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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Yarychkivska O, Sharmin R, Elkhalil A, Ghose P. Apoptosis and beyond: A new era for programmed cell death in Caenorhabditis elegans. Semin Cell Dev Biol 2024; 154:14-22. [PMID: 36792437 DOI: 10.1016/j.semcdb.2023.02.003] [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: 01/14/2023] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/16/2023]
Abstract
Programmed cell death (PCD) is crucial for normal development and homeostasis. Our first insights into the genetic regulation of apoptotic cell death came from in vivo studies in the powerful genetic model system of C. elegans. More recently, novel developmental cell death programs occurring both embryonically and post-embryonically, and sex-specifically, have been elucidated. Recent studies in the apoptotic setting have also shed new light on the intricacies of phagocytosis in particular. This review provides a brief historical perspective of the origins of PCD studies in C. elegans, followed by a more detailed description of non-canonical apoptotic and non-apoptotic death programs. We conclude by posing open questions and commenting on our outlook on the future of PCD studies in C. elegans, highlighting the importance of advanced imaging tools and the continued leveraging of C. elegans genetics both with classical and modern cutting-edge approaches.
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Affiliation(s)
| | | | | | - Piya Ghose
- The University of Texas at Arlington, USA.
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3
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Ayuda-Durán B, Garzón-García L, González-Manzano S, Santos-Buelga C, González-Paramás AM. Insights into the Neuroprotective Potential of Epicatechin: Effects against Aβ-Induced Toxicity in Caenorhabditis elegans. Antioxidants (Basel) 2024; 13:79. [PMID: 38247503 PMCID: PMC10812808 DOI: 10.3390/antiox13010079] [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: 11/09/2023] [Revised: 12/21/2023] [Accepted: 01/05/2024] [Indexed: 01/23/2024] Open
Abstract
Medical therapies to avoid the progression of Alzheimer's disease (AD) are limited to date. Certain diets have been associated with a lower incidence of neurodegenerative diseases. In particular, the regular intake of foods rich in polyphenols, such as epicatechin (EC), could help prevent or mitigate AD progression. This work aims to explore the neuroprotective effects of EC using different transgenic strains of Caenorhabditis elegans, which express human Aβ1-42 peptides and contribute to elucidating the mechanisms involved in the effects of EC in AD. The performed assays indicate that this flavan-3-ol was able to reduce the signs of β-amyloid accumulation in C. elegans, improving motility and chemotaxis and increasing survival in transgenic strain peptide producers compared to nematodes not treated with EC. The neuroprotective effects exhibited by EC in C. elegans could be explained by the modulation of inflammation and stress-associated genes, as well as autophagy, microgliosis, and heat shock signaling pathways, involving the regulation of cpr-5, epg-8, ced-7, ZC239.12, and hsp-16 genes. Overall, the results obtained in this study support the protective effects of epicatechin against Aβ-induced toxicity.
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Affiliation(s)
| | | | | | - Celestino Santos-Buelga
- Grupo de Investigación en Polifenoles (GIP-USAL), Campus Miguel de Unamuno, Universidad de Salamanca, 37007 Salamanca, Spain; (B.A.-D.); (L.G.-G.); (S.G.-M.)
| | - Ana M. González-Paramás
- Grupo de Investigación en Polifenoles (GIP-USAL), Campus Miguel de Unamuno, Universidad de Salamanca, 37007 Salamanca, Spain; (B.A.-D.); (L.G.-G.); (S.G.-M.)
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4
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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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5
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Gao Y, Jiao Y, Gong X, Liu J, Xiao H, Zheng Q. Role of transcription factors in apoptotic cells clearance. Front Cell Dev Biol 2023; 11:1110225. [PMID: 36743409 PMCID: PMC9892555 DOI: 10.3389/fcell.2023.1110225] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/09/2023] [Indexed: 01/20/2023] Open
Abstract
The human body generates 10-100 billion cells every day, and the same number of cells die to maintain homeostasis. The genetically controlled, autonomously ordered cell death mainly proceeds by apoptosis. Apoptosis is an important way of programmed cell death in multicellular organisms, timely and effective elimination of apoptotic cells plays a key role in the growth and development of organisms and the maintenance of homeostasis. During the clearance of apoptotic cells, transcription factors bind to specific target promoters and act as activators or repressors to regulate multiple genes expression, how transcription factors regulate apoptosis is an important and poorly understood aspect of normal development. This paper summarizes the regulatory mechanisms of transcription factors in the clearance of apoptotic cells to date.
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Affiliation(s)
| | | | | | | | - Hui Xiao
- *Correspondence: Hui Xiao, ; Qian Zheng,
| | - Qian Zheng
- *Correspondence: Hui Xiao, ; Qian Zheng,
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6
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Romero-Molina C, Garretti F, Andrews SJ, Marcora E, Goate AM. Microglial efferocytosis: Diving into the Alzheimer's disease gene pool. Neuron 2022; 110:3513-3533. [PMID: 36327897 DOI: 10.1016/j.neuron.2022.10.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/04/2022] [Accepted: 10/07/2022] [Indexed: 11/07/2022]
Abstract
Genome-wide association studies and functional genomics studies have linked specific cell types, genes, and pathways to Alzheimer's disease (AD) risk. In particular, AD risk alleles primarily affect the abundance or structure, and thus the activity, of genes expressed in macrophages, strongly implicating microglia (the brain-resident macrophages) in the etiology of AD. These genes converge on pathways (endocytosis/phagocytosis, cholesterol metabolism, and immune response) with critical roles in core macrophage functions such as efferocytosis. Here, we review these pathways, highlighting relevant genes identified in the latest AD genetics and genomics studies, and describe how they may contribute to AD pathogenesis. Investigating the functional impact of AD-associated variants and genes in microglia is essential for elucidating disease risk mechanisms and developing effective therapeutic approaches.
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Affiliation(s)
- Carmen Romero-Molina
- Ronald M. Loeb Center for Alzheimer's Disease, 1 Gustave L. Levy Place, New York, NY 10029-6574, USA; Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Francesca Garretti
- Ronald M. Loeb Center for Alzheimer's Disease, 1 Gustave L. Levy Place, New York, NY 10029-6574, USA; Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Shea J Andrews
- Ronald M. Loeb Center for Alzheimer's Disease, 1 Gustave L. Levy Place, New York, NY 10029-6574, USA; Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Psychiatry and Behavioral Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Edoardo Marcora
- Ronald M. Loeb Center for Alzheimer's Disease, 1 Gustave L. Levy Place, New York, NY 10029-6574, USA; Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Alison M Goate
- Ronald M. Loeb Center for Alzheimer's Disease, 1 Gustave L. Levy Place, New York, NY 10029-6574, USA; Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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7
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Yuan L, Li P, Jing H, Zheng Q, Xiao H. trim-21 promotes proteasomal degradation of CED-1 for apoptotic cell clearance in C. elegans. eLife 2022; 11:76436. [PMID: 35929733 PMCID: PMC9388098 DOI: 10.7554/elife.76436] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 08/02/2022] [Indexed: 11/13/2022] Open
Abstract
The phagocytic receptor CED-1 mediates apoptotic cell recognition by phagocytic cells, enabling cell corpse clearance in Caenorhabditis elegans. Whether appropriate levels of CED-1 are maintained for executing the engulfment function remains unknown. Here, we identified the C. elegans E3 ubiquitin ligase tripartite motif containing-21 (TRIM-21) as a component of the CED-1 pathway for apoptotic cell clearance. When the NPXY motif of CED-1 was bound to the adaptor protein CED-6 or the YXXL motif of CED-1 was phosphorylated by tyrosine kinase SRC-1 and subsequently bound to the adaptor protein NCK-1 containing the SH2 domain, TRIM-21 functioned in conjunction with UBC-21 to catalyze K48-linked poly-ubiquitination on CED-1, targeting it for proteasomal degradation. In the absence of TRIM-21, CED-1 accumulated post-translationally and drove cell corpse degradation defects, as evidenced by direct binding to VHA-10. These findings reveal a unique mechanism for the maintenance of appropriate levels of CED-1 to regulate apoptotic cell clearance.
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Affiliation(s)
- Lei Yuan
- College of Life Sciences, Shaanxi Normal University, Xi'An, China
| | - Peiyao Li
- College of Life Sciences, Shaanxi Normal University, Xi'An, China
| | - Huiru Jing
- College of Life Sciences, Shaanxi Normal University, Xi'An, China
| | - Qian Zheng
- College of Life Sciences, Shaanxi Normal University, Xi'An, China
| | - Hui Xiao
- College of Life Sciences, Shaanxi Normal University, Xi'An, China
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8
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Bossaerts L, Cacace R, Van Broeckhoven C. The role of ATP-binding cassette subfamily A in the etiology of Alzheimer's disease. Mol Neurodegener 2022; 17:31. [PMID: 35477481 PMCID: PMC9044696 DOI: 10.1186/s13024-022-00536-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 04/01/2022] [Indexed: 11/12/2022] Open
Abstract
Background Alzheimer’s disease (AD) is the leading cause of dementia, clinically characterized by memory deficits and progressive cognitive decline. Despite decades of research effective therapies are lacking, and a large part of the genetic heritability remains unidentified. ABCA7 and ABCA1, members of the ATP-binding cassette subfamily A (ABCA), were identified as AD risk genes in genome-wide association studies. Nevertheless, genetic and/or functional studies propose a link between AD and two other members of the ABCA subclass, i.e., ABCA2 and ABCA5. Main body Changes in expression or dysfunction of these transporters were found to increase amyloid β levels. This might be related to the common role of ABCA transporters in cellular cholesterol homeostasis, for which a prominent role in AD development has been suggested. In this review, we provide a comprehensive overview and discussion on the contribution of the ABCA subfamily to the etiopathogenesis of AD. Conclusions A better understanding of the function and identification of disease-associated genetic variants in ABCA transporters can contribute to the development of novel therapeutic strategies for AD.
