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Kamenický P, Briot K, Munns CF, Linglart A. X-linked hypophosphataemia. Lancet 2024; 404:887-901. [PMID: 39181153 DOI: 10.1016/s0140-6736(24)01305-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 08/27/2024]
Abstract
X-linked hypophosphataemia is a genetic disease caused by defects in the phosphate regulating endopeptidase homolog X-linked (PHEX) gene and is characterised by X-linked dominant inheritance. The main consequence of PHEX deficiency is increased production of the phosphaturic hormone fibroblast growth factor 23 (FGF23) in osteoblasts and osteocytes. Chronic exposure to circulating FGF23 is responsible for renal phosphate wasting and decreased synthesis of calcitriol, which decreases intestinal phosphate absorption. These mechanisms result in lifelong hypophosphataemia, impaired growth plate and bone matrix mineralisation, and diverse manifestations in affected children and adults, including some debilitating morbidities and possibly increased mortality. Important progress has been made in disease knowledge and management over the past decade; in particular, targeting FGF23 is a therapeutic approach that has substantially improved outcomes. However, patients affected by this complex disease need lifelong care and innovative treatment strategies, such as gene repair of PHEX, are necessary to further limit the disease burden.
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Affiliation(s)
- Peter Kamenický
- Université Paris-Saclay, Inserm, Physiologie et Physiopathologie Endocriniennes, Le Kremlin-Bicêtre, France; Centre de Référence des Maladies du Métabolisme du Calcium et du Phosphate, Service d'Endocrinologie et des Maladies de la Reproduction, Hôpital Bicêtre, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France.
| | - Karine Briot
- Centre de Référence des Maladies du Métabolisme du Calcium et du Phosphate, Service de Rhumatologie, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Craig F Munns
- Department of Endocrinology and Diabetes, Queensland Children's Hospital and Child Health Research Centre and Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Agnès Linglart
- Université Paris-Saclay, Inserm, Physiologie et Physiopathologie Endocriniennes, Le Kremlin-Bicêtre, France; Service d'Endocrinologie et du Diabète de l'Enfant, Hôpital Bicêtre, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France
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2
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Chen X, Cai C, Lun S, Ye Q, Pan W, Chen Y, Wu Y, Feng T, Su F, Ma C, Luo J, Liu M, Ma G. The contribution of a novel PHEX gene mutation to X-linked hypophosphatemic rickets: a case report and an analysis of the gene mutation dosage effect in a rat model. Front Endocrinol (Lausanne) 2023; 14:1251718. [PMID: 38116308 PMCID: PMC10728720 DOI: 10.3389/fendo.2023.1251718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 11/15/2023] [Indexed: 12/21/2023] Open
Abstract
A Chinese family was identified to have two patients with rickets, an adult female and a male child (proband), both exhibiting signs related to X-linked hypophosphatemic rickets (XLH). Gene sequencing analysis revealed a deletion of adenine at position 1985 (c.1985delA) in the PHEX-encoding gene. To investigate the relationship between this mutation and the pathogenicity of XLH, as well as analyze the effects of different dosages of PHEX gene mutations on clinical phenotypes, we developed a rat model carrying the PHEX deletion mutation. The CRISPR/Cas9 gene editing technology was employed to construct the rat model with the PHEX gene mutation (c.1985delA). Through reproductive procedures, five genotypes of rats were obtained: female wild type (X/X), female heterozygous (-/X), female homozygous wild type (-/-), male wild type (X/Y), and male hemizygous (-/Y). The rats with different genotypes underwent analysis of growth, serum biochemical parameters, and bone microstructure. The results demonstrated the successful generation of a stable rat model inheriting the PHEX gene mutation. Compared to the wild-type rats, the mutant rats displayed delayed growth, shorter femurs, and significantly reduced bone mass. Among the female rats, the homozygous individuals exhibited the smallest body size, decreased bone mass, shortest femur length, and severe deformities. Moreover, the mutant rats showed significantly lower blood phosphorus concentration, elevated levels of FGF23 and alkaline phosphatase, and increased expression of phosphorus regulators. In conclusion, the XLH rat model with the PHEX gene mutation dosage demonstrated its impact on growth and development, serum biochemical parameters, and femoral morphology.
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Affiliation(s)
- Xiaoming Chen
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
- Faculty of Chinese Medicine, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau, China
| | - Cijing Cai
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
- Maternal and Children’s Health Research Institute, Shunde Women and Children’s Hospital, Guangdong Medical University, Foshan, China
| | - Shaocong Lun
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Qiuli Ye
- Department of Traditional Chinese Medicine, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Weiyuan Pan
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Yushi Chen
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Yuexuan Wu
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Taoshan Feng
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Faming Su
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Choudi Ma
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Jiaxin Luo
- Department of Endocrinology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Meilian Liu
- Department of Pulmonary Oncology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Guoda Ma
- Maternal and Children’s Health Research Institute, Shunde Women and Children’s Hospital, Guangdong Medical University, Foshan, China
- Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China
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Grimbly C, Graf D, Ward LM, Alexander RT. X-linked hypophosphatemia, fibroblast growth factor 23 signaling, and craniosynostosis. Exp Biol Med (Maywood) 2023; 248:2175-2182. [PMID: 38230523 PMCID: PMC10800125 DOI: 10.1177/15353702231222023] [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] [Indexed: 01/18/2024] Open
Abstract
This review summarizes the current knowledge of fibroblast growth factor 23 signaling in bone and its role in the disease pathology of X-linked hypophosphatemia. Craniosynostosis is an under-recognized complication of X-linked hypophosphatemia. The clinical implications and potential cellular mechanisms invoked by increased fibroblast growth factor 23 signaling causing craniosynostosis are reviewed. Knowledge gaps are identified and provide direction for future clinical and basic science studies.
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Affiliation(s)
- Chelsey Grimbly
- Department of Pediatrics, Edmonton Clinic Health Academy, University of Alberta, Edmonton, AB T6G 2R7, Canada
- Women & Children’s Health Research Institute, University of Alberta, Edmonton, AB T6G 2R7, Canada
| | - Daniel Graf
- Women & Children’s Health Research Institute, University of Alberta, Edmonton, AB T6G 2R7, Canada
- Department of Dentistry and Dental Hygiene, University of Alberta, Edmonton, AB T6G 2R7, Canada
| | - Leanne M Ward
- Division of Endocrinology and Metabolism, Department of Pediatrics Faculty of Medicine, Children’s Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON K1H 8L1, Canada
| | - R Todd Alexander
- Department of Pediatrics, Edmonton Clinic Health Academy, University of Alberta, Edmonton, AB T6G 2R7, Canada
- Women & Children’s Health Research Institute, University of Alberta, Edmonton, AB T6G 2R7, Canada
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Kritmetapak K, Kumar R. Phosphatonins: From Discovery to Therapeutics. Endocr Pract 2023; 29:69-79. [PMID: 36210014 DOI: 10.1016/j.eprac.2022.09.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Phosphate is crucial for cell signaling, energy metabolism, nucleotide synthesis, and bone mineralization. The gut-bone-parathyroid-kidney axis is influenced by parathyroid hormone, 1,25-dihydroxyvitamin D, and phosphatonins, especially fibroblast growth factor 23 (FGF23). These hormones facilitate maintenance of phosphate homeostasis. This review summarizes current knowledge regarding the phosphate homeostasis, phosphatonin pathophysiology, and clinical implications of FGF23-related hypophosphatemic disorders, with specific focus on burosumab treatment. METHOD A focused literature search of PubMed was conducted. RESULTS Phosphatonins including FGF23, secreted frizzled-related protein 4, matrix extracellular phosphoglycoprotein, and fibroblast growth factor 7 play a pathogenic role in several hypophosphatemic disorders. Excess FGF23 inhibits sodium-dependent phosphate cotransporters (NaPi-2a and NaPi-2c), resulting in hyperphosphaturia and hypophosphatemia. Additionally, FGF23 suppresses 1,25-dihydroxyvitamin D synthesis in the proximal renal tubule, and thus, it indirectly inhibits intestinal phosphate absorption. Disorders of FGF23-related hypophosphatemia include X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets, fibrous dysplasia/McCune-Albright syndrome, and tumor-induced osteomalacia (TIO). Complications of conventional therapy with oral phosphate and vitamin D analogs comprise gastrointestinal distress, hypercalcemia, nephrocalcinosis, and secondary/tertiary hyperparathyroidism. In both children and adults with XLH and TIO, the anti-FGF23 antibody burosumab exhibits a favorable safety profile and is associated with healing of rickets in affected children and improvement of osteomalacia in both children and adults. CONCLUSION The treatment paradigm for XLH and TIO is changing based on data from recent clinical trials. Research suggest that burosumab is effective and safe for pediatric and adult patients with XLH or TIO.
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Affiliation(s)
| | - Rajiv Kumar
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota.
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Rowe PS, McCarthy EM, Yu AL, Stubbs JR. Correction of Vascular Calcification and Hyperphosphatemia in CKD Rats Treated with ASARM Peptide. KIDNEY360 2022; 3:1683-1698. [PMID: 36514737 PMCID: PMC9717652 DOI: 10.34067/kid.0002782022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 08/25/2022] [Indexed: 01/11/2023]
Abstract
Background Abnormalities in calcium, phosphorus, PTH, vitamin D metabolism, bone, and vascular calcification occur in chronic kidney disease mineral bone disorder (CKD-MBD). Calciphylaxis, involving painful, ulcerative skin lesions, is also a major problem associated with CKD-MBD. There are no quality medical interventions to address these clinical issues. Bone ASARM peptides are strong inhibitors of mineralization and induce hypophosphatemia by inhibiting phosphate uptake from the gut. We hypothesize treatment of CKD-MBD rats with ASARM peptides will reverse hyperphosphatemia, reduce soft-tissue calcification, and prevent calciphylaxis. Methods To test our hypothesis, we assessed the effects of synthetic ASARM peptide in rats that had undergone a subtotal 5/6th nephrectomy (56NEPHREX), a rodent model of CKD-MBD. All rats were fed a high phosphate diet (2% Pi) to worsen mineral metabolism defects. Changes in serum potassium, phosphate, BUN, creatinine, PTH, FGF23, and calcium were assessed in response to 28 days of ASARM peptide infusion. Also, changes in bone quality, soft-tissue calcification, and expression of gut Npt2b (Slc34a2) were studied following ASARM peptide treatment. Results Rats that had undergone 56NEPHREX treated with ASARM peptide showed major improvements in hyperphosphatemia, blood urea nitrogen (BUN), and bone quality compared with vehicle controls. Also, ASARM-infused 56NEPHREX rats displayed improved renal, brain, and cardiovascular calcification. Notably, ASARM peptide infusion prevented the genesis of subdermal medial blood vessel calcification and calciphylaxis-like lesions in 56NEPHREX rats compared with vehicle controls. Conclusions ASARM peptide infusion corrects hyperphosphatemia and improves vascular calcification, renal calcification, brain calcification, bone quality, renal function, and skin mineralization abnormalities in 56NEPHREX rats. These findings confirm our hypothesis and support the utility of ASARM peptide treatment in patients with CKD-MBD.
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Affiliation(s)
- Peter S. Rowe
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Ellen M. McCarthy
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Alan L. Yu
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Jason R. Stubbs
- The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
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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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Tripathi A, John AA, Kumar D, Kaushal SK, Singh DP, Husain N, Sarkar J, Singh D. MiR-539-3p impairs osteogenesis by suppressing Wnt interaction with LRP-6 co-receptor and subsequent inhibition of Akap-3 signaling pathway. Front Endocrinol (Lausanne) 2022; 13:977347. [PMID: 36267566 PMCID: PMC9577939 DOI: 10.3389/fendo.2022.977347] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 06/24/2022] [Accepted: 09/07/2022] [Indexed: 11/21/2022] Open
Abstract
X-linked hypophosphatemia (XLH), an inheritable form of rickets is caused due to mutation in Phex gene. Several factors are linked to the disease's aetiology, including non-coding RNA molecules (miRNAs), which are key post-transcriptional regulators of gene expression and play a significant role in osteoblast functions. MicroRNAs sequence analysis showed differentially regulated miRNAs in phex silenced osteoblast cells. In this article, we report miR-539-3p, an unidentified novel miRNA, in the functional regulation of osteoblast. MiR-539-3p overexpression impaired osteoblast differentiation. Target prediction algorithm and experimental confirmation by luciferase 3' UTR reporter assay identified LRP-6 as a direct target of miR-539-3p. Over expression of miR-539-3p in osteoblasts down regulated Wnt/beta catenin signaling components and deteriorated trabecular microarchitecture leading to decreased bone formation in ovariectomized (Ovx) mice. Additionally, biochemical bone resorption markers like CTx and Trap-5b were elevated in serum samples of mimic treated group, while, reverse effect was observed in anti-miR treated animals along with increased bone formation marker P1NP. Moreover, transcriptome analysis with miR-539-3p identified a novel uncharacterized Akap-3 gene in osteoblast cells, knock down of which resulted in downregulation of osteoblast differentiation markers at both transcriptional and translational level. Overall, our study for the first time reported the role of miR-539-3p in osteoblast functions and its downstream Akap-3 signalling in regulation of osteoblastogenesis.
