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Cortical actin recovery at the immunological synapse leads to termination of lytic granule secretion in cytotoxic T lymphocytes. Proc Natl Acad Sci U S A 2017; 114:E6585-E6594. [PMID: 28716933 DOI: 10.1073/pnas.1710751114] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
CD8+ cytotoxic T lymphocytes (CTLs) eliminate virally infected cells through directed secretion of specialized lytic granules. Because a single CTL can kill multiple targets, degranulation must be tightly regulated. However, how CTLs regulate the termination of granule secretion remains unclear. Previous work demonstrated that centralized actin reduction at the immune synapse precedes degranulation. Using a combination of live confocal, total internal reflection fluorescence, and superresolution microscopy, we now show that, after granule fusion, actin recovers at the synapse and no further secretion is observed. Depolymerization of actin led to resumed granule secretion, suggesting that recovered actin acts as a barrier preventing sustained degranulation. Furthermore, RAB27a-deficient CTLs, which do not secrete cytotoxic granules, failed to recover actin at the synapse, suggesting that RAB27a-mediated granule secretion is required for actin recovery. Finally, we show that both actin clearance and recovery correlated with synaptic phosphatidylinositol 4,5-bisphosphate (PIP2) and that alterations in PIP2 at the immunological synapse regulate cortical actin in CTLs, providing a potential mechanism through which CTLs control cortical actin density. Our work provides insight into actin-related mechanisms regulating CTL secretion that may facilitate serial killing during immune responses.
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52
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Dynamic alterations in decoy VEGF receptor-1 stability regulate angiogenesis. Nat Commun 2017; 8:15699. [PMID: 28589930 PMCID: PMC5467243 DOI: 10.1038/ncomms15699] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 04/20/2017] [Indexed: 12/11/2022] Open
Abstract
Blood vessel expansion is driven by sprouting angiogenesis of endothelial cells, and is essential for development, wound healing and disease. Membrane-localized vascular endothelial growth factor receptor-1 (mVEGFR1) is an endothelial cell-intrinsic decoy receptor that negatively modulates blood vessel morphogenesis. Here we show that dynamic regulation of mVEGFR1 stability and turnover in blood vessels impacts angiogenesis. mVEGFR1 is highly stable and constitutively internalizes from the plasma membrane. Post-translational palmitoylation of mVEGFR1 is a binary stabilization switch, and ligand engagement leads to depalmitoylation and lysosomal degradation. Trafficking of palmitoylation enzymes via Rab27a regulates mVEGFR1 stability, as reduced levels of Rab27a impaired palmitoylation of mVEGFR1, decreased its stability, and elevated blood vessel sprouting and in vivo angiogenesis. These findings identify a regulatory axis affecting blood vessel morphogenesis that highlights exquisite post-translational regulation of mVEGFR1 in its role as a molecular rheostat.
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53
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Smith VL, Cheng Y, Bryant BR, Schorey JS. Exosomes function in antigen presentation during an in vivo Mycobacterium tuberculosis infection. Sci Rep 2017; 7:43578. [PMID: 28262829 PMCID: PMC5338015 DOI: 10.1038/srep43578] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/25/2017] [Indexed: 01/03/2023] Open
Abstract
Mycobacterium tuberculosis-infected macrophages and dendritic cells are limited in their ability to present antigen to CD4+ T cells suggesting that other mechanism of antigen presentation are driving the robust T cell response observed during an M. tuberculosis infection. These mechanisms could include antigens present in apoptotic bodies, necrotic debris, exosomes or even release of non-vesicular antigen from infected cells. However, there is limited data to support any of these mechanisms as important in driving T cell activation in vivo. In the present study we use Rab27a-deficient mice which show diminished trafficking of mycobacterial components to exosomes as well as M. tuberculosis strains that express recombinant proteins which traffic or fail to traffic to exosomes. We observed that exosomes released during a mouse M. tuberculosis infection contribute significantly to its T cell response. These finding imply that exosomes function to promote T cell immunity during a bacterial infection and are an important source of extracellular antigen.
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Affiliation(s)
- Victoria L Smith
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Yong Cheng
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Barry R Bryant
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Jeffrey S Schorey
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana 46556, USA
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54
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Maas SLN, Breakefield XO, Weaver AM. Extracellular Vesicles: Unique Intercellular Delivery Vehicles. Trends Cell Biol 2017; 27:172-188. [PMID: 27979573 PMCID: PMC5318253 DOI: 10.1016/j.tcb.2016.11.003] [Citation(s) in RCA: 1009] [Impact Index Per Article: 126.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/03/2016] [Accepted: 11/04/2016] [Indexed: 12/21/2022]
Abstract
Extracellular vesicles (EVs) are a heterogeneous collection of membrane-bound carriers with complex cargoes including proteins, lipids, and nucleic acids. While the release of EVs was previously thought to be only a mechanism to discard nonfunctional cellular components, increasing evidence implicates EVs as key players in intercellular and even interorganismal communication. EVs confer stability and can direct their cargoes to specific cell types. EV cargoes also appear to act in a combinatorial manner to communicate directives to other cells. This review focuses on recent findings and knowledge gaps in the area of EV biogenesis, release, and uptake. In addition, we highlight examples whereby EV cargoes control basic cellular functions, including motility and polarization, immune responses, and development, and contribute to diseases such as cancer and neurodegeneration.
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Affiliation(s)
- Sybren L N Maas
- Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, MA 02114, USA; Department of Neurosurgery, Brain Center Rudolf Magnus, Institute of Neurosciences, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Xandra O Breakefield
- Department of Neurology and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, MA 02114, USA
| | - Alissa M Weaver
- Departments of Cancer Biology and Cell and Developmental Biology, Vanderbilt University School of Medicine and Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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55
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Kudo M, Kobayashi-Nakamura K, Tsuji-Naito K. Bifunctional effects of O-methylated flavones from Scutellaria baicalensis Georgi on melanocytes: Inhibition of melanin production and intracellular melanosome transport. PLoS One 2017; 12:e0171513. [PMID: 28182699 PMCID: PMC5300169 DOI: 10.1371/journal.pone.0171513] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/20/2017] [Indexed: 02/07/2023] Open
Abstract
The growing interest in skin lightening has recently renewed attention on the esthetic applications of Chinese herbal medicine. Although Scutellaria baicalensis Georgi is used for antipyretic and antiinflammatory purposes, its whitening effect remains unclear. This study reports three major findings: (1) S. baicalensis has a potent inhibitory effect on melanogenesis; (2) wogonin and its glycoside are the active components of S. baicalensis; and (3) O-methylated flavones from S. baicalensis, such as wogonin, inhibit intracellular melanosome transport. Using a melanin quantification assay, we showed that S. baicalensis potently inhibits melanogenesis in B16F10 cells. Componential analyses revealed that the main components of S. baicalensis are baicalin, wogonoside, baicalein, wogonin, and oroxylin A. Among these five flavones, wogonin and wogonoside consistently inhibited melanogenesis in both B16F10 melanoma cells and primary melanocytes. Wogonin exhibited the strongest inhibition of melanin production and markedly lightened the color of skin equivalents. We identified microphthalmia-associated transcription factor and tyrosinase-related proteins as potential targets of wogonin- and wogonoside-induced melanogenesis suppression. In culture, we found that the melanosomes in wogonin-treated B16F10 cells were localized to the perinuclear region. Immunoblotting analyses revealed that wogonin significantly reduced in melanophilin protein, which is required for actin-based melanosome transport. Other actin-based melanosome transport-related molecules, i.e., Rab27A and myosin Va, were not affected by wogonin. Cotreatment with MG132 blocked the wogonin-induced decrease in melanophilin, suggesting that wogonin promotes the proteolytic degradation of melanophilin via the calpain/proteasomal pathway. We determined that the structural specificities of the mono-O-methyl group in the flavone A-ring and the aglycone form were responsible for reducing melanosome transport. Furthermore, wogonin and two wogonin analogs, mono-O-methyl flavones, strongly suppressed melanosome transport. Our findings suggest the applicability of S. baicalensis in the esthetic field. Thus, we propose a novel pharmacologic approach for the treatment of hyperpigmentation.
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Affiliation(s)
- Michiko Kudo
- Fundamental Research Laboratory, Fundamental Research Department, DHC Corporation, Chiba, Japan
| | | | - Kentaro Tsuji-Naito
- Fundamental Research Laboratory, Fundamental Research Department, DHC Corporation, Chiba, Japan
- * E-mail:
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56
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Cheeseman LP, Boulanger J, Bond LM, Schuh M. Two pathways regulate cortical granule translocation to prevent polyspermy in mouse oocytes. Nat Commun 2016; 7:13726. [PMID: 27991490 PMCID: PMC5187413 DOI: 10.1038/ncomms13726] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 10/27/2016] [Indexed: 12/20/2022] Open
Abstract
An egg must be fertilized by a single sperm only. To prevent polyspermy, the zona pellucida, a structure that surrounds mammalian eggs, becomes impermeable upon fertilization, preventing the entry of further sperm. The structural changes in the zona upon fertilization are driven by the exocytosis of cortical granules. These translocate from the oocyte's centre to the plasma membrane during meiosis. However, very little is known about the mechanism of cortical granule translocation. Here we investigate cortical granule transport and dynamics in live mammalian oocytes by using Rab27a as a marker. We show that two separate mechanisms drive their transport: myosin Va-dependent movement along actin filaments, and an unexpected vesicle hitchhiking mechanism by which cortical granules bind to Rab11a vesicles powered by myosin Vb. Inhibiting cortical granule translocation severely impaired the block to sperm entry, suggesting that translocation defects could contribute to miscarriages that are caused by polyspermy.
Mammalian eggs release cortical granules to avoid being fertilized by more than a single sperm as polyspermy results in nonviable embryos. Here, the authors describe the mechanism driving translocation of the granules to the cortex in the mouse egg and show this process is essential to prevent polyspermy.
