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An YJ, Jung YE, Lee KW, Kaushal P, Ko IY, Shin SM, Ji S, Yu W, Lee C, Lee WK, Cha K, Lee JH, Cha SS, Yim HS. Structural and biochemical investigation into stable FGF2 mutants with novel mutation sites and hydrophobic replacements for surface-exposed cysteines. PLoS One 2024; 19:e0307499. [PMID: 39236042 PMCID: PMC11376533 DOI: 10.1371/journal.pone.0307499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 07/06/2024] [Indexed: 09/07/2024] Open
Abstract
Fibroblast growth factor 2 (FGF2) is an attractive biomaterial for pharmaceuticals and functional cosmetics. To improve the thermo-stability of FGF2, we designed two mutants harboring four-point mutations: FGF2-M1 (D28E/C78L/C96I/S137P) and FGF2-M2 (D28E/C78I/C96I/S137P) through bioinformatics, molecular thermodynamics, and molecular modeling. The D28E mutation reduced fragmentation of the FGF2 wild type during preparation, and the substitution of a whale-specific amino acid, S137P, enhanced the thermal stability of FGF2. Surface-exposed cysteines that participate in oligomerization through intermolecular disulfide bond formation were substituted with hydrophobic residues (C78L/C78I and C96I) using the in silico method. High-resolution crystal structures revealed at the atomic level that the introduction of mutations stabilizes each local region by forming more favorable interactions with neighboring residues. In particular, P137 forms CH-π interactions with the side chain indole ring of W123, which seems to stabilize a β-hairpin structure, containing a heparin-binding site of FGF2. Compared to the wild type, both FGF2-M1 and FGF2-M2 maintained greater solubility after a week at 45 °C, with their Tm values rising by ~ 5 °C. Furthermore, the duration for FGF2-M1 and FGF2-M2 to reach 50% residual activity at 45 °C extended to 8.8- and 8.2-fold longer, respectively, than that of the wild type. Interestingly, the hydrophobic substitution of surface-exposed cysteine in both FGF2 mutants makes them more resistant to proteolytic cleavage by trypsin, subtilisin, proteinase K, and actinase than the wild type and the Cys → Ser substitution. The hydrophobic replacements can influence protease resistance as well as oligomerization and thermal stability. It is notable that hydrophobic substitutions of surface-exposed cysteines, as well as D28E and S137P of the FGF2 mutants, were designed through various approaches with structural implications. Therefore, the engineering strategies and structural insights adopted in this study could be applied to improve the stability of other proteins.
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Affiliation(s)
- Young Jun An
- Marine Biotechnology & Bioresource Research Department, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea
| | - Ye-Eun Jung
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul, Republic of Korea
| | - Kyeong Won Lee
- Marine Biotechnology & Bioresource Research Department, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea
| | - Prashant Kaushal
- Chemical & Biological Integrative Research Center, Korea Institute of Science and Technology, Seoul, Republic Korea
| | - In Young Ko
- New Drug Development Center, Osong Medical Innovation Foundation, Cheongiu, Republic of Korea
| | - Seung Min Shin
- Marine Biotechnology & Bioresource Research Department, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea
| | - Sangho Ji
- Department of Brain Sciences, DGIST, Daegu, Republic of Korea
| | - Wookyung Yu
- Department of Brain Sciences, DGIST, Daegu, Republic of Korea
| | - Cheolju Lee
- Chemical & Biological Integrative Research Center, Korea Institute of Science and Technology, Seoul, Republic Korea
| | - Won-Kyu Lee
- New Drug Development Center, Osong Medical Innovation Foundation, Cheongiu, Republic of Korea
| | - Kiweon Cha
- New Drug Development Center, Osong Medical Innovation Foundation, Cheongiu, Republic of Korea
| | - Jung-Hyun Lee
- Marine Biotechnology & Bioresource Research Department, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea
| | - Sun-Shin Cha
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul, Republic of Korea
| | - Hyung-Soon Yim
- Marine Biotechnology & Bioresource Research Department, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea
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2
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Nickle A, Ko S, Merrill AE. Fibroblast growth factor 2. Differentiation 2024; 139:100733. [PMID: 37858405 PMCID: PMC11009566 DOI: 10.1016/j.diff.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/20/2023] [Accepted: 10/05/2023] [Indexed: 10/21/2023]
Abstract
Fibroblast Growth Factor 2 (FGF2), also known as basic fibroblast growth factor, is a potent stimulator of growth and differentiation in multiple tissues. Its discovery traces back over 50 years ago when it was first isolated from bovine pituitary extracts due to its ability to stimulate fibroblast proliferation. Subsequent studies investigating the genomic structure of FGF2 identified multiple protein isoforms, categorized as the low molecular weight and high molecular weight FGF2. These isoforms arise from alternative translation initiation events and exhibit unique molecular and cellular functions. In this concise review, we aim to provide an overview of what is currently known about the structure, expression, and functions of the FGF2 isoforms within the contexts of development, homeostasis, and disease.