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Affiliation(s)
- Liene Bossaerts
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, Antwerp, Belgium
| | - Rita Cacace
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, Antwerp, Belgium
| | - Christine Van Broeckhoven
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, Antwerp, Belgium. .,Department of Biomedical Sciences, University of Antwerp - CDE, Universiteitsplein 1, B-2610, Antwerp, Belgium.
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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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ABC-transporter gene expression in ivermectin-susceptible and resistant Haemonchus contortus isolates. Vet Parasitol 2022; 302:109647. [DOI: 10.1016/j.vetpar.2022.109647] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/15/2021] [Accepted: 01/05/2022] [Indexed: 11/21/2022]
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11
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Abstract
Alzheimer's disease (AD) is characterized by the presence of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs), neuronal and synaptic loss and inflammation of the central nervous system (CNS). The majority of AD research has been dedicated to the understanding of two major AD hallmarks (i.e. Aβ and NFTs); however, recent genome-wide association studies (GWAS) data indicate neuroinflammation as having a critical role in late-onset AD (LOAD) development, thus unveiling a novel avenue for AD therapeutics. Recent evidence has provided much support to the innate immune system's involvement with AD progression; however, much remains to be uncovered regarding the role of glial cells, specifically microglia, in AD. Moreover, numerous variants in immune and/or microglia-related genes have been identified in whole-genome sequencing and GWAS analyses, including such genes as TREM2, CD33, APOE, API1, MS4A, ABCA7, BIN1, CLU, CR1, INPP5D, PICALM and PLCG2. In this review, we aim to provide an insight into the function of the major LOAD-associated microglia response genes.
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Affiliation(s)
- Lauren A. Jonas
- Weill Cornell, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10065, USA,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Tanya Jain
- Weill Cornell, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10065, USA,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Yue-Ming Li
- Weill Cornell, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10065, USA,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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12
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Han L, Lan T, Li D, Li H, Deng L, Peng Z, He S, Zhou Y, Han R, Li L, Lu Y, Lu H, Wang Q, Yang S, Zhu Y, Huang Y, Cheng X, Yu J, Wang Y, Sun H, Chai H, Yang H, Xu X, Lisby M, Liu Q, Kristiansen K, Liu H, Hou Z. Chromosome-scale assembly and whole-genome sequencing of 266 giant panda roundworms provide insights into their evolution, adaptation and potential drug targets. Mol Ecol Resour 2021; 22:768-785. [PMID: 34549895 PMCID: PMC9298223 DOI: 10.1111/1755-0998.13504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/02/2021] [Accepted: 08/31/2021] [Indexed: 12/30/2022]
Abstract
Helminth diseases have long been a threat to the health of humans and animals. Roundworms are important organisms for studying parasitic mechanisms, disease transmission and prevention. The study of parasites in the giant panda is of importance for understanding how roundworms adapt to the host. Here, we report a high‐quality chromosome‐scale genome of Baylisascaris schroederi with a genome size of 253.60 Mb and 19,262 predicted protein‐coding genes. We found that gene families related to epidermal chitin synthesis and environmental information processes in the roundworm genome have expanded significantly. Furthermore, we demonstrated unique genes involved in essential amino acid metabolism in the B. schroederi genome, inferred to be essential for the adaptation to the giant panda‐specific diet. In addition, under different deworming pressures, we found that four resistance‐related genes (glc‐1, nrf‐6, bre‐4 and ced‐7) were under strong positive selection in a captive population. Finally, 23 known drug targets and 47 potential drug target proteins were identified. The genome provides a unique reference for inferring the early evolution of roundworms and their adaptation to the host. Population genetic analysis and drug sensitivity prediction provide insights revealing the impact of deworming history on population genetic structure of importance for disease prevention.
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Affiliation(s)
- Lei Han
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China.,Key Laboratory of Wildlife Conservation, China State Forestry Administration, Harbin, China
| | - Tianming Lan
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China.,Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Desheng Li
- Key Laboratory of SFGA on Conservation Biology of Rare Animals in the Giant Panda National Park (CCRCGP), Sichuan, China
| | - Haimeng Li
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Linhua Deng
- Key Laboratory of SFGA on Conservation Biology of Rare Animals in the Giant Panda National Park (CCRCGP), Sichuan, China
| | - Zhiwei Peng
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Shaowen He
- Foping National Nature Reserve, Hanzhong, China
| | - Yanqiang Zhou
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Ruobing Han
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Lingling Li
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Yaxian Lu
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Haorong Lu
- Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Qing Wang
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
| | - Shangchen Yang
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yixin Zhu
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, China
| | - Yunting Huang
- Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | | | - Jieyao Yu
- Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, China
| | - Yulong Wang
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Heting Sun
- General Station for Surveillance of Wildlife Diseases, National Forestry and Grassland Administration, Harbin, China
| | - Hongliang Chai
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Huanming Yang
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China
| | - Xun Xu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China.,Guangdong Provincial Key Laboratory of Genome Read and Write, BGI-Shenzhen, Shenzhen, China
| | - Michael Lisby
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Quan Liu
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China.,School of Life Sciences and Engineering, Foshan University, Foshan, China
| | - Karsten Kristiansen
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Qingdao-Europe Advanced Institute for Life Sciences, Qingdao, China
| | - Huan Liu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, China.,Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Zhijun Hou
- College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China.,Key Laboratory of Wildlife Conservation, China State Forestry Administration, Harbin, China
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13
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Chen W, Li L, Wang J, Zhang R, Zhang T, Wu Y, Wang S, Xing D. The ABCA1-efferocytosis axis: A new strategy to protect against atherosclerosis. Clin Chim Acta 2021; 518:1-8. [PMID: 33741356 DOI: 10.1016/j.cca.2021.02.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 12/13/2022]
Abstract
Atherosclerosis, a disease process characterized by lipid accumulation and inflammation, is the main cause of coronary heart disease (CHD) and myocardial infarction (MI). Efferocytosis involves the clearance of apoptotic cells by phagocytes. Successful engulfment triggers the release of anti-inflammatory cytokines to suppress atherosclerosis. ABCA1 is a key mediator of cholesterol efflux to apoA-I for the generation of HDL-C in reverse cholesterol transport (RCT). Intriguingly, ABCA1 promotes not only cholesterol efflux but also efferocytosis. ABCA1 promotes efferocytosis by regulating the release of "find-me" ligands, including LPC, and the exposure, release, and expression of "eat-me" ligands, including PtdSer, ANXA1, ANXA5, MEGF10, and GULP1. ABCA1 has a pathway similar to TG2, which is an "eat-me" ligand. ABCA1 has the highest known homology to ABCA7, which controls efferocytosis as the engulfment and processing ligand. In addition, ABCA1 can form several regulatory feedback axes with ANXA1, MEGF10, GULP1, TNFα, and IL-6. Therefore, ABCA1 is the central factor that links cholesterol efflux and apoptotic cell clearance. Several drugs have been studied or approved for apoptotic cell clearance, such as CD47 antibody and PD1-/PD-L1 antibody. In this article, we review the role and mechanism of action of ABCA1 in efferocytosis and focus on new insights into the ABCA1-efferocytosis axis and its potential as a novel therapeutic target in atherosclerosis.
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Affiliation(s)
- Wujun Chen
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China
| | - Lu Li
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China
| | - Jie Wang
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China
| | - Renshuai Zhang
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China
| | - Tingting Zhang
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China
| | - Yudong Wu
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China.
| | - Shuai Wang
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China; School of Medical Imaging, Radiotherapy Department of Affiliated Hospital, Weifang Medical University, Weifang, Shandong 261053, China.
| | - Dongming Xing
- Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong 266071, China; School of Life Sciences, Tsinghua University, Beijing 100084, China.
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14
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Flagging fusion: Phosphatidylserine signaling in cell-cell fusion. J Biol Chem 2021; 296:100411. [PMID: 33581114 PMCID: PMC8005811 DOI: 10.1016/j.jbc.2021.100411] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 02/06/2023] Open
Abstract
Formations of myofibers, osteoclasts, syncytiotrophoblasts, and fertilized zygotes share a common step, cell–cell fusion. Recent years have brought about considerable progress in identifying some of the proteins involved in these and other cell-fusion processes. However, even for the best-characterized cell fusions, we still do not know the mechanisms that regulate the timing of cell-fusion events. Are they fully controlled by the expression of fusogenic proteins or do they also depend on some triggering signal that activates these proteins? The latter scenario would be analogous to the mechanisms that control the timing of exocytosis initiated by Ca2+ influx and virus-cell fusion initiated by low pH- or receptor interaction. Diverse cell fusions are accompanied by the nonapoptotic exposure of phosphatidylserine at the surface of fusing cells. Here we review data on the dependence of membrane remodeling in cell fusion on phosphatidylserine and phosphatidylserine-recognizing proteins and discuss the hypothesis that cell surface phosphatidylserine serves as a conserved “fuse me” signal regulating the time and place of cell-fusion processes.
