1
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Gonzales GA, Canton J. Measuring Phagosomal pH by Fluorescence Microscopy. Methods Mol Biol 2023; 2692:153-169. [PMID: 37365467 DOI: 10.1007/978-1-0716-3338-0_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Dual-wavelength and dual-fluorophore ratiometric imaging has become a powerful tool for the study of pH in intracellular compartments. It allows for the dynamic imaging of live cells while accounting for changes in the focal plane, differential loading of the fluorescent probe, and photobleaching caused by repeated image acquisitions. Ratiometric microscopic imaging has the added advantage over whole-population methods of being able to resolve individual cells and even individual organelles. In this chapter, we provide a detailed discussion of the basic principles of ratiometric imaging and its application to the measurement of phagosomal pH, including probe selection, the necessary instrumentation, and calibration methods.
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Affiliation(s)
- Gerone A Gonzales
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Johnathan Canton
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
- Calvin, Joan and Phoebe Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
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2
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Staphylococcus lugdunensis Uses the Agr Regulatory System to Resist Killing by Host Innate Immune Effectors. Infect Immun 2022; 90:e0009922. [PMID: 36069592 PMCID: PMC9584346 DOI: 10.1128/iai.00099-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coagulase-negative staphylococci (CoNS) are frequently commensal bacteria that rarely cause disease in mammals. Staphylococcus lugdunensis is an exceptional CoNS that causes disease in humans similar to virulent Staphylococcus aureus, but the factors that enhance the virulence of this bacterium remain ill defined. Here, we used random transposon insertion mutagenesis to identify the agr quorum sensing system as a regulator of hemolysins in S. lugdunensis. Using RNA sequencing (RNA-seq), we revealed that agr regulates dozens of genes, including hemolytic S. lugdunensis synergistic hemolysins (SLUSH) peptides and the protease lugdulysin. A murine bacteremia model was used to show that mice infected systemically with wild-type S. lugdunensis do not show overt signs of disease despite there being high numbers of bacteria in the livers and kidneys of mice. Moreover, proliferation of the agr mutant in these organs was no different from that of the wild-type strain, leaving the role of the SLUSH peptides and the metalloprotease lugdulysin in pathogenesis still unclear. Nonetheless, the tropism of S. lugdunensis for humans led us to investigate the role of virulence factors in other ways. We show that agr-regulated effectors, but not SLUSH or lugdulysin alone, are important for S. lugdunensis survival in whole human blood. Moreover, we demonstrate that Agr contributes to survival of S. lugdunensis during encounters with murine and primary human macrophages. These findings demonstrate that, in S. lugdunensis, Agr regulates expression of virulence factors and is required for resistance to host innate antimicrobial defenses. This study therefore provides insight into strategies that this Staphylococcus species uses to cause disease.
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3
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A Photoconvertible Reporter System for Bacterial Metabolic Activity Reveals That Staphylococcus aureus Enters a Dormant-Like State to Persist within Macrophages. mBio 2022; 13:e0231622. [DOI: 10.1128/mbio.02316-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The capacity of
Staphylococcus aureus
to survive and persist within phagocytic cells has been associated with antibiotic treatment failure and recurrent infections. Here, we investigated the molecular mechanisms leading to
S. aureus
persistence within macrophages using a reporter system that enables to distinguish between intracellular bacteria with high and low metabolic activity in combinstion with a dual RNA-seq approach.
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4
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Lee S, Zhang Z, Yu Y. Real‐Time Simultaneous Imaging of Acidification and Proteolysis in Single Phagosomes Using Bifunctional Janus‐Particle Probes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Seonik Lee
- Department of Chemistry Indiana University—Bloomington Bloomington IN 47405 USA
| | - Zihan Zhang
- Department of Chemistry Indiana University—Bloomington Bloomington IN 47405 USA
| | - Yan Yu
- Department of Chemistry Indiana University—Bloomington Bloomington IN 47405 USA
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5
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Lee S, Zhang Z, Yu Y. Real-Time Simultaneous Imaging of Acidification and Proteolysis in Single Phagosomes Using Bifunctional Janus-Particle Probes. Angew Chem Int Ed Engl 2021; 60:26734-26739. [PMID: 34624158 PMCID: PMC8648996 DOI: 10.1002/anie.202111094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/24/2021] [Indexed: 12/15/2022]
Abstract
The digestion of pathogens inside phagosomes by immune cells occurs through a sequence of reactions including acidification and proteolysis, but how the reactions are orchestrated in the right order is unclear due to a lack of methods to simultaneously measure more than one reaction in phagosomes. Here we report a bifunctional Janus-particle probe to simultaneously monitor acidification and proteolysis in single phagosomes in live cells. Each probe consists of a pH reporter and a proteolysis reporter that are spatially separated but function concurrently. Using the Janus probes, we found the acidic pH needed to initiate and maintain proteolysis, revealing the mechanism for the sequential occurrence of both reactions during pathogen digestion. We showed how bacterium-derived lipopolysaccharides alter the acidification and proteolysis in phagosomes. This study showcases Janus-particle probes as a generally applicable tool for monitoring multiple reactions in intracellular vesicles.