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Affiliation(s)
- Audrey Nickle
- Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, 90033, USA; Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Sebastian Ko
- Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, 90033, USA; Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Amy E Merrill
- Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, 90033, USA; Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
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3
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Biadun M, Sochacka M, Kalka M, Chorazewska A, Karelus R, Krowarsch D, Opalinski L, Zakrzewska M. Uncovering key steps in FGF12 cellular release reveals a common mechanism for unconventional FGF protein secretion. Cell Mol Life Sci 2024; 81:356. [PMID: 39158730 PMCID: PMC11335280 DOI: 10.1007/s00018-024-05396-9] [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] [Received: 06/11/2024] [Revised: 08/03/2024] [Accepted: 08/04/2024] [Indexed: 08/20/2024]
Abstract
FGF12 belongs to a subfamily of FGF proteins called FGF homologous factors (FHFs), which until recently were thought to be non-signaling intracellular proteins. Our recent studies have shown that although they lack a conventional signal peptide for secretion, they can reach the extracellular space, especially under stress conditions. Here, we unraveled that the long "a" isoform of FGF12 is secreted in a pathway involving the A1 subunit of Na(+)/K(+) ATPase (ATP1A1), Tec kinase and lipids such as phosphatidylinositol and phosphatidylserine. Further, we showed that the short "b" isoform of FGF12, which binds ATP1A1 and phosphatidylserine less efficiently, is not secreted from cells. We also indicated regions in the FGF12a protein sequence that are crucial for its secretion, including N-terminal fragment and specific residues, and proposed that liquid-liquid phase separation may be important in this process. Our results strongly suggest that the mechanism of this process is very similar for all unconventionally secreted FGF proteins.
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Affiliation(s)
- Martyna Biadun
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Martyna Sochacka
- Department of Protein Biotechnology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Marta Kalka
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Aleksandra Chorazewska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Radoslaw Karelus
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Daniel Krowarsch
- Department of Protein Biotechnology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Lukasz Opalinski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland
| | - Malgorzata Zakrzewska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, 50-383, Poland.
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4
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Percio A, Cicchinelli M, Masci D, Summo M, Urbani A, Greco V. Oxidative Cysteine Post Translational Modifications Drive the Redox Code Underlying Neurodegeneration and Amyotrophic Lateral Sclerosis. Antioxidants (Basel) 2024; 13:883. [PMID: 39199129 PMCID: PMC11351139 DOI: 10.3390/antiox13080883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2024] [Revised: 07/17/2024] [Accepted: 07/19/2024] [Indexed: 09/01/2024] Open
Abstract
Redox dysregulation, an imbalance between oxidants and antioxidants, is crucial in the pathogenesis of various neurodegenerative diseases. Within this context, the "redoxome" encompasses the network of redox molecules collaborating to maintain cellular redox balance and signaling. Among these, cysteine-sensitive proteins are fundamental for this homeostasis. Due to their reactive thiol groups, cysteine (Cys) residues are particularly susceptible to oxidative post-translational modifications (PTMs) induced by free radicals (reactive oxygen, nitrogen, and sulfur species) which profoundly affect protein functions. Cys-PTMs, forming what is referred to as "cysteinet" in the redox proteome, are essential for redox signaling in both physiological and pathological conditions, including neurodegeneration. Such modifications significantly influence protein misfolding and aggregation, key hallmarks of neurodegenerative diseases such as Alzheimer's, Parkinson's, and notably, amyotrophic lateral sclerosis (ALS). This review aims to explore the complex landscape of cysteine PTMs in the cellular redox environment, elucidating their impact on neurodegeneration at protein level. By investigating specific cysteine-sensitive proteins and the regulatory networks involved, particular emphasis is placed on the link between redox dysregulation and ALS, highlighting this pathology as a prime example of a neurodegenerative disease wherein such redox dysregulation is a distinct hallmark.
