1
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Harders RH, Morthorst TH, Landgrebe LE, Lande AD, Fuglsang MS, Mortensen SB, Feteira-Montero V, Jensen HH, Wesseltoft JB, Olsen A. CED-6/GULP and components of the clathrin-mediated endocytosis machinery act redundantly to correctly display CED-1 on the cell membrane in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2024; 14:jkae088. [PMID: 38696649 PMCID: PMC11228867 DOI: 10.1093/g3journal/jkae088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/03/2024] [Accepted: 04/16/2024] [Indexed: 05/04/2024]
Abstract
CED-1 (cell death abnormal) is a transmembrane receptor involved in the recognition of "eat-me" signals displayed on the surface of apoptotic cells and thus central for the subsequent engulfment of the cell corpse in Caenorhabditis elegans. The roles of CED-1 in engulfment are well established, as are its downstream effectors. The latter include the adapter protein CED-6/GULP and the ATP-binding cassette family homolog CED-7. However, how CED-1 is maintained on the plasma membrane in the absence of engulfment is currently unknown. Here, we show that CED-6 and CED-7 have a novel role in maintaining CED-1 correctly on the plasma membrane. We propose that the underlying mechanism is via endocytosis as CED-6 and CED-7 act redundantly with clathrin and its adaptor, the Adaptor protein 2 complex, in ensuring correct CED-1 localization. In conclusion, CED-6 and CED-7 impact other cellular processes than engulfment of apoptotic cells.
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Affiliation(s)
- Rikke Hindsgaul Harders
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg, DK-9220, Denmark
| | - Tine H Morthorst
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus, DK-8000, Denmark
| | - Line E Landgrebe
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus, DK-8000, Denmark
| | - Anna D Lande
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus, DK-8000, Denmark
| | - Marie Sikjær Fuglsang
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, Aarhus, DK-8000, Denmark
| | - Stine Bothilde Mortensen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg, DK-9220, Denmark
| | - Verónica Feteira-Montero
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg, DK-9220, Denmark
| | - Helene Halkjær Jensen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg, DK-9220, Denmark
| | - Jonas Bruhn Wesseltoft
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg, DK-9220, Denmark
| | - Anders Olsen
- Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, Aalborg, DK-9220, Denmark
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2
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Wang J, Barr MM, Wehman AM. Extracellular vesicles. Genetics 2024:iyae088. [PMID: 38884207 DOI: 10.1093/genetics/iyae088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 05/21/2024] [Indexed: 06/18/2024] Open
Abstract
Extracellular vesicles (EVs) encompass a diverse array of membrane-bound organelles released outside cells in response to developmental and physiological cell needs. EVs play important roles in remodeling the shape and content of differentiating cells and can rescue damaged cells from toxic or dysfunctional content. EVs can send signals and transfer metabolites between tissues and organisms to regulate development, respond to stress or tissue damage, or alter mating behaviors. While many EV functions have been uncovered by characterizing ex vivo EVs isolated from body fluids and cultured cells, research using the nematode Caenorhabditis elegans has provided insights into the in vivo functions, biogenesis, and uptake pathways. The C. elegans EV field has also developed methods to analyze endogenous EVs within the organismal context of development and adult physiology in free-living, behaving animals. In this review, we summarize major themes that have emerged for C. elegans EVs and their relevance to human health and disease. We also highlight the diversity of biogenesis mechanisms, locations, and functions of worm EVs and discuss open questions and unexplored topics tenable in C. elegans, given the nematode model is ideal for light and electron microscopy, genetic screens, genome engineering, and high-throughput omics.
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Affiliation(s)
- Juan Wang
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Maureen M Barr
- Department of Genetics, Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Ann M Wehman
- Department of Biological Sciences, University of Denver, Denver, CO 80210, USA
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3
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Park S, Noblett N, Pitts L, Colavita A, Wehman AM, Jin Y, Chisholm AD. Dopey-dependent regulation of extracellular vesicles maintains neuronal morphology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.591898. [PMID: 38766017 PMCID: PMC11100700 DOI: 10.1101/2024.05.07.591898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Mature neurons maintain their distinctive morphology for extended periods in adult life. Compared to developmental neurite outgrowth, axon guidance, and target selection, relatively little is known of mechanisms that maintain mature neuron morphology. Loss of function in C. elegans DIP-2, a member of the conserved lipid metabolic regulator Dip2 family, results in progressive overgrowth of neurites in adults. We find that dip-2 mutants display specific genetic interactions with sax-2, the C. elegans ortholog of Drosophila Furry and mammalian FRY. Combined loss of DIP-2 and SAX-2 results in severe disruption of neuronal morphology maintenance accompanied by increased release of neuronal extracellular vesicles (EVs). By screening for suppressors of dip-2 sax-2 double mutant defects we identified gain-of-function (gf) mutations in the conserved Dopey family protein PAD-1 and its associated phospholipid flippase TAT-5/ATP9A. In dip-2 sax-2 double mutants carrying either pad-1(gf) or tat-5(gf) mutation, EV release is reduced and neuronal morphology across multiple neuron types is restored to largely normal. PAD-1(gf) acts cell autonomously in neurons. The domain containing pad-1(gf) is essential for PAD-1 function, and PAD-1(gf) protein displays increased association with the plasma membrane and inhibits EV release. Our findings uncover a novel functional network of DIP-2, SAX-2, PAD-1, and TAT-5 that maintains morphology of neurons and other types of cells, shedding light on the mechanistic basis of neurological disorders involving human orthologs of these genes.
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Affiliation(s)
- Seungmee Park
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Nathaniel Noblett
- Neuroscience Program, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Lauren Pitts
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Antonio Colavita
- Neuroscience Program, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Ann M Wehman
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Yishi Jin
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Andrew D Chisholm
- Department of Neurobiology, School of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
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4
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Elfmark LA, Wenzel EM, Wang L, Pedersen NM, Stenmark H, Raiborg C. Protrudin-mediated ER-endosome contact sites promote phagocytosis. Cell Mol Life Sci 2023; 80:216. [PMID: 37468729 PMCID: PMC10356898 DOI: 10.1007/s00018-023-04862-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 07/06/2023] [Accepted: 07/08/2023] [Indexed: 07/21/2023]
Abstract
During phagocytosis, endosomes both contribute with membrane to forming phagosomes and promote phagosome maturation. However, how these vesicles are delivered to the phagocytic cup and the phagosome has been unknown. Here, we show that Protrudin-mediated endoplasmic reticulum (ER)-endosome contact sites facilitate anterograde translocation of FYCO1 and VAMP7-positive late endosomes and lysosomes (LELys) to forming phagocytic cups in a retinal pigment epithelial-derived cell line (RPE1). Protrudin-dependent phagocytic cup formation required SYT7, which promotes fusion of LELys with the plasma membrane. RPE1 cells perform phagocytosis of dead cells (efferocytosis) that expose phosphatidylserine (PS) on their surface. Exogenous addition of apoptotic bodies increased the formation of phagocytic cups, which further increased when Protrudin was overexpressed. Overexpression of Protrudin also led to elevated uptake of silica beads coated with PS. Conversely, Protrudin depletion or abrogation of ER-endosome contact sites inhibited phagocytic cup formation resulting in reduced uptake of PS-coated beads. Thus, the Protrudin pathway delivers endosomes to facilitate formation of the phagocytic cup important for PS-dependent phagocytosis.
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Affiliation(s)
- Liv Anker Elfmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Eva Maria Wenzel
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Ling Wang
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Nina Marie Pedersen
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Harald Stenmark
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Camilla Raiborg
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway.
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
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5
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Ji H, Wang B, Shen Y, Labib D, Lei J, Chen X, Sapar M, Boulanger A, Dura JM, Han C. The Drosophila chemokine-like Orion bridges phosphatidylserine and Draper in phagocytosis of neurons. Proc Natl Acad Sci U S A 2023; 120:e2303392120. [PMID: 37276397 PMCID: PMC10268242 DOI: 10.1073/pnas.2303392120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/10/2023] [Indexed: 06/07/2023] Open
Abstract
Phagocytic clearance of degenerating neurons is triggered by "eat-me" signals exposed on the neuronal surface. The conserved neuronal eat-me signal phosphatidylserine (PS) and the engulfment receptor Draper (Drpr) mediate phagocytosis of degenerating neurons in Drosophila. However, how PS is recognized by Drpr-expressing phagocytes in vivo remains poorly understood. Using multiple models of dendrite degeneration, we show that the Drosophila chemokine-like protein Orion can bind to PS and is responsible for detecting PS exposure on neurons; it is supplied cell-non-autonomously to coat PS-exposing dendrites and to mediate interactions between PS and Drpr, thus enabling phagocytosis. As a result, the accumulation of Orion on neurons and on phagocytes produces opposite outcomes by potentiating and suppressing phagocytosis, respectively. Moreover, the Orion dosage is a key determinant of the sensitivity of phagocytes to PS exposed on neurons. Lastly, mutagenesis analyses show that the sequence motifs shared between Orion and human immunomodulatory proteins are important for Orion function. Thus, our results uncover a missing link in PS-mediated phagocytosis in Drosophila and imply conserved mechanisms of phagocytosis of neurons.
