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Li D, Huang P, Xia L, Leng W, Qin S. Cancer-associated fibroblasts promote gastric cancer cell proliferation by paracrine FGF2-driven ribosome biogenesis. Int Immunopharmacol 2024; 131:111836. [PMID: 38479160 DOI: 10.1016/j.intimp.2024.111836] [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: 01/28/2024] [Revised: 03/05/2024] [Accepted: 03/08/2024] [Indexed: 04/10/2024]
Abstract
The cancer-associated fibroblast (CAF)-derived secretome plays critical roles in tumor progression by remodelling tumor microenvironment. Tumorigenesis is accompanied by the transformation of normal fibroblasts (NF) into CAF, leading to significant changes in their secretome. This work aims to identify the differential components of secretome between NFs and CAFs and reveal their functions in gastric cancer (GC). Firstly, our molecular typing studies and immune infiltration analysis showed that CAF infiltration level was increased and showed a significant association with clinical characteristics and poor prognosis of GC patients. Secondly, RNA-seq analysis revealed that a total of 1531 genes showed significant expression changes between NF and CAF. According to the annotation of the Human Protein Atlas (HPA) database, 147 genes encode secreted proteins, including FGF2. Particularly, the cell co-culture and RNA sequencing studies confirmed that exogenous recombinant FGF2 protein treatment promoted GC cell proliferation by enhancing ribosome biogenesis. The rescue assay showed that CAF-secreted FGF2 protein promotes GC cell growth and proliferation in a FGFR1-dependent manner. Our finding provides evidence that targeting blockade of CAF-derived FGF2 protein might be a promising treatment for GC.
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Affiliation(s)
- Dandan Li
- Department of Stomatology, Taihe Hospital and Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, China; Laboratory of Tumor Biology, Academy of Bio-Medicine Research, Hubei University of Medicine, Shiyan, Hubei 442000, China; Shiyan Key Laboratory of Natural Medicine Nanoformulation Research, Hubei University of Medicine, Shiyan, Hubei 442000, China
| | - Pan Huang
- Department of Stomatology, Taihe Hospital and Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, China; Laboratory of Tumor Biology, Academy of Bio-Medicine Research, Hubei University of Medicine, Shiyan, Hubei 442000, China
| | - Lingyun Xia
- Department of Stomatology, Taihe Hospital and Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, China
| | - Weidong Leng
- Department of Stomatology, Taihe Hospital and Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, China.
| | - Shanshan Qin
- Department of Stomatology, Taihe Hospital and Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, China; Laboratory of Tumor Biology, Academy of Bio-Medicine Research, Hubei University of Medicine, Shiyan, Hubei 442000, China; Shiyan Key Laboratory of Natural Medicine Nanoformulation Research, Hubei University of Medicine, Shiyan, Hubei 442000, China.
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2
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Wang L, Xu Y, Fukushige T, Saidi L, Wang X, Yu C, Lee JG, Krause M, Huang L, Ye Y. Mono-UFMylation promotes misfolding-associated secretion of α-synuclein. SCIENCE ADVANCES 2024; 10:eadk2542. [PMID: 38489364 PMCID: PMC10942102 DOI: 10.1126/sciadv.adk2542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 02/12/2024] [Indexed: 03/17/2024]
Abstract
Stressed cells secret misfolded proteins lacking signaling sequence via an unconventional protein secretion (UcPS) pathway, but how misfolded proteins are targeted selectively in UcPS is unclear. Here, we report that misfolded UcPS clients are subject to modification by a ubiquitin-like protein named ubiquitin-fold modifier 1 (UFM1). Using α-synuclein (α-Syn) as a UcPS model, we show that mutating the UFMylation sites in α-Syn or genetic inhibition of the UFMylation system mitigates α-Syn secretion, whereas overexpression of UFBP1, a component of the endoplasmic reticulum-associated UFMylation ligase complex, augments α-Syn secretion in mammalian cells and in model organisms. UFM1 itself is cosecreted with α-Syn, and the serum UFM1 level correlates with that of α-Syn. Because UFM1 can be directly recognized by ubiquitin specific peptidase 19 (USP19), a previously established UcPS stimulator known to associate with several chaperoning activities, UFMylation might facilitate substrate engagement by USP19, allowing stringent and regulated selection of misfolded proteins for secretion and proteotoxic stress alleviation.
