1
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Avci D, Heidasch R, Costa M, Lüchtenborg C, Kale D, Brügger B, Lemberg MK. Intramembrane protease SPP defines a cholesterol-regulated abundance control of the mevalonate pathway enzyme squalene synthase. J Biol Chem 2024; 300:105644. [PMID: 38218226 PMCID: PMC10850959 DOI: 10.1016/j.jbc.2024.105644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 01/15/2024] Open
Abstract
Intramembrane proteolysis regulates important processes such as signaling and transcriptional and posttranslational abundance control of proteins with key functions in metabolic pathways. This includes transcriptional control of mevalonate pathway genes, thereby ensuring balanced biosynthesis of cholesterol and other isoprenoids. Our work shows that, at high cholesterol levels, signal peptide peptidase (SPP) cleaves squalene synthase (SQS), an enzyme that defines the branching point for allocation of isoprenoids to the sterol and nonsterol arms of the mevalonate pathway. This intramembrane cleavage releases SQS from the membrane and targets it for proteasomal degradation. Regulation of this mechanism is achieved by the E3 ubiquitin ligase TRC8 that, in addition to ubiquitinating SQS in response to cholesterol levels, acts as an allosteric activator of SPP-catalyzed intramembrane cleavage of SQS. Cellular cholesterol levels increase in the absence of SPP activity. We infer from these results that, SPP-TRC8 mediated abundance control of SQS acts as a regulation step within the mevalonate pathway.
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Affiliation(s)
- Dönem Avci
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
| | - Ronny Heidasch
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Martina Costa
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | | | - Dipali Kale
- Biochemistry Center of Heidelberg University (BZH), Heidelberg, Germany
| | - Britta Brügger
- Biochemistry Center of Heidelberg University (BZH), Heidelberg, Germany
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany.
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2
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Sakson R, Beedgen L, Bernhard P, Alp KM, Lübbehusen N, Röth R, Niesler B, Luzarowski M, Shevchuk O, Mayer MP, Thiel C, Ruppert T. Targeted Proteomics Reveals Quantitative Differences in Low-Abundance Glycosyltransferases of Patients with Congenital Disorders of Glycosylation. Int J Mol Sci 2024; 25:1191. [PMID: 38256263 PMCID: PMC10816918 DOI: 10.3390/ijms25021191] [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: 12/23/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Protein glycosylation is an essential post-translational modification in all domains of life. Its impairment in humans can result in severe diseases named congenital disorders of glycosylation (CDGs). Most of the glycosyltransferases (GTs) responsible for proper glycosylation are polytopic membrane proteins that represent challenging targets in proteomics. We established a multiple reaction monitoring (MRM) assay to comprehensively quantify GTs involved in the processes of N-glycosylation and O- and C-mannosylation in the endoplasmic reticulum. High robustness was achieved by using an enriched membrane protein fraction of isotopically labeled HEK 293T cells as an internal protein standard. The analysis of primary skin fibroblasts from eight CDG type I patients with impaired ALG1, ALG2, and ALG11 genes, respectively, revealed a substantial reduction in the corresponding protein levels. The abundance of the other GTs, however, remained unchanged at the transcript and protein levels, indicating that there is no fail-safe mechanism for the early steps of glycosylation in the endoplasmic reticulum. The established MRM assay was shared with the scientific community via the commonly used open source Skyline software environment, including Skyline Batch for automated data analysis. We demonstrate that another research group could easily reproduce all analysis steps, even while using different LC-MS hardware.
