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Xiao L, Clarke K, Hurley MM. Fibroblast Growth Factor 23 Neutralizing Antibody Ameliorates Abnormal Renal Phosphate Handling in Sickle Cell Disease Mice. Endocrinology 2023; 164:bqad173. [PMID: 37972265 PMCID: PMC11032245 DOI: 10.1210/endocr/bqad173] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 09/06/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
We assessed the involvement of fibroblast growth factor 23 (FGF23) in phosphaturia in sickle cell disease (SCD) mice. Control and SCD mice were treated with FGF23 neutralizing antibody (FGF23Ab) for 24 hours. Serum ferritin was significantly increased in SCD mice and was significantly reduced in female but not male SCD mice by FGF23Ab. FGF23Ab significantly reduced increased erythropoietin in SCD kidneys. Serum intact FGF23 was significantly increased in SCD female mice and was markedly increased in SCD male mice; however, FGF23Ab significantly reduced serum intact FGF23 in both genotypes and sexes. Serum carboxy-terminal-fragment FGF23 (cFGF23) was significantly reduced in SCD IgG male mice and was markedly but not significantly reduced in SCD IgG female mice. FGF23Ab significantly increased cFGF23 in both sexes and genotypes. Serum 1,25-dihydroxyvitamin D3 was significantly increased in SCD IgG and was further significantly increased by FGF23Ab in both sexes and genotypes. Significantly increased blood urea nitrogen in SCD was not reduced by FGF23Ab. The urine phosphate (Pi)/creatinine ratio was significantly increased in SCD in both sexes and was significantly reduced by FGF23Ab. Increased SCD kidney damage marker kidney injury molecule 1 was rescued, but sclerotic glomeruli, increased macrophages, and lymphocytes were not rescued by short-term FGF23Ab. FGF23Ab significantly reduced increased phospho-fibroblast growth factor receptor 1, αKlotho, phosphorylated extracellular signal-regulated kinase, phosphorylated serum/glucocorticoid-regulated kinase 1, phosphorylated sodium-hydrogen exchanger regulatory factor-1, phosphorylated janus kinase 3, and phosphorylated transducer and activator of transcription-3 in SCD kidneys. The type II sodium Pi cotransporter (NPT2a) and sodium-dependent Pi transporter PiT-2 proteins were significantly reduced in SCD kidneys and were increased by FGF23Ab. We conclude that increased FGF23/FGF receptor 1/αKlotho signaling promotes Pi wasting in SCD by downregulating NPT2a and PIT2 via modulation of multiple signaling pathways that could be rescued by FGF23Ab.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
| | - Kai Clarke
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
| | - Marja M Hurley
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
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Hurley MM, Coffin JD, Doetschman T, Valera C, Clarke K, Xiao L. FGF receptor inhibitor BGJ398 partially rescues osteoarthritis-like phenotype in older high molecular weight FGF2 transgenic mice via multiple mechanisms. Sci Rep 2022; 12:15968. [PMID: 36153352 PMCID: PMC9509331 DOI: 10.1038/s41598-022-20269-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/12/2022] [Indexed: 11/10/2022] Open
Abstract
We have used Basic Fibroblast Growth Factor (FGF2) transgenic mice as experimental models for human X-linked hypophosphatemia (XLH)-related degenerative osteoarthritis (OA) to investigate the pathogenesis of the disease and to test potential pharmacotherapies for treatment. This study tested the efficacy of BJG398, a small molecule fibroblast growth factor receptor tyrosine kinase (FGFRTK) inhibitor, to rescue the knee joint osteoarthritis phenotype in High Molecular Weight fibroblast growth factor 2 transgenic (HMWTgFGF2) mice. BJG398 was administered in vivo to 8-month-old female HMWTgFGF2 mice for six weeks. Histomorphometry, immunohistochemistry and micro-CT were used to examine the knee joints in BGJ398-treated and control mice. We assessed: Fibroblast Growth Factor 23 (FGF23) expression and FGFR1 activity; Matrix metalloproteinase 13 (MMP13) and Aggrecanase2 (ADAMTS5) expression; then signaling by SMAD1/5/8-pSMAD6, pERK1/2 and Runt-related transcription factor 2 (RUNX2). Using PrimePCR arrays, we identified a contributing role for major target genes in the TGFB/BMP2 signaling pathway that were regulated by BGJ398. BGJ398 inhibited HMWFGF2/FGF23-induced increase in bone morphogenic protein receptor-1, bone morphogenic protein-2 and 4 and Serine peptidase inhibitor, clade E, member 1. The results from Micro-CT and histology show BGJ398 treatment rescued the OA changes in subchondral bone and knee articular cartilage of HMWTgFGF2 mice. The gene expression and signal transduction results provide convincing evidence that HMWFGF2 generates OA through FGFRTK with characteristic downstream signaling that defines OA, namely: increased FGF23-FGFR1 activity with BMP-BMPR, activation of pSMAD1/5/8-RUNX2 and pERK signaling pathways, then upregulation of MMP13 and ADAMTS5 to degrade matrix. BGJ398 treatment effectively reversed these OA molecular phenotypes, providing further evidence that the OA generated by HMWFGF2 in the transgenic mice is FGFR-mediated and phenocopies the OA found in the Hyp mouse homolog of XLH with a spontaneous mutation in the Phex (phosphate regulating endopeptidase on the X chromosome) gene and human XLH-OA. Overall, the results obtained here explain how the pleotropic effects of FGF2 emanate from the different functions of HMW protein isoforms for cartilage and bone homeostasis, and the pathogenesis of XLH-degenerative osteoarthropathy. BGJ398 inhibits HMWFGF2-induced osteoarthritis via multiple mechanisms. These results provided important scientific evidence for the potential application of BGJ398 as a therapeutic agent for osteoarthritis in XLH.
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Affiliation(s)
- Marja M Hurley
- Department of Medicine, School of Medicine, UConn Health, 263 Farmington Avenue, Farmington, CT, 06030-3023, USA.
| | - J Douglas Coffin
- Department BMED, SB 271, The University of Montana, Missoula, MT, 59812, USA
| | - Thomas Doetschman
- Department of Cellular and Molecular Medicine, University of Arizona College of Medicine, Tucson, AZ, 85724, USA
| | - Christina Valera
- Department of Medicine, School of Medicine, UConn Health, 263 Farmington Avenue, Farmington, CT, 06030-3023, USA
| | - Kai Clarke
- Department of Medicine, School of Medicine, UConn Health, 263 Farmington Avenue, Farmington, CT, 06030-3023, USA
| | - Liping Xiao
- Department of Medicine, School of Medicine, UConn Health, 263 Farmington Avenue, Farmington, CT, 06030-3023, USA
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Millington G, Joseph J, Xiao L, Vijaykumar A, Mina M, Hurley MM. Fibroblast Growth Factor 2 High Molecular Weight Isoforms in Dentoalveolar Mineralization. Calcif Tissue Int 2022; 110:93-103. [PMID: 34245331 PMCID: PMC8738103 DOI: 10.1007/s00223-021-00888-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 10/21/2020] [Accepted: 07/02/2021] [Indexed: 01/03/2023]
Abstract
Transgenic mice overexpressing human high molecular weight fibroblast growth factor 2 (HMWFGF2) isoforms in osteoblast and odontoblast lineages (HMWTg) exhibit decreased dentin and alveolar bone mineralization, enlarged pulp chamber, and increased fibroblast growth factor 23 (FGF23). We examined if the alveolar bone and dentin mineralization defects in HMWTg mice resulted from increased FGF23 expression and whether an FGF23 neutralizing antibody could rescue the hypomineralization phenotype. HMWTg and VectorTg control mice were given subcutaneous injections of FGF23 neutralizing antibody twice/week starting at postnatal day 21 for 6 weeks. Since Calcitriol (1,25D) have direct effects in promoting bone mineralization, we also determined if 1,25D protects against the defective dentin and alveolar bone mineralization. Therefore, HMWTg mice were given subcutaneous injections of 1,25D daily or concomitantly with FGF23 neutralizing antibody for 6 weeks. Our results showed that HMWTg mice displayed thickened predentin, alveolar bone hypomineralization, and enlarged pulp chambers. FGF23 neutralizing antibody and 1,25D monotherapy partially rescued the dentin mineralization defects and the enlarged pulp chamber phenotype in HMWTg mice. 1,25D alone was not sufficient to rescue the alveolar bone hypomineralization. Interestingly, HMWTg mice treated with both FGF23 neutralizing antibody and 1.25D further rescued the enlarged pulp chamber size, and dentin and alveolar bone mineralization defects. We conclude that the dentin and alveolar bone mineralization defects in HMWTg mice might result from increased FGF23 expression. Our results show a novel role of HMWFGF2 on dentoalveolar mineralization.
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Affiliation(s)
- Grethel Millington
- University of Connecticut School of Dental Medicine, Farmington, CT, USA.
| | - Johnny Joseph
- NYU Langone Health, Postdoctoral Pediatric Dentistry Program, Brooklyn, NY, 11220, USA
| | - Liping Xiao
- Department of Medicine, University of Connecticut School of Medicine, UConn Health, Farmington, CT, 06030-052, USA
| | - Anushree Vijaykumar
- Department of Craniofacial Sciences, University of Connecticut School of Dental Medicine, Farmington, CT, USA
| | - Mina Mina
- Department of Craniofacial Sciences, University of Connecticut School of Dental Medicine, Farmington, CT, USA
| | - Marja M Hurley
- Department of Medicine, University of Connecticut School of Medicine, UConn Health, Farmington, CT, 06030-052, USA.
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Kuhn LT, Peng T, Gronowicz G, Hurley MM. Endogenous FGF-2 levels impact FGF-2/BMP-2 growth factor delivery dosing in aged murine calvarial bone defects. J Biomed Mater Res A 2021; 109:2545-2555. [PMID: 34173706 PMCID: PMC9943554 DOI: 10.1002/jbm.a.37249] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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] [Received: 02/09/2021] [Revised: 05/20/2021] [Accepted: 06/11/2021] [Indexed: 12/12/2022]
Abstract
Bone repair in elderly mice has been shown to be improved or negatively impacted by supplementing the highly osteogenic bone morphogenetic protein-2 (BMP-2) with fibroblast growth factor-2 (FGF-2). To better predict the outcome of FGF-2 supplementation, we investigated whether endogenous levels of FGF-2 play a role in optimal dosing of FGF-2 for augmenting BMP-2 activity in elderly mice. In vivo calvarial bone defect studies in Fgf2 knockout mice with wildtype controls were conducted with the growth factors delivered in a highly localized manner from a biomimetic calcium phosphate/polyelectrolyte multilayer coating applied to a bone graft substitute. Endogenous FGF-2 levels were measured in old mice versus young and found to decrease with age. Optimal dosing for improving bone defect repair correlated with levels of endogenous FGF-2, with a larger dose of FGF-2 required to have a positive effect on bone healing in the Fgf2 knockout mice. The same dose in wildtype old mice, with higher levels of FGF-2, promoted chondrogenesis and increased osteoclast activity. The results suggest a personalized medicine approach, based on a knowledge of endogenous levels of FGF-2, should guide FGF-2 supplementation in order to avoid provoking excessive bone resorption and cartilage formation, both of which inhibited calvarial bone repair.
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Affiliation(s)
- Liisa T Kuhn
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Tao Peng
- Department of Biomedical Engineering, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Gloria Gronowicz
- Department of Surgery, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Marja M Hurley
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, USA
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Abstract
Fibroblast growth factor 2 (FGF2) is important in musculoskeletal homeostasis, therefore the impact of reduction or Fgf2 knockout on skeletal muscle function and phenotype was determined. Gait analysis as well as muscle strength testing in young and old WT and Fgf2KO demonstrated age-related gait disturbances and reduction in muscle strength that were exacerbated in the KO condition. Fgf2 mRNA and protein were significantly decreased in skeletal muscle of old WT compared with young WT. Muscle fiber cross-sectional area was significantly reduced with increased fibrosis and inflammatory infiltrates in old WT and Fgf2KO vs. young WT. Inflammatory cells were further significantly increased in old Fgf2KO compared with old WT. Lipid-related genes and intramuscular fat was increased in old WT and old Fgf2KO with a further increase in fibro-adipocytes in old Fgf2KO compared with old WT. Impaired FGF signaling including Increased β-Klotho, Fgf21 mRNA, FGF21 protein, phosphorylated FGF receptors 1 and 3, was observed in old WT and old Fgf2KO. MAPK/ ERK1/2 was significantly increased in young and old Fgf2KO. We conclude that Fgf2KO, age-related decreased FGF2 in WT mice, and increased FGF21 in the setting of impaired Fgf2 expression likely contribute to impaired skeletal muscle function and sarcopenia in mice.
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Affiliation(s)
- C Homer-Bouthiette
- Yale Internal Medicine Residency Program, Yale New Haven Hospital, New Haven, CT, 06510, USA
| | - L Xiao
- Department of Medicine, School of Medicine, UConn Health, University of Connecticut, 263 Farmington Ave., Farmington, CT, 06030, USA
| | - Marja M Hurley
- Department of Medicine, School of Medicine, UConn Health, University of Connecticut, 263 Farmington Ave., Farmington, CT, 06030, USA.