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Affiliation(s)
- Liam P Cheeseman
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Jérôme Boulanger
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Lisa M Bond
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Melina Schuh
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.,Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
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57
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Matsunaga K, Taoka M, Isobe T, Izumi T. Rab2a and Rab27a cooperatively regulate the transition from granule maturation to exocytosis through the dual effector Noc2. J Cell Sci 2016; 130:541-550. [PMID: 27927751 DOI: 10.1242/jcs.195479] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/28/2016] [Indexed: 11/20/2022] Open
Abstract
Exocytosis of secretory granules entails budding from the trans-Golgi network, sorting and maturation of cargo proteins, and trafficking and fusion to the plasma membrane. Rab27a regulates the late steps in this process, such as granule recruitment to the fusion site, whereas Rab2a functions in the early steps, such as granule biogenesis and maturation. Here, we demonstrate that these two small GTPases simultaneously bind to Noc2 (also known as RPH3AL) in a GTP-dependent manner, although Rab2a binds only after Rab27a has bound. In pancreatic β-cells, the ternary Rab2a-Noc2-Rab27a complex specifically localizes on perinuclear immature granules, whereas the binary Noc2-Rab27a complex localizes on peripheral mature granules. In contrast to the wild type, Noc2 mutants defective in binding to Rab2a or Rab27a fail to promote glucose-stimulated insulin secretion. Although knockdown of any component of the ternary complex markedly inhibits insulin secretion, only knockdown of Rab2a or Noc2, and not that of Rab27a, impairs cargo processing from proinsulin to insulin. These results suggest that the dual effector, Noc2, regulates the transition from Rab2a-mediated granule biogenesis to Rab27a-mediated granule exocytosis.
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Affiliation(s)
- Kohichi Matsunaga
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Masato Taoka
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Toshiaki Isobe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Tetsuro Izumi
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan .,Research Program for Signal Transduction, Division of Endocrinology, Metabolism and Signal Research, Gunma University Initiative for Advanced Research, Gunma University, Maebashi 371-8512, Japan
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58
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Fujiwara T, Ye S, Castro-Gomes T, Winchell CG, Andrews NW, Voth DE, Varughese KI, Mackintosh SG, Feng Y, Pavlos N, Nakamura T, Manolagas SC, Zhao H. PLEKHM1/DEF8/RAB7 complex regulates lysosome positioning and bone homeostasis. JCI Insight 2016; 1:e86330. [PMID: 27777970 DOI: 10.1172/jci.insight.86330] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Mutations of the Plekhm1 gene in humans and rats cause osteopetrosis, an inherited bone disease characterized by diminished bone resorption by osteoclasts. PLEKHM1 binds to RAB7 and is critical for lysosome trafficking. However, the molecular mechanisms by which PLEKHM1 regulates lysosomal pathways remain unknown. Here, we generated germline and conditional Plekhm1-deficient mice. These mice displayed no overt abnormalities in major organs, except for an increase in trabecular bone mass. Furthermore, loss of PLEKHM1 abrogated the peripheral distribution of lysosomes and bone resorption in osteoclasts. Mechanistically, we indicated that DEF8 interacts with PLEKHM1 and promotes its binding to RAB7, whereas the binding of FAM98A and NDEL1 with PLEKHM1 connects lysosomes to microtubules. Importantly, suppression of these proteins results in lysosome positioning and bone resorption defects similar to those of Plekhm1-null osteoclasts. Thus, PLHKEM1, DEF8, FAM98A, and NDEL1 constitute a molecular complex that regulates lysosome positioning and secretion through RAB7.
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Affiliation(s)
- Toshifumi Fujiwara
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Shiqiao Ye
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Thiago Castro-Gomes
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | | | - Norma W Andrews
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | | | | | - Samuel G Mackintosh
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Yunfeng Feng
- Department of Pathology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA
| | - Nathan Pavlos
- Center for Orthopedic Research, Dentistry and Health Sciences, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Takashi Nakamura
- Department of Biochemistry & Integrative Medical Biology, School of Medicine, Keio University, Tokyo, Japan
| | - Stavros C Manolagas
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Haibo Zhao
- Center for Osteoporosis and Metabolic Bone Diseases, Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.,Department of Physiology and Biophysics, and
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59
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Johnson JL, Ramadass M, He J, Brown SJ, Zhang J, Abgaryan L, Biris N, Gavathiotis E, Rosen H, Catz SD. Identification of Neutrophil Exocytosis Inhibitors (Nexinhibs), Small Molecule Inhibitors of Neutrophil Exocytosis and Inflammation: DRUGGABILITY OF THE SMALL GTPase Rab27a. J Biol Chem 2016; 291:25965-25982. [PMID: 27702998 DOI: 10.1074/jbc.m116.741884] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 09/21/2016] [Indexed: 12/22/2022] Open
Abstract
Neutrophils constitute the first line of cellular defense in response to bacterial and fungal infections and rely on granular proteins to kill microorganisms, but uncontrolled secretion of neutrophil cargos is injurious to the host and should be closely regulated. Thus, increased plasma levels of neutrophil secretory proteins, including myeloperoxidase and elastase, are associated with tissue damage and are hallmarks of systemic inflammation. Here, we describe a novel high-throughput screening approach to identify small molecule inhibitors of the interaction between the small GTPase Rab27a and its effector JFC1, two central regulators of neutrophil exocytosis. Using this assay, we have identified small molecule inhibitors of Rab27a-JFC1 binding that were also active in cell-based neutrophil-specific exocytosis assays, demonstrating the druggability of Rab GTPases and their effectors. These compounds, named Nexinhibs (neutrophil exocytosis inhibitors), inhibit exocytosis of azurophilic granules in human neutrophils without affecting other important innate immune responses, including phagocytosis and neutrophil extracellular trap production. Furthermore, the compounds are reversible and potent inhibitors of the extracellular production of superoxide anion by preventing the up-regulation of the granule membrane-associated subunit of the NADPH oxidase at the plasma membrane. Nexinhibs also inhibit the up-regulation of activation signature molecules, including the adhesion molecules CD11b and CD66b. Importantly, by using a mouse model of endotoxin-induced systemic inflammation, we show that these inhibitors have significant activity in vivo manifested by decreased plasma levels of neutrophil secretory proteins and significantly decreased tissue infiltration by inflammatory neutrophils. Altogether, our data present the first neutrophil exocytosis-specific inhibitor with in vivo anti-inflammatory activity, supporting its potential use as an inhibitor of systemic inflammation.
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Affiliation(s)
| | | | - Jing He
- From the Departments of Molecular and Experimental Medicine and
| | - Steven J Brown
- Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037 and
| | - Jinzhong Zhang
- From the Departments of Molecular and Experimental Medicine and
| | - Lusine Abgaryan
- Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037 and
| | - Nikolaos Biris
- the Departments of Biochemistry and Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Evripidis Gavathiotis
- the Departments of Biochemistry and Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Hugh Rosen
- Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037 and
| | - Sergio D Catz
- From the Departments of Molecular and Experimental Medicine and
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60
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Wang HH, Cui Q, Zhang T, Wang ZB, Ouyang YC, Shen W, Ma JY, Schatten H, Sun QY. Rab3A, Rab27A, and Rab35 regulate different events during mouse oocyte meiotic maturation and activation. Histochem Cell Biol 2016; 145:647-57. [PMID: 26791531 DOI: 10.1007/s00418-015-1404-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/31/2015] [Indexed: 01/22/2023]
Abstract
Rab family members play important roles in membrane trafficking, cell growth, and differentiation. Almost all components of the cell endomembrane system, the nucleus, and the plasma membrane are closely related to RAB proteins. In this study, we investigated the distribution and functions of three members of the Rab family, Rab3A, Rab27A, and Rab35, in mouse oocyte meiotic maturation and activation. The three Rab family members showed different localization patterns in oocytes. Microinjection of siRNA, antibody injection, or inhibitor treatment showed that (1) Rab3A regulates peripheral spindle and cortical granule (CG) migration, polarity establishment, and asymmetric division; (2) Rab27A regulates CG exocytosis following MII-stage oocyte activation; and (3) Rab35 plays an important role in spindle organization and morphology maintenance, and thus meiotic nuclear maturation. These results show that Rab proteins play important roles in mouse oocyte meiotic maturation and activation and that different members exert different distinct functions.
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Affiliation(s)
- H H Wang
- College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China.,State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, 266109, China
| | - Q Cui
- Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, 266109, China
| | - T Zhang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, 266109, China
| | - Z B Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Y C Ouyang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - W Shen
- Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, 266109, China
| | - J Y Ma
- Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, 266109, China
| | - H Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, 65211, USA
| | - Q Y Sun
- College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China. .,State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China. .,Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, 266109, China.
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61
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Lettau M, Kabelitz D, Janssen O. Lysosome-Related Effector Vesicles in T Lymphocytes and NK Cells. Scand J Immunol 2015; 82:235-43. [DOI: 10.1111/sji.12337] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 06/23/2015] [Indexed: 12/29/2022]
Affiliation(s)
- M. Lettau
- Institute of Immunology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - D. Kabelitz
- Institute of Immunology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - O. Janssen
- Institute of Immunology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
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62
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Reichhart N, Markowski M, Ishiyama S, Wagner A, Crespo-Garcia S, Schorb T, Ramalho JS, Milenkovic VM, Föckler R, Seabra MC, Strauß O. Rab27a GTPase modulates L-type Ca2+ channel function via interaction with the II-III linker of CaV1.3 subunit. Cell Signal 2015; 27:2231-40. [PMID: 26235199 DOI: 10.1016/j.cellsig.2015.07.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/28/2015] [Indexed: 12/31/2022]
Abstract
In a variety of cells, secretory processes require the activation of both Rab27a and L-type channels of the Ca(V)1.3 subtype. In the retinal pigment epithelium (RPE), Rab27a and Ca(V)1.3 channels regulate growth-factor secretion towards its basolateral side. Analysis of murine retina sections revealed a co-localization of both Rab27a and Ca(V)1.3 at the basolateral membrane of the RPE. Heterologously expressed Ca(V)1.3/β3/α2δ1 channels showed negatively shifted voltage-dependence and decreased current density of about 70% when co-expressed with Rab27a. However, co-localization analysis using α(5)β(1) integrin as a membrane marker revealed that Rab27a co-expression reduced the surface expression of Ca(V)1.3 only about 10%. Physical binding of heterologously expressed Rab27a with Ca(V)1.3 channels was shown by co-localization in immunocytochemistry as well as co-immunoprecipitation which was abolished after deletion of a MyRIP-homologous amino acid sequence at the II-III linker of the Ca(V)1.3 subunit. Rab27a over-expression in ARPE-19 cells positively shifted the voltage dependence, decreased current density of endogenous Ca(V)1.3 channels and reduced VEGF-A secretion. We show the first evidence of a direct functional modulation of an ion channel by Rab27a suggesting a new mechanism of Rab and ion channel interaction in the control of VEGF-A secretion in the RPE.
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Affiliation(s)
- Nadine Reichhart
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - Magdalena Markowski
- Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - Shimpei Ishiyama
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Andrea Wagner
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Sergio Crespo-Garcia
- Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - Talitha Schorb
- Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany
| | - José S Ramalho
- CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, Lisbon, Portugal
| | - Vladimir M Milenkovic
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Department of Psychiatry and Psychotherapy, Molecular Neuroscience, University of Regensburg, Germany
| | - Renate Föckler
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Miguel C Seabra
- CEDOC, Faculdade de Ciências Médicas (FCM), Universidade Nova de Lisboa, Lisbon, Portugal
| | - Olaf Strauß
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany; Experimental Ophthalmology, Eye Hospital, Charité University Medicine, Campus Virchow-Clinic, Berlin, Germany.
