1
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Leinung N, Mentrup T, Patel M, Gallagher T, Schröder B. Dynamic association of the intramembrane proteases SPPL2a/b and their substrates with tetraspanin-enriched microdomains. iScience 2023; 26:107819. [PMID: 37736044 PMCID: PMC10509304 DOI: 10.1016/j.isci.2023.107819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 07/21/2023] [Accepted: 08/31/2023] [Indexed: 09/23/2023] Open
Abstract
Signal peptide peptidase-like 2a and b (SPPL2a/b) are aspartyl intramembrane proteases and cleave tail-anchored proteins as well as N-terminal fragments (NTFs) derived from type II-oriented transmembrane proteins. How these proteases recruit substrates and cleavage is regulated, is still incompletely understood. We found that SPPL2a/b localize to detergent-resistant membrane (DRM) domains with the characteristics of tetraspanin-enriched microdomains (TEMs). Based on this, association with several tetraspanins was evaluated. We demonstrate that not only SPPL2a/b but also their substrates tumor necrosis factor (TNF) and CD74 associate with tetraspanins like CD9, CD81, and CD82 and/or TEMs and analyze the stability of these complexes in different detergents. CD9 and CD81 deficiency has protease- and substrate-selective effects on SPPL2a/b function. Our findings suggest that reciprocal interactions with tetraspanins may assist protease-substrate encounters of SPPL2a/b within the membrane. Beyond SPP/SPPL proteases, this supports previous concepts that tetraspanins facilitate membrane-embedded proteolytic processes.
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Affiliation(s)
- Nadja Leinung
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Torben Mentrup
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Mehul Patel
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Tom Gallagher
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Bernd Schröder
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
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2
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Contreras W, Bazan JF, Mentrup T. The transmembrane domain of Frey1 harbors a transplantable inhibitory motif for intramembrane proteases. Cell Mol Life Sci 2023; 80:170. [PMID: 37261541 DOI: 10.1007/s00018-023-04823-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 05/23/2023] [Accepted: 05/23/2023] [Indexed: 06/02/2023]
Abstract
Although aspartic intramembrane-cleaving proteases (I-CLIPs) are crucial switches of multiple signaling pathways and involved in several devastating diseases, little is known about their physiological regulation. We have recently identified Frey regulator of sperm-oocyte fusion 1 (Frey1) as an inhibitory protein of Signal Peptide Peptidase-like 2c (SPPL2c), a member of this protease family. Employing structure modeling along with cell-based inhibition and interaction studies, we identify a short motif within the Frey1 transmembrane domain essential for inhibition of SPPL2c. Intriguingly, this motif can be transplanted to the SPPL2c substrate PLN, thereby transforming it into an inhibitor of this enzyme. It can be adopted for the generation of Notch1-based γ-Secretase inhibitors demonstrating its versatile use among aspartic I-CLIPs. In summary, we describe a mechanism of aspartic I-CLIP inhibition which allows the targeted generation of specific inhibitors of these enzymes and might enable the identification of endogenous negative regulators of these enzymes.
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Affiliation(s)
- Whendy Contreras
- Institute of Physiological Chemistry, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - J Fernando Bazan
- Unit for Structural Biology, VIB-UGent Center for Inflammation Research, Ghent, Belgium
| | - Torben Mentrup
- Institute of Physiological Chemistry, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany.
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3
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Papadopoulou AA, Stelzer W, Silber M, Schlosser C, Spitz C, Haug-Kröper M, Straub T, Müller SA, Lichtenthaler SF, Muhle-Goll C, Langosch D, Fluhrer R. Helical stability of the GnTV transmembrane domain impacts on SPPL3 dependent cleavage. Sci Rep 2022; 12:20987. [PMID: 36470941 PMCID: PMC9722940 DOI: 10.1038/s41598-022-24772-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
Signal-Peptide Peptidase Like-3 (SPPL3) is an intramembrane cleaving aspartyl protease that causes secretion of extracellular domains from type-II transmembrane proteins. Numerous Golgi-localized glycosidases and glucosyltransferases have been identified as physiological SPPL3 substrates. By SPPL3 dependent processing, glycan-transferring enzymes are deactivated inside the cell, as their active site-containing domain is cleaved and secreted. Thus, SPPL3 impacts on glycan patterns of many cellular and secreted proteins and can regulate protein glycosylation. However, the characteristics that make a substrate a favourable candidate for SPPL3-dependent cleavage remain unknown. To gain insights into substrate requirements, we investigated the function of a GxxxG motif located in the transmembrane domain of N-acetylglucosaminyltransferase V (GnTV), a well-known SPPL3 substrate. SPPL3-dependent secretion of the substrate's ectodomain was affected by mutations disrupting the GxxxG motif. Using deuterium/hydrogen exchange and NMR spectroscopy, we studied the effect of these mutations on the helix flexibility of the GnTV transmembrane domain and observed that increased flexibility facilitates SPPL3-dependent shedding and vice versa. This study provides first insights into the characteristics of SPPL3 substrates, combining molecular biology, biochemistry, and biophysical techniques and its results will provide the basis for better understanding the characteristics of SPPL3 substrates with implications for the substrates of other intramembrane proteases.
