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Godse R, Mcgettigan S, Schuchter LM, Ellebrecht CT, Chu EY. Vogt-Koyanagi-Harada-like syndrome in the setting of combined anti-PD1/anti-CTLA4 therapy. Clin Exp Dermatol 2021; 46:1111-1112. [PMID: 33846999 DOI: 10.1111/ced.14640] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/17/2021] [Accepted: 03/08/2021] [Indexed: 11/28/2022]
Affiliation(s)
- R Godse
- Department of Dermatology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - S Mcgettigan
- Division of Haematology/Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - L M Schuchter
- Division of Haematology/Oncology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - C T Ellebrecht
- Department of Dermatology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - E Y Chu
- Department of Dermatology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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2
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Nagasaki A, Nagasaki K, Chu EY, Kear BD, Tadesse WD, Ferebee SE, Li L, Foster BL, Somerman MJ. Ablation of Pyrophosphate Regulators Promotes Periodontal Regeneration. J Dent Res 2020; 100:639-647. [PMID: 33356859 DOI: 10.1177/0022034520981854] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Biomineralization is regulated by inorganic pyrophosphate (PPi), a potent physiological inhibitor of hydroxyapatite crystal growth. Progressive ankylosis protein (ANK) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) act to increase local extracellular levels of PPi, inhibiting mineralization. The periodontal complex includes 2 mineralized tissues, cementum and alveolar bone (AB), both essential for tooth attachment. Previous studies demonstrated that loss of function of ANK or ENPP1 (reducing PPi) resulted in increased cementum formation, suggesting PPi metabolism may be a target for periodontal regenerative therapies. To compare the effects of genetic ablation of Ank, Enpp1, and both factors concurrently on cementum and AB regeneration, mandibular fenestration defects were created in Ank knockout (Ank KO), Enpp1 mutant (Enpp1asj/asj), and double KO (dKO) mice. Genetic ablation of Ank, Enpp1, or both factors increased cementum regeneration compared to controls at postoperative days (PODs) 15 and 30 (Ank KO: 8-fold, 3-fold; Enpp1asj/asj: 7-fold, 3-fold; dKO: 11-fold, 4-fold, respectively) associated with increased fluorochrome labeling and expression of mineralized tissue markers, dentin matrix protein 1 (Dmp1/DMP1), osteopontin (Spp1/OPN), and bone sialoprotein (Ibsp/BSP). Furthermore, dKO mice featured increased cementum thickness compared to single KOs at POD15 and Ank KO at POD30. No differences were noted in AB volume between genotypes, but osteoblast/osteocyte markers were increased in all KOs, partially mineralized osteoid volume was increased in dKO versus controls at POD15 (3-fold), and mineral density was decreased in Enpp1asj/asj and dKOs at POD30 (6% and 9%, respectively). Increased numbers of osteoclasts were present in regenerated AB of all KOs versus controls. These preclinical studies suggest PPi modulation as a potential and novel approach for cementum regeneration, particularly targeting ENPP1 and/or ANK. Differences in cementum and AB regeneration in response to reduced PPi conditions highlight the need to consider tissue-specific responses in strategies targeting regeneration of the entire periodontal complex.
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Affiliation(s)
- A Nagasaki
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - K Nagasaki
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - E Y Chu
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - B D Kear
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - W D Tadesse
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - S E Ferebee
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - L Li
- Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - B L Foster
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M J Somerman
- Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
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3
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Chu EY, Vo TD, Chavez MB, Nagasaki A, Mertz EL, Nociti FH, Aitken SF, Kavanagh D, Zimmerman K, Li X, Stabach PR, Braddock DT, Millán JL, Foster BL, Somerman MJ. Genetic and pharmacologic modulation of cementogenesis via pyrophosphate regulators. Bone 2020; 136:115329. [PMID: 32224162 PMCID: PMC7482720 DOI: 10.1016/j.bone.2020.115329] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 11/27/2022]
Abstract
Pyrophosphate (PPi) serves as a potent and physiologically important regulator of mineralization, with systemic and local concentrations determined by several key regulators, including: tissue-nonspecific alkaline phosphatase (ALPL gene; TNAP protein), the progressive ankylosis protein (ANKH; ANK), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1; ENPP1). Results to date have indicated important roles for PPi in cementum formation, and we addressed several gaps in knowledge by employing genetically edited mouse models where PPi metabolism was disrupted and pharmacologically modulating PPi in a PPi-deficient mouse model. We demonstrate that acellular cementum growth is inversely proportional to PPi levels, with reduced cementum in Alpl KO (increased PPi levels) mice and excess cementum in Ank KO mice (decreased PPi levels). Moreover, simultaneous ablation of Alpl and Ank results in reestablishment of functional cementum in dKO mice. Additional reduction of PPi by dual deletion of Ank and Enpp1 does not further increase cementogenesis, and PDL space is maintained in part through bone modeling/remodeling by osteoclasts. Our results provide insights into cementum formation and expand our knowledge of how PPi regulates cementum. We also demonstrate for the first time that pharmacologic manipulation of PPi through an ENPP1-Fc fusion protein can regulate cementum growth, supporting therapeutic interventions targeting PPi metabolism.