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63
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Rab27A Is Present in Mouse Pancreatic Acinar Cells and Is Required for Digestive Enzyme Secretion. PLoS One 2015; 10:e0125596. [PMID: 25951179 PMCID: PMC4423933 DOI: 10.1371/journal.pone.0125596] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 03/16/2015] [Indexed: 01/24/2023] Open
Abstract
The small G-protein Rab27A has been shown to regulate the intracellular trafficking of secretory granules in various cell types. However, the presence, subcellular localization and functional impact of Rab27A on digestive enzyme secretion by mouse pancreatic acinar cells are poorly understood. Ashen mice, which lack the expression of Rab27A due to a spontaneous mutation, were used to investigate the function of Rab27A in pancreatic acinar cells. Isolated pancreatic acini were prepared from wild-type or ashen mouse pancreas by collagenase digestion, and CCK- or carbachol-induced amylase secretion was measured. Secretion occurring through the major-regulated secretory pathway, which is characterized by zymogen granules secretion, was visualized by Dextran-Texas Red labeling of exocytotic granules. The minor-regulated secretory pathway, which operates through the endosomal/lysosomal pathway, was characterized by luminal cell surface labeling of lysosomal associated membrane protein 1 (LAMP1). Compared to wild-type, expression of Rab27B was slightly increased in ashen mouse acini, while Rab3D and digestive enzymes (amylase, lipase, chymotrypsin and elastase) were not affected. Localization of Rab27B, Rab3D and amylase by immunofluorescence was similar in both wild-type and ashen acinar cells. The GTP-bound states of Rab27B and Rab3D in wild-type and ashen mouse acini also remained similar in amount. In contrast, acini from ashen mice showed decreased amylase release induced by CCK- or carbachol. Rab27A deficiency reduced the apical cell surface labeling of LAMP1, but did not affect that of Dextran-Texas Red incorporation into the fusion pockets at luminal surface. These results show that Rab27A is present in mouse pancreatic acinar cells and mainly regulates secretion through the minor-regulated pathway.
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Shimada-Sugawara M, Sakai E, Okamoto K, Fukuda M, Izumi T, Yoshida N, Tsukuba T. Rab27A regulates transport of cell surface receptors modulating multinucleation and lysosome-related organelles in osteoclasts. Sci Rep 2015; 5:9620. [PMID: 25882854 PMCID: PMC5381753 DOI: 10.1038/srep09620] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/10/2015] [Indexed: 11/21/2022] Open
Abstract
Rab27A regulates transport of lysosome-related organelles (LROs) and release of secretory granules in various types of cells. Here, we identified up-regulation of Rab27A during differentiation of osteoclasts (OCLs) from bone-marrow macrophages (BMMs), by DNA microarray analysis. Rab27A deficiency in OCLs, using small interfering RNA (siRNA) knockdown in RAW-D cell line or BMMs derived from ashen mice, which display genetic defects in Rab27A expression, induced multinucleated and giant cells. Upon stimulation with macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL), essential cytokines for OCL differentiation, phosphorylation levels of extracellular signal-regulated kinase (Erk), proto-oncogene tyrosine-protein kinase (Src), and p-38 were slightly enhanced in ashen BMMs than in wild-type BMMs. The cell surface level of c-fms, an M-CSF receptor, was slightly higher in ashen BMMs than in wild-type BMMs, and down-regulation of RANK, a RANKL receptor, was delayed. In addition to receptors, OCLs derived from ashen mice exhibited aberrant actin ring formation, abnormal subcellular localization of lysosome-associated membrane protein (LAMP2) and cathepsin K (CTSK), and marked reduction in resorbing activity. Thus, these findings suggest that Rab27A regulates normal transport of cell surface receptors modulating multinucleation and LROs in OCLs.
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Affiliation(s)
- Megumi Shimada-Sugawara
- 1] Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan [2] Division of Orthodontics and Dentofacial Orthopedics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
| | - Eiko Sakai
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
| | - Kuniaki Okamoto
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Tetsuro Izumi
- Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan
| | - Noriaki Yoshida
- Division of Orthodontics and Dentofacial Orthopedics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
| | - Takayuki Tsukuba
- Division of Dental Pharmacology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588, Japan
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Yamaoka M, Ishizaki T, Kimura T. Interplay between Rab27a effectors in pancreatic β-cells. World J Diabetes 2015; 6:508-516. [PMID: 25897360 PMCID: PMC4398906 DOI: 10.4239/wjd.v6.i3.508] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/24/2014] [Accepted: 02/09/2015] [Indexed: 02/05/2023] Open
Abstract
The small GTPase Rab27a is a member of the Rab family that is involved in membrane trafficking in various kinds of cells. Rab27a has GTP- and GDP-bound forms, and their interconversion regulates intracellular signaling pathways. Typically, only a GTP-bound GTPase binds its specific effectors with the resulting downstream signals controlling specific cellular functions. We previously identified novel Rab27a-interacting proteins. Surprisingly, some of these proteins interacted with GDP-bound Rab27a. The present study reviews recent progress in our understanding of the roles of Rab27a and its effectors in the secretory process. In pancreatic β-cells, GTP-bound Rab27a regulates insulin secretion at the pre-exocytotic stages via its GTP-specific effectors such as Exophilin8/Slac2-c/MyRIP and Slp4/Granuphilin. Glucose stimulation causes insulin exocytosis. Glucose stimulation also converts Rab27a from its GTP- to its GDP-bound form. GDP-bound Rab27a interacts with GDP-specific effectors and controls endocytosis of the secretory membrane. Thus, Rab27a cycling between GTP- and GDP-bound forms synchronizes with the recycling of secretory membrane to re-use the membrane and keep the β-cell volume constant.
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66
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Yatsu A, Shimada H, Ohbayashi N, Fukuda M. Rab40C is a novel Varp-binding protein that promotes proteasomal degradation of Varp in melanocytes. Biol Open 2015; 4:267-75. [PMID: 25661869 PMCID: PMC4359733 DOI: 10.1242/bio.201411114] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Varp (VPS9-ankyrin repeat protein) was originally identified as an activator of small GTPase Rab21 through its VPS9 domain, but it has subsequently been shown to function as a Rab32/38 effector through its first ANKR1 domain. Although these functions of Varp are important for melanogenesis, Varp contains a second ANKR2 domain, whose function remained completely unknown. Here we identified Rab40C, an atypical Rab containing a SOCS box that recruits a ubiquitin ligase complex, as a novel ANKR2-binding protein and investigated its involvement in melanogenic enzyme trafficking in melanocytes. The results showed that overexpression of Rab40C in melanocytes caused a dramatic reduction in melanogenic enzyme Tyrp1 signals by promoting proteasomal degradation of Varp in a SOCS-box-dependent manner and that knockdown of Rab40C in melanocytes caused an increase in the amount of Varp. Intriguingly, Rab40C knockdown also caused a dramatic reduction in Tyrp1 signals, the same as Varp overexpression did. These findings indicated that Rab40C is a previously unexpected regulator of Tyrp1 trafficking in melanocytes through controlling the proteasomal degradation of Varp.
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Affiliation(s)
- Ayaka Yatsu
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Hikaru Shimada
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Norihiko Ohbayashi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
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Abstract
Rab proteins represent the largest branch of the Ras-like small GTPase superfamily and there are 66 Rab genes in the human genome. They alternate between GTP- and GDP-bound states, which are facilitated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and function as molecular switches in regulation of intracellular membrane trafficking in all eukaryotic cells. Each Rab targets to an organelle and specify a transport step along exocytic, endocytic, and recycling pathways as well as the crosstalk between these pathways. Through interactions with multiple effectors temporally, a Rab can control membrane budding and formation of transport vesicles, vesicle movement along cytoskeleton, and membrane fusion at the target compartment. The large number of Rab proteins reflects the complexity of the intracellular transport system, which is essential for the localization and function of membrane and secretory proteins such as hormones, growth factors, and their membrane receptors. As such, Rab proteins have emerged as important regulators for signal transduction, cell growth, and differentiation. Altered Rab expression and/or activity have been implicated in diseases ranging from neurological disorders, diabetes to cancer.
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Affiliation(s)
- Guangpu Li
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, 975 NE 10 Street, BRC 417, Oklahoma City, OK, 73104, USA,
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Hemophagocytic lymphohistiocytosis (HLH): A heterogeneous spectrum of cytokine-driven immune disorders. Cytokine Growth Factor Rev 2014; 26:263-80. [PMID: 25466631 DOI: 10.1016/j.cytogfr.2014.10.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/17/2014] [Indexed: 01/02/2023]
Abstract
Hemophagocytic lymphohistiocytosis (HLH) comprises a group of life-threatening immune disorders classified into primary or secondary HLH. The former is caused by mutations in genes involved in granule-mediated cytotoxicity, the latter occurs in a context of infections, malignancies or autoimmune/autoinflammatory disorders. Both are characterized by systemic inflammation, severe cytokine storms and immune-mediated organ damage. Despite recent advances, the pathogenesis of HLH remains incompletely understood. Animal models resembling different subtypes of HLH are therefore of great value to study this disease and to uncover novel treatment strategies. In this review, all known animal models of HLH will be discussed, highlighting findings on cell types, cytokines and signaling pathways involved in disease pathogenesis and extrapolating therapeutic implications for the human situation.
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69
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Wandinger-Ness A, Zerial M. Rab proteins and the compartmentalization of the endosomal system. Cold Spring Harb Perspect Biol 2014; 6:a022616. [PMID: 25341920 DOI: 10.1101/cshperspect.a022616] [Citation(s) in RCA: 424] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Of the approximately 70 human Rab GTPases, nearly three-quarters are involved in endocytic trafficking. Significant plasticity in endosomal membrane transport pathways is closely coupled to receptor signaling and Rab GTPase-regulated scaffolds. Here we review current literature pertaining to endocytic Rab GTPase localizations, functions, and coordination with regulatory proteins and effectors. The roles of Rab GTPases in (1) compartmentalization of the endocytic pathway into early, recycling, late, and lysosomal routes; (2) coordination of individual transport steps from vesicle budding to fusion; (3) effector interactomes; and (4) integration of GTPase and signaling cascades are discussed.
