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Liu P, Li J, Tang L, Cong W, Jin H, Zhang H, Cui B, Yang S, Xiao J, Liu C, Saiyin W. Mutations of family with sequence similarity 20-member C gene causing lethal and nonlethal Raine syndrome causes hypophosphatemia rickets. J Cell Physiol 2023; 238:2556-2569. [PMID: 37698039 DOI: 10.1002/jcp.31105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 09/13/2023]
Abstract
Family with sequence similarity 20-member C (FAM20C) is a kinase specific to most of the secreted phosphoproteome. FAM20C has been identified as the causative gene of Raine syndrome, initially characterized by lethal osteosclerosis bone dysplasia. However, since the identification of the cases of nonlethal Raine syndrome characterized by hypophosphatemia rickets, the previous definition of Raine syndrome has become debatable and raised a question about the role of mutations of FAM20C in controversial skeletal manifestation in the two forms of the disease. In this study, we aimed to investigate the influence of FAM20C mutations on skeletogenesis. We developed transgenic mice expressing Fam20c mutations mimicking those associated with human lethal and nonlethal Raine syndrome. The results revealed that transgenic mice expressing the mutant Fam20c found in the lethal (KO;G374R) and nonlethal (KO;D446N) Raine syndrome exhibited osteomalacia without osteosclerotic features. Additionally, both mutants significantly increased the expression of the Fgf23, indicating that Fam20c deficiency in skeletal compartments causes hypophosphatemia rickets. Furthermore, as FAM20C kinase activity catalyzes the phosphorylation of secreted proteomes other than those in the skeletal system, global FAM20C deficiency may trigger alterations in other systems resulting in osteosclerosis secondary to hypophosphatemia rickets. Together, the findings of this study suggest that FAM20C deficiency primarily causes hypophosphatemia rickets or osteomalacia; however, the heterogeneous skeletal manifestation in Raine syndrome was not determined solely by specific mutations of FAM20C. The findings also implicated that rickets or osteomalacia caused by FAM20C deficiency would deteriorate into osteosclerosis by the defects from other systems or environmental impacts.
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Affiliation(s)
- Peihong Liu
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
- Laboratory of Longjiang Scholar, The First Affifiliated Hospital of Harbin Medical University, Harbin, China
| | - Jiaxuan Li
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Linghao Tang
- Department of Otorhinolaryngology, The First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Wei Cong
- Department of Oral Pathology, School of Stomatology, Dalian Medical University, Dalian, China
| | - Han Jin
- Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Hong Zhang
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Bing Cui
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shan Yang
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Jing Xiao
- Department of Oral Pathology, School of Stomatology, Dalian Medical University, Dalian, China
| | - Chao Liu
- Department of Oral Pathology, School of Stomatology, Dalian Medical University, Dalian, China
| | - Wuliji Saiyin
- Department of Stomatology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
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Zhang H, Xiang G, Li J, He S, Wang Y, Deng A, Wang Y, Guo C. Promotion effect of FGF23 on osteopenia in congenital scoliosis through FGFr3/TNAP/OPN pathway. Chin Med J (Engl) 2023; 136:1468-1477. [PMID: 37192015 PMCID: PMC10278695 DOI: 10.1097/cm9.0000000000002690] [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: 11/09/2022] [Indexed: 05/18/2023] Open
Abstract
BACKGROUND Congenital scoliosis (CS) is a complex spinal malformation of unknown etiology with abnormal bone metabolism. Fibroblast growth factor 23 (FGF23), secreted by osteoblasts and osteocytes, can inhibit bone formation and mineralization. This research aims to investigate the relationship between CS and FGF23. METHODS We collected peripheral blood from two pairs of identical twins for methylation sequencing of the target region. FGF23 mRNA levels in the peripheral blood of CS patients and age-matched controls were measured. Receiver operator characteristic (ROC) curve analyses were conducted to evaluate the specificity and sensitivity of FGF23. The expression levels of FGF23 and its downstream factors fibroblast growth factor receptor 3 (FGFr3)/tissue non-specific alkaline phosphatase (TNAP)/osteopontin (OPN) in primary osteoblasts from CS patients (CS-Ob) and controls (CT-Ob) were detected. In addition, the osteogenic abilities of FGF23-knockdown or FGF23-overexpressing Ob were examined. RESULTS DNA methylation of the FGF23 gene in CS patients was decreased compared to that of their identical twins, accompanied by increased mRNA levels. CS patients had increased peripheral blood FGF23 mRNA levels and decreased computed tomography (CT) values compared with controls. The FGF23 mRNA levels were negatively correlated with the CT value of the spine, and ROCs of FGF23 mRNA levels showed high sensitivity and specificity for CS. Additionally, significantly increased levels of FGF23, FGFr3, OPN, impaired osteogenic mineralization and lower TNAP levels were observed in CS-Ob. Moreover, FGF23 overexpression in CT-Ob increased FGFr3 and OPN levels and decreased TNAP levels, while FGF23 knockdown induced downregulation of FGFr3 and OPN but upregulation of TNAP in CS-Ob. Mineralization of CS-Ob was rescued after FGF23 knockdown. CONCLUSIONS Our results suggested increased peripheral blood FGF23 levels, decreased bone mineral density in CS patients, and a good predictive ability of CS by peripheral blood FGF23 levels. FGF23 may contribute to osteopenia in CS patients through FGFr3/TNAP / OPN pathway.
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Affiliation(s)
- Hongqi Zhang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Gang Xiang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Jiong Li
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Sihan He
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Yunjia Wang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Ang Deng
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Yuxiang Wang
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
| | - Chaofeng Guo
- Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
- National Clinical Research Center for Geriatric Disorder, Xiangya Hospital, Central South University, Changsha, Hunan 410000, China
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Chirteș C, Bogliș A, Toth A, Rac C, Bănescu C. Compound heterozygous FAM20C gene variants in a patient with severe Raine syndrome: a case report. Front Genet 2023; 14:1179163. [PMID: 37180977 PMCID: PMC10171555 DOI: 10.3389/fgene.2023.1179163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/13/2023] [Indexed: 05/16/2023] Open
Abstract
Raine syndrome is a congenital disorder caused by biallelic mutations in the FAM20C gene. While most diagnosed cases of the syndrome are lethal in the first few months of life, there are also reports of non-lethal cases with Raine syndrome. The characteristic of this syndrome is typical facial dysmorphism and generalized osteosclerosis, as well as possible intracranial calcification, hearing loss, and seizures. We report a case of a 4-day-old patient at the time of examination, born with a distinct facial dysmorphism, short neck, narrow chest, and curved tibia. The parents, affirmative gypsy and non-consanguineous, had a previous male child born with the same phenotype who died at 4 months old. The computed tomography scan revealed choanal atresia, while transfontanelar ultrasound showed hypoplasia of the frontal and temporal lobes, corpus callosum dysgenesis, and multiple areas of intracranial hyperechogenicity. The chest X-Ray revealed generalized increased bone density. A skeletal disorders gene panel was performed which identified two variants in the FAM20C gene: a pathogenic variant c.1291C>T (p.Gln431*) and a likely pathogenic variant (c.1135G>A) (p.Gly379Arg), confirming the clinical diagnosis. The parents were also tested, and each was found to carry one of the variants. The particularity of this case is the severe phenotype in a compound heterozygous case that consists of FAM20C c.1291C>T (p.Gln431*) variant that has recently been reported in the literature. Also, our case is one of the few compound-heterozygous mutations in the FAM20C gene that has been described in a non-consanguineous marriage.
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Affiliation(s)
- Camelia Chirteș
- Laboratory of Genetics, Department of Genetics, Emergency County Hospital, Târgu Mureș, Romania
- *Correspondence: Camelia Chirteș,
| | - Alina Bogliș
- Laboratory of Genetics, Department of Genetics, Emergency County Hospital, Târgu Mureș, Romania
- Department of Genetics, George Emil Palade University of Medicine, Pharmacy, Science and Technology, Târgu Mureș, Romania
| | - Andrea Toth
- Department of Neonatology, Emergency County Hospital, Târgu Mureș, Romania
| | - Corina Rac
- Department of Neonatology, Emergency County Hospital, Târgu Mureș, Romania
| | - Claudia Bănescu
- Laboratory of Genetics, Department of Genetics, Emergency County Hospital, Târgu Mureș, Romania
- Department of Genetics, George Emil Palade University of Medicine, Pharmacy, Science and Technology, Târgu Mureș, Romania
- Center for Advanced Medical and Pharmaceutical Research, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Targu Mures, Târgu Mureș, Romania
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Michigami T. Paracrine and endocrine functions of osteocytes. Clin Pediatr Endocrinol 2023; 32:1-10. [PMID: 36761497 PMCID: PMC9887291 DOI: 10.1297/cpe.2022-0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/30/2022] [Indexed: 11/04/2022] Open
Abstract
Osteocytes are dendritic-shaped cells embedded in the bone matrix and are terminally differentiated from osteoblasts. Inaccessibility due to their location has hindered the understanding of the molecular functions of osteocytes. However, scientific advances in the past few decades have revealed that osteocytes play critical roles in bone and mineral metabolism through their paracrine and endocrine functions. Sclerostin produced by osteocytes regulates bone formation and resorption by inhibiting Wnt/β-catenin signaling in osteoblast-lineage cells. Receptor activator of nuclear factor κ B ligand (RANKL) derived from osteocytes is essential for osteoclastogenesis and osteoclast activation during postnatal life. Osteocytes also secrete fibroblast growth factor 23 (FGF23), an endocrine FGF that regulates phosphate metabolism mainly by increasing phosphate excretion and decreasing 1, 25-dihydroxyvitamin D production in the kidneys. The regulation of FGF23 production in osteocytes is complex and multifactorial, involving many local and systemic regulators. Antibodies against sclerostin, RANKL, and FGF23 have emerged as new strategies for the treatment of metabolic bone diseases. Improved undrstanding of the paracrine and endocrine functions of osteocytes will provide insight into future therapeutic options.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute,
Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Osaka,
Japan
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Koike T, Mikami T, Tamura JI, Kitagawa H. Altered sulfation status of FAM20C-dependent chondroitin sulfate is associated with osteosclerotic bone dysplasia. Nat Commun 2022; 13:7952. [PMID: 36572689 PMCID: PMC9792594 DOI: 10.1038/s41467-022-35687-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 12/19/2022] [Indexed: 12/27/2022] Open
Abstract
Raine syndrome, a lethal osteosclerotic bone dysplasia in humans, is caused by loss-of-function mutations in FAM20C; however, Fam20c deficiency in mice does not recapitulate the human disorder, so the underlying pathoetiological mechanisms remain poorly understood. Here we show that FAM20C, in addition to the reported casein kinase activity, also fine-tunes the biosynthesis of chondroitin sulfate (CS) chains to impact bone homeostasis. Specifically, FAM20C with Raine-originated mutations loses the ability to interact with chondroitin 4-O-sulfotransferase-1, and is associated with reduced 4-sulfation/6-sulfation (4S/6S) ratio of CS chains and upregulated biomineralization in human osteosarcoma cells. By contrast, overexpressing chondroitin 6-O-sulfotransferase-1 reduces CS 4S/6S ratio, and induces osteoblast differentiation in vitro and higher bone mineral density in transgenic mice. Meanwhile, a potential xylose kinase activity of FAM20C does not impact CS 4S/6S ratio, and is not associated with Raine syndrome mutations. Our results thus implicate CS 4S/6S ratio imbalances caused by FAM20C mutations as a contributor of Raine syndrome etiology.