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Stewart KA, Brown SL, Wrensford G, Hurley MM. Creating a Comprehensive Approach to Exposing Underrepresented Pre-health Professions Students to Clinical Medicine and Health Research. J Natl Med Assoc 2020; 112:36-43. [PMID: 31980210 DOI: 10.1016/j.jnma.2019.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/28/2019] [Accepted: 12/24/2019] [Indexed: 11/15/2022]
Abstract
BACKGROUND/PURPOSE With the urgency to create more equitable health care, increased research and early exposure to health interventions and clinical medicine are imperative. Health disparities continue to persist nationwide, particularly in underserved areas and among traditionally disadvantaged populations. In addition to the need to eliminate health disparities, increasing the diversity among health professionals to more accurately reflect the US population is essential. METHODS The health professions partnership at the School of Medicine and the School of Dental Medicine is a comprehensive pipeline designed to increase the preparation of underrepresented students for health careers. Through this health professions pipeline's Health Disparities Clinical Summer Research Fellowship Program (HDCSRFP), undergraduate students are exposed to health disparities research and clinical skills over seven weeks. Over the course of the program, participants conducted a research project, gained clinical exposure by shadowing community physicians and other health professionals, and received mentoring by health professional faculty and students. At the conclusion of the program, participants presented their research projects during a poster symposium. RESULTS A total of 121 program participants between 2008 and 2018 each conducted a research project focused on reducing health inequities within specific populations, particularly in urban settings. The health professions pipeline has been instrumental in increasing the aptitude and competitiveness of these students pursuing health careers through participation in research, clinical medicine, and enrichment activities. Specifically, 92% of the 79 program participants identified who completed undergraduate studies before the end of the 2018 fall semester pursued a career or further studies within a health profession. Forty-six percent of these college graduates were accepted or matriculated in medical school by the end of 2018. CONCLUSION The HDCSRFP, like the other health professions partnership pipeline programs, serves as a model for other educational programs to expose students to the field of medicine and health research, and to increase diversity within health professions.
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Affiliation(s)
- Kerry-Ann Stewart
- Health Career Opportunity Programs, UConn Health, UConn Schools of Medicine and Dental Medicine Farmington, CT, USA.
| | - Stacey L Brown
- Public Health Sciences, UConn Health, UConn Schools of Medicine and Dental Medicine Farmington, CT, USA
| | - Granville Wrensford
- Health Career Opportunity Programs, UConn Health, UConn Schools of Medicine and Dental Medicine Farmington, CT, USA
| | - Marja M Hurley
- Health Career Opportunity Programs, UConn Health, UConn Schools of Medicine and Dental Medicine Farmington, CT, USA
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7
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Xiao L, Williams D, Hurley MM. Inhibition of FGFR Signaling Partially Rescues Osteoarthritis in Mice Overexpressing High Molecular Weight FGF2 Isoforms. Endocrinology 2020; 161:5696655. [PMID: 31901095 PMCID: PMC6959088 DOI: 10.1210/endocr/bqz016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 09/06/2019] [Accepted: 01/02/2020] [Indexed: 12/29/2022]
Abstract
Fibroblast growth factor 2 (FGF2) and fibroblast growth factor receptors (FGFRs) are key regulatory factors in osteoarthritis (OA). HMWTg mice overexpress the high molecular weight FGF2 isoforms (HMWFGF2) in osteoblast lineage and phenocopy both Hyp mice (which overexpress the HMWFGF2 isoforms in osteoblasts and osteocytes) and humans with X-linked hypophosphatemia (XLH). We previously reported that, similar to Hyp mice and XLH subjects who develop OA, HMWTg mice also develop an OA phenotype associated with increased degradative enzymes and increased FGFR1 compared with VectorTg mice. Therefore, in this study, we examined whether in vivo treatment with the FGFR tyrosine kinase inhibitor NVP-BGJ398 (BGJ) would modulate development of the OA phenotype in knee joints of HMWTg mice. VectorTg and HMWTg mice (21 days of age) were treated with vehicle or BGJ for 13 weeks. Micro-computed tomography images revealed irregular shape and thinning of the subchondral bone with decreased trabecular number and thickness within the epiphyses of vehicle-treated HMWTg knees, which was partially rescued following BGJ treatment. Articular cartilage thickness was decreased in vehicle-treated HMWTg mice, and was restored to the cartilage thickness of VectorTg mice in the BGJ-treated HMWTg group. Increased OA degradative enzymes present in HMWTg vehicle-treated joints decreased after BGJ treatment. OA in HMWTg mice was associated with increased Wnt signaling that was rescued by BGJ treatment. This study demonstrates that overexpression of the HMWFGF2 isoforms in preosteoblasts results in osteoarthropathy that can be partially rescued by FGFR inhibitor via reduction in activated Wnt signaling.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine, UConn Health, Farmington, CT
| | - Donyell Williams
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine, UConn Health, Farmington, CT
| | - Marja M Hurley
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine, UConn Health, Farmington, CT
- Correspondence: Marja Hurley, MD, Department of Medicine MC-3023, UConn Health, 263 Farmington Avenue, Farmington, CT 06030-3105. E-mail:
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8
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Xiao L, Fei Y, Hurley MM. FGF2 crosstalk with Wnt signaling in mediating the anabolic action of PTH on bone formation. Bone Rep 2018; 9:136-144. [PMID: 30258857 PMCID: PMC6152810 DOI: 10.1016/j.bonr.2018.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/30/2018] [Accepted: 09/20/2018] [Indexed: 12/20/2022] Open
Abstract
The mechanisms of the anabolic effect of parathyroid hormone (PTH) in bone are not fully defined. The bone anabolic effects of PTH require fibroblast growth factor 2 (FGF2) as well as Wnt signaling and FGF2 modulates Wnt signaling in osteoblasts. In vivo PTH administration differentially modulated Wnt signaling in bones of wild type (WT) and in mice that Fgf2 was knocked out (Fgf2KO). PTH increased Wnt10b mRNA and protein in WT but not in KO mice. Wnt antagonist SOST mRNA and protein was significantly higher in KO group. However, PTH decreased Sost mRNA significantly in WT as well as in Fgf2KO mice, but to a lesser extent in Fgf2KO. Dickhopf 2 (DKK2) is critical for osteoblast mineralization. PTH increased Dkk2 mRNA in WT mice but the response was impaired in Fgf2KO mice. PTH significantly increased Lrp5 mRNA and phosphorylation of Lrp6 in WT but the increase was markedly attenuated in Fgf2KO mice. PTH increased β-catenin expression and Wnt/β-catenin transcriptional activity significantly in WT but not in Fgf2KO mice. These data suggest that the impaired bone anabolic response to PTH in Fgf2KO mice is partially mediated by attenuated Wnt signaling. In vivo PTH administration differentially modulated Wnt signaling in bones of WT and Fgf2KO mice. PTH treatment increased WNT10b and DKK2 expression in WT mice but the increase was blunted in Fgf2KO mice PTH increased Lrp5 mRNA and phosphorylation of Lrp6 in WT but the increase was markedly attenuated in Fgf2KO mice. PTH treatment increased β-catenin protein level and Wnt/β-catenin transcriptional activity in WT but not in Fgf2KO mice The impaired bone anabolic response to PTH in Fgf2KO mice is partially mediated by attenuated Wnt signaling.
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Affiliation(s)
| | | | - Marja M. Hurley
- Corresponding author at: Department of Medicine, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030, USA.
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Burt PM, Xiao L, Doetschman T, Hurley MM. Ablation of low-molecular-weight FGF2 isoform accelerates murine osteoarthritis while loss of high-molecular-weight FGF2 isoforms offers protection. J Cell Physiol 2018; 234:4418-4431. [PMID: 30144364 DOI: 10.1002/jcp.27230] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/18/2018] [Indexed: 02/06/2023]
Abstract
FGF2 is an essential growth factor implicated in osteoarthritis (OA), and deletion of full-length FGF2 (Fgf2ALLKO ) leads to murine OA. However, the FGF2 gene encodes both high-molecular-weight (HMW) and low-molecular-weight (LMW) isoforms, and the effects of selectively ablating individual isoforms, as opposed to total FGF2, has not been investigated in the context of OA. We undertook this study to examine whether mice lacking HMW FGF2 (Fgf2HMWKO ) or LMW FGF2 (Fgf2LMWKO ) develop OA and to further characterize the observed OA phenotype in Fgf2ALLKO mice. Fgf2HMWKO mice never developed OA, but 6- and 9-month-old Fgf2LMWKO and Fgf2ALLKO mice displayed signs of OA, including eroded articular cartilage, altered subchondral bone and trabecular architecture, and increased OA marker enzyme levels. Even with mechanical induction of OA, Fgf2HMWKO mice were protected against OA, whereas Fgf2LMWKO and Fgf2ALLKO displayed OA-like changes of the subchondral bone. Before exhibiting OA symptoms, Fgf2LMWKO or Fgf2ALLKO joints displayed differential expression of genes encoding key regulatory proteins, including interleukin-1β, insulin-like growth factor 1, bone morphogenetic protein 4, hypoxia-inducible factor 1, B-cell lymphoma 2, Bcl2-associated X protein, a disintegrin and metalloproteinase with thrombospondin motifs 5, ETS domain-containing protein, and sex-determining region Y box 9. Moreover, Fgf2LMWKO OA cartilage exhibited increased FGF2, FGF23, and FGFR1 expression, whereas Fgf2HMWKO cartilage had increased levels of FGFR3, which promotes anabolism in cartilage. These results demonstrate that loss of LMW FGF2 results in catabolic activity in joint cartilage, whereas absence of HMW FGF2 with only the presence of LMW FGF2 offers protection from OA.
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Affiliation(s)
- Patience M Burt
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine, UConn Health, Farmington, Connecticut
| | - Liping Xiao
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine, UConn Health, Farmington, Connecticut
| | - Thomas Doetschman
- B105 Institute and Department Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Marja M Hurley
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine, UConn Health, Farmington, Connecticut
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Wrensford GE, Stewart KA, Hurley MM. A Health Professions Pipeline for Underrepresented Students: Middle and High School Initiatives. J Racial Ethn Health Disparities 2018; 6:207-213. [PMID: 30014447 DOI: 10.1007/s40615-018-0515-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/28/2018] [Accepted: 07/03/2018] [Indexed: 10/28/2022]
Abstract
The Department of Health Career Opportunity Programs at UConn Health has developed the Aetna Health Professions Partnership Initiative (Aetna HPPI), a formal education consortium offering a comprehensive program of educational enrichment and support activities for underrepresented and first-generation students. The purpose is to identify and develop a diverse applicant pool of students who will eventually enter a health professions career with a focus on medicine and dental medicine. Activities are conducted for students in middle school through college. The achievements of the middle and high school pipeline programs and their impact on producing a more diversified health professions workforce were examined. The students are recruited from the greater Hartford, CT area and come from backgrounds traditionally underrepresented in healthcare, first-generation college families and modest family means. Program elements include a 30-week academic year Saturday Academy and a 6-week summer academic enrichment program aimed at preparing students for successful entrance into college, and a Parental Seminar Series for parents. Some of the activities include science, math, language arts, PSAT, SAT and ACT preparation, college tours, career counseling, mentoring by health professionals, and cultural experiences. Data analysis and tracking of the students in the academy have revealed some significant achievements. All seniors in the academy have graduated from high school. The SAT scores of the academy students have consistently stood above the average for the rest of the Hartford School District. In addition, the graduating seniors have a high rate of college matriculation.
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Affiliation(s)
- Granville E Wrensford
- Department of Health Career Opportunity Programs, UConn Health, Schools of Medicine and Dental Medicine, Farmington, CT, 06030-3920, USA.
| | - Kerry-Ann Stewart
- Department of Health Career Opportunity Programs, UConn Health, Schools of Medicine and Dental Medicine, Farmington, CT, 06030-3920, USA
| | - Marja M Hurley
- Department of Health Career Opportunity Programs, UConn Health, Schools of Medicine and Dental Medicine, Farmington, CT, 06030-3920, USA.
