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Griffo A, Sparn C, Lolicato F, Nolle F, Khangholi N, Seemann R, Fleury JB, Brinkmann M, Nickel W, Hähl H. Mechanics of biomimetic free-standing lipid membranes: insights into the elasticity of complex lipid compositions. RSC Adv 2024; 14:13044-13052. [PMID: 38655466 PMCID: PMC11034475 DOI: 10.1039/d4ra00738g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/08/2024] [Indexed: 04/26/2024] Open
Abstract
The creation of free-standing lipid membranes has been so far of remarkable interest to investigate processes occurring in the cell membrane since its unsupported part enables studies in which it is important to maintain cell-like physicochemical properties of the lipid bilayer, that nonetheless depend on its molecular composition. In this study, we prepare pore-spanning membranes that mimic the composition of plasma membranes and perform force spectroscopy indentation measurements to unravel mechanistic insights depending on lipid composition. We show that this approach is highly effective for studying the mechanical properties of such membranes. Furthermore, we identify a direct influence of cholesterol and sphingomyelin on the elasticity of the bilayer and adhesion between the two leaflets. Eventually, we explore the possibilities of imaging in the unsupported membrane regions. For this purpose, we investigate the adsorption and movement of a peripheral protein, the fibroblast growth factor 2, on the complex membrane.
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Affiliation(s)
- Alessandra Griffo
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
- Biophysical Engineering Group, Max Planck Institute for Medical Research Heidelberg Germany
| | - Carola Sparn
- Heidelberg University Biochemistry Center Heidelberg Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center Heidelberg Germany
| | - Friederike Nolle
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Navid Khangholi
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Ralf Seemann
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
| | - Jean-Baptiste Fleury
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Martin Brinkmann
- Department of Experimental Physics, Saarland University Saarbrücken Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center Heidelberg Germany
| | - Hendrik Hähl
- Center for Biophysics, Experimental Physics, Saarland University Saarbrücken Germany
- Department of Experimental Physics, Saarland University Saarbrücken Germany
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2
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Lolicato F, Steringer JP, Saleppico R, Beyer D, Fernandez-Sobaberas J, Unger S, Klein S, Riegerová P, Wegehingel S, Müller HM, Schmitt XJ, Kaptan S, Freund C, Hof M, Šachl R, Chlanda P, Vattulainen I, Nickel W. Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space. eLife 2024; 12:RP88579. [PMID: 38252473 PMCID: PMC10945597 DOI: 10.7554/elife.88579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024] Open
Abstract
Fibroblast growth factor 2 (FGF2) exits cells by direct translocation across the plasma membrane, a type I pathway of unconventional protein secretion. This process is initiated by phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2)-dependent formation of highly dynamic FGF2 oligomers at the inner plasma membrane leaflet, inducing the formation of lipidic membrane pores. Cell surface heparan sulfate chains linked to glypican-1 (GPC1) capture FGF2 at the outer plasma membrane leaflet, completing FGF2 membrane translocation into the extracellular space. While the basic steps of this pathway are well understood, the molecular mechanism by which FGF2 oligomerizes on membrane surfaces remains unclear. In the current study, we demonstrate the initial step of this process to depend on C95-C95 disulfide-bridge-mediated FGF2 dimerization on membrane surfaces, producing the building blocks for higher FGF2 oligomers that drive the formation of membrane pores. We find FGF2 with a C95A substitution to be defective in oligomerization, pore formation, and membrane translocation. Consistently, we demonstrate a C95A variant of FGF2 to be characterized by a severe secretion phenotype. By contrast, while also important for efficient FGF2 secretion from cells, a second cysteine residue on the molecular surface of FGF2 (C77) is not involved in FGF2 oligomerization. Rather, we find C77 to be part of the interaction interface through which FGF2 binds to the α1 subunit of the Na,K-ATPase, the landing platform for FGF2 at the inner plasma membrane leaflet. Using cross-linking mass spectrometry, atomistic molecular dynamics simulations combined with a machine learning analysis and cryo-electron tomography, we propose a mechanism by which disulfide-bridged FGF2 dimers bind with high avidity to PI(4,5)P2 on membrane surfaces. We further propose a tight coupling between FGF2 secretion and the formation of ternary signaling complexes on cell surfaces, hypothesizing that C95-C95-bridged FGF2 dimers are functioning as the molecular units triggering autocrine and paracrine FGF2 signaling.
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Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry CenterHeidelbergGermany
- Department of Physics, University of HelsinkiHelsinkiFinland
| | | | | | - Daniel Beyer
- Heidelberg University Biochemistry CenterHeidelbergGermany
| | | | | | - Steffen Klein
- Schaller Research Group, Department of Infectious Diseases-Virology, Heidelberg University HospitalHeidelbergGermany
| | - Petra Riegerová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesPragueCzech Republic
| | | | | | - Xiao J Schmitt
- Institute for Chemistry and Biochemistry, Freie Universität BerlinBerlinGermany
| | - Shreyas Kaptan
- Department of Physics, University of HelsinkiHelsinkiFinland
| | - Christian Freund
- Institute for Chemistry and Biochemistry, Freie Universität BerlinBerlinGermany
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesPragueCzech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of SciencesPragueCzech Republic
| | - Petr Chlanda
- Schaller Research Group, Department of Infectious Diseases-Virology, Heidelberg University HospitalHeidelbergGermany
| | | | - Walter Nickel
- Heidelberg University Biochemistry CenterHeidelbergGermany
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3
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Singh V, Macharová S, Riegerová P, Steringer JP, Müller HM, Lolicato F, Nickel W, Hof M, Šachl R. Determining the Functional Oligomeric State of Membrane-Associated Protein Oligomers Forming Membrane Pores on Giant Lipid Vesicles. Anal Chem 2023. [PMID: 37148264 DOI: 10.1021/acs.analchem.2c05692] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Several peripheral membrane proteins are known to form membrane pores through multimerization. In many cases, in biochemical reconstitution experiments, a complex distribution of oligomeric states has been observed that may, in part, be irrelevant to their physiological functions. This phenomenon makes it difficult to identify the functional oligomeric states of membrane lipid interacting proteins, for example, during the formation of transient membrane pores. Using fibroblast growth factor 2 (FGF2) as an example, we present a methodology applicable to giant lipid vesicles by which functional oligomers can be distinguished from nonspecifically aggregated proteins without functionality. Two distinct populations of fibroblast growth factor 2 were identified with (i) dimers to hexamers and (ii) a broad population of higher oligomeric states of membrane-associated FGF2 oligomers significantly distorting the original unfiltered histogram of all detectable oligomeric species of FGF2. The presented statistical approach is relevant for various techniques for characterizing membrane-dependent protein oligomerization.
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Affiliation(s)
- Vandana Singh
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
- Faculty of Mathematics and Physics, Charles University, Ke Karlovu, 2027/3, 121 16 Prague, Czech Republic
| | - Sabína Macharová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Petra Riegerová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Julia P Steringer
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Hans-Michael Müller
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
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Yamada K, Yoshida K. Cancer-Related Unconventional Protein Secretion: A New Role of the Endoplasmic Reticulum. DNA Cell Biol 2023; 42:225-228. [PMID: 36930842 DOI: 10.1089/dna.2023.0044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023] Open
Abstract
Unconventional protein secretion (UPS) is a crucial mechanism controlling the localization of cytosolic proteins lacking signal peptides and is implicated in inflammation, neurodegenerative diseases, and cancer. Several previous studies on immune cells have demonstrated the mechanisms of UPS. In cancer, the active secretion of several cytosolic proteins, including PKCδ and nucleolin, has been described. Moreover, we have recently demonstrated that extended synaptotagmin 1, one of the membrane proteins of the endoplasmic reticulum, plays a critical role in UPS in liver cancer cells. Importantly, UPS in cancer cells shows characteristics that are markedly different from those of the previously known UPS, and therefore, we categorize them as cancer-related UPS (CUPS). In this article, we provide an overview of UPS mechanisms and discuss the process that leads to the naming of cancer-specific UPS as CUPS.
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Affiliation(s)
- Kohji Yamada
- Department of Biochemistry, Jikei University School of Medicine, Minato-ku, Japan
| | - Kiyotsugu Yoshida
- Department of Biochemistry, Jikei University School of Medicine, Minato-ku, Japan
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Joliot A. Role of PI(4,5)P2 and Cholesterol in Unconventional Protein Secretion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:381-392. [PMID: 36988889 DOI: 10.1007/978-3-031-21547-6_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Besides its protective role in the maintenance of cell homeostasis, the plasma membrane is the site of exchanges between the cell interior and the extracellular medium. To circumvent the hydrophobic barrier formed by the acyl chains of the lipid bilayer, protein channels and transporters are key players in the exchange of small hydrophilic compounds such as ions or nutrients, but they hardly account for the transport of larger biological molecules. Exchange of proteins usually relies on membrane-fusion events between vesicles and the plasma membrane. In recent years, several alternative unconventional protein secretion (UPS) pathways across the plasma membrane have been characterised for a specific set of secreted substrates, some of them excluding any membrane-fusion events (Dimou and Nickel, Curr Biol 28:R406-R410, 2018). One of thesbe pathways, referred as type I UPS, relies on the direct translocation of the protein across the plasma membrane and not surprisingly, lipids are essential players in this process. In this chapter, we discuss the roles of phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) and cholesterol in unconventional pathways involving Engrailed-2 homeoprotein and fibroblast growth factor 2.
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Affiliation(s)
- Alain Joliot
- INSERM U932, Institut Curie Centre de Recherche, PSL Research University, Paris, France.
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6
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Lolicato F, Saleppico R, Griffo A, Meyer A, Scollo F, Pokrandt B, Müller HM, Ewers H, Hähl H, Fleury JB, Seemann R, Hof M, Brügger B, Jacobs K, Vattulainen I, Nickel W. Cholesterol promotes clustering of PI(4,5)P2 driving unconventional secretion of FGF2. J Biophys Biochem Cytol 2022; 221:213511. [PMID: 36173379 PMCID: PMC9526255 DOI: 10.1083/jcb.202106123] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/22/2022] [Accepted: 08/30/2022] [Indexed: 11/22/2022] Open
Abstract
FGF2 is a cell survival factor involved in tumor-induced angiogenesis that is secreted through an unconventional secretory pathway based upon direct protein translocation across the plasma membrane. Here, we demonstrate that both PI(4,5)P2-dependent FGF2 recruitment at the inner plasma membrane leaflet and FGF2 membrane translocation into the extracellular space are positively modulated by cholesterol in living cells. We further revealed cholesterol to enhance FGF2 binding to PI(4,5)P2-containing lipid bilayers. Based on extensive atomistic molecular dynamics (MD) simulations and membrane tension experiments, we proposed cholesterol to modulate FGF2 binding to PI(4,5)P2 by (i) increasing head group visibility of PI(4,5)P2 on the membrane surface, (ii) increasing avidity by cholesterol-induced clustering of PI(4,5)P2 molecules triggering FGF2 oligomerization, and (iii) increasing membrane tension facilitating the formation of lipidic membrane pores. Our findings have general implications for phosphoinositide-dependent protein recruitment to membranes and explain the highly selective targeting of FGF2 toward the plasma membrane, the subcellular site of FGF2 membrane translocation during unconventional secretion of FGF2.