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Affiliation(s)
- Seonik Lee
- Department of Chemistry, Indiana University-Bloomington, Bloomington, IN, 47405, USA
| | - Zihan Zhang
- Department of Chemistry, Indiana University-Bloomington, Bloomington, IN, 47405, USA
| | - Yan Yu
- Department of Chemistry, Indiana University-Bloomington, Bloomington, IN, 47405, USA
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6
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Stricker HM, Rommerswinkel N, Keil S, Gnoth SA, Niggemann B, Dittmar T. The phospholipase D inhibitor FIPI potently blocks EGF-induced calcium signaling in human breast cancer cells. Cell Commun Signal 2021; 19:43. [PMID: 33832505 PMCID: PMC8034102 DOI: 10.1186/s12964-021-00724-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 02/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phosphotyrosine kinase (PTK)-mediated phospholipase C-γ1 (PLC-γ1) signaling plays a crucial role in the release of the universal second messenger calcium from intracellular stores, which is mandatory for several cellular processes, including cell migration. However, PLC-γ1 could also be activated in a PTK-independent manner by phospholipase D (PLD)-derived phosphatidic acid (PA). Because both higher PLD expression levels and PLD activity have also been associated with breast cancer cell invasion and migration, we wondered whether there might be a link between PLD and PLC-γ1, which was investigated in this study. MATERIALS MDA-MB-468-NEO (EGFR positive) and MDA-MB-468-HER2 (EGFR and HER2 positive) human breast cancer cells were used in this study. The migratory behavior of the cells in the presence of epidermal growth factor (EGF) and the PLD inhibitor 5-fluoro-2-indolyl-des-chlorohalopemide (FIPI) was analyzed using the 3D collagen matrix migration assay. Changes in cytosolic calcium levels in the presence of EGF, FIPI and Sig-1R agonists and antagonists as well as in PLD1 siRNA knockdown cells were determined by flow cytometry. Western blot analyses were performed to determine the basal expression levels and phosphorylation patterns of EGFR, HER2, AKT, MAPKp42/44, PLC-γ1 and Sig-1R. RESULTS The EGF-induced migration of MDA-MB-468-NEO and MDA-MB-468-HER2 cells was significantly impaired by FIPI. Likewise, FIPI also significantly abolished EGF-induced calcium release in both cell lines. However, neither the expression levels nor the phosphorylation patterns of EGFR, HER2, AKT, MAPKp42/44 and PLC-γ1 were markedly changed by FIPI. Knockdown of PLD1 expression by siRNA also significantly impaired EGF-induced calcium release in both cell lines. Targeting Sig-1R, which interacts with IP3R, with the antagonist BD1047 also abrogated EGF-induced calcium release. However, EGF-induced calcium release was also impaired if cells were treated with the Sig-1R agonists PRE084 and PPBP maleate. CONCLUSION In summary, blocking PLD activity with the specific inhibitor FIPI or knocking down PDL1 expression by siRNA significantly impaired EGF-induced calcium release in MDA-MB-468-NEO and MDA-MB-468-HER2 cells, likely indicating a connection between PLD activity and PLC-γ1-mediated calcium signaling. However, how PLD activity interferes with the release of calcium from intracellular stores remains unclear. Video Abstract.
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Affiliation(s)
- Helena M. Stricker
- Institute of Immunology, Center of Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Nadine Rommerswinkel
- Institute of Immunology, Center of Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
- Community Hospital Herdecke, Herdecke, Germany
| | - Silvia Keil
- Institute of Immunology, Center of Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | | | - Bernd Niggemann
- Institute of Immunology, Center of Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Thomas Dittmar
- Institute of Immunology, Center of Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
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7
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Ernest James Phillips T, Maguire E. Phosphoinositides: Roles in the Development of Microglial-Mediated Neuroinflammation and Neurodegeneration. Front Cell Neurosci 2021; 15:652593. [PMID: 33841102 PMCID: PMC8032904 DOI: 10.3389/fncel.2021.652593] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/08/2021] [Indexed: 12/11/2022] Open
Abstract
Microglia are increasingly recognized as vital players in the pathology of a variety of neurodegenerative conditions including Alzheimer’s (AD) and Parkinson’s (PD) disease. While microglia have a protective role in the brain, their dysfunction can lead to neuroinflammation and contributes to disease progression. Also, a growing body of literature highlights the seven phosphoinositides, or PIPs, as key players in the regulation of microglial-mediated neuroinflammation. These small signaling lipids are phosphorylated derivates of phosphatidylinositol, are enriched in the brain, and have well-established roles in both homeostasis and disease.Disrupted PIP levels and signaling has been detected in a variety of dementias. Moreover, many known AD disease modifiers identified via genetic studies are expressed in microglia and are involved in phospholipid metabolism. One of these, the enzyme PLCγ2 that hydrolyzes the PIP species PI(4,5)P2, displays altered expression in AD and PD and is currently being investigated as a potential therapeutic target.Perhaps unsurprisingly, neurodegenerative conditions exhibiting PIP dyshomeostasis also tend to show alterations in aspects of microglial function regulated by these lipids. In particular, phosphoinositides regulate the activities of proteins and enzymes required for endocytosis, toll-like receptor signaling, purinergic signaling, chemotaxis, and migration, all of which are affected in a variety of neurodegenerative conditions. These functions are crucial to allow microglia to adequately survey the brain and respond appropriately to invading pathogens and other abnormalities, including misfolded proteins. AD and PD therapies are being developed to target many of the above pathways, and although not yet investigated, simultaneous PIP manipulation might enhance the beneficial effects observed. Currently, only limited therapeutics are available for dementia, and although these show some benefits for symptom severity and progression, they are far from curative. Given the importance of microglia and PIPs in dementia development, this review summarizes current research and asks whether we can exploit this information to design more targeted, or perhaps combined, dementia therapeutics. More work is needed to fully characterize the pathways discussed in this review, but given the strength of the current literature, insights in this area could be invaluable for the future of neurodegenerative disease research.
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Affiliation(s)
| | - Emily Maguire
- UK Dementia Research Institute at Cardiff University, Cardiff, United Kingdom
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8
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Montaño-Rendón F, Grinstein S, Walpole GFW. Monitoring Phosphoinositide Fluxes and Effectors During Leukocyte Chemotaxis and Phagocytosis. Front Cell Dev Biol 2021; 9:626136. [PMID: 33614656 PMCID: PMC7890364 DOI: 10.3389/fcell.2021.626136] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023] Open
Abstract
The dynamic re-organization of cellular membranes in response to extracellular stimuli is fundamental to the cell physiology of myeloid and lymphoid cells of the immune system. In addition to maintaining cellular homeostatic functions, remodeling of the plasmalemma and endomembranes endow leukocytes with the potential to relay extracellular signals across their biological membranes to promote rolling adhesion and diapedesis, migration into the tissue parenchyma, and to ingest foreign particles and effete cells. Phosphoinositides, signaling lipids that control the interface of biological membranes with the external environment, are pivotal to this wealth of functions. Here, we highlight the complex metabolic transitions that occur to phosphoinositides during several stages of the leukocyte lifecycle, namely diapedesis, migration, and phagocytosis. We describe classical and recently developed tools that have aided our understanding of these complex lipids. Finally, major downstream effectors of inositides are highlighted including the cytoskeleton, emphasizing the importance of these rare lipids in immunity and disease.
