1
|
Birts CN, Wilton DC. Could anionic LDL be a ligand for RAGE and TREM2 in addition to LOX-1 and thus exacerbate lung disease and dementia? Biochim Biophys Acta Mol Basis Dis 2023; 1869:166837. [PMID: 37544530 DOI: 10.1016/j.bbadis.2023.166837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 07/14/2023] [Accepted: 07/31/2023] [Indexed: 08/08/2023]
Abstract
We recently highlighted the potential of protein glycation to generate anionic (electronegative) surfaces. We hypothesised that these anionic proteins are perceived by the innate immune system as arising from infection or damaged cell components, producing an inflammatory response within the lung involving the receptor RAGE. We now review two other pathologies linked to the innate immune response, cardiovascular disease and dementia that involve receptors LOX-1 and TREM2 respectively. Remarkable similarities in properties between RAGE, LOX-1 and TREM2 suggest that electronegative LDL may act as a pathogenic anionic ligand for all three receptors and exacerbate lung inflammation and dementia.
Collapse
Affiliation(s)
- Charles N Birts
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton SO17 1BJ, UK; Antibody and Vaccine Group, Centre for Cancer Immunology, School of Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK.
| | - David C Wilton
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| |
Collapse
|
2
|
James JK, Norland K, Johar AS, Kullo IJ. Deep generative models of LDLR protein structure to predict variant pathogenicity. J Lipid Res 2023; 64:100455. [PMID: 37821076 PMCID: PMC10696256 DOI: 10.1016/j.jlr.2023.100455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 09/16/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023] Open
Abstract
The complex structure and function of low density lipoprotein receptor (LDLR) makes classification of protein-coding missense variants challenging. Deep generative models, including Evolutionary model of Variant Effect (EVE), Evolutionary Scale Modeling (ESM), and AlphaFold 2 (AF2), have enabled significant progress in the prediction of protein structure and function. ESM and EVE directly estimate the likelihood of a variant sequence but are purely data-driven and challenging to interpret. AF2 predicts LDLR structures, but variant effects are explicitly modeled by estimating changes in stability. We tested the effectiveness of these models for predicting variant pathogenicity compared to established methods. AF2 produced two distinct conformations based on a novel hinge mechanism. Within ESM's hidden space, benign and pathogenic variants had different distributions. In EVE, these distributions were similar. EVE and ESM were comparable to Polyphen-2, SIFT, REVEL, and Primate AI for predicting binary classifications in ClinVar. However, they were more strongly correlated with experimental measures of LDL uptake. AF2 poorly performed in these tasks. Using the UK Biobank to compare association with clinical phenotypes, ESM and EVE were more strongly associated with serum LDL-C than Polyphen-2. ESM was able to identify variants with more extreme LDL-C levels than EVE and had a significantly stronger association with atherosclerotic cardiovascular disease. In conclusion, AF2 predicted LDLR structures do not accurately model variant pathogenicity. ESM and EVE are competitive with prior scoring methods for prediction based on binary classifications in ClinVar but are superior based on correlations with experimental assays and clinical phenotypes.
Collapse
Affiliation(s)
- Jose K James
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Kristjan Norland
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Angad S Johar
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Iftikhar J Kullo
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA; Gonda Vascular Center, Mayo Clinic, Rochester, MN, USA.
| |
Collapse
|
3
|
Beenken A, Cerutti G, Brasch J, Guo Y, Sheng Z, Erdjument-Bromage H, Aziz Z, Robbins-Juarez SY, Chavez EY, Ahlsen G, Katsamba PS, Neubert TA, Fitzpatrick AWP, Barasch J, Shapiro L. Structures of LRP2 reveal a molecular machine for endocytosis. Cell 2023; 186:821-836.e13. [PMID: 36750096 PMCID: PMC9993842 DOI: 10.1016/j.cell.2023.01.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/29/2022] [Accepted: 01/10/2023] [Indexed: 02/08/2023]
Abstract
The low-density lipoprotein (LDL) receptor-related protein 2 (LRP2 or megalin) is representative of the phylogenetically conserved subfamily of giant LDL receptor-related proteins, which function in endocytosis and are implicated in diseases of the kidney and brain. Here, we report high-resolution cryoelectron microscopy structures of LRP2 isolated from mouse kidney, at extracellular and endosomal pH. The structures reveal LRP2 to be a molecular machine that adopts a conformation for ligand binding at the cell surface and for ligand shedding in the endosome. LRP2 forms a homodimer, the conformational transformation of which is governed by pH-sensitive sites at both homodimer and intra-protomer interfaces. A subset of LRP2 deleterious missense variants in humans appears to impair homodimer assembly. These observations lay the foundation for further understanding the function and mechanism of LDL receptors and implicate homodimerization as a conserved feature of the LRP receptor subfamily.
Collapse
Affiliation(s)
- Andrew Beenken
- Division of Nephrology, Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032, USA
| | - Gabriele Cerutti
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Julia Brasch
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Yicheng Guo
- Aaron Diamond AIDS Research Center, Columbia University, New York, NY 10032, USA
| | - Zizhang Sheng
- Aaron Diamond AIDS Research Center, Columbia University, New York, NY 10032, USA
| | - Hediye Erdjument-Bromage
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Zainab Aziz
- Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | | | - Estefania Y Chavez
- Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - Goran Ahlsen
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Phinikoula S Katsamba
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Thomas A Neubert
- Department of Cell Biology, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Anthony W P Fitzpatrick
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Department of Biochemistry and Molecular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032, USA; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Jonathan Barasch
- Division of Nephrology, Department of Medicine, Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032, USA; Columbia University George M. O'Brien Urology Center, New York, NY 10032, USA.
| | - Lawrence Shapiro
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA; Aaron Diamond AIDS Research Center, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032, USA.
| |
Collapse
|
4
|
A New Structural Model of Apolipoprotein B100 Based on Computational Modeling and Cross Linking. Int J Mol Sci 2022; 23:ijms231911480. [PMID: 36232786 PMCID: PMC9569473 DOI: 10.3390/ijms231911480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/17/2022] [Accepted: 09/18/2022] [Indexed: 12/02/2022] Open
Abstract
ApoB-100 is a member of a large lipid transfer protein superfamily and is one of the main apolipoproteins found on low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) particles. Despite its clinical significance for the development of cardiovascular disease, there is limited information on apoB-100 structure. We have developed a novel method based on the “divide and conquer” algorithm, using PSIPRED software, by dividing apoB-100 into five subunits and 11 domains. Models of each domain were prepared using I-TASSER, DEMO, RoseTTAFold, Phyre2, and MODELLER. Subsequently, we used disuccinimidyl sulfoxide (DSSO), a new mass spectrometry cleavable cross-linker, and the known position of disulfide bonds to experimentally validate each model. We obtained 65 unique DSSO cross-links, of which 87.5% were within a 26 Å threshold in the final model. We also evaluated the positions of cysteine residues involved in the eight known disulfide bonds in apoB-100, and each pair was measured within the expected 5.6 Å constraint. Finally, multiple domains were combined by applying constraints based on detected long-range DSSO cross-links to generate five subunits, which were subsequently merged to achieve an uninterrupted architecture for apoB-100 around a lipoprotein particle. Moreover, the dynamics of apoB-100 during particle size transitions was examined by comparing VLDL and LDL computational models and using experimental cross-linking data. In addition, the proposed model of receptor ligand binding of apoB-100 provides new insights into some of its functions.
Collapse
|
5
|
Fang Y, Zhu Y, Wu Y, Liu L, Wang H. Protective effects of mitochondrial fission inhibition on ox-LDL induced VSMC foaming via metabolic reprogramming. Front Pharmacol 2022; 13:970151. [PMID: 36120304 PMCID: PMC9478346 DOI: 10.3389/fphar.2022.970151] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/10/2022] [Indexed: 11/28/2022] Open
Abstract
Atherosclerosis (AS) is one of the most common diseases in middle-age and elderly population. Lipid metabolism disorder induced foaming of vascular smooth muscle cell (VSMC) is an important pathological process of AS. Mitochondria plays an important role in lipids metabolism. While it is not known whether regulating mitochondrial function can protect ox-LDL induced VSMC foaming via metabolic reprogramming. With ox-LDL induced mouse model of VSMC injury, the injury effect of ox-LDL and the protective effect of mdivi-1, the mitochondrial fission inhibitor on mitochondrial morphology and function of VSMC, and the formation of lipid droplet were observed. With metabonomics and proteomics techniques, the main lipid metabolites and regulation proteins were identified. The results showed that Ox-LDL induced a significant mitochondrial fission and fragmentation of VSMC, and mitochondrial function disorder along with lipid deposition and foaming. Mdivi-1 significantly antagonized the damage effect of ox-LDL on mitochondrial morphology and function of VSMC, and blocked the lipid deposition. Metabonomics analysis found 848 different metabolites between ox-LDL and mdivi-1 treatment group, in which the lipid metabolites were the main, and heptadecanoic acid, palmitoleic acid and myristic acid were the critical metabolites changed most. Proteomics results showed that there were 125 differential expressed proteins between ox-LDL and mdivi-1 treatment, acetyl -CoA carboxylase1 and fatty acid synthase were the main differential expressed proteins. This study suggest that Mitochondrial fission plays an important role in VSMC lipid deposition and foaming. Inhibition of mitochondrial fission may effectively fight against ox-LDL induced lipid deposition and foaming of VSMC via improving mitochondrial function and metabolic reprogramming. This finding provides a new insight for prevention and treatment of AS.
