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Kauffenstein G, Martin L, Le Saux O. The Purinergic Nature of Pseudoxanthoma Elasticum. BIOLOGY 2024; 13:74. [PMID: 38392293 PMCID: PMC10886499 DOI: 10.3390/biology13020074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/13/2024] [Accepted: 01/19/2024] [Indexed: 02/24/2024]
Abstract
Pseudoxanthoma Elasticum (PXE) is an inherited disease characterized by elastic fiber calcification in the eyes, the skin and the cardiovascular system. PXE results from mutations in ABCC6 that encodes an ABC transporter primarily expressed in the liver and kidneys. It took nearly 15 years after identifying the gene to better understand the etiology of PXE. ABCC6 function facilitates the efflux of ATP, which is sequentially hydrolyzed by the ectonucleotidases ENPP1 and CD73 into pyrophosphate (PPi) and adenosine, both inhibitors of calcification. PXE, together with General Arterial Calcification of Infancy (GACI caused by ENPP1 mutations) as well as Calcification of Joints and Arteries (CALJA caused by NT5E/CD73 mutations), forms a disease continuum with overlapping phenotypes and shares steps of the same molecular pathway. The explanation of these phenotypes place ABCC6 as an upstream regulator of a purinergic pathway (ABCC6 → ENPP1 → CD73 → TNAP) that notably inhibits mineralization by maintaining a physiological Pi/PPi ratio in connective tissues. Based on a review of the literature and our recent experimental data, we suggest that PXE (and GACI/CALJA) be considered as an authentic "purinergic disease". In this article, we recapitulate the pathobiology of PXE and review molecular and physiological data showing that, beyond PPi deficiency and ectopic calcification, PXE is associated with wide and complex alterations of purinergic systems. Finally, we speculate on the future prospects regarding purinergic signaling and other aspects of this disease.
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Affiliation(s)
- Gilles Kauffenstein
- UMR INSERM 1260, Regenerative Nanomedicine, University of Strasbourg, 67084 Strasbourg, France
| | - Ludovic Martin
- PXE Consultation Center, MAGEC Nord Reference Center for Rare Skin Diseases, Angers University Hospital, 49000 Angers, France
- MITOVASC-UMR CNRS 6015 INSERM 1083, University of Angers, 49000 Angers, France
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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Wu F, Mukai S. Refractory Choroidal Neovascularization in a Patient With Pseudoxanthoma Elasticum and Cowden Syndrome. JOURNAL OF VITREORETINAL DISEASES 2023; 7:70-73. [PMID: 37008396 PMCID: PMC9954156 DOI: 10.1177/24741264221117013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Purpose To describe a patient with concurrent pseudoxanthoma elasticum (PXE) and Cowden syndrome who developed choroidal neovascularization (CNV) secondary to angioid streaks. The CNV presented at a young age and was relatively refractory to intravitreal antivascular endothelial growth factor (anti-VEGF) therapy. Methods A retrospective chart review was performed. Results A 32-year-old man was treated for bilateral sequential CNV over 11 years. Good visual acuity was maintained with 53 anti-VEGF injections in the right eye and 82 injections in the left eye. On average, 1 injection was administered every 1.7 months in each eye to control the exudation. A skin biopsy and genetic testing confirmed a diagnosis of PXE. He was also found to harbor a PTEN mutation consistent with Cowden syndrome. Conclusions The concurrent PTEN mutation lends a possible explanation for the relative resistance of CNV to anti-VEGF therapy in this patient with PXE. Phosphatase and tensin homolog is a tumor suppressor that negatively regulates the VEGF pathway.
