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Winer BY, Settle AH, Yakimov AM, Jeronimo C, Lazarov T, Tipping M, Saoi M, Sawh A, Sepp ALL, Galiano M, Perry JSA, Wong YY, Geissmann F, Cross J, Zhou T, Kam LC, Pasolli HA, Hohl T, Cyster JG, Weiner OD, Huse M. Plasma membrane abundance dictates phagocytic capacity and functional cross-talk in myeloid cells. Sci Immunol 2024; 9:eadl2388. [PMID: 38848343 DOI: 10.1126/sciimmunol.adl2388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 05/15/2024] [Indexed: 06/09/2024]
Abstract
Professional phagocytes like neutrophils and macrophages tightly control what they consume, how much they consume, and when they move after cargo uptake. We show that plasma membrane abundance is a key arbiter of these cellular behaviors. Neutrophils and macrophages lacking the G protein subunit Gβ4 exhibited profound plasma membrane expansion, accompanied by marked reduction in plasma membrane tension. These biophysical changes promoted the phagocytosis of bacteria, fungus, apoptotic corpses, and cancer cells. We also found that Gβ4-deficient neutrophils are defective in the normal inhibition of migration following cargo uptake. Sphingolipid synthesis played a central role in these phenotypes by driving plasma membrane accumulation in cells lacking Gβ4. In Gβ4 knockout mice, neutrophils not only exhibited enhanced phagocytosis of inhaled fungal conidia in the lung but also increased trafficking of engulfed pathogens to other organs. Together, these results reveal an unexpected, biophysical control mechanism central to myeloid functional decision-making.
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Affiliation(s)
- Benjamin Y Winer
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Alexander H Settle
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | | | - Carlos Jeronimo
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Tomi Lazarov
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Murray Tipping
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Michelle Saoi
- Donald B. and Catherine C. Marron Cancer Metabolism Center, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | | | - Anna-Liisa L Sepp
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Michael Galiano
- Molecular Cytology Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Justin S A Perry
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Yung Yu Wong
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Frederic Geissmann
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Justin Cross
- Donald B. and Catherine C. Marron Cancer Metabolism Center, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ting Zhou
- Center for Stem Cell Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- SKI Stem Cell Research Facility, Center for Stem Cell Biology and Developmental Biology Program, Sloan Kettering Institute, 1275 York Avenue, New York, NY, USA
| | - Lance C Kam
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - H Amalia Pasolli
- Electron Microscopy Resource Center, Rockefeller University, New York, NY, USA
| | - Tobias Hohl
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jason G Cyster
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Orion D Weiner
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Morgan Huse
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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2
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Muth LT, Van Bogaert INA. Let it stick: Strategies and applications for intracellular plasma membrane targeting of proteins in Saccharomyces cerevisiae. Yeast 2024; 41:315-329. [PMID: 38444057 DOI: 10.1002/yea.3933] [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: 07/06/2023] [Revised: 02/09/2024] [Accepted: 02/12/2024] [Indexed: 03/07/2024] Open
Abstract
Lipid binding domains and protein lipidations are essential features to recruit proteins to intracellular membranes, enabling them to function at specific sites within the cell. Membrane association can also be exploited to answer fundamental and applied research questions, from obtaining insights into the understanding of lipid metabolism to employing them for metabolic engineering to redirect fluxes. This review presents a broad catalog of membrane binding strategies focusing on the plasma membrane of Saccharomyces cerevisiae. Both lipid binding domains (pleckstrin homology, discoidin-type C2, kinase associated-1, basic-rich and bacterial phosphoinositide-binding domains) and co- and post-translational lipidations (prenylation, myristoylation and palmitoylation) are introduced as tools to target the plasma membrane. To provide a toolset of membrane targeting modules, respective candidates that facilitate plasma membrane targeting are showcased including their in vitro and in vivo properties. The relevance and versatility of plasma membrane targeting modules are further highlighted by presenting a selected set of use cases.
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Affiliation(s)
- Liv Teresa Muth
- Department of Biotechnology, Centre for Synthetic Biology, Ghent University, Ghent, Belgium
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Ke H, Bai F, Li Z, Zhu Y, Zhang C, Li Y, Talifu Z, Pan Y, Liu W, Xu X, Gao F, Yang D, Du L, Yu Y, Li J. Inhibition of phospholipase D promotes neurological function recovery and reduces neuroinflammation after spinal cord injury in mice. Front Cell Neurosci 2024; 18:1352630. [PMID: 38572075 PMCID: PMC10987874 DOI: 10.3389/fncel.2024.1352630] [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: 01/08/2024] [Accepted: 02/28/2024] [Indexed: 04/05/2024] Open
Abstract
Introduction Spinal cord injury (SCI) is a severely disabling disease. Hyperactivation of neuroinflammation is one of the main pathophysiological features of secondary SCI, with phospholipid metabolism playing an important role in regulating inflammation. Phospholipase D (PLD), a critical lipid-signaling molecule, is known to be involved in various physiological processes, including the regulation of inflammation. Despite this knowledge, the specific role of PLD in SCI remains unclear. Methods In this study, we constructed mouse models of SCI and administered PLD inhibitor (FIPI) treatment to investigate the efficacy of PLD. Additionally, transcriptome sequencing and protein microarray analysis of spinal cord tissues were conducted to further elucidate its mechanism of action. Results The results showed that PLD expression increased after SCI, and inhibition of PLD significantly improved the locomotor ability, reduced glial scarring, and decreased the damage of spinal cord tissues in mice with SCI. Transcriptome sequencing analysis showed that inhibition of PLD altered gene expression in inflammation regulation. Subsequently, the protein microarray analysis of spinal cord tissues revealed variations in numerous inflammatory factors. Biosignature analysis pointed to an association with immunity, thus confirming the results obtained from transcriptome sequencing. Discussion Collectively, these observations furnish compelling evidence supporting the anti-inflammatory effect of FIPI in the context of SCI, while also offering important insights into the PLD function which may be a potential therapeutic target for SCI.
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Affiliation(s)
- Han Ke
- Shandong University, Jinan, Shandong, China
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
| | - Fan Bai
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Zihan Li
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Yanbing Zhu
- Beijing Clinical Research Institute, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Chunjia Zhang
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Yan Li
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Zuliyaer Talifu
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Yunzhu Pan
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Wubo Liu
- Shandong University, Jinan, Shandong, China
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
| | - Xin Xu
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Feng Gao
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Degang Yang
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Liangjie Du
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Yan Yu
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Jianjun Li
- Shandong University, Jinan, Shandong, China
- China Rehabilitation Research Center, Beijing Bo’ai Hospital, Beijing, China
- University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- Center of Neural Injury and Repair, Beijing Institute for Brain Disorders, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
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Sanchez L, Lensen A, Connor MG, Hamon M, Enninga J, Valenzuela C. Shigella generates distinct IAM subpopulations during epithelial cell invasion to promote efficient intracellular niche formation. Eur J Cell Biol 2024; 103:151381. [PMID: 38183814 DOI: 10.1016/j.ejcb.2023.151381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 12/20/2023] [Accepted: 12/24/2023] [Indexed: 01/08/2024] Open
Abstract
The facultative intracellular pathogen Shigella flexneri invades non-phagocytic epithelial gut cells. Through a syringe-like apparatus called type 3 secretion system, it injects effector proteins into the host cell triggering actin rearrangements leading to its uptake within a tight vacuole, termed the bacterial-containing vacuole (BCV). Simultaneously, Shigella induces the formation of large vesicles around the entry site, which we refer to as infection-associated macropinosomes (IAMs). After entry, Shigella ruptures the BCV and escapes into the host cytosol by disassembling the BCV remnants. Previously, IAM formation has been shown to be required for efficient BCV escape, but the molecular events associated with BCV disassembly have remained unclear. To identify host components required for BCV disassembly, we performed a microscopy-based screen to monitor the recruitment of BAR domain-containing proteins, which are a family of host proteins involved in membrane shaping and sensing (e.g. endocytosis and recycling) during Shigella epithelial cell invasion. We identified endosomal recycling BAR protein Sorting Nexin-8 (SNX8) localized to IAMs in a PI(3)P-dependent manner before BCV disassembly. At least two distinct IAM subpopulations around the BCV were found, either being recycled back to cellular compartments such as the plasma membrane or transitioning to become RAB11A positive "contact-IAMs" involved in promoting BCV rupture. The IAM subpopulation duality was marked by the exclusive recruitment of either SNX8 or RAB11A. Hindering PI(3)P production at the IAMs led to an inhibition of SNX8 recruitment at these compartments and delayed both, the step of BCV rupture time and successful BCV disassembly. Finally, siRNA depletion of SNX8 accelerated BCV rupture and unpeeling of BCV remnants, indicating that SNX8 is involved in controlling the timing of the cytosolic release. Overall, our work sheds light on how Shigella establishes its intracellular niche through the subversion of a specific set of IAMs.
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Affiliation(s)
- Lisa Sanchez
- Institut Pasteur, Université Paris Cité, CNRS UMR3691, Dynamics of Host-Pathogen Interactions Unit, 75015 Paris, France
| | - Arthur Lensen
- Institut Pasteur, Université Paris Cité, CNRS UMR3691, Dynamics of Host-Pathogen Interactions Unit, 75015 Paris, France
| | - Michael G Connor
- Institut Pasteur, Université Paris Cité, Chromatin and Infection Unit, 75015 Paris, France
| | - Mélanie Hamon
- Institut Pasteur, Université Paris Cité, Chromatin and Infection Unit, 75015 Paris, France
| | - Jost Enninga
- Institut Pasteur, Université Paris Cité, CNRS UMR3691, Dynamics of Host-Pathogen Interactions Unit, 75015 Paris, France.
| | - Camila Valenzuela
- Institut Pasteur, Université Paris Cité, CNRS UMR3691, Dynamics of Host-Pathogen Interactions Unit, 75015 Paris, France.
