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Traczyk G, Hromada-Judycka A, Świątkowska A, Wiśniewska J, Ciesielska A, Kwiatkowska K. Diacylglycerol kinase-ε is S-palmitoylated on cysteine in the cytoplasmic end of its N-terminal transmembrane fragment. J Lipid Res 2024; 65:100480. [PMID: 38008259 PMCID: PMC10759177 DOI: 10.1016/j.jlr.2023.100480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 11/17/2023] [Accepted: 11/18/2023] [Indexed: 11/28/2023] Open
Abstract
Diacylglycerol kinase-ε (DGKε) catalyzes phosphorylation of diacylglycerol to phosphatidic acid with a unique specificity toward 1-stearoyl-2-arachidonoyl-sn-glycerol, which is a backbone of phosphatidylinositol (PI). Owing to this specificity, DGKε is involved in the PI cycle maintaining the cellular level of phosphorylated PI derivatives of signaling activity and was also found crucial for lipid metabolism. DGKε dysfunction is linked with the development of atypical hemolytic uremic syndrome (aHUS) and possibly other human diseases. Despite the DGKε significance, data on its regulation by cotranslational and/or post-translational modifications are scarce. Here, we report that DGKε is S-palmitoylated at Cys38/40 (mouse/human DGKε) located in the cytoplasmic end of its N-terminal putative transmembrane fragment. The S-palmitoylation of DGKε was revealed by metabolic labeling of cells with a palmitic acid analogue followed by click chemistry and with acyl-biotin and acyl-polyethylene glycol exchange assays. The S-acyltransferases zDHHC7 (zinc finger DHHC domain containing) and zDHHC17 and the zDHHC6/16 tandem were found to catalyze DGKε S-palmitoylation, which also increased the DGKε abundance. Mouse DGKε-Myc ectopically expressed in human embryonic kidney 293 cells localized to the endoplasmic reticulum where zDHHC6/16 reside and in small amounts also to the Golgi apparatus where zDHHC7 and zDHHC17 are present. The Cys38Ala substitution upregulated, whereas hyperpalmitoylation of wild-type DGKε reduced the kinase activity, indicating an inhibitory effect of the Cys38 S-palmitoylation. In addition, the substitution of neighboring Pro31 with Ala also diminished the activity of DGKε. Taken together, our data indicate that S-palmitoylation can fine-tune DGKε activity in distinct cellular compartments, possibly by affecting the distance between the kinase and its substrate in a membrane.
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Affiliation(s)
- Gabriela Traczyk
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland
| | - Aneta Hromada-Judycka
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland
| | - Anna Świątkowska
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland
| | - Julia Wiśniewska
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland
| | - Anna Ciesielska
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland
| | - Katarzyna Kwiatkowska
- Laboratory of Molecular Membrane Biology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
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Curson JE, Luo L, Liu L, Burgess BJ, Bokil NJ, Wall AA, Brdicka T, Kapetanovic R, Stow JL, Sweet MJ. An alternative downstream translation start site in the non-TIR adaptor Scimp enables selective amplification of CpG DNA responses in mouse macrophages. Immunol Cell Biol 2022; 100:267-284. [PMID: 35201640 PMCID: PMC9544816 DOI: 10.1111/imcb.12540] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 02/17/2022] [Accepted: 02/22/2022] [Indexed: 01/01/2023]
Abstract
Toll-like receptor (TLR) signaling relies on Toll/interleukin-1 receptor homology (TIR) domain-containing adaptor proteins that recruit downstream signaling molecules to generate tailored immune responses. In addition, the palmitoylated transmembrane adaptor protein family member Scimp acts as a non-TIR-containing adaptor protein in macrophages, scaffolding the Src family kinase Lyn to enable TLR phosphorylation and proinflammatory signaling responses. Here we report the existence of a smaller, naturally occurring translational variant of Scimp (Scimp TV1), which is generated through leaky scanning and translation at a downstream methionine. Scimp TV1 also scaffolds Lyn, but in contrast to full-length Scimp, it is basally rather than lipopolysaccharide (LPS)-inducibly phosphorylated. Macrophages from mice that selectively express Scimp TV1, but not full-length Scimp, have impaired sustained LPS-inducible cytokine responses. Furthermore, in granulocyte macrophage colony-stimulating factor-derived myeloid cells that express high levels of Scimp, selective overexpression of Scimp TV1 enhances CpG DNA-inducible cytokine production. Unlike full-length Scimp that localizes to the cell surface and filopodia, Scimp TV1 accumulates in intracellular compartments, particularly the Golgi. Moreover, this variant of Scimp is not inducibly phosphorylated in response to CpG DNA, suggesting that it may act via an indirect mechanism to enhance TLR9 responses. Our findings thus reveal the use of alternative translation start sites as a previously unrecognized mechanism for diversifying TLR responses in the innate immune system.
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Affiliation(s)
- James Eb Curson
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Lin Luo
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Liping Liu
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Belinda J Burgess
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Nilesh J Bokil
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Adam A Wall
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Tomas Brdicka
- Laboratory of Leukocyte Signaling, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ronan Kapetanovic
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia.,Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jennifer L Stow
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research, and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, QLD, Australia
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3
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Li X, Shen L, Xu Z, Liu W, Li A, Xu J. Protein Palmitoylation Modification During Viral Infection and Detection Methods of Palmitoylated Proteins. Front Cell Infect Microbiol 2022; 12:821596. [PMID: 35155279 PMCID: PMC8829041 DOI: 10.3389/fcimb.2022.821596] [Citation(s) in RCA: 1] [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: 11/24/2021] [Accepted: 01/12/2022] [Indexed: 01/31/2023] Open
Abstract
Protein palmitoylation—a lipid modification in which one or more cysteine thiols on a substrate protein are modified to form a thioester with a palmitoyl group—is a significant post-translational biological process. This process regulates the trafficking, subcellular localization, and stability of different proteins in cells. Since palmitoylation participates in various biological processes, it is related to the occurrence and development of multiple diseases. It has been well evidenced that the proteins whose functions are palmitoylation-dependent or directly involved in key proteins’ palmitoylation/depalmitoylation cycle may be a potential source of novel therapeutic drugs for the related diseases. Many researchers have reported palmitoylation of proteins, which are crucial for host-virus interactions during viral infection. Quite a few explorations have focused on figuring out whether targeting the acylation of viral or host proteins might be a strategy to combat viral diseases. All these remarkable achievements in protein palmitoylation have been made to technological advances. This paper gives an overview of protein palmitoylation modification during viral infection and the methods for palmitoylated protein detection. Future challenges and potential developments are proposed.