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Xiao L, Homer-Bouthiette C, Hurley MM. FGF23 Neutralizing Antibody Partially Improves Bone Mineralization Defect of HMWFGF2 Isoforms in Transgenic Female Mice. J Bone Miner Res 2018; 33:1347-1361. [PMID: 29502359 PMCID: PMC11034775 DOI: 10.1002/jbmr.3417] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/20/2018] [Accepted: 02/28/2018] [Indexed: 01/12/2023]
Abstract
Mice overexpressing high molecular weight FGF2 isoforms (HMWTg) in osteoblast lineage phenocopy human X-linked hypophosphatemic rickets (XLH) and a Hyp murine model of XLH demonstrating increased FGF23/FGF receptor signaling and hypophosphatemic rickets/osteomalacia. Because HMWFGF2 was upregulated in bones of Hyp mice and abnormal FGF23 signaling is important in XLH, HMWTg mice were used to examine the effect of the FGF23 neutralizing antibody (FGF23Ab). Eight-week-old female Vector control mice and HMWTg mice were treated with FGF23Ab or control IgG. A single injection of FGF23Ab rescued abnormal hypophosphatemia in HMWTg. The decreased type II sodium-dependent phosphate co-transporter (Npt2a) was rescued by FGF23Ab treatment. Inappropriately low serum 1,25(OH)2 D in HMWTg mice was normalized by FGF23Ab treatment, which is accompanied by increased anabolic vitamin D hydroxylase Cyp27b1 and decreased catabolic vitamin D hydroxylase Cyp24 mRNA in kidney. Long-term treatment with FGF23Ab normalized femur length and significantly increased vertebrae BMD and BMC, and femur BMC in HMWTg mice compared to IgG-treated HMWTg mice. Micro-computed tomography (μCT) revealed increased cortical porosity and decreased cortical apparent density in the HMWTg-IgG group compared with the Vector-IgG group; however, FGF23Ab treatment rescued defective cortical mineralization, decreased porosity, and increased apparent density in HMWTg mice. Bone histomorphometry analysis showed FGF23Ab treatment decreased osteoid volume, increased intra-label thickness, mineralization apposition rate, and bone formation rate in HMWTg mice. FGF23Ab improved disorganized double labeling in femurs from HMWTg mice. Quantitative real-time PCR analysis of tibia shafts showed FGF23Ab treatment normalized the osteocalcin (Ocn) mRNA expression in HMWTg mice, but further increased expression of SIBLING protein-related and pyrophosphate-related genes that are important in matrix mineralization, suggesting that HMWFGF2 modulates these genes independent of FGF23. We conclude that FGF23Ab partially rescued hypophosphatemic osteomalacia in HMWTg. However, long-term treatment with FGF23Ab further increased SIBLING protein-related genes and pyrophosphate-related genes in bone that could contribute to incomplete rescue of the mineralization defect. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, University of Connecticut School of Medicine, UCONN Health, Farmington, CT, USA
| | - Collin Homer-Bouthiette
- Department of Medicine, University of Connecticut School of Medicine, UCONN Health, Farmington, CT, USA
| | - Marja M Hurley
- Department of Medicine, University of Connecticut School of Medicine, UCONN Health, Farmington, CT, USA
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12
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Meo Burt P, Xiao L, Hurley MM. FGF23 Regulates Wnt/β-Catenin Signaling-Mediated Osteoarthritis in Mice Overexpressing High-Molecular-Weight FGF2. Endocrinology 2018; 159:2386-2396. [PMID: 29718273 PMCID: PMC6457004 DOI: 10.1210/en.2018-00184] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/21/2018] [Indexed: 12/23/2022]
Abstract
Although humans with X-linked hypophosphatemia (XLH) and the Hyp mouse, a murine homolog of XLH, are known to develop degenerative joint disease, the exact mechanism that drives the osteoarthritis (OA) phenotype remains unclear. Mice that overexpress high-molecular-weight fibroblast growth factor (FGF) 2 isoforms (HMWTg mice) phenocopy both XLH and Hyp, including OA with increased FGF23 production in bone and serum. Because HMWTg cartilage also has increased FGF23 and there is cross-talk between FGF23-Wnt/β-catenin signaling, the purpose of this study was to determine if OA observed in HMWTg mice is due to FGF23-mediated canonical Wnt signaling in chondrocytes, given that both pathways are implicated in OA pathogenesis. HMWTg OA joints had decreased Dkk1, Sost, and Lrp6 expression with increased Wnt5a, Wnt7b, Lrp5, Axin2, phospho-GSK3β, Lef1, and nuclear β-catenin, as indicated by immunohistochemistry or quantitative PCR analysis. Chondrocytes from HMWTg mice had enhanced alcian blue and alkaline phosphatase staining as well as increased FGF23, Adamts5, Il-1β, Wnt7b, Wnt16, and Wisp1 gene expression and phospho-GSK3β protein expression as indicated by Western blot, compared with chondrocytes of vector control and chondrocytes from mice overexpressing the low-molecular-weight isoform, which were protected from OA. Canonical Wnt inhibitor treatment rescued some of those parameters in HMWTg chondrocytes, seemingly delaying the initially accelerated chondrogenic differentiation. FGF23 neutralizing antibody treatment was able to partly ameliorate OA abnormalities in subchondral bone and reduce degradative/hypertrophic chondrogenic marker expression in HMWTg joints in vivo. These results demonstrate that osteoarthropathy of HMWTg is at least partially due to FGF23-modulated Wnt/β-catenin signaling in chondrocytes.
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Affiliation(s)
- Patience Meo Burt
- Division of Endocrinology and Metabolism, Department of Medicine, School of Medicine, UConn Health, Farmington, Connecticut
| | - Liping Xiao
- Division of Endocrinology and Metabolism, Department of Medicine, School of Medicine, UConn Health, Farmington, Connecticut
| | - Marja M Hurley
- Division of Endocrinology and Metabolism, Department of Medicine, School of Medicine, UConn Health, Farmington, Connecticut
- Correspondence: Marja M. Hurley, MD, Department of Medicine MC-3023, UConn Health, 263 Farmington Avenue, Farmington, Connecticut 06030. E-mail:
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13
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Xiao L, Du E, Homer-Bouthiette C, Hurley MM. Inhibition of FGFR Signaling Partially Rescues Hypophosphatemic Rickets in HMWFGF2 Tg Male Mice. Endocrinology 2017; 158:3629-3646. [PMID: 28938491 PMCID: PMC5659690 DOI: 10.1210/en.2016-1617] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 08/08/2017] [Indexed: 12/13/2022]
Abstract
Transgenic mice harboring high molecular weight fibroblast growth factor (FGF)2 isoforms (HMWTg) in osteoblast lineage cells phenocopy human X-linked hypophosphatemic rickets (XLH) and Hyp murine model of XLH demonstrating increased FGF23/FGF receptor signaling and hypophosphatemic rickets. Because HMWFGF2 was upregulated in bones of Hyp mice and abnormal FGF receptor (FGFR) signaling is important in XLH, HMWTg mice were used to examine the effect of the FGFR inhibitor NVP-BGJ398, now in clinical trials for cancer therapy, on hypophosphatemic rickets. Short-term treatment with NVP-BGJ398 rescued abnormal FGFR signaling and hypophosphatemia in HMWTg. Long-term treatment with NVP-BGJ398 normalized tail, tibia, and femur length. Four weeks NVP-BGJ398 treatment significantly increased total body bone mineral density (BMD) and bone mineral content (BMC) in HMWTg mice; however, at 8 weeks, total body BMD and BMC was indistinguishable among groups. Micro-computed tomography revealed decreased vertebral bone volume, trabecular number, and increased trabecular spacing, whereas femur trabecular tissue density was increased; however, NVP-BGJ398 rescued defective cortical bone mineralization, increased thickness, reduced porosity, and increased endosteal perimeter and cortical tissue density in HMWTg. NVP-BGJ398 improved femur cancellous bone, cortical bone structure, growth plate, and double labeling in cortical bone and also increased femur trabeculae double labeled surface, mineral apposition rate, bone formation rate, and osteoclast number and surface in HMWTg. The decreased NPT2a protein that is important for renal phosphate excretion was rescued by NVP-BGJ398 treatment. We conclude that NVP-BGJ398 partially rescued hypophosphatemic rickets in HMWTg. However, long-term treatment with NVP-BGJ398 further increased serum FGF23 that could exacerbate the mineralization defect.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, University of Connecticut School of Medicine, UConn Health, Farmington, Connecticut, 06030-052
| | - Erxia Du
- Department of Medicine, University of Connecticut School of Medicine, UConn Health, Farmington, Connecticut, 06030-052
| | - Collin Homer-Bouthiette
- Department of Medicine, University of Connecticut School of Medicine, UConn Health, Farmington, Connecticut, 06030-052
| | - Marja M. Hurley
- Department of Medicine, University of Connecticut School of Medicine, UConn Health, Farmington, Connecticut, 06030-052
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Jacobs EE, Gronowicz G, Hurley MM, Kuhn LT. Biomimetic calcium phosphate/polyelectrolyte multilayer coatings for sequential delivery of multiple biological factors. J Biomed Mater Res A 2017; 105:1500-1509. [PMID: 28002652 DOI: 10.1002/jbm.a.35985] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 11/01/2016] [Accepted: 12/14/2016] [Indexed: 12/12/2022]
Abstract
Combinations of growth factors synergistically enhance tissue regeneration, but typically require sequential, rather than co-delivery from biomaterials for maximum efficacy. Polyelectrolyte multilayer (PEM) coatings can deliver multiple factors without loss of activity; however, sequential delivery from PEM has been limited due to interlayer diffusion that results in co-delivery of the factors. This study shows that addition of a biomimetic calcium phosphate (bCaP) barrier layer to a PEM coating effectively prevents interlayer diffusion and enables sequential delivery of two different biomolecules via direct cell access. A simulated body fluid method was used to deposit a layer of bCaP followed by 30 bilayers of PEM made with poly-l-Lysine (+) and poly l-Glutamic acid (-) (bCaP-PEM). Measurements of MC3T3-E1 proliferation and viability over time on bCaP-PEM were used to demonstrate the sequential delivery kinetics of a proliferative factor [fibroblast growth factor-2 (FGF-2)] followed by a cytotoxic factor (antimycin A, AntiA). FGF-2 and AntiA both retained their bioactivity within bCaP-PEM, yet no release of FGF-2 or AntiA from bCaP-PEM was observed when cells were absent indicating a cell-mediated, local delivery process. This coating technique is useful for a variety of applications that would benefit from highly localized, sequential delivery of multiple biomolecules governed by cell initiated degradation that avoids off-target effects associated with diffusion-based release. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1500-1509, 2017.
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Affiliation(s)
- E E Jacobs
- Reconstructive Sciences, University of Connecticut Health, Farmington, Connecticut.,Biomedical Engineering, University of Connecticut, Storrs, Connecticut
| | - G Gronowicz
- Department of Surgery, University of Connecticut Health, Farmington, Connecticut
| | - M M Hurley
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut
| | - L T Kuhn
- Reconstructive Sciences, University of Connecticut Health, Farmington, Connecticut.,Biomedical Engineering, University of Connecticut, Storrs, Connecticut
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15
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Abstract
Humans with X-linked hypophosphatemia (XLH) and Hyp mice, the murine homolog of the disease, develop severe osteoarthropathy and the precise factors that contribute to this joint degeneration remain largely unknown. Fibroblast growth factor 2 (FGF2) is a key regulatory growth factor in osteoarthritis. Although there are multiple FGF2 isoforms the potential involvement of specific FGF2 isoforms in joint degradation has not been investigated. Mice that overexpress the high molecular weight FGF2 isoforms in bone (HMWTg mice) phenocopy Hyp mice and XLH subjects and Hyp mice overexpress the HMWFGF2 isoforms in osteoblasts and osteocytes. Given that Hyp mice and XLH subjects develop osteoarthropathies we examined whether HMWTg mice also develop knee joint degeneration at 2, 8, and 18 mo compared with VectorTg (control) mice. HMWTg mice developed spontaneous osteoarthropathy as early as age 2 mo with thinning of subchondral bone, osteophyte formation, decreased articular cartilage thickness, abnormal mineralization within the joint, increased cartilage degradative enzymes, hypertrophic markers, and angiogenesis. FGF receptors 1 and 3 and fibroblast growth factor 23 were significantly altered compared with VectorTg mice. In addition, gene expression of growth factors and cytokines including bone morphogenetic proteins, Insulin like growth factor 1, Interleukin 1 beta, as well as transcription factors Sex determining region Y box 9, hypoxia inducible factor 1, and nuclear factor kappa B subunit 1 were differentially modulated in HMWTg compared with VectorTg. This study demonstrates that overexpression of the HMW isoforms of FGF2 in bone results in catabolic activity in joint cartilage and bone that leads to osteoarthropathy.
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Affiliation(s)
- Patience Meo Burt
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine (P.M.B., L.X., M.M.H.), and Department of Reconstructive Sciences Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine (C.D.), UConn Health, Farmington, CT, 06030-3023
| | - Liping Xiao
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine (P.M.B., L.X., M.M.H.), and Department of Reconstructive Sciences Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine (C.D.), UConn Health, Farmington, CT, 06030-3023
| | - Caroline Dealy
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine (P.M.B., L.X., M.M.H.), and Department of Reconstructive Sciences Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine (C.D.), UConn Health, Farmington, CT, 06030-3023
| | - Melanie C Fisher
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine (P.M.B., L.X., M.M.H.), and Department of Reconstructive Sciences Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine (C.D.), UConn Health, Farmington, CT, 06030-3023
| | - Marja M Hurley
- Department of Medicine, Division of Endocrinology and Metabolism, School of Medicine (P.M.B., L.X., M.M.H.), and Department of Reconstructive Sciences Center for Regenerative Medicine and Skeletal Development, School of Dental Medicine (C.D.), UConn Health, Farmington, CT, 06030-3023
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16
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Xiao L, Andemariam B, Taxel P, Adams DJ, Zempsky WT, Dorcelus V, Hurley MM. Loss of Bone in Sickle Cell Trait and Sickle Cell Disease Female Mice Is Associated With Reduced IGF-1 in Bone and Serum. Endocrinology 2016; 157:3036-46. [PMID: 27171384 DOI: 10.1210/en.2015-2001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Characterization of the bone phenotype of 24-week-old female transgenic sickle cell disease (SCD), sickle cell trait (SCT) revealed significant reductions in bone mineral density and bone mineral content relative to control with a further significant decreased in SCD compared with SCT. By microcomputed tomography, femur middiaphyseal cortical area was significantly reduced in SCT and SCD. Cortical thickness was significantly decreased in SCD vs control. Diaphysis structural stiffness and strength were significantly reduced in SCT and SCD. Histomorphometry showed a significant increase in osteoclast perimeter in SCD and significantly decreased bone formation in SCD and SCT compared with control with a further significant decrease in SCD compared with SCT. Collagen-I mRNA was significantly decreased in tibiae from SCT and SCD and osterix, Runx2, osteoclacin, and Dmp-1 mRNA were significantly decreased in tibiae of SCD compared with control. Serum osteocalcin was significantly decreased and ferritin was significantly increased in SCD compared with control. Igf1 mRNA and serum IGF1 were significantly decreased in SCD and SCT. IGF1 protein was decreased in bone marrow stromal cells from SCT and SCD cultured in osteogenic media. Crystal violet staining revealed fewer cells and significantly reduced alkaline phosphatase positive mineralized nodules in SCT and SCD that was rescued by IGF1 treatment. We conclude that reduced bone mass in SCD and SCT mice carries architectural consequences that are detrimental to the mechanical integrity of femoral diaphysis. Furthermore reduced IGF1 and osteoblast terminal differentiation contributed to reduced bone formation in SCT and SCD mice.
