51
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Melcarne C, Ramond E, Dudzic J, Bretscher AJ, Kurucz É, Andó I, Lemaitre B. Two Nimrod receptors, NimC1 and Eater, synergistically contribute to bacterial phagocytosis in Drosophila melanogaster. FEBS J 2019; 286:2670-2691. [PMID: 30993828 PMCID: PMC6852320 DOI: 10.1111/febs.14857] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/19/2019] [Accepted: 04/15/2019] [Indexed: 12/15/2022]
Abstract
Eater and NimC1 are transmembrane receptors of the Drosophila Nimrod family, specifically expressed in haemocytes, the insect blood cells. Previous ex vivo and in vivoRNAi studies have pointed to their role in the phagocytosis of bacteria. Here, we have created a novel NimC1 null mutant to re-evaluate the role of NimC1, alone or in combination with Eater, in the cellular immune response. We show that NimC1 functions as an adhesion molecule ex vivo, but in contrast to Eater it is not required for haemocyte sessility in vivo. Ex vivo phagocytosis assays and electron microscopy experiments confirmed that Eater is the main phagocytic receptor for Gram-positive, but not Gram-negative bacteria, and contributes to microbe tethering to haemocytes. Surprisingly, NimC1 deletion did not impair phagocytosis of bacteria, nor their adhesion to the haemocytes. However, phagocytosis of both types of bacteria was almost abolished in NimC11 ;eater1 haemocytes. This indicates that both receptors contribute synergistically to the phagocytosis of bacteria, but that Eater can bypass the requirement for NimC1. Finally, we uncovered that NimC1, but not Eater, is essential for uptake of latex beads and zymosan particles. We conclude that Eater and NimC1 are the two main receptors for phagocytosis of bacteria in Drosophila, and that each receptor likely plays distinct roles in microbial uptake.
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Affiliation(s)
- Claudia Melcarne
- Global Health InstituteSchool of Life SciencesÉcole Polytechnique Fédérale de Lausanne (EPFL)Switzerland
| | - Elodie Ramond
- Global Health InstituteSchool of Life SciencesÉcole Polytechnique Fédérale de Lausanne (EPFL)Switzerland
| | - Jan Dudzic
- Global Health InstituteSchool of Life SciencesÉcole Polytechnique Fédérale de Lausanne (EPFL)Switzerland
| | - Andrew J. Bretscher
- Global Health InstituteSchool of Life SciencesÉcole Polytechnique Fédérale de Lausanne (EPFL)Switzerland
| | - Éva Kurucz
- Institute of GeneticsBiological Research Centre of the Hungarian Academy of SciencesSzegedHungary
| | - István Andó
- Institute of GeneticsBiological Research Centre of the Hungarian Academy of SciencesSzegedHungary
| | - Bruno Lemaitre
- Global Health InstituteSchool of Life SciencesÉcole Polytechnique Fédérale de Lausanne (EPFL)Switzerland
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52
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Takahashi S, Ishida A, Kubo A, Kawasaki H, Ochiai S, Nakayama M, Koseki H, Amagai M, Okada T. Homeostatic pruning and activity of epidermal nerves are dysregulated in barrier-impaired skin during chronic itch development. Sci Rep 2019; 9:8625. [PMID: 31197234 PMCID: PMC6565750 DOI: 10.1038/s41598-019-44866-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 05/24/2019] [Indexed: 12/19/2022] Open
Abstract
The epidermal barrier is thought to protect sensory nerves from overexposure to environmental stimuli, and barrier impairment leads to pathological conditions associated with itch, such as atopic dermatitis (AD). However, it is not known how the epidermal barrier continuously protects nerves for the sensory homeostasis during turnover of the epidermis. Here we show that epidermal nerves are contained underneath keratinocyte tight junctions (TJs) in normal human and mouse skin, but not in human AD samples or mouse models of chronic itch caused by epidermal barrier impairment. By intravital imaging of the mouse skin, we found that epidermal nerve endings were frequently extended and retracted, and occasionally underwent local pruning. Importantly, the epidermal nerve pruning took place rapidly at intersections with newly forming TJs in the normal skin, whereas this process was disturbed during chronic itch development. Furthermore, aberrant Ca2+ increases in epidermal nerves were induced in association with the disturbed pruning. Finally, TRPA1 inhibition suppressed aberrant Ca2+ increases in epidermal nerves and itch. These results suggest that epidermal nerve endings are pruned through interactions with keratinocytes to stay below the TJ barrier, and that disruption of this mechanism may lead to aberrant activation of epidermal nerves and pathological itch.
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Affiliation(s)
- Sonoko Takahashi
- Laboratory for Tissue Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan.,Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa, 230-0045, Japan
| | - Azusa Ishida
- Laboratory for Tissue Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan.,Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa, 230-0045, Japan
| | - Akiharu Kubo
- Department of Dermatology, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan.,Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan
| | - Hiroshi Kawasaki
- Department of Dermatology, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan.,Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan.,Disease Biology Group, RIKEN Medical Sciences Innovation Hub Program, Yokohama, Kanagawa, 230-0045, Japan
| | - Sotaro Ochiai
- Laboratory for Tissue Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan
| | - Manabu Nakayama
- Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba, 292-0818, Japan
| | - Haruhiko Koseki
- Disease Biology Group, RIKEN Medical Sciences Innovation Hub Program, Yokohama, Kanagawa, 230-0045, Japan.,Laboratory for Developmental Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan
| | - Masayuki Amagai
- Department of Dermatology, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan.,Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan
| | - Takaharu Okada
- Laboratory for Tissue Dynamics, RIKEN Center for Integrative Medical Sciences, Yokohama, Kanagawa, 230-0045, Japan. .,Graduate School of Medical Life Science, Yokohama City University, Yokohama, Kanagawa, 230-0045, Japan. .,JST, PRESTO, Kawaguchi, Saitama, 332-0012, Japan.
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53
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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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54
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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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55
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Yang WK, Chueh YR, Cheng YJ, Siegenthaler D, Pielage J, Chien CT. Epidermis-Derived L1CAM Homolog Neuroglian Mediates Dendrite Enclosure and Blocks Heteroneuronal Dendrite Bundling. Curr Biol 2019; 29:1445-1459.e3. [PMID: 31006568 DOI: 10.1016/j.cub.2019.03.050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/31/2019] [Accepted: 03/23/2019] [Indexed: 12/31/2022]
Abstract
Building sensory dendritic arbors requires branching, growth, spacing, and substrate support. The conserved L1CAM family of cell-adhesion molecules generates neuronal isoforms to regulate neurite development in various aspects. However, whether non-neuronal isoforms participate in any of these aspects is unclear. In Drosophila, the L1CAM homolog Neuroglian (Nrg) is expressed as two isoforms: the neuronal isoform Nrg180 on dendritic surfaces of dendritic arborization (da) neurons and the non-neuronal isoform Nrg167 in epidermis innervated by dendrites. We found that epidermal Nrg167 encircles dendrites by interactions with dendritic Nrg180 to support dendrite growth, stabilization, and enclosure inside epidermis. Interestingly, whereas Nrg180 forms homophilic interactions to facilitate axonal bundling, heteroneuronal dendrites in the same innervating field avoid bundling through unknown mechanisms to maintain individual dendritic patterns. Here, we show that both epidermal Nrg167 depletion and neuronal Nrg180 overexpression can cause dendrite bundling, with genetic analyses suggesting that Nrg167-Nrg180 interactions antagonize Nrg180-Nrg180 homophilic interaction to prevent dendrite bundling. Furthermore, internalization of Nrg180 also participates in resolving dendrite bundling, as overexpression of endocytosis-defective Nrg180 and compromising endocytosis in neurons both exacerbated dendrite-bundling defects. Together, our study highlights the functional significance of substrate-derived Nrg167 in conferring dendrite stability, positioning, and avoidance.
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Affiliation(s)
- Wei-Kang Yang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ru Chueh
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Ying-Ju Cheng
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Dominique Siegenthaler
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jan Pielage
- Department of Zoology and Neurobiology, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Cheng-Ting Chien
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
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56
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Zhu S, Chen R, Soba P, Jan YN. JNK signaling coordinates with ecdysone signaling to promote pruning of Drosophila sensory neuron dendrites. Development 2019; 146:dev.163592. [PMID: 30936183 DOI: 10.1242/dev.163592] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/25/2019] [Indexed: 12/15/2022]
Abstract
Developmental pruning of axons and dendrites is crucial for the formation of precise neuronal connections, but the mechanisms underlying developmental pruning are not fully understood. Here, we have investigated the function of JNK signaling in dendrite pruning using Drosophila class IV dendritic arborization (c4da) neurons as a model. We find that loss of JNK or its canonical downstream effectors Jun or Fos led to dendrite-pruning defects in c4da neurons. Interestingly, our data show that JNK activity in c4da neurons remains constant from larval to pupal stages but the expression of Fos is specifically activated by ecdysone receptor B1 (EcRB1) at early pupal stages, suggesting that ecdysone signaling provides temporal control of the regulation of dendrite pruning by JNK signaling. Thus, our work not only identifies a novel pathway involved in dendrite pruning and a new downstream target of EcRB1 in c4da neurons, but also reveals that JNK and Ecdysone signaling coordinate to promote dendrite pruning.
