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Sachan V, Le Dévéhat M, Roubtsova A, Essalmani R, Laurendeau JF, Garçon D, Susan-Resiga D, Duval S, Mikaeeli S, Hamelin J, Evagelidis A, Chong M, Paré G, Chernetsova E, Gao ZH, Robillard I, Ruiz M, Trinh VQH, Estall JL, Faraj M, Austin RC, Sauvageau M, Prat A, Kiss RS, Seidah NG. PCSK7: A novel regulator of apolipoprotein B and a potential target against non-alcoholic fatty liver disease. Metabolism 2024; 150:155736. [PMID: 37967646 DOI: 10.1016/j.metabol.2023.155736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 10/17/2023] [Accepted: 11/08/2023] [Indexed: 11/17/2023]
Abstract
BACKGROUND Epidemiological evidence links the proprotein convertase subtilisin/kexin 7 (PCSK7) to triglyceride (TG) metabolism. We associated the known PCSK7 gain-of-function non-coding SNP rs236918 with higher levels of plasma apolipoprotein B (apoB) and the loss-of-function coding variant p.Pro777Leu (SNP rs201598301) with lower apoB and TG. Herein, we aimed to unravel the in vivo role of liver PCSK7. METHODS We biochemically defined the functional role of PCSK7 in lipid metabolism using hepatic cell lines and Pcsk7-/- mice. Our findings were validated following subcutaneous administration of hepatocyte-targeted N-acetylgalactosamine (GalNAc)-antisense oligonucleotides (ASOs) against Pcsk7. RESULTS Independent of its proteolytic activity, membrane-bound PCSK7 binds apoB100 in the endoplasmic reticulum and enhances its secretion. Mechanistically, the loss of PCSK7/Pcsk7 leads to apoB100 degradation, triggering an unfolded protein response, autophagy, and β-oxidation, eventually reducing lipid accumulation in hepatocytes. Non-alcoholic fatty liver disease (NAFLD) was induced by a 12-week high fat/fructose/cholesterol diet in wild type (WT) and Pcsk7-/- mice that were then allowed to recover on a 4-week control diet. Pcsk7-/- mice recovered more effectively than WT mice from all NAFLD-related liver phenotypes. Finally, subcutaneous administration of GalNAc-ASOs targeting hepatic Pcsk7 to WT mice validated the above results. CONCLUSIONS Our data reveal hepatic PCSK7 as one of the major regulators of apoB, and its absence reduces apoB secretion from hepatocytes favoring its ubiquitination and degradation by the proteasome. This results in a cascade of events, eventually reducing hepatic lipid accumulation, thus supporting the notion of silencing PCSK7 mRNA in hepatocytes for targeting NAFLD.
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Affiliation(s)
- Vatsal Sachan
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Maïlys Le Dévéhat
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Anna Roubtsova
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Rachid Essalmani
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Jean-Francois Laurendeau
- RNA and Noncoding Mechanisms of Disease, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Damien Garçon
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Delia Susan-Resiga
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Stéphanie Duval
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Sahar Mikaeeli
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Josée Hamelin
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Alexandra Evagelidis
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Michael Chong
- Department of Biochemistry & Biomedical Sciences, McMaster University Faculty of Health Sciences, Hamilton, Ontario, Canada
| | - Guillaume Paré
- Department of Biochemistry & Biomedical Sciences, McMaster University Faculty of Health Sciences, Hamilton, Ontario, Canada
| | | | - Zu-Hua Gao
- Department of Pathology, McGill University Health Centre, Montréal, QC, Canada
| | - Isabelle Robillard
- Montreal Heart Institute, Metabolomics Platform, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montréal, QC, Canada
| | - Matthieu Ruiz
- Montreal Heart Institute, Metabolomics Platform, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montréal, QC, Canada
| | - Vincent Quoc-Huy Trinh
- Departement of Pathology and Cellular Biology, Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montréal, QC, Canada
| | - Jennifer L Estall
- Molecular Mechanisms of Diabetes, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - May Faraj
- Nutrition Department, Université de Montréal, Research Unit on Nutrition, Lipoproteins and Cardiometabolic Diseases, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Richard C Austin
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe's Hamilton and the Hamilton Center for Kidney Research, Hamilton, ON, Canada
| | - Martin Sauvageau
- RNA and Noncoding Mechanisms of Disease, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Annik Prat
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada
| | - Robert S Kiss
- McGill University Health Centre Research Institute, Montréal, QC, Canada
| | - Nabil G Seidah
- Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (IRCM), affiliated to the Université de Montréal, Montréal, QC, Canada.
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Essalmani R, Andréo U, Evagelidis A, Le Dévéhat M, Pereira Ramos OH, Fruchart Gaillard C, Susan-Resiga D, Cohen ÉA, Seidah NG. SKI-1/S1P Facilitates SARS-CoV-2 Spike Induced Cell-to-Cell Fusion via Activation of SREBP-2 and Metalloproteases, Whereas PCSK9 Enhances the Degradation of ACE2. Viruses 2023; 15:v15020360. [PMID: 36851576 PMCID: PMC9959508 DOI: 10.3390/v15020360] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Proprotein convertases activate various envelope glycoproteins and participate in cellular entry of many viruses. We recently showed that the convertase furin is critical for the infectivity of SARS-CoV-2, which requires cleavage of its spike protein (S) at two sites: S1/S2 and S2'. This study investigates the implication of the two cholesterol-regulating convertases SKI-1 and PCSK9 in SARS-CoV-2 entry. The assays used were cell-to-cell fusion in HeLa cells and pseudoparticle entry into Calu-3 cells. SKI-1 increased cell-to-cell fusion by enhancing the activation of SREBP-2, whereas PCSK9 reduced cell-to-cell fusion by promoting the cellular degradation of ACE2. SKI-1 activity led to enhanced S2' formation, which was attributed to increased metalloprotease activity as a response to enhanced cholesterol levels via activated SREBP-2. However, high metalloprotease activity resulted in the shedding of S2' into a new C-terminal fragment (S2″), leading to reduced cell-to-cell fusion. Indeed, S-mutants that increase S2″ formation abolished S2' and cell-to-cell fusion, as well as pseudoparticle entry, indicating that the formation of S2″ prevents SARS-CoV-2 cell-to-cell fusion and entry. We next demonstrated that PCSK9 enhanced the cellular degradation of ACE2, thereby reducing cell-to-cell fusion. However, different from the LDLR, a canonical target of PCSK9, the C-terminal CHRD domain of PCSK9 is dispensable for the PCSK9-induced degradation of ACE2. Molecular modeling suggested the binding of ACE2 to the Pro/Catalytic domains of mature PCSK9. Thus, both cholesterol-regulating convertases SKI-1 and PCSK9 can modulate SARS-CoV-2 entry via two independent mechanisms.
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Affiliation(s)
- Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Université de Montréal, Montreal, QC H2W 1R7, Canada
| | - Ursula Andréo
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Université de Montréal, Montreal, QC H2W 1R7, Canada
| | - Alexandra Evagelidis
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Université de Montréal, Montreal, QC H2W 1R7, Canada
| | - Maïlys Le Dévéhat
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Université de Montréal, Montreal, QC H2W 1R7, Canada
| | - Oscar Henrique Pereira Ramos
- Département Médicaments et Technologies pour la Santé (DMTS), Université Paris-Saclay, CEA, INRAE, SI-MoS, 91191 Gif-sur-Yvette, France
| | - Carole Fruchart Gaillard
- Département Médicaments et Technologies pour la Santé (DMTS), Université Paris-Saclay, CEA, INRAE, SI-MoS, 91191 Gif-sur-Yvette, France
| | - Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Université de Montréal, Montreal, QC H2W 1R7, Canada
| | - Éric A. Cohen
- Laboratory of Human Retrovirology, Montreal Clinical Research Institute (IRCM), Université de Montréal, 110 Pine Ave West, Montreal, QC H2W 1R7, Canada
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC H3C 3J7, Canada
| | - Nabil G. Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Université de Montréal, Montreal, QC H2W 1R7, Canada
- Correspondence: ; Tel.: +1-514-987-5609
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Susan-Resiga D, Girard E, Essalmani R, Roubtsova A, Marcinkiewicz J, Derbali RM, Evagelidis A, Byun JH, Lebeau PF, Austin RC, Seidah NG. Asialoglycoprotein receptor 1 is a novel PCSK9-independent ligand of liver LDLR cleaved by furin. J Biol Chem 2021; 297:101177. [PMID: 34508778 PMCID: PMC8479480 DOI: 10.1016/j.jbc.2021.101177] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/26/2021] [Accepted: 09/07/2021] [Indexed: 01/06/2023] Open
Abstract
The hepatic carbohydrate-recognizing asialoglycoprotein receptor (ASGR1) mediates the endocytosis/lysosomal degradation of desialylated glycoproteins following binding to terminal galactose/N-acetylgalactosamine. Human heterozygote carriers of ASGR1 deletions exhibit ∼34% lower risk of coronary artery disease and ∼10% to 14% reduction of non-HDL cholesterol. Since the proprotein convertase PCSK9 is a major degrader of the low-density lipoprotein receptor (LDLR), we investigated the degradation and functionality of LDLR and/or PCSK9 by endogenous/overexpressed ASGR1 using Western blot and immunofluorescence in HepG2-naïve and HepG2-PCSK9-knockout cells. ASGR1, like PCSK9, targets LDLR, and both independently interact with/enhance the degradation of the receptor. This lack of cooperativity between PCSK9 and ASGR1 was confirmed in livers of wildtype (WT) and Pcsk9−/− mice. ASGR1 knockdown in HepG2-naïve cells significantly increased total (∼1.2-fold) and cell-surface (∼4-fold) LDLR protein. In HepG2-PCSK9-knockout cells, ASGR1 silencing led to ∼2-fold higher levels of LDLR protein and DiI (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate)-LDL uptake associated with ∼9-fold increased cell-surface LDLR. Overexpression of WT-ASGR1/2 primarily reduced levels of immature non-O-glycosylated LDLR (∼110 kDa), whereas the triple Ala-mutant of Gln240/Trp244/Glu253 (characterized by loss of carbohydrate binding) reduced expression of the mature form of LDLR (∼150 kDa), suggesting that ASGR1 binds the LDLR in both a sugar-dependent and -independent fashion. The protease furin cleaves ASGR1 at the RKMK103↓ motif into a secreted form, likely resulting in a loss of function on LDLR. Altogether, we demonstrate that LDLR is the first example of a liver-receptor ligand of ASGR1. We conclude that silencing of ASGR1 and PCSK9 may lead to higher LDL uptake by hepatocytes, thereby providing a novel approach to further reduce LDL cholesterol levels.
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Affiliation(s)
- Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Emmanuelle Girard
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Anna Roubtsova
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Jadwiga Marcinkiewicz
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Rabeb M Derbali
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Alexandra Evagelidis
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada
| | - Jae H Byun
- Division of Nephrology, Department of Medicine, McMaster University, St. Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada
| | - Paul F Lebeau
- Division of Nephrology, Department of Medicine, McMaster University, St. Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada
| | - Richard C Austin
- Division of Nephrology, Department of Medicine, McMaster University, St. Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM), Affiliated to the University of Montreal, Montreal, Quebec, Canada.