Collapse
Affiliation(s)
- Yijin Fang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People’s Republic of China, School of Medicine, Jinan University, Guangzhou, China
| | - Yu Zhu
- State Key Laboratory of Trauma, Burns and Combined Injury, Shock and Transfusion Department of Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, China
| | - Yue Wu
- State Key Laboratory of Trauma, Burns and Combined Injury, Shock and Transfusion Department of Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, China
| | - Liangming Liu
- State Key Laboratory of Trauma, Burns and Combined Injury, Shock and Transfusion Department of Research Institute of Surgery, Daping Hospital, Army Medical University, Chongqing, China
- *Correspondence: Liangming Liu, ; Huadong Wang,
| | - Huadong Wang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People’s Republic of China, School of Medicine, Jinan University, Guangzhou, China
- *Correspondence: Liangming Liu, ; Huadong Wang,
| |
Collapse
|
6
|
Burger AL, Pogran E, Muthspiel M, Kaufmann CC, Jäger B, Huber K. New Treatment Targets and Innovative Lipid-Lowering Therapies in Very-High-Risk Patients with Cardiovascular Disease. Biomedicines 2022; 10:biomedicines10050970. [PMID: 35625707 PMCID: PMC9138506 DOI: 10.3390/biomedicines10050970] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/15/2022] [Accepted: 04/19/2022] [Indexed: 11/16/2022] Open
Abstract
The effective and fast reduction of circulating low-density lipoprotein cholesterol (LDL-C) is a cornerstone for secondary prevention of atherosclerotic disease progression. Despite the substantial lipid-lowering effects of the established treatment option with statins and ezetimibe, a significant proportion of very-high-risk patients with cardiovascular disease do not reach the recommended treatment goal of <55 mg/dL (<1.4 mmol/L). Novel lipid-lowering agents, including the proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies alirocumab and evolocumab, the small interfering ribonucleotide acid (si-RNA) inclisiran, as well as the recently approved bempedoic acid, now complete the current arsenal of LDL-C lowering agents. These innovative therapies have demonstrated promising results in clinical studies. Besides a strong reduction of LDL-C by use of highly effective agents, there is still discussion as to whether a very rapid achievement of the treatment goal should be a new strategic approach in lipid-lowering therapy. In this review, we summarize evidence for the lipid-modifying properties of these novel agents and their safety profiles, and discuss their potential pleiotropic effects beyond LDL-C reduction (if any) as well as their effects on clinical endpoints as cardiovascular mortality. In addition to a treatment strategy of “the lower, the better”, we also discuss the concept of “the earlier, the better”, which may also add to the early clinical benefit of large LDL-C reduction after an acute ischemic event.
Collapse
Affiliation(s)
- Achim Leo Burger
- 3rd Medical Department with Cardiology and Intensive Care Medicine, Clinic Ottakring (Wilhelminenhospital), Montleartstrasse 37, 1160 Vienna, Austria; (A.L.B.); (E.P.); (M.M.); (C.C.K.); (B.J.)
| | - Edita Pogran
- 3rd Medical Department with Cardiology and Intensive Care Medicine, Clinic Ottakring (Wilhelminenhospital), Montleartstrasse 37, 1160 Vienna, Austria; (A.L.B.); (E.P.); (M.M.); (C.C.K.); (B.J.)
| | - Marie Muthspiel
- 3rd Medical Department with Cardiology and Intensive Care Medicine, Clinic Ottakring (Wilhelminenhospital), Montleartstrasse 37, 1160 Vienna, Austria; (A.L.B.); (E.P.); (M.M.); (C.C.K.); (B.J.)
| | - Christoph Clemens Kaufmann
- 3rd Medical Department with Cardiology and Intensive Care Medicine, Clinic Ottakring (Wilhelminenhospital), Montleartstrasse 37, 1160 Vienna, Austria; (A.L.B.); (E.P.); (M.M.); (C.C.K.); (B.J.)
| | - Bernhard Jäger
- 3rd Medical Department with Cardiology and Intensive Care Medicine, Clinic Ottakring (Wilhelminenhospital), Montleartstrasse 37, 1160 Vienna, Austria; (A.L.B.); (E.P.); (M.M.); (C.C.K.); (B.J.)
| | - Kurt Huber
- 3rd Medical Department with Cardiology and Intensive Care Medicine, Clinic Ottakring (Wilhelminenhospital), Montleartstrasse 37, 1160 Vienna, Austria; (A.L.B.); (E.P.); (M.M.); (C.C.K.); (B.J.)
- Medical School, Sigmund Freud University, 1020 Vienna, Austria
- Correspondence: ; Tel.: +43-1-49150-2301
| |
Collapse
|
7
|
PCSK9 promotes tumor growth by inhibiting tumor cell apoptosis in hepatocellular carcinoma. Exp Hematol Oncol 2021; 10:25. [PMID: 33789749 PMCID: PMC8011384 DOI: 10.1186/s40164-021-00218-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 03/20/2021] [Indexed: 02/07/2023] Open
Abstract
Background Proprotein convertase subtilisin/kexin type 9 (PCSK9), one of the key enzymes in the process of lipid transport, is involved in the disease progression of various types of tumors. This article is to study the role of PCSK9 in the progression of hepatocellular carcinoma (HCC). Methods Immunohistochemistry was used to assess the expression of PCSK9 in tumor specimens from 105 HCC patients who underwent curative resection. Western blotting and quantitative real-time PCR were used to test the protein and mRNA expression levels in HCC cell lines. Cell Counting Kit-8 (CCK-8) and clone formation assays were performed to evaluate the proliferation ability of different kinds of cells in vitro. Flow cytometry was used to analyze cell cycle distribution and apoptosis rate. A xenograft model was established to study the effect of PCSK9 on HCC growth in vivo. TUNEL and immunofluorescence assays were used to detect cell apoptosis. Results High expression of PCSK9 in tumor tissues was related to microvascular invasion (p = 0.036) and large tumor size (p = 0.001) in HCC patients. Overall survival and disease-free survival after surgery were poor in patients with high expression of PCSK9 (p = 0.035 and p = 0.007, respectively). In vivo and in vitro experiments showed that PCSK9 promoted the growth of HCC by inhibiting cell apoptosis. A mechanistic study revealed that PCSK9 increases FASN expression, thereby inhibiting apoptosis of HCC cells via the Bax/Bcl-2/Caspase9/Caspase3 pathway. Conclusions PCSK9 expression level in HCC is an indicator of poor prognosis for patients with HCC. FASN-mediated anti-apoptosis plays an important role in PCSK9-induced HCC progression.
Collapse
|
8
|
Chemello K, García-Nafría J, Gallo A, Martín C, Lambert G, Blom D. Lipoprotein metabolism in familial hypercholesterolemia. J Lipid Res 2021; 62:100062. [PMID: 33675717 PMCID: PMC8050012 DOI: 10.1016/j.jlr.2021.100062] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/20/2021] [Accepted: 02/21/2021] [Indexed: 02/06/2023] Open
Abstract
Familial hypercholesterolemia (FH) is one of the most common genetic disorders in humans. It is an extremely atherogenic metabolic disorder characterized by lifelong elevations of circulating LDL-C levels often leading to premature cardiovascular events. In this review, we discuss the clinical phenotypes of heterozygous and homozygous FH, the genetic variants in four genes (LDLR/APOB/PCSK9/LDLRAP1) underpinning the FH phenotype as well as the most recent in vitro experimental approaches used to investigate molecular defects affecting the LDL receptor pathway. In addition, we review perturbations in the metabolism of lipoproteins other than LDL in FH, with a major focus on lipoprotein (a). Finally, we discuss the mode of action and efficacy of many of the currently approved hypocholesterolemic agents used to treat patients with FH, with a special emphasis on the treatment of phenotypically more severe forms of FH.