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Affiliation(s)
- Alkmini A. Papadopoulou
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Walter Stelzer
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Mara Silber
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Christine Schlosser
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Charlotte Spitz
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Martina Haug-Kröper
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Tobias Straub
- grid.5252.00000 0004 1936 973XCore Facility Bioinformatics, Biomedical Center, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Stephan A. Müller
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany
| | - Stefan F. Lichtenthaler
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany ,grid.15474.330000 0004 0477 2438Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany ,grid.452617.3Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Claudia Muhle-Goll
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Dieter Langosch
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Regina Fluhrer
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
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4
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Trávníčková K, Stříšovský K. On the track of intramembrane clippers: the
SPPL2a
/b proteases caught in the act in animal models. FEBS J 2022; 290:2306-2310. [PMID: 36310421 DOI: 10.1111/febs.16663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 10/20/2022] [Indexed: 11/05/2022]
Abstract
In this issue, Ballin et al. report on their analysis of the substrate repertoire of SPPL2a and b intramembrane proteases. Based on the previous studies of their closest homologues, SPPL2c, SPPL3 and SPP, the authors hypothesized that SPPL2a/b proteases may cleave a subset of SNARE proteins. Indeed, four R-SNARE proteins, VAMP1, 2, 3 and 4, were cleaved by SPPL2a/b, both in overexpression assays and at endogenous levels. These findings have been validated by analysis of SPPL2a/b double knock-out mice tissues, which implicates these proteases in the regulation of SNARE protein turnover in vivo. The study of Ballin et al. also provides material for future studies of factors determining substrate specificity of SPPLs, as they cleave different subsets of the tail-anchored SNARE proteins. Comment on: https://doi.org/10.1111/febs.16610.
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Affiliation(s)
- Květa Trávníčková
- Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Praha Czechia
| | - Kvido Stříšovský
- Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Praha Czechia
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5
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Hobohm L, Koudelka T, Bahr FH, Truberg J, Kapell S, Schacht SS, Meisinger D, Mengel M, Jochimsen A, Hofmann A, Heintz L, Tholey A, Voss M. N-terminome analyses underscore the prevalence of SPPL3-mediated intramembrane proteolysis among Golgi-resident enzymes and its role in Golgi enzyme secretion. Cell Mol Life Sci 2022; 79:185. [PMID: 35279766 PMCID: PMC8918473 DOI: 10.1007/s00018-022-04163-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 01/07/2022] [Accepted: 01/22/2022] [Indexed: 12/17/2022]
Abstract
Golgi membrane proteins such as glycosyltransferases and other glycan-modifying enzymes are key to glycosylation of proteins and lipids. Secretion of soluble Golgi enzymes that are released from their membrane anchor by endoprotease activity is a wide-spread yet largely unexplored phenomenon. The intramembrane protease SPPL3 can specifically cleave select Golgi enzymes, enabling their secretion and concomitantly altering global cellular glycosylation, yet the entire range of Golgi enzymes cleaved by SPPL3 under physiological conditions remains to be defined. Here, we established isogenic SPPL3-deficient HEK293 and HeLa cell lines and applied N-terminomics to identify substrates cleaved by SPPL3 and released into cell culture supernatants. With high confidence, our study identifies more than 20 substrates of SPPL3, including entirely novel substrates. Notably, our N-terminome analyses provide a comprehensive list of SPPL3 cleavage sites demonstrating that SPPL3-mediated shedding of Golgi enzymes occurs through intramembrane proteolysis. Through the use of chimeric glycosyltransferase constructs we show that transmembrane domains can determine cleavage by SPPL3. Using our cleavage site data, we surveyed public proteome data and found that SPPL3 cleavage products are present in human blood. We also generated HEK293 knock-in cells expressing the active site mutant D271A from the endogenous SPPL3 locus. Immunoblot analyses revealed that secretion of select novel substrates such as the key mucin-type O-glycosylation enzyme GALNT2 is dependent on endogenous SPPL3 protease activity. In sum, our study expands the spectrum of known physiological substrates of SPPL3 corroborating its significant role in Golgi enzyme turnover and secretion as well as in the regulation of global glycosylation pathways.
