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Al-Hakeim HK, Alhillawi ZH. Effect of serum fibroblast growth factor receptor 2 and CAPS proteins on calcium status in β-thalassaemia major patients who are free from overt inflammation. Growth Factors 2018; 36:178-185. [PMID: 30375242 DOI: 10.1080/08977194.2018.1520707] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Bone disorders and disturbed calcium (Ca) homeostasis are common disorders in β-thalassaemia major (β-TM). In the present study, two bone related markers are studied in β-TM patients with negative C-reactive protein for the first time; fibroblast growth factor receptor 2 (FGFR2) and CAPS protein. Another goal is to estimate the correlation between the recent parameters and bone biomaterials as a function of iron status parameters in β-TM patients. The results revealed that, in patients with β-TM serum FGFR2, CAPS, alkaline phosphatase (ALP) and Mg significantly increased while serum Ca levels were low as compared with controls. Ca status is correlated with iron overload in β-TM. A significant correlation was present between CAPS and FGFR2. In conclusion, FGFR2 and CAPS associated with Ca status and subsequent bone disturbances in β-TM patients. Their level can be predicted from the equation: CAPS =0.001ALP +0.48FGFR2-1.26Ca - 3.95Pi +12.76 with acceptable applicability.
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Wang X, Qi H, Wang Q, Zhu Y, Wang X, Jin M, Tan Q, Huang Q, Xu W, Li X, Kuang L, Tang Y, Du X, Chen D, Chen L. FGFR3/fibroblast growth factor receptor 3 inhibits autophagy through decreasing the ATG12-ATG5 conjugate, leading to the delay of cartilage development in achondroplasia. Autophagy 2015; 11:1998-2013. [PMID: 26491898 PMCID: PMC4824585 DOI: 10.1080/15548627.2015.1091551] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 08/26/2015] [Accepted: 09/03/2015] [Indexed: 01/15/2023] Open
Abstract
FGFR3 (fibroblast growth factor receptor 3) is a negative regulator of endochondral ossification. Gain-of-function mutations in FGFR3 are responsible for achondroplasia, the most common genetic form of dwarfism in humans. Autophagy, an evolutionarily conserved catabolic process, maintains chondrocyte viability in the growth plate under stress conditions, such as hypoxia and nutritional deficiencies. However, the role of autophagy and its underlying molecular mechanisms in achondroplasia remain elusive. In this study, we found activated FGFR3 signaling inhibited autophagic activity in chondrocytes, both in vivo and in vitro. By employing an embryonic bone culture system, we demonstrated that treatment with autophagy inhibitor 3-MA or chloroquine led to cartilage growth retardation, which mimics the effect of activated-FGFR3 signaling on chondrogenesis. Furthermore, we found that FGFR3 interacted with ATG12-ATG5 conjugate by binding to ATG5. More intriguingly, FGFR3 signaling was found to decrease the protein level of ATG12-ATG5 conjugate. Consistently, using in vitro chondrogenic differentiation assay system, we showed that the ATG12-ATG5 conjugate was essential for the viability and differentiation of chondrocytes. Transient transfection of ATG5 partially rescued FGFR3-mediated inhibition on chondrocyte viability and differentiation. Our findings reveal that FGFR3 inhibits the autophagic activity by decreasing the ATG12-ATG5 conjugate level, which may play an essential role in the pathogenesis of achondroplasia.
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Affiliation(s)
- Xiaofeng Wang
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Huabing Qi
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Quan Wang
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Ying Zhu
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Xianxing Wang
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Min Jin
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Qiaoyan Tan
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Qizhao Huang
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Wei Xu
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Xiaogang Li
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Liang Kuang
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Yubing Tang
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Xiaolan Du
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
| | - Di Chen
- Department of Biochemistry; Rush University Medical Center; Chicago, IL USA
| | - Lin Chen
- Center of Bone Metabolism and Repair (CBMR); Trauma Center; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing,China
- State Key Laboratory of Trauma; Burns and Combined Injury; Third Military Medical University; Chongqing, China
- Department of Rehabilitation Medicine; Institute of Surgery Research; Daping Hospital; Third Military Medical University; Chongqing, China
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Horakova D, Cela P, Krejci P, Balek L, Moravcova Balkova S, Matalova E, Buchtova M. Effect of FGFR inhibitors on chicken limb development. Dev Growth Differ 2014; 56:555-72. [DOI: 10.1111/dgd.12156] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 07/30/2014] [Accepted: 08/07/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Dana Horakova
- Department of Anatomy, Histology and Embryology; Faculty of Veterinary Medicine; University of Veterinary and Pharmaceutical Sciences; Brno Czech Republic
| | - Petra Cela
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Department of Animal Physiology and Immunology; Institute of Experimental Biology; Masaryk University; Brno Czech Republic
| | - Pavel Krejci
- Department of Animal Physiology and Immunology; Institute of Experimental Biology; Masaryk University; Brno Czech Republic
- Department of Biology; Faculty of Medicine; Masaryk University; Brno Czech Republic
| | - Lukas Balek
- Department of Animal Physiology and Immunology; Institute of Experimental Biology; Masaryk University; Brno Czech Republic
- Department of Biology; Faculty of Medicine; Masaryk University; Brno Czech Republic
| | - Simona Moravcova Balkova
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Clinic of Stomatology, St. Anne's Faculty Hospital and Faculty of Medicine; Masaryk University; Brno Czech Republic
| | - Eva Matalova
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Department of Physiology; Faculty of Veterinary Medicine; University of Veterinary and Pharmaceutical Sciences; Brno Czech Republic
| | - Marcela Buchtova
- Department of Anatomy, Histology and Embryology; Faculty of Veterinary Medicine; University of Veterinary and Pharmaceutical Sciences; Brno Czech Republic
- Institute of Animal Physiology and Genetics, v.v.i.; Academy of Sciences of the Czech Republic; Brno Czech Republic
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Wu S, Levenson A, Kharitonenkov A, De Luca F. Fibroblast growth factor 21 (FGF21) inhibits chondrocyte function and growth hormone action directly at the growth plate. J Biol Chem 2012; 287:26060-7. [PMID: 22696219 DOI: 10.1074/jbc.m112.343707] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fibroblast growth factor 21 (FGF21) modulates glucose and lipid metabolism during fasting. In addition, previous evidence indicates that increased expression of FGF21 during chronic food restriction is associated with reduced bone growth and growth hormone (GH) insensitivity. In light of the inhibitory effects on growth plate chondrogenesis mediated by other FGFs, we hypothesized that FGF21 causes growth inhibition by acting directly at the long bones' growth plate. We first demonstrated the expression of FGF21, FGFR1 and FGFR3 (two receptors known to be activated by FGF21) and β-klotho (a co-receptor required for the FGF21-mediated receptor binding and activation) in fetal and 3-week-old mouse growth plate chondrocytes. We then cultured mouse growth plate chondrocytes in the presence of graded concentrations of rhFGF21 (0.01-10 μg/ml). Higher concentrations of FGF21 (5 and 10 μg/ml) inhibited chondrocyte thymidine incorporation and collagen X mRNA expression. 10 ng/ml GH stimulated chondrocyte thymidine incorporation and collagen X mRNA expression, with both effects prevented by the addition in the culture medium of FGF21 in a concentration-dependent manner. In addition, FGF21 reduced GH binding in cultured chondrocytes. In cells transfected with FGFR1 siRNA or ERK 1 siRNA, the antagonistic effects of FGF21 on GH action were all prevented, supporting a specific effect of this growth factor in chondrocytes. Our findings suggest that increased expression of FGF21 during food restriction causes growth attenuation by antagonizing the GH stimulatory effects on chondrogenesis directly at the growth plate. In addition, high concentrations of FGF21 may directly suppress growth plate chondrocyte proliferation and differentiation.
