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Brinkley DM, Smith KC, Fink EC, Kwen W, Yoo NH, West Z, Sullivan NL, Farthing AS, Hale VA, Goutte C. Notch signaling without the APH-2/nicastrin subunit of gamma secretase in Caenorhabditis elegans germline stem cells. Genetics 2024; 227:iyae076. [PMID: 38717968 DOI: 10.1093/genetics/iyae076] [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: 03/22/2024] [Accepted: 05/01/2024] [Indexed: 07/09/2024] Open
Abstract
The final step in Notch signaling activation is the transmembrane cleavage of Notch receptor by γ secretase. Thus far, genetic and biochemical evidence indicates that four subunits are essential for γ secretase activity in vivo: presenilin (the catalytic core), APH-1, PEN-2, and APH-2/nicastrin. Although some γ secretase activity has been detected in APH-2/nicastrin-deficient mammalian cell lines, the lack of biological relevance for this activity has left the quaternary γ secretase model unchallenged. Here, we provide the first example of in vivo Notch signal transduction without APH-2/nicastrin. The surprising dispensability of APH-2/nicastrin is observed in Caenorhabditis elegans germline stem cells (GSCs) and contrasts with its essential role in previously described C. elegans Notch signaling events. Depletion of GLP-1/Notch, presenilin, APH-1, or PEN-2 causes a striking loss of GSCs. In contrast, aph-2/nicastrin mutants maintain GSCs and exhibit robust and localized expression of the downstream Notch target sygl-1. Interestingly, APH-2/nicastrin is normally expressed in GSCs and becomes essential under conditions of compromised Notch function. Further insight is provided by reconstituting the C. elegans γ secretase complex in yeast, where we find that APH-2/nicastrin increases but is not essential for γ secretase activity. Together, our results are most consistent with a revised model of γ secretase in which the APH-2/nicastrin subunit has a modulatory, rather than obligatory role. We propose that a trimeric presenilin-APH-1-PEN-2 γ secretase complex can provide a low level of γ secretase activity, and that cellular context determines whether or not APH-2/nicastrin is essential for effective Notch signal transduction.
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Affiliation(s)
- David M Brinkley
- Program in Biochemistry and Biophysics, Amherst College, Amherst, MA 01002, USA
| | - Karen C Smith
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Emma C Fink
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Woohyun Kwen
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Nina H Yoo
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Zachary West
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Nora L Sullivan
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Alex S Farthing
- Program in Biochemistry and Biophysics, Amherst College, Amherst, MA 01002, USA
| | - Valerie A Hale
- Department of Biology, Amherst College, Amherst, MA 01002, USA
| | - Caroline Goutte
- Program in Biochemistry and Biophysics, Amherst College, Amherst, MA 01002, USA
- Department of Biology, Amherst College, Amherst, MA 01002, USA
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Sharrouf K, Schlosser C, Mildenberger S, Fluhrer R, Hoeppner S. In vitro cleavage of tumor necrosis factor α (TNFα) by Signal-Peptide-Peptidase-like 2b (SPPL2b) resembles mechanistic principles observed in the cellular context. Chem Biol Interact 2024; 395:111006. [PMID: 38636792 DOI: 10.1016/j.cbi.2024.111006] [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: 12/22/2023] [Revised: 03/27/2024] [Accepted: 04/14/2024] [Indexed: 04/20/2024]
Abstract
Members of the Signal Peptide-Peptidase (SPP) and Signal Peptide-Peptidase-like (SPPL) family are intramembrane aspartyl-proteases like their well-studied homologs, the presenilins, which comprise the catalytically active subunit within the γ-secretase complex. The lack of in vitro cleavage assays for SPPL proteases limited their biochemical characterization as well as substrate identification and validation. So far, SPPL proteases have been analyzed exclusively in intact cells or membranes, restricting mechanistic analysis to co-expression of enzyme and substrate variants colocalizing in the same subcellular compartments. We describe the details of developing an in vitro cleavage assay for SPPL2b and its model substrate TNFα and analyzed the influence of phospholipids, detergent supplements, and cholesterol on the SPPL2b in vitro activity. SPPL2b in vitro activity resembles mechanistic principles that have been observed in a cellular context, such as cleavage sites and consecutive turnover of the TNFα transmembrane domain. The novel in vitro cleavage assay is functional with separately isolated protease and substrate and amenable to a high throughput plate-based readout overcoming previous limitations and providing the basis for studying enzyme kinetics, catalytic activity, substrate recognition, and the characteristics of small molecule inhibitors. As a proof of concept, we present the first biochemical in vitro characterization of the SPPL2a and SPPL2b specific small molecule inhibitor SPL-707.
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Affiliation(s)
- Kinda Sharrouf
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätsstrasse 2, D-86159, Augsburg, Germany
| | - Christine Schlosser
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätsstrasse 2, D-86159, Augsburg, Germany
| | - Sandra Mildenberger
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätsstrasse 2, D-86159, Augsburg, Germany; Institut für Entwicklungsbiologie und Neurobiologie, Johannes Gutenberg-Universität Mainz, Hanns-Dieter-Hüsch-Weg 15, 55099, Mainz, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätsstrasse 2, D-86159, Augsburg, Germany; University of Augsburg, Center for Interdisciplinary Health Research, 86135, Augsburg, Germany
| | - Sabine Hoeppner
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätsstrasse 2, D-86159, Augsburg, Germany.
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Li G, Zhu W, Tian M, Liu R, Ruan Y, Liu C. Genome-Wide Identification of the SPP/SPPL Gene Family and BnaSPPL4 Regulating Male Fertility in Rapeseed ( Brassica napus L.). Int J Mol Sci 2024; 25:3936. [PMID: 38612746 PMCID: PMC11012144 DOI: 10.3390/ijms25073936] [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: 02/27/2024] [Revised: 03/23/2024] [Accepted: 03/31/2024] [Indexed: 04/14/2024] Open
Abstract
Signal peptide peptidase (SPP) and its homologs, signal peptide peptidase-like (SPPL) proteases, are members of the GxGD-type aspartyl protease family, which is widespread in plants and animals and is a class of transmembrane proteins with significant biological functions. SPP/SPPLs have been identified; however, the functions of SPP/SPPL in rapeseed (Brassica napus L.) have not been reported. In this study, 26 SPP/SPPLs were identified in rapeseed and categorized into three groups: SPP, SPPL2, and SPPL3. These members mainly contained the Peptidase_A22 and PA domains, which were distributed on 17 out of 19 chromosomes. Evolutionary analyses indicated that BnaSPP/SPPLs evolved with a large number of whole-genome duplication (WGD) events and strong purifying selection. Members are widely expressed and play a key role in the growth and development of rapeseed. The regulation of rapeseed pollen fertility by the BnaSPPL4 gene was further validated through experiments based on bioinformatics analysis, concluding that BnaSPPL4 silencing causes male sterility. Cytological observation showed that male infertility caused by loss of BnaSPPL4 gene function occurs late in the mononucleate stage due to microspore dysplasia.
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Affiliation(s)
- Guangze Li
- Yuelushan Laboratory, Hunan Agricultural University, Changsha 410128, China; (G.L.); (W.Z.); (M.T.); (R.L.); (Y.R.)
- Key Laboratory of Hunan Provincial on Crop Epigenetic Regulation and Development, Hunan Agricultural University, Changsha 410128, China
| | - Wenjun Zhu
- Yuelushan Laboratory, Hunan Agricultural University, Changsha 410128, China; (G.L.); (W.Z.); (M.T.); (R.L.); (Y.R.)
- Key Laboratory of Hunan Provincial on Crop Epigenetic Regulation and Development, Hunan Agricultural University, Changsha 410128, China
| | - Minyu Tian
- Yuelushan Laboratory, Hunan Agricultural University, Changsha 410128, China; (G.L.); (W.Z.); (M.T.); (R.L.); (Y.R.)
- Key Laboratory of Hunan Provincial on Crop Epigenetic Regulation and Development, Hunan Agricultural University, Changsha 410128, China
| | - Rong Liu
- Yuelushan Laboratory, Hunan Agricultural University, Changsha 410128, China; (G.L.); (W.Z.); (M.T.); (R.L.); (Y.R.)
- Key Laboratory of Hunan Provincial on Crop Epigenetic Regulation and Development, Hunan Agricultural University, Changsha 410128, China
| | - Ying Ruan
- Yuelushan Laboratory, Hunan Agricultural University, Changsha 410128, China; (G.L.); (W.Z.); (M.T.); (R.L.); (Y.R.)
- Key Laboratory of Hunan Provincial on Crop Epigenetic Regulation and Development, Hunan Agricultural University, Changsha 410128, China
| | - Chunlin Liu
- Yuelushan Laboratory, Hunan Agricultural University, Changsha 410128, China; (G.L.); (W.Z.); (M.T.); (R.L.); (Y.R.)
- Key Laboratory of Hunan Provincial on Crop Epigenetic Regulation and Development, Hunan Agricultural University, Changsha 410128, China
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Feng YT, Yang CY, Wu L, Wang YC, Shen GW, Lin P. BmSPP is a virus resistance gene in Bombyx mori. Front Immunol 2024; 15:1377270. [PMID: 38585268 PMCID: PMC10995218 DOI: 10.3389/fimmu.2024.1377270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 03/06/2024] [Indexed: 04/09/2024] Open
Abstract
Introduction Signal peptide peptidase (SPP) is an intramembrane protease involved in a variety of biological processes, it participates in the processing of signal peptides after the release of the nascent protein to regulate the endoplasmic reticulum associated degradation (ERAD) pathway, binds misfolded membrane proteins, and aids in their clearance process. Additionally, it regulates normal immune surveillance and assists in the processing of viral proteins. Although SPP is essential for many viral infections, its role in silkworms remains unclear. Studying its role in the silkworm, Bombyx mori , may be helpful in breeding virus-resistant silkworms. Methods First, we performed RT-qPCR to analyze the expression pattern of BmSPP. Subsequently, we inhibited BmSPP using the SPP inhibitor 1,3-di-(N-carboxybenzoyl-L-leucyl-L-leucylaminopropanone ((Z-LL)2-ketone) and downregulated the expression of BmSPP using CRISPR/Cas9 gene editing. Furthermore, we assessed the impact of these interventions on the proliferation of Bombyx mori nucleopolyhedrovirus (BmNPV). Results We observed a decreased in the expression of BmSPP during viral proliferation. It was found that higher concentration of the inhibitor resulted in greater inhibition of BmNPV proliferation. The down-regulation of BmSPP in both in vivo and in vitro was found to affect the proliferation of BmNPV. In comparison to wild type silkworm, BmSPPKO silkworms exhibited a 12.4% reduction in mortality rate. Discussion Collectively, this work demonstrates that BmSPP plays a negative regulatory role in silkworm resistance to BmNPV infection and is involved in virus proliferation and replication processes. This finding suggests that BmSPP servers as a target gene for BmNPV virus resistance in silkworms and can be utilized in resistance breeding programs.