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Affiliation(s)
- Hui Ji
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Bei Wang
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Yifan Shen
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - David Labib
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Joyce Lei
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Xinchen Chen
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Maria Sapar
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
| | - Ana Boulanger
- Institute of Human Genetics (IGH), Univ Montpellier, CNRS, Montpellier34090, France
| | - Jean-Maurice Dura
- Institute of Human Genetics (IGH), Univ Montpellier, CNRS, Montpellier34090, France
| | - Chun Han
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
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6
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Zhu X, Huang C, Li N, Ma X, Li Z, Fan J. Distinct roles of graphene and graphene oxide nanosheets in regulating phospholipid flip-flop. J Colloid Interface Sci 2023; 637:112-122. [PMID: 36689797 DOI: 10.1016/j.jcis.2023.01.080] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 12/30/2022] [Accepted: 01/15/2023] [Indexed: 01/19/2023]
Abstract
Two-dimensional (2D) nanomaterials, such as graphene nanosheets (GNs) and graphene oxide nanosheets (GOs), could adhere onto or insert into a biological membrane, leading to a change in membrane properties and biological activities. Consequently, GN and GO become potential candidates for mediating interleaflet phospholipid transfer. In this work, molecular dynamics (MD) simulations were employed to investigate the effects of GN and GO on lipid flip-flop behavior and the underlying molecular mechanisms. Of great interest is that GN and GO work in opposite directions. The inserted GN can induce the formation of an ordered nanodomain, which dramatically elevates the free energy barrier of flipping phospholipids from one leaflet to the other, thus leading to a decreased lipid flip-flop rate. In contrast, the embedded GO can catalyze the transport of phospholipids between membrane leaflets by facilitating the formation of water pores. These results suggest that GN may work as an inhibitor of the interleaflet lipid translocation, while GO may play the role of scramblases. These findings are expected to expand promising biomedical applications of 2D nanomaterials.
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Affiliation(s)
- Xiaohong Zhu
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Changxiong Huang
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Na Li
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Xinyao Ma
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Zhen Li
- School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China.
| | - Jun Fan
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China; Center for Advanced Nuclear Safety and Sustainable Development, City University of Hong Kong, Hong Kong, China.
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7
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Furuta Y, Zhou Z. How do necrotic cells expose phosphatidylserine to attract their predators—What’s unique and what’s in common with apoptotic cells. Front Cell Dev Biol 2023; 11:1170551. [PMID: 37091984 PMCID: PMC10113483 DOI: 10.3389/fcell.2023.1170551] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/27/2023] [Indexed: 04/09/2023] Open
Abstract
Phosphatidylserine (PS) is a lipid component of the plasma membrane. It is asymmetrically distributed to the inner leaflet in live cells. In cells undergoing apoptosis, phosphatidylserine is exposed to the outer surfaces. The exposed phosphatidylserine acts as an evolutionarily conserved “eat-me” signal that attracts neighboring engulfing cells in metazoan organisms, including the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and mammals. During apoptosis, the exposure of phosphatidylserine to the outer surface of a cell is driven by the membrane scramblases and flippases, the activities of which are regulated by caspases. Cells undergoing necrosis, a kind of cell death frequently associated with cellular injuries and morphologically distinct from apoptosis, were initially believed to allow passive exposure of phosphatidylserine through membrane rupture. Later studies revealed that necrotic cells actively expose phosphatidylserine before any rupture occurs. A recent study in C. elegans further reported that the calcium ion (Ca2+) plays an essential role in promoting the exposure of phosphatidylserine on the surfaces of necrotic cells. These findings indicate that necrotic and apoptotic cells, which die through different molecular mechanisms, use common and unique mechanisms for promoting the exposure of the same “eat me” signal. This article will review the mechanisms regulating the exposure of phosphatidylserine on the surfaces of necrotic and apoptotic cells and highlight their similarities and differences.
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8
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Fazeli G, Frondoni J, Kolli S, Wehman AM. Visualizing Phagocytic Cargo In Vivo from Engulfment to Resolution in Caenorhabditis elegans. Methods Mol Biol 2023; 2692:337-360. [PMID: 37365478 DOI: 10.1007/978-1-0716-3338-0_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
The nematode Caenorhabditis elegans offers many experimental advantages to study conserved mechanisms of phagocytosis and phagocytic clearance. These include the stereotyped timing of phagocytic events in vivo for time-lapse imaging, the availability of transgenic reporters labeling molecules involved in different steps of phagocytosis, and the transparency of the animal for fluorescence imaging. Further, the ease of forward and reverse genetics in C. elegans has enabled many of the initial discoveries of proteins involved in phagocytic clearance. In this chapter, we focus on phagocytosis by the large undifferentiated blastomeres of C. elegans embryos, which engulf and eliminate diverse phagocytic cargo from the corpse of the second polar body to cytokinetic midbody remnants. We describe the use of fluorescent time-lapse imaging to observe the distinct steps of phagocytic clearance and methods to normalize this process to distinguish defects in mutant strains. These approaches have enabled us to reveal new insights from the initial signaling to induce phagocytosis up until the final resolution of phagocytic cargo in phagolysosomes.
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Affiliation(s)
- Gholamreza Fazeli
- Imaging Core Facility, Biocenter, University of Würzburg, Würzburg, Germany
| | - Julia Frondoni
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Shruti Kolli
- Department of Biological Sciences, University of Denver, Denver, CO, USA
| | - Ann M Wehman
- Department of Biological Sciences, University of Denver, Denver, CO, USA.
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9
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Juanez K, Ghose P. Repurposing the Killing Machine: Non-canonical Roles of the Cell Death Apparatus in Caenorhabditis elegans Neurons. Front Cell Dev Biol 2022; 10:825124. [PMID: 35237604 PMCID: PMC8882910 DOI: 10.3389/fcell.2022.825124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/31/2022] [Indexed: 12/29/2022] Open
Abstract
Here we highlight the increasingly divergent functions of the Caenorhabditis elegans cell elimination genes in the nervous system, beyond their well-documented roles in cell dismantling and removal. We describe relevant background on the C. elegans nervous system together with the apoptotic cell death and engulfment pathways, highlighting pioneering work in C. elegans. We discuss in detail the unexpected, atypical roles of cell elimination genes in various aspects of neuronal development, response and function. This includes the regulation of cell division, pruning, axon regeneration, and behavioral outputs. We share our outlook on expanding our thinking as to what cell elimination genes can do and noting their versatility. We speculate on the existence of novel genes downstream and upstream of the canonical cell death pathways relevant to neuronal biology. We also propose future directions emphasizing the exploration of the roles of cell death genes in pruning and guidance during embryonic development.
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10
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Raiders S, Black EC, Bae A, MacFarlane S, Klein M, Shaham S, Singhvi A. Glia actively sculpt sensory neurons by controlled phagocytosis to tune animal behavior. eLife 2021; 10:63532. [PMID: 33759761 PMCID: PMC8079151 DOI: 10.7554/elife.63532] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/23/2021] [Indexed: 02/07/2023] Open
Abstract
Glia in the central nervous system engulf neuron fragments to remodel synapses and recycle photoreceptor outer segments. Whether glia passively clear shed neuronal debris or actively prune neuron fragments is unknown. How pruning of single-neuron endings impacts animal behavior is also unclear. Here, we report our discovery of glia-directed neuron pruning in Caenorhabditis elegans. Adult C. elegans AMsh glia engulf sensory endings of the AFD thermosensory neuron by repurposing components of the conserved apoptotic corpse phagocytosis machinery. The phosphatidylserine (PS) flippase TAT-1/ATP8A functions with glial PS-receptor PSR-1/PSR and PAT-2/α-integrin to initiate engulfment. This activates glial CED-10/Rac1 GTPase through the ternary GEF complex of CED-2/CrkII, CED-5/DOCK180, CED-12/ELMO. Execution of phagocytosis uses the actin-remodeler WSP-1/nWASp. This process dynamically tracks AFD activity and is regulated by temperature, the AFD sensory input. Importantly, glial CED-10 levels regulate engulfment rates downstream of neuron activity, and engulfment-defective mutants exhibit altered AFD-ending shape and thermosensory behavior. Our findings reveal a molecular pathway underlying glia-dependent engulfment in a peripheral sense-organ and demonstrate that glia actively engulf neuron fragments, with profound consequences on neuron shape and animal sensory behavior. Neurons are tree-shaped cells that receive information through endings connected to neighbouring cells or the environment. Controlling the size, number and location of these endings is necessary to ensure that circuits of neurons get precisely the right amount of input from their surroundings. Glial cells form a large portion of the nervous system, and they are tasked with supporting, cleaning and protecting neurons. In humans, part of their duties is to ‘eat’ (or prune) unnecessary neuron endings. In fact, this role is so important that defects in glial pruning are associated with conditions such as Alzheimer’s disease. Yet it is still unknown how pruning takes place, and in particular whether it is the neuron or the glial cell that initiates the process. To investigate this question, Raiders et al. enlisted the common laboratory animal Caenorhabditis elegans, a tiny worm with a simple nervous system where each neuron has been meticulously mapped out. First, the experiments showed that glial cells in C. elegans actually prune the endings of sensory neurons. Focusing on a single glia-neuron pair then revealed that the glial cell could trim the endings of a living neuron by redeploying the same molecular machinery it uses to clear dead cell debris. Compared to this debris-clearing activity, however, the glial cell takes a more nuanced approach to pruning: specifically, it can adjust the amount of trimming based on the activity load of the neuron. When Raiders et al. disrupted the glial pruning for a single temperature-sensing neuron, the worm lost its normal temperature preferences; this demonstrated how the pruning activity of a single glial cell can be linked to behavior. Taken together the experiments showcase how C. elegans can be used to study glial pruning. Further work using this model could help to understand how disease emerges when glial cells cannot perform their role, and to spot the genetic factors that put certain individuals at increased risk for neurological and sensory disorders.