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Affiliation(s)
- Fernando Montaño-Rendón
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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9
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Potential role of diacylglycerol kinases in immune-mediated diseases. Clin Sci (Lond) 2021; 134:1637-1658. [PMID: 32608491 DOI: 10.1042/cs20200389] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/08/2020] [Accepted: 06/22/2020] [Indexed: 02/07/2023]
Abstract
The mechanism promoting exacerbated immune responses in allergy and autoimmunity as well as those blunting the immune control of cancer cells are of primary interest in medicine. Diacylglycerol kinases (DGKs) are key modulators of signal transduction, which blunt diacylglycerol (DAG) signals and produce phosphatidic acid (PA). By modulating lipid second messengers, DGK modulate the activity of downstream signaling proteins, vesicle trafficking and membrane shape. The biological role of the DGK α and ζ isoforms in immune cells differentiation and effector function was subjected to in deep investigations. DGK α and ζ resulted in negatively regulating synergistic way basal and receptor induced DAG signals in T cells as well as leukocytes. In this way, they contributed to keep under control the immune response but also downmodulate immune response against tumors. Alteration in DGKα activity is also implicated in the pathogenesis of genetic perturbations of the immune function such as the X-linked lymphoproliferative disease 1 and localized juvenile periodontitis. These findings suggested a participation of DGK to the pathogenetic mechanisms underlying several immune-mediated diseases and prompted several researches aiming to target DGK with pharmacologic and molecular strategies. Those findings are discussed inhere together with experimental applications in tumors as well as in other immune-mediated diseases such as asthma.
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10
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Pidwill GR, Gibson JF, Cole J, Renshaw SA, Foster SJ. The Role of Macrophages in Staphylococcus aureus Infection. Front Immunol 2021; 11:620339. [PMID: 33542723 PMCID: PMC7850989 DOI: 10.3389/fimmu.2020.620339] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/02/2020] [Indexed: 12/23/2022] Open
Abstract
Staphylococcus aureus is a member of the human commensal microflora that exists, apparently benignly, at multiple sites on the host. However, as an opportunist pathogen it can also cause a range of serious diseases. This requires an ability to circumvent the innate immune system to establish an infection. Professional phagocytes, primarily macrophages and neutrophils, are key innate immune cells which interact with S. aureus, acting as gatekeepers to contain and resolve infection. Recent studies have highlighted the important roles of macrophages during S. aureus infections, using a wide array of killing mechanisms. In defense, S. aureus has evolved multiple strategies to survive within, manipulate and escape from macrophages, allowing them to not only subvert but also exploit this key element of our immune system. Macrophage-S. aureus interactions are multifaceted and have direct roles in infection outcome. In depth understanding of these host-pathogen interactions may be useful for future therapeutic developments. This review examines macrophage interactions with S. aureus throughout all stages of infection, with special emphasis on mechanisms that determine infection outcome.
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Affiliation(s)
- Grace R Pidwill
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.,Florey Institute, University of Sheffield, Sheffield, United Kingdom
| | - Josie F Gibson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.,Florey Institute, University of Sheffield, Sheffield, United Kingdom.,The Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Joby Cole
- Florey Institute, University of Sheffield, Sheffield, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Stephen A Renshaw
- Florey Institute, University of Sheffield, Sheffield, United Kingdom.,The Bateson Centre, University of Sheffield, Sheffield, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, Medical School, University of Sheffield, Sheffield, United Kingdom
| | - Simon J Foster
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom.,Florey Institute, University of Sheffield, Sheffield, United Kingdom
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11
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Levin-Konigsberg R, Mantegazza AR. A guide to measuring phagosomal dynamics. FEBS J 2020; 288:1412-1433. [PMID: 32757358 PMCID: PMC7984381 DOI: 10.1111/febs.15506] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/07/2020] [Accepted: 07/31/2020] [Indexed: 02/06/2023]
Abstract
Phagocytosis is an essential mechanism for immunity and homeostasis, performed by a subset of cells known as phagocytes. Upon target engulfment, de novo formation of specialized compartments termed phagosomes takes place. Phagosomes then undergo a series of fusion and fission events as they interact with the endolysosomal system and other organelles, in a dynamic process known as phagosome maturation. Because phagocytes play a key role in tissue patrolling and immune surveillance, phagosome maturation is associated with signaling pathways that link phagocytosis to antigen presentation and the development of adaptive immune responses. In addition, and depending on the nature of the cargo, phagosome integrity may be compromised, triggering additional cellular mechanisms including inflammation and autophagy. Upon completion of maturation, phagosomes enter a recently described phase: phagosome resolution, where catabolites from degraded cargo are metabolized, phagosomes are resorbed, and vesicles of phagosomal origin are recycled. Finally, phagocytes return to homeostasis and become ready for a new round of phagocytosis. Altogether, phagosome maturation and resolution encompass a series of dynamic events and organelle crosstalk that can be measured by biochemical, imaging, photoluminescence, cytometric, and immune‐based assays that will be described in this guide.
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Affiliation(s)
| | - Adriana R Mantegazza
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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12
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The NADPH Oxidase and the Phagosome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1246:153-177. [DOI: 10.1007/978-3-030-40406-2_9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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13
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Ewanchuk BW, Yates RM. The phagosome and redox control of antigen processing. Free Radic Biol Med 2018; 125:53-61. [PMID: 29578071 DOI: 10.1016/j.freeradbiomed.2018.03.040] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/09/2018] [Accepted: 03/20/2018] [Indexed: 11/22/2022]
Abstract
In addition to debris clearance and antimicrobial function, versatile organelles known as phagosomes play an essential role in the processing of exogenous antigen in antigen presenting cells. While there has been much attention on human leukocyte antigen haplotypes in the determination of antigenic peptide repertoires, the lumenal biochemistries within phagosomes and endosomes are emerging as equally-important determinants of peptide epitope composition and immunodominance. Recently, the lumenal redox microenvironment within these degradative compartments has been shown to impact two key antigenic processing chemistries: proteolysis by lysosomal cysteine proteases and disulfide reduction of protein antigens. Through manipulation of the balance between oxidative and reductive capacities in the phagosome-principally by modulating NADPH oxidase (NOX2) and γ-interferon-inducible lysosomal thiol reductase (GILT) activities-studies have demonstrated changes to antigen processing patterns leading to modified repertoires of antigenic peptides available for presentation, and subsequently, altered disease progression in T cell-driven autoimmunity. This review focuses on the mechanisms and consequences of redox-mediated phagosomal antigen processing, and the potential downstream implications to tolerance and autoimmunity.