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Al Rifai O, Susan-Resiga D, Essalmani R, Creemers JWM, Seidah NG, Ferron M. In Vivo Analysis of the Contribution of Proprotein Convertases to the Processing of FGF23. Front Endocrinol (Lausanne) 2021; 12:690681. [PMID: 34149625 PMCID: PMC8213403 DOI: 10.3389/fendo.2021.690681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Accepted: 05/13/2021] [Indexed: 12/25/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) is a hormone secreted from fully differentiated osteoblasts and osteocytes that inhibits phosphate reabsorption by kidney proximal tubules. The full-length (i.e., intact) protein mediates FGF23 endocrine functions, while endoproteolytic cleavage at a consensus cleavage sequence for the proprotein convertases (PCs) inactivates FGF23. Two PCs, furin and PC5, were shown to cleave FGF23 in vitro at RHTR179↓, but whether they are fulfilling this function in vivo is currently unknown. To address this question, we used here mice lacking either or both furin and PC5 in cell-specific manners and mice lacking the paired basic amino acid-cleaving enzyme 4 (PACE4) in all cells. Our analysis shows that furin inactivation in osteoblasts and osteocytes results in a 25% increase in circulating intact FGF23, without any significant impact on serum phosphate levels, whether mice are maintained on a normal or a low phosphate diet. Under conditions of iron deficiency, FGF23 is normally processed in control mice, but its processing is impaired in mice lacking furin in osteoblasts and osteocytes. In contrast, FGF23 is normally cleaved following erythropoietin or IL-1β injections in mice lacking furin or both furin and PC5, and in PACE4-deficient mice. Altogether, these studies suggest that furin is only partially responsible for FGF23 cleavage under certain conditions in vivo. The processing of FGF23 may therefore involve the redundant action of multiple PCs or of other peptidases in osteoblasts, osteocytes and hematopoietic cells.
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Affiliation(s)
- Omar Al Rifai
- Unité de recherche en physiologie moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Programme de biologie moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Delia Susan-Resiga
- Unité de recherche en biochimie neuroendocrinienne, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
| | - Rachid Essalmani
- Unité de recherche en biochimie neuroendocrinienne, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
| | - John W. M. Creemers
- Department of Human Genetics, Katholieke Universiteit (KU) Leuven, Leuven, Belgium
| | - Nabil G. Seidah
- Unité de recherche en biochimie neuroendocrinienne, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
| | - Mathieu Ferron
- Unité de recherche en physiologie moléculaire, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Programme de biologie moléculaire, Université de Montréal, Montréal, QC, Canada
- Département de Médecine, Université de Montréal, Montréal, QC, Canada
- Division of Experimental Medicine, McGill University, Montréal, QC, Canada
- *Correspondence: Mathieu Ferron,
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Ashraf Y, Duval S, Sachan V, Essalmani R, Susan-Resiga D, Roubtsova A, Hamelin J, Gerhardy S, Kirchhofer D, Tagliabracci VS, Prat A, Kiss RS, Seidah NG. Proprotein convertase 7 (PCSK7) reduces apoA-V levels. FEBS J 2020; 287:3565-3578. [PMID: 31945259 DOI: 10.1111/febs.15212] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/07/2019] [Accepted: 01/10/2020] [Indexed: 01/24/2023]
Abstract
The locus of the human proprotein convertase subtilisin-kexin type-7 (PC7) gene (PCSK7) is on chromosome 11q23.3 close to the gene cluster APOA5/APOA4/APOC3/APOA1, a region implicated in the regulation of lipoprotein metabolism. A GWAS reported the association of PCSK7 SNPs with plasma triglyceride (TG), and exome sequencing of African Americans revealed the association of a low-frequency coding variant of PC7 (R504H; SNP rs142953140) with a ~ 30% TG reduction. Another PCSK7 SNP rs508487 is in linkage disequilibrium with a promoter variant of the liver-derived apolipoprotein A-V (apoA-V), an indirect activator of the lipoprotein lipase (LpL), and is associated with elevated TG levels. We thus hypothesized that PC7 regulates the levels/activity of apoA-V. Studies in the human hepatic cell line HuH7 revealed that wild-type (WT) PC7 and its endoplasmic reticulum (ER)-retained forms bind to and enhance the degradation of human apoA-V in acidic lysosomes in a nonenzymatic fashion. PC7-induced degradation of apoA-V is inhibited by bafilomycin A1 and the alkalinizing agents: chloroquine and NH4 Cl. Thus, the PC7-induced apoA-V degradation implicates an ER-lysosomal communication inhibited by bafilomycin A1. In vitro, the natural R504H mutant enhances PC7 Ser505 phosphorylation at the structurally exposed Ser-X-Glu507 motif recognized by the secretory kinase Fam20C. Co-expression of the phosphomimetic PC7-S505E with apoA-V resulted in lower degradation compared to WT, suggesting that Ser505 phosphorylation of PC7 lowers TG levels via reduced apoA-V degradation. In agreement, in Pcsk7-/- mice fed high-fat diet, plasma apoA-V levels and adipocyte LpL activity are increased, providing an in vivo mechanistic link for a role of liver PC7 in enhanced TG storage in adipocytes.
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Affiliation(s)
- Yahya Ashraf
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Stéphanie Duval
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Vatsal Sachan
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Anna Roubtsova
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Josée Hamelin
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Stefan Gerhardy
- Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA
| | - Daniel Kirchhofer
- Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
| | - Robert Scott Kiss
- Research Institute, McGill University Health Center, Montreal, QC, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, QC, Canada
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Ibrahim NS, Lazaris A, Rada M, Petrillo SK, Huck L, Hussain S, Ouladan S, Gao ZH, Gregorieff A, Essalmani R, Seidah NG, Metrakos P. Angiopoietin1 Deficiency in Hepatocytes Affects the Growth of Colorectal Cancer Liver Metastases (CRCLM). Cancers (Basel) 2019; 12:cancers12010035. [PMID: 31877668 PMCID: PMC7016878 DOI: 10.3390/cancers12010035] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/12/2019] [Accepted: 12/19/2019] [Indexed: 01/02/2023] Open
Abstract
Colorectal cancer liver metastases (CRCLM) that receive their blood supply via vessel co-option are associated with a poor response to anti-angiogenic therapy. Angiopoietins (Ang1 and Ang2) with their Tyrosine-protein kinase receptor (Tie2) have been shown to support vessel co-option. We demonstrate significantly higher expression of Ang1 in hepatocytes adjacent to the tumor region of human chemonaïve and treated co-opting (replacement histopathological growth patterns: RHGP) tumors. To investigate the role of the host Ang1 expression, Ang1 knockout (KO) mice were injected intra-splenically with metastatic MC-38 colon cancer cells that develop co-opting liver metastases. We observed a reduction in the number of liver metastases and interestingly, for the first time, the development of angiogenic driven desmoplastic (DHGP) liver metastases. In addition, in-vitro, knockout of Ang1 in primary hepatocytes inhibited viability, migration and invasion ability of MC-38 cells. We also demonstrate that Ang 1 alone promotes the migration and growth of both human and mouse colon cancer cell lines These results provide evidence that high expression of Ang1 in the host liver is important to support vessel co-option (RHGP lesions) and when inhibited, favours the formation of angiogenic driven liver metastases (DHGP lesions).
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Affiliation(s)
- Nisreen S. Ibrahim
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0G4, Canada; (N.S.I.); (M.R.)
| | - Anthoula Lazaris
- Department of Surgery, McGill University Health Center Research Institute, Cancer Program, Montreal, QC H4A 3J1, Canada; (A.L.); (S.K.P.)
| | - Miran Rada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0G4, Canada; (N.S.I.); (M.R.)
| | - Stephanie K. Petrillo
- Department of Surgery, McGill University Health Center Research Institute, Cancer Program, Montreal, QC H4A 3J1, Canada; (A.L.); (S.K.P.)
| | - Laurent Huck
- Departments of Critical Care and Medicine, McGill University Health Centre and Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, QC 4A 3J1, Canada; (L.H.); (S.H.)
| | - Sabah Hussain
- Departments of Critical Care and Medicine, McGill University Health Centre and Meakins-Christie Laboratories, Department of Medicine, McGill University, Montreal, QC 4A 3J1, Canada; (L.H.); (S.H.)
| | - Shaida Ouladan
- Department of Pathology, McGill University Health Center, Montreal, QC H4A 3J1, Canada; (S.O.); (Z.-H.G.); (A.G.)
| | - Zu-Hua Gao
- Department of Pathology, McGill University Health Center, Montreal, QC H4A 3J1, Canada; (S.O.); (Z.-H.G.); (A.G.)
| | - Alexander Gregorieff
- Department of Pathology, McGill University Health Center, Montreal, QC H4A 3J1, Canada; (S.O.); (Z.-H.G.); (A.G.)
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, University of Montreal, Montreal, QC H3T 1J4, Canada; (R.E.); (N.G.S.)
| | - Nabil G. Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, University of Montreal, Montreal, QC H3T 1J4, Canada; (R.E.); (N.G.S.)
| | - Peter Metrakos
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0G4, Canada; (N.S.I.); (M.R.)
- Department of Surgery, McGill University Health Center Research Institute, Cancer Program, Montreal, QC H4A 3J1, Canada; (A.L.); (S.K.P.)
- Department of Pathology, McGill University Health Center, Montreal, QC H4A 3J1, Canada; (S.O.); (Z.-H.G.); (A.G.)
- Correspondence:
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Ben Djoudi Ouadda A, Gauthier MS, Susan-Resiga D, Girard E, Essalmani R, Black M, Marcinkiewicz J, Forget D, Hamelin J, Evagelidis A, Ly K, Day R, Galarneau L, Corbin F, Coulombe B, Çaku A, Tagliabracci VS, Seidah NG. Ser-Phosphorylation of PCSK9 (Proprotein Convertase Subtilisin-Kexin 9) by Fam20C (Family With Sequence Similarity 20, Member C) Kinase Enhances Its Ability to Degrade the LDLR (Low-Density Lipoprotein Receptor). Arterioscler Thromb Vasc Biol 2019; 39:1996-2013. [PMID: 31553664 DOI: 10.1161/atvbaha.119.313247] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE PCSK9 (proprotein convertase subtilisin-kexin 9) enhances the degradation of the LDLR (low-density lipoprotein receptor) in endosomes/lysosomes. This study aimed to determine the sites of PCSK9 phosphorylation at Ser-residues and the consequences of such posttranslational modification on the secretion and activity of PCSK9 on the LDLR. Approach and Results: Fam20C (family with sequence similarity 20, member C) phosphorylates serines in secretory proteins containing the motif S-X-E/phospho-Ser, including the cholesterol-regulating PCSK9. In situ hybridization of Fam20C mRNA during development and in adult mice revealed a wide tissue distribution, including liver, but not small intestine. Here, we show that Fam20C phosphorylates PCSK9 at Serines 47, 666, 668, and 688. In hepatocytes, phosphorylation enhances PCSK9 secretion and maximizes its induced degradation of the LDLR via the extracellular and intracellular pathways. Replacing any of the 4 Ser by the phosphomimetic Glu or Asp enhanced PCSK9 activity only when the other sites are phosphorylated, whereas Ala substitutions reduced it, as evidenced by Western blotting, Elisa, and LDLR-immunolabeling. This newly uncovered PCSK9/LDLR regulation mechanism refines our understanding of the implication of global PCSK9 phosphorylation in the modulation of LDL-cholesterol and rationalizes the consequence of natural mutations, for example, S668R and E670G. Finally, the relationship of Ser-phosphorylation to the implication of PCSK9 in regulating LDL-cholesterol in the neurological Fragile X-syndrome disorder was investigated. CONCLUSIONS Ser-phosphorylation of PCSK9 maximizes both its secretion and activity on the LDLR. Mass spectrometric approaches to measure such modifications were developed and applied to quantify the levels of bioactive PCSK9 in human plasma under normal and pathological conditions.