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Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany.,Department of Physics, University of Helsinki, Helsinki, Finland
| | | | - Alessandra Griffo
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany.,Biophysical Engineering Group, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Annalena Meyer
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Federica Scollo
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Bianca Pokrandt
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | | | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Hendrik Hähl
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany
| | | | - Ralf Seemann
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Britta Brügger
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Karin Jacobs
- Department of Experimental Physics, Saarland University, Saarbrücken, Germany.,Max Planck School Matter to Life, Heidelberg, Germany
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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7
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Joliot A, Prochiantz A. Unconventional Secretion, Gate to Homeoprotein Intercellular Transfer. Front Cell Dev Biol 2022; 10:926421. [PMID: 35837333 PMCID: PMC9274163 DOI: 10.3389/fcell.2022.926421] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/07/2022] [Indexed: 11/24/2022] Open
Abstract
Unconventional secretion allows for the secretion of fully mature and biologically active proteins mostly present in the cytoplasm or nucleus. Besides extra vesicle-driven secretion, non-extravesicular pathways also exist that specifically rely on the ability of the secreted proteins to translocate directly across the plasma membrane. This is the case for several homeoproteins, a family of over 300 transcription factors characterized by the structure of their DNA-binding homeodomain. The latter highly conserved homeodomain is necessary and sufficient for secretion, a process that requires PI(4,5)P2 binding, as is the case for FGF2 and HIV Tat unconventional secretion. An important feature of homeoproteins is their ability to cross membranes in both directions and thus to transfer between cells. This confers to homeoproteins their paracrine activity, an essential facet of their physiological functions.
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Affiliation(s)
- Alain Joliot
- INSERM U932, Institut Curie Centre de Recherche, PSL Research University, Paris, France
- *Correspondence: Alain Joliot,
| | - Alain Prochiantz
- Centre for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, PSL Research University, Labex MemoLife, Paris, France
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8
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Biswal MR, Padmanabhan S, Manjithaya R, Prakash MK. Early Bioinformatic Implication of Triacidic Amino Acid Motifs in Autophagy-Dependent Unconventional Secretion of Mammalian Proteins. Front Cell Dev Biol 2022; 10:863825. [PMID: 35646924 PMCID: PMC9136135 DOI: 10.3389/fcell.2022.863825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/11/2022] [Indexed: 11/22/2022] Open
Abstract
Several proteins are secreted outside the cell, and in many cases, they may be identified by a characteristic signal peptide. However, more and more studies point to the evidence for an “unconventional” secretion, where proteins without a hitherto unknown signal are secreted, possibly in conditions of starvation. In this work, we analyse a set of 202 RNA binding mammalian proteins, whose unconventional secretion has recently been established. Analysis of these proteins secreted by LC3 mediation, the largest unconventionally secreted dataset to our knowledge, identifies the role of KKX motif as well as triacidic amino acid motif in unconventional secretion, the latter being an extension of the recent implicated diacidic amino acid motif. Further data analysis evolves a hypothesis on the sequence or structural proximity of the triacidic or KKX motifs to the LC3 interacting region, and a phosphorylatable amino acid such as serine as a statistically significant feature among these unconventionally secreted proteins. This hypothesis, although needs to be validated in experiments that challenge the specific details of each of these aspects, appears to be one of the early steps in defining what may be a plausible signal for unconventional protein secretion.
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Affiliation(s)
- Malay Ranjan Biswal
- Computational Biology, Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
| | - Sreedevi Padmanabhan
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
| | - Ravi Manjithaya
- Autophagy Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
- *Correspondence: Ravi Manjithaya, ; Meher K. Prakash,
| | - Meher K. Prakash
- Computational Biology, Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
- *Correspondence: Ravi Manjithaya, ; Meher K. Prakash,
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9
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Unconventional secretion mediated by direct protein self-translocation across the plasma membranes of mammalian cells. Trends Biochem Sci 2022; 47:699-709. [PMID: 35490075 DOI: 10.1016/j.tibs.2022.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/22/2022] [Accepted: 04/01/2022] [Indexed: 12/17/2022]
Abstract
In recent years, a surprisingly complex picture emerged about endoplasmic reticulum (ER)/Golgi-independent secretory pathways, and several routes have been discovered that differ with regard to their molecular mechanisms and machineries. Fibroblast growth factor 2 (FGF2) is secreted by a pathway of unconventional protein secretion (UPS) that is based on direct self-translocation across the plasma membrane. Building on previous research, a component of this process has been identified to be glypican-1 (GPC1), a GPI-anchored heparan sulfate proteoglycan located on cell surfaces. These findings not only shed light on the molecular mechanism underlying this process but also reveal an intimate relationship between FGF2 and GPC1 that might be of critical relevance for the prominent roles they both have in tumor progression and metastasis.
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10
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Chen MM, Yang SR, Wang J, Fang YL, Peng YL, Fan J. Fungal oxysterol-binding protein-related proteins promote pathogen virulence and activate plant immunity. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2125-2141. [PMID: 34864987 DOI: 10.1093/jxb/erab530] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 12/02/2021] [Indexed: 06/13/2023]
Abstract
Oxysterol-binding protein-related proteins (ORPs) are a conserved class of lipid transfer proteins that are closely involved in multiple cellular processes in eukaryotes, but their roles in plant-pathogen interactions are mostly unknown. We show that transient expression of ORPs of Magnaporthe oryzae (MoORPs) in Nicotiana benthamina plants triggered oxidative bursts and cell death; treatment of tobacco Bright Yellow-2 suspension cells with recombinant MoORPs elicited the production of reactive oxygen species. Despite ORPs being normally described as intracellular proteins, we detected MoORPs in fungal culture filtrates and intercellular fluids from barley plants infected with the fungus. More importantly, infiltration of Arabidopsis plants with recombinant Arabidopsis or fungal ORPs activated oxidative bursts, callose deposition, and PR1 gene expression, and enhanced plant disease resistance, implying that ORPs may function as endogenous and exogenous danger signals triggering plant innate immunity. Extracellular application of fungal ORPs exerted an opposite impact on salicylic acid and jasmonic acid/ethylene signaling pathways. Brassinosteroid Insensitive 1-associated Kinase 1 was dispensable for the ORP-activated defense. Besides, simultaneous knockout of MoORP1 and MoORP3 abolished fungal colony radial growth and conidiation, whereas double knockout of MoORP1 and MoORP2 compromised fungal virulence on barley and rice plants. These observations collectively highlight the multifaceted role of MoORPs in the modulation of plant innate immunity and promotion of fungal development and virulence in M. oryzae.
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Affiliation(s)
- Meng-Meng Chen
- Department of Plant Pathology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Si-Ru Yang
- Department of Plant Pathology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Jian Wang
- Department of Plant Pathology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - Ya-Li Fang
- Department of Plant Pathology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
| | - You-Liang Peng
- Department of Plant Pathology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, China
| | - Jun Fan
- Department of Plant Pathology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, China
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11
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Lolicato F, Nickel W. A Role for Liquid-Ordered Plasma Membrane Nanodomains Coordinating the Unconventional Secretory Pathway of Fibroblast Growth Factor 2? Front Cell Dev Biol 2022; 10:864257. [PMID: 35433697 PMCID: PMC9010882 DOI: 10.3389/fcell.2022.864257] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 02/18/2022] [Indexed: 11/22/2022] Open
Abstract
Fibroblast growth factor 2 (FGF2) is a tumor cell survival factor that belongs to a subgroup of extracellular proteins lacking N-terminal signal peptides. Whereas this phenomenon was already recognized in the early 1990s, detailed insights into the molecular mechanisms underlying alternative pathways of protein secretion from eukaryotic cells were obtained only recently. Today, we know about a number of alternative secretory mechanisms, collectively termed unconventional protein secretion (UPS). FGF2 belongs to a subgroup of cargo proteins secreted by direct translocation across the plasma membrane. This feature has been classified as type I UPS and is shared with other unconventionally secreted proteins, such as HIV-Tat and Tau. FGF2 translocation across the membrane is initiated through sequential interactions with the Na,K-ATPase, Tec kinase, and phosphoinositide PI(4,5)P2 at the inner plasma membrane leaflet. Whereas the first two are auxiliary factors of this pathway, the interaction of FGF2 with PI(4,5)P2 triggers the core mechanism of FGF2 membrane translocation. It is based on a lipidic membrane pore that is formed by PI(4,5)P2-induced oligomerization of FGF2. Membrane-inserted FGF2 oligomers are recognized as translocation intermediates that are resolved at the outer plasma membrane leaflet by glypican-1, a heparan sulfate proteoglycan that captures and disassembles FGF2 oligomers on cell surfaces. Here, we discuss recent findings suggesting the molecular machinery mediating FGF2 membrane translocation to be highly organized in liquid-ordered plasma membrane nanodomains, the core process underlying this unusual pathway of protein secretion.
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12
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Sparn C, Dimou E, Meyer A, Saleppico R, Wegehingel S, Gerstner M, Klaus S, Ewers H, Nickel W. Glypican-1 drives unconventional secretion of Fibroblast Growth Factor 2. eLife 2022; 11:75545. [PMID: 35348113 PMCID: PMC8986318 DOI: 10.7554/elife.75545] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Fibroblast Growth Factor 2 (FGF2) is a tumor cell survival factor that is transported into the extracellular space by an unconventional secretory mechanism. Cell surface heparan sulfate proteoglycans are known to play an essential role in this process. Unexpectedly, we found that among the diverse sub-classes consisting of syndecans, perlecans, glypicans and others, Glypican-1 (GPC1) is the principle and rate-limiting factor that drives unconventional secretion of FGF2. By contrast, we demonstrate GPC1 to be dispensable for FGF2 signaling into cells. We provide first insights into the structural basis for GPC1-dependent FGF2 secretion, identifying disaccharides with N-linked sulfate groups to be enriched in the heparan sulfate chains of GPC1 to which FGF2 binds with high affinity. Our findings have broad implications for the role of GPC1 as a key molecule in tumor progression.
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Affiliation(s)
| | | | | | | | | | | | | | - Helge Ewers
- Institut für Chemie und Biochemie, Freie Universität Berlin
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13
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Filaquier A, Marin P, Parmentier ML, Villeneuve J. Roads and hubs of unconventional protein secretion. Curr Opin Cell Biol 2022; 75:102072. [PMID: 35305454 DOI: 10.1016/j.ceb.2022.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/07/2022] [Accepted: 02/14/2022] [Indexed: 12/11/2022]
Abstract
In eukaryotes, there is now compelling evidence that in addition to the conventional endoplasmic reticulum-Golgi secretory pathway, there are additional routes for the export of cytoplasmic proteins with a critical role in numerous physio-pathological conditions. These alternative secretory pathways or unconventional protein secretion (UPS) start now to be molecularly dissected, and while UPS landscape appears to be governed by a striking diversity and heterogeneity of mechanisms, common principles are emerging. We review here the role of key molecular determinants as well as the role of central hubs for UPS, highlighting the plasticity and dynamic properties of membrane-bound compartments. We also describe recent findings that position UPS as an integral component of adaptive responses to cope with particular cellular needs and stresses.
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Affiliation(s)
- Aurore Filaquier
- Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Philippe Marin
- Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Marie-Laure Parmentier
- Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Julien Villeneuve
- Institute of Functional Genomics, University of Montpellier, CNRS, INSERM, Montpellier, France.