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Affiliation(s)
- Frances Wu
- Retina Service, Massachusetts Eye and Ear,
Boston, MA, USA
- Department of Ophthalmology, Harvard Medical
School, Boston, MA, USA
| | - Shizuo Mukai
- Retina Service, Massachusetts Eye and Ear,
Boston, MA, USA
- Department of Ophthalmology, Harvard Medical
School, Boston, MA, USA
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De Vilder EYG, Martin L, Lefthériotis G, Coucke P, Van Nieuwerburgh F, Vanakker OM. Rare Modifier Variants Alter the Severity of Cardiovascular Disease in Pseudoxanthoma Elasticum: Identification of Novel Candidate Modifier Genes and Disease Pathways Through Mixture of Effects Analysis. Front Cell Dev Biol 2021; 9:612581. [PMID: 34169069 PMCID: PMC8218811 DOI: 10.3389/fcell.2021.612581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 05/11/2021] [Indexed: 12/30/2022] Open
Abstract
Introduction: Pseudoxanthoma elasticum (PXE), an ectopic mineralization disorder caused by pathogenic ABCC6 variants, is characterized by skin, ocular and cardiovascular (CV) symptoms. Due to striking phenotypic variability without genotype-phenotype correlations, modifier genes are thought to play a role in disease variability. In this study, we evaluated the collective modifying effect of rare variants on the cardiovascular phenotype of PXE. Materials and Methods: Mixed effects of rare variants were assessed by Whole Exome Sequencing in 11 PXE patients with an extreme CV phenotype (mild/severe). Statistical analysis (SKAT-O and C-alpha testing) was performed to identify new modifier genes for the CV PXE phenotype and enrichment analysis for genes significantly associated with the severe cohort was used to evaluate pathway and gene ontology features. Results Respectively 16 (SKAT-O) and 74 (C-alpha) genes were significantly associated to the severe cohort. Top significant genes could be stratified in 3 groups–calcium homeostasis, association with vascular disease and induction of apoptosis. Comparative analysis of both analyses led to prioritization of four genes (NLRP1, SELE, TRPV1, and CSF1R), all signaling through IL-1B. Conclusion This study explored for the first time the cumulative effect of rare variants on the severity of cardiovascular disease in PXE, leading to a panel of novel candidate modifier genes and disease pathways. Though further validation is essential, this panel may aid in risk stratification and genetic counseling of PXE patients and will help to gain new insights in the PXE pathophysiology.
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Affiliation(s)
- Eva Y G De Vilder
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,The Research Foundation - Flanders, Ghent, Belgium.,Department of Ophthalmology, Ghent University Hospital, Ghent, Belgium
| | - Ludovic Martin
- Department of Dermatology, Angers University Hospital, Angers, France
| | - Georges Lefthériotis
- Department of Vascular Physiology and Sports Medicine, Angers University, Angers, France
| | - Paul Coucke
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
| | - Filip Van Nieuwerburgh
- Department of Pharmaceutics, Laboratory of Pharmaceutical Biotechnology, Ghent University, Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.,Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
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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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Bartstra JW, Risseeuw S, de Jong PA, van Os B, Kalsbeek L, Mol C, Baas AF, Verschuere S, Vanakker O, Florijn RJ, Hendrikse J, Mali W, Imhof S, Ossewaarde-van Norel J, van Leeuwen R, Spiering W. Genotype-phenotype correlation in pseudoxanthoma elasticum. Atherosclerosis 2021; 324:18-26. [PMID: 33812167 DOI: 10.1016/j.atherosclerosis.2021.03.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/26/2021] [Accepted: 03/10/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND AIMS Pseudoxanthoma elasticum (PXE) is caused by variants in the ABCC6 gene. It results in calcification in the skin, peripheral arteries and the eyes, but has considerable phenotypic variability. We investigated the association between the ABCC6 genotype and calcification and clinical phenotypes in these different organs. METHODS ABCC6 sequencing was performed in 289 PXE patients. Genotypes were grouped as two truncating, mixed, or two non-truncating variants. Arterial calcification mass was quantified on whole body, low dose CT scans; and peripheral arterial disease was measured with the ankle brachial index after treadmill test. The presence of pseudoxanthoma in the skin was systematically scored. Ophthalmological phenotypes were the length of angioid streaks as a measure of Bruchs membrane calcification, the presence of choroidal neovascularizations, severity of macular atrophy and visual acuity. Regression models were built to test the age and sex adjusted genotype-phenotype association. RESULTS 158 patients (median age 51 years) had two truncating variants, 96 (median age 54 years) a mixed genotype, 18 (median age 47 years) had two non-truncating variants. The mixed genotype was associated with lower peripheral (β: 0.39, 95%CI:-0.62;-0.17) and total (β: 0.28, 95%CI:-0.47;-0.10) arterial calcification mass scores, and lower prevalence of choroidal neovascularizations (OR: 0.41 95%CI:0.20; 0.83) compared to two truncating variants. No association with pseudoxanthomas was found. CONCLUSIONS PXE patients with a mixed genotype have less severe arterial and ophthalmological phenotypes than patients with two truncating variants in the ABCC6 gene. Research into environmental and genetic modifiers might provide further insights into the unexplained phenotypic variability.
