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Ge C, Li Y, Wu F, Ma P, Franceschi RT. Synthetic peptides activating discoidin domain receptor 2 and collagen-binding integrins cooperate to stimulate osteoblast differentiation of skeletal progenitor cells. Acta Biomater 2023; 166:109-118. [PMID: 37245640 PMCID: PMC10617013 DOI: 10.1016/j.actbio.2023.05.039] [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: 10/11/2022] [Revised: 05/16/2023] [Accepted: 05/22/2023] [Indexed: 05/30/2023]
Abstract
Skeletal progenitor: collagen interactions are critical for bone development and regeneration. Both collagen-binding integrins and discoidin domain receptors (DDR1 and DDR2) function as collagen receptors in bone. Each receptor is activated by a distinct collagen sequence; GFOGER for integrins and GVMGFO for DDRs. Specific triple helical peptides containing each of these binding domains were evaluated for ability to stimulate DDR2 and integrin signaling and osteoblast differentiation. GVMGFO peptide stimulated DDR2 Y740 phosphorylation and osteoblast differentiation as measured by induction of osteoblast marker mRNAs and mineralization without affecting integrin activity. In contrast, GFOGER peptide stimulated focal adhesion kinase (FAK) Y397 phosphorylation, an early measure of integrin activation, and to a lesser extent osteoblast differentiation without affecting DDR2-P. Significantly, the combination of both peptides cooperatively enhanced both DDR2 and FAK signaling and osteoblast differentiation, a response that was blocked in Ddr2-deficient cells. These studies suggest that the development of scaffolds containing DDR and integrin-activating peptides may provide a new route for promoting bone regeneration. STATEMENT OF SIGNIFICANCE: A method for stimulating osteoblast differentiation of skeletal progenitor cells is described that uses culture surfaces coated with a collagen-derived triple-helical peptide to selectively activate discoidin domain receptors. When this peptide is combined with an integrin-activating peptide, synergistic stimulation of differentiation is seen. This approach of combining collagen-derived peptides to stimulate the two main collagen receptors in bone (DDR2 and collagen-binding integrins) provides a route for developing a new class of tissue engineering scaffolds for bone regeneration.
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Affiliation(s)
- Chunxi Ge
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA
| | - Yiming Li
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA
| | - Fashuai Wu
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA; Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Peter Ma
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA
| | - Renny T Franceschi
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, 1011 N. University Avenue, Ann Arbor, MI 48109-1078, USA.
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2
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Franceschi RT, Hallett SA, Ge C. Discoidin domain receptors; an ancient family of collagen receptors has major roles in bone development, regeneration and metabolism. FRONTIERS IN DENTAL MEDICINE 2023; 4:1181817. [PMID: 38222874 PMCID: PMC10785288 DOI: 10.3389/fdmed.2023.1181817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024] Open
Abstract
The extracellular matrix (ECM) niche plays a critical role in determining cellular behavior during bone development including the differentiation and lineage allocation of skeletal progenitor cells to chondrocytes, osteoblasts, or marrow adipocytes. As the major ECM component in mineralized tissues, collagen has instructive as well as structural roles during bone development and is required for bone cell differentiation. Cells sense their extracellular environment using specific cell surface receptors. For many years, specific β1 integrins were considered the main collagen receptors in bone, but, more recently, the important role of a second, more primordial collagen receptor family, the discoidin domain receptors, has become apparent. This review will specifically focus on the roles of discoidin domain receptors in mineralized tissue development as well as related functions in abnormal bone formation, regeneration and metabolism.