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Affiliation(s)
- Shufang Wu
- Department of Pediatrics, Drexel University College of Medicine, Philadelphia, Pennsylvania 19134, USA
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Xie Y, Su N, Jin M, Qi H, Yang J, Li C, Du X, Luo F, Chen B, Shen Y, Huang H, Xian CJ, Deng C, Chen L. Intermittent PTH (1-34) injection rescues the retarded skeletal development and postnatal lethality of mice mimicking human achondroplasia and thanatophoric dysplasia. Hum Mol Genet 2012; 21:3941-55. [PMID: 22634226 DOI: 10.1093/hmg/dds181] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Achondroplasia (ACH) and thanatophoric dysplasia (TD) are caused by gain-of-function mutations of fibroblast growth factor receptor 3 (FGFR3) and they are the most common forms of dwarfism and lethal dwarfism, respectively. Currently, there are few effective treatments for ACH. For the neonatal lethality of TD patients, no practical effective therapies are available. We here showed that systemic intermittent PTH (1-34) injection can rescue the lethal phenotype of TD type II (TDII) mice and significantly alleviate the retarded skeleton development of ACH mice. PTH-treated ACH mice had longer naso-anal length than ACH control mice, and the bone lengths of humeri and tibiae were rescued to be comparable with those of wild-type control mice. Our study also found that the premature fusion of cranial synchondroses in ACH mice was partially corrected after the PTH (1-34) treatment, suggesting that the PTH treatment may rescue the progressive narrowing of neurocentral synchondroses that cannot be readily corrected by surgery. In addition, we found that the PTH treatment can improve the osteopenia and bone structure of ACH mice. The increased expression of PTHrP and down-regulated FGFR3 level may be responsible for the positive effects of PTH on bone phenotype of ACH and TDII mice.
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Affiliation(s)
- Yangli Xie
- State Key Laboratory of Trauma, Burns and Combined Injury, Center of Bone Metabolism and Repair, Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing 400042, China
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Almodóvar J, Bacon S, Gogolski J, Kisiday JD, Kipper MJ. Polysaccharide-Based Polyelectrolyte Multilayer Surface Coatings can Enhance Mesenchymal Stem Cell Response to Adsorbed Growth Factors. Biomacromolecules 2010; 11:2629-39. [DOI: 10.1021/bm1005799] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Jorge Almodóvar
- Department of Chemical and Biological Engineering and School of Biomedical Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, Colorado 80523-1370, and Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, Colorado 80523
| | - Samantha Bacon
- Department of Chemical and Biological Engineering and School of Biomedical Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, Colorado 80523-1370, and Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, Colorado 80523
| | - Jarrod Gogolski
- Department of Chemical and Biological Engineering and School of Biomedical Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, Colorado 80523-1370, and Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, Colorado 80523
| | - John D. Kisiday
- Department of Chemical and Biological Engineering and School of Biomedical Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, Colorado 80523-1370, and Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, Colorado 80523
| | - Matt J. Kipper
- Department of Chemical and Biological Engineering and School of Biomedical Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, Colorado 80523-1370, and Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, Colorado 80523
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Vora SR, Palamakumbura AH, Mitsi M, Guo Y, Pischon N, Nugent MA, Trackman PC. Lysyl oxidase propeptide inhibits FGF-2-induced signaling and proliferation of osteoblasts. J Biol Chem 2010; 285:7384-93. [PMID: 20048148 DOI: 10.1074/jbc.m109.033597] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Pro-lysyl oxidase is secreted as a 50-kDa proenzyme and is then cleaved to a 30-kDa mature enzyme (lysyl oxidase (LOX)) and an 18-kDa propeptide (lysyl oxidase propeptide (LOX-PP)). The presence of LOX-PP in the cell layers of phenotypically normal osteoblast cultures led us to investigate the effects of LOX-PP on osteoblast differentiation. Data indicate that LOX-PP inhibits terminal mineralization in primary calvaria osteoblast cultures when added at early stages of differentiation, with no effects seen when present at later stages. LOX-PP was found to inhibit serum- and FGF-2-stimulated DNA synthesis and FGF-2-stimulated cell growth. Enzyme-linked immunosorbent assay and Western blot analyses show that LOX-PP inhibits FGF-2-induced ERK1/2 phosphorylation, signaling events that mediate the FGF-2-induced proliferative response. LOX-PP inhibits FGF-2-stimulated phosphorylation of FRS2alpha and FGF-2-stimulated DNA synthesis, even after inhibition of sulfation of heparan sulfate proteoglycans. These data point to a LOX-PP target at or near the level of fibroblast growth factor receptor binding or activation. Ligand binding assays on osteoblast cell layers with (125)I-FGF-2 demonstrate a concentration-dependent inhibition of FGF-2 binding to osteoblasts by LOX-PP. In vitro binding assays with recombinant fibroblast growth factor receptor protein revealed that LOX-PP inhibits FGF-2 binding in an uncompetitive manner. We propose a working model for the respective roles of LOX enzyme and LOX-PP in osteoblast phenotype development in which LOX-PP may act to inhibit the proliferative response possibly to allow cells to exit from the cell cycle and progress to the next stages of differentiation.
