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Hou G, Wang X, Wang A, Yuan L, Zheng Q, Xiao H, Wang H. The role of secreted proteins in efferocytosis. Front Cell Dev Biol 2024; 11:1332482. [PMID: 38259511 PMCID: PMC10800375 DOI: 10.3389/fcell.2023.1332482] [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: 11/03/2023] [Accepted: 12/20/2023] [Indexed: 01/24/2024] Open
Abstract
The clearance of apoptotic cells known as efferocytosis is the final stage of apoptosis, and includes the recognition, phagocytosis, and degradation of apoptotic cells. The maintenance of tissue homeostasis requires the daily elimination of billions of apoptotic cells from the human body via the process of efferocytosis. Accordingly, aberrations in efferocytosis underlie a growing list of diseases, including atherosclerosis, cancer, and infections. During the initial phase of apoptosis, "Eat-Me" signals are exposed and recognized by phagocytes either directly through phagocyte receptors or indirectly through secreted proteins that function as bridge molecules that cross-link dying cells to phagocytes. Here, we set out to provide a comprehensive review of the molecular mechanisms and biological significance of secreted proteins in apoptotic cell clearance. Specifically, it focuses on how these secreted proteins act as bridging molecules to facilitate the clearance process.
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Affiliation(s)
| | | | | | | | | | - Hui Xiao
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
| | - Hui Wang
- College of Life Sciences, Shaanxi Normal University, Xi’an, China
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2
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Park J, Chung WS. Astrocyte-dependent circuit remodeling by synapse phagocytosis. Curr Opin Neurobiol 2023; 81:102732. [PMID: 37247606 DOI: 10.1016/j.conb.2023.102732] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/30/2023] [Accepted: 05/03/2023] [Indexed: 05/31/2023]
Abstract
In the central nervous system, synaptic pruning, the removal of unnecessary synaptic contacts, is an essential process for proper circuit maturation in neurodevelopment as well as for synaptic homeostasis in the adult stage. Dysregulation of synaptic pruning can contribute to the initiation and progression of various mental disorders, such as schizophrenia and depression, as well as neurodegenerative diseases including Alzheimer's disease. In the past 15 years, pioneering works have demonstrated that different types of glial cells regulate the number of synapses by selectively eliminating them through phagocytic molecular machinery. Although a majority of findings have been focused on microglia, it is increasingly evident that astrocytes function as a critical player in activity-dependent synapse elimination in developing, adult, and diseased brains. In this review, we will discuss recent findings showing the mechanisms and physiological importance of astrocyte-mediated synapse elimination in controlling synapses and circuit homeostasis. We propose that astrocytes play dominant and non-redundant roles in eliminating synapses during the activity-dependent circuit remodeling processes that do not involve neuro-inflammation.
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Affiliation(s)
- Jungjoo Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
| | - Won-Suk Chung
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
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3
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Wang Y, Zhang R, Huang S, Valverde PTT, Lobb-Rabe M, Ashley J, Venkatasubramanian L, Carrillo RA. Glial Draper signaling triggers cross-neuron plasticity in bystander neurons after neuronal cell death in Drosophila. Nat Commun 2023; 14:4452. [PMID: 37488133 PMCID: PMC10366216 DOI: 10.1038/s41467-023-40142-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/07/2023] [Indexed: 07/26/2023] Open
Abstract
Neuronal cell death and subsequent brain dysfunction are hallmarks of aging and neurodegeneration, but how the nearby healthy neurons (bystanders) respond to the death of their neighbors is not fully understood. In the Drosophila larval neuromuscular system, bystander motor neurons can structurally and functionally compensate for the loss of their neighbors by increasing their terminal bouton number and activity. We term this compensation as cross-neuron plasticity, and in this study, we demonstrate that the Drosophila engulfment receptor, Draper, and the associated kinase, Shark, are required for cross-neuron plasticity. Overexpression of the Draper-I isoform boosts cross-neuron plasticity, implying that the strength of plasticity correlates with Draper signaling. In addition, we find that functional cross-neuron plasticity can be induced at different developmental stages. Our work uncovers a role for Draper signaling in cross-neuron plasticity and provides insights into how healthy bystander neurons respond to the loss of their neighboring neurons.
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Affiliation(s)
- Yupu Wang
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA.
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, 20147, USA.
| | - Ruiling Zhang
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Sihao Huang
- Program in Biochemistry and Molecular Biophysics, University of Chicago, Chicago, IL, 60637, USA
| | - Parisa Tajalli Tehrani Valverde
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Meike Lobb-Rabe
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - James Ashley
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA
| | | | - Robert A Carrillo
- Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL, 60637, USA.
- Neuroscience Institute, University of Chicago, Chicago, IL, 60637, USA.
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA.
- Program in Cell and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA.
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4
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Wang Y, Zhang R, Huang S, Valverde PTT, Lobb-Rabe M, Ashley J, Venkatasubramanian L, Carrillo RA. Glial Draper signaling triggers cross-neuron plasticity in bystander neurons after neuronal cell death. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.09.536190. [PMID: 37090512 PMCID: PMC10120647 DOI: 10.1101/2023.04.09.536190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Neuronal cell death and subsequent brain dysfunction are hallmarks of aging and neurodegeneration, but how the nearby healthy neurons (bystanders) respond to the cell death of their neighbors is not fully understood. In the Drosophila larval neuromuscular system, bystander motor neurons can structurally and functionally compensate for the loss of their neighbors by increasing their axon terminal size and activity. We termed this compensation as cross-neuron plasticity, and in this study, we demonstrated that the Drosophila engulfment receptor, Draper, and the associated kinase, Shark, are required in glial cells. Surprisingly, overexpression of the Draper-I isoform boosts cross-neuron plasticity, implying that the strength of plasticity correlates with Draper signaling. Synaptic plasticity normally declines as animals age, but in our system, functional cross-neuron plasticity can be induced at different time points, whereas structural cross-neuron plasticity can only be induced at early stages. Our work uncovers a novel role for glial Draper signaling in cross-neuron plasticity that may enhance nervous system function during neurodegeneration and provides insights into how healthy bystander neurons respond to the loss of their neighboring neurons.
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5
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Song C, Broadie K. Fragile X mental retardation protein coordinates neuron-to-glia communication for clearance of developmentally transient brain neurons. Proc Natl Acad Sci U S A 2023; 120:e2216887120. [PMID: 36920921 PMCID: PMC10041173 DOI: 10.1073/pnas.2216887120] [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: 10/05/2022] [Accepted: 02/07/2023] [Indexed: 03/16/2023] Open
Abstract
In the developmental remodeling of brain circuits, neurons are removed by glial phagocytosis to optimize adult behavior. Fragile X mental retardation protein (FMRP) regulates neuron-to-glia signaling to drive glial phagocytosis for targeted neuron pruning. We find that FMRP acts in a mothers against decapentaplegic (Mad)-insulin receptor (InR)-protein kinase B (Akt) pathway to regulate pretaporter (Prtp) and amyloid precursor protein-like (APPL) signals directing this glial clearance. Neuronal RNAi of Drosophila fragile X mental retardation 1 (dfmr1) elevates mad transcript levels and increases pMad signaling. Neuronal dfmr1 and mad RNAi both elevate phospho-protein kinase B (pAkt) and delay neuron removal but cause opposite effects on InR expression. Genetically correcting pAkt levels in the mad RNAi background restores normal remodeling. Consistently, neuronal dfmr1 and mad RNAi both decrease Prtp levels, whereas neuronal InR and akt RNAi increase Prtp levels, indicating FMRP works with pMad and insulin signaling to tightly regulate Prtp signaling and thus control glial phagocytosis for correct circuit remodeling. Neuronal dfmr1 and mad and akt RNAi all decrease APPL levels, with the pathway signaling higher glial endolysosome activity for phagocytosis. These findings reveal a FMRP-dependent control pathway for neuron-to-glia communication in neuronal pruning, identifying potential molecular mechanisms for devising fragile X syndrome treatments.
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Affiliation(s)
- Chunzhu Song
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN37235
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, TN37235
- Department of Cell and Developmental Biology, Vanderbilt University and Medical Center, Nashville, TN37235
- Kennedy Center for Research on Human Development, Vanderbilt University and Medical Center, Nashville, TN37235
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, TN37235
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6
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Lin S. The making of the Drosophila mushroom body. Front Physiol 2023; 14:1091248. [PMID: 36711013 PMCID: PMC9880076 DOI: 10.3389/fphys.2023.1091248] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/02/2023] [Indexed: 01/14/2023] Open
Abstract
The mushroom body (MB) is a computational center in the Drosophila brain. The intricate neural circuits of the mushroom body enable it to store associative memories and process sensory and internal state information. The mushroom body is composed of diverse types of neurons that are precisely assembled during development. Tremendous efforts have been made to unravel the molecular and cellular mechanisms that build the mushroom body. However, we are still at the beginning of this challenging quest, with many key aspects of mushroom body assembly remaining unexplored. In this review, I provide an in-depth overview of our current understanding of mushroom body development and pertinent knowledge gaps.