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Affiliation(s)
- Alok Tripathi
- Division of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad, Uttar Pradesh, India
| | - Aijaz A. John
- Division of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
| | - Deepak Kumar
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad, Uttar Pradesh, India
- Division of Cancer Biology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
| | - Saurabh Kumar Kaushal
- Division of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad, Uttar Pradesh, India
| | - Devendra Pratap Singh
- Division of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad, Uttar Pradesh, India
| | - Nazim Husain
- Division of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
| | - Jayanta Sarkar
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad, Uttar Pradesh, India
- Division of Cancer Biology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
| | - Divya Singh
- Division of Endocrinology, Council of Scientific and Industrial Research-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research (AcSIR) Ghaziabad, Uttar Pradesh, India
- *Correspondence: Divya Singh,
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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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Sisk LJ, Patel RK, Stevens KK. A descriptive analysis of non-human leukocyte antigens present in renal transplant donor-recipient pairs. Transpl Immunol 2021; 69:101474. [PMID: 34582968 DOI: 10.1016/j.trim.2021.101474] [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: 07/31/2021] [Revised: 09/22/2021] [Accepted: 09/22/2021] [Indexed: 11/16/2022]
Abstract
INTRODUCTION End stage renal disease (ESRD) is the irreversible deterioration of renal function requiring renal replacement therapy by dialysis or transplant. Human leucocyte antigens (HLA) have been well examined however research still is required into the non-HLA antibodies. Antibody mediated rejection (AMR) can be seen in the absence of HLA antibodies on biopsies of patients who have received identical transplants; anti-endothelial cell antibodies may explain this. Investigation into endothelial cell antigens on donor and recipient endothelium may elucidate and stratify the degree of risk of any given transplant and may guide towards the best matched donor. METHODS Protein array analysis was carried out on 8 patient pairs using nitro-cellulose membranes and biotinylated detection antibodies. The fluorescence emitted was captured by X-Ray film and results were recorded with ImageJ software. A fold increase of more than 2 was considered to be positive. RESULTS 11 proteins identified had a fold increase of increase ≥2 and were present in ≥2 patient pairs which may point to potential clinical utility. Nectin2/CD112 may be measured in order analyse graft survival time in transplant recipients. Prognosticating renal failure has clinical importance and potential markers that have been identified to aid which include MEPE, CRELD2, and TIMP-4. Novel pharmacological therapies for specific biomarkers identified in this study include JAM-A, E-Selectin, CD147, Galectin-3, JAM-C, PAR-1, and TNFR2. CONCLUSION Protein analysis showed differences in expression of antigens between patients with and without Chronic Kidney Disease (CKD). This information could be used at the matching stage of renal transplantation and also in the treatment of rejection episodes. The results highlight biomarkers that potentially prognosticate and pharmacological therapies that may ameliorate kidney disease and rejection in ESRD and transplant recipients.
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Affiliation(s)
- Louis J Sisk
- University of Glasgow, United Kingdom; British Heart Foundation Cardiovascular Research Centre, University of Glasgow, United Kingdom.
| | - Rajan K Patel
- University of Glasgow, United Kingdom; British Heart Foundation Cardiovascular Research Centre, University of Glasgow, United Kingdom
| | - Kathryn K Stevens
- University of Glasgow, United Kingdom; British Heart Foundation Cardiovascular Research Centre, University of Glasgow, United Kingdom
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Minamizaki T, Sakurai K, Hayashi I, Toshishige M, Yoshioka H, Kozai K, Yoshiko Y. Active sites of human MEPE-ASARM regulating bone matrix mineralization. Mol Cell Endocrinol 2020; 517:110931. [PMID: 32712387 DOI: 10.1016/j.mce.2020.110931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 06/17/2020] [Accepted: 06/24/2020] [Indexed: 11/25/2022]
Abstract
The proteolytic fragment ASARM (acidic serine- and aspartate-rich motif) of MEPE (matrix extracellular phosphoglycoprotein) (MEPE-ASARM) may act as an endogenous anti-mineralization factor involved in X-linked hypophosphatemic rickets/osteomalacia (XLH). We synthesized MEPE-ASARM peptides and relevant peptide fragments with or without phosphorylated Ser residues (pSer) to determine the active site(s) of MEPE-ASARM in a rat calvaria cell culture model. None of the synthetic peptides elicited changes in cell death, proliferation or differentiation, but the peptide (pASARM) with three pSer residues inhibited mineralization without causing changes in gene expression of osteoblast markers tested. The anti-mineralization effect was maintained in peptides in which any one of three pSer residues was deleted. Polyclonal antibodies recognizing pASARM but not ASARM abolished the pASARM effect. Deletion of six N-terminal residues but leaving the recognition sites for PHEX (phosphate regulating endopeptidase homolog, X-linked), a membrane endopeptidase responsible for XLH, intact and two C-terminal amino acid residues did not alter the anti-mineralization activity of pASARM. Our results strengthen understanding of the active sites of MEPE-pASARM and allowed us to identify a shorter more stable sequence with fewer pSer residues still exhibiting hypomineralization activity, reducing peptide synthesis cost and increasing reliability for exploring biological and potential therapeutic effects.
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Affiliation(s)
- Tomoko Minamizaki
- Department of Calcified Tissue Biology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Kaoru Sakurai
- Department of Calcified Tissue Biology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan; Department of Pediatric Dentistry, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Ikue Hayashi
- Research Facility, Hiroshima University School of Dentistry, Hiroshima, Japan
| | - Masaaki Toshishige
- Department of Calcified Tissue Biology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Hirotaka Yoshioka
- Department of Calcified Tissue Biology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Katsuyuki Kozai
- Department of Pediatric Dentistry, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Yuji Yoshiko
- Department of Calcified Tissue Biology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan.
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11
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Reznikov N, Hoac B, Buss DJ, Addison WN, Barros NMT, McKee MD. Biological stenciling of mineralization in the skeleton: Local enzymatic removal of inhibitors in the extracellular matrix. Bone 2020; 138:115447. [PMID: 32454257 DOI: 10.1016/j.bone.2020.115447] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/14/2020] [Accepted: 05/20/2020] [Indexed: 12/12/2022]
Abstract
Biomineralization is remarkably diverse and provides myriad functions across many organismal systems. Biomineralization processes typically produce hardened, hierarchically organized structures usually having nanostructured mineral assemblies that are formed through inorganic-organic (usually protein) interactions. Calcium‑carbonate biomineral predominates in structures of small invertebrate organisms abundant in marine environments, particularly in shells (remarkably it is also found in the inner ear otoconia of vertebrates), whereas calcium-phosphate biomineral predominates in the skeletons and dentitions of both marine and terrestrial vertebrates, including humans. Reconciliation of the interplay between organic moieties and inorganic crystals in bones and teeth is a cornerstone of biomineralization research. Key molecular determinants of skeletal and dental mineralization have been identified in health and disease, and in pathologic ectopic calcification, ranging from small molecules such as pyrophosphate, to small membrane-bounded matrix vesicles shed from cells, and to noncollagenous extracellular matrix proteins such as osteopontin and their derived bioactive peptides. Beyond partly knowing the regulatory role of the direct actions of inhibitors on vertebrate mineralization, more recently the importance of their enzymatic removal from the extracellular matrix has become increasingly understood. Great progress has been made in deciphering the relationship between mineralization inhibitors and the enzymes that degrade them, and how adverse changes in this physiologic pathway (such as gene mutations causing disease) result in mineralization defects. Two examples of this are rare skeletal diseases having osteomalacia/odontomalacia (soft bones and teeth) - namely hypophosphatasia (HPP) and X-linked hypophosphatemia (XLH) - where inactivating mutations occur in the gene for the enzymes tissue-nonspecific alkaline phosphatase (TNAP, TNSALP, ALPL) and phosphate-regulating endopeptidase homolog X-linked (PHEX), respectively. Here, we review and provide a concept for how existing and new information now comes together to describe the dual nature of regulation of mineralization - through systemic mineral ion homeostasis involving circulating factors, coupled with molecular determinants operating at the local level in the extracellular matrix. For the local mineralization events in the extracellular matrix, we present a focused concept in skeletal mineralization biology called the Stenciling Principle - a principle (building upon seminal work by Neuman and Fleisch) describing how the action of enzymes to remove tissue-resident inhibitors defines with precision the location and progression of mineralization.
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Affiliation(s)
- N Reznikov
- Object Research Systems Inc., 760 St. Paul West, Montreal, Quebec H3C 1M4, Canada.
| | - B Hoac
- Faculty of Dentistry, McGill University, 3640 University St., Montreal, Quebec H3A 0C7, Canada
| | - D J Buss
- Department of Anatomy and Cell Biology, McGill University, 3640 University St., Montreal, Quebec H3A 0C7, Canada
| | - W N Addison
- Department of Molecular Signaling and Biochemistry, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka, Japan
| | - N M T Barros
- Departamento de Biofísica, São Paulo, Departamento de Ciências Biológicas, Universidade Federal de São Paulo, Diadema, Brazil
| | - M D McKee
- Faculty of Dentistry, McGill University, 3640 University St., Montreal, Quebec H3A 0C7, Canada; Department of Anatomy and Cell Biology, McGill University, 3640 University St., Montreal, Quebec H3A 0C7, Canada.
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12
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Christensen B, Schytte GN, Scavenius C, Enghild JJ, McKee MD, Sørensen ES. FAM20C-Mediated Phosphorylation of MEPE and Its Acidic Serine- and Aspartate-Rich Motif. JBMR Plus 2020; 4:e10378. [PMID: 32803110 PMCID: PMC7422707 DOI: 10.1002/jbm4.10378] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/11/2020] [Accepted: 05/17/2020] [Indexed: 01/10/2023] Open
Abstract
Matrix extracellular phosphoglycoprotein (MEPE) is expressed in bone and teeth where it has multiple functions. The C-terminus of MEPE contains a mineral-binding, acidic serine- and aspartate-rich motif (ASARM) that is also present in other noncollagenous proteins of mineralized tissues. MEPE-derived ASARM peptides function in phosphate homeostasis and direct inhibition of bone mineralization in a phosphorylation-dependent manner. MEPE is phosphorylated by family with sequence similarity 20, member C (FAM20C), which is the main kinase phosphorylating secreted phosphoprotein. Although the functional importance of protein phosphorylation status in mineralization processes has now been well-established for secreted bone and tooth proteins (particularly for osteopontin), the phosphorylation pattern of MEPE has not been previously determined. Here we provide evidence for a very high phosphorylation level of this protein, reporting on the localization of 31 phosphoresidues in human MEPE after coexpression with FAM20C in HEK293T cells. This includes the finding that all serine residues located in the canonical target sequence of FAM20C (Ser-x-Glu) were phosphorylated, thus establishing the major target sites for this kinase. We also show that MEPE has numerous other phosphorylation sites, these not being positioned in the canonical phosphorylation sequence. Of note, and underscoring a possible important function in mineralization biology, all nine serine residues in the ASARM were phosphorylated, even though only two of these were positioned in the Ser-x-Glu sequence. The presence of many phosphorylated amino acids in MEPE, and particularly their high density in the ASARM motif, provides an important basis for the understanding of structural and functional interdependencies in mineralization and phosphate homeostasis. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Brian Christensen
- Department of Molecular Biology and Genetics Aarhus University Aarhus Denmark
| | - Gitte N Schytte
- Department of Molecular Biology and Genetics Aarhus University Aarhus Denmark
| | - Carsten Scavenius
- Department of Molecular Biology and Genetics Aarhus University Aarhus Denmark.,Interdisciplinary Nanoscience Center Aarhus University Aarhus Denmark
| | - Jan J Enghild
- Department of Molecular Biology and Genetics Aarhus University Aarhus Denmark.,Interdisciplinary Nanoscience Center Aarhus University Aarhus Denmark
| | - Marc D McKee
- Faculty of Dentistry and Department of Anatomy and Cell Biology McGill University Montreal Quebec Canada
| | - Esben S Sørensen
- Department of Molecular Biology and Genetics Aarhus University Aarhus Denmark.,Interdisciplinary Nanoscience Center Aarhus University Aarhus Denmark
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13
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Abstract
Phosphate is an essential nutrient for life and is a critical component of bone formation, a major signaling molecule, and structural component of cell walls. Phosphate is also a component of high-energy compounds (i.e., AMP, ADP, and ATP) and essential for nucleic acid helical structure (i.e., RNA and DNA). Phosphate plays a central role in the process of mineralization, normal serum levels being associated with appropriate bone mineralization, while high and low serum levels are associated with soft tissue calcification. The serum concentration of phosphate and the total body content of phosphate are highly regulated, a process that is accomplished by the coordinated effort of two families of sodium-dependent transporter proteins. The three isoforms of the SLC34 family (SLC34A1-A3) show very restricted tissue expression and regulate intestinal absorption and renal excretion of phosphate. SLC34A2 also regulates the phosphate concentration in multiple lumen fluids including milk, saliva, pancreatic fluid, and surfactant. Both isoforms of the SLC20 family exhibit ubiquitous expression (with some variation as to which one or both are expressed), are regulated by ambient phosphate, and likely serve the phosphate needs of the individual cell. These proteins exhibit similarities to phosphate transporters in nonmammalian organisms. The proteins are nonredundant as mutations in each yield unique clinical presentations. Further research is essential to understand the function, regulation, and coordination of the various phosphate transporters, both the ones described in this review and the phosphate transporters involved in intracellular transport.