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Affiliation(s)
- E Y Chu
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.
| | - T D Vo
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M B Chavez
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - A Nagasaki
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - E L Mertz
- National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
| | - F H Nociti
- Department of Prosthodontics & Periodontics, State University of Campinas, Piracicaba Dental School, Piracicaba, São Paulo, Brazil
| | - S F Aitken
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - D Kavanagh
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - K Zimmerman
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - X Li
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - P R Stabach
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - D T Braddock
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - J L Millán
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - B L Foster
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M J Somerman
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
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4
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Zhang H, Chavez MB, Kolli TN, Tan MH, Fong H, Chu EY, Li Y, Ren X, Watanabe K, Kim DG, Foster BL. Dentoalveolar Defects in the Hyp Mouse Model of X-linked Hypophosphatemia. J Dent Res 2020; 99:419-428. [PMID: 31977267 DOI: 10.1177/0022034520901719] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in PHEX cause X-linked hypophosphatemia (XLH), a form of hypophosphatemic rickets. Hyp (Phex mutant) mice recapitulate the XLH phenotype. Dental disorders are prevalent in individuals with XLH; however, underlying dentoalveolar defects remain incompletely understood. We analyzed Hyp mouse dentoalveolar defects at 42 and 90 d postnatal to comparatively define effects of XLH on dental formation and function. Phex mRNA was expressed by odontoblasts (dentin), osteocytes (bone), and cementocytes (cellular cementum) in wild-type (WT) mice. Enamel density was unaffected, though enamel volume was significantly reduced in Hyp mice. Dentin defects in Hyp molars were indicated histologically by wide predentin, thin dentin, and extensive interglobular dentin, confirming micro-computed tomography (micro-CT) findings of reduced dentin volume and density. Acellular cementum was thin and showed periodontal ligament detachment. Mechanical testing indicated dramatically altered periodontal mechanical properties in Hyp versus WT mice. Hyp mandibles demonstrated expanded alveolar bone with accumulation of osteoid, and micro-CT confirmed decreased bone volume fraction and alveolar bone density. Cellular cementum area was significantly increased in Hyp versus WT molars owing to accumulation of hypomineralized cementoid. Histology, scanning electron microscopy, and nanoindentation revealed hypomineralized "halos" surrounding Hyp cementocyte and osteocyte lacunae. Three-dimensional micro-CT analyses confirmed larger cementocyte/osteocyte lacunae and significantly reduced perilacunar mineral density. While long bone and alveolar bone osteocytes in Hyp mice overexpressed fibroblast growth factor 23 (Fgf23), its expression in molars was much lower, with cementocyte Fgf23 expression particularly low. Expression and distribution of other selected markers were disturbed in Hyp versus WT long bone, alveolar bone, and cementum, including osteocyte/cementocyte marker dentin matrix protein 1 (Dmp1). This study reports for the first time a quantitative analysis of the Hyp mouse dentoalveolar phenotype, including all mineralized tissues. Novel insights into cellular cementum provide evidence for a role for cementocytes in perilacunar mineralization and cementum biology.