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Affiliation(s)
- Benjamin W Ewanchuk
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Robin M Yates
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1; Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1.
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14
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Wood PL, Cebak JE, Woltjer RL. Diacylglycerols as biomarkers of sustained immune activation in Proteinopathies associated with dementia. Clin Chim Acta 2018; 476:107-110. [DOI: 10.1016/j.cca.2017.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/10/2017] [Accepted: 11/12/2017] [Indexed: 12/12/2022]
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15
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Wright LM, Carpinone EM, Bennett TL, Hondalus MK, Starai VJ. VapA of Rhodococcus equi binds phosphatidic acid. Mol Microbiol 2017; 107:428-444. [PMID: 29205554 DOI: 10.1111/mmi.13892] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 11/28/2017] [Accepted: 12/03/2017] [Indexed: 12/30/2022]
Abstract
Rhodococcus equi is a multihost, facultative intracellular bacterial pathogen that primarily causes pneumonia in foals less than six months in age and immunocompromised people. Previous studies determined that the major virulence determinant of R. equi is the surface bound virulence associated protein A (VapA). The presence of VapA inhibits the maturation of R. equi-containing phagosomes and promotes intracellular bacterial survival, as determined by the inability of vapA deletion mutants to replicate in host macrophages. While the mechanism of action of VapA remains elusive, we show that soluble recombinant VapA32-189 both rescues the intramacrophage replication defect of a wild type R. equi strain lacking the vapA gene and enhances the persistence of nonpathogenic Escherichia coli in macrophages. During macrophage infection, VapA was observed at both the bacterial surface and at the membrane of the host-derived R. equi containing vacuole, thus providing an opportunity for VapA to interact with host constituents and promote alterations in phagolysosomal function. In support of the observed host membrane binding activity of VapA, we also found that rVapA32-189 interacted specifically with liposomes containing phosphatidic acid in vitro. Collectively, these data demonstrate a lipid binding property of VapA, which may be required for its function during intracellular infection.
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Affiliation(s)
- Lindsay M Wright
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - Emily M Carpinone
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Terry L Bennett
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Mary K Hondalus
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - Vincent J Starai
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.,Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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16
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Redka DS, Gütschow M, Grinstein S, Canton J. Differential ability of proinflammatory and anti-inflammatory macrophages to perform macropinocytosis. Mol Biol Cell 2017; 29:53-65. [PMID: 29093026 PMCID: PMC5746066 DOI: 10.1091/mbc.e17-06-0419] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/16/2017] [Accepted: 10/27/2017] [Indexed: 02/02/2023] Open
Abstract
Macropinocytosis mediates the uptake of antigens and of nutrients that dictate the regulation of cell growth by mechanistic target of rapamycin complex 1 (mTORC1). Because these functions differ in proinflammatory and anti-inflammatory macrophages, we compared the macropinocytic ability of two extreme polarization states. We found that anti-inflammatory macrophages perform vigorous macropinocytosis constitutively, while proinflammatory cells are virtually inactive. The total cellular content of Rho-family GTPases was higher in anti-inflammatory cells, but this disparity failed to account for the differential macropinocytic activity. Instead, reduced activity of Rac/RhoG was responsible for the deficient macropinocytosis of proinflammatory macrophages, as suggested by the stimulatory effects of heterologously expressed guanine nucleotide-exchange factors or of constitutively active (but not wild-type) forms of these GTPases. Similarly, differences in the activation state of phosphatidylinositol 3-kinase (PtdIns3K) correlated with the macropinocytic activity of pro- and anti-inflammatory macrophages. Differences in PtdIns3K and Rho-GTPase activity were attributable to the activity of calcium-sensing receptors (CaSRs), which appear to be functional only in anti-inflammatory cells. However, agonists of PtdIns3K, including cytokines, chemokines, and LPS, induced macropinocytosis in proinflammatory cells. Our findings revealed a striking difference in the macropinocytic ability of pro- and anti-inflammatory macrophages that correlates with their antigen-presenting and metabolic activity.
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Affiliation(s)
- Dar'ya S Redka
- Division of Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Michael Gütschow
- Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, D-53121 Bonn, Germany
| | - Sergio Grinstein
- Division of Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada .,Department of Biochemistry, University of Toronto, ON M5S 1A8, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada
| | - Johnathan Canton
- Division of Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
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17
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Kinkead LC, Fayram DC, Allen LAH. Francisella novicida inhibits spontaneous apoptosis and extends human neutrophil lifespan. J Leukoc Biol 2017; 102:815-828. [PMID: 28550119 DOI: 10.1189/jlb.4ma0117-014r] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 04/27/2017] [Accepted: 05/02/2017] [Indexed: 01/09/2023] Open
Abstract
Francisella novicida is a Gram-negative bacterium that is closely related to the highly virulent facultative intracellular pathogen, Francisella tularensis Data published by us and others demonstrate that F. tularensis virulence correlates directly with its ability to impair constitutive apoptosis and extend human neutrophil lifespan. In contrast, F. novicida is attenuated in humans, and the mechanisms that account for this are incompletely defined. Our published data demonstrate that F. novicida binds natural IgG that is present in normal human serum, which in turn, elicits NADPH oxidase activation that does not occur in response to F. tularensis As it is established that phagocytosis and oxidant production markedly accelerate neutrophil death, we predicted that F. novicida may influence the neutrophil lifespan in an opsonin-dependent manner. To test this hypothesis, we quantified bacterial uptake, phosphatidylserine (PS) externalization, and changes in nuclear morphology, as well as the kinetics of procaspase-3, -8, and -9 processing and activation. To our surprise, we discovered that F. novicida not only failed to accelerate neutrophil death but also diminished and delayed apoptosis in a dose-dependent, but opsonin-independent, manner. In keeping with this, studies of conditioned media (CM) showed that neutrophil longevity could be uncoupled from phagocytosis and that F. novicida stimulated neutrophil secretion of CXCL8. Taken together, the results of this study reveal shared and unique aspects of the mechanisms used by Francisella species to manipulate neutrophil lifespan and as such, advance understanding of cell death regulation during infection.
