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Molin A. Human genetic diseases of phosphate and pyrophosphate metabolism. Arch Pediatr 2024; 31:4S13-4S20. [PMID: 39343468 DOI: 10.1016/s0929-693x(24)00152-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2024]
Abstract
In humans, physiological bone and tooth mineralization is a complex cell-mediated process. Prerequisites for proper mineralization include sufficient amounts of minerals (calcium and phosphate [Pi]) to initiate the formation and the growth of apatite crystals and adequate amounts of mineralization inhibitors, such as pyrophosphate (PPi), to prevent uncontrolled extraskeletal mineralization. In this review, we provide an overview of the genetics of human disorders of mineralization, focusing on Pi and PPi metabolism and transport diseases, as the Pi/PPi ratio is an important determinant of crystal production in vivo. Variants in genes implicated in the homeostasis of this ratio may lead to a systemic or local increased Pi/PPi ratio, either by increasing the Pi concentration or by decreasing the PPi concentration, resulting in ectopic calcifications; conversely, variants may lead to a decreased Pi/PPi ratio, resulting in defective mineralization. Owing to the implication of common pathways and, occasionally, to some extent of clinical overlap, an accurate diagnosis and understanding of the pathophysiology of these disorders may be challenging. However, precise molecular characterization of these conditions not only facilitates their diagnosis, but also helps to gather evidence regarding the pathophysiology and phenotype-genotype correlation to improve medical care and develop innovative therapeutics.
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Affiliation(s)
- Arnaud Molin
- Université de Caen Normandie, UFR Santé, CHU Caen Normandie, BIOTARGEN UR 7450, Centre de Référence Maladies rares du métabolisme du calcium et du phosphate, Service de Génétique, F-14000, Caen, France.
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2
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Wu A, Yang B, Yu X. A GALNT3 mutation causing Hyperphosphatemic familial Tumoral calcinosis. Mol Genet Metab Rep 2024; 40:101128. [PMID: 39185017 PMCID: PMC11342870 DOI: 10.1016/j.ymgmr.2024.101128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 07/26/2024] [Accepted: 07/27/2024] [Indexed: 08/27/2024] Open
Abstract
Aim Hyperphosphatemic Familial Tumoral Calcinosis (HFTC) is an autosomal recessive disorder. This study investigates the etiology of HFTC in offspring from consanguineous parents. Methods Clinical assessment, imaging, and direct sequencing were utilized to elucidate the condition. Previously reported cases were also reviewed. Result We identified a consanguineous Chinese family with HFTC caused by an interesting homozygous G to A substitution in GALNT3 (c.1626 + 1G > A). The parents were carriers. Conclusion This study represents the first report of HFTC in a consanguineous Chinese family due to an interesting GALNT3 mutation. We reviewed known GALNT3 variants and associated clinical features of calcification disorders. The phenotypic difference between homozygous and complex heterozygous mutations is not clinically significant. Gene mutations affect the function of proteins mainly by affecting their binding to polyvalent ligands.
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Affiliation(s)
- Aijia Wu
- Department of Endocrinology, Laboratory of Endocrinology and Metabolism, Rare Disease Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Bangxiang Yang
- Departement of Pain Management, West China Hospital, Sichuan University No 37, Guoxuexiang, Chengdu, Sichuan, PRC
| | - Xijie Yu
- Department of Endocrinology, Laboratory of Endocrinology and Metabolism, Rare Disease Center, West China Hospital, Sichuan University, Chengdu 610041, China
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Wynsberghe JV, Vanakker OM. Significance of Premature Vertebral Mineralization in Zebrafish Models in Mechanistic and Pharmaceutical Research on Hereditary Multisystem Diseases. Biomolecules 2023; 13:1621. [PMID: 38002303 PMCID: PMC10669475 DOI: 10.3390/biom13111621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
Zebrafish are increasingly becoming an important model organism for studying the pathophysiological mechanisms of human diseases and investigating how these mechanisms can be effectively targeted using compounds that may open avenues to novel treatments for patients. The zebrafish skeleton has been particularly instrumental in modeling bone diseases as-contrary to other model organisms-the lower load on the skeleton of an aquatic animal enables mutants to survive to early adulthood. In this respect, the axial skeletons of zebrafish have been a good read-out for congenital spinal deformities such as scoliosis and degenerative disorders such as osteoporosis and osteoarthritis, in which aberrant mineralization in humans is reflected in the respective zebrafish models. Interestingly, there have been several reports of hereditary multisystemic diseases that do not affect the vertebral column in human patients, while the corresponding zebrafish models systematically show anomalies in mineralization and morphology of the spine as their leading or, in some cases, only phenotype. In this review, we describe such examples, highlighting the underlying mechanisms, the already-used or potential power of these models to help us understand and amend the mineralization process, and the outstanding questions on how and why this specific axial type of aberrant mineralization occurs in these disease models.
