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Brampton C, Pomozi V, Le Corre Y, Zoll J, Kauffenstein G, Ma C, Hoffmann PR, Martin L, Le Saux O. Bone Marrow-Derived ABCC6 Is an Essential Regulator of Ectopic Calcification In Pseudoxanthoma Elasticum. J Invest Dermatol 2024; 144:1772-1783.e3. [PMID: 38367909 PMCID: PMC11260544 DOI: 10.1016/j.jid.2024.01.026] [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: 10/30/2023] [Revised: 12/31/2023] [Accepted: 01/26/2024] [Indexed: 02/19/2024]
Abstract
Physiological calcification of soft tissues is a common occurrence in aging and various acquired and inherited disorders. ABCC6 sequence variations cause the calcification phenotype of pseudoxanthoma elasticum (PXE) as well as some cases of generalized arterial calcification of infancy, which is otherwise caused by defective ENPP1. ABCC6 is primarily expressed in the liver, which has given the impression that the liver is central to the pathophysiology of PXE/generalized arterial calcification of infancy. The emergence of inflammation as a contributor to the calcification in PXE suggested that peripheral tissues play a larger role than expected. In this study, we investigated whether bone marrow-derived ABCC6 contributes to the calcification in PXE. In Abcc6‒/‒ mice, we observed prevalent mineralization in several lymph nodes and surrounding connective tissues and an extensive network of lymphatic vessels within vibrissae, a calcified tissue in Abcc6‒/‒ mice. Furthermore, we found evidence of lymphangiogenesis in patients with PXE and mouse skin, suggesting an inflammatory process. Finally, restoring wild-type bone marrow in Abcc6‒/‒ mice produced a significant reduction of calcification, suggesting that the liver alone is not sufficient to fully inhibit mineralization. With evidence that ABCC6 is expressed in lymphocytes, we suggest that the adaptative immune system and inflammation largely contribute to the calcification in PXE/generalized arterial calcification of infancy.
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Affiliation(s)
- Christopher Brampton
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; Bio-Rad Laboratories, Hercules, California, USA
| | - Viola Pomozi
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Centre of Excellence, Budapest, Hungary
| | - Yannick Le Corre
- PXE National Reference Center (MAGEC Nord), University Hospital of Angers, Angers, France
| | - Janna Zoll
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Gilles Kauffenstein
- UMR INSERM 1260, Nano Regenerative Medicine, University of Strasbourg, Strasbourg, France
| | - Chi Ma
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Peter R Hoffmann
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Ludovic Martin
- PXE National Reference Center (MAGEC Nord), University Hospital of Angers, Angers, France; CNRS 6015, UMR INSERM U1083, MITOVASC Laboratory, University of Angers, Angers, France
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
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Inorganic Pyrophosphate Plasma Levels Are Decreased in Pseudoxanthoma Elasticum Patients and Heterozygous Carriers but Do Not Correlate with the Genotype or Phenotype. J Clin Med 2023; 12:jcm12051893. [PMID: 36902680 PMCID: PMC10003929 DOI: 10.3390/jcm12051893] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/29/2023] [Accepted: 02/10/2023] [Indexed: 03/08/2023] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a rare ectopic calcification disorder affecting soft connective tissues that is caused by biallelic ABCC6 mutations. While the underlying pathomechanisms are incompletely understood, reduced circulatory levels of inorganic pyrophosphate (PPi)-a potent mineralization inhibitor-have been reported in PXE patients and were suggested to be useful as a disease biomarker. In this study, we explored the relation between PPi, the ABCC6 genotype and the PXE phenotype. For this, we optimized and validated a PPi measurement protocol with internal calibration that can be used in a clinical setting. An analysis of 78 PXE patients, 69 heterozygous carriers and 14 control samples revealed significant differences in the measured PPi levels between all three cohorts, although there was overlap between all groups. PXE patients had a ±50% reduction in PPi levels compared to controls. Similarly, we found a ±28% reduction in carriers. PPi levels were found to correlate with age in PXE patients and carriers, independent of the ABCC6 genotype. No correlations were found between PPi levels and the Phenodex scores. Our results suggest that other factors besides PPi are at play in ectopic mineralization, which limits the use of PPi as a predictive biomarker for severity and disease progression.
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Ralph D, Levine M, Millán JL, Uitto J, Li Q. Weighing the Evidence for the Roles of Plasma Versus Local Pyrophosphate in Ectopic Calcification Disorders. J Bone Miner Res 2023; 38:457-463. [PMID: 36807615 PMCID: PMC10365072 DOI: 10.1002/jbmr.4791] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/02/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023]
Abstract
Ectopic calcification is characterized by inappropriate deposition of calcium mineral in nonskeletal connective tissues and can cause significant morbidity and mortality, particularly when it affects the cardiovascular system. Identification of the metabolic and genetic determinants of ectopic calcification could help distinguish individuals at the greatest risk of developing these pathological calcifications and could guide development of medical interventions. Inorganic pyrophosphate (PPi ) has long been recognized as the most potent endogenous inhibitor of biomineralization. It has been intensively studied as both a marker and a potential therapeutic for ectopic calcification. Decreased extracellular concentrations of PPi have been proposed to be a unifying pathophysiological mechanism for disorders of ectopic calcification, both genetic and acquired. However, are reduced plasma concentrations of PPi a reliable predictor of ectopic calcification? This perspective article evaluates the literature in favor and against a pathophysiological role of plasma versus tissue PPi dysregulation as a determinant of, and as a biomarker for, ectopic calcification. © 2023 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Douglas Ralph
- Genetics, Genomics and Cancer Biology Ph.D. Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA.,Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael Levine
- Division of Endocrinology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
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4
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Serum Calcification Propensity T50 Associates with Disease Severity in Patients with Pseudoxanthoma Elasticum. J Clin Med 2022; 11:jcm11133727. [PMID: 35807012 PMCID: PMC9267205 DOI: 10.3390/jcm11133727] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/21/2022] [Accepted: 06/26/2022] [Indexed: 11/17/2022] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a currently intractable genetic disorder characterized by progressive ectopic calcification in the skin, eyes and arteries. Therapeutic trials in PXE are severely hampered by the lack of reliable biomarkers. Serum calcification propensity T50 is a blood test measuring the functional anticalcifying buffer capacity of serum. Here, we evaluated T50 in PXE patients aiming to investigate its determinants and suitability as a potential biomarker for disease severity. Fifty-seven PXE patients were included in this cross-sectional study, and demographic, clinical, imaging and biochemical data were collected from medical health records. PXE severity was assessed using Phenodex scores. T50 was measured using a validated, nephelometry-based assay. Multivariate models were then created to investigate T50 determinants and associations with disease severity. In short, the mean age of patients was 45.2 years, 68.4% was female and mean serum T50 was 347 min. Multivariate regression analysis identified serum fetuin-A (p < 0.001), phosphorus (p = 0.007) and magnesium levels (p = 0.034) as significant determinants of T50, while no correlations were identified with serum calcium, eGFR, plasma PPi levels or the ABCC6 genotype. After correction for covariates, T50 was found to be an independent determinant of ocular (p = 0.013), vascular (p = 0.013) and overall disease severity (p = 0.016) in PXE. To conclude, shorter serum T50—indicative of a higher calcification propensity—was associated with a more severe phenotype in PXE patients. This study indicates, for the first time, that serum T50 might be a clinically relevant biomarker in PXE and may thus be of importance to future therapeutic trials.