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14
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Identification of cis-acting determinants mediating the unconventional secretion of tau. Sci Rep 2021; 11:12946. [PMID: 34155306 PMCID: PMC8217235 DOI: 10.1038/s41598-021-92433-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/31/2021] [Indexed: 12/23/2022] Open
Abstract
The deposition of tau aggregates throughout the brain is a pathological characteristic within a group of neurodegenerative diseases collectively termed tauopathies, which includes Alzheimer’s disease. While recent findings suggest the involvement of unconventional secretory pathways driving tau into the extracellular space and mediating the propagation of the disease-associated pathology, many of the mechanistic details governing this process remain elusive. In the current study, we provide an in-depth characterization of the unconventional secretory pathway of tau and identify novel molecular determinants that are required for this process. Here, using Drosophila models of tauopathy, we correlate the hyperphosphorylation and aggregation state of tau with the disease-related neurotoxicity. These newly established systems recapitulate all the previously identified hallmarks of tau secretion, including the contribution of tau hyperphosphorylation as well as the requirement for PI(4,5)P2 triggering the direct translocation of tau. Using a series of cellular assays, we demonstrate that both the sulfated proteoglycans on the cell surface and the correct orientation of the protein at the inner plasma membrane leaflet are critical determinants of this process. Finally, we identify two cysteine residues within the microtubule binding repeat domain as novel cis-elements that are important for both unconventional secretion and trans-cellular propagation of tau.
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15
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Lee B, Shin M, Park Y, Won SY, Cho KS. Physical Exercise-Induced Myokines in Neurodegenerative Diseases. Int J Mol Sci 2021; 22:ijms22115795. [PMID: 34071457 PMCID: PMC8198301 DOI: 10.3390/ijms22115795] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/18/2022] Open
Abstract
Neurodegenerative diseases (NDs), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS), are disorders characterized by progressive degeneration of the nervous system. Currently, there is no disease-modifying treatments for most NDs. Meanwhile, numerous studies conducted on human and animal models over the past decades have showed that exercises had beneficial effects on NDs. Inter-tissue communication by myokine, a peptide produced and secreted by skeletal muscles during exercise, is thought to be an important underlying mechanism for the advantages. Here, we reviewed studies about the effects of myokines regulated by exercise on NDs and their mechanisms. Myokines could exert beneficial effects on NDs through a variety of regulatory mechanisms, including cell survival, neurogenesis, neuroinflammation, proteostasis, oxidative stress, and protein modification. Studies on exercise-induced myokines are expected to provide a novel strategy for treating NDs, for which there are no adequate treatments nowadays. To date, only a few myokines have been investigated for their effects on NDs and studies on mechanisms involved in them are in their infancy. Therefore, future studies are needed to discover more myokines and test their effects on NDs.
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Affiliation(s)
- Banseok Lee
- Department of Biological Sciences, Konkuk University, Seoul 05029, Korea; (B.L.); (M.S.); (Y.P.)
| | - Myeongcheol Shin
- Department of Biological Sciences, Konkuk University, Seoul 05029, Korea; (B.L.); (M.S.); (Y.P.)
| | - Youngjae Park
- Department of Biological Sciences, Konkuk University, Seoul 05029, Korea; (B.L.); (M.S.); (Y.P.)
| | - So-Yoon Won
- Department of Biological Sciences, Konkuk University, Seoul 05029, Korea; (B.L.); (M.S.); (Y.P.)
- Korea Hemp Institute, Konkuk University, Seoul 05029, Korea
- Correspondence: (S.-Y.W.); (K.S.C.); Tel.: +82-10-3688-5474 (S.-Y.W.); Tel.: +82-2-450-3424 (K.S.C.)
| | - Kyoung Sang Cho
- Department of Biological Sciences, Konkuk University, Seoul 05029, Korea; (B.L.); (M.S.); (Y.P.)
- Korea Hemp Institute, Konkuk University, Seoul 05029, Korea
- Correspondence: (S.-Y.W.); (K.S.C.); Tel.: +82-10-3688-5474 (S.-Y.W.); Tel.: +82-2-450-3424 (K.S.C.)
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16
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Balmer EA, Faso C. The Road Less Traveled? Unconventional Protein Secretion at Parasite-Host Interfaces. Front Cell Dev Biol 2021; 9:662711. [PMID: 34109175 PMCID: PMC8182054 DOI: 10.3389/fcell.2021.662711] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/07/2021] [Indexed: 01/01/2023] Open
Abstract
Protein secretion in eukaryotic cells is a well-studied process, which has been known for decades and is dealt with by any standard cell biology textbook. However, over the past 20 years, several studies led to the realization that protein secretion as a process might not be as uniform among different cargos as once thought. While in classic canonical secretion proteins carry a signal sequence, the secretory or surface proteome of several organisms demonstrated a lack of such signals in several secreted proteins. Other proteins were found to indeed carry a leader sequence, but simply circumvent the Golgi apparatus, which in canonical secretion is generally responsible for the modification and sorting of secretory proteins after their passage through the endoplasmic reticulum (ER). These alternative mechanisms of protein translocation to, or across, the plasma membrane were collectively termed “unconventional protein secretion” (UPS). To date, many research groups have studied UPS in their respective model organism of choice, with surprising reports on the proportion of unconventionally secreted proteins and their crucial roles for the cell and survival of the organism. Involved in processes such as immune responses and cell proliferation, and including far more different cargo proteins in different organisms than anyone had expected, unconventional secretion does not seem so unconventional after all. Alongside mammalian cells, much work on this topic has been done on protist parasites, including genera Leishmania, Trypanosoma, Plasmodium, Trichomonas, Giardia, and Entamoeba. Studies on protein secretion have mainly focused on parasite-derived virulence factors as a main source of pathogenicity for hosts. Given their need to secrete a variety of substrates, which may not be compatible with canonical secretion pathways, the study of mechanisms for alternative secretion pathways is particularly interesting in protist parasites. In this review, we provide an overview on the current status of knowledge on UPS in parasitic protists preceded by a brief overview of UPS in the mammalian cell model with a focus on IL-1β and FGF-2 as paradigmatic UPS substrates.
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Affiliation(s)
- Erina A Balmer
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Carmen Faso
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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17
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Šachl R, Čujová S, Singh V, Riegerová P, Kapusta P, Müller HM, Steringer JP, Hof M, Nickel W. Functional Assay to Correlate Protein Oligomerization States with Membrane Pore Formation. Anal Chem 2020; 92:14861-14866. [PMID: 33198473 DOI: 10.1021/acs.analchem.0c03276] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In-membrane oligomerization is decisive for the function (or dysfunction) of many proteins. Techniques were developed to characterize membrane-inserted oligomers and the hereby obtained oligomerization states were intuitively related to the function of these proteins. However, in many cases, it is unclear whether the obtained oligomerization states are functionally relevant or are merely the consequence of nonspecific aggregation. Using fibroblast growth factor 2 (FGF2) as a model system, we addressed this methodological challenge. FGF2 oligomerizes in a PI(4,5)P2-dependent manner at the inner plasma membrane leaflet. This process results in membrane insertion and the formation of a lipidic membrane pore, the key intermediate in unconventional secretion of FGF2. To tackle the problem of discriminating functional oligomers from irrelevant aggregates, we present a statistical single molecule and single vesicle assay determining the brightness of individually diffusing in-membrane oligomers and correlating their oligomerization state with membrane pore formation. Importantly, time-dependent membrane pore formation was analyzed with an ensemble of single vesicles providing detailed statistics. Our findings demonstrate that quantifying oligomeric states alone does not allow for a deep understanding of the structure-function relationship of membrane-inserted oligomers.
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Affiliation(s)
- Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3 182 23 Prague, Czech Republic
| | - Sabína Čujová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3 182 23 Prague, Czech Republic
| | - Vandana Singh
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3 182 23 Prague, Czech Republic
| | - Petra Riegerová
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3 182 23 Prague, Czech Republic
| | - Peter Kapusta
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3 182 23 Prague, Czech Republic
| | - Hans-Michael Müller
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69 120 Heidelberg, Germany
| | - Julia P Steringer
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69 120 Heidelberg, Germany
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3 182 23 Prague, Czech Republic
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69 120 Heidelberg, Germany
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18
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Pallotta MT, Nickel W. FGF2 and IL-1β – explorers of unconventional secretory pathways at a glance. J Cell Sci 2020; 133:133/21/jcs250449. [DOI: 10.1242/jcs.250449] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ABSTRACT
Fibroblast growth factor 2 (FGF2) and interleukin 1β (IL-1β) were among the earliest examples of a subclass of proteins with extracellular functions that were found to lack N-terminal secretory signal peptides and were shown to be secreted in an ER- and Golgi-independent manner. Many years later, a number of alternative secretory pathways have been discovered, processes collectively termed unconventional protein secretion (UPS). In the course of these studies, unconventional secretion of FGF2 and IL-1β were found to be based upon distinct pathways, mechanisms and molecular machineries. Following a concise introduction into various pathways mediating unconventional secretion and transcellular spreading of proteins, this Cell Science at a Glance poster article aims at a focused analysis of recent key discoveries providing unprecedented detail about the molecular mechanisms and machineries driving FGF2 and IL-1β secretion. These findings are also highly relevant for other unconventionally secreted cargoes that, like FGF2 and IL1β, exert fundamental biological functions in biomedically relevant processes, such as tumor-induced angiogenesis and inflammation.
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Affiliation(s)
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg 69120, Germany
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19
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Merezhko M, Uronen RL, Huttunen HJ. The Cell Biology of Tau Secretion. Front Mol Neurosci 2020; 13:569818. [PMID: 33071756 PMCID: PMC7539664 DOI: 10.3389/fnmol.2020.569818] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/26/2020] [Indexed: 12/27/2022] Open
Abstract
The progressive accumulation and spread of misfolded tau protein in the nervous system is the hallmark of tauopathies, progressive neurodegenerative diseases with only symptomatic treatments available. A growing body of evidence suggests that spreading of tau pathology can occur via cell-to-cell transfer involving secretion and internalization of pathological forms of tau protein followed by templated misfolding of normal tau in recipient cells. Several studies have addressed the cell biological mechanisms of tau secretion. It now appears that instead of a single mechanism, cells can secrete tau via three coexisting pathways: (1) translocation through the plasma membrane; (2) membranous organelles-based secretion; and (3) ectosomal shedding. The relative importance of these pathways in the secretion of normal and pathological tau is still elusive, though. Moreover, glial cells contribute to tau propagation, and the involvement of different cell types, as well as different secretion pathways, complicates the understanding of prion-like propagation of tauopathy. One of the important regulators of tau secretion in neuronal activity, but its mechanistic connection to tau secretion remains unclear and may involve all three secretion pathways of tau. This review article summarizes recent advancements in the field of tau secretion with an emphasis on cell biological aspects of the secretion process and discusses the role of neuronal activity and glial cells in the spread of pathological forms of tau.
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Affiliation(s)
- Maria Merezhko
- Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
| | | | - Henri J Huttunen
- Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
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20
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Kosnopfel C, Sinnberg T, Sauer B, Niessner H, Muenchow A, Fehrenbacher B, Schaller M, Mertens PR, Garbe C, Thakur BK, Schittek B. Tumour Progression Stage-Dependent Secretion of YB-1 Stimulates Melanoma Cell Migration and Invasion. Cancers (Basel) 2020; 12:cancers12082328. [PMID: 32824741 PMCID: PMC7464723 DOI: 10.3390/cancers12082328] [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: 07/21/2020] [Revised: 08/10/2020] [Accepted: 08/16/2020] [Indexed: 12/16/2022] Open
Abstract
Secreted factors play an important role in intercellular communication. Therefore, they are not only indispensable for the regulation of various physiological processes but can also decisively advance the development and progression of tumours. In the context of inflammatory disease, Y-box binding protein 1 (YB-1) is actively secreted and the extracellular protein promotes cell proliferation and migration. In malignant melanoma, intracellular YB-1 expression increases during melanoma progression and represents an unfavourable prognostic marker. Here, we show active secretion of YB-1 from melanoma cells as opposed to benign cells of the skin. Intriguingly, YB-1 secretion correlates with the stage of melanoma progression and depends on a calcium- and ATP-dependent non-classical secretory pathway leading to the occurrence of YB-1 in the extracellular space as a free protein. Along with an elevated YB-1 secretion of melanoma cells in the metastatic growth phase, extracellular YB-1 exerts a stimulating effect on melanoma cell migration, invasion, and tumourigenicity. Collectively, these data suggest that secreted YB-1 plays a functional role in melanoma cell biology, stimulating metastasis, and may serve as a novel biomarker in malignant melanoma that reflects tumour aggressiveness.