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7
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Song C, Broadie K. Dysregulation of BMP, Wnt, and Insulin Signaling in Fragile X Syndrome. Front Cell Dev Biol 2022; 10:934662. [PMID: 35880195 PMCID: PMC9307498 DOI: 10.3389/fcell.2022.934662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 06/06/2022] [Indexed: 01/21/2023] Open
Abstract
Drosophila models of neurological disease contribute tremendously to research progress due to the high conservation of human disease genes, the powerful and sophisticated genetic toolkit, and the rapid generation time. Fragile X syndrome (FXS) is the most prevalent heritable cause of intellectual disability and autism spectrum disorders, and the Drosophila FXS disease model has been critical for the genetic screening discovery of new intercellular secretion mechanisms. Here, we focus on the roles of three major signaling pathways: BMP, Wnt, and insulin-like peptides. We present Drosophila FXS model defects compared to mouse models in stem cells/embryos, the glutamatergic neuromuscular junction (NMJ) synapse model, and the developing adult brain. All three of these secreted signaling pathways are strikingly altered in FXS disease models, giving new mechanistic insights into impaired cellular outcomes and neurological phenotypes. Drosophila provides a powerful genetic screening platform to expand understanding of these secretory mechanisms and to test cellular roles in both peripheral and central nervous systems. The studies demonstrate the importance of exploring broad genetic interactions and unexpected regulatory mechanisms. We discuss a number of research avenues to pursue BMP, Wnt, and insulin signaling in future FXS investigations and the development of potential therapeutics.
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Affiliation(s)
- Chunzhu Song
- Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN, United States
| | - Kendal Broadie
- Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN, United States
- Department of Cell and Developmental Biology, School of Medicine, Vanderbilt University, Nashville, TN, United States
- Kennedy Center for Research on Human Development, Nashville, TN, United States
- Vanderbilt Brain Institute, School of Medicine, Vanderbilt University and Medical Center, Nashville, TN, United States
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8
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Disruption of the lipolysis pathway results in stem cell death through a sterile immunity-like pathway in adult Drosophila. Cell Rep 2022; 39:110958. [PMID: 35732115 PMCID: PMC9377423 DOI: 10.1016/j.celrep.2022.110958] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 01/26/2022] [Accepted: 05/23/2022] [Indexed: 11/29/2022] Open
Abstract
We previously showed that the Arf1-mediated lipolysis pathway sustains stem cells and cancer stem cells (CSCs); its ablation resulted in necrosis of stem cells and CSCs, which further triggers a systemic antitumor immune response. Here we show that knocking down Arf1 in intestinal stem cells (ISCs) causes metabolic stress, which promotes the expression and translocation of ISC-produced damage-associated molecular patterns (DAMPs; Pretaporter [Prtp] and calreticulin [Calr]). DAMPs regulate macroglobulin complement-related (Mcr) expression and secretion. The secreted Mcr influences the expression and localization of enterocyte (EC)-produced Draper (Drpr) and LRP1 receptors (pattern recognition receptors [PRRs]) to activate autophagy in ECs for ATP production. The secreted ATP possibly feeds back to kill ISCs by activating inflammasome-like pyroptosis. We identify an evolutionarily conserved pathway that sustains stem cells and CSCs, and its ablation results in an immunogenic cascade that promotes death of stem cells and CSCs as well as antitumor immunity. Aggarwal et al. show that disruption of Arf1-mediated lipolysis results in stem cell death through a sterile immunity-like pathway in adult Drosophila. They identify an evolutionarily conserved pathway that specifically sustains stem cells and cancer stem cells (CSCs), and its ablation results in an immunogenic cascade that promotes death of stem cells and CSCs as well as antitumor immunity.
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9
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Coupe D, Bossing T. Insights into nervous system repair from the fruit fly. Neuronal Signal 2022; 6:NS20210051. [PMID: 35474685 PMCID: PMC9008705 DOI: 10.1042/ns20210051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 11/17/2022] Open
Abstract
Millions of people experience injury to the central nervous system (CNS) each year, many of whom are left permanently disabled, providing a challenging hurdle for the field of regenerative medicine. Repair of damage in the CNS occurs through a concerted effort of phagocytosis of debris, cell proliferation and differentiation to produce new neurons and glia, distal axon/dendrite degeneration, proximal axon/dendrite regeneration and axon re-enwrapment. In humans, regeneration is observed within the peripheral nervous system, while in the CNS injured axons exhibit limited ability to regenerate. This has also been described for the fruit fly Drosophila. Powerful genetic tools available in Drosophila have allowed the response to CNS insults to be probed and novel regulators with mammalian orthologs identified. The conservation of many regenerative pathways, despite considerable evolutionary separation, stresses that these signals are principal regulators and may serve as potential therapeutic targets. Here, we highlight the role of Drosophila CNS injury models in providing key insight into regenerative processes by exploring the underlying pathways that control glial and neuronal activation in response to insult, and their contribution to damage repair in the CNS.
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Affiliation(s)
- David Coupe
- Peninsula Medical School, University of Plymouth, John Bull Building, 16 Research Way, Plymouth PL6 8BU, U.K
| | - Torsten Bossing
- Peninsula Medical School, University of Plymouth, John Bull Building, 16 Research Way, Plymouth PL6 8BU, U.K
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10
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Boulanger A, Dura JM. Neuron-glia crosstalk in neuronal remodeling and degeneration: Neuronal signals inducing glial cell phagocytic transformation in Drosophila. Bioessays 2022; 44:e2100254. [PMID: 35315125 DOI: 10.1002/bies.202100254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 11/09/2022]
Abstract
Neuronal remodeling is a conserved mechanism that eliminates unwanted neurites and can include the loss of cell bodies. In these processes, a key role for glial cells in events from synaptic pruning to neuron elimination has been clearly identified in the last decades. Signals sent from dying neurons or neurites to be removed are received by appropriate glial cells. After receiving these signals, glial cells infiltrate degenerating sites and then, engulf and clear neuronal debris through phagocytic mechanisms. There are few identified or proposed signals and receptors involved in neuron-glia crosstalk, which induces the transformation of glial cells to phagocytes during neuronal remodeling in Drosophila. Many of these signaling pathways are conserved in mammals. Here, we particularly emphasize the role of Orion, a recently identified neuronal CX3 C chemokine-like secreted protein, which induces astrocyte infiltration and engulfment during mushroom body neuronal remodeling. Although, chemokine signaling was not described previously in insects we propose that chemokine-like involvement in neuron/glial cell interaction is an evolutionarily ancient mechanism.
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Affiliation(s)
- Ana Boulanger
- IGH, Université de Montpellier, CNRS, Montpellier, France
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11
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Konishi H, Koizumi S, Kiyama H. Phagocytic astrocytes: Emerging from the shadows of microglia. Glia 2022; 70:1009-1026. [PMID: 35142399 PMCID: PMC9305589 DOI: 10.1002/glia.24145] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/18/2021] [Accepted: 01/07/2022] [Indexed: 12/12/2022]
Abstract
Elimination of dead or live cells take place in both a healthy and diseased central nervous system (CNS). Dying or dead cells are quickly cleared by phagocytosis for the maintenance of a healthy CNS or for recovery after injury. Live cells or parts thereof, such as the synapses and myelin, are appropriately eliminated by phagocytosis to maintain or refine neural networks during development and adulthood. Microglia, the specific population of resident macrophages in the CNS, are classically considered as primary phagocytes; however, astrocytes have also been highlighted as phagocytes in the last decade. Phagocytic targets and receptors are reported to be mostly common between astrocytes and microglia, which raises the question of how astrocytic phagocytosis differs from microglial phagocytosis, and how these two phagocytic systems cooperate. In this review, we address the consequences of astrocytic phagocytosis, particularly focusing on these elusive points.
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Affiliation(s)
- Hiroyuki Konishi
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, University of Yamanashi, Yamanashi, Japan.,GLIA Center, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Hiroshi Kiyama
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, Nagoya, Japan
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12
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Järvelä-Stölting M, Vesala L, Maasdorp MK, Ciantar J, Rämet M, Valanne S. Proteasome α6 Subunit Negatively Regulates the JAK/STAT Pathway and Blood Cell Activation in Drosophila melanogaster. Front Immunol 2021; 12:729631. [PMID: 35003057 PMCID: PMC8727353 DOI: 10.3389/fimmu.2021.729631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
JAK/STAT signaling regulates central biological functions such as development, cell differentiation and immune responses. In Drosophila, misregulated JAK/STAT signaling in blood cells (hemocytes) induces their aberrant activation. Using mass spectrometry to analyze proteins associated with a negative regulator of the JAK/STAT pathway, and by performing a genome-wide RNAi screen, we identified several components of the proteasome complex as negative regulators of JAK/STAT signaling in Drosophila. A selected proteasome component, Prosα6, was studied further. In S2 cells, Prosα6 silencing decreased the amount of the known negative regulator of the pathway, ET, leading to enhanced expression of a JAK/STAT pathway reporter gene. Silencing of Prosα6 in vivo resulted in activation of the JAK/STAT pathway, leading to the formation of lamellocytes, a specific hemocyte type indicative of hemocyte activation. This hemocyte phenotype could be partially rescued by simultaneous knockdown of either the Drosophila STAT transcription factor, or MAPKK in the JNK-pathway. Our results suggest a role for the proteasome complex components in the JAK/STAT pathway in Drosophila blood cells both in vitro and in vivo.