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Affiliation(s)
- Xiaoling Li
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
| | - Lingyi Shen
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
| | - Zhao Xu
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
| | - Wei Liu
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
| | - Aihua Li
- Clinical Lab, Henan Provincial Chest Hospital, Zhengzhou, China
| | - Jun Xu
- College of Life Sciences, Henan Agricultural University, Zhengzhou, China
- *Correspondence: Jun Xu, ;
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Lucas RM, Liu L, Curson JEB, Koh YWH, Tuladhar N, Condon ND, Das Gupta K, Burgener SS, Schroder K, Ingley E, Sweet MJ, Stow JL, Luo L. SCIMP is a spatiotemporal transmembrane scaffold for Erk1/2 to direct pro-inflammatory signaling in TLR-activated macrophages. Cell Rep 2021; 36:109662. [PMID: 34496234 DOI: 10.1016/j.celrep.2021.109662] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/12/2021] [Accepted: 08/13/2021] [Indexed: 02/06/2023] Open
Abstract
Immune cells are armed with Toll-like receptors (TLRs) for sensing and responding to pathogens and other danger cues. The role of extracellular-signal-regulated kinases 1/2 (Erk1/2) in TLR signaling remains enigmatic, with both pro- and anti-inflammatory functions described. We reveal here that the immune-specific transmembrane adaptor SCIMP is a direct scaffold for Erk1/2 in TLR pathways, with high-resolution, live-cell imaging revealing that SCIMP guides the spatial and temporal recruitment of Erk2 to membrane ruffles and macropinosomes for pro-inflammatory TLR4 signaling. SCIMP-deficient mice display defects in Erk1/2 recruitment to TLR4, c-Fos activation, and pro-inflammatory cytokine production, with these effects being phenocopied by Erk1/2 signaling inhibition. Our findings thus delineate a selective role for SCIMP as a key scaffold for the membrane recruitment of Erk1/2 kinase to initiate TLR-mediated pro-inflammatory responses in macrophages.
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Affiliation(s)
- Richard M Lucas
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Liping Liu
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - James E B Curson
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Yvette W H Koh
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Neeraj Tuladhar
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kaustav Das Gupta
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sabrina S Burgener
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Evan Ingley
- Cell Signalling Group, Harry Perkins Institute of Medical Research and Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; Discipline of Medical, Molecular and Forensic Sciences, College of Science, Health, Engineering and Education, Murdoch University, Murdoch, WA 6150, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Lin Luo
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia.
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Zhang Y, Qin Z, Sun W, Chu F, Zhou F. Function of Protein S-Palmitoylation in Immunity and Immune-Related Diseases. Front Immunol 2021; 12:661202. [PMID: 34557182 PMCID: PMC8453015 DOI: 10.3389/fimmu.2021.661202] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 08/23/2021] [Indexed: 02/04/2023] Open
Abstract
Protein S-palmitoylation is a covalent and reversible lipid modification that specifically targets cysteine residues within many eukaryotic proteins. In mammalian cells, the ubiquitous palmitoyltransferases (PATs) and serine hydrolases, including acyl protein thioesterases (APTs), catalyze the addition and removal of palmitate, respectively. The attachment of palmitoyl groups alters the membrane affinity of the substrate protein changing its subcellular localization, stability, and protein-protein interactions. Forty years of research has led to the understanding of the role of protein palmitoylation in significantly regulating protein function in a variety of biological processes. Recent global profiling of immune cells has identified a large body of S-palmitoylated immunity-associated proteins. Localization of many immune molecules to the cellular membrane is required for the proper activation of innate and adaptive immune signaling. Emerging evidence has unveiled the crucial roles that palmitoylation plays to immune function, especially in partitioning immune signaling proteins to the membrane as well as to lipid rafts. More importantly, aberrant PAT activity and fluctuations in palmitoylation levels are strongly correlated with human immunologic diseases, such as sensory incompetence or over-response to pathogens. Therefore, targeting palmitoylation is a novel therapeutic approach for treating human immunologic diseases. In this review, we discuss the role that palmitoylation plays in both immunity and immunologic diseases as well as the significant potential of targeting palmitoylation in disease treatment.
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Borowicz P, Chan H, Hauge A, Spurkland A. Adaptor proteins: Flexible and dynamic modulators of immune cell signalling. Scand J Immunol 2020; 92:e12951. [DOI: 10.1111/sji.12951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/22/2020] [Accepted: 07/26/2020] [Indexed: 12/16/2022]
Affiliation(s)
- Paweł Borowicz
- Department of Molecular Medicine Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Hanna Chan
- Department of Molecular Medicine Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Anette Hauge
- Department of Molecular Medicine Institute of Basic Medical Sciences University of Oslo Oslo Norway
| | - Anne Spurkland
- Department of Molecular Medicine Institute of Basic Medical Sciences University of Oslo Oslo Norway
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Igarashi M, Honda A, Kawasaki A, Nozumi M. Neuronal Signaling Involved in Neuronal Polarization and Growth: Lipid Rafts and Phosphorylation. Front Mol Neurosci 2020; 13:150. [PMID: 32922262 PMCID: PMC7456915 DOI: 10.3389/fnmol.2020.00150] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/16/2020] [Indexed: 12/17/2022] Open
Abstract
Neuronal polarization and growth are developmental processes that occur during neuronal cell differentiation. The molecular signaling mechanisms involved in these events in in vivo mammalian brain remain unclear. Also, cellular events of the neuronal polarization process within a given neuron are thought to be constituted of many independent intracellular signal transduction pathways (the "tug-of-war" model). However, in vivo results suggest that such pathways should be cooperative with one another among a given group of neurons in a region of the brain. Lipid rafts, specific membrane domains with low fluidity, are candidates for the hotspots of such intracellular signaling. Among the signals reported to be involved in polarization, a number are thought to be present or translocated to the lipid rafts in response to extracellular signals. As part of our analysis, we discuss how such novel molecular mechanisms are combined for effective regulation of neuronal polarization and growth, focusing on the significance of the lipid rafts, including results based on recently introduced methods.
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Affiliation(s)
- Michihiro Igarashi
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
| | - Atsuko Honda
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
| | - Asami Kawasaki
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
| | - Motohiro Nozumi
- Department of Neurochemistry and Molecular Cell Biology, Niigata University School of Medicine and Graduate School of Medical/Dental Sciences, Niigata, Japan
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Mu W, Provaznik J, Hackert T, Zöller M. Tspan8-Tumor Extracellular Vesicle-Induced Endothelial Cell and Fibroblast Remodeling Relies on the Target Cell-Selective Response. Cells 2020; 9:cells9020319. [PMID: 32013145 PMCID: PMC7072212 DOI: 10.3390/cells9020319] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/17/2020] [Accepted: 01/26/2020] [Indexed: 12/12/2022] Open
Abstract
Tumor cell-derived extracellular vesicles (TEX) expressing tetraspanin Tspan8-alpha4/beta1 support angiogenesis. Tspan8-alpha6/beta4 facilitates lung premetastatic niche establishment. TEX-promoted target reprogramming is still being disputed, we explored rat endothelial cell (EC) and lung fibroblast (Fb) mRNA and miRNA profile changes after coculture with TEX. TEX were derived from non-metastatic BSp73AS (AS) or metastatic BSp73ASML (ASML) rat tumor lines transfected with Tspan8 (AS-Tspan8) or Tspan8-shRNA (ASML-Tspan8kd). mRNA was analyzed by deep sequencing and miRNA by array analysis of EC and Fb before and after coculture with TEX. EC and Fb responded more vigorously to AS-Tspan8- than AS-TEX. Though EC and Fb responses differed, both cell lines predominantly responded to membrane receptor activation with upregulation and activation of signaling molecules and transcription factors. Minor TEX-initiated changes in the miRNA profile relied, at least partly, on long noncoding RNA (lncRNA) that also affected chromosome organization and mRNA processing. These analyses uncovered three important points. TEX activate target cell autonomous programs. Responses are initiated by TEX targeting units and are target cell-specific. The strong TEX-promoted lncRNA impact reflects lncRNA shuttling and location-dependent distinct activities. These informations urge for an in depth exploration on the mode of TEX-initiated target cell-specific remodeling including, as a major factor, lncRNA.