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Affiliation(s)
- Corinna Kosnopfel
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
- Department of Dermatology, University Hospital Würzburg, 97080 Würzburg, Germany
- Correspondence: (C.K.); (B.S.); Tel.: +49-931-20126778 (C.K.); +49-7071-29-80832 (B.S.)
| | - Tobias Sinnberg
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Birgit Sauer
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Heike Niessner
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Alina Muenchow
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Birgit Fehrenbacher
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Martin Schaller
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Peter R. Mertens
- Department of Nephrology and Hypertension, Diabetes and Endocrinology, Otto-von-Guericke University, 39120 Magdeburg, Germany;
| | - Claus Garbe
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
| | - Basant Kumar Thakur
- Department of Pediatric Hematology and Oncology, University Hospital Essen, 45147 Essen, Germany;
| | - Birgit Schittek
- Department of Dermatology, University of Tübingen, 72076 Tübingen, Germany; (T.S.); (B.S.); (H.N.); (A.M.); (B.F.); (M.S.); (C.G.)
- Correspondence: (C.K.); (B.S.); Tel.: +49-931-20126778 (C.K.); +49-7071-29-80832 (B.S.)
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21
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Amblard I, Dupont E, Alves I, Miralvès J, Queguiner I, Joliot A. Bidirectional transfer of homeoprotein EN2 across the plasma membrane requires PIP 2. J Cell Sci 2020; 133:jcs244327. [PMID: 32434869 DOI: 10.1242/jcs.244327] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/05/2020] [Indexed: 01/21/2023] Open
Abstract
Homeoproteins are a class of transcription factors sharing the unexpected property of intercellular trafficking that confers to homeoproteins a paracrine mode of action. Homeoprotein paracrine action participates in the control of patterning processes, including axonal guidance, brain plasticity and boundary formation. Internalization and secretion, the two steps of intercellular transfer, rely on unconventional mechanisms, but the cellular mechanisms at stake still need to be fully characterized. Thanks to the design of new quantitative and sensitive assays dedicated to the study of homeoprotein transfer within HeLa cells in culture, we demonstrate a core role of phosphatidylinositol (4,5)-bisphosphate (PIP2) together with cholesterol in the translocation of the homeobox protein engrailed-2 (EN2) across the plasma membrane. By using drug and enzyme treatments, we show that both secretion and internalization are regulated according to PIP2 levels. The requirement for PIP2 and cholesterol in EN2 trafficking correlates with their selective affinity for this protein in artificial bilayers, which is drastically decreased in a paracrine-deficient mutant of EN2. We propose that the bidirectional plasma membrane translocation events that occur during homeoprotein secretion and internalization are parts of a common process.
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Affiliation(s)
- Irène Amblard
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
- Sorbonne University, Paris, France
| | - Edmond Dupont
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Isabel Alves
- CBMN, UMR 5248 CNRS, University of Bordeaux, 33600 Pessac, France
| | - Julie Miralvès
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Isabelle Queguiner
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Alain Joliot
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, PSL Research University, 75005 Paris, France
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22
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Sluzalska KD, Slawski J, Sochacka M, Lampart A, Otlewski J, Zakrzewska M. Intracellular partners of fibroblast growth factors 1 and 2 - implications for functions. Cytokine Growth Factor Rev 2020; 57:93-111. [PMID: 32475760 DOI: 10.1016/j.cytogfr.2020.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/04/2020] [Accepted: 05/07/2020] [Indexed: 01/01/2023]
Abstract
Fibroblast growth factors 1 and 2 (FGF1 and FGF2) are mainly considered as ligands of surface receptors through which they regulate a broad spectrum of biological processes. They are secreted in non-canonical way and, unlike other growth factors, they are able to translocate from the endosome to the cell interior. These unique features, as well as the role of the intracellular pool of FGF1 and FGF2, are far from being fully understood. An increasing number of reports address this problem, focusing on the intracellular interactions of FGF1 and 2. Here, we summarize the current state of knowledge of the FGF1 and FGF2 binding partners inside the cell and the possible role of these interactions. The partner proteins are grouped according to their function, including proteins involved in secretion, cell signaling, nucleocytoplasmic transport, binding and processing of nucleic acids, ATP binding, and cytoskeleton assembly. An in-depth analysis of the network of these binding partners could indicate novel, non-classical functions of FGF1 and FGF2 and uncover an additional level of a fine control of the well-known FGF-regulated cellular processes.
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Affiliation(s)
- Katarzyna Dominika Sluzalska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Jakub Slawski
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Martyna Sochacka
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Agata Lampart
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Jacek Otlewski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland
| | - Malgorzata Zakrzewska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, ul. F. Joliot-Curie 14a, 50-383 Wroclaw, Poland.
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23
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Legrand C, Saleppico R, Sticht J, Lolicato F, Müller HM, Wegehingel S, Dimou E, Steringer JP, Ewers H, Vattulainen I, Freund C, Nickel W. The Na,K-ATPase acts upstream of phosphoinositide PI(4,5)P 2 facilitating unconventional secretion of Fibroblast Growth Factor 2. Commun Biol 2020; 3:141. [PMID: 32214225 PMCID: PMC7096399 DOI: 10.1038/s42003-020-0871-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 03/02/2020] [Indexed: 12/19/2022] Open
Abstract
FGF2 is a tumor cell survival factor that is exported from cells by an ER/Golgi-independent secretory pathway. This unconventional mechanism of protein secretion is based on direct translocation of FGF2 across the plasma membrane. The Na,K-ATPase has previously been shown to play a role in this process, however, the underlying mechanism has remained elusive. Here, we define structural elements that are critical for a direct physical interaction between FGF2 and the α1 subunit of the Na,K-ATPase. In intact cells, corresponding FGF2 mutant forms were impaired regarding both recruitment at the inner plasma membrane leaflet and secretion. Ouabain, a drug that inhibits both the Na,K-ATPase and FGF2 secretion, was found to impair the interaction of FGF2 with the Na,K-ATPase in cells. Our findings reveal the Na,K-ATPase as the initial recruitment factor for FGF2 at the inner plasma membrane leaflet being required for efficient membrane translocation of FGF2 to cell surfaces. Legrand et al. identify two lysine residues on molecular surface of Fibroblast Growth Factor 2 (FGF2) essential for its interaction with α1 subunit of the Na,K-ATPase. They further conclude that this interaction precedes interaction of the FGF2 with PI(4,5)P2 and facilitates its unconventional secretion across the membrane, which is impaired by Ouabain, an Na,K-ATPase inhibitor.
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Affiliation(s)
- Cyril Legrand
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Roberto Saleppico
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Jana Sticht
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany.,Core Facility BioSupraMol, Freie Universität Berlin, Berlin, Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany.,Department of Physics, University of Helsinki, FL-00014, Helsinki, Finland.,Computational Physics Laboratory, Tampere University, Fl-33100, Tampere, Finland
| | - Hans-Michael Müller
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Sabine Wegehingel
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Eleni Dimou
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Julia P Steringer
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, FL-00014, Helsinki, Finland.,Computational Physics Laboratory, Tampere University, Fl-33100, Tampere, Finland
| | - Christian Freund
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany.
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24
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Loschwitz J, Olubiyi OO, Hub JS, Strodel B, Poojari CS. Computer simulations of protein-membrane systems. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 170:273-403. [PMID: 32145948 PMCID: PMC7109768 DOI: 10.1016/bs.pmbts.2020.01.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The interactions between proteins and membranes play critical roles in signal transduction, cell motility, and transport, and they are involved in many types of diseases. Molecular dynamics (MD) simulations have greatly contributed to our understanding of protein-membrane interactions, promoted by a dramatic development of MD-related software, increasingly accurate force fields, and available computer power. In this chapter, we present available methods for studying protein-membrane systems with MD simulations, including an overview about the various all-atom and coarse-grained force fields for lipids, and useful software for membrane simulation setup and analysis. A large set of case studies is discussed.
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Affiliation(s)
- Jennifer Loschwitz
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Olujide O Olubiyi
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany; Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
| | - Birgit Strodel
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
| | - Chetan S Poojari
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany.
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Unconventional Secretion Mediates the Trans-cellular Spreading of Tau. Cell Rep 2019; 23:2039-2055. [PMID: 29768203 DOI: 10.1016/j.celrep.2018.04.056] [Citation(s) in RCA: 167] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 01/19/2018] [Accepted: 04/13/2018] [Indexed: 12/12/2022] Open
Abstract
The progressive deposition of misfolded hyperphosphorylated tau is a pathological hallmark of tauopathies, including Alzheimer's disease. However, the underlying molecular mechanisms governing the intercellular spreading of tau species remain elusive. Here, we show that full-length soluble tau is unconventionally secreted by direct translocation across the plasma membrane. Increased secretion is favored by tau hyperphosphorylation, which provokes microtubule detachment and increases the availability of free protein inside cells. Using a series of binding assays, we show that free tau interacts with components enriched at the inner leaflet of the plasma membrane, finally leading to its translocation across the plasma membrane mediated by sulfated proteoglycans. We provide further evidence that secreted soluble tau species spread trans-cellularly and are sufficient for the induction of intracellular tau aggregation in adjacent cells. Our study demonstrates the mechanistic details of tau secretion and provides insights into the initiation and progression of tau pathology.
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Khanna K, Chaudhuri R, Aich J, Pattnaik B, Panda L, Prakash YS, Mabalirajan U, Ghosh B, Agrawal A. Secretory Inositol Polyphosphate 4-Phosphatase Protects against Airway Inflammation and Remodeling. Am J Respir Cell Mol Biol 2019; 60:399-412. [PMID: 30335467 PMCID: PMC6444634 DOI: 10.1165/rcmb.2017-0353oc] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 09/14/2018] [Indexed: 01/16/2023] Open
Abstract
The asthma candidate gene inositol polyphosphate 4-phosphatase type I A (INPP4A) is a lipid phosphatase that negatively regulates the PI3K/Akt pathway. Destabilizing genetic variants of INPP4A increase the risk of asthma, and lung-specific INPP4A knockdown induces asthma-like features. INPP4A is known to localize intracellularly, and its extracellular presence has not been reported yet. Here we show for the first time that INPP4A is secreted by airway epithelial cells and that extracellular INPP4A critically inhibits airway inflammation and remodeling. INPP4A was present in blood and BAL fluid, and this extracellular INPP4A was reduced in patients with asthma and mice with allergic airway inflammation. In both naive mice and mice with allergic airway inflammation, antibody-mediated neutralization of extracellular INPP4A potentiated PI3K/Akt signaling and induced airway hyperresponsiveness, with prominent airway remodeling, subepithelial fibroblast proliferation, and collagen deposition. The link between extracellular INPP4A and fibroblasts was investigated in vitro. Cultured airway epithelial cells secreted enzymatically active INPP4A in extracellular vesicles and in a free form. Extracellular vesicle-mediated transfer of labeled INPP4A, from epithelial cells to fibroblasts, was observed. Inhibition of such transfer by anti-INPP4A antibody increased fibroblast proliferation. We propose that secretory INPP4A is a novel "paracrine" layer of the intricate regulation of lung homeostasis, by which airway epithelium dampens PI3K/Akt signaling in inflammatory cells or local fibroblasts, thereby limiting inflammation and remodeling.