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Affiliation(s)
- Angela Wandinger-Ness
- Department of Pathology MSC08 4640, University of New Mexico HSC, Albuquerque, New Mexico 87131
| | - Marino Zerial
- Max Planck Institute of Molecular and Cell Biology and Genetics, 01307 Dresden, Germany
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70
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Wandinger-Ness A, Zerial M. Rab proteins and the compartmentalization of the endosomal system. Cold Spring Harb Perspect Biol 2014; 6:a022616. [PMID: 25341920 PMCID: PMC4413231 DOI: 10.1101/cshperspect.a022616;] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Of the approximately 70 human Rab GTPases, nearly three-quarters are involved in endocytic trafficking. Significant plasticity in endosomal membrane transport pathways is closely coupled to receptor signaling and Rab GTPase-regulated scaffolds. Here we review current literature pertaining to endocytic Rab GTPase localizations, functions, and coordination with regulatory proteins and effectors. The roles of Rab GTPases in (1) compartmentalization of the endocytic pathway into early, recycling, late, and lysosomal routes; (2) coordination of individual transport steps from vesicle budding to fusion; (3) effector interactomes; and (4) integration of GTPase and signaling cascades are discussed.
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Affiliation(s)
- Angela Wandinger-Ness
- Department of Pathology MSC08 4640, University of New Mexico HSC, Albuquerque, New Mexico 87131
| | - Marino Zerial
- Max Planck Institute of Molecular and Cell Biology and Genetics, 01307 Dresden, Germany
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71
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Bultema JJ, Boyle JA, Malenke PB, Martin FE, Dell'Angelica EC, Cheney RE, Di Pietro SM. Myosin vc interacts with Rab32 and Rab38 proteins and works in the biogenesis and secretion of melanosomes. J Biol Chem 2014; 289:33513-28. [PMID: 25324551 DOI: 10.1074/jbc.m114.578948] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Class V myosins are actin-based motors with conserved functions in vesicle and organelle trafficking. Herein we report the discovery of a function for Myosin Vc in melanosome biogenesis as an effector of melanosome-associated Rab GTPases. We isolated Myosin Vc in a yeast two-hybrid screening for proteins that interact with Rab38, a Rab protein involved in the biogenesis of melanosomes and other lysosome-related organelles. Rab38 and its close homolog Rab32 bind to Myosin Vc but not to Myosin Va or Myosin Vb. Binding depends on residues in the switch II region of Rab32 and Rab38 and regions of the Myosin Vc coiled-coil tail domain. Myosin Vc also interacts with Rab7a and Rab8a but not with Rab11, Rab17, and Rab27. Although Myosin Vc is not particularly abundant on pigmented melanosomes, its knockdown in MNT-1 melanocytes caused defects in the trafficking of integral membrane proteins to melanosomes with substantially increased surface expression of Tyrp1, nearly complete loss of Tyrp2, and significant Vamp7 mislocalization. Knockdown of Myosin Vc in MNT-1 cells more than doubled the abundance of pigmented melanosomes but did not change the number of unpigmented melanosomes. Together the data demonstrate a novel role for Myosin Vc in melanosome biogenesis and secretion.
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Affiliation(s)
- Jarred J Bultema
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, the Department of Chemistry and Biochemistry, University of Colorado, Colorado Springs, Colorado Springs, Colorado 80918
| | - Judith A Boyle
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Parker B Malenke
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Faye E Martin
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Esteban C Dell'Angelica
- the Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California 90095, and
| | - Richard E Cheney
- the Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Santiago M Di Pietro
- From the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523,
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72
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Yu S, Yehia G, Wang J, Stypulkowski E, Sakamori R, Jiang P, Hernandez-Enriquez B, Tran TS, Bonder EM, Guo W, Gao N. Global ablation of the mouse Rab11a gene impairs early embryogenesis and matrix metalloproteinase secretion. J Biol Chem 2014; 289:32030-32043. [PMID: 25271168 DOI: 10.1074/jbc.m113.538223] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Rab11a has been conceived as a prominent regulatory component of the recycling endosome, which acts as a nexus in the endo- and exocytotic networks. The precise in vivo role of Rab11a in mouse embryonic development is unknown. We globally ablated Rab11a and examined the phenotypic and molecular outcomes in Rab11a(null) blastocysts and mouse embryonic fibroblasts. Using multiple trafficking assays and complementation analyses, we determined, among multiple important membrane-associated and soluble cargos, the critical contribution of Rab11a vesicular traffic to the secretion of multiple soluble MMPs. Rab11a(null) embryos were able to properly form normal blastocysts but died at peri-implantation stages. Our data suggest that Rab11a critically controls mouse blastocyst development and soluble matrix metalloproteinase secretion.
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Affiliation(s)
- Shiyan Yu
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| | - Ghassan Yehia
- Transgenic Core Facility, Rutgers New Jersey Medical School, Newark, New Jersey 07103
| | - Juanfei Wang
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Ewa Stypulkowski
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| | - Ryotaro Sakamori
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| | - Ping Jiang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724
| | | | - Tracy S Tran
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| | - Edward M Bonder
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102
| | - Wei Guo
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and
| | - Nan Gao
- Department of Biological Sciences, Rutgers University, Newark, New Jersey 07102,.
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73
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Rab proteins: the key regulators of intracellular vesicle transport. Exp Cell Res 2014; 328:1-19. [PMID: 25088255 DOI: 10.1016/j.yexcr.2014.07.027] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/06/2014] [Accepted: 07/23/2014] [Indexed: 01/01/2023]
Abstract
Vesicular/membrane trafficking essentially regulates the compartmentalization and abundance of proteins within the cells and contributes in many signalling pathways. This membrane transport in eukaryotic cells is a complex process regulated by a large and diverse array of proteins. A large group of monomeric small GTPases; the Rabs are essential components of this membrane trafficking route. Most of the Rabs are ubiquitously expressed proteins and have been implicated in vesicle formation, vesicle motility/delivery along cytoskeleton elements and docking/fusion at target membranes through the recruitment of effectors. Functional impairments of Rabs affecting transport pathways manifest different diseases. Rab functions are accompanied by cyclical activation and inactivation of GTP-bound and GDP-bound forms between the cytosol and membranes which is regulated by upstream regulators. Rab proteins are characterized by their distinct sub-cellular localization and regulate a wide variety of endocytic, transcytic and exocytic transport pathways. Mutations of Rabs affect cell growth, motility and other biological processes.
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74
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Booth AEG, Tarafder AK, Hume AN, Recchi C, Seabra MC. A role for Na+,K+-ATPase α1 in regulating Rab27a localisation on melanosomes. PLoS One 2014; 9:e102851. [PMID: 25051489 PMCID: PMC4106853 DOI: 10.1371/journal.pone.0102851] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/23/2014] [Indexed: 12/23/2022] Open
Abstract
The mechanism(s) by which Rab GTPases are specifically recruited to distinct intracellular membranes remains elusive. Here we used Rab27a localisation onto melanosomes as a model to investigate Rab targeting. We identified the α1 subunit of Na+,K+-ATPase (ATP1a1) as a novel Rab27a interacting protein in melanocytes and showed that this interaction is direct with the intracellular M4M5 loop of ATP1a1 and independent of nucleotide bound status of the Rab. Knockdown studies in melanocytes revealed that ATP1a1 plays an essential role in Rab27a-dependent melanosome transport. Specifically, expression of ATP1a1, like the Rab27a GDP/GTP exchange factor (Rab3GEP), is essential for targeting and activation of Rab27a to melanosomes. Finally, we showed that the ability of Rab27a mutants to target to melanosomes correlates with the efficiency of their interaction with ATP1a1. Altogether these studies point to a new role for ATP1a1 as a regulator of Rab27a targeting and activation.
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Affiliation(s)
- Antonia E. G. Booth
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
| | - Abul K. Tarafder
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
| | - Alistair N. Hume
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
- School of Biomedical Sciences, University of Nottingham, Medical School, Queens Medical Centre, Nottingham, United Kingdom
| | - Chiara Recchi
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
| | - Miguel C. Seabra
- Molecular Medicine, National Heart and Lung Institute, Sir Alexander Fleming Building, Imperial College London, London, United Kingdom
- CEDOC, Faculdade de Ciencias Medicas, FCM, Universidade Nova de Lisboa, Lisboa, Portugal
- * E-mail:
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75
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Tarafder AK, Bolasco G, Correia MS, Pereira FJC, Iannone L, Hume AN, Kirkpatrick N, Picardo M, Torrisi MR, Rodrigues IP, Ramalho JS, Futter CE, Barral DC, Seabra MC. Rab11b mediates melanin transfer between donor melanocytes and acceptor keratinocytes via coupled exo/endocytosis. J Invest Dermatol 2014; 134:1056-1066. [PMID: 24141907 DOI: 10.1038/jid.2013.432] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 08/30/2013] [Accepted: 09/17/2013] [Indexed: 12/30/2022]
Abstract
The transfer of melanin from melanocytes to keratinocytes is a crucial process underlying maintenance of skin pigmentation and photoprotection against UV damage. Here, we present evidence supporting coupled exocytosis of the melanin core, or melanocore, by melanocytes and subsequent endocytosis by keratinocytes as a predominant mechanism of melanin transfer. Electron microscopy analysis of human skin samples revealed three lines of evidence supporting this: (1) the presence of melanocores in the extracellular space; (2) within keratinocytes, melanin was surrounded by a single membrane; and (3) this membrane lacked the melanosomal membrane protein tyrosinase-related protein 1 (TYRP1). Moreover, co-culture of melanocytes and keratinocytes suggests that melanin exocytosis is specifically induced by keratinocytes. Furthermore, depletion of Rab11b, but not Rab27a, caused a marked decrease in both keratinocyte-stimulated melanin exocytosis and transfer to keratinocytes. Thus, we propose that the predominant mechanism of melanin transfer is keratinocyte-induced exocytosis, mediated by Rab11b through remodeling of the melanosome membrane, followed by subsequent endocytosis by keratinocytes.
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Affiliation(s)
- Abul K Tarafder
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal; Molecular Medicine, National Heart and Lung Institute, Imperial College London, London, UK
| | - Giulia Bolasco
- Molecular Medicine, National Heart and Lung Institute, Imperial College London, London, UK
| | - Maria S Correia
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Francisco J C Pereira
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Lucio Iannone
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Alistair N Hume
- Molecular Medicine, National Heart and Lung Institute, Imperial College London, London, UK
| | - Niall Kirkpatrick
- Craniofacial and Orbito-Palpebral Surgery Unit at Chelsea and Westminster Hospital, London, UK
| | - Mauro Picardo
- Laboratorio di Fisiopatologia Cutanea, Istituto Dermatologico San Gallicano, IFO, Rome, Italy
| | - Maria R Torrisi
- Laboratorio di Fisiopatologia Cutanea, Istituto Dermatologico San Gallicano, IFO, Rome, Italy; Dipartimento di Medicina Clinica e Molecolare, Azienda Ospedaliera Sant'Andrea, Università di Roma 'La Sapienza', Rome, Italy
| | - Inês P Rodrigues
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - José S Ramalho
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Clare E Futter
- Institute of Ophthalmology, University College London, London, UK
| | - Duarte C Barral
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal.
| | - Miguel C Seabra
- CEDOC, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal; Instituto Gulbenkian de Ciência, Oeiras, Portugal; Molecular Medicine, National Heart and Lung Institute, Imperial College London, London, UK.