Collapse
Affiliation(s)
- Kévin Chemello
- Inserm UMR 1188 DéTROI, Université de La Réunion, Saint- Denis de La Réunion, France
| | - Javier García-Nafría
- Institute for Biocomputation and Physics of complex systems (BIFI), University of Zaragoza, Zaragoza, Spain; Laboratorio de Microscopías Avanzadas, University of Zaragoza, Zaragoza, Spain
| | - Antonio Gallo
- Cardiovascular Prevention Unit, Department of Endocrinology and Metabolism, Pitié-Salpêtrière University Hospital, Paris, France; Laboratoire d'imagerie Biomédicale, INSERM 1146, CNRS 7371, Sorbonne University, Paris, France
| | - Cesar Martín
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco UPV/EHU, Bilbao, Spain
| | - Gilles Lambert
- Inserm UMR 1188 DéTROI, Université de La Réunion, Saint- Denis de La Réunion, France.
| | - Dirk Blom
- Hatter Institute for Cardiovascular Research in Africa and Division of Lipidology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
9
|
Sánchez A, Bustos P, Honorato P, Burgos CF, Barriga N, Jannes CE, Sáez K, Alonso R, Asenjo S, Radojkovic C. Phenotypic characterization and predictive analysis of p.Asp47Asn LDL receptor mutation associated with Familial Hypercholesterolemia in a Chilean population. J Clin Lipidol 2021; 15:366-374.e1. [PMID: 33547002 DOI: 10.1016/j.jacl.2021.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/22/2020] [Accepted: 01/11/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND Familial hypercholesterolemia (FH) is an inherited disorder mainly caused by mutations in the LDL receptor (LDL-R) and characterized by elevation of low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease. OBJECTIVE In this study, we evaluated the clinical phenotype of the p.Asp47Asn, described as an uncertain pathogenic variant, and its effect on the structure of LDL-R and ligand interactions with apolipoproteins. METHODS 27 children and adolescents with suspected FH diagnosis were recruited from a pediatric endocrinology outpatient clinic. Blood samples were collected after 12 h fasting for lipid profile analysis. DNA sequencing was performed for six FH-related genes by Ion Torrent PGM platform and copy number variation by MLPA. For index cases, a familial cascade screening was done restricted to the same mutation found in the index case. In silico analysis were developed to evaluate the binding capacity of LDL-R to apolipoproteins B100 and E. RESULTS Lipid profile in children and adolescents demonstrated higher LDL-C levels in p.Asp47Asn carriers compared to the wild type genotype. In silico analysis predicted a reduction in the binding capacity of the ligand-binding modules LA1-2 of p.Asp47Asn LDL-R for ApoB100 and ApoE, which was not produced by local structural changes or folding defects but as a consequence of a decreased apparent affinity for both apolipoproteins. CONCLUSION The clinical phenotype and the structural effects of p.Asp47Asn LDL-R mutation suggest that this variant associates to FH.
Collapse
Affiliation(s)
- Andrea Sánchez
- Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile
| | - Paulina Bustos
- Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile
| | - Paula Honorato
- Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile
| | - Carlos F Burgos
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Natalia Barriga
- Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile
| | - Cinthia E Jannes
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School Hospital, São Paulo, Brazil
| | - Katia Sáez
- Departamento de Estadística, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile
| | - Rodrigo Alonso
- Center for Advanced Metabolic Medicine and Nutrition, Santiago de Chile. Fundación Hipercolesterolemia Familiar, Madrid, Spain
| | - Sylvia Asenjo
- Departamento de Pediatría, Facultad de Medicina, Universidad de Concepción, Concepción, Chile
| | - Claudia Radojkovic
- Departamento de Bioquímica Clínica e Inmunología, Facultad de Farmacia, Universidad de Concepción, Concepción, Chile.
| |
Collapse
|
10
|
Development of an LDL Receptor-Targeted Peptide Susceptible to Facilitate the Brain Access of Diagnostic or Therapeutic Agents. BIOLOGY 2020; 9:biology9070161. [PMID: 32664518 PMCID: PMC7407834 DOI: 10.3390/biology9070161] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/30/2020] [Accepted: 07/08/2020] [Indexed: 12/02/2022]
Abstract
Blood-brain barrier (BBB) crossing and brain penetration are really challenging for the delivery of therapeutic agents and imaging probes. The development of new crossing strategies is needed, and a wide range of approaches (invasive or not) have been proposed so far. The receptor-mediated transcytosis is an attractive mechanism, allowing the non-invasive penetration of the BBB. Among available targets, the low-density lipoprotein (LDL) receptor (LDLR) shows favorable characteristics mainly because of the lysosome-bypassed pathway of LDL delivery to the brain, allowing an intact discharge of the carried ligand to the brain targets. The phage display technology was employed to identify a dodecapeptide targeted to the extracellular domain of LDLR (ED-LDLR). This peptide was able to bind the ED-LDLR in the presence of natural ligands and dissociated at acidic pH and in the absence of calcium, in a similar manner as the LDL. In vitro, our peptide was endocytosed by endothelial cells through the caveolae-dependent pathway, proper to the LDLR route in BBB, suggesting the prevention of its lysosomal degradation. The in vivo studies performed by magnetic resonance imaging and fluorescent lifetime imaging suggested the brain penetration of this ED-LDLR-targeted peptide.
Collapse
|
11
|
Petroglou D, Kanellos I, Savopoulos C, Kaiafa G, Chrysochoou A, Skantzis P, Daios S, Hatzitolios AI, Giannoglou G. The LDL-Receptor and its Molecular Properties: From Theory to Novel Biochemical and Pharmacological Approaches in Reducing LDL-cholesterol. Curr Med Chem 2020; 27:317-333. [PMID: 29865996 DOI: 10.2174/0929867325666180604114819] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 02/25/2018] [Accepted: 05/31/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND The Low-Density Lipoprotein (LDL) Receptor (LDL-R) is a transmembrane protein playing a crucial role in effective lipid homeostasis. Various therapeutic agents have been used in the management of dyslipidemias, however, the outcome of therapeutic target is debated. OBJECTIVE The aim of this review is to summarize and fully understand the current concept regarding LDL-R and its molecular properties, metabolic pathway, factors affecting LDL-R activity and all available pharmacological interventions. Additionally, non-lipid related properties of LDL-R are also referred. METHODS Literature from the PubMed database was extracted to identify papers between 1984 to 2017 regarding LDL-R and therapeutic agents on dyslipidemia management. RESULTS We analyzed basic data regarding agents associated with LDL-R (Sterol Regulating Element-Binding Proteins - SREBPs, Protein ARH, IDOL, Thyroid Hormones, Haematologic Disorders, Protein convertase subtilisin kexintype 9 - PCSK-9, ApoC-III) as well as non-lipid related properties of LDL-R, while all relevant (common and novel) pharmacological interventions (statins, fibrates, cholesterol absorption inhibitors, bile acid sequestrants and PCSK- 9) are also referred. CONCLUSION LDL-R and its molecular properties are involved in lipid homeostasis, so potentially sets the therapeutic goals in cardiovascular patients, which is usually debated. Further research is needed in order to fully understand its properties, as well as to find the potential pharmacological interventions that could be beneficial in cholesterol homeostasis and various morbidities in order to reach the most appropriate therapeutic goal.
Collapse
Affiliation(s)
- Dimitrios Petroglou
- 1st Department of Cardiology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Ilias Kanellos
- 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Christos Savopoulos
- 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgia Kaiafa
- 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Anastasios Chrysochoou
- 1st Department of Cardiology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Panagiotis Skantzis
- 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Stylianos Daios
- 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Apostolos I Hatzitolios
- 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgios Giannoglou
- 1st Department of Cardiology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| |
Collapse
|
12
|
Mutation type classification and pathogenicity assignment of sixteen missense variants located in the EGF-precursor homology domain of the LDLR. Sci Rep 2020; 10:1727. [PMID: 32015373 PMCID: PMC6997160 DOI: 10.1038/s41598-020-58734-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 01/21/2020] [Indexed: 12/21/2022] Open
Abstract
The primary genetic cause of familial hypercholesterolemia (FH) is related to mutations in the LDLR gene encoding the Low-density Lipoprotein Receptor. LDLR structure is organized in 5 different domains, including an EGF-precursor homology domain that plays a pivotal role in lipoprotein release and receptor recycling. Mutations in this domain constitute 51.7% of the total missense variants described in LDLR. The aim of the present work was to analyse how clinically significant variants in the EGF-precursor homology domain impact LDLR. The activity of sixteen LDLR variants was functionally characterized by determining LDLR expression by Western blot and LDLR expression, LDL binding capacity and uptake, and LDLR recycling activity by flow cytometry in transfected CHO-ldlA7 cells. Of the analysed variants, we found six non-pathogenic LDLR variants and ten pathogenic variants distributed as follow: three class 3 variants; four class 2 variants; and three class 5 variants. These results can be incorporated into clinical management of patients by helping guide the appropriate level of treatment intensity depending on the extent of loss of LDLR activity. This data can also contribute to cascade-screening for pathogenic FH variants.