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Affiliation(s)
- Wei Mu
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Department of General, Visceral and Transplantation Surgery, Pancreas Section, University of Heidelberg, 69120 Heidelberg, Germany
- Correspondence: (W.M.); (M.Z.); Tel.: +86-021-6384-6590 (W.M.); +49-6221-484-730 (M.Z.)
| | - Jan Provaznik
- EMBL Genomics Core Facility, 69117 Heidelberg, Germany
| | - Thilo Hackert
- Department of General, Visceral and Transplantation Surgery, Pancreas Section, University of Heidelberg, 69120 Heidelberg, Germany
| | - Margot Zöller
- Department of General, Visceral and Transplantation Surgery, Pancreas Section, University of Heidelberg, 69120 Heidelberg, Germany
- Correspondence: (W.M.); (M.Z.); Tel.: +86-021-6384-6590 (W.M.); +49-6221-484-730 (M.Z.)
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Luo L, Curson JEB, Liu L, Wall AA, Tuladhar N, Lucas RM, Sweet MJ, Stow JL. SCIMP is a universal Toll‐like receptor adaptor in macrophages. J Leukoc Biol 2019; 107:251-262. [DOI: 10.1002/jlb.2ma0819-138rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 02/06/2023] Open
Affiliation(s)
- Lin Luo
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - James E. B. Curson
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - Liping Liu
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - Adam A. Wall
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - Neeraj Tuladhar
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - Richard M. Lucas
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - Matthew J. Sweet
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
| | - Jennifer L. Stow
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research The University of Queensland Brisbane Queensland Australia
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Ernst AM, Toomre D, Bogan JS. Acylation - A New Means to Control Traffic Through the Golgi. Front Cell Dev Biol 2019; 7:109. [PMID: 31245373 PMCID: PMC6582194 DOI: 10.3389/fcell.2019.00109] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/29/2019] [Indexed: 12/22/2022] Open
Abstract
The Golgi is well known to act as center for modification and sorting of proteins for secretion and delivery to other organelles. A key sorting step occurs at the trans-Golgi network and is mediated by protein adapters. However, recent data indicate that sorting also occurs much earlier, at the cis-Golgi, and uses lipid acylation as a novel means to regulate anterograde flux. Here, we examine an emerging role of S-palmitoylation/acylation as a mechanism to regulate anterograde routing. We discuss the critical Golgi-localized DHHC S-palmitoyltransferase enzymes that orchestrate this lipid modification, as well as their diverse protein clients (e.g., MAP6, SNAP25, CSP, LAT, β-adrenergic receptors, GABA receptors, and GLUT4 glucose transporters). Critically, for integral membrane proteins, S-acylation can act as new a “self-sorting” signal to concentrate these cargoes in rims of Golgi cisternae, and to promote their rapid traffic through the Golgi or, potentially, to bypass the Golgi. We discuss this mechanism and examine its potential relevance to human physiology and disease, including diabetes and neurodegenerative diseases.
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Affiliation(s)
- Andreas M Ernst
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Derek Toomre
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jonathan S Bogan
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, United States.,Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, CT, United States
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Abstract
Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.
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Affiliation(s)
- Zhe Wang
- Department of Oncology, The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China.
| | - Margot Zöller
- Department of Oncology, The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China.
- Pancreas Section, University Hospital of Surgery, Heidelberg, Germany.
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12
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Mu W, Wang Z, Zöller M. Ping-Pong-Tumor and Host in Pancreatic Cancer Progression. Front Oncol 2019; 9:1359. [PMID: 31921628 PMCID: PMC6927459 DOI: 10.3389/fonc.2019.01359] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/18/2019] [Indexed: 12/12/2022] Open
Abstract
Metastasis is the main cause of high pancreatic cancer (PaCa) mortality and trials dampening PaCa mortality rates are not satisfying. Tumor progression is driven by the crosstalk between tumor cells, predominantly cancer-initiating cells (CIC), and surrounding cells and tissues as well as distant organs, where tumor-derived extracellular vesicles (TEX) are of major importance. A strong stroma reaction, recruitment of immunosuppressive leukocytes, perineural invasion, and early spread toward the peritoneal cavity, liver, and lung are shared with several epithelial cell-derived cancer, but are most prominent in PaCa. Here, we report on the state of knowledge on the PaCIC markers Tspan8, alpha6beta4, CD44v6, CXCR4, LRP5/6, LRG5, claudin7, EpCAM, and CD133, which all, but at different steps, are engaged in the metastatic cascade, frequently via PaCIC-TEX. This includes the contribution of PaCIC markers to TEX biogenesis, targeting, and uptake. We then discuss PaCa-selective features, where feedback loops between stromal elements and tumor cells, including distorted transcription, signal transduction, and metabolic shifts, establish vicious circles. For the latter particularly pancreatic stellate cells (PSC) are responsible, furnishing PaCa to cope with poor angiogenesis-promoted hypoxia by metabolic shifts and direct nutrient transfer via vesicles. Furthermore, nerves including Schwann cells deliver a large range of tumor cell attracting factors and Schwann cells additionally support PaCa cell survival by signaling receptor binding. PSC, tumor-associated macrophages, and components of the dysplastic stroma contribute to perineural invasion with signaling pathway activation including the cholinergic system. Last, PaCa aggressiveness is strongly assisted by the immune system. Although rich in immune cells, only immunosuppressive cells and factors are recovered in proximity to tumor cells and hamper effector immune cells entering the tumor stroma. Besides a paucity of immunostimulatory factors and receptors, immunosuppressive cytokines, myeloid-derived suppressor cells, regulatory T-cells, and M2 macrophages as well as PSC actively inhibit effector cell activation. This accounts for NK cells of the non-adaptive and cytotoxic T-cells of the adaptive immune system. We anticipate further deciphering the molecular background of these recently unraveled intermingled phenomena may turn most lethal PaCa into a curatively treatable disease.
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Affiliation(s)
- Wei Mu
- School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Wei Mu
| | - Zhe Wang
- Department of Oncology, The First Affiliated Hospital of Guangdong, Pharmaceutical University, Guangzhou, China
| | - Margot Zöller
- Department of Oncology, The First Affiliated Hospital of Guangdong, Pharmaceutical University, Guangzhou, China
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Weidle UH, Rohwedder I, Birzele F, Weiss EH, Schiller C. LST1: A multifunctional gene encoded in the MHC class III region. Immunobiology 2018; 223:699-708. [PMID: 30055863 DOI: 10.1016/j.imbio.2018.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/14/2018] [Indexed: 12/11/2022]
Abstract
The LST1 gene is located in the MHC class III cluster between the MHC class I and II regions. While most genes in this cluster have been sufficiently characterised, a definitive function and expression pattern for LST1 still remains elusive. In the present review we describe its promotor, gene organisation, splice variants and expression in human tissues, cell lines and cancer. We focus on LST1 expression in inflammation and discuss known correlations with autoimmune diseases and cancer. Current data on LST1 polymorphisms and their known associations with pathologies are also discussed in detail. We summarize the potential functions that have been described for the full-length LST1 protein including its function as a transmembrane adaptor protein with inhibitory signal transduction and its role as a membrane scaffold facilitating the formation of tunnelling nanotubes. We also discuss further potential functions by compiling all known LST1-interacting proteins. Furthermore, we address knowledge gaps and conflictive issues regarding disease association, non-hematopoietic expression and the discrepancy between RNA and protein expression data.