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Affiliation(s)
- Siddharth R Vora
- Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118, USA
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Kawata K, Kubota S, Eguchi T, Moritani NH, Shimo T, Kondo S, Nishida T, Minagi S, Takigawa M. Role of the low-density lipoprotein receptor-related protein-1 in regulation of chondrocyte differentiation. J Cell Physiol 2010; 222:138-48. [DOI: 10.1002/jcp.21930] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Sundaram K, Senn J, Yuvaraj S, Rao DS, Reddy SV. FGF-2 stimulation of RANK ligand expression in Paget's disease of bone. Mol Endocrinol 2009; 23:1445-54. [PMID: 19556344 DOI: 10.1210/me.2009-0078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Receptor activator for nuclear factor-kappaB ligand (RANKL), a critical osteoclastogenic factor expressed in marrow stromal/preosteoblast cells is up-regulated in Paget's disease of bone (PDB). We previously demonstrated that heat-shock factor-2 (HSF-2) is a downstream target of fibroblast growth factor-2 (FGF-2) signaling to induce RANKL expression in bone marrow stromal/preosteoblast cells. In this study, we identified a 2.5-fold increase in serum FGF-2 levels in patients (n = 8) with PDB compared with normal subjects (n = 10). We showed that HSF-2 co-immunoprecipitates with heat-shock protein-27 (HSP-27) and that FGF-2 stimulation significantly increased phospho-HSP-27 levels in marrow stromal cells. Confocal microscopy revealed HSF-2 colocalization with HSP-27 in unstimulated cells and HSF-2 nuclear translocation upon FGF-2 stimulation. We further show that FGF-2 stimulation significantly increased the levels of phosphorylated signal transducers and activators of the transcription (p-STAT-1) in these cells. Western blot analysis confirmed that small interfering RNA suppression of STAT-1 significantly decreased (3.2-fold) RANKL expression and promoter activity in FGF-2-stimulated cells. Chromatin immunoprecipitation assay revealed STAT-1 binding to a putative motif located far upstream (-8 kb) in the hRANKL gene promoter region. These results suggest STAT-1 is a downstream effector of FGF-2 signaling and that elevated levels of FGF-2 stimulates RANKL expression in PDB.
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Affiliation(s)
- Kumaran Sundaram
- Charles P. Darby Children's Research Institute, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Harada D, Yamanaka Y, Ueda K, Tanaka H, Seino Y. FGFR3-related dwarfism and cell signaling. J Bone Miner Metab 2009; 27:9-15. [PMID: 19066716 DOI: 10.1007/s00774-008-0009-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Accepted: 04/15/2008] [Indexed: 11/27/2022]
Affiliation(s)
- Daisuke Harada
- Department of Pediatrics, Okayama University Graduated School of Medicine and Dentistry, 2-5-1, Shikata-cho, Okayama 700-8558, Japan.
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Kappen C, Neubüser A, Balling R, Finnell R. Molecular basis for skeletal variation: insights from developmental genetic studies in mice. BIRTH DEFECTS RESEARCH. PART B, DEVELOPMENTAL AND REPRODUCTIVE TOXICOLOGY 2007; 80:425-50. [PMID: 18157899 PMCID: PMC3938168 DOI: 10.1002/bdrb.20136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Skeletal variations are common in humans, and potentially are caused by genetic as well as environmental factors. We here review molecular principles in skeletal development to develop a knowledge base of possible alterations that could explain variations in skeletal element number, shape or size. Environmental agents that induce variations, such as teratogens, likely interact with the molecular pathways that regulate skeletal development.
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Affiliation(s)
- C Kappen
- Center for Human Molecular Genetics, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA.
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Harada D, Yamanaka Y, Ueda K, Nishimura R, Morishima T, Seino Y, Tanaka H. Sustained phosphorylation of mutated FGFR3 is a crucial feature of genetic dwarfism and induces apoptosis in the ATDC5 chondrogenic cell line via PLCgamma-activated STAT1. Bone 2007; 41:273-81. [PMID: 17561467 DOI: 10.1016/j.bone.2006.11.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 11/03/2006] [Accepted: 11/14/2006] [Indexed: 12/23/2022]
Abstract
The most frequent type of rhizomelic dwarfism, achondroplasia (ACH), is caused by mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. Mutations in FGFR3 result in skeletal dysplasias of variable severity, including mild phenotypic effects in hypochondroplasia (HCH), severe phenotypic effects in thanatophoric dysplasia types I (TDI) and II (TDII), and severe but survivable phenotypic effects in severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN). To explore the molecular mechanisms that result in the different phenotypes, we investigated the kinetics of mutated versions of FGFR3. First, we assayed the phosphorylation states of the mutated FGFR3s and found that the level of phosphorylation in TDI-FGFR3 was lower than in ACH-FGFR3, although the other mutants were phosphorylated according to phenotypic severity. Second, we analyzed the duration of the phosphorylation. TDI-FGFR3 was not highly phosphorylated under ligand-free conditions, but the peak phosphorylation levels of TDI-FGFR3 and ACH-FGFR3 were maintained for 30 min after stimulation with FGF-1. Moreover, ligand-dependent phosphorylation of TDI-FGFR3, but not ACH-FGFR3, lasted for more than 8 h after FGF-1 administration. The other mutant proteins showed sustained phosphorylation independent of ligand presence. Third, we investigated the intracellular localization of the mutant proteins. Immunofluorescence analysis showed accumulations of TDII-FGFR3, SADDAN-FGFR3, and a portion of TDI-FGFR3 in the endoplasmic reticulum (ER). Based on these data, we concluded that sustained phosphorylation of FGFR3 causes chondrodysplasia, and the phenotypic severity depends on the proportion of ER-localized mutant FGFR3. In FGFR3 signaling, the transcription factor, signal transducer and activator of transcription 1 (STAT1) inhibit proliferation and induce apoptosis of chondrocytes. Here we reveal that phospholipase C gamma (PLCgamma) mediates FGFR3-induced STAT1 activation. Both PLCgamma and STAT1 were activated by FGFR3 signaling, but a dominant-negative form of PLCgamma (DN-PLCgamma) remarkably reduced STAT1 phosphorylation. Apoptosis assays revealed that the constitutively active forms of FGFR3 (TDII-FGFR3) and STAT1 (STAT1-C) induce apoptosis of chondrogenic ATDC5 cells via caspase activity. DN-PLCgamma reduced the apoptosis of ATDC5 cells expressing TDII-FGFR3, but over-expression of both DN-PLCgamma and STAT1-C induced apoptosis. Therefore, we conclude that a PLCgamma-STAT1 pathway mediates apoptotic signaling by FGFR3.