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5
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Weckerly CC, Rahn TA, Ehrlich M, Wills RC, Pemberton JG, Airola MV, Hammond GRV. Nir1-LNS2 is a novel phosphatidic acid biosensor that reveals mechanisms of lipid production. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582557. [PMID: 38464273 PMCID: PMC10925316 DOI: 10.1101/2024.02.28.582557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Despite various roles of phosphatidic acid (PA) in cellular functions such as lipid homeostasis and vesicular trafficking, there is a lack of high-affinity tools to study PA in live cells. After analysis of the predicted structure of the LNS2 domain in the lipid transfer protein Nir1, we suspected that this domain could serve as a novel PA biosensor. We created a fluorescently tagged Nir1-LNS2 construct and then performed liposome binding assays as well as pharmacological and genetic manipulations of HEK293A cells to determine how specific lipids affect the interaction of Nir1-LNS2 with membranes. We found that Nir1-LNS2 bound to both PA and PIP2 in vitro. Interestingly, only PA was necessary and sufficient to localize Nir1-LNS2 to membranes in cells. Nir1-LNS2 also showed a heightened responsiveness to PA when compared to biosensors using the Spo20 PA binding domain (PABD). Nir1-LNS2's high sensitivity revealed a modest but discernible contribution of PLD to PA production downstream of muscarinic receptors, which has not been visualized with previous Spo20-based probes. In summary, Nir1-LNS2 emerges as a versatile and sensitive biosensor, offering researchers a new powerful tool for real-time investigation of PA dynamics in live cells.
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Affiliation(s)
- Claire C Weckerly
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Taylor A Rahn
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
| | - Max Ehrlich
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Rachel C Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Joshua G Pemberton
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD, USA
| | - Michael V Airola
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, USA
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Yao S, Kim SC, Li J, Tang S, Wang X. Phosphatidic acid signaling and function in nuclei. Prog Lipid Res 2024; 93:101267. [PMID: 38154743 PMCID: PMC10843600 DOI: 10.1016/j.plipres.2023.101267] [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: 10/18/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 12/30/2023]
Abstract
Membrane lipidomes are dynamic and their changes generate lipid mediators affecting various biological processes. Phosphatidic acid (PA) has emerged as an important class of lipid mediators involved in a wide range of cellular and physiological responses in plants, animals, and microbes. The regulatory functions of PA have been studied primarily outside the nuclei, but an increasing number of recent studies indicates that some of the PA effects result from its action in nuclei. PA levels in nuclei are dynamic in response to stimuli. Changes in nuclear PA levels can result from activities of enzymes associated with nuclei and/or from movements of PA generated extranuclearly. PA has also been found to interact with proteins involved in nuclear functions, such as transcription factors and proteins undergoing nuclear translocation in response to stimuli. The nuclear action of PA affects various aspects of plant growth, development, and response to stress and environmental changes.
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Affiliation(s)
- Shuaibing Yao
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Sang-Chul Kim
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Jianwu Li
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Shan Tang
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Xuemin Wang
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA.
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7
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Taya T, Teruyama F, Gojo S. Host-directed therapy for bacterial infections -Modulation of the phagolysosome pathway. Front Immunol 2023; 14:1227467. [PMID: 37841276 PMCID: PMC10570837 DOI: 10.3389/fimmu.2023.1227467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Bacterial infections still impose a significant burden on humanity, even though antimicrobial agents have long since been developed. In addition to individual severe infections, the f fatality rate of sepsis remains high, and the threat of antimicrobial-resistant bacteria grows with time, putting us at inferiority. Although tremendous resources have been devoted to the development of antimicrobial agents, we have yet to recover from the lost ground we have been driven into. Looking back at the evolution of treatment for cancer, which, like infectious diseases, has the similarity that host immunity eliminates the lesion, the development of drugs to eliminate the tumor itself has shifted from a single-minded focus on drug development to the establishment of a treatment strategy in which the de-suppression of host immunity is another pillar of treatment. In infectious diseases, on the other hand, the development of therapies that strengthen and support the immune system has only just begun. Among innate immunity, the first line of defense that bacteria encounter after invading the host, the molecular mechanisms of the phagolysosome pathway, which begins with phagocytosis to fusion with lysosome, have been elucidated in detail. Bacteria have a large number of strategies to escape and survive the pathway. Although the full picture is still unfathomable, the molecular mechanisms have been elucidated for some of them, providing sufficient clues for intervention. In this article, we review the host defense mechanisms and bacterial evasion mechanisms and discuss the possibility of host-directed therapy for bacterial infection by intervening in the phagolysosome pathway.
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Affiliation(s)
- Toshihiko Taya
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Fumiya Teruyama
- Pharmacology Research Department, Tokyo New Drug Research Laboratories, Kowa Company, Ltd., Tokyo, Japan
- Department of Regenerative Medicine, Graduate School of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Satoshi Gojo
- Department of Regenerative Medicine, Graduate School of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
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8
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Salloum G, Bresnick AR, Backer JM. Macropinocytosis: mechanisms and regulation. Biochem J 2023; 480:335-362. [PMID: 36920093 DOI: 10.1042/bcj20210584] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/22/2023] [Accepted: 02/27/2023] [Indexed: 03/16/2023]
Abstract
Macropinocytosis is defined as an actin-dependent but coat- and dynamin-independent endocytic uptake process, which generates large intracellular vesicles (macropinosomes) containing a non-selective sampling of extracellular fluid. Macropinocytosis provides an important mechanism of immune surveillance by dendritic cells and macrophages, but also serves as an essential nutrient uptake pathway for unicellular organisms and tumor cells. This review examines the cell biological mechanisms that drive macropinocytosis, as well as the complex signaling pathways - GTPases, lipid and protein kinases and phosphatases, and actin regulatory proteins - that regulate macropinosome formation, internalization, and disposition.
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Affiliation(s)
- Gilbert Salloum
- Department of Molecular Pharamacology, Albert Einstein College of Medicine, Bronx, NY, U.S.A
| | - Anne R Bresnick
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, U.S.A
| | - Jonathan M Backer
- Department of Molecular Pharamacology, Albert Einstein College of Medicine, Bronx, NY, U.S.A
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, U.S.A
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9
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Werner LE, Wagner U. Calcium-sensing receptor-mediated NLRP3 inflammasome activation in rheumatoid arthritis and autoinflammation. Front Physiol 2023; 13:1078569. [PMID: 36685206 PMCID: PMC9854345 DOI: 10.3389/fphys.2022.1078569] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/17/2022] [Indexed: 01/09/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is expressed in many cell types - including immune cells and in particular circulating monocytes. Here, the receptor plays an important physiological role as a regulator of constitutive macropinocytosis. This review article provides an overview of the literature on the role of the calcium sensing receptor in the context of inflammatory processes. Special emphasis is laid upon the importance for monocytes in the context of rheumatoid arthritis. We have shown previously, that stimulation of the receptor by increased extracellular Ca2+ ([Ca2+]ex) triggers a pro-inflammatory response due to NLRP3 inflammasome assembly and interleukin (IL)-1β release. The underlying mechanism includes macropinocytosis of calciprotein particles (CPPs), which are taken up in a [Ca2+]ex-induced, CaSR dependent manner, and leads to strong IL-1β release. In rheumatoid arthritis (RA), this uptake and the resulting IL-1β release is significantly increased due to increased expression of the receptor. Moreover, increased [Ca2+]ex-induced CPP uptake and IL-1β release is associated with more active disease, while CaSR overexpression has been reported to be associated with cardiovascular complications of RA. Most importantly, however, in animal experiments with arthritic mice, increased local calcium concentrations are present, which in combination with release of fetuin-A from eroded bone could contribute to formation of CPPs. We propose, that increased [Ca2+]ex, CPPs and pro-inflammatory cytokines drive a vicious cycle of inflammation and bone destruction which in turn offers new potential therapeutic approaches.
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10
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Odfalk KF, Bieniek KF, Hopp SC. Microglia: Friend and foe in tauopathy. Prog Neurobiol 2022; 216:102306. [PMID: 35714860 PMCID: PMC9378545 DOI: 10.1016/j.pneurobio.2022.102306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 04/24/2022] [Accepted: 06/10/2022] [Indexed: 12/16/2022]
Abstract
Aggregation of misfolded microtubule associated protein tau into abnormal intracellular inclusions defines a class of neurodegenerative diseases known as tauopathies. The consistent spatiotemporal progression of tau pathology in Alzheimer's disease (AD) led to the hypothesis that tau aggregates spread in the brain via bioactive tau "seeds" underlying advancing disease course. Recent studies implicate microglia, the resident immune cells of the central nervous system, in both negative and positive regulation of tau pathology. Polymorphisms in genes that alter microglial function are associated with the development of AD and other tauopathies. Experimental manipulation of microglia function can alter tau pathology and microglia-mediated neuroinflammatory cascades can exacerbate tau pathology. Microglia also exert protective functions by mitigating tau spread: microglia internalize tau seeds and have the capacity to degrade them. However, when microglia fail to degrade these tau seeds there are deleterious consequences, including secretion of exosomes containing tau that can spread to neurons. This review explores the intersection of microglia and tau from the perspective of neuropathology, neuroimaging, genetics, transcriptomics, and molecular biology. As tau-targeted therapies such as anti-tau antibodies advance through clinical trials, it is critical to understand the interaction between tau and microglia.
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Affiliation(s)
- Kristian F Odfalk
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio, San Antonio, TX, USA; Department of Pharmacology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Kevin F Bieniek
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio, San Antonio, TX, USA; Department of Pathology and Laboratory Medicine, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Sarah C Hopp
- Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Science Center San Antonio, San Antonio, TX, USA; Department of Pharmacology, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
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11
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Hammond GRV, Ricci MMC, Weckerly CC, Wills RC. An update on genetically encoded lipid biosensors. Mol Biol Cell 2022; 33:tp2. [PMID: 35420888 PMCID: PMC9282013 DOI: 10.1091/mbc.e21-07-0363] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 01/16/2023] Open
Abstract
Specific lipid species play central roles in cell biology. Their presence or enrichment in individual membranes can control properties or direct protein localization and/or activity. Therefore, probes to detect and observe these lipids in intact cells are essential tools in the cell biologist's freezer box. Herein, we discuss genetically encoded lipid biosensors, which can be expressed as fluorescent protein fusions to track lipids in living cells. We provide a state-of-the-art list of the most widely available and reliable biosensors and highlight new probes (circa 2018-2021). Notably, we focus on advances in biosensors for phosphatidylinositol, phosphatidic acid, and PI 3-kinase lipid products.