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Affiliation(s)
- Judith Van Wynsberghe
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Ectopic Mineralization Research Group, 9000 Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Ectopic Mineralization Research Group, 9000 Ghent, Belgium
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Hassan N, Gregson CL, Tang H, van der Kamp M, Leo P, McInerney‐Leo AM, Zheng J, Brandi ML, Tang JCY, Fraser W, Stone MD, Grundberg E, Brown MA, Duncan EL, Tobias JH. Rare and Common Variants in GALNT3 May Affect Bone Mass Independently of Phosphate Metabolism. J Bone Miner Res 2023; 38:678-691. [PMID: 36824040 PMCID: PMC10729283 DOI: 10.1002/jbmr.4795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 02/25/2023]
Abstract
Anabolic treatment options for osteoporosis remain limited. One approach to discovering novel anabolic drug targets is to identify genetic causes of extreme high bone mass (HBM). We investigated a pedigree with unexplained HBM within the UK HBM study, a national cohort of probands with HBM and their relatives. Whole exome sequencing (WES) in a family with HBM identified a rare heterozygous missense variant (NM_004482.4:c.1657C > T, p.Arg553Trp) in GALNT3, segregating appropriately. Interrogation of data from the UK HBM study and the Anglo-Australasian Osteoporosis Genetics Consortium (AOGC) revealed an unrelated individual with HBM with another rare heterozygous variant (NM_004482.4:c.831 T > A, p.Asp277Glu) within the same gene. In silico protein modeling predicted that p.Arg553Trp would disrupt salt-bridge interactions, causing instability of GALNT3, and that p.Asp277Glu would disrupt manganese binding and consequently GALNT3 catalytic function. Bi-allelic loss-of-function GALNT3 mutations alter FGF23 metabolism, resulting in hyperphosphatemia and causing familial tumoral calcinosis (FTC). However, bone mineral density (BMD) in FTC cases, when reported, has been either normal or low. Common variants in the GALNT3 locus show genome-wide significant associations with lumbar, femoral neck, and total body BMD. However, no significant associations with BMD are observed at loci coding for FGF23, its receptor FGFR1, or coreceptor klotho. Mendelian randomization analysis, using expression quantitative trait loci (eQTL) data from primary human osteoblasts and genome-wide association studies data from UK Biobank, suggested increased expression of GALNT3 reduces total body, lumbar spine, and femoral neck BMD but has no effect on phosphate concentrations. In conclusion, rare heterozygous loss-of-function variants in GALNT3 may cause HBM without altering phosphate concentration. These findings suggest that GALNT3 may affect BMD through pathways other than FGF23 regulation, the identification of which may yield novel anabolic drug targets for osteoporosis. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Neelam Hassan
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
| | - Celia L. Gregson
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
| | - Haotian Tang
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
| | | | - Paul Leo
- Faculty of Health, Translational Genomics Group, Institute of Health and Biomedical InnovationQueensland University of TechnologyBrisbaneQueenslandAustralia
| | - Aideen M. McInerney‐Leo
- The Faculty of Medicine, Frazer InstituteThe University of QueenslandWoolloongabbaQueenslandAustralia
| | - Jie Zheng
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai National Clinical Research Center for metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR ChinaShanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
| | | | - Jonathan C. Y. Tang
- Norwich Medical SchoolUniversity of East AngliaNorwichUK
- Clinical Biochemistry, Departments of Laboratory MedicineNorfolk and Norwich University Hospital NHS Foundation TrustNorwichUK
| | - William Fraser
- Norwich Medical SchoolUniversity of East AngliaNorwichUK
- Department of Diabetes, Endocrinology and Clinical BiochemistryNorfolk and Norwich University Hospital NHS Foundation TrustNorwichUK
| | - Michael D. Stone
- University Hospital LlandoughCardiff & Vale University Health BoardCardiffUK
| | - Elin Grundberg
- Genomic Medicine CenterChildren's Mercy Kansas CityKansas CityMissouriUSA