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Affiliation(s)
- Stephan Raiders
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, United States
| | - Erik Calvin Black
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Andrea Bae
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States.,Cellular Imaging Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Stephen MacFarlane
- Department of Physics and Department of Biology, University of Miami, Coral Gables, United States
| | - Mason Klein
- Department of Physics and Department of Biology, University of Miami, Coral Gables, United States
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, United States.,Department of Biological Structure, University of Washington School of Medicine, Seattle, United States.,Brotman Baty Institute for Precision Medicine, Seattle, United States
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11
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Perez MA, Watts JL. Worms, Fat, and Death: Caenorhabditis elegans Lipid Metabolites Regulate Cell Death. Metabolites 2021; 11:metabo11020125. [PMID: 33672292 PMCID: PMC7926963 DOI: 10.3390/metabo11020125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/19/2021] [Accepted: 02/19/2021] [Indexed: 12/28/2022] Open
Abstract
Caenorhabditis elegans is well-known as the model organism used to elucidate the genetic pathways underlying the first described form of regulated cell death, apoptosis. Since then, C. elegans investigations have contributed to the further understanding of lipids in apoptosis, especially the roles of phosphatidylserines and phosphatidylinositols. More recently, studies in C. elegans have shown that dietary polyunsaturated fatty acids can induce the non-apoptotic, iron-dependent form of cell death, ferroptosis. In this review, we examine the roles of various lipids in specific aspects of regulated cell death, emphasizing recent work in C. elegans.
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12
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Li P, Jing H, Wang Y, Yuan L, Xiao H, Zheng Q. SUMO modification in apoptosis. J Mol Histol 2020; 52:1-10. [PMID: 33225418 PMCID: PMC7790789 DOI: 10.1007/s10735-020-09924-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022]
Abstract
Apoptosis and clearance of dead cells is highly evolutionarily conserved from nematode to humans, which is crucial to the growth and development of multicellular organism. Fail to remove apoptotic cells often lead to homeostasis imbalance, fatal autoimmune diseases, and neurodegenerative diseases. Small ubiquitin-related modifiers (SUMOs) modification is a post-translational modification of ubiquitin proteins mediated by the sentrin-specific proteases (SENPs) family. SUMO modification is widely involved in many cellular biological process, and abnormal SUMO modification is also closely related to many major human diseases. Recent researches have revealed that SUMO modification event occurs during apoptosis and clearance of apoptotic cells, and plays an important role in the regulation of apoptotic signaling pathways. This review summarizes some recent progress in the revelation of regulatory mechanisms of these pathways and provides some potential researching hotpots of the SUMO modification regulation to apoptosis.
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Affiliation(s)
- Peiyao Li
- 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, 710119, China
| | - Huiru Jing
- 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, 710119, China
| | - Yanzhe Wang
- 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, 710119, 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, 710119, China
| | - 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, 710119, China
| | - 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, 710119, China.
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13
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Ghose P, Wehman AM. The developmental and physiological roles of phagocytosis in Caenorhabditis elegans. Curr Top Dev Biol 2020; 144:409-432. [PMID: 33992160 DOI: 10.1016/bs.ctdb.2020.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Phagocytosis is an essential process by which cellular debris and pathogens are cleared from the environment. Cells extend their plasma membrane to engulf objects and contain them within a limiting membrane for isolation from the cytosol or for intracellular degradation in phagolysosomes. The basic mechanisms of phagocytosis and intracellular clearance are well conserved between animals. Indeed, much of our understanding is derived from studies on the nematode worm, Caenorhabditis elegans. Here, we review the latest progress in understanding the mechanisms and functions of phagocytic clearance from C. elegans studies. In particular, we highlight new insights into phagocytic signaling pathways, phagosome formation and phagolysosome resolution, as well as the challenges in studying these cyclic processes.
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Affiliation(s)
- Piya Ghose
- Department of Biology, University of Texas, Arlington, TX, United States.
| | - Ann M Wehman
- Department of Biological Sciences, University of Denver, Denver, CO, United States.
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14
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Fazeli G, Beer KB, Geisenhof M, Tröger S, König J, Müller-Reichert T, Wehman AM. Loss of the Major Phosphatidylserine or Phosphatidylethanolamine Flippases Differentially Affect Phagocytosis. Front Cell Dev Biol 2020; 8:648. [PMID: 32793595 PMCID: PMC7385141 DOI: 10.3389/fcell.2020.00648] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/29/2020] [Indexed: 12/31/2022] Open
Abstract
The lipids phosphatidylserine (PtdSer) and phosphatidylethanolamine (PtdEth) are normally asymmetrically localized to the cytosolic face of membrane bilayers, but can both be externalized during diverse biological processes, including cell division, cell fusion, and cell death. Externalized lipids in the plasma membrane are recognized by lipid-binding proteins to regulate the clearance of cell corpses and other cell debris. However, it is unclear whether PtdSer and PtdEth contribute in similar or distinct ways to these processes. We discovered that disruption of the lipid flippases that maintain PtdSer or PtdEth asymmetry in the plasma membrane have opposite effects on phagocytosis in Caenorhabditis elegans embryos. Constitutive PtdSer externalization caused by disruption of the major PtdSer flippase TAT-1 led to increased phagocytosis of cell debris, sometimes leading to two cells engulfing the same debris. In contrast, PtdEth externalization caused by depletion of the major PtdEth flippase TAT-5 or its activator PAD-1 disrupted phagocytosis. These data suggest that PtdSer and PtdEth externalization have opposite effects on phagocytosis. Furthermore, externalizing PtdEth is associated with increased extracellular vesicle release, and we present evidence that the extent of extracellular vesicle accumulation correlates with the extent of phagocytic defects. Thus, a general loss of lipid asymmetry can have opposing impacts through different lipid subtypes simultaneously exerting disparate effects.
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Affiliation(s)
- Gholamreza Fazeli
- Rudolf Virchow Center, University of Würzburg, Würzburg, Germany.,Imaging Core Facility, Biocenter, University of Würzburg, Würzburg, Germany
| | - Katharina B Beer
- Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | | | - Sarah Tröger
- Imaging Core Facility, Biocenter, University of Würzburg, Würzburg, Germany
| | - Julia König
- Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | | | - Ann M Wehman
- Rudolf Virchow Center, University of Würzburg, Würzburg, Germany.,Department of Biological Sciences, University of Denver, Denver, CO, United States
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15
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Lorent JH, Levental KR, Ganesan L, Rivera-Longsworth G, Sezgin E, Doktorova M, Lyman E, Levental I. Plasma membranes are asymmetric in lipid unsaturation, packing and protein shape. Nat Chem Biol 2020; 16:644-652. [PMID: 32367017 DOI: 10.1101/698837] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 03/27/2020] [Indexed: 05/26/2023]
Abstract
A fundamental feature of cellular plasma membranes (PMs) is an asymmetric lipid distribution between the bilayer leaflets. However, neither the detailed, comprehensive compositions of individual PM leaflets nor how these contribute to structural membrane asymmetries have been defined. We report the distinct lipidomes and biophysical properties of both monolayers in living mammalian PMs. Phospholipid unsaturation is dramatically asymmetric, with the cytoplasmic leaflet being approximately twofold more unsaturated than the exoplasmic leaflet. Atomistic simulations and spectroscopy of leaflet-selective fluorescent probes reveal that the outer PM leaflet is more packed and less diffusive than the inner leaflet, with this biophysical asymmetry maintained in the endocytic system. The structural asymmetry of the PM is reflected in the asymmetric structures of protein transmembrane domains. These structural asymmetries are conserved throughout Eukaryota, suggesting fundamental cellular design principles.
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Affiliation(s)
- J H Lorent
- McGovern Medical School, Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - K R Levental
- McGovern Medical School, Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - L Ganesan
- McGovern Medical School, Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
| | | | - E Sezgin
- John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
- SciLifeLab, Karolinska Institute, Stockholm, Sweden
| | - M Doktorova
- McGovern Medical School, Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
| | - E Lyman
- Department of Physics and Astronomy and Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - I Levental
- McGovern Medical School, Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA.
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16
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Zhang S, Liu W, Yang Y, Sun K, Li S, Xu H, Yang M, Zhang L, Zhu X. TMEM30A deficiency in endothelial cells impairs cell proliferation and angiogenesis. J Cell Sci 2019; 132:jcs.225052. [PMID: 30814335 DOI: 10.1242/jcs.225052] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 02/19/2019] [Indexed: 12/23/2022] Open
Abstract
Phosphatidylserine (PS) asymmetry in the eukaryotic cell membrane is maintained by a group of proteins belonging to the P4-ATPase family, namely, PS flippases. The folding and transporting of P4-ATPases to their cellular destination requires a β-subunit member of the TMEM30 protein family. Loss of Tmem30a has been shown to cause multiple disease conditions. However, its roles in vascular development have not been elucidated. Here, we show that TMEM30A plays critical roles in retinal vascular angiogenesis, which is a fundamental process in vascular development. Our data indicate that knockdown of TMEM30A in primary human retinal endothelial cells led to reduced tube formation. In mice, endothelial cell (EC)-specific deletion of Tmem30a led to retarded retinal vascular development with a hyperpruned vascular network as well as blunted-end, aneurysm-like tip ECs with fewer filopodia at the vascular front and a reduced number of tip cells. Deletion of Tmem30a also impaired vessel barrier integrity. Mechanistically, deletion of TMEM30A caused reduced EC proliferation by inhibiting VEGF-induced signaling. Our findings reveal essential roles of TMEM30A in angiogenesis, providing a potential therapeutic target.