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Affiliation(s)
- Daisuke Harada
- Department of Pediatrics, Okayama University, Graduate School of Medicine and Dentistry, 2-5-1 Shikata-Cho, Okayama 700-8558, Japan
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Ueda K, Yamanaka Y, Harada D, Yamagami E, Tanaka H, Seino Y. PTH has the potential to rescue disturbed bone growth in achondroplasia. Bone 2007; 41:13-8. [PMID: 17466614 DOI: 10.1016/j.bone.2007.02.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 01/21/2007] [Accepted: 02/07/2007] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Achondroplasia (Ach), the most common form of short-limb short stature, and related disorders are caused by constitutively active point mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. Recent studies have provided a large body of evidence for the role of the proliferation and differentiation of chondrocytes in these disorders. Furthermore, a G380R mutation in FGFR3 (FGFR3(Ach)), which results in achondroplasia, induces apoptosis in the chondrogenic cell line ATDC5. This is associated with a decrease in the expression of PTHrP, which shares the same receptor with PTH, and it is significant that PTHrP rescues these cells from apoptosis. METHODS Fetuses derived from transgenic mice expressing FGFR3(Ach) under the control of the type II collagen promoter (AchTG) or from wild-type mice were obtained on the 15th day of pregnancy. The femurs were collected from these specimens and cultured for 4 days with PTH. The effects of PTH treatment were then determined by morphometric and histological analyses, in situ hybridization of type X collagen mRNA, and the TUNEL assay. RESULTS AchTG femurs showed suppressed growth compared with wild type (0.29+/-0.10 mm vs. 0.46+/-0.06 mm, respectively; p<0.05), particularly in cartilage. PTH treatments improved the growth velocity in the femurs of the AchTG (0.50+/-0.06 mm; p<0.01 vs. control). This was associated with the inhibition of both differentiation and apoptosis in chondrocytes. CONCLUSIONS Our data suggest that PTH inhibits differentiation and apoptosis in chondrocytes and improves bone growth. These effects thus counterbalance the effects of FGFR3 mutations. PTH therefore is a potential therapeutic agent for achondroplasia.
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Affiliation(s)
- Koso Ueda
- Department of Pediatrics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
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Sljivic S, Kamenov B, Maglajlic S, Djordjevic V, Stojkovic-Eferica I, Stojanovic M, Stefanovic M, Mihailovic D, Mrkaic L, Tasic G. Possible interactions of genetic and immuno-neuro-endocrine regulatory mechanisms in pathogenesis of congenital anomalies. Med Hypotheses 2006; 67:57-64. [PMID: 16574341 DOI: 10.1016/j.mehy.2005.07.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 07/14/2005] [Indexed: 11/29/2022]
Abstract
The process of organogenesis depends on genetic and environmental factors. Besides genetic background, congenital anomalies can also be influenced by micro environmental changes, which are related to maternal-foetal interactions followed by the production of cytokines, hormones, neurotransmitters, growth factors and biochemical mediators, and stress proteins. Pre-natal maternal stress, including infections, psychological stress and other teratogens, can influence a disregulation of maternal immune, endocrine and nervous systems, during pregnancy. This is a crucial condition for the abnormal growth and development of the foetus. Activated maternal immune system can alter the cytokine network and make it inadequate for normal embryogenesis and organogenesis. Heat-shock proteins play an important role in stress physiology repairing DNA errors or activating pro-inflammatory response. Regarded from this aspect, the altered cytokine network suggests aetiopathogenetic basis of congenital anomalies in neonates. It is our wish to point out our potentially harmful conditions in the development of congenital anomalies, as well as their control by using pre-natal and pre-conceptional diagnostics and treatment.
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Affiliation(s)
- Sofija Sljivic
- Gynaecology and Obstetrics Clinic, Department of Neonatology, Clinical Centre, Nis Bulevar Nemanjica 7/12, 18 000 Nis, and University Clinic of Pediatrics, Belgrade, Serbia and Montenegro.