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MESH Headings
- Anemia, Sickle Cell/blood
- Anemia, Sickle Cell/complications
- Anemia, Sickle Cell/metabolism
- Anemia, Sickle Cell/pathology
- Animals
- Bone Density
- Bone Diseases, Metabolic/blood
- Bone Diseases, Metabolic/metabolism
- Bone Diseases, Metabolic/pathology
- Bone Resorption/blood
- Bone Resorption/metabolism
- Bone Resorption/pathology
- Bone and Bones/metabolism
- Cells, Cultured
- Disease Models, Animal
- Female
- Insulin-Like Growth Factor I/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Sickle Cell Trait/blood
- Sickle Cell Trait/complications
- Sickle Cell Trait/metabolism
- Sickle Cell Trait/pathology
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Affiliation(s)
- Liping Xiao
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
| | - Biree Andemariam
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
| | - Pam Taxel
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
| | - Douglas J Adams
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
| | - William T Zempsky
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
| | - Valerie Dorcelus
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
| | - Marja M Hurley
- Departments of Medicine (L.X., B.A., P.T., V.D., M.M.H.) and Orthopedic Surgery (D.J.A.), UConn Health, Farmington, Connecticut 06030-3105; and Connecticut Children's Hospital (W.T.Z.), Hartford, Connecticut 06106-3322
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17
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Hurley MM, Resch JM, Maunze B, Frenkel MM, Baker DA, Choi S. N-acetylcysteine decreases binge eating in a rodent model. Int J Obes (Lond) 2016; 40:1183-6. [PMID: 26975440 PMCID: PMC4935583 DOI: 10.1038/ijo.2016.31] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/06/2016] [Accepted: 01/13/2016] [Indexed: 01/22/2023]
Abstract
Binge-eating behavior involves rapid consumption of highly palatable foods leading to increased weight gain. Feeding in binge disorders resembles other compulsive behaviors, many of which are responsive to N-acetylcysteine (NAC), which is a cysteine prodrug often used to promote non-vesicular glutamate release by a cystine-glutamate antiporter. To examine the potential for NAC to alter a form of compulsive eating, we examined the impact of NAC on binge eating in a rodent model. Specifically, we monitored consumption of standard chow and a high-fat, high carbohydrate western diet (WD) in a rodent limited-access binge paradigm. Before each session, rats received either a systemic or intraventricular injection of NAC. Both systemic and central administration of NAC resulted in significant reductions of binge eating the WD without decreasing standard chow consumption. The reduction in WD was not attributable to general malaise as NAC did not produce condition taste aversion. These results are consistent with the clinical evidence of NAC to reduce or reverse compulsive behaviors, such as, drug addiction, skin picking and hair pulling.
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Affiliation(s)
- M M Hurley
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - J M Resch
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - B Maunze
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - M M Frenkel
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - D A Baker
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - S Choi
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
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18
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Du E, Xiao L, Hurley MM. FGF23 Neutralizing Antibody Ameliorates Hypophosphatemia and Impaired FGF Receptor Signaling in Kidneys of HMWFGF2 Transgenic Mice. J Cell Physiol 2016; 232:610-616. [PMID: 27306296 DOI: 10.1002/jcp.25458] [Citation(s) in RCA: 13] [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] [Received: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 01/15/2023]
Abstract
High molecular weight FGF2 transgenic mice (HMWTg) phenocopy the Hyp mouse, homolog of human X-linked hypophosphatemic rickets with phosphate wasting and abnormal fibroblast growth factor (FGF23), fibroblast growth factor receptor (FGFR), Klotho and mitogen activated protein kinases (MAPK) signaling in kidney. In this study, we assessed whether short-term (24 h) in vivo administration of FGF23 neutralizing antibody (FGF23Ab) could rescue hypophosphatemia and impaired FGFR signaling in kidneys of HMWTg male mice. Bone mineral density and bone mineral content in 1-month-old HMWTg mice were significantly reduced compared with Control/VectorTg mice. Serum FGF23 was significantly increased in HMWTg compared with VectorTg. Serum phosphate was significantly reduced in HMWTg and was rescued by FGF23Ab. Serum parathyroid hormone (PTH) was significantly increased in HMWTg but was not reduced by FGF23Ab. 1, 25(OH)2 D was inappropriately normal in serum of HMWTg and was significantly increased in both Vector and HMWTg by FGF23Ab. Analysis of HMWTg kidneys revealed significantly increased mRNA expression of the FGF23 co-receptor Klotho, transcription factor mRNAs for early growth response-1 transcription factor (Egr-1), and c-fos were all significantly decreased by FGF23Ab. A significant reduction in the phosphate transporter Npt2a mRNA was also observed in HMWTg kidneys, which was increased by FGF23Ab. FGF23Ab reduced p-FGFR1, p-FGFR3, KLOTHO, p-ERK1/2, C-FOS, and increased NPT2A protein in HMWTg kidneys. We conclude that FGF23 blockade rescued hypophosphatemia by regulating FGF23/FGFR downstream signaling in HMWTg kidneys. Furthermore, HMWFGF2 isoforms regulate PTH expression independent of FGF23/FGFR signaling. J. Cell. Physiol. 232: 610-616, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- E Du
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut
| | - L Xiao
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut
| | - M M Hurley
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut
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19
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Du E, Xiao L, Hurley MM. FGFR Inhibitor Ameliorates Hypophosphatemia and Impaired Engrailed-1/Wnt Signaling in FGF2 High Molecular Weight Isoform Transgenic Mice. J Cell Biochem 2016; 117:1991-2000. [PMID: 26762209 DOI: 10.1002/jcb.25493] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 12/26/2022]
Abstract
High molecular weight FGF2 transgenic (HMWTg) mouse phenocopies the Hyp mouse, homolog of human X-linked hypophosphatemic rickets with hypophosphatemis, and abnormal FGF23, FGFR, Klotho signaling in kidney. Since abnormal Wnt signaling was reported in Hyp mice we assessed whether Wnt signaling was impaired in HMWTg kidneys and the effect of blocking FGF receptor (FGFR) signaling. Bone mineral density and bone mineral content in female HMWTg mice were significantly reduced. HMWTg mice were gavaged with FGFR inhibitor NVP-BGJ398, or vehicle and were euthanized 24 h post treatment. Serum phosphate was significantly reduced and urine phosphate was significantly increased in HMWTg and was rescued by NVP-BGJ398. Analysis of kidneys revealed a significant reduction in Npt2a mRNA in HMWTg that was significantly increased by NVP-BGJ398. Increased FGFR1, KLOTHO, P-ERK1/2, and decreased NPT2a protein in HMWTg were rescued by NVP-BGJ398. Wnt inhibitor Engrailed-1 mRNA and protein was increased in HMWTg and was decreased by BGJ398. Akt mRNA and protein was decreased in HMWTg and was increased by NVP-BGJ398. The active form of glycogen synthase 3 beta (pGSK3-β) and phosphor-β-catenin were increased in HMWTg and were both decreased by NVP-BGJ398 while decreased active-β-catenin in HMWTg was increased by NVP-BGJ398. We conclude that FGFR blockade rescued hypophosphatemia by regulating FGF and WNT signaling in HMWTg kidneys. J. Cell. Biochem. 117: 1991-2000, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Erxia Du
- Department of Medicine, UCONN Health, Farmington, 06030, Connecticut
| | - Liping Xiao
- Department of Medicine, UCONN Health, Farmington, 06030, Connecticut
| | - Marja M Hurley
- Department of Medicine, UCONN Health, Farmington, 06030, Connecticut
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20
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Hurley MM, Adams DJ, Wang L, Jiang X, Burt PM, Du E, Xiao L. Accelerated fracture healing in transgenic mice overexpressing an anabolic isoform of fibroblast growth factor 2. J Cell Biochem 2016; 117:599-611. [DOI: 10.1002/jcb.25308] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 08/04/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Marja M. Hurley
- Department of Medicine; University of Connecticut School of Medicine, UCONN Health; Farmington Connecticut 06030-052
| | - Douglas J. Adams
- Department of Orthopaedic Surgery; University of Connecticut School of Medicine, UCONN Health; Farmington Connecticut 06030-052
| | - Liping Wang
- Department of Craniofacial Sciences; University of Connecticut School of Dental Medicine, UCONN Health; Farmington Connecticut 06030-052
| | - Xi Jiang
- Department of Craniofacial Sciences; University of Connecticut School of Dental Medicine, UCONN Health; Farmington Connecticut 06030-052
| | - Patience Meo Burt
- Department of Medicine; University of Connecticut School of Medicine, UCONN Health; Farmington Connecticut 06030-052
| | - Erxia Du
- Department of Medicine; University of Connecticut School of Medicine, UCONN Health; Farmington Connecticut 06030-052
| | - Liping Xiao
- Department of Medicine; University of Connecticut School of Medicine, UCONN Health; Farmington Connecticut 06030-052
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21
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Hurley MM, Gronowicz G, Zhu L, Kuhn LT, Rodner C, Xiao L. Age-Related Changes in FGF-2, Fibroblast Growth Factor Receptors and β-Catenin Expression in Human Mesenchyme-Derived Progenitor Cells. J Cell Biochem 2015; 117:721-9. [PMID: 26332075 DOI: 10.1002/jcb.25357] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 08/31/2015] [Indexed: 12/14/2022]
Abstract
FGF-2 stimulates preosteoblast replication, and knockout of the FGF-2 gene in mice resulted in osteopenia with age, associated with decreased Wnt-β-Catenin signaling. In addition, targeted expression of FGF-2 in osteoblast progenitors increased bone mass in mice via Wnt-β-Catenin signaling. We posited that diminution of the intrinsic proliferative capacity of human mesenchyme-derived progenitor cells (HMDPCs) with age is due in part to reduction in FGF-2. To test this hypothesis HMDPCs from young (27-38), middle aged (47-56), and old (65-76) female human subjects were isolated from bone discarded after orthopedic procedures. HMDPCs cultures were mostly homogeneous with greater than 90% mesenchymal progenitor cells, determined by fluorescence-activated cell sorting. There was a progressive decrease in FGF-2 and FGFR1 mRNA and protein in HMDPCs with age. Since FGF-2 activates β-catenin, which can enhance bone formation, we also assessed its age-related expression in HMDPCs. An age-related decrease in total-β-Catenin mRNA and protein expression was observed. However there were increased levels of p-β-Catenin and decreased levels of activated-β-Catenin in old HMDSCs. FGF-2 treatment increased FGFR1 and β-Catenin protein, reduced the level of p-β-Catenin and increased activated-β-Catenin in aged HMDPCs. In conclusion, reduction in FGF-2 expression could contribute to age-related impaired function of HMDPCs via modulation of Wnt-β-catenin signaling.
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Affiliation(s)
| | | | - Li Zhu
- Department of Reconstructive Sciences, UCONN Health, Farmington, CT
| | - Liisa T Kuhn
- Department of Reconstructive Sciences, UCONN Health, Farmington, CT
| | - Craig Rodner
- Department of Orthopedics, UCONN Health, Farmington, CT
| | - Liping Xiao
- Department of Medicine, UCONN Health, Farmington, CT
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22
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Charles LF, Woodman JL, Ueno D, Gronowicz G, Hurley MM, Kuhn LT. Effects of low dose FGF-2 and BMP-2 on healing of calvarial defects in old mice. Exp Gerontol 2015; 64:62-9. [PMID: 25681640 DOI: 10.1016/j.exger.2015.02.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/30/2015] [Accepted: 02/10/2015] [Indexed: 02/06/2023]
Abstract
There is an age-associated reduction in the bone healing activity of bone morphogenetic protein-2 (BMP-2) that is currently addressed by administering higher doses of BMP-2 in elderly patients. The unwanted medical complications from high dose BMP-2 motivated this investigation to determine whether the addition of a low dose of fibroblast growth factor 2 (FGF-2) could enhance the ability of a lower dose of BMP-2 to heal calvarial bone defects in old mice (18-20 months old). FGF-2 (5 ng) and BMP-2 (2 μg) were administered by a controlled release two-phase biomaterial scaffold placed into the bone defect. FGF-2 released more rapidly and completely in vitro than BMP-2 (40% vs 2%). In vivo, both BMP-2 and FGF-2+BMP-2 groups formed more new bone in calvarial defects than scaffold alone (p < 0.001) or FGF-2 only groups (p < 0.01). The overall total volume of new bone was not statistically increased by the addition of FGF-2 to BMP-2 as measured by microCT, but the pattern of bone deposition was different. In old mice, but not young, there was enhanced bony fill in the central bone defect area when the BMP-2 was supplemented with FGF-2. Histological analysis of the center of the defect revealed an increased bone volume (%BV/TV (p = 0.004)) from the addition of FGF-2. These studies suggest that combining a low dose of FGF-2 with a low dose of BMP-2 has the potential to increase bone healing in old mice relative to BMP-2 alone.