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Shimada BK, Pomozi V, Zoll J, Kuo S, Martin L, Le Saux O. ABCC6, Pyrophosphate and Ectopic Calcification: Therapeutic Solutions. Int J Mol Sci 2021; 22:ijms22094555. [PMID: 33925341 PMCID: PMC8123679 DOI: 10.3390/ijms22094555] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022] Open
Abstract
Pathological (ectopic) mineralization of soft tissues occurs during aging, in several common conditions such as diabetes, hypercholesterolemia, and renal failure and in certain genetic disorders. Pseudoxanthoma elasticum (PXE), a multi-organ disease affecting dermal, ocular, and cardiovascular tissues, is a model for ectopic mineralization disorders. ABCC6 dysfunction is the primary cause of PXE, but also some cases of generalized arterial calcification of infancy (GACI). ABCC6 deficiency in mice underlies an inducible dystrophic cardiac calcification phenotype (DCC). These calcification diseases are part of a spectrum of mineralization disorders that also includes Calcification of Joints and Arteries (CALJA). Since the identification of ABCC6 as the “PXE gene” and the development of several animal models (mice, rat, and zebrafish), there has been significant progress in our understanding of the molecular genetics, the clinical phenotypes, and pathogenesis of these diseases, which share similarities with more common conditions with abnormal calcification. ABCC6 facilitates the cellular efflux of ATP, which is rapidly converted into inorganic pyrophosphate (PPi) and adenosine by the ectonucleotidases NPP1 and CD73 (NT5E). PPi is a potent endogenous inhibitor of calcification, whereas adenosine indirectly contributes to calcification inhibition by suppressing the synthesis of tissue non-specific alkaline phosphatase (TNAP). At present, therapies only exist to alleviate symptoms for both PXE and GACI; however, extensive studies have resulted in several novel approaches to treating PXE and GACI. This review seeks to summarize the role of ABCC6 in ectopic calcification in PXE and other calcification disorders, and discuss therapeutic strategies targeting various proteins in the pathway (ABCC6, NPP1, and TNAP) and direct inhibition of calcification via supplementation by various compounds.
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Affiliation(s)
- Briana K Shimada
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96817, USA
| | - Viola Pomozi
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, 1117 Budapest, Hungary
| | - Janna Zoll
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96817, USA
| | - Sheree Kuo
- Department of Pediatrics, Kapi'olani Medical Center for Women and Children, University of Hawaii, Honolulu, HI 96826, USA
| | - Ludovic Martin
- PXE Consultation Center, MAGEC Reference Center for Rare Skin Diseases, Angers University Hospital, 49100 Angers, France
- BNMI, CNRS 6214/INSERM 1083, University Bretagne-Loire, 49100 Angers, France
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96817, USA
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Omur S, Cerik I, Tekin G. The relationship of fetuin-a, omentin-1, and chemerin with left ventricular ejection fraction in heart failure. INTERNATIONAL JOURNAL OF THE CARDIOVASCULAR ACADEMY 2021. [DOI: 10.4103/ijca.ijca_36_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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7
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Chen Y, Zhao X, Wu H. Arterial Stiffness: A Focus on Vascular Calcification and Its Link to Bone Mineralization. Arterioscler Thromb Vasc Biol 2020; 40:1078-1093. [PMID: 32237904 DOI: 10.1161/atvbaha.120.313131] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This review focuses on the association between vascular calcification and arterial stiffness, highlighting the important genetic factors, systemic and local microenvironmental signals, and underlying signaling pathways and molecular regulators of vascular calcification. Elevated oxidative stress appears to be a common procalcification factor that induces osteogenic differentiation and calcification of vascular cells in a variety of disease conditions such as atherosclerosis, diabetes mellitus, and chronic kidney disease. Thus, the role of oxidative stress and oxidative stress-regulated signals in vascular smooth muscle cells and their contributions to vascular calcification are highlighted. In relation to diabetes mellitus, the regulation of both hyperglycemia and increased protein glycosylation, by AGEs (advanced glycation end products) and O-linked β-N-acetylglucosamine modification, and its role in enhancing intracellular pathophysiological signaling that promotes osteogenic differentiation and calcification of vascular smooth muscle cells are discussed. In the context of chronic kidney disease, this review details the role of calcium and phosphate homeostasis, parathyroid hormone, and specific calcification inhibitors in regulating vascular calcification. In addition, the impact of the systemic and microenvironmental factors on respective intrinsic signaling pathways that promote osteogenic differentiation and calcification of vascular smooth muscle cells and osteoblasts are compared and contrasted, aiming to dissect the commonalities and distinctions that underlie the paradoxical vascular-bone mineralization disorders in aging and diseases.
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Affiliation(s)
- Yabing Chen
- From the Departments of Pathology (Y.C.), The University of Alabama at Birmingham.,Birmingham Veterans Affairs Medical Center, Research Department, AL (Y.C.)
| | - Xinyang Zhao
- Biochemistry (X.Z.), The University of Alabama at Birmingham
| | - Hui Wu
- Pediatric Dentistry (H.W.), The University of Alabama at Birmingham
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8
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Van Gils M, Nollet L, Verly E, Deianova N, Vanakker OM. Cellular signaling in pseudoxanthoma elasticum: an update. Cell Signal 2019; 55:119-129. [PMID: 30615970 DOI: 10.1016/j.cellsig.2018.12.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/20/2018] [Accepted: 12/20/2018] [Indexed: 12/27/2022]
Abstract
Pseudoxanthoma elasticum is an autosomal recessive genodermatosis with variable expression, due to mutations in the ABCC6 or ENPP1 gene. It is characterized by elastic fiber mineralization and fragmentation, resulting in skin, eye and cardiovascular symptoms. Significant advances have been made in the last 20 years with respect to the phenotypic characterization and pathophysiological mechanisms leading to elastic fiber mineralization. Nonetheless, the substrates of the ABCC6 transporter - the main cause of PXE - remain currently unknown. Though the precise mechanisms linking the ABCC6 transporter to mineralization of the extracellular matrix are unclear, several studies have looked into the cellular consequences of ABCC6 deficiency in PXE patients and/or animal models. In this paper, we compile the evidence on cellular signaling in PXE, which seems to revolve mainly around TGF-βs, BMPs and inorganic pyrophosphate signaling cascades. Where conflicting results or fragmented data are present, we address these with novel signaling data. This way, we aim to better understand the up- and down-stream signaling of TGF-βs and BMPs in PXE and we demonstrate that ANKH deficiency can be an additional mechanism contributing to decreased serum PPi levels in PXE patients.
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Affiliation(s)
- M Van Gils
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Belgium
| | - L Nollet
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - E Verly
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - N Deianova
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - O M Vanakker
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Belgium.
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9
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Merdler-Rabinowicz R, Grinberg A, Jacobson JM, Somekh I, Klein C, Lev A, Ihsan S, Habib A, Somech R, Simon AJ. Fetuin-A deficiency is associated with infantile cortical hyperostosis (Caffey disease). Pediatr Res 2019; 86:603-607. [PMID: 31288248 PMCID: PMC7086575 DOI: 10.1038/s41390-019-0499-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/11/2019] [Accepted: 06/29/2019] [Indexed: 12/02/2022]
Abstract
BACKGROUND Infantile cortical hyperostosis (ICH)/Caffey disease is an inflammatory collagenopathy of infancy, manifested by subperiosteal bone hyperplasia. Genetically, ICH was linked with heterozygosity for an R836C mutation in the COL1A1 gene. Although an autosomal-recessive trait is also suspected, it has not been proven thus far. METHODS A case of an infant male born to consanguineous parents is reported, presenting with classical findings, course, and clinical outcome of ICH. Whole-exome sequencing (WES) was performed in order to identify a possible underlying genetic defect. RESULTS WES analysis revealed a novel homozygous nonsense mutation in lysine 2 of fetuin-A, encoded by the ALPHA-2-HS-GLYCOPROTEIN (AHSG) gene (c.A4T; p.K2X). Fetuin-A is an important regulator of bone remodeling and an inhibitor of ectopic mineralization. By enzyme-linked immunosorbent assay (ELISA), we show a complete deficiency of this protein in the patient's serum, compared to controls. CONCLUSION A novel homozygous nonsense mutation in AHSG gene has been found in ICH patient with a typical phenotype, resulting in fetuin-A deficiency. This finding postulates an autosomal-recessive mode of inheritance in ICH, which, unlike the autosomal-dominant inheritance associated with COL1A1, is associated with AHSG and fetuin-A deficiency.