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Affiliation(s)
- Anna Percio
- Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (A.P.); (M.C.); (D.M.); (M.S.); (A.U.)
- Department of Laboratory Diagnostic and Infectious Diseases, Unity of Chemistry, Biochemistry and Clinical Molecular Biology, Fondazione Policlinico Universitario Agostino Gemelli-IRCCS, 00168 Rome, Italy
| | - Michela Cicchinelli
- Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (A.P.); (M.C.); (D.M.); (M.S.); (A.U.)
- Department of Laboratory Diagnostic and Infectious Diseases, Unity of Chemistry, Biochemistry and Clinical Molecular Biology, Fondazione Policlinico Universitario Agostino Gemelli-IRCCS, 00168 Rome, Italy
| | - Domiziana Masci
- Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (A.P.); (M.C.); (D.M.); (M.S.); (A.U.)
| | - Mariagrazia Summo
- Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (A.P.); (M.C.); (D.M.); (M.S.); (A.U.)
| | - Andrea Urbani
- Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (A.P.); (M.C.); (D.M.); (M.S.); (A.U.)
- Department of Laboratory Diagnostic and Infectious Diseases, Unity of Chemistry, Biochemistry and Clinical Molecular Biology, Fondazione Policlinico Universitario Agostino Gemelli-IRCCS, 00168 Rome, Italy
| | - Viviana Greco
- Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Università Cattolica del Sacro Cuore, 00168 Rome, Italy; (A.P.); (M.C.); (D.M.); (M.S.); (A.U.)
- Department of Laboratory Diagnostic and Infectious Diseases, Unity of Chemistry, Biochemistry and Clinical Molecular Biology, Fondazione Policlinico Universitario Agostino Gemelli-IRCCS, 00168 Rome, Italy
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5
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Müller C, Budnik N, Mirkin FG, Vater CF, Bravo-Almonacid FF, Perez-Castro C, Wirth SA, Segretin ME. Production of biologically active human basic fibroblast growth factor (hFGFb) using Nicotiana tabacum transplastomic plants. PLANTA 2024; 260:28. [PMID: 38878167 DOI: 10.1007/s00425-024-04456-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Accepted: 06/02/2024] [Indexed: 06/29/2024]
Abstract
MAIN CONCLUSION We generated transplastomic tobacco lines that stably express a human Basic Fibroblast Growth Factor (hFGFb) in their chloroplasts stroma and purified a biologically active recombinant hFGFb. MAIN: The use of plants as biofactories presents as an attractive technology with the potential to efficiently produce high-value human recombinant proteins in a cost-effective manner. Plastid genome transformation stands out for its possibility to accumulate recombinant proteins at elevated levels. Of particular interest are recombinant growth factors, given their applications in animal cell culture and regenerative medicine. In this study, we produced recombinant human Fibroblast Growth Factor (rhFGFb), a crucial protein required for animal cell culture, in tobacco chloroplasts. We successfully generated two independent transplastomic lines that are homoplasmic and accumulate rhFGFb in their leaves. Furthermore, the produced rhFGFb demonstrated its biological activity by inducing proliferation in HEK293T cell lines. These results collectively underscore plastid genome transformation as a promising plant-based bioreactor for rhFGFb production.
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Affiliation(s)
- Carolina Müller
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, Ciudad Autónoma Buenos Aires, C1428ADN, Argentina
| | - Nicolás Budnik
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA-CONICET)- Partner Institute of the Max Planck Society, Godoy Cruz 2390, Ciudad Autónoma Buenos Aires, C1425FQ, Argentina
| | - Federico Gabriel Mirkin
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, Ciudad Autónoma Buenos Aires, C1428ADN, Argentina
| | - Catalina Francisca Vater
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, Ciudad Autónoma Buenos Aires, C1428ADN, Argentina
| | - Fernando Félix Bravo-Almonacid
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, Ciudad Autónoma Buenos Aires, C1428ADN, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, Bernal, Buenos Aires, B1876BXD, Argentina
| | - Carolina Perez-Castro
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA-CONICET)- Partner Institute of the Max Planck Society, Godoy Cruz 2390, Ciudad Autónoma Buenos Aires, C1425FQ, Argentina
| | - Sonia Alejandra Wirth
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA-CONICET-UBA), Intendente Güiraldes 2160, Ciudad Autónoma Buenos Aires, C1428EGA, Argentina
- Laboratorio de Agrobiotecnología, Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Autónoma Buenos Aires, C1428EGA, Argentina
| | - María Eugenia Segretin
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI-CONICET), Vuelta de Obligado 2490, Ciudad Autónoma Buenos Aires, C1428ADN, Argentina.