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Affiliation(s)
- Toshiyasu Koike
- grid.411100.50000 0004 0371 6549Laboratory of Biochemistry, Kobe Pharmaceutical University, Higashinada-Ku, Kobe, 658-8558 Japan
| | - Tadahisa Mikami
- grid.411100.50000 0004 0371 6549Laboratory of Biochemistry, Kobe Pharmaceutical University, Higashinada-Ku, Kobe, 658-8558 Japan
| | - Jun-Ichi Tamura
- grid.265107.70000 0001 0663 5064Department of Agricultural, Life and Environmental Sciences, Faculty of Agriculture, Tottori University, Tottori, 680-8551 Japan
| | - Hiroshi Kitagawa
- grid.411100.50000 0004 0371 6549Laboratory of Biochemistry, Kobe Pharmaceutical University, Higashinada-Ku, Kobe, 658-8558 Japan
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Abstract
Inorganic phosphate (Pi) in the mammalian body is balanced by its influx and efflux through the intestines, kidneys, bones, and soft tissues, at which several sodium/Pi co-transporters mediate its active transport. Pi homeostasis is achieved through the complex counter-regulatory feedback balance between fibroblast growth factor 23 (FGF23), 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone. FGF23, which is mainly produced by osteocytes in bone, plays a central role in Pi homeostasis and exerts its effects by binding to the FGF receptor (FGFR) and αKlotho in distant target organs. In the kidneys, the main target, FGF23 promotes the excretion of Pi and suppresses the production of 1,25(OH)2D. Deficient and excess FGF23 result in hyperphosphatemia and hypophosphatemia, respectively. FGF23-related hypophosphatemic rickets/osteomalacia include tumor-induced osteomalacia and various genetic diseases, such as X-linked hypophosphatemic rickets. Coverage by the national health insurance system in Japan for the measurement of FGF23 and the approval of burosumab, an FGF23-neutralizing antibody, have had a significant impact on the diagnosis and treatment of FGF23-related hypophosphatemic rickets/osteomalacia. Some of the molecules responsible for genetic hypophosphatemic rickets/osteomalacia are highly expressed in osteocytes and function as local regulators of FGF23 production. A number of systemic factors also regulate FGF23 levels. Although the mechanisms responsible for Pi sensing in mammals have not yet been elucidated in detail, recent studies have suggested the involvement of FGFR1. The further clarification of the mechanisms by which osteocytes detect Pi levels and regulate FGF23 production will lead to the development of better strategies to treat hyperphosphatemic and hypophosphatemic conditions.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka 594-1101, Japan
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Pathogenesis of FGF23-Related Hypophosphatemic Diseases Including X-linked Hypophosphatemia. ENDOCRINES 2022. [DOI: 10.3390/endocrines3020025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Since phosphate is indispensable for skeletal mineralization, chronic hypophosphatemia causes rickets and osteomalacia. Fibroblast growth factor 23 (FGF23), which is mainly produced by osteocytes in bone, functions as the central regulator of phosphate metabolism by increasing the renal excretion of phosphate and suppressing the production of 1,25-dihydroxyvitamin D. The excessive action of FGF23 results in hypophosphatemic diseases, which include a number of genetic disorders such as X-linked hypophosphatemic rickets (XLH) and tumor-induced osteomalacia (TIO). Phosphate-regulating gene homologous to endopeptidase on the X chromosome (PHEX), dentin matrix protein 1 (DMP1), ectonucleotide pyrophosphatase phosphodiesterase-1, and family with sequence similarity 20c, the inactivating variants of which are responsible for FGF23-related hereditary rickets/osteomalacia, are highly expressed in osteocytes, similar to FGF23, suggesting that they are local negative regulators of FGF23. Autosomal dominant hypophosphatemic rickets (ADHR) is caused by cleavage-resistant variants of FGF23, and iron deficiency increases serum levels of FGF23 and the manifestation of symptoms in ADHR. Enhanced FGF receptor (FGFR) signaling in osteocytes is suggested to be involved in the overproduction of FGF23 in XLH and autosomal recessive hypophosphatemic rickets type 1, which are caused by the inactivation of PHEX and DMP1, respectively. TIO is caused by the overproduction of FGF23 by phosphaturic tumors, which are often positive for FGFR. FGF23-related hypophosphatemia may also be associated with McCune-Albright syndrome, linear sebaceous nevus syndrome, and the intravenous administration of iron. This review summarizes current knowledge on the pathogenesis of FGF23-related hypophosphatemic diseases.
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FAM20C plays a critical role in the development of mouse vertebra. Spine J 2022; 22:337-348. [PMID: 34343663 DOI: 10.1016/j.spinee.2021.07.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Family with sequence similarity 20-member C (FAM20C) is a protein kinase that is responsible for the phosphorylation of many secretory proteins; however, its roles in spine or vertebra development have not be studied. PURPOSE The aim of this investigation is to analyze the roles of FAM20C in vertebra development. STUDY DESIGN/SETTING A mouse study of the Fam20c gene using conditional knockout to assess the effects of its inactivation on vertebra development. METHODS By breeding Sox2-Cre mice with Fam20cflox/flox mice, Sox2-Cre;Fam20cflox/flox mice (abbreviated as cKO mice) are created. X-ray radiography, resin-casted scanning electron microscopy, Hematoxylin and Eosin staining, safranin O staining, Goldner's Masson trichrome staining, Von Kossa staining, tartrate-resistant alkaline phosphatase staining, immunohistochemistry staining, Western Immunoblotting and real-time PCR were employed to characterize the vertebrae of cKO mice compared to the normal control mice. RESULTS Inactivation of Fam20c in mice results in remarkable spine deformity, severe morphology and mineralization defects, altered levels of osteoblast differentiation markers, reduction of activity of the Wnt/β-catenin signaling pathway and reduced level of osteoclastogenesis in the vertebrae. CONCLUSIONS FAM20C plays an essential role in vertebral development; it may regulate vertebral formation through the Wnt/β-catenin signaling pathway. CLINICAL SIGNIFICANCE Mutations in the human FAM20C gene are associated with Raine syndrome. The findings of this study provide valuable clues for the clinical management of Raine syndrome regarding spine manifestations in patients.
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Geng YW, Zhang Z, Jin H, Da JL, Zhang K, Wang JQ, Guo YY, Zhang B, Li Y. Mesenchymal-to-epithelial transition of osteoblasts induced by Fam20c knockout. Genes Genomics 2022; 44:155-164. [PMID: 35025083 DOI: 10.1007/s13258-021-01170-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 09/20/2021] [Indexed: 11/04/2022]
Abstract
BACKGROUND Fam20c is intimately related to tissue development and diseases. At present, it has been reported that Fam20c regulates the mineralization of osteoblasts, but there are few reports on other effects. OBJECTIVE To study the effect of Fam20c on osteoblasts by knocking out the Fam20c gene. METHODS Fam20c knockout osteoblasts were constructed by transfecting mouse osteoblasts with lentivirus. The proliferation, migration and mineralization of Fam20c knockout cells were detected by CCK-8, scratch test and alizarin red staining assays. The subcellular structure was observed by transmission electron microscopy. RT-PCR was used to detect the differential expression of mesenchymal-to-epithelial transition (MET)-related marker genes and core transcription factors. The differential expression of MET-related proteins was detected by immunofluorescence or Western blot. Transcriptome analysis of Fam20c knockout osteoblasts was performed, and real-time PCR was used to verify transcriptome analysis related to MET. RESULTS The proliferation ability of osteoblasts was not significantly changed after Fam20c deletion, but the migration ability and mineralization ability were significantly weakened. There were tight junctions between Fam20c knockout cells. The expression of mesenchymal cell marker genes and core transcription factors was significantly decreased, and the expression of epithelial cell marker genes was significantly increased. The expression of mesenchymal cell marker proteins was significantly decreased, and the expression of epithelial cell marker proteins was significantly increased. Multiple signalling molecules and pathways involved in MET have changed. CONCLUSIONS Knockdown of Fam20c resulted in MET. Fam20c affects the transcription of key factors in osteoblast MET.
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Affiliation(s)
- Ya-Wei Geng
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Zhen Zhang
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Han Jin
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Jun-Long Da
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Kai Zhang
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Jian-Qun Wang
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Yu-Yao Guo
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China.,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China
| | - Bin Zhang
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China. .,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China. .,Heilongjiang Academy of Medical Sciences, Harbin, 150001, Heilongjiang, People's Republic of China.
| | - Ying Li
- Institute of Hard Tissue Development and Regeneration, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150001, Heilongjiang, People's Republic of China. .,Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin, 150001, Heilongjiang, People's Republic of China.
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Abstract
Osteocytes are dendritic cells in the mineralized bone matrix that descend from osteoblasts. They play critical roles in controlling bone mass through the production of sclerostin, an inhibitor of bone formation, and receptor activator of nuclear factor κ B ligand, an inducer of osteoblastic bone resorption. Osteocytes also govern phosphate homeostasis through the production of fibroblast growth factor 23 (FGF23), which lowers serum phosphate levels by increasing renal phosphate excretion and reducing the synthesis of 1,25-dihydroxyvitamin D (1,25(OH)2D), an active metabolite of vitamin D. The production of FGF23 in osteocytes is regulated by various local and systemic factors. Phosphate-regulating gene homologous to endopeptidase on X chromosome (PHEX), dentin matrix protein 1 (DMP1), and family with sequence similarity 20, member C function as local negative regulators of FGF23 production in osteocytes, and their inactivation causes the overproduction of FGF23 and hypophosphatemia. Sclerostin has been suggested to regulate the production of FGF23, which may link the two functions of osteocytes, namely, the control of bone mass and regulation of phosphate homeostasis. Systemic regulators of FGF23 production include 1,25(OH)2D, phosphate, parathyroid hormone, insulin, iron, and inflammation. Therefore, the regulation of FGF23 in osteocytes is complex and multifactorial. Recent mouse studies have suggested that decreases in serum phosphate levels from youth to adulthood are caused by growth-related increases in FGF23 production by osteocytes, which are associated with the down-regulation of Phex and Dmp1.
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Michigami T, Yamazaki M, Razzaque MS. Extracellular Phosphate, Inflammation and Cytotoxicity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1362:15-25. [DOI: 10.1007/978-3-030-91623-7_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Yamazaki M, Michigami T. Osteocytes and the pathogenesis of hypophosphatemic rickets. Front Endocrinol (Lausanne) 2022; 13:1005189. [PMID: 36246908 PMCID: PMC9556901 DOI: 10.3389/fendo.2022.1005189] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 09/15/2022] [Indexed: 11/13/2022] Open
Abstract
Since phosphorus is a component of hydroxyapatite, its prolonged deprivation affects bone mineralization. Fibroblast growth factor 23 (FGF23) is essential for maintaining phosphate homeostasis and is mainly produced by osteocytes. FGF23 increases the excretion of inorganic phosphate (Pi) and decreases the production of 1,25-dihydroxyvitamin D in the kidneys. Osteocytes are cells of osteoblastic lineage that have undergone terminal differentiation and become embedded in mineralized bone matrix. Osteocytes express FGF23 and other multiple genes responsible for hereditary hypophosphatemic rickets, which include phosphate-regulating gene homologous to endopeptidase on X chromosome (PHEX), dentin matrix protein 1 (DMP1), and family with sequence similarity 20, member C (FAM20C). Since inactivating mutations in PHEX, DMP1, and FAM20C boost the production of FGF23, these molecules might be considered as local negative regulators of FGF23. Mouse studies have suggested that enhanced FGF receptor (FGFR) signaling is involved in the overproduction of FGF23 in PHEX-deficient X-linked hypophosphatemic rickets (XLH) and DMP1-deficient autosomal recessive hypophosphatemic rickets type 1. Since FGFR is involved in the transduction of signals evoked by extracellular Pi, Pi sensing in osteocytes may be abnormal in these diseases. Serum levels of sclerostin, an inhibitor Wnt/β-catenin signaling secreted by osteocytes, are increased in XLH patients, and mouse studies have suggested the potential of inhibiting sclerostin as a new therapeutic option for the disease. The elucidation of complex abnormalities in the osteocytes of FGF23-related hypophosphatemic diseases will provide a more detailed understanding of their pathogenesis and more effective treatments.
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Zuo H, Yang D, Wan Y. Fam20C Regulates Bone Resorption and Breast Cancer Bone Metastasis through Osteopontin and BMP4. Cancer Res 2021; 81:5242-5254. [PMID: 34433585 DOI: 10.1158/0008-5472.can-20-3328] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/14/2020] [Accepted: 08/23/2021] [Indexed: 11/16/2022]
Abstract
Fam20C is a kinase that generates the majority of secreted phosphoproteins and regulates biomineralization. However, its potential roles in bone resorption and breast cancer bone metastasis are unknown. Here we show that Fam20C in the myeloid lineage suppresses osteoclastogenesis and bone resorption, during which, osteopontin (OPN) is the most abundant phosphoprotein secreted in a Fam20C-dependent manner. OPN phosphorylation by Fam20C decreased OPN secretion, and OPN neutralization reduced Fam20C deficiency-induced osteoclast differentiation and bone metastasis. In contrast, Fam20C in breast cancer cells promoted bone metastasis by facilitating the phosphorylation and secretion of BMP4, which in turn enhanced osteoclastogenesis. Mutation of the BMP4 phosphorylation site elevated BMP4 lysosomal degradation and reduced BMP4 secretion. In breast cancer cells, BMP4 depletion or treatment with a BMP4 signaling inhibitor diminished osteoclast differentiation and bone metastasis and abolished Fam20C-mediated regulation of these processes. Collectively, this study discovers distinct roles for Fam20C in myeloid cells and breast cancer cells and highlights OPN and BMP4 as potential therapeutic targets for breast cancer bone metastasis. SIGNIFICANCE: Osteoclastogenesis and bone metastasis are suppressed by myeloid-derived Fam20C, but enhanced by breast cancer-associated Fam20C, uncovering novel Fam20C functions and new therapeutic strategies via targeting Fam20C substrates OPN and BMP4.
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Affiliation(s)
- Hao Zuo
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Dengbao Yang
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Yihong Wan
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas.