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Affiliation(s)
- H Zhang
- Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, USA
| | - M B Chavez
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - T N Kolli
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M H Tan
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - H Fong
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
| | - E Y Chu
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Y Li
- Department of Oral Maxillofacial Surgery, West China School of Stomatology, Sichuan University, Chengdu, China
| | - X Ren
- Department of Periodontics, School of Stomatology, Shanxi Medical University, Taiyuan, China
| | - K Watanabe
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - D G Kim
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - B L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
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5
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Wolf M, Ao M, Chavez MB, Kolli TN, Thumbigere-Math V, Becker K, Chu EY, Jäger A, Somerman MJ, Foster BL. Reduced Orthodontic Tooth Movement in Enpp1 Mutant Mice with Hypercementosis. J Dent Res 2018. [PMID: 29533727 DOI: 10.1177/0022034518759295] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Previous studies revealed that cementum formation is tightly regulated by inorganic pyrophosphate (PPi), a mineralization inhibitor. Local PPi concentrations are determined by regulators, including ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which increases PPi concentrations by adenosine triphosphate hydrolysis. Orthodontic forces stimulate alveolar bone remodelling, leading to orthodontic tooth movement (OTM). To better understand how disturbed mineral metabolism and the resulting altered periodontal structures affect OTM, we employed Enpp1 mutant mice that feature reduced PPi and increased cervical cementum in a model of OTM induced by a stretched closed-coil spring ligated between the maxillary left first molar and maxillary incisors. We analyzed tooth movement, osteoclast/odontoclast response, and tooth root resorption by micro-computed tomography, histology, histomorphometry, and immunohistochemistry. Preoperatively, we noted an altered periodontium in Enpp1 mutant mice, with significantly increased periodontal ligament (PDL) volume and thickness, as well as increased PDL-bone/tooth root surface area, compared to wild-type (WT) controls. After 11 d of orthodontic treatment, Enpp1 mutant mice displayed 38% reduced tooth movement versus WT mice. Molar roots in Enpp1 mutant mice exhibited less change in PDL width in compression and tension zones compared to WT mice. Root resorption was noted in both groups with no difference in average depths, but resorption lacunae in Enpp1 mutant mice were almost entirely limited to cementum, with 150% increased cementum resorption and 92% decreased dentin resorption. Osteoclast/odontoclast cells were reduced by 64% in Enpp1 mutant mice, with a predominance of tartrate-resistant acid phosphatase (TRAP)-positive cells on root surfaces, compared to WT mice. Increased numbers of TRAP-positive cells on root surfaces were associated with robust immunolocalization of osteopontin (OPN) and receptor-activator of NF-κB ligand (RANKL). Collectively, reduced response to orthodontic forces, decreased tooth movement, and altered osteoclast/odontoclast distribution suggests Enpp1 loss of function has direct effects on clastic function/recruitment and/or indirect effects on periodontal remodeling via altered periodontal structure or tissue mineralization.
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Affiliation(s)
- M Wolf
- 1 Department of Orthodontics, Aachen University, Aachen, Germany.,2 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M Ao
- 2 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M B Chavez
- 3 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - T N Kolli
- 3 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - V Thumbigere-Math
- 2 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.,4 Division of Periodontics, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - K Becker
- 5 Department of Orthodontics, Universitätsklinikum Düsseldorf, Düsseldorf, Germany
| | - E Y Chu
- 2 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - A Jäger
- 6 Department of Orthodontics, University of Bonn, Bonn, Germany
| | - M J Somerman
- 2 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - B L Foster
- 3 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
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6
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Foster BL, Ao M, Salmon CR, Chavez MB, Kolli TN, Tran AB, Chu EY, Kantovitz KR, Yadav M, Narisawa S, Millán JL, Nociti FH, Somerman MJ. Osteopontin regulates dentin and alveolar bone development and mineralization. Bone 2018; 107:196-207. [PMID: 29313816 PMCID: PMC5803363 DOI: 10.1016/j.bone.2017.12.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 11/09/2017] [Accepted: 12/03/2017] [Indexed: 01/09/2023]
Abstract
The periodontal complex is essential for tooth attachment and function and includes the mineralized tissues, cementum and alveolar bone, separated by the unmineralized periodontal ligament (PDL). To gain insights into factors regulating cementum-PDL and bone-PDL borders and protecting against ectopic calcification within the PDL, we employed a proteomic approach to analyze PDL tissue from progressive ankylosis knock-out (Ank-/-) mice, featuring reduced PPi, rapid cementogenesis, and excessive acellular cementum. Using this approach, we identified the matrix protein osteopontin (Spp1/OPN) as an elevated factor of interest in Ank-/- mouse molar PDL. We studied the role of OPN in dental and periodontal development and function. During tooth development in wild-type (WT) mice, Spp1 mRNA was transiently expressed by cementoblasts and strongly by alveolar bone osteoblasts. Developmental analysis from 14 to 240days postnatal (dpn) indicated normal histological structures in Spp1-/- comparable to WT control mice. Microcomputed tomography (micro-CT) analysis at 30 and 90dpn revealed significantly increased volumes and tissue mineral densities of Spp1-/- mouse dentin and alveolar bone, while pulp and PDL volumes were decreased and tissue densities were increased. However, acellular cementum growth was unaltered in Spp1-/- mice. Quantitative PCR of periodontal-derived mRNA failed to identify potential local compensators influencing cementum in Spp1-/- vs. WT mice at 26dpn. We genetically deleted Spp1 on the Ank-/- mouse background to determine whether increased Spp1/OPN was regulating periodontal tissues when the PDL space is challenged by hypercementosis in Ank-/- mice. Ank-/-; Spp1-/- double deficient mice did not exhibit greater hypercementosis than that in Ank-/- mice. Based on these data, we conclude that OPN has a non-redundant role regulating formation and mineralization of dentin and bone, influences tissue properties of PDL and pulp, but does not control acellular cementum apposition. These findings may inform therapies targeted at controlling soft tissue calcification.