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Affiliation(s)
- Gerald R. V. Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Morgan M. C. Ricci
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Claire C. Weckerly
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Rachel C. Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
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12
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Abstract
Macropinocytosis is an evolutionarily conserved endocytic pathway that mediates the nonselective acquisition of extracellular material via large endocytic vesicles known as macropinosomes. In addition to other functions, this uptake pathway supports cancer cell metabolism through the uptake of nutrients. Cells harboring oncogene or tumor suppressor mutations are known to display heightened macropinocytosis, which confers to the cancer cells the ability to survive and proliferate despite the nutrient-scarce conditions of the tumor microenvironment. Thus, macropinocytosis is associated with cancer malignancy. Macropinocytic uptake can be induced in cancer cells by different stress stimuli, acting as an adaptive mechanism for the cells to resist stresses in the tumor milieu. Here, we review the cellular stresses that are known to promote macropinocytosis, as well as the underlying molecular mechanisms that drive this process.
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Affiliation(s)
- Guillem Lambies
- Cell and Molecular Biology of Cancer Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Cosimo Commisso
- Cell and Molecular Biology of Cancer Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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13
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Quintanilla CG, Lee WR, Liou J. Nir1 constitutively localizes at ER-PM junctions and promotes Nir2 recruitment for PIP 2 homeostasis. Mol Biol Cell 2022; 33:br2. [PMID: 35020418 PMCID: PMC9250379 DOI: 10.1091/mbc.e21-07-0356] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Homeostatic regulation of plasma membrane (PM) phosphatidylinositol 4,5-bisphosphate (PIP2) in receptor-stimulated cells is mediated by the lipid transfer protein Nir2. Nir2 is dynamically recruited to endoplasmic reticulum–plasma membrane (ER–PM) junctions to facilitate replenishment of PM PIP2 hydrolyzed during receptor-mediated signaling. However, our knowledge regarding the activation and sustainment of Nir2-mediated replenishment of PM PIP2 is limited. Here, we describe the functions of Nir1 as a positive regulator of Nir2 and PIP2 homeostasis. In contrast to the family proteins Nir2 and Nir3, Nir1 constitutively localizes at ER–PM junctions. Nir1 potentiates Nir2 targeting to ER–PM junctions during receptor-mediated signaling and is required for efficient PM PIP2 replenishment. Live-cell imaging and biochemical analysis reveal that Nir1 interacts with Nir2 via a region between the FFAT motif and the DDHD domain. Combined, results from this study identify Nir1 as an ER–PM junction localized protein that promotes Nir2 recruitment for PIP2 homeostasis.
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Affiliation(s)
| | - Wan-Ru Lee
- Department of Physiology, UT Southwestern Medical Center, TX 75390, USA
| | - Jen Liou
- Department of Physiology, UT Southwestern Medical Center, TX 75390, USA
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14
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Lucas RM, Liu L, Curson JEB, Koh YWH, Tuladhar N, Condon ND, Das Gupta K, Burgener SS, Schroder K, Ingley E, Sweet MJ, Stow JL, Luo L. SCIMP is a spatiotemporal transmembrane scaffold for Erk1/2 to direct pro-inflammatory signaling in TLR-activated macrophages. Cell Rep 2021; 36:109662. [PMID: 34496234 DOI: 10.1016/j.celrep.2021.109662] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/12/2021] [Accepted: 08/13/2021] [Indexed: 02/06/2023] Open
Abstract
Immune cells are armed with Toll-like receptors (TLRs) for sensing and responding to pathogens and other danger cues. The role of extracellular-signal-regulated kinases 1/2 (Erk1/2) in TLR signaling remains enigmatic, with both pro- and anti-inflammatory functions described. We reveal here that the immune-specific transmembrane adaptor SCIMP is a direct scaffold for Erk1/2 in TLR pathways, with high-resolution, live-cell imaging revealing that SCIMP guides the spatial and temporal recruitment of Erk2 to membrane ruffles and macropinosomes for pro-inflammatory TLR4 signaling. SCIMP-deficient mice display defects in Erk1/2 recruitment to TLR4, c-Fos activation, and pro-inflammatory cytokine production, with these effects being phenocopied by Erk1/2 signaling inhibition. Our findings thus delineate a selective role for SCIMP as a key scaffold for the membrane recruitment of Erk1/2 kinase to initiate TLR-mediated pro-inflammatory responses in macrophages.
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Affiliation(s)
- Richard M Lucas
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Liping Liu
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - James E B Curson
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yvette W H Koh
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Neeraj Tuladhar
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kaustav Das Gupta
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sabrina S Burgener
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Evan Ingley
- Cell Signalling Group, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; Discipline of Medical, Molecular and Forensic Sciences, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, WA 6150, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Lin Luo
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia.
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15
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Freeman S, Grinstein S. Promoters and Antagonists of Phagocytosis: A Plastic and Tunable Response. Annu Rev Cell Dev Biol 2021; 37:89-114. [PMID: 34152790 DOI: 10.1146/annurev-cellbio-120219-055903] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent observations indicate that, rather than being an all-or-none response, phagocytosis is finely tuned by a host of developmental and environmental factors. The expression of key phagocytic determinants is regulated via transcriptional and epigenetic means that confer memory on the process. Membrane traffic, the cytoskeleton, and inside-out signaling control the activation of phagocytic receptors and their ability to access their targets. An exquisite extra layer of complexity is introduced by the coexistence of distinct "eat-me" and "don't-eat-me" signals on targets and of corresponding "eat" and "don't-eat" receptors on the phagocyte surface. Moreover, assorted physical barriers constitute "don't-come-close-to-me" hurdles that obstruct the engagement of ligands by receptors. The expression, mobility, and accessibility of all these determinants can be modulated, conferring extreme plasticity on phagocytosis and providing attractive targets for therapeutic intervention in cancer, atherosclerosis, and dementia. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Spencer Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario M5G0A4, Canada; , .,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, Toronto, Ontario M5G0A4, Canada; , .,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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16
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Mylvaganam S, Freeman SA, Grinstein S. The cytoskeleton in phagocytosis and macropinocytosis. Curr Biol 2021; 31:R619-R632. [PMID: 34033794 DOI: 10.1016/j.cub.2021.01.036] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cells of the innate immune system, notably macrophages, neutrophils and dendritic cells, perform essential antimicrobial and homeostatic functions. These functions rely on the dynamic surveillance of the environment supported by the formation of elaborate membrane protrusions. Such protrusions - pseudopodia, lamellipodia and filopodia - facilitate the sampling of the surrounding fluid by macropinocytosis, as well as the engulfment of particulates by phagocytosis. Both processes entail extreme plasma membrane deformations that require the coordinated rearrangement of cytoskeletal polymers, which exert protrusive force and drive membrane coalescence and scission. The resulting vacuolar compartments undergo pronounced remodeling and ultimate resolution by mechanisms that also involve the cytoskeleton. Here, we describe the regulation and functions of cytoskeletal assembly and remodeling during macropinocytosis and phagocytosis.
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Affiliation(s)
- Sivakami Mylvaganam
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
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17
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Maxson ME, Sarantis H, Volchuk A, Brumell JH, Grinstein S. Rab5 regulates macropinocytosis by recruiting the inositol 5-phosphatases OCRL and Inpp5b that hydrolyse PtdIns(4,5)P2. J Cell Sci 2021; 134:237783. [PMID: 33722976 DOI: 10.1242/jcs.252411] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 02/25/2021] [Indexed: 01/09/2023] Open
Abstract
Rab5 is required for macropinosome formation, but its site and mode of action remain unknown. We report that Rab5 acts at the plasma membrane, downstream of ruffling, to promote macropinosome sealing and scission. Dominant-negative Rab5, which obliterates macropinocytosis, had no effect on the development of membrane ruffles. However, Rab5-containing vesicles were recruited to circular membrane ruffles, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-dependent endomembrane fusion was necessary for the completion of macropinocytosis. This fusion event coincided with the disappearance of PtdIns(4,5)P2 that accompanies macropinosome closure. Counteracting the depletion of PtdIns(4,5)P2 by expression of phosphatidylinositol-4-phosphate 5-kinase impaired macropinosome formation. Importantly, we found that the removal of PtdIns(4,5)P2 is dependent on Rab5, through the Rab5-mediated recruitment of the inositol 5-phosphatases OCRL and Inpp5b, via APPL1. Knockdown of OCRL and Inpp5b, or APPL1, prevented macropinosome closure without affecting ruffling. We therefore propose that Rab5 is essential for the clearance of PtdIns(4,5)P2 needed to complete the scission of macropinosomes or to prevent their back-fusion with the plasmalemma.
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Affiliation(s)
- Michelle E Maxson
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Helen Sarantis
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Allen Volchuk
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - John H Brumell
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,SickKids IBD Centre, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A1, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A1, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario M5B 1W8, Canada
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18
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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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19
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Kovalenko A, Sanin A, Kosmas K, Zhang L, Wang J, Akl EW, Giannikou K, Probst CK, Hougard TR, Rue RW, Krymskaya VP, Asara JM, Lam HC, Kwiatkowski DJ, Henske EP, Filippakis H. Therapeutic Targeting of DGKA-Mediated Macropinocytosis Leads to Phospholipid Reprogramming in Tuberous Sclerosis Complex. Cancer Res 2021; 81:2086-2100. [PMID: 33593821 DOI: 10.1158/0008-5472.can-20-2218] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/16/2020] [Accepted: 02/10/2021] [Indexed: 11/16/2022]
Abstract
Lymphangioleiomyomatosis is a rare destructive lung disease affecting primarily women and is the primary lung manifestation of tuberous sclerosis complex (TSC). In lymphangioleiomyomatosis, biallelic loss of TSC1/2 leads to hyperactivation of mTORC1 and inhibition of autophagy. To determine how the metabolic vulnerabilities of TSC2-deficient cells can be targeted, we performed a high-throughput screen utilizing the "Repurposing" library at the Broad Institute of MIT and Harvard (Cambridge, MA), with or without the autophagy inhibitor chloroquine. Ritanserin, an inhibitor of diacylglycerol kinase alpha (DGKA), was identified as a selective inhibitor of proliferation of Tsc2-/- mouse embryonic fibroblasts (MEF), with no impact on Tsc2+/+ MEFs. DGKA is a lipid kinase that metabolizes diacylglycerol to phosphatidic acid, a key component of plasma membranes. Phosphatidic acid levels were increased 5-fold in Tsc2-/- MEFs compared with Tsc2+/+ MEFs, and treatment of Tsc2-/- MEFs with ritanserin led to depletion of phosphatidic acid as well as rewiring of phospholipid metabolism. Macropinocytosis is known to be upregulated in TSC2-deficient cells. Ritanserin decreased macropinocytic uptake of albumin, limited the number of lysosomes, and reduced lysosomal activity in Tsc2-/- MEFs. In a mouse model of TSC, ritanserin treatment decreased cyst frequency and volume, and in a mouse model of lymphangioleiomyomatosis, genetic downregulation of DGKA prevented alveolar destruction and airspace enlargement. Collectively, these data indicate that DGKA supports macropinocytosis in TSC2-deficient cells to maintain phospholipid homeostasis and promote proliferation. Targeting macropinocytosis with ritanserin may represent a novel therapeutic approach for the treatment of TSC and lymphangioleiomyomatosis. SIGNIFICANCE: This study identifies macropinocytosis and phospholipid metabolism as novel mechanisms of metabolic homeostasis in mTORC1-hyperactive cells and suggest ritanserin as a novel therapeutic strategy for use in mTORC1-hyperactive tumors, including pancreatic cancer. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/8/2086/F1.large.jpg.
