1
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Birks S, Howard S, O'Rourke C, Thompson WR, Lau A, Uzer G. Osterix-driven LINC complex disruption in vivo diminishes osteogenesis at 8 weeks but not at 15 weeks. J Orthop Res 2024. [PMID: 38602438 DOI: 10.1002/jor.25849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 03/15/2024] [Accepted: 03/24/2024] [Indexed: 04/12/2024]
Abstract
The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex is a crucial connective component between the nuclear envelope and the cytoskeleton involving various cellular processes including nuclear positioning, nuclear architecture, and mechanotransduction. How LINC complexes regulate bone formation in vivo, however, is not well understood. To start bridging this gap, here we created a LINC disruption murine model using transgenic mice expressing Cre recombinase enzyme under the control of the Osterix (Osx-Cre) which is primarily active in pre-osteoblasts and floxed Tg(CAG-LacZ/EGFP-KASH2) mice. Tg(CAG-LacZ/EGFP-KASH2) mice contain a lox-STOP-lox flanked LacZ gene which is deleted upon cre recombination allowing for the overexpression of an EGFP-KASH2 fusion protein. This overexpressed protein disrupts endogenous Nesprin-Sun binding leading to disruption of LINC complexes. Thus, crossing these two lines results in an Osx- driven LINC disruption (ODLD) specific to pre-osteoblasts. In this study, we investigated how this LINC disruption affects exercise-induced bone accrual. ODLD cells had decreased osteogenic and adipogenic potential in vitro compared to non-disrupted controls and sedentary ODLD mice showed decreased bone quality at 8 weeks. Upon access to a voluntary running wheel, ODLD animals showed increased running time and distance; however, our 6-week exercise intervention did not significantly affect bone microarchitecture and bone mechanical properties.
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Affiliation(s)
- Scott Birks
- Micron School of Materials Science and Engineering, Boise State University, Boise, Idaho, USA
| | - Sean Howard
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, Idaho, USA
| | - Caroline O'Rourke
- Biomedical Engineering, The College of New Jersey, Ewing Township, New Jersey, USA
| | - William R Thompson
- Department of Physical Therapy, Indiana University, Bloomington, Indiana, USA
| | - Anthony Lau
- Biomedical Engineering, The College of New Jersey, Ewing Township, New Jersey, USA
| | - Gunes Uzer
- Department of Mechanical and Biomedical Engineering, Boise State University, Boise, Idaho, USA
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2
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Collins JM, Lang A, Parisi C, Moharrer Y, Nijsure MP, Thomas Kim JH, Ahmed S, Szeto GL, Qin L, Gottardi R, Dyment NA, Nowlan NC, Boerckel JD. YAP and TAZ couple osteoblast precursor mobilization to angiogenesis and mechanoregulation in murine bone development. Dev Cell 2024; 59:211-227.e5. [PMID: 38141609 PMCID: PMC10843704 DOI: 10.1016/j.devcel.2023.11.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 08/07/2023] [Accepted: 11/30/2023] [Indexed: 12/25/2023]
Abstract
Fetal bone development occurs through the conversion of avascular cartilage to vascularized bone at the growth plate. This requires coordinated mobilization of osteoblast precursors with blood vessels. In adult bone, vessel-adjacent osteoblast precursors are maintained by mechanical stimuli; however, the mechanisms by which these cells mobilize and respond to mechanical cues during embryonic development are unknown. Here, we show that the mechanoresponsive transcriptional regulators Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) spatially couple osteoblast precursor mobilization to angiogenesis, regulate vascular morphogenesis to control cartilage remodeling, and mediate mechanoregulation of embryonic murine osteogenesis. Mechanistically, YAP and TAZ regulate a subset of osteoblast-lineage cells, identified by single-cell RNA sequencing as vessel-associated osteoblast precursors, which regulate transcriptional programs that direct blood vessel invasion through collagen-integrin interactions and Cxcl12. Functionally, in 3D human cell co-culture, CXCL12 treatment rescues angiogenesis impaired by stromal cell YAP/TAZ depletion. Together, these data establish functions of the vessel-associated osteoblast precursors in bone development.
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Affiliation(s)
- Joseph M Collins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Annemarie Lang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cristian Parisi
- Department of Bioengineering, Imperial College London, London, UK
| | - Yasaman Moharrer
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Mechanical Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Madhura P Nijsure
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jong Hyun Thomas Kim
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Saima Ahmed
- Department of Bioengineering, Imperial College London, London, UK
| | | | - Ling Qin
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Riccardo Gottardi
- Department of Pediatrics, Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Nathaniel A Dyment
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Niamh C Nowlan
- Department of Bioengineering, Imperial College London, London, UK; School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland; UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Joel D Boerckel
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA; Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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3
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Ma C, Yu R, Li J, Chao J, Liu P. Targeting proteostasis network in osteoporosis: Pathological mechanisms and therapeutic implications. Ageing Res Rev 2023; 90:102024. [PMID: 37532006 DOI: 10.1016/j.arr.2023.102024] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 07/11/2023] [Accepted: 07/28/2023] [Indexed: 08/04/2023]
Abstract
As the most common bone disease, osteoporosis (OP) increases bone fragility and makes patients more vulnerable to the threat of osteoporotic fractures. With the ageing population in today's society, OP has become a huge and growing public health problem. Unfortunately, the clear pathogenesis of OP is still under exploration, and effective interventions are still scarce. Therefore, exploring new targets for pharmacological interventions to develop promising therapeutic drugs for OP is of great clinical value. Previous studies have shown that normal bone remodeling depends on proteostasis, whereas loss of proteostasis during ageing leads to the dysfunctional proteostasis network (PN) that fails to maintain bone homeostasis. Nevertheless, only a few studies have revealed the pathophysiological relationship between bone metabolism and a single component of PN, yet the role of PN as a whole in the pathogenesis of OP is still under investigation. This review comprehensively summarized the role of PN in the pathogenesis of OP and further discussed the potential of PN as innovative drug targets for the therapy of OP.
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Affiliation(s)
- Cong Ma
- Department of Orthopedics, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China; Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Ronghui Yu
- Department of Orthopedics, The First Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Junhong Li
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jiashuo Chao
- Department of Liver Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China
| | - Ping Liu
- Department of Orthopedics, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China.
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4
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Birks S, Howard S, O’Rourke C, Thompson WR, Lau A, Uzer G. Osterix-driven LINC complex disruption in vivo diminishes bone microarchitecture in 8-week male mice but not after 6-week voluntary wheel running. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554623. [PMID: 37662368 PMCID: PMC10473717 DOI: 10.1101/2023.08.24.554623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex is a crucial connective component between the nuclear envelope and the cytoskeleton involving various cellular processes including nuclear positioning, nuclear architecture, and mechanotransduction. How LINC complexes regulate bone formation in vivo, however, is not well understood. To start bridging this gap, here we created a LINC disruption murine model using transgenic mice expressing Cre recombinase enzyme under the control of the Osterix (Osx-Cre) which is primarily active in pre-osteoblasts and floxed Tg(CAG-LacZ/EGFP-KASH2) mice. Tg(CAG-LacZ/EGFP-KASH2) mice contain a lox-STOP-lox flanked LacZ gene which is deleted upon cre recombination allowing for the overexpression of an EGFP-KASH2 fusion protein. This overexpressed protein disrupts endogenous Nesprin-Sun binding leading to disruption of LINC complexes. Thus, crossing these two lines results in a Osx-driven LINC disruption (ODLD) specific to pre-osteoblasts. In this study, we investigated how this LINC disruption affects exercise induced bone accrual. ODLD cells had decreased osteogenic and adipogenic potential in vitro compared to non-disrupted controls and sedentary ODLD mice showed decreased bone quality at 8-weeks. Upon access to a voluntary running wheel ODLD animals showed increased running time and distance; however, our 6-week exercise intervention did not significantly affect bone microarchitecture and bone mechanical properties.
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Affiliation(s)
- Scott Birks
- Boise State University, Micron School of Materials Science and Engineering
| | - Sean Howard
- Boise State University, Mechanical and Biomedical Engineering
| | | | | | - Anthony Lau
- The College of New Jersey, Biomedical Engineering
| | - Gunes Uzer
- Boise State University, Mechanical and Biomedical Engineering
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5
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Cunningham CJ, Choi RB, Bullock WA, Robling AG. Perspective: The current state of Cre driver mouse lines in skeletal research: Challenges and opportunities. Bone 2023; 170:116719. [PMID: 36868507 PMCID: PMC10087282 DOI: 10.1016/j.bone.2023.116719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/15/2023] [Accepted: 02/19/2023] [Indexed: 03/04/2023]
Abstract
The Cre/Lox system has revolutionized the ability of biomedical researchers to ask very specific questions about the function of individual genes in specific cell types at specific times during development and/or disease progression in a variety of animal models. This is true in the skeletal biology field, and numerous Cre driver lines have been created to foster conditional gene manipulation in specific subpopulations of bone cells. However, as our ability to scrutinize these models increases, an increasing number of issues have been identified with most driver lines. All existing skeletal Cre mouse models exhibit problems in one or more of the following three areas: (1) cell type specificity-avoiding Cre expression in unintended cell types; (2) Cre inducibility-improving the dynamic range for Cre in inducible models (negligible Cre activity before induction and high Cre activity after induction); and (3) Cre toxicity-reducing the unwanted biological effects of Cre (beyond loxP recombination) on cellular processes and tissue health. These issues are hampering progress in understanding the biology of skeletal disease and aging, and consequently, identification of reliable therapeutic opportunities. Skeletal Cre models have not advanced technologically in decades despite the availability of improved tools, including multi-promoter-driven expression of permissive or fragmented recombinases, new dimerization systems, and alternative forms of recombinases and DNA sequence targets. We review the current state of skeletal Cre driver lines, and highlight some of the successes, failures, and opportunities to improve fidelity in the skeleton, based on successes pioneered in other areas of biomedical science.
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Affiliation(s)
- Connor J Cunningham
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Roy B Choi
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | | | - Alexander G Robling
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA; Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, IN, USA; Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, USA; Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA.
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6
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Swami S, Zhu H, Nisco A, Kimura T, Kim MJ, Nair V, Wu JY. Parathyroid hormone 1 receptor signaling mediates breast cancer metastasis to bone in mice. JCI Insight 2023; 8:157390. [PMID: 36692956 PMCID: PMC10077472 DOI: 10.1172/jci.insight.157390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
Bone metastases are a common complication of breast cancer. We have demonstrated that intermittent administration of parathyroid hormone (PTH[1-34]) reduces the incidence of bone metastases in murine models of breast cancer by acting on osteoblasts to alter the bone microenvironment. Here, we examined the role of signaling mediated by PTH 1 receptor (PTH1R) in both osteoblasts and breast cancer cells in influencing bone metastases. In mice with impaired PTH1R signaling in osteoblasts, intermittent PTH did not reduce bone metastasis. Intermittent PTH also did not reduce bone metastasis when expression of PTH1R was knocked down in 4T1 murine breast cancer cells by shRNA. In 4T1 breast cancer cells, PTH decreased expression of PTH-related protein (PTHrP), implicated in the vicious cycle of bone metastases. Knockdown of PTHrP in 4T1 cells significantly reduced migration toward MC3T3-E1 osteoblasts, and migration was further inhibited by treatment with intermittent PTH. Conversely, overexpression of PTHrP in 4T1 cells increased migration toward MC3T3-E1 osteoblasts, and this was not inhibited by PTH. In conclusion, PTH1R expression is crucial in both osteoblasts and breast cancer cells for PTH to reduce bone metastases, and in breast cancer cells, this may be mediated in part by suppression of PTHrP.
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Collins JM, Lang A, Parisi C, Moharrer Y, Nijsure MP, Kim JH(T, Szeto GL, Qin L, Gottardi RL, Dyment NA, Nowlan NC, Boerckel JD. YAP and TAZ couple osteoblast precursor mobilization to angiogenesis and mechanoregulated bone development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524918. [PMID: 36711590 PMCID: PMC9882292 DOI: 10.1101/2023.01.20.524918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Endochondral ossification requires coordinated mobilization of osteoblast precursors with blood vessels. During adult bone homeostasis, vessel adjacent osteoblast precursors respond to and are maintained by mechanical stimuli; however, the mechanisms by which these cells mobilize and respond to mechanical cues during embryonic development are unknown. Previously, we found that deletion of the mechanoresponsive transcriptional regulators, YAP and TAZ, from Osterix-expressing osteoblast precursors and their progeny caused perinatal lethality. Here, we show that embryonic YAP/TAZ signaling couples vessel-associated osteoblast precursor mobilization to angiogenesis in developing long bones. Osterix-conditional YAP/TAZ deletion impaired endochondral ossification in the primary ossification center but not intramembranous osteogenesis in the bone collar. Single-cell RNA sequencing revealed YAP/TAZ regulation of the angiogenic chemokine, Cxcl12, which was expressed uniquely in vessel-associated osteoblast precursors. YAP/TAZ signaling spatially coupled osteoblast precursors to blood vessels and regulated vascular morphogenesis and vessel barrier function. Further, YAP/TAZ signaling regulated vascular loop morphogenesis at the chondro-osseous junction to control hypertrophic growth plate remodeling. In human cells, mesenchymal stromal cell co-culture promoted 3D vascular network formation, which was impaired by stromal cell YAP/TAZ depletion, but rescued by recombinant CXCL12 treatment. Lastly, YAP and TAZ mediated mechanotransduction for load-induced osteogenesis in embryonic bone.