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Affiliation(s)
- B L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA.
| | - M Ao
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - C R Salmon
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas, São Paulo, Brazil
| | - M B Chavez
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - T N Kolli
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - A B Tran
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - E Y Chu
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - K R Kantovitz
- Department of Dental Materials, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil
| | - M Yadav
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Research Institute, La Jolla, CA, USA
| | - S Narisawa
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Research Institute, La Jolla, CA, USA
| | - J L Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Research Institute, La Jolla, CA, USA
| | - F H Nociti
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas, São Paulo, Brazil
| | - M J Somerman
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
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7
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Thumbigere-Math V, Alqadi A, Chalmers NI, Chavez MB, Chu EY, Collins MT, Ferreira CR, FitzGerald K, Gafni RI, Gahl WA, Hsu KS, Ramnitz MS, Somerman MJ, Ziegler SG, Foster BL. Hypercementosis Associated with ENPP1 Mutations and GACI. J Dent Res 2017; 97:432-441. [PMID: 29244957 DOI: 10.1177/0022034517744773] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mineralization of bones and teeth is tightly regulated by levels of extracellular inorganic phosphate (Pi) and pyrophosphate (PPi). Three regulators that control pericellular concentrations of Pi and PPi include tissue-nonspecific alkaline phosphatase (TNAP), progressive ankylosis protein (ANK), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Inactivation of these factors results in mineralization disorders affecting teeth and their supporting structures. This study for the first time analyzed the effect of decreased PPi on dental development in individuals with generalized arterial calcification of infancy (GACI) due to loss-of-function mutations in the ENPP1 gene. Four of the 5 subjects reported a history of infraocclusion, overretained primary teeth, ankylosis, and/or slow orthodontic tooth movement, suggesting altered mineral metabolism contributing to disrupted tooth movement and exfoliation. All subjects had radiographic evidence of unusually protruding cervical root morphology in primary and/or secondary dentitions. High-resolution micro-computed tomography (micro-CT) analyses of extracted primary teeth from 3 GACI subjects revealed 4-fold increased cervical cementum thickness ( P = 0.00007) and a 23% increase in cementum density ( P = 0.009) compared to age-matched healthy control teeth. There were no differences in enamel and dentin densities between GACI and control teeth. Histology revealed dramatically expanded cervical cementum in GACI teeth, including cementocyte-like cells and unusual patterns of cementum resorption and repair. Micro-CT analysis of Enpp1 mutant mouse molars revealed 4-fold increased acellular cementum thickness ( P = 0.002) and 5-fold increased cementum volume ( P = 0.002), with no changes in enamel or dentin. Immunohistochemistry identified elevated ENPP1 expression in cementoblasts of human and mouse control teeth. Collectively, these findings reveal a novel dental phenotype in GACI and identify ENPP1 genetic mutations associated with hypercementosis. The sensitivity of cementum to reduced PPi levels in both human and mouse teeth establishes this as a well-conserved and fundamental biological process directing cementogenesis across species (ClinicalTrials.gov NCT00369421).