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15
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Furuta Y, Pena-Ramos O, Li Z, Chiao L, Zhou Z. Calcium ions trigger the exposure of phosphatidylserine on the surface of necrotic cells. PLoS Genet 2021; 17:e1009066. [PMID: 33571185 PMCID: PMC7904182 DOI: 10.1371/journal.pgen.1009066] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 02/24/2021] [Accepted: 01/18/2021] [Indexed: 11/18/2022] Open
Abstract
Intracellular Ca2+ level is under strict regulation through calcium channels and storage pools including the endoplasmic reticulum (ER). Mutations in certain ion channel subunits, which cause mis-regulated Ca2+ influx, induce the excitotoxic necrosis of neurons. In the nematode Caenorhabditis elegans, dominant mutations in the DEG/ENaC sodium channel subunit MEC-4 induce six mechanosensory (touch) neurons to undergo excitotoxic necrosis. These necrotic neurons are subsequently engulfed and digested by neighboring hypodermal cells. We previously reported that necrotic touch neurons actively expose phosphatidylserine (PS), an “eat-me” signal, to attract engulfing cells. However, the upstream signal that triggers PS externalization remained elusive. Here we report that a robust and transient increase of cytoplasmic Ca2+ level occurs prior to the exposure of PS on necrotic touch neurons. Inhibiting the release of Ca2+ from the ER, either pharmacologically or genetically, specifically impairs PS exposure on necrotic but not apoptotic cells. On the contrary, inhibiting the reuptake of cytoplasmic Ca2+ into the ER induces ectopic necrosis and PS exposure. Remarkably, PS exposure occurs independently of other necrosis events. Furthermore, unlike in mutants of DEG/ENaC channels, in dominant mutants of deg-3 and trp-4, which encode Ca2+ channels, PS exposure on necrotic neurons does not rely on the ER Ca2+ pool. Our findings indicate that high levels of cytoplasmic Ca2+ are necessary and sufficient for PS exposure. They further reveal two Ca2+-dependent, necrosis-specific pathways that promote PS exposure, a “two-step” pathway initiated by a modest influx of Ca2+ and further boosted by the release of Ca2+ from the ER, and another, ER-independent, pathway. Moreover, we found that ANOH-1, the worm homolog of mammalian phospholipid scramblase TMEM16F, is necessary for efficient PS exposure in thapsgargin-treated worms and trp-4 mutants, like in mec-4 mutants. We propose that both the ER-mediated and ER-independent Ca2+ pathways promote PS externalization through activating ANOH-1. Necrosis is a type of cell death that exhibits distinct morphological features such as cell and organelle swelling. Necrotic cells expose phosphatidylserine (PS)–a type of phospholipid—on their outer surfaces. Receptor molecules on phagocytes detect PS on necrotic cells and subsequently initiate the engulfment process. As necrosis is associated with stroke, cancer, neurodegenerative diseases, and heart diseases, studying necrotic cell clearance has important medical relevance. In the model organism the nematode C. elegans, we previously identified membrane proteins that promote the exposure of PS on necrotic cell surfaces by studying neurons that are induced to undergo necrosis by dominant mutations in ion channels. Here, in C. elegans, we have discovered that the necrotic insults trigger an increase of the cytoplasmic calcium ion (Ca2+), which in turn promotes PS externalization on necrotic cell surfaces. Furthermore, we have identified two different mechanisms that increase cytoplasmic Ca2+ levels, one dependent on the Ca2+ contribution from the endoplasmic reticulum (ER), the other independent of the ER. The Ca2+ signal targets ANOH-1, a worm homolog of mammalian proteins capable of externalizing PS, for promoting PS exposure on necrotic cells. Our findings reveal novel upstream regulatory mechanisms that promote necrotic cell clearance in animals.
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Affiliation(s)
- Yoshitaka Furuta
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- School of Pharmacy, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, Japan
| | - Omar Pena-Ramos
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zao Li
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lucia Chiao
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Zheng Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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16
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Chang C, Hisamoto N. Engulfment Genes Promote Neuronal Regeneration in
Caenorhabditis Elegans
: Two Divergent But Complementary Views. Bioessays 2020; 42:e1900185. [DOI: 10.1002/bies.201900185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 04/23/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Chieh Chang
- Department of Biological Sciences University of Illinois at Chicago Chicago Illinois 60607 USA
| | - Naoki Hisamoto
- Dept. of Biological Science Graduate School of Science Nagoya University Furo‐cho, Chikusa‐ku, Aichi Prefecture Nagoya 464‐8602 Japan
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17
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Davidson AJ, Wood W. Phagocyte Responses to Cell Death in Flies. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a036350. [PMID: 31501193 DOI: 10.1101/cshperspect.a036350] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Multicellular organisms are not created through cell proliferation alone. It is through cell death that an indefinite cellular mass is pared back to reveal its true form. Cells are also lost throughout life as part of homeostasis and through injury. This detritus represents a significant burden to the living organism and must be cleared, most notably through the use of specialized phagocytic cells. Our understanding of these phagocytes and how they engulf cell corpses has been greatly aided by studying the fruit fly, Drosophila melanogaster Here we review the contribution of Drosophila research to our understanding of how phagocytes respond to cell death. We focus on the best studied phagocytes in the fly: the glia of the central nervous system, the ovarian follicle cells, and the macrophage-like hemocytes. Each is explored in the context of the tissue they maintain as well as how they function during development and in response to injury.
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Affiliation(s)
- Andrew J Davidson
- Centre for Inflammation Research, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
| | - Will Wood
- Centre for Inflammation Research, University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
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18
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Haley R, Zhou Z. The small GTPase RAB-35 facilitates the initiation of phagosome maturation and acts as a robustness factor for apoptotic cell clearance. Small GTPases 2019; 12:188-201. [PMID: 31607221 DOI: 10.1080/21541248.2019.1680066] [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: 10/25/2022] Open
Abstract
We recently identified the novel function of the small GTPase RAB-35 in apoptotic cell clearance in Caenorhabditis elegans, a process in which dying cells are engulfed and degraded inside phagosomes. We have found that RAB-35 functions in two separate steps of cell corpse clearance, cell corpse recognition and the initiation of phagosome maturation. During the latter process, RAB-35 facilitates the removal of phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) from the membranes of nascent phagosomes and the simultaneous production of phosphatidylinositol-3-P (PI(3)P) on these same membranes, a process that we have coined the PI(4,5)P2 to PI(3)P shift. RAB-35 also promotes the recruitment of the small GTPase RAB-5 to the phagosomal surface. During these processes, the activity of RAB-35 is controlled by the candidate GTPase-activating protein (GAP) TBC-10 and the candidate guanine nucleotide exchange factor (GEF) FLCN-1. Overall, RAB-35 leads a third pathway during cell corpse clearance that functions in parallel to the two known pathways, one led by the phagocytic receptor CED-1 and the other led by the CED-10/Rac1 GTPase. Here, we further report that RAB-35 acts as a robustness factor that maintains the clearance activity and embryonic viability under conditions of heat stress. Moreover, we obtained additional evidence suggesting that RAB-35 acts upstream of RAB-5 and RAB-7. To establish a precise temporal pattern for its own dissociation from phagosomal surfaces, RAB-35 controls the removal of its own GAP. We propose that RAB-35 defines a largely unexplored initial phase of phagosome maturation.
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Affiliation(s)
- Ryan Haley
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Zheng Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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19
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Wang G, Sun L, Reina CP, Song I, Gabel CV, Driscoll M. CED-4 CARD domain residues can modulate non-apoptotic neuronal regeneration functions independently from apoptosis. Sci Rep 2019; 9:13315. [PMID: 31527664 PMCID: PMC6746752 DOI: 10.1038/s41598-019-49633-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 06/20/2019] [Indexed: 12/31/2022] Open
Abstract
A major challenge in regenerative medicine is the repair of injured neurons. Regeneration of laser-cut C. elegans neurons requires early action of core apoptosis activator CED-4/Apaf1 and CED-3/caspase. While testing models for CED-4 as a candidate calcium-sensitive activator of repair, we unexpectedly discovered that amino acid substitutions affecting alpha-helix-6 within the CED-4 caspase recruitment domain (CARD) confer a CED-4 gain-of-function (gf) activity that increases axonal regrowth without disrupting CED-4 apoptosis activity. The in vivo caspase reporter CA-GFP reveals a rapid localized increase in caspase activity upon axotomy, which is absent in ced-4 and ced-3 loss-of-function mutants but present in the ced-4(gf) mutant. The ced-3 loss-of-function mutation can significantly suppress the axonal regrowth of the ced-4(gf) mutant, indicating that CED-4(gf) regeneration depends on CED-3 caspase. Thus, we identified a subdomain within the CED-4 CARD that regulates the dynamic and controlled caspase activity required for efficient regeneration.
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Affiliation(s)
- Guoqiang Wang
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, 08854, USA
| | - Lin Sun
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, 02118, USA
| | - Christopher P Reina
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, 08854, USA
| | - Isaac Song
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, 08854, USA
| | - Christopher V Gabel
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, 02118, USA
| | - Monica Driscoll
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ, 08854, USA.
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20
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Abstract
Tissue macrophages rapidly recognize and engulf apoptotic cells. These events require the display of so-called eat-me signals on the apoptotic cell surface, the most fundamental of which is phosphatidylserine (PtdSer). Externalization of this phospholipid is catalysed by scramblase enzymes, several of which are activated by caspase cleavage. PtdSer is detected both by macrophage receptors that bind to this phospholipid directly and by receptors that bind to a soluble bridging protein that is independently bound to PtdSer. Prominent among the latter receptors are the MER and AXL receptor tyrosine kinases. Eat-me signals also trigger macrophages to engulf virus-infected or metabolically traumatized, but still living, cells, and this 'murder by phagocytosis' may be a common phenomenon. Finally, the localized presentation of PtdSer and other eat-me signals on delimited cell surface domains may enable the phagocytic pruning of these 'locally dead' domains by macrophages, most notably by microglia of the central nervous system.
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Affiliation(s)
- Greg Lemke
- Molecular Neurobiology Laboratory, Immunobiology and Microbial Pathogenesis Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA.