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Affiliation(s)
- Andrii Kovalenko
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Andres Sanin
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Kosmas Kosmas
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Long Zhang
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ji Wang
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Elie W Akl
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Krinio Giannikou
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Clemens K Probst
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Thomas R Hougard
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ryan W Rue
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Lung Biology Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Vera P Krymskaya
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Lung Biology Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - John M Asara
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Hilaire C Lam
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - David J Kwiatkowski
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Elizabeth P Henske
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
| | - Harilaos Filippakis
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
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20
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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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21
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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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22
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Abstract
Lipids, like phosphoinositides, can be visualized in living cells in real time using genetically encoded biosensors and fluorescence microscopy. Sensor localization can be quantified by determining the fluorescence intensity of each fluorophore. Enrichment of lipids at membranes can be determined by generating and applying an organelle-specific binary mask. In this chapter, we provide a detailed list of reagents and methods to visualize and quantify relative lipid levels. Applying this approach, changes in lipid levels can be assessed in cases when lipid metabolizing enzymes are mutated or otherwise altered.
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Affiliation(s)
- Rachel C Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jonathan Pacheco
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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23
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Phosphatidic acid increases Notch signalling by affecting Sanpodo trafficking during Drosophila sensory organ development. Sci Rep 2020; 10:21731. [PMID: 33303974 PMCID: PMC7729928 DOI: 10.1038/s41598-020-78831-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 11/27/2020] [Indexed: 11/08/2022] Open
Abstract
Organ cell diversity depends on binary cell-fate decisions mediated by the Notch signalling pathway during development and tissue homeostasis. A clear example is the series of binary cell-fate decisions that take place during asymmetric cell divisions that give rise to the sensory organs of Drosophila melanogaster. The regulated trafficking of Sanpodo, a transmembrane protein that potentiates receptor activity, plays a pivotal role in this process. Membrane lipids can regulate many signalling pathways by affecting receptor and ligand trafficking. It remains unknown, however, whether phosphatidic acid regulates Notch-mediated binary cell-fate decisions during asymmetric cell divisions, and what are the cellular mechanisms involved. Here we show that increased phosphatidic acid derived from Phospholipase D leads to defects in binary cell-fate decisions that are compatible with ectopic Notch activation in precursor cells, where it is normally inactive. Null mutants of numb or the α-subunit of Adaptor Protein complex-2 enhance dominantly this phenotype while removing a copy of Notch or sanpodo suppresses it. In vivo analyses show that Sanpodo localization decreases at acidic compartments, associated with increased internalization of Notch. We propose that Phospholipase D-derived phosphatidic acid promotes ectopic Notch signalling by increasing receptor endocytosis and inhibiting Sanpodo trafficking towards acidic endosomes.
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Tei R, Baskin JM. Spatiotemporal control of phosphatidic acid signaling with optogenetic, engineered phospholipase Ds. J Cell Biol 2020; 219:133675. [PMID: 31999306 PMCID: PMC7054994 DOI: 10.1083/jcb.201907013] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 11/09/2019] [Accepted: 12/17/2019] [Indexed: 12/21/2022] Open
Abstract
Phosphatidic acid (PA) is both a central phospholipid biosynthetic intermediate and a multifunctional lipid second messenger produced at several discrete subcellular locations. Organelle-specific PA pools are believed to play distinct physiological roles, but tools with high spatiotemporal control are lacking for unraveling these pleiotropic functions. Here, we present an approach to precisely generate PA on demand on specific organelle membranes. We exploited a microbial phospholipase D (PLD), which produces PA by phosphatidylcholine hydrolysis, and the CRY2–CIBN light-mediated heterodimerization system to create an optogenetic PLD (optoPLD). Directed evolution of PLD using yeast membrane display and IMPACT, a chemoenzymatic method for visualizing cellular PLD activity, yielded a panel of optoPLDs whose range of catalytic activities enables mimicry of endogenous, physiological PLD signaling. Finally, we applied optoPLD to elucidate that plasma membrane, but not intracellular, pools of PA can attenuate the oncogenic Hippo signaling pathway. OptoPLD represents a powerful and precise approach for revealing spatiotemporally defined physiological functions of PA.
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Affiliation(s)
- Reika Tei
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY
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25
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Interface of Phospholipase Activity, Immune Cell Function, and Atherosclerosis. Biomolecules 2020; 10:biom10101449. [PMID: 33076403 PMCID: PMC7602611 DOI: 10.3390/biom10101449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 09/30/2020] [Accepted: 10/13/2020] [Indexed: 12/16/2022] Open
Abstract
Phospholipases are a family of lipid-altering enzymes that can either reduce or increase bioactive lipid levels. Bioactive lipids elicit signaling responses, activate transcription factors, promote G-coupled-protein activity, and modulate membrane fluidity, which mediates cellular function. Phospholipases and the bioactive lipids they produce are important regulators of immune cell activity, dictating both pro-inflammatory and pro-resolving activity. During atherosclerosis, pro-inflammatory and pro-resolving activities govern atherosclerosis progression and regression, respectively. This review will look at the interface of phospholipase activity, immune cell function, and atherosclerosis.
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Armistead J, Hatzold J, van Roye A, Fahle E, Hammerschmidt M. Entosis and apical cell extrusion constitute a tumor-suppressive mechanism downstream of Matriptase. J Cell Biol 2020; 219:132730. [PMID: 31819976 PMCID: PMC7041680 DOI: 10.1083/jcb.201905190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 10/02/2019] [Accepted: 11/04/2019] [Indexed: 12/21/2022] Open
Abstract
Armistead et al. show that in a bilayered epithelium in vivo, apical cell extrusion of basal cells is achieved via their engulfment by surface cells. In zebrafish hai1a mutants, this constitutes a tumor-suppressive mechanism, revealing a double face of Matriptase. The type II transmembrane serine protease Matriptase 1 (ST14) is commonly known as an oncogene, yet it also plays an understudied role in suppressing carcinogenesis. This double face is evident in the embryonic epidermis of zebrafish loss-of-function mutants in the cognate Matriptase inhibitor Hai1a (Spint1a). Mutant embryos display epidermal hyperplasia, but also apical cell extrusions, during which extruding outer keratinocytes carry out an entosis-like engulfment and entrainment of underlying basal cells, constituting a tumor-suppressive effect. These counteracting Matriptase effects depend on EGFR and the newly identified mediator phospholipase D (PLD), which promotes both mTORC1-dependent cell proliferation and sphingosine-1-phosphate (S1P)–dependent entosis and apical cell extrusion. Accordingly, hypomorphic hai1a mutants heal spontaneously, while otherwise lethal hai1a amorphs are efficiently rescued upon cotreatment with PLD inhibitors and S1P. Together, our data elucidate the mechanisms underlying the double face of Matriptase function in vivo and reveal the potential use of combinatorial carcinoma treatments when such double-face mechanisms are involved.
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Affiliation(s)
- Joy Armistead
- Institute of Zoology, Developmental Biology Unit, University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Julia Hatzold
- Institute of Zoology, Developmental Biology Unit, University of Cologne, Cologne, Germany
| | - Anna van Roye
- Institute of Zoology, Developmental Biology Unit, University of Cologne, Cologne, Germany
| | - Evelin Fahle
- Institute of Zoology, Developmental Biology Unit, University of Cologne, Cologne, Germany
| | - Matthias Hammerschmidt
- Institute of Zoology, Developmental Biology Unit, University of Cologne, Cologne, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
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27
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Flannagan RS, Heinrichs DE. Macrophage-driven nutrient delivery to phagosomal Staphylococcus aureus supports bacterial growth. EMBO Rep 2020; 21:e50348. [PMID: 32452129 PMCID: PMC7403714 DOI: 10.15252/embr.202050348] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/28/2020] [Accepted: 05/05/2020] [Indexed: 11/09/2022] Open
Abstract
Staphylococcus aureus is a notorious pathogen causing significant morbidity and mortality worldwide. The ability of S. aureus to survive and replicate within phagocytes such as macrophages represents an important facet of immune evasion and contributes to pathogenesis. The mechanisms by which S. aureus acquires nutrients within host cells to support growth remain poorly characterized. Here, we demonstrate that macrophages infected with S. aureus maintain their dynamic ruffling behavior and consume macromolecules from the extracellular milieu. To support the notion that fluid-phase uptake by macrophages can provide S. aureus with nutrients, we utilized the pharmacological inhibitors PIK-III and Dynasore to impair uptake of extracellular macromolecules. Inhibitor treatment also impaired S. aureus replication within macrophages. Finally, using a mutant of S. aureus that is defective in purine biosynthesis we show that intracellular growth is inhibited unless the macrophage culture medium is supplemented with the metabolite inosine monophosphate. This growth rescue can be impaired by inhibition of fluid-phase uptake. In summary, through consumption of the extracellular environment macrophages deliver nutrients to phagolysosomal S. aureus to promote bacterial growth.