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Affiliation(s)
- V Thumbigere-Math
- 1 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.,2 Division of Periodontics, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - A Alqadi
- 3 Division of Public and Child Dental Health, Dublin Dental University Hospital, Dublin, Ireland
| | - N I Chalmers
- 4 Analytics and Publication, DentaQuest Institute, Westborough, MA, USA
| | - M B Chavez
- 5 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - E Y Chu
- 1 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M T Collins
- 6 Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - C R Ferreira
- 7 National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD, USA.,8 Division of Genetics and Metabolism, Children's National Health System, Washington, DC, USA
| | - K FitzGerald
- 3 Division of Public and Child Dental Health, Dublin Dental University Hospital, Dublin, Ireland.,9 Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - R I Gafni
- 6 Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - W A Gahl
- 7 National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD, USA
| | - K S Hsu
- 7 National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M S Ramnitz
- 6 Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M J Somerman
- 1 National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - S G Ziegler
- 10 Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - B L Foster
- 5 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
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8
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Ao M, Chavez MB, Chu EY, Hemstreet KC, Yin Y, Yadav MC, Millán JL, Fisher LW, Goldberg HA, Somerman MJ, Foster BL. Overlapping functions of bone sialoprotein and pyrophosphate regulators in directing cementogenesis. Bone 2017; 105:134-147. [PMID: 28866368 PMCID: PMC5730356 DOI: 10.1016/j.bone.2017.08.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 12/19/2022]
Abstract
Although acellular cementum is essential for tooth attachment, factors directing its development and regeneration remain poorly understood. Inorganic pyrophosphate (PPi), a mineralization inhibitor, is a key regulator of cementum formation: tissue-nonspecific alkaline phosphatase (Alpl/TNAP) null mice (increased PPi) feature deficient cementum, while progressive ankylosis protein (Ank/ANK) null mice (decreased PPi) feature increased cementum. Bone sialoprotein (Bsp/BSP) and osteopontin (Spp1/OPN) are multifunctional extracellular matrix components of cementum proposed to have direct and indirect effects on cell activities and mineralization. Studies on dentoalveolar development of Bsp knockout (Bsp-/-) mice revealed severely reduced acellular cementum, however underlying mechanisms remain unclear. The similarity in defective cementum phenotypes between Bsp-/- mice and Alpl-/- mice (the latter featuring elevated PPi and OPN), prompted us to examine whether BSP is operating by modulating PPi-associated genes. Genetic ablation of Bsp caused a 2-fold increase in circulating PPi, altered mRNA expression of Alpl, Spp1, and Ank, and increased OPN protein in the periodontia. Generation of a Bsp knock-out (KO) cementoblast cell line revealed significantly decreased mineralization capacity, 50% increased PPi in culture media, and increased Spp1 and Ank mRNA expression. While addition of 2μg/ml recombinant BSP altered Spp1, Ank, and Enpp1 expression in cementoblasts, changes resulting from this dose were not dependent on the integrin-binding RGD motif or MAPK/ERK signaling pathway. Decreasing PPi by genetic ablation of Ank on the Bsp-/- mouse background reestablished cementum formation, allowing >3-fold increased acellular cementum volume compared to wild-type (WT). However, deleting Ank did not fully compensate for the absence of BSP. Bsp-/-; Ank-/- double-deficient mice exhibited mean 20-27% reduced cementum thickness and volume compared to Ank-/- mice. From these data, we conclude that the perturbations in PPi metabolism are not solely driving the cementum pathology in Bsp-/- mice, and that PPi is more potent than BSP as a cementum regulator, as shown by the ability to override loss of BSP by lowering PPi. We propose that BSP and PPi work in concert to direct mineralization in cementum and likely other mineralized tissues.
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Affiliation(s)
- M Ao
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M B Chavez
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - E Y Chu
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - K C Hemstreet
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Y Yin
- National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - M C Yadav
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - J L Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - L W Fisher
- National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), Bethesda, MD, USA
| | - H A Goldberg
- Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - M J Somerman
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA
| | - B L Foster
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA.
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Parada-Sanchez MT, Chu EY, Cox LL, Undurty SS, Standley JM, Murray JC, Cox TC. Disrupted IRF6-NME1/2 Complexes as a Cause of Cleft Lip/Palate. J Dent Res 2017; 96:1330-1338. [PMID: 28767310 DOI: 10.1177/0022034517723615] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mutations and common polymorphisms in interferon regulatory factor 6 ( IRF6) are associated with both syndromic and nonsyndromic forms of cleft lip/palate (CLP). To date, much of the focus on this transcription factor has been on identifying its direct targets and the gene regulatory network in which it operates. Notably, however, IRF6 is found predominantly in the cytoplasm, with its import into the nucleus tightly regulated like other members of the IRF family. To provide further insight into the role of IRF6 in the pathogenesis of CLP, we sought to identify direct IRF6 protein interactors using a combination of yeast 2-hybrid screens and co-immunoprecipitation assays. Using this approach, we identified NME1 and NME2, well-known regulators of Rho-type GTPases, E-cadherin endocytosis, and epithelial junctional remodeling, as bona fide IRF6 partner proteins. The NME proteins co-localize with IRF6 in the cytoplasm of primary palatal epithelial cells in vivo, and their interaction with IRF6 is significantly enhanced by phosphorylation of key serine residues in the IRF6 C-terminus. Furthermore, CLP associated IRF6 missense mutations disrupt the ability of IRF6 to bind the NME proteins and result in elevated activation of Rac1 and RhoA, compared to wild-type IRF6, when ectopically expressed in 293T epithelial cells. Significantly, we also report the identification of 2 unique missense mutations in the NME proteins in patients with CLP (NME1 R18Q in an IRF6 and GRHL3 mutation-negative patient with van der Woude syndrome and NME2 G71V in a patient with nonsyndromic CLP). Both variants disrupted the ability of the respective proteins to interact with IRF6. The data presented suggest an important role for cytoplasmic IRF6 in regulating the availability or localization of the NME1/2 complex and thus the dynamic behavior of epithelia during lip/palate development.