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Affiliation(s)
| | | | | | | | | | - Ping Lin
- Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, Biological Science Research Center, Southwest University, Chongqing, China
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Thulasi Devendrakumar K, Peng TS, Pierdzig L, Jackson E, Lipka V, Li X. Signal Peptide Peptidase and PI4Kβ1/2 play opposite roles in plant ER stress response and immunity. STRESS BIOLOGY 2024; 4:20. [PMID: 38507026 PMCID: PMC10954597 DOI: 10.1007/s44154-024-00155-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 02/07/2024] [Indexed: 03/22/2024]
Abstract
The Arabidopsis pi4kβ1,2 mutant is mutated in the phosphatidylinositol 4-kinase (PI4K) β1 and PI4Kβ2 enzymes which are involved in the biosynthesis of phosphatidylinositol 4-phosphate (PI4P), a minor membrane lipid with important signaling roles. pi4kβ1,2 plants display autoimmunity and shorter roots. Though the pi4kβ1,2 mutant has been extensively characterized, the source of its autoimmunity remains largely unknown. In this study, through a genetic suppressor screen, we identified multiple partial loss-of-function alleles of signal peptide peptidase (spp) that can suppress all the defects of pi4kβ1,2. SPP is an intramembrane cleaving aspartic protease. Interestingly, pi4kβ1,2 plants display enhanced ER stress response and mutations in SPP can suppress such phenotype. Furthermore, reduced ER stress responses were observed in the spp single mutants. Overall, our study reveals a previously unknown function of PI4Kβ and SPP in ER stress and plant immunity.
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Affiliation(s)
- Karen Thulasi Devendrakumar
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Tony ShengZhe Peng
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Leon Pierdzig
- Department of Plant Cell Biology, Georg August Universität Göttingen, 37077, Göttingen, Lower Saxony, Germany
| | - Edan Jackson
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Volker Lipka
- Department of Plant Cell Biology, Georg August Universität Göttingen, 37077, Göttingen, Lower Saxony, Germany
| | - Xin Li
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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6
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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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7
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Dulloo I, Tellier M, Levet C, Chikh A, Zhang B, Blaydon DC, Webb CM, Kelsell DP, Freeman M. Cleavage of the pseudoprotease iRhom2 by the signal peptidase complex reveals an ER-to-nucleus signaling pathway. Mol Cell 2024; 84:277-292.e9. [PMID: 38183983 DOI: 10.1016/j.molcel.2023.12.012] [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: 11/29/2022] [Revised: 09/18/2023] [Accepted: 12/08/2023] [Indexed: 01/08/2024]
Abstract
iRhoms are pseudoprotease members of the rhomboid-like superfamily and are cardinal regulators of inflammatory and growth factor signaling; they function primarily by recognizing transmembrane domains of their clients. Here, we report a mechanistically distinct nuclear function of iRhoms, showing that both human and mouse iRhom2 are non-canonical substrates of signal peptidase complex (SPC), the protease that removes signal peptides from secreted proteins. Cleavage of iRhom2 generates an N-terminal fragment that enters the nucleus and modifies the transcriptome, in part by binding C-terminal binding proteins (CtBPs). The biological significance of nuclear iRhom2 is indicated by elevated levels in skin biopsies of patients with psoriasis, tylosis with oesophageal cancer (TOC), and non-epidermolytic palmoplantar keratoderma (NEPPK); increased iRhom2 cleavage in a keratinocyte model of psoriasis; and nuclear iRhom2 promoting proliferation of keratinocytes. Overall, this work identifies an unexpected SPC-dependent ER-to-nucleus signaling pathway and demonstrates that iRhoms can mediate nuclear signaling.
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Affiliation(s)
- Iqbal Dulloo
- Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
| | - Michael Tellier
- Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Clémence Levet
- Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Anissa Chikh
- Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK
| | - Boyan Zhang
- Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Diana C Blaydon
- Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK
| | - Catherine M Webb
- Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK
| | - David P Kelsell
- Blizard Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK
| | - Matthew Freeman
- Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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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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9
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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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10
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Tipper DJ, Harley CA. Spf1 and Ste24: quality controllers of transmembrane protein topology in the eukaryotic cell. Front Cell Dev Biol 2023; 11:1220441. [PMID: 37635876 PMCID: PMC10456885 DOI: 10.3389/fcell.2023.1220441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 07/14/2023] [Indexed: 08/29/2023] Open
Abstract
DNA replication, transcription, and translation in eukaryotic cells occur with decreasing but still high fidelity. In contrast, for the estimated 33% of the human proteome that is inserted as transmembrane (TM) proteins, insertion with a non-functional inverted topology is frequent. Correct topology is essential for function and trafficking to appropriate cellular compartments and is controlled principally by responses to charged residues within 15 residues of the inserted TM domain (TMD); the flank with the higher positive charge remains in the cytosol (inside), following the positive inside rule (PIR). Yeast (Saccharomyces cerevisiae) mutants that increase insertion contrary to the PIR were selected. Mutants with strong phenotypes were found only in SPF1 and STE24 (human cell orthologs are ATP13A1 and ZMPSte24) with, at the time, no known relevant functions. Spf1/Atp13A1 is now known to dislocate to the cytosol TM proteins inserted contrary to the PIR, allowing energy-conserving reinsertion. We hypothesize that Spf1 and Ste24 both recognize the short, positively charged ER luminal peptides of TM proteins inserted contrary to the PIR, accepting these peptides into their large membrane-spanning, water-filled cavities through interaction with their many interior surface negative charges. While entry was demonstrated for Spf1, no published evidence directly demonstrates substrate entry to the Ste24 cavity, internal access to its zinc metalloprotease (ZMP) site, or active withdrawal of fragments, which may be essential for function. Spf1 and Ste24 comprise a PIR quality control system that is conserved in all eukaryotes and presumably evolved in prokaryotic progenitors as they gained differentiated membrane functions. About 75% of the PIR is imposed by this quality control system, which joins the UPR, ERAD, and autophagy (ER-phagy) in coordinated, overlapping quality control of ER protein function.
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Affiliation(s)
- Donald J. Tipper
- University of Massachusetts Medical School, Worcester, MA, United States
| | - Carol A. Harley
- i3S-Instituto de Investigação e Inovação em Saude, Universidade do Porto, Porto, Portugal
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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11
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Ono K, Sato J, Suzuki H, Sawada M. Distribution of Signal Peptides in Microvesicles from Activated Macrophage Cells. Int J Mol Sci 2023; 24:12131. [PMID: 37569508 PMCID: PMC10418841 DOI: 10.3390/ijms241512131] [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: 06/29/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
Extracellular vesicles, such as microvesicles (LEV) and exosomes (SEV), play an important role in intercellular signaling by encapsulating functional molecules and delivering them to specific cells. Recent studies showed that signal peptides (SPs), which are derived from sequences at the N-terminal of newly synthesized proteins, exhibited biological activity in the extracellular fluid. We previously reported that SPs were secreted into the extracellular fluid via SEV; however, it remains unclear whether the release of SPs occurs via LEV. In the present study, we demonstrated that SP fragments from human placental secreted alkaline phosphatase (SEAP) were present in LEV as well as SEV released from RAW-Blue cells, which stably express an NF-κB-inducible SEAP reporter. When RAW-Blue cells were treated with LPS at 0-10,000 ng/mL, SEAP SP fragments per particle were more abundant in LEV than in SEV, with fragments in LEV and SEV reaching a maximum at 1000 and 100 ng/mL, respectively. The content of SEAP SP fragments in LEV from IFNγ-stimulated RAW-Blue cells was higher than those from TNFα-stimulated cells, whereas that in SEV from TNFα-stimulated RAW-Blue cells was higher than those from IFNγ-stimulated cells. Moreover, the content of SEAP SP fragments in LEV and SEV decreased in the presence of W13, a calmodulin inhibitor. Collectively, these results indicate that the transportation of SP fragments to extracellular vesicles was changed by cellular activation, and calmodulin was involved in their transportation to LEV and SEV.
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Affiliation(s)
- Kenji Ono
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
| | - Junpei Sato
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
| | - Hiromi Suzuki
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
| | - Makoto Sawada
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
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12
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Yang J, Zhai N, Chen Y, Wang L, Chen R, Pan H. A signal peptide peptidase is required for ER-symbiosome proximal association and protein secretion. Nat Commun 2023; 14:4355. [PMID: 37468528 DOI: 10.1038/s41467-023-40008-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 07/09/2023] [Indexed: 07/21/2023] Open
Abstract
During legume-rhizobia symbiosis, differentiation of the symbiosome (engulfed intracellular rhizobia) is necessary for successful nitrogen fixation. To control symbiosome differentiation, host cell subcellular components, e.g., ER (endoplasmic reticulum), must adapt robustly to ensure large-scale host protein secretion to the new organelle. However, the key components controlling the adaption of ER in nodule cells remain elusive. We report that Medicago BID1, a nodule-specific signal peptide peptidase (SPP), is central to ER structural dynamics and host protein secretion. In bid1, symbiosome differentiation is blocked. BID1 localizes specifically to the ER membrane and expresses exclusively in nodule cells with symbiosomes. In the wild type ER forms proximal association structures with symbiosomes, but not in bid1. Consequently, in bid1 excessive ER stress responses are induced and ER-to-symbiosome protein secretion is impaired. In summary, a nodule-specific SPP is necessary for ER-symbiosome proximal association, host protein secretion, and symbiosome differentiation.
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Affiliation(s)
- Jian Yang
- College of Biology, Hunan University, Changsha, China
| | - Niu Zhai
- Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou, China
| | - Yuhui Chen
- College of Life Sciences, Lanzhou University, Lanzhou, China
| | - Luying Wang
- College of Biology, Hunan University, Changsha, China
| | - Rujin Chen
- College of Life Sciences, Lanzhou University, Lanzhou, China
| | - Huairong Pan
- College of Biology, Hunan University, Changsha, China.
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13
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Bruno PM, Timms RT, Abdelfattah NS, Leng Y, Lelis FJN, Wesemann DR, Yu XG, Elledge SJ. High-throughput, targeted MHC class I immunopeptidomics using a functional genetics screening platform. Nat Biotechnol 2023; 41:980-992. [PMID: 36593401 PMCID: PMC10314971 DOI: 10.1038/s41587-022-01566-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 10/13/2022] [Indexed: 01/03/2023]
Abstract
Identification of CD8+ T cell epitopes is critical for the development of immunotherapeutics. Existing methods for major histocompatibility complex class I (MHC class I) ligand discovery are time intensive, specialized and unable to interrogate specific proteins on a large scale. Here, we present EpiScan, which uses surface MHC class I levels as a readout for whether a genetically encoded peptide is an MHC class I ligand. Predetermined starting pools composed of >100,000 peptides can be designed using oligonucleotide synthesis, permitting large-scale MHC class I screening. We exploit this programmability of EpiScan to uncover an unappreciated role for cysteine that increases the number of predicted ligands by 9-21%, reveal affinity hierarchies by analysis of biased anchor peptide libraries and screen viral proteomes for MHC class I ligands. Using these data, we generate and iteratively refine peptide binding predictions to create EpiScan Predictor. EpiScan Predictor performs comparably to other state-of-the-art MHC class I peptide binding prediction algorithms without suffering from underrepresentation of cysteine-containing peptides. Thus, targeted immunopeptidomics using EpiScan will accelerate CD8+ T cell epitope discovery toward the goal of individual-specific immunotherapeutics.