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76
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Köhnke M, Delon C, Hastie ML, Nguyen UTT, Wu YW, Waldmann H, Goody RS, Gorman JJ, Alexandrov K. Rab GTPase prenylation hierarchy and its potential role in choroideremia disease. PLoS One 2013; 8:e81758. [PMID: 24358126 PMCID: PMC3864799 DOI: 10.1371/journal.pone.0081758] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 10/16/2013] [Indexed: 11/29/2022] Open
Abstract
Protein prenylation is a widespread post-translational modification in eukaryotes that plays a crucial role in membrane targeting and signal transduction. RabGTPases is the largest group of post-translationally C-terminally geranylgeranylated. All Rabs are processed by Rab geranylgeranyl-transferase and Rab escort protein (REP). Human genetic defects resulting in the loss one of two REP isoforms REP-1, lead to underprenylation of RabGTPases that manifests in retinal degradation and blindness known as choroideremia. In this study we used a combination of microinjections and chemo-enzymatic tagging to establish whether Rab GTPases are prenylated and delivered to their target cellular membranes with the same rate. We demonstrate that although all tested Rab GTPases display the same rate of membrane delivery, the extent of Rab prenylation in 5 hour time window vary by more than an order of magnitude. We found that Rab27a, Rab27b, Rab38 and Rab42 display the slowest prenylation in vivo and in the cell. Our work points to possible contribution of Rab38 to the emergence of choroideremia in addition to Rab27a and Rab27b.
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Affiliation(s)
- Monika Köhnke
- Department of Cell and Molecular Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Christine Delon
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, Dortmund, Germany
| | - Marcus L. Hastie
- Queensland Berghofer Medical Research Institute, PO Royal Brisbane Hospital, Herston, Queensland, Australia
| | - Uyen T. T. Nguyen
- Department of Cell and Molecular Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Yao-Wen Wu
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, Dortmund, Germany
| | - Herbert Waldmann
- Department of Chemical Biology, Max-Planck-Institute for Molecular Physiology, Dortmund, Germany
| | - Roger S. Goody
- Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, Dortmund, Germany
| | - Jeffrey J. Gorman
- Queensland Berghofer Medical Research Institute, PO Royal Brisbane Hospital, Herston, Queensland, Australia
| | - Kirill Alexandrov
- Department of Cell and Molecular Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- * E-mail:
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77
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Fontanesi L, Scotti E, Allain D, Dall'Olio S. A frameshift mutation in themelanophilingene causes the dilute coat colour in rabbit (Oryctolagus cuniculus) breeds. Anim Genet 2013; 45:248-55. [DOI: 10.1111/age.12104] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2013] [Indexed: 11/29/2022]
Affiliation(s)
- L. Fontanesi
- Division of Animal Sciences; Department of Agricultural and Food Sciences (DISTAL); University of Bologna; Viale Fanin 46 40127 Bologna Italy
- Centre for Genome Biology; University of Bologna; 40126 Bologna Italy
| | - E. Scotti
- Division of Animal Sciences; Department of Agricultural and Food Sciences (DISTAL); University of Bologna; Viale Fanin 46 40127 Bologna Italy
| | - D. Allain
- INRA; UR631; SAGA; CS52627 31326 Castanet Tolosan France
- INRA; UE 1372; GenESI; Le Magneraud; BP52 17700 Surgères France
| | - S. Dall'Olio
- Division of Animal Sciences; Department of Agricultural and Food Sciences (DISTAL); University of Bologna; Viale Fanin 46 40127 Bologna Italy
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78
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Joung JY, Lee HY, Park J, Lee JY, Chang BH, No KT, Nam KY, Hwang JS. Identification of novel rab27a/melanophilin blockers by pharmacophore-based virtual screening. Appl Biochem Biotechnol 2013; 172:1882-97. [PMID: 24293275 DOI: 10.1007/s12010-013-0615-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 10/30/2013] [Indexed: 12/31/2022]
Abstract
Melanocytes are unique cells that produce specific melanin-containing intracellular organelles called melanosomes. Melanosomes are transported from the perinuclear area of melanocytes toward the plasma membrane as they become more melanized in order to increase skin pigmentation. In this vesicular trafficking of melanosomes, Rab27a, melanophilin, and myosin Va play crucial roles in linking melanosomes to actin-based motors. To identify novel compounds to inhibit binding interface between Rab27a and melanophilin, a pharmacophore model was built based on a modeled 3D structure of the protein complex that describes the essential binding residues in the intermolecular interaction. A pharmacophore model was employed to screen a chemical library database. Finally, 25 virtual hits were selected for biological evaluations. The biological activities of 11 analogues were evaluated in a second assay. Two compounds were identified as having concentration-dependent inhibitory activity. By analyzing structure-activity relationships of derivatives of BMD-20, two hydroxyl functional groups were found to be critical for blocking the intermolecular binding between Rab27a and melanophilin.
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Affiliation(s)
- Jong Young Joung
- Bioinformatics and Molecular Design Research Center, Seoul, 120-749, Republic of Korea
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79
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Galandrini R, Capuano C, Santoni A. Activation of Lymphocyte Cytolytic Machinery: Where are We? Front Immunol 2013; 4:390. [PMID: 24312097 PMCID: PMC3832890 DOI: 10.3389/fimmu.2013.00390] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/06/2013] [Indexed: 11/13/2022] Open
Abstract
Target cell recognition by cytotoxic lymphocytes implies the simultaneous engagement and clustering of adhesion and activating receptors followed by the activation of an array of signal transduction pathways. The cytotoxic immune synapse represents the highly specialized dynamic interface formed between the cytolytic effector and its target that allows temporal and spatial integration of signals responsible for a defined sequence of processes culminating with the polarized secretion of lytic granules. Over the last decades, much attention has been given to the molecular signals coupling receptor ligation to the activation of cytolytic machinery. Moreover, in the last 10 years the discovery of genetic defects affecting cytotoxic responses greatly boosted our knowledge on the molecular effectors involved in the regulation of discrete phases of cytotoxic process at post-receptor levels. More recently, the use of super resolution and total internal reflection fluorescence imaging technologies added new insights on the dynamic reorganization of receptor and signaling molecules at lytic synapse as well as on the relationship between granule dynamics and cytoskeleton remodeling. To date we have a solid knowledge of the molecular mechanisms governing granule movement and secretion, being not yet fully unraveled the machinery that couples early receptor signaling to the late stage of synapse remodeling and granule dynamics. Here we highlight recent advances in our understanding of the molecular mechanisms acting in the activation of cytolytic machinery, also discussing similarities and differences between Natural killer cells and cytotoxic CD8+ T cells.
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Affiliation(s)
- Ricciarda Galandrini
- Department of Experimental Medicine, Istituto Pasteur-Fondazione Cenci-Bolognetti, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University , Rome , Italy
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80
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Kim JD, Willetts L, Ochkur S, Srivastava N, Hamburg R, Shayeganpour A, Seabra MC, Lee JJ, Moqbel R, Lacy P. An essential role for Rab27a GTPase in eosinophil exocytosis. J Leukoc Biol 2013; 94:1265-74. [PMID: 23986549 DOI: 10.1189/jlb.0812431] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Eosinophil degranulation has been implicated in inflammatory processes associated with allergic asthma. Rab27a, a Rab-related GTPase, is a regulatory intracellular signaling molecule expressed in human eosinophils. We postulated that Rab27a regulates eosinophil degranulation. We investigated the role of Rab27a in eosinophil degranulation within the context of airway inflammation. Rab27a expression and localization in eosinophils were investigated by using subcellular fractionation combined with Western blot analysis, and the results were confirmed by immunofluorescence analysis of Rab27a and the granule membrane marker CD63. To determine the function of eosinophil Rab27a, we used Ashen mice, a strain of Rab27a-deficient animals. Ashen eosinophils were tested for degranulation in response to PAF and calcium ionophore by measuring released EPX activity. Airway EPX release was also determined by intratracheal injection of eosinophils into mice lacking EPX. Rab27a immunoreactivity colocalized with eosinophil crystalloid granules, as determined by subcellular fractionation and immunofluorescence analysis. PAF induced eosinophil degranulation in correlation with redistribution of Rab27a(+) structures, some of which colocalized with CD63(+) crystalloid granules at the cell membrane. Eosinophils from mice had significantly reduced EPX release compared with normal WT eosinophils, both in vitro and in vivo. In mouse models, Ashen mice demonstrated reduced EPX release in BAL fluid. These findings suggest that Rab27a has a key role in eosinophil degranulation. Furthermore, these findings have implications for Rab27a-dependent eosinophil degranulation in airway inflammation.
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Affiliation(s)
- John Dongil Kim
- 2.559 HMRC, Department of Medicine, University of Alberta, Edmonton, AB, T6G 2S2, Canada.
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81
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Andrews TD, Whittle B, Field MA, Balakishnan B, Zhang Y, Shao Y, Cho V, Kirk M, Singh M, Xia Y, Hager J, Winslade S, Sjollema G, Beutler B, Enders A, Goodnow CC. Massively parallel sequencing of the mouse exome to accurately identify rare, induced mutations: an immediate source for thousands of new mouse models. Open Biol 2013; 2:120061. [PMID: 22724066 PMCID: PMC3376740 DOI: 10.1098/rsob.120061] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 04/16/2012] [Indexed: 01/17/2023] Open
Abstract
Accurate identification of sparse heterozygous single-nucleotide variants (SNVs) is a critical challenge for identifying the causative mutations in mouse genetic screens, human genetic diseases and cancer. When seeking to identify causal DNA variants that occur at such low rates, they are overwhelmed by false-positive calls that arise from a range of technical and biological sources. We describe a strategy using whole-exome capture, massively parallel DNA sequencing and computational analysis, which identifies with a low false-positive rate the majority of heterozygous and homozygous SNVs arising de novo with a frequency of one nucleotide substitution per megabase in progeny of N-ethyl-N-nitrosourea (ENU)-mutated C57BL/6j mice. We found that by applying a strategy of filtering raw SNV calls against known and platform-specific variants we could call true SNVs with a false-positive rate of 19.4 per cent and an estimated false-negative rate of 21.3 per cent. These error rates are small enough to enable calling a causative mutation from both homozygous and heterozygous candidate mutation lists with little or no further experimental validation. The efficacy of this approach is demonstrated by identifying the causative mutation in the Ptprc gene in a lymphocyte-deficient strain and in 11 other strains with immune disorders or obesity, without the need for meiotic mapping. Exome sequencing of first-generation mutant mice revealed hundreds of unphenotyped protein-changing mutations, 52 per cent of which are predicted to be deleterious, which now become available for breeding and experimental analysis. We show that exome sequencing data alone are sufficient to identify induced mutations. This approach transforms genetic screens in mice, establishes a general strategy for analysing rare DNA variants and opens up a large new source for experimental models of human disease.