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21
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Doll MA, Soltanmohammadi N, Schumacher B. ALG-2/AGO-Dependent mir-35 Family Regulates DNA Damage-Induced Apoptosis Through MPK-1/ERK MAPK Signaling Downstream of the Core Apoptotic Machinery in Caenorhabditis elegans. Genetics 2019; 213:173-194. [PMID: 31296532 PMCID: PMC6727803 DOI: 10.1534/genetics.119.302458] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 07/08/2019] [Indexed: 12/12/2022] Open
Abstract
MicroRNAs (miRNAs) associate with argonaute (AGO) proteins to post-transcriptionally modulate the expression of genes involved in various cellular processes. Herein, we show that loss of the Caenorhabditis elegans AGO gene alg-2 results in rapid and significantly increased germ cell apoptosis in response to DNA damage inflicted by ionizing radiation (IR). We demonstrate that the abnormal apoptosis phenotype in alg-2 mutant animals can be explained by reduced expression of mir-35 miRNA family members. We show that the increased apoptosis levels in IR-treated alg-2 or mir-35 family mutants depend on a transient hyperactivation of the C. elegans ERK1/2 MAPK ortholog MPK-1 in dying germ cells. Unexpectedly, MPK-1 phosphorylation occurs downstream of caspase activation and depends at least in part on a functional cell corpse-engulfment machinery. Therefore, we propose a refined mechanism, in which an initial proapoptotic stimulus by the core apoptotic machinery initiates the engulfment process, which in turn activates MAPK signaling to facilitate the demise of genomically compromised germ cells.
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Affiliation(s)
- Markus Alexander Doll
- Institute for Genome Stability in Ageing and Disease, Medical Faculty, University of Cologne, 50931, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931, Germany
| | - Najmeh Soltanmohammadi
- Institute for Genome Stability in Ageing and Disease, Medical Faculty, University of Cologne, 50931, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931, Germany
| | - Björn Schumacher
- Institute for Genome Stability in Ageing and Disease, Medical Faculty, University of Cologne, 50931, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Ageing-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931, Germany
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22
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De Roeck A, Van Broeckhoven C, Sleegers K. The role of ABCA7 in Alzheimer's disease: evidence from genomics, transcriptomics and methylomics. Acta Neuropathol 2019; 138:201-220. [PMID: 30903345 PMCID: PMC6660495 DOI: 10.1007/s00401-019-01994-1] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 12/12/2022]
Abstract
Genome-wide association studies (GWAS) originally identified ATP-binding cassette, sub-family A, member 7 (ABCA7), as a novel risk gene of Alzheimer’s disease (AD). Since then, accumulating evidence from in vitro, in vivo, and human-based studies has corroborated and extended this association, promoting ABCA7 as one of the most important risk genes of both early-onset and late-onset AD, harboring both common and rare risk variants with relatively large effect on AD risk. Within this review, we provide a comprehensive assessment of the literature on ABCA7, with a focus on AD-related human -omics studies (e.g. genomics, transcriptomics, and methylomics). In European and African American populations, indirect ABCA7 GWAS associations are explained by expansion of an ABCA7 variable number tandem repeat (VNTR), and a common premature termination codon (PTC) variant, respectively. Rare ABCA7 PTC variants are strongly enriched in AD patients, and some of these have displayed inheritance patterns resembling autosomal dominant AD. In addition, rare missense variants are more frequent in AD patients than healthy controls, whereas a common ABCA7 missense variant may protect from disease. Methylation at several CpG sites in the ABCA7 locus is significantly associated with AD. Furthermore, ABCA7 contains many different isoforms and ABCA7 splicing has been shown to associate with AD. Besides associations with disease status, these genetic and epigenetic ABCA7 markers also showed significant correlations with AD endophenotypes; in particular amyloid deposition and brain morphology. In conclusion, human-based –omics studies provide converging evidence of (partial) ABCA7 loss as an AD pathomechanism, and future studies should make clear if interventions on ABCA7 expression can serve as a valuable therapeutic target for AD.
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Affiliation(s)
- Arne De Roeck
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, University of Antwerp, CDE, Universiteitsplein 1, 2610, Antwerp, Belgium
- Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Christine Van Broeckhoven
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, University of Antwerp, CDE, Universiteitsplein 1, 2610, Antwerp, Belgium
- Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Kristel Sleegers
- Neurodegenerative Brain Diseases Group, VIB Center for Molecular Neurology, University of Antwerp, CDE, Universiteitsplein 1, 2610, Antwerp, Belgium.
- Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
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23
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Disruption of RAB-5 Increases EFF-1 Fusogen Availability at the Cell Surface and Promotes the Regenerative Axonal Fusion Capacity of the Neuron. J Neurosci 2019; 39:2823-2836. [PMID: 30737314 DOI: 10.1523/jneurosci.1952-18.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 12/29/2022] Open
Abstract
Following a transection injury to the axon, neurons from a number of species have the ability to undergo spontaneous repair via fusion of the two separated axonal fragments. In the nematode Caenorhabditis elegans, this highly efficient regenerative axonal fusion is mediated by epithelial fusion failure-1 (EFF-1), a fusogenic protein that functions at the membrane to merge the two axonal fragments. Identifying modulators of axonal fusion and EFF-1 is an important step toward a better understanding of this repair process. Here, we present evidence that the small GTPase RAB-5 acts to inhibit axonal fusion, a function achieved via endocytosis of EFF-1 within the injured neuron. Therefore, we find that perturbing RAB-5 activity is sufficient to restore axonal fusion in mutant animals with decreased axonal fusion capacity. This is accompanied by enhanced membranous localization of EFF-1 and the production of extracellular EFF-1-containing vesicles. These findings identify RAB-5 as a novel regulator of axonal fusion in C. elegans hermaphrodites and the first regulator of EFF-1 in neurons.SIGNIFICANCE STATEMENT Peripheral and central nerve injuries cause life-long disabilities due to the fact that repair rarely leads to reinnervation of the target tissue. In the nematode Caenorhabditis elegans, axonal regeneration can proceed through axonal fusion, whereby a regrowing axon reconnects and fuses with its own separated distal fragment, restoring the original axonal tract. We have characterized axonal fusion and established that the fusogen epithelial fusion failure-1 (EFF-1) is a key element for fusing the two separated axonal fragments back together. Here, we show that the small GTPase RAB-5 is a key cell-intrinsic regulator of the fusogen EFF-1 and can in turn regulate axonal fusion. Our findings expand the possibility for this process to be controlled and exploited to facilitate axonal repair in medical applications.
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24
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Neumann B, Linton C, Giordano-Santini R, Hilliard MA. Axonal fusion: An alternative and efficient mechanism of nerve repair. Prog Neurobiol 2018; 173:88-101. [PMID: 30500382 DOI: 10.1016/j.pneurobio.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/22/2018] [Accepted: 11/26/2018] [Indexed: 02/07/2023]
Abstract
Injuries to the nervous system can cause lifelong morbidity due to the disconnect that occurs between nerve cells and their cellular targets. Re-establishing these lost connections is the ultimate goal of endogenous regenerative mechanisms, as well as those induced by exogenous manipulations in a laboratory or clinical setting. Reconnection between severed neuronal fibers occurs spontaneously in some invertebrate species and can be induced in mammalian systems. This process, known as axonal fusion, represents a highly efficient means of repair after injury. Recent progress has greatly enhanced our understanding of the molecular control of axonal fusion, demonstrating that the machinery required for the engulfment of apoptotic cells is repurposed to mediate the reconnection between severed axon fragments, which are subsequently merged by fusogen proteins. Here, we review our current understanding of naturally occurring axonal fusion events, as well as those being ectopically produced with the aim of achieving better clinical outcomes.
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Affiliation(s)
- Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800, 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
| | - 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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25
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Kerr CH, Dalwadi U, Scott NE, Yip CK, Foster LJ, Jan E. Transmission of Cricket paralysis virus via exosome-like vesicles during infection of Drosophila cells. Sci Rep 2018; 8:17353. [PMID: 30478341 PMCID: PMC6255767 DOI: 10.1038/s41598-018-35717-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 10/17/2018] [Indexed: 01/06/2023] Open
Abstract
Viruses are classically characterized as being either enveloped or nonenveloped depending on the presence or absence of a lipid bi-layer surrounding their proteinaceous capsid. In recent years, many studies have challenged this view by demonstrating that some nonenveloped viruses (e.g. hepatitis A virus) can acquire an envelope during infection by hijacking host cellular pathways. In this study, we examined the role of exosome-like vesicles (ELVs) during infection of Drosophilia melanogaster S2 cells by Cricket paralysis virus (CrPV). Utilizing quantitative proteomics, we demonstrated that ELVs can be isolated from both mock- and CrPV-infected S2 cells that contain distinct set of proteins compared to the cellular proteome. Moreover, 40 proteins increased in abundance in ELVs derived from CrPV-infected cells compared to mock, suggesting specific factors associate with ELVs during infection. Interestingly, peptides from CrPV capsid proteins (ORF2) and viral RNA were detected in ELVs from infected cells. Finally, ELVs from CrPV-infected cells are infectious suggesting that CrPV may hijack ELVs to acquire an envelope during infection of S2 cells. This study further demonstrates the diverse strategies of nonenveloped viruses from invertebrates to vertebrates to acquire an envelope in order to evade the host response or facilitate transmission.
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Affiliation(s)
- Craig H Kerr
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver BC, V6T 1Z3, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver BC, V6T 1Z3, Melbourne, Australia
| | - Udit Dalwadi
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver BC, V6T 1Z3, Canada
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia
| | - Calvin K Yip
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver BC, V6T 1Z3, Canada
| | - Leonard J Foster
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver BC, V6T 1Z3, Canada.
- Michael Smith Laboratories, University of British Columbia, Vancouver BC, V6T 1Z3, Melbourne, Australia.
