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Ribes JM, Patel MP, Halim HA, Berretta A, Tooze SA, Klöhn PC. Prion protein conversion at two distinct cellular sites precedes fibrillisation. Nat Commun 2023; 14:8354. [PMID: 38102121 PMCID: PMC10724300 DOI: 10.1038/s41467-023-43961-1] [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: 05/04/2022] [Accepted: 11/24/2023] [Indexed: 12/17/2023] Open
Abstract
The self-templating nature of prions plays a central role in prion pathogenesis and is associated with infectivity and transmissibility. Since propagation of proteopathic seeds has now been acknowledged a principal pathogenic process in many types of dementia, more insight into the molecular mechanism of prion replication is vital to delineate specific and common disease pathways. By employing highly discriminatory anti-PrP antibodies and conversion-tolerant PrP chimera, we here report that de novo PrP conversion and formation of fibril-like PrP aggregates are distinct in mechanistic and kinetic terms. De novo PrP conversion occurs within minutes after infection at two subcellular locations, while fibril-like PrP aggregates are formed exclusively at the plasma membrane, hours after infection. Phenotypically distinct pools of abnormal PrP at perinuclear sites and the plasma membrane show differences in N-terminal processing, aggregation state and fibril formation and are linked by exocytic transport via synaptic and large-dense core vesicles.
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Affiliation(s)
- Juan Manuel Ribes
- Medical Research Council Prion Unit at UCL, Institute of Prion Diseases, University College London, London, W1W 7FF, UK
| | - Mitali P Patel
- Medical Research Council Prion Unit at UCL, Institute of Prion Diseases, University College London, London, W1W 7FF, UK
| | - Hazim A Halim
- Medical Research Council Prion Unit at UCL, Institute of Prion Diseases, University College London, London, W1W 7FF, UK
| | - Antonio Berretta
- Medical Research Council Prion Unit at UCL, Institute of Prion Diseases, University College London, London, W1W 7FF, UK
| | - Sharon A Tooze
- Molecular Cell Biology of Autophagy Laboratory, the Francis Crick Institute, London, NW1 1BF, UK
| | - Peter-Christian Klöhn
- Medical Research Council Prion Unit at UCL, Institute of Prion Diseases, University College London, London, W1W 7FF, UK.
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Post-Transcriptional Effects of miRNAs on PCSK7 Expression and Function: miR-125a-5p, miR-143-3p, and miR-409-3p as Negative Regulators. Metabolites 2022; 12:metabo12070588. [PMID: 35888711 PMCID: PMC9323720 DOI: 10.3390/metabo12070588] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 12/14/2022] Open
Abstract
The regulatory mechanism of PCSK7 gene is still unknown, although its encoded protein PC7 is the most ancient and highly conserved of all proprotein convertases and exhibits enzymatic and non-enzymatic functions in liver triglyceride regulation. Bioinformatics algorithms were used to predict regulatory microRNAs (miRNAs) of PCSK7 expression. This led to the identification of four miRNAs, namely miR-125a-5p, miR-143-3p, miR-409-3p, and miR-320a-3p, with potential binding sites on the 3′-untranslated region (3′-UTR) of human PCSK7 mRNA. The expression patterns of these miRNAs and PCSK7 mRNA were assessed in three different cell lines with quantitative polymerase chain reaction (qPCR), which revealed reciprocal expression patterns between the expression levels of the four selected miRNAs and PCSK7. Next, the interactions and effects of these miRNAs on PCSK7 expression levels were investigated via cell-based expression analysis, dual-luciferase assay, and Western blot analysis. The data revealed that PCSK7 mRNA levels decreased in cells transfected with vectors overexpressing miR-125a-5p, miR-143-3p, and miR-409-3p, but not miR-320a-3p. The dual-luciferase assay demonstrated that the above three miRNAs could directly interact with putative target sites in PCSK7 3′-UTR and regulate its expression, whereas miR-320-3p exhibited no interaction. Western blot analysis further revealed that the overexpression of miR-125a-5p in Huh7 cells inhibits the expression and ability of PC7 to cleave human transferrin receptor 1. Our results support a regulatory role of these miRNAs on PCSK7 expression and function and open the way to assess their roles in the regulation of PC7 activity in vivo in the development of hepatic steatosis.
