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Hopkins C, de Castro LF, Corsi A, Boyce A, Collins MT, Riminucci M, Heegaard AM. Fibrous dysplasia animal models: A systematic review. Bone 2022; 155:116270. [PMID: 34875396 DOI: 10.1016/j.bone.2021.116270] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/22/2021] [Accepted: 11/25/2021] [Indexed: 12/09/2022]
Abstract
BACKGROUND Fibrous dysplasia (FD) is a rare genetic bone disorder resulting in an overproduction of cAMP leading to a structurally unsound tissue, caused by a genetic mutation in the guanine nucleotide-binding protein gene (GNAS). In order to better understand this disease, several animal models have been developed with different strategies and features. OBJECTIVE Conduct a systematic review to analyze and compare animal models with the causative mutation and features of FD. METHODS A PRISMA search was conducted in Scopus, PubMed, and Web of Science. Studies reporting an in vivo model of FD that expressed the causative mutation were included for analysis. Models without the causative mutation, but developed an FD phenotype and models of FD cell implantation were included for subanalysis. RESULTS Seven unique models were identified. The models were assessed and compared for their face validity, construct validity, mosaicism, and induction methods. This was based on the features of clinical FD that were reported within the categories of: macroscopic features, imaging, histology and histomorphometry, histochemical and cellular markers, and blood/urine markers. LIMITATIONS None of the models reported all features of FD and some features were only reported in one model. This made comparing models a challenge, but indicates areas where further research is necessary. CONCLUSION The benefits and disadvantages of every model were assessed from a practical and scientific standpoint. While all published reports lacked complete data, the models have nonetheless informed our understanding of FD and provided meaningful information to guide researchers in bench and clinical research.
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Affiliation(s)
- Chelsea Hopkins
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Luis Fernandez de Castro
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Alessandro Corsi
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Alison Boyce
- Metabolic Bone Disorders Unit, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Michael T Collins
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Mara Riminucci
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Anne-Marie Heegaard
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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2
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Zhang L, Sugamori KS, Claridge C, Dela Cruz A, Grynpas MD, Mitchell J. Overexpression of Gα S in Murine Osteoblasts In Vivo Leads to Increased Bone Mass and Decreased Bone Quality. J Bone Miner Res 2017; 32:2171-2181. [PMID: 28727179 DOI: 10.1002/jbmr.3223] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 07/11/2017] [Accepted: 07/19/2017] [Indexed: 11/10/2022]
Abstract
GαS is a heterotrimeric G protein that transduces signals from activated G protein-coupled receptors on the cell surface to stimulate adenylyl cyclase/cyclic adenosine monophosphate (AMP) signaling. GαS plays a central role in mediating numerous growth and maintenance processes including osteogenesis and bone turnover. Decreased GαS expression or activating mutations in GαS both affect bone, suggesting that modulating GαS protein levels may be important for bone health and development. To examine the effects of increased osteoblastic GαS expression on bone development in vivo, we generated transgenic mice with GαS overexpression in osteoblasts (HOM-Gs mice) driven by the 3.6-kilobase (kb) Col1A1 promoter. Both male and female HOM-Gs mice exhibit increased bone turnover with overactive osteoblasts and osteoclasts, resulting in a high bone mass phenotype with significantly reduced bone quality. At 9 weeks of age, HOM-Gs mice have increased trabecular number, volumetric BMD (vBMD), and bone volume; however, the bone was woven and disorganized. There was also increased cortical bone volume despite an overall reduction in size in HOM-Gs mice along with increased cortical porosity and brittleness. The skeletal phenotype of HOM-Gs mice progressed into maturity at 26 weeks of age with further accrual of trabecular bone, whereas WT mice lost trabecular bone at this age. Although cortical bone volume and geometry were similar between mature HOM-Gs and WT mice, increased porosity persisted and the bone was weaker. At the cellular level, these alterations were mediated by an increase in bone resorption by osteoclasts and an overwhelmingly higher increase in bone formation by osteoblasts. In summary, our findings demonstrate that high osteoblastic GαS expression results in aberrant skeletal development in which bone production is favored at the cost of bone quality. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Lucia Zhang