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Affiliation(s)
- Rona Merdler-Rabinowicz
- 0000 0004 1937 0546grid.12136.37Pediatric Department A and the Immunology Services, “Edmond and Lily Safra” Children’s Hospital, Jeffrey Modell Foundation Center, Sheba Medical Center, Tel Hashomer, affiliated to Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Anna Grinberg
- 0000 0004 1937 0546grid.12136.37Pediatric Department A and the Immunology Services, “Edmond and Lily Safra” Children’s Hospital, Jeffrey Modell Foundation Center, Sheba Medical Center, Tel Hashomer, affiliated to Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Jeffrey M. Jacobson
- grid.460042.4Pediatric Radiology Department, “Edmond and Lily Safra” Children’s Hospital, Tel Hashomer, Israel
| | - Ido Somekh
- 0000 0004 1936 973Xgrid.5252.0Dr. von Hauner Children’s Hospital, University Hospital, Ludwig Maximilian University, Munich, Germany
| | - Christoph Klein
- 0000 0004 1936 973Xgrid.5252.0Dr. von Hauner Children’s Hospital, University Hospital, Ludwig Maximilian University, Munich, Germany
| | - Atar Lev
- 0000 0004 1937 0546grid.12136.37Pediatric Department A and the Immunology Services, “Edmond and Lily Safra” Children’s Hospital, Jeffrey Modell Foundation Center, Sheba Medical Center, Tel Hashomer, affiliated to Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Adib Habib
- 0000 0004 1937 0503grid.22098.31Saint Vincent De Paul French Hospital, Nazareth, affiliated to the Azrieli Faculty of Medicine, Bar-Ilan University, Ramat Gan, Israel
| | - Raz Somech
- 0000 0004 1937 0546grid.12136.37Pediatric Department A and the Immunology Services, “Edmond and Lily Safra” Children’s Hospital, Jeffrey Modell Foundation Center, Sheba Medical Center, Tel Hashomer, affiliated to Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Amos J. Simon
- 0000 0004 1937 0546grid.12136.37Pediatric Department A and the Immunology Services, “Edmond and Lily Safra” Children’s Hospital, Jeffrey Modell Foundation Center, Sheba Medical Center, Tel Hashomer, affiliated to Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel ,0000 0001 2107 2845grid.413795.dSheba Cancer Research Center and Institute of Hematology, Sheba Medical Center, Tel Hashomer, Israel
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Borst P, Váradi A, van de Wetering K. PXE, a Mysterious Inborn Error Clarified. Trends Biochem Sci 2018; 44:125-140. [PMID: 30446375 DOI: 10.1016/j.tibs.2018.10.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/07/2018] [Accepted: 10/15/2018] [Indexed: 12/15/2022]
Abstract
Ever since Garrod deduced the existence of inborn errors in 1901, a vast array of metabolic diseases has been identified and characterized in molecular terms. In 2018 it is difficult to imagine that there is any uncharted backyard left in the metabolic disease landscape. Nevertheless, it took until 2013 to identify the cause of a relatively frequent inborn error, pseudoxanthoma elasticum (PXE), a disorder resulting in aberrant calcification. The mechanism found was not only biochemically interesting but also points to possible new treatments for PXE, a disease that has remained untreatable. In this review we sketch the tortuous road that led to the biochemical understanding of PXE and to new ideas for treatment. We also discuss some of the controversies still haunting the field.
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Affiliation(s)
- Piet Borst
- Division of Oncogenetics, The Netherlands Cancer Institute, 1066CX Amsterdam, The Netherlands.
| | - András Váradi
- Institute of Enzymology, Research Center for Natural Sciences (RCNS), Hungarian Academy of Sciences, 1117 Budapest, Hungary
| | - Koen van de Wetering
- Department of Dermatology and Cutaneous Biology and PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA 19107, USA
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11
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Serum vitamin D, intact parathyroid hormone, and Fetuin A concentrations were associated with geriatric sarcopenia and cardiac hypertrophy. Sci Rep 2017; 7:40996. [PMID: 28112206 PMCID: PMC5253676 DOI: 10.1038/srep40996] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 12/13/2016] [Indexed: 01/19/2023] Open
Abstract
With aging, intact parathyroid hormone (iPTH) increases. It plays a crucial role in left ventricular hypertrophy (LVH). Also, 25-hydroxy vitamin D (Vit-D) and iPTH have been observed to be determinants of muscle wasting known as sarcopenia. Fetuin A (FetA), a systemic calcification inhibitor, involves in the development of diastolic heart failure. Hence, we hypothesized that the interplay among FetA, Vit-D and iPTH may contribute to sarcopenic LVH among the elders. We analyzed a database from the Tianliao Old People study with 541 elders (≥65 years) in a Taiwan’s suburban community. After excluding patients with renal function impairment, 120/449 (26.7%) patients were diagnosed with sarcopenia. Sarcopenic patients had lower serum Vit-D levels but higher FetA as well as iPTH. Notably, sarcopenic patients with LVH had significantly lower FetA and higher iPTH levels. In multivariate logistic regression analysis, only the increase in iPTH was independently associated with sarcopenic LVH (Odds ratio: 1.05; confidence interval: 1.03–1.08, p = 0.005). Using iPTH >52.3 ng/l as a cutoff point, the sensitivity and specificity was 66% and 84%, respectively. In conclusion, FetA, Vit-D, and iPTH levels were all associated with sarcopenia in this geriatric population. Among them, iPTH specifically indicates patients with sarcopenic LVH.
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12
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Pomozi V, Brampton C, Szeri F, Dedinszki D, Kozák E, van de Wetering K, Hopkins H, Martin L, Váradi A, Le Saux O. Functional Rescue of ABCC6 Deficiency by 4-Phenylbutyrate Therapy Reduces Dystrophic Calcification in Abcc6 -/- Mice. J Invest Dermatol 2016; 137:595-602. [PMID: 27826008 DOI: 10.1016/j.jid.2016.10.035] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 10/04/2016] [Accepted: 10/13/2016] [Indexed: 12/16/2022]
Abstract
Soft-tissue calcification is associated with aging, common conditions such as diabetes or hypercholesterolemia, and with certain genetic disorders. ABCC6 is an efflux transporter primarily expressed in liver facilitating the release of adenosine triphosphate from hepatocytes. Within the liver vasculature, adenosine triphosphate is converted into pyrophosphate, a major inhibitor of ectopic calcification. ABCC6 mutations thus lead to reduced plasma pyrophosphate levels, resulting in the calcification disorder pseudoxanthoma elasticum and some cases of generalized arterial calcification of infancy. Most mutations in ABCC6 are missense, and many preserve transport activity but are retained intracellularly. We have previously shown that the chemical chaperone 4-phenylbutyrate (4-PBA) promotes the maturation of ABCC6 mutants to the plasma membrane. In a humanized mouse model of pseudoxanthoma elasticum, we investigated whether 4-PBA treatments could rescue the calcification inhibition potential of selected ABCC6 mutants. We used the dystrophic cardiac calcification phenotype of Abcc6-/- mice as an indicator of ABCC6 function to quantify the effect of 4-PBA on human ABCC6 mutants transiently expressed in the liver. We showed that 4-PBA administrations restored the physiological function of ABCC6 mutants, resulting in enhanced calcification inhibition. This study identifies 4-PBA treatment as a promising strategy for allele-specific therapy of ABCC6-associated calcification disorders.
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Affiliation(s)
- Viola Pomozi
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary
| | - Christopher Brampton
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Flóra Szeri
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary
| | - Dóra Dedinszki
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary
| | - Eszter Kozák
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary
| | - Koen van de Wetering
- Division of Molecular Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Hi'ilani Hopkins
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Ludovic Martin
- University of Angers, Angers, France; CHU Angers, Centre de consultation PXE, Angers, France
| | - András Váradi
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
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Wu J, Xue F, Shi WZ, Xiao HJ. Fetuin A is down-regulated in rats during heterotopic ossification after Achilles tenotomy. Biotech Histochem 2016; 91:229-36. [PMID: 26984264 DOI: 10.3109/10520295.2015.1047793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We investigated the role of fetuin A during heterotopic ossification (HO) in rats following Achilles tenotomy. We performed a right midpoint Achilles tenotomy on 24 rats. At 5 and 10 h after surgery, we investigated the formation of ectopic bone using X-ray and histological examination. We evaluated the mRNA level of fetuin A using real-time PCR. Presence of fetuin A in the Achilles tendon was assessed by immunohistochemical staining. We also measured the serum concentration of fetuin A using enzyme linked immunosorbent assay (ELISA). The expression of fetuin A was significantly decreased in both the liver and Achilles tendon during HO. ELISA showed a small amount of fetuin A in blood throughout the development of HO. Immunohistochemical staining showed that fetuin A was abundant in the ectopic bone. Fetuin A appears to be involved in the formation of ectopic bone induced by Achilles tenotomy, and a deficiency of fetuin A plays a role in the development of HO.