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Affiliation(s)
- Laura Hobohm
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Tomas Koudelka
- Systematic Proteome Research and Bioanalytics, Institute for Experimental Medicine, Kiel University, 24105, Kiel, Germany
| | - Fenja H Bahr
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Jule Truberg
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Sebastian Kapell
- National Bioinformatics Infrastructure Sweden (NBIS), Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 10691, Stockholm, Sweden
| | - Sarah-Sophie Schacht
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
- Institute of Immunology, University Medical Center Schleswig-Holstein, 24105, Kiel, Germany
| | - Daniel Meisinger
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Marion Mengel
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Alexander Jochimsen
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Anna Hofmann
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
| | - Lukas Heintz
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany
- Institute for Cellular and Integrative Physiology, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Andreas Tholey
- Systematic Proteome Research and Bioanalytics, Institute for Experimental Medicine, Kiel University, 24105, Kiel, Germany
| | - Matthias Voss
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, 24118, Kiel, Germany.
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6
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Mentrup T, Schröder B. Signal peptide peptidase-like 2 proteases: Regulatory switches or proteasome of the membrane? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119163. [PMID: 34673079 DOI: 10.1016/j.bbamcr.2021.119163] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 10/07/2021] [Accepted: 10/11/2021] [Indexed: 12/30/2022]
Abstract
Signal peptide peptidase-like 2 (SPPL) proteases constitute a subfamily of SPP/SPPL intramembrane proteases which are homologues of the presenilins, the catalytic core of the γ-secretase complex. The three SPPL2 proteases SPPL2a, SPPL2b and SPPL2c proteolyse single-span, type II-oriented transmembrane proteins and/or tail-anchored proteins within their hydrophobic transmembrane segments. We review recent progress in defining substrate spectra and in vivo functions of these proteases. Characterisation of the respective knockout mice has implicated SPPL2 proteases in immune cell differentiation and function, prevention of atherosclerotic plaque development and spermatogenesis. Mechanisms how substrates are selected by these enzymes are still incompletely understood. We will discuss current views on how selective SPPL2-mediated cleavage is or whether these proteases may exhibit a generalised role in the turnover of membrane proteins. This has been suggested previously for the mechanistically related γ-secretase for which the term "proteasome of the membrane" has been coined based on its broad substrate spectrum. With regard to individual substrates, potential signalling functions of the resulting cytosolic cleavage fragments remain a controversial aspect. However, it has been clearly shown that SPPL2 proteases can influence cellular signalling and membrane trafficking by controlling levels of their membrane-bound substrate proteins which highlights these enzymes as regulatory switches. Based on this, regulatory mechanisms controlling activity of SPPL2 proteases would need to be postulated, which are just beginning to emerge. These different questions, which are relevant for other families of intramembrane proteases in a similar way, will be critically discussed based on the current state of knowledge.
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Affiliation(s)
- Torben Mentrup
- Institute for Physiological Chemistry, Technische Universität Dresden, Fiedlerstraße 42, D-01307 Dresden, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Technische Universität Dresden, Fiedlerstraße 42, D-01307 Dresden, Germany.