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Autónoma Buenos Aires, C1428EGA, Argentina.
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6
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Lolicato F, Nickel W, Haucke V, Ebner M. Phosphoinositide switches in cell physiology - From molecular mechanisms to disease. J Biol Chem 2024; 300:105757. [PMID: 38364889 PMCID: PMC10944118 DOI: 10.1016/j.jbc.2024.105757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/02/2024] [Accepted: 02/08/2024] [Indexed: 02/18/2024] Open
Abstract
Phosphoinositides are amphipathic lipid molecules derived from phosphatidylinositol that represent low abundance components of biological membranes. Rather than serving as mere structural elements of lipid bilayers, they represent molecular switches for a broad range of biological processes, including cell signaling, membrane dynamics and remodeling, and many other functions. Here, we focus on the molecular mechanisms that turn phosphoinositides into molecular switches and how the dysregulation of these processes can lead to disease.
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Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany; Department of Physics, University of Helsinki, Helsinki, Finland.
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Department of Biology, Chemistry, Pharmacy, Freie Universität Berlin, Berlin, Germany; Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael Ebner
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.
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7
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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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8
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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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9
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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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10
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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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11
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Ornitz DM, Itoh N. New developments in the biology of fibroblast growth factors. WIREs Mech Dis 2022; 14:e1549. [PMID: 35142107 PMCID: PMC10115509 DOI: 10.1002/wsbm.1549] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 01/28/2023]
Abstract
The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.
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Affiliation(s)
- David M Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nobuyuki Itoh
- Kyoto University Graduate School of Pharmaceutical Sciences, Sakyo, Kyoto, Japan
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12
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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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13
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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] [Key Words] [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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Affiliation(s)
- Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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14
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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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15
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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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16
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Membrane interaction and disulphide-bridge formation in the unconventional secretion of Tau. Biosci Rep 2021; 41:229358. [PMID: 34308969 PMCID: PMC8350431 DOI: 10.1042/bsr20210148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 07/04/2021] [Accepted: 07/21/2021] [Indexed: 11/17/2022] Open
Abstract
Misfolded, pathological tau protein propagates from cell to cell causing neuronal degeneration in Alzheimer's disease and other tauopathies. The molecular mechanisms of this process have remained elusive. Unconventional secretion of tau takes place via several different routes, including direct penetration through the plasma membrane. Here, we show that tau secretion requires membrane interaction via disulphide bridge formation. Mutating residues that reduce tau interaction with membranes or formation of disulphide bridges decrease both tau secretion from cells, and penetration through artificial lipid membranes. Our results demonstrate that tau is indeed able to penetrate protein-free membranes in a process independent of active cellular processes and that both membrane interaction and disulphide bridge formation are needed for this process. QUARK-based de novo modelling of the second and third microtubule-binding repeat domains (MTBDs), in which the two cysteine residues of 4R isoforms of tau are located, supports the concept that this region of tau could form transient amphipathic helices for membrane interaction.