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Affiliation(s)
- J Wu
- a Department of Orthopedics , Changsha Hospital of Traditional Chinese Medicine (Changsha Eighth Hospital) , Changsha , China
| | - F Xue
- b Department of Orthopedics , Southern Medical University Affiliated Fengxian Hospital , Shanghai , China
| | - W Z Shi
- b Department of Orthopedics , Southern Medical University Affiliated Fengxian Hospital , Shanghai , China
| | - H J Xiao
- b Department of Orthopedics , Southern Medical University Affiliated Fengxian Hospital , Shanghai , China
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14
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A functional proteomics approach to the comprehension of sarcoidosis. J Proteomics 2015; 128:375-87. [PMID: 26342673 DOI: 10.1016/j.jprot.2015.08.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 07/30/2015] [Accepted: 08/19/2015] [Indexed: 12/22/2022]
Abstract
Pulmonary sarcoidosis (Sar) is an idiopathic disease histologically typified by non-caseating epitheliod cell sarcoid granulomas. A cohort of 37 Sar patients with chronic persistent pulmonary disease was described in this study. BAL protein profiles from 9 of these Sar patients were compared with those from 8 smoker (SC) and 10 no-smoker controls (NSC) by proteomic approach. Principal Component Analysis was performed to clusterize the samples in the corresponding conditions highlighting a differential pattern profiles primarily in Sar than SC. Spot identification reveals thirty-four unique proteins involved in lipid, mineral, and vitamin Dmetabolism, and immuneregulation of macrophage function. Enrichment analysis has been elaborated by MetaCore, revealing 14-3-3ε, α1-antitrypsin, GSTP1, and ApoA1 as "central hubs". Process Network as well as Pathway Maps underline proteins involved in immune response and inflammation induced by complement system, innate inflammatory response and IL-6signalling. Disease Biomarker Network highlights Tuberculosis and COPD as pathologies that share biomarkers with sarcoidosis. In conclusion, Sar protein expression profile seems more similar to that of NSC than SC, conversely to other ILDs. Moreover, Disease Biomarker Network revealed several common features between Sar and TB, exhorting to orientate the future proteomics investigations also in comparative BALF analysis of Sar and TB.
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15
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Marconi B, Bobyr I, Campanati A, Molinelli E, Consales V, Brisigotti V, Scarpelli M, Racchini S, Offidani A. Pseudoxanthoma elasticum and skin: Clinical manifestations, histopathology, pathomechanism, perspectives of treatment. Intractable Rare Dis Res 2015; 4:113-22. [PMID: 26361562 PMCID: PMC4561240 DOI: 10.5582/irdr.2015.01014] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 01/10/2023] Open
Abstract
Pseudoxantoma elasticum (PXE), also known as Groenblad-Strandberg syndrome, is a rare heritable disease with an estimated prevalence of 1:50,000 in the general population. PXE is considered a prototype of multisystem ectopic mineralization disorders and it is characterized by aberrant mineralization of soft connective tissue with degeneration of the elastic fibers, involving primarily the eyes, the cardiovascular system, and the skin. Cutaneous lesions consist of small, asymptomatic, yellowish papules or larger coalescent plaques, typically located on the neck and the flexural areas. PXE is caused by mutations in the ABCC6 (ATP-binding cassette subfamily C member 6) gene that encodes a transmembrane ATP binding efflux transporter, normally expressed in the liver and the kidney; however, the exact mechanism of ectopic mineralization remains largely unknown. The histological examination of cutaneous lesions, revealing accumulation of pleomorphic elastic structures in middermis, is essential for the definitive diagnosis of PXE, excluding PXE-like conditions. PXE is currently an intractable disease; although the cutaneous findings primarily present a cosmetic problem, they signify the risk for development of ocular and cardiovascular complications associated with considerable morbidity and mortality. The purpose of this review is to present a comprehensive overview of this rare form of hereditary connective tissue disorders, focus on the pathogenesis, the clinical manifestation, and the differential diagnosis of PXE. Emphasis is also placed on the management of cutaneous lesions and treatment perspectives of PXE.
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Affiliation(s)
- Barbara Marconi
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
| | - Ivan Bobyr
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
| | - Anna Campanati
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
- Address correspondence to: Dr. Anna Campanati, Dermatological Unit, Department of Clinical and Molecular Sciences, Polytechnic Marche University, Via Conca 71, Ancona 60020, Italty. E-mail:
| | - Elisa Molinelli
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
| | - Veronica Consales
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
| | - Valerio Brisigotti
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
| | - Marina Scarpelli
- Institute of Pathological Anatomy and Histopathology, Polytechnic University Marche, Ancona, Italty
| | - Stefano Racchini
- Institute of Pathological Anatomy and Histopathology, Polytechnic University Marche, Ancona, Italty
| | - Annamaria Offidani
- Dermatological Unit, Department of Clinical and Molecular Sciences, Polytehnic Marche University, Ancona, Italty
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16
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Fetuin-A as a predicator of sarcopenic left ventricular dysfunction. Sci Rep 2015; 5:12078. [PMID: 26159840 PMCID: PMC4498243 DOI: 10.1038/srep12078] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/01/2015] [Indexed: 02/06/2023] Open
Abstract
Sarcopenia is an aging condition involving low muscle mass and function. Fetuin-A (FetA) appears to be a factor for body composition remodeling. We hypothesized that age increases FetA levels and deteriorates the myocardial function by affecting diastolic function, especially in people with sarcopenia. We enrolled 541 asymptomatic elderly (≥65 years) patients. Compared with non-sarcopenic population, FetA levels were significantly elevated in the ninety-two (17%) patients (79 ± 6 years; male: 34.7%) diagnosed with sarcopenia (621.1 ± 140.7 vs. 697.3 ± 179.6 μg/ml, < 0.001). Sarcopenic left ventricular dysfunction (S-LVD) was defined by the coexistence of sarcopenia and systolic impairment (LVEF < 50%) and 23 (4.3%) of them met the criteria. Patients with S-LVD showed relatively reduced systolic heart function, higher end-diastolic pressure and a higher FetA level (all p < 0.001) than did those with sarcopenia but without LV dysfunction (S-NLVD). Conversely, in the group without sarcopenia, FetA levels were similar regardless of systolic function. Multivariable logistic regression showed that older age, impaired diastolic function, and higher FetA levels were significantly associated with S-LVD. In conclusion, we found that FetA was significantly higher in elderly patients with sarcopenia, which was associated with impaired diastolic and systolic functions.
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17
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Mackay EW, Apschner A, Schulte-Merker S. Vitamin K reduces hypermineralisation in zebrafish models of PXE and GACI. Development 2015; 142:1095-101. [PMID: 25758222 DOI: 10.1242/dev.113811] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mineralisation disorder pseudoxanthoma elasticum (PXE) is associated with mutations in the transporter protein ABCC6. Patients with PXE suffer from calcified lesions in the skin, eyes and vasculature, and PXE is related to a more severe vascular calcification syndrome called generalised arterial calcification of infancy (GACI). Mutations in ABCC6 are linked to reduced levels of circulating vitamin K. Here, we describe a mutation in the zebrafish (Danio rerio) orthologue abcc6a, which results in extensive hypermineralisation of the axial skeleton. Administration of vitamin K to embryos was sufficient to restore normal levels of mineralisation. Vitamin K also reduced ectopic mineralisation in a zebrafish model of GACI, and warfarin exacerbated the mineralisation phenotype in both mutant lines. These data suggest that vitamin K could be a beneficial treatment for human patients with PXE or GACI. Additionally, we found that abcc6a is strongly expressed at the site of mineralisation rather than the liver, as it is in mammals, which has significant implications for our understanding of the function of ABCC6.