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Affiliation(s)
- Lauren C Kinkead
- Inflammation Program, University of Iowa, Iowa City, Iowa, USA.,Department of Microbiology, University of Iowa, Iowa City, Iowa, USA.,Iowa City VA Medical Center, Iowa City, Iowa, USA
| | - Drew C Fayram
- Inflammation Program, University of Iowa, Iowa City, Iowa, USA.,Department of Microbiology, University of Iowa, Iowa City, Iowa, USA
| | - Lee-Ann H Allen
- Inflammation Program, University of Iowa, Iowa City, Iowa, USA; .,Department of Microbiology, University of Iowa, Iowa City, Iowa, USA.,Iowa City VA Medical Center, Iowa City, Iowa, USA.,Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA; and
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18
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Hassaninasab A, Han GS, Carman GM. Tips on the analysis of phosphatidic acid by the fluorometric coupled enzyme assay. Anal Biochem 2017; 526:69-70. [PMID: 28359787 DOI: 10.1016/j.ab.2017.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 03/23/2017] [Accepted: 03/25/2017] [Indexed: 02/05/2023]
Abstract
The fluorometric coupled enzyme assay to measure phosphatidic acid (PA) involves the solubilization of extracted lipids in Triton X-100, deacylation, and the oxidation of PA-derived glycerol-3-phosphate to produce hydrogen peroxide for conversion of Amplex Red to resorufin. The enzyme assay is sensitive, but plagued by high background fluorescence from the peroxide-containing detergent and incomplete heat inactivation of lipoprotein lipase. These problems affecting the assay reproducibility were obviated by the use of highly pure Triton X-100 and by sufficient heat inactivation of the lipase enzyme. The enzyme assay could accurately measure the PA content from the subcellular fractions of yeast cells.
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Affiliation(s)
- Azam Hassaninasab
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, United States
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, United States
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ 08901, United States.
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19
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Cheung S, Greene C, Yates RM. Simultaneous Analysis of Multiple Lumenal Parameters of Individual Phagosomes Using High-Content Imaging. Methods Mol Biol 2017; 1519:227-239. [PMID: 27815883 DOI: 10.1007/978-1-4939-6581-6_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The biochemical processes within the phagosomes of macrophages and dendritic cells are essential to immunity and homeostasis. Measurable properties of the phagosomal lumen include: assessment of various hydrolytic activities, reduction and oxidation events, pH, ion concentrations, and electrochemical gradients. These often-interdependent phagosomal features are commonly evaluated individually, hindering the analysis of the biochemical relationship between these factors within the same phagosome. In addition, the ability of phagosomes within the same cell to behave autonomously is becoming more evident, thus highlighting the need for a technique capable of multiplex analyses of phagosomal lumenal chemistries at the single phagosome level. In this chapter, we outline an approach that is capable of simultaneously measuring multiple phagosomal parameters of individual phagosomes by utilizing specifically designed experimental particles with multiple reporter fluors, in combination with real-time fluorometric measurement via automated microscopy. Subsequent analysis using high-content image analysis software enables each phagosomal parameter to be evaluated in a quantitative or semi-quantitative manner. This approach facilitates investigation of the complex relationship between phagosomal properties in a population of macrophages in real time, at the level of individual phagosomes.
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Affiliation(s)
- Samuel Cheung
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - Catherine Greene
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1
| | - Robin M Yates
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1. .,Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1.
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20
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Abstract
Dual wavelength ratiometric imaging has become a powerful tool for the study of pH in intracellular compartments. It allows for the dynamic imaging of live cells while accounting for changes in the focal plane, differential loading of the fluorescent probe, and photobleaching caused by repeated image acquisitions. Ratiometric microscopic imaging has the added advantage over whole population methods of being able to resolve individual cells and even individual organelles. In this chapter we provide a detailed discussion of the basic principles of ratiometric imaging and its application to the measurement of phagosomal pH, including probe selection, the necessary instrumentation, and calibration methods.
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Affiliation(s)
- Johnathan Canton
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, Canada, M5G 0A4
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON, Canada, M5G 0A4. .,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 290 Victoria Street, Toronto, ON, Canada, M5C 1N8.
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21
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Wood PL, Medicherla S, Sheikh N, Terry B, Phillipps A, Kaye JA, Quinn JF, Woltjer RL. Targeted Lipidomics of Fontal Cortex and Plasma Diacylglycerols (DAG) in Mild Cognitive Impairment and Alzheimer's Disease: Validation of DAG Accumulation Early in the Pathophysiology of Alzheimer's Disease. J Alzheimers Dis 2016; 48:537-46. [PMID: 26402017 DOI: 10.3233/jad-150336] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Previous studies have demonstrated augmented levels of diacylglycerols (DAG) in the frontal cortex and plasma of Alzheimer's disease (AD) patients. We extended these findings from non-targeted lipidomics studies to design a lipidomics platform to interrogate DAGs and monoacylglycerols (MAG) in the frontal cortex and plasma of MCI subjects. Control subjects included both aged normal controls and controls with normal cognition, but AD pathology at autopsy, individuals termed non-demented AD neuropathology. DAGs with saturated, unsaturated, and polyunsaturated fatty acid substituents were found to be elevated in MCI frontal cortex and plasma. Tandem mass spectrometry of the DAGs did not reveal any differences in the distributions of the fatty acid substitutions between MCI and control subjects. While triacylglycerols were not altered in MCI subjects there were increases in MAG levels both in the frontal cortex and plasma. In toto, increased levels of DAGs and MAGs appear to occur early in AD pathophysiology and require both further validation in a larger patient cohort and elucidation of the lipidomics alteration(s) that lead to the accumulation of DAGs in MCI subjects.