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Affiliation(s)
- Peter M Bruno
- Department of Genetics, Harvard Medical School and Division of Genetics, Brigham and Women's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Richard T Timms
- Department of Genetics, Harvard Medical School and Division of Genetics, Brigham and Women's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
- Cambridge Institute of Therapeutic Immunology and Infectious Disease, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus, University of Cambridge, Cambridge, UK
| | - Nouran S Abdelfattah
- Department of Genetics, Harvard Medical School and Division of Genetics, Brigham and Women's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Yumei Leng
- Department of Genetics, Harvard Medical School and Division of Genetics, Brigham and Women's Hospital, Boston, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Felipe J N Lelis
- Department of Medicine, Division of Allergy and Immunology, Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Duane R Wesemann
- Department of Medicine, Division of Allergy and Immunology, Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Massachusetts Consortium on Pathogen Readiness, Boston, MA, USA
| | - Xu G Yu
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA
- Infectious Disease Division, Brigham and Women's Hospital, Boston, MA, USA
| | - Stephen J Elledge
- Department of Genetics, Harvard Medical School and Division of Genetics, Brigham and Women's Hospital, Boston, MA, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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14
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Itell HL, Humes D, Overbaugh J. Several cell-intrinsic effectors drive type I interferon-mediated restriction of HIV-1 in primary CD4 + T cells. Cell Rep 2023; 42:112556. [PMID: 37227817 PMCID: PMC10592456 DOI: 10.1016/j.celrep.2023.112556] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 03/30/2023] [Accepted: 05/05/2023] [Indexed: 05/27/2023] Open
Abstract
Type I interferon (IFN) upregulates proteins that inhibit HIV within infected cells. Prior studies have identified IFN-stimulated genes (ISGs) that impede lab-adapted HIV in cell lines, yet the ISG(s) that mediate IFN restriction in HIV target cells, primary CD4+ T cells, are unknown. Here, we interrogate ISG restriction of primary HIV in CD4+ T cells by performing CRISPR-knockout screens with a custom library that specifically targets ISGs expressed in CD4+ T cells. Our investigation identifies previously undescribed HIV-restricting ISGs (HM13, IGFBP2, LAP3) and finds that two factors characterized in other HIV infection models (IFI16 and UBE2L6) mediate IFN restriction in T cells. Inactivation of these five ISGs in combination further diminishes IFN's protective effect against diverse HIV strains. This work demonstrates that IFN restriction of HIV is multifaceted, resulting from several effectors functioning collectively, and establishes a primary cell ISG screening model to identify both single and combinations of HIV-restricting ISGs.
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Affiliation(s)
- Hannah L Itell
- Molecular and Cellular Biology PhD Program, University of Washington, Seattle, WA 98195, USA; Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Daryl Humes
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Julie Overbaugh
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
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15
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Collett S, Earnest L, Carrera Montoya J, Edeling MA, Yap A, Wong CY, Christiansen D, Roberts J, Mumford J, Lecouturier V, Pavot V, Marco S, Loi JK, Simmons C, Gulab SA, Mackenzie JM, Elbourne A, Ramsland PA, Cameron G, Hans D, Godfrey DI, Torresi J. Development of virus-like particles with inbuilt immunostimulatory properties as vaccine candidates. Front Microbiol 2023; 14:1065609. [PMID: 37350788 PMCID: PMC10282183 DOI: 10.3389/fmicb.2023.1065609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 05/17/2023] [Indexed: 06/24/2023] Open
Abstract
The development of virus-like particle (VLP) based vaccines for human papillomavirus, hepatitis B and hepatitis E viruses represented a breakthrough in vaccine development. However, for dengue and COVID-19, technical complications, such as an incomplete understanding of the requirements for protective immunity, but also limitations in processes to manufacture VLP vaccines for enveloped viruses to large scale, have hampered VLP vaccine development. Selecting the right adjuvant is also an important consideration to ensure that a VLP vaccine induces protective antibody and T cell responses. For diseases like COVID-19 and dengue fever caused by RNA viruses that exist as families of viral variants with the potential to escape vaccine-induced immunity, the development of more efficacious vaccines is also necessary. Here, we describe the development and characterisation of novel VLP vaccine candidates using SARS-CoV-2 and dengue virus (DENV), containing the major viral structural proteins, as protypes for a novel approach to produce VLP vaccines. The VLPs were characterised by Western immunoblot, enzyme immunoassay, electron and atomic force microscopy, and in vitro and in vivo immunogenicity studies. Microscopy techniques showed proteins self-assemble to form VLPs authentic to native viruses. The inclusion of the glycolipid adjuvant, α-galactosylceramide (α-GalCer) in the vaccine formulation led to high levels of natural killer T (NKT) cell stimulation in vitro, and strong antibody and memory CD8+ T cell responses in vivo, demonstrated with SARS-CoV-2, hepatitis C virus (HCV) and DEN VLPs. This study shows our unique vaccine formulation presents a promising, and much needed, new vaccine platform in the fight against infections caused by enveloped RNA viruses.
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Affiliation(s)
- Simon Collett
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC, Australia
| | - Linda Earnest
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Julio Carrera Montoya
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Melissa A. Edeling
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Ashley Yap
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Chinn Yi Wong
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Dale Christiansen
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Jason Roberts
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
- Department of Infectious Diseases, The University of Melbourne at the Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | - Jamie Mumford
- Victorian Infectious Diseases Reference Laboratory, Royal Melbourne Hospital at the Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
| | | | | | | | - Joon Keit Loi
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Cameron Simmons
- Institute of Vector-Borne Disease, Monash University, Clayton, VIC, Australia
| | - Shivali A. Gulab
- Avalia Immunotherapies Limited, Wellington, New Zealand
- Vaccine Alliance Aotearoa New Zealand, Wellington, New Zealand
| | - Jason M. Mackenzie
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Aaron Elbourne
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC, Australia
| | - Paul A. Ramsland
- School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC, Australia
- Department of Surgery Austin Health, University of Melbourne, Heidelberg, VIC, Australia
- Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Garth Cameron
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Dhiraj Hans
- Research, Innovation and Commercialisation, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Dale I. Godfrey
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
| | - Joseph Torresi
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC, Australia
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16
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Itell HL, Humes D, Overbaugh J. Several cell-intrinsic effectors drive type I interferon-mediated restriction of HIV-1 in primary CD4 + T cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.07.527545. [PMID: 36798236 PMCID: PMC9934674 DOI: 10.1101/2023.02.07.527545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Type I interferon (IFN) upregulates proteins that inhibit HIV within infected cells. Prior studies have identified IFN-stimulated genes (ISGs) that impede lab-adapted HIV in cell lines, yet the ISG(s) that mediate IFN restriction in HIV target cells, primary CD4 + T cells, are unknown. Here, we interrogate ISG restriction of primary HIV in CD4 + T cells. We performed CRISPR-knockout screens using a custom library that specifically targets ISGs expressed in CD4 + T cells and validated top hits. Our investigation identified new HIV-restricting ISGs (HM13, IGFBP2, LAP3) and found that two previously studied factors (IFI16, UBE2L6) are IFN effectors in T cells. Inactivation of these five ISGs in combination further diminished IFN’s protective effect against six diverse HIV strains. This work demonstrates that IFN restriction of HIV is multifaceted, resulting from several effectors functioning collectively, and establishes a primary cell ISG screening model to identify both single and combinations of HIV-restricting ISGs.
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Affiliation(s)
- Hannah L. Itell
- Molecular and Cellular Biology PhD Program, University of Washington, Seattle, WA, 98109, USA
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
| | - Daryl Humes
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
- Present address: Tr1X Inc, La Jolla, CA, 92037, USA
| | - Julie Overbaugh
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
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17
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Ono K, Niwa M, Suzuki H, Kobayashi NB, Yoshida T, Sawada M. Calmodulin as a Key Regulator of Exosomal Signal Peptides. Cells 2022; 12:cells12010158. [PMID: 36611951 PMCID: PMC9818429 DOI: 10.3390/cells12010158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/16/2022] [Accepted: 12/27/2022] [Indexed: 01/04/2023] Open
Abstract
Signal peptides (SPs) and their fragments play important roles as biomarkers and substances with physiological functions in extracellular fluid. We previously reported that SP fragments were released into extracellular fluid via exosomes and bound to calmodulin (CaM), an exosomal component, in a cell-free system. However, it currently remains unclear whether CaM intracellularly interacts with SP fragments or is involved in the trafficking of these fragments to exosomes. Therefore, the present study examined the binding of CaM to SP fragments in T-REx AspALP cells, transformed HEK293 cells expressing amyloid precursor protein (APP) SP flanking a reporter protein, and their exosomes. APP SP fragments were detected in exosomes from T-REx AspALP cells in the absence of W13, a CaM inhibitor, but were present in lower amounts in exosomes from W13-treated cells. Cargo proteins, such as Alix, CD63, and CD81, were increased in W13-treated T-REx AspALP cells but were decreased in their exosomes. Furthermore, CaM interacted with heat shock protein 70 and CD81 in T-REx AspALP cells and this increased in the presence of W13. APP SP fragments were detected in intracellular CaM complexes in the absence of W13, but not in its presence. These results indicate that CaM functions as a key regulator of the transport of SP fragments into exosomes and plays novel roles in the sorting of contents during exosomal biogenesis.
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Affiliation(s)
- Kenji Ono
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan
- Department of Molecular Pharmacokinetics, Graduate School of Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan
- Correspondence: ; Tel.: +81-52-789-5002; Fax: +81-52-789-3994
| | - Mikio Niwa
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba 300-2611, Ibaraki, Japan
| | - Hiromi Suzuki
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan
- Department of Molecular Pharmacokinetics, Graduate School of Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan
| | | | - Tetsuhiko Yoshida
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba 300-2611, Ibaraki, Japan
| | - Makoto Sawada
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan
- Department of Molecular Pharmacokinetics, Graduate School of Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan
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18
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Papadopoulou AA, Stelzer W, Silber M, Schlosser C, Spitz C, Haug-Kröper M, Straub T, Müller SA, Lichtenthaler SF, Muhle-Goll C, Langosch D, Fluhrer R. Helical stability of the GnTV transmembrane domain impacts on SPPL3 dependent cleavage. Sci Rep 2022; 12:20987. [PMID: 36470941 PMCID: PMC9722940 DOI: 10.1038/s41598-022-24772-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
Signal-Peptide Peptidase Like-3 (SPPL3) is an intramembrane cleaving aspartyl protease that causes secretion of extracellular domains from type-II transmembrane proteins. Numerous Golgi-localized glycosidases and glucosyltransferases have been identified as physiological SPPL3 substrates. By SPPL3 dependent processing, glycan-transferring enzymes are deactivated inside the cell, as their active site-containing domain is cleaved and secreted. Thus, SPPL3 impacts on glycan patterns of many cellular and secreted proteins and can regulate protein glycosylation. However, the characteristics that make a substrate a favourable candidate for SPPL3-dependent cleavage remain unknown. To gain insights into substrate requirements, we investigated the function of a GxxxG motif located in the transmembrane domain of N-acetylglucosaminyltransferase V (GnTV), a well-known SPPL3 substrate. SPPL3-dependent secretion of the substrate's ectodomain was affected by mutations disrupting the GxxxG motif. Using deuterium/hydrogen exchange and NMR spectroscopy, we studied the effect of these mutations on the helix flexibility of the GnTV transmembrane domain and observed that increased flexibility facilitates SPPL3-dependent shedding and vice versa. This study provides first insights into the characteristics of SPPL3 substrates, combining molecular biology, biochemistry, and biophysical techniques and its results will provide the basis for better understanding the characteristics of SPPL3 substrates with implications for the substrates of other intramembrane proteases.