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Affiliation(s)
- Ali Ben Djoudi Ouadda
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Marie-Soleil Gauthier
- Translational Proteomics Research Unit, Clinical Research Institute of Montreal (IRCM, affiliated to the Université de Montréal), QC, Canada (M.-S.G., D.F., B.C.)
| | - Delia Susan-Resiga
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Emmanuelle Girard
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Rachid Essalmani
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Miles Black
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas (M.B., V.S.T.)
| | - Jadwiga Marcinkiewicz
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Diane Forget
- Translational Proteomics Research Unit, Clinical Research Institute of Montreal (IRCM, affiliated to the Université de Montréal), QC, Canada (M.-S.G., D.F., B.C.)
| | - Josée Hamelin
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Alexandra Evagelidis
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
| | - Kevin Ly
- Institut de Pharmacologie, Université de Sherbrooke, QC, Canada (K.L., R.D.)
| | - Robert Day
- Institut de Pharmacologie, Université de Sherbrooke, QC, Canada (K.L., R.D.)
| | - Luc Galarneau
- Department of Biochemistry, Université de Sherbrooke, and Centre de Recherche du CHUS, QC, Canada (L.G., F.C., A.Ç.)
| | - Francois Corbin
- Department of Biochemistry, Université de Sherbrooke, and Centre de Recherche du CHUS, QC, Canada (L.G., F.C., A.Ç.)
| | - Benoit Coulombe
- Translational Proteomics Research Unit, Clinical Research Institute of Montreal (IRCM, affiliated to the Université de Montréal), QC, Canada (M.-S.G., D.F., B.C.)
| | - Artuela Çaku
- Department of Biochemistry, Université de Sherbrooke, and Centre de Recherche du CHUS, QC, Canada (L.G., F.C., A.Ç.)
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas (M.B., V.S.T.)
| | - Nabil G Seidah
- From the Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM; affiliated to the Université de Montréal), QC, Canada (A.B.D.O., D.S.-R., E.G., R.E., J.M., J.H., A.E., N.G.S.)
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8
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Essalmani R, Weider E, Marcinkiewicz J, Chamberland A, Susan-Resiga D, Roubtsova A, Seidah NG, Prat A. A single domain antibody against the Cys- and His-rich domain of PCSK9 and evolocumab exhibit different inhibition mechanisms in humanized PCSK9 mice. Biol Chem 2019; 399:1363-1374. [PMID: 30044755 DOI: 10.1515/hsz-2018-0194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 07/09/2018] [Indexed: 11/15/2022]
Abstract
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that binds and escorts the low density lipoprotein receptor (LDLR) into the lysosomal degradation pathway. Prescribed monoclonal antibodies (mAbs) against PCSK9 prevent its binding to the LDLR, and result in ~60% lower LDL cholesterol (LDLc) levels. Although efficient, mAbs are expensive. Hence other PCSK9 inhibitors are needed. For screening purpose, we developed C57BL/6J mice expressing the human PCSK9 gene under the control of its own promoter, but lacking endogenous mouse PCSK9. All lines recapitulate the endogenous PCSK9 expression pattern. The Tg2 line that expresses physiological levels of human PCSK9 (hPCSK9) was selected to characterize the inhibitory properties of a previously reported single domain antibody (sdAb), PKF8-mFc, which binds the C-terminal domain of PCSK9. Upon intraveinous injection of 10 mg/kg, PKF8-mFc and the mAb evolocumab neutralized ~50% and 100% of the hPCSK9 impact on total cholesterol (TC) levels, respectively, but PKF8-mFc had a more sustained effect. PKF8-mFc barely affected hPCSK9 levels, whereas evolocumab promoted a 4-fold increase 3 days post-injection, suggesting very different inhibitory mechanisms. The present study also shows that the new transgenic mice are well suited to screen a variety of hPCSK9 inhibitors.
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Affiliation(s)
- Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Elodie Weider
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Jadwiga Marcinkiewicz
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Ann Chamberland
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Anna Roubtsova
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, Affiliated to the Université de Montréal, 110 Pine Ave. West, Montreal H2W 1R7, QC, Canada
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9
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Ashraf Y, Sachan V, Essalmani R, Duval S, Marcinkiewicz J, Hamelin J, Roubtsova A, Prat A, Seidah NG. The Proprotein Convertase 7 Regulates Triglyceride Levels via Enhanced ApoA5 Degradation. ATHEROSCLEROSIS SUPP 2018. [DOI: 10.1016/j.atherosclerosissup.2018.04.169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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10
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Hoac B, Susan-Resiga D, Essalmani R, Marcinkiweicz E, Seidah NG, McKee MD. Osteopontin as a novel substrate for the proprotein convertase 5/6 (PCSK5) in bone. Bone 2018; 107:45-55. [PMID: 29126984 DOI: 10.1016/j.bone.2017.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 11/05/2017] [Accepted: 11/06/2017] [Indexed: 12/30/2022]
Abstract
Seven proprotein convertases cleave the basic amino acid consensus sequence K/R-Xn-K/R↓ (where n=0, 2, 4 or 6 variable amino acids) to activate precursor proteins. Despite similarities in substrate specificity, basic amino acid-specific proprotein convertases have a distinct tissue distribution allowing for enzymatic actions on tissue-resident substrates. Proprotein convertase 5/6 (PC5/6) has two splice variants - soluble PC5/6A and membrane-bound PC5/6B - and is expressed during mouse development in many tissues including bone and tooth, but little is known about the substrates for PC5/6 therein. Osteopontin (OPN) is an abundant bone extracellular matrix protein with roles in mineralization, cell adhesion and cell migration, and it has putative consensus sequence sites for cleavage by PC5/6, which may modify its function in bone. Since PC5/6-knockout mouse embryos show developmental abnormalities, and reduced overall mineralization, we designed this study to determine whether OPN is a substrate of PC5/6. In silico analysis of OPN protein sequences identified four potential PC5/6 consensus cleavage sites in human OPN, and three sites - including a noncanonical sequence - in mouse OPN. Ex vivo co-transfections with human OPN revealed complete OPN cleavage reducing full-length OPN (~70kDa) to an N-terminal fragment migrating at ~50kDa and two C-terminal fragments at ~18kDa and ~16kDa. Direct cleavage of OPN by PC5/6A - the predominant isoform expressed in human osteoblast cells - was confirmed by cell-free enzyme-substrate assays and by mass spectrometry. The latter was also used to investigate potential cleavage sites. Co-transfections of PC5/6 and mouse OPN showed partial cleavage of OPN into a C-terminal OPN fragment migrating at ~30kDa and an N-terminal fragment migrating at ~29kDa. Micro-computed tomography of PC5/6-knockout embryos at E18.5 confirmed a reduction in mineralized bone, and in situ hybridization performed on cryo-sections of normal mouse bone using Pcsk5 and Opn anti-sense and control-sense cRNA probes indicated the co-localization of the expression of these genes in bone cells. This mRNA expression profile was supported by semi-quantitative RT-PCR using osteoblast primary cultures, and cultured MC3T3-E1 osteoblast and MLO-Y4 osteocyte cell lines. Immunoblotting for OPN from mouse bone extracts showed altered OPN processing in PC5/6-knockout mice compared to wildtype mice. OPN fragments migrated at ~25kDa and ~16kDa in wildtype bone and were not present in PC5/6-deficient bone. In conclusion, this study demonstrates that Pcsk5 is expressed in bone-forming cells, and that OPN is a novel substrate for PC5/6. Cleavage of OPN by PC5/6 may modify the function of OPN in bone and/or modulate other enzymatic cleavages of OPN, leading to alterations in the bone phenotype.
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Affiliation(s)
- Betty Hoac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, Affiliated with the University of Montreal, Montreal, QC, Canada
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, Affiliated with the University of Montreal, Montreal, QC, Canada
| | - Edwige Marcinkiweicz
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, Affiliated with the University of Montreal, Montreal, QC, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute, Affiliated with the University of Montreal, Montreal, QC, Canada
| | - Marc D McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada.
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11
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Al Rifai O, Chow J, Lacombe J, Julien C, Faubert D, Susan-Resiga D, Essalmani R, Creemers JW, Seidah NG, Ferron M. Proprotein convertase furin regulates osteocalcin and bone endocrine function. J Clin Invest 2017; 127:4104-4117. [PMID: 28972540 DOI: 10.1172/jci93437] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 08/15/2017] [Indexed: 12/12/2022] Open
Abstract
Osteocalcin (OCN) is an osteoblast-derived hormone that increases energy expenditure, insulin sensitivity, insulin secretion, and glucose tolerance. The cDNA sequence of OCN predicts that, like many other peptide hormones, OCN is first synthesized as a prohormone (pro-OCN). The importance of pro-OCN maturation in regulating OCN and the identity of the endopeptidase responsible for pro-OCN cleavage in osteoblasts are still unknown. Here, we show that the proprotein convertase furin is responsible for pro-OCN maturation in vitro and in vivo. Using pharmacological and genetic experiments, we also determined that furin-mediated pro-OCN cleavage occurred independently of its γ-carboxylation, a posttranslational modification that is known to hamper OCN endocrine action. However, because pro-OCN is not efficiently decarboxylated and activated during bone resorption, inactivation of furin in osteoblasts in mice resulted in decreased circulating levels of undercarboxylated OCN, impaired glucose tolerance, and reduced energy expenditure. Furthermore, we show that Furin deletion in osteoblasts reduced appetite, a function not modulated by OCN, thus suggesting that osteoblasts may secrete additional hormones that regulate different aspects of energy metabolism. Accordingly, the metabolic defects of the mice lacking furin in osteoblasts became more apparent under pair-feeding conditions. These findings identify furin as an important regulator of bone endocrine function.
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Affiliation(s)
- Omar Al Rifai
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada.,Molecular Biology Programs of the Faculty of Medicine, Université de Montréal, Québec, Canada
| | - Jacqueline Chow
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Julie Lacombe
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | - Catherine Julien
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada
| | | | | | - Rachid Essalmani
- Biochemical Neuroendocrinology Research Unit, IRCM, Québec, Canada
| | | | - Nabil G Seidah
- Biochemical Neuroendocrinology Research Unit, IRCM, Québec, Canada.,Department of Medicine, Université de Montréal, Québec, Canada.,Division of Experimental Medicine, McGill University, Montréal, Québec, Canada
| | - Mathieu Ferron
- Integrative and Molecular Physiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada.,Molecular Biology Programs of the Faculty of Medicine, Université de Montréal, Québec, Canada.,Department of Medicine, Université de Montréal, Québec, Canada.,Division of Experimental Medicine, McGill University, Montréal, Québec, Canada
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12
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Essalmani R, Susan-Resiga D, Guillemot J, Kim W, Sachan V, Awan Z, Chamberland A, Asselin MC, Ly K, Desjardins R, Day R, Prat A, Seidah NG. Thrombin activation of protein C requires prior processing by a liver proprotein convertase. J Biol Chem 2017; 292:13565. [DOI: 10.1074/jbc.a116.77040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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13
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Essalmani R, Susan-Resiga D, Guillemot J, Kim W, Sachan V, Awan Z, Chamberland A, Asselin MC, Ly K, Desjardins R, Day R, Prat A, Seidah NG. Thrombin activation of protein C requires prior processing by a liver proprotein convertase. J Biol Chem 2017; 292:10564-10573. [PMID: 28468828 DOI: 10.1074/jbc.m116.770040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 04/25/2017] [Indexed: 01/29/2023] Open
Abstract
Protein C, a secretory vitamin K-dependent anticoagulant serine protease, inactivates factors Va/VIIIa. It is exclusively synthesized in liver hepatocytes as an inactive zymogen (proprotein C). In humans, thrombin cleavage of the propeptide at PR221↓ results in activated protein C (APC; residues 222-461). However, the propeptide is also cleaved by a furin-like proprotein convertase(s) (PCs) at KKRSHLKR199↓ (underlined basic residues critical for the recognition by PCs), but the order of cleavage is unknown. Herein, we present evidence that at the surface of COS-1 cells, mouse proprotein C is first cleaved by the convertases furin, PC5/6A, and PACE4. In mice, this cleavage occurs at the equivalent site, KKRKILKR198↓, and requires the presence of Arg198 at P1 and a combination of two other basic residues at either P2 (Lys197), P6 (Arg193), or P8 (Lys191) positions. Notably, the thrombin-resistant R221A mutant is still cleaved by these PCs, revealing that convertase cleavage can precede thrombin activation. This conclusion was supported by the fact that the APC-specific activity in the medium of COS-1 cells is exclusively dependent on prior cleavage by the convertases, because both R198A and R221A lack protein C activity. Primary cultures of hepatocytes derived from wild-type or hepatocyte-specific furin, PC5/6, or complete PACE4 knock-out mice suggested that the cleavage of overexpressed proprotein C is predominantly performed by furin intracellularly and by all three proprotein convertases at the cell surface. Indeed, plasma analyses of single-proprotein convertase-knock-out mice showed that loss of the convertase furin or PC5/6 in hepatocytes results in a ∼30% decrease in APC levels, with no significant contribution from PACE4. We conclude that prior convertase cleavage of protein C in hepatocytes is critical for its thrombin activation.