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Affiliation(s)
- M T Parada-Sanchez
- 1 School of Dentistry, Universidad de Antioquia, Medellín, Colombia.,2 Departments of Oral Health Sciences, University of Washington, Seattle, WA, USA
| | - E Y Chu
- 2 Departments of Oral Health Sciences, University of Washington, Seattle, WA, USA
| | - L L Cox
- 3 Departments of Pediatrics (Craniofacial Medicine), University of Washington, Seattle, WA, USA.,4 Center for Developmental Biology & Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - S S Undurty
- 5 Division of Neonatology, Department of Pediatrics, University of Iowa, Iowa City, IA, USA
| | - J M Standley
- 5 Division of Neonatology, Department of Pediatrics, University of Iowa, Iowa City, IA, USA
| | - J C Murray
- 5 Division of Neonatology, Department of Pediatrics, University of Iowa, Iowa City, IA, USA
| | - T C Cox
- 3 Departments of Pediatrics (Craniofacial Medicine), University of Washington, Seattle, WA, USA.,4 Center for Developmental Biology & Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA.,6 Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC, Australia
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10
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Sargen MR, Merrill SL, Chu EY, Nathanson KL. CDKN2A mutations with p14 loss predisposing to multiple nerve sheath tumours, melanoma, dysplastic naevi and internal malignancies: a case series and review of the literature. Br J Dermatol 2016; 175:785-9. [PMID: 26876133 DOI: 10.1111/bjd.14485] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2016] [Indexed: 12/20/2022]
Abstract
An inherited germline mutation in CDKN2A is the most common cause of familial atypical multiple mole melanoma (FAMMM) syndrome. Although it is well known that CDKN2A mutations confer an increased risk for melanoma and pancreatic carcinoma, the association with an increased risk for nerve sheath tumours and other tumour types is under-recognized. We report a family with a missense mutation (c.151-1G>C) at the acceptor splice site of intron 1 of CDKN2A, resulting in loss of function of both tumour suppressor proteins p16(INK) (4) and p14(ARF) . This mutation is associated with a clinical phenotype of FAMMM syndrome in which patients develop numerous benign and malignant mutations, brain tumours, sarcomas and other solid tumours, in addition to melanoma and dysplastic naevi. Our proband initially presented with multiple nerve sheath tumours, leading to diagnostic confusion with Neurofibromatosis type 1. Loss of p14 expression results in increased MDM2-mediated degradation of the tumour suppressor protein p53, and predisposes mutation carriers to multiple benign and malignant neoplasms. This article highlights the importance of considering CDKN2A mutations in patients with dysplastic naevi, melanoma and multiple nerve sheath tumours, specifically those with histological features of both neurofibromas and schwannomas. We also present a discussion of medical management for patients with this high-risk cancer susceptibility syndrome.
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Affiliation(s)
- M R Sargen
- Department of Dermatology, Emory University School of Medicine, Atlanta, GA, 30322, U.S.A
| | - S L Merrill
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, U.S.A
| | - E Y Chu
- Department of Dermatology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, U.S.A
- Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, U.S.A
| | - K L Nathanson
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, U.S.A.
- Abramson Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, 19104, U.S.A.