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Affiliation(s)
- Roman Sakson
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
- Heidelberg Biosciences International Graduate School (HBIGS), Heidelberg University, 69120 Heidelberg, Germany
| | - Lars Beedgen
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Patrick Bernhard
- Institute for Surgical Pathology, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - K. Merve Alp
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
| | - Nicole Lübbehusen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Ralph Röth
- nCounter Core Facility, Institute of Human Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Beate Niesler
- nCounter Core Facility, Institute of Human Genetics, University Hospital Heidelberg, 69120 Heidelberg, Germany
- Interdisciplinary Center for Neurosciences, Heidelberg University, 69120 Heidelberg, Germany
| | - Marcin Luzarowski
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Olga Shevchuk
- Department of Immunodynamics, Institute of Experimental Immunology and Imaging, University Hospital Essen, 45147 Essen, Germany
| | - Matthias P. Mayer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Christian Thiel
- Center for Child and Adolescent Medicine, Department Pediatrics I, Heidelberg University, 69120 Heidelberg, Germany
| | - Thomas Ruppert
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
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3
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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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4
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Daskivich GJ, Brodsky JL. The generation of detergent-insoluble clipped fragments from an ERAD substrate in mammalian cells. Sci Rep 2023; 13:21508. [PMID: 38057493 PMCID: PMC10700608 DOI: 10.1038/s41598-023-48769-z] [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: 07/28/2023] [Accepted: 11/30/2023] [Indexed: 12/08/2023] Open
Abstract
Proteostasis ensures the proper synthesis, folding, and trafficking of proteins and is required for cellular and organellar homeostasis. This network also oversees protein quality control within the cell and prevents accumulation of aberrant proteins, which can lead to cellular dysfunction and disease. For example, protein aggregates irreversibly disrupt proteostasis and can exert gain-of-function toxic effects. Although this process has been examined in detail for cytosolic proteins, how endoplasmic reticulum (ER)-tethered, aggregation-prone proteins are handled is ill-defined. To determine how a membrane protein with a cytoplasmic aggregation-prone domain is routed for ER-associated degradation (ERAD), we analyzed a new model substrate, TM-Ubc9ts. In yeast, we previously showed that TM-Ubc9ts ERAD requires Hsp104, which is absent in higher cells. In transient and stable HEK293 cells, we now report that TM-Ubc9ts degradation is largely proteasome-dependent, especially at elevated temperatures. In contrast to yeast, clipped TM-Ubc9ts polypeptides, which are stabilized upon proteasome inhibition, accumulate and are insoluble at elevated temperatures. TM-Ubc9ts cleavage is independent of the intramembrane protease RHBDL4, which clips other classes of ERAD substrates. These studies highlight an unappreciated mechanism underlying the degradation of aggregation-prone substrates in the ER and invite further work on other proteases that contribute to ERAD.
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Affiliation(s)
- Grant J Daskivich
- A320 Langley Hall, Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Jeffrey L Brodsky
- A320 Langley Hall, Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
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5
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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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6
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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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7
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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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8
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Congenital disorder of glycosylation caused by starting site-specific variant in syntaxin-5. Nat Commun 2021; 12:6227. [PMID: 34711829 PMCID: PMC8553859 DOI: 10.1038/s41467-021-26534-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 10/05/2021] [Indexed: 12/26/2022] Open
Abstract
The SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein syntaxin-5 (Stx5) is essential for Golgi transport. In humans, the STX5 mRNA encodes two protein isoforms, Stx5 Long (Stx5L) from the first starting methionine and Stx5 Short (Stx5S) from an alternative starting methionine at position 55. In this study, we identify a human disorder caused by a single missense substitution in the second starting methionine (p.M55V), resulting in complete loss of the short isoform. Patients suffer from an early fatal multisystem disease, including severe liver disease, skeletal abnormalities and abnormal glycosylation. Primary human dermal fibroblasts isolated from these patients show defective glycosylation, altered Golgi morphology as measured by electron microscopy, mislocalization of glycosyltransferases, and compromised ER-Golgi trafficking. Measurements of cognate binding SNAREs, based on biotin-synchronizable forms of Stx5 (the RUSH system) and Förster resonance energy transfer (FRET), revealed that the short isoform of Stx5 is essential for intra-Golgi transport. Alternative starting codons of Stx5 are thus linked to human disease, demonstrating that the site of translation initiation is an important new layer of regulating protein trafficking.