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Kim S Sugamori
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Colin Claridge
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Ariana Dela Cruz
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Marc D Grynpas
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Jane Mitchell
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
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3
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Wang L, Roth T, Abbott M, Ho L, Wattanachanya L, Nissenson RA. Osteoblast-derived FGF9 regulates skeletal homeostasis. Bone 2017; 98:18-25. [PMID: 28189801 PMCID: PMC8474898 DOI: 10.1016/j.bone.2016.12.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 12/01/2016] [Accepted: 12/10/2016] [Indexed: 11/21/2022]
Abstract
FGF9 has complex and important roles in skeletal development and repair. We have previously observed that Fgf9 expression in osteoblasts (OBs) is regulated by G protein signaling and therefore the present study was done to determine whether OB-derived FGF9 was important in skeletal homeostasis. To directly test this idea, we deleted functional expression of Fgf9 gene in OBs using a 2.3kb collagen type I promoter-driven Cre transgenic mouse line (Fgf9OB-/-). Both Fgf9 knockout (Fgf9OB-/-) and the Fgf9 floxed littermates (Fgf9fl/fl) mice were fully backcrossed and maintained in an FBV/N background. Three month old Fgf9OB-/- mice displayed a significant decrease in cancellous bone and bone formation in the distal femur and a significant decrease in cortical thickness at the TFJ. Strikingly, female Fgf9OB-/- mice did not display altered bone mass. Continuous treatment of mouse BMSCs with exogenous FGF9 inhibited mouse BMSC mineralization while acute treatment increased the proliferation of progenitors, an effect requiring the activation of Akt1. Our results suggest that mature OBs are an important source of FGF9, positively regulating skeletal homeostasis in male mice. Osteoblast-derived FGF9 may serve a paracrine role to maintain the osteogenic progenitor cell population through activation of Akt signaling.
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Affiliation(s)
- Liping Wang
- Endocrine Unit, VA Medical Center, San Francisco, CA, USA; Department of Medicine, University of California, San Francisco, CA, USA
| | - Theresa Roth
- Endocrine Unit, VA Medical Center, San Francisco, CA, USA
| | - Marcia Abbott
- Endocrine Unit, VA Medical Center, San Francisco, CA, USA
| | - Linh Ho
- Endocrine Unit, VA Medical Center, San Francisco, CA, USA
| | - Lalita Wattanachanya
- Endocrine Unit, VA Medical Center, San Francisco, CA, USA; Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Thai Red Cross Society, Bangkok, Thailand; King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Robert A Nissenson
- Endocrine Unit, VA Medical Center, San Francisco, CA, USA; Department of Medicine, University of California, San Francisco, CA, USA.
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4
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Cain CJ, Valencia JT, Ho S, Jordan K, Mattingly A, Morales BM, Hsiao EC. Increased Gs Signaling in Osteoblasts Reduces Bone Marrow and Whole-Body Adiposity in Male Mice. Endocrinology 2016; 157:1481-94. [PMID: 26901092 PMCID: PMC4816728 DOI: 10.1210/en.2015-1867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/16/2016] [Indexed: 12/21/2022]
Abstract
Bone is increasingly recognized as an endocrine organ that can regulate systemic hormones and metabolism through secreted factors. Although bone loss and increased adiposity appear to be linked clinically, whether conditions of increased bone formation can also change systemic metabolism remains unclear. In this study, we examined how increased osteogenesis affects metabolism by using an engineered G protein-coupled receptor, Rs1, to activate Gs signaling in osteoblastic cells in ColI(2.3)(+)/Rs1(+) transgenic mice. We previously showed that these mice have dramatically increased bone formation resembling fibrous dysplasia of the bone. We found that total body fat was significantly reduced starting at 3 weeks of age. Furthermore, ColI(2.3)(+)/Rs1(+) mice showed reduced O2 consumption and respiratory quotient measures without effects on food intake and energy expenditure. The mice had significantly decreased serum triacylglycerides, leptin, and adiponectin. Resting glucose and insulin levels were unchanged; however, glucose and insulin tolerance tests revealed increased sensitivity to insulin. The mice showed resistance to fat accumulation from a high-fat diet. Furthermore, ColI(2.3)(+)/Rs1(+) mouse bones had dramatically reduced mature adipocyte differentiation, increased Wingless/Int-1 (Wnt) signaling, and higher osteoblastic glucose utilization than controls. These findings suggest that osteoblasts can influence both local and peripheral adiposity in conditions of increased bone formation and suggest a role for osteoblasts in the regulation of whole-body adiposity and metabolic homeostasis.