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Affiliation(s)
- Joseph M. Collins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Annemarie Lang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cristian Parisi
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Yasaman Moharrer
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Mechanical Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Madhura P. Nijsure
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jong Hyun (Thomas) Kim
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Ling Qin
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Riccardo L. Gottardi
- Department of Pediatrics, Division of Pulmonary Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Nathanial A. Dyment
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Niamh C. Nowlan
- Department of Bioengineering, Imperial College London, London, United Kingdom
- School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland
- UCD Conway Institute, University College Dublin, Dublin, Ireland
| | - Joel D. Boerckel
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
- Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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8
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Lu Z, Chen P, Xu Q, Li B, Jiang S, Jiang L, Zheng X. Constitutive and conditional gene knockout mice for the study of intervertebral disc degeneration: Current status, decision considerations, and future possibilities. JOR Spine 2023; 6:e1242. [PMID: 36994464 PMCID: PMC10041386 DOI: 10.1002/jsp2.1242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 12/13/2022] [Accepted: 12/22/2022] [Indexed: 01/09/2023] Open
Abstract
There have been an increasing number of patients with degenerative disc diseases due to the aging population. In light of this, studies on the pathogenesis of intervertebral disc degeneration have become a hot topic, and gene knockout mice have become a valuable tool in this field of research. With the development of science and technology, constitutive gene knockout mice can be constructed using homologous recombination, zinc finger nuclease, transcription activator-like effector nuclease technology and clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) system, and conditional gene knockout mice can be constructed using the Cre/LoxP system. The gene-edited mice using these techniques have been widely used in the studies on disc degeneration. This paper reviews the development process and principles of these technologies, functions of the edited genes in disc degeneration, advantages, and disadvantages of different methods and possible targets of the specific Cre recombinase in intervertebral discs. Recommendations for the choice of suitable gene-edited model mice are presented. At the same time, possible technological improvements in the future are also discussed.
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Affiliation(s)
- Ze‐Yu Lu
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Peng‐Bo Chen
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Qing‐Yin Xu
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Bo Li
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Sheng‐Dan Jiang
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Lei‐Sheng Jiang
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
| | - Xin‐Feng Zheng
- Spine Center Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai China
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Abstract
The tissue-resident skeletal stem cells (SSCs), which are self-renewal and multipotent, continuously provide cells (including chondrocytes, bone cells, marrow adipocytes, and stromal cells) for the development and homeostasis of the skeletal system. In recent decade, utilizing fluorescence-activated cell sorting, lineage tracing, and single-cell sequencing, studies have identified various types of SSCs, plotted the lineage commitment trajectory, and partially revealed their properties under physiological and pathological conditions. In this review, we retrospect to SSCs identification and functional studies. We discuss the principles and approaches to identify bona fide SSCs, highlighting pioneering findings that plot the lineage atlas of SSCs. The roles of SSCs and progenitors in long bone, craniofacial tissues, and periosteum are systematically discussed. We further focus on disputes and challenges in SSC research.
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10
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Awida Z, Hiram-Bab S, Bachar A, Saed H, Zyc D, Gorodov A, Ben-Califa N, Omari S, Omar J, Younis L, Iden JA, Graniewitz Visacovsky L, Gluzman I, Liron T, Raphael-Mizrahi B, Kolomansky A, Rauner M, Wielockx B, Gabet Y, Neumann D. Erythropoietin Receptor (EPOR) Signaling in the Osteoclast Lineage Contributes to EPO-Induced Bone Loss in Mice. Int J Mol Sci 2022; 23:ijms231912051. [PMID: 36233351 PMCID: PMC9570419 DOI: 10.3390/ijms231912051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 09/29/2022] [Accepted: 10/03/2022] [Indexed: 11/16/2022] Open
Abstract
Erythropoietin (EPO) is a pleiotropic cytokine that classically drives erythropoiesis but can also induce bone loss by decreasing bone formation and increasing resorption. Deletion of the EPO receptor (EPOR) on osteoblasts or B cells partially mitigates the skeletal effects of EPO, thereby implicating a contribution by EPOR on other cell lineages. This study was designed to define the role of monocyte EPOR in EPO-mediated bone loss, by using two mouse lines with conditional deletion of EPOR in the monocytic lineage. Low-dose EPO attenuated the reduction in bone volume (BV/TV) in Cx3cr1Cre EPORf/f female mice (27.05%) compared to controls (39.26%), but the difference was not statistically significant. To validate these findings, we increased the EPO dose in LysMCre model mice, a model more commonly used to target preosteoclasts. There was a significant reduction in both the increase in the proportion of bone marrow preosteoclasts (CD115+) observed following high-dose EPO administration and the resulting bone loss in LysMCre EPORf/f female mice (44.46% reduction in BV/TV) as compared to controls (77.28%), without interference with the erythropoietic activity. Our data suggest that EPOR in the monocytic lineage is at least partially responsible for driving the effect of EPO on bone mass.
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Affiliation(s)
- Zamzam Awida
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Sahar Hiram-Bab
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Almog Bachar
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Hussam Saed
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Dan Zyc
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Anton Gorodov
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Nathalie Ben-Califa
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Sewar Omari
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Jana Omar
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Liana Younis
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Jennifer Ana Iden
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Liad Graniewitz Visacovsky
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ida Gluzman
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tamar Liron
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Bitya Raphael-Mizrahi
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Albert Kolomansky
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Department of Medicine A, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6423906, Israel
| | - Martina Rauner
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, 01307 Dresden, Germany
| | - Ben Wielockx
- Institute for Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, 01307 Dresden, Germany
| | - Yankel Gabet
- Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Correspondence: (Y.G.); (D.N.); Tel.: +972-3-6407684 (Y.G.); +972-3-6407256 (D.N.)
| | - Drorit Neumann
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
- Correspondence: (Y.G.); (D.N.); Tel.: +972-3-6407684 (Y.G.); +972-3-6407256 (D.N.)
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11
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Ahmed R, Uppuganti S, Derasari S, Meyer J, Pennings JS, Elefteriou F, Nyman JS. Identifying Bone Matrix Impairments in a Mouse Model of Neurofibromatosis Type 1 (NF1) by Clinically Translatable Techniques. J Bone Miner Res 2022; 37:1603-1621. [PMID: 35690920 PMCID: PMC9378557 DOI: 10.1002/jbmr.4633] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 05/25/2022] [Accepted: 06/04/2022] [Indexed: 11/06/2022]
Abstract
Three-to-four percent of children with neurofibromatosis type 1 (NF1) present with unilateral tibia bowing, fracture, and recalcitrant healing. Alkaline phosphatase (ALP) enzyme therapy prevented poor bone mineralization and poor mechanical properties in mouse models of NF1 skeletal dysplasia; but transition to clinical trials is hampered by the lack of a technique that (i) identifies NF1 patients at risk of tibia bowing and fracture making them eligible for trial enrollment and (ii) monitors treatment effects on matrix characteristics related to bone strength. Therefore, we assessed the ability of matrix-sensitive techniques to provide characteristics that differentiate between cortical bone from mice characterized by postnatal loss of Nf1 in Osx-creTet-Off ;Nf1flox/flox osteoprogenitors (cKO) and from wild-type (WT) mice. Following euthanasia at two time points of bone disease progression, femur and tibia were harvested from both genotypes (n ≥ 8/age/sex/genotype). A reduction in the mid-diaphysis ultimate force during three-point bending at 20 weeks confirmed deleterious changes in bone induced by Nf1 deficiency, regardless of sex. Pooling females and males, low bound water (BW), and low cortical volumetric bone mineral density (Ct.vBMD) were the most accurate outcomes in distinguishing cKO from WT femurs with accuracy improving with age. Ct.vBMD and the average unloading slope (Avg-US) from cyclic reference point indentation tests were the most sensitive in differentiating WT from cKO tibias. Mineral-to-matrix ratio and carbonate substitution from Raman spectroscopy were not good classifiers. However, when combined with Ct.vBMD and BW (femur), they helped predict bending strength. Nf1 deficiency in osteoprogenitors negatively affected bone microstructure and matrix quality with deficits in properties becoming more pronounced with duration of Nf1 deficiency. Clinically measurable without ionizing radiation, BW and Avg-US are sensitive to deleterious changes in bone matrix in a preclinical model of NF1 bone dysplasia and require further clinical investigation as potential indicators of an onset of bone weakness in children with NF1. © 2022 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Rafay Ahmed
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.,Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sasidhar Uppuganti
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.,Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shrey Derasari
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Joshua Meyer
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Jacquelyn S Pennings
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.,Center for Musculoskeletal Research, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Florent Elefteriou
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Jeffry S Nyman
- Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.,Center for Bone Biology, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.,Center for Musculoskeletal Research, Vanderbilt University Medical Center, Nashville, TN, USA.,Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
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12
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Single-cell atlas of craniogenesis uncovers SOXC-dependent, highly proliferative, and myofibroblast-like osteodermal progenitors. Cell Rep 2022; 40:111045. [PMID: 35830813 PMCID: PMC9595211 DOI: 10.1016/j.celrep.2022.111045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 05/20/2022] [Accepted: 06/14/2022] [Indexed: 11/27/2022] Open
Abstract
The mammalian skull vault is essential to shape the head and protect the brain, but the cellular and molecular events underlying its development remain incompletely understood. Single-cell transcriptomic profiling from early to late mouse embryonic stages provides a detailed atlas of cranial lineages. It distinguishes various populations of progenitors and reveals a high expression of SOXC genes (encoding the SOX4, SOX11, and SOX12 transcription factors) early in development in actively proliferating and myofibroblast-like osteodermal progenitors. SOXC inactivation in these cells causes severe skull and skin underdevelopment due to the limited expansion of cell populations before and upon lineage commitment. SOXC genes enhance the expression of gene signatures conferring dynamic cellular and molecular properties, including actin cytoskeleton assembly, chromatin remodeling, and signaling pathway induction and responsiveness. These findings shed light onto craniogenic mechanisms and SOXC functions and suggest that similar mechanisms could decisively control many developmental, adult, pathological, and regenerative processes. Angelozzi and colleagues establish a detailed transcriptomic atlas of mouse embryonic craniogenesis and use mutant mice to show that SOXC (SOX4, SOX11, and SOX12 transcription factors) critically support osteogenesis and dermogenesis by promoting the expression of dynamic cellular and molecular properties of progenitor populations. SOXC could similarly affect many other processes.
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13
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Pierce JL, Sharma AK, Roberts RL, Yu K, Irsik DL, Choudhary V, Dorn JS, Bensreti H, Benson RD, Kaiser H, Khayrullin A, Davis C, Wehrle CJ, Johnson MH, Bollag WB, Hamrick MW, Shi X, Isales CM, McGee-Lawrence ME. The Glucocorticoid Receptor in Osterix-Expressing Cells Regulates Bone Mass, Bone Marrow Adipose Tissue, and Systemic Metabolism in Female Mice During Aging. J Bone Miner Res 2022; 37:285-302. [PMID: 34747055 PMCID: PMC9976194 DOI: 10.1002/jbmr.4468] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 09/23/2021] [Accepted: 10/17/2021] [Indexed: 12/18/2022]
Abstract
Hallmarks of aging-associated osteoporosis include bone loss, bone marrow adipose tissue (BMAT) expansion, and impaired osteoblast function. Endogenous glucocorticoid levels increase with age, and elevated glucocorticoid signaling, associated with chronic stress and dysregulated metabolism, can have a deleterious effect on bone mass. Canonical glucocorticoid signaling through the glucocorticoid receptor (GR) was recently investigated as a mediator of osteoporosis during the stress of chronic caloric restriction. To address the role of the GR in an aging-associated osteoporotic phenotype, the current study utilized female GR conditional knockout (GR-CKO; GRfl/fl :Osx-Cre+) mice and control littermates on the C57BL/6 background aged to 21 months and studied in comparison to young (3- and 6-month-old) mice. GR deficiency in Osx-expressing cells led to low bone mass and BMAT accumulation that persisted with aging. Surprisingly, however, GR-CKO mice also exhibited alterations in muscle mass (reduced % lean mass and soleus fiber size), accompanied by reduced voluntary physical activity, and also exhibited higher whole-body metabolic rate and elevated blood pressure. Moreover, increased lipid storage was observed in GR-CKO osteoblastic cultures in a glucocorticoid-dependent fashion despite genetic deletion of the GR, and could be reversed via pharmacological inhibition of the mineralocorticoid receptor (MR). These findings provide evidence of a role for the GR (and possibly the MR) in facilitating healthy bone maintenance with aging in females. The effects of GR-deficient bone on whole-body physiology also demonstrate the importance of bone as an endocrine organ and suggest evidence for compensatory mechanisms that facilitate glucocorticoid signaling in the absence of osteoblastic GR function; these represent new avenues of research that may improve understanding of glucocorticoid signaling in bone toward the development of novel osteogenic agents. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Jessica L Pierce
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Anuj K Sharma
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Rachel L Roberts
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Kanglun Yu
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Debra L Irsik
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA.,Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Vivek Choudhary
- Department of Physiology, Augusta University, Augusta, GA, USA
| | - Jennifer S Dorn
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Husam Bensreti
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Reginald D Benson
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Helen Kaiser
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Andrew Khayrullin
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Colleen Davis
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Chase J Wehrle
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Maribeth H Johnson
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA
| | - Wendy B Bollag
- Charlie Norwood VA Medical Center, Augusta, GA, USA.,Department of Physiology, Augusta University, Augusta, GA, USA
| | - Mark W Hamrick
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA
| | - Xingming Shi
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA
| | - Carlos M Isales
- Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA, USA
| | - Meghan E McGee-Lawrence
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, GA, USA.,Department of Orthopaedic Surgery, Augusta University, Augusta, GA, USA
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14
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Gomez GA, Rundle CH, Xing W, Kesavan C, Pourteymoor S, Lewis RE, Powell DR, Mohan S. Contrasting effects of <i>Ksr2</i>, an obesity gene, on trabecular bone volume and bone marrow adiposity. eLife 2022; 11:82810. [PMID: 36342465 PMCID: PMC9640193 DOI: 10.7554/elife.82810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 10/06/2022] [Indexed: 11/25/2022] Open
Abstract
Pathological obesity and its complications are associated with an increased propensity for bone fractures. Humans with certain genetic polymorphisms at the kinase suppressor of ras2 (KSR2) locus develop severe early-onset obesity and type 2 diabetes. Both conditions are phenocopied in mice with <i>Ksr2</i> deleted, but whether this affects bone health remains unknown. Here we studied the bones of global <i>Ksr2</i> null mice and found that <i>Ksr2</i> negatively regulates femoral, but not vertebral, bone mass in two genetic backgrounds, while the paralogous gene, <i>Ksr1</i>, was dispensable for bone homeostasis. Mechanistically, KSR2 regulates bone formation by influencing adipocyte differentiation at the expense of osteoblasts in the bone marrow. Compared with <i>Ksr2</i>'s known role as a regulator of feeding by its function in the hypothalamus, pair-feeding and osteoblast-specific conditional deletion of <i>Ksr2</i> reveals that <i>Ksr2</i> can regulate bone formation autonomously. Despite the gains in appendicular bone mass observed in the absence of <i>Ksr2</i>, bone strength, as well as fracture healing response, remains compromised in these mice. This study highlights the interrelationship between adiposity and bone health and provides mechanistic insights into how <i>Ksr2</i>, an adiposity and diabetic gene, regulates bone metabolism.