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Parvaz N, Jalali Z. Molecular evolution of PCSK family: Analysis of natural selection rate and gene loss. PLoS One 2021; 16:e0259085. [PMID: 34710160 PMCID: PMC8553125 DOI: 10.1371/journal.pone.0259085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 10/12/2021] [Indexed: 12/20/2022] Open
Abstract
Proprotein convertases subtilisin kexins are serine endoproteases, playing critical roles in the biological functions, including lipid, glucose, and bile acid metabolism, as well as cell proliferation, migration, and metastasis. Experimental studies have demonstrated the physiological functions of PCSKs and their association with diseases; however, studies on the evolutionary history and diversification of these proteins are missing. In the present research, a bioinformatics study was conducted on the molecular evolution of several PCSKs family members and gene loss events across placental mammalian. In order to detect evolutionary constraints and positive selection, the CodeML program of the PAML package was used. The results showed the positive selection to occur in PCSK1, PCSK3, PCSK5, and PCSK7. A decelerated rate of evolution was observed in PCSK7, PCSK3, and MBTPS1 in Carnivores compared to the rest of phylogeny, and an accelerated evolution of PCSK1, PCSK7, and MBTPS1 in Muridae family of rodents was found. Additionally, our results indicated pcsk9 gene loss in 12 species comprising Carnivores and bats (Chiroptera). Future studies are required to evaluate the functional relevance and selective evolutionary advantages associated with these modifications in PCSK proteins during evolution.
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Affiliation(s)
- Najmeh Parvaz
- Department of Clinical Biochemistry, School of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Zahra Jalali
- Department of Clinical Biochemistry, School of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- Non-Communicable Diseases Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- * E-mail:
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Abstract
The kexin-like proprotein convertases perform the initial proteolytic cleavages that ultimately generate a variety of different mature peptide and proteins, ranging from brain neuropeptides to endocrine peptide hormones, to structural proteins, among others. In this review, we present a general introduction to proprotein convertase structure and biochemistry, followed by a comprehensive discussion of each member of the kexin-like subfamily of proprotein convertases. We summarize current knowledge of human proprotein convertase insufficiency syndromes, including genome-wide analyses of convertase polymorphisms, and compare these to convertase null and mutant mouse models. These mouse models have illuminated our understanding of the roles specific convertases play in human disease and have led to the identification of convertase-specific substrates; for example, the identification of procorin as a specific PACE4 substrate in the heart. We also discuss the limitations of mouse null models in interpreting human disease, such as differential precursor cleavage due to species-specific sequence differences, and the challenges presented by functional redundancy among convertases in attempting to assign specific cleavages and/or physiological roles. However, in most cases, knockout mouse models have added substantively both to our knowledge of diseases caused by human proprotein convertase insufficiency and to our appreciation of their normal physiological roles, as clearly seen in the case of the furin, proprotein convertase 1/3, and proprotein convertase 5/6 mouse models. The creation of more sophisticated mouse models with tissue- or temporally-restricted expression of specific convertases will improve our understanding of human proprotein convertase insufficiency and potentially provide support for the emerging concept of therapeutic inhibition of convertases.
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Affiliation(s)
- Manita Shakya
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Iris Lindberg
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Durand L, Duval S, Evagelidis A, Guillemot J, Dianati V, Sikorska E, Schu P, Day R, Seidah NG. The motif E XE XXXL in the cytosolic tail of the secretory human proprotein convertase PC7 regulates its trafficking and cleavage activity. J Biol Chem 2020; 295:2068-2083. [PMID: 31915245 DOI: 10.1074/jbc.ra119.011775] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/17/2019] [Indexed: 02/05/2023] Open
Abstract
Many secretory proteins are activated by cleavage at specific sites. The proprotein convertases (PCs) form a family of nine secretory subtilisin-like serine proteases, seven of which cleave at specific basic residues within the trans-Golgi network, granules, or at the cell surface/endosomes. The seventh member, PC7, is a type-I transmembrane (TM) protein with a 97-residue-long cytosolic tail (CT). PC7 sheds human transferrin receptor 1 (hTfR1) into soluble shTfR1 in endosomes. To better understand the physiological roles of PC7, here we focused on the relationship between the CT-regulated trafficking of PC7 and its ability to shed hTfR1. Deletion of the TMCT resulted in soluble PC7 and loss of its hTfR1 shedding activity. Extensive CT deletions and mutagenesis analyses helped us zoom in on three residues in the CT, namely Glu-719, Glu-721, and Leu-725, that are part of a novel motif, EXEXXXL725, critical for PC7 activity on hTfR1. NMR studies of two 14-mer peptides mimicking this region of the CT and its Ala variants revealed that the three exposed residues are on the same side of the molecule. This led to the identification of adaptor protein 2 (AP-2) as a protein that recognizes the EXEXXXL725 motif, thus representing a potentially new regulator of PC7 trafficking and cleavage activity. Immunocytochemistry of the subcellular localization of PC7 and its Ala variants of Leu-725 and Glu-719 and Glu-721 revealed that Leu-725 enhances PC7 localization to early endosomes and that, together with Glu-719 and Glu-721, it increases the endosomal activity of PC7 on hTfR1.