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Affiliation(s)
- Nati Hernando
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Kenneth Gagnon
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Eleanor Lederer
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
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14
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Abstract
Over the past 25 years, successive cloning of SLC34A1, SLC34A2 and SLC34A3, which encode the sodium-dependent inorganic phosphate (Pi) cotransport proteins 2a-2c, has facilitated the identification of molecular mechanisms that underlie the regulation of renal and intestinal Pi transport. Pi and various hormones, including parathyroid hormone and phosphatonins, such as fibroblast growth factor 23, regulate the activity of these Pi transporters through transcriptional, translational and post-translational mechanisms involving interactions with PDZ domain-containing proteins, lipid microdomains and acute trafficking of the transporters via endocytosis and exocytosis. In humans and rodents, mutations in any of the three transporters lead to dysregulation of epithelial Pi transport with effects on serum Pi levels and can cause cardiovascular and musculoskeletal damage, illustrating the importance of these transporters in the maintenance of local and systemic Pi homeostasis. Functional and structural studies have provided insights into the mechanism by which these proteins transport Pi, whereas in vivo and ex vivo cell culture studies have identified several small molecules that can modify their transport function. These small molecules represent potential new drugs to help maintain Pi homeostasis in patients with chronic kidney disease - a condition that is associated with hyperphosphataemia and severe cardiovascular and skeletal consequences.
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15
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Hansen S, Shanbhogue VV, Jørgensen NR, Beck-Nielsen SS. Elevated Bone Remodeling Markers of CTX and P1NP in Addition to Sclerostin in Patients with X-linked Hypophosphatemia: A Cross-Sectional Controlled Study. Calcif Tissue Int 2019; 104:591-598. [PMID: 30710161 DOI: 10.1007/s00223-019-00526-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 01/16/2019] [Indexed: 02/06/2023]
Abstract
Aspects of bone remodeling have only been scarcely studied in X-linked hypophosphatemia (XLH). In this cross-sectional controlled study, we assessed biochemical indices of bone remodeling and sclerostin in 27 adult patients (median age 47 [range 24-79] years, 19 women, 8 men) with XLH matched with 81 healthy control subjects (1:3) with respect to age-, sex-, and menopausal status. Markers of bone resorption (carboxyterminal cross-linked telopeptide of type 1 collagen, CTX) and formation (N-terminal propeptide of type 1 procollagen, P1NP) were higher in XLH patients compared to controls (median [IQR] 810 [500-1340] vs 485 [265-715] ng/l and 90 [57-136] vs 49 [39-65] ug/l, respectively, both p < 0.001) as well as sclerostin (0.81 [0.60-1.18] vs 0.54 [0.45-0.69] ng/ml, p < 0.001). Similar differences were found when comparing currently treated (with phosphate and alfacalcidol) (n = 11) and untreated (n = 16) XLH patients with their respective controls. We found no significant associations with treatment status and indices of bone remodeling or sclerostin although sclerostin tended to be increased in untreated versus treated (p = 0.06). In contrast to previous histomorphometric studies suggesting a low remodeling activity in XLH, these biochemical indices suggest high osteoblast and osteoclast activity. Further studies are needed to ascertain if the higher sclerostin level in XLH is related to osteocyte dysfunction or represents a secondary phenomenon.
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Affiliation(s)
- Stinus Hansen
- Department of Endocrinology, Hospital South West Jutland, Esbjerg, Denmark.
| | | | - Niklas Rye Jørgensen
- Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark
- OPEN, Odense Patient Data Explorative Network, Odense University Hospital/Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Signe Sparre Beck-Nielsen
- Department of Pediatrics, Kolding Hospital at Lillebaelt Hospital, Kolding, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
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16
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Chien YC, Mansouri A, Jiang W, Khan SR, Gray JJ, McKee MD. Modulation of calcium oxalate dihydrate growth by phosphorylated osteopontin peptides. J Struct Biol 2018; 204:131-144. [PMID: 30016645 DOI: 10.1016/j.jsb.2018.07.010] [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: 03/28/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 01/28/2023]
Abstract
Osteopontin (OPN) is a significant component of kidney stone matrix and a key modulator of stone formation. Here, we investigated the effects of different phosphorylated states of a synthesized peptide of OPN (the ASARM peptide; acidic, serine- and aspartate-rich motif) on calcium oxalate dihydrate (COD) crystals, a major mineral phase of kidney stones. In vitro, phosphorylated OPN-ASARM peptides strongly inhibited COD crystal growth in solution as compared to the nonphosphorylated state, with increasing inhibitory potency correlating with the degree of peptide phosphorylation. Scanning electron microscopy revealed that the inhibition from the phosphopeptides resulted in distinctive, rosette-like crystal aggregates called spherulites. The OPN-ASARM peptides preferentially bound and specifically inhibited the {1 1 0} crystallographic faces of COD, as identified by combining atomic force microscopy and computational simulation approaches. These {1 1 0} surfaces of COD have high lattice calcium occupancy (exposure), providing preferential binding sites for the highly acidic peptides; binding and inhibition by OPN-ASARM peptides at the {1 1 0} faces led to crystal aggregation and intergrowth. The crystal spherulite formations obtained in vitro when using the most phosphorylated form of OPN-ASARM peptide at a high concentration, resembled crystal morphologies observed in vivo in a rat model of urolithiasis, in which crystal deposits in the kidney contain abundant OPN as revealed by immunogold labeling. A mechanistic model for spherulite formation is proposed based on the symmetry and crystallographic structure of COD, where the phosphate groups of OPN-ASARM bind to calcium atoms at [1 1 1] step risers on the COD {1 1 0} surface, inducing the periodic emergence of new COD crystals to form spherulites.
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Affiliation(s)
| | - Ahmad Mansouri
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Wenge Jiang
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Saeed R Khan
- Department of Urology, College of Medicine, University of Florida, FL, USA
| | - Jeffrey J Gray
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Marc D McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada.
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17
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Shanbhogue VV, Hansen S, Jørgensen NR, Beck-Nielsen SS. Impact of Conventional Medical Therapy on Bone Mineral Density and Bone Turnover in Adult Patients with X-Linked Hypophosphatemia: A 6-Year Prospective Cohort Study. Calcif Tissue Int 2018; 102:321-328. [PMID: 29143140 DOI: 10.1007/s00223-017-0363-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/09/2017] [Indexed: 12/24/2022]
Abstract
X-linked hypophosphatemia (XLH) is a rare, inheritable disorder manifesting as rickets in children and osteomalacia in adults. While conventional medical treatment with oral phosphate and alfacalcidol is recommended in childhood, it is undecided whether adults should continue therapy. The aim of this 6-year prospective study was to determine the impact of conventional medical treatment on areal bone mineral density (aBMD), bone turnover markers (BTMs) and measures of calcium homeostasis in 27 adult patients with XLH, 11 of whom received medical treatment. Lumbar spine and total hip aBMD, as assessed by DXA, and biochemical measures of calcium, phosphate, PTH, 1,25 dihydroxyvitamin D2+3 (1,25(OH)2D), fibroblast growth factor 23 (FGF23), P1NP and CTX were measured at baseline and at follow-up. The renal tubular reabsorption of PO4 (TmPO4/GFR) was calculated at both time points. Multilevel mixed-effects linear regression models were used for analyses. During the study period, spine and hip aBMD did not change significantly between treated and non-treated XLH patients. There was a trend towards a decrease in calcium, phosphate and TmPO4/GFR in the treatment group (p = 0.057, p = 0.080 and p = 0.063, respectively), whereas PTH, FGF23, 1,25(OH)2D and P1NP did not change significantly in either groups. However, CTX increased significantly in the treated compared to non-treated group (p = 0.044). Continuing conventional medical therapy in adulthood, although associated with increased bone resorption, does not promote or prevent loss of bone mass as evidenced from the stable aBMD of the hip and spine in XLH patients.
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Affiliation(s)
- Vikram Vinod Shanbhogue
- Department of Endocrinology, Odense University Hospital, Odense, Denmark
- Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Stinus Hansen
- Department of Endocrinology, Odense University Hospital, Odense, Denmark
- Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Niklas Rye Jørgensen
- Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark
- OPEN, Odense Patient data Explorative Network, Odense University Hospital/Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Signe Sparre Beck-Nielsen
- Department of Pediatrics, Kolding Hospital at Lillebaelt Hospital, Sygehusvej 24, DK-6000, Kolding, Denmark.
- Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark.
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18
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Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone suppressing phosphate reabsorption and vitamin D hormone synthesis in the kidney. At physiological concentrations of the hormone, the endocrine actions of FGF23 in the kidney are αKlotho-dependent, because high-affinity binding of FGF23 to FGF receptors requires the presence of the co-receptor αKlotho on target cells. It is well established that excessive concentrations of intact FGF23 in the blood lead to phosphate wasting in patients with normal kidney function. Based on the importance of diseases associated with gain of FGF23 function such as phosphate-wasting diseases and chronic kidney disease, a large body of literature has focused on the pathophysiological consequences of FGF23 excess. Less emphasis has been put on the role of FGF23 in normal physiology. Nevertheless, during recent years, lessons we have learned from loss-of-function models have shown that besides the paramount physiological roles of FGF23 in the control of 1α-hydroxylase expression and of apical membrane expression of sodium-phosphate co-transporters in proximal renal tubules, FGF23 also is an important stimulator of calcium and sodium reabsorption in distal renal tubules. In addition, there is an emerging role of FGF23 as an auto-/paracrine regulator of alkaline phosphatase expression and mineralization in bone. In contrast to the renal actions of FGF23, the FGF23-mediated suppression of alkaline phosphatase in bone is αKlotho-independent. Moreover, FGF23 may be a physiological suppressor of differentiation of hematopoietic stem cells into the erythroid lineage in the bone microenvironment. At present, there is little evidence for a physiological role of FGF23 in organs other than kidney and bone. The purpose of this mini-review is to highlight the current knowledge about the complex physiological functions of FGF23.
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19
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Meng X, Zhao Y, Wang J, Gao Z, Geng Q, Liu X. Regulatory roles of miRNA-758 and matrix extracellular phosphoglycoprotein in cervical cancer. Exp Ther Med 2017; 14:2789-2794. [PMID: 28928798 PMCID: PMC5590035 DOI: 10.3892/etm.2017.4887] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 03/03/2017] [Indexed: 01/03/2023] Open
Abstract
The present study aimed to examine the role and underlying mechanism of miRNA-758 (miR-758) expression in cancer tissues, blood and cervical exfoliated cells from patients with cervical cancer. A total of 49 patients with cervical cancer and 26 healthy people for cervical cancer screening were included in the present study. The patients with cervical cancer were treated with resection, and the tumor and adjacent tissues, blood and cervical exfoliated cells were collected. The expression levels of miR-758 and matrix extracellular phosphoglycoprotein (MEPE) mRNA in each sample were detected by reverse transcription-quantitative polymerase chain reaction. In addition, western blot analysis was used to detect the MEPE protein in tumor tissues, while ELISA was applied to detect the MEPE protein expression in the blood and cervical exfoliated cells. Compared with the normal control, MEPE mRNA expression was upregulated in cervical cancer tissues, blood and cervical exfoliated cells. At the protein level, MEPE was also upregulated significantly in patients with cervical cancer. miR-758 expression was decreased significantly in cervical cancer tissues, blood and cervical exfoliated cells (P<0.05), which was opposite to the trend observed for MEPE mRNA expression. Furthermore, MEPE expression was increased in the tumor tissue, blood and cervical exfoliated cells of cervical cancer patients, which was associated to the downregulated miR-758. Therefore, miR-758 may regulate the infiltration and invasion of cervical cancer by targeting MEPE.
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Affiliation(s)
- Xianhua Meng
- Department of Gynaecology and Obstetrics, Laiwu City People's Hospital, Laiwu, Shandong 271199, P.R. China
| | - Yinghui Zhao
- Department of Gynaecology and Obstetrics, Laiwu City People's Hospital, Laiwu, Shandong 271199, P.R. China
| | - Jinyun Wang
- Department of Gynaecology and Obstetrics, Laiwu City People's Hospital, Laiwu, Shandong 271199, P.R. China
| | - Zheng Gao
- Department of Gynaecology and Obstetrics, Laiwu City People's Hospital, Laiwu, Shandong 271199, P.R. China
| | - Qingxia Geng
- Department of Gynaecology and Obstetrics, Laiwu Maternal and Child Care Hospital, Laiwu, Shandong 271100, P.R. China
| | - Xiaoxia Liu
- Department of Gynaecology and Obstetrics, Laiwu City People's Hospital, Laiwu, Shandong 271199, P.R. China
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20
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Boukpessi T, Hoac B, Coyac BR, Leger T, Garcia C, Wicart P, Whyte MP, Glorieux FH, Linglart A, Chaussain C, McKee MD. Osteopontin and the dento-osseous pathobiology of X-linked hypophosphatemia. Bone 2017; 95:151-161. [PMID: 27884786 DOI: 10.1016/j.bone.2016.11.019] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 11/11/2016] [Accepted: 11/19/2016] [Indexed: 01/13/2023]
Abstract
Seven young patients with X-linked hypophosphatemia (XLH, having inactivating PHEX mutations) were discovered to accumulate osteopontin (OPN) at the sites of defective bone mineralization near osteocytes - the so-called hallmark periosteocytic (lacunar) "halos" of XLH. OPN was also localized in the pericanalicular matrix extending beyond the osteocyte lacunae, as well as in the hypomineralized matrix of tooth dentin. OPN, a potent inhibitor of mineralization normally degraded by PHEX, is a member of a family of acidic, phosphorylated, calcium-binding, extracellular matrix proteins known to regulate dental, skeletal, and pathologic mineralization. Associated with the increased amount of OPN (along with inhibitory OPN peptide fragments) in XLH bone matrix, we found an enlarged, hypomineralized, lacuno-canalicular network - a defective pattern of skeletal mineralization that decreases stiffness locally at: i) the cell-matrix interface in the pericellular environment of the mechanosensing osteocyte, and ii) the osteocyte's dendritic network of cell processes extending throughout the bone. Our findings of an excess of inhibitory OPN near osteocytes and their cell processes, and in dentin, spatially correlates with the defective mineralization observed at these sites in the skeleton and teeth of XLH patients. These changes likely contribute to the dento-osseous pathobiology of XLH, and participate in the aberrant bone adaptation and remodeling seen in XLH.