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Affiliation(s)
| | - Charles H Rundle
- VA Loma Linda Healthcare SystemLoma LindaUnited States,Loma Linda University Medical CenterLoma LindaUnited States
| | - Weirong Xing
- VA Loma Linda Healthcare SystemLoma LindaUnited States,Loma Linda University Medical CenterLoma LindaUnited States
| | - Chandrasekhar Kesavan
- VA Loma Linda Healthcare SystemLoma LindaUnited States,Loma Linda University Medical CenterLoma LindaUnited States
| | | | | | | | - Subburaman Mohan
- VA Loma Linda Healthcare SystemLoma LindaUnited States,Loma Linda University Medical CenterLoma LindaUnited States
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15
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Wirth F, Huck K, Lubosch A, Zoeller C, Ghura H, Porubsky S, Nakchbandi IA. Cdc42 in osterix-expressing cells alters osteoblast behavior and myeloid lineage commitment. Bone 2021; 153:116150. [PMID: 34400384 DOI: 10.1016/j.bone.2021.116150] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/06/2021] [Accepted: 08/09/2021] [Indexed: 01/05/2023]
Abstract
Osteoblasts are not only responsible for bone formation. They also support hematopoiesis. This requires responding to cues originating from several signaling pathways, a task performed by Rho GTPases. We therefore examined several transgenic mouse models and used inhibitors of Cdc42 in vitro. Deletion of Cdc42 in vivo using the Osterix promoter suppressed osteoblast function, while its deletion in differentiating osteoblasts using the Collagen-α1(I) promoter decreased osteoblast numbers. In both cases, bone mineral density diminished confirming the importance of Cdc42. Evaluation of hematopoiesis revealed that deletion of Cdc42 using the Osterix, but not the Collagen-α1(I) promoter increased the common myeloid progenitors (CMPs) in the bone marrow as well as the erythrocytes and the thrombocytes/platelets in peripheral blood. Causality between Cdc42 loss in early osteoblasts and increased myelopoiesis was confirmed in vitro. Work in vitro supported the conclusion that interleukin-4 mediated the increase in myelopoiesis. Thus, Cdc42 is required for healthy bone through regulation of bone formation in Osterix-expressing osteoblasts and the number of osteoblasts in differentiating osteoblasts. In addition, its expression in early osteoblasts/stromal cells modulates myelopoiesis. This highlights the importance of osteoblasts in regulating hematopoiesis.
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Affiliation(s)
- Franziska Wirth
- Institute of Immunology, University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Katrin Huck
- Institute of Immunology, University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Alexander Lubosch
- Institute of Immunology, University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Caren Zoeller
- Institute of Immunology, University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Hiba Ghura
- Institute of Immunology, University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Stefan Porubsky
- Institute of Pathology, University of Mainz, 55131 Mainz, Germany
| | - Inaam A Nakchbandi
- Institute of Immunology, University of Heidelberg, 69120 Heidelberg, Germany; Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany; Max-Planck Institute for Biochemistry, 82152 Martinsried, Germany.
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16
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STAT3 is critical for skeletal development and bone homeostasis by regulating osteogenesis. Nat Commun 2021; 12:6891. [PMID: 34824272 PMCID: PMC8616950 DOI: 10.1038/s41467-021-27273-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 10/19/2021] [Indexed: 11/08/2022] Open
Abstract
Skeletal deformities are typical AD-HIES manifestations, which are mainly caused by heterozygous and loss-of-function mutations in Signal transducer and activator of transcription 3 (STAT3). However, the mechanism is still unclear and the treatment strategy is limited. Herein, we reported that the mice with Stat3 deletion in osteoblasts, but not in osteoclasts, induced AD-HIES-like skeletal defects, including craniofacial malformation, osteoporosis, and spontaneous bone fracture. Mechanistic analyses revealed that STAT3 in cooperation with Msh homeobox 1(MSX1) drove osteoblast differentiation by promoting Distal-less homeobox 5(Dlx5) transcription. Furthermore, pharmacological activation of STAT3 partially rescued skeletal deformities in heterozygous knockout mice, while inhibition of STAT3 aggravated bone loss. Taken together, these data show that STAT3 is critical for modulating skeletal development and maintaining bone homeostasis through STAT3-indcued osteogenesis and suggest it may be a potential target for treatments.
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17
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Thomas JR, Sloan K, Cave K, Wallace JM, Roper RJ. Skeletal Deficits in Male and Female down Syndrome Model Mice Arise Independent of Normalized Dyrk1a Expression in Osteoblasts. Genes (Basel) 2021; 12:1729. [PMID: 34828335 PMCID: PMC8624983 DOI: 10.3390/genes12111729] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 01/11/2023] Open
Abstract
Trisomy 21 (Ts21) causes alterations in skeletal development resulting in decreased bone mass, shortened stature and weaker bones in individuals with Down syndrome (DS). There is a sexual dimorphism in bone mineral density (BMD) deficits associated with DS with males displaying earlier deficits than females. The relationships between causative trisomic genes, cellular mechanisms, and influence of sex in DS skeletal abnormalities remain unknown. One hypothesis is that the low bone turnover phenotype observed in DS results from attenuated osteoblast function, contributing to impaired trabecular architecture, altered cortical geometry, and decreased mineralization. DYRK1A, found in three copies in humans with DS, Ts65Dn, and Dp1Tyb DS model mice, has been implicated in the development of postnatal skeletal phenotypes associated with DS. Reduced copy number of Dyrk1a to euploid levels from conception in an otherwise trisomic Ts65Dn mice resulted in a rescue of appendicular bone deficits, suggesting DYRK1A contributes to skeletal development and homeostasis. We hypothesized that reduction of Dyrk1a copy number in trisomic osteoblasts would improve cellular function and resultant skeletal structural anomalies in trisomic mice. Female mice with a floxed Dyrk1a gene (Ts65Dn,Dyrk1afl/wt) were mated with male Osx-Cre+ (expressed in osteoblasts beginning around E13.5) mice, resulting in reduced Dyrk1a copy number in mature osteoblasts in Ts65Dn,Dyrk1a+/+/Osx-Cre P42 male and female trisomic and euploid mice, compared with littermate controls. Male and female Ts65Dn,Dyrk1a+/+/+ (3 copies of DYRK1A in osteoblasts) and Ts65Dn,Dyrk1a+/+/Osx-Cre (2 copies of Dyrk1a in osteoblasts) displayed similar defects in both trabecular architecture and cortical geometry, with no improvements with reduced Dyrk1a in osteoblasts. This suggests that trisomic DYRK1A does not affect osteoblast function in a cell-autonomous manner at or before P42. Although male Dp1Tyb and Ts65Dn mice exhibit similar skeletal deficits at P42 in both trabecular and cortical bone compartments between euploid and trisomic mice, female Ts65Dn mice exhibit significant cortical and trabecular deficits at P42, in contrast to an absence of genotype effect in female Dp1Tyb mice in trabecular bone. Taken together, these data suggest skeletal deficits in DS mouse models and are sex and age dependent, and influenced by strain effects, but are not solely caused by the overexpression of Dyrk1a in osteoblasts. Identifying molecular and cellular mechanisms, disrupted by gene dosage imbalance, that are involved in the development of skeletal phenotypes associated with DS could help to design therapies to rescue skeletal deficiencies seen in DS.
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Affiliation(s)
- Jared R. Thomas
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (J.R.T.); (K.S.); (K.C.)
| | - Kourtney Sloan
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (J.R.T.); (K.S.); (K.C.)
| | - Kelsey Cave
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (J.R.T.); (K.S.); (K.C.)
| | - Joseph M. Wallace
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA;
| | - Randall J. Roper
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (J.R.T.); (K.S.); (K.C.)
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18
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Rauner M, Murray M, Thiele S, Watts D, Neumann D, Gabet Y, Hofbauer LC, Wielockx B. Epo/EpoR signaling in osteoprogenitor cells is essential for bone homeostasis and Epo-induced bone loss. Bone Res 2021; 9:42. [PMID: 34518518 PMCID: PMC8437981 DOI: 10.1038/s41413-021-00157-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 03/05/2021] [Accepted: 04/20/2021] [Indexed: 11/09/2022] Open
Abstract
High erythropoietin (Epo) levels are detrimental to bone health in adult organisms. Adult mice receiving high doses of Epo lose bone mass due to suppressed bone formation and increased bone resorption. In humans, high serum Epo levels are linked to fractures in elderly men. Our earlier studies indicated that Epo modulates osteoblast activity; however, direct evidence that Epo acts via its receptor (EpoR) on osteoblasts in vivo is still missing. Here, we created mice lacking EpoR in osteoprogenitor cells to specifically address this gap. Deletion of EpoR in osteoprogenitors (EpoR:Osx-cre, cKO) starting at 5 weeks of age did not alter red blood cell parameters but increased vertebral bone volume by 25% in 12-week-old female mice. This was associated with low bone turnover. Histological (osteoblast number, bone formation rate) and serum (P1NP, osteocalcin) bone formation parameters were all reduced, as were the number of osteoclasts and TRAP serum level. Differentiation of osteoblast precursors isolated from cKO versus control mice resulted in lower expression of osteoblast marker genes including Runx2, Alp, and Col1a1 on day 21, whereas the mineralization capacity was similar. Moreover, the RANKL/OPG ratio, which determines the osteoclast-supporting potential of osteoblasts, was substantially decreased by 50%. Similarly, coculturing cKO osteoblasts with control or cKO osteoclast precursors produced significantly fewer osteoclasts than coculture with control osteoblasts. Finally, exposing female mice to Epo pumps (10 U·d−1) for 4 weeks resulted in trabecular bone loss (−25%) and increased osteoclast numbers (1.7-fold) in control mice only, not in cKO mice. Our data show that EpoR in osteoprogenitors is essential in regulating osteoblast function and osteoblast-mediated osteoclastogenesis via the RANKL/OPG axis. Thus, osteogenic Epo/EpoR signaling controls bone mass maintenance and contributes to Epo-induced bone loss.
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Affiliation(s)
- Martina Rauner
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany.
| | - Marta Murray
- Institute for Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden, Germany
| | - Sylvia Thiele
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Deepika Watts
- Institute for Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden, Germany
| | - Drorit Neumann
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yankel Gabet
- Department of Anatomy & Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lorenz C Hofbauer
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Ben Wielockx
- Institute for Clinical Chemistry and Laboratory Medicine, Technische Universität Dresden, Dresden, Germany.
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19
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Toth Z, Ward A, Tang SY, McBride-Gagyi S. Sexual differences in bone porosity, osteocyte density, and extracellular matrix organization due to osteoblastic-specific Bmp2 deficiency in mice. Bone 2021; 150:116002. [PMID: 33971313 PMCID: PMC8217247 DOI: 10.1016/j.bone.2021.116002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/26/2021] [Accepted: 05/05/2021] [Indexed: 12/01/2022]
Abstract
Clinical studies have come to conflicting conclusions regarding BMP2 deficiency's link to regulating bone mass and increasing fracture risk. This may be due to the signaling protein having sex- or age-dependent effects. Previous pre-clinical studies have supported a role, but have not adequately determined the physical mechanism causing altered bulk material properties. This study investigated the physical effects of Bmp2 ablation from osteogenic lineage cells (Osx-Cre; Bmp2fl/fl) in 10- and 15-week-old male and female mice. Bones collected post-mortem were subjected to fracture toughness testing, reference point indentation testing, microCT, and histological analysis to determine the multi-scale relationships between mechanical/material behavior and collagen production, collagen organization, and bone architecture. BMP2-deficient bones were smaller, more brittle, and contained more lacunae-scale voids and cortical pores. The cellular density was significantly increased and there were material-level differences measured by reference point indentation, independently of collagen fiber alignment or organization. The disparities in bone size and in bone fracture toughness between genotypes were especially striking in males at 15-weeks-old. Together, this study suggests that there are sex- and age-dependent effects of BMP2 deficiency. The results from both sexes also warrant further investigation into BMP2 deficiency's role in osteoblasts' transition to osteocytes and overall bone porosity.
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Affiliation(s)
- Zacharie Toth
- Department of Orthopaedic Surgery, Saint Louis University, St. Louis, MO, United States of America
| | - Ashley Ward
- Department of Orthopaedic Surgery, Saint Louis University, St. Louis, MO, United States of America
| | - Simon Y Tang
- Department of Orthopaedics, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Sarah McBride-Gagyi
- Department of Orthopaedic Surgery, Saint Louis University, St. Louis, MO, United States of America.