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Affiliation(s)
- Lyndon F Charles
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Jessica L Woodman
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Daisuke Ueno
- Unit of Oral and Maxillofacial Implantology, Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Gloria Gronowicz
- Department of Surgery, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Marja M Hurley
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Liisa T Kuhn
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, CT 06030, USA.
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Homer-Bouthiette C, Doetschman T, Xiao L, Hurley MM. Knockout of nuclear high molecular weight FGF2 isoforms in mice modulates bone and phosphate homeostasis. J Biol Chem 2014; 289:36303-14. [PMID: 25389287 PMCID: PMC4276890 DOI: 10.1074/jbc.m114.619569] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [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] [Received: 10/17/2014] [Revised: 11/07/2014] [Indexed: 11/06/2022] Open
Abstract
We previously reported that targeted overexpression of the fibroblast growth factor 2 (FGF2) high molecular weight (HMW) isoforms in osteoblastic lineage cells in mice resulted in phenotypic changes, including dwarfism, rickets, osteomalacia, hypophosphatemia, increased serum parathyroid hormone, and increased levels of the phosphatonin FGF23 in serum and bone. This study examined the effects of genetically knocking out the FGF2HMW isoforms (HMWKO) on bone and phosphate homeostasis. HMWKO mice were not dwarfed and had significantly increased bone mineral density and bone mineral content in femurs and lumbar vertebrae when compared with the wild-type (WT) littermates. Micro-computed tomography analysis of femurs revealed increased trabecular bone volume, thickness, number, and connective tissue density with decreased trabecular spacing compared with WT. In addition, there was significantly decreased cortical porosity and increased cortical thickness and sub-periosteal area in femurs of HMWKO. Histomorphometric analysis demonstrated increased osteoblast activity and diminished osteoclast activity in the HMWKO. In vitro bone marrow stromal cell cultures showed there was a significant increase in alkaline phosphatase-positive colony number at 1 week in HMWKO. At 3 weeks of culture, the mineralized area was also significantly increased. There was increased expression of osteoblast differentiation marker genes and reduced expression of genes associated with impaired mineralization, including a significant reduction in Fgf23 and Sost mRNA. Normal serum phosphate and parathyroid hormone were observed in HMWKO mice. This study demonstrates a significant negative impact of HMWFGF2 on biological functions in bone and phosphate homeostasis in mice.
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Affiliation(s)
- Collin Homer-Bouthiette
- From the Department of Medicine, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, Connecticut 06030 and
| | - Thomas Doetschman
- the B105 Institute and Department Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona 85724-5217
| | - Liping Xiao
- From the Department of Medicine, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, Connecticut 06030 and
| | - Marja M Hurley
- From the Department of Medicine, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, Connecticut 06030 and
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Xiao L, Ueno D, Catros S, Homer-Bouthiette C, Charles L, Kuhn L, Hurley MM. Fibroblast growth factor-2 isoform (low molecular weight/18 kDa) overexpression in preosteoblast cells promotes bone regeneration in critical size calvarial defects in male mice. Endocrinology 2014; 155:965-74. [PMID: 24424065 PMCID: PMC3929728 DOI: 10.1210/en.2013-1919] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Repair of bone defects remains a significant clinical problem. Bone morphogenetic protein 2 (BMP2) is US Food and Drug Administration-approved for fracture healing but is expensive and has associated morbidity. Studies have shown that targeted overexpression of the 18-kDa low-molecular-weight fibroblast growth factor 2 isoform (LMW) by the osteoblastic lineage of transgenic mice increased bone mass. This study tested the hypotheses that overexpression of LMW would directly enhance healing of a critical size calvarial bone defect in mice and that this overexpression would have a synergistic effect with low-dose administration of BMP2 on critical size calvarial bone defect healing. Bilateral calvarial defects were created in LMW transgenic male mice and control/vector transgenic (Vector) male mice and scaffold with or without BMP2 was placed into the defects. New bone formation was assessed by VIVA-computed tomography of live animals over a 27-week period. Radiographic and computed tomography analysis revealed that at all time points, healing of the defect was enhanced in LMW mice compared with that in Vector mice. Although the very low concentration of BMP2 did not heal the defect in Vector mice, it resulted in complete healing of the defect in LMW mice. Histomorphometric and gene analysis revealed that targeted overexpression of LMW in osteoblast precursors resulted in enhanced calvarial defect healing due to increased osteoblast activity and increased canonical Wnt signaling.
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Affiliation(s)
- Liping Xiao
- Department of Medicine (L.X., C.H.-B., M.M.H.) and Department of Reconstructive Sciences (L.C., L.K.), University of Connecticut Health Center, Farmington, Connecticut 06030; Unit of Oral and Maxillofacial Implantology (D.U.), Tsurumi University School of Dental Medicine, Yokohama 230, Japan; and Inserm U1026 (S.C.), University of Bordeaux Segalen, 33076 Bordeaux, France
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25
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Agas D, Sabbieti MG, Marchetti L, Xiao L, Hurley MM. FGF-2 enhances Runx-2/Smads nuclear localization in BMP-2 canonical signaling in osteoblasts. J Cell Physiol 2013; 228:2149-58. [PMID: 23559326 DOI: 10.1002/jcp.24382] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Accepted: 03/28/2013] [Indexed: 01/30/2023]
Abstract
Bone morphogenetic protein 2 (BMP-2) is one of the most potent regulators of osteoblast differentiation and bone formation. R-Smads (Smads 1/5/8) are the major transducers for BMPs receptors and, once activated, they are translocated in the nucleus regulating transcription target genes by interacting with various transcription factors. Runx-2 proteins have been shown to interact through their C-terminal segment with Smads and this interaction is required for in vivo osteogenesis. In particular, recruitment of Smads to intranuclear sites is Runx-2 dependent, and Runx-2 factor may accommodate the dynamic targeting of signal transducer to active transcription sites. Previously, we have shown, by in vitro and in vivo experiments, that BMP-2 up-regulated FGF-2 which is important for the maximal responses of BMP-2 in bone. In this study, we found that endogenous FGF2 is necessary for BMP-2 induced nuclear accumulation and co-localization of Runx-2 and phospho-Smads1/5/8, while Runx/Smads nuclear accumulation and co-localization was reduced in Fgf2-/- osteoblasts. Based on these novel data, we conclude that the impaired nuclear accumulation of Runx-2 in Fgf2-/- osteoblasts reduces R-Smads sub-nuclear targeting with a consequent decreased expression of differentiating markers and impaired bone formation in Fgf2 null mice.
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Affiliation(s)
- Dimitrios Agas
- School of Biosciences and Biotechnology, University of Camerino, Camerino, Macerata, Italy
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26
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Abstract
We previously generated separate lines of transgenic mice that specifically overexpress either the Fibroblast growth factor (FGF)-2 low-molecular-mass isoform (Tg(LMW)) or the high-mass isoforms (Tg(HMW)) in the osteoblast lineage. Vector/control (Tg(Vector)) mice were also made. Here we report the use of isolated calvarial osteoblasts (COBs) from those mice to investigate whether the FGF-2 protein isoforms differentially modulate bone formation in vitro. Our hypothesis states that FGF-2 isoforms specifically modulate bone morphogenetic protein 2 (BMP-2) function and subsequently bone differentiation genes and their related signaling pathways. We found a significant increase in alkaline phosphatase-positive colonies in Tg(LMW) COBs compared with Tg(Vector) controls. BMP-2 treatment significantly increased mineralized colonies in Tg(Vector) and Tg(LMW) COBs. BMP-2 caused a further significant increase in mineralized colonies in Tg(LMW) COBs compared with Tg(Vector) COBs but did not increase alkaline phosphatase-positive colonies in Tg(HMW) COBs. Time-course studies showed that BMP-2 caused a sustained increase in phosphorylated mothers against decapentaplegic-1/5/8 (Smad/1/5/8), runt-related transcription factor-2 (Runx-2), and osterix protein in Tg(LMW) COBs. BMP-2 caused a sustained increase in phospho-p38 MAPK in Tg(Vector) but only a transient increase in Tg(LMW) and Tg(HMW) COBs. BMP-2 caused a transient increase in phospho-p44/42 MAPK in Tg(Vector) COBs and no increase in Tg(LMW) COBs, but a sustained increase was found in Tg(HMW) COBs. Basal expression of FGF receptor 1 protein was significantly increased in Tg(LMW) COBs relative to Tg(Vector) COBs, and although BMP-2 caused a transient increase in FGF receptor 1 expression in Tg(Vector) COBs and Tg(HMW) COBs, there was no further increase Tg(LMW) COBs. Interestingly, although basal expression of FGF receptor 2 was similar in COBs from all genotypes, BMP-2 treatment caused a sustained increase in Tg(LMW) COBs but decreased FGF receptor 2 in Tg(Vector) COBs and Tg(HMW) COBs.
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MESH Headings
- Alkaline Phosphatase/metabolism
- Animals
- Animals, Newborn
- Blotting, Western
- Bone Morphogenetic Protein 2/pharmacology
- Cells, Cultured
- Core Binding Factor Alpha 1 Subunit/metabolism
- Female
- Fibroblast Growth Factor 2/genetics
- Fibroblast Growth Factor 2/metabolism
- Humans
- Male
- Mice
- Mice, Transgenic
- Mitogen-Activated Protein Kinases/metabolism
- Osteoblasts/cytology
- Osteoblasts/drug effects
- Osteoblasts/metabolism
- Phosphorylation/drug effects
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- RNA Interference
- Receptor, Fibroblast Growth Factor, Type 1/genetics
- Receptor, Fibroblast Growth Factor, Type 1/metabolism
- Receptor, Fibroblast Growth Factor, Type 2/genetics
- Receptor, Fibroblast Growth Factor, Type 2/metabolism
- Skull/cytology
- Smad Proteins/metabolism
- Sp7 Transcription Factor
- Transcription Factors/metabolism
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27
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Fei Y, Gronowicz G, M. Hurley M. Fibroblast Growth Factor-2, Bone Homeostasis and Fracture Repair. Curr Pharm Des 2013; 19:3354-63. [DOI: 10.2174/1381612811319190002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/10/2013] [Indexed: 11/22/2022]
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28
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Kuhn LT, Ou G, Charles L, Hurley MM, Rodner CM, Gronowicz G. Fibroblast growth factor-2 and bone morphogenetic protein-2 have a synergistic stimulatory effect on bone formation in cell cultures from elderly mouse and human bone. J Gerontol A Biol Sci Med Sci 2013; 68:1170-80. [PMID: 23531867 DOI: 10.1093/gerona/glt018] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [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: 11/13/2022] Open
Abstract
Combined regimens of fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2) were investigated to stimulate osteogenic differentiation. In young mouse calvaria-derived cells, FGF-2 (0.16ng/mL) in combination with BMP-2 (50ng/mL) did not enhance mineralization, but in old mouse cells it resulted in more mineralization than BMP-2 alone. In young long bone mouse cultures, FGF-2 enhanced mineralization relative to BMP-2 alone, but in old cultures, lower dose of FGF-2 (0.016ng/mL) was necessary. In neonatal mouse calvarial cells, sequential delivery of low-dose FGF-2 and low-dose BMP-2 (5ng/mL) was more stimulatory than co-delivery. In young human cultures, 0.016ng/mL of FGF-2 did not enhance mineralization, in combination with 5ng/mL of BMP-2, but in older cultures, codelivery of FGF-2 and BMP-2 was superior to BMP-2 alone. In conclusion, BMP-2 treatment alone was sufficient for maximal mineralization in young osteoblast cultures. However, coadministration of FGF-2 and BMP-2 increases mineralization more than BMP-2 alone in cultures from old and young mouse long bones and old humans but not in young mouse calvarial cultures.
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Affiliation(s)
- Liisa T Kuhn
- Department of Surgery MC-3105, University of Connecticut Health Center, Farmington, CT 06030-3105.