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14
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FAM20C Overview: Classic and Novel Targets, Pathogenic Variants and Raine Syndrome Phenotypes. Int J Mol Sci 2021; 22:ijms22158039. [PMID: 34360805 PMCID: PMC8348777 DOI: 10.3390/ijms22158039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/16/2021] [Accepted: 07/18/2021] [Indexed: 12/24/2022] Open
Abstract
FAM20C is a gene coding for a protein kinase that targets S-X-E/pS motifs on different phosphoproteins belonging to diverse tissues. Pathogenic variants of FAM20C are responsible for Raine syndrome (RS), initially described as a lethal and congenital osteosclerotic dysplasia characterized by generalized atherosclerosis with periosteal bone formation, characteristic facial dysmorphisms and intracerebral calcifications. The aim of this review is to give an overview of targets and variants of FAM20C as well as RS aspects. We performed a wide phenotypic review focusing on clinical aspects and differences between all lethal (LRS) and non-lethal (NLRS) reported cases, besides the FAM20C pathogenic variant description for each. As new targets of FAM20C kinase have been identified, we reviewed FAM20C targets and their functions in bone and other tissues, with emphasis on novel targets not previously considered. We found the classic lethal and milder non-lethal phenotypes. The milder phenotype is defined by a large spectrum ranging from osteonecrosis to osteosclerosis with additional congenital defects or intellectual disability in some cases. We discuss our current understanding of FAM20C deficiency, its mechanism in RS through classic FAM20C targets in bone tissue and its potential biological relevance through novel targets in non-bone tissues.
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15
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The ABCs of the atypical Fam20 secretory pathway kinases. J Biol Chem 2021; 296:100267. [PMID: 33759783 PMCID: PMC7948968 DOI: 10.1016/j.jbc.2021.100267] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 12/12/2022] Open
Abstract
The study of extracellular phosphorylation was initiated in late 19th century when the secreted milk protein, casein, and egg-yolk protein, phosvitin, were shown to be phosphorylated. However, it took more than a century to identify Fam20C, which phosphorylates both casein and phosvitin under physiological conditions. This kinase, along with its family members Fam20A and Fam20B, defined a new family with altered amino acid sequences highly atypical from the canonical 540 kinases comprising the kinome. Fam20B is a glycan kinase that phosphorylates xylose residues and triggers peptidoglycan biosynthesis, a role conserved from sponges to human. The protein kinase, Fam20C, conserved from nematodes to humans, phosphorylates well over 100 substrates in the secretory pathway with overall functions postulated to encompass endoplasmic reticulum homeostasis, nutrition, cardiac function, coagulation, and biomineralization. The preferred phosphorylation motif of Fam20C is SxE/pS, and structural studies revealed that related member Fam20A allosterically activates Fam20C by forming a heterodimeric/tetrameric complex. Fam20A, a pseudokinase, is observed only in vertebrates. Loss-of-function genetic alterations in the Fam20 family lead to human diseases such as amelogenesis imperfecta, nephrocalcinosis, lethal and nonlethal forms of Raine syndrome with major skeletal defects, and altered phosphate homeostasis. Together, these three members of the Fam20 family modulate a diverse network of secretory pathway components playing crucial roles in health and disease. The overarching theme of this review is to highlight the progress that has been made in the emerging field of extracellular phosphorylation and the key roles secretory pathway kinases play in an ever-expanding number of cellular processes.
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16
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Eras N, Celik Y. Nonlethal Raine Syndrome in a Newborn Boy Caused by a Novel FAM20C Variant. Mol Syndromol 2021; 12:169-173. [PMID: 34177433 DOI: 10.1159/000513384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 11/25/2020] [Indexed: 11/19/2022] Open
Abstract
Raine syndrome (RS) is a rare genetic disorder characterized by osteosclerotic bone dysplasia caused by a homozygous mutation, compound heterozygous mutation, or microdeletion in the FAM20C gene. In the present study, the MiSeq next-generation sequencing platform was used to perform the FAM20C gene sequence analysis. A novel homozygous variant c.1255T>C (p.W419R) in the FAM20C gene was diagnosed, and a nonlethal RS phenotype was confirmed, thus contributing to the expansion of the nonlethal RS phenotype. Since there is limited information about rare diseases, we believe that these studies will contribute to the literature and to the understanding of how these disorders develop and progress.
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Affiliation(s)
- Nazan Eras
- Department of Medical Genetics, Faculty of Medicine, Mersin University, Mersin, Turkey
| | - Yalcin Celik
- Department of Pediatrics, Division of Neonatology, Faculty of Medicine, Mersin University, Mersin, Turkey
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17
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Koumakis E, Cormier C, Roux C, Briot K. The Causes of Hypo- and Hyperphosphatemia in Humans. Calcif Tissue Int 2021; 108:41-73. [PMID: 32285168 DOI: 10.1007/s00223-020-00664-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 01/20/2020] [Indexed: 12/11/2022]
Abstract
Phosphate homeostasis involves several major organs that are the skeleton, the intestine, the kidney, and parathyroid glands. Major regulators of phosphate homeostasis are parathormone, fibroblast growth factor 23, 1,25-dihydroxyvitamin D, which respond to variations of serum phosphate levels and act to increase or decrease intestinal absorption and renal tubular reabsorption, through the modulation of expression of transcellular transporters at the intestinal and/or renal tubular level. Any acquired or genetic dysfunction in these major organs or regulators may induce hypo- or hyperphosphatemia. The causes of hypo- and hyperphosphatemia are numerous. This review develops the main causes of acquired and genetic hypo- and hyperphosphatemia.
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Affiliation(s)
- Eugénie Koumakis
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France.
| | - Catherine Cormier
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
| | - Christian Roux
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
| | - Karine Briot
- Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Reference Center for Rare Genetic Bone Disorders, OSCAR Filière, Rheumatology Department, Cochin Hospital, AP-HP Centre-Paris University, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
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18
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Laurent MR, De Schepper J, Trouet D, Godefroid N, Boros E, Heinrichs C, Bravenboer B, Velkeniers B, Lammens J, Harvengt P, Cavalier E, Kaux JF, Lombet J, De Waele K, Verroken C, van Hoeck K, Mortier GR, Levtchenko E, Vande Walle J. Consensus Recommendations for the Diagnosis and Management of X-Linked Hypophosphatemia in Belgium. Front Endocrinol (Lausanne) 2021; 12:641543. [PMID: 33815294 PMCID: PMC8018577 DOI: 10.3389/fendo.2021.641543] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/19/2021] [Indexed: 12/11/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is the most common genetic form of hypophosphatemic rickets and osteomalacia. In this disease, mutations in the PHEX gene lead to elevated levels of the hormone fibroblast growth factor 23 (FGF23), resulting in renal phosphate wasting and impaired skeletal and dental mineralization. Recently, international guidelines for the diagnosis and treatment of this condition have been published. However, more specific recommendations are needed to provide guidance at the national level, considering resource availability and health economic aspects. A national multidisciplinary group of Belgian experts convened to discuss translation of international best available evidence into locally feasible consensus recommendations. Patients with XLH may present to a wide array of primary, secondary and tertiary care physicians, among whom awareness of the disease should be raised. XLH has a very broad differential-diagnosis for which clinical features, biochemical and genetic testing in centers of expertise are recommended. Optimal care requires a multidisciplinary approach, guided by an expert in metabolic bone diseases and involving (according to the individual patient's needs) pediatric and adult medical specialties and paramedical caregivers, including but not limited to general practitioners, dentists, radiologists and orthopedic surgeons. In children with severe or refractory symptoms, FGF23 inhibition using burosumab may provide superior outcomes compared to conventional medical therapy with phosphate supplements and active vitamin D analogues. Burosumab has also demonstrated promising results in adults on certain clinical outcomes such as pseudofractures. In summary, this work outlines recommendations for clinicians and policymakers, with a vision for improving the diagnostic and therapeutic landscape for XLH patients in Belgium.
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Affiliation(s)
- Michaël R. Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
- *Correspondence: Michaël R. Laurent,
| | - Jean De Schepper
- Division of Pediatric Endocrinology, KidZ Health Castle, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Department of Pediatric Endocrinology, University Hospital Ghent, Ghent, Belgium
| | - Dominique Trouet
- Department of Pediatric Nephrology, Antwerp University Hospital, Antwerp, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
| | - Nathalie Godefroid
- Pediatric Nephrology, Cliniques Universitaires St. Luc (UCL), Brussels, Belgium
| | - Emese Boros
- Paediatric Endocrinology Unit, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Claudine Heinrichs
- Paediatric Endocrinology Unit, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Bert Bravenboer
- Department of Endocrinology, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Brigitte Velkeniers
- Department of Endocrinology, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Johan Lammens
- Department of Orthopaedic Surgery and Department of Development and Regeneration, Prometheus LRD Division of Skeletal Tissue Engineering, KU Leuven - University Hospitals Leuven, Leuven, Belgium
| | - Pol Harvengt
- XLH Belgium, Belgian X-Linked Hypophosphatemic Rickets (XLH) Patient Association, Waterloo, Belgium
| | - Etienne Cavalier
- Department of Clinical Chemistry, University Hospital Center of Liège, University of Liège, Liège, Belgium
| | - Jean-François Kaux
- Physical Medicine, Rehabilitation and Sports Traumatology, University and University Hospital of Liège, Liège, Belgium
| | - Jacques Lombet
- Division of Nephrology, Department of Pediatrics, University Hospital Center of Liège, Liège, Belgium
| | - Kathleen De Waele
- Department of Pediatric Endocrinology, University Hospital Ghent, Ghent, Belgium
| | - Charlotte Verroken
- Unit for Osteoporosis and Metabolic Bone Diseases, Department of Endocrinology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Koenraad van Hoeck
- Department of Pediatric Nephrology, Antwerp University Hospital, Antwerp, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
| | - Geert R. Mortier
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, Antwerp, Belgium
| | - Elena Levtchenko
- Department of Pediatrics/Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Johan Vande Walle
- Department of Pediatric Nephrology, University Hospital Ghent, Ghent, Belgium
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19
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Abstract
FGF23 is a phosphotropic hormone produced by the bone. FGF23 works by binding to the FGF receptor-Klotho complex. Klotho is expressed in several limited tissues including the kidney and parathyroid glands. This tissue-restricted expression of Klotho is believed to determine the target organs of FGF23. FGF23 reduces serum phosphate by suppressing the expression of type 2a and 2c sodium-phosphate cotransporters in renal proximal tubules. FGF23 also decreases 1,25-dihydroxyvitamin D levels by regulating the expression of vitamin D-metabolizing enzymes, which results in reduced intestinal phosphate absorption. Excessive actions of FGF23 cause several types of hypophosphatemic rickets/osteomalacia characterized by impaired mineralization of bone matrix. In contrast, deficient actions of FGF23 result in hyperphosphatemic tumoral calcinosis with high 1,25-dihydroxyvitamin D levels. These results indicate that FGF23 is a physiological regulator of phosphate and vitamin D metabolism and indispensable for the maintenance of serum phosphate levels.
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20
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Abstract
Osteocytes are an ancient cell, appearing in fossilized skeletal remains of early fish and dinosaurs. Despite its relative high abundance, even in the context of nonskeletal cells, the osteocyte is perhaps among the least studied cells in all of vertebrate biology. Osteocytes are cells embedded in bone, able to modify their surrounding extracellular matrix via specialized molecular remodeling mechanisms that are independent of the bone forming osteoblasts and bone-resorbing osteoclasts. Osteocytes communicate with osteoclasts and osteoblasts via distinct signaling molecules that include the RankL/OPG axis and the Sost/Dkk1/Wnt axis, among others. Osteocytes also extend their influence beyond the local bone environment by functioning as an endocrine cell that controls phosphate reabsorption in the kidney, insulin secretion in the pancreas, and skeletal muscle function. These cells are also finely tuned sensors of mechanical stimulation to coordinate with effector cells to adjust bone mass, size, and shape to conform to mechanical demands.
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Affiliation(s)
- Alexander G Robling
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA;
| | - Lynda F Bonewald
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA;
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21
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Khor JM, Ettensohn CA. Transcription Factors of the Alx Family: Evolutionarily Conserved Regulators of Deuterostome Skeletogenesis. Front Genet 2020; 11:569314. [PMID: 33329706 PMCID: PMC7719703 DOI: 10.3389/fgene.2020.569314] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 10/19/2020] [Indexed: 12/13/2022] Open
Abstract
Members of the alx gene family encode transcription factors that contain a highly conserved Paired-class, DNA-binding homeodomain, and a C-terminal OAR/Aristaless domain. Phylogenetic and comparative genomic studies have revealed complex patterns of alx gene duplications during deuterostome evolution. Remarkably, alx genes have been implicated in skeletogenesis in both echinoderms and vertebrates. In this review, we provide an overview of current knowledge concerning alx genes in deuterostomes. We highlight their evolutionarily conserved role in skeletogenesis and draw parallels and distinctions between the skeletogenic gene regulatory circuitries of diverse groups within the superphylum.