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Affiliation(s)
- Renny T. Franceschi
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI, United States
| | - Shawn A. Hallett
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI, United States
| | - Chunxi Ge
- Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI, United States
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3
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Qin L, Chen Z, Yang D, He T, Xu Z, Zhang P, Chen D, Yi W, Xiao G. Osteocyte β3 integrin promotes bone mass accrual and force-induced bone formation in mice. J Orthop Translat 2023; 40:58-71. [PMID: 37457310 PMCID: PMC10338905 DOI: 10.1016/j.jot.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 04/24/2023] [Accepted: 05/08/2023] [Indexed: 07/18/2023] Open
Abstract
Background Cell culture studies demonstrate the importance of β3 integrin in osteocyte mechanotransduction. However, the in vivo roles of osteocyte β3 integrin in the regulation of bone homeostasis and mechanotransduction are poorly defined. Materials and methods To study the in vivo role of osteocyte β3 integrin in bone, we utilized the 10-kb Dmp1 (dentin matrix acidic phosphoprotein 1)-Cre to delete β3 integrin expression in osteocyte in mice. Micro-computerized tomography (μCT), bone histomorphometry and in vitro cell culture experiments were performed to determine the effects of osteocyte β3 integrin loss on bone mass accrual and biomechanical properties. In addition, in vivo tibial loading model was applied to study the possible involvement of osteocyte β3 integrin in the mediation of bone mechanotransduction. Results Deletion of β3 integrin in osteocytes resulted in a low bone mass and impaired biomechanical properties in load-bearing long bones in adult mice. The loss of β3 integrin led to abnormal cell morphology with reduced number and length of dentritic processes in osteocytes. Furthermore, osteocyte β3 integrin loss did not impact the osteoclast formation, but significantly reduced the osteoblast-mediated bone formation rate and reduced the osteogenic differentiation of the bone marrow stromal cells in the bone microenvironment. In addition, mechanical loading failed to accelerate the anabolic bone formation in mutant mice. Conclusions Our studies demonstrate the essential roles of osteocyte β3 integrin in regulating bone mass and mechanotransduction.
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Affiliation(s)
- Lei Qin
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518000, China
| | - Zecai Chen
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518000, China
| | - Dazhi Yang
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518000, China
| | - Tailin He
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Shenzhen, 518055, China
| | - Zhen Xu
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518000, China
| | - Peijun Zhang
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Shenzhen, 518055, China
| | - Di Chen
- Research Center for Human Tissues and Organs Degeneration, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Weihong Yi
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518000, China
| | - Guozhi Xiao
- Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Shenzhen, 518055, China
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4
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Dienes B, Bazsó T, Szabó L, Csernoch L. The Role of the Piezo1 Mechanosensitive Channel in the Musculoskeletal System. Int J Mol Sci 2023; 24:ijms24076513. [PMID: 37047487 PMCID: PMC10095409 DOI: 10.3390/ijms24076513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
Since the recent discovery of the mechanosensitive Piezo1 channels, many studies have addressed the role of the channel in various physiological or even pathological processes of different organs. Although the number of studies on their effects on the musculoskeletal system is constantly increasing, we are still far from a precise understanding. In this review, the knowledge available so far regarding the musculoskeletal system is summarized, reviewing the results achieved in the field of skeletal muscles, bones, joints and cartilage, tendons and ligaments, as well as intervertebral discs.
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5
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Pazarçeviren AE, Evis Z, Dikmen T, Altunbaş K, Yaprakçı MV, Keskin D, Tezcaner A. Alginate/gelatin/boron-doped hydroxyapatite-coated Ti implants: in vitro and in vivo evaluation of osseointegration. Biodes Manuf 2023. [DOI: 10.1007/s42242-022-00218-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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6
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Qin L, He T, Yang D, Wang Y, Li Z, Yan Q, Zhang P, Chen Z, Lin S, Gao H, Yao Q, Xu Z, Tang B, Yi W, Xiao G. Osteocyte β1 integrin loss causes low bone mass and impairs bone mechanotransduction in mice. J Orthop Translat 2022; 34:60-72. [PMID: 35615639 PMCID: PMC9119859 DOI: 10.1016/j.jot.2022.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 03/19/2022] [Accepted: 03/21/2022] [Indexed: 11/09/2022] Open
Abstract