| | | | | | - Emma L. Duncan
- Department of Twin Research and Genetic Epidemiology, School of Life Course & Population Sciences, Faculty of Life Sciences and MedicineKing's College LondonLondonUK
| | - Jonathan H. Tobias
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
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Kato K, Hansen L, Clausen H. Polypeptide N-acetylgalactosaminyltransferase-Associated Phenotypes in Mammals. Molecules 2021; 26:5504. [PMID: 34576978 PMCID: PMC8472655 DOI: 10.3390/molecules26185504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 01/31/2023] Open
Abstract
Mucin-type O-glycosylation involves the attachment of glycans to an initial O-linked N-acetylgalactosamine (GalNAc) on serine and threonine residues on proteins. This process in mammals is initiated and regulated by a large family of 20 UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) (EC 2.4.1.41). The enzymes are encoded by a large gene family (GALNTs). Two of these genes, GALNT2 and GALNT3, are known as monogenic autosomal recessive inherited disease genes with well characterized phenotypes, whereas a broad spectrum of phenotypes is associated with the remaining 18 genes. Until recently, the overlapping functionality of the 20 members of the enzyme family has hindered characterizing the specific biological roles of individual enzymes. However, recent evidence suggests that these enzymes do not have full functional redundancy and may serve specific purposes that are found in the different phenotypes described. Here, we summarize the current knowledge of GALNT and associated phenotypes.
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Affiliation(s)
- Kentaro Kato
- Department of Eco-Epidemiology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Lars Hansen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Mærsk Building, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark;
| | - Henrik Clausen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Mærsk Building, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark;
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6
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Chakhtoura M, Ramnitz MS, Khoury N, Nemer G, Shabb N, Abchee A, Berberi A, Hourani M, Collins M, Ichikawa S, El Hajj Fuleihan G. Hyperphosphatemic familial tumoral calcinosis secondary to fibroblast growth factor 23 (FGF23) mutation: a report of two affected families and review of the literature. Osteoporos Int 2018; 29:1987-2009. [PMID: 29923062 DOI: 10.1007/s00198-018-4574-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 05/14/2018] [Indexed: 01/20/2023]
Abstract
Hyperphosphatemic familial tumoral calcinosis (HFTC), secondary to fibroblast growth factor 23 (FGF23) gene mutation, is a rare genetic disorder characterized by recurrent calcified masses. We describe young Lebanese cousins presenting with HFTC, based on a retrospective chart review and a prospective case study. In addition, we present a comprehensive review on the topic, based on a literature search conducted in PubMed and Google Scholar, in 2014 and updated in December 2017. While the patients had the same previously reported FGF23 gene mutation (homozygous c.G367T variant in exon 3 leading to a missense mutation), they presented with variable severity and age of disease onset (at 4 years in patient 1 and at 23 years in patient 2). A review of the literature revealed several potential patho-physiologic pathways of HFTC clinical manifestations, some of which may be independent of hyperphosphatemia. Most available treatment options aim at reducing serum phosphate level, by stimulating renal excretion or by inhibiting intestinal absorption. HFTC is a challenging disease. While the available medical treatment has a limited and inconsistent effect on disease symptomatology, surgical resection of calcified masses remains the last resort. Research is needed to determine the safety and efficacy of FGF23 replacement or molecular therapy, targeting the specific genetic aberration. Hyperphosphatemic familial tumoral calcinosis is a rare genetic disorder characterized by recurrent calcified masses, in addition to other visceral, skeletal, and vascular manifestations. It remains a very challenging disease.