Collapse
|
13
|
Keiser KJ, Barlowe C. Molecular dissection of the Erv41-Erv46 retrograde receptor reveals a conserved cysteine-rich region in Erv46 required for retrieval activity. Mol Biol Cell 2019; 31:209-220. [PMID: 31825724 PMCID: PMC7001479 DOI: 10.1091/mbc.e19-08-0484] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Erv41-Erv46 complex is a conserved retrograde cargo receptor that retrieves ER resident proteins from Golgi compartments in a pH-dependent manner. Here we functionally dissect the Erv46 subunit and define an approximately 60 residue cysteine-rich region that is unique to the Erv46 family of proteins. This cysteine-rich region contains two vicinal cysteine pairs in CXXC and CCXXC configurations that are each required for retrieval activity in cells. Mutation of the individual cysteine residues produced stable Erv46 proteins that were partially reduced and form mixed-disulfide species on nonreducing gels. Conserved hydrophobic amino acids within the cysteine-rich region of Erv46 were also required for retrieval function in cells. In vitro binding experiments showed that this hydrophobic patch is required for direct cargo binding. Surprisingly, the Erv46 cysteine mutants continued to bind cargo in cell-free assays and produced an increased level of Erv46-cargo complexes in cell extracts suggesting that disulfide linkages in the cysteine-rich region perform a role in releasing bound cargo. On the basis of these findings, we propose that both pH and redox environments regulate cargo binding to a hydrophobic site within the cysteine-rich region of Erv46.
Collapse
Affiliation(s)
- Kristofer J Keiser
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Charles Barlowe
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
14
|
Benito-Vicente A, Uribe KB, Siddiqi H, Jebari S, Galicia-Garcia U, Larrea-Sebal A, Cenarro A, Stef M, Ostolaza H, Civeira F, Palacios L, Martin C. Replacement of cysteine at position 46 in the first cysteine-rich repeat of the LDL receptor impairs apolipoprotein recognition. PLoS One 2018; 13:e0204771. [PMID: 30332439 PMCID: PMC6192581 DOI: 10.1371/journal.pone.0204771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 09/13/2018] [Indexed: 11/18/2022] Open
Abstract
Background and aims Pathogenic mutations in the Low Density Lipoprotein Receptor gene (LDLR) cause Familial Hypercholesterolemia (FH), one of the most common genetic disorders with a prevalence as high as 1 in 200 in some populations. FH is an autosomal dominant disorder of lipoprotein metabolism characterized by high blood cholesterol levels, deposits of cholesterol in peripheral tissues such as tendon xanthomas and accelerated atherosclerosis. To date, 2500 LDLR variants have been identified in the LDLR gene; however, only a minority of them have been experimentally characterized and proven to be pathogenic. Here we investigated the role of Cys46 located in the first repeat of the LDL receptor binding domain in recognition of apolipoproteins. Methods Activity of the p.(Cys46Gly) LDLR variant was assessed by immunoblotting and flow cytometry in CHO-ldlA7 expressing the receptor variant. Affinity of p.(Cys46Gly) for LDL and VLDL was determined by solid-phase immunoassays and in silico analysis was used to predict mutation effects. Results and conclusion Functional characterization of p.(Cys46Gly) LDLR variant showed impaired LDL and VLDL binding and uptake activity. Consistent with this, solid-phase immunoassays showed the p.(Cys46Gly) LDLR variant has decreased binding affinity for apolipoproteins. These results indicate the important role of Cys46 in LDL receptor activity and highlight the role of LR1 in LDLr activity modulation. This study reinforces the significance of in vitro functional characterization of LDL receptor activity in developing an accurate approach to FH genetic diagnosis. This is of particular importance because it enables clinicians to tailor personalized treatments for patients’ mutation profile.
Collapse
Affiliation(s)
- A. Benito-Vicente
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - K. B. Uribe
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - H. Siddiqi
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - S. Jebari
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - U. Galicia-Garcia
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - A. Larrea-Sebal
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - A. Cenarro
- Unidad de Lípidos and Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - M. Stef
- Progenika Biopharma, a Grifols Company, Derio, Spain
| | - H. Ostolaza
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - F. Civeira
- Unidad de Lípidos and Laboratorio de Investigación Molecular, Hospital Universitario Miguel Servet, Instituto Aragonés de Ciencias de la Salud (IACS), Zaragoza, Spain
| | - L. Palacios
- Progenika Biopharma, a Grifols Company, Derio, Spain
| | - C. Martin
- Instituto Biofisika (UPV/EHU, CSIC) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
- * E-mail:
| |
Collapse
|
15
|
Coakley JC. Lipids in Children and Links to Adult Vascular Disease. Clin Biochem Rev 2018; 39:65-76. [PMID: 30828113 PMCID: PMC6370283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Atherosclerosis often begins in childhood or adolescence. Post-mortem studies in children have shown the presence of coronary atheroma, and there are hereditary conditions associated with hyperlipidaemia in childhood which lead to premature cardiovascular disease. Detection of hyperlipidaemia early in life can be crucial in the prevention of premature death from atherosclerosis. The circulating lipoproteins are in a constant state of flux, with passage of apolipoproteins and lipids between the various particles. Genetic variants of apolipoproteins can cause both hypercholesterolaemia and hypertriglyceridaemia. Elevated concentrations of lipoprotein(a) predispose to coronary artery disease. Another important molecule in lipid metabolism, proprotein convertase subtilisin/kexin type 9 (PCSK9), plays a crucial role in the removal of low-density lipoprotein (LDL) receptors. Reference intervals for the various lipid subfractions are now available for children, and there are guidelines regarding when to take action regarding paediatric hyperlipidaemia. The most important genetic condition in children which may lead to premature death from coronary heart disease is familial hypercholesterolaemia (FH). FH is best diagnosed and treated early in life. Most cases are due to defects in the LDL receptor. Pharmacotherapy for FH usually involves the statin group of drugs, although newer medications are now available, especially for the treatment of homozygous FH. Statin therapy has been demonstrated to be successful in preventing cardiac events in FH. Secondary dyslipidaemia in childhood can be associated with numerous diseases including diabetes, lifestyle disorders such as obesity, and drugs. Treatment of the underlying condition usually resolves the hyperlipidaemia.
Collapse
Affiliation(s)
- John C Coakley
- Retired Head of Biochemistry Department, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia
| |
Collapse
|
16
|
Wang S, Mao Y, Narimatsu Y, Ye Z, Tian W, Goth CK, Lira-Navarrete E, Pedersen NB, Benito-Vicente A, Martin C, Uribe KB, Hurtado-Guerrero R, Christoffersen C, Seidah NG, Nielsen R, Christensen EI, Hansen L, Bennett EP, Vakhrushev SY, Schjoldager KT, Clausen H. Site-specific O-glycosylation of members of the low-density lipoprotein receptor superfamily enhances ligand interactions. J Biol Chem 2018; 293:7408-7422. [PMID: 29559555 DOI: 10.1074/jbc.m117.817981] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 02/27/2018] [Indexed: 11/06/2022] Open
Abstract
The low-density lipoprotein receptor (LDLR) and related receptors are important for the transport of diverse biomolecules across cell membranes and barriers. Their functions are especially relevant for cholesterol homeostasis and diseases, including neurodegenerative and kidney disorders. Members of the LDLR-related protein family share LDLR class A (LA) repeats providing binding properties for lipoproteins and other biomolecules. We previously demonstrated that short linker regions between these LA repeats contain conserved O-glycan sites. Moreover, we found that O-glycan modifications at these sites are selectively controlled by the GalNAc-transferase isoform, GalNAc-T11. However, the effects of GalNAc-T11-mediated O-glycosylation on LDLR and related receptor localization and function are unknown. Here, we characterized O-glycosylation of LDLR-related proteins and identified conserved O-glycosylation sites in the LA linker regions of VLDLR, LRP1, and LRP2 (Megalin) from both cell lines and rat organs. Using a panel of gene-edited isogenic cell line models, we demonstrate that GalNAc-T11-mediated LDLR and VLDLR O-glycosylation is not required for transport and cell-surface expression and stability of these receptors but markedly enhances LDL and VLDL binding and uptake. Direct ELISA-based binding assays with truncated LDLR constructs revealed that O-glycosylation increased affinity for LDL by ∼5-fold. The molecular basis for this observation is currently unknown, but these findings open up new avenues for exploring the roles of LDLR-related proteins in disease.