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Affiliation(s)
- Corey J Cain
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
| | - Joel T Valencia
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
| | - Samantha Ho
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
| | - Kate Jordan
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
| | - Aaron Mattingly
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
| | - Blanca M Morales
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
| | - Edward C Hsiao
- Department of Medicine, Division of Endocrinology and Metabolism; Institute for Human Genetics; and Program in Craniofacial Biology (C.J.C., S.H., K.J., A.M., B.M.M., and E.C.H.); and the Biomedical Sciences Graduate Program (J.T.V. and E.C.H.); University of California, San Francisco, San Francisco, California 94143-0794
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5
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Wang L, Hsiao EC, Lieu S, Scott M, O'Carroll D, Urrutia A, Conklin BR, Colnot C, Nissenson RA. Loss of Gi G-Protein-Coupled Receptor Signaling in Osteoblasts Accelerates Bone Fracture Healing. J Bone Miner Res 2015; 30:1896-904. [PMID: 25917236 DOI: 10.1002/jbmr.2540] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 04/08/2015] [Accepted: 04/21/2015] [Indexed: 12/24/2022]
Abstract
G-protein-coupled receptors (GPCRs) are key regulators of skeletal homeostasis and are likely important in fracture healing. Because GPCRs can activate multiple signaling pathways simultaneously, we used targeted disruption of G(i) -GPCR or activation of G(s) -GPCR pathways to test how each pathway functions in the skeleton. We previously demonstrated that blockade of G(i) signaling by pertussis toxin (PTX) transgene expression in maturing osteoblastic cells enhanced cortical and trabecular bone formation and prevented age-related bone loss in female mice. In addition, activation of G(s) signaling by expressing the G(s) -coupled engineered receptor Rs1 in maturing osteoblastic cells induced massive trabecular bone formation but cortical bone loss. Here, we test our hypothesis that the G(i) and G(s) pathways also have distinct functions in fracture repair. We applied closed, nonstabilized tibial fractures to mice in which endogenous G(i) signaling was inhibited by PTX, or to mice with activated G(s) signaling mediated by Rs1. Blockade of endogenous G(i) resulted in a smaller callus but increased bone formation in both young and old mice. PTX treatment decreased expression of Dkk1 and increased Lef1 mRNAs during fracture healing, suggesting a role for endogenous G(i) signaling in maintaining Dkk1 expression and suppressing Wnt signaling. In contrast, adult mice with activated Gs signaling showed a slight increase in the initial callus size with increased callus bone formation. These results show that G(i) blockade and G(s) activation of the same osteoblastic lineage cell can induce different biological responses during fracture healing. Our findings also show that manipulating the GPCR/cAMP signaling pathway by selective timing of G(s) and G(i) -GPCR activation may be important for optimizing fracture repair.
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Affiliation(s)
- Liping Wang
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA
| | - Edward C Hsiao
- Department of Medicine, the Program in Craniofacial Biology, and the Institute for Human Genetics, University of California, San Francisco, CA
| | - Shirley Lieu
- Department of Orthopedic Surgery, University of California, San Francisco General Hospital, Orthopaedic Trauma Institute, San Francisco, CA
| | - Mark Scott
- Department of Orthopedic Surgery, University of California, San Francisco General Hospital, Orthopaedic Trauma Institute, San Francisco, CA
| | - Dylan O'Carroll
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA
| | - Ashley Urrutia
- Department of Medicine, the Program in Craniofacial Biology, and the Institute for Human Genetics, University of California, San Francisco, CA
| | - Bruce R Conklin
- Department of Medicine, the Program in Craniofacial Biology, and the Institute for Human Genetics, University of California, San Francisco, CA.,Gladstone Institute of Cardiovascular Disease, San Francisco, CA.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA
| | - Celine Colnot
- Department of Orthopedic Surgery, University of California, San Francisco General Hospital, Orthopaedic Trauma Institute, San Francisco, CA.,Institut National de la Santé et de la Recherche Médicale (INSERM; National Institute of Health and Medical Research), Unités Mixtes de Recherche (UMR) 1163, Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris, France
| | - Robert A Nissenson
- Endocrine Research Unit, VA Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA
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Remoli C, Michienzi S, Sacchetti B, Consiglio AD, Cersosimo S, Spica E, Robey PG, Holmbeck K, Cumano A, Boyde A, Davis G, Saggio I, Riminucci M, Bianco P. Osteoblast-specific expression of the fibrous dysplasia (FD)-causing mutation Gsα(R201C) produces a high bone mass phenotype but does not reproduce FD in the mouse. J Bone Miner Res 2015; 30:1030-43. [PMID: 25487351 PMCID: PMC5526456 DOI: 10.1002/jbmr.2425] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/26/2014] [Accepted: 12/04/2014] [Indexed: 12/20/2022]
