1
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Mentrup T, Leinung N, Patel M, Fluhrer R, Schröder B. The role of SPP/SPPL intramembrane proteases in membrane protein homeostasis. FEBS J 2024; 291:25-44. [PMID: 37625440 DOI: 10.1111/febs.16941] [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] [Received: 05/24/2023] [Revised: 07/03/2023] [Accepted: 08/23/2023] [Indexed: 08/27/2023]
Abstract
Signal peptide peptidase (SPP) and the four SPP-like proteases SPPL2a, SPPL2b, SPPL2c and SPPL3 constitute a family of aspartyl intramembrane proteases with homology to presenilins. The different members reside in distinct cellular localisations within the secretory pathway and the endo-lysosomal system. Despite individual cleavage characteristics, they all cleave single-span transmembrane proteins with a type II orientation exhibiting a cytosolic N-terminus. Though the identification of substrates is not complete, SPP/SPPL-mediated proteolysis appears to be rather selective. Therefore, according to our current understanding cleavage by SPP/SPPL proteases rather seems to serve a regulatory function than being a bulk proteolytic pathway. In the present review, we will summarise our state of knowledge on SPP/SPPL proteases and in particular highlight recently identified substrates and the functional and/or (patho)-physiological implications of these cleavage events. Based on this, we aim to provide an overview of the current open questions in the field. These are connected to the regulation of these proteases at the cellular level but also in context of disease and patho-physiological processes. Furthermore, the interplay with other proteostatic systems capable of degrading membrane proteins is beginning to emerge.
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Affiliation(s)
- Torben Mentrup
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Nadja Leinung
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Mehul Patel
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Germany
- Center for Interdisciplinary Health Research, University of Augsburg, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
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2
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Höppner S, Schröder B, Fluhrer R. Structure and function of SPP/SPPL proteases: insights from biochemical evidence and predictive modeling. FEBS J 2023; 290:5456-5474. [PMID: 37786993 DOI: 10.1111/febs.16968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/13/2023] [Accepted: 09/29/2023] [Indexed: 10/04/2023]
Abstract
More than 20 years ago, signal peptide peptidase (SPP) and its homologues, the signal peptide peptidase-like (SPPL) proteases have been identified based on their sequence similarity to presenilins, a related family of intramembrane aspartyl proteases. Other than those for the presenilins, no high-resolution structures for the SPP/SPPL proteases are available. Despite this limitation, over the years bioinformatical and biochemical data have accumulated, which altogether have provided a picture of the overall structure and topology of these proteases, their localization in the cell, the process of substrate recognition, their cleavage mechanism, and their function. Recently, the artificial intelligence-based structure prediction tool AlphaFold has added high-confidence models of the expected fold of SPP/SPPL proteases. In this review, we summarize known structural aspects of the SPP/SPPL family as well as their substrates. Of particular interest are the emerging substrate recognition and catalytic mechanisms that might lead to the prediction and identification of more potential substrates and deeper insight into physiological and pathophysiological roles of proteolysis.
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Affiliation(s)
- Sabine Höppner
- Biochemistry and Molecular Biology, Faculty of Medicine, Institute of Theoretical Medicine, University of Augsburg, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Technische Universität Dresden, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Faculty of Medicine, Institute of Theoretical Medicine, University of Augsburg, Germany
- Center for Interdisciplinary Health Research, University of Augsburg, Germany
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3
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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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4
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Truberg J, Hobohm L, Jochimsen A, Desel C, Schweizer M, Voss M. Endogenous tagging reveals a mid-Golgi localization of the glycosyltransferase-cleaving intramembrane protease SPPL3. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119345. [PMID: 36007678 DOI: 10.1016/j.bbamcr.2022.119345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 08/16/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Numerous Golgi-resident enzymes implicated in glycosylation are regulated by the conserved intramembrane protease SPPL3. SPPL3-catalyzed endoproteolysis separates Golgi enzymes from their membrane anchors, enabling subsequent release from the Golgi and secretion. Experimentally altered SPPL3 expression changes glycosylation patterns, yet the regulation of SPPL3-mediated Golgi enzyme cleavage is not understood and conflicting results regarding the subcellular localization of SPPL3 have been reported. Here, we used precise genome editing to generate isogenic cell lines expressing N- or C-terminally tagged SPPL3 from its endogenous locus. Using these cells, we conducted co-localization analyses of tagged endogenous SPPL3 and Golgi markers under steady-state conditions and upon treatment with drugs disrupting Golgi organization. Our data demonstrate that endogenous SPPL3 is Golgi-resident and found predominantly in the mid-Golgi. We find that endogenous SPPL3 co-localizes with its substrates but similarly with non-substrate type II proteins, demonstrating that in addition to co-localization in the Golgi other substrate-intrinsic properties govern SPPL3-mediated intramembrane proteolysis. Given the prevalence of SPPL3-mediated cleavage among Golgi-resident proteins our results have important implications for the regulation of SPPL3 and its role in the organization of the Golgi glycosylation machinery.
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Affiliation(s)
- Jule Truberg
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, D-24118 Kiel, Germany
| | - Laura Hobohm
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, D-24118 Kiel, Germany
| | - Alexander Jochimsen
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, D-24118 Kiel, Germany
| | - Christine Desel
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, D-24118 Kiel, Germany
| | - Michaela Schweizer
- Morphology and Electron Microscopy, University Medical Center Hamburg-Eppendorf, Center for Molecular Neurobiology (ZMNH), 20251 Hamburg, Germany
| | - Matthias Voss
- Institute of Biochemistry, Kiel University, Rudolf-Höber-Str. 1, D-24118 Kiel, Germany.
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5
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Ballin M, Griep W, Patel M, Karl M, Mentrup T, Rivera‐Monroy J, Foo B, Schwappach B, Schröder B. The intramembrane proteases
SPPL2a
and
SPPL2b
regulate the homeostasis of selected
SNARE
proteins. FEBS J 2022; 290:2320-2337. [PMID: 36047592 DOI: 10.1111/febs.16610] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/28/2022] [Accepted: 08/30/2022] [Indexed: 01/15/2023]
Abstract
Signal peptide peptidase (SPP) and SPP-like (SPPL) aspartyl intramembrane proteases are known to contribute to sequential processing of type II-oriented membrane proteins referred to as regulated intramembrane proteolysis. The ER-resident family members SPP and SPPL2c were shown to also cleave tail-anchored proteins, including selected SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins facilitating membrane fusion events. Here, we analysed whether the related SPPL2a and SPPL2b proteases, which localise to the endocytic or late secretory pathway, are also able to process SNARE proteins. Therefore, we screened 18 SNARE proteins for cleavage by SPPL2a and SPPL2b based on cellular co-expression assays, of which the proteins VAMP1, VAMP2, VAMP3 and VAMP4 were processed by SPPL2a/b demonstrating the capability of these two proteases to proteolyse tail-anchored proteins. Cleavage of the four SNARE proteins was scrutinised at the endogenous level upon SPPL2a/b inhibition in different cell lines as well as by analysing VAMP1-4 levels in tissues and primary cells of SPPL2a/b double-deficient (dKO) mice. Loss of SPPL2a/b activity resulted in an accumulation of VAMP1-4 in a cell type- and tissue-dependent manner, identifying these proteins as SPPL2a/b substrates validated in vivo. Therefore, we propose that SPPL2a/b control cellular levels of VAMP1-4 by initiating the degradation of these proteins, which might impact cellular trafficking.