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Affiliation(s)
- Tchilalo Boukpessi
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; EA 2496, Laboratory of Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry University Paris Descartes Sorbonne Paris Cité, Paris, France; AP-HP Department of Odontology, Charles Foix and Bretonneau Hospitals, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France.
| | - Betty Hoac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Benjamin R Coyac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; EA 2496, Laboratory of Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry University Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Thibaut Leger
- Jacques Monod Institute, Proteomic Facility, University Paris Diderot Sorbonne Paris Cité, Paris, France
| | - Camille Garcia
- Jacques Monod Institute, Proteomic Facility, University Paris Diderot Sorbonne Paris Cité, Paris, France
| | - Philippe Wicart
- AP-HP Department of Pediatric Orthopedics, Necker Hospital, School of Medicine University Paris Descartes Sorbonne Paris Cité, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospital for Children, Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO, USA
| | | | - Agnès Linglart
- AP-HP Department of Pediatric Endocrinology, Kremlin Bicêtre Hospital, School of Medicine University Paris Sud, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Catherine Chaussain
- EA 2496, Laboratory of Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry University Paris Descartes Sorbonne Paris Cité, Paris, France; AP-HP Department of Odontology, Charles Foix and Bretonneau Hospitals, Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Marc D McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada.
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21
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Liu ES, Martins JS, Raimann A, Chae BT, Brooks DJ, Jorgetti V, Bouxsein ML, Demay MB. 1,25-Dihydroxyvitamin D Alone Improves Skeletal Growth, Microarchitecture, and Strength in a Murine Model of XLH, Despite Enhanced FGF23 Expression. J Bone Miner Res 2016; 31:929-39. [PMID: 26751835 PMCID: PMC4862933 DOI: 10.1002/jbmr.2783] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/05/2016] [Accepted: 01/07/2016] [Indexed: 01/24/2023]
Abstract
X-linked hypophosphatemia (XLH) is characterized by impaired renal tubular reabsorption of phosphate owing to increased circulating FGF23 levels, resulting in rickets in growing children and impaired bone mineralization. Increased FGF23 decreases renal brush border membrane sodium-dependent phosphate transporter IIa (Npt2a) causing renal phosphate wasting, impairs 1-α hydroxylation of 25-hydroxyvitamin D, and induces the vitamin D 24-hydroxylase, leading to inappropriately low circulating levels of 1,25-dihydroxyvitamin D (1,25D). The goal of therapy is prevention of rickets and improvement of growth in children by phosphate and 1,25D supplementation. However, this therapy is often complicated by hypercalcemia and nephrocalcinosis and does not always prevent hyperparathyroidism. To determine if 1,25D or blocking FGF23 action can improve the skeletal phenotype without phosphate supplementation, mice with XLH (Hyp) were treated with daily 1,25D repletion, FGF23 antibodies (FGF23Ab), or biweekly high-dose 1,25D from d2 to d75 without supplemental phosphate. All treatments maintained normocalcemia, increased serum phosphate, and normalized parathyroid hormone levels. They also prevented the loss of Npt2a, α-Klotho, and pERK1/2 immunoreactivity observed in the kidneys of untreated Hyp mice. Daily treatment with 1,25D decreased urine phosphate losses despite a marked increase in bone FGF23 mRNA and in circulating FGF23 levels. Daily 1,25D was more effective than other treatments in normalizing the growth plate and metaphyseal organization. In addition to being the only therapy that normalized lumbar vertebral height and body weight, daily 1,25D therapy normalized bone geometry and was more effective than FGF23Ab in improving trabecular bone structure. Daily 1,25D and FGF23Ab improved cortical microarchitecture and whole-bone biomechanical properties more so than biweekly 1,25D. Thus, monotherapy with 1,25D improves growth, skeletal microarchitecture, and bone strength in the absence of phosphate supplementation despite enhancing FGF23 expression, demonstrating that 1,25D has direct beneficial effects on the skeleton in XLH, independent of its role in phosphate homeostasis. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Eva S Liu
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA, USA.,Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - Janaina S Martins
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA.,Division of Nephrology, Universidade de São Paulo, São Paulo, Brazil
| | - Adalbert Raimann
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA.,Department of Pediatrics and Adolescent Medicine, Medical University Vienna, Vienna, Austria
| | | | - Daniel J Brooks
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Department of Orthopedics, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Vanda Jorgetti
- Division of Nephrology, Universidade de São Paulo, São Paulo, Brazil
| | - Mary L Bouxsein
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA.,Department of Orthopedics, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
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22
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Murali SK, Andrukhova O, Clinkenbeard EL, White KE, Erben RG. Excessive Osteocytic Fgf23 Secretion Contributes to Pyrophosphate Accumulation and Mineralization Defect in Hyp Mice. PLoS Biol 2016; 14:e1002427. [PMID: 27035636 PMCID: PMC4818020 DOI: 10.1371/journal.pbio.1002427] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 03/08/2016] [Indexed: 11/24/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is the most frequent form of inherited rickets in humans caused by mutations in the phosphate-regulating gene with homologies to endopeptidases on the X-chromosome (PHEX). Hyp mice, a murine homologue of XLH, are characterized by hypophosphatemia, inappropriately low serum vitamin D levels, increased serum fibroblast growth factor-23 (Fgf23), and osteomalacia. Although Fgf23 is known to be responsible for hypophosphatemia and reduced vitamin D hormone levels in Hyp mice, its putative role as an auto-/paracrine osteomalacia-causing factor has not been explored. We recently reported that Fgf23 is a suppressor of tissue nonspecific alkaline phosphatase (Tnap) transcription via FGF receptor-3 (FGFR3) signaling, leading to inhibition of mineralization through accumulation of the TNAP substrate pyrophosphate. Here, we report that the pyrophosphate concentration is increased in Hyp bones, and that Tnap expression is decreased in Hyp-derived osteocyte-like cells but not in Hyp-derived osteoblasts ex vivo and in vitro. In situ mRNA expression profiling in bone cryosections revealed a ~70-fold up-regulation of Fgfr3 mRNA in osteocytes versus osteoblasts of Hyp mice. In addition, we show that blocking of increased Fgf23-FGFR3 signaling with anti-Fgf23 antibodies or an FGFR3 inhibitor partially restored the suppression of Tnap expression, phosphate production, and mineralization, and decreased pyrophosphate concentration in Hyp-derived osteocyte-like cells in vitro. In vivo, bone-specific deletion of Fgf23 in Hyp mice rescued the suppressed TNAP activity in osteocytes of Hyp mice. Moreover, treatment of wild-type osteoblasts or mice with recombinant FGF23 suppressed Tnap mRNA expression and increased pyrophosphate concentrations in the culture medium and in bone, respectively. In conclusion, we found that the cell autonomous increase in Fgf23 secretion in Hyp osteocytes drives the accumulation of pyrophosphate through auto-/paracrine suppression of TNAP. Hence, we have identified a novel mechanism contributing to the mineralization defect in Hyp mice. A novel mechanism involving autocrine and paracrine actions of fibroblast growth factor-23 contributes to the mineralization defect observed in Hyp, a mouse model for X-linked hypophosphatemia. X-linked hypophosphatemia (XLH) is the most frequent form of inherited rickets in humans. A mouse model of XLH, known as Hyp, is characterized by exceptionally low serum phosphate and vitamin D levels, increased serum levels of the hormone fibroblast growth factor-23 (Fgf23), and impaired bone mineralization. Fgf23 is secreted from two classes of bone cells known as osteoblasts and osteocytes. Fgf23 increases urinary phosphate excretion and suppresses vitamin D hormone production in the kidney. Although Fgf23 is known to be responsible for lower blood phosphate and vitamin D hormone levels in Hyp mice, its putative role as a signaling factor causing impaired mineralization has not been explored. We recently reported that Fgf23 is a suppressor of tissue nonspecific alkaline phosphatase (Tnap) gene expression via FGF receptor-3 (FGFR3) signaling in osteoblasts, leading to inhibition of mineralization through accumulation of the TNAP substrate pyrophosphate. Pyrophosphate is a potent inhibitor of mineralization. Using a combination of cell culture and animal models, we report that the increase in osteocyte Fgf23 secretion of Hyp mice leads to FGFR3-mediated suppression of TNAP with subsequent accumulation of pyrophosphate. Hence, we have identified a novel signaling mechanism by which excessive osteocytic secretion of Fgf23 contributes to the mineralization defect in Hyp mice.
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Affiliation(s)
- Sathish K. Murali
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Olena Andrukhova
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Erica L. Clinkenbeard
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Kenneth E. White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Reinhold G. Erben
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
- * E-mail:
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23
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Zelenchuk LV, Hedge AM, Rowe PSN. Age dependent regulation of bone-mass and renal function by the MEPE ASARM-motif. Bone 2015; 79:131-42. [PMID: 26051469 PMCID: PMC4501877 DOI: 10.1016/j.bone.2015.05.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 05/07/2015] [Accepted: 05/22/2015] [Indexed: 11/28/2022]
Abstract
CONTEXT Mice with null mutations in matrix extracellular phosphoglycoprotein (MEPE) have increased bone mass, increased trabecular density and abnormal cancellous bone (MN-mice). These defects worsen with age and MEPE overexpression induces opposite effects. Also, genome wide association studies show that MEPE plays a major role in bone mass. We hypothesized that the conserved C-terminal MEPE ASARM-motif is chiefly responsible for regulating bone mass and trabecular structure. DESIGN To test our theory we overexpressed C-terminal ASARM-peptide in MN-mice using the Col1α1 promoter (MNAt-mice). We then compared the bone and renal phenotypes of the MNAt-mouse with the MN-mouse and the X-linked hypophosphatemic rickets mouse (HYP). The HYP mouse overexpresses ASARM-peptides and is defective for the PHEX gene. RESULTS The MN-mouse developed increased bone mass, bone strength and trabecular abnormalities that worsened markedly with age. Defects in bone formation were chiefly responsible with suppressed sclerostin and increased active β-catenin. Increased uric acid levels also suggested that abnormalities in purine-metabolism and a reduced fractional excretion of uric acid signaled additional renal transport changes. The MN mouse developed a worsening hyperphosphatemia and reduced FGF23 with age. An increase in the fractional excretion of phosphate (FEP) despite the hyperphosphatemia confirms an imbalance in kidney-intestinal phosphate regulation. Also, the MN mice showed an increased creatinine clearance suggesting hyperfiltration. A reversal of the MN bone-renal phenotype changes occurred with the MNAt mice including the apparent hyperfiltration. The MNAt mice also developed localized hypomineralization, hypophosphatemia and increased FGF23. CONCLUSIONS The C-terminal ASARM-motif plays a major role in regulating bone-mass and cancellous structure as mice age. In healthy mice, the processing and release of free ASARM-peptide are chiefly responsible for preserving normal bone and renal function. Free ASARM-peptide also affects renal mineral phosphate handling by influencing FGF23 expression. These findings have implications for understanding age-dependent osteoporosis, unraveling drug-targets and developing treatments.
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Affiliation(s)
- Lesya V Zelenchuk
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Anne-Marie Hedge
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Peter S N Rowe
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA.
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24
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Silva SRB, Illarramendi X, Tempone AJ, Silva PHL, Nery JAC, Monteiro AMV, Pessolani MCV, Boasquevisque E, Sarno EN, Pereira GMB, Esquenazi D. Downregulation of PHEX in multibacillary leprosy patients: observational cross-sectional study. J Transl Med 2015; 13:296. [PMID: 26362198 PMCID: PMC4566286 DOI: 10.1186/s12967-015-0651-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 08/25/2015] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Peripheral nerve injury and bone lesions, well known leprosy complications, lead to deformities and incapacities. The phosphate-regulating gene with homologies to endopeptidase on the X chromosome (PHEX) encodes a homonymous protein (PHEX) implicated in bone metabolism. PHEX/PHEX alterations may result in bone and cartilage lesions. PHEX expression is downregulated by intracellular Mycobacterium leprae (M. leprae) in cultures of human Schwann cells and osteoblasts. M. leprae in vivo effect on PHEX/PHEX is not known. METHODS Cross-sectional observational study of 36 leprosy patients (22 lepromatous and 14 borderline-tuberculoid) and 20 healthy volunteers (HV). The following tests were performed: PHEX flow cytometric analysis on blood mononuclear cells, cytokine production in culture supernatant, 25-hydroxyvitamin D (OHvitD) serum levels and (99m)Tc-MDP three-phase bone scintigraphy, radiography of upper and lower extremities and blood and urine biochemistry. RESULTS Significantly lower PHEX expression levels were observed in lepromatous patients than in the other groups (χ(2) = 16.554, p < 0.001 for lymphocytes and χ(2) = 13.933, p = 0.001 for monocytes). Low levels of 25-(OHvitD) were observed in HV (median = 23.0 ng/mL) and BT patients (median = 27.5 ng/mL) and normal serum levels were found in LL patients (median = 38.6 ng/mL). Inflammatory cytokines, such as TNF, a PHEX transcription repressor, were lower after stimulation with M. leprae in peripheral blood mononuclear cells from lepromatous in comparison to BT patients and HV (χ(2) = 10.820, p < 0.001). CONCLUSION Downregulation of PHEX may constitute an important early component of bone loss and joint damage in leprosy. The present results suggest a direct effect produced by M. leprae on the osteoarticular system that may use this mechanism.