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Affiliation(s)
- M Chakhtoura
- Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon.
| | - M S Ramnitz
- Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - N Khoury
- Department of Radiology, American University of Beirut Medical Center, Beirut, Lebanon
| | - G Nemer
- Department of Biochemistry and Molecular Genetics, American University of Beirut Medical Center, Beirut, Lebanon
| | - N Shabb
- Department of Pathology and Laboratory Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - A Abchee
- Department of Internal Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - A Berberi
- Department of Internal Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - M Hourani
- Department of Radiology, American University of Beirut Medical Center, Beirut, Lebanon
| | - M Collins
- Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - S Ichikawa
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - G El Hajj Fuleihan
- Calcium Metabolism and Osteoporosis Program, WHO Collaborating Center for Metabolic Bone Disorders, American University of Beirut Medical Center, Beirut, Lebanon
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EFEMP2 Mediates GALNT14-Dependent Breast Cancer Cell Invasion. Transl Oncol 2018; 11:346-352. [PMID: 29428518 PMCID: PMC5884205 DOI: 10.1016/j.tranon.2018.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/09/2018] [Accepted: 01/16/2018] [Indexed: 01/21/2023] Open
Abstract
N-Acetylgalactosaminyltransferase-14 (GALNT14) is a member of acetylgalactosaminyltransferases family. We have shown that GALNT14 could promote breast cancer cell invasion. However, the underlying molecular mechanism is unclear. Here, using yeast two hybrid, we find that EGF-containing fibulin-like extracellular matrix protein 2 (EFEMP2) interacts with GALNT14. Both in vitro and in vivo binding assays show that EFEMP2 is associated with GALNT14. Moreover, we find that GALNT14 mediates glycosylation of EFEMP2. EFEMP2 significantly increased the invasion ability of breast cancer cells including MCF-7 and MBA-MD-231 cells, and this phenomenon is suppressed by knockdown expression of GALNT14. In addition, the GALNT14-dependent O-glycosylation of EFEMP-2 regulates the stability of EFEMP-2 protein in breast cancer cells. Taken together, our results demonstrate a novel molecular mechanism underlying breast cancer invasion.
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Yumusak E, Mutlu FM, Gok F. An Unusual Cause of Pseudopapillary Oedema: Hyperphosphatemic Hyperostosis Syndrome. Ophthalmic Genet 2016; 37:238-41. [DOI: 10.3109/13816810.2015.1033559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Erhan Yumusak
- Department of Ophthalmology, University of Kirikkale, Kirikkale, Turkey,
| | | | - Faysal Gok
- Department of Paediatry, Gulhane Military Medical Academy, Ankara, Turkey
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Rafaelsen S, Johansson S, Ræder H, Bjerknes R. Long-term clinical outcome and phenotypic variability in hyperphosphatemic familial tumoral calcinosis and hyperphosphatemic hyperostosis syndrome caused by a novel GALNT3 mutation; case report and review of the literature. BMC Genet 2014; 15:98. [PMID: 25249269 PMCID: PMC4181413 DOI: 10.1186/s12863-014-0098-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 09/04/2014] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Hyperphosphatemic Familial Tumoral Calcinosis (HFTC) and Hyperphosphatemic Hyperostosis Syndrome (HHS) are associated with autosomal recessive mutations in three different genes, FGF23, GALNT3 and KL, leading to reduced levels of fibroblast growth factor 23 (FGF23) and subsequent clinical effects. RESULTS We describe a consanguineous family with two affected siblings with HFTC and HHS caused by a novel homozygous G-to T substitution in exon 3 of GALNT3 (c.767 G > T; p.Gly256Val), demonstrating great phenotypic variation and long asymptomatic intervals. Calcific tumors appeared at 14 years of age in the male, and the female displayed episodic diaphysitis from age 9 years. Symptoms of eye involvement were present in both from childhood, and progressed into band keratopathy in the female. Abnormal dental roots and tooth loss, as well as myalgia were present in both from their mid-twenties, while the female also had calcifications in the placenta, the iliac vessels and thyroid cartilage. New calcific tumors appeared more than 20 years after the initial episodes, delaying diagnosis and treatment until the ages of 37 and 50 years, respectively. Both siblings had elevated serum phosphate levels, inappropriately elevated tubular maximum phosphate reabsorption per unit glomerular filtration rate (TmP/GFR), reduced levels of intact FGF23 and increased levels of c-terminal FGF23. Review of all 54 previously published cases of GALNT3, FGF23, and KL associated HFTC and HHS demonstrated that more subjects than previously recognized have a combined phenotype. CONCLUSION We have described HFTC and HHS in a consanguineous Caucasian family with a novel GALNT3 mutation, demonstrating new phenotypic features and significant variability in the natural course of the disease. A review of the literature, show that more subjects than previously recognized have a combined phenotype of HFTC and HHS. HHS and HFTC are two distinct phenotypes in a spectrum of GALNT3 mutation related calcification disorders, where the additional factors determining the phenotypic expression, are yet to be clarified.