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17
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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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18
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Ferguson HR, Smith MP, Francavilla C. Fibroblast Growth Factor Receptors (FGFRs) and Noncanonical Partners in Cancer Signaling. Cells 2021; 10:1201. [PMID: 34068954 PMCID: PMC8156822 DOI: 10.3390/cells10051201] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/06/2021] [Accepted: 05/09/2021] [Indexed: 02/07/2023] Open
Abstract
Increasing evidence indicates that success of targeted therapies in the treatment of cancer is context-dependent and is influenced by a complex crosstalk between signaling pathways and between cell types in the tumor. The Fibroblast Growth Factor (FGF)/FGF receptor (FGFR) signaling axis highlights the importance of such context-dependent signaling in cancer. Aberrant FGFR signaling has been characterized in almost all cancer types, most commonly non-small cell lung cancer (NSCLC), breast cancer, glioblastoma, prostate cancer and gastrointestinal cancer. This occurs primarily through amplification and over-expression of FGFR1 and FGFR2 resulting in ligand-independent activation. Mutations and translocations of FGFR1-4 are also identified in cancer. Canonical FGF-FGFR signaling is tightly regulated by ligand-receptor combinations as well as direct interactions with the FGFR coreceptors heparan sulfate proteoglycans (HSPGs) and Klotho. Noncanonical FGFR signaling partners have been implicated in differential regulation of FGFR signaling. FGFR directly interacts with cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins, contributing to invasive and migratory properties of cancer cells, whereas interactions with other receptor tyrosine kinases (RTKs) regulate angiogenic, resistance to therapy, and metastatic potential of cancer cells. The diversity in FGFR signaling partners supports a role for FGFR signaling in cancer, independent of genetic aberration.
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Affiliation(s)
- Harriet R. Ferguson
- Division of Molecular and Cellular Function, School of Biological Science, Faculty of Biology Medicine and Health (FBMH), The University of Manchester, Manchester M13 9PT, UK;
| | - Michael P. Smith
- Division of Molecular and Cellular Function, School of Biological Science, Faculty of Biology Medicine and Health (FBMH), The University of Manchester, Manchester M13 9PT, UK;
| | - Chiara Francavilla
- Division of Molecular and Cellular Function, School of Biological Science, Faculty of Biology Medicine and Health (FBMH), The University of Manchester, Manchester M13 9PT, UK;
- Manchester Breast Centre, Manchester Cancer Research Centre, The University of Manchester, Manchester M20 4GJ, UK
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19
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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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20
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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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21
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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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22
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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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23
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The Mechanical Power of Titin Folding. Cell Rep 2020; 27:1836-1847.e4. [PMID: 31067467 PMCID: PMC6937205 DOI: 10.1016/j.celrep.2019.04.046] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/09/2019] [Accepted: 04/09/2019] [Indexed: 11/21/2022] Open
Abstract
The delivery of mechanical power, a crucial component of animal motion, is constrained by the universal compromise between the force and the velocity of its constituent molecular systems. While the mechanisms of force generation have been studied at the single molecular motor level, there is little understanding of the magnitude of power that can be generated by folding proteins. Here, we use single-molecule force spectroscopy techniques to measure the force-velocity relation of folding titin domains that contain single internal disulfide bonds, a common feature throughout the titin I-band. We find that formation of the disulfide regulates the peak power output of protein folding in an all-or-none manner, providing at 6.0 pN, for example, a boost from 0 to 6,000 zW upon oxidation. This mechanism of power generation from protein folding is of great importance for muscle, where titin domains may unfold and refold with each extension and contraction of the sarcomere. Eckels et al. use single-molecule magnetic tweezers to simultaneously probe the folding dynamics of titin Ig domains and monitor the redox status of single disulfides within the Ig fold. Oxidation of the disulfide bond greatly increases both the folding force and the magnitude of power delivered by protein folding.
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24
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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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25
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Brunello CA, Merezhko M, Uronen RL, Huttunen HJ. Mechanisms of secretion and spreading of pathological tau protein. Cell Mol Life Sci 2020; 77:1721-1744. [PMID: 31667556 PMCID: PMC7190606 DOI: 10.1007/s00018-019-03349-1] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/10/2019] [Accepted: 10/16/2019] [Indexed: 12/12/2022]
Abstract
Accumulation of misfolded and aggregated forms of tau protein in the brain is a neuropathological hallmark of tauopathies, such as Alzheimer's disease and frontotemporal lobar degeneration. Tau aggregates have the ability to transfer from one cell to another and to induce templated misfolding and aggregation of healthy tau molecules in previously healthy cells, thereby propagating tau pathology across different brain areas in a prion-like manner. The molecular mechanisms involved in cell-to-cell transfer of tau aggregates are diverse, not mutually exclusive and only partially understood. Intracellular accumulation of misfolded tau induces several mechanisms that aim to reduce the cellular burden of aggregated proteins and also promote secretion of tau aggregates. However, tau may also be released from cells physiologically unrelated to protein aggregation. Tau secretion involves multiple vesicular and non-vesicle-mediated pathways, including secretion directly through the plasma membrane. Consequently, extracellular tau can be found in various forms, both as a free protein and in vesicles, such as exosomes and ectosomes. Once in the extracellular space, tau aggregates can be internalized by neighboring cells, both neurons and glial cells, via endocytic, pinocytic and phagocytic mechanisms. Importantly, accumulating evidence suggests that prion-like propagation of misfolding protein pathology could provide a general mechanism for disease progression in tauopathies and other related neurodegenerative diseases. Here, we review the recent literature on cellular mechanisms involved in cell-to-cell transfer of tau, with a particular focus in tau secretion.