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Affiliation(s)
- Sijun Zhu
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA .,Department of Physiology, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 20251, USA
| | - Rui Chen
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Peter Soba
- Department of Physiology, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 20251, USA.,Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, University of Hamburg, Hamburg, Germany
| | - Yuh-Nung Jan
- Department of Physiology, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 20251, USA
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57
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Jiang N, Rasmussen JP, Clanton JA, Rosenberg MF, Luedke KP, Cronan MR, Parker ED, Kim HJ, Vaughan JC, Sagasti A, Parrish JZ. A conserved morphogenetic mechanism for epidermal ensheathment of nociceptive sensory neurites. eLife 2019; 8:42455. [PMID: 30855229 PMCID: PMC6450671 DOI: 10.7554/elife.42455] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 03/08/2019] [Indexed: 12/13/2022] Open
Abstract
Interactions between epithelial cells and neurons influence a range of sensory modalities including taste, touch, and smell. Vertebrate and invertebrate epidermal cells ensheath peripheral arbors of somatosensory neurons, including nociceptors, yet the developmental origins and functional roles of this ensheathment are largely unknown. Here, we describe an evolutionarily conserved morphogenetic mechanism for epidermal ensheathment of somatosensory neurites. We found that somatosensory neurons in Drosophila and zebrafish induce formation of epidermal sheaths, which wrap neurites of different types of neurons to different extents. Neurites induce formation of plasma membrane phosphatidylinositol 4,5-bisphosphate microdomains at nascent sheaths, followed by a filamentous actin network, and recruitment of junctional proteins that likely form autotypic junctions to seal sheaths. Finally, blocking epidermal sheath formation destabilized dendrite branches and reduced nociceptive sensitivity in Drosophila. Epidermal somatosensory neurite ensheathment is thus a deeply conserved cellular process that contributes to the morphogenesis and function of nociceptive sensory neurons. Humans and other animals perceive and interact with the outside world through their sensory nervous system. Nerve cells, acting as the body’s ‘telegraph wires’, convey signals from sensory organs – like the eyes – to the brain, which then processes this information and tells the body how to respond. There are different kinds of sensory nerve cells that carry different types of information, but they all associate closely with the tissues and organs they connect to the brain. Human skin contains sensory nerve cells, which underpin our senses of touch and pain. There is a highly specialized, complex connection between some of these nerve cells and cells in the skin: the skin cells wrap tightly around the nerve cells’ free ends, forming sheath-like structures. This ‘ensheathment’ process happens in a wide range of animals, including those with a backbone, like fish and humans, and those without, like insects. Ensheathment is thought to be important for the skin’s nerve cells to work properly. Yet it remains unclear how or when these connections first appear. Jiang et al. therefore wanted to determine the developmental origins of ensheathment and to find out if these were also similar in animals with and without backbones. Experiments using fruit fly and zebrafish embryos revealed that nerve cells, not skin cells, were responsible for forming and maintaining the sheaths. In embryos where groups of sensory nerve cells were selectively killed – either using a laser or by making the cells produce a toxin – ensheathment did not occur. Further studies, using a variety of microscopy techniques, revealed that the molecular machinery required to stabilize the sheaths was similar in both fish and flies, and therefore likely to be conserved across different groups of animals. Removing sheaths in fly embryos led to nerve cells becoming unstable; the animals were also less sensitive to touch. This confirmed that ensheathment was indeed necessary for sensory nerve cells to work properly. By revealing how ensheathment first emerges, these findings shed new light on how the sensory nervous system develops and how its activity is controlled. In humans, skin cells ensheath the nerve cells responsible for sensing pain. A better understanding of how ensheathments first arise could therefore lead to new avenues for treating chronic pain and related conditions.
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Affiliation(s)
- Nan Jiang
- Department of Biology, University of Washington, Seattle, United States
| | - Jeffrey P Rasmussen
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Joshua A Clanton
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Marci F Rosenberg
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Kory P Luedke
- Department of Biology, University of Washington, Seattle, United States
| | - Mark R Cronan
- Department of Molecular Genetics and Microbiology, Duke University, Durham, United States
| | - Edward D Parker
- Department of Opthalmology, University of Washington, Seattle, United States
| | - Hyeon-Jin Kim
- Department of Chemistry, University of Washington, Seattle, United States.,Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, United States.,Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Alvaro Sagasti
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, United States
| | - Jay Z Parrish
- Department of Biology, University of Washington, Seattle, United States
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58
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Glial ensheathment of the somatodendritic compartment regulates sensory neuron structure and activity. Proc Natl Acad Sci U S A 2019; 116:5126-5134. [PMID: 30804200 DOI: 10.1073/pnas.1814456116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Sensory neurons perceive environmental cues and are important of organismal survival. Peripheral sensory neurons interact intimately with glial cells. While the function of axonal ensheathment by glia is well studied, less is known about the functional significance of glial interaction with the somatodendritic compartment of neurons. Herein, we show that three distinct glia cell types differentially wrap around the axonal and somatodendritic surface of the polymodal dendritic arborization (da) neuron of the Drosophila peripheral nervous system for detection of thermal, mechanical, and light stimuli. We find that glial cell-specific loss of the chromatin modifier gene dATRX in the subperineurial glial layer leads to selective elimination of somatodendritic glial ensheathment, thus allowing us to investigate the function of such ensheathment. We find that somatodendritic glial ensheathment regulates the morphology of the dendritic arbor, as well as the activity of the sensory neuron, in response to sensory stimuli. Additionally, glial ensheathment of the neuronal soma influences dendritic regeneration after injury.
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59
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Tixeira R, Poon IKH. Disassembly of dying cells in diverse organisms. Cell Mol Life Sci 2019; 76:245-257. [PMID: 30317529 PMCID: PMC11105331 DOI: 10.1007/s00018-018-2932-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 09/25/2018] [Accepted: 10/01/2018] [Indexed: 01/09/2023]
Abstract
Programmed cell death (PCD) is a conserved phenomenon in multicellular organisms required to maintain homeostasis. Among the regulated cell death pathways, apoptosis is a well-described form of PCD in mammalian cells. One of the characteristic features of apoptosis is the change in cellular morphology, often leading to the fragmentation of the cell into smaller membrane-bound vesicles through a process called apoptotic cell disassembly. Interestingly, some of these morphological changes and cell disassembly are also noted in cells of other organisms including plants, fungi and protists while undergoing 'apoptosis-like PCD'. This review will describe morphologic features leading to apoptotic cell disassembly, as well as its regulation and function in mammalian cells. The occurrence of cell disassembly during cell death in other organisms namely zebrafish, fly and worm, as well as in other eukaryotic cells will also be discussed.
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Affiliation(s)
- Rochelle Tixeira
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia.
| | - Ivan K H Poon
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, 3086, Australia.
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60
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Pei J, Kinch LN, Grishin NV. FlyXCDB—A Resource for Drosophila Cell Surface and Secreted Proteins and Their Extracellular Domains. J Mol Biol 2018; 430:3353-3411. [DOI: 10.1016/j.jmb.2018.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/31/2018] [Accepted: 06/02/2018] [Indexed: 02/06/2023]
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61
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Differential Requirement for Translation Initiation Factor Pathways during Ecdysone-Dependent Neuronal Remodeling in Drosophila. Cell Rep 2018; 24:2287-2299.e4. [DOI: 10.1016/j.celrep.2018.07.074] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 06/22/2018] [Accepted: 07/23/2018] [Indexed: 11/23/2022] Open
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62
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Lancaster CE, Ho CY, Hipolito VEB, Botelho RJ, Terebiznik MR. Phagocytosis: what's on the menu? 1. Biochem Cell Biol 2018; 97:21-29. [PMID: 29791809 DOI: 10.1139/bcb-2018-0008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phagocytosis is an evolutionarily conserved process. In Protozoa, phagocytosis fulfills a feeding mechanism, while in Metazoa, phagocytosis diversified to play multiple organismal roles, including immune defence, tissue homeostasis, and remodeling. Accordingly, phagocytes display a high level of plasticity in their capacity to recognize, engulf, and process targets that differ in composition and morphology. Here, we review how phagocytosis adapts to its multiple roles and discuss in particular the effect of target morphology in phagocytic uptake and phagosome maturation.
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Affiliation(s)
- Charlene E Lancaster
- a Department of Biological Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada.,b Department of Cell and System Biology, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
| | - Cheuk Y Ho
- a Department of Biological Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
| | - Victoria E B Hipolito
- c Molecular Science Graduate Program, Ryerson University, Toronto, ON M5B 2K3, Canada.,d Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Roberto J Botelho
- c Molecular Science Graduate Program, Ryerson University, Toronto, ON M5B 2K3, Canada.,d Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - Mauricio R Terebiznik
- a Department of Biological Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada.,b Department of Cell and System Biology, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
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63
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Jin EJ, Kiral FR, Hiesinger PR. The where, what, and when of membrane protein degradation in neurons. Dev Neurobiol 2018; 78:283-297. [PMID: 28884504 PMCID: PMC5816708 DOI: 10.1002/dneu.22534] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/01/2017] [Accepted: 09/04/2017] [Indexed: 12/20/2022]
Abstract
Membrane protein turnover and degradation are required for the function and health of all cells. Neurons may live for the entire lifetime of an organism and are highly polarized cells with spatially segregated axonal and dendritic compartments. Both longevity and morphological complexity represent challenges for regulated membrane protein degradation. To investigate how neurons cope with these challenges, an increasing number of recent studies investigated local, cargo-specific protein sorting, and degradation at axon terminals and in dendritic processes. In this review, we explore the current answers to the ensuing questions of where, what, and when membrane proteins are degraded in neurons. © 2017 The Authors Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 78: 283-297, 2018.