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Affiliation(s)
- Moritz Ballin
- Biochemical Institute Christian Albrechts University Kiel Kiel Germany
- Institute of Physiological Chemistry Technische Universität Dresden Dresden Germany
| | - Wolfram Griep
- Biochemical Institute Christian Albrechts University Kiel Kiel Germany
- Institute of Physiological Chemistry Technische Universität Dresden Dresden Germany
| | - Mehul Patel
- Institute of Physiological Chemistry Technische Universität Dresden Dresden Germany
| | - Martin Karl
- Institute of Physiological Chemistry Technische Universität Dresden Dresden Germany
| | - Torben Mentrup
- Institute of Physiological Chemistry Technische Universität Dresden Dresden Germany
| | - Jhon Rivera‐Monroy
- Department of Molecular Biology University Medical Center Göttingen Göttingen Germany
| | - Brian Foo
- Department of Molecular Biology University Medical Center Göttingen Göttingen Germany
| | - Blanche Schwappach
- Department of Molecular Biology University Medical Center Göttingen Göttingen Germany
| | - Bernd Schröder
- Institute of Physiological Chemistry Technische Universität Dresden Dresden Germany
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6
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Mentrup T, Stumpff-Niggemann AY, Leinung N, Schlosser C, Schubert K, Wehner R, Tunger A, Schatz V, Neubert P, Gradtke AC, Wolf J, Rose-John S, Saftig P, Dalpke A, Jantsch J, Schmitz M, Fluhrer R, Jacobsen ID, Schröder B. Phagosomal signalling of the C-type lectin receptor Dectin-1 is terminated by intramembrane proteolysis. Nat Commun 2022; 13:1880. [PMID: 35388002 PMCID: PMC8987071 DOI: 10.1038/s41467-022-29474-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/14/2022] [Indexed: 11/23/2022] Open
Abstract
Sensing of pathogens by pattern recognition receptors (PRR) is critical to initiate protective host defence reactions. However, activation of the immune system has to be carefully titrated to avoid tissue damage necessitating mechanisms to control and terminate PRR signalling. Dectin-1 is a PRR for fungal β-glucans on immune cells that is rapidly internalised after ligand-binding. Here, we demonstrate that pathogen recognition by the Dectin-1a isoform results in the formation of a stable receptor fragment devoid of the ligand binding domain. This fragment persists in phagosomal membranes and contributes to signal transduction which is terminated by the intramembrane proteases Signal Peptide Peptidase-like (SPPL) 2a and 2b. Consequently, immune cells lacking SPPL2b demonstrate increased anti-fungal ROS production, killing capacity and cytokine responses. The identified mechanism allows to uncouple the PRR signalling response from delivery of the pathogen to degradative compartments and identifies intramembrane proteases as part of a regulatory circuit to control anti-fungal immune responses. Dectin-1 is a critical component of the innate sensing repertoire which is involved in pattern based recognition of fungal pathogens. Here the authors show that intramembrane proteolysis is involved in the regulation of the antifungal host response by termination of the phagosomal signalling of Dectin-1.
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Affiliation(s)
- Torben Mentrup
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | | | - Nadja Leinung
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Christine Schlosser
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Katja Schubert
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Rebekka Wehner
- Institute of Immunology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany.,German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Antje Tunger
- Institute of Immunology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany
| | - Valentin Schatz
- Institute of Clinical Microbiology and Hygiene, University Hospital of Regensburg and University of Regensburg, Regensburg, Germany
| | - Patrick Neubert
- Institute of Clinical Microbiology and Hygiene, University Hospital of Regensburg and University of Regensburg, Regensburg, Germany
| | - Ann-Christine Gradtke
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Janina Wolf
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Stefan Rose-John
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Paul Saftig
- Biochemical Institute, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Alexander Dalpke
- Institute of Medical Microbiology and Virology, University Hospital Carl Gustav Carus, Medical Faculty, Technische Universität Dresden, Dresden, Germany
| | - Jonathan Jantsch
- Institute of Clinical Microbiology and Hygiene, University Hospital of Regensburg and University of Regensburg, Regensburg, Germany
| | - Marc Schmitz
- Institute of Immunology, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.,National Center for Tumor Diseases (NCT), Partner Site Dresden, Dresden, Germany.,German Cancer Consortium (DKTK), Partner Site Dresden, Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Ilse D Jacobsen
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany.,Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Bernd Schröder
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.
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7
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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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8
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Novikova G, Kapoor M, Tcw J, Abud EM, Efthymiou AG, Chen SX, Cheng H, Fullard JF, Bendl J, Liu Y, Roussos P, Björkegren JL, Liu Y, Poon WW, Hao K, Marcora E, Goate AM. Integration of Alzheimer's disease genetics and myeloid genomics identifies disease risk regulatory elements and genes. Nat Commun 2021; 12:1610. [PMID: 33712570 PMCID: PMC7955030 DOI: 10.1038/s41467-021-21823-y] [Citation(s) in RCA: 100] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 02/10/2021] [Indexed: 02/07/2023] Open
Abstract
Genome-wide association studies (GWAS) have identified more than 40 loci associated with Alzheimer's disease (AD), but the causal variants, regulatory elements, genes and pathways remain largely unknown, impeding a mechanistic understanding of AD pathogenesis. Previously, we showed that AD risk alleles are enriched in myeloid-specific epigenomic annotations. Here, we show that they are specifically enriched in active enhancers of monocytes, macrophages and microglia. We integrated AD GWAS with myeloid epigenomic and transcriptomic datasets using analytical approaches to link myeloid enhancer activity to target gene expression regulation and AD risk modification. We identify AD risk enhancers and nominate candidate causal genes among their likely targets (including AP4E1, AP4M1, APBB3, BIN1, MS4A4A, MS4A6A, PILRA, RABEP1, SPI1, TP53INP1, and ZYX) in twenty loci. Fine-mapping of these enhancers nominates candidate functional variants that likely modify AD risk by regulating gene expression in myeloid cells. In the MS4A locus we identified a single candidate functional variant and validated it in human induced pluripotent stem cell (hiPSC)-derived microglia and brain. Taken together, this study integrates AD GWAS with multiple myeloid genomic datasets to investigate the mechanisms of AD risk alleles and nominates candidate functional variants, regulatory elements and genes that likely modulate disease susceptibility.
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Affiliation(s)
- Gloriia Novikova
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Manav Kapoor
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Julia Tcw
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Edsel M Abud
- Department of Neurobiology & Behavior, University of California Irvine, Irvine, CA, USA
- Sue and Bill Gross Stem Cell Research Center, University of California Irvine, Irvine, CA, USA
| | - Anastasia G Efthymiou
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Steven X Chen
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Haoxiang Cheng
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John F Fullard
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jaroslav Bendl
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yiyuan Liu
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Panos Roussos
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Johan Lm Björkegren
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Integrated Cardio Metabolic Centre, Department of Medicine, Karolinska Institutet, Karolinska Universitetssjukhuset, Huddinge, Sweden
| | - Yunlong Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wayne W Poon
- Institute for Memory Impairments and Neurological Disorders, University of California Irvine, Irvine, CA, USA
| | - Ke Hao
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Edoardo Marcora
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Alison M Goate
- Ronald M. Loeb Center for Alzheimer's Disease, Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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9
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Gradtke AC, Mentrup T, Lehmann CHK, Cabrera-Cabrera F, Desel C, Okakpu D, Assmann M, Dalpke A, Schaible UE, Dudziak D, Schröder B. Deficiency of the Intramembrane Protease SPPL2a Alters Antimycobacterial Cytokine Responses of Dendritic Cells. THE JOURNAL OF IMMUNOLOGY 2021; 206:164-180. [PMID: 33239420 DOI: 10.4049/jimmunol.2000151] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 10/30/2020] [Indexed: 12/30/2022]
Abstract
Signal peptide peptidase-like 2a (SPPL2a) is an aspartyl intramembrane protease essential for degradation of the invariant chain CD74. In humans, absence of SPPL2a leads to Mendelian susceptibility to mycobacterial disease, which is attributed to a loss of the dendritic cell (DC) subset conventional DC2. In this study, we confirm depletion of conventional DC2 in lymphatic tissues of SPPL2a-/- mice and demonstrate dependence on CD74 using SPPL2a-/- CD74-/- mice. Upon contact with mycobacteria, SPPL2a-/- bone marrow-derived DCs show enhanced secretion of IL-1β, whereas production of IL-10 and IFN-β is reduced. These effects correlated with modulated responses upon selective stimulation of the pattern recognition receptors TLR4 and Dectin-1. In SPPL2a-/- bone marrow-derived DCs, Dectin-1 is redistributed to endosomal compartments. Thus, SPPL2a deficiency alters pattern recognition receptor pathways in a CD74-dependent way, shifting the balance from anti- to proinflammatory cytokines in antimycobacterial responses. We propose that in addition to the DC reduction, this altered DC functionality contributes to Mendelian susceptibility to mycobacterial disease upon SPPL2a deficiency.