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Affiliation(s)
- Ronald S Flannagan
- Department of Microbiology and ImmunologyThe University of Western OntarioLondonONCanada
| | - David E Heinrichs
- Department of Microbiology and ImmunologyThe University of Western OntarioLondonONCanada
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28
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Lin XP, Mintern JD, Gleeson PA. Macropinocytosis in Different Cell Types: Similarities and Differences. MEMBRANES 2020; 10:membranes10080177. [PMID: 32756454 PMCID: PMC7463864 DOI: 10.3390/membranes10080177] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 12/14/2022]
Abstract
Macropinocytosis is a unique pathway of endocytosis characterised by the nonspecific internalisation of large amounts of extracellular fluid, solutes and membrane in large endocytic vesicles known as macropinosomes. Macropinocytosis is important in a range of physiological processes, including antigen presentation, nutrient sensing, recycling of plasma proteins, migration and signalling. It has become apparent in recent years from the study of specialised cells that there are multiple pathways of macropinocytosis utilised by different cell types, and some of these pathways are triggered by different stimuli. Understanding the physiological function of macropinocytosis requires knowledge of the regulation and fate of the macropinocytosis pathways in a range of cell types. Here, we compare the mechanisms of macropinocytosis in different primary and immortalised cells, identify the gaps in knowledge in the field and discuss the potential approaches to analyse the function of macropinocytosis in vivo.
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29
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Lee J, Salsman J, Foster J, Dellaire G, Ridgway ND. Lipid-associated PML structures assemble nuclear lipid droplets containing CCTα and Lipin1. Life Sci Alliance 2020; 3:3/8/e202000751. [PMID: 32461215 PMCID: PMC7266991 DOI: 10.26508/lsa.202000751] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 11/24/2022] Open
Abstract
PML proteins assemble into noncanonical lipid-associated PML structures (LAPS) on nuclear lipid droplets, which recruit CCTα and Lipin1 for the synthesis of phosphatidylcholine and triacylglycerol. Nuclear lipid droplets (nLDs) form on the inner nuclear membrane by a mechanism involving promyelocytic leukemia (PML), the protein scaffold of PML nuclear bodies. We report that PML structures on nLDs in oleate-treated U2OS cells, referred to as lipid-associated PML structures (LAPS), differ from canonical PML nuclear bodies by the relative absence of SUMO1, SP100, and DAXX. These nLDs were also enriched in CTP:phosphocholine cytidylyltransferase α (CCTα), the phosphatidic acid phosphatase Lipin1, and DAG. Translocation of CCTα onto nLDs was mediated by its α-helical M-domain but was not correlated with its activator DAG. High-resolution imaging revealed that CCTα and LAPS occupied distinct polarized regions on nLDs. PML knockout U2OS (PML KO) cells lacking LAPS had a 40–50% reduction in nLDs with associated CCTα, and residual nLDs were almost devoid of Lipin1 and DAG. As a result, phosphatidylcholine and triacylglycerol synthesis was inhibited in PML KO cells. We conclude that in response to excess exogenous fatty acids, LAPS are required to assemble nLDs that are competent to recruit CCTα and Lipin1.
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Affiliation(s)
- Jonghwa Lee
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
| | - Jayme Salsman
- Department of Pathology, Dalhousie University, Halifax, Canada
| | - Jason Foster
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
| | - Graham Dellaire
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada .,Department of Pathology, Dalhousie University, Halifax, Canada
| | - Neale D Ridgway
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada .,Department of Pediatrics, Dalhousie University, Halifax, Canada
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30
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Walpole GFW, Grinstein S. Endocytosis and the internalization of pathogenic organisms: focus on phosphoinositides. F1000Res 2020; 9. [PMID: 32494357 PMCID: PMC7233180 DOI: 10.12688/f1000research.22393.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/07/2020] [Indexed: 12/18/2022] Open
Abstract
Despite their comparatively low abundance in biological membranes, phosphoinositides are key to the regulation of a diverse array of signaling pathways and direct membrane traffic. The role of phosphoinositides in the initiation and progression of endocytic pathways has been studied in considerable depth. Recent advances have revealed that distinct phosphoinositide species feature prominently in clathrin-dependent and -independent endocytosis as well as in phagocytosis and macropinocytosis. Moreover, a variety of intracellular and cell-associated pathogens have developed strategies to commandeer host cell phosphoinositide metabolism to gain entry and/or metabolic advantage, thereby promoting their survival and proliferation. Here, we briefly survey the current knowledge on the involvement of phosphoinositides in endocytosis, phagocytosis, and macropinocytosis and highlight several examples of molecular mimicry employed by pathogens to either “hitch a ride” on endocytic pathways endogenous to the host or create an entry path of their own.
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Affiliation(s)
- Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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31
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Yao Y, Wang X, Li H, Fan J, Qian X, Li H, Xu Y. Phospholipase D as a key modulator of cancer progression. Biol Rev Camb Philos Soc 2020; 95:911-935. [PMID: 32073216 DOI: 10.1111/brv.12592] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 02/01/2020] [Accepted: 02/06/2020] [Indexed: 12/15/2022]
Abstract
The phospholipase D (PLD) family has a ubiquitous expression in cells. PLD isoforms (PLDs) and their hydrolysate phosphatidic acid (PA) have been demonstrated to engage in multiple stages of cancer progression. Aberrant expression of PLDs, especially PLD1 and PLD2, has been detected in various cancers. Inhibition or elimination of PLDs activity has been shown to reduce tumour growth and metastasis. PLDs and PA also serve as downstream effectors of various cell-surface receptors, to trigger and regulate propagation of intracellular signals in the process of tumourigenesis and metastasis. Here, we discuss recent advances in understanding the functions of PLDs and PA in discrete stages of cancer progression, including cancer cell growth, invasion and migration, and angiogenesis, with special emphasis on the tumour-associated signalling pathways mediated by PLDs and PA and the functional importance of PLDs and PA in cancer therapy.
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Affiliation(s)
- Yuanfa Yao
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xinyi Wang
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Clinical Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Hanbing Li
- Institute of Pharmacology, College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Jiannan Fan
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Xiaohan Qian
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Respiratory Disease, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hong Li
- Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingke Xu
- Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education, Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Endocrinology, The Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
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32
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Abstract
Macropinosome formation occurs as a localized sequence of biochemical activities and associated morphological changes, which may be considered a form of signal transduction leading to the construction of an organelle. Macropinocytosis may also convey information about the availability of extracellular nutrients to intracellular regulators of metabolism. Consistent with this idea, activation of the metabolic regulator mechanistic target of rapamycin complex-1 (mTORC1) in response to acute stimulation by growth factors and extracellular amino acids requires internalization of amino acids by macropinocytosis. This suggests that macropinocytosis is necessary for mTORC1-dependent growth of metazoan cells, both as a route for delivery of amino acids to sensors associated with lysosomes and as a platform for growth factor-dependent signalling to mTORC1 via phosphatidylinositol 3-kinase (PI3K) and the Akt pathway. Because the biochemical signals required for the construction of macropinosomes are also required for cell growth, and inhibition of macropinocytosis inhibits growth factor signalling to mTORC1, we propose that signalling by growth factor receptors is organized into stochastic, structure-dependent cascades of chemical reactions that both build a macropinosome and stimulate mTORC1. More generally, as discrete units of signal transduction, macropinosomes may be subject to feedback regulation by metabolism and cell dimensions. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
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Affiliation(s)
- Joel A Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School , Ann Arbor, MI 48109-5620 , USA
| | - Sei Yoshida
- Department of Microbiology and Immunology, University of Michigan Medical School , Ann Arbor, MI 48109-5620 , USA
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33
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Doodnauth SA, Grinstein S, Maxson ME. Constitutive and stimulated macropinocytosis in macrophages: roles in immunity and in the pathogenesis of atherosclerosis. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180147. [PMID: 30967001 DOI: 10.1098/rstb.2018.0147] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Macrophages respond to several stimuli by forming florid membrane ruffles that lead to fluid uptake by macropinocytosis. This type of induced macropinocytosis, executed by a variety of non-malignant and malignant cells, is initiated by transmembrane receptors and is involved in nutrient acquisition and mTOR signalling. However, macrophages also perform a unique type of constitutive ruffling and macropinocytosis that is dependent on the presence of extracellular calcium. Calcium-sensing receptors are responsible for this activity. This distinct form of macropinocytosis enables macrophages to continuously sample their microenvironment for antigenic molecules and for pathogen- and danger-associated molecular patterns, as part of their immune surveillance functions. Interestingly, even within the monocyte lineage, there are differences in macropinocytic ability that reflect the polarized functional roles of distinct macrophage subsets. This review discusses the shared and distinct features of both induced and constitutive macropinocytosis displayed by the macrophage lineage and their roles in physiology, immunity and pathophysiology. In particular, we analyse the role of macropinocytosis in the uptake of modified low-density lipoprotein (LDL) and its contribution to foam cell and atherosclerotic plaque formation. We propose a combined role of scavenger receptors and constitutive macropinocytosis in oxidized LDL uptake, a process we have termed 'receptor-assisted macropinocytosis'. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
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Affiliation(s)
- Sasha A Doodnauth
- 1 Princess Margaret Cancer Center, University Health Network , Toronto, ON , Canada M5G 1L7.,2 Department of Medical Biophysics, University of Toronto , Toronto, ON , Canada M5G 1L7
| | - Sergio Grinstein
- 3 Program in Cell Biology, Hospital for Sick Children , 686 Bay Street, Toronto, ON , Canada M5G 0A4.,4 Department of Biochemistry, University of Toronto , 1 King's Circle, Toronto, ON , Canada M5S 1A8.,5 Keenan Research Centre of the Li Ka Shing Knowledge Institute , St. Michael's Hospital, 290 Victoria Street, Toronto, ON , Canada M5C 1N8
| | - Michelle E Maxson
- 3 Program in Cell Biology, Hospital for Sick Children , 686 Bay Street, Toronto, ON , Canada M5G 0A4
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Thakur R, Naik A, Panda A, Raghu P. Regulation of Membrane Turnover by Phosphatidic Acid: Cellular Functions and Disease Implications. Front Cell Dev Biol 2019; 7:83. [PMID: 31231646 PMCID: PMC6559011 DOI: 10.3389/fcell.2019.00083] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 05/03/2019] [Indexed: 01/23/2023] Open
Abstract
Phosphatidic acid (PA) is a simple glycerophospholipid with a well-established role as an intermediate in phospholipid biosynthesis. In addition to its role in lipid biosynthesis, PA has been proposed to act as a signaling molecule that modulates several aspects of cell biology including membrane transport. PA can be generated in eukaryotic cells by several enzymes whose activity is regulated in the context of signal transduction and enzymes that can metabolize PA thus terminating its signaling activity have also been described. Further, several studies have identified PA binding proteins and changes in their activity are proposed to be mediators of the signaling activity of this lipid. Together these enzymes and proteins constitute a PA signaling toolkit that mediates the signaling functions of PA in cells. Recently, a number of novel genetic models for the analysis of PA function in vivo and analytical methods to quantify PA levels in cells have been developed and promise to enhance our understanding of PA functions. Studies of several elements of the PA signaling toolkit in a single cell type have been performed and are presented to provide a perspective on our understanding of the biochemical and functional organization of pools of PA in a eukaryotic cell. Finally, we also provide a perspective on the potential role of PA in human disease, synthesizing studies from model organisms, human disease genetics and analysis using recently developed PLD inhibitors.