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Affiliation(s)
- Paul L Wood
- Lipidomics Unit, Department of Physiology and Pharmacology, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, USA
| | - Srikanth Medicherla
- Lipidomics Unit, Department of Physiology and Pharmacology, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, USA
| | - Naveen Sheikh
- Lipidomics Unit, Department of Physiology and Pharmacology, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, USA
| | - Bradley Terry
- Lipidomics Unit, Department of Physiology and Pharmacology, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, USA
| | - Aaron Phillipps
- Lipidomics Unit, Department of Physiology and Pharmacology, DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, USA
| | - Jeffrey A Kaye
- Department of Neurology, Oregon Health Science University and Portland VA Medical Center, Portland, OR, USA
| | - Joseph F Quinn
- Department of Neurology, Oregon Health Science University and Portland VA Medical Center, Portland, OR, USA
| | - Randall L Woltjer
- Department of Neurology, Oregon Health Science University and Portland VA Medical Center, Portland, OR, USA
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22
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Surewaard BGJ, Deniset JF, Zemp FJ, Amrein M, Otto M, Conly J, Omri A, Yates RM, Kubes P. Identification and treatment of the Staphylococcus aureus reservoir in vivo. J Exp Med 2016; 213:1141-51. [PMID: 27325887 PMCID: PMC4925027 DOI: 10.1084/jem.20160334] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 04/29/2016] [Indexed: 02/05/2023] Open
Abstract
Kubes et al. show that methicillin-resistant Staphylococcus aureus (MRSA) survive and proliferate inside Kupffer cells. Intracellular MRSA is resistant to neutrophil-killing and antibiotics treatment and, when released into the circulation, can infect other organs. Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is reaching epidemic proportions causing morbidity, mortality, and chronic disease due to relapses, suggesting an intracellular reservoir. Using spinning-disk confocal intravital microscopy to track MRSA-GFP in vivo, we identified that within minutes after intravenous infection MRSA is primarily sequestered and killed by intravascular Kupffer cells (KCs) in the liver. However, a minority of the Staphylococci overcome the KC’s antimicrobial defenses. These bacteria survive and proliferate for many days within this intracellular niche, where they remain undetected by recruited neutrophils. Over time, the KCs lyse, releasing bacteria into the circulation, enabling dissemination to other organs such as the kidneys. Vancomycin, the antibiotic of choice to treat MRSA bacteremia, could not penetrate the KCs to eradicate intracellular MRSA. However, based on the intravascular location of these specific macrophages, we designed a liposomal formulation of vancomycin that is efficiently taken up by KCs and diminished the intracellular MRSA. Targeting the source of the reservoir dramatically protected the liver but also dissemination to other organs, and prevented mortality. This vancomycin formulation strategy could help treat patients with Staphylococcal bacteremia without a need for novel antibiotics by targeting the previously inaccessible intracellular reservoir in KCs.
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Affiliation(s)
- Bas G J Surewaard
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada Department of Medical Microbiology, University Medical Centre, 3584 CX Utrecht, the Netherlands
| | - Justin F Deniset
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada
| | - Franz J Zemp
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada
| | - Matthias Amrein
- Department of Cell Biology and Anatomy, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - John Conly
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada Department of Pathology and Laboratory Medicine, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada Department of Microbiology, Infectious Diseases and Immunology, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada
| | - Abdelwahab Omri
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury ON P3E 2C6, Ontario, Canada
| | - Robin M Yates
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada
| | - Paul Kubes
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada Department of Physiology and Pharmacology, University of Calgary, Calgary AB T2N 1N4, Alberta, Canada
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23
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Balce DR, Rybicka JM, Greene CJ, Ewanchuk BW, Yates RM. Ligation of FcγR Alters Phagosomal Processing of Protein via Augmentation of NADPH Oxidase Activity. Traffic 2016; 17:786-802. [PMID: 27020146 DOI: 10.1111/tra.12396] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 03/24/2016] [Accepted: 03/24/2016] [Indexed: 01/01/2023]
Abstract
Proteolysis and the reduction of disulfides, both major components of protein degradation, are profoundly influenced by phagosomal redox conditions in macrophages. We evaluated the activation of phagocytic receptors that are known to influence activation of the phagocyte NADPH oxidase (NOX2), and its effect on phagosomal protein degradation. Population-based and single phagosome analyses of phagosomal chemistries in murine macrophages revealed that activation of NOX2 via the Fcγ receptor (FcγR) during phagocytosis decreased rates of proteolysis and disulfide reduction. Immunoglobulin G (IgG)-stimulated reactive oxygen species (ROS) production and the inhibition of phagosomal proteolysis and disulfide reduction were dependent on NOX2, FcγR and protein kinase C (PKC)/spleen tyrosine kinase (Syk) signaling. In contrast, low levels of ROS production were observed following the phagocytosis of unopsonized beads, which resulted in higher rates of phagosomal proteolysis and disulfide reduction. Phagosomes displayed autonomy with respect to FcγR-mediated differences in NOX2 activation and proteolysis, as phagosomes containing unopsonized cargo retained low NOX2 activation and high proteolysis even in the presence of phagosomes containing IgG-opsonized cargo in the same macrophage. These results show that opsonization of phagocytic cargo results in vastly different phagosomal processing of proteins through the FcγR-triggered, PKC/Syk-dependent local assembly and activation of NOX2.