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Affiliation(s)
- T D Andrews
- Immunogenomics Laboratory, Australian National University, GPO Box 334, Canberra City, Australian Capital Territory, 2601 , Australia.
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82
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Fukuda M. Rab27 effectors, pleiotropic regulators in secretory pathways. Traffic 2013; 14:949-63. [PMID: 23678941 DOI: 10.1111/tra.12083] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/13/2013] [Accepted: 05/16/2013] [Indexed: 12/18/2022]
Abstract
Rab27, a member of the small GTPase Rab family, is widely conserved in metazoan, and two Rab27 isoforms, Rab27A and Rab27B, are present in vertebrates. Rab27A was the first Rab protein whose dysfunction was found to cause a human hereditary disease, type 2 Griscelli syndrome, which is characterized by silvery hair and immunodeficiency. The discovery in the 21st century of three distinct types of mammalian Rab27A effectors [synaptotagmin-like protein (Slp), Slp homologue lacking C2 domains (Slac2), and Munc13-4] that specifically bind active Rab27A has greatly accelerated our understanding not only of the molecular mechanisms of Rab27A-mediated membrane traffic (e.g. melanosome transport and regulated secretion) but of the symptoms of Griscelli syndrome patients at the molecular level. Because Rab27B is widely expressed in various tissues together with Rab27A and has been found to have the ability to bind all of the Rab27A effectors that have been tested, Rab27A and Rab27B were initially thought to function redundantly by sharing common Rab27 effectors. However, recent evidence has indicated that by interacting with different Rab27 effectors Rab27A and Rab27B play different roles in special types of secretion (e.g. exosome secretion and mast cell secretion) even within the same cell type. In this review article, I describe the current state of our understanding of the functions of Rab27 effectors in secretory pathways.
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Affiliation(s)
- Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
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83
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Cirera S, Markakis MN, Christensen K, Anistoroaei R. New insights into the melanophilin (MLPH) gene controlling coat color phenotypes in American mink. Gene 2013; 527:48-54. [PMID: 23747352 DOI: 10.1016/j.gene.2013.05.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/21/2013] [Accepted: 05/23/2013] [Indexed: 10/26/2022]
Abstract
The mutation causing the Silverblue color type (pp) is one of the most used recessive mutations within American mink (Neovison vison) fur farming, since it is involved in some of the popular color types such as Violet and Saphire which originate from a combination of recessive mutations. In the present study, the genomic and mRNA sequences of the melanophilin (MLPH) gene were studied in Violet, Silverblue and wild-type (wt) mink animals. Although breeding schemes and previous literature indicates that the Violet (aammpp) phenotype is a triple recessive color type involving the same locus as the Silverblue (pp) color type, our findings indicate different genotypes at the MLPH locus. Upon comparison at genomic level, we identified two deletions of the entire intron 7 and of the 5' end of intron 8 in the sequence of the Silverblue MLPH gene. When investigating the mRNA, the Silverblue animals completely lack exon 8, which encodes 65 residues, of which 47 define the Myosin Va (MYO5A) binding domain. This may cause the incorrect anchoring of the MLPH protein to MYO5A in Silverblue animals, resulting in an improper pigmentation as seen in diluted phenotypes. Additionally, in the MLPH mRNA of wt, Violet and Silverblue phenotypes, part of intron 8 is retained resulting in a truncated MLPH protein, which is 359 residues long in wt and Violet and 284 residues long in Silverblue. Subsequently, our findings point out that the missing actin-binding domain, in neither of the 3 analyzed phenotypes affects the transport of melanosomes or the consequent final pigmentation. Moreover, the loss of the major part of the MYO5A domain in the Silverblue MLPH protein seems to be the responsible for the dilute phenotype. Based on our genomic DNA data, genetic tests for selecting Silverblue and Violet carrier animals can be performed in American mink.
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Affiliation(s)
- Susanna Cirera
- University of Copenhagen, Faculty of Health and Medical Science, Department of Veterinary Clinical and Animal Sciences, Division of Genetics, Bioinformatics and Breeding, 1870 Frederiksberg C, Denmark
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84
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Upregulation of the Rab27a-dependent trafficking and secretory mechanisms improves lysosomal transport, alleviates endoplasmic reticulum stress, and reduces lysosome overload in cystinosis. Mol Cell Biol 2013; 33:2950-62. [PMID: 23716592 DOI: 10.1128/mcb.00417-13] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cystinosis is a lysosomal storage disorder caused by the accumulation of the amino acid cystine due to genetic defects in the CTNS gene, which encodes cystinosin, the lysosomal cystine transporter. Although many cellular dysfunctions have been described in cystinosis, the mechanisms leading to these defects are not well understood. Here, we show that increased lysosomal overload induced by accumulated cystine leads to cellular abnormalities, including vesicular transport defects and increased endoplasmic reticulum (ER) stress, and that correction of lysosomal transport improves cellular function in cystinosis. We found that Rab27a was expressed in proximal tubular cells (PTCs) and partially colocalized with the lysosomal marker LAMP-1. The expression of Rab27a but not other small GTPases, including Rab3 and Rab7, was downregulated in kidneys from Ctns-/- mice and in human PTCs from cystinotic patients. Using total internal reflection fluorescence microscopy, we found that lysosomal transport is impaired in Ctns-/- cells. Ctns-/- cells showed significant ER expansion and a marked increase in the unfolded protein response-induced chaperones Grp78 and Grp94. Upregulation of the Rab27a-dependent vesicular trafficking mechanisms rescued the defective lysosomal transport phenotype and reduced ER stress in cystinotic cells. Importantly, reconstitution of lysosomal transport mediated by Rab27a led to decreased lysosomal overload, manifested as reduced cystine cellular content. Our data suggest that upregulation of the Rab27a-dependent lysosomal trafficking and secretory pathways contributes to the correction of some of the cellular defects induced by lysosomal overload in cystinosis, including ER stress.
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85
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Hou Y, Chen X, Tolmachova T, Ernst SA, Williams JA. EPI64B acts as a GTPase-activating protein for Rab27B in pancreatic acinar cells. J Biol Chem 2013; 288:19548-57. [PMID: 23671284 DOI: 10.1074/jbc.m113.472134] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The small GTPase Rab27B localizes to the zymogen granule membranes and plays an important role in regulating protein secretion by pancreatic acinar cells, as does Rab3D. A common guanine nucleotide exchange factor (GEF) for Rab3 and Rab27 has been reported; however, the GTPase-activating protein (GAP) specific for Rab27B has not been identified. In this study, the expression in mouse pancreatic acini of two candidate Tre-2/Bub2/Cdc16 (TBC) domain-containing proteins, EPI64 (TBC1D10A) and EPI64B (TBC1D10B), was first demonstrated. Their GAP activity on digestive enzyme secretion was examined by adenovirus-mediated overexpression of EPI64 and EPI64B in isolated pancreatic acini. EPI64B almost completely abolished the GTP-bound form of Rab27B, without affecting GTP-Rab3D. Overexpression of EPI64B also enhanced amylase release. This enhanced release was independent of Rab27A, but dependent on Rab27B, as shown using acini from genetically modified mice. EPI64 had a mild effect on both GTP-Rab27B and amylase release. Co-overexpression of EPI64B with Rab27B can reverse the inhibitory effect of Rab27B on amylase release. Mutations that block the GAP activity decreased the inhibitory effect of EPI64B on the GTP-bound state of Rab27B and abolished the enhancing effect of EPI64B on the amylase release. These data suggest that EPI64B can serve as a potential physiological GAP for Rab27B and thereby participate in the regulation of exocytosis in pancreatic acinar cells.
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Affiliation(s)
- Yanan Hou
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
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86
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Abstract
Intracellular membrane trafficking requires the complex interplay of several classes of trafficking proteins. Rab proteins, the largest subfamily of the Ras superfamily of small G-proteins, are central regulators of all aspects of intracellular trafficking processes including vesicle budding and uncoating, motility, tethering and fusion. In the present paper, we discuss the discovery, evolution and characterization of the Rab GTPase family. We examine their basic functional roles, their important structural features and the regulatory proteins which mediate Rab function. We speculate on outstanding issues in the field, such as the mechanisms of Rab membrane association and the co-ordinated interplay between distinct Rab proteins. Finally, we summarize the data implicating Rab proteins in an ever increasing number of diseases.
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87
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Seixas E, Barros M, Seabra MC, Barral DC. Rab and Arf proteins in genetic diseases. Traffic 2013; 14:871-85. [PMID: 23565987 DOI: 10.1111/tra.12072] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 04/03/2013] [Accepted: 04/08/2013] [Indexed: 01/29/2023]
Abstract
Rab and ADP-ribosylation factor (Arf) family proteins are master regulators of membrane trafficking and are involved in all steps of vesicular transport. These families of small guanine-nucleotide-binding (G) proteins are well suited to regulate membrane trafficking processes since their nucleotide state determines their conformation and the capacity to bind to a multitude of effectors, which mediate their functions. In recent years, several inherited diseases have been associated with mutations in genes encoding proteins belonging to these two families or in proteins that regulate their GTP-binding cycle. The genetic diseases that are caused by defects in Rabs, Arfs or their regulatory proteins are heterogeneous and display diverse symptoms. However, these diseases mainly affect two types of subcellular compartments, namely lysosome-related organelles and cilia. Also, several of these diseases affect the nervous system. Thus, the study of these diseases represents an opportunity to understand their etiology and the molecular mechanisms involved, as well as to develop novel therapeutic strategies.
