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Mazaheri F, Breus O, Durdu S, Haas P, Wittbrodt J, Gilmour D, Peri F. Distinct roles for BAI1 and TIM-4 in the engulfment of dying neurons by microglia. Nat Commun 2014; 5:4046. [DOI: 10.1038/ncomms5046] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 05/05/2014] [Indexed: 12/31/2022] Open
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Stevenson C, de la Rosa G, Anderson CS, Murphy PS, Capece T, Kim M, Elliott MR. Essential role of Elmo1 in Dock2-dependent lymphocyte migration. THE JOURNAL OF IMMUNOLOGY 2014; 192:6062-70. [PMID: 24821968 DOI: 10.4049/jimmunol.1303348] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Elmo1 and Elmo2 are highly homologous cytoplasmic adaptor proteins that interact with Dock family guanine nucleotide exchange factors to promote activation of the small GTPase Rac. In T lymphocytes, Dock2 is essential for CCR7- and CXCR4-dependent Rac activation and chemotaxis, but the role of Elmo proteins in regulating Dock2 function in primary T cells is not known. In this article, we show that endogenous Elmo1, but not Elmo2, interacts constitutively with Dock2 in mouse and human primary T cells. CD4(+) T cells from Elmo1(-/-) mice were profoundly impaired in polarization, Rac activation, and chemotaxis in response to CCR7 and CXCR4 stimulation. Transfection of full-length Elmo1, but not Elmo2 or a Dock2-binding mutant of Elmo1, rescued defective migration of Elmo1(-/-) T cells. Interestingly, Dock2 protein levels were reduced by 4-fold in Elmo1(-/-) lymphocytes despite normal levels of Dock2 mRNA. Dock2 polyubiquitination was increased in Elmo1(-/-) T cells, and treatment with proteasome inhibitors partially restored Dock2 levels in Elmo1(-/-) T cells. Finally, we show that Dock2 is directly ubiquitinated in CD4(+) T cells and that Elmo1 expression in heterologous cells inhibits ubiquitination of Dock2. Taken together, these findings reveal a previously unknown, nonredundant role for Elmo1 in controlling Dock2 levels and Dock2-dependent T cell migration in primary lymphocytes. Inhibition of Dock2 has therapeutic potential as a means to control recruitment of pathogenic lymphocytes in diseased tissues. This work provides valuable insights into the molecular regulation of Dock2 by Elmo1 that can be used to design improved inhibitors that target the Elmo-Dock-Rac signaling complex.
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Affiliation(s)
- Catherine Stevenson
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
| | - Gonzalo de la Rosa
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
| | - Christopher S Anderson
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
| | - Patrick S Murphy
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
| | - Tara Capece
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
| | - Minsoo Kim
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
| | - Michael R Elliott
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642; and David H. Smith Center for Vaccine Biology and Imunology, University of Rochester Medical Center, Rochester, NY 14642
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Tasdemir-Yilmaz OE, Freeman MR. Astrocytes engage unique molecular programs to engulf pruned neuronal debris from distinct subsets of neurons. Genes Dev 2013; 28:20-33. [PMID: 24361692 PMCID: PMC3894410 DOI: 10.1101/gad.229518.113] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neural circuit assembly involves an initial overproduction of neurons and synaptic connections, followed by their selective elimination. Tasdemir-Yilmaz and Freeman show that Drosophila larval astrocytes are the primary phagocytic cell type in the pupal CNS neuropil. MB γ neuron axons are engulfed by astrocytes using the Draper and Crk/Mbc/dCed-12 signaling pathways, while Crk/Mbc/dCed-12, but not Draper, mediates the elimination of vCrz+ neurites. Eliminating Draper signaling delays early vCrz+ neurite degeneration, suggesting that glial cells promote neurite destruction through engulfment signaling. Precise neural circuit assembly is achieved by initial overproduction of neurons and synapses, followed by refinement through elimination of exuberant neurons and synapses. Glial cells are the primary cells responsible for clearing neuronal debris, but the cellular and molecular basis of glial pruning is poorly defined. Here we show that Drosophila larval astrocytes transform into phagocytes through activation of a cell-autonomous, steroid-dependent program at the initiation of metamorphosis and are the primary phagocytic cell type in the pupal neuropil. We examined the developmental elimination of two neuron populations—mushroom body (MB) γ neurons and vCrz+ neurons (expressing Corazonin [Crz] neuropeptide in the ventral nerve cord [VNC])—where only neurites are pruned or entire cells are eliminated, respectively. We found that MB γ axons are engulfed by astrocytes using the Draper and Crk/Mbc/dCed-12 signaling pathways in a partially redundant manner. In contrast, while elimination of vCrz+ cell bodies requires Draper, elimination of vCrz+ neurites is mediated by Crk/Mbc/dCed-12 but not Draper. Intriguingly, we also found that elimination of Draper delayed vCrz+ neurite degeneration, suggesting that glia promote neurite destruction through engulfment signaling. This study identifies a novel role for astrocytes in the clearance of synaptic and neuronal debris and for Crk/Mbc/dCed-12 as a new glial pathway mediating pruning and reveals, unexpectedly, that the engulfment signaling pathways engaged by glia depend on whether neuronal debris was generated through cell death or local pruning.