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Affiliation(s)
- Ann-Christine Gradtke
- Institute of Physiological Chemistry, Technische Universität Dresden, D-01307 Dresden, Germany
| | - Torben Mentrup
- Institute of Physiological Chemistry, Technische Universität Dresden, D-01307 Dresden, Germany
| | - Christian H K Lehmann
- Laboratory of Dendritic Cell Biology, Department of Dermatology, Friedrich-Alexander University Erlangen-Nürnberg, University Hospital Erlangen, D-91052 Erlangen, Germany.,Medical Immunology Campus Erlangen, D-91054 Erlangen, Germany.,Deutsches Zentrum Immuntherapie, D-91054 Erlangen, Germany.,Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg, D-91054 Erlangen, Germany
| | - Florencia Cabrera-Cabrera
- Institute of Physiological Chemistry, Technische Universität Dresden, D-01307 Dresden, Germany.,Biochemical Institute, Christian-Albrechts-University Kiel, D-24118 Kiel, Germany
| | - Christine Desel
- Biochemical Institute, Christian-Albrechts-University Kiel, D-24118 Kiel, Germany
| | - Darian Okakpu
- Institute of Physiological Chemistry, Technische Universität Dresden, D-01307 Dresden, Germany
| | - Maike Assmann
- Priority Program Infections, Division of Cellular Microbiology, Research Center Borstel, Leibniz Lung Center, and German Center for Infection Research, partner site Borstel, D-23845 Borstel, Germany; and
| | - Alexander Dalpke
- Institute of Medical Microbiology and Hygiene, Technische Universität Dresden, D-01307 Dresden, Germany
| | - Ulrich E Schaible
- Priority Program Infections, Division of Cellular Microbiology, Research Center Borstel, Leibniz Lung Center, and German Center for Infection Research, partner site Borstel, D-23845 Borstel, Germany; and
| | - Diana Dudziak
- Laboratory of Dendritic Cell Biology, Department of Dermatology, Friedrich-Alexander University Erlangen-Nürnberg, University Hospital Erlangen, D-91052 Erlangen, Germany.,Medical Immunology Campus Erlangen, D-91054 Erlangen, Germany.,Deutsches Zentrum Immuntherapie, D-91054 Erlangen, Germany.,Comprehensive Cancer Center Erlangen-European Metropolitan Area of Nuremberg, D-91054 Erlangen, Germany
| | - Bernd Schröder
- Institute of Physiological Chemistry, Technische Universität Dresden, D-01307 Dresden, Germany;
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10
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Papadopoulou AA, Fluhrer R. Signaling Functions of Intramembrane Aspartyl-Proteases. Front Cardiovasc Med 2020; 7:591787. [PMID: 33381526 PMCID: PMC7768045 DOI: 10.3389/fcvm.2020.591787] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/16/2020] [Indexed: 01/18/2023] Open
Abstract
Intramembrane proteolysis is more than a mechanism to “clean” the membranes from proteins no longer needed. By non-reversibly modifying transmembrane proteins, intramembrane cleaving proteases hold key roles in multiple signaling pathways and often distinguish physiological from pathological conditions. Signal peptide peptidase (SPP) and signal peptide peptidase-like proteases (SPPLs) recently have been associated with multiple functions in the field of signal transduction. SPP/SPPLs together with presenilins (PSs) are the only two families of intramembrane cleaving aspartyl proteases known in mammals. PS1 or PS2 comprise the catalytic center of the γ-secretase complex, which is well-studied in the context of Alzheimer's disease. The mammalian SPP/SPPL family of intramembrane cleaving proteases consists of five members: SPP and its homologous proteins SPPL2a, SPPL2b, SPPL2c, and SPPL3. Although these proteases were discovered due to their homology to PSs, it became evident in the past two decades that no physiological functions are shared between these two families. Based on studies in cell culture models various substrates of SPP/SPPL proteases have been identified in the past years and recently-developed mouse lines lacking individual members of this protease family, will help to further clarify the physiological functions of these proteases. In this review we concentrate on signaling roles of mammalian intramembrane cleaving aspartyl proteases. In particular, we will highlight the signaling roles of PS via its substrates NOTCH, VEGF, and others, mainly focusing on its involvement in vasculature. Delineating also signaling pathways that are affected and/or controlled by SPP/SPPL proteases. From SPP's participation in tumor progression and survival, to SPPL3's regulation of protein glycosylation and SPPL2c's control over cellular calcium stores, various crossovers between proteolytic activity of intramembrane proteases and cell signaling will be described.
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Affiliation(s)
- Alkmini A Papadopoulou
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Augsburg, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
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11
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Podleśny-Drabiniok A, Marcora E, Goate AM. Microglial Phagocytosis: A Disease-Associated Process Emerging from Alzheimer’s Disease Genetics. Trends Neurosci 2020; 43:965-979. [DOI: 10.1016/j.tins.2020.10.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/02/2020] [Accepted: 10/05/2020] [Indexed: 01/02/2023]
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12
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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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13
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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: 21] [Impact Index Per Article: 5.3] [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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14
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Papadopoulou AA, Müller SA, Mentrup T, Shmueli MD, Niemeyer J, Haug-Kröper M, von Blume J, Mayerhofer A, Feederle R, Schröder B, Lichtenthaler SF, Fluhrer R. Signal peptide peptidase-like 2c impairs vesicular transport and cleaves SNARE proteins. EMBO Rep 2019; 20:e46451. [PMID: 30733281 PMCID: PMC6399617 DOI: 10.15252/embr.201846451] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 12/07/2018] [Accepted: 12/21/2018] [Indexed: 12/25/2022] Open
Abstract
Members of the GxGD-type intramembrane aspartyl proteases have emerged as key players not only in fundamental cellular processes such as B-cell development or protein glycosylation, but also in development of pathologies, such as Alzheimer's disease or hepatitis virus infections. However, one member of this protease family, signal peptide peptidase-like 2c (SPPL2c), remains orphan and its capability of proteolysis as well as its physiological function is still enigmatic. Here, we demonstrate that SPPL2c is catalytically active and identify a variety of SPPL2c candidate substrates using proteomics. The majority of the SPPL2c candidate substrates cluster to the biological process of vesicular trafficking. Analysis of selected SNARE proteins reveals proteolytic processing by SPPL2c that impairs vesicular transport and causes retention of cargo proteins in the endoplasmic reticulum. As a consequence, the integrity of subcellular compartments, in particular the Golgi, is disturbed. Together with a strikingly high physiological SPPL2c expression in testis, our data suggest involvement of SPPL2c in acrosome formation during spermatogenesis.