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Affiliation(s)
- Cecilia A Brunello
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland
| | - Maria Merezhko
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland
| | - Riikka-Liisa Uronen
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland
| | - Henri J Huttunen
- Neuroscience Center, HiLIFE, University of Helsinki, P.O. Box 63, Haartmaninkatu 8, 00014, Helsinki, Finland.
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26
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Eguchi R, Wakabayashi I. HDGF enhances VEGF‑dependent angiogenesis and FGF‑2 is a VEGF‑independent angiogenic factor in non‑small cell lung cancer. Oncol Rep 2020; 44:14-28. [PMID: 32319650 PMCID: PMC7251661 DOI: 10.3892/or.2020.7580] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 03/04/2020] [Indexed: 12/12/2022] Open
Abstract
Non-small cell lung cancer (NSCLC) accounts for over 80% of all diagnosed lung cancer cases. Lung cancer is the leading cause of cancer-related deaths worldwide. Most NSCLC cells overexpress vascular endothelial growth factor-A (VEGF-A) which plays a pivotal role in tumour angiogenesis. Anti-angiogenic therapies including VEGF-A neutralisation have significantly improved the response rates, progression-free survival and overall survival of patients with NSCLC. However, the median survival of these patients is shorter than 18 months, suggesting that NSCLC cells secrete VEGF-independent angiogenic factors, which remain unknown. We aimed to explore these factors in human NSCLC cell lines, A549, Lu99 and EBC-1 using serum-free culture, to which only EBC-1 cells could adapt. By mass spectrometry, we identified 1,007 proteins in the culture supernatant derived from EBC-1 cells. Among the identified proteins, interleukin-8 (IL-8), macrophage migration inhibitory factor (MIF), galectin-1, midkine (MK), IL-18, galectin-3, VEGF-A, hepatoma-derived growth factor (HDGF), osteopontin (OPN), connective tissue growth factor (CTGF) and granulin (GRN) are known to be involved in angiogenesis. Tube formation, neutralisation and RNA interference assays revealed that VEGF-A and HDGF function as angiogenic factors in EBC-1 cells. To confirm whether VEGF-A and HDGF also regulate angiogenesis in the other NSCLC cell lines, we established a novel culture method. NSCLC cells were embedded in collagen gel and cultured three-dimensionally. Tube formation, neutralisation and RNA interference assays using the three-dimensional (3D) culture supernatant showed that VEGF-A and HDGF were not angiogenic factors in Lu99 cells. By gene microarray in EBC-1 and Lu99 cells, we identified 61 mRNAs expressed only in Lu99 cells. Among these mRNAs, brain-derived neurotrophic factor (BDNF), fibroblast growth factor-2 (FGF-2) and FGF-5 are known to be involved in angiogenesis. Tube formation and neutralisation assays clarified that FGF-2 functions as an angiogenic factor in Lu99 cells. These results indicate that HDGF enhances VEGF-dependent angiogenesis and that FGF-2 is a VEGF-independent angiogenic factor in human NSCLC cells.