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Affiliation(s)
- Alkmini A. Papadopoulou
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Walter Stelzer
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Mara Silber
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Christine Schlosser
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Charlotte Spitz
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Martina Haug-Kröper
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
| | - Tobias Straub
- grid.5252.00000 0004 1936 973XCore Facility Bioinformatics, Biomedical Center, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Stephan A. Müller
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany
| | - Stefan F. Lichtenthaler
- grid.424247.30000 0004 0438 0426DZNE – German Center for Neurodegenerative Diseases, Munich, Germany ,grid.15474.330000 0004 0477 2438Neuroproteomics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, 81675 Munich, Germany ,grid.452617.3Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Claudia Muhle-Goll
- grid.7892.40000 0001 0075 5874Institute for Biological Interfaces 4, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Organic Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Dieter Langosch
- grid.6936.a0000000123222966Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Regina Fluhrer
- grid.7307.30000 0001 2108 9006Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Universitätstrasse 2, 86159 Augsburg, Germany
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19
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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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20
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Trávníčková K, Stříšovský K. On the track of intramembrane clippers: the
SPPL2a
/b proteases caught in the act in animal models. FEBS J 2022; 290:2306-2310. [PMID: 36310421 DOI: 10.1111/febs.16663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 10/20/2022] [Indexed: 11/05/2022]
Abstract
In this issue, Ballin et al. report on their analysis of the substrate repertoire of SPPL2a and b intramembrane proteases. Based on the previous studies of their closest homologues, SPPL2c, SPPL3 and SPP, the authors hypothesized that SPPL2a/b proteases may cleave a subset of SNARE proteins. Indeed, four R-SNARE proteins, VAMP1, 2, 3 and 4, were cleaved by SPPL2a/b, both in overexpression assays and at endogenous levels. These findings have been validated by analysis of SPPL2a/b double knock-out mice tissues, which implicates these proteases in the regulation of SNARE protein turnover in vivo. The study of Ballin et al. also provides material for future studies of factors determining substrate specificity of SPPLs, as they cleave different subsets of the tail-anchored SNARE proteins. Comment on: https://doi.org/10.1111/febs.16610.
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Affiliation(s)
- Květa Trávníčková
- Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Praha Czechia
| | - Kvido Stříšovský
- Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic Praha Czechia
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21
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Hodges SL, Bouza AA, Isom LL. Therapeutic Potential of Targeting Regulated Intramembrane Proteolysis Mechanisms of Voltage-Gated Ion Channel Subunits and Cell Adhesion Molecules. Pharmacol Rev 2022; 74:1028-1048. [PMID: 36113879 PMCID: PMC9553118 DOI: 10.1124/pharmrev.121.000340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/13/2022] [Indexed: 10/03/2023] Open
Abstract
Several integral membrane proteins undergo regulated intramembrane proteolysis (RIP), a tightly controlled process through which cells transmit information across and between intracellular compartments. RIP generates biologically active peptides by a series of proteolytic cleavage events carried out by two primary groups of enzymes: sheddases and intramembrane-cleaving proteases (iCLiPs). Following RIP, fragments of both pore-forming and non-pore-forming ion channel subunits, as well as immunoglobulin super family (IgSF) members, have been shown to translocate to the nucleus to function in transcriptional regulation. As an example, the voltage-gated sodium channel β1 subunit, which is also an IgSF-cell adhesion molecule (CAM), is a substrate for RIP. β1 RIP results in generation of a soluble intracellular domain, which can regulate gene expression in the nucleus. In this review, we discuss the proposed RIP mechanisms of voltage-gated sodium, potassium, and calcium channel subunits as well as the roles of their generated proteolytic products in the nucleus. We also discuss other RIP substrates that are cleaved by similar sheddases and iCLiPs, such as IgSF macromolecules, including CAMs, whose proteolytically generated fragments function in the nucleus. Importantly, dysfunctional RIP mechanisms are linked to human disease. Thus, we will also review how understanding RIP events and subsequent signaling processes involving ion channel subunits and IgSF proteins may lead to the discovery of novel therapeutic targets. SIGNIFICANCE STATEMENT: Several ion channel subunits and immunoglobulin superfamily molecules have been identified as substrates of regulated intramembrane proteolysis (RIP). This signal transduction mechanism, which generates polypeptide fragments that translocate to the nucleus, is an important regulator of gene transcription. RIP may impact diseases of excitability, including epilepsy, cardiac arrhythmia, and sudden death syndromes. A thorough understanding of the role of RIP in gene regulation is critical as it may reveal novel therapeutic strategies for the treatment of previously intractable diseases.
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Affiliation(s)
- Samantha L Hodges
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Alexandra A Bouza
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
| | - Lori L Isom
- Departments of Pharmacology (S.L.H., A.A.B., L.L.I.), Neurology (L.L.I.), and Molecular & Integrative Physiology (L.L.I.), University of Michigan Medical School, Ann Arbor, Michigan
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Yang H, Li Z, Wang Z, Zhang X, Dai X, Zhou G, Ding Q. Histocompatibility Minor 13 (HM13), targeted by miR-760, exerts oncogenic role in breast cancer by suppressing autophagy and activating PI3K-AKT-mTOR pathway. Cell Death Dis 2022; 13:728. [PMID: 36153332 PMCID: PMC9509374 DOI: 10.1038/s41419-022-05154-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 01/21/2023]
Abstract
Histocompatibility Minor 13 (HM13) is reported to participate in regulating multiple cancers. In the present study, we uncovered that HM13 was highly expressed in breast cancer and correlated with worse prognosis. Downregulation of HM13 could suppress breast cancer cell proliferation and metastasis abilities. Tumorigenicity mediated by HM13 was also observed in the xenograft model. Knockdown of HM13 could activate autophagy by inducing endoplasmic reticulum (ER) stress. Moreover, further experiments demonstrated that downregulated HM13 could inhibit PI3K-AKT-mTOR pathway. We then verified that HM13 was a direct target of miR-760 functioned as a tumor -suppressor in breast cancer. And the tumor suppressive effects of miR-760 could be partially reversed by HM13. Taken together, these findings elucidated that HM13, targeted by miR-760, could play an oncogenic role in breast cancer by inducing autophagic inhibition and facilitating PI3K-AKT-mTOR pathway. Our findings suggested HM13 could act as a novel therapeutic target candidate for breast cancer and supported the idea that autophagy inducers might represent a new approach to treat breast cancer.
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Affiliation(s)
- Haiyan Yang
- grid.412676.00000 0004 1799 0784Jiangsu Breast Disease Center, the First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029 PR China
| | - Zhi Li
- grid.89957.3a0000 0000 9255 8984Department of Breast and Thyroid Surgery, Huai’an First People’s Hospital, Nanjing Medical University, Huai’an, Jiangsu 223399 PR China
| | - Zhangwei Wang
- grid.412676.00000 0004 1799 0784Jiangsu Breast Disease Center, the First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029 PR China
| | - Xu Zhang
- grid.412676.00000 0004 1799 0784Jiangsu Breast Disease Center, the First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029 PR China
| | - Xinyuan Dai
- grid.412676.00000 0004 1799 0784Jiangsu Breast Disease Center, the First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029 PR China
| | - Guoren Zhou
- grid.452509.f0000 0004 1764 4566Department of Oncology, Jiangsu Cancer Hospital & the Affiliated Cancer Hospital of Nanjing Medical University & Jiangsu Institute of Cancer Research, Nanjing, Jiangsu 210009 PR China
| | - Qiang Ding
- grid.412676.00000 0004 1799 0784Jiangsu Breast Disease Center, the First Affiliated Hospital with Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029 PR China
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Kaushik S, He H, Dalbey RE. Bacterial Signal Peptides- Navigating the Journey of Proteins. Front Physiol 2022; 13:933153. [PMID: 35957980 PMCID: PMC9360617 DOI: 10.3389/fphys.2022.933153] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 06/21/2022] [Indexed: 11/18/2022] Open
Abstract
In 1971, Blobel proposed the first statement of the Signal Hypothesis which suggested that proteins have amino-terminal sequences that dictate their export and localization in the cell. A cytosolic binding factor was predicted, and later the protein conducting channel was discovered that was proposed in 1975 to align with the large ribosomal tunnel. The 1975 Signal Hypothesis also predicted that proteins targeted to different intracellular membranes would possess distinct signals and integral membrane proteins contained uncleaved signal sequences which initiate translocation of the polypeptide chain. This review summarizes the central role that the signal peptides play as address codes for proteins, their decisive role as targeting factors for delivery to the membrane and their function to activate the translocation machinery for export and membrane protein insertion. After shedding light on the navigation of proteins, the importance of removal of signal peptide and their degradation are addressed. Furthermore, the emerging work on signal peptidases as novel targets for antibiotic development is described.
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24
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Feilen LP, Chen SY, Fukumori A, Feederle R, Zacharias M, Steiner H. Active site geometry stabilization of a presenilin homolog by the lipid bilayer promotes intramembrane proteolysis. eLife 2022; 11:76090. [PMID: 35579427 PMCID: PMC9282858 DOI: 10.7554/elife.76090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Cleavage of membrane proteins in the lipid bilayer by intramembrane proteases is crucial for health and disease. Although different lipid environments can potently modulate their activity, how this is linked to their structural dynamics is unclear. Here, we show that the carboxy-peptidase-like activity of the archaeal intramembrane protease PSH, a homolog of the Alzheimer’s disease-associated presenilin/γ-secretase is impaired in micelles and promoted in a lipid bilayer. Comparative molecular dynamics simulations revealed that important elements for substrate binding such as transmembrane domain 6a of PSH are more labile in micelles and stabilized in the lipid bilayer. Moreover, consistent with an enhanced interaction of PSH with a transition-state analog inhibitor, the bilayer promoted the formation of the enzyme’s catalytic active site geometry. Our data indicate that the lipid environment of an intramembrane protease plays a critical role in structural stabilization and active site arrangement of the enzyme-substrate complex thereby promoting intramembrane proteolysis. Cutting proteins into pieces is a crucial process in the cell, allowing several important processes to take place, including cell differentiation (which allows cells to develop into specific types), cell death, protein quality control, or even where in the cell a protein will end up. However, the specialized proteins that carry out this task, known as proteases, can also be involved in the development of disease. For example, in the brain, a protease called γ-secretase cuts up the amyloid-β protein precursor, producing toxic forms of amyloid-β peptides that are widely believed to cause Alzheimer’s disease. Proteases like γ-secretase carry out their role in the membrane, the layer of fats (also known as lipids) that forms the outer boundary of the cell. The environment in this area of the cell can influence the activity of proteases, but it is poorly understood how this happens. One way to address this question would be to compare the activity of γ-secretase in the lipid environment of the membrane to its activity when it is entirely surrounded by different molecules, such as detergent molecules. Unfortunately, γ-secretase is not active when it is removed from its lipid environment by a detergent, making it difficult to perform this comparison. To overcome this issue, Feilen et al. chose to study PSH, a protease similar to γ-secretase that produces the same amyloid-β peptides but remains active in detergent. When Feilen et al. mixed PSH with lipid molecules like those found in the membrane and amyloid-β precursor protein, PSH produced amyloid-β peptides including those that are thought to cause Alzheimer’s. However, when a detergent was substituted for the lipid molecules this led to longer amyloid-β peptides than usual, indicating that PSH was not able to cut proteins as effectively. The change in environment appeared to reduce PSH’s ability to progressively trim small segments from the peptides. Computer modelling of the protease’s structure in lipids versus detergent supported the experimental findings: the model predicted that the areas of PSH important for recognizing and cutting other proteins would be more stable in the membrane compared to the detergent. These results indicate that the cell membrane plays a vital role in the stability of the active regions of proteases that are cleaving in this environment. In the future, this could help to better understand how changes to the lipid molecules in the membrane may contribute to the activity of γ-secretase and its role in Alzheimer’s disease.