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9
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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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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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Jiang H. Quality control pathways of tail-anchored proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118922. [PMID: 33285177 DOI: 10.1016/j.bbamcr.2020.118922] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/14/2020] [Accepted: 12/01/2020] [Indexed: 12/20/2022]
Abstract
Tail-anchored (TA) proteins have an N-terminal domain in the cytosol and a C-terminal transmembrane domain anchored to a variety of organelle membranes. TA proteins are recognized by targeting factors at the transmembrane domain and C-terminal sequence and are guided to distinct membranes. The promiscuity of targeting sequences and the dysfunction of targeting pathways cause mistargeting of TA proteins. TA proteins are under surveillance by quality control pathways. For resident TA proteins at mitochondrial and ER membranes, intrinsic instability or stimuli induced degrons of the cytosolic and transmembrane domains are sensed by quality control factors to initiate degradation of TA proteins. These pathways are summarized as TA protein degradation-Cytosol (TAD-C) and TAD-Membrane (TAD-M) pathways. For mistargeted and a subset of solitary TA proteins at mitochondrial and peroxisomal membranes, a unique pathway has been revealed in recent years. Msp1/ATAD1 is an AAA-ATPase dually-localized to mitochondrial and peroxisomal membranes. It directly recognizes mistargeted and solitary TA proteins and dislocates them out of membrane. Dislocated substrates are subsequently ubiquitinated by the ER-resident Doa10 ubiquitin E3 ligase complex for degradation. We summarize and discuss the substrate recognition, dislocation and degradation mechanisms of the Msp1 pathway.
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Affiliation(s)
- Hui Jiang
- National Institute of Biological Sciences, Beijing 102206, China; Beijing Key Laboratory of Cell Biology for Animal Aging, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100871, China.
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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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Kühnle N, Dederer V, Lemberg MK. Intramembrane proteolysis at a glance: from signalling to protein degradation. J Cell Sci 2019; 132:132/16/jcs217745. [DOI: 10.1242/jcs.217745] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
ABSTRACT
Over the last two decades, a group of unusual proteases, so-called intramembrane proteases, have become increasingly recognized for their unique ability to cleave peptide bonds within cellular membranes. They are found in all kingdoms of life and fulfil versatile functions ranging from protein maturation, to activation of signalling molecules, to protein degradation. In this Cell Science at a Glance article and the accompanying poster, we focus on intramembrane proteases in mammalian cells. By comparing intramembrane proteases in different cellular organelles, we set out to review their functions within the context of the roles of individual cellular compartments. Additionally, we exemplify their mode of action in relation to known substrates by distinguishing cleavage events that promote degradation of substrate from those that release active domains from the membrane bilayer.
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Affiliation(s)
- Nathalie Kühnle
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Verena Dederer
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Marius K. Lemberg
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
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15
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Linders PT, Horst CVD, Beest MT, van den Bogaart G. Stx5-Mediated ER-Golgi Transport in Mammals and Yeast. Cells 2019; 8:cells8080780. [PMID: 31357511 PMCID: PMC6721632 DOI: 10.3390/cells8080780] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 07/25/2019] [Accepted: 07/25/2019] [Indexed: 01/12/2023] Open
Abstract
The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) syntaxin 5 (Stx5) in mammals and its ortholog Sed5p in Saccharomyces cerevisiae mediate anterograde and retrograde endoplasmic reticulum (ER)-Golgi trafficking. Stx5 and Sed5p are structurally highly conserved and are both regulated by interactions with other ER-Golgi SNARE proteins, the Sec1/Munc18-like protein Scfd1/Sly1p and the membrane tethering complexes COG, p115, and GM130. Despite these similarities, yeast Sed5p and mammalian Stx5 are differently recruited to COPII-coated vesicles, and Stx5 interacts with the microtubular cytoskeleton, whereas Sed5p does not. In this review, we argue that these different Stx5 interactions contribute to structural differences in ER-Golgi transport between mammalian and yeast cells. Insight into the function of Stx5 is important given its essential role in the secretory pathway of eukaryotic cells and its involvement in infections and neurodegenerative diseases.
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Affiliation(s)
- Peter Ta Linders
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Chiel van der Horst
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Martin Ter Beest
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Geert van den Bogaart
- Tumor Immunology Lab, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands.
- Department of Molecular Immunology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
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16
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Young HS, Lemieux MJ. Regulating the regulator: intramembrane proteolysis of vesicular trafficking proteins and the SERCA regulator phospholamban. EMBO Rep 2019; 20:embr.201947792. [PMID: 30804015 DOI: 10.15252/embr.201947792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Howard S Young
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, AB, Canada
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