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Affiliation(s)
- Kritika Khanna
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Rituparna Chaudhuri
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Jyotirmoi Aich
- Centre of Excellence for Translational Research in Asthma and Lung Disease
| | - Bijay Pattnaik
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
- Department of Pulmonary Medicine and Sleep Disorders, All India Institute of Medical Sciences, New Delhi, India; and
| | - Lipsa Panda
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Y. S. Prakash
- Department of Anesthesiology
- Department of Physiology, and
- Department of Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Ulaganathan Mabalirajan
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
| | - Balaram Ghosh
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
| | - Anurag Agrawal
- Centre of Excellence for Translational Research in Asthma and Lung Disease
- Molecular Immunogenetics Laboratory, and
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Delhi, India
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Botero S, Chiaroni-Clarke R, Simon SM. Escherichia coli as a platform for the study of phosphoinositide biology. SCIENCE ADVANCES 2019; 5:eaat4872. [PMID: 30944849 PMCID: PMC6436935 DOI: 10.1126/sciadv.aat4872] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Despite being a minor component of cells, phosphoinositides are essential for eukaryotic membrane biology, serving as markers of organelle identity and involved in several signaling cascades. Their many functions, combined with alternative synthesis pathways, make in vivo study very difficult. In vitro studies are limited by their inability to fully recapitulate the complexities of membranes in living cells. We engineered the biosynthetic pathway for the most abundant phosphoinositides into the bacterium Escherichia coli, which is naturally devoid of this class of phospholipids. These modified E. coli, when grown in the presence of myo-inositol, incorporate phosphatidylinositol (PI), phosphatidylinositol-4-phosphate (PI4P), phosphatidylinositol-4,5-bisphosphate (PIP2), and phosphatidylinositol-3,4,5-trisphosphate (PIP3) into their plasma membrane. We tested models of biophysical mechanisms with these phosphoinositides in a living membrane, using our system to evaluate the role of PIP2 in nonconventional protein export of human basic fibroblast growth factor 2. We found that PI alone is sufficient for the process.
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Dimou E, Cosentino K, Platonova E, Ros U, Sadeghi M, Kashyap P, Katsinelos T, Wegehingel S, Noé F, García-Sáez AJ, Ewers H, Nickel W. Single event visualization of unconventional secretion of FGF2. J Cell Biol 2018; 218:683-699. [PMID: 30470711 PMCID: PMC6363455 DOI: 10.1083/jcb.201802008] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 07/07/2018] [Accepted: 11/08/2018] [Indexed: 12/29/2022] Open
Abstract
FGF2 is a cell survival factor secreted by unconventional means. Dimou et al. visualize individual FGF2 translocation events at the plasma membrane by live cell TIRF microscopy, providing insight into the kinetics and the mechanism of this process. FGF2 is exported from cells by an unconventional secretory mechanism. Here, we directly visualized individual FGF2 membrane translocation events at the plasma membrane using live cell TIRF microscopy. This process was dependent on both PI(4,5)P2–mediated recruitment of FGF2 at the inner leaflet and heparan sulfates capturing FGF2 at the outer plasma membrane leaflet. By simultaneous imaging of both FGF2 membrane recruitment and the appearance of FGF2 at the cell surface, we revealed the kinetics of FGF2 membrane translocation in living cells with an average duration of ∼200 ms. Furthermore, we directly demonstrated FGF2 oligomers at the inner leaflet of living cells with a FGF2 dimer being the most prominent species. We propose this dimer to represent a key intermediate in the formation of higher FGF2 oligomers that form membrane pores and put forward a kinetic model explaining the mechanism by which membrane-inserted FGF2 oligomers serve as dynamic translocation intermediates during unconventional secretion of FGF2.
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Affiliation(s)
- Eleni Dimou
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Katia Cosentino
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Evgenia Platonova
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
| | - Uris Ros
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Mohsen Sadeghi
- Department of Mathematics and Computer Science, Free University Berlin, Berlin, Germany
| | - Purba Kashyap
- Institute for Chemistry and Biochemistry, Free University Berlin, Berlin, Germany
| | | | | | - Frank Noé
- Department of Mathematics and Computer Science, Free University Berlin, Berlin, Germany
| | - Ana J García-Sáez
- Interfaculty Institute of Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Helge Ewers
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK .,Institute for Chemistry and Biochemistry, Free University Berlin, Berlin, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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29
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Claude-Taupin A, Bissa B, Jia J, Gu Y, Deretic V. Role of autophagy in IL-1β export and release from cells. Semin Cell Dev Biol 2018; 83:36-41. [PMID: 29580970 PMCID: PMC6173661 DOI: 10.1016/j.semcdb.2018.03.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/20/2018] [Accepted: 03/20/2018] [Indexed: 01/12/2023]
Abstract
The autophagy pathway known also as macroautophagy (herein referred to as autophagy) is characterized by the formation of double-membrane organelles that capture cytosolic material. Based on pathway termination alternatives, autophagy has been divided into degradative and secretory. During degradative autophagy, autophagosomes typically fuse with lysosomes upon which the sequestered material is degraded. During secretory autophagy, instead of degradation the sequestered cargo is subjected to active secretion or passive release. In this review, we focus on the mechanisms of secretion/passive release of the potent pro-inflammatory cytokine IL-1β, as a prototypical leaderless cytosolic protein cargo studied in the context of secretory autophagy.
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Affiliation(s)
- Aurore Claude-Taupin
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA; Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA
| | - Bhawana Bissa
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA; Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA
| | - Jingyue Jia
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA; Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA
| | - Yuexi Gu
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA; Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA
| | - Vojo Deretic
- Autophagy Inflammation and Metabolism Center of Biomedical Research Excellence, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA; Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, 915 Camino de Salud, NE, Albuquerque, NM 87131 USA.
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30
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Popa SJ, Stewart SE, Moreau K. Unconventional secretion of annexins and galectins. Semin Cell Dev Biol 2018; 83:42-50. [PMID: 29501720 PMCID: PMC6565930 DOI: 10.1016/j.semcdb.2018.02.022] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 02/23/2018] [Accepted: 02/26/2018] [Indexed: 12/31/2022]
Abstract
Eukaryotic cells have a highly evolved system of protein secretion, and dysfunction in this pathway is associated with many diseases including cancer, infection, metabolic disease and neurological disorders. Most proteins are secreted using the conventional endoplasmic reticulum (ER)/Golgi network and as such, this pathway is well-characterised. However, several cytosolic proteins have now been documented as secreted by unconventional transport pathways. This review focuses on two of these proteins families: annexins and galectins. The extracellular functions of these proteins are well documented, as are associations of their perturbed secretion with several diseases. However, the mechanisms and regulation of their secretion remain poorly characterised, and are discussed in this review. This review is part of a Special Issues of SCDB on 'unconventional protein secretion' edited by Walter Nickel and Catherine Rabouille.
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Affiliation(s)
- Stephanie J Popa
- University of Cambridge, Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge, CB2 0QQ, UK
| | - Sarah E Stewart
- University of Cambridge, Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge, CB2 0QQ, UK
| | - Kevin Moreau
- University of Cambridge, Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge, CB2 0QQ, UK.
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31
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Urano Y, Mori C, Fuji A, Konno K, Yamamoto T, Yashirogi S, Ando M, Saito Y, Noguchi N. 6-Hydroxydopamine induces secretion of PARK7/DJ-1 via autophagy-based unconventional secretory pathway. Autophagy 2018; 14:1943-1958. [PMID: 30112966 PMCID: PMC6152502 DOI: 10.1080/15548627.2018.1493043] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
PARK7/DJ-1 is a Parkinson disease- and cancer-associated protein that functions as a multifunctional protein involved in gene transcription regulation and anti-oxidative defense. Although PARK7 lacks the secretory signal sequence, it is secreted and plays important physiological and pathophysiological roles. Whereas secretory proteins that lack the endoplasmic reticulum-targeting signal sequence are secreted from cells by way of what is called the unconventional secretion mechanism, the specific processes responsible for causing PARK7 to be secreted across the plasma membrane have remained unclear. In the present study, we found that PARK7 secretion was increased by treatment with 6-OHDA via the unconventional secretory pathway in human neuroblastoma SH-SY5Y cells and MEF cells. We also found that 6-OHDA-induced PARK7 secretion was suppressed in Atg5-, Atg9-, or Atg16l1-deficient MEF cells or ATG16L1 knockdown SH-SY5Y cells, indicating that the autophagy-based unconventional secretory pathway is involved in PARK7 secretion. We moreover observed that 6-OHDA-derived electrophilic quinone induced oxidative stress as indicated by a decrease in glutathione levels, and that this was suppressed by pretreatment with antioxidant NAC. We further found that NAC treatment suppressed autophagy and PARK7 secretion. We also observed that 6-OHDA-induced autophagy was associated with activation of AMPK and ULK1 via a pathway which was independent of MTOR. Collectively these results suggest that electrophilic 6-OHDA quinone enhances oxidative stress, and that this is followed by AMPK-ULK1 pathway activation and induction of secretory autophagy to produce unconventional secretion of PARK7. Abbreviations: 6-OHDA: 6-hydroxydopamine; AMPK: AMP-activated protein kinase; ATG: autophagy related; CAV1: caveolin 1; ER: endoplasmic reticulum; FN1: fibronectin 1; GSH: glutathione; IDE: insulin degrading enzyme; IL: interleukin; LDH: lactate dehydrogenase; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; MTOR: mechanistic target of rapamycin kinase; NAC: N-acetyl-L-cysteine; PARK7/DJ-1: Parkinsonism associated deglycase; PD: Parkinson disease; RPS6KB1/p70S6K: ribosomal protein S6 kinase B1; RPN1: ribophorin I; ROS: reactive oxygen species; ULK1: unc-51 like autophagy activating kinase 1; WT: wild-type
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Affiliation(s)
- Yasuomi Urano
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Chinatsu Mori
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Ayano Fuji
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Keito Konno
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Takayuki Yamamoto
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Shohei Yashirogi
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Mayu Ando
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Yoshiro Saito
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
| | - Noriko Noguchi
- a Department of Medical Life Systems, Faculty of Life and Medical Sciences , Doshisha University , Kyoto , Japan
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Mele AR, Marino J, Chen K, Pirrone V, Janetopoulos C, Wigdahl B, Klase Z, Nonnemacher MR. Defining the molecular mechanisms of HIV-1 Tat secretion: PtdIns(4,5)P 2 at the epicenter. Traffic 2018; 19:10.1111/tra.12578. [PMID: 29708629 PMCID: PMC6207469 DOI: 10.1111/tra.12578] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/18/2022]
Abstract
The human immunodeficiency virus type 1 (HIV-1) transactivator of transcription (Tat) protein functions both intracellularly and extracellularly. Intracellularly, the main function is to enhance transcription of the viral promoter. However, this process only requires a small amount of intracellular Tat. The majority of Tat is secreted through an unconventional mechanism by binding to phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2 ), a phospholipid in the inner leaflet of the plasma membrane that is required for secretion. This interaction is mediated by the basic domain of Tat (residues 48-57) and a conserved tryptophan (residue 11). After binding to PtdIns(4,5)P2 , Tat secretion diverges into multiple pathways, which we categorized as oligomerization-mediated pore formation, spontaneous translocation and incorporation into exosomes. Extracellular Tat has been shown to be neurotoxic and toxic to other cells of the central nervous system (CNS) and periphery, able to recruit immune cells to the CNS and cerebrospinal fluid, and alter the gene expression and morphology of uninfected cells. The effects of extracellular Tat have been examined in HIV-1-associated neurocognitive disorders (HAND); however, only a small number of studies have focused on the mechanisms underlying Tat secretion. In this review, the molecular mechanisms of Tat secretion will be examined in a variety of biologically relevant cell types.