Background The key focal adhesion protein β1 integrin plays an essential role in early skeletal development. However, roles of β1 integrin expression in osteocytes during the regulation of bone homeostasis and mechanotransduction are incompletely understood. Materials and methods To study the in vivo function of osteocyte β1 integrin in bone, we utilized the 10-kb Dmp1 (Dentin matrix acidic phosphoprotein 1)-Cre to generate mice with β1 integrin deletion in this cell type. Micro-computerized tomography, bone histomorphometry and immunohistochemistry were performed to determine the effects of osteocyte β1 integrin loss on bone mass accrual and biomechanical properties. In vivo tibial loading model was applied to study the possible involvement of osteocyte β1 integrin in bone mechanotransduction. Results Loss of β1 integrin expression in osteocytes resulted in a severe low bone mass and impaired biomechanical properties in load-bearing long bones and spines, but not in non-weight-bearing calvariae, in mice. The loss of β1 integrin led to enlarged size of lacunar-canalicular system, abnormal cell morphology, and disorientated nuclei in osteocytes. Furthermore, β1 integrin loss caused shortening and disorientated collagen I fibers in long bones. Osteocyte β1 integrin loss did not impact the osteoclast activities, but significantly reduced the osteoblast bone formation rate and, in the meantime, enhanced the adipogenic differentiation of the bone marrow stromal cells in the bone microenvironment. In addition, tibial loading failed to accelerate the anabolic bone formation and improve collagen I fiber integrity in mutant mice. Conclusions Our studies demonstrate an essential role of osteocyte β1 integrin in regulating bone homeostasis and mechanotransduction. The transnational potential of this article: This study reveals the regulatory roles of osteocyte β1 integrin in vivo for the maintenance of bone mass accrual, biomechanical properties, extracellular matrix integrity as well as bone mechanobiology, which defines β1 integrin a potential therapeutic target for skeletal diseases, such as osteoporosis.
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7
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Choi JUA, Kijas AW, Lauko J, Rowan AE. The Mechanosensory Role of Osteocytes and Implications for Bone Health and Disease States. Front Cell Dev Biol 2022; 9:770143. [PMID: 35265628 PMCID: PMC8900535 DOI: 10.3389/fcell.2021.770143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/13/2021] [Indexed: 12/14/2022] Open
Abstract
Bone homeostasis is a dynamic equilibrium between bone-forming osteoblasts and bone-resorbing osteoclasts. This process is primarily controlled by the most abundant and mechanosensitive bone cells, osteocytes, that reside individually, within chambers of porous hydroxyapatite bone matrix. Recent studies have unveiled additional functional roles for osteocytes in directly contributing to local matrix regulation as well as systemic roles through endocrine functions by communicating with distant organs such as the kidney. Osteocyte function is governed largely by both biochemical signaling and the mechanical stimuli exerted on bone. Mechanical stimulation is required to maintain bone health whilst aging and reduced level of loading are known to result in bone loss. To date, both in vivo and in vitro approaches have been established to answer important questions such as the effect of mechanical stimuli, the mechanosensors involved, and the mechanosensitive signaling pathways in osteocytes. However, our understanding of osteocyte mechanotransduction has been limited due to the technical challenges of working with these cells since they are individually embedded within the hard hydroxyapatite bone matrix. This review highlights the current knowledge of the osteocyte functional role in maintaining bone health and the key regulatory pathways of these mechanosensitive cells. Finally, we elaborate on the current therapeutic opportunities offered by existing treatments and the potential for targeting osteocyte-directed signaling.
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Affiliation(s)
- Jung Un Ally Choi
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Amanda W Kijas
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Jan Lauko
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Alan E Rowan
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
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8
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Patel C, Shi L, Whitesides JF, Foster BM, Fajardo RJ, Quillen EE, Kerr BA. A New Method of Bone Stromal Cell Characterization by Flow Cytometry. Curr Protoc 2022; 2:e400. [PMID: 35349226 PMCID: PMC8981709 DOI: 10.1002/cpz1.400] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The bone microenvironment cellular composition plays an essential role in bone health and is disrupted in bone pathologies, such as osteoporosis, osteoarthritis, and cancer. Flow cytometry protocols for hematopoietic stem cell lineages are well defined and well established. Additionally, a consensus for mesenchymal stem cell flow markers has been developed. However, flow cytometry markers for bone-residing cells-osteoblasts, osteoclasts, and osteocytes-have not been proposed. Here, we describe a novel partial digestion method to separate these cells from the bone matrix and present new markers for enumerating these cells by flow cytometry. We optimized bone digestion and analyzed markers across murine, nonhuman primate, and human bone. The isolation and staining protocols can be used with either cell sorting or flow cytometry. Our method allows for the enumeration and collection of hematopoietic and mesenchymal lineage cells in the bone microenvironment combined with bone-residing stromal cells. Thus, we have established a multi-fluorochrome bone marrow cell-typing methodology. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Partial digestion for murine long bone stromal cell isolation Alternate Protocol 1: Partial digestion for primate vertebrae stromal cell isolation Alternate Protocol 2: Murine vertebrae crushing for bone stromal cell isolation Basic Protocol 2: Staining of bone stromal cells Support Protocol 1: Fluorescence minus one control, isotype control, and antibody titration Basic Protocol 3: Cell sorting of bone stromal cells Alternate Protocol 3: Flow cytometry analysis of bone stromal cells Support Protocol 2: Preparing compensation beads.