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Affiliation(s)
- Eirinn W Mackay
- Hubrecht Institute - KNAW & University Medical Center Utrecht, Utrecht 3584 CT, The Netherlands
| | - Alexander Apschner
- Hubrecht Institute - KNAW & University Medical Center Utrecht, Utrecht 3584 CT, The Netherlands
| | - Stefan Schulte-Merker
- Hubrecht Institute - KNAW & University Medical Center Utrecht, Utrecht 3584 CT, The Netherlands EZO, WUR, Wageningen 6709 PG, The Netherlands Institute of Cardiovascular Organogenesis and Regeneration, University of Münster, Münster 48149, Germany Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University of Münster, Münster 48149, Germany
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18
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The role of fetuin-A in mineral trafficking and deposition. BONEKEY REPORTS 2015; 4:672. [PMID: 25987986 DOI: 10.1038/bonekey.2015.39] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/13/2015] [Indexed: 12/18/2022]
Abstract
Calcium and phosphate are the principle ions involved in the deposition of mineral in the human body. Inhibitors of mineralisation are essential for the prevention of ectopic mineral precipitation and deposition. In the past decade, through in vitro, in vivo and clinical observation studies, we have come to appreciate the importance of fetuin-A (Fet-A), a circulating glycoprotein, in preventing ectopic calcium phosphate mineralisation. Moreover, the detection of Fet-A-containing mineral complex, termed calciprotein particles (CPPs), has provided new ways to assess an individual's calcific risk. The pathophysiological significance of CPPs in disease states is yet to be defined, but it provides an exciting avenue to further our understanding of the development of ectopic mineralisation.
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19
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Jin L, Jiang Q, Wu Z, Shao C, Zhou Y, Yang L, Uitto J, Wang G. Genetic heterogeneity of pseudoxanthoma elasticum: the Chinese signature profile of ABCC6 and ENPP1 mutations. J Invest Dermatol 2015; 135:1294-1302. [PMID: 25615550 PMCID: PMC4402129 DOI: 10.1038/jid.2015.10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/09/2014] [Accepted: 12/16/2014] [Indexed: 12/28/2022]
Abstract
Pseudoxanthoma elasticum (PXE), an autosomal recessive disorder characterized by ectopic mineralization, is caused by mutations in the ABCC6 gene. We examined clinically 29 Chinese PXE patients from unrelated families, so far the largest cohort of Asian PXE patients. In a subset of 22 patients, we sequenced ABCC6 and another candidate gene, ENPP1, and conducted pathogenicity analyses for each variant. We identified a total of 17 distinct mutations in ABCC6, 15 of them being, to our knowledge, previously unreported, including 5 frameshift and 10 missense variants. In addition, a missense mutation in combination with a recurrent nonsense mutation in ENPP1 was discovered in a pediatric PXE case. No cases with p.R1141X or del23-29 mutations, common in Caucasian patient populations, were identified. The 10 missense mutations in ABCC6 were expressed in the mouse liver via hydrodynamic tail-vein injections. One mutant protein showed cytoplasmic accumulation indicating abnormal subcellular trafficking, while the other nine mutants showed correct plasma membrane location. These nine mutations were further investigated for their pathogenicity using a recently developed zebrafish mRNA rescue assay. Minimal rescue of the morpholino-induced phenotype was achieved with eight of the nine mutant human ABCC6 mRNAs tested, implying pathogenicity. This study demonstrates that the Chinese PXE population harbors unique ABCC6 mutations. These genetic data have implications for allele-specific therapy currently being developed for PXE.
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Affiliation(s)
- Liang Jin
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Qiujie Jiang
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Zhengsheng Wu
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Changxia Shao
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Yong Zhou
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA; Department of Dermatology, PLA General Hospital, Beijing, China
| | - Luting Yang
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
| | - Gang Wang
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
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20
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Taverna D, Boraldi F, De Santis G, Caprioli RM, Quaglino D. Histology-directed and imaging mass spectrometry: An emerging technology in ectopic calcification. Bone 2015; 74:83-94. [PMID: 25595835 PMCID: PMC4355241 DOI: 10.1016/j.bone.2015.01.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 12/24/2014] [Accepted: 01/07/2015] [Indexed: 01/18/2023]
Abstract
The present study was designed to demonstrate the potential of an optimized histology directed protein identification combined with imaging mass spectrometry technology to reveal and identify molecules associated to ectopic calcification in human tissue. As a proof of concept, mineralized and non-mineralized areas were compared within the same dermal tissue obtained from a patient affected by Pseudoxanthoma elasticum, a genetic disorder characterized by calcification only at specific sites of soft connective tissues. Data have been technically validated on a contralateral dermal tissue from the same subject and compared with those from control healthy skin. Results demonstrate that this approach 1) significantly reduces the effects generated by techniques that, disrupting tissue organization, blend data from affected and unaffected areas; 2) demonstrates that, abolishing differences due to inter-individual variability, mineralized and non-mineralized areas within the same sample have a specific protein profile and have a different distribution of molecules; and 3) avoiding the bias of focusing on already known molecules, reveals a number of proteins that have been never related to the disease nor to the calcification process, thus paving the way for the selection of new molecules to be validated as pathogenic or as potential pharmacological targets.
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Affiliation(s)
- Domenico Taverna
- Department of Chemistry and Chemical Technologies, University of Calabria, Arcavacata di Rende, Italy
| | - Federica Boraldi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Giorgio De Santis
- Department of Medical and Surgical Sciences for Children and Adults, University of Modena and Reggio Emilia, Modena, Italy
| | - Richard M Caprioli
- Departments of Biochemistry, Medicine, Pharmacology and Chemistry and the Mass Spectrometry Research Center, Vanderbilt University Medical Center, Nashville, USA
| | - Daniela Quaglino
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
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21
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Lau WL, Liu S, Vaziri ND. Chronic kidney disease results in deficiency of ABCC6, the novel inhibitor of vascular calcification. Am J Nephrol 2014; 40:51-5. [PMID: 24994603 DOI: 10.1159/000365014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/01/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND Chronic kidney disease (CKD) is associated with arterial medial calcification which plays a major role in the pathogenesis of cardiovascular disease in this population. Several factors are known to promote soft tissue and accelerated arterial calcification in CKD including systemic inflammation, altered calcium and phosphate homeostasis, hypertension, and deficiency of endogenous calcification inhibitors. The ABCC6 transporter (ATP-binding cassette subfamily C number 6), also known as multidrug resistance-associated protein 6 (MRP6), is highly expressed in the liver and kidney. Mutation of ABCC6 results in pseudoxanthoma elasticum, an inherited disorder characterized by arterial and soft tissue calcification. Given the prevalence of arterial medial calcification in CKD, the present study was undertaken to test the hypothesis that CKD may lead to acquired ABCC6 deficiency. METHODS CKD was induced via 5/6 nephrectomy in male Sprague-Dawley rats and by adenine-containing diet to cause chronic interstitial nephropathy in female DBA/2J mice. Sham-operated rats and mice fed regular diet served as controls. Liver and kidney tissues were harvested and processed for ABCC6 protein and mRNA analysis. RESULTS ABCC6 protein levels were significantly reduced in the liver and kidney tissues from CKD rats and mice. However, ABCC6 mRNA levels were unchanged, pointing to post-transcriptional or post-translational mechanisms for the observed ABCC6 deficiency. Additionally, plasma levels of the calcification inhibitor fetuin-A were significantly decreased in CKD animals compared to controls. CONCLUSIONS CKD results in acquired ABCC6 transporter deficiency. To our knowledge this abnormality has not been previously reported and may contribute to CKD-associated vascular and soft tissue calcification.