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver BC, V6T 1Z3, Canada.
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26
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Chiu H, Zou Y, Suzuki N, Hsieh YW, Chuang CF, Wu YC, Chang C. Engulfing cells promote neuronal regeneration and remove neuronal debris through distinct biochemical functions of CED-1. Nat Commun 2018; 9:4842. [PMID: 30451835 PMCID: PMC6242819 DOI: 10.1038/s41467-018-07291-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 10/22/2018] [Indexed: 11/25/2022] Open
Abstract
Two important biological events happen coincidently soon after nerve injury in the peripheral nervous system in C. elegans: removal of axon debris and initiation of axon regeneration. But, it is not known how these two events are co-regulated. Mutants of ced-1, a homolog of Draper and MEGF10, display defects in both events. One model is that those events could be related. But our data suggest that they are actually separable. CED-1 functions in the muscle-type engulfing cells in both events and is enriched in muscle protrusions in close contact with axon debris and regenerating axons. Its two functions occur through distinct biochemical mechanisms; extracellular domain-mediated adhesion for regeneration and extracellular domain binding-induced intracellular domain signaling for debris removal. These studies identify CED-1 in engulfing cells as a receptor in debris removal but as an adhesion molecule in neuronal regeneration, and have important implications for understanding neural circuit repair after injury.
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Affiliation(s)
- Hui Chiu
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, 60607, USA
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 10617, Taiwan
- Division of Biology and Biological Engineering and HHMI, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Yan Zou
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, 60607, USA
- School of Life Science, ShanghaiTech University, Shanghai, 200031, China
| | - Nobuko Suzuki
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, 60607, USA
| | - Yi-Wen Hsieh
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, 60607, USA
| | - Chiou-Fen Chuang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, 60607, USA
| | - Yi-Chun Wu
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, 10617, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Chieh Chang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, 60607, USA.
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27
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Haley R, Wang Y, Zhou Z. The small GTPase RAB-35 defines a third pathway that is required for the recognition and degradation of apoptotic cells. PLoS Genet 2018; 14:e1007558. [PMID: 30138370 PMCID: PMC6107108 DOI: 10.1371/journal.pgen.1007558] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/12/2018] [Indexed: 01/18/2023] Open
Abstract
In metazoans, apoptotic cells are swiftly engulfed by phagocytes and degraded inside phagosomes. Multiple small GTPases in the Rab family are known to function in phagosome maturation by regulating vesicle trafficking. We discovered rab-35 as a new gene important for apoptotic cell clearance from a genetic screen targeting putative Rab GTPases in Caenorhabditis elegans. We further identified TBC-10 as a putative GTPase-activating protein (GAP), and FLCN-1 and RME-4 as two putative Guanine Nucleotide Exchange Factors (GEFs), for RAB-35. We found that RAB-35 was required for the efficient incorporation of early endosomes to phagosomes and for the timely degradation of apoptotic cell corpses. More specifically, RAB-35 promotes two essential events that initiate phagosome maturation: the switch of phagosomal membrane phosphatidylinositol species from PtdIns(4,5)P2 to PtdIns(3)P, and the recruitment of the small GTPase RAB-5 to phagosomal surfaces. These functions of RAB-35 were previously unknown. Remarkably, although the phagocytic receptor CED-1 regulates these same events, RAB-35 and CED-1 appear to function independently. Upstream of degradation, RAB-35 also facilitates the recognition of apoptotic cells independently of the known CED-1 and CED-5 pathways. RAB-35 localizes to extending pseudopods and is further enriched on nascent phagosomes, consistent with its dual roles in regulating apoptotic cell-recognition and phagosome maturation. Epistasis analyses indicate that rab-35 acts in parallel to both of the canonical ced-1/6/7 and ced-2/5/10/12 clearance pathways. We propose that RAB-35 acts as a robustness factor, defining a novel pathway that aids these canonical pathways in both the recognition and degradation of apoptotic cells.
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Affiliation(s)
- Ryan Haley
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, United States of America
| | - Ying Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, United States of America
| | - Zheng Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, United States of America
- * E-mail:
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28
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Phosphatidylserine exposure mediated by ABC transporter activates the integrin signaling pathway promoting axon regeneration. Nat Commun 2018; 9:3099. [PMID: 30082731 PMCID: PMC6079064 DOI: 10.1038/s41467-018-05478-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 07/02/2018] [Indexed: 12/22/2022] Open
Abstract
Following axon injury, a cascade of signaling events is triggered to initiate axon regeneration. However, the mechanisms regulating axon regeneration are not well understood at present. In Caenorhabditis elegans, axon regeneration utilizes many of the components involved in phagocytosis, including integrin and Rac GTPase. Here, we identify the transthyretin (TTR)-like protein TTR-11 as a component functioning in axon regeneration upstream of integrin. We show that TTR-11 binds to both the extracellular domain of integrin-α and phosphatidylserine (PS). Axon injury induces the accumulation of PS around the injured axons in a manner dependent on TTR-11, the ABC transporter CED-7, and the caspase CED-3. Furthermore, we demonstrate that CED-3 activates CED-7 during axon regeneration. Thus, TTR-11 functions to link the PS injury signal to activation of the integrin pathway, which then initiates axon regeneration.
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29
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Kumar S, Calianese D, Birge RB. Efferocytosis of dying cells differentially modulate immunological outcomes in tumor microenvironment. Immunol Rev 2018; 280:149-164. [PMID: 29027226 DOI: 10.1111/imr.12587] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Programmed cell death (apoptosis) is an integral part of tissue homeostasis in complex organisms, allowing for tissue turnover, repair, and renewal while simultaneously inhibiting the release of self antigens and danger signals from apoptotic cell-derived constituents that can result in immune activation, inflammation, and autoimmunity. Unlike cells in culture, the physiological fate of cells that die by apoptosis in vivo is their rapid recognition and engulfment by phagocytic cells (a process called efferocytosis). To this end, apoptotic cells express specific eat-me signals, such as externalized phosphatidylserine (PS), that are recognized in a specific context by receptors to initiate signaling pathways for engulfment. The importance of carefully regulated recognition and clearance pathways is evident in the spectrum of inflammatory and autoimmune disorders caused by defects in PS receptors and signaling molecules. However, in recent years, several additional cell death pathways have emerged, including immunogenic cell death, necroptosis, pyroptosis, and netosis that interweave different cell death pathways with distinct innate and adaptive responses from classical apoptosis that can shape long-term host immunity. In this review, we discuss the role of different cell death pathways in terms of their immune potential outcomes specifically resulting in specific cell corpse/phagocyte interactions (phagocytic synapses) that impinge on host immunity, with a main emphasis on tolerance and cancer immunotherapy.
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Affiliation(s)
- Sushil Kumar
- New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, USA
| | - David Calianese
- New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, USA
| | - Raymond B Birge
- New Jersey Medical School, Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers University, Newark, NJ, USA
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30
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Kim MJ, Lee YJ, Yoon YS, Kim M, Choi JH, Kim HS, Kang JL. Apoptotic cells trigger the ABCA1/STAT6 pathway leading to PPAR-γ expression and activation in macrophages. J Leukoc Biol 2018; 103:885-895. [PMID: 29603355 DOI: 10.1002/jlb.2a0817-341rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 02/06/2017] [Accepted: 02/25/2018] [Indexed: 11/12/2022] Open
Abstract
The signal transducer and activator of transcription 6 (STAT6) transcription factor activates peroxisome proliferator-activated receptor gamma (PPAR-γ)-regulated gene expression in immune cells. We investigated proximal membrane signaling that was initiated in macrophages after exposure to apoptotic cells that led to enhanced PPAR-γ expression and activity, using specific siRNAs for ABCA1, STAT6, and PPAR-γ, or their antagonists. The interactions between mouse bone marrow-derived macrophages or RAW 264.7 cells and apoptotic Jurkat cells, but not viable cells, resulted in the induction of STAT6 phosphorylation as well as PPAR-γ expression and activation. Knockdown of ATP-binding cassette transporter A1 (ABCA1) after the transfection of macrophages with ABCA1-specific siRNAs reduced apoptotic cell-induced STAT6 phosphorylation as well as PPAR-γ mRNA and protein expression. ABCA1 knockdown also reduced apoptotic cell-induced liver X receptor α (LXR-α) mRNA and protein expression. Moreover, inhibition of STAT6 with specific siRNAs or the pharmacological inhibitor AS1517499AS reversed the induction of PPAR-γ, LXR-α, and ABCA1 by apoptotic Jurkat cells. PPAR-γ-specific siRNAs or the PPAR-γ antagonist GW9662 inhibited apoptotic cell-induced increases in LXR-α and ABCA1 mRNA and protein levels. Thus, these results indicate that apoptotic cells trigger the ABCA1/STAT6 pathway, leading to the activation of the PPAR-γ/LXR-α/ABCA1 pathway in macrophages.