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Affiliation(s)
- Mirva Järvelä-Stölting
- Laboratory of Experimental Immunology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Laura Vesala
- Laboratory of Experimental Immunology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Matthew K. Maasdorp
- Laboratory of Experimental Immunology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Joanna Ciantar
- Laboratory of Experimental Immunology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Mika Rämet
- Laboratory of Experimental Immunology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Research Unit for Pediatrics, Pediatric Neurology, Pediatric Surgery, Child Psychiatry, Dermatology, Clinical Genetics, Obstetrics and Gynecology, Otorhinolaryngology and Ophthalmology, Faculty of Medicine, University of Oulu, Oulu, Finland
- Medical Research Center Oulu, University of Oulu, Oulu, Finland
- Department of Children and Adolescents, Oulu University Hospital, University of Oulu, Oulu, Finland
| | - Susanna Valanne
- Laboratory of Experimental Immunology, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- *Correspondence: Susanna Valanne,
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13
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Gul I, Kausar S, You Q, Sun W, Li Z, Abbas MN, Cui H. Identification and the immunological role of two Nimrod family genes in the silkworm, Bombyx mori. Int J Biol Macromol 2021; 193:154-165. [PMID: 34688681 DOI: 10.1016/j.ijbiomac.2021.10.083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 01/30/2023]
Abstract
In animals, immune signaling pathways and effector molecules participate in attenuating microbial infection. Recent work has shown that the Nimrod family proteins can directly bind to bacteria, and this binding leads to bacterial phagocytosis. Although the Nimrod gene family has been reported in many non-drosophilids, their functions remain unexplored in most insect species. Here, we report two members (Nimrod-B and Draper) of the Nimrod gene family from Bombyx mori and analyzed their role in immunity. The two genes were ubiquitously expressed in the tested tissues; but, they transcribed preferentially in immune tissues. The developmental profiles showed that BmNimrod-B and BmDraper transcription levels were highest in the pupal stages. Challenge with microbial pathogens induced the transcription levels of all two genes at different time points. Knockdown of BmDraper decreased the bacterial clearance and increased their replication relative to the control group, whereas, BmNimrod-B suppression had a non-significant effect on them. Furthermore, the mortality rate was increased after BmDraper silencing. The knockdown of these genes did not significantly affect the production of antimicrobial peptides following E. coli infection. Taken together, the Nimrod family genes play a crucial role in host defense by positively regulating the antibacterial immune response in silkworm B. mori.
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Affiliation(s)
- Isma Gul
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, China; Cancer Center, Medical Research Institute, Southwest University, Chongqing 400716, China
| | - Saima Kausar
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, China; Cancer Center, Medical Research Institute, Southwest University, Chongqing 400716, China
| | - Qiuxiang You
- Neurological Disease Center of the Third Affiliated Hospital of Chongqing Medical University, 401120, China
| | - Wei Sun
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, China; Cancer Center, Medical Research Institute, Southwest University, Chongqing 400716, China
| | - Zekun Li
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, China; Cancer Center, Medical Research Institute, Southwest University, Chongqing 400716, China
| | - Muhammad Nadeem Abbas
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, China; Cancer Center, Medical Research Institute, Southwest University, Chongqing 400716, China.
| | - Hongjuan Cui
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, China; Cancer Center, Medical Research Institute, Southwest University, Chongqing 400716, China.
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14
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Britt EA, Gitau V, Saha A, Williamson AP. Modular Organization of Engulfment Receptors and Proximal Signaling Networks: Avenues to Reprogram Phagocytosis. Front Immunol 2021; 12:661974. [PMID: 33953723 PMCID: PMC8092387 DOI: 10.3389/fimmu.2021.661974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Transmembrane protein engulfment receptors expressed on the surface of phagocytes engage ligands on apoptotic cells and debris to initiate a sequence of events culminating in material internalization and immunologically beneficial outcomes. Engulfment receptors are modular, comprised of functionally independent extracellular ligation domains and cytosolic signaling motifs. Cognate kinases, adaptors, and phosphatases regulate engulfment by controlling the degree of receptor activation in phagocyte plasma membranes, thus acting as receptor-proximal signaling modules. Here, we review recent efforts to reprogram phagocytes using modular synthetic receptors composed of antibody-based extracellular domains fused to engulfment receptor signaling domains. To aid the development of new phagocyte reprogramming methods, we then define the kinases, adaptors, and phosphatases that regulate a conserved family of engulfment receptors. Finally, we discuss current challenges and opportunities for the field.
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Affiliation(s)
- Emily A Britt
- Department of Biology, Bryn Mawr College, Bryn Mawr, PA, United States
| | - Vanessa Gitau
- Department of Biology, Bryn Mawr College, Bryn Mawr, PA, United States
| | - Amara Saha
- Department of Biology, Bryn Mawr College, Bryn Mawr, PA, United States
| | - Adam P Williamson
- Department of Biology, Bryn Mawr College, Bryn Mawr, PA, United States
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15
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Axonal chemokine-like Orion induces astrocyte infiltration and engulfment during mushroom body neuronal remodeling. Nat Commun 2021; 12:1849. [PMID: 33758182 PMCID: PMC7988174 DOI: 10.1038/s41467-021-22054-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 02/25/2021] [Indexed: 11/13/2022] Open
Abstract
The remodeling of neurons is a conserved fundamental mechanism underlying nervous system maturation and function. Astrocytes can clear neuronal debris and they have an active role in neuronal remodeling. Developmental axon pruning of Drosophila memory center neurons occurs via a degenerative process mediated by infiltrating astrocytes. However, how astrocytes are recruited to the axons during brain development is unclear. Using an unbiased screen, we identify the gene requirement of orion, encoding for a chemokine-like protein, in the developing mushroom bodies. Functional analysis shows that Orion is necessary for both axonal pruning and removal of axonal debris. Orion performs its functions extracellularly and bears some features common to chemokines, a family of chemoattractant cytokines. We propose that Orion is a neuronal signal that elicits astrocyte infiltration and astrocyte-driven axonal engulfment required during neuronal remodeling in the Drosophila developing brain. Astrocytes can engulf axonal debris in the developing brain. However, the mechanisms regulating astrocyte recruitment to the proper axons is unclear. Here, the authors identify Orion as a signal for astrocyte infiltration and engulfment to the mushroom bodies in the Drosophila developing brain.
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16
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Vita DJ, Meier CJ, Broadie K. Neuronal fragile X mental retardation protein activates glial insulin receptor mediated PDF-Tri neuron developmental clearance. Nat Commun 2021; 12:1160. [PMID: 33608547 PMCID: PMC7896095 DOI: 10.1038/s41467-021-21429-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/08/2021] [Indexed: 01/31/2023] Open
Abstract
Glia engulf and phagocytose neurons during neural circuit developmental remodeling. Disrupting this pruning process contributes to Fragile X syndrome (FXS), a leading cause of intellectual disability and autism spectrum disorder in mammals. Utilizing a Drosophila FXS model central brain circuit, we identify two glial classes responsible for Draper-dependent elimination of developmentally transient PDF-Tri neurons. We find that neuronal Fragile X Mental Retardation Protein (FMRP) drives insulin receptor activation in glia, promotes glial Draper engulfment receptor expression, and negatively regulates membrane-molding ESCRT-III Shrub function during PDF-Tri neuron clearance during neurodevelopment in Drosophila. In this context, we demonstrate genetic interactions between FMRP and insulin receptor signaling, FMRP and Draper, and FMRP and Shrub in PDF-Tri neuron elimination. We show that FMRP is required within neurons, not glia, for glial engulfment, indicating FMRP-dependent neuron-to-glia signaling mediates neuronal clearance. We conclude neuronal FMRP drives glial insulin receptor activation to facilitate Draper- and Shrub-dependent neuronal clearance during neurodevelopment in Drosophila.
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Affiliation(s)
- Dominic J Vita
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Cole J Meier
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Kennedy Center for Research on Human Development, Nashville, TN, USA.
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA.
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17
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Davidson AJ, Wood W. Phagocyte Responses to Cell Death in Flies. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a036350. [PMID: 31501193 DOI: 10.1101/cshperspect.a036350] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Multicellular organisms are not created through cell proliferation alone. It is through cell death that an indefinite cellular mass is pared back to reveal its true form. Cells are also lost throughout life as part of homeostasis and through injury. This detritus represents a significant burden to the living organism and must be cleared, most notably through the use of specialized phagocytic cells. Our understanding of these phagocytes and how they engulf cell corpses has been greatly aided by studying the fruit fly, Drosophila melanogaster Here we review the contribution of Drosophila research to our understanding of how phagocytes respond to cell death. We focus on the best studied phagocytes in the fly: the glia of the central nervous system, the ovarian follicle cells, and the macrophage-like hemocytes. Each is explored in the context of the tissue they maintain as well as how they function during development and in response to injury.
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Affiliation(s)
- Andrew J Davidson
- Centre for Inflammation Research, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
| | - Will Wood
- Centre for Inflammation Research, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
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18
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Wang G, Xu J, Zhao J, Yin W, Liu D, Chen W, Hou SX. Arf1-mediated lipid metabolism sustains cancer cells and its ablation induces anti-tumor immune responses in mice. Nat Commun 2020; 11:220. [PMID: 31924786 PMCID: PMC6954189 DOI: 10.1038/s41467-019-14046-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/11/2019] [Indexed: 01/07/2023] Open
Abstract
Cancer stem cells (CSCs) may be responsible for treatment resistance, tumor metastasis, and disease recurrence. Here we demonstrate that the Arf1-mediated lipid metabolism sustains cells enriched with CSCs and its ablation induces anti-tumor immune responses in mice. Notably, Arf1 ablation in cancer cells induces mitochondrial defects, endoplasmic-reticulum stress, and the release of damage-associated molecular patterns (DAMPs), which recruit and activate dendritic cells (DCs) at tumor sites. The activated immune system finally elicits antitumor immune surveillance by stimulating T-cell infiltration and activation. Furthermore, TCGA data analysis shows an inverse correlation between Arf1 expression and T-cell infiltration and activation along with patient survival in various human cancers. Our results reveal that Arf1-pathway knockdown not only kills CSCs but also elicits a tumor-specific immune response that converts dying CSCs into a therapeutic vaccine, leading to durable benefits. Cancer stem cells (CSC) have been shown as the origin for therapeutic resistance and patient relapse. Here, the authors show that targeting Arf1-mediated lipid metabolism in CSC induces cell death but also an immunogenic anti-cancer response.