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Affiliation(s)
- Rachid Essalmani
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Delia Susan-Resiga
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Johann Guillemot
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Woojin Kim
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Vatsal Sachan
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Zuhier Awan
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Ann Chamberland
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Marie-Claude Asselin
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Kévin Ly
- the Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Roxane Desjardins
- the Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Robert Day
- the Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Annik Prat
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
| | - Nabil G Seidah
- From the Laboratories of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada and
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14
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Susan-Resiga D, Girard E, Kiss RS, Essalmani R, Hamelin J, Asselin MC, Awan Z, Butkinaree C, Fleury A, Soldera A, Dory YL, Baass A, Seidah NG. The Proprotein Convertase Subtilisin/Kexin Type 9-resistant R410S Low Density Lipoprotein Receptor Mutation: A NOVEL MECHANISM CAUSING FAMILIAL HYPERCHOLESTEROLEMIA. J Biol Chem 2016; 292:1573-1590. [PMID: 27998977 DOI: 10.1074/jbc.m116.769430] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 12/20/2016] [Indexed: 12/22/2022] Open
Abstract
Familial hypercholesterolemia (FH) is characterized by severely elevated low density lipoprotein (LDL) cholesterol. Herein, we identified an FH patient presenting novel compound heterozygote mutations R410S and G592E of the LDL receptor (LDLR). The patient responded modestly to maximum rosuvastatin plus ezetimibe therapy, even in combination with a PCSK9 monoclonal antibody injection. Using cell biology and molecular dynamics simulations, we aimed to define the underlying mechanism(s) by which these LDLR mutations affect LDL metabolism and lead to hypercholesterolemia. Our data showed that the LDLR-G592E is a class 2b mutant, because it mostly failed to exit the endoplasmic reticulum and was degraded. Even though LDLR-R410S and LDLR-WT were similar in levels of cell surface and total receptor and bound equally well to LDL or extracellular PCSK9, the LDLR-R410S was resistant to exogenous PCSK9-mediated degradation in endosomes/lysosomes and showed reduced LDL internalization and degradation relative to LDLR-WT. Evidence is provided for a tighter association of LDL with LDLR-R410S at acidic pH, a reduced LDL delivery to late endosomes/lysosomes, and an increased release in the medium of the bound/internalized LDL, as compared with LDLR-WT. These data suggested that LDLR-R410S recycles loaded with its LDL-cargo. Our findings demonstrate that LDLR-R410S represents an LDLR loss-of-function through a novel class 8 FH-causing mechanism, thereby rationalizing the observed phenotype.
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Affiliation(s)
- Delia Susan-Resiga
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Emmanuelle Girard
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Robert Scott Kiss
- the Department of Medicine, McGill University, Montreal, Quebec H3G 2M1, Canada
| | - Rachid Essalmani
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Josée Hamelin
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Marie-Claude Asselin
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Zuhier Awan
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Chutikarn Butkinaree
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada
| | - Alexandre Fleury
- the Laboratory of Supramolecular Chemistry, Department of Chemistry, University of Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Armand Soldera
- the Laboratory of Supramolecular Chemistry, Department of Chemistry, University of Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Yves L Dory
- the Laboratory of Supramolecular Chemistry, Department of Chemistry, University of Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Alexis Baass
- Nutrition, Metabolism, and Atherosclerosis Clinic, Institut de Recherches Cliniques de Montréal, affiliated with University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Nabil G Seidah
- From the Laboratory of Biochemical Neuroendocrinology, Montreal, Quebec H2W 1R7, Canada.
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15
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Weider E, Susan-Resiga D, Essalmani R, Hamelin J, Asselin MC, Nimesh S, Ashraf Y, Wycoff KL, Zhang J, Prat A, Seidah NG. Proprotein convertase subtilisin/Kexin type 9 (PCSK9) single domain antibodies are potent inhibitors of low density lipoprotein receptor degradation. J Biol Chem 2016; 291:26586. [PMID: 27986868 DOI: 10.1074/jbc.a116.717736] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Ly K, Essalmani R, Desjardins R, Seidah NG, Day R. An Unbiased Mass Spectrometry Approach Identifies Glypican-3 as an Interactor of Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) and Low Density Lipoprotein Receptor (LDLR) in Hepatocellular Carcinoma Cells. J Biol Chem 2016; 291:24676-24687. [PMID: 27758865 DOI: 10.1074/jbc.m116.746883] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/07/2016] [Indexed: 12/24/2022] Open
Abstract
The mechanism of LDL receptor (LDLR) degradation mediated by the proprotein convertase subtilisin/kexin type 9 (PCSK9) has been extensively studied; however, many steps within this process remain unclear and still require characterization. Recent studies have shown that PCSK9 lacking its Cys/His-rich domain can still promote LDLR internalization, but the complex does not reach the lysosome suggesting the presence of an additional interaction partner(s). In this study we carried out an unbiased screening approach to identify PCSK9-interacting proteins in the HepG2 cells' secretome using co-immunoprecipitation combined with mass spectrometry analyses. Several interacting proteins were identified, including glypican-3 (GPC3), phospholipid transfer protein, matrilin-3, tissue factor pathway inhibitor, fibrinogen-like 1, and plasminogen activator inhibitor-1. We then validated these interactions by co-immunoprecipitation and Western blotting. Furthermore, functional validation was examined by silencing each candidate protein in HepG2 cells using short hairpin RNAs to determine their effect on LDL uptake and LDLR levels. Only GPC3 and phospholipid transfer protein silencing in HepG2 cells significantly increased LDL uptake in these cells and displayed higher total LDLR protein levels compared with control cells. Moreover, our study provides the first evidence that GPC3 can modulate the PCSK9 extracellular activity as a competitive binding partner to the LDLR in HepG2 cells.
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Affiliation(s)
- Kévin Ly
- From the Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1H5N4 and
| | - Rachid Essalmani
- the Institut de Recherches Cliniques de Montréal, Affiliated with Université de Montréal, Montréal, Quebec H2W 1R7, Canada
| | - Roxane Desjardins
- From the Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1H5N4 and
| | - Nabil G Seidah
- the Institut de Recherches Cliniques de Montréal, Affiliated with Université de Montréal, Montréal, Quebec H2W 1R7, Canada
| | - Robert Day
- From the Institut de Pharmacologie de Sherbrooke, Department of Surgery/Urology Division, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec J1H5N4 and.
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Weider E, Susan-Resiga D, Essalmani R, Hamelin J, Asselin MC, Nimesh S, Ashraf Y, Wycoff KL, Zhang J, Prat A, Seidah NG. Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Single Domain Antibodies Are Potent Inhibitors of Low Density Lipoprotein Receptor Degradation. J Biol Chem 2016; 291:16659-71. [PMID: 27284008 DOI: 10.1074/jbc.m116.717736] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 01/14/2023] Open
Abstract
Single domain antibodies (sdAbs) correspond to the antigen-binding domains of camelid antibodies. They have the same antigen-binding properties and specificity as monoclonal antibodies (mAbs) but are easier and cheaper to produce. We report here the development of sdAbs targeting human PCSK9 (proprotein convertase subtilisin/kexin type 9) as an alternative to anti-PCSK9 mAbs. After immunizing a llama with human PCSK9, we selected four sdAbs that bind PCSK9 with a high affinity and produced them as fusion proteins with a mouse Fc. All four sdAb-Fcs recognize the C-terminal Cys-His-rich domain of PCSK9. We performed multiple cellular assays and demonstrated that the selected sdAbs efficiently blocked PCSK9-mediated low density lipoprotein receptor (LDLR) degradation in cell lines, in human hepatocytes, and in mouse primary hepatocytes. We further showed that the sdAb-Fcs do not affect binding of PCSK9 to the LDLR but rather block its induced cellular LDLR degradation. Pcsk9 knock-out mice expressing a human bacterial artificial chromosome (BAC) transgene were generated, resulting in plasma levels of ∼300 ng/ml human PCSK9. Mice were singly or doubly injected with the best sdAb-Fc and analyzed at day 4 or 11, respectively. After 4 days, mice exhibited a 32 and 44% decrease in the levels of total cholesterol and apolipoprotein B and ∼1.8-fold higher liver LDLR protein levels. At 11 days, the equivalent values were 24 and 46% and ∼2.3-fold higher LDLR proteins. These data constitute a proof-of-principle for the future usage of sdAbs as PCSK9-targeting drugs that can efficiently reduce LDL-cholesterol, and as tools to study the Cys-His-rich domain-dependent sorting the PCSK9-LDLR complex to lysosomes.
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Affiliation(s)
- Elodie Weider
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Delia Susan-Resiga
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Rachid Essalmani
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Josée Hamelin
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Marie-Claude Asselin
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Surendra Nimesh
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Yahya Ashraf
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Keith L Wycoff
- Planet Biotechnology Inc., Hayward, California 94545-2740, and
| | - Jianbing Zhang
- the Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Annik Prat
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Nabil G Seidah
- From the Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal, University of Montreal, Montreal, Quebec H2W 1R7, Canada,
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Guillemot J, Asselin MC, Susan-Resiga D, Essalmani R, Seidah NG. Back cover: Deferoxamine stimulates LDLR expression and LDL uptake in HepG2 cells. Mol Nutr Food Res 2016. [DOI: 10.1002/mnfr.201670035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Guillemot J, Asselin MC, Susan-Resiga D, Essalmani R, Seidah NG. Deferoxamine stimulates LDLR expression and LDL uptake in HepG2 cells. Mol Nutr Food Res 2015; 60:600-8. [PMID: 26577249 DOI: 10.1002/mnfr.201500467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/02/2015] [Accepted: 10/26/2015] [Indexed: 12/13/2022]
Abstract
SCOPE Iron overload contributes to the pathogenesis of atherosclerosis and iron chelators are beneficial through their antioxidant properties. Hepatic iron loading increases cholesterol synthesis. Whether iron depletion could affect hepatic cholesterol metabolism is unknown. METHODS AND RESULTS We examined the effect of the iron chelator deferoxamine (DFO) on mRNA expression of genes involved in cholesterol metabolism and/or cholesterol uptake. Our results revealed that DFO increases LDL receptor (LDLR) mRNA levels in human hepatocyte-derived cell lines HepG2 and Huh7 cells, and in K562 cells. In HepG2 cells, we observed that DFO increases (i) LDLR-mRNA levels in a time- and dose-dependent manner, (ii) LDLR-protein levels; (iii) cell surface LDLR; and (iv) LDL uptake. In contrast, the mRNA levels of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, sterol regulatory element-binding proteins, and the mRNA/protein levels of proprotein convertase subtilisin-kexin 9 were not modulated by DFO, suggesting that the LDLR regulation by DFO is not at the transcriptional or posttranslational levels. Since LDLR-mRNA was stabilized by DFO, a posttranscriptional mechanism is suggested for the DFO-mediated upregulation of LDLR. CONCLUSION DFO induced an increase in LDLR expression by a posttranscriptional mechanism resulting in an enhancement of LDL uptake in HepG2 cells, suggesting increased LDLR activity as one of the underlying causes of the hypocholesterolemic effect of iron reduction.