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Affiliation(s)
- Alkmini A Papadopoulou
- Institute for Metabolic Biochemistry, Biomedical Center (BMC), Ludwig-Maximilians University Munich, Munich, Germany
| | - Stephan A Müller
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Torben Mentrup
- Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Merav D Shmueli
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
- Neuroproteomics, School of Medicine, Klinikum Rechts der Isar, and Institute for Advanced Study, Technical University Munich, Munich, Germany
| | - Johannes Niemeyer
- Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Martina Haug-Kröper
- Institute for Metabolic Biochemistry, Biomedical Center (BMC), Ludwig-Maximilians University Munich, Munich, Germany
| | | | - Artur Mayerhofer
- Cell Biology, Anatomy III, Biomedical Center (BMC), Ludwig-Maximilians University Munich, Munich, Germany
| | - Regina Feederle
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
- Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
- Munich Center for Systems Neurology (SyNergy), Munich, Germany
| | - Bernd Schröder
- Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
- Institute for Physiological Chemistry, Technische Universität Dresden, Dresden, 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 Munich, Munich, Germany
- Munich Center for Systems Neurology (SyNergy), Munich, Germany
| | - Regina Fluhrer
- Institute for Metabolic Biochemistry, Biomedical Center (BMC), Ludwig-Maximilians University Munich, Munich, Germany
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
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15
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Mentrup T, Theodorou K, Cabrera-Cabrera F, Helbig AO, Happ K, Gijbels M, Gradtke AC, Rabe B, Fukumori A, Steiner H, Tholey A, Fluhrer R, Donners M, Schröder B. Atherogenic LOX-1 signaling is controlled by SPPL2-mediated intramembrane proteolysis. J Exp Med 2019; 216:807-830. [PMID: 30819724 PMCID: PMC6446863 DOI: 10.1084/jem.20171438] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 08/21/2018] [Accepted: 10/17/2018] [Indexed: 11/27/2022] Open
Abstract
The intramembrane proteases SPPL2a/b control pro-atherogenic signaling of membrane-bound proteolytic fragments derived from the oxLDL receptor LOX-1. In mice deficient for these proteases, plaque development and fibrosis is enhanced. This highlights SPPL2a/b as crucial players of a novel athero-protective mechanism, which is conserved in humans. The lectin-like oxidized LDL receptor 1 (LOX-1) is a key player in the development of atherosclerosis. LOX-1 promotes endothelial activation and dysfunction by mediating uptake of oxidized LDL and inducing pro-atherogenic signaling. However, little is known about modulators of LOX-1–mediated responses. Here, we show that the function of LOX-1 is controlled proteolytically. Ectodomain shedding by the metalloprotease ADAM10 and lysosomal degradation generate membrane-bound N-terminal fragments (NTFs), which we identified as novel substrates of the intramembrane proteases signal peptide peptidase–like 2a and b (SPPL2a/b). SPPL2a/b control cellular LOX-1 NTF levels which, following self-association via their transmembrane domain, can activate MAP kinases in a ligand-independent manner. This leads to an up-regulation of several pro-atherogenic and pro-fibrotic targets including ICAM-1 and the connective tissue growth factor CTGF. Consequently, SPPL2a/b-deficient mice, which accumulate LOX-1 NTFs, develop larger and more advanced atherosclerotic plaques than controls. This identifies intramembrane proteolysis by SPPL2a/b as a novel atheroprotective mechanism via negative regulation of LOX-1 signaling.
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Affiliation(s)
- Torben Mentrup
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany.,Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Kosta Theodorou
- Department of Pathology, Cardiovascular Research Institute, Maastricht University, Maastricht, Netherlands
| | - Florencia Cabrera-Cabrera
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany.,Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Andreas O Helbig
- Systematic Proteome Research and Bioanalytics, Institute for Experimental Medicine, Christian Albrechts University of Kiel, Kiel, Germany
| | - Kathrin Happ
- Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Marion Gijbels
- Department of Pathology, Cardiovascular Research Institute, Maastricht University, Maastricht, Netherlands.,Department of Molecular Genetics, Cardiovascular Research Institute, Maastricht University, Maastricht, Netherlands.,Amsterdam Cardiovascular Sciences, Department of Medical Biochemistry, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Ann-Christine Gradtke
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany.,Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Björn Rabe
- Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
| | - Akio Fukumori
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Harald Steiner
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Biomedical Center, Metabolic Biochemistry, Ludwig Maximilians University of Munich, Munich, Germany
| | - Andreas Tholey
- Systematic Proteome Research and Bioanalytics, Institute for Experimental Medicine, Christian Albrechts University of Kiel, Kiel, Germany
| | - Regina Fluhrer
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Biomedical Center, Metabolic Biochemistry, Ludwig Maximilians University of Munich, Munich, Germany
| | - Marjo Donners
- Department of Pathology, Cardiovascular Research Institute, Maastricht University, Maastricht, Netherlands
| | - Bernd Schröder
- Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany .,Biochemical Institute, Christian Albrechts University of Kiel, Kiel, Germany
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16
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Jules F, Sauvageau E, Dumaresq-Doiron K, Mazzaferri J, Haug-Kröper M, Fluhrer R, Costantino S, Lefrancois S. CLN5 is cleaved by members of the SPP/SPPL family to produce a mature soluble protein. Exp Cell Res 2017; 357:40-50. [PMID: 28442266 DOI: 10.1016/j.yexcr.2017.04.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/19/2017] [Accepted: 04/21/2017] [Indexed: 11/30/2022]
Abstract
The Neuronal ceroid lipofuscinoses (NCLs) are a group of recessive disorders of childhood with overlapping symptoms including vision loss, ataxia, cognitive regression and premature death. 14 different genes have been linked to NCLs (CLN1-CLN14), but the functions of the proteins encoded by the majority of these genes have not been fully elucidated. Mutations in the CLN5 gene are responsible for the Finnish variant late-infantile form of NCL (Finnish vLINCL). CLN5 is translated as a 407 amino acid transmembrane domain containing protein that is heavily glycosylated, and subsequently cleaved into a mature soluble protein. Functionally, CLN5 is implicated in the recruitment of the retromer complex to endosomes, which is required to sort the lysosomal sorting receptors from endosomes to the trans-Golgi network. The mechanism that processes CLN5 into a mature soluble protein is currently not known. Herein, we demonstrate that CLN5 is initially translated as a type II transmembrane protein and subsequently cleaved by SPPL3, a member of the SPP/SPPL intramembrane protease family, into a mature soluble protein consisting of residues 93-407. The remaining N-terminal fragment is then cleaved by SPPL3 and SPPL2b and degraded in the proteasome. This work further characterizes the biology of CLN5 in the hopes of identifying a novel therapeutic strategy for affected children.
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Affiliation(s)
- Felix Jules
- Centre INRS-Institut Armand-Frappier, INRS, Laval, Canada H7V 1B7
| | | | | | - Javier Mazzaferri
- Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Canada H1T 2M4
| | - Martina Haug-Kröper
- Biomedical Center (BMC), Institute for Metabolic Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Regina Fluhrer
- Biomedical Center (BMC), Institute for Metabolic Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany; DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Santiago Costantino
- Département d'Ophtalmologie et Institut de Génie Biomédical, Université de Montréal, Montréal, Canada H3T 1J4; Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Canada H1T 2M4
| | - Stephane Lefrancois
- Centre INRS-Institut Armand-Frappier, INRS, Laval, Canada H7V 1B7; Department of Anatomy and Cell Biology, McGill University, Montreal, Canada H3A 2B2.