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Affiliation(s)
- Wei Ling Lau
- Division of Nephrology and Hypertension, Department of Medicine, University of California, Irvine, Calif., USA
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Dabisch-Ruthe M, Kuzaj P, Götting C, Knabbe C, Hendig D. Pyrophosphates as a major inhibitor of matrix calcification in Pseudoxanthoma elasticum. J Dermatol Sci 2014; 75:109-20. [PMID: 24907773 DOI: 10.1016/j.jdermsci.2014.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND Pseudoxanthoma elasticum (PXE) is a rare hereditary disorder characterized by late onset and progressive calcification of elastic fibers in skin, eyes and the cardiovascular system, exemplifying a model for conditions characterized by soft tissue calcification. OBJECTIVE The aim of our study was to characterize cellular inorganic pyrophosphate (PPi) homeostasis in PXE. METHODS Gene expression of PPi metabolizing enzymes was determined by quantitative real-time PCR after incubation up to 21 days with or without addition of Na2HPO4. Extracellular and cytosolic PPi concentrations were measured by enzyme-linked bioluminescence assay. ALP and ENPP1 activity was determined spectrophotometrically. We further established a human cell culture model suitable for investigating PXE and related disorders without addition of artificial calcification triggers. RESULTS Independently of the experimental conditions, PXE fibroblasts revealed a higher degree of matrix calcification. We observed that matrix calcification was associated with altered gene expression of PPi metabolizing enzymes in PXE fibroblasts. In this context, PXE fibroblasts exhibited significantly higher expression of ALP and OPN and reduced mRNA expression and activity of ENPP1. Here, for the first time cytosolic and extracellular PPi levels were shown to be strongly reduced in PXE fibroblasts. We further showed that PPi concentration in bovine and human sera additives had a strong impact on matrix calcification. In a last experimental line, we demonstrated that addition of PPi analogs reduced matrix calcification of PXE fibroblasts most likely by reducing ALP and OPN mRNA expression, restoring ENPP1 activity and subsequently elevating PPi concentrations. CONCLUSION The results of our study along with recent findings point to the essential role of PPi as the central regulatory metabolites preventing matrix calcification in PXE. But what remains to be determined is the underlying molecular mechanism leading to depletion of PPi in PXE. We further suggest that supplementation of PPi analogs might counteract pathological calcification in PXE and related disorders.
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Affiliation(s)
- Mareike Dabisch-Ruthe
- Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Bad Oeynhausen, Germany
| | - Patricia Kuzaj
- Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Bad Oeynhausen, Germany
| | | | - Cornelius Knabbe
- Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Bad Oeynhausen, Germany
| | - Doris Hendig
- Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Bad Oeynhausen, Germany.
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Uitto J, Jiang Q, Váradi A, Bercovitch LG, Terry SF. PSEUDOXANTHOMA ELASTICUM: DIAGNOSTIC FEATURES, CLASSIFICATION, AND TREATMENT OPTIONS. Expert Opin Orphan Drugs 2014; 2:567-577. [PMID: 25383264 DOI: 10.1517/21678707.2014.908702] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
INTRODUCTION Pseudoxanthoma elasticum (PXE), a multisystem orphan disease, clinically affects the skin, the eyes, and the cardiovascular system with considerable morbidity and mortality. The clinical manifestations reflect the underlying pathology consisting of ectopic mineralization of peripheral connective tissues. AREAS COVERED The diagnostic criteria of PXE include characteristic clinical findings, together with histopathology of accumulation of pleiomorphic elastic structures in the dermis with progressive mineralization, and the presence of mutations in the ABCC6 gene. PXE-like cutaneous changes can also be encountered in other ectopic mineralization disorders, including generalized arterial calcification of infancy (GACI) caused by mutations in the ENPP1 gene. In some cases, overlapping clinical features of PXE/GACI, associated with mutations either in ABCC6 or ENPP1, have been noted. PXE demonstrates considerable inter- and intrafamilial heterogeneity, and consequently, accurate diagnosis is required for appropriate classification with prognostic implications. There is no effective and specific treatment for the systemic manifestations of PXE, but effective therapies to counteract the ocular complications are in current clinical use. EXPERT OPINION A number of observations in the murine model, the Abcc6-/- mouse, have indicated that the mineral composition of diet, particularly the magnesium content, can influence the severity of the mineralization phenotype. These observations suggest that appropriate dietary interventions, coupled with lifestyle modifications, including smoking cessation, might alleviate the symptoms and improve the quality of life of individuals affected with this, currently intractable, orphan disease.
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Affiliation(s)
- Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Philadelphia, PA
| | - Qiujie Jiang
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Philadelphia, PA
| | - András Váradi
- Institute of Enzymology, RCNS, Hungarian Academy of Sciences
| | - Lionel G Bercovitch
- Department of Dermatology, Warren Alpert Medical School of Brown University, Providence, RI ; PXE International, Washington, DC
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Direct inhibitory effects of pioglitazone on hepatic fetuin-A expression. PLoS One 2014; 9:e88704. [PMID: 24551137 PMCID: PMC3923806 DOI: 10.1371/journal.pone.0088704] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 01/16/2014] [Indexed: 02/06/2023] Open
Abstract
Fetuin-A, a circulating glycoprotein synthesized in the liver, is involved in insulin resistance and type 2 diabetes. However, regulation of fetuin-A synthesis has remained obscure. We previously reported that pioglitazone treatment significantly reduced serum fetuin-A levels in patients with type 2 diabetes. To clarify whether pioglitazone can directory inhibit hepatic fetuin-A synthesis, we investigated the effects of pioglitazone on fetuin-A expression both in vitro and in vivo. Pioglitazone treatment suppressed mRNA and protein expression of fetuin-A in Fao hepatoma cells. Interestingly, rosiglitazone but not metformin, also inhibited fetuin-A expression. In addition, GW 9662, an inhibitor of peroxisome proliferator-activated receptor (PPAR) γ, reversed pioglitazone-induced suppression of fetuin-A, suggesting that thiazolidinedione derivatives may have common characteristics with regard to fetuin-A suppression, possibly through PPARγactivation. Finally, oral administration of pioglitazone to mice for 8 weeks resulted in suppression of hepatic fetuin-A mRNA. These findings suggest that pioglitazone may partially ameliorate insulin resistance through its direct inhibitory effects on fetuin-A expression in the liver.
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Brampton C, Aherrahrou Z, Chen LH, Martin L, Bergen AA, Gorgels TG, Erdfdi J, Schunkert H, Szabó Z, Váradi A, Le Saux O. The level of hepatic ABCC6 expression determines the severity of calcification after cardiac injury. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:159-70. [PMID: 24479134 PMCID: PMC3873484 DOI: 10.1016/j.ajpath.2013.09.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/18/2013] [Indexed: 12/22/2022]
Abstract
Because vascular or cardiac mineralization is inversely correlated with morbidity and long-term survival, we investigated the role of ABCC6 in the calcification response to cardiac injury in mice. By using two models of infarction, nonischemic cryoinjury and the pathologically relevant coronary artery ligation, we confirmed a large propensity to acute cardiac mineralization in Abcc6−/− mice. Furthermore, when the expression of ABCC6 was reduced to approximately 38% of wild-type levels in Abcc6+/− mice, no calcium deposits in injured cardiac tissue were observed. In addition, we used a gene therapy approach to deliver a functional human ABCC6 via hydrodynamic tail vein injection to approximately 13% of mouse hepatocytes, significantly reducing the calcification response to cardiac cryoinjury. We observed that the level and distribution of known regulators of mineralization, such as osteopontin and matrix Gla protein, but not osteocalcin, were concomitant to the level of hepatic expression of human and mouse ABCC6. We notably found that undercarboxylated matrix Gla protein precisely colocalized within areas of mineralization, whereas osteopontin was more diffusely distributed in the area of injury, suggesting a prominent association for matrix Gla protein and osteopontin in ABCC6-related dystrophic cardiac calcification. This study showed that the expression of ABCC6 in liver is an important determinant of calcification in cardiac tissues in response to injuries and is associated with changes in the expression patterns of regulators of mineralization.