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20
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Couasnay G, Madel MB, Lim J, Lee B, Elefteriou F. Sites of Cre-recombinase activity in mouse lines targeting skeletal cells. J Bone Miner Res 2021; 36:1661-1679. [PMID: 34278610 DOI: 10.1002/jbmr.4415] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/12/2021] [Accepted: 07/15/2021] [Indexed: 12/22/2022]
Abstract
The Cre/Lox system is a powerful tool in the biologist's toolbox, allowing loss-of-function and gain-of-function studies, as well as lineage tracing, through gene recombination in a tissue-specific and inducible manner. Evidence indicates, however, that Cre transgenic lines have a far more nuanced and broader pattern of Cre activity than initially thought, exhibiting "off-target" activity in tissues/cells other than the ones they were originally designed to target. With the goal of facilitating the comparison and selection of optimal Cre lines to be used for the study of gene function, we have summarized in a single manuscript the major sites and timing of Cre activity of the main Cre lines available to target bone mesenchymal stem cells, chondrocytes, osteoblasts, osteocytes, tenocytes, and osteoclasts, along with their reported sites of "off-target" Cre activity. We also discuss characteristics, advantages, and limitations of these Cre lines for users to avoid common risks related to overinterpretation or misinterpretation based on the assumption of strict cell-type specificity or unaccounted effect of the Cre transgene or Cre inducers. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Greig Couasnay
- Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA
| | | | - Joohyun Lim
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Florent Elefteriou
- Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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21
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Liu Z, Hussien AA, Wang Y, Heckmann T, Gonzalez R, Karner CM, Snedeker JG, Gray RS. An adhesion G protein-coupled receptor is required in cartilaginous and dense connective tissues to maintain spine alignment. eLife 2021; 10:67781. [PMID: 34318745 PMCID: PMC8328515 DOI: 10.7554/elife.67781] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 07/22/2021] [Indexed: 12/11/2022] Open
Abstract
Adolescent idiopathic scoliosis (AIS) is the most common spine disorder affecting children worldwide, yet little is known about the pathogenesis of this disorder. Here, we demonstrate that genetic regulation of structural components of the axial skeleton, the intervertebral discs, and dense connective tissues (i.e., ligaments and tendons) is essential for the maintenance of spinal alignment. We show that the adhesion G protein-coupled receptor ADGRG6, previously implicated in human AIS association studies, is required in these tissues to maintain typical spine alignment in mice. Furthermore, we show that ADGRG6 regulates biomechanical properties of tendon and stimulates CREB signaling governing gene expression in cartilaginous tissues of the spine. Treatment with a cAMP agonist could mirror aspects of receptor function in culture, thus defining core pathways for regulating these axial cartilaginous and connective tissues. As ADGRG6 is a key gene involved in human AIS, these findings open up novel therapeutic opportunities for human scoliosis.
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Affiliation(s)
- Zhaoyang Liu
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, United States.,Department of Nutritional Sciences, The University of Texas at Austin, Austin, United States
| | - Amro A Hussien
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Yunjia Wang
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, United States.,Department of Spine Surgery and Orthopaedics, Xiangya Hospital, Central South University, Changsha, China
| | - Terry Heckmann
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, United States
| | - Roberto Gonzalez
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, United States
| | - Courtney M Karner
- Department of Internal Medicine, Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jess G Snedeker
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ryan S Gray
- Department of Pediatrics, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd, The University of Texas at Austin, Dell Medical School, Austin, United States.,Department of Nutritional Sciences, The University of Texas at Austin, Austin, United States
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22
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Skeletal Deformities in Osterix-Cre;Tgfbr2 f/f Mice May Cause Postnatal Death. Genes (Basel) 2021; 12:genes12070975. [PMID: 34202311 PMCID: PMC8307487 DOI: 10.3390/genes12070975] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/24/2021] [Accepted: 06/24/2021] [Indexed: 12/25/2022] Open
Abstract
Transforming growth factor β (TGFβ) signaling plays an important role in skeletal development. We previously demonstrated that the loss of TGFβ receptor II (Tgfbr2) in Osterix-Cre-expressing mesenchyme results in defects in bones and teeth due to reduced proliferation and differentiation in pre-osteoblasts and pre-odontoblasts. These Osterix-Cre;Tgfbr2f/f mice typically die within approximately four weeks for unknown reasons. To investigate the cause of death, we performed extensive pathological analysis on Osterix-Cre- (Cre-), Osterix-Cre+;Tgfbr2f/wt (HET), and Osterix-Cre+;Tgfbr2f/f (CKO) mice. We also crossed Osterix-Cre mice with the ROSA26mTmG reporter line to identify potential off-target Cre expression. The findings recapitulated published skeletal and tooth abnormalities and revealed previously unreported osteochondral dysplasia throughout both the appendicular and axial skeletons in the CKO mice, including the calvaria. Alterations to the nasal area and teeth suggest a potentially reduced capacity to sense and process food, while off-target Cre expression in the gastrointestinal tract may indicate an inability to absorb nutrients. Additionally, altered nasal passages and unexplained changes in diaphragmatic muscle support the possibility of hypoxia. We conclude that these mice likely died due to a combination of breathing difficulties, malnutrition, and starvation resulting primarily from skeletal deformities that decreased their ability to sense, gather, and process food.
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23
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Nieminen-Pihala V, Tarkkonen K, Laine J, Rummukainen P, Saastamoinen L, Nagano K, Baron R, Kiviranta R. Early B-cell Factor1 (Ebf1) promotes early osteoblast differentiation but suppresses osteoblast function. Bone 2021; 146:115884. [PMID: 33582307 DOI: 10.1016/j.bone.2021.115884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/22/2020] [Accepted: 02/09/2021] [Indexed: 11/17/2022]
Abstract
Early B cell factor 1 (Ebf1) is a transcription factor that regulates B cell, neuronal cell and adipocyte differentiation. We and others have shown that Ebf1 is expressed in osteoblasts and that global deletion of Ebf1 results in increased bone formation in vivo. However, as Ebf1 is expressed in multiple tissues and cell types, it has remained unclear, which of the phenotypic changes in bone are derived from bone cells. The aim of this study was to determine the cell-autonomous and differentiation stage-specific roles of Ebf1 in osteoblasts. In vitro, haploinsufficient Ebf1+/- calvarial cells showed impaired osteoblastic differentiation indicated by lower alkaline phosphatase (ALP) activity and reduced mRNA expression of osteoblastic genes, while overexpression of Ebf1 in wild type mouse calvarial cells led to enhanced osteoblast differentiation with increased expression of Osterix (Osx). We identified a putative Ebf1 binding site in the Osterix promoter by ChIP assay in MC3T3-E1 osteoblasts and showed that Ebf1 was able to activate Osx-luc reporter construct that included this Ebf1 binding site, suggesting that Ebf1 indeed regulates osteoblast differentiation by inducing Osterix expression. To reconcile our previous data and that of others with our novel findings, we hypothesized that Ebf1 could have a dual role in osteoblast differentiation promoting early but inhibiting late stages of differentiation and osteoblast function. To test this hypothesis in vivo, we generated conditional Ebf1 knockout mice, in which Ebf1 deletion was targeted to early or late osteoblasts by crossing Ebf1fl/fl mice with Osx- or Osteocalcin (hOC)-Cre mouse lines, respectively. Deletion of Ebf1 in early Ebf1Osx-/- osteoblasts resulted in significantly increased bone volume and trabecular number at 12 weeks by μCT analysis, while Ebf1hOC-/- mice did not have a bone phenotype. To conclude, our data demonstrate that Ebf1 promotes early osteoblast differentiation by regulating Osterix expression. However, Ebf1 inhibits bone accrual in the Osterix expressing osteoblasts in vivo but it is redundant in the maintenance of mature osteoblast function.
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Affiliation(s)
| | - Kati Tarkkonen
- Institute of Biomedicine, University of Turku, Turku, Finland
| | - Julius Laine
- Institute of Biomedicine, University of Turku, Turku, Finland
| | | | | | - Kenichi Nagano
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Harvard University, Boston, MA, USA
| | - Roland Baron
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Harvard University, Boston, MA, USA
| | - Riku Kiviranta
- Institute of Biomedicine, University of Turku, Turku, Finland; Department of Endocrinology, Division of Medicine, University of Turku and Turku University Hospital, Turku, Finland.
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24
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Biosse Duplan M, Dambroise E, Estibals V, Veziers J, Guicheux J, Legeai-Mallet L. An Fgfr3-activating mutation in immature murine osteoblasts affects the appendicular and craniofacial skeleton. Dis Model Mech 2021; 14:dmm048272. [PMID: 33737326 PMCID: PMC8084574 DOI: 10.1242/dmm.048272] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/03/2021] [Indexed: 12/17/2022] Open
Abstract
Achondroplasia (ACH), the most common form of dwarfism, is caused by a missense mutation in the gene coding for fibroblast growth factor receptor 3 (FGFR3). The resulting increase in FGFR3 signaling perturbs the proliferation and differentiation of chondrocytes (CCs), alters the process of endochondral ossification and thus reduces bone elongation. Increased FGFR3 signaling in osteoblasts (OBs) might also contribute to bone anomalies in ACH. In the present study of a mouse model of ACH, we sought to determine whether FGFR3 overactivation in OBs leads to bone modifications. The model carries an Fgfr3-activating mutation (Fgfr3Y367C/+) that accurately mimics ACH; we targeted the mutation to either immature OBs and hypertrophic CCs or to mature OBs by using the Osx-cre and collagen 1α1 (2.3 kb Col1a1)-cre mouse strains, respectively. We observed that Fgfr3 activation in immature OBs and hypertrophic CCs (Osx-Fgfr3) not only perturbed the hypertrophic cells of the growth plate (thus affecting long bone growth) but also led to osteopenia and low cortical thickness in long bones in adult (3-month-old) mice but not growing (3-week-old) mice. Importantly, craniofacial membranous bone defects were present in the adult mice. In contrast, activation of Fgfr3 in mature OBs (Col1-Fgfr3) had very limited effects on skeletal shape, size and micro-architecture. In vitro, we observed that Fgfr3 activation in immature OBs was associated with low mineralization activity. In conclusion, immature OBs appear to be affected by Fgfr3 overactivation, which might contribute to the bone modifications observed in ACH independently of CCs.
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Affiliation(s)
- Martin Biosse Duplan
- Laboratory of Molecular and Physiopathological Bases of Osteochondrodysplasia, INSERM UMR 1163, Imagine Institute, Paris 75015, France
- Université de Paris, Paris 75006, France
- Service de Médecine Bucco-Dentaire, Hôpital Bretonneau, AP-HP, Paris 75018, France
| | - Emilie Dambroise
- Laboratory of Molecular and Physiopathological Bases of Osteochondrodysplasia, INSERM UMR 1163, Imagine Institute, Paris 75015, France
- Université de Paris, Paris 75006, France
| | - Valentin Estibals
- Laboratory of Molecular and Physiopathological Bases of Osteochondrodysplasia, INSERM UMR 1163, Imagine Institute, Paris 75015, France
- Université de Paris, Paris 75006, France
| | - Joelle Veziers
- Inserm, UMR 1229, RMeS – Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France
- SC3M, SFR Santé F. Bonamy, FED 4203, UMS Inserm 016, CNRS 3556, Nantes F-44042, France
- CHU Nantes, PHU4 OTONN, Nantes, F-44093, France
| | - Jérome Guicheux
- Inserm, UMR 1229, RMeS – Regenerative Medicine and Skeleton, Université de Nantes, ONIRIS, Nantes, F-44042, France
- SC3M, SFR Santé F. Bonamy, FED 4203, UMS Inserm 016, CNRS 3556, Nantes F-44042, France
- CHU Nantes, PHU4 OTONN, Nantes, F-44093, France
| | - Laurence Legeai-Mallet
- Laboratory of Molecular and Physiopathological Bases of Osteochondrodysplasia, INSERM UMR 1163, Imagine Institute, Paris 75015, France
- Université de Paris, Paris 75006, France
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25
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Tangseefa P, Martin SK, Arthur A, Panagopoulos V, Page AJ, Wittert GA, Proud CG, Fitter S, Zannettino ACW. Deletion of Rptor in Preosteoblasts Reveals a Role for the Mammalian Target of Rapamycin Complex 1 (mTORC1) Complex in Dietary-Induced Changes to Bone Mass and Glucose Homeostasis in Female Mice. JBMR Plus 2021; 5:e10486. [PMID: 33977204 PMCID: PMC8101617 DOI: 10.1002/jbm4.10486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 02/22/2021] [Accepted: 02/28/2021] [Indexed: 12/11/2022] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) complex is the major nutrient sensor in mammalian cells that responds to amino acids, energy levels, growth factors, and hormones, such as insulin, to control anabolic and catabolic processes. We have recently shown that suppression of the mTORC1 complex in bone‐forming osteoblasts (OBs) improved glucose handling in male mice fed a normal or obesogenic diet. Mechanistically, this occurs, at least in part, by increasing OB insulin sensitivity leading to upregulation of glucose uptake and glycolysis. Given previously reported sex‐dependent differences observed upon antagonism of mTORC1 signaling, we investigated the metabolic and skeletal effects of genetic inactivation of preosteoblastic‐mTORC1 in female mice. Eight‐week‐old control diet (CD)‐fed Rptorob−/− mice had a low bone mass with a significant reduction in trabecular bone volume and trabecular number, reduced cortical bone thickness, and increased marrow adiposity. Despite no changes in body composition, CD‐fed Rptorob−/− mice exhibited significant lower fasting insulin and glucose levels and increased insulin sensitivity. Upon high‐fat diet (HFD) feeding, Rptorob−/− mice were resistant to a diet‐induced increase in whole‐body and total fat mass and protected from the development of diet‐induced insulin resistance. Notably, although 12 weeks of HFD increased marrow adiposity, with minimal changes in both trabecular and cortical bone in the female control mice, marrow adiposity was significantly reduced in HFD‐fed Rptorob−/− compared to both HFD‐fed control and CD‐fed Rptorob−/− mice. Collectively, our results demonstrate that mTORC1 function in preosteoblasts is crucial for skeletal development and skeletal regulation of glucose homeostasis in both male and female mice. Importantly, loss of mTORC1 function in OBs results in metabolic and physiological adaptations that mirror a caloric restriction phenotype (under CD) and protects against HFD‐induced obesity, associated insulin resistance, and marrow adiposity expansion. These results highlight the critical contribution of the skeleton in the regulation of whole‐body energy homeostasis. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Pawanrat Tangseefa
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Sally K Martin
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Agnieszka Arthur
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Vasilios Panagopoulos
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Amanda J Page
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Nutrition, Diabetes & Gut Health Program, Lifelong Health Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Gary A Wittert
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Nutrition, Diabetes & Gut Health Program, Lifelong Health Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia.,Freemasons Foundation Centre for Men's Health University of Adelaide Adelaide South Australia Australia
| | - Christopher G Proud
- Nutrition, Diabetes & Gut Health Program, Lifelong Health Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia.,School of Biological Sciences, University of Adelaide Adelaide South Australia Australia
| | - Stephen Fitter
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia
| | - Andrew C W Zannettino
- Adelaide Medical School, Faculty of Health and Medical Science University of Adelaide Adelaide South Australia Australia.,Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute Adelaide South Australia Australia.,Central Adelaide Local Health Network Adelaide South Australia Australia
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26
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Rothmund-Thomson Syndrome-Like RECQL4 Truncating Mutations Cause a Haploinsufficient Low-Bone-Mass Phenotype in Mice. Mol Cell Biol 2021; 41:e0059020. [PMID: 33361189 PMCID: PMC8088275 DOI: 10.1128/mcb.00590-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Rothmund-Thomson syndrome (RTS) is an autosomal recessive disorder characterized by defects in the skeletal system, such as bone hypoplasia, short stature, low bone mass, and an increased incidence of osteosarcoma. RTS type 2 patients have germ line compound biallelic protein-truncating mutations of RECQL4. As existing murine models employ Recql4 null alleles, we have attempted to more accurately model RTS by generating mice with patient-mimicking truncating Recql4 mutations. Truncating mutations impaired the stability and subcellular localization of RECQL4 and resulted in homozygous embryonic lethality and a haploinsufficient low-bone mass phenotype. Combination of a truncating mutation with a conditional Recql4 null allele demonstrated that the skeletal defects were intrinsic to the osteoblast lineage. However, the truncating mutations did not promote tumorigenesis. We utilized murine Recql4 null cells to assess the impact of human RECQL4 mutations using an in vitro complementation assay. While some mutations created unstable protein products, others altered subcellular localization of the protein. Interestingly, the severity of the phenotypes correlated with the extent of protein truncation. Collectively, our results reveal that truncating RECQL4 mutations in mice lead to an osteoporosis-like phenotype through defects in early osteoblast progenitors and identify RECQL4 gene dosage as a novel regulator of bone mass.