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Affiliation(s)
- Eugene Jennifer Jin
- Division of NeurobiologyInstitute for Biology, Freie Universität Berlin14195 BerlinGermany
- Graduate School of Biomedical SciencesUniversity of Texas Southwestern Medical CenterDallasTX75390USA
| | - Ferdi Ridvan Kiral
- Division of NeurobiologyInstitute for Biology, Freie Universität Berlin14195 BerlinGermany
| | - Peter Robin Hiesinger
- Division of NeurobiologyInstitute for Biology, Freie Universität Berlin14195 BerlinGermany
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64
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Herzmann S, Götzelmann I, Reekers LF, Rumpf S. Spatial regulation of microtubule disruption during dendrite pruning in Drosophila. Development 2018; 145:dev.156950. [DOI: 10.1242/dev.156950] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 04/18/2018] [Indexed: 11/20/2022]
Abstract
Large scale neurite pruning is an important specificity mechanism during neuronal morphogenesis. Drosophila sensory neurons prune their larval dendrites during metamorphosis. Pruning dendrites are severed in their proximal regions, but how this spatial information is encoded is not clear. Dendrite severing is preceded by local breakdown of dendritic microtubules through PAR-1-mediated inhibition of Tau. Here, we investigated spatial aspects of microtubule breakdown during dendrite pruning. Live imaging of fluorescently tagged tubulin shows that microtubule breakdown first occurs at proximal dendritic branchpoints, followed by breakdown at more distal branchpoints, suggesting that the process is triggered by a signal emanating from the soma. In fly dendrites, microtubules are arranged in uniformly oriented arrays where all plus ends face towards the soma. Mutants in kinesin-1 and -2, which are required for uniform microtubule orientation, cause defects in microtubule breakdown and dendrite pruning. Our data suggest that the local microtubule organization at branch points determines where microtubule breakdown occurs. Local microtubule organization may therefore contribute spatial information for severing sites during dendrite pruning.
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Affiliation(s)
- Svende Herzmann
- Insitute for Neurobiology, University of Münster, Badestrasse 9, 48149 Münster, Germany
| | - Ina Götzelmann
- Insitute for Neurobiology, University of Münster, Badestrasse 9, 48149 Münster, Germany
| | - Lea-Franziska Reekers
- Insitute for Neurobiology, University of Münster, Badestrasse 9, 48149 Münster, Germany
| | - Sebastian Rumpf
- Insitute for Neurobiology, University of Münster, Badestrasse 9, 48149 Münster, Germany
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65
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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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66
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Dendritic space-filling requires a neuronal type-specific extracellular permissive signal in Drosophila. Proc Natl Acad Sci U S A 2017; 114:E8062-E8071. [PMID: 28874572 DOI: 10.1073/pnas.1707467114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurons sometimes completely fill available space in their receptive fields with evenly spaced dendrites to uniformly sample sensory or synaptic information. The mechanisms that enable neurons to sense and innervate all space in their target tissues are poorly understood. Using Drosophila somatosensory neurons as a model, we show that heparan sulfate proteoglycans (HSPGs) Dally and Syndecan on the surface of epidermal cells act as local permissive signals for the dendritic growth and maintenance of space-filling nociceptive C4da neurons, allowing them to innervate the entire skin. Using long-term time-lapse imaging with intact Drosophila larvae, we found that dendrites grow into HSPG-deficient areas but fail to stay there. HSPGs are necessary to stabilize microtubules in newly formed high-order dendrites. In contrast to C4da neurons, non-space-filling sensory neurons that develop in the same microenvironment do not rely on HSPGs for their dendritic growth. Furthermore, HSPGs do not act by transporting extracellular diffusible ligands or require leukocyte antigen-related (Lar), a receptor protein tyrosine phosphatase (RPTP) and the only known Drosophila HSPG receptor, for promoting dendritic growth of space-filling neurons. Interestingly, another RPTP, Ptp69D, promotes dendritic growth of C4da neurons in parallel to HSPGs. Together, our data reveal an HSPG-dependent pathway that specifically allows dendrites of space-filling neurons to innervate all target tissues in Drosophila.
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67
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Rode S, Ohm H, Zipfel J, Rumpf S. The spliceosome-associated protein Mfap1 binds to VCP in Drosophila. PLoS One 2017; 12:e0183733. [PMID: 28837687 PMCID: PMC5570293 DOI: 10.1371/journal.pone.0183733] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 08/09/2017] [Indexed: 12/14/2022] Open
Abstract
Posttranscriptional regulation of gene expression contributes to many developmental transitions. Previously, we found that the AAA chaperone Valosin-Containing Protein (VCP) regulates ecdysone-dependent dendrite pruning of Drosophila class IV dendritic arborization (c4da) neurons via an effect on RNA metabolism. In a search for RNA binding proteins associated with VCP, we identified the spliceosome-associated protein Mfap1, a component of the tri-snRNP complex. Mfap1 is a nucleolar protein in neurons and its levels are regulated by VCP. Mfap1 binds to VCP and TDP-43, a disease-associated RNA-binding protein. via distinct regions in its N- and C-terminal halfs. Similar to vcp mutations, Mfap1 overexpression causes c4da neuron dendrite pruning defects and mislocalization of TDP-43 in these cells, but genetic analyses show that Mfap1 is not a crucial VCP target during dendrite pruning. Finally, rescue experiments with a lethal mfap1 mutant show that the VCP binding region is not essential for Mfap1 function, but may act to increase its stability or activity.
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Affiliation(s)
- Sandra Rode
- Institute for Neurobiology, University of Münster, Badestrasse 9, Münster, Germany
| | - Henrike Ohm
- Institute for Neurobiology, University of Münster, Badestrasse 9, Münster, Germany
| | - Jaqueline Zipfel
- Institute for Neurobiology, University of Münster, Badestrasse 9, Münster, Germany
| | - Sebastian Rumpf
- Institute for Neurobiology, University of Münster, Badestrasse 9, Münster, Germany
- * E-mail:
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68
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Wingen A, Carrera P, Ekaterini Psathaki O, Voelzmann A, Paululat A, Hoch M. Debris buster is a Drosophila scavenger receptor essential for airway physiology. Dev Biol 2017; 430:52-68. [PMID: 28821389 DOI: 10.1016/j.ydbio.2017.08.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 01/01/2023]
Abstract
Scavenger receptors class B (SR-B) are multifunctional transmembrane proteins, which in vertebrates participate in lipid transport, pathogen clearance, lysosomal delivery and intracellular sorting. Drosophila has 14 SR-B members whose functions are still largely unknown. Here, we reveal a novel role for the SR-B family member Debris buster (Dsb) in Drosophila airway physiology. Larvae lacking dsb show yeast avoidance behavior, hypoxia, and severe growth defects associated with impaired elongation and integrity along the airways. Furthermore, in dsb mutant embryos, the barrier function of the posterior spiracles, which are critical for gas exchange, is not properly established and liquid clearance is locally impaired at the spiracular lumen. We found that Dsb is specifically expressed in a group of distal epithelial cells of the posterior spiracle organ and not throughout the entire airways. Furthermore, tissue-specific knockdown and rescue experiments demonstrate that Dsb function in the airways is only required in the posterior spiracles. Dsb localizes in intracellular vesicles, and a subset of these associate with lysosomes. However, we found that depletion of proteins involved in vesicular transport to the apical membrane, but not in lysosomal function, causes dsb-like airway elongation defects. We propose a model in which Dsb sorts components of the apical extracellular matrix which are essential for airway physiology. Since SR-B LIMP2-deficient mice show reduced expression of several apical plasma membrane proteins, sorting of proteins to the apical membrane is likely an evolutionary conserved function of Dsb and LIMP2. Our data provide insights into a spatially confined function of the SR-B Dsb in intracellular trafficking critical for the physiology of the whole tubular airway network.
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Affiliation(s)
- Almut Wingen
- Developmental Genetic&Molecular Physiology Unit, Life&Medical Sciences Institute (LIMES), University of Bonn, Carl-Troll-Strasse 31, D-53115 Bonn, Germany
| | - Pilar Carrera
- Developmental Genetic&Molecular Physiology Unit, Life&Medical Sciences Institute (LIMES), University of Bonn, Carl-Troll-Strasse 31, D-53115 Bonn, Germany.
| | - Olympia Ekaterini Psathaki
- Department of Zoology and Developmental Biology, University of Osnabrück, Barbarastrasse 11, D-49076 Osnabrück, Germany; EM Unit, University of Osnabrück, Barbarastrasse 11, D-49076 Osnabrück, Germany
| | - André Voelzmann
- Developmental Genetic&Molecular Physiology Unit, Life&Medical Sciences Institute (LIMES), University of Bonn, Carl-Troll-Strasse 31, D-53115 Bonn, Germany
| | - Achim Paululat
- Department of Zoology and Developmental Biology, University of Osnabrück, Barbarastrasse 11, D-49076 Osnabrück, Germany
| | - Michael Hoch
- Developmental Genetic&Molecular Physiology Unit, Life&Medical Sciences Institute (LIMES), University of Bonn, Carl-Troll-Strasse 31, D-53115 Bonn, Germany.