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Affiliation(s)
- Lukas P Feilen
- German Center for Neurodegenerative Diseases, Munich, Germany
| | - Shu-Yu Chen
- Physics Department T38, Technical University of Munich, Garching, Germany
| | - Akio Fukumori
- Department of Pharmacotherapeutics II, Osaka Medical and Pharmaceutical University, Takatsuki, Japan
| | - Regina Feederle
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Munich, Germany
| | - Martin Zacharias
- Physics Department T38, Technical University of Munich, Garching, Germany
| | - Harald Steiner
- Biomedical Center (BMC), Ludwig-Maximilians-Universität München, Munich, Germany
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25
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Ono K, Niwa M, Suzuki H, Kobayashi NB, Yoshida T, Sawada M. Signal Sequence-Dependent Orientation of Signal Peptide Fragments to Exosomes. Int J Mol Sci 2022; 23:ijms23063137. [PMID: 35328557 PMCID: PMC8950404 DOI: 10.3390/ijms23063137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 12/04/2022] Open
Abstract
Signal peptides (SPs) not only mediate targeting to the endoplasmic reticulum (ER) but also play important roles as biomarkers and substances with physiological activity in extracellular fluids including blood. SPs are thought to be degraded intracellularly, making it unclear how they are transported from the ER to the extracellular fluid. In a recent study, we showed that a C-terminal fragment of the SP of a type I membrane protein, amyloid precursor protein (APP), was secreted into the extracellular fluid via exosomes using transformed HEK293 cells expressing APP SP flanking a reporter protein. In the present study, we demonstrate that a N-terminal fragment of the SP from a type II membrane protein, human placental secreted alkaline phosphatase (SEAP), is contained in exosomes and secreted into the extracellular fluid using HEK-Blue hTLR3 cells, which express both a human toll-like receptor 3 gene and an inducible SEAP reporter gene. When HEK-Blue hTLR3 cells were stimulated with a TLR3 ligand, a N-terminal fragment of SEAP SP in exosomes was increased in parallel with SEAP secretion in a concentration-dependent manner. These results indicated that SP fragments are exosomal components. In addition, migrating SP fragments were determined by characteristics of the signal–anchor sequence of membrane proteins. Furthermore, we found that SP fragments could bind to calmodulin (CALM), which is a cytosolic protein and also a component of exosomes, suggesting its involvement in the transportation of SP fragments from the endoplasmic reticulum to exosomes.
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Affiliation(s)
- Kenji Ono
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan; (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
- Correspondence: ; Tel.: +81-52-789-5002; Fax: +81-52-789-3994
| | - Mikio Niwa
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba 300-2611, Ibaraki, Japan; (M.N.); (N.B.K.); (T.Y.)
| | - Hiromi Suzuki
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan; (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
| | - Nahoko Bailey Kobayashi
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba 300-2611, Ibaraki, Japan; (M.N.); (N.B.K.); (T.Y.)
| | - Tetsuhiko Yoshida
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba 300-2611, Ibaraki, Japan; (M.N.); (N.B.K.); (T.Y.)
| | - Makoto Sawada
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Aichi, Japan; (H.S.); (M.S.)
- Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Aichi, Japan
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Schwake C, Hyon M, Chishti AH. Signal peptide peptidase: A potential therapeutic target for parasitic and viral infections. Expert Opin Ther Targets 2022; 26:261-273. [PMID: 35235480 DOI: 10.1080/14728222.2022.2047932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Signal peptide peptidase (SPP) is a GxGD-type intramembrane-cleaving aspartyl protease responsible for clearing accumulating signal peptides in the endoplasmic reticulum. SPP is conserved among all kingdoms and is essential for maintaining cell homeostasis. Inhibition of SPP with selective inhibitors and the structurally similar HIV protease inhibitors results in signal peptide accumulation and subsequent cell death. Identification of SPP homologues in major human parasitic infections has opened a new therapeutic opportunity. Moreover, the essentiality of mammalian SPP-mediated viral protein processing during infection is emerging. AREAS COVERED This review introduces the discovery and biological function of human SPP enzymes and identify parasitic homologues as pharmacological targets of both SPP and HIV protease inhibitors. Later, the role of mammalian SPP during viral infection and how disruption of host SPP can be employed as a novel antiviral therapy are examined and discussed. EXPERT OPINION Parasitic and viral infections cause severe health and economic burden, exacerbated by the lack of new therapeutics in the pipeline. SPP has been shown to be essential for malaria parasite growth and encouraging evidence in other parasites demonstrates broad essentiality of these proteases as therapeutic targets. As drug resistant parasite and viruses emerge, SPP inhibition will provide a new generation of compounds to counter the growing threat of antimicrobial resistance.
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Affiliation(s)
- Christopher Schwake
- Department of Developmental, Molecular, and Chemical Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Michael Hyon
- Department of Developmental, Molecular, and Chemical Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
| | - Athar H Chishti
- Department of Developmental, Molecular, and Chemical Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA
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Das P, Xu WK, Gautam AKS, Lozano MM, Dudley JP. A Retrotranslocation Assay That Predicts Defective VCP/p97-Mediated Trafficking of a Retroviral Signal Peptide. mBio 2022; 13:e0295321. [PMID: 35089078 PMCID: PMC8725593 DOI: 10.1128/mbio.02953-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 11/18/2021] [Indexed: 12/12/2022] Open
Abstract
Studies of viral replication have provided critical insights into host processes, including protein trafficking and turnover. Mouse mammary tumor virus (MMTV) is a betaretrovirus that encodes a functional 98-amino-acid signal peptide (SP). MMTV SP is generated from both Rem and envelope precursor proteins by signal peptidase cleavage in the endoplasmic reticulum (ER) membrane. We previously showed that SP functions as a human immunodeficiency virus type 1 (HIV-1) Rev-like protein that is dependent on the AAA ATPase valosin-containing protein (VCP)/p97 to subvert ER-associated degradation (ERAD). SP contains a nuclear localization sequence (NLS)/nucleolar localization sequence (NoLS) within the N-terminal 45 amino acids. To directly determine the SP regions needed for membrane extraction and trafficking, we developed a quantitative retrotranslocation assay with biotin acceptor peptide (BAP)-tagged SP proteins. Use of alanine substitution mutants of BAP-tagged MMTV SP in retrotranslocation assays revealed that mutation of amino acids 57 and 58 (M57-58) interfered with ER membrane extraction, whereas adjacent mutations did not. The M57-58 mutant also showed reduced interaction with VCP/p97 in coimmunoprecipitation experiments. Using transfection and reporter assays to measure activity of BAP-tagged proteins, both M57-58 and an adjacent mutant (M59-61) were functionally defective compared to wild-type SP. Confocal microscopy revealed defects in SP nuclear trafficking and abnormal localization of both M57-58 and M59-61. Furthermore, purified glutathione S-transferase (GST)-tagged M57-58 and M59-61 demonstrated reduced ability to oligomerize compared to tagged wild-type SP. These experiments suggest that SP amino acids 57 and 58 are critical for VCP/p97 interaction and retrotranslocation, whereas residues 57 to 61 are critical for oligomerization and nuclear trafficking independent of the NLS/NoLS. Our results emphasize the complex host interactions with long signal peptides. IMPORTANCE Endoplasmic reticulum-associated degradation (ERAD) is a form of cellular protein quality control that is manipulated by viruses, including the betaretrovirus, mouse mammary tumor virus (MMTV). MMTV-encoded signal peptide (SP) has been shown to interact with an essential ERAD factor, VCP/p97 ATPase, to mediate its extraction from the ER membrane, also known as retrotranslocation, for RNA binding and nuclear function. In this paper, we developed a quantitative retrotranslocation assay that identified an SP substitution mutant, which is defective for VCP interaction as well as nuclear trafficking, oligomer formation, and function. An adjacent SP mutant was competent for retrotranslocation and VCP interaction but shared the other defects. Our results revealed the requirement for VCP during SP trafficking and the complex cellular pathways used by long signal peptides.
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Affiliation(s)
- Poulami Das
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Wendy Kaichun Xu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Amit Kumar Singh Gautam
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Mary M. Lozano
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
| | - Jaquelin P. Dudley
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, USA
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, Texas, USA
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Asadi M, Oanca G, Warshel A. Effect of Environmental Factors on the Catalytic Activity of Intramembrane Serine Protease. J Am Chem Soc 2022; 144:1251-1257. [PMID: 35023734 PMCID: PMC10349665 DOI: 10.1021/jacs.1c10494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The cleavage of protein inside cell membranes regulates pathological pathways and is a subject of major interest. Thus, the nature of the coupling between the physical environment and the function of such proteins has recently attracted significant experimental and theoretical efforts. However, it is difficult to determine the nature of this coupling uniquely by experimental and theoretical studies unless one can separate the chemical and the environmental factors. This work describes calculations of the activation barriers of the intramembrane rhomboid protease in neutral and charged lipid bilayers and in detergent micelle, trying to explore the environmental effect. The calculations of the chemical barrier are done using the empirical valence bond (EVB) method. Additionally, the renormalization method captures the energetics and dynamical effects of the conformational change. The simulations indicate that the physical environment around the rhomboid protease is not a major factor in changing the chemical catalysis and that the conformational and substrate dynamics do not exhibit long-time coupling. General issues about the action of membrane-embedded enzymes are also considered.
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Affiliation(s)
- Mojgan Asadi
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Gabriel Oanca
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
| | - Arieh Warshel
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062, United States
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Ono K, Niwa M, Suzuki H, Kobayashi NB, Yoshida T, Sawada M. Secretion of signal peptides via extracellular vesicles. Biochem Biophys Res Commun 2021; 560:21-26. [PMID: 33964503 DOI: 10.1016/j.bbrc.2021.04.073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 04/18/2021] [Indexed: 11/26/2022]
Abstract
Signal peptides (SPs) consist of short peptide sequences present at the N-terminal of newly synthesizing proteins and act as a zip code for the translocation of the proteins to the endoplasmic reticulum (ER). It was thought that the SPs are intracellularly degraded after translocation to the ER; however, recent studies showed cleaved SPs have diverse roles for controlling cell functions in auto- and/or intercellular manners. In addition, it still remains obscure how SP fragments translocate away from the site where they are produced. Extracellular vesicles (EV) are important for intercellular communication and can transport functional molecules to specific cells. In this study, we show that SPs are involved in EV from T-REx AspALP cells that were transfected with a human APP SP-inducible expression vector. There was no difference in the average particle size or particle concentration of EV collected from T-REx AspALP cells and T-REx Mock cells. When the SP content in the EV was examined by mass spectrometry, the C-terminal fragment of APP SP was identified in the exosomes (SEV) of T-REx AspALP cells. In our preparation of SEV fractions, no ER-specific proteins were detected; therefore, SPs may be included in SEV but not in the debris of degraded ER. This is the first indication that SPs are secreted from cells via EV.
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Affiliation(s)
- Kenji Ono
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 464-8601, Japan.
| | - Mikio Niwa
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba, Ibaraki, 300-2611, Japan
| | - Hiromi Suzuki
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 464-8601, Japan
| | | | - Tetsuhiko Yoshida
- Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba, Ibaraki, 300-2611, Japan
| | - Makoto Sawada
- Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 464-8601, Japan
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30
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Hulswit RJG, Paesen GC, Bowden TA, Shi X. Recent Advances in Bunyavirus Glycoprotein Research: Precursor Processing, Receptor Binding and Structure. Viruses 2021; 13:353. [PMID: 33672327 PMCID: PMC7926653 DOI: 10.3390/v13020353] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/13/2021] [Accepted: 02/15/2021] [Indexed: 01/04/2023] Open
Abstract
The Bunyavirales order accommodates related viruses (bunyaviruses) with segmented, linear, single-stranded, negative- or ambi-sense RNA genomes. Their glycoproteins form capsomeric projections or spikes on the virion surface and play a crucial role in virus entry, assembly, morphogenesis. Bunyavirus glycoproteins are encoded by a single RNA segment as a polyprotein precursor that is co- and post-translationally cleaved by host cell enzymes to yield two mature glycoproteins, Gn and Gc (or GP1 and GP2 in arenaviruses). These glycoproteins undergo extensive N-linked glycosylation and despite their cleavage, remain associated to the virion to form an integral transmembrane glycoprotein complex. This review summarizes recent advances in our understanding of the molecular biology of bunyavirus glycoproteins, including their processing, structure, and known interactions with host factors that facilitate cell entry.