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Affiliation(s)
- Johann Guillemot
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), University of Montreal, Montreal, Quebec, Canada
| | - Marie-Claude Asselin
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), University of Montreal, Montreal, Quebec, Canada
| | - Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), University of Montreal, Montreal, Quebec, Canada
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), University of Montreal, Montreal, Quebec, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal (IRCM), University of Montreal, Montreal, Quebec, Canada
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Roubtsova A, Chamberland A, Marcinkiewicz J, Essalmani R, Fazel A, Bergeron JJ, Seidah NG, Prat A. PCSK9 deficiency unmasks a sex- and tissue-specific subcellular distribution of the LDL and VLDL receptors in mice. J Lipid Res 2015; 56:2133-42. [PMID: 26323289 DOI: 10.1194/jlr.m061952] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Indexed: 01/01/2023] Open
Abstract
Proprotein convertase subtilisin kexin type 9 (PCSK9), the last member of the family of Proprotein Convertases related to Subtilisin and Kexin, regulates LDL-cholesterol by promoting the endosomal/lysosomal degradation of the LDL receptor (LDLR). Herein, we show that the LDLR cell surface levels dramatically increase in the liver and pancreatic islets of PCSK9 KO male but not female mice. In contrast, in KO female mice, the LDLR is more abundant at the cell surface enterocytes, as is the VLDL receptor (VLDLR) at the cell surface of adipocytes. Ovariectomy of KO female mice led to a typical KO male pattern, whereas 17β-estradiol (E2) treatment restored the female pattern without concomitant changes in LDLR adaptor protein 1 (also known as ARH), disabled-2, or inducible degrader of the LDLR expression levels. We also show that this E2-mediated regulation, which is observed only in the absence of PCSK9, is abolished upon feeding the mice a high-cholesterol diet. The latter dramatically represses PCSK9 expression and leads to high surface levels of the LDLR in the hepatocytes of all sexes and genotypes. In conclusion, the absence of PCSK9 results in a sex- and tissue-specific subcellular distribution of the LDLR and VLDLR, which is determined by E2 levels.
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Affiliation(s)
- Anna Roubtsova
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (affiliated with the University of Montreal), Montreal, Quebec, Canada
| | - Ann Chamberland
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (affiliated with the University of Montreal), Montreal, Quebec, Canada
| | - Jadwiga Marcinkiewicz
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (affiliated with the University of Montreal), Montreal, Quebec, Canada
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (affiliated with the University of Montreal), Montreal, Quebec, Canada
| | - Ali Fazel
- Department of Medicine, McGill University Hospital Research Institute, Montreal, Quebec, Canada
| | - John J Bergeron
- Department of Medicine, McGill University Hospital Research Institute, Montreal, Quebec, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (affiliated with the University of Montreal), Montreal, Quebec, Canada
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Institut de Recherches Cliniques de Montréal (affiliated with the University of Montreal), Montreal, Quebec, Canada
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21
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Butkinaree C, Canuel M, Essalmani R, Poirier S, Benjannet S, Asselin MC, Roubtsova A, Hamelin J, Marcinkiewicz J, Chamberland A, Guillemot J, Mayer G, Sisodia SS, Jacob Y, Prat A, Seidah NG. Amyloid Precursor-like Protein 2 and Sortilin Do Not Regulate the PCSK9 Convertase-mediated Low Density Lipoprotein Receptor Degradation but Interact with Each Other. J Biol Chem 2015; 290:18609-20. [PMID: 26085104 DOI: 10.1074/jbc.m115.647180] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Indexed: 01/07/2023] Open
Abstract
Amyloid precursor-like protein 2 (APLP2) and sortilin were reported to individually bind the proprotein convertase subtilisin/kexin type 9 (PCSK9) and regulate its activity on the low-density lipoprotein receptor (LDLR). The data presented herein demonstrate that mRNA knockdowns of APLP2, sortilin, or both in the human hepatocyte cell lines HepG2 and Huh7 do not affect the ability of extracellular PCSK9 to enhance the degradation of the LDLR. Furthermore, mice deficient in APLP2 or sortilin do not exhibit significant changes in liver LDLR or plasma total cholesterol levels. Moreover, cellular overexpression of one or both proteins does not alter PCSK9 secretion, or its activity on the LDLR. We conclude that PCSK9 enhances the degradation of the LDLR independently of either APLP2 or sortilin both ex vivo and in mice. Interestingly, when co-expressed with PCSK9, both APLP2 and sortilin were targeted for lysosomal degradation. Using chemiluminescence proximity and co-immunoprecipitation assays, as well as biosynthetic analysis, we discovered that sortilin binds and stabilizes APLP2, and hence could regulate its intracellular functions on other targets.
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Affiliation(s)
- Chutikarn Butkinaree
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Maryssa Canuel
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Rachid Essalmani
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Steve Poirier
- the Laboratory of Molecular Cell Biology, Montreal Heart Institute, 5000 Bélanger, Montréal, Quebec H1T 1C8, Canada
| | - Suzanne Benjannet
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Marie-Claude Asselin
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Anna Roubtsova
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Josée Hamelin
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Jadwiga Marcinkiewicz
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Ann Chamberland
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Johann Guillemot
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Gaétan Mayer
- the Laboratory of Molecular Cell Biology, Montreal Heart Institute, 5000 Bélanger, Montréal, Quebec H1T 1C8, Canada
| | - Sangram S Sisodia
- the Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
| | - Yves Jacob
- the Département de Virologie, Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, F-75015 Paris, France, the CNRS, URA3015, F-75015 Paris, France, and the Université Paris Diderot, Sorbonne Paris Cité, Unité de Génétique Moléculaire des Virus à ARN, F-75015 Paris, France
| | - Annik Prat
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Nabil G Seidah
- From the Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada,
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Awan Z, Denis M, Roubtsova A, Essalmani R, Marcinkiewicz J, Awan A, Gram H, Seidah NG, Genest J. Reducing Vascular Calcification by Anti-IL-1β Monoclonal Antibody in a Mouse Model of Familial Hypercholesterolemia. Angiology 2015; 67:157-67. [PMID: 25904765 DOI: 10.1177/0003319715583205] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Given the link between cholesterol and activation of inflammation via interleukin 1β (IL-1β), we tested the effects of IL-1β inhibition on atherosclerotic calcification in mice. Patients with familial hypercholesterolemia develop extensive aortic calcification and calcific aortic stenosis. Although statins delay this process, low-density lipoprotein (LDL) cholesterol lowering alone is not enough to avert it. Data suggest that vascular inflammation initiated by hypercholesterolemia is followed by unchecked mineralization at sites of atherosclerotic plaques. The LDL-receptor (LDLR)-deficient (Ldlr(-/-)) and LDLR-attenuated Pcsk9(Tg) mice are available animal models for pharmacological testing. METHODS A mouse monoclonal antibody (mAb) against IL-1β or placebo was administered subcutaneously in Ldlr(-/-) and Pcsk9(Tg) models fed a Western diet. Drug level, anthropometric, lipid, and glucose profiles were determined. Expressions of proprotein convertase subtilisin/kexin type 9 (PCSK9), serum amyloid A1, and cytokine were measured by enzyme-linked immunosorbent assay. Aortic calcification was determined by microcomputerized tomography (micro-CT) and X-ray densitometry, and aortic flow velocity was assessed by ultrasound. RESULTS Circulating levels of IL-1β in Ldlr(-/-) mice were significantly greater (2-fold) than observed in Pcsk9(Tg) mice. Placebo- and mAb-treated mice did not differ in their growth, lipid, glucose profiles, and other cytokines. Calcifications were significantly diminished in mAb-treatment Ldlr(-/-) mice (a reduction of ∼ 75% by X-ray and ∼ 90% by micro-CT) and reduced insignificantly in mAb-treatment Pcsk9(Tg) mice, whereas aortic flow velocity was unchanged in both models. CONCLUSIONS Herein, we demonstrate that aortic calcifications can be inhibited by an IL-1β mAb in LDLR-deficient mice. These results have a translational component to prevent vascular calcification in human and represent new evidence to rationalize targeting inflammation in cardiovascular disease.
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Affiliation(s)
- Zuhier Awan
- Division of Clinical Biochemistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Maxime Denis
- The Department Cardiology, McGill University, Montréal, Québec, Canada
| | - Anna Roubtsova
- Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
| | - Rachid Essalmani
- Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
| | | | - Amani Awan
- Division of Clinical Biochemistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Hermann Gram
- Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Nabil G Seidah
- Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
| | - Jacques Genest
- The Department Cardiology, McGill University, Montréal, Québec, Canada
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Seidah N, Essalmani R, Kim W, Welsh I, Kurpios N. The Proprotein Convertases: Cell Surface and Extracellular Matrix Remodeling. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.236.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nabil Seidah
- Biochemical NeuroendocrinologyIRCMMontrealQCCanada
| | | | - Woojin Kim
- Biochemical NeuroendocrinologyIRCMMontrealQCCanada
| | - Ian Welsh
- Molecular MedicineCornell UniversityIthacaNew YorkUnited States
| | - Natasza Kurpios
- Molecular MedicineCornell UniversityIthacaNew YorkUnited States
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Hipp MM, Shepherd D, Gileadi U, Aichinger MC, Kessler BM, Edelmann MJ, Essalmani R, Seidah NG, Reis e Sousa C, Cerundolo V. Processing of human toll-like receptor 7 by furin-like proprotein convertases is required for its accumulation and activity in endosomes. Immunity 2013; 39:711-21. [PMID: 24138882 PMCID: PMC4839496 DOI: 10.1016/j.immuni.2013.09.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 07/25/2013] [Indexed: 11/18/2022]
Abstract
Toll-like receptor 7 (TLR7) triggers antiviral immune responses by recognizing viral single-stranded RNA in endosomes, but the biosynthetic pathway of human TLR7 (hTLR7) remains unclear. Here, we show that hTLR7 is proteolytically processed and that the C-terminal fragment selectively accumulates in endocytic compartments. hTLR7 processing occurred at neutral pH and was dependent on furin-like proprotein convertases (PCs). Furthermore, TLR7 processing was required for its functional response to TLR7 agonists such as R837 or influenza virus. Notably, proinflammatory and differentiation stimuli increased the expression of furin-like PCs in immune cells, suggesting a positive feedback mechanism for TLR7 processing during infection. Because self-RNA can under certain conditions activate TLR7 and trigger autoimmunity, our results identify furin-like PCs as a possible target to attenuate TLR7-dependent autoimmunity and other immune pathologies.