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Affiliation(s)
- Shanshan Zhang
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China.,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Wenjing Liu
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China
| | - Yeming Yang
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China
| | - Kuanxiang Sun
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China.,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Shujin Li
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China
| | - Huijuan Xu
- Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Mu Yang
- Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Lin Zhang
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China .,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Xianjun Zhu
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China .,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China.,Department of Ophthalmology, Shangqiu First People's Hospital, Shangqiu, Henan, 476000, China.,Institute of Laboratory Animal Sciences, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610212, China
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17
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Chen YZ, Klöditz K, Lee ES, Nguyen DP, Yuan Q, Johnson J, Lee-Yow Y, Hall A, Mitani S, Xia NS, Fadeel B, Xue D. Structure and function analysis of the C. elegans aminophospholipid translocase TAT-1. J Cell Sci 2019; 132:jcs.227660. [PMID: 30683797 DOI: 10.1242/jcs.227660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 01/21/2019] [Indexed: 11/20/2022] Open
Abstract
The Caenorhabditis elegans aminophospholipid translocase TAT-1 maintains phosphatidylserine (PS) asymmetry in the plasma membrane and regulates endocytic transport. Despite these important functions, the structure-function relationship of this protein is poorly understood. Taking advantage of the tat-1 mutations identified by the C. elegans million mutation project, we investigated the effects of 16 single amino acid substitutions on the two functions of the TAT-1 protein. Two substitutions that alter a highly conserved PISL motif in the fourth transmembrane domain and a highly conserved DKTGT phosphorylation motif, respectively, disrupt both functions of TAT-1, leading to a vesicular gut defect and ectopic PS exposure on the cell surface, whereas most other substitutions across the TAT-1 protein, often predicted to be deleterious by bioinformatics programs, do not affect the functions of TAT-1. These results provide in vivo evidence for the importance of the PISL and DKTGT motifs in P4-type ATPases and improve our understanding of the structure-function relationship of TAT-1. Our study also provides an example of how the C. elegans million mutation project helps decipher the structure, functions, and mechanisms of action of important genes.
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Affiliation(s)
- Yu-Zen Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Katharina Klöditz
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm 17177, Sweden
| | - Eui-Seung Lee
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Diemmy Pham Nguyen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Quan Yuan
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen, Fujian 361005, China
| | - Jack Johnson
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Yannick Lee-Yow
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Adam Hall
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Shohei Mitani
- Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen, Fujian 361005, China
| | - Bengt Fadeel
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm 17177, Sweden
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
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18
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Shin HW, Takatsu H. Substrates of P4‐ATPases: beyond aminophospholipids (phosphatidylserine and phosphatidylethanolamine). FASEB J 2018; 33:3087-3096. [DOI: 10.1096/fj.201801873r] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hye-Won Shin
- Graduate School of Pharmaceutical SciencesKyoto University Kyoto Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical SciencesKyoto University Kyoto Japan
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19
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Disruption of Tmem30a results in cerebellar ataxia and degeneration of Purkinje cells. Cell Death Dis 2018; 9:899. [PMID: 30185775 PMCID: PMC6125289 DOI: 10.1038/s41419-018-0938-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 07/30/2018] [Accepted: 08/02/2018] [Indexed: 12/11/2022]
Abstract
Phospholipids are asymmetrically distributed across mammalian plasma membrane with phosphatidylserine (PS) and phosphatidylethanolamine concentrated in the cytoplasmic leaflet of the membrane bilayer. This asymmetric distribution is dependent on a group of P4-ATPases named PS flippases. The proper transport and function of PS flippases require a β-subunit transmembrane protein 30 A (TMEM30A). Disruption of PS flippases led to several human diseases. However, the roles of TMEM30A in the central nervous system remain elusive. To investigate the role of Tmem30a in the cerebellum, we developed a Tmem30a Purkinje cell (PC)-specific knockout (KO) mouse model. The Tmem30a KO mice displayed early-onset ataxia and progressive PC death. Deficiency in Tmem30a led to an increased expression of Glial fibrillary acidic protein and astrogliosis in regions with PC loss. Elevated C/EBP homologous protein and BiP expression levels indicated the presence of endoplasmic reticulum stress in the PCs prior to visible cell loss. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis suggested that apoptotic cell death occurred in the cerebellum. Our data demonstrate that loss of Tmem30a in PCs results in protein folding and transport defects, a substantial decrease in dendritic spine density, increased astrogliosis and PC death. Taken together, our data demonstrate an essential role of Tmem30a in the cerebellum PCs.
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20
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Abstract
Cell death is a perpetual feature of tissue microenvironments; each day under homeostatic conditions, billions of cells die and must be swiftly cleared by phagocytes. However, cell death is not limited to this natural turnover-apoptotic cell death can be induced by infection, inflammation, or severe tissue injury. Phagocytosis of apoptotic cells is thus coupled to specific functions, from the induction of growth factors that can stimulate the replacement of dead cells to the promotion of tissue repair or tissue remodeling in the affected site. In this review, we outline the mechanisms by which phagocytes sense apoptotic cell death and discuss how phagocytosis is integrated with environmental cues to drive appropriate responses.
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Affiliation(s)
- Lidia Bosurgi
- I. Medizinische Klinik und Poliklinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.,Bernard-Nocht-Institut für Tropenmedizin, Hamburg, Germany
| | - Lindsey D Hughes
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA
| | - Carla V Rothlin
- Department of Immunobiology, School of Medicine, Yale University, New Haven, CT, USA.,Department of Pharmacology, School of Medicine, Yale University, New Haven, CT, USA
| | - Sourav Ghosh
- Department of Pharmacology, School of Medicine, Yale University, New Haven, CT, USA.,Department of Neurology, School of Medicine, Yale University, New Haven, CT, USA
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21
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Li N, Yang Y, Liang C, Qiu Q, Pan C, Li M, Yang S, Chen L, Zhu X, Hu Y. Tmem30a Plays Critical Roles in Ensuring the Survival of Hematopoietic Cells and Leukemia Cells in Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:1457-1468. [PMID: 29574182 DOI: 10.1016/j.ajpath.2018.02.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 02/03/2018] [Accepted: 02/27/2018] [Indexed: 02/05/2023]
Abstract
The fundamental structure of eukaryotic cell plasma membrane is the phospholipid bilayer, which contains four major phospholipids. These phospholipids are asymmetrically distributed between the outer and inner leaflets. P4-ATPase flippase complexes play essential roles in ensuring this asymmetry. We found that conditional deletion of Tmem30a, the β subunit of P4-ATPase flippase complex, caused pancytopenia in mice. Tmem30a deficiency resulted in depletion of lineage-committed blood cells in the peripheral blood, spleen, and bone marrow. Ablation of Tmem30a also caused the depletion of hematopoietic stem cells (HSCs). HSC RNA sequencing results revealed that multiple biological processes and signal pathways were involved in the event, including mammalian target of rapamycin signaling, genes for HSC stemness, and genes responding to interferons. Our results also revealed that targeting Tmem30a signaling had therapeutic utility in BCR/ABL1-induced chronic myeloid leukemia.
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Affiliation(s)
- Ning Li
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Cailing Liang
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Qiang Qiu
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Cong Pan
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Mengyuan Li
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Shengyong Yang
- State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lijuan Chen
- State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China.
| | - Yiguo Hu
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
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22
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Abstract
The human body generates 10-100 billion cells every day, and the same number of cells die to maintain homeostasis in our body. Cells infected by bacteria or viruses also die. The cell death that occurs under physiological conditions mainly proceeds by apoptosis, which is a noninflammatory, or silent, process, while pathogen infection induces necroptosis or pyroptosis, which activates the immune system and causes inflammation. Dead cells generated by apoptosis are quickly engulfed by macrophages for degradation. Caspases are a large family of cysteine proteases that act in cascades. A cascade that leads to caspase 3 activation mediates apoptosis and is responsible for killing cells, recruiting macrophages, and presenting an "eat me" signal(s). When apoptotic cells are not efficiently engulfed by macrophages, they undergo secondary necrosis and release intracellular materials that represent a damage-associated molecular pattern, which may lead to a systemic lupus-like autoimmune disease.
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Affiliation(s)
- Shigekazu Nagata
- Laboratory of Biochemistry and Immunology, World Premier International Research Center Initiative Immunology Frontier Research Center, Osaka University, Osaka 565-0871, Japan;
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23
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Watts JL, Ristow M. Lipid and Carbohydrate Metabolism in Caenorhabditis elegans. Genetics 2017; 207:413-446. [PMID: 28978773 PMCID: PMC5629314 DOI: 10.1534/genetics.117.300106] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/02/2017] [Indexed: 12/14/2022] Open
Abstract
Lipid and carbohydrate metabolism are highly conserved processes that affect nearly all aspects of organismal biology. Caenorhabditis elegans eat bacteria, which consist of lipids, carbohydrates, and proteins that are broken down during digestion into fatty acids, simple sugars, and amino acid precursors. With these nutrients, C. elegans synthesizes a wide range of metabolites that are required for development and behavior. In this review, we outline lipid and carbohydrate structures as well as biosynthesis and breakdown pathways that have been characterized in C. elegans We bring attention to functional studies using mutant strains that reveal physiological roles for specific lipids and carbohydrates during development, aging, and adaptation to changing environmental conditions.