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Affiliation(s)
- Lihui Wang
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yue Xu
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tetsunari Fukushige
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Layla Saidi
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiaorong Wang
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA
| | - Jin-Gu Lee
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Michael Krause
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lan Huang
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, USA
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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3
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Kádková A, Murach J, Østergaard M, Malsam A, Malsam J, Lolicato F, Nickel W, Söllner TH, Sørensen JB. SNAP25 disease mutations change the energy landscape for synaptic exocytosis due to aberrant SNARE interactions. eLife 2024; 12:RP88619. [PMID: 38411501 PMCID: PMC10911398 DOI: 10.7554/elife.88619] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024] Open
Abstract
SNAP25 is one of three neuronal SNAREs driving synaptic vesicle exocytosis. We studied three mutations in SNAP25 that cause epileptic encephalopathy: V48F, and D166Y in the synaptotagmin-1 (Syt1)-binding interface, and I67N, which destabilizes the SNARE complex. All three mutations reduced Syt1-dependent vesicle docking to SNARE-carrying liposomes and Ca2+-stimulated membrane fusion in vitro and when expressed in mouse hippocampal neurons. The V48F and D166Y mutants (with potency D166Y > V48F) led to reduced readily releasable pool (RRP) size, due to increased spontaneous (miniature Excitatory Postsynaptic Current, mEPSC) release and decreased priming rates. These mutations lowered the energy barrier for fusion and increased the release probability, which are gain-of-function features not found in Syt1 knockout (KO) neurons; normalized mEPSC release rates were higher (potency D166Y > V48F) than in the Syt1 KO. These mutations (potency D166Y > V48F) increased spontaneous association to partner SNAREs, resulting in unregulated membrane fusion. In contrast, the I67N mutant decreased mEPSC frequency and evoked EPSC amplitudes due to an increase in the height of the energy barrier for fusion, whereas the RRP size was unaffected. This could be partly compensated by positive charges lowering the energy barrier. Overall, pathogenic mutations in SNAP25 cause complex changes in the energy landscape for priming and fusion.
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Affiliation(s)
- Anna Kádková
- Department of Neuroscience, University of CopenhagenCopenhagenDenmark
| | | | - Maiken Østergaard
- Department of Neuroscience, University of CopenhagenCopenhagenDenmark
| | - Andrea Malsam
- Heidelberg University Biochemistry CenterHeidelbergDenmark
| | - Jörg Malsam
- Heidelberg University Biochemistry CenterHeidelbergDenmark
| | - Fabio Lolicato
- Heidelberg University Biochemistry CenterHeidelbergDenmark
- Department of Physics, University of HelsinkiHelsinkiFinland
| | - Walter Nickel
- Heidelberg University Biochemistry CenterHeidelbergDenmark
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4
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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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5
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Balmer EA, Wirdnam CD, Faso C. A core UPS molecular complement implicates unique endocytic compartments at the parasite-host interface in Giardia lamblia. Virulence 2023; 14:2174288. [PMID: 36730629 PMCID: PMC9928461 DOI: 10.1080/21505594.2023.2174288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Unconventional protein secretion (UPS) plays important roles in cell physiology. In contrast to canonical secretory routes, UPS does not generally require secretory signal sequences and often bypasses secretory compartments such as the ER and the Golgi apparatus. Giardia lamblia is a protist parasite with reduced subcellular complexity which releases several proteins, some of them virulence factors, without canonical secretory signals. This implicates UPS at the parasite-host interface. No dedicated machinery nor mechanism(s) for UPS in Giardia are currently known, although speculations on the involvement of endocytic organelles called PV/PECs, have been put forth. To begin to address the question of whether PV/PECs are implicated in virulence-associated UPS and to define the composition of molecular machinery involved in protein release, we employed affinity purification and mass spectrometry, coupled to microscopy-based subcellular localization and signal correlation quantification to investigate the interactomes of 11 reported unconventionally secreted proteins, all predicted to be cytosolic. A subset of these are associated with PV/PECs. Extended and validated interactomes point to a core PV/PECs-associated UPS machinery, which includes uncharacterized and Giardia-specific coiled-coil proteins and NEK kinases. Finally, a subset of the alpha-giardin protein family was enriched in all PV/PECs-associated protein interactomes, highlighting a previously unappreciated role for these proteins at PV/PECs and in UPS. Taken together, our results provide the first characterization of a virulence-associated UPS protein complex in Giardia lamblia at PV/PECs, suggesting a novel link between these primarily endocytic and feeding organelles and UPS at the parasite-host interface.