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17
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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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18
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Fritsch J, Zingler P, Särchen V, Heck AL, Schütze S. Role of ubiquitination and proteolysis in the regulation of pro- and anti-apoptotic TNF-R1 signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2138-2146. [PMID: 28765050 DOI: 10.1016/j.bbamcr.2017.07.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/25/2017] [Accepted: 07/27/2017] [Indexed: 02/07/2023]
Abstract
Tumor Necrosis Factor Receptor 1 (TNF-R1) transmits various intracellular signaling cascades leading to diverse biological outcomes, ranging from proliferation, differentiation, survival to the induction of various forms of cell death (i.e. apoptosis, necrosis, necroptosis). These signaling pathways have to be tightly regulated. Proteolysis is an important regulatory mechanism in TNF-R1 pro-apoptotic as well as anti-apoptotic/pro-inflammatory signaling. Some key players in these signaling cascades are known (mainly the caspase-family of proteases and a previously unrecognized "lysosomal death pathway" involving cathepsins), however the interaction of proteases in the regulation of TNF signaling is still enigmatic. Ubiquitination of proteins, both non-degradative degradative, which either results in proteolytic degradation of target substrates or regulates their biological function, represents another layer of regulation in this signaling cascade. We and others found out that the differences in signal quality depend on the localization of the receptors. Plasma membrane resident receptors activate survival signals, while endocytosed receptors can induce cell death. In this article we will review the role of ubiquitination and proteolysis in these diverse events focusing on our own contributions to the lysosomal apoptotic pathway linked to the subcellular compartmentalization of TNF-R1. 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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Affiliation(s)
- Jürgen Fritsch
- Institute of Immunology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Philipp Zingler
- Institute of Immunology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Vinzenz Särchen
- Institute of Immunology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Anna Laura Heck
- Institute of Immunology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Stefan Schütze
- Institute of Immunology, Christian-Albrechts-University of Kiel, Kiel, Germany.
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19
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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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20
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Elgner F, Ren H, Medvedev R, Ploen D, Himmelsbach K, Boller K, Hildt E. The Intracellular Cholesterol Transport Inhibitor U18666A Inhibits the Exosome-Dependent Release of Mature Hepatitis C Virus. J Virol 2016; 90:11181-11196. [PMID: 27707921 PMCID: PMC5126375 DOI: 10.1128/jvi.01053-16] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/28/2016] [Indexed: 12/18/2022] Open
Abstract
Hepatitis C virus (HCV) particles are described as lipoviroparticles which are released similarly to very-low-density lipoproteins (VLDLs). However, the release mechanism is still poorly understood; the canonical endoplasmic reticulum-Golgi intermediate compartment (ERGIC) pathway as well as endosome-dependent release has been proposed. Recently, the role of exosomes in the transmission of HCV has been reported. Only a minor fraction of the de novo-synthesized lipoviroparticles is released by the infected cell. To investigate the relevance of multivesicular bodies (MVBs) for viral morphogenesis and release, the MVB inhibitor U18666A was used. Intracellular trafficking was analyzed by confocal microscopy and electron microscopy. Moreover, an mCherry-tagged HCV variant was used. Conditions were established that enable U18666A-dependent inhibition of MVBs without affecting viral replication. Under these conditions, significant inhibition of the HCV release was observed. The assembly of viral particles is not affected. In U18666A-treated cells, intact infectious viral particles accumulate in CD63-positive exosomal structures and large dysfunctional lysosomal structures (multilamellar bodies). These retained particles possess a lower density, reflecting a misloading with lipids. Our data indicate that at least a fraction of HCV particles leaves the cell via the endosomal pathway. Endosomes facilitate the sorting of HCV particles for release or degradation. IMPORTANCE There are still a variety of open questions regarding morphogenesis and release of hepatitis C virus. The HCV-infected cell produces significant more viral particles that are released, raising the question about the fate of the nonreleased particles. Moreover, the relevance of the endosomal pathway for the release of HCV is under debate. Use of the MVB (multivesicular body) inhibitor U18666A enabled a detailed analysis of the impact of MVBs for viral morphogenesis and release. It was revealed that infectious, fully assembled HCV particles are either MVB-dependently released or intracellularly degraded by the lysosome. Our data indicate that at least a fraction of HCV particles leaves the cell via the endosomal pathway independent from the constitutive secretory pathway. Our study describes a so-far-unprecedented cross talk between two pathways regulating on the one hand the release of infectious viral particles and on the other hand the intracellular degradation of nonreleased particles.
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Affiliation(s)
- Fabian Elgner
- Paul-Ehrlich-Institut, Department of Virology, Langen, Germany
| | - Huimei Ren
- Paul-Ehrlich-Institut, Department of Virology, Langen, Germany
| | - Regina Medvedev
- Paul-Ehrlich-Institut, Department of Virology, Langen, Germany
| | - Daniela Ploen
- Paul-Ehrlich-Institut, Department of Virology, Langen, Germany
| | | | - Klaus Boller
- Paul-Ehrlich-Institut, Department of Virology, Langen, Germany
| | - Eberhard Hildt
- Paul-Ehrlich-Institut, Department of Virology, Langen, Germany
- Deutsches Zentrum für Infektionsforschung, Braunschweig, Germany
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21
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Schröder B, Saftig P. Intramembrane proteolysis within lysosomes. Ageing Res Rev 2016; 32:51-64. [PMID: 27143694 DOI: 10.1016/j.arr.2016.04.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 04/01/2016] [Accepted: 04/26/2016] [Indexed: 11/26/2022]
Abstract
Regulated intramembrane proteolysis is of pivotal importance in a diverse set of developmental and physiological processes. Altered intramembrane substrate turnover may be associated with neurodegeneration, cancer and impaired immune function. In this review we will focus on the intramembrane proteases which have been localized in the lysosomal membrane. Members of the γ-secretase complex and γ-secretase activity are found in the lysosomal membrane and are discussed to contribute to intracellular amyloid β production. Mutant or deficient γ-secretase may cause disturbed lysosomal function. The signal peptide peptidase-like (SPPL) protease 2a is a lysosomal membrane component and cleaves CD74, the invariant chain of the MHC II complex, as well as FasL, TNF, ITM2B and TMEM106, type II transmembrane proteins involved in the regulation of immunity and neurodegeneration. Therefore, it can be concluded, that not only proteolysis within the lysosomal lumen but also within lysosomal membranes regulates important cellular functions and contributes essentially to proteostasis of membrane proteins what may become increasingly compromised in the aged individual.
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22
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Substrate determinants of signal peptide peptidase-like 2a (SPPL2a)-mediated intramembrane proteolysis of the invariant chain CD74. Biochem J 2016; 473:1405-22. [DOI: 10.1042/bcj20160156] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 03/16/2016] [Indexed: 11/17/2022]
Abstract
Intramembrane proteolysis of CD74 by SPPL2a is essential for B- and dendritic cells. We show that CD74 is proteolysed in the luminal third of the transmembrane segment and identify determinants within its transmembrane and luminal membrane-proximal domain facilitating this cleavage.
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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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24
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Hüttl S, Kläsener K, Schweizer M, Schneppenheim J, Oberg HH, Kabelitz D, Reth M, Saftig P, Schröder B. Processing of CD74 by the Intramembrane Protease SPPL2a Is Critical for B Cell Receptor Signaling in Transitional B Cells. THE JOURNAL OF IMMUNOLOGY 2015; 195:1548-63. [PMID: 26157172 DOI: 10.4049/jimmunol.1403171] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 06/09/2015] [Indexed: 12/16/2022]
Abstract
The invariant chain (CD74), a chaperone in MHC class II-mediated Ag presentation, is sequentially processed by different endosomal proteases. We reported recently that clearance of the final membrane-bound N-terminal fragment (NTF) of CD74 is mediated by the intramembrane protease signal peptide peptidase-like (SPPL)2a, a process critical for B cell development. In mice, SPPL2a deficiency provokes the accumulation of this NTF in endocytic vesicles, which leads to a B cell maturation arrest at the transitional 1 stage. To define the underlying mechanism, we analyzed the impact of SPPL2a deficiency on signaling pathways involved in B cell homeostasis. We demonstrate that tonic as well as BCR-induced activation of the PI3K/Akt pathway is massively compromised in SPPL2a(-/-) B cells and identify this as major cause of the B cell maturation defect in these mice. Altered BCR trafficking induces a reduction of surface IgM in SPPL2a-deficient B cells, leading to a diminished signal transmission via the BCR and the tyrosine kinase Syk. We provide evidence that in SPPL2a(-/-) mice impaired BCR signaling is to a great extent provoked by the accumulating CD74 NTF, which can interact with the BCR and Syk, and that impaired PI3K/Akt signaling and reduced surface IgM are not directly linked processes. In line with disturbances in PI3K/Akt signaling, SPPL2a(-/-) B cells show a dysregulation of the transcription factor FOXO1, causing elevated transcription of proapoptotic genes. We conclude that SPPL2a-mediated processing of CD74 NTF is indispensable to maintain appropriate levels of tonic BCR signaling to promote B cell maturation.