Abstract
We recently reported the generation and initial characterization of the first direct model of human fibrous dysplasia (FD; OMIM #174800), obtained through the constitutive systemic expression of one of the disease-causing mutations, Gsα(R201C) , in the mouse. To define the specific pathogenetic role(s) of individual cell types within the stromal/osteogenic system in FD, we generated mice expressing Gsα(R201C) selectively in mature osteoblasts using the 2.3kb Col1a1 promoter. We show here that this results in a striking high bone mass phenotype but not in a mimicry of human FD. The high bone mass phenotype involves specifically a deforming excess of cortical bone and prolonged and ectopic cortical bone remodeling. Expression of genes characteristic of late stages of bone cell differentiation/maturation is profoundly altered as a result of expression of Gsα(R201C) in osteoblasts, and expression of the Wnt inhibitor Sost is reduced. Although high bone mass is, in fact, a feature of some types/stages of FD lesions in humans, it is marrow fibrosis, localized loss of adipocytes and hematopoietic tissue, osteomalacia, and osteolytic changes that together represent the characteristic pathological profile of FD, as well as the sources of specific morbidity. None of these features are reproduced in mice with osteoblast-specific expression of Gsα(R201C) . We further show that hematopoietic progenitor/stem cells, as well as more mature cell compartments, and adipocyte development are normal in these mice. These data demonstrate that effects of Gsα mutations underpinning FD-defining tissue changes and morbidity do not reflect the effects of the mutations on osteoblasts proper.
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Affiliation(s)
- Cristina Remoli
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Stefano Michienzi
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | | | | | - Stefania Cersosimo
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Emanuela Spica
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Pamela G Robey
- Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
| | - Kenn Holmbeck
- Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
| | - Ana Cumano
- Lymphopoiesis Unit, INSERM, Pasteur Institute, Paris, France
| | - Alan Boyde
- Dental Physical Sciences, Queen Mary University of London, London, UK
| | - Graham Davis
- Dental Physical Sciences, Queen Mary University of London, London, UK
| | - Isabella Saggio
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, and IBPM CNR, Rome, Italy
| | - Mara Riminucci
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Paolo Bianco
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
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7
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Wattanachanya L, Wang L, Millard SM, Lu WD, O'Carroll D, Hsiao EC, Conklin BR, Nissenson RA. Assessing the osteoblast transcriptome in a model of enhanced bone formation due to constitutive Gs-G protein signaling in osteoblasts. Exp Cell Res 2015; 333:289-302. [PMID: 25704759 DOI: 10.1016/j.yexcr.2015.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/29/2015] [Accepted: 02/11/2015] [Indexed: 12/29/2022]
Abstract
G protein-coupled receptor (GPCR) signaling in osteoblasts (OBs) is an important regulator of bone formation. We previously described a mouse model expressing Rs1, an engineered constitutively active Gs-coupled GPCR, under the control of the 2.3 kb Col I promoter. These mice showed a dramatic age-dependent increase in trabecular bone of femurs. Here, we further evaluated the effects of enhanced Gs signaling in OBs on intramembranous bone formation by examining calvariae of 1- and 9-week-old Col1(2.3)/Rs1 mice and characterized the in vivo gene expression specifically occurring in osteoblasts with activated Gs G protein-coupled receptor signaling, at the cellular level rather than in a whole bone. Rs1 calvariae displayed a dramatic increase in bone volume with partial loss of cortical structure. By immunohistochemistry, Osterix was detected in cells throughout the inter-trabecular space while Osteocalcin was expressed predominantly in cells along bone surfaces, suggesting the role of paracrine mediators secreted from OBs driven by 2.3 kb Col I promoter could influence early OB commitment, differentiation, and/or proliferation. Gene expression analysis of calvarial OBs revealed that genes affected by Rs1 signaling include those encoding proteins important for cell differentiation, cytokines and growth factors, angiogenesis, coagulation, and energy metabolism. The set of Gs-GPCRs and other GPCRs that may contribute to the observed skeletal phenotype and candidate paracrine mediators of the effect of Gs signaling in OBs were also determined. Our results identify novel detailed in vivo cellular changes of the anabolic response of the skeleton to Gs signaling in mature OBs.