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Affiliation(s)
- Jonas W Bartstra
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Sara Risseeuw
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Pim A de Jong
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Bram van Os
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Lianne Kalsbeek
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Chris Mol
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Annette F Baas
- Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Shana Verschuere
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Olivier Vanakker
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Ralph J Florijn
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, the Netherlands
| | - Jeroen Hendrikse
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Willem Mali
- Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Saskia Imhof
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | | | - Redmer van Leeuwen
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, the Netherlands.
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Molecular Genetics and Modifier Genes in Pseudoxanthoma Elasticum, a Heritable Multisystem Ectopic Mineralization Disorder. J Invest Dermatol 2020; 141:1148-1156. [PMID: 33341249 DOI: 10.1016/j.jid.2020.10.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 10/19/2020] [Accepted: 10/23/2020] [Indexed: 01/08/2023]
Abstract
In the past two decades, there has been great progress in identifying the molecular basis and pathomechanistic details in pseudoxanthoma elasticum (PXE), a heritable multisystem ectopic mineralization disorder. Although the identification of pathogenic variants in ABCC6 has been critical for understanding the disease process, genetic modifiers have been disclosed that explain the phenotypic heterogeneity of PXE. Adding to the genetic complexity of PXE are PXE-like phenotypes caused by pathogenic variants in other ectopic mineralization-associated genes. This review summarizes the current knowledge of the genetics and candidate modifier genes in PXE, a multifactorial disease at the genome-environment interface.
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Verschuere S, Van Gils M, Nollet L, Vanakker OM. From membrane to mineralization: the curious case of the ABCC6 transporter. FEBS Lett 2020; 594:4109-4133. [PMID: 33131056 DOI: 10.1002/1873-3468.13981] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/12/2020] [Accepted: 10/16/2020] [Indexed: 12/13/2022]
Abstract
ATP-binding cassette subfamily C member 6 gene/protein (ABCC6) is an ATP-dependent transmembrane transporter predominantly expressed in the liver and the kidney. ABCC6 first came to attention in human medicine when it was discovered in 2000 that mutations in its encoding gene, ABCC6, caused the autosomal recessive multisystemic mineralization disease pseudoxanthoma elasticum (PXE). Since then, the physiological and pathological roles of ABCC6 have been the subject of intense research. In the last 20 years, significant findings have clarified ABCC6 structure as well as its physiological role in mineralization homeostasis in humans and animal models. Yet, several facets of ABCC6 biology remain currently incompletely understood, ranging from the precise nature of its substrate(s) to the increasingly complex molecular genetics. Nonetheless, advances in our understanding of pathophysiological mechanisms causing mineralization lead to several treatment options being suggested or already tested in pilot clinical trials for ABCC6 deficiency. This review highlights current knowledge of ABCC6 and the challenges ahead, particularly the attempts to translate basic science into clinical practice.
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Affiliation(s)
- Shana Verschuere
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
| | - Matthias Van Gils
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
| | - Lukas Nollet
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, Belgium.,Department of Biomolecular Medicine, Ghent University, Belgium.,Ectopic Mineralization Research Group Ghent, Ghent, Belgium
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Rutsch F, Buers I, Nitschke Y. Hereditary Disorders of Cardiovascular Calcification. Arterioscler Thromb Vasc Biol 2020; 41:35-47. [PMID: 33176451 DOI: 10.1161/atvbaha.120.315577] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Arterial calcification is a common phenomenon in the elderly, in patients with atherosclerosis or renal failure and in diabetes. However, when present in very young individuals, it is likely to be associated with an underlying hereditary disorder of arterial calcification. Here, we present an overview of the few monogenic disorders presenting with early-onset cardiovascular calcification. These disorders can be classified according to the function of the respective disease gene into (1) disorders caused by an altered purine and phosphate/pyrophosphate metabolism, (2) interferonopathies, and (3) Gaucher disease. The finding of arterial calcification in early life should alert the clinician and prompt further genetic work-up to define the underlying genetic defect, to establish the correct diagnosis, and to enable appropriate therapy.
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Affiliation(s)
- Frank Rutsch
- Department of General Pediatrics, Muenster University Children's Hospital, Germany
| | - Insa Buers
- Department of General Pediatrics, Muenster University Children's Hospital, Germany
| | - Yvonne Nitschke
- Department of General Pediatrics, Muenster University Children's Hospital, Germany
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