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Affiliation(s)
- Jian Ming Khor
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Charles A Ettensohn
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, United States
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22
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El-Dessouky SH, Abdel-Hamid MS, Abdel-Ghafar SF, Aboulghar MM, Gaafar HM, Fouad M, Ahmed AH, Abdel-Salam GMH. Raine syndrome: Prenatal diagnosis based on recognizable fetal facial features and characteristic intracranial calcification. Prenat Diagn 2020; 40:1578-1597. [PMID: 32833257 DOI: 10.1002/pd.5818] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 08/20/2020] [Accepted: 08/20/2020] [Indexed: 01/21/2023]
Abstract
OBJECTIVE The purpose of this study was to elucidate the facial morphology and the pattern of internal malformations in three fetuses with RS born to first cousins of Egyptian decent. METHODS The fetal ultrasonography findings were highly suggestive of RS leading to targeted Sanger sequencing of FAM20C and postnatal assessment. RESULTS The prenatal ultrasound findings of osteosclerotic skull, exorbitism, hypoplastic nose, midface hypoplasia, small mouth with down-curved corners, and a distinct and recognizable pattern of intracranial calcification were identified in three fetuses with RS. The calcifications were evident specifically around the corpus callosum and/or ventricular walls. Ectopic renal and hepatic calcifications, pulmonary hypoplasia, mild rhizomelic shortening of the upper limbs, intrauterine fractures, and cerebellar hypoplasia were also noted. Molecular analysis identified three novel homozygous variants, two frameshift: [c.456delC (p.Gly153Alafs*34)] in exon 1 and [c.905delT (Phe302Serfs*35)] in exon 4 and one nonsense mutation in exon 10, [c.1557C>G(p.Tyrs519*)]. The three variants were segregated with the phenotype. This is the first description of a phenotype associated with homozygous truncating variants of FAM20C. CONCLUSION RS has characteristic prenatal ultrasound findings which can improve the prenatal identification of this condition and help in guiding the molecular diagnosis and counseling.
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Affiliation(s)
- Sara H El-Dessouky
- Department of Prenatal Diagnosis & Fetal Medicine, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
| | - Mohamed S Abdel-Hamid
- Department of Medical & Molecular Genetics, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
| | - Sherif F Abdel-Ghafar
- Department of Medical & Molecular Genetics, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
| | | | | | - Mona Fouad
- Fetal Medicine Unit, Cairo University, Cairo, Egypt
| | - Adel H Ahmed
- Fetal Medicine Unit, Cairo University, Cairo, Egypt
| | - Ghada M H Abdel-Salam
- Department of Clinical Genetics, Division of Human Genetics and Genome Research, National Research Centre, Cairo, Egypt
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23
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Hirose K, Ishimoto T, Usami Y, Sato S, Oya K, Nakano T, Komori T, Toyosawa S. Overexpression of Fam20C in osteoblast in vivo leads to increased cortical bone formation and osteoclastic bone resorption. Bone 2020; 138:115414. [PMID: 32416287 DOI: 10.1016/j.bone.2020.115414] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/10/2020] [Accepted: 05/11/2020] [Indexed: 01/03/2023]
Abstract
Fam20C, which phosphorylates many secretory proteins with S-x-E/pS motifs, is highly expressed in bone and tooth tissues, implying that Fam20C-mediated phosphorylation is critical for regulation of these mineralized tissues. Previous studies of Fam20C-deficient mice revealed that Fam20C plays important roles in bone formation and mineralization. However, Fam20C-deficient mice develop hypophosphatemia, a systemic factor that masks the local effect of Fam20C in the bone tissue; consequently, the local role of Fam20C remains unknown. To elucidate the local function of Fam20C in bone tissue, we studied osteoblast-specific Fam20C transgenic (Fam20C-Tg) mice, which have no alteration in serum calcium and phosphate levels. Fam20C-Tg mice had more highly phosphorylated proteins in bone tissue than wild-type mice. In cortical bone of Fam20C-Tg mice, bone volume, mineralization surface (MS/BS), and mineral apposition rate (MAR) were elevated; in addition, the transgenic mice had an elevated number of vascular canals, resulting in an increased cortical porosity. Osteocyte number was elevated in the transgenics, but osteoblast number was unchanged. The microstructure of bone matrix characterized by the preferential orientation of collagen and apatite, was degraded and thus the mechanical function of bone material was deteriorated. In trabecular bone of Fam20C-Tg mice, bone volume was reduced, whereas MS/BS and MAR were unchanged. Osteoclast number was elevated and eroded surface area was non-significantly elevated with an increased serum CTX-I level, whereas osteoblast number was unchanged. These findings indicated that Fam20C overexpression in osteoblasts promotes cortical bone formation by increasing MS/BS and MAR and promoting osteocyte differentiation, but does not affect trabecular bone formation. Furthermore, Fam20C overexpression indirectly promotes osteoclastic bone resorption in cortical and trabecular bones. Our findings show that osteoblastic Fam20C-mediated phosphorylation in bone tissue regulates bone formation and resorption, and bone material quality.
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Affiliation(s)
- Katsutoshi Hirose
- Department of Oral Pathology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Takuya Ishimoto
- Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Yu Usami
- Department of Oral Pathology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Sunao Sato
- Department of Oral Pathology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Kaori Oya
- Clinical Laboratory, Osaka University Dental Hospital, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Takayoshi Nakano
- Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Toshihisa Komori
- Basic and Translational Research Center for Hard Tissue Disease, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan.
| | - Satoru Toyosawa
- Department of Oral Pathology, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
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24
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Eltan M, Alavanda C, Yavas Abali Z, Ergenekon P, Yalındag Ozturk N, Sakar M, Dagcinar A, Kirkgoz T, Kaygusuz SB, Gokdemir Y, Elcioglu HN, Guran T, Bereket A, Ata P, Turan S. A Rare Cause of Hypophosphatemia: Raine Syndrome Changing Clinical Features with Age. Calcif Tissue Int 2020; 107:96-103. [PMID: 32337609 PMCID: PMC7222149 DOI: 10.1007/s00223-020-00694-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/11/2020] [Indexed: 11/29/2022]
Abstract
Raine Syndrome (RS) is caused by biallelic loss-of-function mutations in FAM20C gene and characterized by hypophosphatemia, typical facial and skeletal features. Subperiosteal bone formation and generalized osteosclerosis are the most common radiological findings. Here we present a new case with RS. A 9-month-old male patient on a home-type ventilator was referred for hypophosphatemia. He was born with a weight of 3800 g to non-consanguineous parents. Prenatal ultrasound had demonstrated nasal bone agenesis. A large anterior fontanel, frontal bossing, exophthalmos, hypoplastic nose, high arched palate, low set ears, triangular mouth, and corneal opacification were detected on physical examination. Serial skeletal X-rays revealed diffuse osteosclerosis at birth which was gradually decreased by the age of 5 months with subperiosteal undermineralized bone formation and medullary space of long bone could be distinguishable with bone-within-a-bone appearance. At 9 months of age, hand X-ray revealed cupping of the ulna with loose radial bone margin with minimal fraying and osteopenia. Cranial computed tomography scan showed bilateral periventricular calcification and hydrocephalus in progress. The clinical, laboratory, and radiological examinations were consistent with RS. Molecular analyses revealed a compound heterozygous mutation in FAM20C gene (a known pathogenic mutation, c.1645C > T, p.Arg549Trp; and a novel c.863 + 5 G > C variant). The patient died due to respiratory failure at 17 months of age. This case allowed us to demonstrate natural progression of skeletal features in RS. Furthermore, we have described a novel FAM20C variant causing RS. Previous literature on RS is also reviewed.
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Affiliation(s)
- Mehmet Eltan
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Ceren Alavanda
- Department of Medical Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Zehra Yavas Abali
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Pinar Ergenekon
- Department of Pediatric Chest Disease, Marmara University School of Medicine, Istanbul, Turkey
| | - Nilufer Yalındag Ozturk
- Department of Pediatric Intensive Care Unit, Marmara University School of Medicine, Istanbul, Turkey
| | - Mustafa Sakar
- Department of Pediatric Neurosurgery, Marmara University School of Medicine, Istanbul, Turkey
| | - Adnan Dagcinar
- Department of Pediatric Neurosurgery, Marmara University School of Medicine, Istanbul, Turkey
| | - Tarik Kirkgoz
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Sare Betul Kaygusuz
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Yasemin Gokdemir
- Department of Pediatric Chest Disease, Marmara University School of Medicine, Istanbul, Turkey
| | - Huriye Nursel Elcioglu
- Department of Pediatric Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Tulay Guran
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Abdullah Bereket
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Pinar Ata
- Department of Medical Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Serap Turan
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey.
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25
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Mameli C, Zichichi G, Mahmood N, Elalaoui SC, Mirza A, Dharmaraj P, Burrone M, Cattaneo E, Sheth J, Gandhi A, Kochar GS, Alkuraya FS, Kabra M, Mercurio G, Zuccotti G. Natural history of non-lethal Raine syndrome during childhood. Orphanet J Rare Dis 2020; 15:93. [PMID: 32299476 PMCID: PMC7164176 DOI: 10.1186/s13023-020-01373-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Raine syndrome (RS) is a rare autosomal recessive disorder caused by biallelic loss-of-function mutations of FAM20C. The most common clinical features are microcephaly, exophthalmos, hypoplastic nose and severe midface hypoplasia, leading to choanal atresia. The radiological findings include generalized osteosclerosis and brain calcifications. RS is usually lethal during the neonatal period due to severe respiratory distress. However, there exists a non-lethal RS form, the phenotype of which is extremely heterogeneous. There is paucity of data about clinical course and life expectancy of these patients. RESULTS This is the first description of follow-up features of non-lethal RS patients. Moreover, we present three unpublished cases. There are five Asian and two Arab patients. All were born to consanguineous parents. The most common neonatal comorbidity was respiratory distress secondary to choanal atresia. A variable degree of neurodevelopmental delay was seen in the majority of our cases and seizures and hearing or vision involvement were also frequent. Neurological and orthopedic issues were the most frequent complications seen at follow-up in our group. Persistent hypophosphatemic rickets was the most striking endocrinological manifestation, which was scarcely responsive to therapy with phosphate salts and alfacalcidol. Life expectancy of our patients goes beyond childhood, with the oldest of those described being 18 years old at present. CONCLUSIONS Manifestations of RS in those surviving the neonatal period are being increasingly recognized. Our study supports previous findings and provides clinical and biochemical observations and data from longer follow up. Finally, we propose multidisciplinary follow up for patients with non-lethal RS.
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Affiliation(s)
- Chiara Mameli
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Department of Biomedical and Clinical Science L. Sacco, Università degli Studi di Milano, Milan, Italy.
| | - Giulia Zichichi
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Nasim Mahmood
- Department of General Paediatrics, Alder Hey Children's Hospital, Liverpool, UK
| | - Siham Chafai Elalaoui
- Centre de Recherche en Génomique des Pathologies Humaines (GENOPATH), Faculté de Médecine et de Pharmacie, Mohammed V University of Rabat, 10100, Rabat, Morocco
| | - Adnan Mirza
- Faculty of Paediatrics, Aga Khan University Hospital, Karachi, Pakistan
| | - Poonam Dharmaraj
- Department of Paediatric Endocrinology, Alder Hey Children's Hospital, Liverpool, UK
| | - Marco Burrone
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Elisa Cattaneo
- Clinical Genetics Service, V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Jayesh Sheth
- FRIGE-Institute of Human Genetics, Dept of Biochemical and Molecular Genetics, Ahmadabad, Gujarat, and Unique Hospital, Solapur, India
| | - Ajit Gandhi
- FRIGE-Institute of Human Genetics, Dept of Biochemical and Molecular Genetics, Ahmadabad, Gujarat, and Unique Hospital, Solapur, India
| | | | - Fowzan Sami Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Madhulika Kabra
- Division of Genetics, Department of Paediatrics, AIIMS, New Delhi, India
| | - Giuseppe Mercurio
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Gianvincenzo Zuccotti
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Department of Biomedical and Clinical Science L. Sacco, Università degli Studi di Milano, Milan, Italy
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Zhang H, Li L, Kesterke MJ, Lu Y, Qin C. High-Phosphate Diet Improved the Skeletal Development of Fam20c-Deficient Mice. Cells Tissues Organs 2020; 208:25-36. [PMID: 32101876 DOI: 10.1159/000506005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/19/2020] [Indexed: 12/29/2022] Open
Abstract
FAM20C (family with sequence similarity 20 - member C) is a protein kinase that phosphorylates secretory proteins, including the proteins that are essential to the formation and mineralization of calcified tissues. Previously, we reported that inactivation of Fam20c in mice led to hypophosphatemic rickets/osteomalacia along with increased circulating fibroblast growth factor 23 (FGF23) levels and dental defects. In this study, we examined whether a high-phosphate (hPi) diet could rescue the skeletal defects in Fam20c-deficient mice. Fam20c conditional knockout (cKO) mice were generated by crossing female Fam20c-floxed mice (Fam20cfl/fl) with male Sox2-Cre;Fam20cfl/+ mice. The pregnant female Fam20cfi/fl mice were fed either a normal or hPi diet until the litters were weaned. The cKO and control offspring were continuously given a normal or hPi diet for 4 weeks after weaning. Plain X-ray radiography, micro-CT, histology, immunohistochemistry (FGF23, DMP1, OPN, and SOX9), and in situ hybridization (type II and type X collagen) analyses were performed to evaluate the effects of an hPi diet on the mouse skeleton. Plain X-ray radiography and micro-CT radiography analyses showed that the hPi diet improved the shape and mineral density of the Fam20c-deficient femurs/tibiae, and rescued the growth plate defects in the long bone. Histology analyses further demonstrated that an hPi diet nearly completely rescued the growth plate-widening defects in the long bone and restored the expanded hypertrophic zone to nearly normal width. These results suggested that the hPi diet significantly improved the skeletal development of the Fam20c-deficient mice, implying that hypophosphatemia partially contributed to the skeletal defects in Fam20c-deficient subjects.