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Affiliation(s)
- Jennifer L Watts
- School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, Pullman, Washington 99164
| | - Michael Ristow
- Energy Metabolism Laboratory, Institute of Translational Medicine, Department of Health Sciences and Technology, Swiss Federal Institute of Technology Zurich, 8603 Schwerzenbach-Zurich, Switzerland
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24
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Zhang L, Yang Y, Li S, Zhang S, Zhu X, Tai Z, Yang M, Liu Y, Guo X, Chen B, Jiang Z, Lu F, Zhu X. Loss of Tmem30a leads to photoreceptor degeneration. Sci Rep 2017; 7:9296. [PMID: 28839191 PMCID: PMC5571223 DOI: 10.1038/s41598-017-09506-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/26/2017] [Indexed: 12/16/2022] Open
Abstract
Phosphatidylserine (PS) is asymmetrically distributed between the outer and inner leaflets of the plasma membrane in eukaryotic cells. PS asymmetry on the plasma membrane depends on the activities of P4-ATPases, and disruption of PS distribution can lead to various disease conditions. Folding and transporting of P4-ATPases to their cellular destination requires the β subunit TMEM30A proteins. However, the in vivo functions of Tmem30a remain unknown. To this end, we generated retinal-specific Tmem30a-knockout mice to investigate its roles in vivo for the first time. Our data demonstrated that loss of Tmem30a in mouse cone cells leads to mislocalization of cone opsin, loss of photopic electroretinogram (ERG) responses and loss of cone cells. Mechanistically, Tmem30a-mutant mouse embryonic fibroblasts (MEFs) exhibited diminished PS flippase activity and increased exposure of PS on the cell surface. The broad loss of Tmem30a in adult mice led to a reduced scotopic photoresponse, mislocalization of ATP8A2 to the inner segment and cell body, and increased apoptosis in the retina. Our data demonstrated novel essential roles of Tmem30a in the retina.
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Affiliation(s)
- Lin Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Shujin Li
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Shanshan Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Xiong Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Zhengfu Tai
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Mu Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Yuqing Liu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Xinzheng Guo
- Department of Ophthalmology, Yale University School of Medicine, New Haven, CT, USA
| | - Bo Chen
- Department of Ophthalmology, Yale University School of Medicine, New Haven, CT, USA
| | - Zhilin Jiang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Fang Lu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China. .,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China. .,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China. .,Institute of Laboratory Animal Sciences, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China. .,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China.
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25
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Programmed Cell Death During Caenorhabditis elegans Development. Genetics 2017; 203:1533-62. [PMID: 27516615 DOI: 10.1534/genetics.115.186247] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/22/2016] [Indexed: 12/21/2022] Open
Abstract
Programmed cell death is an integral component of Caenorhabditis elegans development. Genetic and reverse genetic studies in C. elegans have led to the identification of many genes and conserved cell death pathways that are important for the specification of which cells should live or die, the activation of the suicide program, and the dismantling and removal of dying cells. Molecular, cell biological, and biochemical studies have revealed the underlying mechanisms that control these three phases of programmed cell death. In particular, the interplay of transcriptional regulatory cascades and networks involving multiple transcriptional regulators is crucial in activating the expression of the key death-inducing gene egl-1 and, in some cases, the ced-3 gene in cells destined to die. A protein interaction cascade involving EGL-1, CED-9, CED-4, and CED-3 results in the activation of the key cell death protease CED-3, which is tightly controlled by multiple positive and negative regulators. The activation of the CED-3 caspase then initiates the cell disassembly process by cleaving and activating or inactivating crucial CED-3 substrates; leading to activation of multiple cell death execution events, including nuclear DNA fragmentation, mitochondrial elimination, phosphatidylserine externalization, inactivation of survival signals, and clearance of apoptotic cells. Further studies of programmed cell death in C. elegans will continue to advance our understanding of how programmed cell death is regulated, activated, and executed in general.
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MITANI S. Comprehensive functional genomics using Caenorhabditis elegans as a model organism. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2017; 93:561-577. [PMID: 29021508 PMCID: PMC5743858 DOI: 10.2183/pjab.93.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
We have been working on functional genomics using C. elegans as a model organism. We first used cell-type specific markers and preexisting mutants to investigate how genotype-phenotype causal relationships are regulated. With the aid of transgenic methods, we analyzed various biological processes in C. elegans. We have developed efficient methods to isolate gene knockout strains. Thousands of strains isolated this way are used by many researchers and have revealed many biological mechanisms. We have also developed methods to examine the functions of genes in a comprehensive manner by integrating transgenes into chromosomes, designing conditional knockouts, and creating balancers for lethal mutations. A combination of these biological resources and techniques will be useful to understand the functions of genes in C. elegans, which has many genes that are orthologous to those of higher organisms including humans.
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Affiliation(s)
- Shohei MITANI
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, Tokyo, Japan
- Tokyo Women’s Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
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27
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Klöditz K, Chen YZ, Xue D, Fadeel B. Programmed cell clearance: From nematodes to humans. Biochem Biophys Res Commun 2016; 482:491-497. [PMID: 27919685 DOI: 10.1016/j.bbrc.2016.12.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 12/01/2016] [Indexed: 11/30/2022]
Abstract
Programmed cell clearance is a highly regulated physiological process of elimination of dying cells that occurs rapidly and efficiently in healthy organisms. It thus ensures proper development as well as homeostasis. Recent studies have disclosed a considerable degree of conservation of cell clearance pathways between nematodes and higher organisms. The externalization of the anionic phospholipid phosphatidylserine (PS) has emerged as an important "eat-me" signal for phagocytes and its exposition on apoptotic cells is controlled by phospholipid translocases and scramblases. However, there is mounting evidence that PS exposure occurs not only in apoptosis, but may also be actively expressed on the surface of cells undergoing other forms of cell death including necrosis; PS is also expressed on the surface of engulfing cells. Additionally, PS may act as a "save-me" signal during axonal regeneration. Here we discuss mechanisms of PS exposure and its recognition by phagocytes as well as the consequences of PS signaling in nematodes and in mammals.
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Affiliation(s)
- Katharina Klöditz
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Yu-Zen Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Bengt Fadeel
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177, Stockholm, Sweden.
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28
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Beer KB, Wehman AM. Mechanisms and functions of extracellular vesicle release in vivo-What we can learn from flies and worms. Cell Adh Migr 2016; 11:135-150. [PMID: 27689411 PMCID: PMC5351733 DOI: 10.1080/19336918.2016.1236899] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cells from bacteria to man release extracellular vesicles (EVs) that contain signaling molecules like proteins, lipids, and nucleic acids. The content, formation, and signaling roles of these conserved vesicles are diverse, but the physiological relevance of EV signaling in vivo is still debated. Studies in classical genetic model organisms like C. elegans and Drosophila have begun to reveal the developmental and behavioral roles for EVs. In this review, we discuss the emerging evidence for the in vivo signaling roles of EVs. Significant effort has also been made to understand the mechanisms behind the formation and release of EVs, specifically of exosomes derived from exocytosis of multivesicular bodies and of microvesicles derived from plasma membrane budding called ectocytosis. In this review, we detail the impact of flies and worms on understanding the proteins and lipids involved in EV biogenesis and highlight the open questions in the field.
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Affiliation(s)
- Katharina B Beer
- a Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg , Würzburg , Germany
| | - Ann Marie Wehman
- a Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg , Würzburg , Germany
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29
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Wang X, Yang C. Programmed cell death and clearance of cell corpses in Caenorhabditis elegans. Cell Mol Life Sci 2016; 73:2221-36. [PMID: 27048817 PMCID: PMC11108496 DOI: 10.1007/s00018-016-2196-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 01/01/2023]
Abstract
Programmed cell death is critical to the development of diverse animal species from C. elegans to humans. In C. elegans, the cell death program has three genetically distinguishable phases. During the cell suicide phase, the core cell death machinery is activated through a protein interaction cascade. This activates the caspase CED-3, which promotes numerous pro-apoptotic activities including DNA degradation and exposure of the phosphatidylserine "eat me" signal on the cell corpse surface. Specification of the cell death fate involves transcriptional activation of the cell death initiator EGL-1 or the caspase CED-3 by coordinated actions of specific transcription factors in distinct cell types. In the cell corpse clearance stage, recognition of cell corpses by phagocytes triggers several signaling pathways to induce phagocytosis of apoptotic cell corpses. Cell corpse-enclosing phagosomes ultimately fuse with lysosomes for digestion of phagosomal contents. This article summarizes our current knowledge about programmed cell death and clearance of cell corpses in C. elegans.
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Affiliation(s)
- Xiaochen Wang
- National Institute of Biological Sciences, No. 7 Science Park Road, Zhongguancun Life Science Park, Beijing, 102206, China.
| | - Chonglin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing, 100101, China.