Collapse
Affiliation(s)
- Shengjun Wang
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Yang Mao
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Yoshiki Narimatsu
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Zilu Ye
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Weihua Tian
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Christoffer K Goth
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Erandi Lira-Navarrete
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Nis B Pedersen
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Asier Benito-Vicente
- Biofisika Institute, Centro Superior de Investigaciones Cientificas (CSIC), Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), and Departamento de Bioquimica, Universidad del Pais Vasco, 48080 Bilbao, Spain
| | - Cesar Martin
- Biofisika Institute, Centro Superior de Investigaciones Cientificas (CSIC), Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), and Departamento de Bioquimica, Universidad del Pais Vasco, 48080 Bilbao, Spain
| | - Kepa B Uribe
- Biofisika Institute, Centro Superior de Investigaciones Cientificas (CSIC), Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), and Departamento de Bioquimica, Universidad del Pais Vasco, 48080 Bilbao, Spain
| | - Ramon Hurtado-Guerrero
- The Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-Instituto de Química Física Rocasolano (IQFR), CSIC Joint Unit, Mariano Esquillor s/n, Campus Rio Ebro, 50009 Zaragoza, Spain
| | - Christina Christoffersen
- Department of Clinical Biochemistry, Rigshospitalet and Department of Biomedical Sciences, University of Copenhagen, Copenhagen 2100, Denmark
| | - Nabil G Seidah
- Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Rikke Nielsen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus, Denmark
| | | | - Lars Hansen
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Eric P Bennett
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Sergey Y Vakhrushev
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Katrine T Schjoldager
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
| | - Henrik Clausen
- Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
| |
Collapse
|
17
|
Chang Y, Robidoux J. Dyslipidemia management update. Curr Opin Pharmacol 2017; 33:47-55. [DOI: 10.1016/j.coph.2017.04.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 03/27/2017] [Accepted: 04/19/2017] [Indexed: 12/11/2022]
|
18
|
Zhang PY. PCSK9 as a therapeutic target for cardiovascular disease. Exp Ther Med 2017; 13:810-814. [PMID: 28450903 PMCID: PMC5403434 DOI: 10.3892/etm.2017.4055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 01/12/2017] [Indexed: 01/14/2023] Open
Abstract
It is well recognized that the elevated plasma level of low-density lipoprotein-cholesterol (LDL-C) is a major risk factor for atherosclerosis and cardiovascular disease (CVD). Deposition of pro-atherogenic LDL-C, on the intima of arterial wall, contributes to plaque formation and atherosclerosis, which further leads to lowered blood flow to vital organs and increased risk of CVD. The most commonly used statin therapy is effective in reducing dyslipidemia and preventing cardiovascular events only in about half of the patient population. However, in patients with familial hypercholesterolemia, these drugs were not effective to meet the required goals of lower LDL-C, and to reduce the CVD risk. Furthermore, many patients even develop intolerability to statins and resistance. The identification of pro-protein convertase subtilisin/kexin type 9 (PCSK9) and the association of PCSK9 mutations with familial hypercholesterolemia led to the identification of PCSK9 as a new therapeutic target for lowering LDL-C and dyslipidemia-associated CVD. PCSK9 is found to promote the degradation of LDL-receptor (LDLR), thus rendering it unavailable for recycling to hepatocyte plasma membrane, leading to elevated levels of circulating LDL-C, as it cannot be taken up into cells. While gain-of-function mutations aggravate the degradation of LDLR as in familial hypercholesterolemia whereas loss of function mutations reduce the ability of PCSK9 to promote the degradation of LDLR and thus lower the plasma level of LDL-C and dyslipidemia. Monoclonal antibodies against PCSK9 are currently being tested in clinical trials and are found to be efficacious in countering the activity of PCSK9 and thus control the plasma LDL-C and triglycerides even in statin non-responsive patients and protect against dyslipidemia-related CVD.
Collapse
Affiliation(s)
- Pei-Ying Zhang
- Department of Cardiology, Xuzhou Central Hospital, The Affiliated Xuzhou Hospital of Medical College of Southeast University, Xuzhou, Jiangsu 221009, P.R. China
| |
Collapse
|
19
|
Dong H, Zhao Z, LeBrun DG, Michaely P. Identification of roles for H264, H306, H439, and H635 in acid-dependent lipoprotein release by the LDL receptor. J Lipid Res 2016; 58:364-374. [PMID: 27895090 DOI: 10.1194/jlr.m070938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/19/2016] [Indexed: 11/20/2022] Open
Abstract
Lipoproteins internalized by the LDL receptor (LDLR) are released from this receptor in endosomes through a process that involves acid-dependent conformational changes in the receptor ectodomain. How acidic pH promotes this release process is not well understood. Here, we assessed roles for six histidine residues for which either genetic or structural data suggested a possible role in the acid-responsiveness of the LDLR. Using assays that measured conformational change, acid-dependent lipoprotein release, LDLR recycling, and net lipoprotein uptake, we show that H635 plays important roles in acid-dependent conformational change and lipoprotein release, while H264, H306, and H439 play ancillary roles in the response of the LDLR to acidic pH.
Collapse
Affiliation(s)
- Hongyun Dong
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Zhenze Zhao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Drake G LeBrun
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Peter Michaely
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| |
Collapse
|
20
|
Abstract
There are several established lipid-modifying agents, including statins, fibrates, niacin, and ezetimibe, that have been shown in randomized clinical outcome trials to reduce the risk of having an atherosclerotic cardiovascular event. However, in many people, the risk of having an event remains unacceptably high despite treatment with these established agents. This has stimulated the search for new therapies designed to reduce residual cardiovascular risk. New approaches that target atherogenic lipoproteins include: 1) inhibition of proprotein convertase subtilisin/kexin type 9 to increase removal of atherogenic lipoproteins from plasma; 2) inhibition of the synthesis of apolipoprotein (apo) B, the main protein component of atherogenic lipoproteins; 3) inhibition of microsomal triglyceride transfer protein to block the formation of atherogenic lipoproteins; 4) inhibition of adenosine triphosphate citrate lyase to inhibit the synthesis of cholesterol; 5) inhibition of the synthesis of lipoprotein(a), a factor known to cause atherosclerosis; 6) inhibition of apoC-III to reduce triglyceride-rich lipoproteins and to enhance high-density lipoprotein (HDL) functionality; and 7) inhibition of cholesteryl ester transfer protein, which not only reduces the concentration of atherogenic lipoproteins but also increases the level and function of the potentially antiatherogenic HDL fraction. Other new therapies that specifically target HDLs include infusions of reconstituted HDLs, HDL delipidation, and infusions of apoA-I mimetic peptides that mimic some of the functions of HDLs. This review describes the scientific basis and rationale for developing these new therapies and provides a brief summary of established therapies.
Collapse
Affiliation(s)
- Philip J Barter
- School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Kerry-Anne Rye
- School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| |
Collapse
|
21
|
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] [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.
Collapse
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,
| |
Collapse
|
22
|
Angarica VE, Orozco M, Sancho J. Exploring the complete mutational space of the LDL receptor LA5 domain using molecular dynamics: linking SNPs with disease phenotypes in familial hypercholesterolemia. Hum Mol Genet 2016; 25:1233-46. [PMID: 26755827 PMCID: PMC4764198 DOI: 10.1093/hmg/ddw004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/05/2016] [Indexed: 11/18/2022] Open
Abstract
Familial hypercholesterolemia (FH), a genetic disorder with a prevalence of 0.2%, represents a high-risk factor to develop cardiovascular and cerebrovascular diseases. The majority and most severe FH cases are associated to mutations in the receptor for low-density lipoproteins receptor (LDL-r), but the molecular basis explaining the connection between mutation and phenotype is often unknown, which hinders early diagnosis and treatment of the disease. We have used atomistic simulations to explore the complete SNP mutational space (227 mutants) of the LA5 repeat, the key domain for interacting with LDL that is coded in the exon concentrating the highest number of mutations. Four clusters of mutants of different stability have been identified. The majority of the 50 FH known mutations (33) appear distributed in the unstable clusters, i.e. loss of conformational stability explains two-third of FH phenotypes. However, one-third of FH phenotypes (17 mutations) do not destabilize the LR5 repeat. Combining our simulations with available structural data from different laboratories, we have defined a consensus-binding site for the interaction of the LA5 repeat with LDL-r partner proteins and have found that most (16) of the 17 stable FH mutations occur at binding site residues. Thus, LA5-associated FH arises from mutations that cause either the loss of stability or a decrease in domain's-binding affinity. Based on this finding, we propose the likely phenotype of each possible SNP in the LA5 repeat and outline a procedure to make a full computational diagnosis for FH.
Collapse
Affiliation(s)
- Vladimir Espinosa Angarica
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain, Biocomputation and Complex Systems Physics Institute (BIFI), Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Mariano Esquillor, Edificio I + D, 50018 Zaragoza, Spain
| | - Modesto Orozco
- Institut de Recerca Biomèdica (IRB Barcelona), Baldiri Reixac 10-12, 08028 Barcelona, Spain, Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Diagonal 643, 08028 Barcelona, Spain, Joint BSC-CRG-IRB Program in Computational Biology, Baldiri Reixac 10-12, 08028 Barcelona, Spain, and
| | - Javier Sancho
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain, Biocomputation and Complex Systems Physics Institute (BIFI), Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Mariano Esquillor, Edificio I + D, 50018 Zaragoza, Spain, Aragon Institute for Health Research (IIS Aragón), Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain
| |
Collapse
|
23
|
Martínez-Oliván J, Arias-Moreno X, Hurtado-Guerrero R, Carrodeguas JA, Miguel-Romero L, Marina A, Bruscolini P, Sancho J. The closed conformation of the LDL receptor is destabilized by the low Ca(++) concentration but favored by the high Mg(++) concentration in the endosome. FEBS Lett 2015; 589:3534-40. [PMID: 26526611 DOI: 10.1016/j.febslet.2015.10.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/06/2015] [Accepted: 10/14/2015] [Indexed: 10/22/2022]
Abstract
The LDL receptor (LDLR) internalizes LDL and VLDL particles. In the endosomes, it adopts a closed conformation important for recycling, by interaction of two modules of the ligand binding domain (LR4-5) and a β-propeller motif. Here, we investigate by SPR the interactions between those two modules and the β-propeller. Our results indicate that the two modules cooperate to bind the β-propeller. The binding is favored by low pH and by high [Ca(++)]. Our data show that Mg(++), at high concentration in the endosome, favors the formation of the closed conformation by replacing the structuring effect of Ca(++) in LR5. We propose a sequential model of LDL release where formation of the close conformation follows LDL release.