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Affiliation(s)
- Madeleine M Hipp
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DU, UK
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Essalmani R, Susan-Resiga D, Chamberland A, Asselin MC, Canuel M, Constam D, Creemers JW, Day R, Gauthier D, Prat A, Seidah NG. Furin is the primary in vivo convertase of angiopoietin-like 3 and endothelial lipase in hepatocytes. J Biol Chem 2013; 288:26410-8. [PMID: 23918928 DOI: 10.1074/jbc.m113.501304] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The proprotein convertases (PCs) furin, PC5/6, and PACE4 exhibit unique and/or complementary functions. Their knock-out (KO) in mice resulted in strong and specific phenotypes demonstrating that, in vivo, these PCs are unique and essential during development. However, they also exhibit redundant functions. Liver angiopoietin-like 3 (ANGPTL3) inhibits lipolysis by binding to lipoprotein lipases. It is found in the plasma as full length and truncated forms. The latter is more active and generated by cleavage at a furin-like site. Endothelial lipase (EL) binds heparin sulfate proteoglycans on cell surfaces and catalyzes the hydrolysis of HDL phospholipids. EL activity is regulated by two endogenous inhibitors, ANGPTL3 and ANGPTL4, and by PCs that inactivate EL through cleavage releasing the N-terminal catalytic and C-terminal lipid-binding domains. Herein, because furin and PC5/6 complete KOs are lethal, we used mice lacking furin or PC5/6 specifically in hepatocytes (hKO) or mice completely lacking PACE4. In primary hepatocytes, ANGPTL3 was processed into a shorter form of ANGPTL3 intracellularly by furin only, and extracellularly mainly by PACE4. In vivo, the absence of furin in hepatocytes reduced by ∼50% the circulating levels of cleaved ANGPTL3, while the lack of PACE4 had only a minor effect. Analysis of the EL processing in primary hepatocytes and in vivo revealed that it is mostly cleaved by furin. However, the lack of furin or PC5/6 in hepatocytes and complete PACE4 KO did not appreciably modify plasma HDL levels or EL activity. Thus, inhibition of furin in liver would not be expected to modify the plasma lipid profiles.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Sun X, Essalmani R, Susan-Resiga D, Prat A, Seidah NG. Latent transforming growth factor beta-binding proteins-2 and -3 inhibit the proprotein convertase 5/6A. J Biol Chem 2011; 286:29063-29073. [PMID: 21700711 DOI: 10.1074/jbc.m111.242479] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The basic amino acid-specific proprotein convertase 5/6 (PC5/6) is an essential secretory protease, as knock-out mice die at birth and exhibit multiple homeotic transformation defects, including impaired bone morphogenesis and lung structure. Some of the observed defects were attributed to impaired processing of the TGFβ-like growth differentiating factor 11 precursor (proGdf11). In this work we present evidence that the latent TGFβ-binding proteins 2 and 3 (LTBP-2 and -3) inhibit the extracellular processing of proGdf11 by PC5/6A. This is partly due to the binding of LTBPs in the endoplasmic reticulum to the zymogen proPC5/6A, thus allowing the complex to exit the endoplasmic reticulum and be sequestered as an inactive zymogen in the extracellular matrix but not at the cell surface. This results in lower levels of PC5/6A in the media, without affecting those of PACE4, Furin, or a soluble form of PC7. The secreted soluble protease-specific activity of PC5/6A or a variant lacking the C-terminal Cys-rich domain (PC5/6-ΔCRD) is significantly decreased when co-expressed with LTBPs in cells. A similar enzymatic inhibition seems to apply to PACE4 and Furin. In situ hybridization analyses revealed extensive co-localization of PC5/6 and LTBP-3 mRNAs in mice at embryonic day 15.5 and post partum day 1. In conclusion, this is the first time that a zymogen of the proprotein convertases was shown to exit the endoplasmic reticulum in the presence of LTBPs, representing a potential novel mechanism for the regulation of PC5/6A activity, e.g. in tissues such as bone and lung where LTBP-3 and PC5/6 co-localize.
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Affiliation(s)
- Xiaowei Sun
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada.
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Susan-Resiga D, Essalmani R, Hamelin J, Asselin MC, Benjannet S, Chamberland A, Day R, Szumska D, Constam D, Bhattacharya S, Prat A, Seidah NG. Furin is the major processing enzyme of the cardiac-specific growth factor bone morphogenetic protein 10. J Biol Chem 2011; 286:22785-94. [PMID: 21550985 DOI: 10.1074/jbc.m111.233577] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bone morphogenetic protein 10 (BMP10) is a member of the TGF-β superfamily and plays a critical role in heart development. In the postnatal heart, BMP10 is restricted to the right atrium. The inactive pro-BMP10 (∼60 kDa) is processed into active BMP10 (∼14 kDa) by an unknown protease. Proteolytic cleavage occurs at the RIRR(316)↓ site (human), suggesting the involvement of proprotein convertase(s) (PCs). In vitro digestion of a 12-mer peptide encompassing the predicted cleavage site with furin, PACE4, PC5/6, and PC7, showed that furin cleaves the best, whereas PC7 is inactive on this peptide. Ex vivo studies in COS-1 cells, a cell line lacking PC5/6, revealed efficient processing of pro-BMP10 by endogenous PCs other than PC5/6. The lack of processing of overexpressed pro-BMP10 in the furin- and PACE4-deficient cell line, CHO-FD11, and in furin-deficient LoVo cells, was restored by stable (CHO-FD11/Fur cells) or transient (LoVo cells) expression of furin. Use of cell-permeable and cell surface inhibitors suggested that endogenous PCs process pro-BMP10 mostly intracellularly, but also at the cell surface. Ex vivo experiments in mouse primary hepatocytes (wild type, PC5/6 knock-out, and furin knock-out) corroborated the above findings that pro-BMP10 is a substrate for endogenous furin. Western blot analyses of heart right atria extracts from wild type and PACE4 knock-out adult mice showed no significant difference in the processing of pro-BMP10, implying no in vivo role of PACE4. Overall, our in vitro, ex vivo, and in vivo data suggest that furin is the major convertase responsible for the generation of BMP10.
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Affiliation(s)
- Delia Susan-Resiga
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Université de Montréal, Montreal, Quebec H2W 1R7, Canada
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Essalmani R, Susan-Resiga D, Chamberland A, Abifadel M, Creemers JW, Boileau C, Seidah NG, Prat A. In vivo evidence that furin from hepatocytes inactivates PCSK9. J Biol Chem 2010; 286:4257-63. [PMID: 21147780 DOI: 10.1074/jbc.m110.192104] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The proprotein convertase PCSK9 plays a key role in cholesterol homeostasis by binding the LDL receptor and targeting it toward degradation. PCSK9 is strongly expressed in the liver and is found in human and mouse plasma as mature (∼ 62 kDa) and inactivated (∼ 55 kDa) forms. Ex vivo data showed that human PCSK9 is inactivated by cleavage at Arg(218)↓ by the overexpressed convertases furin and PC5/6A. Analysis of the plasma of human heterozygotes for R218S and F216L mutations revealed a ∼ 50% reduction in the levels of the ∼ 55-kDa form. To identify the convertase(s) responsible for cleavage at Arg(218) in vivo, we inactivated the genes of furin and/or PC5/6 specifically in hepatocytes. The PCSK9-inactivated form was strongly reduced in mice lacking furin in hepatocytes (Fur-hKO) and only slightly reduced in PC5/6-hKO plasma. In agreement with a key role of furin in regulating PCSK9 activity in vivo, we observed an overall 26% drop in the LDL receptor protein levels of Fur-hKO livers, likely due to the compound effects of a 35% increase in PCSK9 mRNA levels and the loss of PCSK9 cleavage, suggesting a higher activity of PCSK9 in these mice. Overexpression of PCSK9 in primary hepatocytes obtained from these mice revealed that only full-length, membrane-bound, but not soluble, furin is the cognate convertase. We conclude that in hepatocytes furin regulates PCSK9 mRNA levels and is the key in vivo-inactivating protease of circulating PCSK9.
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Affiliation(s)
- Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
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Benjannet S, Saavedra YGL, Hamelin J, Asselin MC, Essalmani R, Pasquato A, Lemaire P, Duke G, Miao B, Duclos F, Parker R, Mayer G, Seidah NG. Effects of the prosegment and pH on the activity of PCSK9: evidence for additional processing events. J Biol Chem 2010; 285:40965-78. [PMID: 20937814 DOI: 10.1074/jbc.m110.154815] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PCSK9, a target for the treatment of dyslipidemia, enhances the degradation of the LDL receptor (LDLR) in endosomes/lysosomes, up-regulating LDL-cholesterol levels. Whereas the targeting and degradation of the PCSK9-LDLR complex are under scrutiny, the roles of the N- and C-terminal domains of PCSK9 are unknown. Although autocatalytic zymogen processing of PCSK9 occurs at Gln(152)↓, here we show that human PCSK9 can be further cleaved in its N-terminal prosegment at Arg(46)↓ by an endogenous enzyme of insect High Five cells and by a cellular mammalian protease, yielding an ∼4-fold enhanced activity. Removal of the prosegment acidic stretch resulted in ∼3-fold higher binding to LDLR in vitro, in ≥4-fold increased activity on cellular LDLR, and faster cellular internalization in endosome/lysosome-like compartments. Finally, swapping the acidic stretch of PCSK9 with a similar one found in the glycosylphosphatidylinositol-anchored heparin-binding protein 1 does not impair PCSK9 autoprocessing, secretion, or activity and confirmed that the acidic stretch acts as an inhibitor of PCSK9 function. We also show that upon short exposure to pH values 6.5 to 5.5, an ∼2.5-fold increase in PCSK9 activity on total and cell surface LDLR occurs, and PCSK9 undergoes a second cleavage at Arg(248), generating a two-chain PCSK9-ΔN(248). At pH values below 5.5, PCSK9 dissociates from its prosegment and loses its activity. This pH-dependent activation of PCSK9 represents a novel pathway to further activate PCSK9 in acidic endosomes. These data enhance our understanding of the functional role of the acidic prosegment and on the effect of pH in the regulation of PCSK9 activity.
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Affiliation(s)
- Suzanne Benjannet
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
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Sun X, Essalmani R, Seidah NG, Prat A. The proprotein convertase PC5/6 is protective against intestinal tumorigenesis: in vivo mouse model. Mol Cancer 2009; 8:73. [PMID: 19737405 PMCID: PMC2746178 DOI: 10.1186/1476-4598-8-73] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Accepted: 09/08/2009] [Indexed: 03/26/2023] Open
Abstract
Background The secretory basic amino acid-specific proprotein convertases (PCs) have often been associated with cancer/metastasis. By controlling the cleavage of cancer-associated proteins, PCs play key roles in multiple steps of cancer development. Most analyses of the implication of PCs in cancer/metastasis relied on the use of in vitro overexpression systems or inhibitors that can affect more than one PC. Aside from the role of furin in salivary gland tumorigenesis, no other in vivo genetic model of PC-knockout was reported in relation to cancer development. Results Since PC5/6 is highly expressed in the small intestine, the present study examined its in vivo role in intestinal tumorigenesis. Analysis of human intestinal tumors at various stages showed a systematic down-regulation of PC5/6 expression. Since gene inactivation of PC5/6 leads to lethality at birth, we generated mice lacking PC5/6 in enterocytes and analyzed the impact of the presence or absence of this PC in the mouse ApcMin/+ model that develops numerous adenocarcinomas along the intestinal tract. This resulted in viable mice with almost no expression of PC5/6 in small intestine, but with no overt phenotype. The data showed that by themselves ApcMin/+ tumors express lower levels of PC5/6 mRNA, and that the lack of PC5/6 in enterocytes results in a significantly higher tumor number in the duodenum, with a similar trend in other intestinal segments. Finally, the absence of PC5/6 is also associated with a premature mortality of ApcMin/+ mice. Conclusion Overall, these data suggest that intestinal PC5/6 is protective towards tumorigenesis, especially in mouse duodenum, and possibly in human colon.