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Affiliation(s)
- Ruben J. G. Hulswit
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Guido C. Paesen
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Thomas A. Bowden
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (R.J.G.H.); (G.C.P.)
| | - Xiaohong Shi
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow G61 1QH, UK
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31
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Spitz C, Schlosser C, Guschtschin-Schmidt N, Stelzer W, Menig S, Götz A, Haug-Kröper M, Scharnagl C, Langosch D, Muhle-Goll C, Fluhrer R. Non-canonical Shedding of TNFα by SPPL2a Is Determined by the Conformational Flexibility of Its Transmembrane Helix. iScience 2020; 23:101775. [PMID: 33294784 PMCID: PMC7689174 DOI: 10.1016/j.isci.2020.101775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/21/2020] [Accepted: 11/03/2020] [Indexed: 12/22/2022] Open
Abstract
Ectodomain (EC) shedding defines the proteolytic removal of a membrane protein EC and acts as an important molecular switch in signaling and other cellular processes. Using tumor necrosis factor (TNF)α as a model substrate, we identify a non-canonical shedding activity of SPPL2a, an intramembrane cleaving aspartyl protease of the GxGD type. Proline insertions in the TNFα transmembrane (TM) helix strongly increased SPPL2a non-canonical shedding, while leucine mutations decreased this cleavage. Using biophysical and structural analysis, as well as molecular dynamic simulations, we identified a flexible region in the center of the TNFα wildtype TM domain, which plays an important role in the processing of TNFα by SPPL2a. This study combines molecular biology, biochemistry, and biophysics to provide insights into the dynamic architecture of a substrate's TM helix and its impact on non-canonical shedding. Thus, these data will provide the basis to identify further physiological substrates of non-canonical shedding in the future.
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Affiliation(s)
- Charlotte Spitz
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Christine Schlosser
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Nadja Guschtschin-Schmidt
- Karlsruhe Institute of Technology, Institute for Biological Interfaces 4, 76344 Eggenstein- Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute of Organic Chemistry, 76131 Karlsruhe, Germany
| | - Walter Stelzer
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Simon Menig
- Physics of Synthetic Biological Systems, Technische Universität München, Maximus-von-Imhof Forum 4, 85340 Freising, Germany
| | - Alexander Götz
- Present Address: Leibniz Supercomputing Centre, Boltzmannstr. 1, 85748 Garching, Germany
| | - Martina Haug-Kröper
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
| | - Christina Scharnagl
- Physics of Synthetic Biological Systems, Technische Universität München, Maximus-von-Imhof Forum 4, 85340 Freising, Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany
| | - Claudia Muhle-Goll
- Karlsruhe Institute of Technology, Institute for Biological Interfaces 4, 76344 Eggenstein- Leopoldshafen, Germany and Karlsruhe Institute of Technology, Institute of Organic Chemistry, 76131 Karlsruhe, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Institute of Theoretical Medicine, Medical Faculty, University of Augsburg, Universitätsstrasse 2, 86159 Augsburg, Germany
- DZNE – German Center for Neurodegenerative Diseases, Feodor-Lynen-Str 17, 81377 Munich, Germany
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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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Kawaguchi K, Kaneko S. Notch Signaling and Liver Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1287:69-80. [PMID: 33034027 DOI: 10.1007/978-3-030-55031-8_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Interactions between liver cells are closely regulated by Notch signaling. Notch signaling has been reported clinically related to bile duct hypogenesis in Alagille syndrome, which is caused by mutations in the Jagged1 gene. Notch activation and hepatocarcinogenesis are closely associated since cancer signaling is affected by the development of liver cells and cancer stem cells. Gene expression and genomic analysis using a microarray revealed that abnormalities in Notch-related genes were associated with the aggressiveness of liver cancer. This pattern was also accompanied with α-fetoprotein- and EpCAM-expressing phenotypes in vitro, in vivo, and in clinical tissues. Hepatitis B or C virus chronic infection or alcohol- or steatosis-related liver fibrosis induces liver cancer. Previous reports demonstrated that HBx, a hepatitis B virus protein, was associated with Jagged1 expression. We found that the Jagged1 and Notch1 signaling pathways were closely associated with the transcription of covalently closed circular hepatitis B virus DNA, which regulated cAMP response element-binding protein, thereby affecting Notch1 regulation by the E3 ubiquitin ligase ITCH. This viral pathogenesis in hepatocytes induces liver cancer. In conclusion, Notch signaling exerts various actions and is a clinical signature associated with hepatocarcinogenesis and liver context-related developmental function.
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Affiliation(s)
- Kazunori Kawaguchi
- Department of Gastroenterology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
| | - Shuichi Kaneko
- Department of Gastroenterology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
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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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Mentrup T, Cabrera-Cabrera F, Fluhrer R, Schröder B. Physiological functions of SPP/SPPL intramembrane proteases. Cell Mol Life Sci 2020; 77:2959-2979. [PMID: 32052089 PMCID: PMC7366577 DOI: 10.1007/s00018-020-03470-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/09/2020] [Accepted: 01/22/2020] [Indexed: 01/07/2023]
Abstract
Intramembrane proteolysis describes the cleavage of substrate proteins within their hydrophobic transmembrane segments. Several families of intramembrane proteases have been identified including the aspartyl proteases Signal peptide peptidase (SPP) and its homologues, the SPP-like (SPPL) proteases SPPL2a, SPPL2b, SPPL2c and SPPL3. As presenilin homologues, they employ a similar catalytic mechanism as the well-studied γ-secretase. However, SPP/SPPL proteases cleave transmembrane proteins with a type II topology. The characterisation of SPP/SPPL-deficient mouse models has highlighted a still growing spectrum of biological functions and also promoted the substrate discovery of these proteases. In this review, we will summarise the current hypotheses how phenotypes of these mouse models are linked to the molecular function of the enzymes. At the cellular level, SPP/SPPL-mediated cleavage events rather provide specific regulatory switches than unspecific bulk proteolysis. By this means, a plethora of different cell biological pathways is influenced including signal transduction, membrane trafficking and protein glycosylation.
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Affiliation(s)
- Torben Mentrup
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - Florencia Cabrera-Cabrera
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany
| | - Regina Fluhrer
- Biochemistry and Molecular Biology, Faculty of Medicine, University of Augsburg, Universitätsstraße 2, 86135, Augsburg, Germany
- Biomedizinisches Centrum (BMC), Ludwig Maximilians University of Munich, Feodor-Lynen-Strasse 17, 81377, Munich, Germany
- DZNE-German Center for Neurodegenerative Diseases, Munich, Feodor-Lynen-Strasse 17, 81377, Munich, Germany
| | - Bernd Schröder
- Institute for Physiological Chemistry, Medizinisch-Theoretisches Zentrum MTZ, Technische Universität Dresden, Fiedlerstraße 42, 01307, Dresden, Germany.
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Kusunoki K, Hoshi M, Tamura T, Maeda T, Abe K, Asakura T. Yeast-based reporter assay system for identifying the requirements of intramembrane proteolysis by signal peptide peptidase of Arabidopsis thaliana. FEBS Open Bio 2020; 10:1833-1842. [PMID: 32686366 PMCID: PMC7459403 DOI: 10.1002/2211-5463.12936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/11/2020] [Accepted: 07/05/2020] [Indexed: 11/09/2022] Open
Abstract
Signal peptide peptidase (SPP) is an aspartic protease with two active sites, YD and GXGD, in the transmembrane domain. SPP cleaves signal peptides, and the released fragments play key roles in the immune system, embryo development and protein turnover in cells. Despite SPP having an important function, a general system to identify the requirements of intramembrane proteolysis by SPP has not been developed because proteolysis occurs in the membrane. In this study, we first established a reporter assay system in yeast to verify the cleavage activity of the Arabidopsis thaliana SPP (AtSPP). Next, we screened candidate substrates of AtSPP from A. thaliana pollen and roots. In the pollen, 13 signal peptides with 'pollen' and 'cell wall' as gene ontology terms were selected. In the roots, mutants overexpressing AtSPP were constructed, and gene expression changes were compared with the wild‐type. Nine signal peptides expressed in the roots were selected. Then we used the candidate substrates in our reporter assay system to determine the requirements for proteolysis by AtSPP. Fifteen of 22 signal peptides were cleaved by AtSPP. The absence of the positively charged amino acids, His and Lys on the C terminus of the signal sequence, was observed in cleaved substrates. Moreover, mutation of a helix breaker‐to‐Leu substitution in the intramembrane region in substrates prevented cleavage by AtSPP. These results indicated that substrates of AtSPP required the helix breaker structure to be cleaved.
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Affiliation(s)
- Kenta Kusunoki
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan
| | - Masako Hoshi
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan
| | - Tomoko Tamura
- Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Tatsuya Maeda
- Department of Biology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Keiko Abe
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan
| | - Tomiko Asakura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan
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Hartigan A, Kosakyan A, Pecková H, Eszterbauer E, Holzer AS. Transcriptome of Sphaerospora molnari (Cnidaria, Myxosporea) blood stages provides proteolytic arsenal as potential therapeutic targets against sphaerosporosis in common carp. BMC Genomics 2020; 21:404. [PMID: 32546190 PMCID: PMC7296530 DOI: 10.1186/s12864-020-6705-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 03/27/2020] [Indexed: 01/24/2023] Open
Abstract
Background Parasites employ proteases to evade host immune systems, feed and replicate and are often the target of anti-parasite strategies to disrupt these interactions. Myxozoans are obligate cnidarian parasites, alternating between invertebrate and fish hosts. Their genes are highly divergent from other metazoans, and available genomic and transcriptomic datasets are limited. Some myxozoans are important aquaculture pathogens such as Sphaerospora molnari replicating in the blood of farmed carp before reaching the gills for sporogenesis and transmission. Proliferative stages cause a massive systemic lymphocyte response and the disruption of the gill epithelia by spore-forming stages leads to respiratory problems and mortalities. In the absence of a S. molnari genome, we utilized a de novo approach to assemble the first transcriptome of proliferative myxozoan stages to identify S. molnari proteases that are upregulated during the first stages of infection when the parasite multiplies massively, rather than in late spore-forming plasmodia. Furthermore, a subset of orthologs was used to characterize 3D structures and putative druggable targets. Results An assembled and host filtered transcriptome containing 9436 proteins, mapping to 29,560 contigs was mined for protease virulence factors and revealed that cysteine proteases were most common (38%), at a higher percentage than other myxozoans or cnidarians (25–30%). Two cathepsin Ls that were found upregulated in spore-forming stages with a presenilin like aspartic protease and a dipeptidyl peptidase. We also identified downregulated proteases in the spore-forming development when compared with proliferative stages including an astacin metallopeptidase and lipases (qPCR). In total, 235 transcripts were identified as putative proteases using a MEROPS database. In silico analysis of highly transcribed cathepsins revealed potential drug targets within this data set that should be prioritised for development. Conclusions In silico surveys for proteins are essential in drug discovery and understanding host-parasite interactions in non-model systems. The present study of S. molnari’s protease arsenal reveals previously unknown proteases potentially used for host exploitation and immune evasion. The pioneering dataset serves as a model for myxozoan virulence research, which is of particular importance as myxozoan diseases have recently been shown to emerge and expand geographically, due to climate change.