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Affiliation(s)
- Erina A. Balmer
- Institute of Cell Biology, University of Bern, Bern, Switzerland,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | | | - Carmen Faso
- Institute of Cell Biology, University of Bern, Bern, Switzerland,Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland,CONTACT Carmen Faso
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6
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Biadun M, Sochacka M, Karelus R, Baran K, Czyrek A, Otlewski J, Krowarsch D, Opalinski L, Zakrzewska M. FGF homologous factors are secreted from cells to induce FGFR-mediated anti-apoptotic response. FASEB J 2023; 37:e23043. [PMID: 37342898 DOI: 10.1096/fj.202300324r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/10/2023] [Accepted: 06/07/2023] [Indexed: 06/23/2023]
Abstract
FGF homologous factors (FHFs) are the least described group of fibroblast growth factors (FGFs). The FHF subfamily consists of four proteins: FGF11, FGF12, FGF13, and FGF14. Until recently, FHFs were thought to be intracellular, non-signaling molecules, despite sharing structural and sequence similarities with other members of FGF family that can be secreted and activate cell signaling by interacting with surface receptors. Here, we show that despite lacking a canonical signal peptide for secretion, FHFs are exported to the extracellular space. Furthermore, we propose that their secretion mechanism is similar to the unconventional secretion of FGF2. The secreted FHFs are biologically active and trigger signaling in cells expressing FGF receptors (FGFRs). Using recombinant proteins, we demonstrated their direct binding to FGFR1, resulting in the activation of downstream signaling and the internalization of the FHF-FGFR1 complex. The effect of receptor activation by FHF proteins is an anti-apoptotic response of the cell.
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Affiliation(s)
- Martyna Biadun
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
- Department of Protein Biotechnology, Faculty of Biotchnology, University of Wroclaw, Wroclaw, Poland
| | - Martyna Sochacka
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Radoslaw Karelus
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Karolina Baran
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Aleksandra Czyrek
- Department of Protein Biotechnology, Faculty of Biotchnology, University of Wroclaw, Wroclaw, Poland
| | - Jacek Otlewski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Daniel Krowarsch
- Department of Protein Biotechnology, Faculty of Biotchnology, University of Wroclaw, Wroclaw, Poland
| | - Lukasz Opalinski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Malgorzata Zakrzewska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
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7
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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: 3] [Impact Index Per Article: 1.5] [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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8
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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: 31] [Impact Index Per Article: 15.5] [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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9
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Maricchiolo E, Panfili E, Pompa A, De Marchis F, Bellucci M, Pallotta MT. Unconventional Pathways of Protein Secretion: Mammals vs. Plants. Front Cell Dev Biol 2022; 10:895853. [PMID: 35573696 PMCID: PMC9096121 DOI: 10.3389/fcell.2022.895853] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 04/13/2022] [Indexed: 01/08/2023] Open
Abstract
In eukaryotes, many proteins contain an N-terminal signal peptide that allows their translocation into the endoplasmic reticulum followed by secretion outside the cell according to the classical secretory system. However, an increasing number of secreted proteins lacking the signal peptide sequence are emerging. These proteins, secreted in several alternative ways collectively known as unconventional protein secretion (UPS) pathways, exert extracellular functions including cell signaling, immune modulation, as well as moonlighting activities different from their well-described intracellular functions. Pathways for UPS include direct transfer across the plasma membrane, secretion from endosomal/multivesicular body-related components, release within plasma membrane-derived microvesicles, or use of elements of autophagy. In this review we describe the mammals and plants UPS pathways identified so far highlighting commonalities and differences.
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Affiliation(s)
- Elisa Maricchiolo
- Section of Biological and Biotechnological Sciences, Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy
| | - Eleonora Panfili
- Section of Pharmacology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Andrea Pompa
- Section of Biological and Biotechnological Sciences, Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy
| | - Francesca De Marchis
- Institute of Biosciences and Bioresources, National Research Council of Italy, Perugia, Italy
| | - Michele Bellucci
- Institute of Biosciences and Bioresources, National Research Council of Italy, Perugia, Italy
- *Correspondence: Michele Bellucci, ; Maria Teresa Pallotta,
| | - Maria Teresa Pallotta
- Section of Pharmacology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
- *Correspondence: Michele Bellucci, ; Maria Teresa Pallotta,
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10
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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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11
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Lolicato F, Nickel W. A Role for Liquid-Ordered Plasma Membrane Nanodomains Coordinating the Unconventional Secretory Pathway of Fibroblast Growth Factor 2? Front Cell Dev Biol 2022; 10:864257. [PMID: 35433697 PMCID: PMC9010882 DOI: 10.3389/fcell.2022.864257] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 02/18/2022] [Indexed: 11/22/2022] Open
Abstract
Fibroblast growth factor 2 (FGF2) is a tumor cell survival factor that belongs to a subgroup of extracellular proteins lacking N-terminal signal peptides. Whereas this phenomenon was already recognized in the early 1990s, detailed insights into the molecular mechanisms underlying alternative pathways of protein secretion from eukaryotic cells were obtained only recently. Today, we know about a number of alternative secretory mechanisms, collectively termed unconventional protein secretion (UPS). FGF2 belongs to a subgroup of cargo proteins secreted by direct translocation across the plasma membrane. This feature has been classified as type I UPS and is shared with other unconventionally secreted proteins, such as HIV-Tat and Tau. FGF2 translocation across the membrane is initiated through sequential interactions with the Na,K-ATPase, Tec kinase, and phosphoinositide PI(4,5)P2 at the inner plasma membrane leaflet. Whereas the first two are auxiliary factors of this pathway, the interaction of FGF2 with PI(4,5)P2 triggers the core mechanism of FGF2 membrane translocation. It is based on a lipidic membrane pore that is formed by PI(4,5)P2-induced oligomerization of FGF2. Membrane-inserted FGF2 oligomers are recognized as translocation intermediates that are resolved at the outer plasma membrane leaflet by glypican-1, a heparan sulfate proteoglycan that captures and disassembles FGF2 oligomers on cell surfaces. Here, we discuss recent findings suggesting the molecular machinery mediating FGF2 membrane translocation to be highly organized in liquid-ordered plasma membrane nanodomains, the core process underlying this unusual pathway of protein secretion.