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27
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Yu S, Guo J, Sun Z, Lin C, Tao H, Zhang Q, Cui Y, Zuo H, Lin Y, Chen S, Liu H, Chen Z. BMP2-dependent gene regulatory network analysis reveals Klf4 as a novel transcription factor of osteoblast differentiation. Cell Death Dis 2021; 12:197. [PMID: 33608506 PMCID: PMC7895980 DOI: 10.1038/s41419-021-03480-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
Transcription factors (TFs) regulate the expression of target genes, inducing changes in cell morphology or activities needed for cell fate determination and differentiation. The BMP signaling pathway is widely regarded as one of the most important pathways in vertebrate skeletal biology, of which BMP2 is a potent inducer, governing the osteoblast differentiation of bone marrow stromal cells (BMSCs). However, the mechanism by which BMP2 initiates its downstream transcription factor cascade and determines the direction of differentiation remains largely unknown. In this study, we used RNA-seq, ATAC-seq, and animal models to characterize the BMP2-dependent gene regulatory network governing osteoblast lineage commitment. Sp7-Cre; Bmp2fx/fx mice (BMP2-cKO) were generated and exhibited decreased bone density and lower osteoblast number (n > 6). In vitro experiments showed that BMP2-cKO mouse bone marrow stromal cells (mBMSCs) had an impact on osteoblast differentiation and deficient cell proliferation. Osteogenic medium induced mBMSCs from BMP2-cKO mice and control were subjected to RNA-seq and ATAC-seq analysis to reveal differentially expressed TFs, along with their target open chromatin regions. Combined with H3K27Ac CUT&Tag during osteoblast differentiation, we identified 2338 BMP2-dependent osteoblast-specific active enhancers. Motif enrichment assay revealed that over 80% of these elements were directly targeted by RUNX2, DLX5, MEF2C, OASIS, and KLF4. We deactivated Klf4 in the Sp7 + lineage to validate the role of KLF4 in osteoblast differentiation of mBMSCs. Compared to the wild-type, Sp7-Cre; Klf4fx/+ mice (KLF4-Het) were smaller in size and had abnormal incisors resembling BMP2-cKO mice. Additionally, KLF4-Het mice had fewer osteoblasts and decreased osteogenic ability. RNA-seq and ATAC-seq revealed that KLF4 mainly "co-bound" with RUNX2 to regulate downstream genes. Given the significant overlap between KLF4- and BMP2-dependent NFRs and enriched motifs, our findings outline a comprehensive BMP2-dependent gene regulatory network specifically governing osteoblast differentiation of the Sp7 + lineage, in which Klf4 is a novel transcription factor.
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Affiliation(s)
- Shuaitong Yu
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jinqiang Guo
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Zheyi Sun
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Chujiao Lin
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Huangheng Tao
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Qian Zhang
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yu Cui
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Huanyan Zuo
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yuxiu Lin
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Shuo Chen
- Department of Developmental Dentistry, University of Texas Health Science Center, San Antonio, TX, USA
| | - Huan Liu
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China.
- Department of Periodontology, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
| | - Zhi Chen
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory for Oral Biomedicine of Ministry of Education (KLOBM), School and Hospital of Stomatology, Wuhan University, Wuhan, China.
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28
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Samsa WE, Mamidi MK, Hausman BS, Bashur LA, Greenfield EM, Zhou G. The master developmental regulator Jab1/Cops5/Csn5 is essential for proper bone growth and survival in mice. Bone 2021; 143:115733. [PMID: 33157284 PMCID: PMC7769967 DOI: 10.1016/j.bone.2020.115733] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/29/2020] [Accepted: 11/02/2020] [Indexed: 11/29/2022]
Abstract
Jab1, also known as Csn5/Cops5, is a key subunit of the COP9 Signalosome, a highly conserved macromolecular complex. We previously reported that the conditional knockout of Jab1 in mouse limb buds and chondrocytes results in severely shortened limbs and neonatal lethal chondrodysplasia, respectively. In this study, we further investigated the specific role of Jab1 in osteoblast differentiation and postnatal bone growth by characterizing a novel mouse model, the Osx-cre; Jab1flox/flox conditional knockout (Jab1 cKO) mouse, in which Jab1 is deleted in osteoblast precursor cells. Jab1 cKO mutant mice appeared normal at birth, but developed progressive dwarfism. Inevitably, all mutant mice died prior to weaning age. The histological and micro-computed tomography analysis of mutant long bones revealed severely altered bone microarchitecture, with a significant reduction in trabecular thickness. Moreover, Jab1 cKO mouse tibiae had a drastic decrease in mineralization near the epiphyseal growth plates, and Jab1 cKO mice also developed spontaneous fractures near the tibiofibular junction. Additionally, our cell culture studies demonstrated that Jab1 deletion in osteoblast precursors led to decreased mineralization and a reduced response to TGFβ and BMP signaling. Moreover, an unbiased reporter screen also identified decreased TGFβ activity in Jab1-knockdown osteoblasts. Thus, Jab1 is necessary for proper osteoblast differentiation and postnatal bone growth, likely in part through its positive regulation of the TGFβ and BMP signaling pathways in osteoblast progenitor cells.
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Affiliation(s)
- William E Samsa
- Department of Orthopaedics, Case Western Reserve University, Cleveland, OH 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Murali K Mamidi
- Department of Orthopaedics, Case Western Reserve University, Cleveland, OH 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Bryan S Hausman
- Department of Orthopaedics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Lindsay A Bashur
- Department of Orthopaedics, Case Western Reserve University, Cleveland, OH 44106, USA
| | | | - Guang Zhou
- Department of Orthopaedics, Case Western Reserve University, Cleveland, OH 44106, USA; Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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29
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Baddam P, Biancardi V, Roth DM, Eaton F, Thereza-Bussolaro C, Mandal R, Wishart DS, Barr A, MacLean J, Flores-Mir C, Pagliardini S, Graf D. Neural crest-specific deletion of Bmp7 leads to midfacial hypoplasia, nasal airway obstruction, and disordered breathing modelling Obstructive Sleep Apnea. Dis Model Mech 2021; 14:dmm.047738. [PMID: 33431521 PMCID: PMC7888714 DOI: 10.1242/dmm.047738] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022] Open
Abstract
Pediatric obstructive sleep apnea (OSA), a relatively common sleep-related breathing disorder (SRBD) affecting approximately 1-5% of children, is often caused by anatomical obstruction and/or collapse of the nasal and/or pharyngeal airways. The resulting sleep disruption and intermittent hypoxia lead to various systemic morbidities. Predicting the development of OSA from craniofacial features alone is currently not possible and a controversy remains if upper airway obstruction facilitates reduced midfacial growth or vice-versa. Currently, there is no rodent model that recapitulates both the development of craniofacial abnormalities and upper airway obstruction to address these questions. Here, we describe that mice with a neural crest-specific deletion of Bmp7 (Bmp7ncko) present with shorter, more acute angled cranial base, midfacial hypoplasia, nasal septum deviation, turbinate swelling and branching defects, and nasal airway obstruction. Interestingly, several of these craniofacial features develop after birth during periods of rapid midfacial growth and precede the development of an upper airway obstruction. We identified that in this rodent model, no single feature appeared to predict upper airway obstruction, but the sum of those features resulted in a reduced breathing frequency, apneas and overall reduced oxygen consumption. Metabolomics analysis of serum from peripheral blood identified increased levels of hydroxyproline, a metabolite upregulated under hypoxic conditions. As this model recapitulates many features observed in OSA, it offers unique opportunities for studying how upper airway obstruction affects breathing physiology and leads to systemic morbidities.
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Affiliation(s)
- Pranidhi Baddam
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Vivian Biancardi
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Equal contributions
| | - Daniela M Roth
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Equal contributions
| | - Farah Eaton
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Claudine Thereza-Bussolaro
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Department of Dentistry, Hospital dos Pinheiros, UNIFASIPE, Sinop, Mato Grosso, Brazil
| | - Rupasri Mandal
- The Metabolomics Innovation Centre, Department of Biological Sciences, Faculty of Science, University of Alberta, Edmonton, AB, Canada
| | - David S Wishart
- The Metabolomics Innovation Centre, Department of Biological Sciences, Faculty of Science, University of Alberta, Edmonton, AB, Canada
| | - Amy Barr
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Joanna MacLean
- Department of Pediatrics and the Women & Children's Health Research Institute, Faculty of Medicine and Dentistry, University of Alberta
- Stollery Children's Hospital; Edmonton, AB, Canada
| | - Carlos Flores-Mir
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Silvia Pagliardini
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Daniel Graf
- School of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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30
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Abstract
The Cre-LoxP technology permits gene ablation in specific cell lineages, at chosen differentiation stages of this lineage and in an inducible manner. It has allowed tremendous advances in our understanding of skeleton biology and related pathophysiological mechanisms, through the generation of loss/gain of function or cell tracing experiments based on the creation of an expanding toolbox of transgenic mice expressing the Cre recombinase in skeletal stem cells, chondrocytes, osteoblasts, or osteoclasts. In this chapter, we provide an overview of the different Cre-LoxP systems and Cre mouse lines used in the bone field, we discuss their advantages, limitations, and we outline best practices to interpret results obtained from the use of Cre mice.
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Affiliation(s)
- Florent Elefteriou
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
- Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA.
| | - Greig Couasnay
- Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, USA
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31
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Patra D, Kim J, Zhang Q, Tycksen E, Sandell LJ. Site-1 protease ablation in the osterix-lineage in mice results in bone marrow neutrophilia and hematopoietic stem cell alterations. Biol Open 2020; 9:bio052993. [PMID: 32576566 PMCID: PMC7328000 DOI: 10.1242/bio.052993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 04/24/2020] [Indexed: 01/03/2023] Open
Abstract
Site-1 protease (S1P) ablation in the osterix-lineage in mice drastically reduces bone development and downregulates bone marrow-derived skeletal stem cells. Here we show that these mice also suffer from spina bifida occulta with a characteristic lack of bone fusion in the posterior neural arches. Molecular analysis of bone marrow-derived non-red blood cell cells, via single-cell RNA-Seq and protein mass spectrometry, demonstrate that these mice have a much-altered bone marrow with a significant increase in neutrophils and Ly6C-expressing leukocytes. The molecular composition of bone marrow neutrophils is also different as they express more and additional members of the stefin A (Stfa) family of proteins. In vitro, recombinant Stfa1 and Stfa2 proteins have the ability to drastically inhibit osteogenic differentiation of bone marrow stromal cells, with no effect on adipogenic differentiation. FACS analysis of hematopoietic stem cells show that despite a decrease in hematopoietic stem cells, S1P ablation results in an increased production of granulocyte-macrophage progenitors, the precursors to neutrophils. These observations indicate that S1P has a role in the lineage specification of hematopoietic stem cells and/or their progenitors for development of a normal hematopoietic niche. Our study designates a fundamental requirement of S1P for maintaining a balanced regenerative capacity of the bone marrow niche.