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29
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Xiao L, Esliger A, Hurley MM. Nuclear fibroblast growth factor 2 (FGF2) isoforms inhibit bone marrow stromal cell mineralization through FGF23/FGFR/MAPK in vitro. J Bone Miner Res 2013; 28:35-45. [PMID: 22836867 PMCID: PMC3519956 DOI: 10.1002/jbmr.1721] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 07/11/2012] [Accepted: 07/16/2012] [Indexed: 12/22/2022]
Abstract
Fibroblast growth factor 23 (FGF23) is responsible for phosphate wasting and the phenotypic changes observed in human diseases such as X-linked hypophosphatemia (XLH). Targeted overexpression of nuclear high-molecular weight fibroblast growth factor 2 isoforms (HMW isoforms) in osteoblasts resulted in a transgenic mouse with phenotypic changes similar to XLH, including increased FGF23, hypophosphatemia, and rickets/osteomalacia. The goal of this study was to assess whether HMW isoforms also reduced mineralized bone formation via phosphate-independent effects in bone marrow stromal cells (BMSCs) by modulating FGF23/FGF receptor (FGFR)/extracellular signal-regulated kinase (ERK) signaling. To determine if decreased bone formation in BMSC cultures from HMW transgenic mice could be rescued by blocking this pathway, an FGF23 neutralizing antibody, the FGFR tyrosine kinase inhibitor SU5402 and the mitogen-activated protein kinase (MAPK) inhibitor PD98059 were used. FGF23 levels in the conditioned medium of HMW BMSC cultures were dramatically increased compared to BMSC from control (Vector) mice. Mineralized nodule formation was significantly decreased in HMW BMSC cultures compared with control cultures. The decreased nodule formation in HMW cultures was partially rescued by the FGF23 neutralizing antibody, SU5402 and PD98059. mRNA levels for the osteoblast-related genes, osteocalcin, Runt-related transcription factor 2 (Runx2), and osterix, and the osteocyte-related gene dentin matrix acidic phosphoprotein 1 (Dmp1) were significantly decreased in HMW cultures compared with control cultures, and the decreases were partially rescued by SU5402 or PD98059 treatment. Matrix-gla-protein (Mgp) mRNA was significantly higher in HMW cultures compared with control cultures, reduced by SU5402, but further increased by PD98059. Our results suggest that phosphate-independent effects of HMW isoforms in vitro may be directly mediated in part via FGF23 and that HMW isoforms signal via FGF23/FGFR/MAPK to inhibit bone formation in vitro.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA.
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30
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Abstract
Prostaglandin F2α (PGF2α) plays multiple roles on bone metabolism by regulating a wide range of signaling pathways. PGF2α, via activation of PKC, stimulates Na-dependent inorganic phosphate (Pi) transport system in osteoblasts; up-regulates interleukin (IL)-6 synthesis; increases vascular endothelial growth factor (VEGF). In addition, PGF2α acts as a strong mitogenic and survival agent on osteoblasts, and these effects are, at least in part, mediated by the binding of fibroblast growth factor-2 (FGF-2) to the specific receptor FGFR1. The understanding of PGF2α intracellular network, albeit complex to clarify, provides molecular bases useful to identify the players of osteoblast proliferation, apoptosis, and the associated angiogenic processes. Indeed, the molecular mechanism that underline PGF2α-regulated bone metabolism may be a promising platform for the development of novel targeted therapies in the treatment of bone disorders and disease.
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Affiliation(s)
- Dimitrios Agas
- School of Biosciences and Biotechnology, University of Camerino, Camerino (MC), Italy
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31
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Fei Y, Hurley MM. Role of fibroblast growth factor 2 and Wnt signaling in anabolic effects of parathyroid hormone on bone formation. J Cell Physiol 2012; 227:3539-45. [PMID: 22378151 DOI: 10.1002/jcp.24075] [Citation(s) in RCA: 33] [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] [Indexed: 12/17/2022]
Abstract
Osteoporosis poses enormous health and economic burden worldwide. One of the very few anabolic agents for osteoporosis is parathyroid hormone (PTH). Although great progress has been made since the FDA approved PTH in 2002, the detailed mechanisms of the bone anabolic effects of intermittent PTH treatment is still not well understood. PTH bone anabolic effect is regulated by extracellular factors. Maximal bone anabolic effect of PTH requires fibroblast growth factor 2 (FGF2) signaling, which might be mediated by transcription factor activating transcription factor 4 (ATF4). Maximal bone anabolic effect of PTH also requires Wnt signaling. Particularly, Wnt antagonists such as sclerostin, dickkopf 1 (DKK1) and secreted frizzled related protein 1 (sFRP1) are promising targets to increase bone formation. Interestingly, FGF2 signaling modulates Wnt/β-Catenin signaling pathway in bone. Therefore, multiple signaling pathways utilized by PTH are cross talking and working together to promote bone formation. Extensive studies on the mechanisms of action of PTH will help to identify new pathways that regulate bone formation, to improve available agents to stimulate bone formation, and to identify potential new anabolic agents for osteoporosis.
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Affiliation(s)
- Yurong Fei
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030, USA
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32
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Fei Y, Xu RH, Hurley MM. Stem cell-based bone repair. Am J Stem Cells 2012; 1:106-113. [PMID: 23671803 PMCID: PMC3636738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 05/12/2012] [Indexed: 06/02/2023]
Abstract
To accelerate bone repair, one strategy is to deliver the cells that make bone. The current review focuses on stem cell-based bone repair. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) can self-renew unlimitedly and differentiate into the bone forming cells - osteoblasts. Scientists have been actively investigating culture conditions to stably and efficiently induce differentiation of these stem cells into osteoblasts. However, ESCs have the issues of ethnics, immune response and both ESCs and iPSCs have tumorigenic potential. In contrast, bone marrow stromal/stem cells (BMSCs) hold great potential to enhance bone formation. Use of BMSCs can avoid the ethical issues and can obviate the immune response problem. However, BMSCs are a rare population with limited self-renewal ability and their differentiation ability decreases in elderly individuals. Considering the unlimited self-renewal ability, it is promising to develop protocols to differentiate ESCs into osteoblasts faithfully and efficiently. It is important to eliminate undifferentiated ESCs or iPSCs because of their tumorigenic potential. Therefore, future studies need to identify BMSCs specific cell surface markers since the cell surface markers utilized currently are not specific to BMSCs. Future studies also need to enhance the osteogenic potential without using viral vectors for transgene delivery to eliminate the risk of tumor generation.
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Affiliation(s)
- Yurong Fei
- Department of Medicine, University of Connecticut Health Center; University of Connecticut Stem Cell Institute263 Farmington Ave., Farmington, CT 06030, USA
| | - Ren-He Xu
- Department of Genetics and Developmental Biology, University of Connecticut Health Center; University of Connecticut Stem Cell Institute263 Farmington Ave., Farmington, CT 06030, USA
| | - Marja M Hurley
- Department of Medicine, University of Connecticut Health Center; University of Connecticut Stem Cell Institute263 Farmington Ave., Farmington, CT 06030, USA
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33
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Fei Y, Xiao L, Doetschman T, Coffin DJ, Hurley MM. Fibroblast growth factor 2 stimulation of osteoblast differentiation and bone formation is mediated by modulation of the Wnt signaling pathway. J Biol Chem 2011; 286:40575-83. [PMID: 21987573 DOI: 10.1074/jbc.m111.274910] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Fibroblast growth factor 2 (FGF2) positively modulates osteoblast differentiation and bone formation. However, the mechanism(s) is not fully understood. Because the Wnt canonical pathway is important for bone homeostasis, this study focuses on modulation of Wnt/β-catenin signaling using Fgf2(-/-) mice (FGF2 all isoforms ablated), both in the absence of endogenous FGF2 and in the presence of exogenous FGF2. This study demonstrates a role of endogenous FGF2 in bone formation through Wnt signaling. Specifically, mRNA expression for the canonical Wnt genes Wnt10b, Lrp6, and β-catenin was decreased significantly in Fgf2(-/-) bone marrow stromal cells during osteoblast differentiation. In addition, a marked reduction of Wnt10b and β-catenin protein expression was observed in Fgf2(-/-) mice. Furthermore, Fgf2(-/-) osteoblasts displayed marked reduction of inactive phosphorylated glycogen synthase kinase-3β, a negative regulator of Wnt/β-catenin pathway as well as a significant decrease of Dkk2 mRNA, which plays a role in terminal osteoblast differentiation. Addition of exogenous FGF2 promoted β-catenin nuclear accumulation and further partially rescued decreased mineralization in Fgf2(-/-) bone marrow stromal cell cultures. Collectively, our findings suggest that FGF2 stimulation of osteoblast differentiation and bone formation is mediated in part by modulating the Wnt pathway.
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Affiliation(s)
- Yurong Fei
- University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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34
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Fei Y, Xiao L, Hurley MM. The impaired bone anabolic effect of PTH in the absence of endogenous FGF2 is partially due to reduced ATF4 expression. Biochem Biophys Res Commun 2011; 412:160-4. [PMID: 21806973 DOI: 10.1016/j.bbrc.2011.07.066] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 07/18/2011] [Indexed: 02/06/2023]
Abstract
Parathyroid hormone (PTH) is currently the only approved anabolic agent for osteoporosis pharmacotherapy in the USA. However, the molecular and cellular mechanisms underlying which intermittent PTH stimulates bone formation are not fully established. Activating transcription factor 4 (ATF4) was recently identified to be a downstream target of PTH signaling in osteoblasts and FGF2 is able to rapidly increase ATF4 mRNA and protein expression in osteoblasts. Furthermore, ATF4 expression is markedly reduced in Fgf2(-/-) osteoblasts. In addition, FGF2 is required for the anabolic action of PTH on bone formation. Therefore, we hypothesize that the impaired anabolic effect of PTH in Fgf2(-/-) mice is partially due to reduced ATF4 expression. To test this hypothesis, we examined the ability of PTH to increase ATF4 expression in vitro and in vivo. In vitro data showed that PTH induced a significant increase in ATF4 mRNA expression as early as 15 min in Fgf2(+/+) primary bone marrow stromal cells (BMSCs) but not in Fgf2(-/-) BMSCs. In vivo data showed that treatment with PTH (1-34) (40 μg/kg/d) treatment for 2 weeks in 21-23 months female mice increased lumbar vertebrae bone mineral density in Fgf2(+/+) (13.8% increase). In contrast there was a 2.1% decrease in Fgf2(-/-) mice. Interestingly, basal ATF4 mRNA expression in tibiae was significantly lower in Fgf2(-/-) mice (46% decrease) compared to Fgf2(+/+) mice. PTH treatment increased ATF4 mRNA by 97% (p<0.05) in Fgf2(+/+) compared to 8% (p=0.57) in Fgf2(-/-) mice. Immunohistochemistry of vertebrae showed less ATF4 staining in Fgf2(-/-) tissue, and treatment with PTH increased ATF4 staining in Fgf2(+/+) but the increase was attenuated in Fgf2(-/-) tissue. In summary, reduced ATF4 expression may result in decreased osteoblast differentiation, and possibly contribute to the impaired stimulation of PTH on bone formation in Fgf2(-/-) mice.
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Affiliation(s)
- Yurong Fei
- University of Connecticut Health Center, Farmington, CT 06030, USA.
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Xiao L, Sobue T, Eisliger A, Kronenberg MS, Coffin JD, Doetschman T, Hurley MM. Disruption of the Fgf2 gene activates the adipogenic and suppresses the osteogenic program in mesenchymal marrow stromal stem cells. Bone 2010; 47:360-70. [PMID: 20510392 PMCID: PMC2947437 DOI: 10.1016/j.bone.2010.05.021] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [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: 07/21/2009] [Revised: 03/28/2010] [Accepted: 05/16/2010] [Indexed: 12/25/2022]
Abstract
Here we determine the Fibroblast Growth Factor-2 (FGF2) dependency of the time course of changes in bone mass in female mice. This study extends our earlier reports that knockout of the FGF2 gene (Fgf2) caused low turnover bone loss in Fgf2(-/-) male mice by examining bone loss with age in Fgf2(-/-) female mice, and by assessing whether reduced bone formation is associated with differentiation of bone marrow stromal cells (BMSCs) towards the adipocyte lineage. Bone mineral density (BMD) was similar in 3-month-old female Fgf2(+/+) and Fgf2(-/-) mice but was significantly reduced as early as 5 months of age in Fgf2(-/-) mice. In vivo studies showed that there was a greater accumulation of marrow fat in long bones of 14 and 20 month old Fgf2(-/-) mice compared with Fgf2(+/+) littermates. To study the effect of disruption of FGF2 on osteoblastogenesis and adipogenesis, BMSCs from both genotypes were cultured in osteogenic or adipogenic media. Reduced alkaline phosphatase positive (ALP), mineralized colonies and a marked increase in adipocytes were observed in Fgf2(-/-) BMSC cultures. These cultures also showed an increase in the mRNA of the adipogenic transcription factor PPARgamma2 as well as the downstream target genes aP2 and adiponectin. Treatment with exogenous FGF2 blocked adipocyte formation and increased ALP colony formation and ALP activity in BMSC cultures of both genotypes. These results support an important role for endogenous FGF2 in osteoblast (OB) lineage determination. Alteration in FGF2 signaling may contribute to impaired OB bone formation capacity and to increased bone marrow fat accumulation both of which are characteristics of aged bone.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA
| | - Takanori Sobue
- Department of Oral Health and Diagnostic Sciences, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA
| | - Alycia Eisliger
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA
| | - Mark. S Kronenberg
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA
| | - J. Douglas Coffin
- Department of Biomedical & Pharmaceutical Sciences, The University of Montana, Missoula, Montana, 59812, USA
| | - Thomas Doetschman
- BIO5 Institute and Department of Cell Biology and Anatomy, University of Arizona, Tucson, Arizona, 85724-5217, USA
| | - Marja M. Hurley
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, 06030, USA
- Corresponding Author: Phone: 860-679-2129; FAX: 860-679-1875;
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Sabbieti MG, Agas D, Marchetti L, Santoni G, Amantini C, Xiao L, Menghi G, Hurley MM. Signaling pathways implicated in PGF2alpha effects on Fgf2+/+ and Fgf2-/- osteoblasts. J Cell Physiol 2010; 224:465-74. [PMID: 20432442 DOI: 10.1002/jcp.22143] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Prostaglandin F2alpha (PGF2alpha) regulates fibroblast growth factor-2 (FGF-2) and fibroblast growth factor receptor (FGFR) expression in osteoblasts. Here, the role of FGF-2 in PGF2alpha-induced proliferation and the signaling pathway involved, were determined in calvarial osteoblasts (COBs) from Fgf2+/+ and Fgf2-/- mice. The involvement of the exported FGF-2 isoform, was determined using the FGF-2 neutralizing antibody to alter its binding to FGFR1. PGF2alpha increased activity of Ras, and MAP-kinase cascade as well as Bcl-2 and c-Myc levels in Fgf2+/+ but not in Fgf2-/- COBs. Moreover, in Fgf2+/+ COBs, PGF2alpha-enhanced nuclear accumulation and co-localization of Bcl-2/c-Myc. Although up-regulation of multiple proliferative and survival signals were induced by PGF2alpha in Fgf2+/+ COBs, phospho-p53 was unmodified while p53 was increased. Increased phospho-p53 was, instead, found in Fgf2-/- COBs without up-regulation of oncogenic proteins. The lack of p53 activation in wild type osteoblasts could be due in part to the overexpression of MDM2 caused by PGF2alpha via FGF-2. PGF2alpha, also, increased cyclins D and E in Fgf2+/+ COBs and induced an expansion of Fgf2+/+ osteoblasts in G(2)/M phase. These data clearly show that PGF2alpha induces proliferation via endogenous FGF-2 and the exported isoform mediates PGF2alpha effects by acting in autocrine manner. Furthermore, silencing of FGFR1 in Fgf2+/+ COBs blocked PGF2alpha induced increase of phospho-MDM2 and cyclins.