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Affiliation(s)
- Lalita Wattanachanya
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA; Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand.
| | - Liping Wang
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Susan M Millard
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Wei-Dar Lu
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Dylan O'Carroll
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
| | - Edward C Hsiao
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Francisco, CA, USA.
| | - Bruce R Conklin
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, USA; Department of Medicine, University of California, San Francisco, CA, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA.
| | - Robert A Nissenson
- Endocrine Research Unit, Veterans Affairs Medical Center and Departments of Medicine and Physiology, University of California, San Francisco, CA, USA.
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Saggio I, Remoli C, Spica E, Cersosimo S, Sacchetti B, Robey PG, Holmbeck K, Cumano A, Boyde A, Bianco P, Riminucci M. Constitutive expression of Gsα(R201C) in mice produces a heritable, direct replica of human fibrous dysplasia bone pathology and demonstrates its natural history. J Bone Miner Res 2014; 29:2357-68. [PMID: 24764158 PMCID: PMC4205271 DOI: 10.1002/jbmr.2267] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 04/07/2014] [Accepted: 04/15/2014] [Indexed: 12/24/2022]
Abstract
Fibrous dysplasia of bone (FD) is a crippling skeletal disease associated with postzygotic mutations (R201C, R201H) of the gene encoding the α subunit of the stimulatory G protein, Gs. By causing a characteristic structural subversion of bone and bone marrow, the disease results in deformity, hypomineralization, and fracture of the affected bones, with severe morbidity arising in childhood or adolescence. Lack of inheritance of the disease in humans is thought to reflect embryonic lethality of germline-transmitted activating Gsα mutations, which would only survive through somatic mosaicism. We have generated multiple lines of mice that express Gsα(R201C) constitutively and develop an inherited, histopathologically exact replica of human FD. Robust transgene expression in neonatal and embryonic tissues and embryonic stem (ES) cells were associated with normal development of skeletal tissues and differentiation of skeletal cells. As in humans, FD lesions in mice developed only in the postnatal life; a defined spatial and temporal pattern characterized the onset and progression of lesions across the skeleton. In individual bones, lesions developed through a sequence of three distinct histopathological stages: a primary modeling phase defined by endosteal/medullary excess bone formation and normal resorption; a secondary phase, with excess, inappropriate remodeling; and a tertiary fibrous dysplastic phase, which reproduced a full-blown replica of the human bone pathology in mice of age ≥1 year. Gsα mutations are sufficient to cause FD, and are per se compatible with germline transmission and normal embryonic development in mice. Our novel murine lines constitute the first model of FD.