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Affiliation(s)
- Susann Hüttl
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany
| | - Kathrin Kläsener
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany; Institute for Biology III, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany; Max Planck Institute for Immunobiology and Epigenetics, D-79108 Freiburg, Germany
| | - Michaela Schweizer
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Janna Schneppenheim
- Institute of Anatomy, Christian Albrechts University of Kiel, D-24118 Kiel, Germany; and
| | - Hans-Heinrich Oberg
- Institute of Immunology, Christian Albrechts University of Kiel, D-24105 Kiel, Germany
| | - Dieter Kabelitz
- Institute of Immunology, Christian Albrechts University of Kiel, D-24105 Kiel, Germany
| | - Michael Reth
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany; Institute for Biology III, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany; Max Planck Institute for Immunobiology and Epigenetics, D-79108 Freiburg, Germany
| | - Paul Saftig
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany
| | - Bernd Schröder
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany;
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Mentrup T, Häsler R, Fluhrer R, Saftig P, Schröder B. A Cell-Based Assay Reveals Nuclear Translocation of Intracellular Domains Released by SPPL Proteases. Traffic 2015; 16:871-92. [DOI: 10.1111/tra.12287] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 03/26/2015] [Accepted: 03/26/2015] [Indexed: 12/27/2022]
Affiliation(s)
- Torben Mentrup
- Biochemical Institute; Christian Albrechts University of Kiel; Otto-Hahn-Platz 9 D-24118 Kiel Germany
| | - Robert Häsler
- Institute of Clinical Molecular Biology; Christian Albrechts University of Kiel; Schittenhelmstr. 12 D-24105 Kiel Germany
| | - Regina Fluhrer
- Biomedizinisches Centrum (BMC); Ludwig Maximilians University of Munich; Feodor-Lynen-Strasse 17 D-81377 Munich Germany
- DZNE - German Center for Neurodegenerative Diseases; Feodor-Lynen-Strasse 17 D-81377 Munich Germany
| | - Paul Saftig
- Biochemical Institute; Christian Albrechts University of Kiel; Otto-Hahn-Platz 9 D-24118 Kiel Germany
| | - Bernd Schröder
- Biochemical Institute; Christian Albrechts University of Kiel; Otto-Hahn-Platz 9 D-24118 Kiel Germany
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26
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Voss M, Künzel U, Higel F, Kuhn PH, Colombo A, Fukumori A, Haug-Kröper M, Klier B, Grammer G, Seidl A, Schröder B, Obst R, Steiner H, Lichtenthaler SF, Haass C, Fluhrer R. Shedding of glycan-modifying enzymes by signal peptide peptidase-like 3 (SPPL3) regulates cellular N-glycosylation. EMBO J 2014; 33:2890-905. [PMID: 25354954 DOI: 10.15252/embj.201488375] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Protein N-glycosylation is involved in a variety of physiological and pathophysiological processes such as autoimmunity, tumour progression and metastasis. Signal peptide peptidase-like 3 (SPPL3) is an intramembrane-cleaving aspartyl protease of the GxGD type. Its physiological function, however, has remained enigmatic, since presently no physiological substrates have been identified. We demonstrate that SPPL3 alters the pattern of cellular N-glycosylation by triggering the proteolytic release of active site-containing ectodomains of glycosidases and glycosyltransferases such as N-acetylglucosaminyltransferase V, β-1,3 N-acetylglucosaminyltransferase 1 and β-1,4 galactosyltransferase 1. Cleavage of these enzymes leads to a reduction in their cellular activity. In line with that, reduced expression of SPPL3 results in a hyperglycosylation phenotype, whereas elevated SPPL3 expression causes hypoglycosylation. Thus, SPPL3 plays a central role in an evolutionary highly conserved post-translational process in eukaryotes.
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Affiliation(s)
- Matthias Voss
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Ulrike Künzel
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Fabian Higel
- Sandoz Biopharmaceuticals/HEXAL AG, Oberhaching, Germany
| | - Peer-Hendrik Kuhn
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany Institute for Advanced Study, Technische Universität München, Garching, Germany
| | - Alessio Colombo
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Akio Fukumori
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Martina Haug-Kröper
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Bärbel Klier
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Gudula Grammer
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Andreas Seidl
- Sandoz Biopharmaceuticals/HEXAL AG, Oberhaching, Germany
| | - Bernd Schröder
- Biochemical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Reinhard Obst
- Institute for Immunology, Ludwig-Maximilians University Munich, Munich, Germany
| | - Harald Steiner
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Stefan F Lichtenthaler
- DZNE - German Center for Neurodegenerative Diseases, Munich, Germany Munich Cluster for Systems Neurology (SyNergy), Munich, Germany Neuroproteomics, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Christian Haass
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany DZNE - German Center for Neurodegenerative Diseases, Munich, Germany Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Regina Fluhrer
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
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Signal-peptide-peptidase-like 2a is required for CD74 intramembrane proteolysis in human B cells. Biochem Biophys Res Commun 2014; 451:48-53. [PMID: 25035924 DOI: 10.1016/j.bbrc.2014.07.051] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 07/10/2014] [Indexed: 01/16/2023]
Abstract
The invariant chain (CD74) mediates targeting of the MHCII complex to endosomal compartments, where CD74 undergoes degradation allowing MHCII to acquire peptides. We demonstrated recently that intramembrane proteolysis of the final membrane-bound N-terminal fragment (NTF) of CD74 is catalyzed by Signal-peptide-peptidase-like 2a (SPPL2a) and that this process is indispensable for development and function of B lymphocytes in mice. In SPPL2a(-/-) mice, homeostasis of these cells is disturbed by the accumulation of the unprocessed CD74 NTF. So far, evidence for this essential role of SPPL2a is restricted to mice. Nevertheless, inhibition of SPPL2a has been suggested as novel approach to target B cells for treating autoimmunity. Here, we characterize human B cell lines with a homozygous microdeletion on chromosome 15. We demonstrate that this deletion disrupts the SPPL2a genomic locus and leads to loss of SPPL2a transcript. Lymphoblastoid cell lines from patients with this deletion exhibit absence of SPPL2a at the protein level and show an accumulation of the CD74 NTF comparable to B cells from SPPL2a(-/-) mice. By this means, we present evidence that the role of SPPL2a in CD74 proteolysis is conserved in human B cells and provide support for modulation of SPPL2a activity as a therapeutic concept.