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Affiliation(s)
- Myeong-Joo Kim
- Department of Physiology, Ewha Womans University, Seoul, Korea
| | - Ye-Ji Lee
- Department of Physiology, Ewha Womans University, Seoul, Korea
| | - Young-So Yoon
- Department of Physiology, Ewha Womans University, Seoul, Korea
| | - Minsuk Kim
- Department of Pharmacology, Ewha Womans University, Seoul, Korea.,Tissue Injury Defense Research Center, College of Medicine, Ewha Womans University, Seoul, Korea
| | - Ji Ha Choi
- Department of Pharmacology, Ewha Womans University, Seoul, Korea.,Tissue Injury Defense Research Center, College of Medicine, Ewha Womans University, Seoul, Korea
| | - Hee-Sun Kim
- Department of Molecular Medicine, Ewha Womans University, Seoul, Korea.,Tissue Injury Defense Research Center, College of Medicine, Ewha Womans University, Seoul, Korea
| | - Jihee Lee Kang
- Department of Physiology, Ewha Womans University, Seoul, Korea.,Tissue Injury Defense Research Center, College of Medicine, Ewha Womans University, Seoul, Korea
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31
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The ABC Transporter Eato Promotes Cell Clearance in the Drosophila melanogaster Ovary. G3-GENES GENOMES GENETICS 2018; 8:833-843. [PMID: 29295819 PMCID: PMC5844305 DOI: 10.1534/g3.117.300427] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The clearance of dead cells is a fundamental process in the maintenance of tissue homeostasis. Genetic studies in Drosophila melanogaster, Caenorhabditis elegans, and mammals have identified two evolutionarily conserved signaling pathways that act redundantly to regulate this engulfment process: the ced-1/-6/-7 and ced-2/-5/-12 pathways. Of these engulfment genes, only the ced-7/ABCA1 ortholog remains to be identified in D. melanogaster Homology searches have revealed a family of putative ced-7/ABCA1 homologs encoding ATP-binding cassette (ABC) transporters in D. melanogaster To determine which of these genes functions similarly to ced-7/ABCA1, we analyzed mutants for engulfment phenotypes in oogenesis, during which nurse cells (NCs) in each egg chamber undergo programmed cell death (PCD) and are removed by neighboring phagocytic follicle cells (FCs). Our genetic analyses indicate that one of the ABC transporter genes, which we have named Eato (Engulfment ABC Transporter in the ovary), is required for NC clearance in the ovary and acts in the same pathways as drpr, the ced-1 ortholog, and in parallel to Ced-12 in the FCs. Additionally, we show that Eato acts in the FCs to promote accumulation of the transmembrane receptor Drpr, and promote membrane extensions around the NCs for their clearance. Since ABCA class transporters, such as CED-7 and ABCA1, are known to be involved in lipid trafficking, we propose that Eato acts to transport membrane material to the growing phagocytic cup for cell corpse clearance. Our work presented here identifies Eato as the ced-7/ABCA1 ortholog in D. melanogaster, and demonstrates a role for Eato in Drpr accumulation and phagocytic membrane extensions during NC clearance in the ovary.
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32
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Luo YL, Ma GX, Luo YF, Kuang CY, Jiang AY, Li GQ, Zhou RQ. Tissue expression pattern of ABCG transporter indicates functional roles in reproduction of Toxocara canis. Parasitol Res 2018; 117:775-782. [PMID: 29423531 DOI: 10.1007/s00436-018-5751-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 01/05/2018] [Indexed: 01/16/2023]
Abstract
Toxocara canis is a zoonotic parasite with worldwide distribution. ATP-binding cassette (ABC) transporters are integral membrane proteins which involve in a range of biological processes in various organisms. In present study, the full-length coding sequence of abcg-5 gene of T. canis (Tc-abcg-5) was cloned and characterized. A 633 aa polypeptide containing two conserved Walker A and Walker B motifs was predicted from a continuous 1902 nt open reading frame. Quantitative real-time PCR was employed to determine the transcriptional levels of Tc-abcg-5 gene in adult male and female worms, which indicated high mRNA level of Tc-abcg-5 in the reproductive tract of adult female T. canis. Tc-abcg-5 was expressed to produce rabbit polyclonal antiserum against recombinant TcABCG5. Indirect-fluorescence immunohistochemical assays were carried out to detect the tissue distribution of TcABCG5, which showed predominant distribution of TcABCG5 in the uterus (especially in the germ cells) of adult female T. canis. Tissue transcription and expression pattern of Tc-abcg-5 indicated that Tc-abcg-5 might play essential roles in the reproduction of this parasitic nematode.
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Affiliation(s)
- Yong-Li Luo
- College of Animal Science, Southwest University, Chongqing, 402460, People's Republic of China
| | - Guang-Xu Ma
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Yong-Fang Luo
- College of Animal Science, Southwest University, Chongqing, 402460, People's Republic of China
| | - Ce-Yan Kuang
- College of Animal Science, Southwest University, Chongqing, 402460, People's Republic of China
| | - Ai-Yun Jiang
- College of Animal Science, Southwest University, Chongqing, 402460, People's Republic of China
| | - Guo-Qing Li
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
| | - Rong-Qiong Zhou
- College of Animal Science, Southwest University, Chongqing, 402460, People's Republic of China.
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33
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Aikawa T, Holm ML, Kanekiyo T. ABCA7 and Pathogenic Pathways of Alzheimer's Disease. Brain Sci 2018; 8:E27. [PMID: 29401741 PMCID: PMC5836046 DOI: 10.3390/brainsci8020027] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 02/01/2018] [Accepted: 02/03/2018] [Indexed: 12/22/2022] Open
Abstract
The ATP-binding cassette (ABC) reporter family functions to regulate the homeostasis of phospholipids and cholesterol in the central nervous system, as well as peripheral tissues. ABCA7 belongs to the A subfamily of ABC transporters, which shares 54% sequence identity with ABCA1. While ABCA7 is expressed in a variety of tissues/organs, including the brain, recent genome-wide association studies (GWAS) have identified ABCA7 gene variants as susceptibility loci for late-onset Alzheimer's disease (AD). More important, subsequent genome sequencing analyses have revealed that premature termination codon mutations in ABCA7 are associated with the increased risk for AD. Alzheimer's disease is a progressive neurodegenerative disease and the most common cause of dementia, where the accumulation and deposition of amyloid-β (Aβ) peptides cleaved from amyloid precursor protein (APP) in the brain trigger the pathogenic cascade of the disease. In consistence with human genetic studies, increasing evidence has demonstrated that ABCA7 deficiency exacerbates Aβ pathology using in vitro and in vivo models. While ABCA7 has been shown to mediate phagocytic activity in macrophages, ABCA7 is also involved in the microglial Aβ clearance pathway. Furthermore, ABCA7 deficiency results in accelerated Aβ production, likely by facilitating endocytosis and/or processing of APP. Taken together, current evidence suggests that ABCA7 loss-of-function contributes to AD-related phenotypes through multiple pathways. A better understanding of the function of ABCA7 beyond lipid metabolism in both physiological and pathological conditions becomes increasingly important to explore AD pathogenesis.
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Affiliation(s)
- Tomonori Aikawa
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
| | - Marie-Louise Holm
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
| | - Takahisa Kanekiyo
- Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
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34
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Serizier SB, McCall K. Scrambled Eggs: Apoptotic Cell Clearance by Non-Professional Phagocytes in the Drosophila Ovary. Front Immunol 2017; 8:1642. [PMID: 29238344 PMCID: PMC5712531 DOI: 10.3389/fimmu.2017.01642] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/09/2017] [Indexed: 01/20/2023] Open
Abstract
For half of a century, it has been known that non-professional phagocytes, such as fibroblasts, endothelial, and epithelial cells, are capable of efferocytosis (engulfment of apoptotic cells). Non-professional phagocytes differ from professional phagocytes in the range and efficiency of engulfment. Much of the recognition and underlying signaling machinery between non-professional and professional phagocytes is the same, but it is not known how the engulfment capacity of non-professional phagocytes is controlled. Moreover, the signaling networks involved in cell corpse recognition, engulfment, and phagosome maturation are only partially understood. The Drosophila ovary provides an excellent system to investigate the regulation of phagocytic activity by epithelial cells, a major class of non-professional phagocytes. During Drosophila oogenesis, mid-stage egg chambers undergo apoptosis of the germline in response to nutrient deprivation. Epithelial follicle cells then undergo major cell shape changes and concomitantly engulf the germline material. Our previous work has established that Draper and the integrin α-PS3/β-PS heterodimer are required in follicle cells for germline cell clearance. In addition, we have characterized phagosome maturation pathways, and found that the JNK pathway amplifies the engulfment response. In this review, we discuss recent advances on the interplay between engulfment pathways in the follicular epithelium for cell clearance in the Drosophila ovary. We also provide a comparison to apoptotic cell clearance mechanisms in C. elegans and mammals, illustrating strong conservation of efferocytosis mechanisms by non-professional phagocytes.
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Affiliation(s)
- Sandy B Serizier
- Department of Biology, Boston University, Boston, MA, United States.,Graduate Program in Molecular Biology, Cell Biology and Biochemistry, Boston University, Boston, MA, United States
| | - Kimberly McCall
- Department of Biology, Boston University, Boston, MA, United States
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35
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Morizawa YM, Hirayama Y, Ohno N, Shibata S, Shigetomi E, Sui Y, Nabekura J, Sato K, Okajima F, Takebayashi H, Okano H, Koizumi S. Reactive astrocytes function as phagocytes after brain ischemia via ABCA1-mediated pathway. Nat Commun 2017. [PMID: 28642575 PMCID: PMC5481424 DOI: 10.1038/s41467-017-00037-1] [Citation(s) in RCA: 242] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Astrocytes become reactive following various brain insults; however, the functions of reactive astrocytes are poorly understood. Here, we show that reactive astrocytes function as phagocytes after transient ischemic injury and appear in a limited spatiotemporal pattern. Following transient brain ischemia, phagocytic astrocytes are observed within the ischemic penumbra region during the later stage of ischemia. However, phagocytic microglia are mainly observed within the ischemic core region during the earlier stage of ischemia. Phagocytic astrocytes upregulate ABCA1 and its pathway molecules, MEGF10 and GULP1, which are required for phagocytosis, and upregulation of ABCA1 alone is sufficient for enhancement of phagocytosis in vitro. Disrupting ABCA1 in reactive astrocytes result in fewer phagocytic inclusions after ischemia. Together, these findings suggest that astrocytes are transformed into a phagocytic phenotype as a result of increase in ABCA1 and its pathway molecules and contribute to remodeling of damaged tissues and penumbra networks. Astrocytic phagocytosis has been shown to play a role in synaptic pruning during development, but whether adult astrocytes possess phagocytic ability is unclear. Here the authors show that following brain ischemia, reactive astrocytes become phagocytic and engulf debris via the ABCA1 pathway.