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69
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Herzmann S, Krumkamp R, Rode S, Kintrup C, Rumpf S. PAR-1 promotes microtubule breakdown during dendrite pruning in Drosophila. EMBO J 2017; 36:1981-1991. [PMID: 28554895 DOI: 10.15252/embj.201695890] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 04/21/2017] [Accepted: 04/26/2017] [Indexed: 11/09/2022] Open
Abstract
Pruning of unspecific neurites is an important mechanism during neuronal morphogenesis. Drosophila sensory neurons prune their dendrites during metamorphosis. Pruning dendrites are severed in their proximal regions. Prior to severing, dendritic microtubules undergo local disassembly, and dendrites thin extensively through local endocytosis. Microtubule disassembly requires a katanin homologue, but the signals initiating microtubule breakdown are not known. Here, we show that the kinase PAR-1 is required for pruning and dendritic microtubule breakdown. Our data show that neurons lacking PAR-1 fail to break down dendritic microtubules, and PAR-1 is required for an increase in neuronal microtubule dynamics at the onset of metamorphosis. Mammalian PAR-1 is a known Tau kinase, and genetic interactions suggest that PAR-1 promotes microtubule breakdown largely via inhibition of Tau also in Drosophila Finally, PAR-1 is also required for dendritic thinning, suggesting that microtubule breakdown might precede ensuing plasma membrane alterations. Our results shed light on the signaling cascades and epistatic relationships involved in neurite destabilization during dendrite pruning.
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Affiliation(s)
- Svende Herzmann
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Rafael Krumkamp
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Sandra Rode
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Carina Kintrup
- Institute for Neurobiology, University of Münster, Münster, Germany
| | - Sebastian Rumpf
- Institute for Neurobiology, University of Münster, Münster, Germany
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70
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Thompson-Peer KL, DeVault L, Li T, Jan LY, Jan YN. In vivo dendrite regeneration after injury is different from dendrite development. Genes Dev 2017; 30:1776-89. [PMID: 27542831 PMCID: PMC5002981 DOI: 10.1101/gad.282848.116] [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: 04/18/2016] [Accepted: 07/25/2016] [Indexed: 12/22/2022]
Abstract
Thompson-Peer et al. show that, in intact Drosophila larvae, a discrete injury that removes all dendrites induces robust dendritic growth that recreates many features of uninjured dendrites. However, the growth and patterning of injury-induced dendrites is significantly different from uninjured dendrites. Neurons receive information along dendrites and send signals along axons to synaptic contacts. The factors that control axon regeneration have been examined in many systems, but dendrite regeneration has been largely unexplored. Here we report that, in intact Drosophila larvae, a discrete injury that removes all dendrites induces robust dendritic growth that recreates many features of uninjured dendrites, including the number of dendrite branches that regenerate and responsiveness to sensory stimuli. However, the growth and patterning of injury-induced dendrites is significantly different from uninjured dendrites. We found that regenerated arbors cover much less territory than uninjured neurons, fail to avoid crossing over other branches from the same neuron, respond less strongly to mechanical stimuli, and are pruned precociously. Finally, silencing the electrical activity of the neurons specifically blocks injury-induced, but not developmental, dendrite growth. By elucidating the essential features of dendrites grown in response to acute injury, our work builds a framework for exploring dendrite regeneration in physiological and pathological conditions.
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Affiliation(s)
- Katherine L Thompson-Peer
- Howard Hughes Medical Institute, Department of Physiology, Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Laura DeVault
- Howard Hughes Medical Institute, Department of Physiology, Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Tun Li
- Howard Hughes Medical Institute, Department of Physiology, Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Lily Yeh Jan
- Howard Hughes Medical Institute, Department of Physiology, Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, Department of Physiology, Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
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71
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Howick VM, Lazzaro BP. The genetic architecture of defence as resistance to and tolerance of bacterial infection in Drosophila melanogaster. Mol Ecol 2017; 26:1533-1546. [PMID: 28099780 DOI: 10.1111/mec.14017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 12/17/2022]
Abstract
Defence against pathogenic infection can take two forms: resistance and tolerance. Resistance is the ability of the host to limit a pathogen burden, whereas tolerance is the ability to limit the negative consequences of infection at a given level of infection intensity. Evolutionarily, a tolerance strategy that is independent of resistance could allow the host to avoid mounting a costly immune response and, theoretically, to avoid a co-evolutionary arms race between pathogen virulence and host resistance. Biomedically, understanding the mechanisms of tolerance and how they relate to resistance could potentially yield treatment strategies that focus on health improvement instead of pathogen elimination. To understand the impact of tolerance on host defence and identify genetic variants that determine host tolerance, we defined genetic variation in tolerance as the residual deviation from a binomial regression of fitness under infection against infection intensity. We then performed a genomewide association study to map the genetic basis of variation in resistance to and tolerance of infection by the bacterium Providencia rettgeri. We found a positive genetic correlation between resistance and tolerance, and we demonstrated that the level of resistance is highly predictive of tolerance. We identified 30 loci that predict tolerance, many of which are in genes involved in the regulation of immunity and metabolism. We used RNAi to confirm that a subset of mapped genes have a role in defence, including putative wound repair genes grainy head and debris buster. Our results indicate that tolerance is not an independent strategy from resistance, but that defence arises from a collection of physiological processes intertwined with canonical immunity and resistance.
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Affiliation(s)
- Virginia M Howick
- Department of Entomology, Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Comstock Hall, Ithaca, NY, 14853, USA
| | - Brian P Lazzaro
- Department of Entomology, Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Comstock Hall, Ithaca, NY, 14853, USA
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72
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Tsuyama T, Tsubouchi A, Usui T, Imamura H, Uemura T. Mitochondrial dysfunction induces dendritic loss via eIF2α phosphorylation. J Cell Biol 2017; 216:815-834. [PMID: 28209644 PMCID: PMC5346966 DOI: 10.1083/jcb.201604065] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 11/30/2016] [Accepted: 01/19/2017] [Indexed: 12/25/2022] Open
Abstract
Mitochondrial dysfunction is associated with neuropathological events, but how it mediates loss of specific neuronal subtypes is unclear. Tsuyama et al. show that mitochondrial dysfunction triggers selective dendritic loss in class IV arborization neurons in a manner dependent on eIF2α phosphorylation and translation inhibition. Mitochondria are key contributors to the etiology of diseases associated with neuromuscular defects or neurodegeneration. How changes in cellular metabolism specifically impact neuronal intracellular processes and cause neuropathological events is still unclear. We here dissect the molecular mechanism by which mitochondrial dysfunction induced by Prel aberrant function mediates selective dendritic loss in Drosophila melanogaster class IV dendritic arborization neurons. Using in vivo ATP imaging, we found that neuronal cellular ATP levels during development are not correlated with the progression of dendritic loss. We searched for mitochondrial stress signaling pathways that induce dendritic loss and found that mitochondrial dysfunction is associated with increased eIF2α phosphorylation, which is sufficient to induce dendritic pathology in class IV arborization neurons. We also observed that eIF2α phosphorylation mediates dendritic loss when mitochondrial dysfunction results from other genetic perturbations. Furthermore, mitochondrial dysfunction induces translation repression in class IV neurons in an eIF2α phosphorylation-dependent manner, suggesting that differential translation attenuation among neuron subtypes is a determinant of preferential vulnerability.
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Affiliation(s)
- Taiichi Tsuyama
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Asako Tsubouchi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tadao Usui
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Hiromi Imamura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Tadashi Uemura
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
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73
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Bashir H, Seykora JT, Lee V. Invisible Shield: Review of the Corneal Epithelium as a Barrier to UV Radiation, Pathogens, and Other Environmental Stimuli. J Ophthalmic Vis Res 2017; 12:305-311. [PMID: 28791065 PMCID: PMC5525501 DOI: 10.4103/jovr.jovr_114_17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The ocular surface is comprised of the cornea and conjunctiva, which are structures that not only protect the eye but also enable vision. The corneal epithelium is the most superficial layer of the cornea, and therefore first line of defense against external assaults. Damage to this highly specialized structure could lead to vision loss, making it an important structure to investigate and understand. Here, we conducted a search of the current literature on the mechanisms the corneal epithelium has adapted against three frequent insults: UV-radiation, pathogens, and environmental assaults. This review systematically examines the corneal epithelium's response to each assault in order to maintain its role as an invisible shield. The goal of this review is to provide insight into some of the critical functions the corneal epithelium performs that may be valuable to current regenerative studies.
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Affiliation(s)
- Hasan Bashir
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, USA
| | - John T Seykora
- Department of Dermatology, University of Pennsylvania, Philadelphia, USA
| | - Vivian Lee
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, USA.,Department of Dermatology, University of Pennsylvania, Philadelphia, USA
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74
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Heppert JK, Goldstein B. Remodelling germ cells by intercellular cannibalism. Nat Cell Biol 2016; 18:1267-1268. [PMID: 27897161 DOI: 10.1038/ncb3449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Work from the early 1980s reported strange lobes protruding from Caenorhabditis elegans germ cell precursors. However, the fate and potential significance of these lobes remained unexplored for decades. Now, neighbouring endodermal cells are shown to sever and digest these lobes, in an unexpected process of 'intercellular cannibalism', which could play an important part in regulating primordial germ cells.
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Affiliation(s)
- Jennifer K Heppert
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Bob Goldstein
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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75
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Developmentally programmed germ cell remodelling by endodermal cell cannibalism. Nat Cell Biol 2016; 18:1302-1310. [PMID: 27842058 PMCID: PMC5129868 DOI: 10.1038/ncb3439] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 10/13/2016] [Indexed: 02/06/2023]
Abstract
Primordial germ cells (PGCs) in many species associate intimately with endodermal cells, but the significance of such interactions is largely unexplored. Here, we show that Caenorhabditis elegans PGCs form lobes that are removed and digested by endodermal cells, dramatically altering PGC size and mitochondrial content. We demonstrate that endodermal cells do not scavenge lobes PGCs shed, but rather, actively remove lobes from the cell body. CED-10 (Rac)-induced actin, DYN-1 (dynamin) and LST-4 (SNX9) transiently surround lobe necks and are required within endodermal cells for lobe scission, suggesting that scission occurs through a mechanism resembling vesicle endocytosis. These findings reveal an unexpected role for endoderm in altering the contents of embryonic PGCs, and define a form of developmentally programmed cell remodelling involving intercellular cannibalism. Active roles for engulfing cells have been proposed in several neuronal remodelling events, suggesting that intercellular cannibalism may be a more widespread method used to shape cells than previously thought.