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Affiliation(s)
- Rajan Thakur
- National Centre for Biological Sciences-TIFR, Bengaluru, India
| | - Amruta Naik
- National Centre for Biological Sciences-TIFR, Bengaluru, India
| | - Aniruddha Panda
- National Centre for Biological Sciences-TIFR, Bengaluru, India
| | - Padinjat Raghu
- National Centre for Biological Sciences-TIFR, Bengaluru, India
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35
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Tanguy E, Tran Nguyen AP, Kassas N, Bader MF, Grant NJ, Vitale N. Regulation of Phospholipase D by Arf6 during FcγR-Mediated Phagocytosis. THE JOURNAL OF IMMUNOLOGY 2019; 202:2971-2981. [DOI: 10.4049/jimmunol.1801019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 03/11/2019] [Indexed: 12/20/2022]
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36
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Abstract
Lipids convey both structural and functional properties to eukaryotic membranes. Understanding the basic lipid composition and the dynamics of these important molecules, in the context of cellular membranes, can shed light on signaling, metabolism, trafficking, and even membrane identity. The development of genetically encoded lipid biosensors has allowed for the visualization of specific lipids inside individual, living cells. However, a number of caveats and considerations have emerged with the overexpression of these biosensors. In this Technical Perspective, we provide a current list of available genetically encoded lipid biosensors, together with criteria that determine their veracity. We also provide some suggestions for the optimal utilization of these biosensors when both designing experiments and interpreting results.
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Affiliation(s)
- Rachel C Wills
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 16261
| | - Brady D Goulden
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 16261
| | - Gerald R V Hammond
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 16261
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37
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Portet A, Pinaud S, Chaparro C, Galinier R, Dheilly NM, Portela J, Charriere GM, Allienne JF, Duval D, Gourbal B. Sympatric versus allopatric evolutionary contexts shape differential immune response in Biomphalaria / Schistosoma interaction. PLoS Pathog 2019; 15:e1007647. [PMID: 30893368 PMCID: PMC6443186 DOI: 10.1371/journal.ppat.1007647] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 04/01/2019] [Accepted: 02/19/2019] [Indexed: 12/22/2022] Open
Abstract
Selective pressures between hosts and their parasites can result in reciprocal evolution or adaptation of specific life history traits. Local adaptation of resident hosts and parasites should lead to increase parasite infectivity/virulence (higher compatibility) when infecting hosts from the same location (in sympatry) than from a foreign location (in allopatry). Analysis of geographic variations in compatibility phenotypes is the most common proxy used to infer local adaptation. However, in some cases, allopatric host-parasite systems demonstrate similar or greater compatibility than in sympatry. In such cases, the potential for local adaptation remains unclear. Here, we study the interaction between Schistosoma and its vector snail Biomphalaria in which such discrepancy in local versus foreign compatibility phenotype has been reported. Herein, we aim at bridging this gap of knowledge by comparing life history traits (immune cellular response, host mortality, and parasite growth) and molecular responses in highly compatible sympatric and allopatric Schistosoma/Biomphalaria interactions originating from different geographic localities (Brazil, Venezuela and Burundi). We found that despite displaying similar prevalence phenotypes, sympatric schistosomes triggered a rapid immune suppression (dual-RNAseq analyses) in the snails within 24h post infection, whereas infection by allopatric schistosomes (regardless of the species) was associated with immune cell proliferation and triggered a non-specific generalized immune response after 96h. We observed that, sympatric schistosomes grow more rapidly. Finally, we identify miRNAs differentially expressed by Schistosoma mansoni that target host immune genes and could be responsible for hijacking the host immune response during the sympatric interaction. We show that despite having similar prevalence phenotypes, sympatric and allopatric snail-Schistosoma interactions displayed strong differences in their immunobiological molecular dialogue. Understanding the mechanisms allowing parasites to adapt rapidly and efficiently to new hosts is critical to control disease emergence and risks of Schistosomiasis outbreaks. Schistosomiasis, the second most widespread human parasitic disease after malaria, is caused by helminth parasites of the genus Schistosoma. More than 200 million people in 74 countries suffer from the pathological, and societal consequences of this disease. To complete its life cycle, the parasite requires an intermediate host, a freshwater snail of the genus Biomphalaria for its transmission. Given the limited options for treating Schistosoma mansoni infections in humans, much research has focused on developing methods to control transmission by its intermediate snail host. Biomphalaria glabrata. Comparative studies have shown that infection of the snail triggers complex cellular and humoral immune responses resulting in significant variations in parasite infectivity and snail susceptibility, known as the so-called polymorphism of compatibility. However, studies have mostly focused on characterizing the immunobiological mechanisms in sympatric interactions. Herein we used a combination of molecular and phenotypic approaches to compare the effect of infection in various sympatric and allopatric evolutionary contexts, allowing us to better understand the mechanisms of host-parasite local adaptation. Learning more about the immunobiological interactions between B. glabrata and S. mansoni could have important socioeconomic and public health impacts by changing the way we attempt to eradicate parasitic diseases and prevent or control schistosomiasis in the field.
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Affiliation(s)
- Anaïs Portet
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Silvain Pinaud
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Cristian Chaparro
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Richard Galinier
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Nolwenn M. Dheilly
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, United States of America
| | - Julien Portela
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Guillaume M. Charriere
- Interactions Hôtes-Pathogènes-Environnements (IHPE), UMR 5244, CNRS, Ifremer, Université de Perpignan Via Domitia, Université de Montpellier, Montpellier, France
| | - Jean-François Allienne
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - David Duval
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
| | - Benjamin Gourbal
- Univ. Perpignan Via Domitia, Interactions Hôtes Pathogènes Environnements UMR 5244, CNRS, IFREMER, Univ. Montpellier, Perpignan, France
- * E-mail:
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Plasma lipidomic profiling in murine mutants of Hermansky-Pudlak syndrome reveals differential changes in pro- and anti-atherosclerotic lipids. Biosci Rep 2019; 39:BSR20182339. [PMID: 30710063 PMCID: PMC6379572 DOI: 10.1042/bsr20182339] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/22/2019] [Accepted: 01/29/2019] [Indexed: 11/17/2022] Open
Abstract
Atherosclerosis is characterized by the accumulation of lipid-rich plaques in the arterial wall. Its pathogenesis is very complicated and has not yet been fully elucidated. It is known that dyslipidemia is a major factor in atherosclerosis. Several different Hermansky-Pudlak syndrome (HPS) mutant mice have been shown either anti-atherosclerotic or atherogenic phenotypes, which may be mainly attributed to corresponding lipid perturbation. To explore the effects of different HPS proteins on lipid metabolism and plasma lipid composition, we analyzed the plasma lipid profiles of three HPS mutant mice, pa (Hps9 -/-), ru (Hps6 -/-), ep (Hps1 -/-), and wild-type (WT) mice. In pa and ru mice, some pro-atherosclerotic lipids, e.g. ceramide (Cer) and diacylglycerol (DAG), were down-regulated whereas triacylglycerol (TAG) containing docosahexaenoic acid (DHA) (22:6) fatty acyl was up-regulated when compared with WT mice. Several pro-atherosclerotic lipids including phosphatidic acid (PA), lysophosphatidylserine (LPS), sphingomyelin (SM), and cholesterol (Cho) were up-regulated in ep mice compared with WT mice. The lipid droplets in hepatocytes showed corresponding changes in these mutants. Our data suggest that the pa mutant resembles the ru mutant in its anti-atherosclerotic effects, but the ep mutant has an atherogenic effect. Our findings may provide clues to explain why different HPS mutant mice exhibit distinct anti-atherosclerotic or atherogenic effects after being exposed to high-cholesterol diets.
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Halder RC, Tran C, Prasad P, Wang J, Nallapothula D, Ishikawa T, Wang M, Zajonc DM, Singh RR. Self-glycerophospholipids activate murine phospholipid-reactive T cells and inhibit iNKT cell activation by competing with ligands for CD1d loading. Eur J Immunol 2018; 49:242-254. [PMID: 30508304 DOI: 10.1002/eji.201847717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/15/2018] [Accepted: 11/27/2018] [Indexed: 01/12/2023]
Abstract
Glycosphingolipids and glycerophospholipids bind CD1d. Glycosphingolipid-reactive invariant NKT-cells (iNKT) exhibit myriad immune effects, however, little is known about the functions of phospholipid-reactive T cells (PLT). We report that the normal mouse immune repertoire contains αβ T cells, which recognize self-glycerophospholipids such as phosphatidic acid (PA) in a CD1d-restricted manner and don't cross-react with iNKT-cell ligands. PA bound to CD1d in the absence of lipid transfer proteins. Upon in vivo priming, PA induced an expansion and activation of T cells in Ag-specific manner. Crystal structure of the CD1d:PA complex revealed that the ligand is centrally located in the CD1d-binding groove opening for TCR recognition. Moreover, the increased flexibility of the two acyl chains in diacylglycerol ligands and a less stringent-binding orientation for glycerophospholipids as compared with the bindings of glycosphingolipids may allow glycerophospholipids to readily occupy CD1d. Indeed, PA competed with α-galactosylceramide to load onto CD1d, leading to reduced expression of CD1d:α-galactosylceramide complexes on the surface of dendritic cells. Consistently, glycerophospholipids reduced iNKT-cell proliferation, expansion, and cytokine production in vitro and in vivo. Such superior ability of self-glycerophospholipids to compete with iNKT-cell ligands to occupy CD1d may help maintain homeostasis between the diverse subsets of lipid-reactive T cells, with important pathogenetic and therapeutic implications.