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Affiliation(s)
- Christopher Brampton
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Zouhair Aherrahrou
- Institute for Integrative and Experimental Genomics, German Centre for Cardiovascular Research, partner site Lübeck/Hamburg/Kiel, University of Luebeck, Luebeck, Germany
| | - Li-Hsieh Chen
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Ludovic Martin
- Integrated Neurovascular and Mitochondrial Biology, L’UNAM University, UMR CNRS/INSERM, Angers School of Medicine, Angers, France
| | - Arthur A.B. Bergen
- Department of Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, the Netherlands
- Department of Ophthalmology, Academic Medical Center, Amsterdam, the Netherlands
| | - Theo G.M.F. Gorgels
- Department of Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Amsterdam, the Netherlands
| | - Jeannette Erdfdi
- Institute for Integrative and Experimental Genomics, German Centre for Cardiovascular Research, partner site Lübeck/Hamburg/Kiel, University of Luebeck, Luebeck, Germany
| | - Heribert Schunkert
- German Heart Center Munich, German Centre for Cardiovascular Research, partner site Munich Heart Alliance, Munich, Germany
| | - Zalán Szabó
- Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary
| | - András Váradi
- Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
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Li Q, Jiang Q, Uitto J. Ectopic mineralization disorders of the extracellular matrix of connective tissue: molecular genetics and pathomechanisms of aberrant calcification. Matrix Biol 2013; 33:23-8. [PMID: 23891698 DOI: 10.1016/j.matbio.2013.06.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 06/10/2013] [Accepted: 06/11/2013] [Indexed: 01/07/2023]
Abstract
Ectopic mineralization of connective tissues is a complex process leading to deposition of calcium phosphate complexes in the extracellular matrix, particularly affecting the skin and the arterial blood vessels and common in age-associated disorders. A number of initiating and contributing metabolic and environmental factors are linked to aberrant mineralization in these diseases, making the identification of precise pathomechanistic pathways exceedingly difficult. However, there has been significant recent progress in understanding the ectopic mineralization processes through study of heritable single-gene disorders, which have allowed identification of discrete pathways and contributing factors leading to aberrant connective tissue mineralization. These studies have provided support for the concept of an intricate mineralization/anti-mineralization network present in peripheral connective tissues, providing a perspective to development of pharmacologic approaches to limit the phenotypic consequences of ectopic mineralization. This overview summarizes the current knowledge of ectopic heritable mineralization disorders, with accompanying animal models, focusing on pseudoxanthoma elasticum and generalized arterial calcification of infancy, two autosomal recessive diseases manifesting with extensive connective tissue mineralization in the skin and the cardiovascular system.
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Affiliation(s)
- Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, 233 S. 10th Street, Philadelphia, PA, United States
| | - Qiujie Jiang
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, 233 S. 10th Street, Philadelphia, PA, United States
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, 233 S. 10th Street, Philadelphia, PA, United States.
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Ronchetti I, Boraldi F, Annovi G, Cianciulli P, Quaglino D. Fibroblast involvement in soft connective tissue calcification. Front Genet 2013; 4:22. [PMID: 23467434 PMCID: PMC3588566 DOI: 10.3389/fgene.2013.00022] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 02/11/2013] [Indexed: 12/19/2022] Open
Abstract
Soft connective tissue calcification is not a passive process, but the consequence of metabolic changes of local mesenchymal cells that, depending on both genetic and environmental factors, alter the balance between pro- and anti-calcifying pathways. While the role of smooth muscle cells and pericytes in ectopic calcifications has been widely investigated, the involvement of fibroblasts is still elusive. Fibroblasts isolated from the dermis of pseudoxanthoma elasticum (PXE) patients and of patients exhibiting PXE-like clinical and histopathological findings offer an attractive model to investigate the mechanisms leading to the precipitation of mineral deposits within elastic fibers and to explore the influence of the genetic background and of the extracellular environment on fibroblast-associated calcifications, thus improving the knowledge on the role of mesenchymal cells on pathologic mineralization.
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Affiliation(s)
| | - Federica Boraldi
- PXELab, University of Modena and Reggio EmiliaModena, Italy
- Department of Life Science, University of Modena and Reggio EmiliaModena, Italy
| | - Giulia Annovi
- PXELab, University of Modena and Reggio EmiliaModena, Italy
- Department of Life Science, University of Modena and Reggio EmiliaModena, Italy
| | | | - Daniela Quaglino
- PXELab, University of Modena and Reggio EmiliaModena, Italy
- Department of Life Science, University of Modena and Reggio EmiliaModena, Italy
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Rasmussen MR, Sommerlund M, Moestrup SK. Is classical pseudoxanthoma elasticum a consequence of hepatic 'intoxication' due to ABCC6 substrate accumulation in the liver? Expert Rev Endocrinol Metab 2013; 8:37-46. [PMID: 30731651 DOI: 10.1586/eem.12.72] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pseudoxanthoma elasticum (PXE) is a serious genetic disorder with ectopic mineralization affecting the skin, the eye and the cardiovascular system. The disease is predominantly caused by mutations in the transmembrane ABC protein ABCC6, a putative small substrate transporter. Interestingly, ABCC6 seems virtually absent in the affected organs, whereas a high expression is seen in hepatocytes. This and further published experimental evidence indicate that PXE is a systemic, metabolic liver disease where circulatory changes affect the peripheral mineralization process. Owing to the well-characterized transport of organic substrates by related ABC proteins, it has been proposed that PXE is caused by impaired export of an antimineralization compound to the blood. The authors here present an alternative hypothesis that explains ectopic mineralization in PXE as a consequence of hepatic accumulation of ABCC6 substrate(s) that via gene-regulating effects leads to altered hepatic secretion and activation of antimineralization/anticalcification proteins such as fetuin-A and Gla proteins.
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Affiliation(s)
- Mie Rostved Rasmussen
- a Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus C, Denmark
| | - Mette Sommerlund
- b Department of Dermatology and Venereology, Aarhus University Hospital, P. P. Ørumsgade 11, 8000 Aarhus C, Denmark
| | - Søren Kragh Moestrup
- a Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus C, Denmark
- c Department of Clinical Biochemistry, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark.
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Heritable ectopic mineralization disorders: the paradigm of pseudoxanthoma elasticum. J Invest Dermatol 2012; 132 Suppl 3:E15-9. [PMID: 23154625 DOI: 10.1038/skinbio.2012.5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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30
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Seto J, Busse B, Gupta HS, Schäfer C, Krauss S, Dunlop JWC, Masic A, Kerschnitzki M, Zaslansky P, Boesecke P, Catalá-Lehnen P, Schinke T, Fratzl P, Jahnen-Dechent W. Accelerated growth plate mineralization and foreshortened proximal limb bones in fetuin-A knockout mice. PLoS One 2012; 7:e47338. [PMID: 23091616 PMCID: PMC3473050 DOI: 10.1371/journal.pone.0047338] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/10/2012] [Indexed: 12/27/2022] Open
Abstract
The plasma protein fetuin-A/alpha2-HS-glycoprotein (genetic symbol Ahsg) is a systemic inhibitor of extraskeletal mineralization, which is best underscored by the excessive mineral deposition found in various tissues of fetuin-A deficient mice on the calcification-prone genetic background DBA/2. Fetuin-A is known to accumulate in the bone matrix thus an effect of fetuin-A on skeletal mineralization is expected. We examined the bones of fetuin-A deficient mice maintained on a C57BL/6 genetic background to avoid bone disease secondary to renal calcification. Here, we show that fetuin-A deficient mice display normal trabecular bone mass in the spine, but increased cortical thickness in the femur. Bone material properties, as well as mineral and collagen characteristics of cortical bone were unaffected by the absence of fetuin-A. In contrast, the long bones especially proximal limb bones were severely stunted in fetuin-A deficient mice compared to wildtype littermates, resulting in increased biomechanical stability of fetuin-A deficient femora in three-point-bending tests. Elevated backscattered electron signal intensities reflected an increased mineral content in the growth plates of fetuin-A deficient long bones, corroborating its physiological role as an inhibitor of excessive mineralization in the growth plate cartilage matrix - a site of vigorous physiological mineralization. We show that in the case of fetuin-A deficiency, active mineralization inhibition is a necessity for proper long bone growth.