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Affiliation(s)
- Ozge E Tasdemir-Yilmaz
- Department of Neurobiology, Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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Gardet A, Zheng TS, Viney JL. Genetic architecture of human fibrotic diseases: disease risk and disease progression. Front Pharmacol 2013; 4:159. [PMID: 24391588 PMCID: PMC3866586 DOI: 10.3389/fphar.2013.00159] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 12/03/2013] [Indexed: 12/12/2022] Open
Abstract
Genetic studies of human diseases have identified multiple genetic risk loci for various fibrotic diseases. This has provided insights into the myriad of biological pathways potentially involved in disease pathogenesis. These discoveries suggest that alterations in immune responses, barrier function, metabolism and telomerase activity may be implicated in the genetic risks for fibrotic diseases. In addition to genetic disease-risks, the identification of genetic disease-modifiers associated with disease complications, severity or prognosis provides crucial insights into the biological processes implicated in disease progression. Understanding the biological processes driving disease progression may be critical to delineate more effective strategies for therapeutic interventions. This review provides an overview of current knowledge and gaps regarding genetic disease-risks and genetic disease-modifiers in human fibrotic diseases.
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Liu B, Xu N, Man Y, Shen H, Avital I, Stojadinovic A, Liao DJ. Apoptosis in Living Animals Is Assisted by Scavenger Cells and Thus May Not Mainly Go through the Cytochrome C-Caspase Pathway. J Cancer 2013; 4:716-23. [PMID: 24312141 PMCID: PMC3842440 DOI: 10.7150/jca.7577] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/19/2013] [Indexed: 11/21/2022] Open
Abstract
Because billions of cells die every day in their bodies, animals have evolutionarily developed apoptosis to preserve the tissue environment from adverse effects of dead cells, a process achieved via phagocytosis of the cell corpses by professional or amateur phagocytes that are collectively referred to as scavengers. Hence, apoptosis is a merger of two procedures separately occurring inside the dying and the scavenger cells, respectively. The task of apoptosis research is to study how these death procedures occur without hurting the host tissues, and recruitment of in vitro system into the study must be justified for this purpose. Cells in culture have no motivation to preserve the environment, and their death does not involve corpse clearance by scavengers. Therefore, programmed cell death in culture should be redefined, for example as stress-induced cell death, to avoid many sources of confusions, since the word “apoptosis” had already been defined, prior to the era of cell culture, as a silent and beneficial cell suicide with corpse clearance as a distinctive hallmark. We should start over again on apoptosis research by determining whether different physiological apoptotic procedures in animals involve the cytochrome c-caspase pathway, since it has been established from cultured cells as a central mechanism of “apoptosis” but whether it overarches any physiological apoptotic procedure in animals is still unclear. Probably, cells in living animals are programmed to use scavengers to assist their apoptosis but cells in culture have no scavengers to help and thus need to go mainly through the cytochrome c-caspase pathway.