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Affiliation(s)
- Loreleï Durand
- Laboratory of Biochemical Neuroendocrinology, Clinical Research of Montreal, affiliated with Université de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Stéphanie Duval
- Laboratory of Biochemical Neuroendocrinology, Clinical Research of Montreal, affiliated with Université de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Alexandra Evagelidis
- Laboratory of Biochemical Neuroendocrinology, Clinical Research of Montreal, affiliated with Université de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Johann Guillemot
- CIRI, Centre International de Recherche en Infectiologie, Team Pathogenesis of Legionella, INSERM U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, École Normale Supérieure de Lyon, Université Lyon, Villeurbanne, 69100 France
| | - Vahid Dianati
- Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, and Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Quebec J 1H 5N4, Canada
| | - Emilia Sikorska
- Faculty of Chemistry, University of Gdańsk, Gdańsk, 80-233 Poland
| | - Peter Schu
- Department of Cellular Biochemistry, University Medical Center, Göttingen, Humboldtallee 23, 37073 Goettingen, Germany
| | - Robert Day
- Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, and Faculté de Médecine et des Sciences de la Santé, Sherbrooke, Quebec J 1H 5N4, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research of Montreal, affiliated with Université de Montréal, Montreal, Quebec H2W 1R7, Canada.
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Ginefra P, Filippi BGH, Donovan P, Bessonnard S, Constam DB. Compartment-Specific Biosensors Reveal a Complementary Subcellular Distribution of Bioactive Furin and PC7. Cell Rep 2019; 22:2176-2189. [PMID: 29466742 DOI: 10.1016/j.celrep.2018.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 12/13/2017] [Accepted: 01/31/2018] [Indexed: 12/21/2022] Open
Abstract
Furin trafficking, and that of related proprotein convertases (PCs), may regulate which substrates are accessible for endoproteolysis, but tools to directly test this hypothesis have been lacking. Here, we develop targeted biosensors that indicate Furin activity in endosomes is 10-fold less inhibited by decanoyl-RVKR-chloromethylketone and enriched >3-fold in endosomes compared to the trans-Golgi network (TGN). Endogenous PC7, which resists this inhibitor, was active in distinct vesicles. Only overexpressed PC7 activity reached the cell surface, endosomes, and the TGN. A PLC motif in the cytosolic tail of PC7 was dispensable for endosomal activity, but it was specifically required for TGN recycling and to rescue proActivin-A cleavage in Furin-depleted B16F1 melanoma cells. In sharp contrast, PC7 complemented Furin in cleaving Notch1 independently of PLC-mediated TGN access. Our study provides a proof in principle that compartment-specific biosensors can be used to gain insight into the regulation of PC trafficking and to map the tropism of PC-specific inhibitors.
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Affiliation(s)
- Pierpaolo Ginefra
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Bruno G H Filippi
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Prudence Donovan
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Sylvain Bessonnard
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Daniel B Constam
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland.
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Böttcher-Friebertshäuser E, Garten W, Klenk HD. Characterization of Proprotein Convertases and Their Involvement in Virus Propagation. ACTIVATION OF VIRUSES BY HOST PROTEASES 2018. [PMCID: PMC7122180 DOI: 10.1007/978-3-319-75474-1_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | - Wolfgang Garten
- Institut für Virologie, Philipps Universität, Marburg, Germany
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8
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Endosome to trans-Golgi network transport of Proprotein Convertase 7 is mediated by a cluster of basic amino acids and palmitoylated cysteines. Eur J Cell Biol 2017; 96:432-439. [PMID: 28413120 DOI: 10.1016/j.ejcb.2017.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 03/30/2017] [Accepted: 03/30/2017] [Indexed: 11/22/2022] Open
Abstract
Proprotein Convertase 7 (PC7) is a Furin-like endoprotease that cleaves precursor proteins at basic amino acids. PC7 is concentrated in the trans-Golgi network (TGN) but it shuttles between the plasma membrane and the TGN depending on sequences in the cytoplasmic tail. A short region containing a three amino acids motif, P724-L725-C726, is essential and sufficient for internalization of PC7 but not for TGN localization, which requires the additional presence of the juxtamembrane region. In this study we have investigated the contribution of a cluster of basic amino acids and two reversibly palmitoylated cysteine residues to endocytic trafficking. Stable cell lines overexpressing chimeric proteins (CD25 and CD46) containing the cytoplasmic domain of PC7 in which the basic cluster alone or together with both palmitoylated cysteines are mutated showed enhanced surface expression as demonstrated by immunofluorescence experiments and surface biotinylation. The mutant proteins no longer recycled to the TGN in antibody uptake experiments and accumulated in an endosomal compartment. Recycling of wild type PC7 to the TGN is blocked by nocodazole, suggesting that PC7 shuttles to the TGN via late endosomes, similar to Furin. Unlike furin, however, PC7 was found to recycle to a region within the TGN, which is deficient in sialyltransferase, as shown by resialylation experiments. In conclusion, a novel motif, composed of a basic amino acid cluster and two palmitoylated cysteines are essential for TGN localization and endocytic trafficking.