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Affiliation(s)
- Jong Seto
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Himadri S. Gupta
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Cora Schäfer
- Helmholtz Institute of Biomedical Engineering, Biointerface Laboratory, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
| | - Stefanie Krauss
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - John W. C. Dunlop
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Admir Masic
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Michael Kerschnitzki
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Paul Zaslansky
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Peter Boesecke
- Beamline ID2, European Synchrotron Radiation Facility, Grenoble, France
| | - Philip Catalá-Lehnen
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Peter Fratzl
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Willi Jahnen-Dechent
- Helmholtz Institute of Biomedical Engineering, Biointerface Laboratory, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
- * E-mail:
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Gorgels TGMF, Teeling P, Meeldijk JD, Nillesen STM, van der Wal AC, van Kuppevelt TH, Bergen AAB. Abcc6 deficiency in the mouse leads to calcification of collagen fibers in Bruch's membrane. Exp Eye Res 2012; 104:59-64. [PMID: 23041262 DOI: 10.1016/j.exer.2012.09.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 09/14/2012] [Accepted: 09/24/2012] [Indexed: 11/28/2022]
Abstract
Pseudoxanthoma elasticum (PXE) is a heritable disorder characterized by mineralization of connective tissue, which leads to pathology in eye, skin and blood vessels. The disease is caused by mutations in ABCC6. To learn more about PXE eye pathology, we analyzed Bruch's membrane (BM) of the eye of an Abcc6 knockout mouse. With age, BM differences between Abcc6-/- and wild type mice became apparent. At two years of age, von Kossa staining indicated clear calcification of BM in Abcc6-/- mice, and not in healthy controls. Electron microscopy revealed BM changes as early as at 10 months of age: Fibrous structures with abnormal high electron-density were present in the central layers of BM of Abcc6-/- mice. EDX (Energy Dispersive X-ray) analysis demonstrated that these structures contained elevated levels of Ca, P and O. Since some of these electron-dense structures showed a banding pattern with periodicity of about 50 nm, they most likely represent calcified collagen fibers. Immunoelectron microscopy showed that the calcified structures were positive for collagen III. Remarkably, the elastic layer of BM appeared to have a normal ultrastructure, even in 2.5 year old Abcc6-/- mice. Our results suggest that Abcc6 deficiency in the mouse causes calcification of BM. While PXE is considered to affect primarily the elastic fibers, we found predominantly mineralization of collagen fibers.
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Affiliation(s)
- Theo G M F Gorgels
- Molecular Ophthalmogenetics, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands.
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Abstract
Artery calcification reflects an admixture of factors such as ectopic osteochondral differentiation with primary host pathological conditions. We review how genetic factors, as identified by human genome-wide association studies, and incomplete correlations with various mouse studies, including knockout and strain analyses, fit into "pieces of the puzzle" in intimal calcification in human atherosclerosis, and artery tunica media calcification in aging, diabetes mellitus, and chronic kidney disease. We also describe in sharp contrast how ENPP1, CD73, and ABCC6 serve as "cogs in a wheel" of arterial calcification. Specifically, each is a minor component in the function of a much larger network of factors that exert balanced effects to promote and suppress arterial calcification. For the network to normally suppress spontaneous arterial calcification, the "cogs" ENPP1, CD73, and ABCC6 must be present and in working order. Monogenic ENPP1, CD73, and ABCC6 deficiencies each drive a molecular pathophysiology of closely related but phenotypically different diseases (generalized arterial calcification of infancy (GACI), pseudoxanthoma elasticum (PXE) and arterial calcification caused by CD73 deficiency (ACDC)), in which premature onset arterial calcification is a prominent but not the sole feature.
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Affiliation(s)
- Frank Rutsch
- Department of General Pediatrics, Münster University Children's Hospital, Albert-Schweitzer-Campus 1, D-48149 Münster, Germany.
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Abstract
The final step of biomineralization is a chemical precipitation reaction that occurs spontaneously in supersaturated or metastable salt solutions. Genetic programs direct precursor cells into a mineralization-competent state in physiological bone formation (osteogenesis) and in pathological mineralization (ectopic mineralization or calcification). Therefore, all tissues not meant to mineralize must be actively protected against chance precipitation of mineral. Fetuin-A is a liver-derived blood protein that acts as a potent inhibitor of ectopic mineralization. Monomeric fetuin-A protein binds small clusters of calcium and phosphate. This interaction results in the formation of prenucleation cluster-laden fetuin-A monomers, calciprotein monomers, and considerably larger aggregates of protein and mineral calciprotein particles. Both monomeric and aggregate forms of fetuin-A mineral accrue acidic plasma protein including albumin, thus stabilizing supersaturated and metastable mineral ion solutions as colloids. Hence, fetuin-A is a mineral carrier protein and a systemic inhibitor of pathological mineralization complementing local inhibitors that act in a cell-restricted or tissue-restricted fashion. Fetuin-A deficiency is associated with soft tissue calcification in mice and humans.
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Uitto J, Bercovitch L, Terry SF, Terry PF. Pseudoxanthoma elasticum: progress in diagnostics and research towards treatment : Summary of the 2010 PXE International Research Meeting. Am J Med Genet A 2011; 155A:1517-26. [PMID: 21671388 PMCID: PMC3121926 DOI: 10.1002/ajmg.a.34067] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 03/25/2011] [Indexed: 11/07/2022]
Abstract
Pseudoxanthoma elasticum (PXE), a prototypic heritable disorder with ectopic mineralization, manifests with characteristic skin findings, ocular involvement, and cardiovascular problems. The classic forms of PXE are due to loss-of-function mutations in the ABCC6 gene, which encodes ABCC6, a putative transmembrane efflux transporter expressed primarily in the liver. While considerable progress has recently been made in understanding the molecular genetics and pathomechanisms of PXE, no effective or specific treatment is currently available for this disorder. PXE International, the premiere patient advocacy organization, organized a workshop in November 2010 to assess the current state of diagnostics and research to develop an agenda towards treatment of PXE. This overview summarizes the progress in PXE research, with emphasis on molecular therapies for this, currently intractable, disorder.
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Affiliation(s)
- Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
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Jiang Q, Li Q, Grand-Pierre AE, Schurgers LJ, Uitto J. Administration of vitamin K does not counteract the ectopic mineralization of connective tissues in Abcc6 (-/-) mice, a model for pseudoxanthoma elasticum. Cell Cycle 2011; 10:701-7. [PMID: 21304270 DOI: 10.4161/cc.10.4.14862] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a heritable multisystem disorder manifesting with ectopic calcification of peripheral connective tissues, caused by mutations in the ABCC6 gene. Alterations in vitamin K metabolism have been suggested to contribute to the pathomechanisms of the mineralization process. In this study we administered vitamin K or its glutathione conjugate (K3-GSH) into Abcc6 (-/-) mice which recapitulate features of PXE. Oral administration of vitamin K2 in dosages, which vastly exceed the amounts in control diet or the recommended amounts for humans, did not alter the ectopic mineralization in Abcc6 (-/-) mice. Similarly, intravenous administration of K3-GSH did not alter the degree of mineralization. Testing of vitamin K2, K3 and K3-GSH in an in vitro calcification system provided no evidence of mineralization inhibition. Collectively, our data suggest that vitamin K deficiency in the peripheral tissues is not a simple explanation for development of mineral deposits in PXE.
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Affiliation(s)
- Qiujie Jiang
- Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA, USA
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36
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Abstract
Pseudoxanthoma elasticum (PXE), a prototypic heritable disorder with ectopic mineralization, manifests with characteristic skin findings, ocular involvement and cardiovascular problems, with considerable morbidity and mortality. The classic forms of PXE are due to loss-of-function mutations in the ABCC6 gene, which encodes ABCC6, a transmembrane efflux transporter expressed primarily in the liver. Several lines of evidence suggest that PXE is a primary metabolic disorder, which in the absence of ABCC6 transporter activity, displays reduced plasma anti-mineralization capacity due to reduced fetuin-A and matrix gla-protein (MGP) levels. MGP requires to be activated by gamma-glutamyl carboxylation, a vitamin K-dependent reaction, to serve in an anti-mineralization role in the peripheral connective tissue cells. Although the molecules transported from the hepatocytes to circulation by ABCC6 in vivo remain unidentified, it has been hypothesized that a critical vitamin K derivative, such as reduced vitamin K conjugated with glutathione, is secreted to circulation physiologically, but not in the absence of ABCC6 transporter activity. As a result, activation of MGP by gamma-glutamyl carboxylase is diminished, allowing slow yet progressive mineralization of connective tissues characteristic of PXE. Understanding of the pathomechanistic details of PXE provides a basis for the development of targeted molecular therapies for this currently intractable disease.
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Affiliation(s)
- Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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