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7
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Spitz C, Schlosser C, Guschtschin-Schmidt N, Stelzer W, Menig S, Götz A, Haug-Kröper M, Scharnagl C, Langosch D, Muhle-Goll C, Fluhrer R. Non-canonical Shedding of TNFα by SPPL2a Is Determined by the Conformational Flexibility of Its Transmembrane Helix. iScience 2020; 23:101775. [PMID: 33294784 PMCID: PMC7689174 DOI: 10.1016/j.isci.2020.101775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/21/2020] [Accepted: 11/03/2020] [Indexed: 12/22/2022] Open
Abstract
Ectodomain (EC) shedding defines the proteolytic removal of a membrane protein EC and acts as an important molecular switch in signaling and other cellular processes. Using tumor necrosis factor (TNF)α as a model substrate, we identify a non-canonical shedding activity of SPPL2a, an intramembrane cleaving aspartyl protease of the GxGD type. Proline insertions in the TNFα transmembrane (TM) helix strongly increased SPPL2a non-canonical shedding, while leucine mutations decreased this cleavage. Using biophysical and structural analysis, as well as molecular dynamic simulations, we identified a flexible region in the center of the TNFα wildtype TM domain, which plays an important role in the processing of TNFα by SPPL2a. This study combines molecular biology, biochemistry, and biophysics to provide insights into the dynamic architecture of a substrate's TM helix and its impact on non-canonical shedding. Thus, these data will provide the basis to identify further physiological substrates of non-canonical shedding in the future.
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Affiliation(s)
- Charlotte Spitz
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Christine Schlosser
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Nadja Guschtschin-Schmidt
- Karlsruhe Institute of Technology, Institute for Biological Interfaces 4, 76344 Eggenstein- Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute of Organic Chemistry, 76131 Karlsruhe, Germany
| | - Walter Stelzer
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Simon Menig
- Physics of Synthetic Biological Systems, Technische Universität München, Maximus-von-Imhof Forum 4, 85340 Freising, Germany
| | - Alexander Götz
- Present Address: Leibniz Supercomputing Centre, Boltzmannstr. 1, 85748 Garching, Germany
| | - Martina Haug-Kröper
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Christina Scharnagl
- Physics of Synthetic Biological Systems, Technische Universität München, Maximus-von-Imhof Forum 4, 85340 Freising, Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Claudia Muhle-Goll
- Karlsruhe Institute of Technology, Institute for Biological Interfaces 4, 76344 Eggenstein- Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute of Organic Chemistry, 76131 Karlsruhe, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
- DZNE – German Center for Neurodegenerative Diseases, Feodor-Lynen-Str 17, 81377 Munich, Germany
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8
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Cathepsin S provokes interleukin-6 (IL-6) trans-signaling through cleavage of the IL-6 receptor in vitro. Sci Rep 2020; 10:21612. [PMID: 33303781 PMCID: PMC7730449 DOI: 10.1038/s41598-020-77884-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 11/18/2020] [Indexed: 02/07/2023] Open
Abstract
The cytokine interleukin-6 (IL-6) fulfills its pleiotropic functions via different modes of signaling. Regenerative and anti-inflammatory activities are mediated via classic signaling, in which IL-6 binds to the membrane-bound IL-6 receptor (IL-6R). For IL-6 trans-signaling, which accounts for the pro-inflammatory properties of the cytokine, IL-6 activates its target cells via soluble forms of the IL-6R (sIL-6R). We have previously shown that the majority of sIL-6R in human serum originates from proteolytic cleavage and mapped the cleavage site of the IL-6R. The cleavage occurs between Pro-355 and Val-356, which is the same cleavage site that the metalloprotease ADAM17 uses in vitro. However, sIL-6R serum levels are unchanged in hypomorphic ADAM17ex/ex mice, making the involvement of ADAM17 questionable. In order to identify other proteases that could be relevant for sIL-6R generation in vivo, we perform a screening approach based on the known cleavage site. We identify several candidate proteases and characterize the cysteine protease cathepsin S (CTSS) in detail. We show that CTSS is able to cleave the IL-6R in vitro and that the released sIL-6R is biologically active and can induce IL-6 trans-signaling. However, CTSS does not use the Pro-355/Val-356 cleavage site, and sIL-6R serum levels are not altered in Ctss-/- mice. In conclusion, we identify a novel protease of the IL-6R that can induce IL-6 trans-signaling, but does not contribute to steady-state sIL-6R serum levels.