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28
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Brady OA, Zhou X, Hu F. Regulated intramembrane proteolysis of the frontotemporal lobar degeneration risk factor, TMEM106B, by signal peptide peptidase-like 2a (SPPL2a). J Biol Chem 2014; 289:19670-80. [PMID: 24872421 DOI: 10.1074/jbc.m113.515700] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The sequential processing of single pass transmembrane proteins via ectodomain shedding followed by intramembrane proteolysis is involved in a wide variety of signaling processes, as well as maintenance of membrane protein homeostasis. Here we report that the recently identified frontotemporal lobar degeneration risk factor TMEM106B undergoes regulated intramembrane proteolysis. We demonstrate that TMEM106B is readily processed to an N-terminal fragment containing the transmembrane and intracellular domains, and this processing is dependent on the activities of lysosomal proteases. The N-terminal fragment is further processed into a small, rapidly degraded intracellular domain. The GxGD aspartyl proteases SPPL2a and, to a lesser extent, SPPL2b are responsible for this intramembrane cleavage event. Additionally, the TMEM106B paralog TMEM106A is also lysosomally localized; however, it is not a specific substrate of SPPL2a or SPPL2b. Our data add to the growing list of proteins that undergo intramembrane proteolysis and may shed light on the regulation of the frontotemporal lobar degeneration risk factor TMEM106B.
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Affiliation(s)
- Owen A Brady
- From the Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
| | - Xiaolai Zhou
- From the Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
| | - Fenghua Hu
- From the Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853
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29
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The intramembrane proteases signal Peptide peptidase-like 2a and 2b have distinct functions in vivo. Mol Cell Biol 2014; 34:1398-411. [PMID: 24492962 DOI: 10.1128/mcb.00038-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We reported recently that the presenilin homologue signal peptide peptidase-like 2a (SPPL2a) is essential for B cell development by cleaving the N-terminal fragment (NTF) of the invariant chain (li, CD74). Based on this, we suggested that pharmacological modulation of SPPL2a may represent a novel approach to deplete B cells in autoimmune disorders. With regard to reported overlapping substrate spectra of SPPL2a and its close homologue, SPPL2b, we investigated the role of SPPL2b in CD74 NTF proteolysis and its impact on B and dendritic cell homeostasis. In heterologous expression experiments, SPPL2b was found to cleave CD74 NTF with an efficiency similar to that of SPPL2a. For in vivo analysis, SPPL2b single-deficient and SPPL2a/SPPL2b double-deficient mice were generated and examined for CD74 NTF turnover/accumulation, B cell maturation and functionality, and dendritic cell homeostasis. We demonstrate that in vivo SPPL2b does not exhibit a physiologically relevant contribution to CD74 proteolysis in B and dendritic cells. Furthermore, we reveal that both proteases exhibit divergent subcellular localizations in B cells and different expression profiles in murine tissues. These findings suggest distinct functions of SPPL2a and SPPL2b and, based on a high abundance of SPPL2b in brain, a physiological role of this protease in the central nervous system.
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30
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Voss M, Schröder B, Fluhrer R. Mechanism, specificity, and physiology of signal peptide peptidase (SPP) and SPP-like proteases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2828-39. [PMID: 24099004 DOI: 10.1016/j.bbamem.2013.03.033] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 01/09/2023]
Abstract
Signal peptide peptidase (SPP) and the homologous SPP-like (SPPL) proteases SPPL2a, SPPL2b, SPPL2c and SPPL3 belong to the family of GxGD intramembrane proteases. SPP/SPPLs selectively cleave transmembrane domains in type II orientation and do not require additional co-factors for proteolytic activity. Orthologues of SPP and SPPLs have been identified in other vertebrates, plants, and eukaryotes. In line with their diverse subcellular localisations ranging from the ER (SPP, SPPL2c), the Golgi (SPPL3), the plasma membrane (SPPL2b) to lysosomes/late endosomes (SPPL2a), the different members of the SPP/SPPL family seem to exhibit distinct functions. Here, we review the substrates of these proteases identified to date as well as the current state of knowledge about the physiological implications of these proteolytic events as deduced from in vivo studies. Furthermore, the present knowledge on the structure of intramembrane proteases of the SPP/SPPL family, their cleavage mechanism and their substrate requirements are summarised. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Matthias Voss
- Adolf Butenandt Institute for Biochemistry, Ludwig-Maximilians University Munich, Schillerstr. 44, 80336 Munich, Germany
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31
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Bronckers ALJJ, Gueneli N, Lüllmann-Rauch R, Schneppenheim J, Moraru AP, Himmerkus N, Bervoets TJ, Fluhrer R, Everts V, Saftig P, Schröder B. The intramembrane protease SPPL2A is critical for tooth enamel formation. J Bone Miner Res 2013; 28:1622-30. [PMID: 23426979 DOI: 10.1002/jbmr.1895] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/06/2013] [Accepted: 02/11/2013] [Indexed: 12/15/2022]
Abstract
Intramembrane proteases are critically involved in signal transduction and membrane protein turnover. Signal-peptide-peptidase-like 2a (SPPL2A), a presenilin-homologue residing in lysosomes/late endosomes, cleaves type II-oriented transmembrane proteins. We recently identified SPPL2A as the enzyme controlling turnover and functions of the invariant chain (CD74) of the major histocompatibility complex II (MHCII) and demonstrated critical importance of this process for B cell development. Surprisingly, we found that SPPL2A is critical for formation of dental enamel. In Sppl2a knockout mice, enamel of the erupted incisors was chalky white and rapidly eroded after eruption. SPPL2A was found to be expressed in enamel epithelium during secretory and maturation stage amelogenesis. Mineral content of enamel in Sppl2a⁻/⁻ incisors was inhomogeneous and reduced by ∼20% compared to wild-type mice with the most pronounced reduction at the mesial side. Frequently, disruption of the enamel layer and localized detachment of the most superficial enamel layer was observed in the knockout incisors leading to an uneven enamel surface. In Sppl2a null mice, morphology and function of secretory stage ameloblasts were not noticeably different from that of wild-type mice. However, maturation stage ameloblasts showed reduced height and a characteristic undulation of the ameloblast layer with localized adherence of the cells to the outer enamel. This was reflected in a delayed and incomplete resorption of the proteinaceous enamel matrix. Thus, we conclude that intramembrane proteolysis by SPPL2A is essential for maintaining cellular homeostasis of ameloblasts. Because modulation of SPPL2A activity appears to be an attractive therapeutic target to deplete B cells and treat autoimmunity, interference with tooth enamel formation should be investigated as a possible adverse effect of pharmacological SPPL2A inhibitors in humans.
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32
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Schwake M, Schröder B, Saftig P. Lysosomal membrane proteins and their central role in physiology. Traffic 2013; 14:739-48. [PMID: 23387372 DOI: 10.1111/tra.12056] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/01/2013] [Accepted: 02/06/2013] [Indexed: 12/19/2022]
Abstract
The lysosomal membrane was thought for a long time to primarily act as a physical barrier separating the luminal acidic milieu from the cytoplasmic environment. Meanwhile, it has been realized that unique lysosomal membranes play essential roles in a number of cellular events ranging from phagocytosis, autophagy, cell death, virus infection to membrane repair. This review provides an overview about the most interesting emerging functions of lysosomal membrane proteins and how they contribute to health and disease. Their importance is exemplified by their role in acidification, transport of metabolites and ions across the membrane, intracellular transport of hydrolases and the regulation of membrane fusion events. Studies in patient cells, non-mammalian model organisms and knockout mice contributed to our understanding of how the different lysosomal membrane proteins affect cellular homeostasis, developmental processes as well as tissue functions. Because these proteins are central for the biogenesis of this compartment they are also considered as attractive targets to modulate the lysosomal machinery in cases where impaired lysosomal degradation leads to cellular pathologies. We are only beginning to understand the complex composition and function of these proteins which are tightly linked to processes occurring throughout the endocytic and biosynthetic pathways.