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Affiliation(s)
- Sandra R Boiça Silva
- Disciplina de Patologia Geral e Laboratório de Imunopatologia, Departamento de Patologia e Laboratórios, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro (UERJ), Av Professor Manuel de Abreu 444, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil.
| | - Ximena Illarramendi
- Laboratório de Hanseníase, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Antonio J Tempone
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Pedro H L Silva
- Laboratório de Hanseníase, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - José A C Nery
- Laboratório de Hanseníase, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Alexandra M V Monteiro
- Serviço de Medicina Nuclear, Departamento de Radiologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro (UERJ), Av. Prof. Manuel de Abreu 444, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil.
| | - Maria Cristina V Pessolani
- Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Edson Boasquevisque
- Serviço de Medicina Nuclear, Departamento de Radiologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro (UERJ), Av. Prof. Manuel de Abreu 444, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil.
| | - Euzenir N Sarno
- Laboratório de Hanseníase, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Geraldo M B Pereira
- Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil. .,Disciplina de Patologia Geral e Laboratório de Imunopatologia, Departamento de Patologia e Laboratórios, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro (UERJ), Av Professor Manuel de Abreu 444, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil.
| | - Danuza Esquenazi
- Laboratório de Hanseníase, Instituto Oswaldo Cruz (IOC) - Oswaldo Cruz Foundation (FIOCRUZ), Av. Brasil 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil. .,Disciplina de Patologia Geral e Laboratório de Imunopatologia, Departamento de Patologia e Laboratórios, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro (UERJ), Av Professor Manuel de Abreu 444, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil.
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25
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Zelenchuk LV, Hedge AM, Rowe PSN. SPR4-peptide alters bone metabolism of normal and HYP mice. Bone 2015; 72:23-33. [PMID: 25460577 PMCID: PMC4342984 DOI: 10.1016/j.bone.2014.11.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/06/2014] [Accepted: 11/14/2014] [Indexed: 11/13/2022]
Abstract
CONTEXT ASARM-peptides are substrates and ligands for PHEX, the gene responsible for X-linked hypophosphatemic rickets (HYP). PHEX binds to the DMP1-ASARM-motif to form a trimeric-complex with α5β3-integrin on the osteocyte surface and this suppresses FGF23 expression. ASARM-peptide disruption of this complex increases FGF23 expression. We used a 4.2kDa peptide (SPR4) that binds to ASARM-peptide and ASARM-motif to study DMP1-PHEX interactions and to assess SPR4 for treating inherited hypophosphatemic rickets. DESIGN Subcutaneously transplanted osmotic pumps were used to infuse SPR4-peptide or vehicle into wild-type mice (WT) and HYP-mice for 4 weeks. RESULTS Asymmetrically distributed mineralization defects occurred with WT-SPR4 femurs. Specifically, SPR4 induced negative effects on trabecular bone and increased bone volume and mineralization in cortical-bone. Markedly increased sclerostin and reduced active β-catenin occurred with HYP mice. SPR4-infusion suppressed sclerostin and increased active β-catenin in WT and HYP mice and improved HYP-mice trabecular mineralization defects but not cortical mineralization defects. CONCLUSIONS SPR4-peptide has bimodal activity and acts by: (1) preventing DMP1 binding to PHEX and (2) sequestering an inhibitor of DMP1-PHEX binding, ASARM-peptide. In PHEX defective HYP-mice the second pathway predominates. Although SPR4-peptide improved trabecular calcification defects, decreased sclerostin and increased active β-catenin it did not correct HYP-mice cortical mineralization defects on a normal phosphate diet. Thus, for inherited hypophosphatemic rickets patients on a normal phosphate diet, SPR4-peptide is not a useful therapeutic.
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Affiliation(s)
- Lesya V Zelenchuk
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Anne-Marie Hedge
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA
| | - Peter S N Rowe
- The Kidney Institute, Kansas University Medical Center, Kansas City, KS, USA.
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26
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Abstract
The increased awareness of the potential role played by mineral and bone disorder in the appearance of cardiovascular disease in renal patients has produced research efforts aimed at discovering possible pathogenic links. Accordingly, the diagnostic significance of the classic bone markers of mineral disorders and of the new markers in the setting of chronic kidney disease-mineral and bone disorders (CKD-MBD) needs to be re-evaluated along with increasing information. In this article we include classic markers of bone metabolism and some of the noncollagenous bone proteins that are gaining experimental and clinical significance in CKD-MBD. Among classic markers of secondary hyperparathyroidism and of renal osteodystrophy, we analyzed parathyroid hormone, alkaline phosphatase, tartrate-resistant acid phosphatase, and bone collagen-derived peptides. We underlined, for each, the relevance of parent proteins (peptides or isoforms) that affect assay methods and, eventually, the diagnostic or prognostic significance. Also, we considered their relationship with cardiovascular mortality. Among the numerous noncollagenous bone proteins, we examined matrix Gla protein (MGP), osteocalcin (OC), osteoprotegerin, and the small integrin-binding ligand N-linked glycoprotein family. For MGP and OC we report the relevant involvement with the process of calcification (MGP) and with glucose and energy metabolism (OC). Both of these proteins require vitamin K to become active and this is a specific problem in renal patients who frequently are deficient of this vitamin. Finally, recent acquisitions on the fascinating family of the small integrin-binding ligand N-linked glycoprotein proteins are recapitulated briefly to underline their potential clinical interest and their complex involvement with all aspects of CKD-MBD. Their diagnostic role in clinical practice awaits further studies.
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Affiliation(s)
- Sandro Mazzaferro
- Department of Cardiovascular, Respiratory, Nephrologic and Geriatric Sciences, Sapienza University of Rome, Rome, Italy.
| | - Lida Tartaglione
- Department of Cardiovascular, Respiratory, Nephrologic and Geriatric Sciences, Sapienza University of Rome, Rome, Italy
| | - Silverio Rotondi
- Department of Cardiovascular, Respiratory, Nephrologic and Geriatric Sciences, Sapienza University of Rome, Rome, Italy
| | - Jordi Bover
- Department of Nephrology, Fundaciò Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - David Goldsmith
- King's Health Partners, Academic Health Science Centre, London, United Kingdom
| | - Marzia Pasquali
- Department of Cardiovascular, Respiratory, Nephrologic and Geriatric Sciences, Sapienza University of Rome, Rome, Italy
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27
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Zelenchuk LV, Hedge AM, Rowe PSN. PHEX mimetic (SPR4-peptide) corrects and improves HYP and wild type mice energy-metabolism. PLoS One 2014; 9:e97326. [PMID: 24839967 PMCID: PMC4026222 DOI: 10.1371/journal.pone.0097326] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 04/17/2014] [Indexed: 12/19/2022] Open
Abstract
CONTEXT PHEX or DMP1 mutations cause hypophosphatemic-rickets and altered energy metabolism. PHEX binds to DMP1-ASARM-motif to form a complex with α5β3 integrin that suppresses FGF23 expression. ASARM-peptides increase FGF23 by disrupting the PHEX-DMP1-Integrin complex. We used a 4.2 kDa peptide (SPR4) that binds to ASARM-peptide/motif to study the DMP1-PHEX interaction and to assess SPR4 for the treatment of energy metabolism defects in HYP and potentially other bone-mineral disorders. DESIGN Subcutaneously transplanted osmotic pumps were used to infuse SPR4-peptide or vehicle (VE) into wild-type mice (WT) and HYP-mice (PHEX mutation) for 4 weeks. RESULTS SPR4 partially corrected HYP mice hypophosphatemia and increased serum 1.25(OH)2D3. Serum FGF23 remained high and PTH was unaffected. WT-SPR4 mice developed hypophosphatemia and hypercalcemia with increased PTH, FGF23 and 1.25(OH)2D3. SPR4 increased GAPDH HYP-bone expression 60× and corrected HYP-mice hyperglycemia and hypoinsulinemia. HYP-VE serum uric-acid (UA) levels were reduced and SPR4 infusion suppressed UA levels in WT-mice but not HYP-mice. SPR4 altered leptin, adiponectin, and sympathetic-tone and increased the fat mass/weight ratio for HYP and WT mice. Expression of perlipin-2 a gene involved in obesity was reduced in HYP-VE and WT-SPR4 mice but increased in HYP-SPR4 mice. Also, increased expression of two genes that inhibit insulin-signaling, ENPP1 and ESP, occurred with HYP-VE mice. In contrast, SPR4 reduced expression of both ENPP1 and ESP in WT mice and suppressed ENPP1 in HYP mice. Increased expression of FAM20C and sclerostin occurred with HYP-VE mice. SPR4 suppressed expression of FAM20C and sclerostin in HYP and WT mice. CONCLUSIONS ASARM peptides and motifs are physiological substrates for PHEX and modulate osteocyte PHEX-DMP1-α5β3-integrin interactions and thereby FGF23 expression. These interactions also provide a nexus that regulates bone and energy metabolism. SPR4 suppression of sclerostin and/or sequestration of ASARM-peptides improves energy metabolism and may have utility for treating familial rickets, osteoporosis, obesity and diabetes.
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Affiliation(s)
- Lesya V. Zelenchuk
- Internal Medicine, The Kidney Institute, Kansas University Medical Center (KUMC), Kansas City, Kansas, United States of America
| | - Anne-Marie Hedge
- Internal Medicine, The Kidney Institute, Kansas University Medical Center (KUMC), Kansas City, Kansas, United States of America
| | - Peter S. N. Rowe
- Internal Medicine, The Kidney Institute, Kansas University Medical Center (KUMC), Kansas City, Kansas, United States of America
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28
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Staines KA, Zhu D, Farquharson C, MacRae VE. Identification of novel regulators of osteoblast matrix mineralization by time series transcriptional profiling. J Bone Miner Metab 2014; 32:240-51. [PMID: 23925391 DOI: 10.1007/s00774-013-0493-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 06/17/2013] [Indexed: 12/20/2022]
Abstract
Bone mineralization is a carefully orchestrated process, regulated by a number of promoters and inhibitors that function to ensure effective hydroxyapatite formation. Here we sought to identify new regulators of this process through a time series microarray analysis of mineralising primary osteoblast cultures over a 27 day culture period. To our knowledge this is the first microarray study investigating murine calvarial osteoblasts cultured under conditions that permit both physiological extracellular matrix mineralization through the formation of discrete nodules and the terminal differentiation of osteoblasts into osteocytes. RT-qPCR was used to validate and expand the microarray findings. We demonstrate the significant up-regulation of >6,000 genes during the osteoblast mineralization process, the highest-ranked differentially expressed genes of which were those dominated by members of the PPAR-γ signalling pathway, namely Adipoq, Cd36 and Fabp4. Furthermore, we show that the inhibition of this signalling pathway promotes matrix mineralisation in these primary osteoblast cultures. We also identify Cilp, Phex, Trb3, Sox11, and Psat1 as novel regulators of matrix mineralization. Further studies examining the precise function of the identified genes and their interactions will advance our understanding of the mechanisms underpinning biomineralization.
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Affiliation(s)
- Katherine Ann Staines
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK,
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29
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McKee MD, Hoac B, Addison WN, Barros NM, Millán JL, Chaussain C. Extracellular matrix mineralization in periodontal tissues: Noncollagenous matrix proteins, enzymes, and relationship to hypophosphatasia and X-linked hypophosphatemia. Periodontol 2000 2013; 63:102-22. [PMID: 23931057 PMCID: PMC3766584 DOI: 10.1111/prd.12029] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2012] [Indexed: 12/26/2022]
Abstract
As broadly demonstrated for the formation of a functional skeleton, proper mineralization of periodontal alveolar bone and teeth - where calcium phosphate crystals are deposited and grow within an extracellular matrix - is essential for dental function. Mineralization defects in tooth dentin and cementum of the periodontium invariably lead to a weak (soft or brittle) dentition in which teeth become loose and prone to infection and are lost prematurely. Mineralization of the extremities of periodontal ligament fibers (Sharpey's fibers) where they insert into tooth cementum and alveolar bone is also essential for the function of the tooth-suspensory apparatus in occlusion and mastication. Molecular determinants of mineralization in these tissues include mineral ion concentrations (phosphate and calcium), pyrophosphate, small integrin-binding ligand N-linked glycoproteins and matrix vesicles. Amongst the enzymes important in regulating these mineralization determinants, two are discussed at length here, with clinical examples given, namely tissue-nonspecific alkaline phosphatase and phosphate-regulating gene with homologies to endopeptidases on the X chromosome. Inactivating mutations in these enzymes in humans and in mouse models lead to the soft bones and teeth characteristic of hypophosphatasia and X-linked hypophosphatemia, respectively, where the levels of local and systemic circulating mineralization determinants are perturbed. In X-linked hypophosphatemia, in addition to renal phosphate wasting causing low circulating phosphate levels, phosphorylated mineralization-regulating small integrin-binding ligand N-linked glycoproteins, such as matrix extracellular phosphoglycoprotein and osteopontin, and the phosphorylated peptides proteolytically released from them, such as the acidic serine- and aspartate-rich-motif peptide, may accumulate locally to impair mineralization in this disease.
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Affiliation(s)
- Marc D. McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
- Department of Anatomy and Cell Biology, Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Betty Hoac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - William N. Addison
- Department of Oral Medicine, Infection and Immunity, Harvard University School of Dental Medicine, Boston, MA, USA
| | - Nilana M.T. Barros
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brasil, and Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Diadema, SP, Brasil
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Catherine Chaussain
- EA 2496, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité; AP-HP: Odontology Department Bretonneau, Paris and Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium, Kremlin Bicêtre, France
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30
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Abstract
Few investigators think of bone as an endocrine gland, even after the discovery that osteocytes produce circulating fibroblast growth factor 23 that targets the kidney and potentially other organs. In fact, until the last few years, osteocytes were perceived by many as passive, metabolically inactive cells. However, exciting recent discoveries have shown that osteocytes encased within mineralized bone matrix are actually multifunctional cells with many key regulatory roles in bone and mineral homeostasis. In addition to serving as endocrine cells and regulators of phosphate homeostasis, these cells control bone remodeling through regulation of both osteoclasts and osteoblasts, are mechanosensory cells that coordinate adaptive responses of the skeleton to mechanical loading, and also serve as a manager of the bone's reservoir of calcium. Osteocytes must survive for decades within the bone matrix, making them one of the longest lived cells in the body. Viability and survival are therefore extremely important to ensure optimal function of the osteocyte network. As we continue to search for new therapeutics, in addition to the osteoclast and the osteoblast, the osteocyte should be considered in new strategies to prevent and treat bone disease.