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9
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Anyetei-Anum EN, Blum A, Seidah NG, Beinfeld MC. Prohormone convertase 7 is necessary for the normal processing of cholecystokinin in mouse brain. Biochem Biophys Res Commun 2016; 482:1190-1193. [PMID: 27923657 DOI: 10.1016/j.bbrc.2016.12.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 12/02/2016] [Indexed: 10/20/2022]
Abstract
Endoproteases in the secretory pathway process pro-cholecystokinin (CCK) into the biologically active forms found in the tissues that express CCK mRNA. Thus far, the endoproteases involved in CCK processing include cathepsin L and the prohormone convertases (PC) 1, 2, and 5. This study finds that PC7 is also critical for normal production of CCK in specific areas of the brain. Loss of PC7 results in decreased levels of CCK in more brain regions than any other endoprotease studied to date. Substantial decreases in brain levels of CCK are found in the prefrontal, frontal, parietal-insular-pyriform, and temporal cortex, caudate-putamen, basal forebrain, thalamus, hippocampus, septum, and medulla of PC7 knock-out (KO) mice. A tissue-specific sexual dimorphism of PC7 activity was also identified. This is the first report that loss of PC7 alters levels of a neuropeptide in the brain. This loss of PC7 and CCK may independently contribute to the decrease in Brain Derived Neurotrophic Factor production and be partially responsible for the learning and memory defects observed in mice that lack PC7.
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Affiliation(s)
- Emmanuel N Anyetei-Anum
- Pharmacology and Experimental Therapeutics, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Alissa Blum
- Pharmacology and Experimental Therapeutics, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Montréal, QC, H2W1R7, Canada
| | - Margery C Beinfeld
- Pharmacology and Experimental Therapeutics, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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Robertson MJ, Horatscheck A, Sauer S, von Kleist L, Baker JR, Stahlschmidt W, Nazaré M, Whiting A, Chau N, Robinson PJ, Haucke V, McCluskey A. 5-Aryl-2-(naphtha-1-yl)sulfonamido-thiazol-4(5H)-ones as clathrin inhibitors. Org Biomol Chem 2016; 14:11266-11278. [PMID: 27853797 DOI: 10.1039/c6ob02308h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development of a (Z)-5-((6,8-dichloro-4-oxo-4H-chromen-3-yl)methylene)-2-thioxothiazolidin-4-one (2), rhodanine-based lead that led to the Pitstop® 2 family of clathrin inhibitors is described herein. Head group substitution and bioisosteric replacement of the rhodanine core with a 2-aminothiazol-4(5H)-one scaffold eliminated off target dynamin activity. A series of N-substituents gave first phenylglycine (20, IC50 ∼ 20 μM) then phenyl (25, IC50 ∼ 7.1 μM) and 1-napthyl sulfonamide (26, Pitstop® 2 compound, IC50 ∼ 1.9 μM) analogues with good activity, validating this approach. A final library exploring the head group resulted in three analogues displaying either slight improvements or comparable activity (33, 38, and 29 with IC50 ∼ 1.4, 1.6 and 1.8 μM respectively) and nine others with IC50 < 10 μM. These results were rationalized using in silico docking studies. Docking studies predicted enhanced Pitstop® 2 family binding, not a loss of binding, within the Pistop® groove of the reported clathrin mutant invalidating recent assumptions of poor selectivity for this family of clathrin inhibitors.