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Affiliation(s)
- Isabella Saggio
- Department of Biology and Biotechnology "C. Darwin", Sapienza University, and IBPM CNR, Rome, Italy
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9
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Disrupted bone remodeling leads to cochlear overgrowth and hearing loss in a mouse model of fibrous dysplasia. PLoS One 2014; 9:e94989. [PMID: 24788917 PMCID: PMC4006800 DOI: 10.1371/journal.pone.0094989] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 03/20/2014] [Indexed: 02/05/2023] Open
Abstract
Normal hearing requires exquisite cooperation between bony and sensorineural structures within the cochlea. For example, the inner ear secretes proteins such as osteoprotegrin (OPG) that can prevent cochlear bone remodeling. Accordingly, diseases that affect bone regulation can also result in hearing loss. Patients with fibrous dysplasia develop trabecular bone overgrowth resulting in hearing loss if the lesions affect the temporal bones. Unfortunately, the mechanisms responsible for this hearing loss, which could be sensorineural and/or conductive, remain unclear. In this study, we used a unique transgenic mouse model of increased Gs G-protein coupled receptor (GPCR) signaling induced by expression of an engineered receptor, Rs1, in osteoblastic cells. These ColI(2.3)+/Rs1+ mice showed dramatic bone lesions that histologically and radiologically resembled fibrous dysplasia. We found that ColI(2.3)+/Rs1+ mice showed progressive and severe conductive hearing loss. Ossicular chain impingement increased with the size and number of dysplastic lesions. While sensorineural structures were unaffected, ColI(2.3)+/Rs1+ cochleae had abnormally high osteoclast activity, together with elevated tartrate resistant acid phosphatase (TRAP) activity and receptor activator of nuclear factor kappa-B ligand (Rankl) mRNA expression. ColI(2.3)+/Rs1+ cochleae also showed decreased expression of Sclerostin (Sost), an antagonist of the Wnt signaling pathway that normally increases bone formation. The osteocyte canalicular networks of ColI(2.3)+/Rs1+ cochleae were disrupted and showed abnormal osteocyte morphology. The osteocytes in the ColI(2.3)+/Rs1+ cochleae showed increased expression of matrix metalloproteinase 13 (MMP-13) and TRAP, both of which can support osteocyte-mediated peri-lacunar remodeling. Thus, while the ossicular chain impingement is sufficient to account for the progressive hearing loss in fibrous dysplasia, the deregulation of bone remodeling extends to the cochlea as well. Our findings suggest that factors regulating bone remodeling, including peri-lacunar remodeling by osteocytes, may be useful targets for treating the bony overgrowths and hearing changes of fibrous dysplasia and other bony pathologies.
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Salles JP, Laurencin-Dalicieux S, Conte-Auriol F, Briand-Mésange F, Gennero I. Bone defects in LPA receptor genetically modified mice. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:93-8. [PMID: 22867754 DOI: 10.1016/j.bbalip.2012.07.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/20/2012] [Accepted: 07/24/2012] [Indexed: 12/24/2022]
Abstract
LPA and LPA(1) have been shown to increase osteoblastic proliferation and differentiation as well as activation of osteoclasts. Cell and animal model studies have suggested that LPA is produced by bone cells and bone tissues. We obtained data from invalidated mice which support the hypothesis that LPA(1) is involved in bone development by promoting osteogenesis. LPA(1)-invalidated mice demonstrate growth and sternal and costal abnormalities, which highlights the specific roles of LPA(1) during bone development. Microcomputed tomography and histological analysis demonstrate osteoporosis in the trabecular and cortical bone of LPA(1)-invalidated mice. Moreover, bone marrow mesenchymal progenitors from these mice displayed decreased osteoblastic differentiation. Infrared analysis did not indicate osteomalacia in the bone tissue of LPA(1)-invalidated mice. LPA(1) displays opposite effects to LPA(4) on the related G proteins G(i) and G(s), responsible for decrease and increase of the cAMP level respectively, which itself is essential to the control of osteoblastic differentiation. The opposite effects of LPA(1) and LPA(4) during osteoblastic differentiation support the possibility that new pharmacological agents derived from the LPA pathways could be found and used in clinical practice to positively influence bone formation and treat osteoporosis. The paracrine effect of LPA is potentially modulated by its concentration in bone tissues, which may result from various intracellular and extracellular pathways. The relevance of LPA(1) in bone remodeling, as a receptor able to influence both osteoblast and osteoclast activity, still deserves further clarification. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.
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Affiliation(s)
- Jean Pierre Salles
- Unité d'Endocrinologie, Maladies Osseuses, Gynécologie et Génétique, Hôpital des Enfants, Toulouse University Hospital, Toulouse, France.