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11
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Chu EY, Tamasas B, Fong H, Foster BL, LaCourse MR, Tran AB, Martin JF, Schutte BC, Somerman MJ, Cox TC. Full Spectrum of Postnatal Tooth Phenotypes in a Novel Irf6 Cleft Lip Model. J Dent Res 2016; 95:1265-73. [PMID: 27369589 DOI: 10.1177/0022034516656787] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Clefting of the lip, with or without palatal involvement (CLP), is associated with a higher incidence of developmental tooth abnormalities, including hypodontia and supernumerary teeth, aberrant crown and root morphologies, and enamel defects, although the underlying mechanistic link is poorly understood. As most CLP genes are expressed throughout the oral epithelium, the authors hypothesized that the expression of CLP genes may persist in the dental epithelium and thus, in addition to their earlier role in labiopalatine development, may play an important functional role in subsequent tooth patterning and amelogenesis. To address this, the authors generated a unique conditional knockout model involving the major CLP gene, Irf6, that overcomes the previously reported perinatal lethality to enable assessment of any posteruption dental phenotypes. A dental epithelium-specific Irf6 conditional knockout (Irf6-cKO) mouse was generated via a Pitx2-Cre driver line. Dental development was analyzed by microcomputed tomography, scanning electron microscopy, histology, immunohistochemistry, and quantitative polymerase chain reaction. Irf6-cKO mice displayed variable hypodontia, occasional supernumerary incisors and molars, as well as crown and root patterning anomalies, including peg-shaped first molars and taurodontic and C-shaped mandibular second molars. Enamel density was reduced in preeruption Irf6-cKO mice, and some shearing of enamel rods was noted in posteruption incisors. There was also rapid attrition of Irf6-cKO molars following eruption. Histologically, Irf6-cKO ameloblasts exhibited disturbances in adhesion and polarity, and delayed enamel formation was confirmed immunohistochemically. Altered structure of Hertwig's epithelial root sheath was also observed. These data support a role for IRF6 in tooth number, crown and root morphology and amelogenesis that is likely due to a functional role of Irf6 in organization and polarity of epithelial cell types. This data reinforce the notion that various isolated tooth defects could be considered part of the CLP spectrum in relatives of an affected individual.
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Affiliation(s)
- E Y Chu
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - B Tamasas
- Department of Oral Health Sciences, University of Washington, Seattle, WA, USA Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - H Fong
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA
| | - B L Foster
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M R LaCourse
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA
| | - A B Tran
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - J F Martin
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, and Texas Heart Institute, Houston, TX, USA
| | - B C Schutte
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - M J Somerman
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - T C Cox
- Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA, USA Division of Craniofacial Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA Department of Anatomy and Developmental Biology, Monash University, Clayton, Australia
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12
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Foster BL, Nagatomo KJ, Bamashmous SO, Tompkins KA, Fong H, Dunn D, Chu EY, Guenther C, Kingsley DM, Rutherford RB, Somerman MJ. The progressive ankylosis protein regulates cementum apposition and extracellular matrix composition. Cells Tissues Organs 2011; 194:382-405. [PMID: 21389671 DOI: 10.1159/000323457] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND/AIMS Tooth root cementum is sensitive to modulation of inorganic pyrophosphate (PP(i)), an inhibitor of hydroxyapatite precipitation. Factors increasing PP(i) include progressive ankylosis protein (ANK) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) while tissue nonspecific alkaline phosphatase hydrolyzes PP(i). Studies here aimed to define the role of ANK in root and cementum by analyzing tooth development in Ank knock-out (KO) mice versus wild type. MATERIALS AND METHODS Periodontal development in KO versus control mice was analyzed by histology, histomorphometry, immunohistochemistry, in situ hybridization, electron microscopy, and nanoindentation. Cementoblast cultures were used in vitro to provide mechanistic underpinnings for PP(i) modulation of cell function. RESULTS Over the course of root development, Ank KO cervical cementum became 8- to 12-fold thicker than control cervical cementum. Periodontal ligament width was maintained and other dentoalveolar tissues, including apical cementum, were unaltered. Cervical cementum uncharacteristically included numerous cells, from rapid cementogenesis. Ank KO increased osteopontin and dentin matrix protein 1 gene and protein expression, and markedly increased NPP1 protein expression in cementoblasts but not in other cell types. Conditional ablation of Ank in joints and periodontia confirmed a local role for ANK in cementogenesis. In vitro studies employing cementoblasts indicated that Ank and Enpp1 mRNA levels increased in step with mineral nodule formation, supporting a role for these factors in regulation of cementum matrix mineralization. CONCLUSION ANK, by modulating local PP(i), controls cervical cementum apposition and extracellular matrix. Loss of ANK created a local environment conducive to rapid cementogenesis; therefore, approaches modulating PP(i) in periodontal tissues have potential to promote cementum regeneration.
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Affiliation(s)
- B L Foster
- Department of Periodontics, University of Washington School of Dentistry, Seattle, Wash. 98195, USA.