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Affiliation(s)
- Elsa Seixas
- CEDOC, Faculdade de Ciências Médicas, FCM, Universidade Nova de Lisboa, 1169-056, Lisboa, Portugal
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88
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Reissmann M, Ludwig A. Pleiotropic effects of coat colour-associated mutations in humans, mice and other mammals. Semin Cell Dev Biol 2013; 24:576-86. [PMID: 23583561 DOI: 10.1016/j.semcdb.2013.03.014] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 03/27/2013] [Accepted: 03/28/2013] [Indexed: 12/20/2022]
Abstract
The characterisation of the pleiotropic effects of coat colour-associated mutations in mammals illustrates that sensory organs and nerves are particularly affected by disorders because of the shared origin of melanocytes and neurocytes in the neural crest; e.g. the eye-colour is a valuable indicator of disorders in pigment production and eye dysfunctions. Disorders related to coat colour-associated alleles also occur in the skin (melanoma), reproductive tract and immune system. Additionally, the coat colour phenotype of an individual influences its general behaviour and fitness. Mutations in the same genes often produce similar coat colours and pleiotropic effects in different species (e.g., KIT [reproductive disorders, lethality], EDNRB [megacolon] and LYST [CHS]). Whereas similar disorders and similar-looking coat colour phenotypes sometimes have a different genetic background (e.g., deafness [EDN3/EDNRB, MITF, PAX and SNAI2] and visual diseases [OCA2, RAB38, SLC24A5, SLC45A2, TRPM1 and TYR]). The human predilection for fancy phenotypes that ignore disorders and genetic defects is a major driving force for the increase of pleiotropic effects in domestic species and laboratory subjects since domestication has commenced approximately 18,000 years ago.
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Key Words
- AS
- ASIP
- ATRN
- Agouti signalling protein
- Albino
- Angelman syndrome
- Attractin (mahogany)
- BLOC
- Biogenesis of lysosomal organelles complex
- CCSD
- CHS
- CSD
- CSNB
- Canine congenital sensorineural deafness
- Chediak-Higashi syndrome
- Coat colour gene
- Congenital sensorineural deafness
- Congenital stationary night blindness
- Disorder
- EDN3
- EDNRB
- Endothelin 3
- Endothelin receptor type B
- Epistasis
- Fitness
- GS
- Griscelli syndrome (type 1 or 2)
- HPS
- HSCR
- Hermansky-Pudlak syndrome with different types
- Hirschsprung disease
- IPE
- Iris pigment epithelium
- KIT
- KIT ligand (steel factor)
- KITLG
- LFS
- LYST
- Lavender foal syndrome
- Lethal
- Leucism
- Lysosomal trafficking regulator
- MC1R
- MCOA
- MCOLN3
- MGRN1
- MITF
- MYO5A
- Mahogunin ring finger 1 (E3 ubiquitin protein ligase)
- Melanocortin 1 receptor
- Melanoma
- Microphthalmia-associated transcription factor
- Mucolipin 3 (TRPML3)
- Multiple congenital ocular anomalies
- Myosin VA (heavy chain 12, myoxin)
- OA
- OCA
- OCA2
- OLWS
- OSTM1
- Ocular albinism
- Oculocutaneous albinism II (pink-eye dilution homolog)
- Oculocutaneous albinism type 1–4
- Osteopetrosis associated transmembrane protein 1 (Grey lethal osteopetrosis)
- Overo lethal white syndrome
- PAX3
- PMEL
- PWS
- Paired box 3
- Pleiotropy
- Prader-Willi syndrome
- Premelanosome protein (Pmel17, SILV)
- RAB27A
- RAB27A member RAS oncogene family
- RAB38
- RAB38 member RAS oncogene family
- RPE
- Reproduction
- Retinal pigmented epithelium
- SLC24A5
- SLC2A9
- SLC45A2
- SNAI2
- STX17
- Snail homolog 2 (Drosophila), (SLUG), SOX10, SRY (sex determining region Y)-box 10
- Solute carrier family 2 (facilitated glucose transporter), member 9
- Solute carrier family 24, member 5
- Solute carrier family 45, member 2, MATP
- Syntaxin 17
- TRPM1
- TYR
- Tameness
- Transient receptor potential cation channel, subfamily M, member 1 (melastatin-1)
- Tyrosinase, TYRP1, Tyrosinase-related protein 1
- V-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog, tyrosine kinase receptor (c-kit)
- WS
- Waardenburg syndrome (type 1, type 2 combined with Tietz syndrome type 3 Klein-Waardenburg syndrome, type 4 Waardenburg-Shah syndrome)
- alpha-melanocyte-stimulating hormone
- αMSH
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Affiliation(s)
- Monika Reissmann
- Humboldt University Berlin, Department for Crop and Animal Sciences, Berlin, Germany.
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89
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Abstract
In vivo animal models have proven very useful to the understanding of basic biologic pathways of the immune system, a prerequisite for the development of innovate therapies. This article addresses currently available models for defined human monogenetic defects of neutrophil granulocytes, including murine, zebrafish, and larger mammalian species. Strengths and weaknesses of each system are summarized, and clinical investigators may thus be inspired to develop further lines of research to improve diagnosis and therapy by use of the appropriate animal model system.
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Affiliation(s)
- Alejandro A. Schäffer
- Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20894 USA;
| | - Christoph Klein
- Department of Pediatrics, Dr. von Hauner Children’s Hospital, Ludwig-maximilians-University, Lindwurmstraβe 4 D-80337 Munich GERMANY;
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90
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Identification of a novel SBF2 missense mutation associated with a rare case of thrombocytopenia using whole-exome sequencing. J Thromb Thrombolysis 2013; 36:501-6. [DOI: 10.1007/s11239-012-0864-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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91
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Harper MT, van den Bosch MTJ, Hers I, Poole AW. Absence of platelet phenotype in mice lacking the motor protein myosin Va. PLoS One 2013; 8:e53239. [PMID: 23349704 PMCID: PMC3548825 DOI: 10.1371/journal.pone.0053239] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 11/27/2012] [Indexed: 12/22/2022] Open
Abstract
Background The motor protein myosin Va plays an important role in the trafficking of intracellular vesicles. Mutation of the Myo5a gene causes Griscelli syndrome type 1 in humans and the dilute phenotype in mice, which are both characterised by pigment dilution and neurological defects as a result of impaired vesicle transport in melanocytes and neuroendocrine cells. The role of myosin Va in platelets is currently unknown. Rab27 has been shown to be associated with myosin Va cargo vesicles and is known to be important in platelet dense granule biogenesis and secretion, a crucial event in thrombus formation. Therefore, we hypothesised that myosin Va may regulate granule secretion or formation in platelets. Methodology/Principal Findings Platelet function was studied in vitro using a novel Myo5a gene deletion mouse model. Myo5a−/− platelets were devoid of myosin Va, as determined by immunoblotting, and exhibited normal expression of surface markers. We assessed dense granule, α-granule and lysosomal secretion, integrin αIIbβ3 activation, Ca2+ signalling, and spreading on fibrinogen in response to collagen-related peptide or the PAR4 agonist, AYPGKF in washed mouse platelets lacking myosin Va or wild-type platelets. Surprisingly, Myo5a−/− platelets showed no significant functional defects in these responses, or in the numbers of dense and α-granules expressed. Conclusion Despite the importance of myosin Va in vesicle transport in other cells, our data demonstrate this motor protein has no non-redundant role in the secretion of dense and α-granules or other functional responses in platelets.
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Affiliation(s)
- Matthew T. Harper
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | | | - Ingeborg Hers
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Alastair W. Poole
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- * E-mail:
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Shyam K Sharan KB, Sharan SK. Manipulating the Mouse Genome Using Recombineering. ADVANCES IN GENETICS 2013; 2. [PMID: 31404315 DOI: 10.4172/2169-0111.1000108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genetically engineered mouse models are indispensable for understanding the biological function of genes, understanding the genetic basis of human diseases and for preclinical testing of novel therapies. Generation of such mouse models has been possible because of our ability to manipulate the mouse genome. Recombineering is a highly efficient recombination-based method of genetic engineering that has revolutionized our ability to generate mouse models. Since recombineering technology is not dependent on the availability of restriction enzyme recognition sites, it allows us to modify the genome with great precision. It requires homology arms as short as 40 bases for recombination, which makes it relatively easy to generate targeting constructs to insert, change or delete either a single nucleotide or a DNA fragment several kb in size; insert selectable markers, reporter genes or add epitope tags to any gene of interest. In this review, we focus on the development of recombineering technology and its application in the generation of transgenic and knockout or knock-in mouse models. High throughput generation of gene targeting vectors, used to construct knockout alleles in mouse embryonic stem cells, is now feasible because of this technology. The challenge now is to use the "designer" mice to develop novel therapies to prevent, cure or effectively manage some the most debilitating human diseases.
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Affiliation(s)
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland 21702
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93
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Wei AH, Li W. Hermansky-Pudlak syndrome: pigmentary and non-pigmentary defects and their pathogenesis. Pigment Cell Melanoma Res 2012; 26:176-92. [DOI: 10.1111/pcmr.12051] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 11/16/2012] [Indexed: 10/27/2022]
Affiliation(s)
| | - Wei Li
- State Key Laboratory of Molecular Developmental Biology; Institute of Genetics & Developmental Biology; Chinese Academy of Sciences; Beijing; China
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94
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Bello-Morales R, Crespillo AJ, Fraile-Ramos A, Tabarés E, Alcina A, López-Guerrero JA. Role of the small GTPase Rab27a during herpes simplex virus infection of oligodendrocytic cells. BMC Microbiol 2012; 12:265. [PMID: 23164453 PMCID: PMC3554593 DOI: 10.1186/1471-2180-12-265] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 11/01/2012] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The morphogenesis of herpes simplex virus type 1 (HSV-1) comprises several events, of which some are not completely understood. It has been shown that HSV-1 glycoproteins accumulate in the trans-Golgi network (TGN) and in TGN-derived vesicles. It is also accepted that HSV-1 acquires its final morphology through a secondary envelopment by budding into TGN-derived vesicles coated with viral glycoproteins and tegument proteins. Nevertheless, several aspects of this process remain elusive. The small GTPase Rab27a has been implicated in regulated exocytosis, and it seems to play a key role in certain membrane trafficking events. Rab27a also seems to be required for human cytomegalovirus assembly. However, despite the involvement of various Rab GTPases in HSV-1 envelopment, there is, to date, no data reported on the role of Rab27a in HSV-1 infection. RESULTS Herein, we show that Rab27a colocalized with GHSV-UL46, a tegument-tagged green fluorescent protein-HSV-1, in the TGN. In fact, this small GTPase colocalized with viral glycoproteins gH and gD in that compartment. Functional analysis through Rab27a depletion showed a significant decrease in the number of infected cells and viral production in Rab27a-silenced cells. CONCLUSIONS Altogether, our results indicate that Rab27a plays an important role in HSV-1 infection of oligodendrocytic cells.