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Affiliation(s)
- Chirayu Patel
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - Lihong Shi
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - John F. Whitesides
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27157,Wake Forest Baptist Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - Brittni M. Foster
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - Roberto J. Fajardo
- University of the Incarnate Word School of Osteopathic Medicine, San Antonio, TX 78235
| | - Ellen E. Quillen
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157
| | - Bethany A. Kerr
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC 27157,Wake Forest Baptist Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC 27157,Department of Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, NC 27157,Corresponding Author: Telephone: 336-716-0320; Fax: 336-716-0255; Twitter: @BethanyKerrLab;
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9
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Mohamed FF, Ge C, Cowling RT, Lucas D, Hallett SA, Ono N, Binrayes AA, Greenberg B, Franceschi RT. The collagen receptor, discoidin domain receptor 2, functions in Gli1-positive skeletal progenitors and chondrocytes to control bone development. Bone Res 2022; 10:11. [PMID: 35140200 PMCID: PMC8828874 DOI: 10.1038/s41413-021-00182-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 08/31/2021] [Accepted: 10/24/2021] [Indexed: 01/02/2023] Open
Abstract
Discoidin Domain Receptor 2 (DDR2) is a collagen-activated receptor kinase that, together with integrins, is required for cells to respond to the extracellular matrix. Ddr2 loss-of-function mutations in humans and mice cause severe defects in skeletal growth and development. However, the cellular functions of Ddr2 in bone are not understood. Expression and lineage analysis showed selective expression of Ddr2 at early stages of bone formation in the resting zone and proliferating chondrocytes and periosteum. Consistent with these findings, Ddr2+ cells could differentiate into hypertrophic chondrocytes, osteoblasts, and osteocytes and showed a high degree of colocalization with the skeletal progenitor marker, Gli1. A conditional deletion approach showed a requirement for Ddr2 in Gli1-positive skeletal progenitors and chondrocytes but not mature osteoblasts. Furthermore, Ddr2 knockout in limb bud chondroprogenitors or purified marrow-derived skeletal progenitors inhibited chondrogenic or osteogenic differentiation, respectively. This work establishes a cell-autonomous function for Ddr2 in skeletal progenitors and cartilage and emphasizes the critical role of this collagen receptor in bone development.
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Affiliation(s)
- Fatma F Mohamed
- Department of Periodontics & Oral Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Chunxi Ge
- Department of Periodontics & Oral Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Randy T Cowling
- Division of Cardiovascular Medicine, University of California at San Diego, San Diego, CA, USA
| | - Daniel Lucas
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Medical Center, Cincinnati, OH, USA.,Department of Pediatrics, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Shawn A Hallett
- Department of Periodontics & Oral Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Noriaki Ono
- Department of Orthodontics & Pediatric Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - Abdul-Aziz Binrayes
- Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
| | - Barry Greenberg
- Division of Cardiovascular Medicine, University of California at San Diego, San Diego, CA, USA
| | - Renny T Franceschi
- Department of Periodontics & Oral Medicine, University of Michigan, Ann Arbor, MI, USA. .,Department of Biological Chemistry, School of Medicine, University of Michigan, Ann Arbor, MI, USA. .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.