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Chu EY, Fong H, Blethen FA, Tompkins KA, Foster BL, Yeh KD, Nagatomo KJ, Matsa-Dunn D, Sitara D, Lanske B, Rutherford RB, Somerman MJ. Ablation of systemic phosphate-regulating gene fibroblast growth factor 23 (Fgf23) compromises the dentoalveolar complex. Anat Rec (Hoboken) 2010; 293:1214-26. [PMID: 20583265 DOI: 10.1002/ar.21152] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Fibroblast growth factor-23 (FGF23) is a hormone that modulates circulating phosphate (P(i)) levels by controlling P(i) reabsorption from the kidneys. When FGF23 levels are deficient, as in tumoral calcinosis patients, hyperphosphatemia ensues. We show here in a murine model that Fgf23 ablation disrupted morphology and protein expression within the dentoalveolar complex. Ectopic matrix formation in pulp chambers, odontoblast layer disruption, narrowing of periodontal ligament space, and alteration of cementum structure were observed in histological and electron microscopy sections. Because serum P(i) levels are dramatically elevated in Fgf23(-/-), we assayed for apoptosis and expression of members from the small integrin-binding ligand, N-linked glycoprotein (SIBLING) family, both of which are sensitive to elevated P(i) in vitro. Unlike X-linked hypophosphatemic (Hyp) and wild-type (WT) specimens, numerous apoptotic osteocytes and osteoblasts were detected in Fgf23(-/-) specimens. Further, in comparison to Hyp and WT samples, decreased bone sialoprotein and elevated dentin matrix protein-1 protein levels were observed in cementum of Fgf23(-/-) mice. Additional dentin-associated proteins, such as dentin sialoprotein and dentin phosphoprotein, exhibited altered localization in both Fgf23(-/-) and Hyp samples. Based on these results, we propose that FGF23 and (P(i)) homeostasis play a significant role in maintenance of the dentoalveolar complex.
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Affiliation(s)
- E Y Chu
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, Washington, USA
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Fong H, Chu EY, Tompkins KA, Foster BL, Sitara D, Lanske B, Somerman MJ. Aberrant cementum phenotype associated with the hypophosphatemic hyp mouse. J Periodontol 2009; 80:1348-54. [PMID: 19656036 DOI: 10.1902/jop.2009.090129] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Cementogenesis is sensitive to altered local phosphate levels; thus, we hypothesized a cementum phenotype, likely of decreased formation, would be present in the teeth of X-linked hypophosphatemic (Hyp) mice. Mutations in the phosphate-regulating gene with homologies to endopeptidases on the X chromosome (Phex) cause X-linked hypophosphatemia, characterized by rickets, osteomalacia, and hypomineralized dentin formation, a phenotype recapitulated in the Hyp mouse homolog. Here, we report a developmental study of tooth root formation in Hyp mouse molars, focusing on dentin and cementum. METHODS Light and transmission electron microscopy were used to study molar tissues from wild-type (WT) and Hyp mice. Demineralized and hematoxylin and eosin-stained tissues at developmental stages 23 to 96 days postcoital (dpc) were examined by light microscopy. Immunohistochemistry methods were used to detect bone sialoprotein (BSP) distribution in Hyp and WT mouse molar tissues, and transmission electron microscopy was used to study similar molar tissues in the non-demineralized state. RESULTS Dentin in Hyp mice exhibited mineralization defects by 33 dpc, as expected, but this defect was partially corrected by 96 dpc. In support of our hypothesis, a cementum phenotype was detected using a combination of immunohistochemistry and transmission electron microscopy, which included thinner BSP-positive staining within the cementum, discontinuous mineralization, and a globular appearance compared to WT controls. CONCLUSION Mutations in the phosphate-regulating Phex gene of the Hyp mouse resulted in defective cementum development.
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Affiliation(s)
- H Fong
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA.
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Abstract
Progression of the cell cycle and control of apoptosis (programmed cell death) are thought to be intimately linked processes, acting to preserve homeostasis and developmental morphogenesis. Although proteins that regulate apoptosis have been implicated in restraining cell-cycle entry and controlling ploidy (chromosome number), the effector molecules at the interface between cell proliferation and cell survival have remained elusive. Here we show that a new inhibitor of apoptosis (IAP) protein, survivin, is expressed in the G2/M phase of the cell cycle in a cycle-regulated manner. At the beginning of mitosis, survivin associates with microtubules of the mitotic spindle in a specific and saturable reaction that is regulated by microtubule dynamics. Disruption of survivin-microtubule interactions results in loss of survivin's anti-apoptosis function and increased caspase-3 activity, a mechanism involved in cell death, during mitosis. These results indicate that survivin may counteract a default induction of apoptosis in G2/M phase. The overexpression of survivin in cancer may overcome this apoptotic checkpoint and favour aberrant progression of transformed cells through mitosis.
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Affiliation(s)
- F Li
- Boyer Center for Molecular Medicine, Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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17
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Huang SP, Chu EY. Inhibitory Effect of Watermelon Mosaic Virus on Meloidogyne javanica (Treub) Chitwood Infecting Cucurbita pepo L. J Nematol 1984; 16:109-112. [PMID: 19295884 PMCID: PMC2618342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
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