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Affiliation(s)
- Mark J Robertson
- Chemistry, Priority Research Centre for Chemical Biology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
| | - André Horatscheck
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Samantha Sauer
- Chemistry, Priority Research Centre for Chemical Biology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
| | - Lisa von Kleist
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Jennifer R Baker
- Chemistry, Priority Research Centre for Chemical Biology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
| | - Wiebke Stahlschmidt
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Marc Nazaré
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Ainslie Whiting
- Cell Signaling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, NSW 2145, Australia
| | - Ngoc Chau
- Cell Signaling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, NSW 2145, Australia
| | - Phillip J Robinson
- Cell Signaling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, NSW 2145, Australia
| | - Volker Haucke
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Adam McCluskey
- Chemistry, Priority Research Centre for Chemical Biology, University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.
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Robertson MJ, Deane FM, Stahlschmidt W, von Kleist L, Haucke V, Robinson PJ, McCluskey A. Synthesis of the Pitstop family of clathrin inhibitors. Nat Protoc 2014; 9:1592-606. [PMID: 24922269 DOI: 10.1038/nprot.2014.106] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This protocol describes the synthesis of two classes of clathrin inhibitors, Pitstop 1 and Pitstop 2, along with two inactive analogs that can be used as negative controls (Pitstop inactive controls, Pitnot-2 and Pitnot-2-100). Pitstop-induced inhibition of clathrin TD function acutely interferes with clathrin-mediated endocytosis (CME), synaptic vesicle recycling and cellular entry of HIV, whereas clathrin-independent internalization pathways and secretory traffic proceed unperturbed; these reagents can, therefore, be used to investigate clathrin function, and they have potential pharmacological applications. Pitstop 1 is synthesized in two steps: sulfonation of 1,8-naphthalic anhydride and subsequent reaction with 4-amino(methyl)aniline. Pitnot-1 results from the reaction of 4-amino(methyl)aniline with commercially available 4-sulfo-1,8-naphthalic anhydride potassium salt. Reaction of 1-naphthalene sulfonyl chloride with pseudothiohydantoin followed by condensation with 4-bromobenzaldehyde yields Pitstop 2. The synthesis of the inactive control commences with the condensation of 4-bromobenzaldehyde with the rhodanine core. Thioketone methylation and displacement with 1-napthylamine affords the target compound. Although Pitstop 1-series compounds are not cell permeable, they can be used in biochemical assays or be introduced into cells via microinjection. The Pitstop 2-series compounds are cell permeable. The synthesis of these compounds does not require specialist equipment and can be completed in 3-4 d. Microwave irradiation can be used to reduce the synthesis time. The synthesis of the Pitstop 2 family is easily adaptable to enable the synthesis of related compounds such as Pitstop 2-100 and Pitnot-2-100. The procedures are also simple, efficient and amenable to scale-up, enabling cost-effective in-house synthesis for users of these inhibitor classes.
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Affiliation(s)
- Mark J Robertson
- 1] Department of Chemistry, Centre for Chemical Biology, School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia. [2]
| | - Fiona M Deane
- 1] Department of Chemistry, Centre for Chemical Biology, School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia. [2]
| | - Wiebke Stahlschmidt
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Berlin, Germany
| | - Lisa von Kleist
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Berlin, Germany
| | - Volker Haucke
- Leibniz Institut für Molekulare Pharmakologie & Freie Universität Berlin, Berlin, Germany
| | - Phillip J Robinson
- Cell Signalling Unit, Children's Medical Research Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Adam McCluskey
- Department of Chemistry, Centre for Chemical Biology, School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia
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Hoogeveen RC, Gaubatz JW, Sun W, Dodge RC, Crosby JR, Jiang J, Couper D, Virani SS, Kathiresan S, Boerwinkle E, Ballantyne CM. Small dense low-density lipoprotein-cholesterol concentrations predict risk for coronary heart disease: the Atherosclerosis Risk In Communities (ARIC) study. Arterioscler Thromb Vasc Biol 2014; 34:1069-77. [PMID: 24558110 PMCID: PMC3999643 DOI: 10.1161/atvbaha.114.303284] [Citation(s) in RCA: 355] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 02/10/2014] [Indexed: 12/24/2022]
Abstract
OBJECTIVE To investigate the relationship between plasma levels of small dense low-density lipoprotein-cholesterol (sdLDL-C) and risk for incident coronary heart disease (CHD) in a prospective study among Atherosclerosis Risk in Communities (ARIC) study participants. APPROACH AND RESULTS Plasma sdLDL-C was measured in 11 419 men and women of the biracial ARIC study using a newly developed homogeneous assay. A proportional hazards model was used to examine the relationship among sdLDL-C, vascular risk factors, and risk for CHD events (n=1158) for a period of ≈11 years. Plasma sdLDL-C levels were strongly correlated with an atherogenic lipid profile and were higher in patients with diabetes mellitus than non-diabetes mellitus (49.6 versus 42.3 mg/dL; P<0.0001). In a model that included established risk factors, sdLDL-C was associated with incident CHD with a hazard ratio of 1.51 (95% confidence interval, 1.21-1.88) for the highest versus the lowest quartile, respectively. Even in individuals considered to be at low cardiovascular risk based on their LDL-C levels, sdLDL-C predicted risk for incident CHD (hazard ratio, 1.61; 95% confidence interval, 1.04-2.49). Genome-wide association analyses identified genetic variants in 8 loci associated with sdLDL-C levels. These loci were in or close to genes previously associated with risk for CHD. We discovered 1 novel locus, PCSK7, for which genetic variation was significantly associated with sdLDL-C and other lipid factors. CONCLUSIONS sdLDL-C was associated with incident CHD in ARIC study participants. The novel association of genetic variants in PCSK7 with sdLDL-C and other lipid traits may provide new insights into the role of this gene in lipid metabolism.