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Affiliation(s)
- Silje Rafaelsen
- />Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Stefan Johansson
- />Department of Clinical Science, University of Bergen, Bergen, Norway
- />Center of Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Helge Ræder
- />Department of Clinical Science, University of Bergen, Bergen, Norway
- />Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Robert Bjerknes
- />Department of Clinical Science, University of Bergen, Bergen, Norway
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Abstract
This is the continuation of a two-part review of rickets. This part emphasizes the specific pathophysiology, clinical features, pathoanatomy and radiographic findings of vitamin D deficiency rickets. Other forms of rickets, differential diagnostic considerations and the potential relationship between low levels of vitamin D metabolites and unexplained fractures in infants are also discussed.
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Schjoldager KTBG, Clausen H. Site-specific protein O-glycosylation modulates proprotein processing - deciphering specific functions of the large polypeptide GalNAc-transferase gene family. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1820:2079-94. [PMID: 23022508 DOI: 10.1016/j.bbagen.2012.09.014] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 09/17/2012] [Accepted: 09/19/2012] [Indexed: 01/18/2023]
Abstract
BACKGROUND Posttranslational modifications (PTMs) greatly expand the function and regulation of proteins, and glycosylation is the most abundant and diverse PTM. Of the many different types of protein glycosylation, one is quite unique; GalNAc-type (or mucin-type) O-glycosylation, where biosynthesis is initiated in the Golgi by up to twenty distinct UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). These GalNAc-Ts are differentially expressed in cells and have different (although partly overlapping) substrate specificities, which provide for both unique functions and considerable redundancy. Recently we have begun to uncover human diseases associated with deficiencies in GalNAc-T genes (GALNTs). Thus deficiencies in individual GALNTs produce cell and protein specific effects and subtle distinct phenotypes such as hyperphosphatemia with hyperostosis (GALNT3) and dysregulated lipid metabolism (GALNT2). These phenotypes appear to be caused by deficient site-specific O-glycosylation that co-regulates proprotein convertase (PC) processing of FGF23 and ANGPTL3, respectively. SCOPE OF REVIEW Here we summarize recent progress in uncovering the interplay between human O-glycosylation and protease regulated processing and describes other important functions of site-specific O-glycosylation in health and disease. MAJOR CONCLUSIONS Site-specific O-glycosylation modifies pro-protein processing and other proteolytic events such as ADAM processing and thus emerges as an important co-regulator of limited proteolytic processing events. GENERAL SIGNIFICANCE Our appreciation of this function may have been hampered by our sparse knowledge of the O-glycoproteome and in particular sites of O-glycosylation. New strategies for identification of O-glycoproteins have emerged and recently the concept of SimpleCells, i.e. human cell lines made deficient in O-glycan extension by zinc finger nuclease gene targeting, was introduced for broad O-glycoproteome analysis.
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Esapa CT, Head RA, Jeyabalan J, Evans H, Hough TA, Cheeseman MT, McNally EG, Carr AJ, Thomas GP, Brown MA, Croucher PI, Brown SDM, Cox RD, Thakker RV. A mouse with an N-Ethyl-N-nitrosourea (ENU) Induced Trp589Arg Galnt3 mutation represents a model for hyperphosphataemic familial tumoural calcinosis. PLoS One 2012; 7:e43205. [PMID: 22912827 PMCID: PMC3418237 DOI: 10.1371/journal.pone.0043205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 07/18/2012] [Indexed: 01/09/2023] Open
Abstract