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Affiliation(s)
- Bingya Liu
- 1. Shanghai Key Laboratory of Gastric Neoplasms, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P. R. China
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Olsson M, Tintle L, Kierczak M, Perloski M, Tonomura N, Lundquist A, Murén E, Fels M, Tengvall K, Pielberg G, Dufaure de Citres C, Dorso L, Abadie J, Hanson J, Thomas A, Leegwater P, Hedhammar Å, Lindblad-Toh K, Meadows JRS. Thorough investigation of a canine autoinflammatory disease (AID) confirms one main risk locus and suggests a modifier locus for amyloidosis. PLoS One 2013; 8:e75242. [PMID: 24130694 PMCID: PMC3793984 DOI: 10.1371/journal.pone.0075242] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 08/13/2013] [Indexed: 12/04/2022] Open
Abstract
Autoinflammatory disease (AID) manifests from the dysregulation of the innate immune system and is characterised by systemic and persistent inflammation. Clinical heterogeneity leads to patients presenting with one or a spectrum of phenotypic signs, leading to difficult diagnoses in the absence of a clear genetic cause. We used separate genome-wide SNP analyses to investigate five signs of AID (recurrent fever, arthritis, breed specific secondary dermatitis, otitis and systemic reactive amyloidosis) in a canine comparative model, the pure bred Chinese Shar-Pei. Analysis of 255 DNA samples revealed a shared locus on chromosome 13 spanning two peaks of association. A three-marker haplotype based on the most significant SNP (p<2.6×10−8) from each analysis showed that one haplotypic pair (H13-11) was present in the majority of AID individuals, implicating this as a shared risk factor for all phenotypes. We also noted that a genetic signature (FST) distinguishing the phenotypic extremes of the breed specific Chinese Shar-Pei thick and wrinkled skin, flanked the chromosome 13 AID locus; suggesting that breed development and differentiation has played a parallel role in the genetics of breed fitness. Intriguingly, a potential modifier locus for amyloidosis was revealed on chromosome 14, and an investigation of candidate genes from both this and the chromosome 13 regions revealed significant (p<0.05) renal differential expression in four genes previously implicated in kidney or immune health (AOAH, ELMO1, HAS2 and IL6). These results illustrate that phenotypic heterogeneity need not be a reflection of genetic heterogeneity, and that genetic modifiers of disease could be masked if syndromes were not first considered as individual clinical signs and then as a sum of their component parts.
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Affiliation(s)
- Mia Olsson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail: (MO); (KL-T); (JRSM)
| | - Linda Tintle
- Wurtsboro Veterinary Clinic, Wurtsboro, New York, United States of America
| | - Marcin Kierczak
- Computational Genetics Section, Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Michele Perloski
- Broad Institute of Harvard and Massachusetts Institute of Technology (MIT), Cambridge, MA, United States of America
| | - Noriko Tonomura
- Broad Institute of Harvard and Massachusetts Institute of Technology (MIT), Cambridge, MA, United States of America
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts, United States of America
| | - Andrew Lundquist
- Broad Institute of Harvard and Massachusetts Institute of Technology (MIT), Cambridge, MA, United States of America
| | - Eva Murén
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Max Fels
- Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Katarina Tengvall
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Gerli Pielberg
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | | | - Laetitia Dorso
- LUNAM University, Oniris, AMaROC Unit, Nantes, F-44307, France
| | - Jérôme Abadie
- LUNAM University, Oniris, AMaROC Unit, Nantes, F-44307, France
| | - Jeanette Hanson
- Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Anne Thomas
- ANTAGENE Animal Genetics Laboratory, La Tour de Salvagny (69 Lyon), France
| | - Peter Leegwater
- Department of Clinical Sciences of Companion Animals, Utrecht University, Utrecht, The Netherlands
| | - Åke Hedhammar
- Department of Clinical Sciences, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Kerstin Lindblad-Toh
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Broad Institute of Harvard and Massachusetts Institute of Technology (MIT), Cambridge, MA, United States of America
- * E-mail: (MO); (KL-T); (JRSM)
| | - Jennifer R. S. Meadows
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail: (MO); (KL-T); (JRSM)
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Basu S, Sachidanandan C. Zebrafish: a multifaceted tool for chemical biologists. Chem Rev 2013; 113:7952-80. [PMID: 23819893 DOI: 10.1021/cr4000013] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Sandeep Basu