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Affiliation(s)
- Hua Zhang
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA,
| | - Lili Li
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Matthew J Kesterke
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Yongbo Lu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
| | - Chunlin Qin
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, USA
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27
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Hernández-Zavala A, Cortés-Camacho F, Palma-Lara I, Godínez-Aguilar R, Espinosa AM, Pérez-Durán J, Villanueva-Ocampo P, Ugarte-Briones C, Serrano-Bello CA, Sánchez-Santiago PJ, Bonilla-Delgado J, Yáñez-López MA, Victoria-Acosta G, López-Ornelas A, García Alonso-Themann P, Moreno J, Palacios-Reyes C. Two Novel FAM20C Variants in A Family with Raine Syndrome. Genes (Basel) 2020; 11:genes11020222. [PMID: 32093234 PMCID: PMC7073523 DOI: 10.3390/genes11020222] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/30/2020] [Accepted: 02/14/2020] [Indexed: 12/14/2022] Open
Abstract
Two siblings from a Mexican family who carried lethal Raine syndrome are presented. A newborn term male (case 1) and his 21 gestational week brother (case 2), with a similar osteosclerotic pattern: generalized osteosclerosis, which is more evident in facial bones and cranial base. Prenatal findings at 21 weeks and histopathological features for case 2 are described. A novel combination of biallelic FAM20C pathogenic variants were detected, a maternal cytosine duplication at position 456 and a paternal deletion of a cytosine in position 474 in exon 1, which change the reading frame with a premature termination at codon 207 and 185 respectively. These changes are in concordance with a negative detection of the protein in liver and kidney as shown in case 2. Necropsy showed absence of pancreatic Langerhans Islets, which are reported here for the first time. Corpus callosum absence is added to the few reported cases of brain defects in Raine syndrome. This report shows two new FAM20C variants not described previously, and negative protein detection in the liver and the kidney. We highlight that lethal Raine syndrome is well defined as early as 21 weeks, including mineralization defects and craniofacial features. Pancreas and brain defects found here in FAM20C deficiency extend the functional spectrum of this protein to previously unknown organs.
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Affiliation(s)
- Araceli Hernández-Zavala
- Laboratory of Cellular and Molecular Morphology, Section of Postgraduate Studies and Research, Escuela Superior de Medicina, Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Mexico City 11340, Mexico; (A.H.-Z.); (F.C.-C.); (I.P.-L.)
| | - Fernando Cortés-Camacho
- Laboratory of Cellular and Molecular Morphology, Section of Postgraduate Studies and Research, Escuela Superior de Medicina, Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Mexico City 11340, Mexico; (A.H.-Z.); (F.C.-C.); (I.P.-L.)
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Icela Palma-Lara
- Laboratory of Cellular and Molecular Morphology, Section of Postgraduate Studies and Research, Escuela Superior de Medicina, Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Mexico City 11340, Mexico; (A.H.-Z.); (F.C.-C.); (I.P.-L.)
| | - Ricardo Godínez-Aguilar
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Ana María Espinosa
- Service of Clinical Pharmacology, Hospital General de México, Dr. Balmis 148, Doctores, Cuauhtémoc, Mexico City 06720, Mexico;
| | - Javier Pérez-Durán
- National Institute of Perinatology, Calle Montes Urales 800, Lomas - Virreyes, Lomas de Chapultepec IV Section, Miguel Hidalgo, Mexico City 11000, Mexico; (J.P.-D.); (P.G.A.-T.)
| | - Patricia Villanueva-Ocampo
- Deparment of Ginecology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico;
| | - Carlos Ugarte-Briones
- Department of Pathology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (C.U.-B.); (C.A.S.-B.); (P.J.S.-S.)
| | - Carlos Alberto Serrano-Bello
- Department of Pathology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (C.U.-B.); (C.A.S.-B.); (P.J.S.-S.)
| | - Paula Jesús Sánchez-Santiago
- Department of Pathology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (C.U.-B.); (C.A.S.-B.); (P.J.S.-S.)
| | - José Bonilla-Delgado
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Marco Antonio Yáñez-López
- Department of Radiology & Imagenology, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico;
| | - Georgina Victoria-Acosta
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Adolfo López-Ornelas
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Patricia García Alonso-Themann
- National Institute of Perinatology, Calle Montes Urales 800, Lomas - Virreyes, Lomas de Chapultepec IV Section, Miguel Hidalgo, Mexico City 11000, Mexico; (J.P.-D.); (P.G.A.-T.)
| | - José Moreno
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
| | - Carmen Palacios-Reyes
- Direction and Division of Research, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Magdalena de las Salinas, Gustavo A. Madero, Mexico City 07760, Mexico; (R.G.-A.); (J.B.-D.); (G.V.-A.); (A.L.-O.); (J.M.)
- Correspondence:
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28
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Michigami T. Skeletal mineralization: mechanisms and diseases. Ann Pediatr Endocrinol Metab 2019; 24:213-219. [PMID: 31905439 PMCID: PMC6944863 DOI: 10.6065/apem.2019.24.4.213] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 12/20/2019] [Indexed: 12/22/2022] Open
Abstract
Skeletal mineralization is initiated in matrix vesicles (MVs), the small extracellular vesicles derived from osteoblasts and chondrocytes. Calcium and inorganic phosphate (Pi) taken up by MVs form hydroxyapatite crystals, which propagate on collagen fibrils to mineralize the extracellular matrix. Insufficient calcium or phosphate impairs skeletal mineralization. Because active vitamin D is necessary for intestinal calcium absorption, vitamin D deficiency is a significant cause of rickets/osteomalacia. Chronic hypophosphatemia also results in rickets/osteomalacia. Excessive action of fibroblast growth factor 23 (FGF23), a key regulator of Pi metabolism, leads to renal Pi wasting and impairs vitamin D activation. X-linked hypophosphatemic rickets (XLH) is the most common form of hereditary FGF23-related hypophosphatemia, and enhanced FGF receptor (FGFR) signaling in osteocytes may be involved in the pathogenesis of this disease. Increased extracellular Pi triggers signal transduction via FGFR to regulate gene expression, implying a close relationship between Pi metabolism and FGFR. An anti-FGF23 antibody, burosumab, has recently been developed as a new treatment for XLH. In addition to various forms of rickets/osteomalacia, hypophosphatasia (HPP) is characterized by impaired skeletal mineralization. HPP is caused by inactivating mutations in tissue-nonspecific alkaline phosphatase, an enzyme rich in MVs. The recent development of enzyme replacement therapy using bone-targeting recombinant alkaline phosphatase has improved the prognosis, motor function, and quality of life in patients with HPP. This links impaired skeletal mineralization with various conditions, and unraveling its pathogenesis will lead to more precise diagnoses and effective treatments.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Japan,Address for correspondence: Toshimi Michigami, MD, PhD Department of Bone and Mineral Research, Research I nstitute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, Osaka 594-1101, Japan Tel: +81-725-56-1220 Fax: +81-725-57-3021 E-mail:
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29
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Mamedova E, Dimitrova D, Przhiyalkovskaya E, Buryakina S, Vasilyev E, Tiulpakov A, Belaya Z. Non-lethal Raine Syndrome in a Middle-Aged Woman Caused by a Novel FAM20C Mutation. Calcif Tissue Int 2019; 105:567-572. [PMID: 31471673 DOI: 10.1007/s00223-019-00599-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/16/2019] [Indexed: 12/21/2022]
Abstract
Raine syndrome is a rare hereditary disease caused by mutations in the FAM20C gene. Only 18 non-lethal cases have been reported, the majority of them being children and young adults aged up to 30. Due to the rarity of the disease, genotype-phenotype correlations are not available and patient life expectancy is unknown, thus making descriptions of each novel case of particular importance. In this article, we describe a case of an Armenian woman, living in Russia, who was followed-up from age 36 to 39, presenting with pain in the extremities, osteosclerosis with periosteal bone formation, multiple calcifications in solid organs, midface hypoplasia, exophthalmos, amelogenesis imperfecta, shortening of distal phalanges, pectus excavatum, and hypophosphatemia due to renal phosphate wasting. Whole exome sequencing was performed on NextSeq 550 (Illumina, USA) and compound heterozygous variants were identified in the FAM20C gene (reference sequence NM_020223): a frameshift insertion c.1107_1108insTACTG (p.Tyr369fs) and a missense substitution c.1375C > G (p.Arg459Gly). This is the first reported case of a middle-aged patient presenting classical symptoms of Raine syndrome caused by novel compound heterozygous mutations in the conserved C-terminal domain of FAM20C gene.
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Affiliation(s)
- Elizaveta Mamedova
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation.
| | - Diana Dimitrova
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Elena Przhiyalkovskaya
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Svetlana Buryakina
- Department of Radiology, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Evgeny Vasilyev
- Department and Laboratory of Inherited Endocrine Disorders, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Anatoly Tiulpakov
- Department and Laboratory of Inherited Endocrine Disorders, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
| | - Zhanna Belaya
- Department of Neuroendocrinology and Bone Diseases, Endocrinology Research Centre, Ulitsa Dmitriya Ulianova, 11, Moscow, 117036, Russian Federation
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30
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Hung CY, Rodriguez M, Roberts A, Bauer M, Mihalek I, Bodamer O. A novel FAM20C mutation causes a rare form of neonatal lethal Raine syndrome. Am J Med Genet A 2019; 179:1866-1871. [PMID: 31297960 DOI: 10.1002/ajmg.a.61291] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/08/2019] [Accepted: 06/23/2019] [Indexed: 02/06/2023]
Abstract
Raine syndrome is a rare, autosomal recessive, osteosclerotic bone dysplasia due to pathogenic variants in FAM20C. The clinical phenotype is characterized by generalized osteosclerosis affecting all bones, cerebral calcifications, and craniofacial dysmorphism. Most cases present during the neonatal period with early lethality due to pulmonary hypoplasia and respiratory compromise while only few affected individuals have been reported to survive into adulthood. FAM20C is a ubiquitously expressed protein kinase that contains five functional domains including a catalytic domain, a binding pocket for FAM20A and three distinct N-glycosylation sites. We report a newborn infant with a history of prenatal onset fractures, generalized osteosclerosis, and craniofacial dysmorphism and early lethality. The clinical presentation was highly suggestive of Raine syndrome. A homozygous, novel missense variant in exon 5 of FAM20C (c.1007T>G; p.Met336Arg) was identified by targeted Sanger sequencing. Following in silico analysis and mapping of the variant on a three-dimensional (3D) model of FAM20C it is predicted to be deleterious and to affect N-glycosylation, protein folding, and subsequent secretion of FAM20C. In addition, we reviewed all published FAM20C mutations and observed that most pathogenic variants affect functional regions within the protein establishing evidence for an emerging genotype-phenotype correlation.
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Affiliation(s)
- Christina Y Hung
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Mario Rodriguez
- Hussmann Institute of Genomics, University of Miami, Miami, Florida
| | - Abra Roberts
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
| | - Mislen Bauer
- Division of Clinical Genetics and Metabolism, Nicklas Children's Hospital, Miami, Florida
| | - Ivana Mihalek
- Department of Molecular Medicine and Biotechnology, University of Rijeka, Rijeka, Croatia
| | - Olaf Bodamer
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts
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31
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Rolvien T, Kornak U, Schinke T, Amling M, Oheim R. A novel FAM20C mutation causing hypophosphatemic osteomalacia with osteosclerosis (mild Raine syndrome) in an elderly man with spontaneous osteonecrosis of the knee. Osteoporos Int 2019; 30:685-689. [PMID: 30151622 DOI: 10.1007/s00198-018-4667-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 08/12/2018] [Indexed: 12/11/2022]
Abstract
Raine syndrome is characterized by FGF23-mediated hypophosphatemic osteomalacia with osteosclerosis caused by mutations in the FAM20C gene. We report a case of a 72-year-old man who presented with rapid progressive spontaneous osteonecrosis of the knee (SONK). A full osteologic assessment including dual energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and serum analyses revealed a high bone mass in the lumbar spine and hip (DXA T-score + 7.5 and + 4.7/+4.2) with increased bone microstructural parameters in the distal radius and tibia (BV/TV 127%, 140% of the age-matched mean, respectively), as well as a low bone turnover state. Phosphate levels were low due to renal phosphate wasting and high FGF23 levels (126.5 pg/ml, reference range 23.2-95.4 pg/ml). Using gene panel sequencing, we identified a novel FAM20C heterozygous missense mutation in combination with a homozygous duplication that potentially alters splicing. Taken together, this is the first case of mild Raine syndrome with spontaneous osteonecrosis of the knee, phosphate wasting, and a pronounced trabecular high bone mass phenotype.