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Affiliation(s)
- Raquel Bello-Morales
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 5, Cantoblanco, 28049, Madrid, Spain
| | - Antonio Jesús Crespillo
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 5, Cantoblanco, 28049, Madrid, Spain
| | - Alberto Fraile-Ramos
- Universidad Complutense de Madrid, Facultad de Medicina, Ciudad Universitaria, 28040, Madrid, Spain
| | - Enrique Tabarés
- Universidad Autónoma de Madrid, Facultad de Medicina, Arzobispo Morcillo 4, 28029, Madrid, Spain
| | - Antonio Alcina
- Instituto de Parasitología y Biomedicina López Neyra, CSIC, Parque Tecnológico de Ciencias de la Salud, Avenida del Conocimiento s/n, 18100, Armilla, Granada, Spain
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95
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Monfregola J, Johnson JL, Meijler MM, Napolitano G, Catz SD. MUNC13-4 protein regulates the oxidative response and is essential for phagosomal maturation and bacterial killing in neutrophils. J Biol Chem 2012; 287:44603-18. [PMID: 23115246 DOI: 10.1074/jbc.m112.414029] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neutrophils use diverse mechanisms to kill pathogens including phagocytosis, exocytosis, generation of reactive oxygen species (ROS), and neutrophil extracellular traps. These mechanisms rely on their ability to mobilize intracellular organelles and to deliver granular cargoes to specific cellular compartments or into the extracellular milieu, but the molecular mechanisms regulating vesicular trafficking in neutrophils are not well understood. MUNC13-4 is a RAB27A effector that coordinates exocytosis in hematopoietic cells, and its deficiency is associated with the human immunodeficiency familial hemophagocytic lymphohistiocytosis type 3. In this work, we have established an essential role for MUNC13-4 in selective vesicular trafficking, phagosomal maturation, and intracellular bacterial killing in neutrophils. Using neutrophils from munc13-4 knock-out (KO) mice, we show that MUNC13-4 is necessary for the regulation of p22(phox)-expressing granule trafficking to the plasma membrane and regulates extracellular ROS production. MUNC13-4 was also essential for the regulation of intracellular ROS production induced by Pseudomonas aeruginosa despite normal trafficking of p22(phox)-expressing vesicles toward the phagosome. Importantly, in the absence of MUNC13-4, phagosomal maturation was impaired as observed by the defective delivery of azurophilic granules and multivesicular bodies to the phagosome. Significantly, this mechanism was intact in RAB27A KO neutrophils. Intracellular bacterial killing was markedly impaired in MUNC13-4 KO neutrophils. MUNC13-4-deficient cells showed a significant increase in neutrophil extracellular trap formation but were unable to compensate for the impaired bacterial killing. Altogether, these findings characterize novel functions of MUNC13-4 in the innate immune response of the neutrophil and have direct implications for the understanding of immunodeficiencies in patients with MUNC13-4 deficiency.
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Affiliation(s)
- Jlenia Monfregola
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
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96
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Chang H, Choi H, Joo KM, Kim D, Lee TR. Manassantin B inhibits melanosome transport in melanocytes by disrupting the melanophilin-myosin Va interaction. Pigment Cell Melanoma Res 2012; 25:765-72. [PMID: 22863119 DOI: 10.1111/pcmr.12002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skin hyperpigmentation disorders occur when the synthesis and/or distribution of melanin increases. The distribution of melanin in the skin is achieved by melanosome transport and transfer. The transport of melanosomes, the organelles where melanin is made, in a melanocyte precedes the transfer of the melanosomes to a keratinocyte. Therefore, hyperpigmentation can be regulated by decreasing melanosome transport. In this study, we found that an extract of Saururus chinensis Baill (ESCB) and one of its components, manassantin B, inhibited melanosome transport in Melan-a melanocytes and normal human melanocytes (NHMs). Manassantin B disturbed melanosome transport by disrupting the interaction between melanophilin and myosin Va. Manassantin B is neither a direct nor an indirect inhibitor of tyrosinase. The total melanin content was not reduced when melanosome transport was inhibited in a Melan-a melanocyte monoculture by manassantin B. Manassantin B decreased melanin content only when Melan-a melanocytes were co-cultured with SP-1 keratinocytes or stimulated by α-MSH. Therefore, we propose that specific inhibitors of melanosome transport, such as manassantin B, are potential candidate or lead compounds for the development of agents to treat undesirable hyperpigmentation of the skin.
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Affiliation(s)
- Huikyoung Chang
- R&D Center, AmorePacific Corporation, Giheung-gu, Yongin-si, Gyeonggi-do, Korea
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97
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Masliah-Planchon J, Darnige L, Bellucci S. Molecular determinants of platelet delta storage pool deficiencies: an update. Br J Haematol 2012; 160:5-11. [PMID: 23025459 DOI: 10.1111/bjh.12064] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Delta storage pool deficiency (δ-SPD) is a rare heterogeneous group of platelet disorders characterized by a reduction in the number or content of dense granules. δ-SPD causes a mild to moderate bleeding diathesis characterized mainly by mucocutaneous bleeding. Currently, no specific treatment is available and the therapeutic approach is based on prevention of excessive bleeding. However, during the last few years, important insights into the pathophysiology of δ-SPD have been achieved using mouse models and dense granule deficiency-associated congenital diseases, such as Hermansky-Pudlak syndrome and Chediak-Higashi syndrome. It thus appears that δ-SPD represents a genetically heterogeneous group of intracellular vesicle biogenesis and/or trafficking disorders. This review summarizes recent data regarding the molecular mechanisms together with clinical features of the different types of δ-SPD. Although the molecular basis of isolated inherited δ-SPD remains currently unknown, next-generation sequencing strategies should enable researchers to identify the causative genes. Identification of those genes should contribute to our understanding of the pathophysiology, represent useful tools for genetic diagnosis, and eventually lead to new specific therapeutic approaches.
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98
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Abstract
Griscelli syndrome (GS) is a rare autosomal recessive disorder associated with skin or hair hypopigmentation, hepatosplenomegaly, pancytopenia, and immunologic and central nervous system abnormalities. GS type II is caused by RAB27A mutations. We present RAB27A mutation analysis of 6 cases diagnosed as GS type II. Missense mutations (L26P and L130P) in 2 cases, deletion of 5 bases (514delCAAGC) in 2 cases, and 1 base deletion (148delA) in 2 cases were detected. This report has importance in phenotype-genotype correlation of different types of mutations including missense mutations and deletions within the RAB27A gene in GSII syndrome.
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99
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Rachel RA, Nagashima K, O'Sullivan TN, Frost LS, Stefano FP, Marigo V, Boesze-Battaglia K. Melanoregulin, product of the dsu locus, links the BLOC-pathway and OA1 in organelle biogenesis. PLoS One 2012; 7:e42446. [PMID: 22984402 PMCID: PMC3439427 DOI: 10.1371/journal.pone.0042446] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 07/05/2012] [Indexed: 12/27/2022] Open
Abstract
Humans with Hermansky-Pudlak Syndrome (HPS) or ocular albinism (OA1) display abnormal aspects of organelle biogenesis. The multigenic disorder HPS displays broad defects in biogenesis of lysosome-related organelles including melanosomes, platelet dense granules, and lysosomes. A phenotype of ocular pigmentation in OA1 is a smaller number of macromelanosomes, in contrast to HPS, where in many cases the melanosomes are smaller than normal. In these studies we define the role of the Mregdsu gene, which suppresses the coat color dilution of Myo5a, melanophilin, and Rab27a mutant mice in maintaining melanosome size and distribution. We show that the product of the Mregdsu locus, melanoregulin (MREG), interacts both with members of the HPS BLOC-2 complex and with Oa1 in regulating melanosome size. Loss of MREG function facilitates increase in the size of micromelanosomes in the choroid of the HPS BLOC-2 mutants ruby, ruby2, and cocoa, while a transgenic mouse overexpressing melanoregulin corrects the size of retinal pigment epithelium (RPE) macromelanosomes in Oa1ko/ko mice. Collectively, these results suggest that MREG levels regulate pigment incorporation into melanosomes. Immunohistochemical analysis localizes melanoregulin not to melanosomes, but to small vesicles in the cytoplasm of the RPE, consistent with a role for this protein in regulating membrane interactions during melanosome biogenesis. These results provide the first link between the BLOC pathway and Oa1 in melanosome biogenesis, thus supporting the hypothesis that intracellular G-protein coupled receptors may be involved in the biogenesis of other organelles. Furthermore these studies provide the foundation for therapeutic approaches to correct the pigment defects in the RPE of HPS and OA1.
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Affiliation(s)
- Rivka A. Rachel
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, Bethesda, Maryland, United States of America
| | - Kunio Nagashima
- Frederick National Laboratory for Cancer Research, SAIC-Frederick, Frederick, Maryland, United States of America
| | - T. Norene O'Sullivan
- National Cancer Institute-Frederick, Frederick, Maryland, United States of America
| | - Laura S. Frost
- Department of Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Frank P. Stefano
- Department of Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Live Cell Imaging Core, School of Dental Medicine University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Valeria Marigo
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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100
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Pshenichnaya I, Schouwey K, Armaro M, Larue L, Knoepfler PS, Eisenman RN, Trumpp A, Delmas V, Beermann F. Constitutive gray hair in mice induced by melanocyte-specific deletion of c-Myc. Pigment Cell Melanoma Res 2012; 25:312-25. [PMID: 22420299 DOI: 10.1111/j.1755-148x.2012.00998.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
c-Myc is involved in the control of diverse cellular processes and implicated in the maintenance of different tissues including the neural crest. Here, we report that c-Myc is particularly important for pigment cell development and homeostasis. Targeting c-Myc specifically in the melanocyte lineage using the floxed allele of c-Myc and Tyr::Cre transgenic mice results in a congenital gray hair phenotype. The gray coat color is associated with a reduced number of functional melanocytes in the hair bulb and melanocyte stem cells in the hair bulge. Importantly, the gray phenotype does not progress with time, suggesting that maintenance of the melanocyte through the hair cycle does not involve c-Myc function. In embryos, at E13.5, c-Myc-deficient melanocyte precursors are affected in proliferation in concordance with a reduction in numbers, showing that c-Myc is required for the proper melanocyte development. Interestingly, melanocytes from c-Myc-deficient mice display elevated levels of the c-Myc paralog N-Myc. Double deletion of c-Myc and N-Myc results in nearly complete loss of the residual pigmentation, indicating that N-Myc is capable of compensating for c-Myc loss of function in melanocytes.
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Affiliation(s)
- Irina Pshenichnaya
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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