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Affiliation(s)
- Ramesh Chandra Halder
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Cynthia Tran
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Priti Prasad
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA.,Molecular Toxicology Interdepartmental Program, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Jing Wang
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Dhiraj Nallapothula
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Tatsuya Ishikawa
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Meiying Wang
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Dirk M Zajonc
- Division of Immune Regulation, La Jolla Institute for Immunology, La Jolla, CA, USA.,Department of Internal Medicine, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Ram Raj Singh
- Autoimmunity and Tolerance Laboratory, Division of Rheumatology, Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA.,Molecular Toxicology Interdepartmental Program, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA.,Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA.,Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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40
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Flannagan RS, Heinrichs DE. A Fluorescence Based-Proliferation Assay for the Identification of Replicating Bacteria Within Host Cells. Front Microbiol 2018; 9:3084. [PMID: 30619165 PMCID: PMC6299164 DOI: 10.3389/fmicb.2018.03084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 11/29/2018] [Indexed: 01/01/2023] Open
Abstract
Understanding host pathogen interactions is paramount to the development of novel antimicrobials. An important facet of this pursuit is the accurate characterization of pathogen replication within infected host cells. Here we describe the use of a fluorescence-based proliferation assay to identify intracellular populations of replicating bacteria at the subcellular level. Using Staphylococcus aureus as a model Gram-positive bacterial pathogen and macrophages as a model host phagocyte, we demonstrate this assay can be used to reliably identify individual phagocytes that contain replicating bacteria. Furthermore, we demonstrate this assay is compatible with additional cellular probes that enable characterization of cellular compartments in which replicating bacteria reside. Finally, we demonstrate that this assay facilitates the investigation of both Gram-negative and Gram-positive bacteria within host cells.
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Affiliation(s)
- Ronald S Flannagan
- Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada
| | - David E Heinrichs
- Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada
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41
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Canton J. Macropinocytosis: New Insights Into Its Underappreciated Role in Innate Immune Cell Surveillance. Front Immunol 2018; 9:2286. [PMID: 30333835 PMCID: PMC6176211 DOI: 10.3389/fimmu.2018.02286] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 09/14/2018] [Indexed: 12/25/2022] Open
Abstract
Macropinocytosis has received increasing attention in recent years for its various roles in nutrient acquisition, immune surveillance, and virus and cancer pathologies. In most cases macropinocytosis is initiated by the sudden increase in an external stimulus such as a growth factor. This "induced" form of macropinocytosis has been the subject of much of the work addressing its mechanism and function over the years. An alternative, "constitutive" form of macropinocytosis restricted to primary innate immune cells also exists, although its mechanism has remained severely understudied. This mini-review focuses on the very recent advances that have shed new light on the initiation, formation and functional relevance of constitutive macropinocytosis in primary innate immune cells. An emphasis is placed on how this new understanding of constitutive macropinocytosis is helping to define the sentinel function of innate immune cells including polarized macrophages and dendritic cells.
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Affiliation(s)
- Johnathan Canton
- Immunobiology Laboratory, The Francis Crick Institute, London, United Kingdom
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42
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Rac1 Nanoscale Organization on the Plasma Membrane Is Driven by Lipid Binding Specificity Encoded in the Membrane Anchor. Mol Cell Biol 2018; 38:MCB.00186-18. [PMID: 29967243 DOI: 10.1128/mcb.00186-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/21/2018] [Indexed: 12/21/2022] Open
Abstract
Rac1 is a small guanine nucleotide binding protein that cycles between an inactive GDP-bound and active GTP-bound state to regulate cell motility and migration. Rac1 signaling is initiated from the plasma membrane (PM). Here, we used high-resolution spatial mapping and manipulation of PM lipid composition to define Rac1 nanoscale organization. We found that Rac1 proteins in the GTP- and GDP-bound states assemble into nonoverlapping nanoclusters; thus, Rac1 proteins undergo nucleotide-dependent segregation. Rac1 also selectively interacts with phosphatidic acid (PA) and phosphoinositol (3,4,5)-trisphosphate (PIP3), resulting in nanoclusters enriched in these lipids. These lipids are structurally important because depleting the PM of PA or PIP3 impairs both Rac1 PM binding and Rac1 nanoclustering. Lipid binding specificity of Rac1 is encoded in the amino acid sequence of the polybasic domain (PBD) of the C-terminal membrane anchor. Point mutations within the PBD, including arginine-to-lysine substitutions, profoundly alter Rac1 lipid binding specificity without changing the electrostatics of the protein and result in impaired macropinocytosis and decreased cell spreading. We propose that Rac1 nanoclusters act as lipid-based signaling platforms emulating the spatiotemporal organization of Ras proteins and show that the Rac1 PBD-prenyl anchor has a biological function that extends beyond simple electrostatic engagement with the PM.
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43
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Condon ND, Heddleston JM, Chew TL, Luo L, McPherson PS, Ioannou MS, Hodgson L, Stow JL, Wall AA. Macropinosome formation by tent pole ruffling in macrophages. J Cell Biol 2018; 217:3873-3885. [PMID: 30150290 PMCID: PMC6219714 DOI: 10.1083/jcb.201804137] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/01/2018] [Accepted: 08/13/2018] [Indexed: 12/26/2022] Open
Abstract
Condon et al. use lattice light-sheet microscopy to analyze live macrophages and
define a new model of macropinosome formation and closure through tent pole
ruffles. The ruffles, which are enhanced by LPS and regulated by Rab13, are
erected and supported by F-actin tent poles that cross over and twist to
constrict the forming macropinosomes. Pathogen-mediated activation of macrophages arms innate immune responses that
include enhanced surface ruffling and macropinocytosis for environmental
sampling and receptor internalization and signaling. Activation of macrophages
with bacterial lipopolysaccharide (LPS) generates prominent dorsal ruffles,
which are precursors for macropinosomes. Very rapid, high-resolution imaging of
live macrophages with lattice light sheet microscopy (LLSM) reveals new features
and actions of dorsal ruffles, which redefine the process of macropinosome
formation and closure. We offer a new model in which ruffles are erected and
supported by F-actin tent poles that cross over and twist to constrict the
forming macropinosomes. This process allows for formation of large
macropinosomes induced by LPS. We further describe the enrichment of active
Rab13 on tent pole ruffles and show that CRISPR deletion of Rab13 results in
aberrant tent pole ruffles and blocks the formation of large LPS-induced
macropinosomes. Based on the exquisite temporal and spatial resolution of LLSM,
we can redefine the ruffling and macropinosome processes that underpin innate
immune responses.
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Affiliation(s)
- Nicholas D Condon
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia
| | - John M Heddleston
- Advanced Imaging Center, Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA
| | - Teng-Leong Chew
- Advanced Imaging Center, Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA
| | - Lin Luo
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Maria S Ioannou
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Louis Hodgson
- Department of Anatomy and Structural Biology, Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY
| | - Jennifer L Stow
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia
| | - Adam A Wall
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia
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Platre MP, Noack LC, Doumane M, Bayle V, Simon MLA, Maneta-Peyret L, Fouillen L, Stanislas T, Armengot L, Pejchar P, Caillaud MC, Potocký M, Čopič A, Moreau P, Jaillais Y. A Combinatorial Lipid Code Shapes the Electrostatic Landscape of Plant Endomembranes. Dev Cell 2018; 45:465-480.e11. [PMID: 29754803 DOI: 10.1016/j.devcel.2018.04.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 03/06/2018] [Accepted: 04/11/2018] [Indexed: 12/21/2022]
Abstract
Membrane surface charge is critical for the transient, yet specific recruitment of proteins with polybasic regions to certain organelles. In eukaryotes, the plasma membrane (PM) is the most electronegative compartment of the cell, which specifies its identity. As such, membrane electrostatics is a central parameter in signaling, intracellular trafficking, and polarity. Here, we explore which are the lipids that control membrane electrostatics using plants as a model. We show that phosphatidylinositol-4-phosphate (PI4P), phosphatidic acidic (PA), and phosphatidylserine (PS) are separately required to generate the electrostatic signature of the plant PM. In addition, we reveal the existence of an electrostatic territory that is organized as a gradient along the endocytic pathway and is controlled by PS/PI4P combination. Altogether, we propose that combinatorial lipid composition of the cytosolic leaflet of organelles not only defines the electrostatic territory but also distinguishes different functional compartments within this territory by specifying their varying surface charges.
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Affiliation(s)
- Matthieu Pierre Platre
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Lise C Noack
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Mehdi Doumane
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Vincent Bayle
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Mathilde Laetitia Audrey Simon
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Lilly Maneta-Peyret
- UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, Bâtiment A3 - INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux- CS 20032, Villenave d'Ornon 33140, France
| | - Laetitia Fouillen
- UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, Bâtiment A3 - INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux- CS 20032, Villenave d'Ornon 33140, France; Metabolome-Lipidome Facility of Bordeaux, Functional Genomics Center, Villenave d'Ornon, France
| | - Thomas Stanislas
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Laia Armengot
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Přemysl Pejchar
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6 - Lysolaje, Czech Republic
| | - Marie-Cécile Caillaud
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France
| | - Martin Potocký
- Institute of Experimental Botany, Czech Academy of Sciences, 16502 Prague 6 - Lysolaje, Czech Republic
| | - Alenka Čopič
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris 75013, France
| | - Patrick Moreau
- UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, Bâtiment A3 - INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux- CS 20032, Villenave d'Ornon 33140, France; Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, Bordeaux 33000, France
| | - Yvon Jaillais
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon 69342, France.