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Affiliation(s)
- Debabrata Patra
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Joongho Kim
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Qiang Zhang
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Eric Tycksen
- McDonnell Genome Institute, Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Linda J Sandell
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
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32
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Tang J, Xie J, Chen W, Tang C, Wu J, Wang Y, Zhou XD, Zhou HD, Li YP. Runt-related transcription factor 1 is required for murine osteoblast differentiation and bone formation. J Biol Chem 2020; 295:11669-11681. [PMID: 32571873 DOI: 10.1074/jbc.ra119.007896] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/16/2020] [Indexed: 12/12/2022] Open
Abstract
Despite years of research investigating osteoblast differentiation, the mechanisms by which transcription factors regulate osteoblast maturation, bone formation, and bone homeostasis is still unclear. It has been reported that runt-related transcription factor 1 (Runx1) is expressed in osteoblast progenitors, pre-osteoblasts, and mature osteoblasts; yet, surprisingly, the exact function of RUNX1 in osteoblast maturation and bone formation remains unknown. Here, we generated and characterized a pre-osteoblast and differentiating chondrocyte-specific Runx1 conditional knockout mouse model to study RUNX1's function in bone formation. Runx1 ablation in osteoblast precursors and differentiating chondrocytes via osterix-Cre (Osx-Cre) resulted in an osteoporotic phenotype and decreased bone density in the long bones and skulls of Runx1f/fOsx-Cre mice compared with Runx1f/f and Osx-Cre mice. RUNX1 deficiency reduced the expression of SRY-box transcription factor 9 (SOX9), Indian hedgehog signaling molecule (IHH), Patched (PTC), and cyclin D1 in the growth plate, and also reduced the expression of osteocalcin (OCN), OSX, activating transcription factor 4 (ATF4), and RUNX2 in osteoblasts. ChIP assays and promoter activity mapping revealed that RUNX1 directly associates with the Runx2 gene promoter and up-regulates Runx2 expression. Furthermore, the ChIP data also showed that RUNX1 associates with the Ocn promoter. In conclusion, RUNX1 up-regulates the expression of Runx2 and multiple bone-specific genes, and plays an indispensable role in bone formation and homeostasis in both trabecular and cortical bone. We propose that stimulating Runx1 activity may be useful in therapeutic approaches for managing some bone diseases such as osteoporosis.
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Affiliation(s)
- Jun Tang
- Department of Metabolism & Endocrinology, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.,Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
| | - Jing Xie
- Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA.,The State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Wei Chen
- Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
| | - Chenyi Tang
- Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
| | - Jinjin Wu
- Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
| | - Yiping Wang
- Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
| | - Xue-Dong Zhou
- The State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, People's Republic of China
| | - Hou-De Zhou
- Department of Metabolism & Endocrinology, Hunan Provincial Key Laboratory of Metabolic Bone Diseases, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China
| | - Yi-Ping Li
- Department of Pathology, the University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA
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33
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Lim J, Li X, Yuan X, Yang S, Han L, Yang S. Primary cilia control cell alignment and patterning in bone development via ceramide-PKCζ-β-catenin signaling. Commun Biol 2020; 3:45. [PMID: 31988398 PMCID: PMC6985158 DOI: 10.1038/s42003-020-0767-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 12/16/2019] [Indexed: 02/01/2023] Open
Abstract
Intraflagellar transport (IFT) proteins are essential for cilia assembly and function. IFT protein mutations lead to ciliopathies, which manifest as variable skeletal abnormalities. However, how IFT proteins regulate cell alignment during bone development is unknown. Here, we show that the deletion of IFT20 in osteoblast lineage using Osterix-Cre and inducible type I Collagen-CreERT cause a compromised cell alignment and a reduced bone mass. This finding was validated by the disorganized collagen fibrils and decreased bone strength and stiffness in IFT20-deficient femurs. IFT20 maintains cilia and cell alignment in osteoblasts, as the concentric organization of three-dimensional spheroids was disrupted by IFT20 deletion. Mechanistically, IFT20 interacts with the ceramide-PKCζ complex to promote PKCζ phosphorylation in cilia and induce the apical localization of β-catenin in osteoblasts, both of which were disrupted in the absence of IFT20. These results reveal that IFT20 regulates polarity and cell alignment via ceramide-pPKCζ-β-catenin signaling during bone development.
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Affiliation(s)
- Jormay Lim
- Department of Anatomy and Cell Biology, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA
| | - Xinhua Li
- Department of Anatomy and Cell Biology, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA
| | - Xue Yuan
- Department of Oral Biology, State University of New York at Buffalo, School of Dental Medicine, Buffalo, NY, USA
| | - Shuting Yang
- Department of Anatomy and Cell Biology, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA
| | - Lin Han
- Department of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA 19104, USA
| | - Shuying Yang
- Department of Anatomy and Cell Biology, University of Pennsylvania, School of Dental Medicine, Philadelphia, PA 19104, USA.
- Department of Oral Biology, State University of New York at Buffalo, School of Dental Medicine, Buffalo, NY, USA.
- The Penn Center for Musculoskeletal Disorders, University of Pennsylvania, School of Medicine, Philadelphia, PA, 19104, USA.
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34
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Davis JL, Cox L, Shao C, Lyu C, Liu S, Aurora R, Veis DJ. Conditional Activation of NF-κB Inducing Kinase (NIK) in the Osteolineage Enhances Both Basal and Loading-Induced Bone Formation. J Bone Miner Res 2019; 34:2087-2100. [PMID: 31246323 PMCID: PMC6854278 DOI: 10.1002/jbmr.3819] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 05/29/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022]
Abstract
Studies from global loss-of-function mutants suggest that alternative NF-κB downstream of NF-κB inducing kinase (NIK) is a cell-intrinsic negative regulator of osteogenesis. However, the interpretation of the osteoblast and/or osteocyte contribution to the bone phenotype is complicated by simultaneous osteoclast defects in these models. Therefore, we turned to a transgenic mouse model to investigate the direct role of NIK in the osteolineage. Osx-Cre;NT3 animals (NT3-Cre +), which bear a constitutively active NIK allele (NT3) driven by Osx-Cre, were compared with their Cre-negative, Control (Ctrl) littermates. NT3-Cre + mice had elevated serum P1NP and CTX levels. Despite this high turnover state, µCT showed that constitutive activation of NIK resulted in a net increase in basal bone mass in both cortical and cancellous compartments. Furthermore, NT3-Cre + mice exhibited a greater anabolic response following mechanical loading compared with controls. We next performed RNA-Seq on nonloaded and loaded tibias to elucidate possible mechanisms underlying the increased bone anabolism seen in NT3-Cre + mice. Hierarchical clustering revealed two main transcriptional programs: one loading-responsive and the other NT3 transgene-driven. Gene ontology (GO) analysis indicated a distinct upregulation of receptor, kinase, and growth factor activities including Wnts, as well as a calcium-response signature in NT3-Cre + limbs. The promoters of these GO-term associated genes, including many known to be bone-anabolic, were highly enriched for multiple κB recognition elements (κB-RE) relative to the background frequency in the genome. The loading response in NT3-Cre + mice substantially overlapped (>90%) with Ctrl. Surprisingly, control animals had 10-fold more DEGs in response to loading. However, most top DEGs shared between genotypes had a high incidence of multiple κB-RE in their promoters. Therefore, both transcriptional programs (loading-responsive and NT3 transgene-driven) are modulated by NF-κB. Our studies uncover a previously unrecognized role for NF-κB in the promotion of both basal and mechanically stimulated bone formation. © 2019 American Society for Bone and Mineral Research.
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Affiliation(s)
- Jennifer L Davis
- Musculoskeletal Research Center, Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Linda Cox
- Musculoskeletal Research Center, Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Christine Shao
- Musculoskeletal Research Center, Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Cheng Lyu
- Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Shaopeng Liu
- Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Rajeev Aurora
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, MO, USA
| | - Deborah J Veis
- Musculoskeletal Research Center, Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Shriners Hospitals for Children-St. Louis, St. Louis, MO, USA
- Department of Patholgy, Washington University, School of Medicine, St. Louis, MO, USA
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35
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Li Z, Liu T, Gilmore A, Gómez NM, Mitchell CH, Li YP, Oursler MJ, Yang S. Regulator of G Protein Signaling Protein 12 (Rgs12) Controls Mouse Osteoblast Differentiation via Calcium Channel/Oscillation and Gαi-ERK Signaling. J Bone Miner Res 2019; 34:752-764. [PMID: 30489658 PMCID: PMC7675783 DOI: 10.1002/jbmr.3645] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 11/13/2018] [Accepted: 11/17/2018] [Indexed: 12/11/2022]
Abstract
Bone homeostasis intimately relies on the balance between osteoblasts (OBs) and osteoclasts (OCs). Our previous studies have revealed that regulator of G protein signaling protein 12 (Rgs12), the largest protein in the Rgs super family, is essential for osteoclastogenesis from hematopoietic cells and OC precursors. However, how Rgs12 regulates OB differentiation and function is still unknown. To understand that, we generated an OB-targeted Rgs12 conditional knockout (CKO) mice model by crossing Rgs12fl/fl mice with Osterix (Osx)-Cre transgenic mice. We found that Rgs12 was highly expressed in both OB precursor cells (OPCs) and OBs of wild-type (WT) mice, and gradually increased during OB differentiation, whereas Rgs12-CKO mice (OsxCre/+ ; Rgs12fl/fl ) exhibited a dramatic decrease in both trabecular and cortical bone mass, with reduced numbers of OBs and increased apoptotic cell population. Loss of Rgs12 in OPCs in vitro significantly inhibited OB differentiation and the expression of OB marker genes, resulting in suppression of OB maturation and mineralization. Further mechanism study showed that deletion of Rgs12 in OPCs significantly inhibited guanosine triphosphatase (GTPase) activity and cyclic adenosine monophosphate (cAMP) level, and impaired Calcium (Ca2+ ) oscillations via restraints of major Ca2+ entry sources (extracellular Ca2+ influx and intracellular Ca2+ release from endoplasmic reticulum), partially contributed by the blockage of L-type Ca2+ channel mediated Ca2+ influx. Downstream mediator extracellular signal-related protein kinase (ERK) was found inactive in OBs of OsxCre/+ ; Rgs12fl/fl mice and in OPCs after Rgs12 deletion, whereas application of pertussis toxin (PTX) or overexpression of Rgs12 could rescue the defective OB differentiation via restoration of ERK phosphorylation. Our findings reveal that Rgs12 is an important regulator during osteogenesis and highlight Rgs12 as a potential therapeutic target for bone disorders. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Ziqing Li
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Tongjun Liu
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
- Department of Implantology, Shandong Provincial Key Laboratory of Oral Biomedicine, School of Stomatology, Shandong University
- Department of Stomatology, the Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong province 250000, China
| | - Alyssa Gilmore
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
| | - Néstor Más Gómez
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Claire H Mitchell
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
- Department of Physiology, School of Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Yi-ping Li
- Department of Pathology, University of Alabama in Birmingham, Birmingham, AL 35294, USA
| | - Merry J Oursler
- Department of Medicine, Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Shuying Yang
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
- The Penn Center for Musculoskeletal Disorders, University of Pennsylvania Philadelphia, PA 19104, USA
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
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36
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Brommage R, Ohlsson C. High Fidelity of Mouse Models Mimicking Human Genetic Skeletal Disorders. Front Endocrinol (Lausanne) 2019; 10:934. [PMID: 32117046 PMCID: PMC7010808 DOI: 10.3389/fendo.2019.00934] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/23/2019] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The 2019 International Skeletal Dysplasia Society nosology update lists 441 genes for which mutations result in rare human skeletal disorders. These genes code for enzymes (33%), scaffolding proteins (18%), signal transduction proteins (16%), transcription factors (14%), cilia proteins (8%), extracellular matrix proteins (5%), and membrane transporters (4%). Skeletal disorders include aggrecanopathies, channelopathies, ciliopathies, cohesinopathies, laminopathies, linkeropathies, lysosomal storage diseases, protein-folding and RNA splicing defects, and ribosomopathies. With the goal of evaluating the ability of mouse models to mimic these human genetic skeletal disorders, a PubMed literature search identified 260 genes for which mutant mice were examined for skeletal phenotypes. These mouse models included spontaneous and ENU-induced mutants, global and conditional gene knockouts, and transgenic mice with gene over-expression or specific base-pair substitutions. The human X-linked gene ARSE and small nuclear RNA U4ATAC, a component of the minor spliceosome, do not have mouse homologs. Mouse skeletal phenotypes mimicking human skeletal disorders were observed in 249 of the 260 genes (96%) for which comparisons are possible. A supplemental table in spreadsheet format provides PubMed weblinks to representative publications of mutant mouse skeletal phenotypes. Mutations in 11 mouse genes (Ccn6, Cyp2r1, Flna, Galns, Gna13, Lemd3, Manba, Mnx1, Nsd1, Plod1, Smarcal1) do not result in similar skeletal phenotypes observed with mutations of the homologous human genes. These discrepancies can result from failure of mouse models to mimic the exact human gene mutations. There are no obvious commonalities among these 11 genes. Body BMD and/or radiologic dysmorphology phenotypes were successfully identified for 28 genes by the International Mouse Phenotyping Consortium (IMPC). Forward genetics using ENU mouse mutagenesis successfully identified 37 nosology gene phenotypes. Since many human genetic disorders involve hypomorphic, gain-of-function, dominant-negative and intronic mutations, future studies will undoubtedly utilize CRISPR/Cas9 technology to examine transgenic mice having genes modified to exactly mimic variant human sequences. Mutant mice will increasingly be employed for drug development studies designed to treat human genetic skeletal disorders. SIGNIFICANCE Great progress is being made identifying mutant genes responsible for human rare genetic skeletal disorders and mouse models for genes affecting bone mass, architecture, mineralization and strength. This review organizes data for 441 human genetic bone disorders with regard to heredity, gene function, molecular pathways, and fidelity of relevant mouse models to mimic the human skeletal disorders. PubMed weblinks to citations of 249 successful mouse models are provided.
