Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space
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 pla...
| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2024-01-01
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| Series: | eLife |
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| Online Access: | https://elifesciences.org/articles/88579 |
| _version_ | 1797348958352179200 |
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| author | Fabio Lolicato Julia P Steringer Roberto Saleppico Daniel Beyer Jaime Fernandez-Sobaberas Sebastian Unger Steffen Klein Petra Riegerová Sabine Wegehingel Hans-Michael Müller Xiao J Schmitt Shreyas Kaptan Christian Freund Martin Hof Radek Šachl Petr Chlanda Ilpo Vattulainen Walter Nickel |
| author_facet | Fabio Lolicato Julia P Steringer Roberto Saleppico Daniel Beyer Jaime Fernandez-Sobaberas Sebastian Unger Steffen Klein Petra Riegerová Sabine Wegehingel Hans-Michael Müller Xiao J Schmitt Shreyas Kaptan Christian Freund Martin Hof Radek Šachl Petr Chlanda Ilpo Vattulainen Walter Nickel |
| author_sort | Fabio Lolicato |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-03-08T12:13:41Z |
| format | Article |
| id | doaj.art-2e4e6e3f4925498a9fc2d1adf0169274 |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-03-08T12:13:41Z |
| publishDate | 2024-01-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-2e4e6e3f4925498a9fc2d1adf01692742024-01-22T15:53:14ZengeLife Sciences Publications LtdeLife2050-084X2024-01-011210.7554/eLife.88579Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular spaceFabio Lolicato0https://orcid.org/0000-0001-7537-0549Julia P Steringer1https://orcid.org/0000-0001-9418-2762Roberto Saleppico2https://orcid.org/0000-0003-0502-192XDaniel Beyer3Jaime Fernandez-Sobaberas4Sebastian Unger5Steffen Klein6Petra Riegerová7Sabine Wegehingel8Hans-Michael Müller9https://orcid.org/0000-0002-2384-7285Xiao J Schmitt10Shreyas Kaptan11Christian Freund12Martin Hof13Radek Šachl14Petr Chlanda15https://orcid.org/0000-0002-7782-2139Ilpo Vattulainen16https://orcid.org/0000-0001-7408-3214Walter Nickel17https://orcid.org/0000-0002-6496-8286Heidelberg University Biochemistry Center, Heidelberg, Germany; Department of Physics, University of Helsinki, Helsinki, FinlandHeidelberg University Biochemistry Center, Heidelberg, GermanyHeidelberg University Biochemistry Center, Heidelberg, GermanyHeidelberg University Biochemistry Center, Heidelberg, GermanyHeidelberg University Biochemistry Center, Heidelberg, GermanyHeidelberg University Biochemistry Center, Heidelberg, GermanySchaller Research Group, Department of Infectious Diseases-Virology, Heidelberg University Hospital, Heidelberg, GermanyJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czech RepublicHeidelberg University Biochemistry Center, Heidelberg, GermanyHeidelberg University Biochemistry Center, Heidelberg, GermanyInstitute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, GermanyDepartment of Physics, University of Helsinki, Helsinki, FinlandInstitute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, GermanyJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czech RepublicJ. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czech RepublicSchaller Research Group, Department of Infectious Diseases-Virology, Heidelberg University Hospital, Heidelberg, GermanyDepartment of Physics, University of Helsinki, Helsinki, FinlandHeidelberg University Biochemistry Center, Heidelberg, GermanyFibroblast 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.https://elifesciences.org/articles/88579FGF2Unconventional protein secretionProtein traffickingProtein-lipid interactionProtein-protein interaction |
| spellingShingle | Fabio Lolicato Julia P Steringer Roberto Saleppico Daniel Beyer Jaime Fernandez-Sobaberas Sebastian Unger Steffen Klein Petra Riegerová Sabine Wegehingel Hans-Michael Müller Xiao J Schmitt Shreyas Kaptan Christian Freund Martin Hof Radek Šachl Petr Chlanda Ilpo Vattulainen Walter Nickel Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space eLife FGF2 Unconventional protein secretion Protein trafficking Protein-lipid interaction Protein-protein interaction |
| title | Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space |
| title_full | Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space |
| title_fullStr | Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space |
| title_full_unstemmed | Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space |
| title_short | Disulfide bridge-dependent dimerization triggers FGF2 membrane translocation into the extracellular space |
| title_sort | disulfide bridge dependent dimerization triggers fgf2 membrane translocation into the extracellular space |
| topic | FGF2 Unconventional protein secretion Protein trafficking Protein-lipid interaction Protein-protein interaction |
| url | https://elifesciences.org/articles/88579 |
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