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15
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Koike M, Yamanaka Y, Inoue M, Tanaka H, Nishimura R, Seino Y. Insulin-like growth factor-1 rescues the mutated FGF receptor 3 (G380R) expressing ATDC5 cells from apoptosis through phosphatidylinositol 3-kinase and MAPK. J Bone Miner Res 2003; 18:2043-51. [PMID: 14606518 DOI: 10.1359/jbmr.2003.18.11.2043] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED An activated mutation in the FGFR3 gene causes ACH. To examine the effects of IGF-1, which is an important mediator of GH, on apoptosis, we analyzed a chondrogenic cell line expressing the FGFR3 mutants. Our findings that IGF-1 prevented the apoptosis through PI3K and MAPK pathways may explain how GH treatment improves the disturbed bone growth in ACH. INTRODUCTION Achondroplasia (ACH), which is caused by a point mutation of the fibroblast growth factor receptor 3 (FGFR3) gene in the transmembrane domain (G380R), is one of the most common genetic forms of dwarfism. Recently, using a chondrogenic cell line, ATDC5, we have showed that the constitutively active FGFR3 mutants induced an apoptosis of chondrocytes. We have also reported that growth hormone (GH) treatment increased the growth rate in achondroplasia in parallel with the increment of serum levels of insulin-like growth factor (IGF)-1, suggesting an important role of IGF-1 in skeletal development. In this study, to clarify the mechanism by which GH treatment improved the phenotype of ACH patients, we examined the possible effects of IGF-1 on an apoptosis induced by FGFR3 mutant in ATDC5. MATERIALS AND METHODS Using adenovirus vector, wildtype or mutant FGFR3 (G380R) was introduced into ATDC5. Analysis of apoptosis was estimated by TUNEL assay. Expression levels of apoptosis-related genes and activation of signaling molecules were analyzed by immunoblot. RESULTS MTT assay showed that the cell number was reduced in ATDC5 cells expressing the mutant FGFR3 (G380R; ATDC5-mtR3 cells), suggesting that ATDC5-mtR3 cells might fall into apoptosis. IGF-1, which is an important mediator of GH, restored cell proliferation and reduced apoptosis in ATDC5-mtR3 cells. IGF-1 also decreased the ratio of Bax/Bcl-2 in the cells. To investigate which signaling cascade is responsible for antiapoptotic effects of IGF-1, we examined the role of phosphatidylinositol 3-kinase (PI3K) and MAPK in ATDC5-mtR3 cells. Specific inhibitors of PI3K or MAPK blocked the antiapoptotic effects of IGF-1 in ATDC5-mtR3 cells. CONCLUSIONS Our findings, showing IGF-1 prevents the apoptosis induced by FGFR3 mutation through the PI3K pathway and MAPK pathway, explain the mechanisms by which GH treatment improves the disturbed bone growth in ACH.
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Affiliation(s)
- Mio Koike
- Department of Pediatrics, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
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16
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Yamanaka Y, Tanaka H, Koike M, Nishimura R, Seino Y. PTHrP rescues ATDC5 cells from apoptosis induced by FGF receptor 3 mutation. J Bone Miner Res 2003; 18:1395-403. [PMID: 12929929 DOI: 10.1359/jbmr.2003.18.8.1395] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED An activation mutation in the FGFR3 gene causes ACH. The effects of the FGFR3 mutants on apoptosis were analyzed in a chondrogenic cell line. ACH chondrocytes exhibited marked apoptotic with downregulation of PTHrP expression. Rescue of these cells by PTHrP replacement implies a potential therapy for this disorder. INTRODUCTION Achondroplasia (ACH), the most common form of short-limb dwarfism, and its related disorders are caused by constitutively activated point-mutated FGFR3. Recent studies have provided a large body of evidence on chondrocyte proliferation and differentiation in these disorders. However, little is known about the possible effects of the FGFR3 mutants on apoptosis of chondrocytes. METHODS The mutant FGFR3 genes causing ACH and thanatophoric dysplasia (TD), which is a more severe neonatal lethal form, were introduced into a chondrogenic cell line, ATDC5. Analysis of apoptosis was estimated by TUNEL assay, DNA laddering, and fluorescent measurement of mitochondrial membrane potential. Expression levels of parathyroid hormone-related peptide (PTHrP) and apoptosis-related genes were analyzed by Northern blot or immunoblot. RESULTS The introduction of these mutated FGFR3s into ATDC5 cells downregulated PTHrP expression and induced apoptosis with reduction of Bcl-2 expression. Importantly, replacement of PTHrP prevented the apoptotic changes and reduction of Bcl-2 expression in ATDC5 cells expressing the ACH mutant. In parallel with the severity of disease and the activity of FGFR3, ATDC5 cells expressing TD-mutant FGFR3 showed less expression of PTHrP and Bcl-2 and induced more remarkable apoptotic changes compared with ACH-mutant expressing cells. Furthermore, overexpression of Bcl-2 inhibited apoptotic changes, suggesting that the mutant FGFR3 caused apoptosis, at least in part, through reduction of Bcl-2 expression, which seems to be downstream of PTHrP. CONCLUSIONS Our data suggest that excessive activation of signaling cascades mediated by the FGFR3 mutants inhibits the expression of PTHrP and Bcl-2, resulting in apoptosis of chondrocytes, possibly leading to short-limb dwarfism. Rescue of these cells by PTHrP replacement implies a potential therapy for this disorder.
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Affiliation(s)
- Yoshitaka Yamanaka
- Department of Pediatrics, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan
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17
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Enomoto-Iwamoto M, Kitagaki J, Koyama E, Tamamura Y, Wu C, Kanatani N, Koike T, Okada H, Komori T, Yoneda T, Church V, Francis-West PH, Kurisu K, Nohno T, Pacifici M, Iwamoto M. The Wnt antagonist Frzb-1 regulates chondrocyte maturation and long bone development during limb skeletogenesis. Dev Biol 2002; 251:142-56. [PMID: 12413904 DOI: 10.1006/dbio.2002.0802] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Wnt antagonist Frzb-1 is expressed during limb skeletogenesis, but its roles in this complex multistep process are not fully understood. To address this issue, we determined Frzb-1 gene expression patterns during chick long bone development and carried out gain- and loss-of-function studies by misexpression of Frzb-1, Wnt-8 (a known Frzb-1 target), or different forms of the intracellular Wnt mediator LEF-1 in developing limbs and cultured chondrocytes. Frzb-1 expression was quite strong in mesenchymal prechondrogenic condensations and then characterized epiphyseal articular chondrocytes and prehypertrophic chondrocytes in growth plates. Virally driven Frzb-1 misexpression caused shortening of skeletal elements, joint fusion, and delayed chondrocyte maturation, with consequent inhibition of matrix mineralization, metalloprotease expression, and marrow/bone formation. In good agreement, misexpression of Frzb-1 or a dominant-negative form of LEF-1 in cultured chondrocytes maintained the cells at an immature stage. Instead, misexpression of Wnt-8 or a constitutively active LEF-1 strongly promoted chondrocyte maturation, hypertrophy, and calcification. Immunostaining revealed that the distribution of endogenous Wnt mediator beta-catenin changes dramatically in vivo and in vitro, from largely cytoplasmic in immature proliferating and prehypertrophic chondrocytes to nuclear in hypertrophic mineralizing chondrocytes. Misexpression of Frzb-1 prevented beta-catenin nuclear relocalization in chondrocytes in vivo or in vitro. The data demonstrate that Frzb-1 exerts a strong influence on limb skeletogenesis and is a powerful and direct modulator of chondrocyte maturation, phenotype, and function. Phases of skeletogenesis, such as terminal chondrocyte maturation and joint formation, appear to be particularly dependent on Wnt signaling and thus very sensitive to Frzb-1 antagonistic action.