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Affiliation(s)
- T Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- Department of Orthopedics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - U Kornak
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Institute of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Berlin-Brandenburg School for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany
- FG Development and Disease, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - T Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - R Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany.
- National Bone Board, Martin Zeitz Center for Rare Diseases, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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32
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Abstract
Phosphate is essential for skeletal mineralization, and its chronic deficiency leads to rickets and osteomalacia. Skeletal mineralization starts in matrix vesicles (MVs) derived from the plasma membrane of osteoblasts and chondrocytes. MVs contain high activity of tissue non-specific alkaline phosphatase (TNSALP), which hydrolyzes phosphoric esters such as pyrophosphates (PPi) to produce inorganic orthophosphates (Pi). Extracellular Pi in the skeleton is taken up by MVs through type III sodium/phosphate (Na+/Pi) cotransporters and forms hydroxyapatite. In addition to its roles in MV-mediated skeletal mineralization, accumulating evidence has revealed that extracellular Pi evokes signal transduction and regulates cellular function. Pi induces apoptosis of hypertrophic chondrocytes, which is a critical step for endochondral ossification. Extracellular Pi also regulates the expression of various genes including those related to proliferation, differentiation, and mineralization. In vitro cell studies have demonstrated that an elevation in extracellular Pi level leads to the activation of fibroblast growth factor receptor (FGFR), Raf/MEK (mitogen-activated protein kinase/ERK kinase)/ERK (extracellular signal-regulated kinase) pathway, where the type III Na+/Pi cotransporter PiT-1 may be involved. Responsiveness of skeletal cells to extracellular Pi suggests their ability to sense and adapt to an alteration in Pi availability in their environment. Involvement of FGFR in the Pi-evoked signal transduction is interesting because enhanced FGFR signaling in osteoblasts/osteocytes might be responsible for the overproduction of FGF23, a key molecule in phosphate homeostasis, in a mouse model for human X-linked hypophosphatemic rickets (XLH). Impaired Pi sensing may be a pathogenesis of XLH, which needs to be clarified in future.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Izumi, Japan
- *Correspondence: Toshimi Michigami
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
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Michigami T, Kawai M, Yamazaki M, Ozono K. Phosphate as a Signaling Molecule and Its Sensing Mechanism. Physiol Rev 2018; 98:2317-2348. [DOI: 10.1152/physrev.00022.2017] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In mammals, phosphate balance is maintained by influx and efflux via the intestines, kidneys, bone, and soft tissue, which involves multiple sodium/phosphate (Na+/Pi) cotransporters, as well as regulation by several hormones. Alterations in the levels of extracellular phosphate exert effects on both skeletal and extra-skeletal tissues, and accumulating evidence has suggested that phosphate itself evokes signal transduction to regulate gene expression and cell behavior. Several in vitro studies have demonstrated that an elevation in extracellular Piactivates fibroblast growth factor receptor, Raf/MEK (mitogen-activated protein kinase/ERK kinase)/ERK (extracellular signal-regulated kinase) pathway and Akt pathway, which might involve the type III Na+/Picotransporter PiT-1. Excessive phosphate loading can lead to various harmful effects by accelerating ectopic calcification, enhancing oxidative stress, and dysregulating signal transduction. The responsiveness of mammalian cells to altered extracellular phosphate levels suggests that they may sense and adapt to phosphate availability, although the precise mechanism for phosphate sensing in mammals remains unclear. Unicellular organisms, such as bacteria and yeast, use some types of Pitransporters and other molecules, such as kinases, to sense the environmental Piavailability. Multicellular animals may need to integrate signals from various organs to sense the phosphate levels as a whole organism, similarly to higher plants. Clarification of the phosphate-sensing mechanism in humans may lead to the development of new therapeutic strategies to prevent and treat diseases caused by phosphate imbalance.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Masanobu Kawai
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Miwa Yamazaki
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Keiichi Ozono
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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Kinoshita Y, Fukumoto S. X-Linked Hypophosphatemia and FGF23-Related Hypophosphatemic Diseases: Prospect for New Treatment. Endocr Rev 2018; 39:274-291. [PMID: 29381780 DOI: 10.1210/er.2017-00220] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/23/2018] [Indexed: 12/21/2022]
Abstract
Phosphate plays essential roles in many biological processes, and the serum phosphate level is tightly controlled. Chronic hypophosphatemia causes impaired mineralization of the bone matrix and results in rickets and osteomalacia. Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that regulates phosphate metabolism. FGF23 excess induces hypophosphatemia via impaired phosphate reabsorption in the renal proximal tubules and decreased phosphate absorption in the intestines. There are several types of genetic and acquired FGF23-related hypophosphatemic diseases. Among these diseases, X-linked hypophosphatemia (XLH), which is caused by inactivating mutations in the phosphate-regulating endopeptidase homolog, X-linked (PHEX) gene, is the most prevalent form of genetic FGF23-related hypophosphatemic rickets. Another clinically relevant form of FGF23-related hypophosphatemic disease is tumor-induced osteomalacia (TIO), a paraneoplastic syndrome associated with FGF23-producing tumors. A combination of active vitamin D and phosphate salts is the current medical therapy used to treat patients with XLH and inoperative TIO. However, this therapy has certain efficacy- and safety-associated limitations. Several measures to inhibit FGF23 activity have been considered as possible new treatments for FGF23-related hypophosphatemic diseases. In particular, a humanized monoclonal antibody for FGF23 (burosumab) is a promising treatment in patients with XLH and TIO. This review will focus on the phosphate metabolism and the pathogenesis and treatment of FGF23-related hypophosphatemic diseases.
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Affiliation(s)
- Yuka Kinoshita
- Division of Nephrology and Endocrinology, Department of Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - Seiji Fukumoto
- Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
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35
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Sheth J, Bhavsar R, Gandhi A, Sheth F, Pancholi D. A case of Raine syndrome presenting with facial dysmorphy and review of literature. BMC MEDICAL GENETICS 2018; 19:76. [PMID: 29751744 PMCID: PMC5948820 DOI: 10.1186/s12881-018-0593-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 04/25/2018] [Indexed: 11/29/2022]
Abstract
Background Raine syndrome (RS) – an extremely rare autosomal recessive genetic disorder, is caused by a biallelic mutation in the FAM20C gene. Some of the most common clinical features include generalized osteosclerosis with a periosteal bone formation, dysmorphic face, and thoracic hypoplasia. Many cases have also been reported with oro-dental abnormalities, and developmental delay. Most of the cases result in neonatal death. However, a few non-lethal RS cases have been reported where patients survive till adulthood and exhibits a heterogeneous clinical phenotype. Clinical diagnosis of RS has been done through facial appearance and radiological findings, while confirmatory diagnosis has been conducted through a molecular study of the FAM20C gene. Case presentation A 6-year-old girl was born to healthy third degree consanguineous parents. She presented with facial dysmorphy, delayed speech, and delayed cognition. Radiography showed small sclerotic areas in the lower part of the right femur, and an abnormally-shaped skull with minimal sclerosis in the lower occipital region. Computer tomography scan of the brain revealed mild cortical atrophy, and MRI scan of the brain showed corpus callosal dysgenesis with the absence of the rostral area. Chromosome banding at 500 band resolution showed a normal female karyotype. No quantitative genomic imbalance was detected by aCGH. Further study conducted using Clinical Exome Sequencing identified a homozygous missense variation c.1228 T > A (p.Ser410Thr) in the exon 6 of FAM20C gene – a likely pathogenic variant that confirmed the clinical diagnosis of RS. The variant was confirmed in the proband and her parents using Sanger sequencing. Prenatal diagnosis during subsequent pregnancy revealed heterozygous status of the fetus, and a normal carrier child was delivered at term. Conclusions The syndrome revealed markedly variable presentations such as facial dysmorphy and developmental delay, and was localized to diffuse bone osteosclerosis. Clinical indications, striking radiological findings and molecular testing of FAM20C gene confirmed the diagnosis of RS. A rarity of the disorder and inconsistent phenotype hindered the establishment of genotype-phenotype correlations in RS. Therefore, reporting more cases and conducting further research would be crucial in defining the variable radiologic and molecular defects of the lethal and non-lethal forms of this syndrome. Electronic supplementary material The online version of this article (10.1186/s12881-018-0593-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jayesh Sheth
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380015, India.
| | - Riddhi Bhavsar
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380015, India
| | - Ajit Gandhi
- Unique Hospital, Main Road, South Kasba, Solapur, 413007, India
| | - Frenny Sheth
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380015, India
| | - Dhairya Pancholi
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380015, India
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36
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Tamai K, Tada K, Takeuchi A, Nakamura M, Marunaka H, Washio Y, Tanaka H, Miya F, Okamoto N, Kageyama M. Fetal ultrasonographic findings including cerebral hyperechogenicity in a patient with non-lethal form of Raine syndrome. Am J Med Genet A 2018; 176:682-686. [PMID: 29341424 DOI: 10.1002/ajmg.a.38598] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/05/2017] [Accepted: 12/12/2017] [Indexed: 12/14/2022]
Abstract
Raine syndrome is a rare osteosclerotic bone dysplasia characterized by craniofacial anomalies and intracranial calcification. Most patients with Raine syndrome are of Arab ancestry and die during the neonatal period. We herein report a Japanese patient with non-lethal Raine syndrome who presented with characteristic cerebral hyperechogenicity and a hypoplastic nose by fetal ultrasonography. She was admitted to the NICU due to pyriform aperture stenosis. Craniofacial abnormalities, intracranial calcification, osteosclerosis, chondrodysplasia punctata, and a mutation of FAM20C was identified. She was subsequently discharged without surgical intervention and is now 2 years old with mild neurodevelopmental delays. Images of cerebral hyperechogenicity by fetal ultrasonography in a non-lethal case were described herein for the first time. This patient represents a rare occurrence of a child with Raine syndrome born to Japanese parents and confirms that this syndrome is not always lethal. Even if Raine syndrome is suspected in a fetus due to cerebral hyperechogenicity and a hypoplastic nose, cerebral hyperechogenicity without pulmonary hypoplasia does not always predict lethality or severe neurodevelopmental delays. The information provided herein will be useful for prenatal counseling.
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Affiliation(s)
- Kei Tamai
- Department of Neonatology, NHO Okayama Medical Center, Okayama, Japan
| | - Katsuhiko Tada
- Department of Obstetrics and Gynecology, NHO Okayama Medical Center, Okayama, Japan
| | - Akihito Takeuchi
- Department of Neonatology, NHO Okayama Medical Center, Okayama, Japan
| | - Makoto Nakamura
- Department of Neonatology, NHO Okayama Medical Center, Okayama, Japan
| | - Hidenori Marunaka
- Department of Otolaryngology, NHO Okayama Medical Center, Okayama, Japan
| | - Yosuke Washio
- Department of Pediatrics, Okayama University Hospital, Okayama, Japan
| | - Hiroyuki Tanaka
- Department of Pediatrics, Okayama Saiseikai General Hospital, Okayama, Japan
| | - Fuyuki Miya
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.,Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Misao Kageyama
- Department of Neonatology, NHO Okayama Medical Center, Okayama, Japan
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37
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Abstract
Rickets is a metabolic bone disease that develops as a result of inadequate mineralization of growing bone due to disruption of calcium, phosphorus and/or vitamin D metabolism. Nutritional rickets remains a significant child health problem in developing countries. In addition, several rare genetic causes of rickets have also been described, which can be divided into two groups. The first group consists of genetic disorders of vitamin D biosynthesis and action, such as vitamin D-dependent rickets type 1A (VDDR1A), vitamin D-dependent rickets type 1B (VDDR1B), vitamin D-dependent rickets type 2A (VDDR2A), and vitamin D-dependent rickets type 2B (VDDR2B). The second group involves genetic disorders of excessive renal phosphate loss (hereditary hypophosphatemic rickets) due to impairment in renal tubular phosphate reabsorption as a result of FGF23-related or FGF23-independent causes. In this review, we focus on clinical, laboratory and genetic characteristics of various types of hereditary rickets as well as differential diagnosis and treatment approaches.