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30
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Bevers EM, Williamson PL. Getting to the Outer Leaflet: Physiology of Phosphatidylserine Exposure at the Plasma Membrane. Physiol Rev 2016; 96:605-45. [PMID: 26936867 DOI: 10.1152/physrev.00020.2015] [Citation(s) in RCA: 287] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylserine (PS) is a major component of membrane bilayers whose change in distribution between inner and outer leaflets is an important physiological signal. Normally, members of the type IV P-type ATPases spend metabolic energy to create an asymmetric distribution of phospholipids between the two leaflets, with PS confined to the cytoplasmic membrane leaflet. On occasion, membrane enzymes, known as scramblases, are activated to facilitate transbilayer migration of lipids, including PS. Recently, two proteins required for such randomization have been identified: TMEM16F, a scramblase regulated by elevated intracellular Ca(2+), and XKR8, a caspase-sensitive protein required for PS exposure in apoptotic cells. Once exposed at the cell surface, PS regulates biochemical reactions involved in blood coagulation, and bone mineralization, and also regulates a variety of cell-cell interactions. Exposed on the surface of apoptotic cells, PS controls their recognition and engulfment by other cells. This process is exploited by parasites to invade their host, and in specialized form is used to maintain photoreceptors in the eye and modify synaptic connections in the brain. This review discusses what is known about the mechanism of PS exposure at the surface of the plasma membrane of cells, how actors in the extracellular milieu sense surface exposed PS, and how this recognition is translated to downstream consequences of PS exposure.
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Affiliation(s)
- Edouard M Bevers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands; and Department of Biology, Amherst College, Amherst, Massachusetts
| | - Patrick L Williamson
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands; and Department of Biology, Amherst College, Amherst, Massachusetts
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31
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Nichols ALA, Meelkop E, Linton C, Giordano-Santini R, Sullivan RK, Donato A, Nolan C, Hall DH, Xue D, Neumann B, Hilliard MA. The Apoptotic Engulfment Machinery Regulates Axonal Degeneration in C. elegans Neurons. Cell Rep 2016; 14:1673-1683. [PMID: 26876181 PMCID: PMC4821572 DOI: 10.1016/j.celrep.2016.01.050] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/23/2015] [Accepted: 01/13/2016] [Indexed: 01/31/2023] Open
Abstract
Axonal degeneration is a characteristic feature of neurodegenerative disease and nerve injury. Here, we characterize axonal degeneration in Caenorhabditis elegans neurons following laser-induced axotomy. We show that this process proceeds independently of the WLD(S) and Nmnat pathway and requires the axonal clearance machinery that includes the conserved transmembrane receptor CED-1/Draper, the adaptor protein CED-6, the guanine nucleotide exchange factor complex Crk/Mbc/dCed-12 (CED-2/CED-5/CED-12), and the small GTPase Rac1 (CED-10). We demonstrate that CED-1 and CED-6 function non-cell autonomously in the surrounding hypodermis, which we show acts as the engulfing tissue for the severed axon. Moreover, we establish a function in this process for CED-7, an ATP-binding cassette (ABC) transporter, and NRF-5, a lipid-binding protein, both associated with release of lipid-vesicles during apoptotic cell clearance. Thus, our results reveal the existence of a WLD(S)/Nmnat-independent axonal degeneration pathway, conservation of the axonal clearance machinery, and a function for CED-7 and NRF-5 in this process.
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Affiliation(s)
- Annika L A Nichols
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ellen Meelkop
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Casey Linton
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Robert K Sullivan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Alessandra Donato
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cara Nolan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David H Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ding Xue
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Brent Neumann
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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32
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Nagata S, Suzuki J, Segawa K, Fujii T. Exposure of phosphatidylserine on the cell surface. Cell Death Differ 2016; 23:952-61. [PMID: 26891692 DOI: 10.1038/cdd.2016.7] [Citation(s) in RCA: 300] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/11/2016] [Indexed: 12/15/2022] Open
Abstract
Phosphatidylserine (PtdSer) is a phospholipid that is abundant in eukaryotic plasma membranes. An ATP-dependent enzyme called flippase normally keeps PtdSer inside the cell, but PtdSer is exposed by the action of scramblase on the cell's surface in biological processes such as apoptosis and platelet activation. Once exposed to the cell surface, PtdSer acts as an 'eat me' signal on dead cells, and creates a scaffold for blood-clotting factors on activated platelets. The molecular identities of the flippase and scramblase that work at plasma membranes have long eluded researchers. Indeed, their identity as well as the mechanism of the PtdSer exposure to the cell surface has only recently been revealed. Here, we describe how PtdSer is exposed in apoptotic cells and in activated platelets, and discuss PtdSer exposure in other biological processes.
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Affiliation(s)
- S Nagata
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - J Suzuki
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - K Segawa
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - T Fujii
- Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
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33
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Yabas M, Jing W, Shafik S, Bröer S, Enders A. ATP11C Facilitates Phospholipid Translocation across the Plasma Membrane of All Leukocytes. PLoS One 2016; 11:e0146774. [PMID: 26799398 PMCID: PMC4723305 DOI: 10.1371/journal.pone.0146774] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 12/22/2015] [Indexed: 12/12/2022] Open
Abstract
Organization of the plasma membrane into specialized substructures in different blood lineages facilitates important biological functions including proper localization of receptors at the plasma membrane as well as the initiation of crucial intracellular signaling cascades. The eukaryotic plasma membrane is a lipid bilayer that consists of asymmetrically distributed phospholipids. This asymmetry is actively maintained by membrane-embedded lipid transporters, but there is only limited data available about the molecular identity of the predominantly active transporters and their substrate specificity in different leukocyte subsets. We demonstrate here that the P4-type ATPase ATP11C mediates significant flippase activity in all murine leukocyte subsets. Loss of ATP11C resulted in a defective internalization of phosphatidylserine (PS) and phosphatidylethanolamine (PE) in comparison to control cells. The diminished flippase activity caused increased PS exposure on 7-aminoactinomycin D- (7-AAD-) viable pro-B cells freshly isolated from the bone marrow of ATP11C-deficient mice, which was corrected upon a 2-hour resting period in vitro. Despite the impaired flippase activity in all immune cell subsets, the only other blood cell type with an accumulation of PS on the surface were viable 7-AAD- developing T cells but this did not result in any discernable effect on their development in the thymus. These findings show that all leukocyte lineages exhibit flippase activity, and identify ATP11C as an aminophospholipid translocase in immune cells.
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Affiliation(s)
- Mehmet Yabas
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
- Department of Genetics and Bioengineering, Faculty of Engineering, Trakya University, Edirne, Turkey
| | - Weidong Jing
- Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Sarah Shafik
- Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Stefan Bröer
- Division of Biomedical Science and Biochemistry, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Anselm Enders
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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34
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Montigny C, Lyons J, Champeil P, Nissen P, Lenoir G. On the molecular mechanism of flippase- and scramblase-mediated phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:767-783. [PMID: 26747647 DOI: 10.1016/j.bbalip.2015.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
Phospholipid flippases are key regulators of transbilayer lipid asymmetry in eukaryotic cell membranes, critical to many trafficking and signaling pathways. P4-ATPases, in particular, are responsible for the uphill transport of phospholipids from the exoplasmic to the cytosolic leaflet of the plasma membrane, as well as membranes of the late secretory/endocytic pathways, thereby establishing transbilayer asymmetry. Recent studies combining cell biology and biochemical approaches have improved our understanding of the path taken by lipids through P4-ATPases. Additionally, identification of several protein families catalyzing phospholipid 'scrambling', i.e. disruption of phospholipid asymmetry through energy-independent bi-directional phospholipid transport, as well as the recent report of the structure of such a scramblase, opens the way to a deeper characterization of their mechanism of action. Here, we discuss the molecular nature of the mechanism by which lipids may 'flip' across membranes, with an emphasis on active lipid transport catalyzed by P4-ATPases. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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Affiliation(s)
- Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Joseph Lyons
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Philippe Champeil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Poul Nissen
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
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35
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Phagocytosis of apoptotic cells in homeostasis. Nat Immunol 2015; 16:907-17. [PMID: 26287597 DOI: 10.1038/ni.3253] [Citation(s) in RCA: 556] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/17/2015] [Indexed: 02/07/2023]
Abstract
Human bodies collectively turn over about 200 billion to 300 billion cells every day. Such turnover is an integral part of embryonic and postnatal development, as well as routine tissue homeostasis. This process involves the induction of programmed cell death in specific cells within the tissues and the specific recognition and removal of dying cells by a clearance 'crew' composed of professional, non-professional and specialized phagocytes. In the past few years, considerable progress has been made in identifying many features of apoptotic cell clearance. Some of these new observations challenge the way dying cells themselves are viewed, as well as how healthy cells interact with and respond to dying cells. Here we focus on the homeostatic removal of apoptotic cells in tissues.