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Affiliation(s)
- Motomi Enomoto-Iwamoto
- Department of Molecular, Cell and Tumor Biology, Osaka University Faculty of Dentistry, Suita, Osaka 565-0871, Japan.
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18
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Laplantine E, Rossi F, Sahni M, Basilico C, Cobrinik D. FGF signaling targets the pRb-related p107 and p130 proteins to induce chondrocyte growth arrest. J Cell Biol 2002; 158:741-50. [PMID: 12177046 PMCID: PMC2174007 DOI: 10.1083/jcb.200205025] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Unregulated FGF signaling affects endochondral ossification and long bone growth, causing several genetic forms of human dwarfism. One major mechanism by which FGFs regulate endochondral bone growth is through their inhibitory effect on chondrocyte proliferation. Because mice with targeted mutations of the retinoblastoma (Rb)-related proteins p107 and p130 present severe endochondral bone defects with excessive chondrocyte proliferation, we have investigated the role of the Rb family of cell cycle regulators in the FGF response. Using a chondrocyte cell line, we found that FGF induced a rapid dephosphorylation of all three proteins of the Rb family (pRb, p107, and p130) and a blockade of the cells in the G1 phase of the cell cycle. This cell cycle block was reversed by inactivation of Rb proteins with viral oncoproteins such as polyoma large T (PyLT) antigen and Adenovirus E1A. Expression of a PyLT mutant that efficiently binds pRb, but not p107 and p130, allowed the cells to be growth inhibited by FGF, suggesting that pRb itself is not involved in the FGF response. To investigate more precisely the role of the individual Rb family proteins in FGF-mediated growth inhibition, we used chondrocyte micromass culture of limb bud cells isolated from mice lacking Rb proteins individually or in combination. Although wild-type as well as Rb-/- chondrocytes were similarly growth inhibited by FGF, chondrocytes null for p107 and p130 did not respond to FGF. Furthermore, FGF treatment of metatarsal bone rudiments obtained from p107-/-;p130-/- embryos failed to inhibit proliferation of growth plate chondrocytes, whereas rudiments from p107-null or p130-null embryos showed only a slight inhibition of growth. Our findings indicate that p107 and p130, but not pRb, are critical effectors of FGF-mediated growth inhibition in chondrocytes.
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Affiliation(s)
- Emmanuel Laplantine
- Department of Microbiology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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19
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Robson H, Siebler T, Shalet SM, Williams GR. Interactions between GH, IGF-I, glucocorticoids, and thyroid hormones during skeletal growth. Pediatr Res 2002; 52:137-47. [PMID: 12149488 DOI: 10.1203/00006450-200208000-00003] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Linear growth occurs during development and the childhood years until epiphyseal fusion occurs. This process results from endochondral ossification in the growth plates of long bones and is regulated by systemic hormones and paracrine or autocrine factors. The major regulators of developmental and childhood growth are GH, IGF-I, glucocorticoids, and thyroid hormone. Sex steroids are responsible for the pubertal growth spurt and epiphyseal fusion. This review will consider interactions between GH, IGF-I, glucocorticoids, and thyroid hormone during linear growth. It is well known from physiologic and clinical studies that these hormones interact at the level of the hypothalamus and pituitary. Interacting effects on peripheral tissues such as liver are also well understood, but we concentrate here on the epiphyseal growth plate as an important and newly appreciated target organ for convergent hormone action.
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Affiliation(s)
- Helen Robson
- Department of Clinical Research, Christie Hospital National Health Service Trust, Manchester, UK
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20
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Abad V, Meyers JL, Weise M, Gafni RI, Barnes KM, Nilsson O, Bacher JD, Baron J. The role of the resting zone in growth plate chondrogenesis. Endocrinology 2002; 143:1851-7. [PMID: 11956168 DOI: 10.1210/endo.143.5.8776] [Citation(s) in RCA: 171] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In mammals, growth of long bones occurs at the growth plate, a cartilage structure that contains three principal layers: the resting, proliferative, and hypertrophic zones. The function of the resting zone is not well understood. We removed the proliferative and hypertrophic zones from the rabbit distal ulnar growth plate in vivo, leaving only the resting zone. Within 1 wk, a complete proliferative and hypertrophic zone often regenerated. Next, we manipulated growth plates in vivo to place resting zone cartilage ectopically alongside the proliferative columns. Ectopic resting zone cartilage induced a 90-degree shift in the orientation of nearby proliferative zone chondrocytes and seemed to inhibit their hypertrophic differentiation. Our findings suggest that resting zone cartilage makes important contributions to endochondral bone formation at the growth plate: 1) it contains stem-like cells that give rise to clones of proliferative chondrocytes; 2) it produces a growth plate-orienting factor, a morphogen, that directs the alignment of the proliferative clones into columns parallel to the long axis of the bone; and 3) it may also produce a morphogen that inhibits terminal differentiation of nearby proliferative zone chondrocytes and thus may be partially responsible for the organization of the growth plate into distinct zones of proliferation and hypertrophy.