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9
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Antagonism of Macrophage Migration Inhibitory Factory (MIF) after Traumatic Brain Injury Ameliorates Astrocytosis and Peripheral Lymphocyte Activation and Expansion. Int J Mol Sci 2020; 21:ijms21207448. [PMID: 33050322 PMCID: PMC7589344 DOI: 10.3390/ijms21207448] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/10/2020] [Accepted: 09/23/2020] [Indexed: 12/22/2022] Open
Abstract
Traumatic brain injury (TBI) precedes the onset of epilepsy in up to 15–20% of symptomatic epilepsies and up to 5% of all epilepsy. Treatment of acquired epilepsies, including post-traumatic epilepsy (PTE), presents clinical challenges, including frequent resistance to anti-epileptic therapies. Considering that over 1.6 million Americans present with a TBI each year, PTE is an urgent clinical problem. Neuroinflammation is thought to play a major causative role in many of the post-traumatic syndromes, including PTE. Increasing evidence suggests that neuroinflammation facilitates and potentially contributes to seizure induction and propagation. The inflammatory cytokine, macrophage migration inhibitory factor (MIF), is elevated after TBI and higher levels of MIF correlate with worse post-traumatic outcomes. MIF was recently demonstrated to directly alter the firing dynamics of CA1 pyramidal neurons in the hippocampus, a structure critically involved in many types of seizures. We hypothesized that antagonizing MIF after TBI would be anti-inflammatory, anti-neuroinflammatory and neuroprotective. The results show that administering the MIF antagonist ISO1 at 30 min after TBI prevented astrocytosis but was not neuroprotective in the peri-lesion cortex. The results also show that ISO1 inhibited the TBI-induced increase in γδT cells in the gut, and the percent of B cells infiltrating into the brain. The ISO1 treatment also increased this population of B cells in the spleen. These findings are discussed with an eye towards their therapeutic potential for post-traumatic syndromes, including PTE.
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10
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Signal Peptide Peptidase-Type Proteases: Versatile Regulators with Functions Ranging from Limited Proteolysis to Protein Degradation. J Mol Biol 2020; 432:5063-5078. [DOI: 10.1016/j.jmb.2020.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/02/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022]
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11
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Mentrup T, Cabrera-Cabrera F, Fluhrer R, Schröder B. Physiological functions of SPP/SPPL intramembrane proteases. Cell Mol Life Sci 2020; 77:2959-2979. [PMID: 32052089 PMCID: PMC7366577 DOI: 10.1007/s00018-020-03470-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/09/2020] [Accepted: 01/22/2020] [Indexed: 01/07/2023]
Abstract
Intramembrane proteolysis describes the cleavage of substrate proteins within their hydrophobic transmembrane segments. Several families of intramembrane proteases have been identified including the aspartyl proteases Signal peptide peptidase (SPP) and its homologues, the SPP-like (SPPL) proteases SPPL2a, SPPL2b, SPPL2c and SPPL3. As presenilin homologues, they employ a similar catalytic mechanism as the well-studied γ-secretase. However, SPP/SPPL proteases cleave transmembrane proteins with a type II topology. The characterisation of SPP/SPPL-deficient mouse models has highlighted a still growing spectrum of biological functions and also promoted the substrate discovery of these proteases. In this review, we will summarise the current hypotheses how phenotypes of these mouse models are linked to the molecular function of the enzymes. At the cellular level, SPP/SPPL-mediated cleavage events rather provide specific regulatory switches than unspecific bulk proteolysis. By this means, a plethora of different cell biological pathways is influenced including signal transduction, membrane trafficking and protein glycosylation.
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Affiliation(s)
- Torben Mentrup
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - Florencia Cabrera-Cabrera
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Faculty of Medicine, University of Augsburg, Universitätsstraße 2, 86135, Augsburg, Germany
- Biomedizinisches Centrum (BMC), Ludwig Maximilians University of Munich, Feodor-Lynen-Strasse 17, 81377, Munich, Germany
- DZNE-German Center for Neurodegenerative Diseases, Munich, Feodor-Lynen-Strasse 17, 81377, Munich, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany.
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12
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Farr L, Ghosh S, Moonah S. Role of MIF Cytokine/CD74 Receptor Pathway in Protecting Against Injury and Promoting Repair. Front Immunol 2020; 11:1273. [PMID: 32655566 PMCID: PMC7325688 DOI: 10.3389/fimmu.2020.01273] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
Wound healing after an injury is essential for life. An in-depth understanding of the healing process is necessary to ultimately improve the currently limited treatment options for patients suffering as a result of damage to various organs and tissues. Injuries, even the most minor, trigger an inflammatory response that protects the host and activates repair pathways. In recent years, substantial progress has been made in delineating the mechanisms by which inflammatory cytokines and their receptors facilitate tissue repair and regeneration. This mini review focuses on emerging literature on the role of the cytokine macrophage migration inhibitory factor (MIF) and its cell membrane receptor CD74, in protecting against injury and promoting healing in different parts of the body.