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36
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Korneenko TV, Pestov NB, Okkelman IA, Modyanov NN, Shakhparonov MI. [P4-ATP-ase Atp8b1/FIC1: structural properties and (patho)physiological functions]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2015; 41:3-12. [PMID: 26050466 DOI: 10.1134/s1068162015010070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
P4-ATP-ases comprise an interesting family among P-type ATP-ases, since they are thought to play a major role in the transfer of phospholipids such as phosphatydylserine from the outer leaflet to the inner leaflet. Isoforms of P4-ATP-ases are partially interchangeable but peculiarities of tissue-specific expression of their genes, intracellular localization of proteins, as well as regulatory pathways lead to the fact that, on the organismal level, serious pathologies may develop in the presence of structural abnormalities in certain isoforms. Among P4-ATP-ases a special place is occupied by ATP8B1, for which several mutations are known that lead to serious hereditary diseases: two forms of congenital cholestasis (PFIC1 or Byler disease and benign recurrent intrahepatic cholestasis) with extraliver symptoms such as sensorineural hearing loss. The physiological function of the Atp8b1/FIC1 protein is known in general outline: it is responsible for transport of certain phospholipids (phosphatydylserine, cardiolipin) for the outer monolayer of the plasma membrane to the inner one. It is well known that perturbation of membrane asymmetry, caused by the lack of Atp8B1 activity, leads to death of hairy cells of the inner ear, dysfunction of bile acid transport in liver-cells that causes cirrhosis. It is also probable that insufficient activity of Atp8b1/FIC1 increases susceptibility to bacterial pneumonia.Regulatory pathways of Atp8b1/FIC1 activity in vivo remain to be insufficiently studied and this opens novel perspectives for research in this field that may allow better understanding of molecular processes behind the development of certain pathologies and to reveal novel therapeutical targets.
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37
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Panatala R, Hennrich H, Holthuis JCM. Inner workings and biological impact of phospholipid flippases. J Cell Sci 2015; 128:2021-32. [PMID: 25918123 DOI: 10.1242/jcs.102715] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The plasma membrane, trans-Golgi network and endosomal system of eukaryotic cells are populated with flippases that hydrolyze ATP to help establish asymmetric phospholipid distributions across the bilayer. Upholding phospholipid asymmetry is vital to a host of cellular processes, including membrane homeostasis, vesicle biogenesis, cell signaling, morphogenesis and migration. Consequently, defining the identity of flippases and their biological impact has been the subject of intense investigations. Recent work has revealed a remarkable degree of kinship between flippases and cation pumps. In this Commentary, we review emerging insights into how flippases work, how their activity is controlled according to cellular demands, and how disrupting flippase activity causes system failure of membrane function, culminating in membrane trafficking defects, aberrant signaling and disease.
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Affiliation(s)
- Radhakrishnan Panatala
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
| | - Hanka Hennrich
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands
| | - Joost C M Holthuis
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
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38
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P4-ATPases: lipid flippases in cell membranes. Pflugers Arch 2015; 466:1227-40. [PMID: 24077738 PMCID: PMC4062807 DOI: 10.1007/s00424-013-1363-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 09/11/2013] [Accepted: 09/11/2013] [Indexed: 12/13/2022]
Abstract
Cellular membranes, notably eukaryotic plasma membranes, are equipped with special proteins that actively translocate lipids from one leaflet to the other and thereby help generate membrane lipid asymmetry. Among these ATP-driven transporters, the P4 subfamily of P-type ATPases (P4-ATPases) comprises lipid flippases that catalyze the translocation of phospholipids from the exoplasmic to the cytosolic leaflet of cell membranes. While initially characterized as aminophospholipid translocases, recent studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates, including lysophospholipids and synthetic alkylphospholipids. At the same time, the cellular processes known to be directly or indirectly affected by this class of transporters have expanded to include the regulation of membrane traffic, cytoskeletal dynamics, cell division, lipid metabolism, and lipid signaling. In this review, we will summarize the basic features of P4-ATPases and the physiological implications of their lipid transport activity in the cell.
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39
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Yang H, Chen YZ, Zhang Y, Wang X, Zhao X, Godfroy JI, Liang Q, Zhang M, Zhang T, Yuan Q, Ann Royal M, Driscoll M, Xia NS, Yin H, Xue D. A lysine-rich motif in the phosphatidylserine receptor PSR-1 mediates recognition and removal of apoptotic cells. Nat Commun 2015; 6:5717. [PMID: 25564762 PMCID: PMC4306451 DOI: 10.1038/ncomms6717] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 10/31/2014] [Indexed: 02/02/2023] Open
Abstract
The conserved phosphatidylserine receptor (PSR) was first identified as a receptor for phosphatidylserine, an 'eat-me' signal exposed by apoptotic cells. However, several studies suggest that PSR may also act as an arginine demethylase, a lysyl hydroxylase, or an RNA-binding protein through its N-terminal JmjC domain. How PSR might execute drastically different biochemical activities, and whether they are physiologically significant, remain unclear. Here we report that a lysine-rich motif in the extracellular domain of PSR-1, the Caenorhabditis elegans PSR, mediates specific phosphatidylserine binding in vitro and clearance of apoptotic cells in vivo. This motif also mediates phosphatidylserine-induced oligomerization of PSR-1, suggesting a mechanism by which PSR-1 activates phagocytosis. Mutations in the phosphatidylserine-binding motif, but not in its Fe(II) binding site critical for the JmjC activity, abolish PSR-1 phagocytic function. Moreover, PSR-1 enriches and clusters around apoptotic cells during apoptosis. These results establish that PSR-1 is a conserved, phosphatidylserine-recognizing phagocyte receptor.
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Affiliation(s)
- Hengwen Yang
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Yu-Zen Chen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA
| | - Yi Zhang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaohui Wang
- Department of Chemistry &Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA
| | - Xiang Zhao
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - James I Godfroy
- Department of Chemistry &Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA
| | - Qian Liang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Man Zhang
- School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Tianying Zhang
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen 361102, China
| | - Quan Yuan
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen 361102, China
| | - Mary Ann Royal
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - Ning-Shao Xia
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, Xiamen University, Xiamen 361102, China
| | - Hang Yin
- 1] Department of Chemistry &Biochemistry and BioFrontiers Institute, University of Colorado, Boulder, Colorado 80309, USA [2] Center of Basic Molecular Science and Department of Chemistry, Tsinghua University, Beijing 100082, China
| | - Ding Xue
- 1] Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado 80309, USA [2] School of Life Sciences, Tsinghua University, Beijing 100084, China
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40
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Kumar A, Kumar S, Rhim WK, Kim GH, Nam JM. Oxidative Nanopeeling Chemistry-Based Synthesis and Photodynamic and Photothermal Therapeutic Applications of Plasmonic Core-Petal Nanostructures. J Am Chem Soc 2014; 136:16317-25. [DOI: 10.1021/ja5085699] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Amit Kumar
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
| | - Sumit Kumar
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
| | - Won-Kyu Rhim
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
| | - Gyeong-Hwan Kim
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
| | - Jwa-Min Nam
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
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41
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Zhu H, Han M. Exploring developmental and physiological functions of fatty acid and lipid variants through worm and fly genetics. Annu Rev Genet 2014; 48:119-48. [PMID: 25195508 DOI: 10.1146/annurev-genet-041814-095928] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Lipids are more than biomolecules for energy storage and membrane structure. With ample structural variation, lipids critically participate in nearly all aspects of cellular function. Lipid homeostasis and metabolism are closely related to major human diseases and health problems. However, lipid functional studies have been significantly underdeveloped, partly because of the difficulty in applying genetics and common molecular approaches to tackle the complexity associated with lipid biosynthesis, metabolism, and function. In the past decade, a number of laboratories began to analyze the roles of lipid metabolism in development and other physiological functions using animal models and combining genetics, genomics, and biochemical approaches. These pioneering efforts have not only provided valuable insights regarding lipid functions in vivo but have also established feasible methodology for future studies. Here, we review a subset of these studies using Caenorhabditis elegans and Drosophila melanogaster.
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Affiliation(s)
- Huanhu Zhu
- Howard Hughes Medical Institute and Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309;
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42
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Caspase-mediated activation of Caenorhabditis elegans CED-8 promotes apoptosis and phosphatidylserine externalization. Nat Commun 2014; 4:2726. [PMID: 24225442 PMCID: PMC3939056 DOI: 10.1038/ncomms3726] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Accepted: 10/08/2013] [Indexed: 02/04/2023] Open
Abstract
During apoptosis, phosphatidylserine (PS), normally restricted to the inner leaflet of the plasma membrane, is exposed on the surface of apoptotic cells and serves as an “eat-me” signal to trigger phagocytosis. It is poorly understood how PS exposure is activated in apoptotic cells. Here we report that CED-8, a C. elegans protein implicated in controlling the kinetics of apoptosis and a homolog of the XK family proteins, is a substrate of the CED-3 caspase. Cleavage of CED-8 by CED-3 activates its proapoptotic function and generates a carboxyl terminal cleavage product, acCED-8, that promotes PS externalization in apoptotic cells and can induce ectopic PS exposure in living cells. Consistent with its role in promoting PS externalization in apoptotic cells, ced-8 is important for cell corpse engulfment in C. elegans. Our finding identifies a crucial link between caspase activation and PS externalization, which triggers phagocytosis of apoptotic cells.