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Affiliation(s)
- Guohao Wang
- The Basic Research Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD, 21702, USA
| | - Junji Xu
- Mucosal Immunology Section, Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jiangsha Zhao
- The Basic Research Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD, 21702, USA
| | - Weiqin Yin
- The Basic Research Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD, 21702, USA
| | - Dayong Liu
- The Basic Research Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD, 21702, USA
| | - WanJun Chen
- Mucosal Immunology Section, Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Steven X Hou
- The Basic Research Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD, 21702, USA.
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19
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Microglial clearance of focal apoptotic synapses. Neurosci Lett 2019; 707:134317. [DOI: 10.1016/j.neulet.2019.134317] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 05/13/2019] [Accepted: 06/02/2019] [Indexed: 01/23/2023]
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20
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Melcarne C, Lemaitre B, Kurant E. Phagocytosis in Drosophila: From molecules and cellular machinery to physiology. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 109:1-12. [PMID: 30953686 DOI: 10.1016/j.ibmb.2019.04.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 03/22/2019] [Accepted: 04/01/2019] [Indexed: 05/20/2023]
Abstract
Phagocytosis is an evolutionarily conserved mechanism that plays a key role in both host defence and tissue homeostasis in multicellular organisms. A range of surface receptors expressed on different cell types allow discriminating between self and non-self (or altered) material, thus enabling phagocytosis of pathogens and apoptotic cells. The phagocytosis process can be divided into four main steps: 1) binding of the phagocyte to the target particle, 2) particle internalization and phagosome formation, through remodelling of the plasma membrane, 3) phagosome maturation, and 4) particle destruction in the phagolysosome. In this review, we describe our present knowledge on phagocytosis in the fruit fly Drosophila melanogaster, assessing each of the key steps involved in engulfment of both apoptotic cells and bacteria. We also assess the physiological role of phagocytosis in host defence, development and tissue homeostasis.
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Affiliation(s)
- C Melcarne
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - B Lemaitre
- Global Health Institute, School of Life Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - E Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 34988, Israel.
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21
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Nakano R, Iwamura M, Obikawa A, Togane Y, Hara Y, Fukuhara T, Tomaru M, Takano-Shimizu T, Tsujimura H. Cortex glia clear dead young neurons via Drpr/dCed-6/Shark and Crk/Mbc/dCed-12 signaling pathways in the developing Drosophila optic lobe. Dev Biol 2019; 453:68-85. [PMID: 31063730 DOI: 10.1016/j.ydbio.2019.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 04/25/2019] [Accepted: 05/02/2019] [Indexed: 02/06/2023]
Abstract
The molecular and cellular mechanism for clearance of dead neurons was explored in the developing Drosophila optic lobe. During development of the optic lobe, many neural cells die through apoptosis, and corpses are immediately removed in the early pupal stage. Most of the cells that die in the optic lobe are young neurons that have not extended neurites. In this study, we showed that clearance was carried out by cortex glia via a phagocytosis receptor, Draper (Drpr). drpr expression in cortex glia from the second instar larval to early pupal stages was required and sufficient for clearance. Drpr that was expressed in other subtypes of glia did not mediate clearance. Shark and Ced-6 mediated clearance of Drpr. The Crk/Mbc/dCed-12 pathway was partially involved in clearance, but the role was minor. Suppression of the function of Pretaporter, CaBP1 and phosphatidylserine delayed clearance, suggesting a possibility for these molecules to function as Drpr ligands in the developing optic lobe.
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Affiliation(s)
- Ryosuke Nakano
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Masashi Iwamura
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Akiko Obikawa
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Yu Togane
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Yusuke Hara
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Toshiyuki Fukuhara
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Masatoshi Tomaru
- Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Toshiyuki Takano-Shimizu
- Department of Drosophila Genomics and Genetic Resources, Center for Advanced Insect Research Promotion, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Hidenobu Tsujimura
- Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
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22
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Sapar ML, Han C. Die in pieces: How Drosophila sheds light on neurite degeneration and clearance. J Genet Genomics 2019; 46:187-199. [PMID: 31080046 DOI: 10.1016/j.jgg.2019.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/24/2019] [Accepted: 03/26/2019] [Indexed: 01/08/2023]
Abstract
Dendrites and axons are delicate neuronal membrane extensions that undergo degeneration after physical injuries. In neurodegenerative diseases, they often degenerate prior to neuronal death. Understanding the mechanisms of neurite degeneration has been an intense focus of neurobiology research in the last two decades. As a result, many discoveries have been made in the molecular pathways that lead to neurite degeneration and the cell-cell interactions responsible for the subsequent clearance of neuronal debris. Drosophila melanogaster has served as a prime in vivo model system for identifying and characterizing the key molecular players in neurite degeneration, thanks to its genetic tractability and easy access to its nervous system. The knowledge learned in the fly provided targets and fuel for studies in other model systems that have further enhanced our understanding of neurodegeneration. In this review, we will introduce the experimental systems developed in Drosophila to investigate injury-induced neurite degeneration, and then discuss the biological pathways that drive degeneration. We will also cover what is known about the mechanisms of how phagocytes recognize and clear degenerating neurites, and how recent findings in this area enhance our understanding of neurodegenerative disease pathology.
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Affiliation(s)
- Maria L Sapar
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Chun Han
- Weill Institute for Cell and Molecular Biology, Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
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23
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Characterization of Spz5 as a novel ligand for Drosophila Toll-1 receptor. Biochem Biophys Res Commun 2018; 506:510-515. [PMID: 30361090 DOI: 10.1016/j.bbrc.2018.10.096] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 11/22/2022]
Abstract
The Drosophila Toll-1 receptor is involved in embryonic development, innate immunity, and tissue homeostasis. Currently, as a ligand for the Toll-1 receptor, only Spätzle (Spz) has been identified and characterized. We previously reported that Drosophila larva-derived tissue extract contains ligand activity for the Toll-1 receptor, which differs from Spz based on the observation that larval extract prepared from spz mutants possessed full ligand activity. Here, we demonstrate that Spz5, a member of the Spz family of proteins, functions as a ligand for the Toll-1 receptor. Processing of Spz5 by Furin protease, which is known to be important for ligand activity of Spz5 to Toll-6, is not required for its function to the Toll-1 receptor. By generating a spz5 null mutant, we further showed that the Toll-1 ligand activity of larva-derived extract is mainly derived from Spz5. Finally, we found a genetic interaction between spz and spz5 in terms of developmental processes. This study identified a novel ligand for the Drosophila Toll-1 receptor, providing evidence that Toll-1 is a multi-ligand receptor, similar to the mammalian Toll-like receptor.
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24
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Williamson AP, Vale RD. Spatial control of Draper receptor signaling initiates apoptotic cell engulfment. J Cell Biol 2018; 217:3977-3992. [PMID: 30139739 PMCID: PMC6219719 DOI: 10.1083/jcb.201711175] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 03/25/2018] [Accepted: 07/30/2018] [Indexed: 01/20/2023] Open
Abstract
Clearance of apoptotic cells is essential for tissue maintenance and initiated by recognition of “eat-me” ligands on the dead cells. Using a simplified cellular reconstitution system, Williamson and Vale report that the Drosophila melanogaster engulfment receptor Draper (CED-1/Megf10) is triggered in a manner similar to mammalian immune receptors. The engulfment of apoptotic cells is essential for tissue homeostasis and recovering from damage. Engulfment is mediated by receptors that recognize ligands exposed on apoptotic cells such as phosphatidylserine (PS). In this study, we convert Drosophila melanogaster S2 cells into proficient phagocytes by transfecting the Draper engulfment receptor and replacing apoptotic cells with PS-coated beads. Similar to the T cell receptor (TCR), PS-ligated Draper forms dynamic microclusters that recruit cytosolic effector proteins and exclude a bulky transmembrane phosphatase, consistent with a kinetic segregation-based triggering mechanism. However, in contrast with the TCR, localized signaling at Draper microclusters results in time-dependent depletion of actin filaments, which facilitates engulfment. The Draper–PS extracellular module can be replaced with FRB and FKBP, respectively, resulting in a rapamycin-inducible engulfment system that can be programmed toward defined targets. Collectively, our results reveal mechanistic similarities and differences between the receptors involved in apoptotic corpse clearance and mammalian immunity and demonstrate that engulfment can be reprogrammed toward nonnative targets.
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Affiliation(s)
- Adam P Williamson
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
| | - Ronald D Vale
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA .,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA
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25
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Abstract
Cell death is a perpetual feature of tissue microenvironments; each day under homeostatic conditions, billions of cells die and must be swiftly cleared by phagocytes. However, cell death is not limited to this natural turnover-apoptotic cell death can be induced by infection, inflammation, or severe tissue injury. Phagocytosis of apoptotic cells is thus coupled to specific functions, from the induction of growth factors that can stimulate the replacement of dead cells to the promotion of tissue repair or tissue remodeling in the affected site. In this review, we outline the mechanisms by which phagocytes sense apoptotic cell death and discuss how phagocytosis is integrated with environmental cues to drive appropriate responses.