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76
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Tenenbaum CM, Gavis ER. Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells. J Vis Exp 2016. [PMID: 27842373 DOI: 10.3791/54670] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in communication with the epidermal cells they innervate and thus their analysis benefits from in situ visualization of both neuronally and epidermally expressed proteins by immunofluorescence. Traditional methods of preparing larval fillets for immunofluorescence experiments leave intact the muscle tissue that covers most of the body wall, presenting several challenges to imaging neuronal and epidermal proteins. Here we describe a method for removing muscle tissue from Drosophila larval fillets. This protocol enables imaging of proteins that are otherwise obscured by muscle tissue, improves signal to noise ratio, and facilitates the use of super-resolution microscopy to study da neuron development.
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77
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Guillou A, Troha K, Wang H, Franc NC, Buchon N. The Drosophila CD36 Homologue croquemort Is Required to Maintain Immune and Gut Homeostasis during Development and Aging. PLoS Pathog 2016; 12:e1005961. [PMID: 27780230 PMCID: PMC5079587 DOI: 10.1371/journal.ppat.1005961] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 09/29/2016] [Indexed: 12/11/2022] Open
Abstract
Phagocytosis is an ancient mechanism central to both tissue homeostasis and immune defense. Both the identity of the receptors that mediate bacterial phagocytosis and the nature of the interactions between phagocytosis and other defense mechanisms remain elusive. Here, we report that Croquemort (Crq), a Drosophila member of the CD36 family of scavenger receptors, is required for microbial phagocytosis and efficient bacterial clearance. Flies mutant for crq are susceptible to environmental microbes during development and succumb to a variety of microbial infections as adults. Crq acts parallel to the Toll and Imd pathways to eliminate bacteria via phagocytosis. crq mutant flies exhibit enhanced and prolonged immune and cytokine induction accompanied by premature gut dysplasia and decreased lifespan. The chronic state of immune activation in crq mutant flies is further regulated by negative regulators of the Imd pathway. Altogether, our data demonstrate that Crq plays a key role in maintaining immune and organismal homeostasis.
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Affiliation(s)
- Aurélien Guillou
- Department of Entomology, Cornell University, Ithaca, NY, United States Of America
| | - Katia Troha
- Department of Entomology, Cornell University, Ithaca, NY, United States Of America
| | - Hui Wang
- Department of Cell & Molecular Biology, The Scripps Research Institute, La Jolla, CA, United States Of America
| | - Nathalie C. Franc
- Department of Cell & Molecular Biology, The Scripps Research Institute, La Jolla, CA, United States Of America
| | - Nicolas Buchon
- Department of Entomology, Cornell University, Ithaca, NY, United States Of America
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78
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Timmons AK, Mondragon AA, Meehan TL, McCall K. Control of non-apoptotic nurse cell death by engulfment genes in Drosophila. Fly (Austin) 2016; 11:104-111. [PMID: 27686122 DOI: 10.1080/19336934.2016.1238993] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Programmed cell death occurs as a normal part of oocyte development in Drosophila. For each egg that is formed, 15 germline-derived nurse cells transfer their cytoplasmic contents into the oocyte and die. Disruption of apoptosis or autophagy only partially inhibits the death of the nurse cells, indicating that other mechanisms significantly contribute to nurse cell death. Recently, we demonstrated that the surrounding stretch follicle cells non-autonomously promote nurse cell death during late oogenesis and that phagocytosis genes including draper, ced-12, and the JNK pathway are crucial for this process. When phagocytosis genes are inhibited in the follicle cells, events specifically associated with death of the nurse cells are impaired. Death of the nurse cells is not completely blocked in draper mutants, suggesting that other engulfment receptors are involved. Indeed, we found that the integrin subunit, αPS3, is enriched on stretch follicle cells during late oogenesis and is required for elimination of the nurse cells. Moreover, double mutant analysis revealed that integrins act in parallel to draper. Death of nurse cells in the Drosophila ovary is a unique example of programmed cell death that is both non-apoptotic and non-cell autonomously controlled.
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Affiliation(s)
| | | | - Tracy L Meehan
- a Department of Biology , Boston University , Boston , MA
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79
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Yaniv SP, Schuldiner O. A fly's view of neuronal remodeling. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2016; 5:618-35. [PMID: 27351747 PMCID: PMC5086085 DOI: 10.1002/wdev.241] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 04/10/2016] [Accepted: 04/18/2016] [Indexed: 11/17/2022]
Abstract
Developmental neuronal remodeling is a crucial step in sculpting the final and mature brain connectivity in both vertebrates and invertebrates. Remodeling includes degenerative events, such as neurite pruning, that may be followed by regeneration to form novel connections during normal development. Drosophila provides an excellent model to study both steps of remodeling since its nervous system undergoes massive and stereotypic remodeling during metamorphosis. Although pruning has been widely studied, our knowledge of the molecular and cellular mechanisms is far from complete. Our understanding of the processes underlying regrowth is even more fragmentary. In this review, we discuss recent progress by focusing on three groups of neurons that undergo stereotypic pruning and regrowth during metamorphosis, the mushroom body γ neurons, the dendritic arborization neurons and the crustacean cardioactive peptide peptidergic neurons. By comparing and contrasting the mechanisms involved in remodeling of these three neuronal types, we highlight the common themes and differences as well as raise key questions for future investigation in the field. WIREs Dev Biol 2016, 5:618–635. doi: 10.1002/wdev.241 For further resources related to this article, please visit the WIREs website
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Affiliation(s)
- Shiri P Yaniv
- Dept of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Oren Schuldiner
- Dept of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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80
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Meehan TL, Joudi TF, Timmons AK, Taylor JD, Habib CS, Peterson JS, Emmanuel S, Franc NC, McCall K. Components of the Engulfment Machinery Have Distinct Roles in Corpse Processing. PLoS One 2016; 11:e0158217. [PMID: 27347682 PMCID: PMC4922577 DOI: 10.1371/journal.pone.0158217] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 06/13/2016] [Indexed: 01/10/2023] Open
Abstract
Billions of cells die in our bodies on a daily basis and are engulfed by phagocytes. Engulfment, or phagocytosis, can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification. In this study, we focus on the last two steps, which can collectively be considered corpse processing, in which the engulfed material is degraded. We use the Drosophila ovarian follicle cells as a model for engulfment of apoptotic cells by epithelial cells. We show that engulfed material is processed using the canonical corpse processing pathway involving the small GTPases Rab5 and Rab7. The phagocytic receptor Draper is present on the phagocytic cup and on nascent, phosphatidylinositol 3-phosphate (PI(3)P)- and Rab7-positive phagosomes, whereas integrins are maintained on the cell surface during engulfment. Due to the difference in subcellular localization, we investigated the role of Draper, integrins, and downstream signaling components in corpse processing. We found that some proteins were required for internalization only, while others had defects in corpse processing as well. This suggests that several of the core engulfment proteins are required for distinct steps of engulfment. We also performed double mutant analysis and found that combined loss of draper and αPS3 still resulted in a small number of engulfed vesicles. Therefore, we investigated another known engulfment receptor, Crq. We found that loss of all three receptors did not inhibit engulfment any further, suggesting that Crq does not play a role in engulfment by the follicle cells. A more complete understanding of how the engulfment and corpse processing machinery interact may enable better understanding and treatment of diseases associated with defects in engulfment by epithelial cells.
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Affiliation(s)
- Tracy L. Meehan
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- * E-mail: (KM); (TM)
| | - Tony F. Joudi
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Allison K. Timmons
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Jeffrey D. Taylor
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Corey S. Habib
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Jeanne S. Peterson
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Shanan Emmanuel
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
| | - Nathalie C. Franc
- The Scripps Research Institute, Department of Immunology and Microbial Science, La Jolla, California, United States of America
| | - Kimberly McCall
- Department of Biology, Boston University, Boston, Massachusetts, United States of America
- * E-mail: (KM); (TM)
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81
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Gomez-Diaz C, Bargeton B, Abuin L, Bukar N, Reina JH, Bartoi T, Graf M, Ong H, Ulbrich MH, Masson JF, Benton R. A CD36 ectodomain mediates insect pheromone detection via a putative tunnelling mechanism. Nat Commun 2016; 7:11866. [PMID: 27302750 PMCID: PMC4912623 DOI: 10.1038/ncomms11866] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/07/2016] [Indexed: 01/09/2023] Open
Abstract
CD36 transmembrane proteins have diverse roles in lipid uptake, cell adhesion and pathogen sensing. Despite numerous in vitro studies, how they act in native cellular contexts is poorly understood. A Drosophila CD36 homologue, sensory neuron membrane protein 1 (SNMP1), was previously shown to facilitate detection of lipid-derived pheromones by their cognate receptors in olfactory cilia. Here we investigate how SNMP1 functions in vivo. Structure-activity dissection demonstrates that SNMP1's ectodomain is essential, but intracellular and transmembrane domains dispensable, for cilia localization and pheromone-evoked responses. SNMP1 can be substituted by mammalian CD36, whose ectodomain can interact with insect pheromones. Homology modelling, using the mammalian LIMP-2 structure as template, reveals a putative tunnel in the SNMP1 ectodomain that is sufficiently large to accommodate pheromone molecules. Amino-acid substitutions predicted to block this tunnel diminish pheromone sensitivity. We propose a model in which SNMP1 funnels hydrophobic pheromones from the extracellular fluid to integral membrane receptors.