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Affiliation(s)
- Sarah L Dallas
- PhD, Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, 650 East 25th Street, Kansas City, Missouri 64108.
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31
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Barros NMT, Hoac B, Neves RL, Addison WN, Assis DM, Murshed M, Carmona AK, McKee MD. Proteolytic processing of osteopontin by PHEX and accumulation of osteopontin fragments in Hyp mouse bone, the murine model of X-linked hypophosphatemia. J Bone Miner Res 2013; 28:688-99. [PMID: 22991293 DOI: 10.1002/jbmr.1766] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 08/21/2012] [Accepted: 09/07/2012] [Indexed: 12/11/2022]
Abstract
X-linked hypophosphatemia (XLH/HYP)-with renal phosphate wasting, hypophosphatemia, osteomalacia, and tooth abscesses-is caused by mutations in the zinc-metallopeptidase PHEX gene (phosphate-regulating gene with homologies to endopeptidase on the X chromosome). PHEX is highly expressed by mineralized tissue cells. Inactivating mutations in PHEX lead to distal renal effects (implying accumulation of a secreted, circulating phosphaturic factor) and accumulation in bone and teeth of mineralization-inhibiting, acidic serine- and aspartate-rich motif (ASARM)-containing peptides, which are proteolytically derived from the mineral-binding matrix proteins of the SIBLING family (small, integrin-binding ligand N-linked glycoproteins). Although the latter observation suggests a local, direct matrix effect for PHEX, its physiologically relevant substrate protein(s) have not been identified. Here, we investigated two SIBLING proteins containing the ASARM motif-osteopontin (OPN) and bone sialoprotein (BSP)-as potential substrates for PHEX. Using cleavage assays, gel electrophoresis, and mass spectrometry, we report that OPN is a full-length protein substrate for PHEX. Degradation of OPN was essentially complete, including hydrolysis of the ASARM motif, resulting in only very small residual fragments. Western blotting of Hyp (the murine homolog of human XLH) mouse bone extracts having no PHEX activity clearly showed accumulation of an ∼35 kDa OPN fragment that was not present in wild-type mouse bone. Immunohistochemistry and immunogold labeling (electron microscopy) for OPN in Hyp bone likewise showed an accumulation of OPN and/or its fragments compared with normal wild-type bone. Incubation of Hyp mouse bone extracts with PHEX resulted in the complete degradation of these fragments. In conclusion, these results identify full-length OPN and its fragments as novel, physiologically relevant substrates for PHEX, suggesting that accumulation of mineralization-inhibiting OPN fragments may contribute to the mineralization defect seen in the osteomalacic bone characteristic of XLH/HYP.
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Affiliation(s)
- Nilana M T Barros
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil.
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Salmon B, Bardet C, Khaddam M, Naji J, Coyac BR, Baroukh B, Letourneur F, Lesieur J, Decup F, Le Denmat D, Nicoletti A, Poliard A, Rowe PS, Huet E, Vital SO, Linglart A, McKee MD, Chaussain C. MEPE-derived ASARM peptide inhibits odontogenic differentiation of dental pulp stem cells and impairs mineralization in tooth models of X-linked hypophosphatemia. PLoS One 2013; 8:e56749. [PMID: 23451077 PMCID: PMC3579870 DOI: 10.1371/journal.pone.0056749] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 01/13/2013] [Indexed: 01/09/2023] Open
Abstract
Mutations in PHEX (phosphate-regulating gene with homologies to endopeptidases on the X-chromosome) cause X-linked familial hypophosphatemic rickets (XLH), a disorder having severe bone and tooth dentin mineralization defects. The absence of functional PHEX leads to abnormal accumulation of ASARM (acidic serine- and aspartate-rich motif) peptide − a substrate for PHEX and a strong inhibitor of mineralization − derived from MEPE (matrix extracellular phosphoglycoprotein) and other matrix proteins. MEPE-derived ASARM peptide accumulates in tooth dentin of XLH patients where it may impair dentinogenesis. Here, we investigated the effects of ASARM peptides in vitro and in vivo on odontoblast differentiation and matrix mineralization. Dental pulp stem cells from human exfoliated deciduous teeth (SHEDs) were seeded into a 3D collagen scaffold, and induced towards odontogenic differentiation. Cultures were treated with synthetic ASARM peptides (phosphorylated and nonphosphorylated) derived from the human MEPE sequence. Phosphorylated ASARM peptide inhibited SHED differentiation in vitro, with no mineralized nodule formation, decreased odontoblast marker expression, and upregulated MEPE expression. Phosphorylated ASARM peptide implanted in a rat molar pulp injury model impaired reparative dentin formation and mineralization, with increased MEPE immunohistochemical staining. In conclusion, using complementary models to study tooth dentin defects observed in XLH, we demonstrate that the MEPE-derived ASARM peptide inhibits both odontogenic differentiation and matrix mineralization, while increasing MEPE expression. These results contribute to a partial mechanistic explanation of XLH pathogenesis: direct inhibition of mineralization by ASARM peptide leads to the mineralization defects in XLH teeth. This process appears to be positively reinforced by the increased MEPE expression induced by ASARM. The MEPE-ASARM system can therefore be considered as a potential therapeutic target.
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Affiliation(s)
- Benjamin Salmon
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
- AP-HP Odontology Department Bretonneau – Louis Mourier, Hôpitaux Universitaires Paris Nord Val de Seine, Paris France
- Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium, AP-HP, Kremlin Bicêtre, France
| | - Claire Bardet
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Mayssam Khaddam
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Jiar Naji
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Benjamin R. Coyac
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
- AP-HP Odontology Department Bretonneau – Louis Mourier, Hôpitaux Universitaires Paris Nord Val de Seine, Paris France
- Faculty of Dentistry, and Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Brigitte Baroukh
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Franck Letourneur
- Institut Cochin, University Paris Descartes PRES Sorbonne Paris Cité, Paris, France
| | - Julie Lesieur
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Franck Decup
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
- AP-HP Odontology Department Charles Foix, Ivry Sur Seine, France
| | - Dominique Le Denmat
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Antonino Nicoletti
- Inserm UMRS698, Paris, France
- Denis Diderot University, UMRS698, Paris, France
| | - Anne Poliard
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
| | - Peter S. Rowe
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Eric Huet
- Université Paris-Est, Laboratoire CRRET, CNRS, Créteil, France
| | - Sibylle Opsahl Vital
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
- AP-HP Odontology Department Bretonneau – Louis Mourier, Hôpitaux Universitaires Paris Nord Val de Seine, Paris France
- Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium, AP-HP, Kremlin Bicêtre, France
| | - Agnès Linglart
- Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium, AP-HP, Kremlin Bicêtre, France
- APHP Endocrinology and Diabetology for Children, Bicêtre Paris Sud Hospital, Kremlin Bicêtre, France
- Université Paris-Sud, Kremlin Bicêtre, France
| | - Marc D. McKee
- Faculty of Dentistry, and Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Catherine Chaussain
- EA 2496, Pathologies, Imaging and Biotherapies of the Tooth, UFR Odontologie, University Paris Descartes PRES Sorbonne Paris Cité, Montrouge, France
- AP-HP Odontology Department Bretonneau – Louis Mourier, Hôpitaux Universitaires Paris Nord Val de Seine, Paris France
- Centre de Référence des Maladies Rares du Métabolisme du Phosphore et du Calcium, AP-HP, Kremlin Bicêtre, France
- * E-mail:
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Staines KA, Mackenzie NCW, Clarkin CE, Zelenchuk L, Rowe PS, MacRae VE, Farquharson C. MEPE is a novel regulator of growth plate cartilage mineralization. Bone 2012; 51:418-30. [PMID: 22766095 PMCID: PMC3427007 DOI: 10.1016/j.bone.2012.06.022] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 06/21/2012] [Accepted: 06/23/2012] [Indexed: 01/24/2023]
Abstract
Matrix extracellular phosphoglycoprotein (MEPE) belongs to the SIBLING protein family which play key roles in biomineralization. Although the growth plates of MEPE-overexpressing mice display severe morphological disruption, the expression and function of MEPE in growth plate matrix mineralization remains largely undefined. Here we show MEPE and its cleavage product, the acidic serine aspartate-rich MEPE-associated motif (ASARM) peptide, to be localised to the hypertrophic zone of the growth plate. We also demonstrate that the phosphorylated (p)ASARM peptide inhibits ATDC5 chondrocyte matrix mineralization. Stable MEPE-overexpressing ATDC5 cells also had significantly reduced matrix mineralization in comparison to the control cells. Interestingly, we show that the addition of the non-phosphorylated (np)ASARM peptide promoted mineralization in the ATDC5 cells. The peptides and the overexpression of MEPE did not affect the differentiation of the ATDC5 cells. For a more physiologically relevant model, we utilized the metatarsal organ culture model. We show the pASARM peptide to inhibit mineralization at two stages of development, as shown by histological and μCT analysis. Like in the ATDC5 cells, the peptides did not affect the differentiation of the metatarsals indicating that the effects seen on mineralization are direct, as is additionally confirmed by no change in alkaline phosphatase activity or mRNA expression. In the metatarsal organ cultures, the pASARM peptide also reduced endothelial cell markers and vascular endothelial growth factor mRNA expression. Taken together these results show MEPE to be an important regulator of growth plate chondrocyte matrix mineralization through its cleavage to an ASARM peptide.
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Affiliation(s)
- K A Staines
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
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Staines KA, MacRae VE, Farquharson C. The importance of the SIBLING family of proteins on skeletal mineralisation and bone remodelling. J Endocrinol 2012; 214:241-55. [PMID: 22700194 DOI: 10.1530/joe-12-0143] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The small integrin-binding ligand N-linked glycoprotein (SIBLING) family consists of osteopontin, bone sialoprotein, dentin matrix protein 1, dentin sialophosphoprotein and matrix extracellular phosphoglycoprotein. These proteins share many structural characteristics and are primarily located in bone and dentin. Accumulating evidence has implicated the SIBLING proteins in matrix mineralisation. Therefore, in this review, we discuss the individual role that each of the SIBLING proteins has in this highly orchestrated process. In particular, we emphasise how the nature and extent of their proteolytic processing and post-translational modification affect their functional role. Finally, we describe the likely roles of the SIBLING proteins in clinical disorders of hypophosphataemia and their potential therapeutic use.
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Affiliation(s)
- Katherine A Staines
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Edinburgh, Midlothian EH25 9RG, UK.
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Abstract
Osteocytes were the forgotten bone cell until the bone community could become convinced that these cells do serve an important role in bone function and maintenance. In this review we trace the history of osteocyte characterization and present some of the major observations that are leading to the conclusion that these cells are not passive placeholders residing in the bone matrix, but are indeed, major orchestrators of bone remodeling.
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Affiliation(s)
- Dayong Guo
- University of Missouri, Kansas City, MO, USA
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Rowe PSN. The chicken or the egg: PHEX, FGF23 and SIBLINGs unscrambled. Cell Biochem Funct 2012; 30:355-75. [PMID: 22573484 PMCID: PMC3389266 DOI: 10.1002/cbf.2841] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 03/23/2012] [Accepted: 04/18/2012] [Indexed: 12/17/2022]
Abstract
The eggshell is an ancient innovation that helped the vertebrates' transition from the oceans and gain dominion over the land. Coincident with this conquest, several new eggshell and noncollagenous bone-matrix proteins (NCPs) emerged. The protein ovocleidin-116 is one of these proteins with an ancestry stretching back to the Triassic. Ovocleidin-116 is an avian homolog of Matrix Extracellular Phosphoglycoprotein (MEPE) and belongs to a group of proteins called Small Integrin-Binding Ligand Interacting Glycoproteins (SIBLINGs). The genes for these NCPs are all clustered on chromosome 5q in mice and chromosome 4q in humans. A unifying feature of the SIBLING proteins is an Acidic Serine Aspartate-Rich MEPE (ASARM)-associated motif. The ASARM motif and the released ASARM peptide play roles in mineralization, bone turnover, mechanotransduction, phosphate regulation and energy metabolism. ASARM peptides and motifs are physiological substrates for phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX), a Zn metalloendopeptidase. Defects in PHEX are responsible for X-linked hypophosphatemic rickets. PHEX interacts with another ASARM motif containing SIBLING protein, Dentin Matrix Protein-1 (DMP1). DMP1 mutations cause bone-renal defects that are identical with the defects caused by loss of PHEX function. This results in autosomal recessive hypophosphatemic rickets (ARHR). In both X-linked hypophosphatemic rickets and ARHR, increased fibroblast growth factor 23 (FGF23) expression occurs, and activating mutations in FGF23 cause autosomal dominant hypophosphatemic rickets (ADHR). ASARM peptide administration in vitro and in vivo also induces increased FGF23 expression. This review will discuss the evidence for a new integrative pathway involved in bone formation, bone-renal mineralization, renal phosphate homeostasis and energy metabolism in disease and health.