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10
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McCarthy C, Camci-Unal G. Low Intensity Pulsed Ultrasound for Bone Tissue Engineering. MICROMACHINES 2021; 12:1488. [PMID: 34945337 PMCID: PMC8707172 DOI: 10.3390/mi12121488] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/24/2021] [Accepted: 11/28/2021] [Indexed: 12/16/2022]
Abstract
As explained by Wolff's law and the mechanostat hypothesis, mechanical stimulation can be used to promote bone formation. Low intensity pulsed ultrasound (LIPUS) is a source of mechanical stimulation that can activate the integrin/phosphatidylinositol 3-OH kinase/Akt pathway and upregulate osteogenic proteins through the production of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2). This paper analyzes the results of in vitro and in vivo studies that have evaluated the effects of LIPUS on cell behavior within three-dimensional (3D) titanium, ceramic, and hydrogel scaffolds. We focus specifically on cell morphology and attachment, cell proliferation and viability, osteogenic differentiation, mineralization, bone volume, and osseointegration. As shown by upregulated levels of alkaline phosphatase and osteocalcin, increased mineral deposition, improved cell ingrowth, greater scaffold pore occupancy by bone tissue, and superior vascularization, LIPUS generally has a positive effect and promotes bone formation within engineered scaffolds. Additionally, LIPUS can have synergistic effects by producing the piezoelectric effect and enhancing the benefits of 3D hydrogel encapsulation, growth factor delivery, and scaffold modification. Additional research should be conducted to optimize the ultrasound parameters and evaluate the effects of LIPUS with other types of scaffold materials and cell types.
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Affiliation(s)
- Colleen McCarthy
- Department of Chemical Engineering, University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, USA;
| | - Gulden Camci-Unal
- Department of Chemical Engineering, University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, USA;
- Department of Surgery, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01605, USA
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11
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Qin L, He T, Chen S, Yang D, Yi W, Cao H, Xiao G. Roles of mechanosensitive channel Piezo1/2 proteins in skeleton and other tissues. Bone Res 2021; 9:44. [PMID: 34667178 PMCID: PMC8526690 DOI: 10.1038/s41413-021-00168-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/16/2021] [Accepted: 07/08/2021] [Indexed: 12/12/2022] Open
Abstract
Mechanotransduction is a fundamental ability that allows living organisms to receive and respond to physical signals from both the external and internal environments. The mechanotransduction process requires a range of special proteins termed mechanotransducers to convert mechanical forces into biochemical signals in cells. The Piezo proteins are mechanically activated nonselective cation channels and the largest plasma membrane ion channels reported thus far. The regulation of two family members, Piezo1 and Piezo2, has been reported to have essential functions in mechanosensation and transduction in different organs and tissues. Recently, the predominant contributions of the Piezo family were reported to occur in the skeletal system, especially in bone development and mechano-stimulated bone homeostasis. Here we review current studies focused on the tissue-specific functions of Piezo1 and Piezo2 in various backgrounds with special highlights on their importance in regulating skeletal cell mechanotransduction. In this review, we emphasize the diverse functions of Piezo1 and Piezo2 and related signaling pathways in osteoblast lineage cells and chondrocytes. We also summarize our current understanding of Piezo channel structures and the key findings about PIEZO gene mutations in human diseases.
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Affiliation(s)
- Lei Qin
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, Guangdong, China
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Tailin He
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Sheng Chen
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, Guangdong, China
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Dazhi Yang
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, Guangdong, China
| | - Weihong Yi
- Department of Orthopedics, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, Guangdong, China.
| | - Huiling Cao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, Guangdong, China.
| | - Guozhi Xiao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, Guangdong, China.