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Affiliation(s)
- Anthony R Mele
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Jamie Marino
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Kenneth Chen
- Department of Biology, University of the Sciences, Philadelphia, Pennsylvania
| | - Vanessa Pirrone
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Chris Janetopoulos
- Department of Biology, University of the Sciences, Philadelphia, Pennsylvania
| | - Brian Wigdahl
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Zachary Klase
- Department of Biology, University of the Sciences, Philadelphia, Pennsylvania
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
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Schatz M, Tong PBV, Beaumelle B. Unconventional secretion of viral proteins. Semin Cell Dev Biol 2018; 83:8-11. [PMID: 29571970 DOI: 10.1016/j.semcdb.2018.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 03/14/2018] [Accepted: 03/14/2018] [Indexed: 12/25/2022]
Abstract
Although largely less numerous and characterized than bacterial secreted effectors, several viral virulence factors are secreted by virus infected cells. However, their mode of secretion only starts to be studied at the molecular level. Several of these viral effectors are secreted using an unconventional secretion pathway, i.e. despite the lack of signal sequence. We here review recent results illustrating the diversity of these pathways. In the case of HIV-1 proteins Tat and matrix (p17) proteins, secretion directly takes place at the plasma membrane level following binding to PI(4,5)P2. The secretion of HTLV-I Tax was found to partly rely on exocytic pathway intermediates. The secretion pathways of VP22 of Herpes simplex virus type I and VP40 of the Ebola virus are less well characterized but VP40 can be recruited to the plasma membrane by PI(4,5)P2 that thus appears as a key partner enabling the unconventional secretion of many viral proteins. Several studies indicated that circulating retroviral transactivating proteins Tat and Tax are involved in the development of AIDS and HTLV-I associated myelopathy/tropical spastic paraparesis, respectively.
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Affiliation(s)
- Malvina Schatz
- IRIM, UMR9004 University of Montpellier-CNRS, 1919 Route de Mende, 34293, MONTPELLIER Cedex 05, France
| | - Phuoc Bao Viet Tong
- IRIM, UMR9004 University of Montpellier-CNRS, 1919 Route de Mende, 34293, MONTPELLIER Cedex 05, France
| | - Bruno Beaumelle
- IRIM, UMR9004 University of Montpellier-CNRS, 1919 Route de Mende, 34293, MONTPELLIER Cedex 05, France.
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35
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Chouaki Benmansour N, Ruminski K, Sartre AM, Phelipot MC, Salles A, Bergot E, Wu A, Chicanne G, Fallet M, Brustlein S, Billaudeau C, Formisano A, Mailfert S, Payrastre B, Marguet D, Brasselet S, Hamon Y, He HT. Phosphoinositides regulate the TCR/CD3 complex membrane dynamics and activation. Sci Rep 2018; 8:4966. [PMID: 29563576 PMCID: PMC5862878 DOI: 10.1038/s41598-018-23109-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/05/2018] [Indexed: 01/06/2023] Open
Abstract
Phosphoinositides (PIs) play important roles in numerous membrane-based cellular activities. However, their involvement in the mechanism of T cell receptor (TCR) signal transduction across the plasma membrane (PM) is poorly defined. Here, we investigate their role, and in particular that of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] in TCR PM dynamics and activity in a mouse T-cell hybridoma upon ectopic expression of a PM-localized inositol polyphosphate-5-phosphatase (Inp54p). We observed that dephosphorylation of PI(4,5)P2 by the phosphatase increased the TCR/CD3 complex PM lateral mobility prior stimulation. The constitutive and antigen-elicited CD3 phosphorylation as well as the antigen-stimulated early signaling pathways were all found to be significantly augmented in cells expressing the phosphatase. Using state-of-the-art biophotonic approaches, we further showed that PI(4,5)P2 dephosphorylation strongly promoted the CD3ε cytoplasmic domain unbinding from the PM inner leaflet in living cells, thus resulting in an increased CD3 availability for interactions with Lck kinase. This could significantly account for the observed effects of PI(4,5)P2 dephosphorylation on the CD3 phosphorylation. Our data thus suggest that PIs play a key role in the regulation of the TCR/CD3 complex dynamics and activation at the PM.
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Affiliation(s)
| | - Kilian Ruminski
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Anne-Marie Sartre
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Marie-Claire Phelipot
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Audrey Salles
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France.,UTechS Photonic BioImaging (Imagopole) Citech, Institut Pasteur, Paris, 75724, France
| | - Elise Bergot
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Ambroise Wu
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Gaëtan Chicanne
- Institut des Maladies Métaboliques et Cardiovasculaires, Inserm U1048, Université Toulouse 3, Toulouse, France
| | - Mathieu Fallet
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Sophie Brustlein
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Cyrille Billaudeau
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France.,Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Anthony Formisano
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Sébastien Mailfert
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Bernard Payrastre
- Institut des Maladies Métaboliques et Cardiovasculaires, Inserm U1048, Université Toulouse 3, Toulouse, France.,Laboratoire d'Hématologie, Centre Hospitalier Universitaire de Toulouse, Toulouse, France
| | - Didier Marguet
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France
| | - Sophie Brasselet
- Aix-Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13397, Marseille, France
| | - Yannick Hamon
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France.
| | - Hai-Tao He
- Aix Marseille Univ, CNRS, INSERM, CIML, Centre d'Immunologie de Marseille-Luminy, Marseille, France.
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36
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Steringer JP, Nickel W. A direct gateway into the extracellular space: Unconventional secretion of FGF2 through self-sustained plasma membrane pores. Semin Cell Dev Biol 2018; 83:3-7. [PMID: 29458182 DOI: 10.1016/j.semcdb.2018.02.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/01/2018] [Accepted: 02/08/2018] [Indexed: 10/17/2022]
Abstract
As illustrated by a diverse set of examples in this special issue, multiple mechanisms of protein secretion have been identified in eukaryotes that do not involve the endoplasmic reticulum (ER) and the Golgi apparatus. Here we focus on the type I pathway with Fibroblast Growth Factor 2 (FGF2) being the most prominent example. Unconventional secretion of FGF2 from cells is mediated by direct protein translocation across the plasma membrane. A unique feature of this process is the ability of FGF2 to form its own membrane translocation intermediate through oligomerization and membrane insertion. This process depends on the phosphoinositide PI(4,5)P2 at the inner leaflet and results in the formation of lipidic membrane pores in the plasma membrane. Various lines of evidence suggest that these pores are characterized by a toroidal architecture with FGF2 oligomers being accommodated in the center of these structures. At the outer leaflet of the plasma membrane, membrane proximal heparan sulfate proteoglycans are required for the final step of FGF2 translocation into the extracellular space. Based upon mutually exclusive interactions of FGF2 with PI(4,5)P2 versus heparan sulfates, an assembly/disassembly pathway has been proposed to be the underlying principle of directional transport of FGF2 across the plasma membrane. Thus, the core mechanism of unconventional secretion of FGF2 is based upon three discrete steps with (i) PI(4,5)P2 dependent oligomerization of FGF2 at the inner leaflet, (ii) insertion of membrane spanning FGF2 oligomers into the plasma membrane and (iii) disassembly at the outer leaflet mediated by heparan sulfates that subsequently retain FGF2 on cell surfaces. This process has recently been reconstituted with an inside-out membrane model system using giant unilamellar vesicles providing a compelling explanation of how FGF2 reaches the extracellular space in an ER/Golgi independent manner. This review is part of a Special Issue of SCDB on "unconventional protein secretion" edited by Walter Nickel and Catherine Rabouille.
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Affiliation(s)
- Julia P Steringer
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
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37
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Abstract
All eukaryotic cells secrete a range of proteins in a constitutive or regulated manner through the conventional or canonical exocytic/secretory pathway characterized by vesicular traffic from the endoplasmic reticulum, through the Golgi apparatus, and towards the plasma membrane. However, a number of proteins are secreted in an unconventional manner, which are insensitive to inhibitors of conventional exocytosis and use a route that bypasses the Golgi apparatus. These include cytosolic proteins such as fibroblast growth factor 2 (FGF2) and interleukin-1β (IL-1β), and membrane proteins that are known to also traverse to the plasma membrane by a conventional process of exocytosis, such as α integrin and the cystic fibrosis transmembrane conductor (CFTR). Mechanisms underlying unconventional protein secretion (UPS) are actively being analyzed and deciphered, and these range from an unusual form of plasma membrane translocation to vesicular processes involving the generation of exosomes and other extracellular microvesicles. In this chapter, we provide an overview on what is currently known about UPS in animal cells.
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Affiliation(s)
- Fanny Ng
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore, 117597, Singapore
| | - Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore, 117597, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore, 117456, Singapore.
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38
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He K, Marsland R, Upadhyayula S, Song E, Dang S, Capraro BR, Wang W, Skillern W, Gaudin R, Ma M, Kirchhausen T. Dynamics of phosphoinositide conversion in clathrin-mediated endocytic traffic. Nature 2017; 552:410-414. [PMID: 29236694 PMCID: PMC6263037 DOI: 10.1038/nature25146] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/13/2017] [Indexed: 12/22/2022]
Abstract
Vesicular carriers transport proteins and lipids from one organelle to another, recognizing specific identifiers for the donor and acceptor membranes. Two important identifiers are phosphoinositides and GTP-bound GTPases, which provide well-defined but mutable labels. Phosphatidylinositol and its phosphorylated derivatives are present on the cytosolic faces of most cellular membranes. Reversible phosphorylation of its headgroup produces seven distinct phosphoinositides. In endocytic traffic, phosphatidylinositol-4,5-biphosphate marks the plasma membrane, and phosphatidylinositol-3-phosphate and phosphatidylinositol-4-phosphate mark distinct endosomal compartments. It is unknown what sequence of changes in lipid content confers on the vesicles their distinct identity at each intermediate step. Here we describe 'coincidence-detecting' sensors that selectively report the phosphoinositide composition of clathrin-associated structures, and the use of these sensors to follow the dynamics of phosphoinositide conversion during endocytosis. The membrane of an assembling coated pit, in equilibrium with the surrounding plasma membrane, contains phosphatidylinositol-4,5-biphosphate and a smaller amount of phosphatidylinositol-4-phosphate. Closure of the vesicle interrupts free exchange with the plasma membrane. A substantial burst of phosphatidylinositol-4-phosphate immediately after budding coincides with a burst of phosphatidylinositol-3-phosphate, distinct from any later encounter with the phosphatidylinositol-3-phosphate pool in early endosomes; phosphatidylinositol-3,4-biphosphate and the GTPase Rab5 then appear and remain as the uncoating vesicles mature into Rab5-positive endocytic intermediates. Our observations show that a cascade of molecular conversions, made possible by the separation of a vesicle from its parent membrane, can label membrane-traffic intermediates and determine their destinations.