Collapse
Affiliation(s)
- Juan Martínez-Oliván
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain; Aragon Health Research Institute (IIS Aragón), Universidad de Zaragoza, Zaragoza, Spain
| | - Xabier Arias-Moreno
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - Ramón Hurtado-Guerrero
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Zaragoza, Spain; Aragon Health Research Institute (IIS Aragón), Universidad de Zaragoza, Zaragoza, Spain; Fundación ARAID, Diputación General de Aragón, Spain
| | - José Alberto Carrodeguas
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain; Aragon Health Research Institute (IIS Aragón), Universidad de Zaragoza, Zaragoza, Spain
| | - Laura Miguel-Romero
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (IBV-CSIC), Spain
| | - Alberto Marina
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (IBV-CSIC), Spain
| | - Pierpaolo Bruscolini
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Zaragoza, Spain
| | - Javier Sancho
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain; Aragon Health Research Institute (IIS Aragón), Universidad de Zaragoza, Zaragoza, Spain.
| |
Collapse
|
24
|
Barter PJ, Tabet F, Rye KA. Reduction in PCSK9 levels induced by anacetrapib: an off-target effect? J Lipid Res 2015; 56:2045-7. [PMID: 26378095 DOI: 10.1194/jlr.c063768] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Philip J Barter
- School of Medical Sciences, University of New South Wales Australia, Sydney, Australia
| | - Fatiha Tabet
- School of Medical Sciences, University of New South Wales Australia, Sydney, Australia
| | - Kerry-Anne Rye
- School of Medical Sciences, University of New South Wales Australia, Sydney, Australia
| |
Collapse
|
25
|
Yilmaz O, Prat F, Ibañez AJ, Amano H, Koksoy S, Sullivan CV. Estrogen-induced yolk precursors in European sea bass, Dicentrarchus labrax: Status and perspectives on multiplicity and functioning of vitellogenins. Gen Comp Endocrinol 2015; 221:16-22. [PMID: 25637672 DOI: 10.1016/j.ygcen.2015.01.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 12/30/2014] [Accepted: 01/10/2015] [Indexed: 01/22/2023]
Abstract
The estrogen-inducible egg yolk precursor, vitellogenin, of the European sea bass (Dicentrarchus labrax) has received considerable scientific attention by virtue of its central importance in determination of oocyte growth and egg quality in this important aquaculture species. However, the multiplicity of vitellogenins in the sea bass has only recently been examined. Recent cloning and homology analyses have revealed that the sea bass possesses the three forms of vitellogenin, VtgAa, VtgAb and VtgC, reported to occur in some other highly evolved teleosts. Progress has been made in assessing the relative abundance and special structural features of the three Vtgs and their likely roles in oocyte maturation and embryonic nutrition. This report discusses these findings in the context of our prior knowledge of vitellogenesis in this species and of the latest advances in our understanding of the evolution and function of multiple Vtgs in acanthomorph fishes.
Collapse
Affiliation(s)
- Ozlem Yilmaz
- Akdeniz University, Fisheries Faculty, Antalya 07070, Turkey; National Institute of Agrinomic Research, Campus de Beaulieu, 35000 Rennes Cedex, France(1).
| | - Francisco Prat
- Instituto de Acuicultura de Torre de la Sal (CSIC), 12595 Castellón, Spain; Instituto de Ciencias Marinas de Andalucía (CSIC), 11510 Cádiz, Spain(1)
| | - Antonio José Ibañez
- Instituto de Acuicultura de Torre de la Sal (CSIC), 12595 Castellón, Spain; Electron and Confocal Microscopy Service, University of Valencia, 46100 Valencia, Spain(1)
| | - Haruna Amano
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa 252-0373, Japan
| | - Sadi Koksoy
- Faculty of Medicine, Akdeniz University, Antalya 07070, Turkey
| | - Craig V Sullivan
- Department of Biology, North Carolina State University, Raleigh, NC 27695-7617, USA; Carolina AquaGyn, P.O. Box 12914, Raleigh, NC 27605, USA(1)
| |
Collapse
|
26
|
Martínez-Oliván J, Fraga H, Arias-Moreno X, Ventura S, Sancho J. Intradomain Confinement of Disulfides in the Folding of Two Consecutive Modules of the LDL Receptor. PLoS One 2015; 10:e0132141. [PMID: 26168158 PMCID: PMC4500599 DOI: 10.1371/journal.pone.0132141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 06/10/2015] [Indexed: 01/26/2023] Open
Abstract
The LDL receptor internalizes circulating LDL and VLDL particles for degradation. Its extracellular binding domain contains ten (seven LA and three EGF) cysteine-rich modules, each bearing three disulfide bonds. Despite the enormous number of disulfide combinations possible, LDLR oxidative folding leads to a single native species with 30 unique intradomain disulfides. Previous folding studies of the LDLR have shown that non native disulfides are initially formed that lead to compact species. Accordingly, the folding of the LDLR has been described as a "coordinated nonvectorial” reaction, and it has been proposed that early compaction funnels the reaction toward the native structure. Here we analyze the oxidative folding of LA4 and LA5, the modules critical for ApoE binding, isolated and in the LA45 tandem. Compared to LA5, LA4 folding is slow and inefficient, resembling that of LA5 disease-linked mutants. Without Ca++, it leads to a mixture of many two-disulfide scrambled species and, with Ca++, to the native form plus two three-disulfide intermediates. The folding of the LA45 tandem seems to recapitulate that of the individual repeats. Importantly, although the folding of the LA45 tandem takes place through formation of scrambled isomers, no interdomain disulfides are detected, i.e. the two adjacent modules fold independently without the assistance of interdomain covalent interactions. Reduction of incredibly large disulfide combinatorial spaces, such as that in the LDLR, by intradomain confinement of disulfide bond formation might be also essential for the efficient folding of other homologous disulfide-rich receptors.
Collapse
Affiliation(s)
- Juan Martínez-Oliván
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR(CSIC), Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - Hugo Fraga
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Departamento de Bioquimica, Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | - Xabier Arias-Moreno
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR(CSIC), Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - Salvador Ventura
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Bellaterra, Spain
- * E-mail: (SV); (JS)
| | - Javier Sancho
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Unit BIFI-IQFR(CSIC), Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
- * E-mail: (SV); (JS)
| |
Collapse
|
27
|
Vera A, Recabal A, Saldivia N, Stanic K, Torrejón M, Montecinos H, Caprile T. Interaction between SCO-spondin and low density lipoproteins from embryonic cerebrospinal fluid modulates their roles in early neurogenesis. Front Neuroanat 2015; 9:72. [PMID: 26074785 PMCID: PMC4446542 DOI: 10.3389/fnana.2015.00072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/14/2015] [Indexed: 01/20/2023] Open
Abstract
During early stages of development, encephalic vesicles are composed by a layer of neuroepithelial cells surrounding a central cavity filled with embryonic cerebrospinal fluid (eCSF). This fluid contains several morphogens that regulate proliferation and differentiation of neuroepithelial cells. One of these neurogenic factors is SCO-spondin, a giant protein secreted to the eCSF from early stages of development. Inhibition of this protein in vivo or in vitro drastically decreases the neurodifferentiation process. Other important neurogenic factors of the eCSF are low density lipoproteins (LDL), the depletion of which generates a 60% decrease in mesencephalic explant neurodifferentiation. The presence of several LDL receptor class A (LDLrA) domains (responsible for LDL binding in other proteins) in the SCO-spondin sequence suggests a possible interaction between both molecules. This possibility was analyzed using three different experimental approaches: (1) Bioinformatics analyses of the SCO-spondin region, that contains eight LDLrA domains in tandem, and of comparisons with the LDL receptor consensus sequence; (2) Analysis of the physical interactions of both molecules through immunohistochemical colocalization in embryonic chick brains and through the immunoprecipitation of LDL with anti-SCO-spondin antibodies; and (3) Analysis of functional interactions during the neurodifferentiation process when these molecules were added to a culture medium of mesencephalic explants. The results revealed that LDL and SCO-spondin interact to form a complex that diminishes the neurogenic capacities that both molecules have separately. Our work suggests that the eCSF is an active signaling center with a complex regulation system that allows for correct brain development.