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Affiliation(s)
- Ron C Hoogeveen
- From the Department of Medicine, Baylor College of Medicine and Methodist DeBakey Heart and Vascular Center, Houston, TX (R.C.H., J.W.G., W.S., J.J., S.S.V., C.M.B.); Human Genetics Center, University of Texas Health Science Center School of Public Health, Houston (R.C.D., J.R.C., E.B.); Department of Biostatistics, University of North Carolina at Chapel Hill (D.C.); Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX (S.S.V.); Center for Human Genetic Research and Cardiovascular Research Center, Massachusetts General Hospital, Boston (S.K.); and Department of Medicine, Harvard Medical School, Boston, MA (S.K.)
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Turpeinen H, Ortutay Z, Pesu M. Genetics of the first seven proprotein convertase enzymes in health and disease. Curr Genomics 2014; 14:453-67. [PMID: 24396277 PMCID: PMC3867721 DOI: 10.2174/1389202911314050010] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/13/2013] [Accepted: 09/14/2013] [Indexed: 12/16/2022] Open
Abstract
Members of the substilisin/kexin like proprotein convertase (PCSK) protease family cleave and convert immature pro-proteins into their biologically active forms. By cleaving for example prohormones, cytokines and cell membrane proteins, PCSKs participate in maintaining the homeostasis in a healthy human body. Conversely, erratic enzymatic function is thought to contribute to the pathogenesis of a wide variety of diseases, including obesity and hypercholestrolemia. The first characterized seven PCSK enzymes (PCSK1-2, FURIN, PCSK4-7) process their substrates at a motif made up of paired basic amino acid residues. This feature results in a variable degree of biochemical redundancy in vitro, and consequently, shared substrate molecules between the different PCSK enzymes. This redundancy has confounded our understanding of the specific biological functions of PCSKs. The physiological roles of these enzymes have been best illustrated by the phenotypes of genetically engineered mice and patients that carry mutations in the PCSK genes. Recent developments in genome-wide methodology have generated a large amount of novel information on the genetics of the first seven proprotein convertases. In this review we summarize the reported genetic alterations and their associated phenotypes.
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Affiliation(s)
- Hannu Turpeinen
- Immunoregulation, Institute of Biomedical Technology, University of Tampere, and BioMediTech, Tampere, Finland
| | - Zsuzsanna Ortutay
- Immunoregulation, Institute of Biomedical Technology, University of Tampere, and BioMediTech, Tampere, Finland
| | - Marko Pesu
- Immunoregulation, Institute of Biomedical Technology, University of Tampere, and BioMediTech, Tampere, Finland; ; Fimlab laboratories, Pirkanmaa Hospital District, Finland
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Turpeinen H, Oksanen A, Kivinen V, Kukkurainen S, Uusimäki A, Rämet M, Parikka M, Hytönen VP, Nykter M, Pesu M. Proprotein convertase subtilisin/kexin type 7 (PCSK7) is essential for the zebrafish development and bioavailability of transforming growth factor β1a (TGFβ1a). J Biol Chem 2013; 288:36610-23. [PMID: 24178295 DOI: 10.1074/jbc.m113.453183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proprotein convertase subtilisin/kexin (PCSK) enzymes convert proproteins into bioactive end products. Although other PCSK enzymes are known to be essential for biological processes ranging from cholesterol metabolism to host defense, the in vivo importance of the evolutionarily ancient PCSK7 has remained enigmatic. Here, we quantified the expressions of all pcsk genes during the 1st week of fish development and in several tissues. pcsk7 expression was ubiquitous and evident already during the early development. To compare mammalian and zebrafish PCSK7, we prepared homology models, which demonstrated remarkable structural conservation. When the PCSK7 function in developing larvae was inhibited, we found that PCSK7-deficient fish have defects in various organs, including the brain, eye, and otic vesicle, and these result in mortality within 7 days postfertilization. A genome-wide analysis of PCSK7-dependent gene expression showed that, in addition to developmental processes, several immune system-related pathways are also regulated by PCSK7. Specifically, the PCSK7 contributed to the mRNA expression and proteolytic cleavage of the cytokine TGFβ1a. Consequently, tgfβ1a morphant fish displayed phenotypical similarities with pcsk7 morphants, underscoring the importance of this cytokine in the zebrafish development. Targeting PCSK activity has emerged as a strategy for treating human diseases. Our results suggest that inhibiting PCSK7 might interfere with normal vertebrate development.