Mutations of UDP-N-acetyl-alpha-D-galactosamine polypeptide N-acetyl galactosaminyl transferase 3 (GALNT3) result in familial tumoural calcinosis (FTC) and the hyperostosis-hyperphosphataemia syndrome (HHS), which are autosomal recessive disorders characterised by soft-tissue calcification and hyperphosphataemia. To facilitate in vivo studies of these heritable disorders of phosphate homeostasis, we embarked on establishing a mouse model by assessing progeny of mice treated with the chemical mutagen N-ethyl-N-nitrosourea (ENU), and identified a mutant mouse, TCAL, with autosomal recessive inheritance of ectopic calcification, which involved multiple tissues, and hyperphosphataemia; the phenotype was designated TCAL and the locus, Tcal. TCAL males were infertile with loss of Sertoli cells and spermatozoa, and increased testicular apoptosis. Genetic mapping localized Tcal to chromosome 2 (62.64-71.11 Mb) which contained the Galnt3. DNA sequence analysis identified a Galnt3 missense mutation (Trp589Arg) in TCAL mice. Transient transfection of wild-type and mutant Galnt3-enhanced green fluorescent protein (EGFP) constructs in COS-7 cells revealed endoplasmic reticulum retention of the Trp589Arg mutant and Western blot analysis of kidney homogenates demonstrated defective glycosylation of Galnt3 in Tcal/Tcal mice. Tcal/Tcal mice had normal plasma calcium and parathyroid hormone concentrations; decreased alkaline phosphatase activity and intact Fgf23 concentrations; and elevation of circulating 1,25-dihydroxyvitamin D. Quantitative reverse transcriptase-PCR (qRT-PCR) revealed that Tcal/Tcal mice had increased expression of Galnt3 and Fgf23 in bone, but that renal expression of Klotho, 25-hydroxyvitamin D-1α-hydroxylase (Cyp27b1), and the sodium-phosphate co-transporters type-IIa and -IIc was similar to that in wild-type mice. Thus, TCAL mice have the phenotypic features of FTC and HHS, and provide a model for these disorders of phosphate metabolism.
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Affiliation(s)
- Christopher T. Esapa
- Academic Endocrine Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, United Kingdom
- Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, United Kingdom
| | - Rosie A. Head
- Academic Endocrine Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, United Kingdom
- Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, United Kingdom
| | - Jeshmi Jeyabalan
- Academic Endocrine Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, United Kingdom
| | - Holly Evans
- The Mellanby Centre for Bone Research, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - Tertius A. Hough
- Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, United Kingdom
| | - Michael T. Cheeseman
- Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, United Kingdom
| | - Eugene G. McNally
- Department of Radiology, Nuffield Orthopaedic Centre and Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, United Kingdom
| | - Andrew J. Carr
- NIHR Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, United Kingdom
| | - Gethin P. Thomas
- University of Queensland Diamantina Institute, Princess Alexandra Hospital, University of Queensland, Australia
| | - Matthew A. Brown
- University of Queensland Diamantina Institute, Princess Alexandra Hospital, University of Queensland, Australia
| | - Peter I. Croucher
- The Mellanby Centre for Bone Research, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom
- Garvan Institute for Medical Research, Sydney, Australia
| | - Steve D. M. Brown
- Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, United Kingdom
| | - Roger D. Cox
- Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre, MRC Harwell, Harwell Science and Innovation Campus, United Kingdom
| | - Rajesh V. Thakker
- Academic Endocrine Unit, Nuffield Department of Clinical Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, United Kingdom
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Yancovitch A, Hershkovitz D, Indelman M, Galloway P, Whiteford M, Sprecher E, Kılıç E. Novel mutations in GALNT3 causing hyperphosphatemic familial tumoral calcinosis. J Bone Miner Metab 2011; 29:621-5. [PMID: 21347749 DOI: 10.1007/s00774-011-0260-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 01/06/2011] [Indexed: 01/29/2023]
Abstract
Hyperphosphatemic familial tumoral calcinosis (HFTC) is known to be caused by mutations in at least three genes: FGF23, GALNT3 and KL. Two families with two affected members suffering from HFTC were scrutinized for mutations in these candidate genes. We identified in both families homozygous missense mutations affecting highly conserved amino acids in GALNT3. One of the mutations is a novel mutation, whereas the second mutation was reported before in a compound heterozygous state. Our data expand the spectrum of known mutations in GALNT3 and contribute to a better understanding of the phenotypic manifestations of mutations in this gene.