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Affiliation(s)
- Ulrich H Weidle
- Zentrum Seniorenstudium, Ludwig-Maximilians-Universität München, Hohenstaufenstrasse 1, 80801 München, Germany
| | - Ina Rohwedder
- Department of Biology II, Ludwig-Maximilians-Universität München, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Fabian Birzele
- Roche Pharmaceutical Research and Early Development, Pharmaceutical Sciences, Roche Innovation Center, Grenzacherstrasse 124, 4052 Basel, Switzerland
| | - Elisabeth H Weiss
- Zentrum Seniorenstudium, Ludwig-Maximilians-Universität München, Hohenstaufenstrasse 1, 80801 München, Germany; Department of Biology II, Ludwig-Maximilians-Universität München, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Christian Schiller
- Department of Biology II, Ludwig-Maximilians-Universität München, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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Curson JEB, Luo L, Sweet MJ, Stow JL. pTRAPs: Transmembrane adaptors in innate immune signaling. J Leukoc Biol 2018; 103:1011-1019. [PMID: 29601097 DOI: 10.1002/jlb.2ri1117-474r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/08/2018] [Accepted: 02/10/2018] [Indexed: 01/30/2023] Open
Abstract
Transmembrane adaptor proteins (TRAPs) are protein scaffolds and signaling regulators with established roles in signal-induced activation of lymphocytes. A subset of the TRAP family, the palmitoylated TRAPs (pTRAPs), are increasingly emerging with additional roles in innate immune cells. Targeted to lipid rafts, tetraspannin-enriched microdomains, and protein microclusters in membranes, pTRAP scaffolds exert spatiotemporal regulation by recruiting signaling kinases, particularly Src and Syk family members, as well as Csk, and other effectors. In this way, pTRAPs modulate signaling and influence resulting cell responses, including the selective output of inflammatory cytokines and other mediators. Here, we review studies revealing that different pTRAPs work together, often with overlapping or redundant roles, for positive and negative regulation of key innate immune pathways, including Fc receptor and pattern recognition receptor signaling. Recent findings show that pTRAPs can bind directly to innate immune receptors, in addition to other transmembrane binding partners. Thus, pTRAPs are important, multifunctional scaffolds in pathways that are fundamental to diverse innate immune responses.
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Affiliation(s)
- James E B Curson
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Lin Luo
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience (IMB), IMB Centre for Inflammation and Disease Research and Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
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Sobocińska J, Roszczenko-Jasińska P, Ciesielska A, Kwiatkowska K. Protein Palmitoylation and Its Role in Bacterial and Viral Infections. Front Immunol 2018; 8:2003. [PMID: 29403483 PMCID: PMC5780409 DOI: 10.3389/fimmu.2017.02003] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/26/2017] [Indexed: 12/11/2022] Open
Abstract
S-palmitoylation is a reversible, enzymatic posttranslational modification of proteins in which palmitoyl chain is attached to a cysteine residue via a thioester linkage. S-palmitoylation determines the functioning of proteins by affecting their association with membranes, compartmentalization in membrane domains, trafficking, and stability. In this review, we focus on S-palmitoylation of proteins, which are crucial for the interactions of pathogenic bacteria and viruses with the host. We discuss the role of palmitoylated proteins in the invasion of host cells by bacteria and viruses, and those involved in the host responses to the infection. We highlight recent data on protein S-palmitoylation in pathogens and their hosts obtained owing to the development of methods based on click chemistry and acyl-biotin exchange allowing proteomic analysis of protein lipidation. The role of the palmitoyl moiety present in bacterial lipopolysaccharide and lipoproteins, contributing to infectivity and affecting recognition of bacteria by innate immune receptors, is also discussed.
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Affiliation(s)
- Justyna Sobocińska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Paula Roszczenko-Jasińska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Anna Ciesielska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
| | - Katarzyna Kwiatkowska
- Laboratory of Molecular Membrane Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of the Polish Academy of Sciences, Warsaw, Poland
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Akr1 attenuates methylmercury toxicity through the palmitoylation of Meh1 as a subunit of the yeast EGO complex. Biochim Biophys Acta Gen Subj 2017; 1861:1729-1736. [DOI: 10.1016/j.bbagen.2017.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/08/2017] [Accepted: 03/14/2017] [Indexed: 02/05/2023]
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17
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Palmitoylation of Sindbis Virus TF Protein Regulates Its Plasma Membrane Localization and Subsequent Incorporation into Virions. J Virol 2017; 91:JVI.02000-16. [PMID: 27852864 DOI: 10.1128/jvi.02000-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/13/2016] [Indexed: 01/20/2023] Open
Abstract
Palmitoylation is a reversible, posttranslational modification that helps target proteins to cellular membranes. The alphavirus small membrane proteins 6K and TF have been reported to be palmitoylated and to positively regulate budding. 6K and TF are isoforms that are identical in their N termini but unique in their C termini due to a -1 ribosomal frameshift during translation. In this study, we used cysteine (Cys) mutants to test differential palmitoylation of the Sindbis virus 6K and TF proteins. We modularly mutated the five Cys residues in the identical N termini of 6K and TF, the four additional Cys residues in TF's unique C terminus, or all nine Cys residues in TF. Using these mutants, we determined that TF palmitoylation occurs primarily in the N terminus. In contrast, 6K is not palmitoylated, even on these shared residues. In the C-terminal Cys mutant, TF protein levels increase both in the cell and in the released virion compared to the wild type. In viruses with the N-terminal Cys residues mutated, TF is much less efficiently localized to the plasma membrane, and it is not incorporated into the virion. The three Cys mutants have minor defects in cell culture growth but a high incidence of abnormal particle morphologies compared to the wild-type virus as determined by transmission electron microscopy. We propose a model where the C terminus of TF modulates the palmitoylation of TF at the N terminus, and palmitoylated TF is preferentially trafficked to the plasma membrane for virus budding. IMPORTANCE Alphaviruses are a reemerging viral cause of arthritogenic disease. Recently, the small 6K and TF proteins of alphaviruses were shown to contribute to virulence in vivo Nevertheless, a clear understanding of the molecular mechanisms by which either protein acts to promote virus infection is missing. The TF protein is a component of budded virions, and optimal levels of TF correlate positively with wild-type-like particle morphology. In this study, we show that the palmitoylation of TF regulates its localization to the plasma membrane, which is the site of alphavirus budding. Mutants in which TF is not palmitoylated display drastically reduced plasma membrane localization, which effectively prevents TF from participating in budding or being incorporated into virus particles. Investigation of the regulation of TF will aid current efforts in the alphavirus field searching for approaches to mitigate alphaviral disease in humans.
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SCIMP is a transmembrane non-TIR TLR adaptor that promotes proinflammatory cytokine production from macrophages. Nat Commun 2017; 8:14133. [PMID: 28098138 PMCID: PMC5253658 DOI: 10.1038/ncomms14133] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 12/02/2016] [Indexed: 01/04/2023] Open
Abstract
Danger signals activate Toll-like receptors (TLRs), thereby initiating inflammatory responses. Canonical TLR signalling, via Toll/Interleukin-1 receptor domain (TIR)-containing adaptors and proinflammatory transcription factors such as NF-κB, occurs in many cell types; however, additional mechanisms are required for specificity of inflammatory responses in innate immune cells. Here we show that SCIMP, an immune-restricted, transmembrane adaptor protein (TRAP), promotes selective proinflammatory cytokine responses by direct modulation of TLR4. SCIMP is a non-TIR-containing adaptor, binding directly to the TLR4-TIR domain in response to lipopolysaccharide. In macrophages, SCIMP is constitutively associated with the Lyn tyrosine kinase, is required for tyrosine phosphorylation of TLR4, and facilitates TLR-inducible production of the proinflammatory cytokines IL-6 and IL-12p40. Point mutations in SCIMP abrogating TLR4 binding also prevent SCIMP-mediated cytokine production. SCIMP is, therefore, an immune-specific TLR adaptor that shapes host defence and inflammation. Toll-like receptors engage TIR domain-containing adaptors to control proinflammatory gene expression in response to pathogens and tissue damage. Here the authors show that the non-TIR domain-containing transmembrane protein SCIMP is a previously unrecognized TLR adaptor expressed by macrophages.