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Affiliation(s)
- Michael Schwake
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098, Kiel, Germany
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33
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Morohashi Y, Tomita T. Protein trafficking and maturation regulate intramembrane proteolysis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2855-61. [PMID: 23770323 DOI: 10.1016/j.bbamem.2013.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 05/04/2013] [Accepted: 06/03/2013] [Indexed: 12/30/2022]
Abstract
Intramembrane-cleaving proteases (I-CLiPs) are membrane embedded proteolytic enzymes. All substrates identified so far are also membrane proteins, involving a number of critical cellular signaling as well as human diseases. After synthesis and assembly at the endoplasmic reticulum, membrane proteins are exported to the Golgi apparatus and transported to their sites of action. A number of studies have revealed the importance of the intracellular membrane trafficking in i-CLiP-mediated intramembrane proteolysis, not only for limiting the unnecessary encounter between i-CLiPs and their substrate but also for their cleavage site preference. In this review, we will discuss recent advances in our understanding of how each i-CLiP proteolysis is regulated by intracellular vesicle trafficking. This article is part of a Special Issue entitled: Intramembrane Proteases.
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Affiliation(s)
- Yuichi Morohashi
- Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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34
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Xiang L, Etxeberria E, den Ende W. Vacuolar protein sorting mechanisms in plants. FEBS J 2013; 280:979-93. [DOI: 10.1111/febs.12092] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 11/08/2012] [Accepted: 12/11/2012] [Indexed: 01/12/2023]
Affiliation(s)
- Li Xiang
- Laboratory of Molecular Plant Biology KU Leuven Belgium
| | - Ed Etxeberria
- Horticulture Department Citrus Research and Education Center University of Florida Lake Alfred FL USA
| | - Wim den Ende
- Laboratory of Molecular Plant Biology KU Leuven Belgium
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Bergmann H, Yabas M, Short A, Miosge L, Barthel N, Teh CE, Roots CM, Bull KR, Jeelall Y, Horikawa K, Whittle B, Balakishnan B, Sjollema G, Bertram EM, Mackay F, Rimmer AJ, Cornall RJ, Field MA, Andrews TD, Goodnow CC, Enders A. B cell survival, surface BCR and BAFFR expression, CD74 metabolism, and CD8- dendritic cells require the intramembrane endopeptidase SPPL2A. ACTA ACUST UNITED AC 2012; 210:31-40. [PMID: 23267016 PMCID: PMC3549710 DOI: 10.1084/jem.20121076] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mice lacking activity of the intramembrane protease SPPL2A exhibit humoral immunodeficiency and lack mature B cell subsets. Druggable proteins required for B lymphocyte survival and immune responses are an emerging source of new treatments for autoimmunity and lymphoid malignancy. In this study, we show that mice with an inactivating mutation in the intramembrane protease signal peptide peptidase–like 2A (SPPL2A) unexpectedly exhibit profound humoral immunodeficiency and lack mature B cell subsets, mirroring deficiency of the cytokine B cell–activating factor (BAFF). Accumulation of Sppl2a-deficient B cells was rescued by overexpression of the BAFF-induced survival protein B cell lymphoma 2 (BCL2) but not BAFF and was distinguished by low surface BAFF receptor and IgM and IgD B cell receptors. CD8-negative dendritic cells were also greatly decreased. SPPL2A deficiency blocked the proteolytic processing of CD74 MHC II invariant chain in both cell types, causing dramatic build-up of the p8 product of Cathepsin S and interfering with earlier steps in CD74 endosomal retention and processing. The findings illuminate an important role for the final step in the CD74–MHC II pathway and a new target for protease inhibitor treatment of B cell diseases.
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Affiliation(s)
- Hannes Bergmann
- Ramaciotti Immunization Genomics Laboratory, John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory 2600, Australia
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36
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Schneppenheim J, Dressel R, Hüttl S, Lüllmann-Rauch R, Engelke M, Dittmann K, Wienands J, Eskelinen EL, Hermans-Borgmeyer I, Fluhrer R, Saftig P, Schröder B. The intramembrane protease SPPL2a promotes B cell development and controls endosomal traffic by cleavage of the invariant chain. ACTA ACUST UNITED AC 2012; 210:41-58. [PMID: 23267015 PMCID: PMC3549707 DOI: 10.1084/jem.20121069] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The intramembrane protease SPPL2a cleaves the NTF of invariant chain (CD74), which is essential for normal trafficking of MHC class II–containing endosomes and thus for B cell development and function. Regulated intramembrane proteolysis is a central cellular process involved in signal transduction and membrane protein turnover. The presenilin homologue signal-peptide-peptidase-like 2a (SPPL2a) has been implicated in the cleavage of type 2 transmembrane proteins. We show that the invariant chain (li, CD74) of the major histocompatability class II complex (MHCII) undergoes intramembrane proteolysis mediated by SPPL2a. B lymphocytes of SPPL2a−/− mice accumulate an N-terminal fragment (NTF) of CD74, which severely impairs membrane traffic within the endocytic system and leads to an altered response to B cell receptor stimulation, reduced BAFF-R surface expression, and accumulation of MHCII in transitional developmental stage T1 B cells. This results in significant loss of B cell subsets beyond the T1 stage and disrupted humoral immune responses, which can be recovered by additional ablation of CD74. Hence, we provide evidence that regulation of CD74-NTF levels by SPPL2a is indispensable for B cell development and function by maintaining trafficking and integrity of MHCII-containing endosomes, highlighting SPPL2a as a promising pharmacological target for depleting and/or modulating B cells.
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Affiliation(s)
- Janna Schneppenheim
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany
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37
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Bourin M, Gautron J, Berges M, Hennequet-Antier C, Cabau C, Nys Y, Réhault-Godbert S. Transcriptomic profiling of proteases and antiproteases in the liver of sexually mature hens in relation to vitellogenesis. BMC Genomics 2012; 13:457. [PMID: 22950364 PMCID: PMC3495648 DOI: 10.1186/1471-2164-13-457] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 08/22/2012] [Indexed: 11/15/2022] Open
Abstract
Background Most egg yolk precursors are synthesized by the liver, secreted into the blood and transferred into oocytes, to provide nutrients and bioactive molecules for the avian embryo. Three hundred and sixteen distinct proteins have been identified in egg yolk. These include 37 proteases and antiproteases, which are likely to play a role in the formation of the yolk (vitellogenesis), as regulators of protein metabolism. We used a transcriptomic approach to define the protease and antiprotease genes specifically expressed in the hen liver in relation to vitellogenesis by comparing sexually mature and pre-laying chickens showing different steroid milieu. Results Using a 20 K chicken oligoarray, a total of 582 genes were shown to be over-expressed in the liver of sexually mature hens (1.2 to 67 fold-differences). Eight of the top ten over-expressed genes are known components of the egg yolk or perivitelline membrane. This list of 582 genes contains 12 proteases and 3 antiproteases. We found that “uncharacterized protein LOC419301/similar to porin” (GeneID:419301), an antiprotease and “cathepsin E-A-like/similar to nothepsin” (GeneID:417848), a protease, were the only over-expressed candidates (21-fold and 35-fold difference, respectively) that are present in the egg yolk. Additionally, we showed the 4-fold over-expression of “ovochymase-2/similar to oviductin” (GeneID:769290), a vitelline membrane-specific protease. Conclusions Our approach revealed that three proteases and antiproteases are likely to participate in the formation of the yolk. The role of the other 12 proteases and antiproteases which are over-expressed in our model remains unclear. At least 1/3 of proteases and antiproteases identified in egg yolk and vitelline membrane proteomes are expressed similarly in the liver regardless of the maturity of hens, and have been initially identified as regulators of haemostasis and inflammatory events. The lack of effect of sex steroids on these genes expressed in the liver but the products of which are found in the yolk suggests that these may be passively incorporated into the yolk rather than actively produced for that purpose. These results raise the question of the biological significance of egg yolk proteases and antiproteases, and more generally of all minor proteins that have been identified in egg yolk.
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Affiliation(s)
- Marie Bourin
- INRA, SIGENAE, UR83 Recherches Avicoles, 37380, F-37380 Nouzilly, France
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