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Affiliation(s)
- Sezer Acar
- Dokuz Eylül University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | - Korcan Demir
- Dokuz Eylül University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | - Yufei Shi
- King Faisal Specialist Hospital & Research Centre, Department of Genetics, Riyadh, Saudi Arabia
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38
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Abstract
Rickets is a bone disease associated with abnormal serum calcium and phosphate levels. The clinical presentation is heterogeneous and depends on the age of onset and pathogenesis but includes bowing deformities of the legs, short stature and widening of joints. The disorder can be caused by nutritional deficiencies or genetic defects. Mutations in genes encoding proteins involved in vitamin D metabolism or action, fibroblast growth factor 23 (FGF23) production or degradation, renal phosphate handling or bone mineralization have been identified. The prevalence of nutritional rickets has substantially declined compared with the prevalence 200 years ago, but the condition has been re-emerging even in some well-resourced countries; prematurely born infants or breastfed infants who have dark skin types are particularly at risk. Diagnosis is usually established by medical history, physical examination, biochemical tests and radiography. Prevention is possible only for nutritional rickets and includes supplementation or food fortification with calcium and vitamin D either alone or in combination with sunlight exposure. Treatment of typical nutritional rickets includes calcium and/or vitamin D supplementation, although instances infrequently occur in which phosphate repletion may be necessary. Management of heritable types of rickets associated with defects in vitamin D metabolism or activation involves the administration of vitamin D metabolites. Oral phosphate supplementation is usually indicated for FGF23-independent phosphopenic rickets, whereas the conventional treatment of FGF23-dependent types of rickets includes a combination of phosphate and activated vitamin D; an anti-FGF23 antibody has shown promising results and is under further study.
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39
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Baumgart SJ, Najafova Z, Hossan T, Xie W, Nagarajan S, Kari V, Ditzel N, Kassem M, Johnsen SA. CHD1 regulates cell fate determination by activation of differentiation-induced genes. Nucleic Acids Res 2017; 45:7722-7735. [PMID: 28475736 PMCID: PMC5570082 DOI: 10.1093/nar/gkx377] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 05/03/2017] [Indexed: 12/12/2022] Open
Abstract
The coordinated temporal and spatial activation of gene expression is essential for proper stem cell differentiation. The Chromodomain Helicase DNA-binding protein 1 (CHD1) is a chromatin remodeler closely associated with transcription and nucleosome turnover downstream of the transcriptional start site (TSS). In this study, we show that CHD1 is required for the induction of osteoblast-specific gene expression, extracellular-matrix mineralization and ectopic bone formation in vivo. Genome-wide occupancy analyses revealed increased CHD1 occupancy around the TSS of differentiation-activated genes. Furthermore, we observed that CHD1-dependent genes are mainly induced during osteoblast differentiation and are characterized by higher levels of CHD1 occupancy around the TSS. Interestingly, CHD1 depletion resulted in increased pausing of RNA Polymerase II (RNAPII) and decreased H2A.Z occupancy close to the TSS, but not at enhancer regions. These findings reveal a novel role for CHD1 during osteoblast differentiation and provide further insights into the intricacies of epigenetic regulatory mechanisms controlling cell fate determination.
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Affiliation(s)
- Simon J Baumgart
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Zeynab Najafova
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Tareq Hossan
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Wanhua Xie
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Sankari Nagarajan
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Vijayalakshmi Kari
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Nicholas Ditzel
- Molecular Endocrinology and Stem Cell Research Unit (KMEB), University Hospital of Odense and University of Southern Denmark, Odense 5000, Denmark
| | - Moustapha Kassem
- Molecular Endocrinology and Stem Cell Research Unit (KMEB), University Hospital of Odense and University of Southern Denmark, Odense 5000, Denmark
| | - Steven A Johnsen
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany
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40
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Clinkenbeard EL, White KE. Heritable and acquired disorders of phosphate metabolism: Etiologies involving FGF23 and current therapeutics. Bone 2017; 102:31-39. [PMID: 28159712 PMCID: PMC5537045 DOI: 10.1016/j.bone.2017.01.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 01/20/2017] [Accepted: 01/29/2017] [Indexed: 10/20/2022]
Abstract
Phosphate is critical for many cellular processes and structural functions, including as a key molecule for nucleic acid synthesis and energy metabolism, as well as hydroxyapatite formation in bone. Therefore it is critical to maintain tight regulation of systemic phosphate levels. Based upon its broad biological importance, disruption of normal phosphate homeostasis has detrimental effects on skeletal integrity and overall health. Investigating heritable diseases of altered phosphate metabolism has led to key discoveries underlying the regulation and systemic actions of the phosphaturic hormone Fibroblast growth factor-23 (FGF23). Both molecular and clinical studies have revealed novel targets for the development and optimization of therapies for disorders of phosphate handling. This review will focus upon the bridge between genetic discoveries involving disorders of altered FGF23 bioactivity, as well as describe how these findings have translated into pharmacologic application.
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Affiliation(s)
- Erica L Clinkenbeard
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kenneth E White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.
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41
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Liu P, Ma S, Zhang H, Liu C, Lu Y, Chen L, Qin C. Specific ablation of mouse Fam20C in cells expressing type I collagen leads to skeletal defects and hypophosphatemia. Sci Rep 2017; 7:3590. [PMID: 28620244 PMCID: PMC5472603 DOI: 10.1038/s41598-017-03960-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/09/2017] [Indexed: 11/30/2022] Open
Abstract
FAM20C mutations in humans cause Raine syndrome and our previous studies showed that global inactivation of mouse Fam20C led to bone and dental defects. By crossbreeding 2.3
kb Col 1a1-Cre mice with Fam20Cflox/flox mice, we created 2.3
kb Col 1a1-Cre;Fam20Cfoxl/flox (cKO) mice, in which Fam20C was inactivated in cells expressing Type I collagen. This study showed that the long bones of cKO mice were shorter and had a lower level of mineralization compared to the normal mice. The collagen fibrils in Fam20C-deficient bone were disorganized and thicker while the growth plate cartilage in cKO mice was disorganized and wider compared to the normal mice. The Fam20C-deficient bone had a lower level of dentin matrix protein 1, and higher levels of osteopontin and bone sialoprotein than the normal. The blood of cKO mice had an elevated level of fibroblast growth factor 23 and reduced level of phosphorus. These findings indicate that inactivation of Fam20C in cells expressing type I collagen led to skeletal defects and hypophosphatemia. The altered levels of dentin matrix protein 1 and osteopontin in Fam20C-deficient bone may be significant contributors to the mineralized tissue defects in human patients and animals suffering from the functional loss of FAM20C.
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Affiliation(s)
- Peihong Liu
- Department of Periodontics, Harbin Medical University School of Stomatology, Harbin, Heilongjiang, 150001, China.,Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, 75246, USA
| | - Su Ma
- Department of Periodontics, Harbin Medical University School of Stomatology, Harbin, Heilongjiang, 150001, China.,Longjiang Scholar Laboratory, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, 150001, China
| | - Hua Zhang
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, 75246, USA
| | - Chao Liu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, 75246, USA
| | - Yongbo Lu
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, 75246, USA
| | - Li Chen
- Longjiang Scholar Laboratory, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, 150001, China.
| | - Chunlin Qin
- Department of Biomedical Sciences, Texas A&M University College of Dentistry, Dallas, Texas, 75246, USA.
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42
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Cui J, Zhu Q, Zhang H, Cianfrocco MA, Leschziner AE, Dixon JE, Xiao J. Structure of Fam20A reveals a pseudokinase featuring a unique disulfide pattern and inverted ATP-binding. eLife 2017; 6. [PMID: 28432788 PMCID: PMC5413348 DOI: 10.7554/elife.23990] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 04/20/2017] [Indexed: 12/19/2022] Open
Abstract
Mutations in FAM20A cause tooth enamel defects known as Amelogenesis Imperfecta (AI) and renal calcification. We previously showed that Fam20A is a secretory pathway pseudokinase and allosterically activates the physiological casein kinase Fam20C to phosphorylate secreted proteins important for biomineralization (Cui et al., 2015). Here we report the nucleotide-free and ATP-bound structures of Fam20A. Fam20A exhibits a distinct disulfide bond pattern mediated by a unique insertion region. Loss of this insertion due to abnormal mRNA splicing interferes with the structure and function of Fam20A, resulting in AI. Fam20A binds ATP in the absence of divalent cations, and strikingly, ATP is bound in an inverted orientation compared to other kinases. Fam20A forms a dimer in the crystal, and residues in the dimer interface are critical for Fam20C activation. Together, these results provide structural insights into the function of Fam20A and shed light on the mechanism by which Fam20A mutations cause disease. DOI:http://dx.doi.org/10.7554/eLife.23990.001
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Affiliation(s)
- Jixin Cui
- Department of Pharmacology, University of California, San Diego, United States
| | - Qinyu Zhu
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,The State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Hui Zhang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.,The State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Michael A Cianfrocco
- Department of Cellular and Molecular Medicine, University of California, San Diego, United States
| | - Andres E Leschziner
- Department of Cellular and Molecular Medicine, University of California, San Diego, United States
| | - Jack E Dixon
- Department of Pharmacology, University of California, San Diego, United States.,Department of Cellular and Molecular Medicine, University of California, San Diego, United States.,Department of Chemistry and Biochemistry, University of California, San Diego, United States
| | - Junyu Xiao
- The State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
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43
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Whyte MP, McAlister WH, Fallon MD, Pierpont ME, Bijanki VN, Duan S, Otaify GA, Sly WS, Mumm S. Raine Syndrome (OMIM #259775), Caused By FAM20C Mutation, Is Congenital Sclerosing Osteomalacia With Cerebral Calcification (OMIM 259660). J Bone Miner Res 2017; 32:757-769. [PMID: 27862258 DOI: 10.1002/jbmr.3034] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 10/06/2016] [Accepted: 10/30/2016] [Indexed: 12/12/2022]
Abstract
In 1985, we briefly reported infant sisters with a unique, lethal, autosomal recessive disorder designated congenital sclerosing osteomalacia with cerebral calcification. In 1986, this condition was entered into Mendelian Inheritance In Man (MIM) as osteomalacia, sclerosing, with cerebral calcification (MIM 259660). However, no attestations followed. Instead, in 1989 Raine and colleagues published an affected neonate considering unprecedented the striking clinical and radiographic features. In 1992, "Raine syndrome" entered MIM formally as osteosclerotic bone dysplasia, lethal (MIM #259775). In 2007, the etiology emerged as loss-of-function mutation of FAM20C that encodes family with sequence similarity 20, member C. FAM20C is highly expressed in embryonic calcified tissues and encodes a kinase (dentin matrix protein 4) for most of the secreted phosphoproteome including FGF23, osteopontin, and other regulators of skeletal mineralization. Herein, we detail the clinical, radiological, biochemical, histopathological, and FAM20C findings of our patients. Following premortem tetracycline labeling, the proposita's non-decalcified skeletal histopathology after autopsy indicated no rickets but documented severe osteomalacia. Archival DNA revealed the sisters were compound heterozygotes for a unique missense mutation and a novel deletion in FAM20C. Individuals heterozygous for the missense mutation seemed to prematurely fuse their metopic suture and develop a metopic ridge sometimes including trigonocephaly. Our findings clarify FAM20C's role in hard tissue formation and mineralization, and show that Raine syndrome is congenital sclerosing osteomalacia with cerebral calcification. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA.,Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA
| | - William H McAlister
- Department of Pediatric Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine at St. Louis Children's Hospital, St. Louis, MO, USA
| | - Michael D Fallon
- Department of Surgical Pathology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Mary Ella Pierpont
- Department of Pediatrics, University of Minnesota School of Medicine, and Children's Hospitals and Clinics of Minnesota, Minneapolis, MN, USA
| | - Vinieth N Bijanki
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA
| | - Shenghui Duan
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA
| | - Ghada A Otaify
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA.,Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA.,Department of Clinical Genetics, Division of Human Genetics and Genome Research, Centre of Excellence of Human Genetics, National Research Centre, Cairo, Egypt
| | - William S Sly
- E.A. Doisey Department of Biochemistry, St. Louis University School of Medicine, St. Louis, MO, USA
| | - Steven Mumm
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, St. Louis, MO, USA.,Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA
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44
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Abstract
When normal physiologic functions go awry, disorders and disease occur. This is universal; even for the osteocyte, a cell embedded within the mineralized matrix of bone. It was once thought that this cell was simply a placeholder in bone. Within the last decade, the number of studies of osteocytes has increased dramatically, leading to the discovery of novel functions of these cells. With the discovery of novel physiologic functions came the discoveries of how these cells can also be responsible for not only bone diseases and disorders, but also those of the kidney, heart, and potentially muscle.
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Affiliation(s)
- Lynda F Bonewald
- Indiana Center for Musculoskeletal Health, VanNuys Medical Science Building, MS 5055, 635 Barnhill Drive, Indianapolis, IN 46202, USA; Department of Anatomy and Cell Biology, VanNuys Medical Science Building, MS 5035, Indianapolis, IN 46202, USA; Department of Orthopaedic Surgery, 1120 West Michigan Street, Suite 600, Indianapolis, IN 46202, USA.