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Affiliation(s)
- Kangmin He
- Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Department of Pediatrics, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Robert Marsland
- Physics of Living Systems Group, Massachusetts Institute of Technology, 400 Technology Square, Cambridge, Massachusetts 02139, USA
| | - Srigokul Upadhyayula
- Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Department of Pediatrics, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Eli Song
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Song Dang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Benjamin R Capraro
- Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Weiming Wang
- Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Wesley Skillern
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Raphael Gaudin
- Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Minghe Ma
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
| | - Tom Kirchhausen
- Department of Cell Biology, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Ave, Boston, Massachusetts 02115, USA
- Department of Pediatrics, Harvard Medical School, 200 Longwood Ave, Boston, Massachusetts 02115, USA
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39
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Steringer JP, Nickel W. The molecular mechanism underlying unconventional secretion of Fibroblast Growth Factor 2 from tumour cells. Biol Cell 2017; 109:375-380. [PMID: 28799166 DOI: 10.1111/boc.201700036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/07/2017] [Accepted: 08/07/2017] [Indexed: 11/29/2022]
Abstract
Fibroblast Growth Factor 2 (FGF2) is a potent cell survival factor involved in tumour-induced angiogenesis. FGF2 is secreted from cells through an unconventional secretory mechanism based upon direct translocation across the plasma membrane. The molecular mechanism underlying this process depends on a surprisingly small set of trans-acting factors that are physically associated with the plasma membrane. FGF2 membrane translocation is mediated by the ability of FGF2 to oligomerise and to insert into the plasma membrane in a PI(4,5)P2 -dependent manner. Membrane-inserted FGF2 oligomers are dynamic translocation intermediates that are disassembled at the extracellular leaflet mediated by membrane proximal heparan sulphate proteoglycans. This process results in the exposure of FGF2 on cell surfaces as part of its unconventional mechanism of secretion. Although the trans-acting factors and cis-elements in FGF2 required for unconventional secretion have been known for a while, the core mechanism of this mysterious process has now been reconstituted with purified components establishing the molecular basis of FGF2 secretion from tumour cells.
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Affiliation(s)
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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40
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Brough D, Pelegrin P, Nickel W. An emerging case for membrane pore formation as a common mechanism for the unconventional secretion of FGF2 and IL-1β. J Cell Sci 2017; 130:3197-3202. [PMID: 28871048 DOI: 10.1242/jcs.204206] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/20/2017] [Indexed: 12/12/2022] Open
Abstract
Extracellular proteins with important signalling roles in processes, such as inflammation and angiogenesis, are known to employ unconventional routes of protein secretion. Although mechanisms of unconventional protein secretion are beginning to emerge, the precise molecular details have remained elusive for the majority of cargo proteins secreted by unconventional means. Recent findings suggest that for two examples of unconventionally secreted proteins, interleukin 1β (IL-1β) and fibroblast growth factor 2 (FGF2), the common molecular principle of pore formation may be shared. Under specific experimental conditions, secretion of IL-1β and FGF2 is triggered by phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]-dependent formation of pores across the plasma membrane. However, the underlying mechanisms are different, with FGF2 known to directly interact with PI(4,5)P2, whereas in the case of IL-1β secretion, it is proposed that the N-terminal fragment of gasdermin D interacts with PI(4,5)P2 to form the pore. Thus, although implemented in different ways, these findings suggest that pore formation may be shared by the unconventional secretion mechanisms for FGF2 and IL-1β in at least some cases. In this Opinion article, we discuss the unconventional mechanisms of FGF2 and IL-1β release with a particular emphasis on recent discoveries suggesting the importance of pore formation on the plasma membrane.
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Affiliation(s)
- David Brough
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PT, UK
| | - Pablo Pelegrin
- Grupo de Inflamación Molecular, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria-Arrixaca (IMIB-Arrixaca), 30120 Murcia, Spain
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
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41
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Steringer JP, Lange S, Čujová S, Šachl R, Poojari C, Lolicato F, Beutel O, Müller HM, Unger S, Coskun Ü, Honigmann A, Vattulainen I, Hof M, Freund C, Nickel W. Key steps in unconventional secretion of fibroblast growth factor 2 reconstituted with purified components. eLife 2017; 6. [PMID: 28722655 PMCID: PMC5601999 DOI: 10.7554/elife.28985] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/14/2017] [Indexed: 12/31/2022] Open
Abstract
FGF2 is secreted from cells by an unconventional secretory pathway. This process is mediated by direct translocation across the plasma membrane. Here, we define the minimal molecular machinery required for FGF2 membrane translocation in a fully reconstituted inside-out vesicle system. FGF2 membrane translocation is thermodynamically driven by PI(4,5)P2-induced membrane insertion of FGF2 oligomers. The latter serve as dynamic translocation intermediates of FGF2 with a subunit number in the range of 8-12 FGF2 molecules. Vectorial translocation of FGF2 across the membrane is governed by sequential and mutually exclusive interactions with PI(4,5)P2 and heparan sulfates on opposing sides of the membrane. Based on atomistic molecular dynamics simulations, we propose a mechanism that drives PI(4,5)P2 dependent oligomerization of FGF2. Our combined findings establish a novel type of self-sustained protein translocation across membranes revealing the molecular basis of the unconventional secretory pathway of FGF2. DOI:http://dx.doi.org/10.7554/eLife.28985.001
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Affiliation(s)
| | - Sascha Lange
- Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin, Germany
| | - Sabína Čujová
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Chetan Poojari
- Department of Physics, University of Helsinki, Helsinki, Finland.,Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Fabio Lolicato
- Department of Physics, University of Helsinki, Helsinki, Finland.,Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Oliver Beutel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Sebastian Unger
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Ünal Coskun
- Paul Langerhans Institute Dresden, Helmholtz Zentrum München, University Hospital and Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,Deutsches Zentrum fur Diabetesforschung, Neuherberg, Germany
| | - Alf Honigmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Ilpo Vattulainen
- Department of Physics, University of Helsinki, Helsinki, Finland.,Department of Physics, Tampere University of Technology, Tampere, Finland.,MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, Denmark, United Kingdom
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Christian Freund
- Institut für Chemie und Biochemie, Freie Universität Berlin, Berlin, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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42
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Vanova T, Konecna Z, Zbonakova Z, La Venuta G, Zoufalova K, Jelinkova S, Varecha M, Rotrekl V, Krejci P, Nickel W, Dvorak P, Kunova Bosakova M. Tyrosine Kinase Expressed in Hepatocellular Carcinoma, TEC, Controls Pluripotency and Early Cell Fate Decisions of Human Pluripotent Stem Cells via Regulation of Fibroblast Growth Factor-2 Secretion. Stem Cells 2017. [PMID: 28631381 DOI: 10.1002/stem.2660] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Human pluripotent stem cells (hPSC) require signaling provided by fibroblast growth factor (FGF) receptors. This can be initiated by the recombinant FGF2 ligand supplied exogenously, but hPSC further support their niche by secretion of endogenous FGF2. In this study, we describe a role of tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase in this process. We show that TEC-mediated FGF2 secretion is essential for hPSC self-renewal, and its lack mediates specific differentiation. Following both short hairpin RNA- and small interfering RNA-mediated TEC knockdown, hPSC secretes less FGF2. This impairs hPSC proliferation that can be rescued by increasing amounts of recombinant FGF2. TEC downregulation further leads to a lower expression of the pluripotency markers, an improved priming towards neuroectodermal lineage, and a failure to develop cardiac mesoderm. Our data thus demonstrate that TEC is yet another regulator of FGF2-mediated hPSC pluripotency and differentiation. Stem Cells 2017;35:2050-2059.
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Affiliation(s)
- Tereza Vanova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Zaneta Konecna
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Zuzana Zbonakova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | | | - Karolina Zoufalova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic
| | - Sarka Jelinkova
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Miroslav Varecha
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic
| | - Vladimir Rotrekl
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic
| | - Walter Nickel
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Petr Dvorak
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
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43
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Abstract
Besides its essential role in the activation of HIV-1 gene expression, the viral Tat protein has the unusual property of trafficking in and out of cells. In contrast to Tat internalization, the mechanism involved in extracellular Tat release has so far remained elusive. Here we show that Tat secretion occurs through a Golgi-independent pathway requiring binding of Tat with three short, non-consecutive intracytoplasmic loops at the C-terminus of the cellular Na+,K+-ATPase pump alpha subunit. Ouabain, a pump inhibitor, blocked this interaction and prevented Tat secretion; virions produced in the presence of this drug were less infectious, consistent the capacity of virion-associated Tat to increase HIV-1 infectivity. Treatment of CD4+ T-cells with short peptides corresponding to the Tat-binding regions of the pump alpha subunit impaired extracellular Tat release and blocked HIV-1 replication. Thus, non canonical, extracellular Tat secretion is essential for viral infectivity.
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44
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La Venuta G, Wegehingel S, Sehr P, Müller HM, Dimou E, Steringer JP, Grotwinkel M, Hentze N, Mayer MP, Will DW, Uhrig U, Lewis JD, Nickel W. Small Molecule Inhibitors Targeting Tec Kinase Block Unconventional Secretion of Fibroblast Growth Factor 2. J Biol Chem 2016; 291:17787-803. [PMID: 27382052 DOI: 10.1074/jbc.m116.729384] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Indexed: 11/06/2022] Open
Abstract
Fibroblast growth factor 2 (FGF2) is a potent mitogen promoting both tumor cell survival and tumor-induced angiogenesis. It is secreted by an unconventional secretory mechanism that is based upon direct translocation across the plasma membrane. Key steps of this process are (i) phosphoinositide-dependent membrane recruitment, (ii) FGF2 oligomerization and membrane pore formation, and (iii) extracellular trapping mediated by membrane-proximal heparan sulfate proteoglycans. Efficient secretion of FGF2 is supported by Tec kinase that stimulates membrane pore formation based upon tyrosine phosphorylation of FGF2. Here, we report the biochemical characterization of the direct interaction between FGF2 and Tec kinase as well as the identification of small molecules that inhibit (i) the interaction of FGF2 with Tec, (ii) tyrosine phosphorylation of FGF2 mediated by Tec in vitro and in a cellular context, and (iii) unconventional secretion of FGF2 from cells. We further demonstrate the specificity of these inhibitors for FGF2 because tyrosine phosphorylation of a different substrate of Tec is unaffected in their presence. Building on previous evidence using RNA interference, the identified compounds corroborate the role of Tec kinase in unconventional secretion of FGF2. In addition, they are valuable lead compounds with great potential for drug development aiming at the inhibition of FGF2-dependent tumor growth and metastasis.
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Affiliation(s)
- Giuseppe La Venuta
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Sabine Wegehingel
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Peter Sehr
- the European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany, and
| | - Hans-Michael Müller
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Eleni Dimou
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Julia P Steringer
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Mareike Grotwinkel
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
| | - Nikolai Hentze
- the Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Matthias P Mayer
- the Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - David W Will
- the European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany, and
| | - Ulrike Uhrig
- the European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany, and
| | - Joe D Lewis
- the European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany, and
| | - Walter Nickel
- From the Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany,
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45
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Martín-Sánchez F, Diamond C, Zeitler M, Gomez AI, Baroja-Mazo A, Bagnall J, Spiller D, White M, Daniels MJD, Mortellaro A, Peñalver M, Paszek P, Steringer JP, Nickel W, Brough D, Pelegrín P. Inflammasome-dependent IL-1β release depends upon membrane permeabilisation. Cell Death Differ 2016; 23:1219-31. [PMID: 26868913 PMCID: PMC4946890 DOI: 10.1038/cdd.2015.176] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 12/03/2015] [Accepted: 12/22/2015] [Indexed: 12/03/2022] Open
Abstract
Interleukin-1β (IL-1β) is a critical regulator of the inflammatory response. IL-1β is not secreted through the conventional ER–Golgi route of protein secretion, and to date its mechanism of release has been unknown. Crucially, its secretion depends upon the processing of a precursor form following the activation of the multimolecular inflammasome complex. Using a novel and reversible pharmacological inhibitor of the IL-1β release process, in combination with biochemical, biophysical, and real-time single-cell confocal microscopy with macrophage cells expressing Venus-labelled IL-1β, we have discovered that the secretion of IL-1β after inflammasome activation requires membrane permeabilisation, and occurs in parallel with the death of the secreting cell. Thus, in macrophages the release of IL-1β in response to inflammasome activation appears to be a secretory process independent of nonspecific leakage of proteins during cell death. The mechanism of membrane permeabilisation leading to IL-1β release is distinct from the unconventional secretory mechanism employed by its structural homologues fibroblast growth factor 2 (FGF2) or IL-1α, a process that involves the formation of membrane pores but does not result in cell death. These discoveries reveal key processes at the initiation of an inflammatory response and deliver new insights into the mechanisms of protein release.