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Affiliation(s)
- Lidia Bosurgi
- I. Medizinische Klinik und Poliklinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.,Bernard-Nocht-Institut für Tropenmedizin, Hamburg, Germany
| | - Lindsey D Hughes
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA
| | - Carla V Rothlin
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA.,Department of Pharmacology, School of Medicine, Yale University, New Haven, CT, USA
| | - Sourav Ghosh
- Department of Pharmacology, School of Medicine, Yale University, New Haven, CT, USA.,Department of Neurology, School of Medicine, Yale University, New Haven, CT, USA
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26
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Zheng Q, Ma A, Yuan L, Gao N, Feng Q, Franc NC, Xiao H. Apoptotic Cell Clearance in Drosophila melanogaster. Front Immunol 2017; 8:1881. [PMID: 29326726 PMCID: PMC5742343 DOI: 10.3389/fimmu.2017.01881] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/11/2017] [Indexed: 12/13/2022] Open
Abstract
The swift clearance of apoptotic cells (ACs) (efferocytosis) by phagocytes is a critical event during development of all multicellular organisms. It is achieved through phagocytosis by professional or amateur phagocytes. Failure in this process can lead to the development of inflammatory autoimmune or neurodegenerative diseases. AC clearance has been conserved throughout evolution, although many details in its mechanisms remain to be explored. It has been studied in the context of mammalian macrophages, and in the nematode Caenorhabditis elegans, which lacks “professional” phagocytes such as macrophages, but in which other cell types can engulf apoptotic corpses. In Drosophila melanogaster, ACs are engulfed by macrophages, glial, and epithelial cells. Drosophila macrophages perform similar functions to those of mammalian macrophages. They are professional phagocytes that participate in phagocytosis of ACs and pathogens. Study of AC clearance in Drosophila has identified some key elements, like the receptors Croquemort and Draper, promoting Drosophila as a suitable model to genetically dissect this process. In this review, we survey recent works of AC clearance pathways in Drosophila, and discuss the physiological outcomes and consequences of this process.
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Affiliation(s)
- Qian Zheng
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University Xi'an, Xi'an, China
| | - AiYing Ma
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University Xi'an, Xi'an, China.,College of Biological Sciences and Engineering, Beifang University of Nationalities, Yinchuan, NingXia, China
| | - Lei Yuan
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University Xi'an, Xi'an, China
| | - Ning Gao
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University Xi'an, Xi'an, China
| | - Qi Feng
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University Xi'an, Xi'an, China
| | - Nathalie C Franc
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA, United States
| | - Hui Xiao
- Key Laboratory of the Ministry of Education for Medicinal Plant Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in the Northwest of China, College of Life Sciences, Shaanxi Normal University Xi'an, Xi'an, China
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27
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Serizier SB, McCall K. Scrambled Eggs: Apoptotic Cell Clearance by Non-Professional Phagocytes in the Drosophila Ovary. Front Immunol 2017; 8:1642. [PMID: 29238344 PMCID: PMC5712531 DOI: 10.3389/fimmu.2017.01642] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/09/2017] [Indexed: 01/20/2023] Open
Abstract
For half of a century, it has been known that non-professional phagocytes, such as fibroblasts, endothelial, and epithelial cells, are capable of efferocytosis (engulfment of apoptotic cells). Non-professional phagocytes differ from professional phagocytes in the range and efficiency of engulfment. Much of the recognition and underlying signaling machinery between non-professional and professional phagocytes is the same, but it is not known how the engulfment capacity of non-professional phagocytes is controlled. Moreover, the signaling networks involved in cell corpse recognition, engulfment, and phagosome maturation are only partially understood. The Drosophila ovary provides an excellent system to investigate the regulation of phagocytic activity by epithelial cells, a major class of non-professional phagocytes. During Drosophila oogenesis, mid-stage egg chambers undergo apoptosis of the germline in response to nutrient deprivation. Epithelial follicle cells then undergo major cell shape changes and concomitantly engulf the germline material. Our previous work has established that Draper and the integrin α-PS3/β-PS heterodimer are required in follicle cells for germline cell clearance. In addition, we have characterized phagosome maturation pathways, and found that the JNK pathway amplifies the engulfment response. In this review, we discuss recent advances on the interplay between engulfment pathways in the follicular epithelium for cell clearance in the Drosophila ovary. We also provide a comparison to apoptotic cell clearance mechanisms in C. elegans and mammals, illustrating strong conservation of efferocytosis mechanisms by non-professional phagocytes.
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Affiliation(s)
- Sandy B Serizier
- Department of Biology, Boston University, Boston, MA, United States.,Graduate Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA, United States
| | - Kimberly McCall
- Department of Biology, Boston University, Boston, MA, United States
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28
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Glial Draper Rescues Aβ Toxicity in a Drosophila Model of Alzheimer's Disease. J Neurosci 2017; 37:11881-11893. [PMID: 29109235 DOI: 10.1523/jneurosci.0862-17.2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 10/19/2017] [Accepted: 10/23/2017] [Indexed: 12/24/2022] Open
Abstract
Pathological hallmarks of Alzheimer's disease (AD) include amyloid-β (Aβ) plaques, neurofibrillary tangles, and reactive gliosis. Glial cells offer protection against AD by engulfing extracellular Aβ peptides, but the repertoire of molecules required for glial recognition and destruction of Aβ are still unclear. Here, we show that the highly conserved glial engulfment receptor Draper/MEGF10 provides neuroprotection in an AD model of Drosophila (both sexes). Neuronal expression of human Aβ42arc in adult flies results in robust Aβ accumulation, neurodegeneration, locomotor dysfunction, and reduced lifespan. Notably, all of these phenotypes are more severe in draper mutant animals, whereas enhanced expression of glial Draper reverses Aβ accumulation, as well as behavioral phenotypes. We also show that the signal transducer and activator of transcription (Stat92E), c-Jun N-terminal kinase (JNK)/AP-1 signaling, and expression of matrix metalloproteinase-1 (Mmp1) are activated downstream of Draper in glia in response to Aβ42arc exposure. Furthermore, Aβ42-induced upregulation of the phagolysosomal markers Atg8 and p62 was notably reduced in draper mutant flies. Based on our findings, we propose that glia clear neurotoxic Aβ peptides in the AD model Drosophila brain through a Draper/STAT92E/JNK cascade that may be coupled to protein degradation pathways such as autophagy or more traditional phagolysosomal destruction methods.SIGNIFICANCE STATEMENT Alzheimer's disease (AD) and similar dementias are common incurable neurodegenerative disorders in the aging population. As the primary immune responders in the brain, glial cells are implicated as key players in the onset and progression of AD and related disorders. Here we show that the glial engulfment receptor Draper is protective in a Drosophila model of AD, reducing levels of amyloid β (Aβ) peptides, reversing locomotor defects, and extending lifespan. We further show that protein degradation pathways are induced downstream of Draper in AD model flies, supporting a model in which glia engulf and destroy Aβ peptides to reduce amyloid-associated toxicity.
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29
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Nonaka S, Hori A, Nakanishi Y, Kuraishi T. Phagocytosis Assay for Apoptotic Cells in Drosophila Embryos. J Vis Exp 2017. [PMID: 28809832 DOI: 10.3791/56352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The molecular mechanisms underlying the phagocytosis of apoptotic cells need to be elucidated in more detail because of its role in immune and inflammatory intractable diseases. We herein developed an experimental method to investigate phagocytosis quantitatively using the fruit fly Drosophila, in which the gene network controlling engulfment reactions is evolutionally conserved from mammals. In order to accurately detect and count engulfing and un-engulfing phagocytes using whole animals, Drosophila embryos were homogenized to obtain dispersed cells including phagocytes and apoptotic cells. The use of dispersed embryonic cells enables us to measure in vivo phagocytosis levels as if we performed an in vitro phagocytosis assay in which it is possible to observe all phagocytes and apoptotic cells in whole embryos and precisely quantify the level of phagocytosis. We confirmed that this method reproduces those of previous studies that identified the genes required for the phagocytosis of apoptotic cells. This method allows the engulfment of dead cells to be analyzed, and when combined with the powerful genetics of Drosophila, will reveal the complex phagocytic reactions comprised of the migration, recognition, engulfment, and degradation of apoptotic cells by phagocytes.
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Affiliation(s)
- Saori Nonaka
- Graduate School of Medical Sciences, Kanazawa University
| | - Aki Hori
- Graduate School of Medical Sciences, Kanazawa University
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30
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Lin L, Rodrigues FSLM, Kary C, Contet A, Logan M, Baxter RHG, Wood W, Baehrecke EH. Complement-Related Regulates Autophagy in Neighboring Cells. Cell 2017; 170:158-171.e8. [PMID: 28666117 DOI: 10.1016/j.cell.2017.06.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 03/07/2017] [Accepted: 06/13/2017] [Indexed: 11/25/2022]
Abstract
Autophagy degrades cytoplasmic components and is important for development and human health. Although autophagy is known to be influenced by systemic intercellular signals, the proteins that control autophagy are largely thought to function within individual cells. Here, we report that Drosophila macroglobulin complement-related (Mcr), a complement ortholog, plays an essential role during developmental cell death and inflammation by influencing autophagy in neighboring cells. This function of Mcr involves the immune receptor Draper, suggesting a relationship between autophagy and the control of inflammation. Interestingly, Mcr function in epithelial cells is required for macrophage autophagy and migration to epithelial wounds, a Draper-dependent process. This study reveals, unexpectedly, that complement-related from one cell regulates autophagy in neighboring cells via an ancient immune signaling program.