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45
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Nishino J, Yamazaki M, Kawai M, Tachikawa K, Yamamoto K, Miyagawa K, Kogo M, Ozono K, Michigami T. Extracellular Phosphate Induces the Expression of Dentin Matrix Protein 1 Through the FGF Receptor in Osteoblasts. J Cell Biochem 2017; 118:1151-1163. [PMID: 27639037 DOI: 10.1002/jcb.25742] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 09/14/2016] [Indexed: 12/21/2022]
Abstract
Dentin matrix protein 1 (Dmp1) is an extracellular matrix protein involved in phosphate metabolism and biomineralization, and its expression markedly increases during the maturation of osteoblasts into osteocytes. We previously reported that an increased level of inorganic phosphate (Pi) in media up-regulated the expression of Dmp1 in primary osteocytes isolated from mouse bones. In the present study, we found that elevated extracellular Pi strongly induced the expression of Dmp1 in osteoblasts and explored its underlying mechanism of action. In an osteoblastic cell line MC3T3-E1, increases in extracellular Pi induced the phosphorylation of ERK1/2 and up-regulated the expression of Dmp1, fibroblast growth factor 2 (Fgf2), and Fgf receptor 1 (Fgfr1). A co-treatment with the MEK inhibitor U0126 abolished the increase in the expression of Dmp1 and Fgfr1 by elevated Pi, suggesting the involvement of the MEK/ERK pathway in this up-regulation. Elevated extracellular Pi also resulted in the phosphorylation of FGF receptor substrate 2α (FRS2α), which was diminished by knockdown of Slc20a1 encoding Pit1 sodium-phosphate co-transporter. The co-treatment with an inhibitor against FGFR (SU5402) abolished the up-regulation of Dmp1 induced by elevated extracellular Pi. In primary osteoblasts, a treatment with 4 mM Pi transiently increased the expression of early growth response 1 (Egr1) before the up-regulation of Dmp1. These results indicate that FGFR mediates the direct effects of extracellular Pi on the expression of Dmp1 in osteoblasts and enhance the close relationship between the signaling evoked by elevated extracellular Pi and FGF/FGFR signaling. J. Cell. Biochem. 118: 1151-1163, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jin Nishino
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan.,First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Miwa Yamazaki
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan
| | - Masanobu Kawai
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan
| | - Kanako Tachikawa
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan
| | - Keiko Yamamoto
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan.,Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Kazuaki Miyagawa
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan.,First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Mikihiko Kogo
- First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka 594-1101, Japan
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46
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Hytönen MK, Lohi H. Canine models of human rare disorders. Rare Dis 2016; 4:e1241362. [PMID: 27803843 PMCID: PMC5070630 DOI: 10.1080/21675511.2016.1241362] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 08/10/2016] [Accepted: 09/21/2016] [Indexed: 12/21/2022] Open
Abstract
Millions of children worldwide are born with rare and debilitating developmental disorders each year. Although an increasing number of these conditions are being recognized at the molecular level, the characterization of the underlying pathophysiology remains a grand challenge. This is often due to the lack of appropriate patient material or relevant animal models. Dogs are coming to the rescue as physiologically relevant large animal models. Hundreds of spontaneous genetic conditions have been described in dogs, most with close counterparts to human rare disorders. Our recent examples include the canine models of human Caffey (SLC37A2), van den Ende-Gupta (SCARF2) and Raine (FAM20C) syndromes. These studies demonstrate the pathophysiological similarity of human and canine syndromes, and suggest that joint efforts to characterize both human and canine rare diseases could provide additional benefits to the advancement of the field of rare diseases. Besides revealing new candidate genes, canine models allow access to experimental resources such as cells, tissues and even live animals for research and intervention purposes.
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Affiliation(s)
- Marjo K Hytönen
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland; Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland; The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Hannes Lohi
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland; Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland; The Folkhälsan Institute of Genetics, Helsinki, Finland
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47
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Elalaoui SC, Al-Sheqaih N, Ratbi I, Urquhart JE, O'Sullivan J, Bhaskar S, Williams SS, Elalloussi M, Lyahyai J, Sbihi L, Cherkaoui Jaouad I, Sbihi A, Newman WG, Sefiani A. Non lethal Raine syndrome and differential diagnosis. Eur J Med Genet 2016; 59:577-583. [PMID: 27667191 DOI: 10.1016/j.ejmg.2016.09.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/18/2016] [Indexed: 12/12/2022]
Abstract
Raine syndrome is a rare autosomal recessive bone dysplasia characterized by characteristic facial features with exophthalmos and generalized osteosclerosis. Amelogenesis imperfecta, hearing loss, seizures, and intracerebral calcification are apparent in some affected individuals. Originally, Raine syndrome was originally reported as a lethal syndrome. However, recently a milder phenotype, compatible with life, has been described. Biallelic variants inFAM20C, encoding aGolgi casein kinase involved in biomineralisation, have been identified in affected individuals. We report here a consanguineous Moroccan family with two affected siblingsa girl aged 18 and a boy of 15years. Clinical features, including learning disability, seizures and amelogenesis imperfecta, initially suggested a diagnosis of Kohlschutter-Tonz syndrome. However,a novel homozygous FAM20Cvariantc.676T > A, p.(Trp226Arg) was identified in the affected siblings. Our report reinforces that Raine syndrome is compatible with life, and that mild hypophosphatemia and amelogenesis imperfecta are key features of the attenuated form.
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Affiliation(s)
- Siham Chafai Elalaoui
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco; Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Morocco.
| | - Nada Al-Sheqaih
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK; Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester, M13 9WL, UK
| | - Ilham Ratbi
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco
| | - Jill E Urquhart
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK; Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester, M13 9WL, UK
| | - James O'Sullivan
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK; Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester, M13 9WL, UK
| | - Sanjeev Bhaskar
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK
| | - Simon S Williams
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK
| | - Mustapha Elalloussi
- Service d'Odontologie Pédiatrique, Faculté de Médecine Dentaire, Université Mohammed V, Rabat, Morocco
| | - Jaber Lyahyai
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco
| | - Leila Sbihi
- Service de Radiologie, Hopital Ibn Sina, Rabat, Morocco
| | - Imane Cherkaoui Jaouad
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco; Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Morocco
| | | | - William G Newman
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester Academic Health Sciences Centre, Manchester, M13 9WL, UK; Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester, M13 9WL, UK
| | - Abdelaziz Sefiani
- Centre de Génomique Humaine, Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Morocco; Département de Génétique Médicale, Institut National d'Hygiène, Rabat, Morocco
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48
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Loss of epithelial FAM20A in mice causes amelogenesis imperfecta, tooth eruption delay and gingival overgrowth. Int J Oral Sci 2016; 8:98-109. [PMID: 27281036 PMCID: PMC4932772 DOI: 10.1038/ijos.2016.14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2016] [Indexed: 12/24/2022] Open
Abstract
FAM20A has been studied to a very limited extent. Mutations in human FAM20A cause amelogenesis imperfecta, gingival fibromatosis and kidney problems. It would be desirable to systemically analyse the expression of FAM20A in dental tissues and to assess the pathological changes when this molecule is specifically nullified in individual tissues. Recently, we generated mice with a Fam20A-floxed allele containing the beta-galactosidase reporter gene. We analysed FAM20A expression in dental tissues using X-Gal staining, immunohistochemistry and in situ hybridization, which showed that the ameloblasts in the mouse mandibular first molar began to express FAM20A at 1 day after birth, and the reduced enamel epithelium in erupting molars expressed a significant level of FAM20A. By breeding K14-Cre mice with Fam20Aflox/flox mice, we created K14-Cre;Fam20Aflox/flox (conditional knock out, cKO) mice, in which Fam20A was inactivated in the epithelium. We analysed the dental tissues of cKO mice using X-ray radiography, histology and immunohistochemistry. The molar enamel matrix in cKO mice was much thinner than normal and was often separated from the dentinoenamel junction. The Fam20A-deficient ameloblasts were non-polarized and disorganized and were detached from the enamel matrix. The enamel abnormality in cKO mice was consistent with the diagnosis of amelogenesis imperfecta. The levels of enamelin and matrix metalloproteinase 20 were lower in the ameloblasts and enamel of cKO mice than the normal mice. The cKO mice had remarkable delays in the eruption of molars and hyperplasia of the gingival epithelium. The findings emphasize the essential roles of FAM20A in the development of dental and oral tissues.
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49
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Hytönen MK, Arumilli M, Lappalainen AK, Owczarek-Lipska M, Jagannathan V, Hundi S, Salmela E, Venta P, Sarkiala E, Jokinen T, Gorgas D, Kere J, Nieminen P, Drögemüller C, Lohi H. Molecular Characterization of Three Canine Models of Human Rare Bone Diseases: Caffey, van den Ende-Gupta, and Raine Syndromes. PLoS Genet 2016; 12:e1006037. [PMID: 27187611 PMCID: PMC4871343 DOI: 10.1371/journal.pgen.1006037] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 04/18/2016] [Indexed: 12/03/2022] Open
Abstract
One to two percent of all children are born with a developmental disorder requiring pediatric hospital admissions. For many such syndromes, the molecular pathogenesis remains poorly characterized. Parallel developmental disorders in other species could provide complementary models for human rare diseases by uncovering new candidate genes, improving the understanding of the molecular mechanisms and opening possibilities for therapeutic trials. We performed various experiments, e.g. combined genome-wide association and next generation sequencing, to investigate the clinico-pathological features and genetic causes of three developmental syndromes in dogs, including craniomandibular osteopathy (CMO), a previously undescribed skeletal syndrome, and dental hypomineralization, for which we identified pathogenic variants in the canine SLC37A2 (truncating splicing enhancer variant), SCARF2 (truncating 2-bp deletion) and FAM20C (missense variant) genes, respectively. CMO is a clinical equivalent to an infantile cortical hyperostosis (Caffey disease), for which SLC37A2 is a new candidate gene. SLC37A2 is a poorly characterized member of a glucose-phosphate transporter family without previous disease associations. It is expressed in many tissues, including cells of the macrophage lineage, e.g. osteoclasts, and suggests a disease mechanism, in which an impaired glucose homeostasis in osteoclasts compromises their function in the developing bone, leading to hyperostosis. Mutations in SCARF2 and FAM20C have been associated with the human van den Ende-Gupta and Raine syndromes that include numerous features similar to the affected dogs. Given the growing interest in the molecular characterization and treatment of human rare diseases, our study presents three novel physiologically relevant models for further research and therapy approaches, while providing the molecular identity for the canine conditions. Rare developmental disorders make a major contribution to pediatric hospital admissions and mortality. There is a growing interest in the development of therapeutics for these conditions, but that requires understanding of the genetic cause and pathology. Research can be facilitated by physiologically relevant models, such as dogs with corresponding disorders. We have characterized the clinical features and genetic causes of three developmental syndromes in dogs, including craniomandibular osteopathy (CMO), a previously undescribed skeletal syndrome, and dental hypomineralization, for which we identified mutations in the canine SLC37A2, SCARF2 and FAM20C genes, respectively. CMO is a clinical equivalent to an infantile cortical hyperostosis (Caffey disease) for which SLC37A2 is a new candidate gene. SLC37A2 is a glucose-phosphate transporter in osteoclasts, and its defect suggests an impaired glucose homeostasis in developing bone, leading to hyperostosis. Mutations in the SCARF2 and FAM20C genes have been associated with the human van den Ende-Gupta and Raine syndromes. Our study provides molecular identity for the canine conditions and presents three novel physiologically relevant models of human rare diseases.
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Affiliation(s)
- Marjo K. Hytönen
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Meharji Arumilli
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Anu K. Lappalainen
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | | | - Vidhya Jagannathan
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Sruthi Hundi
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Elina Salmela
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Patrick Venta
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| | - Eva Sarkiala
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Tarja Jokinen
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Daniela Gorgas
- Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Juha Kere
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Pekka Nieminen
- Department of Oral and Maxillofacial Diseases, University of Helsinki, Helsinki, Finland
| | - Cord Drögemüller
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Hannes Lohi
- Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
- The Folkhälsan Institute of Genetics, Helsinki, Finland
- * E-mail:
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50
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Kinoshita S, Kawai M. The FGF23/KLOTHO Regulatory Network and Its Roles in Human Disorders. VITAMINS AND HORMONES 2016; 101:151-74. [PMID: 27125741 DOI: 10.1016/bs.vh.2016.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The functions of Klotho (KL) are multifaceted and include the regulation of aging and mineral metabolism. It was originally identified as the gene responsible for premature aging-like symptoms in mice and was subsequently shown to function as a coreceptor in the fibroblast growth factor (FGF) 23 signaling pathway. The discovery of KL as a partner for FGF23 led to significant advances in understanding of the molecular mechanisms underlying phosphate and vitamin D metabolism, and simultaneously clarified the pathogenic roles of the FGF23 signaling pathway in human diseases. These novel insights led to the development of new strategies to combat disorders associated with the dysregulated metabolism of phosphate and vitamin D, and clinical trials on the blockade of FGF23 signaling in X-linked hypophosphatemic rickets are ongoing. Molecular and functional insights on KL and FGF23 have been discussed in this review and were extended to how dysregulation of the FGF23/KL axis causes human disorders associated with abnormal mineral metabolism.
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Affiliation(s)
- S Kinoshita
- Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
| | - M Kawai
- Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan.
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