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Affiliation(s)
- Robert Brommage
- Department of Internal Medicine and Clinical Nutrition, Centre for Bone and Arthritis Research, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- *Correspondence: Robert Brommage
| | - Claes Ohlsson
- Department of Internal Medicine and Clinical Nutrition, Centre for Bone and Arthritis Research, Institute of Medicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- Department of Drug Treatment, Sahlgrenska University Hospital, Gothenburg, Sweden
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37
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Choi HK, Yuan H, Fang F, Wei X, Liu L, Li Q, Guan JL, Liu F. Tsc1 Regulates the Balance Between Osteoblast and Adipocyte Differentiation Through Autophagy/Notch1/β-Catenin Cascade. J Bone Miner Res 2018; 33:2021-2034. [PMID: 29924882 PMCID: PMC6248888 DOI: 10.1002/jbmr.3530] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 06/07/2018] [Accepted: 06/17/2018] [Indexed: 01/14/2023]
Abstract
A reduction in trabecular bone mass is often associated with an increase in marrow fat in osteoporotic bones. The molecular mechanisms underlying this inverse correlation are incompletely understood. Here, we report that mice lacking tuberous sclerosis 1 (Tsc1) in Osterix-expressing cells had a significant decrease in trabecular bone mass characterized by decreased osteoblastogenesis, increased osteoclastogenesis, and increased bone marrow adiposity in vivo. In vitro study showed that Tsc1-deficient bone marrow stromal cells (BMSCs) had decreased proliferation, decreased osteogenic differentiation, and increased adipogenic differentiation in association with the downregulation of Wnt/β-catenin signaling. Mechanistically, TSC1 deficiency led to autophagy suppression and consequent Notch1 protein increase, which mediated the GSK3β-independent β-catenin degradation. Together, our results indicate that Tsc1 controls the balance between osteoblast and adipocyte differentiation of BMSCs. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Han Kyoung Choi
- Department of Biologic and Materials Sciences and Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Hebao Yuan
- Department of Biologic and Materials Sciences and Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Fang Fang
- Department of Biologic and Materials Sciences and Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Xiaoxi Wei
- Department of Biologic and Materials Sciences and Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
- Department of Orthodontics, Jilin University School and Hospital of Stomatology, Changchun, Jilin, China
| | - Lu Liu
- Department of Medicine, Division of Hematology/Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Qing Li
- Department of Medicine, Division of Hematology/Oncology, University of Michigan, Ann Arbor, MI, USA
| | - Jun-Lin Guan
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Fei Liu
- Department of Biologic and Materials Sciences and Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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38
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Martin SK, Fitter S, El Khawanky N, Grose RH, Walkley CR, Purton LE, Ruegg MA, Hall MN, Gronthos S, Zannettino ACW. mTORC1 plays an important role in osteoblastic regulation of B-lymphopoiesis. Sci Rep 2018; 8:14501. [PMID: 30266921 PMCID: PMC6162303 DOI: 10.1038/s41598-018-32858-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 09/17/2018] [Indexed: 01/05/2023] Open
Abstract
Skeletal osteoblasts are important regulators of B-lymphopoiesis, serving as a rich source of factors such as CXCL12 and IL-7 which are crucial for B-cell development. Recent studies from our laboratory and others have shown that deletion of Rptor, a unique component of the mTORC1 nutrient-sensing complex, early in the osteoblast lineage development results in defective bone development in mice. In this study, we now demonstrate that mTORC1 signalling in pre-osteoblasts is required for normal B-lymphocyte development in mice. Targeted deletion of Rptor in osterix-expressing pre-osteoblasts (Rptorob-/-) leads to a significant reduction in the number of B-cells in the bone marrow, peripheral blood and spleen at 4 and 12 weeks of age. Rptorob-/- mice also exhibit a significant reduction in pre-B and immature B-cells in the BM, indicative of a block in B-cell development from the pro-B to pre-B cell stage. Circulating levels of IL-7 and CXCL12 are also significantly reduced in Rptorob-/- mice. Importantly, whilst Rptor-deficient osteoblasts are unable to support HSC differentiation to B-cells in co-culture, this can be rescued by the addition of exogenous IL-7 and CXCL12. Collectively, these findings demonstrate that mTORC1 plays an important role in extrinsic osteoblastic regulation of B-cell development.
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Affiliation(s)
- Sally K Martin
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia.,The South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Stephen Fitter
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia.,The South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Nadia El Khawanky
- The South Australian Health and Medical Research Institute, Adelaide, Australia.,School of Medicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia.,Department of Hematology and Oncology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Randall H Grose
- The South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Carl R Walkley
- Stem Cell Regulation Unit, St Vincent's Institute of Medical Research, Melbourne, Australia
| | - Louise E Purton
- Stem Cell Regulation Unit, St Vincent's Institute of Medical Research, Melbourne, Australia
| | | | | | - Stan Gronthos
- The South Australian Health and Medical Research Institute, Adelaide, Australia.,Mesenchymal Stem Cell Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia
| | - Andrew C W Zannettino
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia. .,The South Australian Health and Medical Research Institute, Adelaide, Australia.
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Abstract
PURPOSE Transgenic Cre lines are a valuable tool for conditionally inactivating or activating genes to understand their function. Here, we provide an overview of Cre transgenic models used for studying gene function in bone cells and discuss their advantages and limitations, with particular emphasis on Cre lines used for studying osteocyte and osteoclast function. RECENT FINDINGS Recent studies have shown that many bone cell-targeted Cre models are not as specific as originally thought. To ensure accurate data interpretation, it is important for investigators to test for unexpected recombination events due to transient expression of Cre recombinase during development or in precursor cells and to be aware of the potential for germ line recombination of targeted genes as well as the potential for unexpected phenotypes due to the Cre transgene. Although many of the bone-targeted Cre-deleter strains are imperfect and each model has its own limitations, their careful use will continue to provide key advances in our understanding of bone cell function in health and disease.
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Affiliation(s)
- Sarah L Dallas
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, 650 E. 25th Street, Kansas, MO, 64108, USA.
| | - Yixia Xie
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, 650 E. 25th Street, Kansas, MO, 64108, USA
| | - Lora A Shiflett
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, 650 E. 25th Street, Kansas, MO, 64108, USA
| | - Yasuyoshi Ueki
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, 650 E. 25th Street, Kansas, MO, 64108, USA
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40
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Xiong J, Almeida M, O'Brien CA. The YAP/TAZ transcriptional co-activators have opposing effects at different stages of osteoblast differentiation. Bone 2018; 112:1-9. [PMID: 29626544 PMCID: PMC5970058 DOI: 10.1016/j.bone.2018.04.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 03/26/2018] [Accepted: 04/04/2018] [Indexed: 01/06/2023]
Abstract
The related transcriptional co-factors YAP (Yes-associated protein) and TAZ (transcriptional co-activator with PDZ-binding motif) have been proposed to either promote or inhibit osteoblast differentiation. Here we investigated the skeletal consequences of deleting YAP and TAZ at different stages of the osteoblast lineage using Prx1-Cre, Osx1-Cre, and Dmp1-Cre transgenic mice. Prx1-Cre-mediated deletion resulted in embryonic lethality. Mice lacking both copies of TAZ and one copy of YAP in cells targeted by Prx1-Cre were viable and displayed elevated bone mass associated increased bone formation. Deletion of YAP and TAZ using Osx1-Cre mice led to perinatal lethality. Suppression of Osx1-Cre activity until 21 days of age permitted postnatal deletion of YAP and TAZ, which resulted in increased osteoblast number at 12 weeks of age but no change in bone mass. Mechanistic studies revealed that YAP and TAZ suppress canonical Wnt signaling and Runx2 activity in osteoblast progenitors. Consistent with this, deletion of YAP and TAZ from osteoprogenitor cells increased osteoblast differentiation in vitro. Deletion of YAP and TAZ from mature osteoblasts and osteocytes using Dmp1-Cre mice led to reduced osteoblast number and bone formation, as well as increased osteoclast number, but no changes in known regulators of bone turnover such as RANKL, OPG, and Sost. Together these results suggest that YAP and TAZ in osteoblast progenitors oppose differentiation towards the osteoblast lineage but in mature osteoblasts and osteocytes, they promote bone formation and inhibit bone resorption.
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Affiliation(s)
- Jinhu Xiong
- Department of Orthopaedic Surgery, Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, AR, United States; Central Arkansas Veterans Healthcare System, Little Rock, AR, United States.
| | - Maria Almeida
- Department of Orthopaedic Surgery, Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, AR, United States; Central Arkansas Veterans Healthcare System, Little Rock, AR, United States
| | - Charles A O'Brien
- Department of Orthopaedic Surgery, Center for Musculoskeletal Disease Research, University of Arkansas for Medical Sciences, Little Rock, AR, United States; Central Arkansas Veterans Healthcare System, Little Rock, AR, United States
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41
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Patra D, DeLassus E, Mueller J, Abou-Ezzi G, Sandell LJ. Site-1 protease regulates skeletal stem cell population and osteogenic differentiation in mice. Biol Open 2018; 7:bio.032094. [PMID: 29437042 PMCID: PMC5861364 DOI: 10.1242/bio.032094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Site-1 protease (S1P) is a proprotein convertase with essential functions in the conversion of precursor proteins to their active form. In earlier studies, we demonstrated that S1P ablation in the chondrocyte lineage results in a drastic reduction in endochondral bone formation. To investigate the mechanistic contribution of S1P to bone development we ablated S1P in the osterix lineage in mice. S1P ablation in this lineage results in osteochondrodysplasia and variable degrees of early postnatal scoliosis. Embryonically, even though Runx2 and osterix expression are normal, S1P ablation results in a delay in vascular invasion and endochondral bone development. Mice appear normal when born, but by day 7 display pronounced dwarfism with fragile bones that exhibit significantly reduced mineral density, mineral apposition rate, bone formation rate and reduced osteoblasts indicating severe osteopenia. Mice suffer from a drastic reduction in bone marrow mesenchymal progenitors as analyzed by colony-forming unit-fibroblast assay. Fluorescence-activated cell sorting analysis of the skeletal mesenchyme harvested from bone marrow and collagenase-digested bone show a drastic reduction in hematopoietic lineage-negative, endothelial-negative, CD105+ skeletal stem cells. Bone marrow mesenchymal progenitors are unable to differentiate into osteoblasts in vitro, with no effect on adipogenic differentiation. Postnatal mice have smaller growth plates with reduced hypertrophic zone. Thus, S1P controls bone development directly by regulating the skeletal progenitor population and their differentiation into osteoblasts. This article has an associated First Person interview with the first author of the paper. Summary: S1P governs a fundamental aspect of skeletal development and homeostasis, mainly the maintenance and osteogenic differentiation of skeletogenic stem cells that are a source of osteoblast and chondrocyte lineages.
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Affiliation(s)
- Debabrata Patra
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Elizabeth DeLassus
- Department of Biochemistry, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jennifer Mueller
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Grazia Abou-Ezzi
- Department of Medicine, Oncology Division, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Linda J Sandell
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Bendre A, Moritz N, Väänänen V, Määttä JA. Dicer1 ablation in osterix positive bone forming cells affects cortical bone homeostasis. Bone 2018; 106:139-147. [PMID: 29066312 DOI: 10.1016/j.bone.2017.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 12/25/2022]
Abstract
The RNAse III enzyme Dicer plays a major role in the processing of microRNAs from large pre-miRNAs. Dicer1 processed microRNAs are known to play a comprehensive role in osteoblast differentiation, bone remodeling and skeletal disorders. Targeted deletion of Dicer1 in osteo-progenitor cells is deleterious to fetal survival whereas targeted deletion in mature osteoblasts leads to an increase in bone mass. To address the role of Dicer1 in post-natal skeletal homeostasis, we generated a pre-osteoblast specific Dicer1 knockout model employing Tamoxifen controllable Cre allele, enabling us, via tamoxifen administration, to time-controllably ablate Dicer1 gene expression in osterix expressing bone forming cells in post-natal mice. Inactivation of Dicer1 in osterix positive bone forming cells led to striking dysregulation of cortical bone formation in pre-pubertal as well as adult mice. Cortical bone thickness was found to be significantly decreased in the Cre+ femora of both young and adult mice. Further, biomechanical testing experiments showed increased ductility, reduced stiffness and altered load at upper yield among the Cre+ tibiae. Our results suggest that Dicer1 processed microRNAs might play an important role in the regulation of post-natal cortical bone formation.
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Affiliation(s)
- Ameya Bendre
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI20520 Turku, Finland
| | - Niko Moritz
- Department of Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland; Turku Biomaterials Research Program, Turku Clinical Biomaterial Centre, Itäinen Pitkäkatu 4B, FI20520 Turku, Finland
| | - Vilma Väänänen
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI20520 Turku, Finland
| | - Jorma A Määttä
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FI20520 Turku, Finland.
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43
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Frey JL, Kim SP, Li Z, Wolfgang MJ, Riddle RC. β-Catenin Directs Long-Chain Fatty Acid Catabolism in the Osteoblasts of Male Mice. Endocrinology 2018; 159:272-284. [PMID: 29077850 PMCID: PMC5761587 DOI: 10.1210/en.2017-00850] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/20/2017] [Indexed: 11/19/2022]
Abstract
Wnt-initiated signaling through a frizzled receptor and the low-density lipoprotein-related receptor-5 coreceptor instructs key anabolic events during skeletal development, homeostasis, and repair. Recent studies indicate that Wnt signaling also regulates the intermediary metabolism of osteoblastic cells, inducing glucose consumption in osteoprogenitors and fatty acid utilization in mature osteoblasts. In this study, we examined the role of the canonical Wnt-signaling target, β-catenin, in the control of osteoblast metabolism. In vitro, Wnt ligands and agonists that stimulated β-catenin activation in osteoblasts enhanced fatty acid catabolism, whereas genetic ablation of β-catenin dramatically reduced oleate oxidation concomitant with reduced osteoblast maturation and increased glycolytic metabolism. Temporal ablation of β-catenin expression in osteoblasts in vivo produced the expected low-bone-mass phenotype and also led to an increase in white adipose tissue mass, dyslipidemia, and impaired insulin sensitivity. Because the expression levels of enzymatic mediators of fatty acid β-oxidation are reduced in the skeleton of β-catenin mutants, these results further confirm the role of the osteoblast in lipid metabolism and indicate that the influence of Wnt signaling on fatty acid utilization proceeds via its canonical signaling pathway.