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19
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Hrdinka M, Sudan K, Just S, Drobek A, Stepanek O, Schlüter D, Reinhold D, Jordan BA, Gintschel P, Schraven B, Kreutz MR. Normal Development and Function of T Cells in Proline Rich 7 (Prr7) Deficient Mice. PLoS One 2016; 11:e0162863. [PMID: 27657535 PMCID: PMC5033326 DOI: 10.1371/journal.pone.0162863] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/30/2016] [Indexed: 11/18/2022] Open
Abstract
Transmembrane adaptor proteins (TRAPs) are important organisers for the transduction of immunoreceptor-mediated signals. Prr7 is a TRAP that regulates T cell receptor (TCR) signalling and potently induces cell death when overexpressed in human Jurkat T cells. Whether endogenous Prr7 has a similar functional role is currently unknown. To address this issue, we analysed the development and function of the immune system in Prr7 knockout mice. We found that loss of Prr7 partially impairs development of single positive CD4+ T cells in the thymus but has no effect on the development of other T cell subpopulations, B cells, NK cells, or NKT cells. Moreover, Prr7 does not affect the TCR signalling pathway as T cells derived from Prr7 knockout and wild-type animals and stimulated in vitro express the same levels of the activation marker CD69, and retain their ability to proliferate and activate induced cell death programs. Importantly, Prr7 knockout mice retained the capacity to mount a protective immune response when challenged with Listeria monocytogenes infection in vivo. In addition, T cell effector functions (activation, migration, and reactivation) were normal following induction of experimental autoimmune encephalomyelitis (EAE) in Prr7 knockout mice. Collectively, our work shows that loss of Prr7 does not result in a major immune system phenotype and suggests that Prr7 has a dispensable function for TCR signalling.
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Affiliation(s)
- Matous Hrdinka
- RG Neuroplasticity, Leibniz-Institute for Neurobiology, Magdeburg, Germany
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Magdeburg, Germany
- * E-mail: (MH); (BS); (MRK)
| | - Kritika Sudan
- RG Neuroplasticity, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Sissy Just
- Institute of Medical Microbiology, Otto-von-Guericke University, Germany
| | - Ales Drobek
- Group of Adaptive Immunity, Institute of Molecular Genetics, CAS, Prague, Czech Republic
| | - Ondrej Stepanek
- Group of Adaptive Immunity, Institute of Molecular Genetics, CAS, Prague, Czech Republic
| | - Dirk Schlüter
- Institute of Medical Microbiology, Otto-von-Guericke University, Germany
- Organ-Specific Immune Regulation, Helmholtz-Center of Infection Research (HZI). Braunschweig, Germany
| | - Dirk Reinhold
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Magdeburg, Germany
| | - Bryen A. Jordan
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Patricia Gintschel
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Magdeburg, Germany
| | - Burkhart Schraven
- Institute of Molecular and Clinical Immunology, Otto-von-Guericke University, Magdeburg, Germany
- Department of Immune Control, Helmholtz-Center of Infection Research (HZI). Braunschweig, Germany
- * E-mail: (MH); (BS); (MRK)
| | - Michael R. Kreutz
- RG Neuroplasticity, Leibniz-Institute for Neurobiology, Magdeburg, Germany
- Leibniz Group 'Dendritic Organelles and Synaptic Function', University Medical Center Hamburg-Eppendorf, Center for Molecular Neurobiology, Hamburg, Germany
- * E-mail: (MH); (BS); (MRK)
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20
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Heiler S, Wang Z, Zöller M. Pancreatic cancer stem cell markers and exosomes - the incentive push. World J Gastroenterol 2016; 22:5971-6007. [PMID: 27468191 PMCID: PMC4948278 DOI: 10.3748/wjg.v22.i26.5971] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 06/03/2016] [Accepted: 06/28/2016] [Indexed: 02/06/2023] Open
Abstract
Pancreatic cancer (PaCa) has the highest death rate and incidence is increasing. Poor prognosis is due to late diagnosis and early metastatic spread, which is ascribed to a minor population of so called cancer stem cells (CSC) within the mass of the primary tumor. CSC are defined by biological features, which they share with adult stem cells like longevity, rare cell division, the capacity for self renewal, differentiation, drug resistance and the requirement for a niche. CSC can also be identified by sets of markers, which for pancreatic CSC (Pa-CSC) include CD44v6, c-Met, Tspan8, alpha6beta4, CXCR4, CD133, EpCAM and claudin7. The functional relevance of CSC markers is still disputed. We hypothesize that Pa-CSC markers play a decisive role in tumor progression. This is fostered by the location in glycolipid-enriched membrane domains, which function as signaling platform and support connectivity of the individual Pa-CSC markers. Outside-in signaling supports apoptosis resistance, stem cell gene expression and tumor suppressor gene repression as well as miRNA transcription and silencing. Pa-CSC markers also contribute to motility and invasiveness. By ligand binding host cells are triggered towards creating a milieu supporting Pa-CSC maintenance. Furthermore, CSC markers contribute to the generation, loading and delivery of exosomes, whereby CSC gain the capacity for a cell-cell contact independent crosstalk with the host and neighboring non-CSC. This allows Pa-CSC exosomes (TEX) to reprogram neighboring non-CSC towards epithelial mesenchymal transition and to stimulate host cells towards preparing a niche for metastasizing tumor cells. Finally, TEX communicate with the matrix to support tumor cell motility, invasion and homing. We will discuss the possibility that CSC markers are the initial trigger for these processes and what is the special contribution of CSC-TEX.
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21
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Kralova J, Fabisik M, Pokorna J, Skopcova T, Malissen B, Brdicka T. The Transmembrane Adaptor Protein SCIMP Facilitates Sustained Dectin-1 Signaling in Dendritic Cells. J Biol Chem 2016; 291:16530-40. [PMID: 27288407 DOI: 10.1074/jbc.m116.717157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Indexed: 11/06/2022] Open
Abstract
Transmembrane adaptor proteins are molecules specialized in recruiting cytoplasmic proteins to the proximity of the cell membrane as part of the signal transduction process. A member of this family, SLP65/SLP76, Csk-interacting membrane protein (SCIMP), recruits a complex of SLP65/SLP76 and Grb2 adaptor proteins, known to be involved in the activation of PLCγ1/2, Ras, and other pathways. SCIMP expression is restricted to antigen-presenting cells. In a previous cell line-based study, it was shown that, in B cells, SCIMP contributes to the reverse signaling in the immunological synapse, downstream of MHCII glycoproteins. There it mainly facilitates the activation of ERK MAP kinases. However, its importance for MHCII glycoprotein-dependent ERK signaling in primary B cells has not been analyzed. Moreover, its role in macrophages and dendritic cells has remained largely unknown. Here we present the results of our analysis of SCIMP-deficient mice. In these mice, we did not observe any defects in B cell signaling and B cell-dependent responses. On the other hand, we found that, in dendritic cells and macrophages, SCIMP expression is up-regulated after exposure to GM-CSF or the Dectin-1 agonist zymosan. Moreover, we found that SCIMP is strongly phosphorylated after Dectin-1 stimulation and that it participates in signal transduction downstream of this important pattern recognition receptor. Our analysis of SCIMP-deficient dendritic cells revealed that SCIMP specifically contributes to sustaining long-term MAP kinase signaling and cytokine production downstream of Dectin-1 because of an increased expression and sustained phosphorylation lasting at least 24 h after signal initiation.