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Affiliation(s)
- Dale R Balce
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, Calgary, Canada
| | - Joanna M Rybicka
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, Calgary, Canada
| | - Catherine J Greene
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Canada
| | - Benjamin W Ewanchuk
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Canada
| | - Robin M Yates
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, Calgary, Canada.,Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Canada
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24
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Luff SA, Papoutsakis ET. Megakaryocytic Maturation in Response to Shear Flow Is Mediated by the Activator Protein 1 (AP-1) Transcription Factor via Mitogen-activated Protein Kinase (MAPK) Mechanotransduction. J Biol Chem 2016; 291:7831-43. [PMID: 26814129 DOI: 10.1074/jbc.m115.707174] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Indexed: 12/26/2022] Open
Abstract
Megakaryocytes (MKs) are exposed to shear flow as they migrate from the bone marrow hematopoietic compartment into circulation to release pro/preplatelets into circulating blood. Shear forces promote DNA synthesis, polyploidization, and maturation in MKs, and platelet biogenesis. To investigate mechanisms underlying these MK responses to shear, we carried out transcriptional analysis on immature and mature stem cell-derived MKs exposed to physiological shear. In immature (day (d)9) MKs, shear exposure up-regulated genes related to growth and MK maturation, whereas in mature (d12) MKs, it up-regulated genes involved in apoptosis and intracellular transport. Following shear-flow exposure, six activator protein 1 (AP-1) transcripts (ATF4,JUNB,JUN,FOSB,FOS, andJUND) were up-regulated at d9 and two AP-1 proteins (JunD and c-Fos) were up-regulated both at d9 and d12. We show that mitogen-activated protein kinase (MAPK) signaling is linked to both the shear stress response and AP-1 up-regulation. c-Jun N-terminal kinase (JNK) phosphorylation increased significantly following shear stimulation, whereas JNK inhibition reduced shear-induced JunD expression. Although p38 phosphorylation did not increase following shear flow, its inhibition reduced shear-induced JunD and c-Fos expression. JNK inhibition reduced fibrinogen binding and P-selectin expression of d12 platelet-like particles (PLPs), whereas p38 inhibition reduced fibrinogen binding of d12 PLPs. AP-1 expression correlated with increased MK DNA synthesis and polyploidization, which might explain the observed impact of shear on MKs. To summarize, we show that MK exposure to shear forces results in JNK activation, AP-1 up-regulation, and downstream transcriptional changes that promote maturation of immature MKs and platelet biogenesis in mature MKs.
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Affiliation(s)
- Stephanie A Luff
- From the Department of Biological Sciences, Delaware Biotechnology Institute, and
| | - Eleftherios T Papoutsakis
- From the Department of Biological Sciences, Delaware Biotechnology Institute, and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19711
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25
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Abstract
Atherosclerosis is responsible for most cardiovascular disease (CVD) and is caused by several factors including hypertension, hypercholesterolemia, and chronic inflammation. Oxidants and electrophiles have roles in the pathophysiology of atherosclerosis and the concentrations of these reactive molecules are an important factor in disease initiation and progression. Overactive NADPH oxidase (Nox) produces excess superoxide resulting in oxidized macromolecules, which is an important factor in atherogenesis. Although superoxide and reactive oxygen species (ROS) have obvious toxic properties, they also have fundamental roles in signaling pathways that enable cells to adapt to stress. In addition to inflammation and ROS, the endocannabinoid system (eCB) is also important in atherogenesis. Linkages have been postulated between the eCB system, Nox, oxidative stress, and atherosclerosis. For instance, CB2 receptor-evoked signaling has been shown to upregulate anti-inflammatory and anti-oxidative pathways, whereas CB1 signaling appears to induce opposite effects. The second messenger lipid molecule diacylglycerol is implicated in the regulation of Nox activity and diacylglycerol lipase β (DAGLβ) is a key biosynthetic enzyme in the biosynthesis eCB ligand 2-arachidonylglycerol (2-AG). Furthermore, Nrf2 is a vital transcription factor that protects against the cytotoxic effects of both oxidant and electrophile stress. This review will highlight the role of reactive oxygen species (ROS) in intracellular signaling and the impact of deregulated ROS-mediated signaling in atherogenesis. In addition, there is also emerging knowledge that the eCB system has an important role in atherogenesis. We will attempt to integrate oxidative stress and the eCB system into a conceptual framework that provides insights into this pathology.
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Affiliation(s)
| | - Matthew K. Ross
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-662-325-5482; Fax: +1-662-325-1031
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26
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Flannagan RS, Heit B, Heinrichs DE. Antimicrobial Mechanisms of Macrophages and the Immune Evasion Strategies of Staphylococcus aureus. Pathogens 2015; 4:826-68. [PMID: 26633519 PMCID: PMC4693167 DOI: 10.3390/pathogens4040826] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 11/17/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022] Open
Abstract
Habitually professional phagocytes, including macrophages, eradicate microbial invaders from the human body without overt signs of infection. Despite this, there exist select bacteria that are professional pathogens, causing significant morbidity and mortality across the globe and Staphylococcus aureus is no exception. S. aureus is a highly successful pathogen that can infect virtually every tissue that comprises the human body causing a broad spectrum of diseases. The profound pathogenic capacity of S. aureus can be attributed, in part, to its ability to elaborate a profusion of bacterial effectors that circumvent host immunity. Macrophages are important professional phagocytes that contribute to both the innate and adaptive immune response, however from in vitro and in vivo studies, it is evident that they fail to eradicate S. aureus. This review provides an overview of the antimicrobial mechanisms employed by macrophages to combat bacteria and describes the immune evasion strategies and some representative effectors that enable S. aureus to evade macrophage-mediated killing.
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Affiliation(s)
- Ronald S Flannagan
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Bryan Heit
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
- Centre for Human Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
| | - David E Heinrichs
- Department of Microbiology and Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
- Centre for Human Immunology, the University of Western Ontario, London, ON N6A 5C1, Canada.
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27
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Xie S, Naslavsky N, Caplan S. Diacylglycerol kinases in membrane trafficking. CELLULAR LOGISTICS 2015; 5:e1078431. [PMID: 27057419 DOI: 10.1080/21592799.2015.1078431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
Diacylglycerol kinases (DGKs) belong to a family of cytosolic kinases that regulate the phosphorylation of diacylglycerol (DAG), converting it into phosphatidic acid (PA). There are 10 known mammalian DGK isoforms, each with a different tissue distribution and substrate specificity. These differences allow regulation of cellular responses by fine-tuning the delicate balance of cellular DAG and PA. DGK isoforms are best characterized as mediators of signal transduction and immune function. However, since recent studies reveal that DAG and PA are also involved in the regulation of endocytic trafficking, it is therefore anticipated that DGKs also plays an important role in membrane trafficking. In this review, we summarize the literature discussing the role of DGK isoforms at different stages of endocytic trafficking, including endocytosis, exocytosis, endocytic recycling, and transport from/to the Golgi apparatus. Overall, these studies contribute to our understanding of the involvement of PA and DAG in endocytic trafficking, an area of research that is drawing increasing attention in recent years.