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Affiliation(s)
- Carolina Gomez-Diaz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Benoîte Bargeton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Liliane Abuin
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Natalia Bukar
- Centre for Self-Assembled Chemical Structures (CSACS), McGill University, Montreal, Quebec, Canada H3A 2K6.,Département de Chimie, Université de Montréal, Montreal, Quebec, Canada H3C 3J7
| | - Jaime H Reina
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Tudor Bartoi
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Marion Graf
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Huy Ong
- Faculty of Pharmacy, Université de Montréal, Montreal, Quebec, Canada H3C 3J7
| | - Maximilian H Ulbrich
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.,Department of Nephrology, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Jean-Francois Masson
- Centre for Self-Assembled Chemical Structures (CSACS), McGill University, Montreal, Quebec, Canada H3A 2K6.,Département de Chimie, Université de Montréal, Montreal, Quebec, Canada H3C 3J7
| | - Richard Benton
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
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82
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Okuda K, Tong M, Dempsey B, Moore KJ, Gazzinelli RT, Silverman N. Leishmania amazonensis Engages CD36 to Drive Parasitophorous Vacuole Maturation. PLoS Pathog 2016; 12:e1005669. [PMID: 27280707 PMCID: PMC4900624 DOI: 10.1371/journal.ppat.1005669] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 05/10/2016] [Indexed: 11/19/2022] Open
Abstract
Leishmania amastigotes manipulate the activity of macrophages to favor their own success. However, very little is known about the role of innate recognition and signaling triggered by amastigotes in this host-parasite interaction. In this work we developed a new infection model in adult Drosophila to take advantage of its superior genetic resources to identify novel host factors limiting Leishmania amazonensis infection. The model is based on the capacity of macrophage-like cells, plasmatocytes, to phagocytose and control the proliferation of parasites injected into adult flies. Using this model, we screened a collection of RNAi-expressing flies for anti-Leishmania defense factors. Notably, we found three CD36-like scavenger receptors that were important for defending against Leishmania infection. Mechanistic studies in mouse macrophages showed that CD36 accumulates specifically at sites where the parasite contacts the parasitophorous vacuole membrane. Furthermore, CD36-deficient macrophages were defective in the formation of the large parasitophorous vacuole typical of L. amazonensis infection, a phenotype caused by inefficient fusion with late endosomes and/or lysosomes. These data identify an unprecedented role for CD36 in the biogenesis of the parasitophorous vacuole and further highlight the utility of Drosophila as a model system for dissecting innate immune responses to infection.
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Affiliation(s)
- Kendi Okuda
- Division of Infectious Diseases & Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail: (KO); (NS)
| | - Mei Tong
- Division of Infectious Diseases & Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Brian Dempsey
- Division of Infectious Diseases & Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Kathryn J. Moore
- Department of Medicine, New York University School of Medicine, Langone Medical Center, New York, New York, United States of America
| | - Ricardo T. Gazzinelli
- Division of Infectious Diseases & Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Neal Silverman
- Division of Infectious Diseases & Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail: (KO); (NS)
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83
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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: 94] [Impact Index Per Article: 11.8] [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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84
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Paclitaxel-induced epithelial damage and ectopic MMP-13 expression promotes neurotoxicity in zebrafish. Proc Natl Acad Sci U S A 2016; 113:E2189-98. [PMID: 27035978 PMCID: PMC4839466 DOI: 10.1073/pnas.1525096113] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Paclitaxel is a microtubule-stabilizing chemotherapeutic agent that is widely used in cancer treatment and in a number of curative and palliative regimens. Despite its beneficial effects on cancer, paclitaxel also damages healthy tissues, most prominently the peripheral sensory nervous system. The mechanisms leading to paclitaxel-induced peripheral neuropathy remain elusive, and therapies that prevent or alleviate this condition are not available. We established a zebrafish in vivo model to study the underlying mechanisms and to identify pharmacological agents that may be developed into therapeutics. Both adult and larval zebrafish displayed signs of paclitaxel neurotoxicity, including sensory axon degeneration and the loss of touch response in the distal caudal fin. Intriguingly, studies in zebrafish larvae showed that paclitaxel rapidly promotes epithelial damage and decreased mechanical stress resistance of the skin before induction of axon degeneration. Moreover, injured paclitaxel-treated zebrafish skin and scratch-wounded human keratinocytes (HEK001) display reduced healing capacity. Epithelial damage correlated with rapid accumulation of fluorescein-conjugated paclitaxel in epidermal basal keratinocytes, but not axons, and up-regulation of matrix-metalloproteinase 13 (MMP-13, collagenase 3) in the skin. Pharmacological inhibition of MMP-13, in contrast, largely rescued paclitaxel-induced epithelial damage and neurotoxicity, whereas MMP-13 overexpression in zebrafish embryos rendered the skin vulnerable to injury under mechanical stress conditions. Thus, our studies provide evidence that the epidermis plays a critical role in this condition, and we provide a previously unidentified candidate for therapeutic interventions.
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85
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Phagocytosis genes nonautonomously promote developmental cell death in the Drosophila ovary. Proc Natl Acad Sci U S A 2016; 113:E1246-55. [PMID: 26884181 DOI: 10.1073/pnas.1522830113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Programmed cell death (PCD) is usually considered a cell-autonomous suicide program, synonymous with apoptosis. Recent research has revealed that PCD is complex, with at least a dozen cell death modalities. Here, we demonstrate that the large-scale nonapoptotic developmental PCD in the Drosophila ovary occurs by an alternative cell death program where the surrounding follicle cells nonautonomously promote death of the germ line. The phagocytic machinery of the follicle cells, including Draper, cell death abnormality (Ced)-12, and c-Jun N-terminal kinase (JNK), is essential for the death and removal of germ-line-derived nurse cells during late oogenesis. Cell death events including acidification, nuclear envelope permeabilization, and DNA fragmentation of the nurse cells are impaired when phagocytosis is inhibited. Moreover, elimination of a small subset of follicle cells prevents nurse cell death and cytoplasmic dumping. Developmental PCD in the Drosophila ovary is an intriguing example of nonapoptotic, nonautonomous PCD, providing insight on the diversity of cell death mechanisms.
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86
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Abstract
Programmed cell death (PCD) is essential for health and development. Generally, the last step of PCD is clearance, or engulfment, by phagocytes. Engulfment can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification of the engulfed material. The Drosophila melanogaster ovary serves as an excellent model to study diverse types of PCD and engulfment by epithelial cells. Here, we describe several methods to detect and analyze multiple steps of engulfment in the Drosophila ovary: recognition, vesicle uptake, phagosome maturation, and acidification. Annexin V detects phosphatidylserine, which is flipped to the outer leaflet of the plasma membrane of apoptotic cells, serving as an "eat me" signal. Several germline markers including tral-GFP, Orb, and cleaved Dcp-1 can all be used to label the germline and visualize its uptake into engulfing follicle cells. Drosophila strains expressing GFP and mCherry protein fusions can enable a detailed analysis of phagosome maturation. LysoTracker labels highly acidified compartments, marking phagolysosomes. Together these labels can be used to mark the progression of engulfment in Drosophila follicle cells.