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Affiliation(s)
- Lin Lin
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA; Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, MD 21218, USA
| | - Frederico S L M Rodrigues
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Christina Kary
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Alicia Contet
- Department of Chemistry and Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Mary Logan
- Junger's Center for Neurosciences Research, Department of Neurology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Richard H G Baxter
- Department of Chemistry and Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Will Wood
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Eric H Baehrecke
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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Fujita Y, Maeda T, Kamaishi K, Saito R, Chiba K, Shen X, Zou K, Komano H. Expression of MEGF10 in cholinergic and glutamatergic neurons. Neurosci Lett 2017; 653:25-30. [DOI: 10.1016/j.neulet.2017.05.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/09/2017] [Accepted: 05/15/2017] [Indexed: 02/04/2023]
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Wood W, Martin P. Macrophage Functions in Tissue Patterning and Disease: New Insights from the Fly. Dev Cell 2017; 40:221-233. [PMID: 28171746 PMCID: PMC5300050 DOI: 10.1016/j.devcel.2017.01.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/02/2016] [Accepted: 01/04/2017] [Indexed: 12/19/2022]
Abstract
Macrophages are multifunctional innate immune cells that seed all tissues within the body and play disparate roles throughout development and in adult tissues, both in health and disease. Their complex developmental origins and many of their functions are being deciphered in mammalian tissues, but opportunities for live imaging and the genetic tractability of Drosophila are offering complementary insights into how these fascinating cells integrate a multitude of guidance cues to fulfill their many tasks and migrate to distant sites to either direct developmental patterning or raise an inflammatory response.
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Affiliation(s)
- Will Wood
- Department of Cellular and Molecular Medicine, Biomedical Sciences, University of Bristol, Bristol BS8 1TD, UK.
| | - Paul Martin
- Departments of Biochemistry and Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University of Bristol, Bristol BS8 1TD, UK; School of Medicine, Cardiff University, Cardiff CF14 4XN, UK; Lee Kong Chiang School of Medicine, Nanyang Technological University, Singapore 636921, Singapore.
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Nonaka S, Ando Y, Kanetani T, Hoshi C, Nakai Y, Nainu F, Nagaosa K, Shiratsuchi A, Nakanishi Y. Signaling pathway for phagocyte priming upon encounter with apoptotic cells. J Biol Chem 2017; 292:8059-8072. [PMID: 28325838 DOI: 10.1074/jbc.m116.769745] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 03/12/2017] [Indexed: 12/18/2022] Open
Abstract
The phagocytic elimination of cells undergoing apoptosis is an evolutionarily conserved innate immune mechanism for eliminating unnecessary cells. Previous studies showed an increase in the level of engulfment receptors in phagocytes after the phagocytosis of apoptotic cells, which leads to the enhancement of their phagocytic activity. However, precise mechanisms underlying this phenomenon require further clarification. We found that the pre-incubation of a Drosophila phagocyte cell line with the fragments of apoptotic cells enhanced the subsequent phagocytosis of apoptotic cells, accompanied by an augmented expression of the engulfment receptors Draper and integrin αPS3. The DNA-binding activity of the transcription repressor Tailless was transiently raised in those phagocytes, depending on two partially overlapping signal-transduction pathways for the induction of phagocytosis as well as the occurrence of engulfment. The RNAi knockdown of tailless in phagocytes abrogated the enhancement of both phagocytosis and engulfment receptor expression. Furthermore, the hemocyte-specific RNAi of tailless reduced apoptotic cell clearance in Drosophila embryos. Taken together, we propose the following mechanism for the activation of Drosophila phagocytes after an encounter with apoptotic cells: two partially overlapping signal-transduction pathways for phagocytosis are initiated; transcription repressor Tailless is activated; expression of engulfment receptors is stimulated; and phagocytic activity is enhanced. This phenomenon most likely ensures the phagocytic elimination of apoptotic cells by stimulated phagocytes and is thus considered as a mechanism to prime phagocytes in innate immunity.
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Affiliation(s)
- Saori Nonaka
- From the Graduate School of Medical Sciences and
| | - Yuki Ando
- From the Graduate School of Medical Sciences and
| | | | - Chiharu Hoshi
- School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Yuji Nakai
- the Institute for Food Sciences, Hirosaki University, Aomori, Aomori 038-0012, Japan, and
| | - Firzan Nainu
- From the Graduate School of Medical Sciences and.,the Faculty of Pharmacy, Hasanuddin University, Makassar, South Sulawesi 90245, Indonesia
| | - Kaz Nagaosa
- the Institute for Food Sciences, Hirosaki University, Aomori, Aomori 038-0012, Japan, and
| | | | - Yoshinobu Nakanishi
- From the Graduate School of Medical Sciences and .,School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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34
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Nonaka S, Shiratsuchi A, Nagaosa K, Nakanishi Y. Mechanisms and Significance of Phagocytic Elimination of Cells Undergoing Apoptotic Death. Biol Pharm Bull 2017; 40:1819-1827. [DOI: 10.1248/bpb.b17-00478] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Saori Nonaka
- Graduate School of Medical Sciences, Kanazawa University
| | | | - Kaz Nagaosa
- Graduate School of Medical Sciences, Kanazawa University
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Smith RC, King JG, Tao D, Zeleznik OA, Brando C, Thallinger GG, Dinglasan RR. Molecular Profiling of Phagocytic Immune Cells in Anopheles gambiae Reveals Integral Roles for Hemocytes in Mosquito Innate Immunity. Mol Cell Proteomics 2016; 15:3373-3387. [PMID: 27624304 DOI: 10.1074/mcp.m116.060723] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Indexed: 11/06/2022] Open
Abstract
The innate immune response is highly conserved across all eukaryotes and has been studied in great detail in several model organisms. Hemocytes, the primary immune cell population in mosquitoes, are important components of the mosquito innate immune response, yet critical aspects of their biology have remained uncharacterized. Using a novel method of enrichment, we isolated phagocytic granulocytes and quantified their proteomes by mass spectrometry. The data demonstrate that phagocytosis, blood-feeding, and Plasmodium falciparum infection promote dramatic shifts in the proteomic profiles of An. gambiae granulocyte populations. Of interest, large numbers of immune proteins were induced in response to blood feeding alone, suggesting that granulocytes have an integral role in priming the mosquito immune system for pathogen challenge. In addition, we identify several granulocyte proteins with putative roles as membrane receptors, cell signaling, or immune components that when silenced, have either positive or negative effects on malaria parasite survival. Integrating existing hemocyte transcriptional profiles, we also compare differences in hemocyte transcript and protein expression to provide new insight into hemocyte gene regulation and discuss the potential that post-transcriptional regulation may be an important component of hemocyte gene expression. These data represent a significant advancement in mosquito hemocyte biology, providing the first comprehensive proteomic profiling of mosquito phagocytic granulocytes during homeostasis blood-feeding, and pathogen challenge. Together, these findings extend current knowledge to further illustrate the importance of hemocytes in shaping mosquito innate immunity and their principal role in defining malaria parasite survival in the mosquito host.
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Affiliation(s)
- Ryan C Smith
- From the ‡W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland 21205.,**Department of Entomology, Iowa State University, Ames, Iowa 50011
| | - Jonas G King
- From the ‡W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland 21205.,‡‡Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Starkville, Mississippi 39762
| | - Dingyin Tao
- From the ‡W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland 21205.,§§Division of Pre-clinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20850
| | - Oana A Zeleznik
- §Bioinformatics, Institute for Knowledge Discovery, Graz University of Technology, 8010 Graz, Austria.,¶Core Facility Bioinformatics, Austrian Centre of Industrial Biotechnology, 8010 Graz, Austria.,‖BioTechMed OMICS Center Graz, 8010 Graz, Austria
| | - Clara Brando
- From the ‡W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland 21205
| | - Gerhard G Thallinger
- §Bioinformatics, Institute for Knowledge Discovery, Graz University of Technology, 8010 Graz, Austria.,¶Core Facility Bioinformatics, Austrian Centre of Industrial Biotechnology, 8010 Graz, Austria.,‖BioTechMed OMICS Center Graz, 8010 Graz, Austria
| | - Rhoel R Dinglasan
- From the ‡W. Harry Feinstone Department of Molecular Microbiology and Immunology and the Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, Maryland 21205; .,¶¶Emerging Pathogens Institute, Department of Infectious Diseases & Immunology, University of Florida, Gainesville, Florida 32611
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36
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Gold KS, Brückner K. Macrophages and cellular immunity in Drosophila melanogaster. Semin Immunol 2016; 27:357-68. [PMID: 27117654 DOI: 10.1016/j.smim.2016.03.010] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 01/08/2016] [Indexed: 12/16/2022]
Abstract
The invertebrate Drosophila melanogaster has been a powerful model for understanding blood cell development and immunity. Drosophila is a holometabolous insect, which transitions through a series of life stages from embryo, larva and pupa to adulthood. In spite of this, remarkable parallels exist between Drosophila and vertebrate macrophages, both in terms of development and function. More than 90% of Drosophila blood cells (hemocytes) are macrophages (plasmatocytes), making this highly tractable genetic system attractive for studying a variety of questions in macrophage biology. In vertebrates, recent findings revealed that macrophages have two independent origins: self-renewing macrophages, which reside and proliferate in local microenvironments in a variety of tissues, and macrophages of the monocyte lineage, which derive from hematopoietic stem or progenitor cells. Like vertebrates, Drosophila possesses two macrophage lineages with a conserved dual ontogeny. These parallels allow us to take advantage of the Drosophila model when investigating macrophage lineage specification, maintenance and amplification, and the induction of macrophages and their progenitors by local microenvironments and systemic cues. Beyond macrophage development, Drosophila further serves as a paradigm for understanding the mechanisms underlying macrophage function and cellular immunity in infection, tissue homeostasis and cancer, throughout development and adult life.
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Affiliation(s)
| | - Katja Brückner
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research; Department of Cell and Tissue Biology; Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, United States.