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Affiliation(s)
- Peter S N Rowe
- Department of Internal Medicine, The Kidney Institute, Division of Nephrology and Hypertension, University of Kansas Medical Center, Kansas City, KS, USA.
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Vital SO, Gaucher C, Bardet C, Rowe P, George A, Linglart A, Chaussain C. Tooth dentin defects reflect genetic disorders affecting bone mineralization. Bone 2012; 50:989-97. [PMID: 22296718 PMCID: PMC3345892 DOI: 10.1016/j.bone.2012.01.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/06/2012] [Accepted: 01/14/2012] [Indexed: 01/27/2023]
Abstract
Several genetic disorders affecting bone mineralization may manifest during dentin mineralization. Dentin and bone are similar in several aspects, especially pertaining to the composition of the extracellular matrix (ECM) which is secreted by well-differentiated odontoblasts and osteoblasts, respectively. However, unlike bone, dentin is not remodelled and is not involved in the regulation of calcium and phosphate metabolism. In contrast to bone, teeth are accessible tissues with the shedding of deciduous teeth and the extractions of premolars and third molars for orthodontic treatment. The feasibility of obtaining dentin makes this a good model to study biomineralization in physiological and pathological conditions. In this review, we focus on two genetic diseases that disrupt both bone and dentin mineralization. Hypophosphatemic rickets is related to abnormal secretory proteins involved in the ECM organization of both bone and dentin, as well as in the calcium and phosphate metabolism. Osteogenesis imperfecta affects proteins involved in the local organization of the ECM. In addition, dentin examination permits evaluation of the effects of the systemic treatment prescribed to hypophosphatemic patients during growth. In conclusion, dentin constitutes a valuable tool for better understanding of the pathological processes affecting biomineralization.
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Affiliation(s)
- S. Opsahl Vital
- Dental School University Paris Descartes PRES Sorbonne Paris Cité, EA 2496, Montrouge, F-92120, France
- AP-HP, Odontology Department, Hôpitaux Universitaires Paris Nord Val de Seine (Bretonneau- Louis Mourier), F-75018, France
- Centre de référence des maladies rares du métabolisme du phosphore et du calcium, Kremlin Bicêtre, AP-HP, F-94275, France
| | - C. Gaucher
- Dental School University Paris Descartes PRES Sorbonne Paris Cité, EA 2496, Montrouge, F-92120, France
- AP-HP, Odontology Department, Hôpital Albert Chennevier, Créteil, F-94010, France
- Centre de référence des maladies rares du métabolisme du phosphore et du calcium, Kremlin Bicêtre, AP-HP, F-94275, France
| | - C. Bardet
- Dental School University Paris Descartes PRES Sorbonne Paris Cité, EA 2496, Montrouge, F-92120, France
| | - P.S. Rowe
- The Kidney Institute, University of Kansas Medical Center, Kansas City, KS, USA
| | - A. George
- Department of Oral Biology, University of Illinois in Chicago, Illinois 60612, USA
| | - A. Linglart
- Inserm, U986 Hôpital St Vincent de Paul AP-HP, Paris, F-75014, France
- Centre de référence des maladies rares du métabolisme du phosphore et du calcium, Kremlin Bicêtre, AP-HP, F-94275, France
| | - C. Chaussain
- Dental School University Paris Descartes PRES Sorbonne Paris Cité, EA 2496, Montrouge, F-92120, France
- AP-HP, Odontology Department, Hôpitaux Universitaires Paris Nord Val de Seine (Bretonneau- Louis Mourier), F-75018, France
- Centre de référence des maladies rares du métabolisme du phosphore et du calcium, Kremlin Bicêtre, AP-HP, F-94275, France
- Corresponding author at: Dental school University Paris Descartes PRES Sorbonne Paris Cité, EA 2496, Montrouge, France 2120. Fax: +33 158076724. (C. Chaussain)
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Imanishi Y, Hashimoto J, Ando W, Kobayashi K, Ueda T, Nagata Y, Miyauchi A, Koyano HM, Kaji H, Saito T, Oba K, Komatsu Y, Morioka T, Mori K, Miki T, Inaba M. Matrix extracellular phosphoglycoprotein is expressed in causative tumors of oncogenic osteomalacia. J Bone Miner Metab 2012; 30:93-9. [PMID: 21739089 DOI: 10.1007/s00774-011-0290-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 06/05/2011] [Indexed: 01/23/2023]
Abstract
Oncogenic osteomalacia (OOM), or tumor-induced osteomalacia, is a rare disease characterized by renal phosphate wasting and osteomalacia. It arises due to the secretion of fibroblast growth factor 23 (FGF-23) from causative tumors. Matrix extracellular phosphoglycoprotein (MEPE) is predominantly expressed in odontoblasts, osteoblasts, and osteocytes. Although the presence of MEPE mRNA has been reported in some OOM tumors, little is known about the prevalence of MEPE expression in OOM tumors. In this study, the expression of MEPE and FGF-23 in OOM tumors was investigated at the transcriptional and translational levels. Eleven causative OOM tumors were analyzed by quantitative real-time reverse transcription-polymerase chain reaction and immunohistochemistry for MEPE and FGF-23 expression. Hemangiopericytomas and giant cell tumors, pathological diagnoses that are common in cases of OOM, were obtained from non-osteomalacic patients and analyzed as controls. The gene expression level of FGF23 and MEPE in OOM tumors was 10(4)- and 10(5)-times higher, respectively, than in non-OOM tumors. Immunohistochemical staining revealed that FGF-23 protein was expressed in all OOM tumors, and MEPE was expressed in 10 out of 11 OOM tumors. Thus, MEPE expression was common in OOM tumors, similar to FGF-23. These results indicate that, in addition to the hypophosphatemic effects of FGF-23, MEPE or the MEPE-derived acidic serine aspartate-rich MEPE-associated motif peptide may contribute to decreased bone mineralization in OOM patients.
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Affiliation(s)
- Yasuo Imanishi
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, 1-4-3, Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
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Rowe PSN. Regulation of bone-renal mineral and energy metabolism: the PHEX, FGF23, DMP1, MEPE ASARM pathway. Crit Rev Eukaryot Gene Expr 2012; 22:61-86. [PMID: 22339660 PMCID: PMC3362997 DOI: 10.1615/critreveukargeneexpr.v22.i1.50] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
More than 300 million years ago, vertebrates emerged from the vast oceans to conquer gravity and the dry land. With this transition, new adaptations occurred that included ingenious changes in reproduction, waste secretion, and bone physiology. One new innovation, the egg shell, contained an ancestral protein (ovocleidin-116) that likely first appeared with the dinosaurs and was preserved through the theropod lineage in modern birds and reptiles. Ovocleidin-116 is an avian homolog of matrix extracellular phosphoglycoprotein (MEPE) and belongs to a group of proteins called short integrin-binding ligand-interacting glycoproteins (SIBLINGs). These proteins are all localized to a defined region on chromosome 5q in mice and chromosome 4q in humans. A unifying feature of SIBLING proteins is an acidic serine aspartate-rich MEPE-associated motif (ASARM). Recent research has shown that the ASARM motif and the released ASARM peptide have regulatory roles in mineralization (bone and teeth), phosphate regulation, vascularization, soft-tissue calcification, osteoclastogenesis, mechanotransduction, and fat energy metabolism. The MEPE ASARM motif and peptide are physiological substrates for PHEX, a zinc metalloendopeptidase. Defects in PHEX are responsible for X-linked hypophosphatemic rickets (HYP). There is evidence that PHEX interacts with another ASARM motif containing SIBLING protein, dentin matrix protein-1 (DMP1). DMP1 mutations cause bone and renal defects that are identical with the defects caused by a loss of PHEX function. This results in autosomal recessive hypophosphatemic rickets (ARHR). In both HYP and ARHR, increased FGF23 expression plays a major role in the disease and in autosomal dominant hypophosphatemic rickets (ADHR), FGF23 half-life is increased by activating mutations. ASARM peptide administration in vitro and in vivo also induces increased FGF23 expression. FGF23 is a member of the fibroblast growth factor (FGF) family of cytokines, which surfaced 500 million years ago with the boney fish (i.e., teleosts) that do not contain SIBLING proteins. In terrestrial vertebrates, FGF23, like SIBLING proteins, is expressed in the osteocyte. The boney fish, however, are an-osteocytic, so a physiological bone-renal link with FGF23 and the SIBLINGs was cemented when life ventured from the oceans to the land during the Triassic period, approximately 300 million years ago. This link has been revealed by recent research that indicates a competitive displacement of a PHEX-DMP1 interaction by an ASARM peptide that leads to increased FGF23 expression. This review discusses the new discoveries that reveal a novel PHEX, DMP1, MEPE, ASARM peptide, and FGF23 bone-renal pathway. This pathway impacts not only bone formation, bone-renal mineralization, and renal phosphate homeostasis but also energy metabolism. The study of this new pathway is relevant for developing therapies for several diseases: bone-teeth mineral loss disorders, renal osteodystrophy, chronic kidney disease and bone mineralization disorders (CKD-MBD), end-stage renal diseases, ectopic arterial-calcification, cardiovascular disease renal calcification, diabetes, and obesity.
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Affiliation(s)
- Peter S N Rowe
- Department of Internal Medicine, The Kidney Institute and Division of Nephrology-Hypertension, University of Kansas Medical Center, Kansas City, Kansas, USA
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Masi L. Phosphatonins: new hormones involved in numerous inherited bone disorders. CLINICAL CASES IN MINERAL AND BONE METABOLISM : THE OFFICIAL JOURNAL OF THE ITALIAN SOCIETY OF OSTEOPOROSIS, MINERAL METABOLISM, AND SKELETAL DISEASES 2011; 8:9-13. [PMID: 22461821 PMCID: PMC3279060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phosphate (Pi) homeostasis is under control of several endocrine factors that play effects on bone, kidney and intestine. The control of Pi homeostasis has a significant biological importance, as it relates to numerous cellular mechanisms involved in energy metabolism, cell signaling, nucleic acid synthesis, membrane function, as well as skeletal health and integrity. Pi is essential for diverse biological processes, and negative Pi balance resulting from improperly regulated intestinal absorption, systemic utilization, and renal excretion. As results of these functions, chronic Pi deprivation causes several biological alterations, such as bone demineralization with unmineralized osateoid typical of osteomalacia in adults and rickets in developing animals and humans (1). Phosphatonins are new hormones playing an important role in the control of Pi homeostasis together with parathyroid hormone (PTH) and 1,25-dihydroxy vitamin D(3). Most insight into the underlying mechanisms was established by defining the molecular basis of different inherited disorders that are characterized by an abnormal regulation of Pi homeostasis.
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Affiliation(s)
- Laura Masi
- Department of Internal Medicine, Bone Metabolic Diseases Unit, University of Florence, Florence, Italy
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Moriyama K, Hanai A, Mekada K, Yoshiki A, Ogiwara K, Kimura A, Takahashi T. Kbus/Idr, a mutant mouse strain with skeletal abnormalities and hypophosphatemia: identification as an allele of 'Hyp'. J Biomed Sci 2011; 18:60. [PMID: 21854633 PMCID: PMC3175157 DOI: 10.1186/1423-0127-18-60] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 08/20/2011] [Indexed: 12/17/2022] Open
Abstract
Background The endopeptidase encoded by Phex (phosphate-regulating gene with homologies to endopeptidases linked to the X chromosome) is critical for regulation of bone matrix mineralization and phosphate homeostasis. PHEX has been identified from analyses of human X-linked hypophosphatemic rickets and Hyp mutant mouse models. We here demonstrated a newly established dwarfism-like Kbus/Idr mouse line to be a novel Hyp model. Methods Histopathological and X-ray examination with cross experiments were performed to characterize Kbus/Idr. RT-PCR-based and exon-directed PCR screening performed to identify the presence of genetic alteration. Biochemical assays were also performed to evaluate activity of alkaline phosphatase. Results Kbus/Idr, characterized by bone mineralization defects, was found to be inherited in an X chromosome-linked dominant manner. RT-PCR experiments showed that a novel mutation spanning exon 16 and 18 causing hypophosphatemic rickets. Alkaline phosphatase activity, as an osteoblast marker, demonstrated raised levels in the bone marrow of Kbus/Idr independent of the age. Conclusions Kbus mice should serve as a useful research tool exploring molecular mechanisms underlying aberrant Phex-associated pathophysiological phenomena.
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Affiliation(s)
- Kenji Moriyama
- Department of Medicine & Clinical Science, School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya 663-8179, Japan.
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Gorski JP. Biomineralization of bone: a fresh view of the roles of non-collagenous proteins. Front Biosci (Landmark Ed) 2011; 16:2598-621. [PMID: 21622198 DOI: 10.2741/3875] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The impact of genetics has dramatically affected our understanding of the functions of non-collagenous proteins. Specifically, mutations and knockouts have defined their cellular spectrum of actions. However, the biochemical mechanisms mediated by non-collagenous proteins in biomineralization remain elusive. It is likely that this understanding will require more focused functional testing at the protein, cell, and tissue level. Although initially viewed as rather redundant and static acidic calcium binding proteins, it is now clear that non-collagenous proteins in mineralizing tissues represent diverse entities capable of forming multiple protein-protein interactions which act in positive and negative ways to regulate the process of bone mineralization. Several new examples from the author's laboratory are provided which illustrate this theme including an apparent activating effect of hydroxyapatite crystals on metalloproteinases. This review emphasizes the view that secreted non-collagenous proteins in mineralizing bone actively participate in the mineralization process and ultimately control where and how much mineral crystal is deposited, as well as determining the quality and biomechanical properties of the mineralized matrix produced.