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Disruption of the expression of the proprotein convertase PC7 reduces BDNF production and affects learning and memory in mice. Proc Natl Acad Sci U S A 2013; 110:17362-7. [PMID: 24101515 DOI: 10.1073/pnas.1314698110] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PC7 belongs to the proprotein convertase family, whose members are implicated in the cleavage of secretory precursors. The in vivo function of PC7 is unknown. Herein, we find that the precursor proBDNF is processed into mature BDNF in COS-1 cells coexpressing proBDNF with either PC7 or Furin. Conversely, the processing of proBDNF into BDNF is markedly reduced in the absence of either Furin or PC7 in mouse primary hepatocytes. In vivo we observe that BDNF and PC7 mRNAs are colocalized in mouse hippocampus and amygdala and that mature BDNF protein levels are reduced in these brain areas in PC7 KO mice but not in the hippocampus of PC1/3 KO mice. Various behavioral tests reveal that in PC7 KO mice spatial memory is intact and plasticity of responding is mildly abnormal. Episodic and emotional memories are severely impaired, but both are rescued with the tyrosine receptor kinase B agonist 7,8-dihydroxyflavone. Altogether, these results support an in vivo role for PC7 in the regulation of certain types of cognitive performance, in part via proBDNF processing. Because polymorphic variants of human PC7 are being characterized, it will be important in future studies to determine their effects on additional physiological and behavioral processes.
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Potential use of potassium efflux-deficient yeast for studying trafficking signals and potassium channel functions. FEBS Open Bio 2013; 3:196-203. [PMID: 23772394 PMCID: PMC3668539 DOI: 10.1016/j.fob.2013.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/02/2013] [Accepted: 04/11/2013] [Indexed: 11/22/2022] Open
Abstract
The activity of potassium (K(+)) channels critically depends on their density on the cell surface membrane, which is regulated by dynamic protein-protein interactions that often involve distinct trafficking signals on the cargo proteins. In this paper we explored the possibility of utilizing the Saccharomyces cerevisiae strain B31 for identification of the signal motifs that regulate surface expression of membrane proteins and for studying structure-function relationships of K(+) channels. B31 cells lack the K(+) efflux system and were reported to show overloaded K(+)-mediated growth inhibition in high K(+) media upon heterologous expression of a mammalian inwardly rectifying K(+) channel (Kir2.1). We show that while the expression of wild-type Kir2.1 channel inhibits the growth of B31 cells in high K(+) media, the human disease-causing mutations of Kir2.1 that abolish K(+) conduction (V302M) or surface trafficking (Δ314/315) fully restores the growth. The expression of two-pore-domain K(+) channel KCNK3 or KCNK9 also inhibited the growth of B31 in high K(+) media while C-terminal mutations that reduce their 14-3-3 protein-dependent cell surface trafficking restored the growth of B31. Finally, the expression of Kir2.1 channels that were C-terminally fused with known sequence motifs including ER retention/retrieval signals and an endocytosis signal allowed the growth of B31 in high K(+) media. These results demonstrate the potential of B31 yeast strain as a unique biological tool to screen the random peptide libraries for novel sequence signals that down-regulate surface expression of membrane proteins, as well as to systematically identify the structural determinants for cell surface trafficking and/or ion conductance of K(+) channels.