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Affiliation(s)
- Alan Yancovitch
- Center for Translational Genetics, Rappaport Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Abstract
PURPOSE OF REVIEW The study of phosphorus physiology and investigations into clinical disorders of phosphorus metabolism has blossomed over the past decade. Recent work has confirmed and further extended our knowledge of basic mechanisms of phosphorus metabolism. RECENT FINDINGS This review will focus on FGF-23 and Klotho, and on the recent further dissection of their roles in phosphorus and skeletal metabolism. Additionally, this review will detail recent studies that implicate a role for these phosphaturic and vitamin D regulating factors in extraskeletal calcification, including that occurring in soft tissue and vascular beds. SUMMARY These findings in total provide fertile ground for investigations into the cause and treatment of abnormal skeletal and extraskeletal calcification in patients with inherited hypophosphatemic disorders. More importantly, and certainly with wider potential clinical application, these studies likewise imply a role for these factors in the pathogenesis of accelerated cardiovascular disease that occurs in patients with the most common hyperphosphatemic disorder, chronic kidney disease. Future studies are needed to confirm a harmful or possibly even beneficial role for FGF-23 and other factors in these disease states, and to determine whether therapeutic manipulation of these factors does truly affect clinical outcomes in patients with hypophosphatemia and hyperphosphatemia.
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Affiliation(s)
- Richard Lee
- Division of Endocrinology, Metabolism and Nutrition, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
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15
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Ichikawa S, Baujat G, Seyahi A, Garoufali AG, Imel EA, Padgett LR, Austin AM, Sorenson AH, Pejin Z, Topouchian V, Quartier P, Cormier-Daire V, Dechaux M, Malandrinou FC, Singhellakis PN, Le Merrer M, Econs MJ. Clinical variability of familial tumoral calcinosis caused by novel GALNT3 mutations. Am J Med Genet A 2010; 152A:896-903. [PMID: 20358599 PMCID: PMC3392654 DOI: 10.1002/ajmg.a.33337] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The GALNT3 gene encodes GalNAc-T3, which prevents degradation of the phosphaturic hormone, fibroblast growth factor 23 (FGF23). Biallelic mutations in either GALNT3 or FGF23 result in hyperphosphatemic familial tumoral calcinosis or its variant, hyperostosis-hyperphosphatemia syndrome. Tumoral calcinosis is characterized by the presence of ectopic calcifications around major joints, whereas hyperostosis-hyperphosphatemia syndrome is characterized by recurrent long bone lesions with hyperostosis. Here we investigated four patients with hyperphosphatemia and clinical manifestations including tumoral calcinosis and/or hyperostosis-hyperphosphatemia syndrome to determine underlying genetic cause and delineate phenotypic heterogeneity of these disorders. Mutational analysis of FGF23 and GALNT3 in these patients revealed novel homozygous mutations in GALNT3. Although the presence of massive calcifications, cortical hyperostosis, or dental anomalies was not shared by all patients, all had persistent hyperphosphatemia. Three of the patients also had inappropriately normal 1,25-dihyroxyvitamin D [1,25(OH)(2)D] and confirmed low circulating intact FGF23 concentrations. The four novel GALNT3 mutations invariably resulted in hyperphosphatemia as a result of low intact FGF23, but other clinical manifestations were variable. Therefore, tumoral calcinosis and hyperostosis-hyperphosphatemia syndrome represent a continuous spectrum of the same disease caused by increased phosphate levels, rather than two distinct disorders.
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Affiliation(s)
- Shoji Ichikawa
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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Sprecher E. Familial tumoral calcinosis: from characterization of a rare phenotype to the pathogenesis of ectopic calcification. J Invest Dermatol 2010; 130:652-60. [PMID: 19865099 PMCID: PMC3169303 DOI: 10.1038/jid.2009.337] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Familial tumoral calcinosis (FTC) refers to a heterogeneous group of inherited disorders characterized by the occurrence of cutaneous and subcutaneous calcified masses. Two major forms of the disease are now recognized. Hyperphosphatemic FTC has been shown to result from mutations in three genes: fibroblast growth factor-23 (FGF23), coding for a potent phosphaturic protein, KL encoding Klotho, which serves as a co-receptor for FGF23, and GALNT3, which encodes a glycosyltransferase responsible for FGF23 O-glycosylation; defective function of any one of these three proteins results in hyperphosphatemia and ectopic calcification. The second form of the disease is characterized by absence of metabolic abnormalities, and is, therefore, termed normophosphatemic FTC. This variant was found to be associated with absence of functional SAMD9, a putative tumor suppressor and anti-inflammatory protein. The data gathered through the study of these rare disorders have recently led to the discovery of novel aspects of the pathogenesis of common disorders in humans, underscoring the potential concealed within the study of rare diseases.
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Affiliation(s)
- Eli Sprecher
- Department of Dermatology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
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