Collapse
Affiliation(s)
- América Vera
- Department of Cell Biology, Faculty of Biological Sciences, University of Concepción Concepción, Chile
| | - Antonia Recabal
- Department of Cell Biology, Faculty of Biological Sciences, University of Concepción Concepción, Chile
| | - Natalia Saldivia
- Department of Cell Biology, Faculty of Biological Sciences, University of Concepción Concepción, Chile
| | - Karen Stanic
- Department of Cell Biology, Faculty of Biological Sciences, University of Concepción Concepción, Chile
| | - Marcela Torrejón
- Faculty of Biological Sciences, Department of Biochemistry and Molecular Biology, University of Concepción Concepción, Chile
| | - Hernán Montecinos
- Department of Cell Biology, Faculty of Biological Sciences, University of Concepción Concepción, Chile
| | - Teresa Caprile
- Department of Cell Biology, Faculty of Biological Sciences, University of Concepción Concepción, Chile
| |
Collapse
|
28
|
Mehmedbasic A, Christensen SK, Nilsson J, Rüetschi U, Gustafsen C, Poulsen ASA, Rasmussen RW, Fjorback AN, Larson G, Andersen OM. SorLA complement-type repeat domains protect the amyloid precursor protein against processing. J Biol Chem 2014; 290:3359-76. [PMID: 25525276 DOI: 10.1074/jbc.m114.619940] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SorLA is a neuronal sorting receptor that is genetically associated with Alzheimer disease. SorLA interacts directly with the amyloid precursor protein (APP) and affects the processing of the precursor, leading to a decreased generation of the amyloid-β peptide. The SorLA complement-type repeat (CR) domains associate in vitro with APP, but the precise molecular determinants of SorLA·APP complex formation and the mechanisms responsible for the effect of binding on APP processing have not yet been elucidated. Here, we have generated protein expression constructs for SorLA devoid of the 11 CR-domains and for two SorLA mutants harboring substitutions of the fingerprint residues in the central CR-domains. We generated SH-SY5Y cell lines that stably express these SorLA variants to study the binding and processing of APP using co-immunoprecipitation and Western blotting/ELISAs, respectively. We found that the SorLA CR-cluster is essential for interaction with APP and that deletion of the CR-cluster abolishes the protection against APP processing. Mutation of identified fingerprint residues in the SorLA CR-domains leads to changes in the O-linked glycosylation of APP when expressed in SH-SY5Y cells. Our results provide novel information on the mechanisms behind the influence of SorLA activity on APP metabolism by controlling post-translational glycosylation in the Golgi, suggesting new strategies against amyloidogenesis in Alzheimer disease.
Collapse
Affiliation(s)
- Arnela Mehmedbasic
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| | - Sofie K Christensen
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| | - Jonas Nilsson
- the Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden
| | - Ulla Rüetschi
- the Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden
| | - Camilla Gustafsen
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| | - Annemarie Svane Aavild Poulsen
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| | - Rikke W Rasmussen
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| | - Anja N Fjorback
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| | - Göran Larson
- the Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, University of Gothenburg, SE-413 45 Gothenburg, Sweden
| | - Olav M Andersen
- From the Lundbeck Foundation Research Center MIND, Danish Research Institute of Translational Neuroscience Nordic-EMBL Partnership (DANDRITE), Department of Biomedicine, Aarhus University, Ole Worms Allé 3, DK-8000 AarhusC, Denmark and
| |
Collapse
|
29
|
Abstract
Since the discovery of proprotein convertase subtilisin kexin 9 (PCSK9) in 2003, this PC has attracted a lot of attention from the scientific community and pharmaceutical companies. Secreted into the plasma by the liver, the proteinase K-like serine protease PCSK9 binds the low-density lipoprotein (LDL) receptor at the surface of hepatocytes, thereby preventing its recycling and enhancing its degradation in endosomes/lysosomes, resulting in reduced LDL-cholesterol clearance. Surprisingly, in a nonenzymatic fashion, PCSK9 enhances the intracellular degradation of all its target proteins. Rare gain-of-function PCSK9 variants lead to higher levels of LDL-cholesterol and increased risk of cardiovascular disease; more common loss-of-function PCSK9 variants are associated with reductions in both LDL-cholesterol and risk of cardiovascular disease. It took 9 years to elaborate powerful new PCSK9-based therapeutic approaches to reduce circulating levels of LDL-cholesterol. Presently, PCSK9 monoclonal antibodies that inhibit its function on the LDL receptor are evaluated in phase III clinical trials. This review will address the biochemical, genetic, and clinical aspects associated with PCSK9's biology and pathophysiology in cells, rodent and human, with emphasis on the clinical benefits of silencing the expression/activity of PCSK9 as a new modality in the treatment of hypercholesterolemia and associated pathologies.
Collapse
Affiliation(s)
- Nabil G Seidah
- From the Laboratories of Biochemical Neuroendocrinology (N.G.S., Z.A.) and Functional Endoproteolysis (M.C., M.M.), Institut de Recherches Cliniques de Montréal, affiliated to the Université de Montréal, Montréal, Quebec, Canada; and Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.C., M.M.)
| | | | | | | |
Collapse
|
30
|
Martínez-Oliván J, Rozado-Aguirre Z, Arias-Moreno X, Angarica VE, Velázquez-Campoy A, Sancho J. Low-density lipoprotein receptor is a calcium/magnesium sensor - role of LR4 and LR5 ion interaction kinetics in low-density lipoprotein release in the endosome. FEBS J 2014; 281:2638-58. [PMID: 24720672 DOI: 10.1111/febs.12811] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/25/2014] [Accepted: 04/08/2014] [Indexed: 11/28/2022]
Abstract
The low-density lipoprotein receptor (LDLR) captures circulating lipoproteins and delivers them in the endosome for degradation. Its function is essential for cholesterol homeostasis, and mutations in the LDLR are the major cause of familiar hypercholesterolemia. The release of LDL is usually attributed to endosome acidification. As the pH drops, the affinity of the LDLR/LDL complex is reduced, whereas the strength of a self-complex formed between two domains of the receptor (i.e. the LDL binding domain and the β-propeller domain) increases. However, an alternative model states that, as a consequence of a drop in both pH and Ca(2+) concentration, the LDLR binding domain is destabilized in the endosome, which weakens the LDLR/LDL complex, thus liberating the LDL particles. In the present study, we test a key underlying assumption of the second model, namely that the lipoprotein binding repeats of the receptor (specifically repeats 4 and 5, LR4 and LR5) rapidly sense endosomal changes in Ca(2+) concentration. Our kinetic and thermodynamic analysis of Ca(2+) and Mg(2+) binding to LR4 and LR5, as well as to the tandem of the two (LR4-5), shows that both repeats spontaneously release Ca(2+) in a time scale much shorter than endosomal delivery of LDL, thus acting as Ca(2+) sensors that become unfolded under endosomal conditions. Our analysis additionally explains the lower Ca(2+) affinity of repeat LR4, compared to LR5, as arising from a very slow Ca(2+) binding reaction in the former, most likely related to the lower conformational stability of apolipoprotein LR4, compared to apolipoprotein LR5, as determined from thermal unfolding experiments and molecular dynamics simulations.
Collapse
Affiliation(s)
- Juan Martínez-Oliván
- Biocomputation and Complex Systems Physics Institute (BIFI) - Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Spain
| | | | | | | | | | | |
Collapse
|
31
|
Martínez-Oliván J, Arias-Moreno X, Velazquez-Campoy A, Millet O, Sancho J. LDL receptor/lipoprotein recognition: endosomal weakening of ApoB and ApoE binding to the convex face of the LR5 repeat. FEBS J 2014; 281:1534-46. [DOI: 10.1111/febs.12721] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 01/02/2014] [Accepted: 01/13/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Juan Martínez-Oliván
- Biocomputation and Complex Systems Physics Institute (BIFI). BIFI-Instituto de Química Física Rocasolano (Consejo Superior de Investigaciones Científicas) Joint Unit; Universidad de Zaragoza; Spain
- Departamento de Bioquímica y Biología Molecular y Celular; Universidad de Zaragoza; Spain
| | - Xabier Arias-Moreno
- Biocomputation and Complex Systems Physics Institute (BIFI). BIFI-Instituto de Química Física Rocasolano (Consejo Superior de Investigaciones Científicas) Joint Unit; Universidad de Zaragoza; Spain
- Departamento de Bioquímica y Biología Molecular y Celular; Universidad de Zaragoza; Spain
| | - Adrián Velazquez-Campoy
- Biocomputation and Complex Systems Physics Institute (BIFI). BIFI-Instituto de Química Física Rocasolano (Consejo Superior de Investigaciones Científicas) Joint Unit; Universidad de Zaragoza; Spain
- Departamento de Bioquímica y Biología Molecular y Celular; Universidad de Zaragoza; Spain
- Fundación Agencia Aragonesa para la Investigación y Desarrollo; Diputación General de Aragón; Spain
| | - Oscar Millet
- Structural Biology Unit; CIC bioGUNE; Derio Spain
| | - Javier Sancho
- Biocomputation and Complex Systems Physics Institute (BIFI). BIFI-Instituto de Química Física Rocasolano (Consejo Superior de Investigaciones Científicas) Joint Unit; Universidad de Zaragoza; Spain
- Departamento de Bioquímica y Biología Molecular y Celular; Universidad de Zaragoza; Spain
| |
Collapse
|
32
|
How calcium makes endocytic receptors attractive. Trends Biochem Sci 2014; 39:82-90. [DOI: 10.1016/j.tibs.2013.12.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 11/28/2013] [Accepted: 12/06/2013] [Indexed: 12/21/2022]
|
33
|
Abstract
Low-density lipoprotein cholesterol (LDL-C) is a most important risk factor for developing coronary artery disease (CAD) and other forms of atherosclerotic cardiovascular disease (CVD) and a major focus of CVD risk reduction with lifestyle and statins. Unfortunately residual risk of CVD remains in patients with familial hypercholesterolaemia and/or statin intolerance in whom adequate LDL-C lowering is not accomplished with lifestyle and statins. PCSK9 is a serine protease that binds the LDL receptor (LDL-R) and acts as a chaparone for endocytosis and shuttling the PCSK9-LDLR complex to lysosomes for degradation. In the absence of PCSK9 the LDLR-LDL-C complex dissociates and LDL-R is recycled back to the cell surface. Humanised monoclonal antibodies (evolocumab, alirocumab, bocolicumab) have been developed that increase LDL-R by ~2-fold and lower LDL-C by up to 75 percent. This effect is synergistic to that of statins with the only common adverse effect is a local injection site reaction. At present, ongoing Phase III CVD outcome trials with PCSK9 inhibitors offer promise that patients with LDL-C levels that remain elevated can decrease CVD events and related mortality.