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Affiliation(s)
- Veronica Abad
- Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 10N262, 10 Center Drive MSC 1862, Bethesda, MD 20892, USA
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21
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Morimoto KI, Shimizu T, Furukawa K, Morio H, Kurosawa H, Shirasawa T. Transgenic expression of the EXT2 gene in developing chondrocytes enhances the synthesis of heparan sulfate and bone formation in mice. Biochem Biophys Res Commun 2002; 292:999-1009. [PMID: 11944914 DOI: 10.1006/bbrc.2002.6770] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hereditary multiple exostoses (HME), a dominantly inherited disorder characterized by multiple cartilaginous tumors, is caused by mutations in the gene for, EXT1 or EXT2. Recent studies have revealed that EXT1 and EXT2 are required for the biosynthesis of heparan sulfate and exert maximal transferase activity as a complex. The Drosophila homologue of EXT1 (tout-velu) regulates the movement and signaling of Hedgehog protein, which plays an important role in the regulation of chondrocyte differentiation and bone development. In this study, to investigate the biological role of EXT2 in bone development in vivo and the pathological role of HME mutations in the development of exostoses, we generated transgenic mice expressing EXT2 or mutant EXT2 in developing chondrocytes. Histological analyses and micro-CT scanning showed that the biosynthesis of heparan sulfate and the formation of trabeculae were upregulated in EXT2-transgenic mice, but not in mutant EXT2-transgenic mice. The expression of EXT1 is concomitantly upregulated in EXT2-transgenic and even mutant EXT2-transgenic mice, suggesting an interactive regulation of EXT1 and EXT2 expression. These findings support that the EXT2 gene encodes an essential component of the glycosyltransferase complex required for the biosynthesis of heparan sulfate, which may eventually modulate the signaling involved in bone formation.
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Affiliation(s)
- Ko-ichi Morimoto
- Department of Molecular Genetics, Department of Biosignal Research, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
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22
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Sobue T, Gravely T, Hand A, Min YK, Pilbeam C, Raisz LG, Zhang X, Larocca D, Florkiewicz R, Hurley MM. Regulation of fibroblast growth factor 2 and fibroblast growth factor receptors by transforming growth factor beta in human osteoblastic MG-63 cells. J Bone Miner Res 2002; 17:502-12. [PMID: 11874241 DOI: 10.1359/jbmr.2002.17.3.502] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fibroblast growth factor 2 (FGF-2) and its receptors (FGFRs) are important regulators of bone cell function. Although FGF-2 is a major modulator of bone cell function, its expression and regulation in human osteoblasts have not been investigated. We examined FGF-2 messenger RNA (mRNA) expression and regulation in the human osteosarcoma MG-63 cells. Northern analysis revealed that MG-63 cells expressed FGF-2 mRNA transcripts of 7, 4, 2.2, and 1.3 kilobases (kb). In the absence of serum, treatment with transforming growth factor beta (TGF-beta; 0.1-10 ng/ml) increased all FGF-2 mRNA transcripts. Maximal increase was seen with 1 ng/ml of TGF-beta. TGF-beta increased FGF-2 mRNA expression within 2 h and this was sustained for 24 h. Phorbal myristate acetate (PMA; 1 microM) also increased FGF-2 mRNA at 6 h. Time course studies showed that TGF-beta did not significantly alter FGFR1 or FGFR2 mRNA expression in MG-63 cells. Western blotting with anti-human FGF-2 revealed that MG-63 cells synthesize three isoforms of FGF-2 protein of approximately 18, 22/23, and 24 kDa, which were increased after either 6 h or 24 h of treatment with TGF-beta. Increased FGF-2 mRNA and protein expression in response to TGF-beta was markedly reduced by the protein kinase A (PKA) inhibitor H-89. Immunogold labeling of MG-63 cells treated with TGF-beta showed increased labeling for FGF-2 and FGFR2 in the nuclei. In contrast, TGF-beta treatment significantly decreased FGFR1 labeling in the nuclei. These data show that TGF-beta regulates FGF-2 gene expression in human osteosarcoma cells. Furthermore, TGF-beta modulates the cellular localization of FGF-2 and its receptors.
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Affiliation(s)
- T Sobue
- University of Connecticut School of Medicine, Farmington, USA
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23
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Spector JA, Greenwald JA, Warren SM, Bouletreau PJ, Detch RC, Fagenholz PJ, Crisera FE, Longaker MT. Dura mater biology: autocrine and paracrine effects of fibroblast growth factor 2. Plast Reconstr Surg 2002; 109:645-54. [PMID: 11818848 DOI: 10.1097/00006534-200202000-00035] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The dura mater, the outermost layer of the meninges, is thought to be essential for calvarial morphogenesis, postnatal suture fusion, and osseous repair of calvarial defects. Despite numerous studies illustrating the fundamental role of the dura mater, there is little information about the autocrine and paracrine mechanisms regulating dural cell biology during calvarial ossification. Previous work conducted in the authors' laboratory demonstrated that non-suture-associated dural cells from 6-day-old rat pups expressed high levels of fibroblast growth factor 2 (FGF-2), whereas dural cells from 60-day-old adult rats expressed very little FGF-2. Because young mammals can successfully heal large calvarial defects, the authors sought to investigate the autocrine and/or paracrine effects of FGF-2 on the proliferation, gene expression, and alkaline phosphatase production of dural cells. Cultures of non-suture-associated dural cells were established from 6-day-old Sprague-Dawley rat pups and then stimulated with recombinant human FGF-2 (rhFGF-2; 10 ng/ml). Dural cells stimulated with rhFGF-2 proliferated significantly faster than untreated dural cells at 24 hours (2.1 x 10(5) +/- 3.2 x 10(4) versus 1.1 x 10(5) +/- 1.8 x 10(4), p < or = 0.001) and 48 hours (2.3 x 10(5) +/- 4.2 x 10(4) versus 1.2 x 10(5) +/- 1.3 x 10(4), p < or = 0.001). Moreover, dural cells stimulated with rhFGF-2 expressed 7-fold more proliferating cell nuclear antigen than did control cultures. Treatment with rhFGF-2 increased dural cell expression of genes important for skeletal repair: FGF-2 (7-fold), transforming growth factor beta 1 (3-fold), transforming growth factor beta 3 (4-fold), and type I collagen (4-fold). Furthermore, rhFGF-2 increased dural cell expression of osteopontin (2-fold), a "late" marker of osteoblastic differentiation. Interestingly, dural cell alkaline phosphatase activity, an "earlier" marker of osteoblast differentiation, was significantly decreased by treatment with rhFGF-2 compared with control cultures at 24 hours (0.005 +/- 0.001 versus 0.01 +/- 0.003, p < or = 0.01) and 48 hours (0.004 +/- 0.0009 versus 0.01 +/- 0.0009). Together these data provide insight into the autocrine and paracrine effects of FGF-2 on the biology of the dura mater.