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Affiliation(s)
- Laura Farr
- Department of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Swagata Ghosh
- Department of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Shannon Moonah
- Department of Medicine, University of Virginia, Charlottesville, VA, United States
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13
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Macrophage Migration Inhibitory Factor Alters Functional Properties of CA1 Hippocampal Neurons in Mouse Brain Slices. Int J Mol Sci 2019; 21:ijms21010276. [PMID: 31906137 PMCID: PMC6981710 DOI: 10.3390/ijms21010276] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/23/2019] [Accepted: 12/24/2019] [Indexed: 02/06/2023] Open
Abstract
Neuroinflammation is implicated in a host of neurological insults, such as traumatic brain injury (TBI), ischemic stroke, Alzheimer's disease, Parkinson's disease, and epilepsy. The immune response to central nervous system (CNS) injury involves sequelae including the release of numerous cytokines and chemokines. Macrophage migration inhibitory factor (MIF), is one such cytokine that is elevated following CNS injury, and is associated with the prognosis of TBI, and ischemic stroke. MIF has been identified in astrocytes and neurons, and some of the trophic actions of MIF have been related to its direct and indirect actions on astrocytes. However, the potential modulation of CNS neuronal function by MIF has not yet been explored. This study tests the hypothesis that MIF can directly influence hippocampal neuronal function. MIF was microinjected into the hippocampus and the genetically encoded calcium indicator, GCaMP6f, was used to measure Ca2+ events in acute adult mouse brain hippocampal slices. Results demonstrated that a single injection of 200 ng MIF into the hippocampus significantly increased baseline calcium signals in CA1 pyramidal neuron somata, and altered calcium responses to N-methyl-d-aspartate (NMDA) + D-serine in pyramidal cell apical dendrites located in the stratum radiatum. These data are the first to show direct effects of MIF on hippocampal neurons and on NMDA receptor function. Considering that MIF is elevated after brain insults such as TBI, the data suggest that, in addition to the previously described role of MIF in astrocyte reactivity, elevated MIF can have significant effects on neuronal function in the hippocampus.
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14
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Penticuff JC, Woolbright BL, Sielecki TM, Weir SJ, Taylor JA. MIF family proteins in genitourinary cancer: tumorigenic roles and therapeutic potential. Nat Rev Urol 2019; 16:318-328. [DOI: 10.1038/s41585-019-0171-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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15
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Niemeyer J, Mentrup T, Heidasch R, Müller SA, Biswas U, Meyer R, Papadopoulou AA, Dederer V, Haug-Kröper M, Adamski V, Lüllmann-Rauch R, Bergmann M, Mayerhofer A, Saftig P, Wennemuth G, Jessberger R, Fluhrer R, Lichtenthaler SF, Lemberg MK, Schröder B. The intramembrane protease SPPL2c promotes male germ cell development by cleaving phospholamban. EMBO Rep 2019; 20:e46449. [PMID: 30733280 PMCID: PMC6399600 DOI: 10.15252/embr.201846449] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 12/21/2018] [Accepted: 12/21/2018] [Indexed: 11/09/2022] Open
Abstract
Signal peptide peptidase (SPP) and the four homologous SPP-like (SPPL) proteases constitute a family of intramembrane aspartyl proteases with selectivity for type II-oriented transmembrane segments. Here, we analyse the physiological function of the orphan protease SPPL2c, previously considered to represent a non-expressed pseudogene. We demonstrate proteolytic activity of SPPL2c towards selected tail-anchored proteins. Despite shared ER localisation, SPPL2c and SPP exhibit distinct, though partially overlapping substrate spectra and inhibitory profiles, and are organised in different high molecular weight complexes. Interestingly, SPPL2c is specifically expressed in murine and human testis where it is primarily localised in spermatids. In mice, SPPL2c deficiency leads to a partial loss of elongated spermatids and reduced motility of mature spermatozoa, but preserved fertility. However, matings of male and female SPPL2c-/- mice exhibit reduced litter sizes. Using proteomics we identify the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2)-regulating protein phospholamban (PLN) as a physiological SPPL2c substrate. Accumulation of PLN correlates with a decrease in intracellular Ca2+ levels in elongated spermatids that likely contribute to the compromised male germ cell differentiation and function of SPPL2c-/- mice.