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Affiliation(s)
| | | | - Jana Pokorna
- Molecular Immunology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic and
| | | | - Bernard Malissen
- the Centre d'Immunophénomique, PHENOMIN-CIPHE, Aix Marseille Université UM2, INSERM US012, CNRS UMS3367, 13288 Marseille, France
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22
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Keller B, Zaidman I, Yousefi OS, Hershkovitz D, Stein J, Unger S, Schachtrup K, Sigvardsson M, Kuperman AA, Shaag A, Schamel WW, Elpeleg O, Warnatz K, Stepensky P. Early onset combined immunodeficiency and autoimmunity in patients with loss-of-function mutation in LAT. J Exp Med 2016; 213:1185-99. [PMID: 27242165 PMCID: PMC4925012 DOI: 10.1084/jem.20151110] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 05/04/2016] [Indexed: 12/13/2022] Open
Abstract
Keller et al. describe for the first time human LAT deficiency, which causes severe immune dysregulation with autoimmunity, lymphoproliferation, and progressive immunodeficiency. The adapter protein linker for activation of T cells (LAT) is a critical signaling hub connecting T cell antigen receptor triggering to downstream T cell responses. In this study, we describe the first kindred with defective LAT signaling caused by a homozygous mutation in exon 5, leading to a premature stop codon deleting most of the cytoplasmic tail of LAT, including the critical tyrosine residues for signal propagation. The three patients presented from early childhood with combined immunodeficiency and severe autoimmune disease. Unlike in the mouse counterpart, reduced numbers of T cells were present in the patients. Despite the reported nonredundant role of LAT in Ca2+ mobilization, residual T cells were able to induce Ca2+ influx and nuclear factor (NF) κB signaling, whereas extracellular signal-regulated kinase (ERK) signaling was completely abolished. This is the first report of a LAT-related disease in humans, manifesting by a progressive combined immune deficiency with severe autoimmune disease.
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Affiliation(s)
- Baerbel Keller
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Irina Zaidman
- Department of Pediatric Hematology Oncology, Ruth Rappaport Children's Hospital, Rambam Health Care Campus, Haifa 3109601, Israel
| | - O Sascha Yousefi
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany Department of Molecular Immunology, Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Dov Hershkovitz
- Department of Pathology, Rambam Health Care Campus, Haifa 3109601, Israel
| | - Jerry Stein
- Department of Pediatric Hematology Oncology and Bone Marrow Transplantation Unit, Schneider Children's Medical Center of Israel, Petah-Tikva 49202, Israel
| | - Susanne Unger
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Kristina Schachtrup
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Mikael Sigvardsson
- Department of Clinical and Experimental Medicine, Experimental Hematopoiesis Unit, Faculty of Health Sciences, Linköping University, 581 85 Linköping, Sweden
| | - Amir A Kuperman
- Blood Coagulation Service and Pediatric Hematology Clinic, Galilee Medical Center, Nahariya 22100, Israel Faculty of Medicine in the Galilee, Bar-Ilan University, Safed 5290002, Israel
| | - Avraham Shaag
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
| | - Wolfgang W Schamel
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany Department of Molecular Immunology, Faculty of Biology, BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Orly Elpeleg
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
| | - Klaus Warnatz
- Center for Chronic Immunodeficiency (CCI), University Medical Center and University of Freiburg, 79106 Freiburg, Germany
| | - Polina Stepensky
- Monique and Jacques Roboh Department of Genetic Research, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel Department of Pediatric Hematology-Oncology and Bone Marrow Transplantation, Hadassah Medical Center, Hebrew University, Jerusalem 91120, Israel
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23
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Thuma F, Heiler S, Schnölzer M, Zöller M. Palmitoylated claudin7 captured in glycolipid-enriched membrane microdomains promotes metastasis via associated transmembrane and cytosolic molecules. Oncotarget 2016; 7:30659-77. [PMID: 27120791 PMCID: PMC5058708 DOI: 10.18632/oncotarget.8928] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/31/2016] [Indexed: 12/13/2022] Open
Abstract
In epithelial cells claudin7 (cld7) is a major component of tight junctions, but is also recovered from glycolipid-enriched membrane microdomains (GEM). In tumor cells, too, cld7 exists in two stages. Only GEM-located cld7, which is palmitoylated, promotes metastasis. Searching for the underlying mechanism(s) revealed the following.The metastatic capacity of the rat pancreatic adenocarcinoma cell line ASML is lost by a knockdown (kd) of cld7 and is not regained by rescuing cld7 with a mutated palmitoylation site (cld7mPalm). ASML-cld7kd and ASML-cld7mPalm cells show reduced motility and invasiveness. This is due to cld7, but not cld7mPalm associating with α6β4, ezrin, uPAR and MMP14, which jointly support motility and invasion. Palmitoylated cld7 also is engaged in drug resistance by repressing Pten, allowing activation of the antiapoptotic PI3K/Akt pathway. An association of cld7mPalm with the major Pten phosphorylating kinases does not restore apoptosis resistance as phosphorylated Pten is not guided towards GEM to compete with non-phosphorylated Pten. The pathway whereby palmitoylated cld7 supports expression of several EMT genes and nuclear translocation of EMT transcription factors remains to be unraveled. An association with Notch, reduced in ASML-cld7mPalm cells, might be the starting point. Finally, GEM-located, palmitoylated cld7 associates with several components of vesicle transport machineries engaged in exosome biogenesis.Taken together, prerequisites for cld7 acting as a cancer-initiating cell marker are GEM location and palmitoylation, which support a multitude of associations and integration into exosomes. The latter suggests palmitoylated cld7 contributing to message transfer via exosomes.
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Affiliation(s)
- Florian Thuma
- Department of Tumor Cell Biology, University Hospital of Surgery, Heidelberg, Germany
| | - Sarah Heiler
- Department of Tumor Cell Biology, University Hospital of Surgery, Heidelberg, Germany
| | - Martina Schnölzer
- Department of Functional Proteome Analysis, German Cancer Research Center, Heidelberg, Germany
| | - Margot Zöller
- Department of Tumor Cell Biology, University Hospital of Surgery, Heidelberg, Germany
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24
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Halova I, Draber P. Tetraspanins and Transmembrane Adaptor Proteins As Plasma Membrane Organizers-Mast Cell Case. Front Cell Dev Biol 2016; 4:43. [PMID: 27243007 PMCID: PMC4861716 DOI: 10.3389/fcell.2016.00043] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/25/2016] [Indexed: 12/16/2022] Open
Abstract
The plasma membrane contains diverse and specialized membrane domains, which include tetraspanin-enriched domains (TEMs) and transmembrane adaptor protein (TRAP)-enriched domains. Recent biophysical, microscopic, and functional studies indicated that TEMs and TRAP-enriched domains are involved in compartmentalization of physicochemical events of such important processes as immunoreceptor signal transduction and chemotaxis. Moreover, there is evidence of a cross-talk between TEMs and TRAP-enriched domains. In this review we discuss the presence and function of such domains and their crosstalk using mast cells as a model. The combined data based on analysis of selected mast cell-expressed tetraspanins [cluster of differentiation (CD)9, CD53, CD63, CD81, CD151)] or TRAPs [linker for activation of T cells (LAT), non-T cell activation linker (NTAL), and phosphoprotein associated with glycosphingolipid-enriched membrane microdomains (PAG)] using knockout mice or specific antibodies point to a diversity within these two families and bring evidence of the important roles of these molecules in signaling events. An example of this diversity is physical separation of two TRAPs, LAT and NTAL, which are in many aspects similar but show plasma membrane location in different microdomains in both non-activated and activated cells. Although our understanding of TEMs and TRAP-enriched domains is far from complete, pharmaceutical applications of the knowledge about these domains are under way.