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Xiao L, Naganawa T, Lorenzo J, Carpenter TO, Coffin JD, Hurley MM. Nuclear isoforms of fibroblast growth factor 2 are novel inducers of hypophosphatemia via modulation of FGF23 and KLOTHO. J Biol Chem 2010; 285:2834-46. [PMID: 19933269 PMCID: PMC2807337 DOI: 10.1074/jbc.m109.030577] [Citation(s) in RCA: 54] [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] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 10/20/2009] [Indexed: 11/06/2022] Open
Abstract
FGF2 transgenic mice were developed in which type I collagen regulatory sequences drive the nuclear high molecular weight FGF2 isoforms in osteoblasts (TgHMW). The phenotype of TgHMW mice included dwarfism, decreased bone mineral density (BMD), osteomalacia, and decreased serum phosphate (P(i)). When TgHMW mice were fed a high P(i) diet, BMD was increased, and dwarfism was partially reversed. The TgHMW phenotype was similar to mice overexpressing FGF23. Serum FGF23 was increased in TgHMW mice. Fgf23 mRNA in bones and fibroblast growth factor receptors 1c and 3c and Klotho mRNAs in kidneys were increased in TgHMW mice, whereas the renal Na(+)/P(i) co-transporter Npt2a mRNA was decreased. Immunohistochemistry and Western blot analyses of TgHMW kidneys showed increased KLOTHO and decreased NPT2a protein. The results suggest that overexpression of HMW FGF2 increases FGF23/FGFR/KLOTHO signaling to down-regulate NPT2a, causing P(i) wasting, osteomalacia, and decreased BMD. We assessed whether HMW FGF2 expression was altered in the Hyp mouse, a mouse homolog of the human disease X-linked hypophosphatemic rickets/osteomalacia. Fgf2 mRNA was increased in bones, and Western blots showed increased FGF2 protein in nuclear fractions from osteoblasts of Hyp mice. In addition, immunohistochemistry demonstrated co-localization of FGF23 and HMW FGF2 protein in osteoblasts and osteocytes from Hyp mice. This study reveals a novel mechanism of regulation of the FGF23-P(i) homeostatic axis.
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Affiliation(s)
- Liping Xiao
- From the Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Takahiro Naganawa
- From the Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Joseph Lorenzo
- From the Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Thomas O. Carpenter
- the Department of Pediatrics (Endocrinology), Yale University School of Medicine, New Haven, Connecticut 06520, and
| | - J. Douglas Coffin
- the Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana 59812
| | - Marja M. Hurley
- From the Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030
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Sabbieti MG, Agas D, Xiao L, Marchetti L, Coffin JD, Doetschman T, Hurley MM. Endogenous FGF-2 is critically important in PTH anabolic effects on bone. J Cell Physiol 2009; 219:143-51. [PMID: 19107841 DOI: 10.1002/jcp.21661] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Parathyroid hormone (PTH) increases fibroblast growth factor receptor-1 (FGFR1) and fibroblast growth factor-2 (FGF-2) expression in osteoblasts and the anabolic response to PTH is reduced in Fgf2-/- mice. This study examined whether candidate factors implicated in the anabolic response to PTH were modulated in Fgf2-/- osteoblasts. PTH increased Runx-2 protein expression in Fgf2+/+ but not Fgf2-/- osteoblasts. By immunocytochemistry, PTH treatment induced nuclear accumulation of Runx-2 only in Fgf2+/+ osteoblasts. PTH and FGF-2 regulate Runx-2 via activation of the cAMP response element binding proteins (CREBs). Western blot time course studies showed that PTH increased phospho-CREB within 15 min that was sustained for 24 h in Fgf2+/+ but had no effect in Fgf2-/- osteoblasts. Silencing of FGF-2 in Fgf2+/+ osteoblasts blocked the stimulatory effect of PTH on Runx-2 and CREBs phosphorylation. Studies of the effects of PTH on proteins involved in osteoblast precursor proliferation and apoptosis showed that PTH increased cyclinD1-cdk4/6 protein in Fgf2+/+ but not Fgf2-/- osteoblasts. Interestingly, PTH increased the cell cycle inhibitor p21/waf1 in Fgf2-/- osteoblasts. PTH increased Bcl-2/Bax protein ratio in Fgf2+/+ but not Fgf2-/- osteoblasts. In addition PTH increased cell viability in Fgf2+/+ but not Fgf2-/- osteoblasts. These data suggest that endogenous FGF-2 is important in PTH effects on osteoblast proliferation, differentiation, and apoptosis. Reduced expression of these factors may contribute to the reduced anabolic response to PTH in the Fgf2-/- mice. Our results strongly indicate that the anabolic PTH effect is dependent in part on FGF-2 expression.
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Affiliation(s)
- Maria Giovanna Sabbieti
- Department of Comparative Morphology and Biochemistry, University of Camerino, Camerino (MC), Italy
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Xiao L, Liu P, Li X, Doetschman T, Coffin JD, Drissi H, Hurley MM. Exported 18-kDa isoform of fibroblast growth factor-2 is a critical determinant of bone mass in mice. J Biol Chem 2008; 284:3170-3182. [PMID: 19056741 DOI: 10.1074/jbc.m804900200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The role of the 18-kDa isoform of fibroblast growth factor-2 (FGF2) in the maintenance of bone mass was examined in Col3.6-18-kDa FGF2-IRES-GFPsaph transgenic (18-kDa TgFGF2) mice in which a 3.6-kb fragment of the type I collagen 5'-regulatory region (Col3.6) drives the expression of only the 18-kDa isoform of FGF2 with green fluorescent protein-sapphire (GFPsaph). Vector only transgenic mice (Col3.6-IRES-GFPsaph, VTg) were also developed as a control, and mice specifically deficient in 18-kDa FGF2 (FGF2(lmw)(-/-)) were also examined. Bone mineral density, femoral bone volume, trabecular thickness, and cortical bone area and thickness were significantly increased in 18-kDa TgFGF2 mice compared with VTg. Bone marrow cultures (BMSC) from 18-kDa TgFGF2 mice produced more mineralized nodules than VTg. Increased bone formation was associated with reduced expression of the Wnt antagonist secreted frizzled receptor 1 (sFRP-1). In contrast to 18-kDa TgFGF2 mice, FGF2(lmw)(-/-) mice have significantly reduced bone mineral density and fewer mineralized nodules, coincident with increased expression of sFRP-1 in bones and BMSC. Moreover, silencing of sFRP-1 in BMSC from FGF2(lmw)(-/-) mice reversed the decrease in beta-catenin and Runx2 mRNA. Assay of Wnt/beta-catenin-mediated transcription showed increased and decreased TCF-luciferase activity in BMSC from 18-kDa TgFGF2 and FGF2(lmw)(-/-) mice, respectively. Collectively, these results demonstrate that the 18-kDa FGF2 isoform is a critical determinant of bone mass in mice by modulation of the Wnt signaling pathway.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Peng Liu
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Xiaofeng Li
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8064, BIO5 Institute
| | - Thomas Doetschman
- Department of Cell Biology and Anatomy, University of Arizona, Tucson, Arizona 85724-5217
| | - J Douglas Coffin
- Department of Biomedical & Pharmaceutical Sciences, the University of Montana, Missoula, Montana 59812-1552
| | - Hicham Drissi
- Department of Orthopaedic Surgery, University of Connecticut Health Center, Farmington, Connecticut 06030
| | - Marja M Hurley
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030.
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Naganawa T, Xiao L, Coffin JD, Doetschman T, Sabbieti MG, Agas D, Hurley MM. Reduced expression and function of bone morphogenetic protein-2 in bones of Fgf2 null mice. J Cell Biochem 2008; 103:1975-88. [PMID: 17955502 DOI: 10.1002/jcb.21589] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Disruption of the fibroblast growth factor 2 (FGF-2) gene results in reduced bone mass in mice and impairs expression of bone morphogenic protein-2 (BMP-2) an important mediator of osteoblast and osteoclast differentiation. Since the relationship between FGF-2 and BMP-2 in bone remodeling has not been fully determined, in this study we examined whether endogenous FGF-2 was necessary for maximal effect of BMP-2 on periosteal bone formation in vivo and bone nodule formation and osteoclast formation in vitro in Fgf2-/- mice. We showed that BMP-2 significantly increased periosteal bone formation by 57% in Fgf2+/+ mice but the changes were not significant in Fgf2-/- littermates. In line with these results we found no significant increase in alkaline phosphatase positive (ALP) activity in calvarial osteoblasts or ALP mineralized colonies in stromal cultures from Fgf2-/- mice after BMP-2 treatment. Moreover, BMP-2 induced osteoclast formation was also impaired in marrow stromal cultures from Fgf2-/- mice. Interestingly, BMP-2 induced nuclear accumulation of the runt related transcription factor (Runx2) was markedly impaired in osteoblasts from Fgf2-/- mice. Examination of the effect of loss of FGF-2 on BMP-2 signaling pathway showed that BMP-2 caused a similar induction of phospho-Smad1/5/8 within 30 min in calvarial osteoblasts from both genotypes. In contrast BMP-2-induced p42/44 MAPK was reduced in Fgf2-/- mice. These findings strongly demonstrated that endogenous FGF-2 is important in the maximal responses of BMP-2 in bone and that this may be dependent on the p42/44 MAPK signaling pathway and downstream modulation of Runx2.
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Affiliation(s)
- Takahiro Naganawa
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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Sabbieti MG, Agas D, Materazzi S, Capacchietti M, Materazzi G, Hurley MM, Menghi G, Marchetti L. Prostaglandin F2alpha involves heparan sulphate sugar chains and FGFRs to modulate osteoblast growth and differentiation. J Cell Physiol 2008; 217:48-59. [PMID: 18459126 DOI: 10.1002/jcp.21471] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [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
The present investigation extends our previous studies on PGF2alpha-mediated signalling in osteoblast metabolism. In particular, the role of PGF2alpha as modulator of heparan sulphate proteoglycans (HSPGs), fibroblast growth factor 2 (FGF-2) and fibroblast growth factor receptors (FGFRs) was evaluated. We hereby reported the novel observation that PGF2alpha was able to promote the formation of HSPGs/FGF-2/FGFRs complexes. Moreover, our data suggested that PGF2alpha could induce new synthesis of heparan sulphate (HS) chains on osteoblasts by a mechanism involving a modulation of MAPK signalling and that HS is required for the regulation of FGF-2 induced by PGF2alpha. Indeed, a proteolytic cleavage of HSPGs with heparinase III (Hep III) prior to PGF2alpha administration down-regulated the basal expression of phospho-p44/42, likely inhibiting FGFRs tyrosine kinase activity. Interestingly, MAPK signalling influenced syntheses and subcellular localization of FGF-2, its specific receptor and HS. In addition, the proteolytic cleavage by Hep III and the MAPK kinase inhibition by PD-98059 also revealed that PGF2alpha induced cell proliferation is dependent on HSPGs and FGF-2 specific receptor, respectively. Of further relevance of this study, we demonstrated, by using a specific siRNA for FGFR1, that PGF2alpha modulates Runx2 expression by FGFR1 and HS.