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87
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Im SH, Takle K, Jo J, Babcock DT, Ma Z, Xiang Y, Galko MJ. Tachykinin acts upstream of autocrine Hedgehog signaling during nociceptive sensitization in Drosophila. eLife 2015; 4:e10735. [PMID: 26575288 PMCID: PMC4739760 DOI: 10.7554/elife.10735] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Accepted: 11/16/2015] [Indexed: 12/20/2022] Open
Abstract
Pain signaling in vertebrates is modulated by neuropeptides like Substance P (SP). To determine whether such modulation is conserved and potentially uncover novel interactions between nociceptive signaling pathways we examined SP/Tachykinin signaling in a Drosophila model of tissue damage-induced nociceptive hypersensitivity. Tissue-specific knockdowns and genetic mutant analyses revealed that both Tachykinin and Tachykinin-like receptor (DTKR99D) are required for damage-induced thermal nociceptive sensitization. Electrophysiological recording showed that DTKR99D is required in nociceptive sensory neurons for temperature-dependent increases in firing frequency upon tissue damage. DTKR overexpression caused both behavioral and electrophysiological thermal nociceptive hypersensitivity. Hedgehog, another key regulator of nociceptive sensitization, was produced by nociceptive sensory neurons following tissue damage. Surprisingly, genetic epistasis analysis revealed that DTKR function was upstream of Hedgehog-dependent sensitization in nociceptive sensory neurons. Our results highlight a conserved role for Tachykinin signaling in regulating nociception and the power of Drosophila for genetic dissection of nociception. DOI:http://dx.doi.org/10.7554/eLife.10735.001 Injured animals from humans to insects become extra sensitive to sensations such as touch and heat. This hypersensitivity is thought to protect areas of injury or inflammation while they heal, but it is not clear how it comes about. Now, Im et al. have addressed this question by assessing pain in fruit flies after tissue damage. The experiments used ultraviolet radiation to essentially cause ‘localized sunburn’ to fruit fly larvae. Electrical impulses were then recorded from the larvae’s pain-detecting neurons and the larvae were analyzed for behaviors that indicate pain responses (for example, rolling). Im et al. found that tissue injury lowers the threshold at which temperature causes pain in fruit fly larvae. Further experiments using mutant flies that lacked genes involved in two signaling pathways showed that a signaling molecule called Tachykinin and its receptor (called DTKR) are needed to regulate the observed threshold lowering. When the genes for either of these proteins were deleted, the larvae no longer showed the pain hypersensitivity following an injury. Further experiments then uncovered a genetic interaction between Tachykinin signaling and a second signaling pathway that also regulates pain sensitization (called Hedgehog signaling). Im et al. found that Tachykinin acts upstream of Hedgehog in the pain-detecting neurons. Following on from these findings, the biggest outstanding questions are: how, when and where does tissue damage lead to the release of Tachykinin to sensitize neurons? Future studies could also ask whether the genetic interactions between Hedgehog and Tachykinin (or related proteins) are conserved in other animals such as humans and mice. DOI:http://dx.doi.org/10.7554/eLife.10735.002
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Affiliation(s)
- Seol Hee Im
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, United States
| | - Kendra Takle
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Juyeon Jo
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, United States.,Genes and Development Graduate Program, University of Texas Graduate School of Biomedical Sciences, Houston, United States
| | - Daniel T Babcock
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, United States.,Neuroscience Graduate Program, University of Texas Graduate School of Biomedical Sciences, Houston, United States
| | - Zhiguo Ma
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Yang Xiang
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, United States
| | - Michael J Galko
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, United States.,Genes and Development Graduate Program, University of Texas Graduate School of Biomedical Sciences, Houston, United States.,Neuroscience Graduate Program, University of Texas Graduate School of Biomedical Sciences, Houston, United States
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88
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Lin T, Pan PY, Lai YT, Chiang KW, Hsieh HL, Wu YP, Ke JM, Lee MC, Liao SS, Shih HT, Tang CY, Yang SB, Cheng HC, Wu JT, Jan YN, Lee HH. Spindle-F Is the Central Mediator of Ik2 Kinase-Dependent Dendrite Pruning in Drosophila Sensory Neurons. PLoS Genet 2015; 11:e1005642. [PMID: 26540204 PMCID: PMC4634852 DOI: 10.1371/journal.pgen.1005642] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 10/11/2015] [Indexed: 11/18/2022] Open
Abstract
During development, certain Drosophila sensory neurons undergo dendrite pruning that selectively eliminates their dendrites but leaves the axons intact. How these neurons regulate pruning activity in the dendrites remains unknown. Here, we identify a coiled-coil protein Spindle-F (Spn-F) that is required for dendrite pruning in Drosophila sensory neurons. Spn-F acts downstream of IKK-related kinase Ik2 in the same pathway for dendrite pruning. Spn-F exhibits a punctate pattern in larval neurons, whereas these Spn-F puncta become redistributed in pupal neurons, a step that is essential for dendrite pruning. The redistribution of Spn-F from puncta in pupal neurons requires the phosphorylation of Spn-F by Ik2 kinase to decrease Spn-F self-association, and depends on the function of microtubule motor dynein complex. Spn-F is a key component to link Ik2 kinase to dynein motor complex, and the formation of Ik2/Spn-F/dynein complex is critical for Spn-F redistribution and for dendrite pruning. Our findings reveal a novel regulatory mechanism for dendrite pruning achieved by temporal activation of Ik2 kinase and dynein-mediated redistribution of Ik2/Spn-F complex in neurons.
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Affiliation(s)
- Tzu Lin
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Yuan Pan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Ting Lai
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kai-Wen Chiang
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hsin-Lun Hsieh
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Ping Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jian-Ming Ke
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Myong-Chol Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shih-Sian Liao
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hsueh-Tzu Shih
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chiou-Yang Tang
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Shi-Bing Yang
- Howard Hughes Medical Institute, Department of Physiology, Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Hsu-Chen Cheng
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yuh-Nung Jan
- Howard Hughes Medical Institute, Department of Physiology, Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Hsiu-Hsiang Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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89
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Abstract
The nervous system is populated by numerous types of neurons, each bearing a dendritic arbor with a characteristic morphology. These type-specific features influence many aspects of a neuron's function, including the number and identity of presynaptic inputs and how inputs are integrated to determine firing properties. Here, we review the mechanisms that regulate the construction of cell type-specific dendrite patterns during development. We focus on four aspects of dendrite patterning that are particularly important in determining the function of the mature neuron: (a) dendrite shape, including branching pattern and geometry of the arbor; (b) dendritic arbor size;
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Affiliation(s)
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138;
| | - Jeremy N Kay
- Departments of Neurobiology and Ophthalmology, Duke University School of Medicine, Durham, North Carolina 27710;
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90
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Meehan TL, Kleinsorge SE, Timmons AK, Taylor JD, McCall K. Polarization of the epithelial layer and apical localization of integrins are required for engulfment of apoptotic cells in the Drosophila ovary. Dis Model Mech 2015; 8:1603-14. [PMID: 26398951 PMCID: PMC4728319 DOI: 10.1242/dmm.021998] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/14/2015] [Indexed: 12/28/2022] Open
Abstract
Inefficient clearance of dead cells or debris by epithelial cells can lead to or exacerbate debilitating conditions such as retinitis pigmentosa, macular degeneration, chronic obstructive pulmonary disease and asthma. Despite the importance of engulfment by epithelial cells, little is known about the molecular changes that are required within these cells. The misregulation of integrins has previously been associated with disease states, suggesting that a better understanding of the regulation of receptor trafficking could be key to treating diseases caused by defects in phagocytosis. Here, we demonstrate that the integrin heterodimer αPS3/βPS becomes apically enriched and is required for engulfment by the epithelial follicle cells of the Drosophila ovary. We found that integrin heterodimer localization and function is largely directed by the α-subunit. Moreover, proper cell polarity promotes asymmetric integrin enrichment, suggesting that αPS3/βPS trafficking occurs in a polarized fashion. We show that several genes previously known for their roles in trafficking and cell migration are also required for engulfment. Moreover, as in mammals, the same α-integrin subunit is required by professional and non-professional phagocytes and migrating cells in Drosophila. Our findings suggest that migrating and engulfing cells use common machinery, and demonstrate a crucial role for integrin function and polarized trafficking of integrin subunits during engulfment. This study also establishes the epithelial follicle cells of the Drosophila ovary as a powerful model for understanding the molecular changes required for engulfment by a polarized epithelium. Summary: Apical integrin localization, mediated by polarized and directed trafficking, is crucial for proper engulfment by epithelial cells.
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Affiliation(s)
- Tracy L Meehan
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Sarah E Kleinsorge
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Allison K Timmons
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Jeffrey D Taylor
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
| | - Kimberly McCall
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA 02215, USA
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91
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Rabinovich D, Mayseless O, Schuldiner O. Long term ex vivo culturing of Drosophila brain as a method to live image pupal brains: insights into the cellular mechanisms of neuronal remodeling. Front Cell Neurosci 2015; 9:327. [PMID: 26379498 PMCID: PMC4547045 DOI: 10.3389/fncel.2015.00327] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/07/2015] [Indexed: 01/01/2023] Open
Abstract
Holometabolous insects, including Drosophila melanogaster, undergo complete metamorphosis that includes a pupal stage. During metamorphosis, the Drosophila nervous system undergoes massive remodeling and growth, that include cell death and large-scale axon and synapse elimination as well as neurogenesis, developmental axon regrowth, and formation of new connections. Neuronal remodeling is an essential step in the development of vertebrate and invertebrate nervous systems. Research on the stereotypic remodeling of Drosophila mushroom body (MB) γ neurons has contributed to our knowledge of the molecular mechanisms of remodeling but our knowledge of the cellular mechanisms remain poorly understood. A major hurdle in understanding various dynamic processes that occur during metamorphosis is the lack of time-lapse resolution. The pupal case and opaque fat bodies that enwrap the central nervous system (CNS) make live-imaging of the central brain in-vivo impossible. We have established an ex vivo long-term brain culture system that supports the development and neuronal remodeling of pupal brains. By optimizing culture conditions and dissection protocols, we have observed development in culture at kinetics similar to what occurs in vivo. Using this new method, we have obtained the first time-lapse sequence of MB γ neurons undergoing remodeling in up to a single cell resolution. We found that axon pruning is initiated by blebbing, followed by one-two nicks that seem to initiate a more widely spread axon fragmentation. As such, we have set up some of the tools and methodologies needed for further exploration of the cellular mechanisms of neuronal remodeling, not limited to the MB. The long-term ex vivo brain culture system that we report here could be used to study dynamic aspects of neurodevelopment of any Drosophila neuron.