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Affiliation(s)
- Ashlie Hartigan
- Institute of Parasitology, Biology Centre, Czech Academy of Science, České Budějovice, Czechia.
| | - Anush Kosakyan
- Institute of Parasitology, Biology Centre, Czech Academy of Science, České Budějovice, Czechia
| | - Hana Pecková
- Institute of Parasitology, Biology Centre, Czech Academy of Science, České Budějovice, Czechia
| | - Edit Eszterbauer
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary
| | - Astrid S Holzer
- Institute of Parasitology, Biology Centre, Czech Academy of Science, České Budějovice, Czechia
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Liu X, Zhao J, Zhang Y, Ubarretxena-Belandia I, Forth S, Lieberman RL, Wang C. Substrate-Enzyme Interactions in Intramembrane Proteolysis: γ-Secretase as the Prototype. Front Mol Neurosci 2020; 13:65. [PMID: 32508589 PMCID: PMC7248309 DOI: 10.3389/fnmol.2020.00065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/03/2020] [Indexed: 11/15/2022] Open
Abstract
Intramembrane-cleaving proteases (I-CLiPs) catalyze the hydrolysis of peptide bonds within the transmembrane regions of membrane protein substrates, releasing bioactive fragments that play roles in many physiological and pathological processes. Based on their catalytic mechanism and nucleophile, I-CLiPs are classified into metallo, serine, aspartyl, and glutamyl proteases. Presenilin is the most prominent among I-CLiPs, as the catalytic subunit of γ-secretase (GS) complex responsible for cleaving the amyloid precursor protein (APP) and Notch, as well as many other membrane substrates. Recent cryo-electron microscopy (cryo-EM) structures of GS provide new details on how presenilin recognizes and cleaves APP and Notch. First, presenilin transmembrane helix (TM) 2 and 6 are dynamic. Second, upon binding to GS, the substrate TM helix is unwound from the C-terminus, resulting in an intermolecular β-sheet between the substrate and presenilin. The transition of the substrate C-terminus from α-helix to β-sheet is proposed to expose the scissile peptide bond in an extended conformation, leaving it susceptible to protease cleavage. Despite the astounding new insights in recent years, many crucial questions remain unanswered regarding the inner workings of γ-secretase, however. Key unanswered questions include how the enzyme recognizes and recruits substrates, how substrates are translocated from an initial docking site to the active site, how active site aspartates recruit and coordinate catalytic water, and the nature of the mechanisms of processive trimming of the substrate and product release. Answering these questions will have important implications for drug discovery aimed at selectively reducing the amyloid load in Alzheimer's disease (AD) with minimal side effects.
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Affiliation(s)
- Xinyue Liu
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Jing Zhao
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Yingkai Zhang
- Department of Chemistry, New York University, New York, NY, United States
| | - Iban Ubarretxena-Belandia
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Scott Forth
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, United States
| | - Chunyu Wang
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, United States
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, United States
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39
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The Metastable XBP1u Transmembrane Domain Defines Determinants for Intramembrane Proteolysis by Signal Peptide Peptidase. Cell Rep 2020; 26:3087-3099.e11. [PMID: 30865896 DOI: 10.1016/j.celrep.2019.02.057] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 12/07/2018] [Accepted: 02/14/2019] [Indexed: 11/23/2022] Open
Abstract
Unspliced XBP1 mRNA encodes XBP1u, the transcriptionally inert variant of the unfolded protein response (UPR) transcription factor XBP1s. XBP1u targets its mRNA-ribosome-nascent-chain-complex to the endoplasmic reticulum (ER) to facilitate UPR activation and prevents overactivation. Yet, its membrane association is controversial. Here, we use cell-free translocation and cellular assays to define a moderately hydrophobic stretch in XBP1u that is sufficient to mediate insertion into the ER membrane. Mutagenesis of this transmembrane (TM) region reveals residues that facilitate XBP1u turnover by an ER-associated degradation route that is dependent on signal peptide peptidase (SPP). Furthermore, the impact of these mutations on TM helix dynamics was assessed by residue-specific amide exchange kinetics, evaluated by a semi-automated algorithm. Based on our results, we suggest that SPP-catalyzed intramembrane proteolysis of TM helices is not only determined by their conformational flexibility, but also by side-chain interactions near the scissile peptide bond with the enzyme's active site.
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40
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van Kempen TS, Leijten EFA, Lindenbergh MFS, Nordkamp MO, Driessen C, Lebbink RJ, Baerlecken N, Witte T, Radstake TRDJ, Boes M. Impaired proteolysis by SPPL2a causes CD74 fragment accumulation that can be recognized by anti-CD74 autoantibodies in human ankylosing spondylitis. Eur J Immunol 2020; 50:1209-1219. [PMID: 32198923 PMCID: PMC7496470 DOI: 10.1002/eji.201948502] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 02/10/2020] [Indexed: 12/14/2022]
Abstract
Ankylosing spondylitis (AS) is associated with autoantibody production to class II MHC‐associated invariant chain peptide, CD74/CLIP. In this study, we considered that anti‐CD74/CLIP autoantibodies present in sera from AS might recognize CD74 degradation products that accumulate upon deficiency of the enzyme signal peptide peptidase‐like 2A (SPPL2a). We analyzed monocytes from healthy controls (n = 42), psoriatic arthritis (n = 25), rheumatoid arthritis (n = 16), and AS patients (n = 15) for SPPL2a enzyme activity and complemented the experiments using SPPL2a‐sufficient and ‐deficient THP‐1 cells. We found defects in SPPL2a function and CD74 processing in a subset of AS patients, which culminated in CD74 and HLA class II display at the cell surface. These findings were verified in SPPL2a‐deficient THP‐1 cells, which showed expedited expression of MHC class II, total CD74 and CD74 N‐terminal degradation products at the plasma membrane upon receipt of an inflammatory trigger. Furthermore, we observed that IgG anti‐CD74/CLIP autoantibodies recognize CD74 N‐terminal degradation products that accumulate upon SPPL2a defect. In conclusion, reduced activity of SPPL2a protease in monocytes from AS predisposes to endosomal accumulation of CD74 and CD74 N‐terminal fragments, which, upon IFN‐γ‐exposure, is deposited at the plasma membrane and can be recognized by anti‐CD74/CLIP autoantibodies.
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Affiliation(s)
- Tessa S van Kempen
- Department of Rheumatology & Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Emmerik F A Leijten
- Department of Rheumatology & Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marthe F S Lindenbergh
- Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Michel Olde Nordkamp
- Department of Rheumatology & Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Christoph Driessen
- Department of Oncology and Hematology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | - Robert-Jan Lebbink
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Niklas Baerlecken
- Department of Clinical Immunology and Rheumatology, Medical University Hannover, Hannover, Germany
| | - Torsten Witte
- Department of Clinical Immunology and Rheumatology, Medical University Hannover, Hannover, Germany
| | - Timothy R D J Radstake
- Department of Rheumatology & Clinical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marianne Boes
- Center for Translational Immunology, University Medical Center Utrecht, Utrecht, The Netherlands.,Department of Pediatrics, University Medical Center Utrecht, Utrecht, the Netherlands
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Cai T, Tomita T. Structure-activity relationship of presenilin in γ-secretase-mediated intramembrane cleavage. Semin Cell Dev Biol 2020; 105:102-109. [PMID: 32171519 DOI: 10.1016/j.semcdb.2020.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 01/12/2023]
Abstract
Genetic research on familial cases of Alzheimer disease have identified presenilin (PS) as an important membrane protein in the pathomechanism of this disease. PS is the catalytic subunit of γ-secretase, which is responsible for the generation of amyloid-β peptide deposited in the brains of Alzheimer disease patients. γ-Secretase is an atypical protease composed of four membrane proteins (i.e., presenilin, nicastrin, anterior pharynx defective-1 (Aph-1), and presenilin enhancer-2 (Pen-2)) and mediates intramembrane proteolysis. Numerous investigations have been conducted toward understanding the structural features of γ-secretase components as well as the cleavage mechanism of γ-secretase. In this review, we summarize our current understanding of the structure and activity relationship of the γ-secretase complex.
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Affiliation(s)
- Tetsuo Cai
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Taisuke Tomita
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.
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42
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Wolfe MS. Unraveling the complexity of γ-secretase. Semin Cell Dev Biol 2020; 105:3-11. [PMID: 31980377 PMCID: PMC7371508 DOI: 10.1016/j.semcdb.2020.01.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/26/2019] [Accepted: 01/15/2020] [Indexed: 01/07/2023]
Abstract
γ-Secretase was initially defined as a proteolytic activity that cleaves within the transmembrane of the amyloid precursor protein (APP) to produce the amyloid β-peptide of Alzheimer's disease. The discovery of mutations in APP and the presenilins associated with familial Alzheimer's disease and their effects on APP processing dovetailed with pharmacological studies on γ-secretase, leading to the revelation that presenilins are unprecedented membrane-embedded aspartyl proteases. Other members of what became known as the γ-secretase complex were subsequently identified. In parallel with these advances, connections between presenilins and Notch receptors essential to metazoan development became evident, resulting in the concurrent realization that γ-secretase also carries out intramembrane proteolysis of Notch as part of its signaling mechanism. Substantial progress has been made toward elucidating how γ-secretase carries out complex processing of transmembrane domains, how it goes awry in familial Alzheimer's disease, the scope of its substrates, and the atomic details of its structure. Critical questions remain for future study, toward further unraveling the complexity of this unique membrane-embedded proteolytic machine and its roles in biology and disease.
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Affiliation(s)
- Michael S Wolfe
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66045, USA.
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43
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Barniol-Xicota M, Verhelst SHL. Isolation of intramembrane proteases in membrane-like environments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183193. [PMID: 31945321 DOI: 10.1016/j.bbamem.2020.183193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/07/2020] [Accepted: 01/10/2020] [Indexed: 12/24/2022]
Abstract
Intramembrane proteases (IMPs) are proteolytic enzymes embedded in the lipid bilayer, where they cleave transmembrane substrates. The importance of IMPs relies on their role in a wide variety of cellular processes and diseases. In order to study the activity and function of IMPs, their purified form is often desired. The production of pure and active IMPs has proven to be a challenging task. This process unavoidably requires the use of solubilizing agents that will, to some extent, alter the native environment of these proteases. In this review we present the current solubilization and reconstitution techniques that have been applied to IMPs. In addition, we describe how these techniques had an influence on the activity and structural studies of IMPs, focusing on rhomboid proteases and γ-secretase.
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Affiliation(s)
- Marta Barniol-Xicota
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49, Box 802, B-3000, Belgium.
| | - Steven H L Verhelst
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49, Box 802, B-3000, Belgium; Leibniz Institute for Analytical Sciences, ISAS, e.V., Otto-Hahn-Str. 6b, 44227 Dortmund, Germany.
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Perez MAS, Bassani-Sternberg M, Coukos G, Gfeller D, Zoete V. Analysis of Secondary Structure Biases in Naturally Presented HLA-I Ligands. Front Immunol 2019; 10:2731. [PMID: 31824508 PMCID: PMC6883762 DOI: 10.3389/fimmu.2019.02731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 11/07/2019] [Indexed: 12/31/2022] Open
Abstract
Recent clinical developments in antitumor immunotherapy involving T-cell related therapeutics have led to a renewed interest for human leukocyte antigen class I (HLA-I) binding peptides, given their potential use as peptide vaccines. Databases of HLA-I binding peptides hold therefore information on therapeutic targets essential for understanding immunity. In this work, we use in depth and accurate HLA-I peptidomics datasets determined by mass-spectrometry (MS) and analyze properties of the HLA-I binding peptides with structure-based computational approaches. HLA-I binding peptides are studied grouping all alleles together or in allotype-specific contexts. We capitalize on the increasing number of structurally determined proteins to (1) map the 3D structure of HLA-I binding peptides into the source proteins for analyzing their secondary structure and solvent accessibility in the protein context, and (2) search for potential differences between these properties in HLA-I binding peptides and in a reference dataset of HLA-I motif-like peptides. This is performed by an in-house developed heuristic search that considers peptides across all the human proteome and converges to a collection of peptides that exhibit exactly the same motif as the HLA-I peptides. Our results, based on 9-mers matched to protein 3D structures, clearly show enriched sampling for HLA-I presentation of helical fragments in the source proteins. This enrichment is significant, as compared to 9-mer HLA-I motif-like peptides, and is not entirely explained by the helical propensity of the preferred residues in the HLA-I motifs. We give possible hypothesis for the secondary structure biases observed in HLA-I peptides. This contribution is of potential interest for researchers working in the field of antigen presentation and proteolysis. This knowledge refines the understanding of the rules governing antigen presentation and could be added to the parameters of the current peptide-MHC class I binding predictors to increase their antigen predictive ability.