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Affiliation(s)
- Ivana Halova
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Petr Draber
- Department of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic Prague, Czech Republic
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Arbulo-Echevarria MM, Muñoz-Miranda JP, Caballero-García A, Poveda-Díaz JL, Fernández-Ponce C, Durán-Ruiz MC, Miazek A, García-Cózar F, Aguado E. Non-T cell activation linker (NTAL) proteolytic cleavage as a terminator of activatory intracellular signals. J Leukoc Biol 2016; 100:351-60. [PMID: 26830332 DOI: 10.1189/jlb.2a0715-318r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 01/21/2016] [Indexed: 12/13/2022] Open
Abstract
Non-T cell activation linker is an adaptor protein that is tyrosine phosphorylated upon cross-linking of immune receptors expressed on B lymphocytes, NK cells, macrophages, basophils, or mast cells, allowing the recruitment of cytosolic mediators for downstream signaling pathways. Fas receptor acts mainly as a death receptor, and when cross-linked with Fas ligand, many proteins are proteolytically cleaved, including several signaling molecules in T and B cells. Fas receptor triggering also interferes with TCR intracellular signals, probably by means of proteolytic cleavage of several adaptor proteins. We have previously found that the adaptor linker for activation of T cells, evolutionarily related to non-T cell activation linker, is cleaved upon proapoptotic stimuli in T lymphocytes and thymocytes, in a tyrosine phosphorylation-dependent fashion. Here, we describe non-T cell activation linker proteolytic cleavage triggered in human B cells and monocytes by Fas cross-linking and staurosporine treatment. Non-T cell activation linker is cleaved, producing an N-terminal fragment of ∼22 kDa, and such cleavage is abrogated in the presence of caspase 8/granzyme B and caspase 3 inhibitors. Moreover, we have identified an aspartic acid residue at which non-T cell activation linker is cleaved, which similar to linker for activation of T cells, this aspartic acid residue is located close to tyrosine and serine residues, suggesting an interdependence of phosphorylation and proteolytic cleavage. Consistently, induction of non-T cell activation linker phosphorylation by pervanadate inhibits its cleavage. Interestingly, the truncated isoform of non-T cell activation linker, generated after cleavage, has a decreased signaling ability when compared with the full-length molecule. Altogether, our results suggest that cleavage of transmembrane adaptors constitutes a general mechanism for signal termination of immune receptors.
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Affiliation(s)
- Mikel M Arbulo-Echevarria
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Juan Pedro Muñoz-Miranda
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Andrés Caballero-García
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - José L Poveda-Díaz
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Cecilia Fernández-Ponce
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - M Carmen Durán-Ruiz
- Department of Biomedicine, Biotechnology and Public Health (Biochemistry), University of Cádiz, Cádiz, Spain
| | - Arkadiusz Miazek
- Department of Biochemistry, Pharmacology and Toxicology, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Francisco García-Cózar
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain
| | - Enrique Aguado
- Core Research Facility for Health Sciences, University of Cádiz and Puerto Real University Hospital Research Unit, Department of Biomedicine, Biotechnology and Public Health (Immunology), Cádiz, Spain,
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Leist SR, Kollmus H, Hatesuer B, Lambertz RLO, Schughart K. Lst1 deficiency has a minor impact on course and outcome of the host response to influenza A H1N1 infections in mice. Virol J 2016; 13:17. [PMID: 26817701 PMCID: PMC4729168 DOI: 10.1186/s12985-016-0471-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/19/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Previously, we performed a quantitative trait locus (QTL) mapping study in BXD recombinant inbred mice to identify host genetic factors that confer resistance to influenza A virus infection. We found Lst1 (leukocyte specific transcript 1) as one of the most promising candidate genes in the Qivr17-2 locus because it is non-functional in DBA/2 J mice. Several studies have proposed that LST1 plays a role in the immune response to inflammatory diseases in humans and has additional immune-regulatory functions. Here, we evaluated the relevance of LST1 for the host response to influenza A infection in B6-Lst1 (-/-) mutant mice. FINDINGS To investigate the role of LST1, we infected B6-Lst1 (-/-) mutant and C57BL/6 N wild-type mice with a low-virulent influenza A virus (PR8M; H1N1). Lst1 deficient mice exhibited significantly increased body weight loss at days 5 and 6 after infection and slightly increased lethality compared to infected wild-type mice. Determination of viral loads, histopathological examination and analysis of immune cell composition in bronchoalveolar lavage of infected lungs did not reveal any obvious differences between KO and wild-type mice. CONCLUSIONS The absence of Lst1 leads to a slightly more susceptible phenotype. However, deletion of Lst1 in DBA/2 J mice alone does not explain the high susceptibility of this strain to PR8M influenza infections.
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Affiliation(s)
- Sarah R Leist
- Department of Infection Genetics, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany. .,University of Veterinary Medicine Hannover, Hannover, Germany.
| | - Heike Kollmus
- Department of Infection Genetics, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany. .,University of Veterinary Medicine Hannover, Hannover, Germany.
| | - Bastian Hatesuer
- Department of Infection Genetics, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany. .,University of Veterinary Medicine Hannover, Hannover, Germany.
| | - Ruth L O Lambertz
- Department of Infection Genetics, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany. .,University of Veterinary Medicine Hannover, Hannover, Germany.
| | - Klaus Schughart
- Department of Infection Genetics, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany. .,University of Veterinary Medicine Hannover, Hannover, Germany. .,University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
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Heiler S, Mu W, Zöller M, Thuma F. The importance of claudin-7 palmitoylation on membrane subdomain localization and metastasis-promoting activities. Cell Commun Signal 2015; 13:29. [PMID: 26054340 PMCID: PMC4459675 DOI: 10.1186/s12964-015-0105-y] [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: 01/06/2015] [Accepted: 04/21/2015] [Indexed: 12/14/2022] Open
Abstract
Background Claudin-7 (cld7), a tight junction (TJ) component, is also found basolaterally and in the cytoplasm. Basolaterally located cld7 is enriched in glycolipid-enriched membrane domains (GEM), where it associates with EpCAM (EpC). The conditions driving cld7 out of TJ into GEM, which is associated with a striking change in function, were not defined. Thus, we asked whether cld7 serines or palmitoylation affect cld7 location and protein, particularly EpCAM, associations. Results HEK cells were transfected with EpCAM and wild type cld7 or cld7, where serine phopsphorylation or the palmitoylation sites (AA184, AA186) (cld7mPalm) were mutated. Exchange of individual serine phosphorylation sites did not significantly affect the GEM localization and the EpCAM association. Instead, cld7mPalm was poorly recruited into GEM. This has consequences on migration and invasiveness as palmitoylated cld7 facilitates integrin and EpCAM recruitment, associates with cytoskeletal linker proteins and cooperates with MMP14, CD147 and TACE, which support motility, matrix degradation and EpCAM cleavage. On the other hand, only cld7mPalm associates with TJ proteins. Conclusion Cld7 palmitoylation prohibits TJ integration and fosters GEM recruitment. Via associated molecules, palmitoylated cld7 supports motility and invasion. Electronic supplementary material The online version of this article (doi:10.1186/s12964-015-0105-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sarah Heiler
- Department of Tumor Cell Biology, University Hospital of Surgery, Im Neuenheimer Feld 365, 69120, Heidelberg, Germany.