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Affiliation(s)
- Xiaowei Sun
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, affiliated to the University of Montreal, Montreal, Quebec, Canada.
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32
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Szumska D, Pieles G, Essalmani R, Bilski M, Mesnard D, Kaur K, Franklyn A, El Omari K, Jefferis J, Bentham J, Taylor JM, Schneider JE, Arnold SJ, Johnson P, Tymowska-Lalanne Z, Stammers D, Clarke K, Neubauer S, Morris A, Brown SD, Shaw-Smith C, Cama A, Capra V, Ragoussis J, Constam D, Seidah NG, Prat A, Bhattacharya S. VACTERL/caudal regression/Currarino syndrome-like malformations in mice with mutation in the proprotein convertase Pcsk5. Genes Dev 2008; 22:1465-77. [PMID: 18519639 DOI: 10.1101/gad.479408] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have identified an ethylnitrosourea (ENU)-induced recessive mouse mutation (Vcc) with a pleiotropic phenotype that includes cardiac, tracheoesophageal, anorectal, anteroposterior patterning defects, exomphalos, hindlimb hypoplasia, a presacral mass, renal and palatal agenesis, and pulmonary hypoplasia. It results from a C470R mutation in the proprotein convertase PCSK5 (PC5/6). Compound mutants (Pcsk5(Vcc/null)) completely recapitulate the Pcsk5(Vcc/Vcc) phenotype, as does an epiblast-specific conditional deletion of Pcsk5. The C470R mutation ablates a disulfide bond in the P domain, and blocks export from the endoplasmic reticulum and proprotein convertase activity. We show that GDF11 is cleaved and activated by PCSK5A, but not by PCSK5A-C470R, and that Gdf11-deficient embryos, in addition to having anteroposterior patterning defects and renal and palatal agenesis, also have a presacral mass, anorectal malformation, and exomphalos. Pcsk5 mutation results in abnormal expression of several paralogous Hox genes (Hoxa, Hoxc, and Hoxd), and of Mnx1 (Hlxb9). These include known Gdf11 targets, and are necessary for caudal embryo development. We identified nonsynonymous mutations in PCSK5 in patients with VACTERL (vertebral, anorectal, cardiac, tracheoesophageal, renal, limb malformation OMIM 192350) and caudal regression syndrome, the phenotypic features of which resemble the mouse mutation. We propose that Pcsk5, at least in part via GDF11, coordinately regulates caudal Hox paralogs, to control anteroposterior patterning, nephrogenesis, skeletal, and anorectal development.
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Affiliation(s)
- Dorota Szumska
- Department of Cardiovascular Medicine and Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
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33
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Zaid A, Roubtsova A, Essalmani R, Marcinkiewicz J, Chamberland A, Hamelin J, Tremblay M, Jacques H, Jin W, Davignon J, Seidah NG, Prat A. Proprotein convertase subtilisin/kexin type 9 (PCSK9): hepatocyte-specific low-density lipoprotein receptor degradation and critical role in mouse liver regeneration. Hepatology 2008; 48:646-54. [PMID: 18666258 DOI: 10.1002/hep.22354] [Citation(s) in RCA: 303] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED The gene encoding the proprotein convertase subtilisin/kexin type 9 (PCSK9) is linked to familial hypercholesterolemia, as are those of the low-density lipoprotein receptor (LDLR) and apolipoprotein B. PCSK9 enhances LDLR degradation, resulting in low-density lipoprotein accumulation in plasma. To analyze the role of hepatic PCSK9, total and hepatocyte-specific knockout mice were generated. They exhibit 42% and 27% less circulating cholesterol, respectively, showing that liver PCSK9 was responsible for two thirds of the phenotype. We also demonstrated that, in liver, PCSK9 is exclusively expressed in hepatocytes, representing the main source of circulating PCSK9. The data suggest that local but not circulating PCSK9 regulates cholesterol levels. Although transgenic mice overexpressing high levels of liver and circulating PCSK9 led to the almost complete disappearance of the hepatic LDLR, they did not recapitulate the plasma cholesterol levels observed in LDLR-deficient mice. Single LDLR or double LDLR/PCSK9 knockout mice exhibited similar cholesterol profiles, indicating that PCSK9 regulates cholesterol homeostasis exclusively through the LDLR. Finally, the regenerating liver of PCSK9-deficient mice exhibited necrotic lesions, which were prevented by a high-cholesterol diet. However, lipid accumulation in hepatocytes of these mice was markedly reduced under both chow and high-cholesterol diets, revealing that PCSK9 deficiency confers resistance to liver steatosis. CONCLUSION Although PCSK9 is a target for controlling hypercholesterolemia, our data indicate that upon hepatic damage, patients lacking PCSK9 could be at risk.
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Affiliation(s)
- Ahmed Zaid
- Laboratorie of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, affiliated to the University of Montreal, Montreal, Quebec, Canada
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Béringue V, Andréoletti O, Le Dur A, Essalmani R, Vilotte JL, Lacroux C, Reine F, Herzog L, Biacabé AG, Baron T, Caramelli M, Casalone C, Laude H. A bovine prion acquires an epidemic bovine spongiform encephalopathy strain-like phenotype on interspecies transmission. J Neurosci 2007; 27:6965-71. [PMID: 17596445 PMCID: PMC6672218 DOI: 10.1523/jneurosci.0693-07.2007] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Implementation in Europe of large-scale testing to detect bovine spongiform encephalopathy (BSE)-infected cattle and prevent the transmission of this prion disease to humans has recently led to the discovery of novel types of bovine prions. We characterized atypical isolates called BSE L-type by analyzing their molecular and neuropathological properties during transmission to several mouse lines transgenic for the prion protein (PrP). Unexpectedly, such isolates acquired strain features closely similar to those of BSE-type agents when propagated in mice expressing ovine PrP, although they retained phenotypic traits distinct from BSE in other lines, including bovine PrP mice. These findings further underline the relationship between the crossing of species barrier and prion strain diversification, and, although the origin of the epidemic BSE agent has only been speculative until now, they provide new insight into the nature of the events that could have led to the appearance of this agent.
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Affiliation(s)
- Vincent Béringue
- Institut National de la Recherche Agronomique (INRA), Unité de Recherche 892, Virologie Immunologie Moléculaires, F-78350 Jouy-en-Josas, France
| | - Olivier Andréoletti
- INRA, Unité Mixte de Recherche 1225, Interactions Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire, F-31000 Toulouse, France
| | - Annick Le Dur
- Institut National de la Recherche Agronomique (INRA), Unité de Recherche 892, Virologie Immunologie Moléculaires, F-78350 Jouy-en-Josas, France
| | - Rachid Essalmani
- INRA, Unité de Recherche 339, Génétique Biochimique et Cytogénétique, F-78350 Jouy-en-Josas, France
| | - Jean-Luc Vilotte
- INRA, Unité de Recherche 339, Génétique Biochimique et Cytogénétique, F-78350 Jouy-en-Josas, France
| | - Caroline Lacroux
- INRA, Unité Mixte de Recherche 1225, Interactions Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire, F-31000 Toulouse, France
| | - Fabienne Reine
- Institut National de la Recherche Agronomique (INRA), Unité de Recherche 892, Virologie Immunologie Moléculaires, F-78350 Jouy-en-Josas, France
| | - Laëtitia Herzog
- Institut National de la Recherche Agronomique (INRA), Unité de Recherche 892, Virologie Immunologie Moléculaires, F-78350 Jouy-en-Josas, France
| | - Anne-Gaëlle Biacabé
- Agence Française de Sécurité Sanitaire des Aliments, Unité Agents Transmissibles Non Conventionnels, F-69000 Lyon, France, and
| | - Thierry Baron
- Agence Française de Sécurité Sanitaire des Aliments, Unité Agents Transmissibles Non Conventionnels, F-69000 Lyon, France, and
| | - Maria Caramelli
- Instituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle, d'Aosta, Torino, Italy
| | - Cristina Casalone
- Instituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle, d'Aosta, Torino, Italy
| | - Hubert Laude
- Institut National de la Recherche Agronomique (INRA), Unité de Recherche 892, Virologie Immunologie Moléculaires, F-78350 Jouy-en-Josas, France
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Essalmani R, Hamelin J, Marcinkiewicz J, Chamberland A, Mbikay M, Chrétien M, Seidah NG, Prat A. Deletion of the gene encoding proprotein convertase 5/6 causes early embryonic lethality in the mouse. Mol Cell Biol 2006; 26:354-61. [PMID: 16354705 PMCID: PMC1317638 DOI: 10.1128/mcb.26.1.354-361.2006] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PC5 belongs to the proprotein convertase family and activates precursor proteins by cleavage at basic sites during their transit through the secretory pathway and/or at the cell surface. These precursors include prohormones, proreceptors, growth factors, adhesion molecules, and viral glycoproteins. The Pcsk5 gene encodes two alternatively spliced isoforms, the soluble PC5A and transmembrane PC5B. We have carefully analyzed the expression of PC5 in the mouse during development and in adulthood by in situ hybridization, as well as in mouse tissues and various cell lines by quantitative reverse transcription-PCR. The data show that adrenal cortex and intestine are the richest sources of PC5A and PC5B, respectively. To better define the specific physiological roles of PC5, we have generated a mouse Pcsk5(Delta4)-deficient allele missing exon 4 that encodes the catalytic Asp173. While Delta4/+ heterozygotes were healthy and fertile, genotyping of progeny obtained from Delta4/+ interbreeding indicated that Delta4/Delta4 embryos died between embryonic days 4.5 and 7.5. These data demonstrate that Pcsk5 is an essential gene.
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Affiliation(s)
- Rachid Essalmani
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, 110 Pine Avenue West, Montreal, Quebec H2W 1R7, Canada
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Benjannet S, Rhainds D, Essalmani R, Mayne J, Wickham L, Jin W, Asselin MC, Hamelin J, Varret M, Allard D, Trillard M, Abifadel M, Tebon A, Attie AD, Rader DJ, Boileau C, Brissette L, Chrétien M, Prat A, Seidah NG. NARC-1/PCSK9 and Its Natural Mutants. J Biol Chem 2004; 279:48865-75. [PMID: 15358785 DOI: 10.1074/jbc.m409699200] [Citation(s) in RCA: 482] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The discovery of autosomal dominant hypercholesterolemic patients with mutations in the PCSK9 gene, encoding the proprotein convertase NARC-1, resulting in the missense mutations suggested a role in low density lipoprotein (LDL) metabolism. We show that the endoplasmic reticulum-localized proNARC-1 to NARC-1 zymogen conversion is Ca2+-independent and that within the zymogen autocatalytic processing site SSVFAQ [downward arrow]SIP Val at P4 and Pro at P3' are critical. The S127R and D374Y mutations result in approximately 50-60% and > or =98% decrease in zymogen processing, respectively. In contrast, the double [D374Y + N157K], F216L, and R218S natural mutants resulted in normal zymogen processing. The cell surface LDL receptor (LDLR) levels are reduced by 35% in lymphoblasts of S127R patients. The LDLR levels are also reduced in stable HepG2 cells overexpressing NARC-1 or its natural mutant S127R, and this reduction is abrogated in the presence of 5 mm ammonium chloride, suggesting that overexpression of NARC-1 increases the turnover rate of the LDLR. Adenoviral expression of wild type human NARC-1 in mice resulted in a maximal approximately 9-fold increase in circulating LDL cholesterol, while in LDLR-/- mice a delayed approximately 2-fold increase in LDL cholesterol was observed. In conclusion, NARC-1 seems to affect both the level of LDLR and that of circulating apoB-containing lipoproteins in an LDLR-dependent and -independent fashion.