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Affiliation(s)
- Yosuke M Morizawa
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan.,Department of Super-network Brain Physiology, Graduate School of Life Science, Tohoku University, Sendai, Miyagi, 980-8575, Japan
| | - Yuri Hirayama
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan
| | - Nobuhiko Ohno
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, 444-8585, Japan
| | - Shinsuke Shibata
- Department of Physiology and Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku, Tokyo, 160-8582, Japan
| | - Eiji Shigetomi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan
| | - Yang Sui
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Aichi, 444-8585, Japan
| | - Junichi Nabekura
- Division of Homeostatic Development, National Institute for Physiological Sciences, Okazaki, Aichi, 444-8585, Japan.,Department of Physiological Sciences, The Graduate School for Advanced Study, Hayama, Kanagawa, 240-0193, Japan
| | - Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, 371-8512, Japan
| | - Fumikazu Okajima
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, 371-8512, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Niigata, 951-8510, Japan
| | - Hideyuki Okano
- Department of Physiology and Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku, Tokyo, 160-8582, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan.
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36
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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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37
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Engulfment signals and the phagocytic machinery for apoptotic cell clearance. Exp Mol Med 2017; 49:e331. [PMID: 28496201 PMCID: PMC5454446 DOI: 10.1038/emm.2017.52] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 12/15/2016] [Indexed: 02/07/2023] Open
Abstract
The clearance of apoptotic cells is an essential process for tissue homeostasis. To this end, cells undergoing apoptosis must display engulfment signals, such as ‘find-me' and ‘eat-me' signals. Engulfment signals are recognized by multiple types of phagocytic machinery in phagocytes, leading to prompt clearance of apoptotic cells. In addition, apoptotic cells and phagocytes release tolerogenic signals to reduce immune responses against apoptotic cell-derived self-antigens. Here we discuss recent advances in our knowledge of engulfment signals, the phagocytic machinery and the signal transduction pathways for apoptotic cell engulfment.
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38
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Polymorphism in ABC transporter genes of Dirofilaria immitis. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:227-235. [PMID: 28494332 PMCID: PMC5421822 DOI: 10.1016/j.ijpddr.2017.04.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/26/2017] [Accepted: 04/28/2017] [Indexed: 11/22/2022]
Abstract
Dirofilaria immitis, a filarial nematode, causes dirofilariasis in dogs, cats and occasionally in humans. Prevention of the disease has been mainly by monthly use of the macrocyclic lactone (ML) endectocides during the mosquito transmission season. Recently, ML resistance has been confirmed in D. immitis and therefore, there is a need to find new classes of anthelmintics. One of the mechanisms associated with ML resistance in nematodes has been the possible role of ATP binding cassette (ABC) transporters in reducing drug concentrations at receptor sites. ABC transporters, mainly from sub-families B, C and G, may contribute to multidrug resistance (MDR) by active efflux of drugs out of the cell. Gene products of ABC transporters may thus serve as the targets for agents that may modulate susceptibility to drugs, by inhibiting drug transport. ABC transporters are believed to be involved in a variety of physiological functions critical to the parasite, such as sterol transport, and therefore may also serve as the target for drugs that can act as anthelmintics on their own. Knowledge of polymorphism in these ABC transporter genes in nematode parasites could provide useful information for the process of drug design. We have identified 15 ABC transporter genes from sub-families A, B, C and G, in D. immitis, by comparative genomic approaches and analyzed them for polymorphism. Whole genome sequencing data from four ML susceptible (SUS) and four loss of efficacy (LOE) pooled populations were used for single nucleotide polymorphism (SNP) genotyping. Out of 231 SNPs identified in those 15 ABC transporter genes, 89 and 75 of them were specific to the SUS or LOE populations, respectively. A few of the SNPs identified may affect gene expression, protein function, substrate specificity or resistance development and may be useful for transporter inhibitor/anthelmintic drug design, or in order to anticipate resistance development. In the D. immitis genome, all ABC-A, -B, -C and -G transporter genes were identified. Within 15 ABC transporter genes identified in D. immitis, 231 SNP loci were found. Four exonic SNPs caused changes in predicted secondary structure of ABC proteins. D. immitis populations have low genetic variability among ABC transporter genes.
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39
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Penberthy KK, Ravichandran KS. Apoptotic cell recognition receptors and scavenger receptors. Immunol Rev 2016; 269:44-59. [PMID: 26683144 DOI: 10.1111/imr.12376] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Phosphatidylserine recognition receptors are a highly diverse set of receptors grouped by their ability to recognize the 'eat-me' signal phosphatidylserine on apoptotic cells. Most of the phosphatidylserine recognition receptors dampen inflammation by inducing the production of anti-inflammatory mediators during the phagocytosis of apoptotic corpses. However, many phosphatidylserine receptors are also capable of recognizing other ligands, with some receptors being categorized as scavenger receptors. It is now appreciated that these receptors can elicit different downstream events for particular ligands. Therefore, how phosphatidylserine recognition receptors mediate specific signals during recognition of apoptotic cells versus other ligands, and how this might help regulate the inflammatory state of a tissue is an important question that is not fully understood. Here, we revisit the work on signaling downstream of the phosphatidylserine recognition receptor BAI1, and evaluate how these and other signaling modules mediate signaling downstream from other receptors, including Stabilin-2, MerTK, and αvβ5. We also propose the concept that phosphatidylserine recognition receptors could be viewed as a subset of scavenger receptors that are capable of eliciting anti-inflammatory responses to apoptotic cells.
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Affiliation(s)
- Kristen K Penberthy
- Department of Microbiology, Immunology, and Cancer Biology, Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, and Cancer Biology, Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA
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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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Dohmen LCT, Navas A, Vargas DA, Gregory DJ, Kip A, Dorlo TPC, Gomez MA. Functional Validation of ABCA3 as a Miltefosine Transporter in Human Macrophages: IMPACT ON INTRACELLULAR SURVIVAL OF LEISHMANIA (VIANNIA) PANAMENSIS. J Biol Chem 2016; 291:9638-47. [PMID: 26903515 DOI: 10.1074/jbc.m115.688168] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Indexed: 12/25/2022] Open
Abstract
Within its mammalian host, Leishmania resides and replicates as an intracellular parasite. The direct activity of antileishmanials must therefore depend on intracellular drug transport, metabolism, and accumulation within the host cell. In this study, we explored the role of human macrophage transporters in the intracellular accumulation and antileishmanial activity of miltefosine (MLF), the only oral drug available for the treatment of visceral and cutaneous leishmaniasis (CL). Membrane transporter gene expression in primary human macrophages infected in vitro with Leishmania Viannia panamensis and exposed to MLF showed modulation of ABC and solute liquid carrier transporters gene transcripts. Among these, ABCA3, a lipid transporter, was significantly induced after exposure to MLF, and this induction was confirmed in primary macrophages from CL patients. Functional validation of MLF as a substrate for ABCA3 was performed by shRNA gene knockdown (KD) in THP-1 monocytes. Intracellular accumulation of radiolabeled MLF was significantly higher in ABCA3(KD) macrophages. ABCA3(KD) resulted in increased cytotoxicity induced by MLF exposure. ABCA3 gene expression inversely correlated with intracellular MLF content in primary macrophages from CL patients. ABCA3(KD) reduced parasite survival during macrophage infection with an L. V. panamensis strain exhibiting low in vitro susceptibility to MLF. Confocal microscopy showed ABCA3 to be located in the cell membrane of resting macrophages and in intracellular compartments in L. V. panamensis-infected cells. These results provide evidence of ABCA3 as an MLF efflux transporter in human macrophages and support its role in the direct antileishmanial effect of this alkylphosphocholine drug.
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Affiliation(s)
- Luuk C T Dohmen
- From the Centro Internacional de Entrenamiento e Investigaciones Médicas, Cra. 125 # 19-225 Cali, Colombia, the Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3508 TB Utrecht, The Netherlands
| | - Adriana Navas
- From the Centro Internacional de Entrenamiento e Investigaciones Médicas, Cra. 125 # 19-225 Cali, Colombia
| | - Deninson Alejandro Vargas
- From the Centro Internacional de Entrenamiento e Investigaciones Médicas, Cra. 125 # 19-225 Cali, Colombia
| | - David J Gregory
- the Molecular and Integrative Physiological Sciences, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Anke Kip
- the Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3508 TB Utrecht, The Netherlands, the Department of Pharmacy and Pharmacology, Antoni van Leeuwenhoek Hospital/Slotervaart Hospital, 1066 CX Amsterdam, The Netherlands, and
| | - Thomas P C Dorlo
- the Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3508 TB Utrecht, The Netherlands, the Department of Pharmaceutical Biosciences, Uppsala University, 751 24 Uppsala, Sweden
| | - Maria Adelaida Gomez
- From the Centro Internacional de Entrenamiento e Investigaciones Médicas, Cra. 125 # 19-225 Cali, Colombia,
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Do not let death do us part: 'find-me' signals in communication between dying cells and the phagocytes. Cell Death Differ 2016; 23:979-89. [PMID: 26891690 DOI: 10.1038/cdd.2016.13] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/04/2016] [Accepted: 01/07/2016] [Indexed: 12/12/2022] Open
Abstract
The turnover and clearance of cells is an essential process that is part of many physiological and pathological processes. Improper or deficient clearance of apoptotic cells can lead to excessive inflammation and autoimmune disease. The steps involved in cell clearance include: migration of the phagocyte toward the proximity of the dying cells, specific recognition and internalization of the dying cell, and degradation of the corpse. The ability of phagocytes to recognize and react to dying cells to perform efficient and immunologically silent engulfment has been well-characterized in vitro and in vivo. However, how apoptotic cells themselves initiate the corpse removal and also influence the cells within the neighboring environment during clearance was less understood. Recent exciting observations suggest that apoptotic cells can attract phagocytes through the regulated release of 'find-me' signals. More recent studies also suggest that these find-me signals can have additional roles outside of phagocyte attraction to help orchestrate engulfment. This review will discuss our current understanding of the different find-me signals released by apoptotic cells, how they may be relevant in vivo, and their additional roles in facilitating engulfment.