- Council of Scientific and Industrial Research-Institute of Genomics & Integrative Biology (CSIR-IGIB) , South Campus, New Delhi 110025, India
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Dzhagalov IL, Chen KG, Herzmark P, Robey EA. Elimination of self-reactive T cells in the thymus: a timeline for negative selection. PLoS Biol 2013; 11:e1001566. [PMID: 23700386 PMCID: PMC3660248 DOI: 10.1371/journal.pbio.1001566] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 04/11/2013] [Indexed: 01/22/2023] Open
Abstract
Two-photon microscopy and flow cytometry reveal the timing of thymocyte death and the surprisingly close coupling between cell death and phagocytosis during negative selection in thymic slices. The elimination of autoreactive T cells occurs via thymocyte apoptosis and removal by thymic phagocytes, but the sequence of events in vivo, and the relationship between thymocyte death and phagocytic clearance, are unknown. Here we address these questions by following a synchronized cohort of thymocytes undergoing negative selection within a three-dimensional thymic tissue environment, from the initial encounter with a negative selecting ligand to thymocyte death and clearance. Encounter with cognate peptide–MHC complexes results in rapid calcium flux and migratory arrest in auto-reactive thymocytes over a broad range of peptide concentrations, followed by a lag period in which gene expression changes occurred, but there was little sign of thymocyte death. Caspase 3 activation and thymocyte loss were first detectable at 2 and 3 hours, respectively, and entry of individual thymocytes into the death program occurred asynchronously over the next 10 hours. Two-photon time-lapse imaging revealed that thymocyte death and phagocytosis occurred simultaneously, often with thymocytes engulfed prior to changes in chromatin and membrane permeability. Our data provide a timeline for negative selection and reveal close coupling between cell death and clearance in the thymus. As an important safeguard against autoimmunity, T cells bearing autoreactive T cell antigen receptors are eliminated during their development in the thymus, a process known as negative selection. Although much is known about the molecular events involved in negative selection, surprisingly little is known about the dynamic aspects of the process. Here we examine a synchronized population of developing T cells (thymocytes) undergoing negative selection within three-dimensional living thymic tissue. We show that the initial encounter with negative selecting ligands results in migratory arrest, but in spite of this synchronous early response, individual thymocytes then undergo delayed and asynchronous entry into the death program between 2 and 12 hours thereafter. Using time-lapse two-photon imaging, we reveal that thymocyte death and the clearance of the dead cells invariably occur together, with many thymocytes already engulfed by a macrophage before the cell death-related changes in chromatin and membrane permeability are evident. These data provide a timeline of the major events during negative selection, and suggest close coupling between thymocyte death and clearance by macrophages.
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Affiliation(s)
- Ivan Lilyanov Dzhagalov
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Katherine Grace Chen
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Paul Herzmark
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Ellen A. Robey
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- * E-mail:
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Rudrapatna VA, Bangi E, Cagan RL. Caspase signalling in the absence of apoptosis drives Jnk-dependent invasion. EMBO Rep 2013; 14:172-7. [PMID: 23306653 DOI: 10.1038/embor.2012.217] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 12/04/2012] [Accepted: 12/12/2012] [Indexed: 11/09/2022] Open
Abstract
Tumours evolve several mechanisms to evade apoptosis, yet many resected carcinomas show significantly elevated caspase activity. Moreover, caspase activity is positively correlated with tumour aggression and adverse patient outcome. These observations indicate that caspases might have a functional role in promoting tumour invasion and metastasis. Using a Drosophila model of invasion, we show that precise effector caspase activity drives cell invasion without initiating apoptosis. Affected cells express the matrix metalloprotinase Mmp1 and invade by activating Jnk. Our results link Jnk and effector caspase signalling during the invasive process and suggest that tumours under apoptotic stresses from treatment, immune surveillance or intrinsic signals might be induced further along the metastatic cascade.
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Affiliation(s)
- Vivek A Rudrapatna
- Department of Developmental and Regenerative Biology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, New York 10029, USA
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