL-1β function in skin tissue, including the transient intra-macrophage stage of M. ulcerans infection, is urgently needed to uncover the double-edged sword of IL-1β in BU pathogenesis, treatment and wound healing.
Collapse
Affiliation(s)
- Belinda S Hall
- Department of Microbial Sciences, School of Bioscience and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Louise Tzung-Harn Hsieh
- Department of Microbial Sciences, School of Bioscience and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Sandra Sacre
- Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
| | - Rachel E Simmonds
- Department of Microbial Sciences, School of Bioscience and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| |
Collapse
|