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Affiliation(s)
- Marta A S Perez
- Computer-Aided Molecular Engineering, Department of Oncology, Ludwig Institute for Cancer Research, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Michal Bassani-Sternberg
- Human Integrated Tumor Immunology Discovery Engine, Department of Oncology, Ludwig Institute for Cancer Research, University Hospital of Lausanne, Lausanne, Switzerland
| | - George Coukos
- Human Integrated Tumor Immunology Discovery Engine, Department of Oncology, Ludwig Institute for Cancer Research, University Hospital of Lausanne, Lausanne, Switzerland
| | - David Gfeller
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Computational Cancer Biology, Department of Oncology, Ludwig Institute for Cancer Research, University of Lausanne, Lausanne, Switzerland
| | - Vincent Zoete
- Computer-Aided Molecular Engineering, Department of Oncology, Ludwig Institute for Cancer Research, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
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45
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Beard HA, Barniol-Xicota M, Yang J, Verhelst SHL. Discovery of Cellular Roles of Intramembrane Proteases. ACS Chem Biol 2019; 14:2372-2388. [PMID: 31287658 DOI: 10.1021/acschembio.9b00404] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Intramembrane proteases (IMPs) are localized within lipid bilayers of membranes-either the cell membrane or membranes of various organelles. Cleavage of substrates often results in release from the membrane, leading to a downstream biological effect. This mechanism allows different signaling events to happen through intramembrane proteolysis. Over the years, various mechanistically distinct families of IMPs have been discovered, but the research progress has generally been slower than for soluble proteases due to the challenges associated with membrane proteins. In this review we summarize how each mechanistic family of IMPs was discovered, which chemical tools are available for the study of IMPs, and which techniques have been developed for the discovery of IMP substrates. Finally, we discuss the various roles in cellular physiology of some of these IMPs.
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Affiliation(s)
- Hester A. Beard
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestr. 49, 3000 Leuven, Belgium
| | - Marta Barniol-Xicota
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestr. 49, 3000 Leuven, Belgium
| | - Jian Yang
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestr. 49, 3000 Leuven, Belgium
| | - Steven H. L. Verhelst
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestr. 49, 3000 Leuven, Belgium
- Leibniz Institute for Analytical Sciences ISAS, Otto-Hahn-Str. 6b, 44227 Dortmund, Germany
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Absence of Signal Peptide Peptidase, an Essential Herpes Simplex Virus 1 Glycoprotein K Binding Partner, Reduces Virus Infectivity In Vivo. J Virol 2019; 93:JVI.01309-19. [PMID: 31511378 DOI: 10.1128/jvi.01309-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 09/02/2019] [Indexed: 12/12/2022] Open
Abstract
We previously reported that herpes simplex virus (HSV) glycoprotein K (gK) binds to signal peptide peptidase (SPP), also known as minor histocompatibility antigen H13. Binding of gK to SPP is required for HSV-1 infectivity in vitro SPP is a member of the γ-secretase family, and mice lacking SPP are embryonic lethal. To determine how SPP affects HSV-1 infectivity in vivo, the SPP gene was deleted using a tamoxifen-inducible Cre recombinase driven by the ubiquitously expressed ROSA26 promoter. SPP mRNA was reduced by more than 93% in the cornea and trigeminal ganglia (TG) and by 99% in the liver of tamoxifen-injected mice, while SPP protein expression was reduced by 90% compared to the level in control mice. Mice lacking SPP had significantly less HSV-1 replication in the eye as well as reduced gK, UL20, ICP0, and gB transcripts in the cornea and TG compared to levels in control mice. In addition, reduced infiltration of CD45+, CD4+, CD8+, F4/80+, CD11c+, and NK1.1+ T cells was observed in the cornea and TG of SPP-inducible knockout mice compared to that in control mice. Finally, in the absence of SPP, latency was significantly reduced in SPP-inducible knockout mice compared to that in control mice. Thus, in this study we have generated SPP-inducible knockout mice and shown that the absence of SPP affects virus replication in the eye of ocularly infected mice and that this reduction is correlated with the interaction of gK and SPP. These results suggest that blocking this interaction may have therapeutic potential in treating HSV-1-associated eye disease.IMPORTANCE Glycoprotein K (gK) is an essential and highly conserved HSV-1 protein. Previously, we reported that gK binds to SPP, an endoplasmic reticulum (ER) protein, and blocking this binding reduces virus infectivity in vitro and also affects gK and UL20 subcellular localization. To evaluate the function of gK binding to SPP in vivo, we generated SPP-inducible knockout mice and observed the following in the absence of SPP: (i) that significantly less HSV-1 replication was seen in ocularly infected mice than in control mice; (ii) that expression of various HSV-1 genes and cellular infiltrates in the eye and trigeminal ganglia of infected mice was less than that in control mice; and (iii) that latency was significantly reduced in infected mice. Thus, blocking of gK binding to SPP may be a useful tool to control HSV-1-induced eye disease in patients with herpes stromal keratitis (HSK).
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Schwake C, Baldwin MR, Bachovchin W, Hegde S, Schiemer J, Okure C, Levin AE, Vannier E, Hanada T, Chishti AH. HIV protease inhibitors block parasite signal peptide peptidases and prevent growth of Babesia microti parasites in erythrocytes. Biochem Biophys Res Commun 2019; 517:125-131. [PMID: 31311649 PMCID: PMC6707064 DOI: 10.1016/j.bbrc.2019.07.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 07/09/2019] [Indexed: 12/11/2022]
Abstract
Malaria and babesiosis are bloodborne protozoan infections for which the emergence of drug-resistant strains poses a threat. Our previous phage display cDNA screens established the essentiality of Plasmodium falciparum signal peptide peptidase (SPP) in asexual development at the blood stage of malaria infection. Given the structural similarities between SPP inhibitors and HIV protease inhibitors, we screened ten HIV protease inhibitors and selected Lopinavir and Atazanavir for their ability to inhibit PfSPP activity. Using a transcription-based assay, we observed that Lopinavir inhibits both parasite-and host-derived SPP activities whereas Atazanavir inhibited only parasite derived SPP activity. Consistent with their inhibitory effect on Plasmodium growth, both Lopinavir and Atazanavir strongly inhibited intraerythrocytic Babesia microti growth ex vivo. Moreover, Lopinavir prevented the steep rise in Babesia microti parasitemia typically observed in rag1-deficient mice. Our data provide first evidence that inhibition of parasite-derived SPPs by HIV protease inhibitors offers a promising therapeutic avenue for the treatment of severe babesiosis and infections caused by other Apicomplexa parasites.
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Affiliation(s)
- Christopher Schwake
- Graduate Program in Cellular, Molecular, and Developmental Biology, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Michael R Baldwin
- Graduate Program in Cellular and, Molecular Physiology, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - William Bachovchin
- Graduate Program in Pharmacology and Experimental Therapeutics, USA; Department of Developmental, Molecular and Chemical Biology, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Shreeya Hegde
- Graduate Program in Pharmacology and Experimental Therapeutics, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - James Schiemer
- Graduate Program in Cellular and, Molecular Physiology, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Carolyn Okure
- Graduate Program in Pharmacology and Experimental Therapeutics, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | | | - Edouard Vannier
- Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Boston, MA, 02111, USA
| | - Toshihiko Hanada
- Department of Developmental, Molecular and Chemical Biology, USA
| | - Athar H Chishti
- Graduate Program in Cellular, Molecular, and Developmental Biology, USA; Graduate Program in Cellular and, Molecular Physiology, USA; Graduate Program in Pharmacology and Experimental Therapeutics, USA; Department of Developmental, Molecular and Chemical Biology, USA; Graduate Program in Molecular Microbiology, USA; Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA.
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Knapp B, Roedig J, Boldt K, Krzysko J, Horn N, Ueffing M, Wolfrum U. Affinity proteomics identifies novel functional modules related to adhesion GPCRs. Ann N Y Acad Sci 2019; 1456:144-167. [PMID: 31441075 DOI: 10.1111/nyas.14220] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 07/08/2019] [Accepted: 07/25/2019] [Indexed: 01/04/2023]
Abstract
Adhesion G protein-coupled receptors (ADGRs) have recently become a target of intense research. Their unique protein structure, which consists of a G protein-coupled receptor combined with long adhesive extracellular domains, suggests a dual role in cell signaling and adhesion. Despite considerable progress in the understanding of ADGR signaling over the past years, the knowledge about ADGR protein networks is still limited. For most receptors, only a few interaction partners are known thus far. We aimed to identify novel ADGR-interacting partners to shed light on cellular protein networks that rely on ADGR function. For this, we applied affinity proteomics, utilizing tandem affinity purifications combined with mass spectrometry. Analysis of the acquired proteomics data provides evidence that ADGRs not only have functional roles at synapses but also at intracellular membranes, namely at the endoplasmic reticulum, the Golgi apparatus, mitochondria, and mitochondria-associated membranes (MAMs). Specifically, we found an association of ADGRs with several scaffold proteins of the membrane-associated guanylate kinases family, elementary units of the γ-secretase complex, the outer/inner mitochondrial membrane, MAMs, and regulators of the Wnt signaling pathways. Furthermore, the nuclear localization of ADGR domains together with their physical interaction with nuclear proteins and several transcription factors suggests a role of ADGRs in gene regulation.
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Affiliation(s)
- Barbara Knapp
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Jens Roedig
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Karsten Boldt
- Institute for Ophthalmic Research and Medical Bioanalytics, Centre for Ophthalmology, Eberhard-Karls University Tübingen, Tübingen, Germany
| | - Jacek Krzysko
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University of Mainz, Mainz, Germany
| | - Nicola Horn
- Institute for Ophthalmic Research and Medical Bioanalytics, Centre for Ophthalmology, Eberhard-Karls University Tübingen, Tübingen, Germany
| | - Marius Ueffing
- Institute for Ophthalmic Research and Medical Bioanalytics, Centre for Ophthalmology, Eberhard-Karls University Tübingen, Tübingen, Germany
| | - Uwe Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg University of Mainz, Mainz, Germany
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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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50
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Peng H, Hulleman JD. Prospective Application of Activity-Based Proteomic Profiling in Vision Research-Potential Unique Insights into Ocular Protease Biology and Pathology. Int J Mol Sci 2019; 20:ijms20163855. [PMID: 31398819 PMCID: PMC6720450 DOI: 10.3390/ijms20163855] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 07/30/2019] [Indexed: 12/12/2022] Open
Abstract
Activity-based proteomic profiling (ABPP) is a powerful tool to specifically target and measure the activity of a family of enzymes with the same function and reactivity, which provides a significant advantage over conventional proteomic strategies that simply provide abundance information. A number of inherited and age-related eye diseases are caused by polymorphisms/mutations or abnormal expression of proteases including serine proteases, cysteine proteases, and matrix metalloproteinases, amongst others. However, neither conventional genomic, transcriptomic, nor traditional proteomic profiling directly interrogate protease activities. Thus, leveraging ABPP to probe the activity of these enzyme classes as they relate to normal function and pathophysiology of the eye represents a unique potential opportunity for disease interrogation and possibly intervention.
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Affiliation(s)
- Hui Peng
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9057, USA
| | - John D Hulleman
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9057, USA.
- Department of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA.
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