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Affiliation(s)
- Ryoji Eguchi
- Department of Environmental and Preventive Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo 663‑8501, Japan
| | - Ichiro Wakabayashi
- Department of Environmental and Preventive Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo 663‑8501, Japan
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27
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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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28
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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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29
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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: 169] [Impact Index Per Article: 33.8] [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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30
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Ahmed M, Legrand C, Yagüe Relimpio A, Beretta CA, Muschko A, Wegehingel S, Müller HM, Sehr P, Will DW, Lewis JD, Nickel W. A time-resolved live cell imaging assay to identify small molecule inhibitors of FGF2 signaling. FEBS Lett 2019; 593:2162-2176. [PMID: 31135968 DOI: 10.1002/1873-3468.13462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/18/2019] [Accepted: 05/24/2019] [Indexed: 11/10/2022]
Abstract
Fibroblast growth factor 2 (FGF2) is a cell survival factor with crucial functions in tumor-induced angiogenesis. Here, we describe a novel time-resolved FGF2 signaling assay based upon live cell imaging of neuroblastoma cells. To validate this system, we tested 8960 small molecules for inhibition of FGF2 signaling with kinetic resolution. Hit compounds were validated in dose-response experiments for FGF2 signaling, FGF receptor antagonism, downstream ERK phosphorylation and FGF2-dependent chemoresistance in a cellular leukemia model system. The new screening system for FGF2 signaling inhibitors has unique features, deselecting compounds with pleiotropic effects on cell proliferation and, along with the experimental pipeline reported, great potential for the discovery of new classes of FGF2 signaling inhibitors that block FGF2 dependent tumor cell survival.
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Affiliation(s)
| | | | | | - Carlo A Beretta
- CellNetworks Math-Clinic Core Facility, BioQuant, Heidelberg University, Germany
| | | | | | | | - Peter Sehr
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - David W Will
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Joe D Lewis
- European Molecular Biology Laboratory, Heidelberg, Germany
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31
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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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32
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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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33
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34
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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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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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36
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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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37
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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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38
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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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39
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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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40
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Pompa A, De Marchis F, Pallotta MT, Benitez-Alfonso Y, Jones A, Schipper K, Moreau K, Žárský V, Di Sansebastiano GP, Bellucci M. Unconventional Transport Routes of Soluble and Membrane Proteins and Their Role in Developmental Biology. Int J Mol Sci 2017; 18:ijms18040703. [PMID: 28346345 PMCID: PMC5412289 DOI: 10.3390/ijms18040703] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/22/2017] [Accepted: 03/23/2017] [Indexed: 12/30/2022] Open
Abstract
Many proteins and cargoes in eukaryotic cells are secreted through the conventional secretory pathway that brings proteins and membranes from the endoplasmic reticulum to the plasma membrane, passing through various cell compartments, and then the extracellular space. The recent identification of an increasing number of leaderless secreted proteins bypassing the Golgi apparatus unveiled the existence of alternative protein secretion pathways. Moreover, other unconventional routes for secretion of soluble or transmembrane proteins with initial endoplasmic reticulum localization were identified. Furthermore, other proteins normally functioning in conventional membrane traffic or in the biogenesis of unique plant/fungi organelles or in plasmodesmata transport seem to be involved in unconventional secretory pathways. These alternative pathways are functionally related to biotic stress and development, and are becoming more and more important in cell biology studies in yeast, mammalian cells and in plants. The city of Lecce hosted specialists working on mammals, plants and microorganisms for the inaugural meeting on “Unconventional Protein and Membrane Traffic” (UPMT) during 4–7 October 2016. The main aim of the meeting was to include the highest number of topics, summarized in this report, related to the unconventional transport routes of protein and membranes.
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Affiliation(s)
- Andrea Pompa
- Institute of Biosciences and Bioresources-Research Division of Perugia, National Research Council (CNR), via della Madonna Alta 130, 06128 Perugia, Italy.
| | - Francesca De Marchis
- Institute of Biosciences and Bioresources-Research Division of Perugia, National Research Council (CNR), via della Madonna Alta 130, 06128 Perugia, Italy.
| | | | | | - Alexandra Jones
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
| | - Kerstin Schipper
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany.
| | - Kevin Moreau
- Clinical Biochemistry, Institute of Metabolic Science, University of Cambridge, Cambridge CB2 1TN, UK.
| | - Viktor Žárský
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844, Prague 2, Czech Republic.
- Institute of Experimental Botany, v.v.i., the Czech Academy of Sciences, 16502, Prague 6, Czech Republic.
| | - Gian Pietro Di Sansebastiano
- Department of Biological and Environmental Sciences and Technologies (DISTEBA), University of Salento, S.P. 6, 73100 Lecce, Italy.
| | - Michele Bellucci
- Institute of Biosciences and Bioresources-Research Division of Perugia, National Research Council (CNR), via della Madonna Alta 130, 06128 Perugia, Italy.