Collapse
Affiliation(s)
- Reynaria N Pitts
- Charles A. Boettcher II Chair in Atherosclerosis, University of Colorado Anschutz Medical Campus, Aurora, CO, US
| | - Robert H Eckel
- Charles A. Boettcher II Chair in Atherosclerosis, University of Colorado Anschutz Medical Campus, Aurora, CO, US
| |
Collapse
|
34
|
Andersen OM, Dagil R, Kragelund BB. New horizons for lipoprotein receptors: communication by β-propellers. J Lipid Res 2013; 54:2763-74. [PMID: 23881912 DOI: 10.1194/jlr.m039545] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The lipoprotein receptor (LR) family constitutes a large group of structurally closely related receptors with broad ligand-binding specificity. Traditionally, ligand binding to LRs has been anticipated to involve merely the complement type repeat (CR)-domains omnipresent in the family. Recently, this dogma has transformed with the observation that β-propellers of some LRs actively engage in complex formation too. Based on an in-depth decomposition of current structures and sequences, we suggest that exploitation of the β-propellers as binding targets depends on receptor subgroups. In particular, we highlight the shutter mechanism of β-propellers as a general recognition motif for NxI-containing ligands, and we present indications that the generalized β-propeller-induced ligand release mechanism is not applicable for the larger LRs. For the giant LR members, we present evidence that their β-propellers may also actively engage in ligand binding. We therefore advocate for an increased focus on solving the structure-function relationship of this group of important biological receptors.
Collapse
Affiliation(s)
- Olav M Andersen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; and
| | | | | |
Collapse
|
35
|
De Marcos Lousa C, Gershlick DC, Denecke J. Mechanisms and concepts paving the way towards a complete transport cycle of plant vacuolar sorting receptors. THE PLANT CELL 2012; 24:1714-32. [PMID: 22570446 PMCID: PMC3442565 DOI: 10.1105/tpc.112.095679] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Delivery of proteins to the lytic vacuole in plants is a complex cascade of selective interactions that specifically excludes residents of the endoplasmic reticulum and secreted proteins. Vacuolar transport must be highly efficient to avoid mistargeting of hydrolytic enzymes to locations where they could be harmful. While plant vacuolar sorting signals have been well described for two decades, it is only during the last 5 years that a critical mass of data was gathered that begins to reveal how vacuolar sorting receptors (VSRs) may complete a full transport cycle. Yet, the field is far from reaching a consensus regarding the organelles that could be involved in vacuolar sorting, their potential biogenesis, and the ultimate recycling of membranes and protein machinery that maintain this pathway. This review will highlight the important landmarks in our understanding of VSR function and compare recent transport models that have been proposed so that an emerging picture of plant vacuolar sorting mechanisms can be drawn.
Collapse
|
36
|
Lo Surdo P, Bottomley MJ, Calzetta A, Settembre EC, Cirillo A, Pandit S, Ni YG, Hubbard B, Sitlani A, Carfí A. Mechanistic implications for LDL receptor degradation from the PCSK9/LDLR structure at neutral pH. EMBO Rep 2011; 12:1300-5. [PMID: 22081141 DOI: 10.1038/embor.2011.205] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 08/26/2011] [Accepted: 09/12/2011] [Indexed: 12/19/2022] Open
Abstract
The protein PCSK9 (proprotein convertase subtilisin/kexin type 9) is a key regulator of low-density lipoprotein receptor (LDLR) levels and cardiovascular health. We have determined the crystal structure of LDLR bound to PCSK9 at neutral pH. The structure shows LDLR in a new extended conformation. The PCSK9 C-terminal domain is solvent exposed, enabling cofactor binding, whereas the catalytic domain and prodomain interact with LDLR epidermal growth factor(A) and β-propeller domains, respectively. Thus, PCSK9 seems to hold LDLR in an extended conformation and to interfere with conformational rearrangements required for LDLR recycling.
Collapse
Affiliation(s)
- Paola Lo Surdo
- Department of Biochemistry and Molecular Biology, IRBM P. Angeletti, Via Pontina Km 30.600, Pomezia, Rome I-00040, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Calandra S, Tarugi P, Speedy HE, Dean AF, Bertolini S, Shoulders CC. Mechanisms and genetic determinants regulating sterol absorption, circulating LDL levels, and sterol elimination: implications for classification and disease risk. J Lipid Res 2011; 52:1885-926. [PMID: 21862702 DOI: 10.1194/jlr.r017855] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestinal and hepatic-derived lipoprotein remnants (LDLR, APOB, APOE, LDLRAP1, PCSK9, IDOL). The insights gained from integrating the wealth of genetic data with biological processes have important implications for the classification of clinical and presymptomatic diagnoses of traditional LDL dyslipidemias, sitosterolemia, and newly emerging phenotypes, as well as their management through both nutritional and pharmaceutical means.
Collapse
Affiliation(s)
- Sebastiano Calandra
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.
| | | | | | | | | | | |
Collapse
|
38
|
Zhao Z, Michaely P. Role of an intramolecular contact on lipoprotein uptake by the LDL receptor. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:397-408. [PMID: 21511053 DOI: 10.1016/j.bbalip.2011.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 03/09/2011] [Accepted: 04/01/2011] [Indexed: 01/06/2023]
Abstract
The LDL receptor (LDLR) is an endocytic receptor that plays a major role in the clearance of atherogenic lipoproteins from the circulation. During the endocytic process, the LDLR first binds lipoprotein at the cell surface and then traffics to endosomes, where the receptor releases bound lipoprotein. Release is acid-dependent and correlates with the formation of an intramolecular contact within the receptor. Human mutations at residues that form the contact are associated with familial hypercholesterolemia (FH) and the goal of the present study was to determine the role of contact residues on LDLR function. We show that mutations at nine contact residues reduce the ability of the LDLR to support lipoprotein uptake. Unexpectedly, only four of the mutations (W515A, W541A, H562Y and H586Y) impaired acid-dependent lipoprotein release. The remaining mutations decreased the lipoprotein-binding capacity of the LDLR through either reduction in the number of surface receptors (H190Y, K560W, H562Y and K582W) or reduction in the fraction of surface receptors that were competent to bind lipoprotein (W144A and W193A). We also examined three residues, distal to the contact, which were predicted to be necessary for the LDLR to adopt the acidic conformation. Of the three mutations we tested (G293S, F362A and G375S), one mutation (F362A) reduced lipoprotein uptake. Together, these data suggest that the intramolecular interface plays multiple roles in LDLR function.
Collapse
Affiliation(s)
- Zhenze Zhao
- Department of Cell Biology at the University of Texas Southwestern Medical Center, Dallas, TX 75390-9039 USA
| | | |
Collapse
|
39
|
Model of human low-density lipoprotein and bound receptor based on cryoEM. Proc Natl Acad Sci U S A 2009; 107:1059-64. [PMID: 20080547 DOI: 10.1073/pnas.0908004107] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human plasma low-density lipoproteins (LDL), a risk factor for cardiovascular disease, transfer cholesterol from plasma to liver cells via the LDL receptor (LDLr). Here, we report the structures of LDL and its complex with the LDL receptor extracellular domain (LDL.LDLr) at extracellular pH determined by cryoEM. Difference imaging between LDL.LDLr and LDL localizes the site of LDLr bound to its ligand. The structural features revealed from the cryoEM map lead to a juxtaposed stacking model of cholesteryl esters (CEs). High density in the outer shell identifies protein-rich regions that can be accounted for by a single apolipoprotein (apo B-100, 500 kDa) leading to a model for the distribution of its alpha-helix and beta-sheet rich domains across the surface. The structural relationship between the apo B-100 and CEs appears to dictate the structural stability and function of normal LDL.
Collapse
|