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Guillemot J, Canuel M, Essalmani R, Prat A, Seidah NG. Implication of the proprotein convertases in iron homeostasis: proprotein convertase 7 sheds human transferrin receptor 1 and furin activates hepcidin. Hepatology 2013; 57:2514-24. [PMID: 23390091 DOI: 10.1002/hep.26297] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/15/2013] [Indexed: 02/01/2023]
Abstract
UNLABELLED The first seven members of the proprotein convertase (PC) family activate protein precursors by cleavage after basic residues. While PC7 has no known specific substrates, it shows redundancy with other PCs. A genome-wide association study suggested that circulating levels of shed human transferrin receptor 1 (hTfR1) are regulated by PC7. We thus examined whether hTfR1 constitutes a specific substrate for PC7. Coexpression of hTfR1 with PCs in several cell lines indicated that PC7 is the only convertase that sheds this receptor into the medium. Site-directed mutagenesis showed that cleavage occurs at the unusual site KTECER100 ↓LA, in which the P1 Arg100 and P6 Lys95 are critical. Pharmacological treatments revealed that shedding of hTfR1 by PC7 requires endocytosis into acidic clathrin-coated vesicles. A PC7 chimera, in which the transmembrane domain and the cytosolic tail of PC7 were replaced by that of the convertase furin, lost its ability to cleave the receptor, demonstrating the importance of these domains in the regulation of PC7 function. Analysis of primary hepatocytes from mice lacking furin, PC5, PACE4, or PC7 revealed that hepcidin, which limits iron availability in the circulation, is specifically generated by furin and not by PC7. Finally, depletion of iron in the medium of hepatoma cell lines incubated with the iron chelator desferrioxamine resulted in PC7 down-regulation. CONCLUSION Among the PC family members, only furin activates hepcidin in hepatocytes, and uniquely the full-length membrane-bound PC7 can directly shed hTfR1 by cleavage at Arg100 ↓. Our results support the notion that, when iron is limiting, hTfR1 levels increase at least in part by way of the down-regulation of PC7 expression. (HEPATOLOGY 2013;).
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Affiliation(s)
- Johann Guillemot
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
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High-affinity Dkk1 receptor Kremen1 is internalized by clathrin-mediated endocytosis. PLoS One 2012; 7:e52190. [PMID: 23251700 PMCID: PMC3522622 DOI: 10.1371/journal.pone.0052190] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 11/15/2012] [Indexed: 12/16/2022] Open
Abstract
Kremens are high-affinity receptors for Dickkopf 1 (Dkk1) and regulate the Wnt/β-catenin signaling pathway by down-regulating the low-density lipoprotein receptor-related protein 6 (LRP6). Dkk1 competes with Wnt for binding to LRP6; binding of Dkk1 inhibits canonical signaling through formation of a ternary complex with Kremen. The majority of down-regulated clathrin-mediated endocytic receptors contain short conserved regions that recognize tyrosine or dileucine sorting motifs. In this study, we found that Kremen1 is internalized from the cell surface in a clathrin-dependent manner. Kremen1 contains an atypical dileucine motif with the sequence DXXXLV. Mutation of LV to AA in this motif blocked Kremen1 internalization; as reported previously for other proteins, the aspartic acid residue in Kremen1 is not critical. Inhibition of expression of the adaptor protein 2 (AP-2) or inhibition of clathrin by pitstop 2 also blocked Kremen1 internalization. The novel amino acid sequence identified in Kremen1 is similar to the motif previously identified in hydra, yeast, and other organisms known to signal from the trans-Golgi network to the endosomal compartment.
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Seidah NG, Prat A. The biology and therapeutic targeting of the proprotein convertases. Nat Rev Drug Discov 2012; 11:367-83. [PMID: 22679642 DOI: 10.1038/nrd3699] [Citation(s) in RCA: 588] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The mammalian proprotein convertases constitute a family of nine secretory serine proteases that are related to bacterial subtilisin and yeast kexin. Seven of these (proprotein convertase 1 (PC1), PC2, furin, PC4, PC5, paired basic amino acid cleaving enzyme 4 (PACE4) and PC7) activate cellular and pathogenic precursor proteins by cleavage at single or paired basic residues, whereas subtilisin kexin isozyme 1 (SKI-1) and proprotein convertase subtilisin kexin 9 (PCSK9) regulate cholesterol and/or lipid homeostasis via cleavage at non-basic residues or through induced degradation of receptors. Proprotein convertases are now considered to be attractive targets for the development of powerful novel therapeutics. In this Review, we summarize the physiological functions and pathological implications of the proprotein convertases, and discuss proposed strategies to control some of their activities, including their therapeutic application and validation in selected disease states.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (affiliated to University of Montreal), 110 Pine Ave West, Montreal, Quebec H2W 1R7, Canada.
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