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Affiliation(s)
- Shuwei Xie
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
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28
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Levin R, Grinstein S, Schlam D. Phosphoinositides in phagocytosis and macropinocytosis. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:805-23. [PMID: 25238964 DOI: 10.1016/j.bbalip.2014.09.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/23/2014] [Accepted: 09/08/2014] [Indexed: 01/08/2023]
Abstract
Professional phagocytes provide immunoprotection and aid in the maintenance of tissue homeostasis. They perform these tasks by recognizing, engulfing and eliminating pathogens and endogenous cell debris. Here, we examine the paramount role played by phosphoinositides in phagocytosis and macropinocytosis, two major endocytic routes that mediate the uptake of particulate and fluid matter, respectively. We analyze accumulating literature describing the molecular mechanisms whereby phosphoinositides translate environmental cues into the complex, sophisticated responses that underlie the phagocytic and macropinocytic responses. In addition, we exemplify virulence strategies involving modulation of host cell phosphoinositide signaling that are employed by bacteria to undermine immunity. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Roni Levin
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada
| | - Sergio Grinstein
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada; Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria St., Toronto M5C1N8, Canada.
| | - Daniel Schlam
- Division of Cell Biology, Hospital for Sick Children, 555 University Ave., Toronto M5G1X8, Canada
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29
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Nauseef WM, Borregaard N. Neutrophils at work. Nat Immunol 2014; 15:602-11. [PMID: 24940954 DOI: 10.1038/ni.2921] [Citation(s) in RCA: 624] [Impact Index Per Article: 62.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 05/13/2014] [Indexed: 12/12/2022]
Abstract
In this Review we discuss data demonstrating recently recognized aspects of neutrophil homeostasis in the steady state, granulopoiesis in 'emergency' conditions and interactions of neutrophils with the adaptive immune system. We explore in vivo observations of the recruitment of neutrophils from blood to tissues in models of blood-borne infections versus bacterial invasion through epithelial linings. We examine data on novel aspects of the activation of NADPH oxidase and the heterogeneity of phagosomes and, finally, consider the importance of two neutrophil-derived biological agents: neutrophil extracellular traps and ectosomes.
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Affiliation(s)
- William M Nauseef
- Inflammation Program, Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, Iowa, USA
| | - Niels Borregaard
- The Granulocyte Research Laboratory, Department of Hematology, National University Hospital, University of Copenhagen, Copenhagen, Denmark
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30
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Abo M, Minakami R, Miyano K, Kamiya M, Nagano T, Urano Y, Sumimoto H. Visualization of phagosomal hydrogen peroxide production by a novel fluorescent probe that is localized via SNAP-tag labeling. Anal Chem 2014; 86:5983-90. [PMID: 24862209 DOI: 10.1021/ac501041w] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hydrogen peroxide (H2O2), a member of reactive oxygen species (ROS), plays diverse physiological roles including host defense and cellular signal transduction. During ingestion of invading microorganisms, professional phagocytes such as macrophages release H2O2 specifically into the phagosome to direct toxic ROS toward engulfed microbes. Although H2O2 is considered to exert discrete effects in living systems depending on location of its production, accumulation, and consumption, there have been limitations of techniques for probing this oxygen metabolite with high molecular specificity at the subcellular resolution. Here we describe the development of an O(6)-benzylguanine derivative of 5-(4-nitrobenzoyl)carbonylfluorescein (NBzF-BG), a novel H2O2-specific fluorescent probe; NBzF-BG is covalently and selectively conjugated with the SNAP-tag protein, leading to formation of the fluorophore-protein conjugate (SNAP-NBzF). SNAP-NBzF rapidly reacts with H2O2 and thereby shows a 9-fold enhancement in fluorescence. When SNAP-tag is expressed in HEK293T cells and RAW264.7 macrophages as a protein C-terminally fused to the transmembrane domain of platelet-derived growth factor receptor (PDGFR), the tag is presented on the outside of the plasma membrane; conjugation of NBzF-BG with the cell surface SNAP-tag enables detection of H2O2 added exogenously. We also demonstrate molecular imaging of H2O2 that is endogenously produced in phagosomes of macrophages ingesting IgG-coated latex beads. Thus, NBzF-BG, combined with the SNAP-tag technology, should be useful as a tool to measure local production of H2O2 in living cells.
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Affiliation(s)
- Masahiro Abo
- Departments of Biochemistry and ‡Health Sciences, Kyushu University Graduate School of Medical Sciences , Fukuoka 812-8582, Japan
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Maekawa M, Fairn GD. Molecular probes to visualize the location, organization and dynamics of lipids. J Cell Sci 2014; 127:4801-12. [DOI: 10.1242/jcs.150524] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cellular lipids play crucial roles in the cell, including in energy storage, the formation of cellular membranes, and in signaling and vesicular trafficking. To understand the functions and characteristics of lipids within cells, various methods to image lipids have been established. In this Commentary, we discuss the four main types of molecular probes that have significantly contributed to our understanding of the cell biology of lipids. In particular, genetically encoded biosensors and antibodies will be discussed, and how they have been used extensively with traditional light and electron microscopy to determine the subcellular localization of lipids and their spatial and temporal regulation. We highlight some of the recent studies that have investigated the distribution of lipids and their ability to cluster using super-resolution and electron microscopy. We also examine methods for analyzing the movement and dynamics of lipids, including single-particle tracking (SPT), fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS). Although the combination of these lipid probes and the various microscopic techniques is very powerful, we also point out several potential caveats and limitations. Finally, we discuss the need for new probes for a variety of phospholipids and cholesterol.
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