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Affiliation(s)
- Suzanne Benjannet
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec H2W 1R7, Canada
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Abstract
The ovine Doppel-encoding gene transcription unit (TU) and proximal flanking regions were cloned from a bacterial artificial chromosome (BAC) and sequenced. The 4586 bp TU is composed of two exons and one intron. When compared with its human counterpart, beside the open reading frame and part of the 3' untranslated sequence, significant regions of homology were found within the intron and the proximal 5' flanking regions. Sequence analysis of the BAC clone revealed that the ovine Prnd gene is located around 52 kb downstream of the Prnp locus. Expression of the sheep and murine Prnd genes was observed in all tissues analyzed of transgenic mice bearing the BAC insert, with a noticeable highest expression level observed in the testis, with no associated noticeable phenotype. The present data suggest that, in contrast to ovine Prnp, ovine Prnd expression in transgenic mice has no obvious influence on conferred susceptibility to scrapie.
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Affiliation(s)
- Rachid Essalmani
- Laboratoire de Génétique Biochimique et de Cytogénétique, Département de Génétique Animale, Institut National de la Recherche Agronomique, 78352 Cedex, Jouy-en-Josas, France
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38
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Laude H, Vilette D, Le Dur A, Archer F, Soulier S, Besnard N, Essalmani R, Vilotte JL. New in vivo and ex vivo models for the experimental study of sheep scrapie: development and perspectives. C R Biol 2002; 325:49-57. [PMID: 11862622 DOI: 10.1016/s1631-0691(02)01393-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Sheep scrapie is a prototypical transmissible spongiform encephalopathy (TSE), and the most widespread of these diseases. Experimental study of TSE infectious agents from sheep and other species essentially depends on bioassays in rodents. Transmission of natural sheep scrapie to conventional mice commonly requires one or two years. In an effort to develop laboratory models in which investigations on the sheep TSE agent would be facilitated, we have established mice and cell lines that were genetically engineered to express ovine PrP protein and examined their susceptibility to the infection. A series of transgenic mice lines (tgOv) expressing the high susceptibility allele (VRQ) of the ovine PrP gene from different constructs was expanded. Following intracerebral inoculation with natural scrapie isolates, all animals developed typical TSE neurological signs and accumulated abnormal PrP in their brain. The survival time in the highest expressing tgOv lines ranged from 2 to 7 months, depending on the isolate. It was inversely related to the brain PrP content, and essentially unchanged on further passaging. Ovine PrP transgene expression thus enhanced scrapie disease transmission from sheep to mice. Such tgOv mice may bring new opportunities for analysing the natural variation of scrapie strains and measuring infectivity. As no relevant cell culture models for agents of naturally-occurring TSE exist, we have explored various strategies in order to obtain stable cell lines that would propagate the sheep agent ex vivo without prior adaptation to rodent. In one otherwise refractory rabbit epithelial cell line, a regulable expression of ovine PrP was achieved and found to enable an efficient replication of the scrapie agent in inoculated cultures. Cells derived from sheep embryos or from tgOv mice were also used in an attempt to establish permissive cell lines derived from the nervous system. Cells engineered to express PrP proteins of a specified sequence may thus represent a promising strategy to further explore, at the cellular level, various aspects of TSE diseases.
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Affiliation(s)
- Hubert Laude
- Unité de virologie et immunologie moléculaires, Institut national de la recherche agronomique, Jouy-en-Josas, France.
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Vilotte JL, Soulier S, Essalmani R, Stinnakre MG, Vaiman D, Lepourry L, Da Silva JC, Besnard N, Dawson M, Buschmann A, Groschup M, Petit S, Madelaine MF, Rakatobe S, Le Dur A, Vilette D, Laude H. Markedly increased susceptibility to natural sheep scrapie of transgenic mice expressing ovine prp. J Virol 2001; 75:5977-84. [PMID: 11390599 PMCID: PMC114313 DOI: 10.1128/jvi.75.13.5977-5984.2001] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The susceptibility of sheep to scrapie is known to involve, as a major determinant, the nature of the prion protein (PrP) allele, with the VRQ allele conferring the highest susceptibility to the disease. Transgenic mice expressing in their brains three different ovine PrP(VRQ)-encoding transgenes under an endogenous PrP-deficient genetic background were established. Nine transgenic (tgOv) lines were selected and challenged with two scrapie field isolates derived from VRQ-homozygous affected sheep. All inoculated mice developed neurological signs associated with a transmissible spongiform encephalopathy (TSE) disease and accumulated a protease-resistant form of PrP (PrPres) in their brains. The incubation duration appeared to be inversely related to the PrP steady-state level in the brain, irrespective of the transgene construct. The survival time for animals from the line expressing the highest level of PrP was reduced by at least 1 year compared to those of two groups of conventional mice. With one isolate, the duration of incubation was as short as 2 months, which is comparable to that observed for the rodent TSE models with the briefest survival times. No survival time reduction was observed upon subpassaging of either isolate, suggesting no need for adaptation of the agent to its new host. Overexpression of the transgene was found not to be required for transmission to be accelerated compared to that observed with wild-type mice. Conversely, transgenic mice overexpressing murine PrP were found to be less susceptible than tgOv lines expressing ovine PrP at physiological levels. These data argue that ovine PrP(VRQ) provided a better substrate for sheep prion replication than did mouse PrP. Altogether, these tgOv mice could be an improved model for experimental studies on natural sheep scrapie.
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Affiliation(s)
- J L Vilotte
- Génétique Biochimique et Cytogénétique, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas cedex, France
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Octave JN, Essalmani R, Tasiaux B, Menager J, Czech C, Mercken L. The role of presenilin-1 in the gamma-secretase cleavage of the amyloid precursor protein of Alzheimer's disease. J Biol Chem 2000; 275:1525-8. [PMID: 10636839 DOI: 10.1074/jbc.275.3.1525] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Presenilin-1 (PS1) is required for the release of the intracellular domain of Notch from the plasma membrane as well as for the cleavage of the amyloid precursor protein (APP) at the gamma-secretase cleavage site. It remains to be demonstrated whether PS1 acts by facilitating the activity of the protease concerned or is the protease itself. PS1 could have a gamma-secretase activity by itself or could traffic APP and Notch to the appropriate cellular compartment for processing. Human APP 695 and PS1 were coexpressed in Sf9 insect cells, in which endogenous gamma-secretase activity is not detected. In baculovirus-infected Sf9 cells, PS1 undergoes endoproteolysis and interacts with APP. However, PS1 does not cleave APP in Sf9 cells. In CHO cells, endocytosis of APP is required for Abeta secretion. Deletion of the cytoplasmic sequence of APP (APPDeltaC) inhibits both APP endocytosis and Abeta production. When APPDeltaC and PS1 are coexpressed in CHO cells, Abeta is secreted without endocytosis of APP. Taken together, these results conclusively show that, although PS1 does not cleave APP in Sf9 cells, PS1 allows the secretion of Abeta without endocytosis of APP by CHO cells.
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Affiliation(s)
- J N Octave
- Laboratoire de Pharmacologie Expérimentale, Université Catholique de Louvain, B-1200 Brussels, Belgium.
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Macq AF, Czech C, Essalmani R, Brion JP, Maron A, Mercken L, Pradier L, Octave JN. The long term adenoviral expression of the human amyloid precursor protein shows different secretase activities in rat cortical neurons and astrocytes. J Biol Chem 1998; 273:28931-6. [PMID: 9786896 DOI: 10.1074/jbc.273.44.28931] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recombinant adenoviruses were used for the expression of human amyloid precursor protein (APP) of Alzheimer's disease in primary cultures of rat cortical neurons and astrocytes. The catabolic pathways of human APP were studied 3 to 4 days after infection, when the equilibrium of APP production was reached. Although the expression of human wild type APP (WtAPP) by rat neurons induced the production of both extracellular and intraneuronal amyloid peptide (Abeta), Abeta was not detected in the culture medium of rat astrocytes producing human WtAPP. Because a low beta-secretase activity was previously reported in rodent astrocytes, we wondered whether modifications of the APP amino acid sequence at the beta-secretase clipping site would modify the astrocytic production of Abeta. Interestingly, rat astrocytes produced high amounts of Abeta after expression of human APP carrying a double amino acid substitution responsible for Alzheimer's disease in a large Swedish family (SwAPP). In both rat cortical neurons and astrocytes, the beta-secretase cleavage of the human SwAPP occurred very early in the secretion process in a cellular compartment in which a different sorting of SwAPP and WtAPP seems unlikely. These results suggest that human WtAPP and SwAPP could be processed by different beta-secretase activities.
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Affiliation(s)
- A F Macq
- Laboratory of Experimental Pharmacology, Université Catholique de Louvain, FARL 5410, 54 Avenue Hippocrate, B-1200 Brussels, Belgium
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Essalmani R, Guillaume JM, Mercken L, Octave JN. Baculovirus-infected cells do not produce the amyloid peptide of Alzheimer's disease from its precursor. FEBS Lett 1996; 389:157-61. [PMID: 8766821 DOI: 10.1016/0014-5793(96)00561-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The amyloid peptide (Abeta) of Alzheimer's disease (AD) is produced by proteolytic cleavage of a larger precursor, the amyloid peptide precursor or APP. The discovery of pathogenic mutations in the APP gene provides strong evidence for the hypothesis that APP metabolism is involved in the etiology of AD. To study the metabolism of the protein, human APP has been expressed in several mammalian cell types. Insect cells, infected by a recombinant baculovirus carrying the human APP sequence, also provide an interesting expression system because these cells do not produce endogenous APP. Baculovirus-infected cells synthesize very high amounts of extracellular soluble APP, after cleavage of the transmembrane protein, as described for mammalian cells. However, we demonstrate here that insect cells do not produce Abeta from APP. These results suggest that while the enzymatic activity needed for the production of soluble APP is conserved between insect and mammalian cells, the enzymes required for the production of Abeta from APP are only expressed in mammalian cells.
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Affiliation(s)
- R Essalmani
- Université Catholique de Louvain, Laboratoire de Neurochimie, Brussels, Belgium
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Essalmani R, Macq AF, Mercken L, Octave JN. Missense mutations associated with familial Alzheimer's disease in Sweden lead to the production of the amyloid peptide without internalization of its precursor. Biochem Biophys Res Commun 1996; 218:89-96. [PMID: 8573182 DOI: 10.1006/bbrc.1996.0017] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Production of soluble amyloid peptide precursor (APP) and amyloid peptide (A beta) was measured in CHO cells transfected by the wild-type APP 695 cDNA sequence or by the same sequence carrying missense mutations associated with familial Alzheimer's disease in Sweden. Deletion of the C-terminal domain of the protein corresponding to residues 654 to 695 of APP 695 not only inhibited very significantly the internalization of APP at 37 degrees C, but also led to the secretion of an uncleaved APP in the culture medium of CHO cells. This deletion did not affect A beta production from the Swedish APP but was able to inhibit the production of the wild-type APP. These results demonstrate that, in CHO cells, the internalization of the wild-type APP is needed for A beta production, while the production of the amyloid peptide from Swedish APP is independent of the internalization process.
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Affiliation(s)
- R Essalmani
- Université Catholique de Louvain, Laboratoire de Neurochimie, UCL 1080, Brussels, Belgium
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