| | - Wei Mu
- Department of Tumor Cell Biology, University Hospital of Surgery, Im Neuenheimer Feld 365, 69120, Heidelberg, Germany.
| | - Margot Zöller
- Department of Tumor Cell Biology, University Hospital of Surgery, Im Neuenheimer Feld 365, 69120, Heidelberg, Germany.
| | - Florian Thuma
- Department of Tumor Cell Biology, University Hospital of Surgery, Im Neuenheimer Feld 365, 69120, Heidelberg, Germany.
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Abstract
Protein S-acylation, the only fully reversible posttranslational lipid modification of proteins, is emerging as a ubiquitous mechanism to control the properties and function of a diverse array of proteins and consequently physiological processes. S-acylation results from the enzymatic addition of long-chain lipids, most typically palmitate, onto intracellular cysteine residues of soluble and transmembrane proteins via a labile thioester linkage. Addition of lipid results in increases in protein hydrophobicity that can impact on protein structure, assembly, maturation, trafficking, and function. The recent explosion in global S-acylation (palmitoyl) proteomic profiling as a result of improved biochemical tools to assay S-acylation, in conjunction with the recent identification of enzymes that control protein S-acylation and de-acylation, has opened a new vista into the physiological function of S-acylation. This review introduces key features of S-acylation and tools to interrogate this process, and highlights the eclectic array of proteins regulated including membrane receptors, ion channels and transporters, enzymes and kinases, signaling adapters and chaperones, cell adhesion, and structural proteins. We highlight recent findings correlating disruption of S-acylation to pathophysiology and disease and discuss some of the major challenges and opportunities in this rapidly expanding field.
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Affiliation(s)
- Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Strathclyde University, Glasgow, United Kingdom; and Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael J Shipston
- Strathclyde Institute of Pharmacy and Biomedical Sciences, Strathclyde University, Glasgow, United Kingdom; and Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
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Chum T, Glatzová D, Kvíčalová Z, Malínský J, Brdička T, Cebecauer M. The role of palmitoylation and transmembrane domain in sorting of transmembrane adaptor proteins. J Cell Sci 2015; 129:95-107. [DOI: 10.1242/jcs.175190] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 11/13/2015] [Indexed: 01/23/2023] Open
Abstract
Plasma membrane proteins synthesised at the endoplasmic reticulum are delivered to cell surface via sorting pathways. Hydrophobic mismatch theory based on the length of transmembrane domain (TMD) dominates discussion about determinants required for protein sorting to the plasma membrane. Transmembrane adaptor proteins (TRAP) are involved in signalling events taking place at the plasma membrane. Members of this protein family have TMD of varying length. We were interested whether palmitoylation or other motifs contribute to the effective sorting of TRAP proteins. We found that palmitoylation is essential for some but not all TRAP proteins independent of their TMD length. We also provide evidence that palmitoylation and proximal sequences can modulate sorting of artificial proteins with TMD of suboptimal length. Our observations point to a unique character of each TMD defined by its primary amino acid sequence and its impact on membrane protein localisation. We conclude that, in addition to the TMD length, secondary sorting determinants such as palmitoylation or flanking sequences have evolved for the localisation of membrane proteins.
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Affiliation(s)
- Tomáš Chum
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Dolejskova 3, Prague, Czech Republic
| | - Daniela Glatzová
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Dolejskova 3, Prague, Czech Republic
- Laboratory of Leukocyte Signaling, Institute of Molecule Genetics, Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Zuzana Kvíčalová
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Dolejskova 3, Prague, Czech Republic
| | - Jan Malínský
- Microscopy Unit, Institute of Experimental Medicine, Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Tomáš Brdička
- Laboratory of Leukocyte Signaling, Institute of Molecule Genetics, Czech Academy of Sciences, Videnska 1083, Prague, Czech Republic
| | - Marek Cebecauer
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, Dolejskova 3, Prague, Czech Republic
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Baumgart F, Schütz GJ. Detecting protein association at the T cell plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:791-801. [PMID: 25300585 DOI: 10.1016/j.bbamcr.2014.09.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 09/18/2014] [Accepted: 09/29/2014] [Indexed: 10/24/2022]
Abstract
At the moment, many models on T cell signaling rely on results obtained via rather indirect methodologies, which makes direct comparison and conclusions to the in vivo situation difficult. Recently, a variety of new imaging methods were developed, which have the potential to directly shed light onto the mysteries of protein association at the T cell membrane. While the new modalities are extremely promising, for a broad readership it may be difficult to judge the results, since technological shortcomings are not always obvious. In this review article, we put key questions on the mechanism of protein interactions in the T cell plasma membrane into relation with techniques that allow to address such questions. We discuss applicability of the techniques, their strengths and weaknesses. This article is part of a Special Issue entitled: Nanoscale membrane organisation and signalling.
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Affiliation(s)
- Florian Baumgart
- Vienna University of Technology, Institute for Applied Physics, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria
| | - Gerhard J Schütz
- Vienna University of Technology, Institute for Applied Physics, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria.
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Schiller C, Nowak C, Diakopoulos KN, Weidle UH, Weiss EH. An upstream open reading frame regulates LST1 expression during monocyte differentiation. PLoS One 2014; 9:e96245. [PMID: 24816991 PMCID: PMC4015914 DOI: 10.1371/journal.pone.0096245] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 04/04/2014] [Indexed: 01/23/2023] Open
Abstract
The regulation of gene expression depends on the interplay of multiple factors at the transcriptional and translational level. Upstream open reading frames (uORFs) play an important role as translational repressors of main ORFs and their presence or usage in transcripts can be regulated by different mechanisms. The main objective of the present study was to assess whether uORFs regulate the expression of the MHC class III gene LST1. We report that expression of LST1 is tightly regulated by alternative transcription initiation and the presence of an uORF in the 5′-UTR of transcripts. Specifically, using EGFP reporter constructs in human HeLa and HEK-293T cells and flow cytometry as well as western blot analysis we found the uORF to reduce the expression of the main ORF by roughly two-thirds. Furthermore, we were able to correlate a previously detected increase in LST1 protein expression during monocyte differentiation with an increase of transcription initiation at an alternative exon that does not contain an uORF.
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Affiliation(s)
- Christian Schiller
- Department of Biology II, Ludwig-Maximilians-Universität München, Germany
| | - Carina Nowak
- Department of Biology II, Ludwig-Maximilians-Universität München, Germany
| | | | | | - Elisabeth H. Weiss
- Department of Biology II, Ludwig-Maximilians-Universität München, Germany
- * E-mail:
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