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Affiliation(s)
- F Martín-Sánchez
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain
| | - C Diamond
- Faculty of Life Sciences, University of Manchester, Manchester, UK.,Singapore Immunology Network (SIgN), Agency for Science Technology and Research (A*STAR), Singapore
| | - M Zeitler
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - A I Gomez
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain
| | - A Baroja-Mazo
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain
| | - J Bagnall
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - D Spiller
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - M White
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - M J D Daniels
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - A Mortellaro
- Singapore Immunology Network (SIgN), Agency for Science Technology and Research (A*STAR), Singapore
| | - M Peñalver
- Probelte Biotechnology, S.L., Murcia, Spain
| | - P Paszek
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - J P Steringer
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - W Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - D Brough
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - P Pelegrín
- Grupo de Inflamación Molecular, Centro de Investigación Biomédica en Red en el Área Temática de Enfermedades Hepáticas y Digestivas, Hospital Clínico Universitario Virgen de la Arrixaca, Instituto Murciano de Investigación Biosanitaria (IMIB-Arrixaca), Murcia, Spain.,Faculty of Life Sciences, University of Manchester, Manchester, UK
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46
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Abstract
Unconventional protein secretion (UPS) describes secretion pathways that bypass one or several of the canonical secretion pit-stops on the way to the plasma membrane, and/or involve the secretion of leaderless proteins. So far, alternatives to conventional secretion were primarily observed and studied in yeast and animal cells. The sessile lifestyle of plants brings with it unique restraints on how they adapt to adverse conditions and environmental challenges. Recently, attention towards unconventional secretion pathways in plant cells has substantially increased, with the large number of leaderless proteins identified through proteomic studies. While UPS pathways in plants are certainly not yet exhaustively researched, an emerging notion is that induction of UPS pathways is correlated with pathogenesis and stress responses. Given the multitude UPS events observed, comprehensively organizing the routes proteins take to the apoplast in defined UPS categories is challenging. With the establishment of a larger collection of studied plant proteins taking these UPS pathways, a clearer picture of endomembrane trafficking as a whole will emerge. There are several novel enabling technologies, such as vesicle proteomics and chemical genomics, with great potential for dissecting secretion pathways, providing information about the cargo that travels along them and the conditions that induce them.
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Affiliation(s)
- Destiny J Davis
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Byung-Ho Kang
- Center for Organelle Biogenesis and Function, School of Life Sciences, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Angelo S Heringer
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA
| | - Thomas E Wilkop
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA.
| | - Georgia Drakakaki
- Department of Plant Sciences, University of California, Asmundson Hall, One Shields Avenue, Davis, CA, 95616, USA.
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47
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La Venuta G, Zeitler M, Steringer JP, Müller HM, Nickel W. The Startling Properties of Fibroblast Growth Factor 2: How to Exit Mammalian Cells without a Signal Peptide at Hand. J Biol Chem 2015; 290:27015-27020. [PMID: 26416892 DOI: 10.1074/jbc.r115.689257] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For a long time, protein transport into the extracellular space was believed to strictly depend on signal peptide-mediated translocation into the lumen of the endoplasmic reticulum. More recently, this view has been challenged, and the molecular mechanisms of unconventional secretory processes are beginning to emerge. Here, we focus on unconventional secretion of fibroblast growth factor 2 (FGF2), a secretory mechanism that is based upon direct protein translocation across plasma membranes. Through a combination of genome-wide RNAi screening approaches and biochemical reconstitution experiments, the basic machinery of FGF2 secretion was identified and validated. This includes the integral membrane protein ATP1A1, the phosphoinositide phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2), and Tec kinase, as well as membrane-proximal heparan sulfate proteoglycans on cell surfaces. Hallmarks of unconventional secretion of FGF2 are: (i) sequential molecular interactions with the inner leaflet along with Tec kinase-dependent tyrosine phosphorylation of FGF2, (ii) PI(4,5)P2-dependent oligomerization and membrane pore formation, and (iii) extracellular trapping of FGF2 mediated by heparan sulfate proteoglycans on cell surfaces. Here, we discuss new developments regarding this process including the mechanism of FGF2 oligomerization during membrane pore formation, the functional role of ATP1A1 in FGF2 secretion, and the possibility that other proteins secreted by unconventional means make use of a similar mechanism to reach the extracellular space. Furthermore, given the prominent role of extracellular FGF2 in tumor-induced angiogenesis, we will discuss possibilities to develop highly specific inhibitors of FGF2 secretion, a novel approach that may yield lead compounds with a high potential to develop into anti-cancer drugs.
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Affiliation(s)
| | - Marcel Zeitler
- Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Julia P Steringer
- Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | | | - Walter Nickel
- Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany.
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Zeitler M, Steringer JP, Müller HM, Mayer MP, Nickel W. HIV-Tat Protein Forms Phosphoinositide-dependent Membrane Pores Implicated in Unconventional Protein Secretion. J Biol Chem 2015; 290:21976-84. [PMID: 26183781 DOI: 10.1074/jbc.m115.667097] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 12/20/2022] Open
Abstract
HIV-Tat has been demonstrated to be secreted from cells in a phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2)-dependent manner. Here we show that HIV-Tat forms membrane-inserted oligomers, a process that is accompanied by changes in secondary structure with a strong increase in antiparallel β sheet content. Intriguingly, oligomerization of HIV-Tat on membrane surfaces leads to the formation of membrane pores, as demonstrated by physical membrane passage of small fluorescent tracer molecules. Although membrane binding of HIV-Tat did not strictly depend on PI(4,5)P2 but, rather, was mediated by a range of acidic membrane lipids, a functional interaction between PI(4,5)P2 and HIV-Tat was critically required for efficient membrane pore formation by HIV-Tat oligomers. These properties are strikingly similar to what has been reported previously for fibroblast growth factor 2 (FGF2), providing strong evidence of a common core mechanism of unconventional secretion shared by HIV-Tat and fibroblast growth factor 2.
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Affiliation(s)
- Marcel Zeitler
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Julia P Steringer
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Hans-Michael Müller
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
| | - Matthias P Mayer
- the Zentrum für Molekulare Biologie der Universität Heidelberg, Deutsches Krebsforschungszentrum-Zentrum für Molekulare Biologie der Universität Heidelberg Allianz, 69120 Heidelberg, Germany
| | - Walter Nickel
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany and
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Förthmann B, Grothe C, Claus P. A nuclear odyssey: fibroblast growth factor-2 (FGF-2) as a regulator of nuclear homeostasis in the nervous system. Cell Mol Life Sci 2015; 72:1651-62. [PMID: 25552245 PMCID: PMC11113852 DOI: 10.1007/s00018-014-1818-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/10/2014] [Accepted: 12/19/2014] [Indexed: 01/07/2023]
Abstract
Nuclear localization of classical growth factors is a well-known phenomenon but still remains a molecular and cellular conundrum. Fibroblast growth factor-2 (FGF-2) is an excellent example of a protein which functions as an extracellular molecule involved in canonical receptor tyrosine kinase signaling as well as displaying intracellular functions. Paracrine and nuclear functions are two important sides of the same protein. FGF-2 is expressed in isoforms with different molecular weights from one mRNA species. In rodents, all of these isoforms become imported to the nucleus. In this review, we discuss structural and functional aspects of FGF-2 isoforms in the nervous system. The nuclear odyssey of FGF-2 is reflected by nuclear dynamics, localization to nuclear bodies such as nucleoli, binding to chromatin and engagement in various protein interactions. Recently discovered molecular partnerships of the isoforms shed light on their nuclear functions, thereby greatly extending our knowledge of the multifaceted functions of FGF-2.
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Affiliation(s)
- Benjamin Förthmann
- Department of Neuroanatomy, Institute of Neuroanatomy, Hannover Medical School, OE 4140, Carl-Neuberg-Str.1, 30625 Hannover, Germany
| | - Claudia Grothe
- Department of Neuroanatomy, Institute of Neuroanatomy, Hannover Medical School, OE 4140, Carl-Neuberg-Str.1, 30625 Hannover, Germany
- Center for Systems Neuroscience, 30625 Hannover, Germany
| | - Peter Claus
- Department of Neuroanatomy, Institute of Neuroanatomy, Hannover Medical School, OE 4140, Carl-Neuberg-Str.1, 30625 Hannover, Germany
- Center for Systems Neuroscience, 30625 Hannover, Germany
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50
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Müller HM, Steringer JP, Wegehingel S, Bleicken S, Münster M, Dimou E, Unger S, Weidmann G, Andreas H, García-Sáez AJ, Wild K, Sinning I, Nickel W. Formation of disulfide bridges drives oligomerization, membrane pore formation, and translocation of fibroblast growth factor 2 to cell surfaces. J Biol Chem 2015; 290:8925-37. [PMID: 25694424 DOI: 10.1074/jbc.m114.622456] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Indexed: 11/06/2022] Open
Abstract
Fibroblast growth factor 2 (FGF2) is a key signaling molecule in tumor-induced angiogenesis. FGF2 is secreted by an unconventional secretory mechanism that involves phosphatidylinositol 4,5-bisphosphate-dependent insertion of FGF2 oligomers into the plasma membrane. This process is regulated by Tec kinase-mediated tyrosine phosphorylation of FGF2. Molecular interactions driving FGF2 monomers into membrane-inserted FGF2 oligomers are unknown. Here we identify two surface cysteines that are critical for efficient unconventional secretion of FGF2. They represent unique features of FGF2 as they are absent from all signal-peptide-containing members of the FGF protein family. We show that phosphatidylinositol 4,5-bisphosphate-dependent FGF2 oligomerization concomitant with the generation of membrane pores depends on FGF2 surface cysteines as either chemical alkylation or substitution with alanines impairs these processes. We further demonstrate that the FGF2 variant forms lacking the two surface cysteines are not secreted from cells. These findings were corroborated by experiments redirecting a signal-peptide-containing FGF family member from the endoplasmic reticulum/Golgi-dependent secretory pathway into the unconventional secretory pathway of FGF2. Cis elements known to be required for unconventional secretion of FGF2, including the two surface cysteines, were transplanted into a variant form of FGF4 without signal peptide. The resulting FGF4/2 hybrid protein was secreted by unconventional means. We propose that the formation of disulfide bridges drives membrane insertion of FGF2 oligomers as intermediates in unconventional secretion of FGF2.
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Affiliation(s)
- Hans-Michael Müller
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Julia P Steringer
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Sabine Wegehingel
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Stephanie Bleicken
- Interfaculty Institute for Biochemistry, University of Tübingen, 72076 Tübingen, Germany, and Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Maximilian Münster
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Eleni Dimou
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Sebastian Unger
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Georg Weidmann
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Helena Andreas
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Ana J García-Sáez
- Interfaculty Institute for Biochemistry, University of Tübingen, 72076 Tübingen, Germany, and Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Klemens Wild
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Irmgard Sinning
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany
| | - Walter Nickel
- From the Heidelberg University Biochemistry Center, 69120 Heidelberg, Germany,
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