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43
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Segawa K, Kurata S, Yanagihashi Y, Brummelkamp TR, Matsuda F, Nagata S. Caspase-mediated cleavage of phospholipid flippase for apoptotic phosphatidylserine exposure. Science 2014; 344:1164-8. [PMID: 24904167 DOI: 10.1126/science.1252809] [Citation(s) in RCA: 370] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Phospholipids are asymmetrically distributed in the plasma membrane. This asymmetrical distribution is disrupted during apoptosis, exposing phosphatidylserine (PtdSer) on the cell surface. Using a haploid genetic screen in human cells, we found that ATP11C (adenosine triphosphatase type 11C) and CDC50A (cell division cycle protein 50A) are required for aminophospholipid translocation from the outer to the inner plasma membrane leaflet; that is, they display flippase activity. ATP11C contained caspase recognition sites, and mutations at these sites generated caspase-resistant ATP11C without affecting its flippase activity. Cells expressing caspase-resistant ATP11C did not expose PtdSer during apoptosis and were not engulfed by macrophages, which suggests that inactivation of the flippase activity is required for apoptotic PtdSer exposure. CDC50A-deficient cells displayed PtdSer on their surface and were engulfed by macrophages, indicating that PtdSer is sufficient as an "eat me" signal.
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Affiliation(s)
- Katsumori Segawa
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Kyoto 606-8501, Japan
| | - Sachiko Kurata
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Kyoto 606-8501, Japan
| | - Yuichi Yanagihashi
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Kyoto 606-8501, Japan
| | - Thijn R Brummelkamp
- Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, Netherlands
| | - Fumihiko Matsuda
- Center for Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Kyoto 606-8501, Japan
| | - Shigekazu Nagata
- Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Kyoto 606-8501, Japan. Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Kyoto 606-8501, Japan.
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44
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Xu M, Liu Y, Zhao L, Gan Q, Wang X, Yang C. The lysosomal cathepsin protease CPL-1 plays a leading role in phagosomal degradation of apoptotic cells in Caenorhabditis elegans. Mol Biol Cell 2014; 25:2071-83. [PMID: 24829385 PMCID: PMC4072580 DOI: 10.1091/mbc.e14-01-0015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
In Caenorhabditis elegans, the lysosomal cathepsin protease CPL-1 is indispensable for clearance of apoptotic cells by playing a leading role in destruction of cell corpses in phagolysosomes. During programmed cell death, the clearance of apoptotic cells is achieved by their phagocytosis and delivery to lysosomes for destruction in engulfing cells. However, the role of lysosomal proteases in cell corpse destruction is not understood. Here we report the identification of the lysosomal cathepsin CPL-1 as an indispensable protease for apoptotic cell removal in Caenorhabditis elegans. We find that loss of cpl-1 function leads to strong accumulation of germ cell corpses, which results from a failure in degradation rather than engulfment. CPL-1 is expressed in a variety of cell types, including engulfment cells, and its mutation does not affect the maturation of cell corpse–containing phagosomes, including phagosomal recruitment of maturation effectors and phagosome acidification. Of importance, we find that phagosomal recruitment and incorporation of CPL-1 occurs before digestion of cell corpses, which depends on factors required for phagolysosome formation. Using RNA interference, we further examine the role of other candidate lysosomal proteases in cell corpse clearance but find that they do not obviously affect this process. Collectively, these findings establish CPL-1 as the leading lysosomal protease required for elimination of apoptotic cells in C. elegans.
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Affiliation(s)
- Meng Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, ChinaGraduate University of Chinese Academy of Sciences, Beijing 100109, China
| | - Yubing Liu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Liyuan Zhao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, ChinaGraduate University of Chinese Academy of Sciences, Beijing 100109, China
| | - Qiwen Gan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, ChinaGraduate University of Chinese Academy of Sciences, Beijing 100109, China
| | - Xiaochen Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Chonglin Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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45
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Lipid flippase modulates olfactory receptor expression and odorant sensitivity in Drosophila. Proc Natl Acad Sci U S A 2014; 111:7831-6. [PMID: 24821794 DOI: 10.1073/pnas.1401938111] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In Drosophila melanogaster, the male-specific pheromone cVA (11-cis-vaccenyl acetate) functions as a sex-specific social cue. However, our understanding of the molecular mechanisms underlying cVA pheromone transduction and its regulation are incomplete. Using a genetic screen combined with an electrophysiological assay to monitor pheromone-evoked activity in the cVA-sensing Or67d neurons, we identified an olfactory sensitivity factor encoded by the dATP8B gene, the Drosophila homolog of mammalian ATP8B. dATP8B is expressed in all olfactory neurons that express Orco, the odorant receptor coreceptor, and the odorant responses in most Orco-expressing neurons are reduced. Or67d neurons are severely affected, with strongly impaired cVA-induced responses and lacking spontaneous spiking in the mutants. The dATP8B locus encodes a member of the P4-type ATPase family thought to flip aminophospholipids such as phosphatidylserine and phosphatidylethanolamine from one membrane leaflet to the other. dATP8B protein is concentrated in the cilia of olfactory neuron dendrites, the site of odorant transduction. Focusing on Or67d neuron function, we show that Or67d receptors are mislocalized in dATP8B mutants and that cVA responses can be restored to dATP8B mutants by misexpressing a wild-type dATP8B rescuing transgene, by expressing a vertebrate P4-type ATPase member in the pheromone-sensing neurons or by overexpressing Or67d receptor subunits. These findings reveal an unexpected role for lipid translocation in olfactory receptor expression and sensitivity to volatile odorants.
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Abstract
Microglia, the brain's professional phagocytes, can remove dead and dying neurons as well as synapses and the processes of live neurons. However, we and others have recently shown that microglia can also execute neuronal death by phagocytosing stressed-but-viable neurons - a process that we have termed phagoptosis. In this Progress article, we discuss evidence suggesting that phagoptosis may contribute to neuronal loss during brain development, inflammation, ischaemia and neurodegeneration.
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47
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Abstract
The counterbalancing action of the endocytosis and secretory pathways maintains a dynamic equilibrium that regulates the composition of the plasma membrane, allowing it to maintain homeostasis and to change rapidly in response to alterations in the extracellular environment and/or intracellular metabolism. These pathways are intimately integrated with intercellular signaling systems and play critical roles in all cells. Studies in Caenorhabditis elegans have revealed diverse roles of membrane trafficking in physiology and development and have also provided molecular insight into the fundamental mechanisms that direct cargo sorting, vesicle budding, and membrane fisson and fusion. In this review, we summarize progress in understanding membrane trafficking mechanisms derived from work in C. elegans, focusing mainly on work done in non-neuronal cell-types, especially the germline, early embryo, coelomocytes, and intestine.
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Affiliation(s)
- Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan. ;
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48
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Structure and mechanism of ATP-dependent phospholipid transporters. Biochim Biophys Acta Gen Subj 2014; 1850:461-75. [PMID: 24746984 DOI: 10.1016/j.bbagen.2014.04.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. SCOPE OF REVIEW This review aims to identify common mechanistic features in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. MAJOR CONCLUSIONS Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit. Further, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic molecules have also been found embedded in P-type ATPase crystal structures. Taken together, in two diverse groups of pumps, nature appears to have evolved quite similar ways of flipping phospholipids. GENERAL SIGNIFICANCE Our understanding of the structural basis for phospholipid flipping is still limited but it seems plausible that a general mechanism for phospholipid flipping exists in nature. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
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Coleman JA, Zhu X, Djajadi HR, Molday LL, Smith RS, Libby RT, John SWM, Molday RS. Phospholipid flippase ATP8A2 is required for normal visual and auditory function and photoreceptor and spiral ganglion cell survival. J Cell Sci 2014; 127:1138-49. [PMID: 24413176 DOI: 10.1242/jcs.145052] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
ATP8A2 is a P4-ATPase that is highly expressed in the retina, brain, spinal cord and testes. In the retina, ATP8A2 is localized in photoreceptors where it uses ATP to transport phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the exoplasmic to the cytoplasmic leaflet of membranes. Although mutations in ATP8A2 have been reported to cause mental retardation in humans and degeneration of spinal motor neurons in mice, the role of ATP8A2 in sensory systems has not been investigated. We have analyzed the retina and cochlea of ATP8A2-deficient mice to determine the role of ATP8A2 in visual and auditory systems. ATP8A2-deficient mice have shortened photoreceptor outer segments, a reduction in photoresponses and decreased photoreceptor viability. The ultrastructure and phagocytosis of the photoreceptor outer segment appeared normal, but the PS and PE compositions were altered and the rhodopsin content was decreased. The auditory brainstem response threshold was significantly higher and degeneration of spiral ganglion cells was apparent. Our studies indicate that ATP8A2 plays a crucial role in photoreceptor and spiral ganglion cell function and survival by maintaining phospholipid composition and contributing to vesicle trafficking.
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Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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50
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Phosphatidylserine-mediated cellular signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 991:177-93. [PMID: 23775696 DOI: 10.1007/978-94-007-6331-9_10] [Citation(s) in RCA: 256] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Phosphatidylserine (PS), a phospholipid with a negatively charged head group, is an important constituent of eukaryotic membranes. Rather than being a passive component of cellular membranes, PS plays an important role in a number of signaling pathways. Signaling is mediated by proteins that are recruited and/or activated by PS in one of two ways: via domains that stereospecifically recognize the head group, or by electrostatic interactions with membranes that are rich in PS and therefore display negative surface charge. Such interactions are key to both intracellular and extracellular signaling cascades. PS, exposed extracellularly, is instrumental in triggering blood clotting and also serves as an "eat me" signal for the clearance of apoptotic cells. Inside the cell, a number of pathways depend of PS; these include kinases, small GTPases and fusogenic proteins. This review will discuss the generation and distribution of PS, current methods of phospholipid visualization within live cells, as well as the current understanding of the role of PS in both extracellular and intracellular signaling events.
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