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Abstract
A significant challenge for neuroscientists is to determine how both electrical and chemical signals affect the activity of cells and circuits and how the nervous system subsequently translates that activity into behavior. Remote, bidirectional manipulation of those signals with high spatiotemporal precision is an ideal approach to addressing that challenge. Neuroscientists have recently developed a diverse set of tools that permit such experimental manipulation with varying degrees of spatial, temporal, and directional control. These tools use light, peptides, and small molecules to primarily activate ion channels and G protein-coupled receptors (GPCRs) that in turn activate or inhibit neuronal firing. By monitoring the electrophysiological, biochemical, and behavioral effects of such activation/inhibition, researchers can better understand the links between brain activity and behavior. Here, we review the tools that are available for this type of experimentation. We describe the development of the tools and highlight exciting in vivo data. We focus primarily on designer GPCRs (receptors activated solely by synthetic ligands, designer receptors exclusively activated by designer drugs) and microbial opsins (e.g., channelrhodopsin-2, halorhodopsin, Volvox carteri channelrhodopsin) but also describe other novel techniques that use orthogonal receptors, caged ligands, allosteric modulators, and other approaches. These tools differ in the direction of their effect (activation/inhibition, hyperpolarization/depolarization), their onset and offset kinetics (milliseconds/minutes/hours), the degree of spatial resolution they afford, and their invasiveness. Although none of these tools is perfect, each has advantages and disadvantages, which we describe, and they are all still works in progress. We conclude with suggestions for improving upon the existing tools.
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Affiliation(s)
- Sarah C Rogan
- University of North Carolina School of Medicine, Department of Pharmacology, 120 Mason Farm Rd, Chapel Hill, NC 27514, USA
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Hsiao EC, Nguyen TD, Ng JK, Scott MJ, Chang WC, Zahed H, Conklin BR. Constitutive Gs activation using a single-construct tetracycline-inducible expression system in embryonic stem cells and mice. Stem Cell Res Ther 2011; 2:11. [PMID: 21375737 PMCID: PMC3226282 DOI: 10.1186/scrt52] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Accepted: 03/04/2011] [Indexed: 01/19/2023] Open
Abstract
INTRODUCTION The controlled expression of many genes, including G-protein coupled receptors (GPCRs), is important for delineating gene functions in complex model systems. Binary systems for inducible regulation of transgene expression are widely used in mice. One system is the tTA/TRE expression system, composed of a tetracycline-dependent DNA binding factor and a separate tetracycline operon. However, the requirement for two separate transgenes (one for each tTA or TRE component) makes this system less amenable to models requiring directed cell targeting, increases the risk of multiple transgene integration sites, and requires extensive screening for appropriately-functioning clones. METHODS We developed a single, polycistronic tetracycline-inducible expression platform to control the expression of multiple cistrons in mammalian cells. This platform has three basic constructs: regulator, responder, and destination vectors. The modular platform is compatible with both the TetOff (tTA) and TetOn (rtTA) systems. The modular Gateway recombineering-compatible components facilitate rapidly generating vectors to genetically modify mammalian cells. We apply this system to use the elongation factor 1α (EF1α) promoter to drive doxycycline-regulated expression of both the fluorescent marker mCherry and an engineered Gs-coupled GPCR "Rs1" separated by a 2A ribosomal skip site. RESULTS We show that our combined expression construct drives expression of both the mCherry and Rs1 transgenes in a doxycycline-dependent manner. We successfully target the expression construct into the Rosa26 locus of mouse embryonic stem (ES) cells. Rs1 expression in mouse ES cells increases cAMP accumulation via both basal and ligand-induced Gs mechanisms and is associated with increased embryoid body size. Heterozygous mice carrying the Rs1 expression construct showed normal growth and weight, and developed small increases in bone formation that could be observed in the calvaria. CONCLUSIONS Our results demonstrate the feasibility of a single-vector strategy that combines both the tTA and TRE tetracycline-regulated components for use in cells and mouse models. Although the EF1α promoter is useful for driving expression in pluripotent cells, a single copy of the EF1α promoter did not drive high levels of mCherry and Rs1 expression in the differentiated tissues of adult mice. These findings indicate that promoter selection is an important factor when developing transgene expression models.
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Affiliation(s)
- Edward C Hsiao
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Division of Endocrinology and Metabolism, Department of Medicine, 400 Parnassus Ave., University of California, San Francisco, CA 94143-1222, USA
| | - Trieu D Nguyen
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Jennifer K Ng
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Mark J Scott
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Wei Chun Chang
- Department of Cellular and Molecular Pharmacology, 600 16th Street Rm. S-222, University of California, San Francisco, CA 94158-2140, USA
| | - Hengameh Zahed
- Gladstone Institute of Neurological Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Biomedical Sciences Graduate Program, 513 Parnassus Ave. Rm. HSE-1285, University of California, San Francisco, CA 94158-0505, USA
| | - Bruce R Conklin
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Department of Medicine, 505 Parnassus Ave., University of California, San Francisco, CA 94143, USA
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