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41
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Batulan Z, Pulakazhi Venu VK, Li Y, Koumbadinga G, Alvarez-Olmedo DG, Shi C, O'Brien ER. Extracellular Release and Signaling by Heat Shock Protein 27: Role in Modifying Vascular Inflammation. Front Immunol 2016; 7:285. [PMID: 27507972 PMCID: PMC4960997 DOI: 10.3389/fimmu.2016.00285] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 07/14/2016] [Indexed: 12/31/2022] Open
Abstract
Heat shock protein 27 (HSP27) is traditionally viewed as an intracellular chaperone protein with anti-apoptotic properties. However, recent data indicate that a number of heat shock proteins, including HSP27, are also found in the extracellular space where they may signal via membrane receptors to alter gene transcription and cellular function. Therefore, there is increasing interest in better understanding how HSP27 is released from cells, its levels and composition in the extracellular space, and the cognate cell membrane receptors involved in effecting cell signaling. In this paper, the knowledge to date, as well as some emerging paradigms about the extracellular function of HSP27 is presented. Of particular interest is the role of HSP27 in attenuating atherogenesis by modifying lipid uptake and inflammation in the plaque. Moreover, the abundance of HSP27 in serum is an emerging new biomarker for ischemic events. Finally, HSP27 replacement therapy may represent a novel therapeutic opportunity for chronic inflammatory disorders, such as atherosclerosis.
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Affiliation(s)
- Zarah Batulan
- Vascular Biology Laboratory, Health Research Innovation Centre, Libin Cardiovascular Institute of Alberta, University of Calgary Cumming School of Medicine , Calgary, AB , Canada
| | - Vivek Krishna Pulakazhi Venu
- Vascular Biology Laboratory, Health Research Innovation Centre, Libin Cardiovascular Institute of Alberta, University of Calgary Cumming School of Medicine , Calgary, AB , Canada
| | - Yumei Li
- Vascular Biology Laboratory, Health Research Innovation Centre, Libin Cardiovascular Institute of Alberta, University of Calgary Cumming School of Medicine , Calgary, AB , Canada
| | - Geremy Koumbadinga
- Vascular Biology Laboratory, Health Research Innovation Centre, Libin Cardiovascular Institute of Alberta, University of Calgary Cumming School of Medicine , Calgary, AB , Canada
| | - Daiana Gisela Alvarez-Olmedo
- Oncology Laboratory, Institute for Experimental Medicine and Biology of Cuyo (IMBECU), CCT CONICET , Mendoza , Argentina
| | - Chunhua Shi
- Vascular Biology Laboratory, Health Research Innovation Centre, Libin Cardiovascular Institute of Alberta, University of Calgary Cumming School of Medicine , Calgary, AB , Canada
| | - Edward R O'Brien
- Vascular Biology Laboratory, Health Research Innovation Centre, Libin Cardiovascular Institute of Alberta, University of Calgary Cumming School of Medicine , Calgary, AB , Canada
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42
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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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43
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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: 200] [Impact Index Per Article: 25.0] [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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44
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Robinson DG, Ding Y, Jiang L. Unconventional protein secretion in plants: a critical assessment. PROTOPLASMA 2016; 253:31-43. [PMID: 26410830 DOI: 10.1007/s00709-015-0887-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 09/18/2015] [Indexed: 05/27/2023]
Abstract
Unconventional protein secretion (UPS) is a collective term for mechanisms by which cytosolic proteins that lack a signal peptide ("leaderless secretory proteins" (LSPs)) can gain access to the cell exterior. Numerous examples of UPS have been well documented in animal and yeast cells. In contrast, our understanding of the mechanism(s) and function of UPS in plants is very limited. This review evaluates the available literature on this subject. The apparent large numbers of LSPs in the plant secretome suggest that UPS also occurs in plants but is not a proof. Although the direct transport of LSPs across the plant plasma membrane (PM) has not yet been described, it is possible that as in other eukaryotes, exosomes may be released from plant cells through fusion of multivesicular bodies (MVBs) with the PM. In this way, LSPs, but also small RNAs (sRNAs), that are passively taken up from the cytosol into the intraluminal vesicles of MVBs, could reach the apoplast. Another possible mechanism is the recently discovered exocyst-positive organelle (EXPO), a double-membrane-bound compartment, distinct from autophagosomes, which appears to sequester LSPs.
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Affiliation(s)
- David G Robinson
- Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, D-69120, Heidelberg, Germany.
| | - Yu Ding
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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45
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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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46
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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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