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Li Z, Zhou Z. How are necrotic cells recognized by their predators? WORM 2015; 5:e1120400. [PMID: 27073733 PMCID: PMC4805362 DOI: 10.1080/21624054.2015.1120400] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 11/08/2015] [Accepted: 11/10/2015] [Indexed: 11/22/2022]
Abstract
Necrosis is a type of cell death often caused by cell injury and is linked to human diseases including neuron degeneration, stroke, and cancer. Cells undergoing necrosis are engulfed and degraded by engulfing cells, their predators. The mechanisms by which necrotic cells are recognized and removed remain elusive. Here we comment on our recent findings that reveal new molecular mechanisms of necrotic-cell recognition. Through studying the C. elegans touch neurons undergoing excitotoxic necrosis, we identified a receptor/ligand pair that enables engulfing cells to recognize necrotic neurons. The phagocytic receptor CED-1 is activated through interaction with its ligand phosphatidylserine (PS), exposed on the surface of necrotic cells. Furthermore, against the common belief that necrotic cells have ruptured plasma membrane, we found that necrotic C. elegans touch neurons actively present PS on their outer surfaces while maintaining plasma membrane integrity. We further identified 2 mechanisms governing the presentation of PS, one of which is shared with cells undergoing apoptosis, a “cell suicide” event, whereas the other is unique to necrotic neurons. The influx of Ca2+, a key necrosis-triggering factor, is implicated in activating a neuronal PS-scramblase for PS exposure. We propose that the mechanisms controlling PS-exposure and necrotic-cell recognition by engulfing cells are likely conserved from worms to humans.
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Affiliation(s)
- Zao Li
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, TX, USA
| | - Zheng Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine , Houston, TX, USA
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Abstract
Cell death is a common and important feature of animal development, and cell death defects underlie many human disease states. The nematode Caenorhabditis elegans has proven fertile ground for uncovering molecular and cellular processes controlling programmed cell death. A core pathway consisting of the conserved proteins EGL-1/BH3-only, CED-9/BCL2, CED-4/APAF1, and CED-3/caspase promotes most cell death in the nematode, and a conserved set of proteins ensures the engulfment and degradation of dying cells. Multiple regulatory pathways control cell death onset in C. elegans, and many reveal similarities with tumor formation pathways in mammals, supporting the idea that cell death plays key roles in malignant progression. Nonetheless, a number of observations suggest that our understanding of developmental cell death in C. elegans is incomplete. The interaction between dying and engulfing cells seems to be more complex than originally appreciated, and it appears that key aspects of cell death initiation are not fully understood. It has also become apparent that the conserved apoptotic pathway is dispensable for the demise of the C. elegans linker cell, leading to the discovery of a previously unexplored gene program promoting cell death. Here, we review studies that formed the foundation of cell death research in C. elegans and describe new observations that expand, and in some cases remodel, this edifice. We raise the possibility that, in some cells, more than one death program may be needed to ensure cell death fidelity.
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Affiliation(s)
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, USA.
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Necrotic Cells Actively Attract Phagocytes through the Collaborative Action of Two Distinct PS-Exposure Mechanisms. PLoS Genet 2015; 11:e1005285. [PMID: 26061275 PMCID: PMC4464654 DOI: 10.1371/journal.pgen.1005285] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/14/2015] [Indexed: 11/19/2022] Open
Abstract
Necrosis, a kind of cell death closely associated with pathogenesis and genetic programs, is distinct from apoptosis in both morphology and mechanism. Like apoptotic cells, necrotic cells are swiftly removed from animal bodies to prevent harmful inflammatory and autoimmune responses. In the nematode Caenorhabditis elegans, gain-of-function mutations in certain ion channel subunits result in the excitotoxic necrosis of six touch neurons and their subsequent engulfment and degradation inside engulfing cells. How necrotic cells are recognized by engulfing cells is unclear. Phosphatidylserine (PS) is an important apoptotic-cell surface signal that attracts engulfing cells. Here we observed PS exposure on the surface of necrotic touch neurons. In addition, the phagocytic receptor CED-1 clusters around necrotic cells and promotes their engulfment. The extracellular domain of CED-1 associates with PS in vitro. We further identified a necrotic cell-specific function of CED-7, a member of the ATP-binding cassette (ABC) transporter family, in promoting PS exposure. In addition to CED-7, anoctamin homolog-1 (ANOH-1), the C. elegans homolog of the mammalian Ca(2+)-dependent phospholipid scramblase TMEM16F, plays an independent role in promoting PS exposure on necrotic cells. The combined activities from CED-7 and ANOH-1 ensure efficient exposure of PS on necrotic cells to attract their phagocytes. In addition, CED-8, the C. elegans homolog of mammalian Xk-related protein 8 also makes a contribution to necrotic cell-removal at the first larval stage. Our work indicates that cells killed by different mechanisms (necrosis or apoptosis) expose a common "eat me" signal to attract their phagocytic receptor(s); furthermore, unlike what was previously believed, necrotic cells actively present PS on their outer surfaces through at least two distinct molecular mechanisms rather than leaking out PS passively.
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EFF-1-mediated regenerative axonal fusion requires components of the apoptotic pathway. Nature 2015; 517:219-22. [DOI: 10.1038/nature14102] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 11/19/2014] [Indexed: 02/03/2023]
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Snodgrass CJ, Burnham-Marusich AR, Meteer JC, Berninsone PM. Conserved ion and amino acid transporters identified as phosphorylcholine-modified N-glycoproteins by metabolic labeling with propargylcholine in Caenorhabditis elegans cells. Glycobiology 2014; 25:403-11. [PMID: 25387872 DOI: 10.1093/glycob/cwu122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Phosphorylcholine (PC) modification of proteins by pathogens has been implicated in mediating host-pathogen interactions. Parasitic nematodes synthesize PC-modified biomolecules that can modulate the host's antibody and cytokine production to favor nematode survival, contributing to long-term infections. Only two nematode PC-modified proteins (PC-proteins) have been unequivocally identified, yet discovering the protein targets of PC modification will be paramount to understanding the role(s) that this epitope plays in nematode biology. A major hurdle in the field has been the lack of techniques for selective purification of PC-proteins. The nonparasitic nematode Caenorhabditis elegans expresses PC-modified N-linked glycans, offering an attractive model to study the biology of PC-modification. We developed a robust method to identify PC-proteins by metabolic labeling of primary embryonic C. elegans cells with propargylcholine, an alkyne-modified choline analog. Cu(I)-catalyzed cycloaddition with biotin-azide enables streptavidin purification and subsequent high-throughput LC-MS identification of propargyl-labeled proteins. All proteins identified using stringent criteria are known or predicted to be membrane or secreted proteins, consistent with the model of a Golgi-resident, putative PC-transferase. Of the 55 PC-N-glycosylation sites reported, 33 have been previously observed as N-glycosylation sites in high-throughput screens of C. elegans. Several identified PC-proteins are nematode-specific proteins, but 10 of the PC-proteins are widely conserved ion transporters and amino acid transporters, while eight are conserved proteins involved in synaptic function. This finding suggests a functional role for PC-modification beyond immunomodulation. The approach presented in this study provides a method to identify PC-proteins in C. elegans and related nematodes.
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Affiliation(s)
| | | | - John C Meteer
- Department of Biology, University of Nevada, Reno, NV 89557, USA
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Signaling by the engulfment receptor draper: a screen in Drosophila melanogaster implicates cytoskeletal regulators, Jun N-terminal Kinase, and Yorkie. Genetics 2014; 199:117-34. [PMID: 25395664 DOI: 10.1534/genetics.114.172544] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Draper, the Drosophila melanogaster homolog of the Ced-1 protein of Caenorhabditis elegans, is a cell-surface receptor required for the recognition and engulfment of apoptotic cells, glial clearance of axon fragments and dendritic pruning, and salivary gland autophagy. To further elucidate mechanisms of Draper signaling, we screened chromosomal deficiencies to identify loci that dominantly modify the phenotype of overexpression of Draper isoform II (suppressed differentiation of the posterior crossvein in the wing). We found evidence for 43 genetic modifiers of Draper II. Twenty-four of the 37 suppressor loci and 3 of the 6 enhancer loci were identified. An additional 5 suppressors and 2 enhancers were identified among mutations in functionally related genes. These studies reveal positive contributions to Drpr signaling for the Jun N-terminal Kinase pathway, supported by genetic interactions with hemipterous, basket, jun, and puckered, and for cytoskeleton regulation as indicated by genetic interactions with rac1, rac2, RhoA, myoblast city, Wiskcott-Aldrich syndrome protein, and the formin CG32138, and for yorkie and expanded. These findings indicate that Jun N-terminal Kinase activation and cytoskeletal remodeling collaborate in Draper signaling. Relationships between Draper signaling and Decapentaplegic signaling, insulin signaling, Salvador/Warts/Hippo signaling, apical-basal cell polarity, and cellular responses to mechanical forces are also discussed.
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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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