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Affiliation(s)
- Jeffrey Paul Gorski
- Center of Excellence in the Study of Musculoskeletal and Dental Tissues and Dept. of Oral Biology, Sch. Of Dentistry, Univ. of Missouri-Kansas City, Kansas City, MO 64108, USA.
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David V, Martin A, Hedge AM, Drezner MK, Rowe PSN. ASARM peptides: PHEX-dependent and -independent regulation of serum phosphate. Am J Physiol Renal Physiol 2011; 300:F783-91. [PMID: 21177780 PMCID: PMC3064126 DOI: 10.1152/ajprenal.00304.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 12/18/2010] [Indexed: 12/21/2022] Open
Abstract
Increased acidic serine aspartate-rich MEPE-associated motif (ASARM) peptides cause mineralization defects in X-linked hypophosphatemic rickets mice (HYP) and "directly" inhibit renal phosphate uptake in vitro. However, ASARM peptides also bind to phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) and are a physiological substrate for this bone-expressed, phosphate-regulating enzyme. We therefore tested the hypothesis that circulating ASARM peptides also "indirectly" contribute to a bone-renal PHEX-dependent hypophosphatemia in normal mice. Male mice (n = 5; 12 wk) were fed for 8 wk with a normal phosphorus and vitamin D(3) diet (1% P(i) diet) or a reduced phosphorus and vitamin D(3) diet (0.1% P(i) diet). For the final 4 wk, transplantation of mini-osmotic pumps supplied a continuous infusion of either ASARM peptide (5 mg·day(-1)·kg(-1)) or vehicle. HYP, autosomal recessive hypophosphatemic rickets (ARHR), and normal mice (no pumps or ASARM infusion; 0.4% P(i) diet) were used in a separate experiment designed to measure and compare circulating ASARM peptides in disease and health. ASARM treatment decreased serum phosphate concentration and renal phosphate cotransporter (NPT2A) mRNA with the 1% P(i) diet. This was accompanied by a twofold increase in serum ASARM and 1,25-dihydroxy vitamin D(3) [1,25 (OH)(2)D(3)] levels without changes in parathyroid hormone. For both diets, ASARM-treated mice showed significant increases in serum fibroblast growth factor 23 (FGF23; +50%) and reduced serum osteocalcin (-30%) and osteopontin (-25%). Circulating ASARM peptides showed a significant inverse correlation with serum P(i) and a significant positive correlation with fractional excretion of phosphate. We conclude that constitutive overexpression of ASARM peptides plays a "component" PHEX-independent part in the HYP and ARHR hypophosphatemia. In contrast, with wild-type mice, ASARM peptides likely play a bone PHEX-dependent role in renal phosphate regulation and FGF23 expression. They may also coordinate FGF23 expression by competitively modulating PHEX/DMP1 interactions and thus bone-renal mineral regulation.
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Affiliation(s)
- Valentin David
- University of Tennessee Health Science Center, Memphis, Tennessee, USA
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Cheng CY, Kuro-o M, Razzaque MS. Molecular regulation of phosphate metabolism by fibroblast growth factor-23-klotho system. Adv Chronic Kidney Dis 2011; 18:91-7. [PMID: 21406293 DOI: 10.1053/j.ackd.2010.11.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 11/11/2010] [Accepted: 11/30/2010] [Indexed: 11/11/2022]
Abstract
Phosphorus is an essential nutrient and is routinely assimilated through consumption of food. The body's need of phosphate is usually fulfilled by intestinal absorption of this element from the consumed food, whereas its serum level is tightly regulated by renal excretion or reabsorption. Sodium-dependent phosphate transporters, located in the luminal side of the proximal tubular epithelial cells, have a molecular control on renal phosphate excretion and reabsorption. The systemic regulation of phosphate metabolism is a complex multiorgan process, and the identification of fibroblast growth factor-23 (FGF23)-Klotho system as a potent phosphatonin has provided new mechanistic insights into the homeostatic control of phosphate. Hypophosphatemia as a result of an increase in urinary phosphate wasting after activation of the FGF23-Klotho system is a common phenomenon, observed in both animal and human studies, whereas suppression of the FGF23-Klotho system leads to the development of hyperphosphatemia. This article will briefly summarize how delicate interactions of the FGF23-klotho system can regulate systemic phosphate homeostasis.
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Wang H, Kawashima N, Iwata T, Xu J, Takahashi S, Sugiyama T, Suda H. MEPE Activated by Furin Promotes Pulpal Cell Adhesion. J Dent Res 2011; 90:529-34. [DOI: 10.1177/0022034510391057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Matrix extracellular phosphoglycoprotein (MEPE) is predominantly expressed in osteoblasts, osteocytes, and odontoblasts and plays key biological roles in bone and dentin metabolism. Post-translational modifications are essential for its activation. This study tested the hypothesis that MEPE is activated through proteolytic processing by furin in dental pulp. MEPE was present in three sizes, 1 full-length and 2 cleaved fragments; the cleavage site was 146R↓147. The proprotein convertase family, particularly furin, was a candidate enzyme. Introducing a substitution at the cleavage site inhibited hydrolysis, but there was no cleavage of MEPE expressed in furin-deficient LoVo cells. Therefore, furin is a strong candidate for the proteolytic cleavage of MEPE. The C-terminal cleavage product promoted cell adhesion via its RGD motif. These results indicate that proteolytic processing by furin may activate MEPE during its secretion from odontoblasts and may play important roles in dentinogenesis and pulpal homeostasis. Abbreviations: MEPE, matrix extracellular phosphoglycoprotein; PTM, post-translational modifications; OLC, odontoblast-lineage cells.
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Affiliation(s)
- H.G. Wang
- Department of Operative Dentistry and Endodontics, School of Stomatology, Fourth Military Medical University, China
| | - N. Kawashima
- Pulp Biology and Endodontics, Graduate School
- GCOE Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical & Dental University, 1–5-45, Bunkyo-ku, Tokyo 113–8549, Japan
| | - T. Iwata
- Institute of Advanced Biomedical Engineering and Science, Tokyo Women’s Medical University, Japan
| | - J. Xu
- Pulp Biology and Endodontics, Graduate School
| | | | - T. Sugiyama
- Department of Biochemistry, School of Medicine, Akita University, Japan
| | - H. Suda
- Pulp Biology and Endodontics, Graduate School
- GCOE Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical & Dental University, 1–5-45, Bunkyo-ku, Tokyo 113–8549, Japan
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The osteocyte--a novel endocrine regulator of body phosphate homeostasis. Maturitas 2010; 67:327-38. [PMID: 20884141 DOI: 10.1016/j.maturitas.2010.08.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 08/27/2010] [Accepted: 08/30/2010] [Indexed: 11/22/2022]
Abstract
Although osteocytes are the most abundant cell type in bone, much of their biology remains enigmatic. They are known to transduce mechanical stress into signals that initiate local bone remodeling, and are targets for systemic and local endocrine signals that affect bone architecture and mineral homeostasis. However, recent data reveal that osteocytes themselves act as endocrine cells that synthesize fibroblast growth factor 23 (FGF23) and several other phosphatonins, shown to underpin the systemic regulation of phosphate homeostasis. This review will synthesize the emerging discoveries concerning the osteocytic endocrine role in phosphate homeostasis through the biology and pathophysiology of these phosphatonins. We also suggest future research paths that might resolve existing uncertainties, and look ahead at how greater understanding might improve the management of clinical disorders of phosphate homeostasis.
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Boukpessi T, Gaucher C, Léger T, Salmon B, Le Faouder J, Willig C, Rowe PS, Garabédian M, Meilhac O, Chaussain C. Abnormal presence of the matrix extracellular phosphoglycoprotein-derived acidic serine- and aspartate-rich motif peptide in human hypophosphatemic dentin. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:803-12. [PMID: 20581062 DOI: 10.2353/ajpath.2010.091231] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Severe dental troubles are associated with X-linked hypophosphatemic rickets and are mainly related to impaired dentin mineralization. In dentin matrix, matrix extracellular phosphoglycoprotein (MEPE) may be protected from proteolysis by a specific interaction with PHEX (phosphate regulating gene with homologies to endopeptidases on the X chromosome). The objective of our work was to determine whether PHEX impairment induces MEPE cleavage in dentin and the subsequent release of the C-terminal acidic serine- and aspartate-rich motif (ASARM) peptide, which is known to inhibit mineralization. By Western blot analysis, we explored dentin extracts from seven hypophosphatemic patients with mutations of the PHEX gene. A proteomic approach combining immunoprecipitation, surface-enhanced laser desorption/ionization-time of flight-mass spectrometry and matrix-assisted laser desorption ionization-time of flight analysis of the samples completed this exploration. This study shows a 4.1-kDa peptide containing the MEPE-derived ASARM peptide in hypophosphatemic samples. The presence of ASARM was less marked in patients treated with 1-hydroxylated vitamin D and phosphate during growth. Moreover, recombinant ASARM implanted in a rat pulp injury model disturbed the formation of the reparative dentin bridge. These results suggest that abnormal MEPE cleavage occurs when PHEX activity is deficient in humans, the ASARM peptide may be involved in the mineralization defects and the PHEX-MEPE interaction may be indirect, as ensuring a better phosphate and vitamin D environment to the mineralizing dentin prevents MEPE cleavage.
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Affiliation(s)
- Tchilalo Boukpessi
- Faculté de Chirurgie Dentaire, Université Paris Descartes, EA 2496, Montrouge, France
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Gattineni J, Baum M. Regulation of phosphate transport by fibroblast growth factor 23 (FGF23): implications for disorders of phosphate metabolism. Pediatr Nephrol 2010; 25:591-601. [PMID: 19669798 PMCID: PMC3151467 DOI: 10.1007/s00467-009-1273-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/16/2009] [Accepted: 06/17/2009] [Indexed: 01/08/2023]
Abstract
There are a number of hypophosphatemic disorders due to renal phosphate wasting that cannot be explained by elevated levels of parathyroid hormone. The circulating factors responsible for the phosphaturia have been designated as phosphatonins. Studies of patients with tumor-induced osteomalacia and other genetic diseases of phosphate metabolism have resulted in the identification of a number of hormones that regulate phosphate homeostasis, including matrix extracellular phosphoglycoprotein (MEPE), secreted frizzled-related protein 4 (sFRP-4), dentin matrix protein 1 (DMP1), fibroblast growth factor 7 (FGF7), fibroblast growth factor 23 (FGF23), and Klotho. Our understanding of the actions of these hypophosphatemic peptides has been enhanced by studies in mice either overexpressing or not expressing these hormones. This review focuses on FGF23 since its regulation is disordered in diseases that affect children, such as X-linked hypophosphatemia, autosomal dominant and recessive hypophosphatemic rickets as well as chronic kidney disease. Recent studies have shown that FGF23 is unique among the FGFs in its requirement for Klotho for receptor activation. Here, we also discuss new potentially clinically important data pointing to the receptor(s) that mediate the binding and action of FGF23 and Klotho.
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Affiliation(s)
- Jyothsna Gattineni
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas 75390-9063 TX, USA
| | - Michel Baum
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas 75390-9063 TX, USA. Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas 75235-9063 TX, USA
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Ramon I, Kleynen P, Body JJ, Karmali R. Fibroblast growth factor 23 and its role in phosphate homeostasis. Eur J Endocrinol 2010; 162:1-10. [PMID: 19776202 DOI: 10.1530/eje-09-0597] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Phosphate homeostasis is complex and incompletely understood. The identification of different factors involved in the regulation of phosphate balance, also called phosphatonins, has largely changed our view on the regulation of phosphate homeostasis. The active role of bone has been demonstrated clearly. Currently, maintaining phosphate homeostasis is considered the result of a complex network of endocrine feedback loops between parathyroid gland, kidney, and bone. This review describes current knowledge on fibroblast growth factor 23, which is one of the best studied phosphatonins.
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Affiliation(s)
- Isolde Ramon
- Department of Internal Medicine-Endocrinology, Brugmann University Hospital, Free University of Brussels, Brussels, Belgium.
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Bardet C, Delgado S, Sire JY. MEPE evolution in mammals reveals regions and residues of prime functional importance. Cell Mol Life Sci 2010; 67:305-20. [PMID: 19924383 PMCID: PMC11115541 DOI: 10.1007/s00018-009-0185-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 10/13/2009] [Accepted: 10/14/2009] [Indexed: 01/17/2023]
Abstract
In mammals, the matrix extracellular phosphoglycoprotein (MEPE) is known to activate osteogenesis and mineralization via a particular region called dentonin, and to inhibit mineralization via its ASARM (acidic serine-aspartate rich MEPE-associated motif) peptide that also plays a role in phosphatemia regulation. In order to understand MEPE evolution in mammals, and particularly that of its functional regions, we conducted an evolutionary analysis based on the study of selective pressures. Using 37 mammalian sequences we: (1) confirmed the presence of an additional coding exon in most placentals; (2) highlighted several conserved residues and regions that could have important functions; (3) found that dentonin function was recruited in a placental ancestor; and (4) revealed that ASARM function was present earlier, pushing the recruitment of MEPE deep into amniote origins. Our data indicate that MEPE was involved in various functions (bone and eggshell mineralization) prior to acquiring those currently known in placental mammals.
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Affiliation(s)
- Claire Bardet
- UMR 7138, Equipe “Evolution & Développement du Squelette” Université Paris 6, Paris, France
| | - Sidney Delgado
- UMR 7138, Equipe “Evolution & Développement du Squelette” Université Paris 6, Paris, France
| | - Jean-Yves Sire
- UMR 7138, Equipe “Evolution & Développement du Squelette” Université Paris 6, Paris, France
- UMR 7138, Université Pierre et Marie Curie-Paris 6, Case 05, 7 Quai St-Bernard, 75005 Paris, France
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