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Affiliation(s)
- Johannes Niemeyer
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Torben Mentrup
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Ronny Heidasch
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Stephan A Müller
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
- Neuroproteomics, School of Medicine, Klinikum rechts der Isar and Institute for Advanced Study, Technical University of Munich, Munich, Germany
| | - Uddipta Biswas
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Rieke Meyer
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Alkmini A Papadopoulou
- Institute for Metabolic Biochemistry, Biomedical Center (BMC) München, Ludwig Maximilians University of Munich, Munich, Germany
| | - Verena Dederer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Martina Haug-Kröper
- Institute for Metabolic Biochemistry, Biomedical Center (BMC) München, Ludwig Maximilians University of Munich, Munich, Germany
| | - Vivian Adamski
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | | | - Martin Bergmann
- Institute of Veterinary Anatomy, Justus Liebig University of Gießen, Gießen, Germany
| | - Artur Mayerhofer
- Cell Biology, Anatomy III, Biomedical Center (BMC) München, Ludwig Maximilians University of Munich, Munich, Germany
| | - Paul Saftig
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Gunther Wennemuth
- Institute of Anatomy, University Hospital, Duisburg-Essen University, Essen, Germany
| | - Rolf Jessberger
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Regina Fluhrer
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
- Institute for Metabolic Biochemistry, Biomedical Center (BMC) München, Ludwig Maximilians University of Munich, Munich, Germany
| | - Stefan F Lichtenthaler
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
- Neuroproteomics, School of Medicine, Klinikum rechts der Isar and Institute for Advanced Study, Technical University of Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Marius K Lemberg
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Bernd Schröder
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany
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16
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Ancient features of the MHC class II presentation pathway, and a model for the possible origin of MHC molecules. Immunogenetics 2018; 71:233-249. [DOI: 10.1007/s00251-018-1090-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/06/2018] [Indexed: 10/28/2022]
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17
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Embedded in the Membrane: How Lipids Confer Activity and Specificity to Intramembrane Proteases. J Membr Biol 2017; 251:369-378. [PMID: 29260282 DOI: 10.1007/s00232-017-0008-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/12/2017] [Indexed: 10/18/2022]
Abstract
Proteases, sharp yet unforgivable tools of every cell, require tight regulation to ensure specific non-aberrant cleavages. The relatively recent discovered class of intramembrane proteases has gained increasing interest due to their involvement in important signaling pathways linking them to diseases including Alzheimer's disease and cancer. Despite tremendous efforts, their regulatory mechanisms have only started to unravel. There is evidence that the membrane composition itself can regulate intramembrane protease activity and specificity. In this review, we highlight the work on γ-secretase and rhomboid proteases and summarize several studies as to how different lipids impact on enzymatic activity.
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18
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Langosch D, Steiner H. Substrate processing in intramembrane proteolysis by γ-secretase - the role of protein dynamics. Biol Chem 2017; 398:441-453. [PMID: 27845877 DOI: 10.1515/hsz-2016-0269] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/08/2016] [Indexed: 01/31/2023]
Abstract
Intramembrane proteases comprise a number of different membrane proteins with different types of catalytic sites. Their common denominator is cleavage within the plane of the membrane, which usually results in peptide bond scission within the transmembrane helices of their substrates. Despite recent progress in the determination of high-resolution structures, as illustrated here for the γ-secretase complex and its substrate C99, it is still unknown how these enzymes function and how they distinguish between substrates and non-substrates. In principle, substrate/non-substrate discrimination could occur at the level of substrate binding and/or cleavage. Focusing on the γ-secretase/C99 pair, we will discuss recent observations suggesting that global motions within a substrate transmembrane helix may be much more important for defining a substrate than local unraveling at cleavage sites.