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12
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Sparn C, Dimou E, Meyer A, Saleppico R, Wegehingel S, Gerstner M, Klaus S, Ewers H, Nickel W. Glypican-1 drives unconventional secretion of Fibroblast Growth Factor 2. eLife 2022; 11:75545. [PMID: 35348113 PMCID: PMC8986318 DOI: 10.7554/elife.75545] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Fibroblast Growth Factor 2 (FGF2) is a tumor cell survival factor that is transported into the extracellular space by an unconventional secretory mechanism. Cell surface heparan sulfate proteoglycans are known to play an essential role in this process. Unexpectedly, we found that among the diverse sub-classes consisting of syndecans, perlecans, glypicans and others, Glypican-1 (GPC1) is the principle and rate-limiting factor that drives unconventional secretion of FGF2. By contrast, we demonstrate GPC1 to be dispensable for FGF2 signaling into cells. We provide first insights into the structural basis for GPC1-dependent FGF2 secretion, identifying disaccharides with N-linked sulfate groups to be enriched in the heparan sulfate chains of GPC1 to which FGF2 binds with high affinity. Our findings have broad implications for the role of GPC1 as a key molecule in tumor progression.
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Affiliation(s)
| | | | | | | | | | | | | | - Helge Ewers
- Institut für Chemie und Biochemie, Freie Universität Berlin
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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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Balmer EA, Faso C. The Road Less Traveled? Unconventional Protein Secretion at Parasite-Host Interfaces. Front Cell Dev Biol 2021; 9:662711. [PMID: 34109175 PMCID: PMC8182054 DOI: 10.3389/fcell.2021.662711] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/07/2021] [Indexed: 01/01/2023] Open
Abstract
Protein secretion in eukaryotic cells is a well-studied process, which has been known for decades and is dealt with by any standard cell biology textbook. However, over the past 20 years, several studies led to the realization that protein secretion as a process might not be as uniform among different cargos as once thought. While in classic canonical secretion proteins carry a signal sequence, the secretory or surface proteome of several organisms demonstrated a lack of such signals in several secreted proteins. Other proteins were found to indeed carry a leader sequence, but simply circumvent the Golgi apparatus, which in canonical secretion is generally responsible for the modification and sorting of secretory proteins after their passage through the endoplasmic reticulum (ER). These alternative mechanisms of protein translocation to, or across, the plasma membrane were collectively termed “unconventional protein secretion” (UPS). To date, many research groups have studied UPS in their respective model organism of choice, with surprising reports on the proportion of unconventionally secreted proteins and their crucial roles for the cell and survival of the organism. Involved in processes such as immune responses and cell proliferation, and including far more different cargo proteins in different organisms than anyone had expected, unconventional secretion does not seem so unconventional after all. Alongside mammalian cells, much work on this topic has been done on protist parasites, including genera Leishmania, Trypanosoma, Plasmodium, Trichomonas, Giardia, and Entamoeba. Studies on protein secretion have mainly focused on parasite-derived virulence factors as a main source of pathogenicity for hosts. Given their need to secrete a variety of substrates, which may not be compatible with canonical secretion pathways, the study of mechanisms for alternative secretion pathways is particularly interesting in protist parasites. In this review, we provide an overview on the current status of knowledge on UPS in parasitic protists preceded by a brief overview of UPS in the mammalian cell model with a focus on IL-1β and FGF-2 as paradigmatic UPS substrates.
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Affiliation(s)
- Erina A Balmer
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Carmen Faso
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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15
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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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