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Affiliation(s)
- Jason A Spector
- Department of Surgery, New York University School of Medicine, NY, USA
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24
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Siebler T, Robson H, Bromley M, Stevens DA, Shalet SM, Williams GR. Thyroid status affects number and localization of thyroid hormone receptor expressing mast cells in bone marrow. Bone 2002; 30:259-66. [PMID: 11792595 DOI: 10.1016/s8756-3282(01)00631-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thyroid hormone (T(3)) plays a key role in endochondral ossification. The process relies on the coordinated synthesis and degradation of cartilage matrix and is disrupted in juvenile hypothyroidism, leading to abnormal skeletal development. Mast cells synthesize and store matrix-degrading enzymes. We examined whether thyroid status influences skeletal mast cell distribution in growing rats to determine whether they might modulate the actions of T(3) in bone. Tibiae were collected for histological, histochemical, immunohistochemical, and immunofluorescence analysis. Mast cells were increased throughout the bone marrow in hypothyroid rats compared with euthyroid, thyrotoxic, and hypothyroid-thyroxine replaced animals. Large numbers were present in metaphyseal marrow adjacent to the growth plate in hypothyroid animals and cells were distributed evenly throughout the marrow. Very few mast cells were present in metaphyseal marrow in other groups, but their numbers increased with increasing distance from the growth plate. T(3) receptor alpha1 (TRalpha1) was expressed in the nucleus and cytoplasm of skeletal mast cells, whereas TRalpha2 and TRbeta1 were restricted to the cytoplasm. Localization of TRs was not affected by altered thyroid status. Thus, disrupted endochondral ossification in hypothyroidism may be mediated in part by skeletal mast cells, which express TR proteins and may function as T(3) target cells.
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Affiliation(s)
- T Siebler
- Department of Endocrinology, Christie Hospital NHS Trust, Manchester, UK
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25
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Abstract
To gain entry into the host, viruses use host cell surface molecules that normally serve as receptors for other ligands. Herpes simplex virus type 1 (HSV-1) uses heparan sulphate (HS) glycosaminoglycans (GAGs) as receptors for initial attachment to the host cell surface. HS GAGs are both ubiquitous and structurally diverse, and normally serve as critical mediators of interactions between the cell and the extracellular environment. We have used the HS binding ability of HSV-1 to identify the function of a cellular gene, EXT1, which is involved in HS polymerisation. Cellular factors that affect virus growth and replication are often key regulators of the cell cycle and EXT1 is no different-humans with inherited mutations in EXT1 have developmental defects that lead to bone tumours (hereditary multiple exostoses, HME) and sometimes chondrosarcomas. Thus, as a result of using HSV-1 as a molecular probe, a functionally orphaned disease gene now has a defined function. These findings highlight the utility of viruses for investigating important cellular processes.
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Affiliation(s)
- C McCormick
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3
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26
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Lin X, Wei G, Shi Z, Dryer L, Esko JD, Wells DE, Matzuk MM. Disruption of gastrulation and heparan sulfate biosynthesis in EXT1-deficient mice. Dev Biol 2000; 224:299-311. [PMID: 10926768 DOI: 10.1006/dbio.2000.9798] [Citation(s) in RCA: 326] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations in the EXT1 gene are responsible for human hereditary multiple exostosis type 1. The Drosophila EXT1 homologue, tout-velu, regulates Hedgehog diffusion and signaling, which play an important role in tissue patterning during both invertebrate and vertebrate development. The EXT1 protein is also required for the biosynthesis of heparan sulfate glycosaminoglycans that bind Hedgehog. In this study, we generated EXT1-deficient mice by gene targeting. EXT1 homozygous mutants fail to gastrulate and generally lack organized mesoderm and extraembryonic tissues, resulting in smaller embryos compared to normal littermates. RT-PCR analysis of markers for visceral endoderm and mesoderm development indicates the delayed and abnormal development of both of these tissues. Immunohistochemical staining revealed a visceral endoderm pattern of Indian hedgehog (Ihh) in wild-type E6.5 embryos. However, in both EXT1-deficient embryos and wild-type embryos treated with heparitinase I, Ihh failed to associate with the cells. The effect of the EXT1 deletion on heparan sulfate formation was tested by HPLC and cellular glycosyltransferase activity assays. Heparan sulfate synthesis was abolished in EXT1 -/- ES cells and decreased to less than 50% in +/- cell lines. These results indicate that EXT1 is essential for both gastrulation and heparan sulfate biosynthesis in early embryonic development.
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Affiliation(s)
- X Lin
- Department of Biology and Biochemistry, University of Houston, Texas 77204, USA
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27
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McCormick C, Duncan G, Tufaro F. New perspectives on the molecular basis of hereditary bone tumours. MOLECULAR MEDICINE TODAY 1999; 5:481-6. [PMID: 10529789 DOI: 10.1016/s1357-4310(99)01593-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bone development is a highly regulated process sensitive to a wide variety of hormones, inflammatory mediators and growth factors. One of the most common hereditary skeletal dysplasias, hereditary multiple exostoses (HME), is an autosomal dominant disorder characterized by skeletal malformations that manifest as bony, benign tumours near the end of long bones. HME is usually caused by defects in either one of two genes, EXT1 and EXT2, which encode enzymes that catalyse the biosynthesis of heparan sulphate, an important component of the extracellular matrix. Thus, HME-linked bone tumours, like many other skeletal dysplasias, probably result from disruptions in cell surface architecture. However, despite the recent success in unravelling functions for several members of the EXT gene family, significant challenges remain before this knowledge can be used to develop new approaches for the diagnosis and treatment of disease.
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Affiliation(s)
- C McCormick
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada V6T 1Z3
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