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Affiliation(s)
- Dana Rabinovich
- Department of Molecular Cell Biology, Weizmann Institute of Sciences Rehovot, Israel
| | - Oded Mayseless
- Department of Molecular Cell Biology, Weizmann Institute of Sciences Rehovot, Israel
| | - Oren Schuldiner
- Department of Molecular Cell Biology, Weizmann Institute of Sciences Rehovot, Israel
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92
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Lin TY, Luo J, Shinomiya K, Ting CY, Lu Z, Meinertzhagen IA, Lee CH. Mapping chromatic pathways in the Drosophila visual system. J Comp Neurol 2015; 524:213-27. [PMID: 26179639 DOI: 10.1002/cne.23857] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/13/2015] [Accepted: 07/13/2015] [Indexed: 11/06/2022]
Abstract
In Drosophila, color vision and wavelength-selective behaviors are mediated by the compound eye's narrow-spectrum photoreceptors R7 and R8 and their downstream medulla projection (Tm) neurons Tm5a, Tm5b, Tm5c, and Tm20 in the second optic neuropil or medulla. These chromatic Tm neurons project axons to a deeper optic neuropil, the lobula, which in insects has been implicated in processing and relaying color information to the central brain. The synaptic targets of the chromatic Tm neurons in the lobula are not known, however. Using a modified GFP reconstitution across synaptic partners (GRASP) method to probe connections between the chromatic Tm neurons and 28 known and novel types of lobula neurons, we identify anatomically the visual projection neurons LT11 and LC14 and the lobula intrinsic neurons Li3 and Li4 as synaptic targets of the chromatic Tm neurons. Single-cell GRASP analyses reveal that Li4 receives synaptic contacts from over 90% of all four types of chromatic Tm neurons, whereas LT11 is postsynaptic to the chromatic Tm neurons, with only modest selectivity and at a lower frequency and density. To visualize synaptic contacts at the ultrastructural level, we develop and apply a "two-tag" double-labeling method to label LT11's dendrites and the mitochondria in Tm5c's presynaptic terminals. Serial electron microscopic reconstruction confirms that LT11 receives direct contacts from Tm5c. This method would be generally applicable to map the connections of large complex neurons in Drosophila and other animals.
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Affiliation(s)
- Tzu-Yang Lin
- Section on Neuronal Connectivity, Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892.,Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, 114, Taiwan
| | - Jiangnan Luo
- Section on Neuronal Connectivity, Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892
| | - Kazunori Shinomiya
- Depart of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Chun-Yuan Ting
- Section on Neuronal Connectivity, Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892
| | - Zhiyuan Lu
- Depart of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Ian A Meinertzhagen
- Depart of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Chi-Hon Lee
- Section on Neuronal Connectivity, Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, 20892
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93
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Pearce MM, Spartz EJ, Hong W, Luo L, Kopito RR. Prion-like transmission of neuronal huntingtin aggregates to phagocytic glia in the Drosophila brain. Nat Commun 2015; 6:6768. [PMID: 25866135 PMCID: PMC4515032 DOI: 10.1038/ncomms7768] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Accepted: 02/24/2015] [Indexed: 12/12/2022] Open
Abstract
The brain has a limited capacity to self-protect against protein aggregate-associated pathology, and mounting evidence supports a role for phagocytic glia in this process. We have established a Drosophila model to investigate the role of phagocytic glia in clearance of neuronal mutant huntingtin (Htt) aggregates associated with Huntington disease. We find that glia regulate steady-state numbers of Htt aggregates expressed in neurons through a clearance mechanism that requires the glial scavenger receptor Draper and downstream phagocytic engulfment machinery. Remarkably, some of these engulfed neuronal Htt aggregates effect prion-like conversion of soluble, wild-type Htt in the glial cytoplasm. We provide genetic evidence that this conversion depends strictly on the Draper signalling pathway, unveiling a previously unanticipated role for phagocytosis in transfer of pathogenic protein aggregates in an intact brain. These results suggest a potential mechanism by which phagocytic glia contribute to both protein aggregate-related neuroprotection and pathogenesis in neurodegenerative disease.
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Affiliation(s)
| | - Ellen J. Spartz
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Weizhe Hong
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Liqun Luo
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Ron R. Kopito
- Department of Biology, Stanford University, Stanford, CA 94305, USA
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94
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Abstract
Cellular debris created by developmental processes or injury must be cleared by phagocytic cells to maintain and repair tissues. Cutaneous injuries damage not only epidermal cells but also the axonal endings of somatosensory (touch-sensing) neurons, which must be repaired to restore the sensory function of the skin. Phagocytosis of neuronal debris is usually performed by macrophages or other blood-derived professional phagocytes, but we have found that epidermal cells phagocytose somatosensory axon debris in zebrafish. Live imaging revealed that epidermal cells rapidly internalize debris into dynamic phosphatidylinositol 3-monophosphate-positive phagosomes that mature into phagolysosomes using a pathway similar to that of professional phagocytes. Epidermal cells phagocytosed not only somatosensory axon debris but also debris created by injury to other peripheral axons that were mislocalized to the skin, neighboring skin cells, and macrophages. Together, these results identify vertebrate epidermal cells as broad-specificity phagocytes that likely contribute to neural repair and wound healing.
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95
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Kanamori T, Yoshino J, Yasunaga KI, Dairyo Y, Emoto K. Local endocytosis triggers dendritic thinning and pruning in Drosophila sensory neurons. Nat Commun 2015; 6:6515. [DOI: 10.1038/ncomms7515] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 02/04/2015] [Indexed: 12/15/2022] Open
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96
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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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97
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Rieger S, Zhao H, Martin P, Abe K, Lisse TS. The role of nuclear hormone receptors in cutaneous wound repair. Cell Biochem Funct 2014; 33:1-13. [PMID: 25529612 DOI: 10.1002/cbf.3086] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/06/2014] [Accepted: 11/14/2014] [Indexed: 12/12/2022]
Abstract
The cutaneous wound repair process involves balancing a dynamic series of events ranging from inflammation, oxidative stress, cell migration, proliferation, survival and differentiation. A complex series of secreted trophic factors, cytokines, surface and intracellular proteins are expressed in a temporospatial manner to restore skin integrity after wounding. Impaired initiation, maintenance or termination of the tissue repair processes can lead to perturbed healing, necrosis, fibrosis or even cancer. Nuclear hormone receptors (NHRs) in the cutaneous environment regulate tissue repair processes such as fibroplasia and angiogenesis. Defects in functional NHRs and their ligands are associated with the clinical phenotypes of chronic non-healing wounds and skin endocrine disorders. The functional relationship between NHRs and skin niche cells such as epidermal keratinocytes and dermal fibroblasts is pivotal for successful wound closure and permanent repair. The aim of this review is to delineate the cutaneous effects and cross-talk of various nuclear receptors upon injury towards functional tissue restoration.
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Affiliation(s)
- Sandra Rieger
- Center for Regenerative Biology and Medicine, MDI Biological Laboratory, Salisbury Cove, ME, USA
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98
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Suzuki J, Imanishi E, Nagata S. Exposure of phosphatidylserine by Xk-related protein family members during apoptosis. J Biol Chem 2014; 289:30257-30267. [PMID: 25231987 DOI: 10.1074/jbc.m114.583419] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apoptotic cells expose phosphatidylserine (PtdSer) on their surface as an "eat me" signal. Mammalian Xk-related (Xkr) protein 8, which is predicted to contain six transmembrane regions, and its Caenorhabditis elegans homolog CED-8 promote apoptotic PtdSer exposure. The mouse and human Xkr families consist of eight and nine members, respectively. Here, we found that mouse Xkr family members, with the exception of Xkr2, are localized to the plasma membrane. When Xkr8-deficient cells, which do not expose PtdSer during apoptosis, were transformed by Xkr family members, the transformants expressing Xkr4, Xkr8, or Xkr9 responded to apoptotic stimuli by exposing cell surface PtdSer and were efficiently engulfed by macrophages. Like Xkr8, Xkr4 and Xkr9 were found to possess a caspase recognition site in the C-terminal region and to require its direct cleavage by caspases for their function. Site-directed mutagenesis of the amino acid residues conserved among CED-8, Xkr4, Xkr8, and Xkr9 identified several essential residues in the second transmembrane and second cytoplasmic regions. Real time PCR analysis indicated that unlike Xkr8, which is ubiquitously expressed, Xkr4 and Xkr9 expression is tissue-specific.
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Affiliation(s)
- Jun Suzuki
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto, Kyoto 606-8501, Japan
| | - Eiichi Imanishi
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto, Kyoto 606-8501, Japan
| | - Shigekazu Nagata
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto, Kyoto 606-8501, Japan.
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99
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Schuldiner O, Yaron A. Mechanisms of developmental neurite pruning. Cell Mol Life Sci 2014; 72:101-19. [PMID: 25213356 DOI: 10.1007/s00018-014-1729-6] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/02/2014] [Accepted: 09/04/2014] [Indexed: 12/19/2022]
Abstract
The precise wiring of the nervous system is a combined outcome of progressive and regressive events during development. Axon guidance and synapse formation intertwined with cell death and neurite pruning sculpt the mature circuitry. It is now well recognized that pruning of dendrites and axons as means to refine neuronal networks, is a wide spread phenomena required for the normal development of vertebrate and invertebrate nervous systems. Here we will review the arising principles of cellular and molecular mechanisms of neurite pruning. We will discuss these principles in light of studies in multiple neuronal systems, and speculate on potential explanations for the emergence of neurite pruning as a mechanism to sculpt the nervous system.
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Affiliation(s)
- Oren Schuldiner
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, 7610001, Rehovot, Israel,
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100
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Pease SE, Segal RA. Preserve and protect: maintaining axons within functional circuits. Trends Neurosci 2014; 37:572-82. [PMID: 25167775 DOI: 10.1016/j.tins.2014.07.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 07/21/2014] [Accepted: 07/27/2014] [Indexed: 12/14/2022]
Abstract
During development, neural circuits are initially generated by exuberant innervation and are rapidly refined by selective preservation and elimination of axons. The establishment and maintenance of functional circuits therefore requires coordination of axon survival and degeneration pathways. Both developing and mature circuits rely on interdependent mitochondrial and cytoskeletal components to maintain axonal health and homeostasis; injury or diseases that impinge on these components frequently cause pathologic axon loss. Here, we review recent findings that identify mechanisms of axonal preservation in the contexts of development, injury, and disease.
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Affiliation(s)
- Sarah E Pease
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Rosalind A Segal
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
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