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19
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Mentrup T, Fluhrer R, Schröder B. Latest emerging functions of SPP/SPPL intramembrane proteases. Eur J Cell Biol 2017; 96:372-382. [DOI: 10.1016/j.ejcb.2017.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/28/2017] [Accepted: 03/02/2017] [Indexed: 10/20/2022] Open
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20
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Signal peptide peptidase and SPP-like proteases - Possible therapeutic targets? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017. [PMID: 28624439 DOI: 10.1016/j.bbamcr.2017.06.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Signal peptide peptidase (SPP) and the four homologous SPP-like proteases SPPL2a, SPPL2b, SPPL2c and SPPL3 are GxGD-type intramembrane-cleaving proteases (I-CLIPs). In addition to divergent subcellular localisations, distinct differences in the mechanistic properties and substrate requirements of individual family members have been unravelled. SPP/SPPL proteases employ a catalytic mechanism related to that of the γ-secretase complex. Nevertheless, differential targeting of SPP/SPPL proteases and γ-secretase by inhibitors has been demonstrated. Furthermore, also within the SPP/SPPL family significant differences in the sensitivity to currently available inhibitory compounds have been reported. Though far from complete, our knowledge on pathophysiological functions of SPP/SPPL proteases, in particular based on studies in mice, has been significantly increased over the last years. Based on this, inhibition of distinct SPP/SPPL proteases has been proposed as a novel therapeutic concept e.g. for the treatment of autoimmunity and viral or protozoal infections, as we will discuss in this review. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.
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21
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Chang H, Smallwood PM, Williams J, Nathans J. Intramembrane Proteolysis of Astrotactins. J Biol Chem 2017; 292:3506-3516. [PMID: 28100779 DOI: 10.1074/jbc.m116.768077] [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] [Received: 11/14/2016] [Revised: 01/14/2017] [Indexed: 11/06/2022] Open
Abstract
Astrotactins are vertebrate-specific membrane proteins implicated in neuron-glia interactions during central nervous system development and in hair follicle polarity during skin development. By studying epitope-tagged derivatives of mouse astrotactin-2 (Astn2) produced in transfected cells, we determined that the amino and carboxyl termini reside in the extracellular space and are initially linked by two transmembrane segments and a single cytoplasmic domain. We further show that Astn2 undergoes proteolytic cleavage in the second transmembrane domain (TM2) and that a disulfide bond holds the resulting two fragments together. Recombinant Astn1 also undergoes TM2 cleavage, as does Astn2 isolated from mouse cerebellum. Astn2 intramembrane proteolysis is insensitive to replacement of TM2 by the transmembrane domain of CD74 or by 21 alanines. However, replacement of TM2 by the transmembrane domain of CD4, the asialoglycoprotein receptor, or the transferrin receptor eliminates intramembrane proteolysis, as does leucine substitution of residues that overlap or are immediately upstream of the cleavage site. Replacement of the transmembrane domain of CD74 or the asialoglycoprotein receptor with Astn2 TM2 leads to the appearance of a carboxyl-terminal fragment consistent with intramembrane proteolysis. These experiments define a highly unusual transmembrane topology for the astrotactins, reveal intramembrane proteolysis as a feature of astrotactin maturation, and constrain the substrate sequences that are permissive for cleavage of one type 2 transmembrane segment.
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Affiliation(s)
- Hao Chang
- Departments of Molecular Biology and Genetics
| | | | | | - Jeremy Nathans
- Departments of Molecular Biology and Genetics; Neuroscience; Ophthalmology, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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22
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The biological function and significance of CD74 in immune diseases. Inflamm Res 2016; 66:209-216. [DOI: 10.1007/s00011-016-0995-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/30/2016] [Indexed: 12/25/2022] Open
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23
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Schröder B. The multifaceted roles of the invariant chain CD74--More than just a chaperone. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1269-81. [PMID: 27033518 DOI: 10.1016/j.bbamcr.2016.03.026] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 01/13/2023]
Abstract
The invariant chain (CD74) is well known for its essential role in antigen presentation by mediating assembly and subcellular trafficking of the MHCII complex. Beyond this, CD74 has also been implicated in a number of processes independent of MHCII. These include the regulation of endosomal trafficking, cell migration and cellular signalling as surface receptor of the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF). In several forms of cancer, CD74 is up-regulated and associated with enhanced proliferation and metastatic potential. In this review, an overview of the diverse biological functions of the CD74 protein is provided with a particular focus on how these may be regulated. In particular, proteolysis of CD74 will be discussed as a central mechanism to control the actions of this important protein at different levels.
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Affiliation(s)
- Bernd Schröder
- Biochemical Institute, Christian Albrechts University of Kiel, Otto-Hahn-Platz 9, D-24118 Kiel, Germany.
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