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MESH Headings
- Adipose Tissue, White/cytology
- Adipose Tissue, White/metabolism
- Adiposity
- Animals
- Animals, Newborn
- Caloric Restriction
- Cells, Cultured
- Crosses, Genetic
- Fatty Acids, Nonesterified/metabolism
- Gene Expression Regulation, Developmental
- Ligands
- Lipid Metabolism
- Male
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Mice, Transgenic
- Mutation
- Osteoblasts/cytology
- Osteoblasts/metabolism
- Random Allocation
- Skull/cytology
- Skull/metabolism
- Wnt Proteins/genetics
- Wnt Proteins/metabolism
- Wnt Signaling Pathway
- beta Catenin/genetics
- beta Catenin/metabolism
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Affiliation(s)
- Julie L. Frey
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Soohyun P. Kim
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Zhu Li
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Michael J. Wolfgang
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Ryan C. Riddle
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Veterans Administration Medical Center, Baltimore, Maryland 21201
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44
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Xu S, Liu X, Gao L, Xu B, Li J, Gao C, Cui Y, Liu J. Development and identification of Set transgenic mice. Exp Ther Med 2017; 15:1982-1988. [PMID: 29434793 PMCID: PMC5776649 DOI: 10.3892/etm.2017.5612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/15/2016] [Indexed: 12/12/2022] Open
Abstract
As a multifunctional protein involved in numerous biological processes, Set is expressed in several embryonic and adult organs. Furthermore, Set is overexpressed in numerous types of human cancers, including acute myeloid leukemia, breast cancer and pancreatic cancer. The expression of Set in germ cells is involved in gonad development, and the overexpression of Set has been observed in polycystic ovaries. In order to elucidate the physiological and pathological roles of Set, a Set transgenic mouse model was developed, in which the global overexpression of Set in adult tissues could be induced via the Cre/loxP system with the precise deletion of the Stop fragment in double-transgenic hybrids. This result was then confirmed by genotypical and protein analysis using polymerase chain reaction and bioluminescence imaging. In conclusion, the conditional Set transgenic mice carrying a reporter system were successfully generated. The transgenic mice open a new window for the further investigation of the function of Set using tissue-specific Cre mice and inducible Cre systems.
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Affiliation(s)
- Siliang Xu
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Xiaoqiang Liu
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Lingling Gao
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Boqun Xu
- Department of Obstetrics and Gynecology, Second Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Jianmin Li
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Chao Gao
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yugui Cui
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Jiayin Liu
- State Key Laboratory of Reproductive Medicine, Center for Clinical Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
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45
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Atsawasuwan P, Ouibaidin M, Dalal B, Khan H, Mohammed A. Calvarial bone development and suture closure in Dicer
-deficient mice. Orthod Craniofac Res 2017. [DOI: 10.1111/ocr.12169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- P. Atsawasuwan
- Department of Orthodontics; University of Illinois at Chicago; Chicago Illinois USA
| | - M. Ouibaidin
- Department of Orthodontics; University of Illinois at Chicago; Chicago Illinois USA
| | - B. Dalal
- Department of Orthodontics; University of Illinois at Chicago; Chicago Illinois USA
| | - H. Khan
- Department of Orthodontics; University of Illinois at Chicago; Chicago Illinois USA
| | - A. Mohammed
- Department of Orthodontics; University of Illinois at Chicago; Chicago Illinois USA
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46
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Peters SB, Wang Y, Serra R. Tgfbr2 is required in osterix expressing cells for postnatal skeletal development. Bone 2017; 97:54-64. [PMID: 28043895 PMCID: PMC5368008 DOI: 10.1016/j.bone.2016.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 11/02/2016] [Accepted: 12/29/2016] [Indexed: 10/20/2022]
Abstract
Transforming growth factor β (TGFβ) is known to play an important role in early skeletal development. We previously demonstrated that loss of TGFβ receptor II (Tgfbr2) in Prx1-Cre-expressing mesenchyme results in defects in long bones, joints, and the skull vault in mice resulting from reduced naïve mesenchymal proliferation and condensation that interrupted osteoblast differentiation. In contrast, others have shown that the loss of Tgfbr2 in fully differentiated mature osteoblasts results in increased bone volume. To study the role of Tgfbr2 in immature osteoblasts, we generated Osx-Cre;Tgfbr2fl/fl mice and found defects in the postnatal development of the skull vault and long bones as compared to controls. No discernible skeletal defects were observed in newborn mice; however, at postnatal day 24 (P24), Tgfbr2-deleted mice demonstrated short stature that correlated with reduced proliferation in the growth plate. X-ray and microCT analysis of long bone and skull from P24 mice showed reduced bone volume. Histomorphometry indicated reductions in osteoblast number but not osteoclast number. Quantitative real-time PCR demonstrated mRNA levels for the osteoblast marker, Runx2, were not altered but mRNA levels of a marker for mature osteoblasts, Bglap, were down in mutant calvaria relative to controls. The mRNA of a proliferation marker, proliferative nuclear cell antigen (PCNA), was also reduced whereas the ratio of Bax2:Bcl2 was unaltered to demonstrate no change in apoptosis. These results suggest proliferation and maturation of immature osteoblasts requires Tgfbr2 signaling and that decreased bone volume in Osx-Cre;Tgfbr2fl/fl mice is likely due to fewer mature osteoblasts.
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Affiliation(s)
- Sarah B Peters
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham AL 35294, USA
| | - Ying Wang
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham AL 35294, USA
| | - Rosa Serra
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham AL 35294, USA.
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47
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Moon YJ, Yun CY, Choi H, Ka SO, Kim JR, Park BH, Cho ES. Smad4 controls bone homeostasis through regulation of osteoblast/osteocyte viability. Exp Mol Med 2016; 48:e256. [PMID: 27585718 PMCID: PMC5050296 DOI: 10.1038/emm.2016.75] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/25/2016] [Accepted: 04/05/2016] [Indexed: 12/23/2022] Open
Abstract
Regulation of osteoblast and osteocyte viability is essential for bone homeostasis. Smad4, a major transducer of bone morphogenetic protein and transforming growth factor-β signaling pathways, regulates apoptosis in various cell types through a mitochondrial pathway. However, it remains poorly understood whether Smad4 is necessary for the regulation of osteoblast and osteocyte viability. In this study, we analyzed Smad4Δ(Os) mice, in which Smad4 was subjected to tissue-specific disruption under the control of the 2.3-kb Col1a1 promoter, to understand the functional significance of Smad4 in regulating osteoblast/osteocyte viability during bone formation and remodeling. Smad4Δ(Os) mice showed a significant increase in osteoblast number and osteocyte density in the trabecular and cortical regions of the femur, whereas osteoclast activity was significantly decreased. The proliferation of osteoblasts/osteocytes did not alter, as shown by measuring 5'-bromo-2'deoxyuridine incorporation. By contrast, the percentage of TUNEL-positive cells decreased, together with a decrease in the Bax/Bcl-2 ratio and in the proteolytic cleavage of caspase 3, in Smad4Δ(Os) mice. Apoptosis in isolated calvaria cells from Smad4Δ(Os) mice decreased after differentiation, which was consistent with the results of the TUNEL assay and western blotting in Smad4Δ(Os) mice. Conversely, osteoblast cells overexpressing Smad4 showed increased apoptosis. In an apoptosis induction model of Smad4Δ(Os) mice, osteoblasts/osteocytes were more resistant to apoptosis than were control cells, and, consequently, bone remodeling was attenuated. These findings indicate that Smad4 has a significant role in regulating osteoblast/osteocyte viability and therefore controls bone homeostasis.
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Affiliation(s)
- Young Jae Moon
- Department of Biochemistry, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea.,Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, Jeonbuk, Republic of Korea
| | - Chi-Young Yun
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, Jeonbuk, Republic of Korea
| | - Hwajung Choi
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, Jeonbuk, Republic of Korea
| | - Sun-O Ka
- Department of Biochemistry, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea
| | - Jung Ryul Kim
- Department of Orthopaedic Surgery, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea.,Research Institute of Clinical Medicine, Chonbuk National University Hospital, Jeonju, Jeonbuk, Republic of Korea
| | - Byung-Hyun Park
- Department of Biochemistry, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea
| | - Eui-Sic Cho
- Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, Jeonbuk, Republic of Korea
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48
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Cain CJ, Gaborit N, Lwin W, Barruet E, Ho S, Bonnard C, Hamamy H, Shboul M, Reversade B, Kayserili H, Bruneau BG, Hsiao EC. Loss of Iroquois homeobox transcription factors 3 and 5 in osteoblasts disrupts cranial mineralization. Bone Rep 2016; 5:86-95. [PMID: 27453922 PMCID: PMC4926823 DOI: 10.1016/j.bonr.2016.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 02/02/2016] [Indexed: 01/13/2023] Open
Abstract
Cranial malformations are a significant cause of perinatal morbidity and mortality. Iroquois homeobox transcription factors (IRX) are expressed early in bone tissue formation and facilitate patterning and mineralization of the skeleton. Mice lacking Irx5 appear grossly normal, suggesting that redundancy within the Iroquois family. However, global loss of both Irx3 and Irx5 in mice leads to significant skeletal malformations and embryonic lethality from cardiac defects. Here, we study the bone-specific functions of Irx3 and Irx5 using Osx-Cre to drive osteoblast lineage-specific deletion of Irx3 in Irx5(-/-) mice. Although we found that the Osx-Cre transgene alone could also affect craniofacial mineralization, newborn Irx3 (flox/flox) /Irx5(-/-)/Osx-Cre (+) mice displayed additional mineralization defects in parietal, interparietal, and frontal bones with enlarged sutures and reduced calvarial expression of osteogenic genes. Newborn endochondral long bones were largely unaffected, but we observed marked reductions in 3-4-week old bone mineral content of Irx3 (flox/flox) /Irx5(-/-)/Osx-Cre (+) mice. Our findings indicate that IRX3 and IRX5 can work together to regulate mineralization of specific cranial bones. Our results also provide insight into the causes of the skeletal changes and mineralization defects seen in Hamamy syndrome patients carrying mutations in IRX5.
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Affiliation(s)
- Corey J Cain
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Nathalie Gaborit
- Inserm, UMR 1087, l'institut du thorax, Nantes, France; CNRS, UMR 6291, Nantes, France; Université de Nantes, France
| | - Wint Lwin
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Emilie Barruet
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Samantha Ho
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
| | - Carine Bonnard
- Human Embryology and Genetics Laboratory, Institute of Medical Biology, ASTAR, Singapore 138648, Singapore
| | - Hanan Hamamy
- Department of Genetic Medicine and Development, Geneva University, Geneva 1211, Switzerland
| | - Mohammad Shboul
- Human Embryology and Genetics Laboratory, Institute of Medical Biology, ASTAR, Singapore 138648, Singapore
| | - Bruno Reversade
- Human Embryology and Genetics Laboratory, Institute of Medical Biology, ASTAR, Singapore 138648, Singapore
| | - Hülya Kayserili
- Medical Genetics Department, Koc University School of Medicine, Rumelifeneri Yolu, Sarıyer, Istanbul 34450, Turkey; Medical Genetics Department, Istanbul Medical Faculty, Istanbul University Topkapi, Fatih, 34093 lstanbul, Turkey
| | - Benoit G Bruneau
- Gladstone Institute for Cardiovascular Disease, San Francisco, CA 94158, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Edward C Hsiao
- Department of Medicine, Division of Endocrinology and Metabolism, Institute for Human Genetics, Program in Craniofacial Biology, University of California, San Francisco, San Francisco, CA 94143-0794, USA
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49
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Low bone mass and changes in the osteocyte network in mice lacking autophagy in the osteoblast lineage. Sci Rep 2016; 6:24262. [PMID: 27064143 PMCID: PMC4827128 DOI: 10.1038/srep24262] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 03/23/2016] [Indexed: 02/07/2023] Open
Abstract
Autophagy maintains cell function and homeostasis by recycling intracellular components. This process is also required for morphological changes associated with maturation of some cell types. Osteoblasts are bone forming cells some of which become embedded in bone and differentiate into osteocytes. This transformation includes development of long cellular projections and a reduction in endoplasmic reticulum and mitochondria. We examined the role of autophagy in osteoblasts by deleting Atg7 using an Osterix1-Cre transgene, which causes recombination in osteoblast progenitors and their descendants. Mice lacking Atg7 in the entire osteoblast lineage had low bone mass and fractures associated with reduced numbers of osteoclasts and osteoblasts. Suppression of autophagy also reduced the amount of osteocyte cellular projections and led to retention of endoplasmic reticulum and mitochondria in osteocytes. These results demonstrate that autophagy in osteoblasts contributes to skeletal homeostasis and to the morphological changes associated with osteocyte formation.
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50
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Karuppaiah K, Yu K, Lim J, Chen J, Smith C, Long F, Ornitz DM. FGF signaling in the osteoprogenitor lineage non-autonomously regulates postnatal chondrocyte proliferation and skeletal growth. Development 2016; 143:1811-22. [PMID: 27052727 DOI: 10.1242/dev.131722] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 03/18/2016] [Indexed: 12/22/2022]
Abstract
Fibroblast growth factor (FGF) signaling is important for skeletal development; however, cell-specific functions, redundancy and feedback mechanisms regulating bone growth are poorly understood. FGF receptors 1 and 2 (Fgfr1 and Fgfr2) are both expressed in the osteoprogenitor lineage. Double conditional knockout mice, in which both receptors were inactivated using an osteoprogenitor-specific Cre driver, appeared normal at birth; however, these mice showed severe postnatal growth defects that include an ∼50% reduction in body weight and bone mass, and impaired longitudinal bone growth. Histological analysis showed reduced cortical and trabecular bone, suggesting cell-autonomous functions of FGF signaling during postnatal bone formation. Surprisingly, the double conditional knockout mice also showed growth plate defects and an arrest in chondrocyte proliferation. We provide genetic evidence of a non-cell-autonomous feedback pathway regulating Fgf9, Fgf18 and Pthlh expression, which led to increased expression and signaling of Fgfr3 in growth plate chondrocytes and suppression of chondrocyte proliferation. These observations show that FGF signaling in the osteoprogenitor lineage is obligately coupled to chondrocyte proliferation and the regulation of longitudinal bone growth.
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Affiliation(s)
- Kannan Karuppaiah
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Kai Yu
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO 63110, USA Division of Craniofacial Medicine, Department of Pediatrics, University of Washington and Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Joohyun Lim
- Departments of Orthopaedic Surgery and Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Jianquan Chen
- Departments of Orthopaedic Surgery and Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Craig Smith
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Fanxin Long
- Departments of Orthopaedic Surgery and Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - David M Ornitz
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO 63110, USA
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