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37
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Nainu F, Tanaka Y, Shiratsuchi A, Nakanishi Y. Protection of Insects against Viral Infection by Apoptosis-Dependent Phagocytosis. THE JOURNAL OF IMMUNOLOGY 2015; 195:5696-706. [PMID: 26546607 DOI: 10.4049/jimmunol.1500613] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 10/14/2015] [Indexed: 11/19/2022]
Abstract
We investigated whether phagocytosis participates in the protection of insects from viral infection using the natural host-virus interaction between Drosophila melanogaster and Drosophila C virus (DCV). Drosophila S2 cells were induced to undergo apoptotic cell death upon DCV infection. However, UV-inactivated virus was unable to cause apoptosis, indicating the need for productive infection for apoptosis induction. S2 cells became susceptible to phagocytosis by hemocyte-derived l(2)mbn cells after viral infection, and the presence of phagocytes in S2 cell cultures reduced viral proliferation. Phagocytosis depended, in part, on caspase activity in S2 cells, as well as the engulfment receptors Draper and integrin βν in phagocytes. To validate the in vivo situation, adult flies were abdominally infected with DCV, followed by the analysis of fly death and viral growth. DCV infection killed flies in a dose-responding manner, and the activation of effector caspases was evident, as revealed by the cleavage of a target protein ectopically expressed in flies. Furthermore, hemocytes isolated from infected flies contained DCV-infected cells, and preinjection of latex beads to inhibit the phagocytic activity of hemocytes accelerated fly death after viral infection. Likewise, viral virulence was exaggerated in flies lacking the engulfment receptors, and was accompanied by the augmented proliferation of virus. Finally, phagocytosis of DCV-infected cells in vitro was inhibited by phosphatidylserine-containing liposome, and virus-infected flies died early when a phosphatidylserine-binding protein was ectopically expressed. Collectively, our study demonstrates that the apoptosis-dependent, phosphatidylserine-mediated phagocytosis of virus-infected cells plays an important role in innate immune responses against viral infection in Drosophila.
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Affiliation(s)
- Firzan Nainu
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; Faculty of Pharmacy, Hasanuddin University, Makassar, South Sulawesi 90245, Indonesia; and
| | - Yumiko Tanaka
- School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Akiko Shiratsuchi
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Yoshinobu Nakanishi
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan; School of Pharmacy, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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Necrotic Cells Actively Attract Phagocytes through the Collaborative Action of Two Distinct PS-Exposure Mechanisms. PLoS Genet 2015; 11:e1005285. [PMID: 26061275 PMCID: PMC4464654 DOI: 10.1371/journal.pgen.1005285] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/14/2015] [Indexed: 11/19/2022] Open
Abstract
Necrosis, a kind of cell death closely associated with pathogenesis and genetic programs, is distinct from apoptosis in both morphology and mechanism. Like apoptotic cells, necrotic cells are swiftly removed from animal bodies to prevent harmful inflammatory and autoimmune responses. In the nematode Caenorhabditis elegans, gain-of-function mutations in certain ion channel subunits result in the excitotoxic necrosis of six touch neurons and their subsequent engulfment and degradation inside engulfing cells. How necrotic cells are recognized by engulfing cells is unclear. Phosphatidylserine (PS) is an important apoptotic-cell surface signal that attracts engulfing cells. Here we observed PS exposure on the surface of necrotic touch neurons. In addition, the phagocytic receptor CED-1 clusters around necrotic cells and promotes their engulfment. The extracellular domain of CED-1 associates with PS in vitro. We further identified a necrotic cell-specific function of CED-7, a member of the ATP-binding cassette (ABC) transporter family, in promoting PS exposure. In addition to CED-7, anoctamin homolog-1 (ANOH-1), the C. elegans homolog of the mammalian Ca(2+)-dependent phospholipid scramblase TMEM16F, plays an independent role in promoting PS exposure on necrotic cells. The combined activities from CED-7 and ANOH-1 ensure efficient exposure of PS on necrotic cells to attract their phagocytes. In addition, CED-8, the C. elegans homolog of mammalian Xk-related protein 8 also makes a contribution to necrotic cell-removal at the first larval stage. Our work indicates that cells killed by different mechanisms (necrosis or apoptosis) expose a common "eat me" signal to attract their phagocytic receptor(s); furthermore, unlike what was previously believed, necrotic cells actively present PS on their outer surfaces through at least two distinct molecular mechanisms rather than leaking out PS passively.
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Draper/CED-1 mediates an ancient damage response to control inflammatory blood cell migration in vivo. Curr Biol 2015; 25:1606-12. [PMID: 26028435 PMCID: PMC4503800 DOI: 10.1016/j.cub.2015.04.037] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 03/16/2015] [Accepted: 04/16/2015] [Indexed: 11/24/2022]
Abstract
Tissue damage leads to a robust and rapid inflammatory response whereby leukocytes are actively drawn toward the wound. Hydrogen peroxide (H2O2) has been shown to be an immediate damage signal essential for the recruitment of these inflammatory blood cells to wound sites in both Drosophila and vertebrates [1, 2]. Recent studies in zebrafish have shown that wound-induced H2O2 is detected by the redox-sensitive Src family kinase (SFK) Lyn within the responding blood cells [3]. Here, we show the same signaling occurs in Drosophila inflammatory cells in response to wound-induced H2O2 with mutants for the Lyn homolog Src42A displaying impaired inflammatory migration to wounds. We go on to show that activation of Src42A is necessary to trigger a signaling cascade within the inflammatory cells involving the ITAM domain-containing protein Draper-I (a member of the CED-1 family of apoptotic cell clearance receptors) and a downstream kinase, Shark, that is required for migration to wounds. The Src42A-Draper-Shark-mediated signaling axis is homologous to the well-established SFK-ITAM-Syk-signaling pathway used in vertebrate adaptive immune responses. Consequently, our results suggest that adaptive immunoreceptor-signaling pathways important in distinguishing self from non-self appear to have evolved from a more-ancient damage response. Furthermore, this changes the role of H2O2 from an inflammatory chemoattractant to an activator signal that primes immune cells to respond to damage cues via the activation of damage receptors such as Draper. Draper works downstream of H2O2 to drive macrophage migration to wounds in Drosophila Draper’s ITAM domain is critically required for migration of macrophages to wounds Draper’s ITAM and NPXY motifs have separable functions in Drosophila macrophages SFK-ITAM-Syk signaling regulates an ancient damage response in Drosophila
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Akagawa H, Hara Y, Togane Y, Iwabuchi K, Hiraoka T, Tsujimura H. The role of the effector caspases drICE and dcp-1 for cell death and corpse clearance in the developing optic lobe in Drosophila. Dev Biol 2015; 404:61-75. [PMID: 26022392 DOI: 10.1016/j.ydbio.2015.05.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 05/13/2015] [Accepted: 05/16/2015] [Indexed: 02/02/2023]
Abstract
In the developing Drosophila optic lobe, cell death occurs via apoptosis and in a distinctive spatio-temporal pattern of dying cell clusters. We analyzed the role of effector caspases drICE and dcp-1 in optic lobe cell death and subsequent corpse clearance using mutants. Neurons in many clusters required either drICE or dcp-1 and each one is sufficient. This suggests that drICE and dcp-1 function in cell death redundantly. However, dying neurons in a few clusters strictly required drICE but not dcp-1, but required drICE and dcp-1 when drICE activity was reduced via hypomorphic mutation. In addition, analysis of the mutants suggests an important role of effecter caspases in corpse clearance. In both null and hypomorphic drICE mutants, greater number of TUNEL-positive cells were observed than in wild type, and many TUNEL-positive cells remained until later stages. Lysotracker staining showed that there was a defect in corpse clearance in these mutants. All the results suggested that drICE plays an important role in activating corpse clearance in dying cells, and that an additional function of effector caspases is required for the activation of corpse clearance as well as that for carrying out cell death.
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Affiliation(s)
- Hiromi Akagawa
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Biological Production Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Yusuke Hara
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Yu Togane
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan
| | - Kikuo Iwabuchi
- Department of Biological Production Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Tsuyoshi Hiraoka
- Department of Biological Production Science, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hidenobu Tsujimura
- Developmental Biology, Tokyo University of Agriculture and Technology, 3-5-8, Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
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41
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Kong Q, Nakai Y, Kuroda N, Shiratsuchi A, Nagaosa K, Nakanishi Y. Peptidoglycan recognition protein-triggered induction of Escherichia coli gene in Drosophila melanogaster. J Biochem 2015; 157:507-17. [DOI: 10.1093/jb/mvv002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 01/07/2015] [Indexed: 11/14/2022] Open
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Kanamori T, Togashi K, Koizumi H, Emoto K. Dendritic Remodeling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:1-25. [DOI: 10.1016/bs.ircmb.2015.05.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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44
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Signaling by the engulfment receptor draper: a screen in Drosophila melanogaster implicates cytoskeletal regulators, Jun N-terminal Kinase, and Yorkie. Genetics 2014; 199:117-34. [PMID: 25395664 DOI: 10.1534/genetics.114.172544] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Draper, the Drosophila melanogaster homolog of the Ced-1 protein of Caenorhabditis elegans, is a cell-surface receptor required for the recognition and engulfment of apoptotic cells, glial clearance of axon fragments and dendritic pruning, and salivary gland autophagy. To further elucidate mechanisms of Draper signaling, we screened chromosomal deficiencies to identify loci that dominantly modify the phenotype of overexpression of Draper isoform II (suppressed differentiation of the posterior crossvein in the wing). We found evidence for 43 genetic modifiers of Draper II. Twenty-four of the 37 suppressor loci and 3 of the 6 enhancer loci were identified. An additional 5 suppressors and 2 enhancers were identified among mutations in functionally related genes. These studies reveal positive contributions to Drpr signaling for the Jun N-terminal Kinase pathway, supported by genetic interactions with hemipterous, basket, jun, and puckered, and for cytoskeleton regulation as indicated by genetic interactions with rac1, rac2, RhoA, myoblast city, Wiskcott-Aldrich syndrome protein, and the formin CG32138, and for yorkie and expanded. These findings indicate that Jun N-terminal Kinase activation and cytoskeletal remodeling collaborate in Draper signaling. Relationships between Draper signaling and Decapentaplegic signaling, insulin signaling, Salvador/Warts/Hippo signaling, apical-basal cell polarity, and cellular responses to mechanical forces are also discussed.