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Affiliation(s)
- Maria Giovanna Sabbieti
- Department of Comparative Morphology and Biochemistry, University of Camerino, Camerino (MC), Italy
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Agas D, Marchetti L, Menghi G, Materazzi S, Materazzi G, Capacchietti M, Hurley MM, Sabbieti MG. Anti-apoptotic Bcl-2 enhancing requires FGF-2/FGF receptor 1 binding in mouse osteoblasts. J Cell Physiol 2007; 214:145-52. [PMID: 17559077 DOI: 10.1002/jcp.21170] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this study, we investigated the role of prostaglandin F2alpha (PGF2alpha) in mouse osteoblast survival and the function of fibroblast growth factor 2 (FGF-2) and fibroblast growth factor receptor 1 (FGFR1) in this process. In particular, for the first time, we demonstrated that PGF2alpha increased osteoblast survival in a dose-dependent manner and we showed that the effect is correlated with an increase in Bcl-2/Bax ratio. Furthermore, we demonstrated that PGF2alpha caused a decrement of the active caspases 9 and 3. By blocking FGF-2 with the specific neutralizing antibody and by depletion of FGFR1 gene with a specific siRNA, we showed that FGFR1 and FGF-2 are critical for the increment of Bcl-2/Bax ratio and the decrement of the active caspases 9 and 3, induced by PGF2alpha. Moreover, transmission electron microscopy studies showed that PGF2alpha increased binding of FGF-2 and FGFR1 and co-localization of reactive sites at plasma membrane level. In conclusion, we report a novel mechanism in which PGF2alpha induces FGF-2 binding to its specific cell surface receptor 1 leading to a cascade pathway that culminates with increased mouse osteoblast survival.
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Affiliation(s)
- Dimitrios Agas
- Department of Comparative Morphology and Biochemistry, University of Camerino, Camerino (MC), Italy
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Agas D, Sabbieti MG, Capacchietti M, Materazzi S, Menghi G, Materazzi G, Hurley MM, Marchetti L. Benzyl butyl phthalate influences actin distribution and cell proliferation in rat Py1a osteoblasts. J Cell Biochem 2007; 101:543-51. [PMID: 17171637 DOI: 10.1002/jcb.21212] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We previously reported that transient administration of phthalates induced actin cytoskeleton disruption in Py1a osteoblasts. However, the mechanism of this transient effect was not elucidated. In this study we provided evidence that the actin cytoskeletal re-established conditions are dependent on new actin expression and synthesis. To assess the role of phthalates in modulating the distribution of actin, confocal and electron microscopy studies were carried out. Results indicated a modification of actin distribution after phthalate administration. In addition, a relation with the nucleoskeletal component lamin A supports the hypothesis that phthalates may participate in regulatory cell processes involving actin in Py1a osteoblasts. The present study also supports the mitogenic effects of phthalates, which involve microfilament disruption, nuclear actin and lamin A. In particular, the increased levels of cyclin D3, which in mammalian cells plays a critical role in G1 to S transition and is a putative proto-oncogene in benzyl butyl phthalate treated cells, suggested a possible effect of the endocrine disruptor in cancer processes.
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Affiliation(s)
- Dimitrios Agas
- Department of Comparative Morphology and Biochemistry, University of Camerino, Camerino, MC, Italy
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Agas D, Marchetti L, Menghi G, Materazzi S, Materazzi G, Capacchietti M, Hurley MM, Sabbieti MG. Anti-apoptotic Bcl-2 enhancing requires FGF-2/FGF receptor 1 binding in mouse osteoblasts. J Cell Physiol 2007. [PMID: 17559077 DOI: 10.1002/jcp.21170.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this study, we investigated the role of prostaglandin F2alpha (PGF2alpha) in mouse osteoblast survival and the function of fibroblast growth factor 2 (FGF-2) and fibroblast growth factor receptor 1 (FGFR1) in this process. In particular, for the first time, we demonstrated that PGF2alpha increased osteoblast survival in a dose-dependent manner and we showed that the effect is correlated with an increase in Bcl-2/Bax ratio. Furthermore, we demonstrated that PGF2alpha caused a decrement of the active caspases 9 and 3. By blocking FGF-2 with the specific neutralizing antibody and by depletion of FGFR1 gene with a specific siRNA, we showed that FGFR1 and FGF-2 are critical for the increment of Bcl-2/Bax ratio and the decrement of the active caspases 9 and 3, induced by PGF2alpha. Moreover, transmission electron microscopy studies showed that PGF2alpha increased binding of FGF-2 and FGFR1 and co-localization of reactive sites at plasma membrane level. In conclusion, we report a novel mechanism in which PGF2alpha induces FGF-2 binding to its specific cell surface receptor 1 leading to a cascade pathway that culminates with increased mouse osteoblast survival.
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Affiliation(s)
- Dimitrios Agas
- Department of Comparative Morphology and Biochemistry, University of Camerino, Camerino (MC), Italy
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Marchetti L, Sabbieti MG, Agas D, Menghi M, Materazzi G, Menghi G, Hurley MM. PGF2alpha increases FGF-2 and FGFR2 trafficking in Py1a rat osteoblasts via clathrin independent and importin beta dependent pathway. J Cell Biochem 2006; 97:1379-92. [PMID: 16365892 DOI: 10.1002/jcb.20746] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Previous studies showed that prostaglandin F2alpha (PGF2alpha) stimulated fibroblast growth factor-2 (FGF-2) and fibroblast growth factor receptor 2 (FGFR2) cytosolic and nuclear accumulation, however, the endocytic pathway has not been elucidated. This study demonstrates that although PGF2alpha increased the formation of clathrin-coated structures in Py1a rat osteoblasts, they were not involved in FGF-2 and FGFR2 trafficking. PGF2alpha increased binding of FGF-2 and FGFR2 and co-localization of reactive sites in addition to nuclear translocation at the nuclear pore complex level. FGF-2 and FGFR2 were in close spatial correlation with importin beta, further supporting nuclear import of the FGF-2/FGFR2 complex. Immunogold and immunofluorescence techniques as well as Western blotting demonstrated increased importin beta protein labeling in response to PGF2alpha. Similar to PGF2alpha, phorbol 12-myristate 13-acetate (PMA) also increased importin beta protein. These data strongly suggest that prostaglandins may regulate osteoblast metabolism via FGF-2/FGFR2/importin beta nuclear trafficking.
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Affiliation(s)
- Luigi Marchetti
- Department of Comparative Morphology and Biochemistry, University of Camerino, Camerino (MC)/Italy.
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Affiliation(s)
- Marja M Hurley
- Department of Health Career Opportunity Programs at the University of Connecticut Health Center in Farmington, Connecticut, USA.
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Abstract
The first experimental mouse model for FGF2 in bone dysplasia was made serendipitously by overexpression of FGF from a constitutive promoter. The results were not widely accepted, rightfully drew skepticism, and were difficult to publish; because of over 2,000 studies published on FGF-2 at the time (1993), only a few reported a role of FGF-2 in bone growth and differentiation. However, mapping of human dwarfisms to mutations of the FGFRs shortly, thereafter, made the case that bone growth and remodeling was a major physiological function for FGF. Subsequent production of numerous transgenic and targeted null mice for several genes in the bone growth and remodeling pathways have marvelously elucidated the role of FGFs and their interactions with other genes. Indeed, studies of the FGF pathway present one of the best success stories for use of experimental genetics in functionally parsing morphogenetic regulatory pathways. What remains largely unresolved is the pleiotropic nature of FGF-2. How does it accelerate growth in one cell then stimulate apoptosis or retard growth for another cell in the same type of tissue? Some of the answers may come through distinguishing the FGF-2 protein isoforms, made from alternative translation start sites, these appear to have substantially different functions. Although we have made substantial progress, there is still much to be learned regarding FGF-2 as a most complex, enigmatic protein. Studies of genetic models in mice and human FGFR mutations have provided strong evidence that FGFRs are important modulators of osteoblast function during membranous bone formation. However, there is some controversy regarding the effects of FGFR signaling in human and murine genetic models. Although significant progress has been made in our understanding of FGFR signaling, several questions remain concerning the signaling pathways involved in osteoblast regulation by activated FGFR. Additionally, little is known about the specific role of FGFR target genes involved in cranial bone formation. These issues need to be addressed in future in in vitro and in vivo approaches to better understand the molecular mechanisms of action of FGFR signaling in osteoblasts that result in anabolic effects in bone formation.
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Affiliation(s)
- P J Marie
- Laboratory of Osteoblast Biology and Pathology, INSERM Unite 606, Hopital Lariboisiere, 2 rue Ambroise Pare, 75475 Paris Cedex 10, France
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Hurley MM, Okada Y, Xiao L, Tanaka Y, Ito M, Okimoto N, Nakamura T, Rosen CJ, Doetschman T, Coffin JD. Impaired bone anabolic response to parathyroid hormone in Fgf2-/- and Fgf2+/- mice. Biochem Biophys Res Commun 2006; 341:989-94. [PMID: 16455048 DOI: 10.1016/j.bbrc.2006.01.044] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 01/12/2006] [Indexed: 11/18/2022]
Abstract
Since parathyroid hormone (PTH) increased FGF2 mRNA and protein expression in osteoblasts, and serum FGF-2 was increased in osteoporotic patients treated with PTH, we assessed whether the anabolic effect of PTH was impaired in Fgf2-/- mice. Eight-week-old Fgf2+/+ and Fgf2-/- male mice were treated with rhPTH 1-34 (80mug/kg) for 4 weeks. Micro-CT and histomorphometry demonstrated that PTH significantly increased parameters of bone formation in femurs from Fgf2+/+ mice but the changes were smaller and not significant in Fgf2-/- mice. IGF-1 was significantly reduced in serum from PTH-treated Fgf2-/- mice. DEXA analysis of femurs from Fgf2+/+, Fgf2+/-, and Fgf2-/- mice treated with rhPTH (160mug/kg) for 10 days showed that PTH significantly increased femoral BMD in Fgf2+/+ by 18%; by only 3% in Fgf2+/- mice and reduced by 3% in Fgf2-/- mice. We conclude that endogenous Fgf2 is important for maximum bone anabolic effect of PTH in mice.
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Affiliation(s)
- M M Hurley
- University of Connecticut Health Center, Farmington, CT, USA.
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Naganawa T, Xiao L, Abogunde E, Sobue T, Kalajzic I, Sabbieti M, Agas D, Hurley MM. In vivo and in vitro comparison of the effects of FGF-2 null and haplo-insufficiency on bone formation in mice. Biochem Biophys Res Commun 2005; 339:490-8. [PMID: 16298332 DOI: 10.1016/j.bbrc.2005.10.215] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Accepted: 10/31/2005] [Indexed: 10/25/2022]
Abstract
We previously reported that deletion of the Fgf2 gene (Fgf2-/-) resulted in decreased bone mass in adult mice. This study examines the effect of haplo-insuffiency (Fgf2+/-) on bone loss in vertebrae from these mutant mice. Fgf2+/+ mice attained peak bone mass at 8-9 months of age. In contrast BMD was significantly reduced in vertebrae from adult (8-9) Fgf2+/- mice. Exogenous FGF-2 rescued reduced bone nodule formation in Fgf2+/- and Fgf2-/- cultures. Runx2 mRNA was reduced in cultures from Fgf2+/- and Fgf2-/- mice. FGF receptor2 mRNA and protein were markedly reduced in Fgf2+/- and Fgf2-/- mice. Decreased bone formation in Fgf2 mutant mice may correlate with impaired FGFR signaling, decreased Runx2 gene expression.
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Affiliation(s)
- T Naganawa
- Department of Medicine, University of Connecticut Health Center, Farmington, CT 06030-0524, USA
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Sobue T, Naganawa T, Xiao L, Okada Y, Tanaka Y, Ito M, Okimoto N, Nakamura T, Coffin JD, Hurley MM. Over-expression of fibroblast growth factor-2 causes defective bone mineralization and osteopenia in transgenic mice. J Cell Biochem 2005; 95:83-94. [PMID: 15723277 DOI: 10.1002/jcb.20389] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Over-expression of human FGF-2 cDNA linked to the phosphoglycerate kinase promoter in transgenic (TgFGF2) mice resulted in a dwarf mouse with premature closure of the growth plate and shortening of bone length. This study was designed to further characterize bone structure and remodeling in these mice. Bones of 1-6 month-old wild (NTg) and TgFGF2 mice were studied. FGF-2 protein levels were higher in bones of TgFGF2 mice. Bone mineral density was significantly decreased as early as 1 month in femurs from TgFGF2 mice compared with NTg mice. Micro-CT of trabecular bone of the distal femurs from 6-month-old TgFGF2 mice revealed significant reduction in trabecular bone volume, trabecular number (Tb.N), and increased trabecular separation (Tb.Sp). Osteoblast surface/bone surface, double-labeled surface, mineral apposition rate, and bone formation rates were all significantly reduced in TgFGF2 mice. There were fewer TRAP positive osteoclasts in calvaria from TgFGF2 mice. Quantitative histomorphometry showed that total bone area was similar in both genotypes, however percent osteoclast surface, and osteoclast number/bone surface were significantly reduced in TgFGF2 mice. Increased replication of TgFGF2 calvarial osteoblasts was observed and primary cultures of bone marrow stromal cells from TgFGF2 expressed markers of mature osteoblasts but formed fewer mineralized nodules. The data presented indicate that non-targeted over-expression of FGF-2 protein resulted in decreased endochondral and intramembranous bone formation. These results are consistent with FGF-2 functioning as a negative regulator of postnatal bone growth and remodeling in this animal model.
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Affiliation(s)
- T Sobue
- University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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