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45
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Nisini R, Poerio N, Mariotti S, De Santis F, Fraziano M. The Multirole of Liposomes in Therapy and Prevention of Infectious Diseases. Front Immunol 2018; 9:155. [PMID: 29459867 PMCID: PMC5807682 DOI: 10.3389/fimmu.2018.00155] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 01/17/2018] [Indexed: 12/17/2022] Open
Abstract
Liposomes are closed bilayer structures spontaneously formed by hydrated phospholipids that are widely used as efficient delivery systems for drugs or antigens, due to their capability to encapsulate bioactive hydrophilic, amphipathic, and lipophilic molecules into inner water phase or within lipid leaflets. The efficacy of liposomes as drug or antigen carriers has been improved in the last years to ameliorate pharmacokinetics and capacity to release their cargo in selected target organs or cells. Moreover, different formulations and variations in liposome composition have been often proposed to include immunostimulatory molecules, ligands for specific receptors, or stimuli responsive compounds. Intriguingly, independent research has unveiled the capacity of several phospholipids to play critical roles as intracellular messengers in modulating both innate and adaptive immune responses through various mechanisms, including (i) activation of different antimicrobial enzymatic pathways, (ii) driving the fusion–fission events between endosomes with direct consequences to phagosome maturation and/or to antigen presentation pathway, and (iii) modulation of the inflammatory response. These features can be exploited by including selected bioactive phospholipids in the bilayer scaffold of liposomes. This would represent an important step forward since drug or antigen carrying liposomes could be engineered to simultaneously activate different signal transduction pathways and target specific cells or tissues to induce antigen-specific T and/or B cell response. This lipid-based host-directed strategy can provide a focused antimicrobial innate and adaptive immune response against specific pathogens and offer a novel prophylactic or therapeutic option against chronic, recurrent, or drug-resistant infections.
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Affiliation(s)
- Roberto Nisini
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Noemi Poerio
- Dipartimento di Biologia, Università degli Studi di Roma "Tor Vergata", Rome, Italy
| | - Sabrina Mariotti
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Federica De Santis
- Dipartimento di Biologia, Università degli Studi di Roma "Tor Vergata", Rome, Italy
| | - Maurizio Fraziano
- Dipartimento di Biologia, Università degli Studi di Roma "Tor Vergata", Rome, Italy
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46
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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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47
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Abstract
Phagocytosis refers to the active process that allows cells to take up large particulate material upon binding to surface receptors. The discovery of phagocytosis in 1883 by Elie Metchnikoff, leading to the concept that specialized cells are implicated in the defense against microbes, was one of the starting points of the field of immunology. After more than a century of research, phagocytosis is now appreciated to be a widely used process that enables the cellular uptake of a remarkable variety of particles, including bacteria, fungi, parasites, viruses, dead cells, and assorted debris and solid materials. Uptake of foreign particles is performed almost exclusively by specialized myeloid cells, commonly termed "professional phagocytes": neutrophils, monocytes, macrophages, and dendritic cells. Phagocytosis of microbes not only stops or at least restricts the spread of infection but also plays an important role in regulating the innate and adaptive immune responses. Activation of the myeloid cells upon phagocytosis leads to the secretion of cytokines and chemokines that convey signals to a variety of immune cells. Moreover, foreign antigens generated by the degradation of microbes following phagocytosis are loaded onto the major histocompatibility complex for presentation to specific T lymphocytes. However, phagocytosis is not restricted to professional myeloid phagocytes; an expanding diversity of cell types appear capable of engulfing apoptotic bodies and debris, playing a critical role in tissue remodeling and in the clearance of billions of effete cells every day.
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48
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Smith LC, Lun CM. The SpTransformer Gene Family (Formerly Sp185/333) in the Purple Sea Urchin and the Functional Diversity of the Anti-Pathogen rSpTransformer-E1 Protein. Front Immunol 2017; 8:725. [PMID: 28713368 PMCID: PMC5491942 DOI: 10.3389/fimmu.2017.00725] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/08/2017] [Indexed: 12/12/2022] Open
Abstract
The complex innate immune system of sea urchins is underpinned by several multigene families including the SpTransformer family (SpTrf; formerly Sp185/333) with estimates of ~50 members, although the family size is likely variable among individuals of Strongylocentrotus purpuratus. The genes are small with similar structure, are tightly clustered, and have several types of repeats in the second of two exons and that surround each gene. The density of repeats suggests that the genes are positioned within regions of genomic instability, which may be required to drive sequence diversification. The second exon encodes the mature protein and is composed of blocks of sequence called elements that are present in mosaics of defined element patterns and are the major source of sequence diversity. The SpTrf genes respond swiftly to immune challenge, but only a single gene is expressed per phagocyte. Many of the mRNAs appear to be edited and encode proteins with altered and/or missense sequence that are often truncated, of which some may be functional. The standard SpTrf protein structure is an N-terminal glycine-rich region, a central RGD motif, a histidine-rich region, and a C-terminal region. Function is predicted from a recombinant protein, rSpTransformer-E1 (rSpTrf-E1), which binds to Vibrio and Saccharomyces, but not to Bacillus, and binds tightly to lipopolysaccharide, β-1,3-glucan, and flagellin, but not to peptidoglycan. rSpTrf-E1 is intrinsically disordered but transforms to α helical structure in the presence of binding targets including lipopolysaccharide, which may underpin the characteristics of binding to multiple targets. SpTrf proteins associate with coelomocyte membranes, and rSpTrf-E1 binds specifically to phosphatidic acid (PA). When rSpTrf-E1 is bound to PA in liposome membranes, it induces morphological changes in liposomes that correlate with PA clustering and leakage of luminal contents, and it extracts or removes PA from the bilayer. The multitasking activities of rSpTrf-E1 infer multiple and perhaps overlapping activities for the hundreds of native SpTrf proteins that are produced by individual sea urchins. This likely generates a flexible and highly protective immune system for the sea urchin in its marine habitat that it shares with broad arrays of microbes that may be pathogens and opportunists.
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Affiliation(s)
- L Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - Cheng Man Lun
- Department of Biological Sciences, George Washington University, Washington, DC, United States
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Macrophages and Phospholipases at the Intersection between Inflammation and the Pathogenesis of HIV-1 Infection. Int J Mol Sci 2017; 18:ijms18071390. [PMID: 28661459 PMCID: PMC5535883 DOI: 10.3390/ijms18071390] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 06/22/2017] [Accepted: 06/26/2017] [Indexed: 12/12/2022] Open
Abstract
Persistent low grade immune activation and chronic inflammation are nowadays considered main driving forces of the progressive immunologic failure in effective antiretroviral therapy treated HIV-1 infected individuals. Among the factors contributing to this phenomenon, microbial translocation has emerged as a key driver of persistent immune activation. Indeed, the rapid depletion of gastrointestinal CD4+ T lymphocytes occurring during the early phases of infection leads to a deterioration of the gut epithelium followed by the translocation of microbial products into the systemic circulation and the subsequent activation of innate immunity. In this context, monocytes/macrophages are increasingly recognized as an important source of inflammation, linked to HIV-1 disease progression and to non-AIDS complications, such as cardiovascular disease and neurocognitive decline, which are currently main challenges in treated patients. Lipid signaling plays a central role in modulating monocyte/macrophage activation, immune functions and inflammatory responses. Phospholipase-mediated phospholipid hydrolysis leads to the production of lipid mediators or second messengers that affect signal transduction, thus regulating a variety of physiologic and pathophysiologic processes. In this review, we discuss the contribution of phospholipases to monocyte/macrophage activation in the context of HIV-1 infection, focusing on their involvement in virus-associated chronic inflammation and co-morbidities.
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Lun CM, Samuel RL, Gillmor SD, Boyd A, Smith LC. The Recombinant Sea Urchin Immune Effector Protein, rSpTransformer-E1, Binds to Phosphatidic Acid and Deforms Membranes. Front Immunol 2017; 8:481. [PMID: 28553283 PMCID: PMC5427130 DOI: 10.3389/fimmu.2017.00481] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/06/2017] [Indexed: 01/11/2023] Open
Abstract
The purple sea urchin, Strongylocentrotus purpuratus, possesses a sophisticated innate immune system that functions without adaptive capabilities and responds to pathogens effectively by expressing the highly diverse SpTransformer gene family (formerly the Sp185/333 gene family). The swift gene expression response and the sequence diversity of SpTransformer cDNAs suggest that the encoded proteins have immune functions. Individual sea urchins can express up to 260 distinct SpTransformer proteins, and their diversity suggests that different versions may have different functions. Although the deduced proteins are diverse, they share an overall structure of a hydrophobic leader, a glycine-rich N-terminal region, a histidine-rich region, and a C-terminal region. Circular dichroism analysis of a recombinant SpTransformer protein, rSpTransformer-E1 (rSpTrf-E1) demonstrates that it is intrinsically disordered and transforms to α helical in the presence of buffer additives and binding targets. Although native SpTrf proteins are associated with the membranes of perinuclear vesicles in the phagocyte class of coelomocytes and are present on the surface of small phagocytes, they have no predicted transmembrane region or conserved site for glycophosphatidylinositol linkage. To determine whether native SpTrf proteins associate with phagocyte membranes through interactions with lipids, when rSpTrf-E1 is incubated with lipid-embedded nylon strips, it binds to phosphatidic acid (PA) through both the glycine-rich region and the histidine-rich region. Synthetic liposomes composed of PA and phosphatidylcholine show binding between rSpTrf-E1 and PA by fluorescence resonance energy transfer, which is associated with leakage of luminal contents suggesting changes in lipid organization and perhaps liposome lysis. Interactions with liposomes also change membrane curvature leading to liposome budding, fusion, and invagination, which is associated with PA clustering induced by rSpTrf-E1 binding. Longer incubations result in the extraction of PA from the liposomes, which form disorganized clusters. CD shows that when rSpTrf-E1 binds to PA, it changes its secondary structure from disordered to α helical. These results provide evidence for how SpTransformer proteins may associate with molecules that have exposed phosphates including PA on cell membranes and how the characteristic of protein multimerization may drive changes in the organization of membrane lipids.
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Affiliation(s)
- Cheng Man Lun
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - Robin L. Samuel
- Department of Chemistry, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - Susan D. Gillmor
- Department of Chemistry, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - Anthony Boyd
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, Washington, DC, USA
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, Washington, DC, USA
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