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Estévez-Lao TY, Hillyer JF. Involvement of the Anopheles gambiae Nimrod gene family in mosquito immune responses. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 44:12-22. [PMID: 24200842 DOI: 10.1016/j.ibmb.2013.10.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 06/02/2023]
Abstract
Insects fight infection using a variety of signaling pathways and immune effector proteins. In Drosophila melanogaster, three members of the Nimrod gene family (draper, nimC1 and eater) bind bacteria, and this binding leads to phagocytosis by hemocytes. The Nimrod gene family has since been identified in other insects, but their function in non-drosophilids remains unknown. The purpose of this study was to identify the members of the Nimrod gene family in the malaria mosquito, Anopheles gambiae, and to assess their role in immunity. We identified and sequenced three members of this gene family, herein named draper, nimrod and eater, which are the orthologs of D. melanogaster draper, nimB2 and eater, respectively. The three genes are preferentially expressed in hemocytes and their peak developmental expression is in pupae and young adults. Infection induces the transcriptional upregulation of all three genes, but the magnitude of this upregulation becomes more attenuated as mosquitoes become older. RNAi-based knockdown of eater, but not draper or nimrod, decreased a mosquito's ability to kill Escherichia coli in the hemocoel. Knockdown of draper, eater, or any combination of Nimrod family genes rendered mosquitoes more likely to die from Staphylococcus epidermidis. Finally, knockdown of Nimrod family genes did not impact mRNA levels of the antimicrobial peptides defensin (def1), cecropin (cecA) or gambicin (gam1), but eater knockdown led to a decrease in mRNA levels of nitric oxide synthase. Together, these data show that members of the A. gambiae Nimrod gene family are positive regulators of the mosquito antibacterial response.
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Affiliation(s)
- Tania Y Estévez-Lao
- Department of Biological Sciences, Vanderbilt University, VU Station B 35-1634, Nashville, TN 37235, USA
| | - Julián F Hillyer
- Department of Biological Sciences, Vanderbilt University, VU Station B 35-1634, Nashville, TN 37235, USA.
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46
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Nonaka S, Nagaosa K, Mori T, Shiratsuchi A, Nakanishi Y. Integrin αPS3/βν-mediated phagocytosis of apoptotic cells and bacteria in Drosophila. J Biol Chem 2013; 288:10374-80. [PMID: 23426364 DOI: 10.1074/jbc.m113.451427] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Integrins exert a variety of cellular functions as heterodimers of two transmembrane subunits named α and β. Integrin βν, a β-subunit of Drosophila integrin, is involved in the phagocytosis of apoptotic cells and bacteria. Here, we searched for an α-subunit that forms a complex and cooperates with βν. Examinations of RNAi-treated animals suggested that αPS3, but not any of four other α-subunits, is required for the effective phagocytosis of apoptotic cells in Drosophila embryos. The mutation of αPS3-encoding scb, deficiency, insertion of P-element, or alteration of nucleotide sequences, brought about a reduction in the level of phagocytosis. The defect in phagocytosis by deficiency was reverted by the forced expression of scb. Furthermore, flies in which the expression of both αPS3 and βν was inhibited by RNAi showed a level of phagocytosis almost equal to that observed in flies with RNAi for either subunit alone. A loss of αPS3 also decreased the activity of larval hemocytes in the phagocytosis of Staphylococcus aureus. Finally, a co-immunoprecipitation analysis using a Drosophila cell line treated with a chemical cross-linker suggested a physical association between αPS3 and βν. These results collectively indicated that integrin αPS3/βν serves as a receptor in the phagocytosis of apoptotic cells and bacteria by Drosophila phagocytes.
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Affiliation(s)
- Saori Nonaka
- Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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47
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Tung TT, Nagaosa K, Fujita Y, Kita A, Mori H, Okada R, Nonaka S, Nakanishi Y. Phosphatidylserine recognition and induction of apoptotic cell clearance by Drosophila engulfment receptor Draper. ACTA ACUST UNITED AC 2013; 153:483-91. [DOI: 10.1093/jb/mvt014] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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48
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Tennant I, Pound JD, Marr LA, Willems JJLP, Petrova S, Ford CA, Paterson M, Devitt A, Gregory CD. Innate recognition of apoptotic cells: novel apoptotic cell-associated molecular patterns revealed by crossreactivity of anti-LPS antibodies. Cell Death Differ 2013; 20:698-708. [PMID: 23392124 DOI: 10.1038/cdd.2012.165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cells dying by apoptosis are normally cleared by phagocytes through mechanisms that can suppress inflammation and immunity. Molecules of the innate immune system, the pattern recognition receptors (PRRs), are able to interact not only with conserved structures on microbes (pathogen-associated molecular patterns, PAMPs) but also with ligands displayed by apoptotic cells. We reasoned that PRRs might therefore interact with structures on apoptotic cells - apoptotic cell-associated molecular patterns (ACAMPs) - that are analogous to PAMPs. Here we show that certain monoclonal antibodies raised against the prototypic PAMP, lipopolysaccharide (LPS), can crossreact with apoptotic cells. We demonstrate that one such antibody interacts with a constitutively expressed intracellular protein, laminin-binding protein, which translocates to the cell surface during apoptosis and can interact with cells expressing the prototypic PRR, mCD14 as well as with CD14-negative cells. Anti-LPS cross reactive epitopes on apoptotic cells colocalised with annexin V- and C1q-binding sites on vesicular regions of apoptotic cell surfaces and were released associated with apoptotic cell-derived microvesicles (MVs). These results confirm that apoptotic cells and microbes can interact with the immune system through common elements and suggest that anti-PAMP antibodies could be used strategically to characterise novel ACAMPs associated not only with apoptotic cells but also with derived MVs.
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Affiliation(s)
- I Tennant
- Medical Research Council MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
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49
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Hochreiter-Hufford A, Ravichandran KS. Clearing the dead: apoptotic cell sensing, recognition, engulfment, and digestion. Cold Spring Harb Perspect Biol 2013; 5:a008748. [PMID: 23284042 DOI: 10.1101/cshperspect.a008748] [Citation(s) in RCA: 375] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Clearance of apoptotic cells is the final stage of programmed cell death. Uncleared corpses can become secondarily necrotic, promoting inflammation and autoimmunity. Remarkably, even in tissues with high cellular turnover, apoptotic cells are rarely seen because of efficient clearance mechanisms in healthy individuals. Recently, significant progress has been made in understanding the steps involved in prompt cell clearance in vivo. These include the sensing of corpses via "find me" signals, the recognition of corpses via "eat me" signals and their cognate receptors, the signaling pathways that regulate cytoskeletal rearrangement necessary for engulfment, and the responses of the phagocyte that keep cell clearance events "immunologically silent." This study focuses on our understanding of these steps.
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Affiliation(s)
- Amelia Hochreiter-Hufford
- Department of Microbiology, Immunology and Cancer Biology, Center for Cell Clearance and Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, VA 22908, USA
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50
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Jedi-1 and MEGF10 signal engulfment of apoptotic neurons through the tyrosine kinase Syk. J Neurosci 2012; 32:13022-31. [PMID: 22993420 DOI: 10.1523/jneurosci.6350-11.2012] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
During the development of the peripheral nervous system there is extensive apoptosis, and these neuronal corpses need to be cleared to prevent an inflammatory response. Recently, Jedi-1 and MEGF10, both expressed in glial precursor cells, were identified in mouse as having an essential role in this phagocytosis (Wu et al., 2009); however, the mechanisms by which they promote engulfment remained unknown. Both Jedi-1 and MEGF10 are homologous to the Drosophila melanogaster receptor Draper, which mediates engulfment through activation of the tyrosine kinase Shark. Here, we identify Syk, the mammalian homolog of Shark, as a signal transducer for both Jedi-1 and MEGF10. Syk interacted with each receptor independently through the immunoreceptor tyrosine-based activation motifs (ITAMs) in their intracellular domains. The interaction was enhanced by phosphorylation of the tyrosines in the ITAMs by Src family kinases (SFKs). Jedi association with Syk and activation of the kinase was also induced by exposure to dead cells. Expression of either Jedi-1 or MEGF10 in HeLa cells facilitated engulfment of carboxylated microspheres to a similar extent, and there was no additive effect when they were coexpressed. Mutation of the ITAM tyrosines of Jedi-1 and MEGF10 prevented engulfment. The SFK inhibitor PP2 or a selective Syk inhibitor (BAY 61-3606) also blocked engulfment. Similarly, in cocultures of glial precursors and dying sensory neurons from embryonic mice, addition of PP2 or knock down of endogenous Syk decreased the phagocytosis of apoptotic neurons. These results indicate that both Jedi-1 and MEGF10 can mediate phagocytosis independently through the recruitment of Syk.
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