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12
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Gould NR, Torre OM, Leser JM, Stains JP. The cytoskeleton and connected elements in bone cell mechano-transduction. Bone 2021; 149:115971. [PMID: 33892173 PMCID: PMC8217329 DOI: 10.1016/j.bone.2021.115971] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/30/2021] [Accepted: 04/17/2021] [Indexed: 02/07/2023]
Abstract
Bone is a mechano-responsive tissue that adapts to changes in its mechanical environment. Increases in strain lead to increased bone mass acquisition, whereas decreases in strain lead to a loss of bone mass. Given that mechanical stress is a regulator of bone mass and quality, it is important to understand how bone cells sense and transduce these mechanical cues into biological changes to identify druggable targets that can be exploited to restore bone cell mechano-sensitivity or to mimic mechanical load. Many studies have identified individual cytoskeletal components - microtubules, actin, and intermediate filaments - as mechano-sensors in bone. However, given the high interconnectedness and interaction between individual cytoskeletal components, and that they can assemble into multiple discreet cellular structures, it is likely that the cytoskeleton as a whole, rather than one specific component, is necessary for proper bone cell mechano-transduction. This review will examine the role of each cytoskeletal element in bone cell mechano-transduction and will present a unified view of how these elements interact and work together to create a mechano-sensor that is necessary to control bone formation following mechanical stress.
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Affiliation(s)
- Nicole R Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Olivia M Torre
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA..
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13
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Tsukasaki M, Asano T, Muro R, Huynh NCN, Komatsu N, Okamoto K, Nakano K, Okamura T, Nitta T, Takayanagi H. OPG Production Matters Where It Happened. Cell Rep 2021; 32:108124. [PMID: 32905763 DOI: 10.1016/j.celrep.2020.108124] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 08/05/2020] [Accepted: 08/18/2020] [Indexed: 12/20/2022] Open
Abstract
Osteoprotegerin (OPG) is a circulating decoy receptor for RANKL, a multifunctional cytokine essential for the differentiation of tissue-specific cells in bone and immune systems such as osteoclasts, medullary thymic epithelial cells (mTECs), and intestinal microfold cells (M cells). However, it is unknown whether OPG functions only at the production site or circulates to other tissues acting in an endocrine fashion. Here we explore the cellular source of OPG by generating OPG-floxed mice and show that locally produced OPG, rather than circulating OPG, is crucial for bone and immune homeostasis. Deletion of OPG in osteoblastic cells leads to severe osteopenia without affecting serum OPG. Deletion of locally produced OPG increases mTEC and M cell numbers while retaining the normal serum OPG level. This study shows that OPG limits its functions within the tissue where it was produced, illuminating the importance of local regulation of the RANKL system.
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Affiliation(s)
- Masayuki Tsukasaki
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Tatsuo Asano
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Ryunosuke Muro
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Nam Cong-Nhat Huynh
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Noriko Komatsu
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Kazuo Okamoto
- Department of Osteoimmunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Kenta Nakano
- Department of Laboratory Animal Medicine, Research Institute, National Center for Global Health and Medicine, 1-21-1, Toyama, Shinjuku-ku, 162-8655 Tokyo, Japan
| | - Tadashi Okamura
- Department of Laboratory Animal Medicine, Research Institute, National Center for Global Health and Medicine, 1-21-1, Toyama, Shinjuku-ku, 162-8655 Tokyo, Japan
| | - Takeshi Nitta
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Hiroshi Takayanagi
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan.
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14
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Binrayes A, Ge C, Mohamed FF, Franceschi RT. Role of Discoidin Domain Receptor 2 in Craniofacial Bone Regeneration. J Dent Res 2021; 100:1359-1366. [PMID: 33899571 PMCID: PMC8532241 DOI: 10.1177/00220345211007447] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Bone loss caused by trauma, neoplasia, congenital defects, or periodontal disease is a major cause of disability and human suffering. Skeletal progenitor cell-extracellular matrix interactions are critical for bone regeneration. Discoidin domain receptor 2 (DDR2), an understudied collagen receptor, plays an important role in skeletal development. Ddr2 loss-of-function mutations in humans and mice cause severe craniofacial and skeletal defects, including altered cranial shape, dwarfing, reduced trabecular and cortical bone, alveolar bone/periodontal defects, and altered dentition. However, the role of this collagen receptor in craniofacial regeneration has not been examined. To address this, calvarial subcritical-size defects were generated in wild-type (WT) and Ddr2-deficient mice. The complete bridging seen in WT controls at 4 wk postsurgery was not observed in Ddr2-deficient mice even after 12 wk. Quantitation of defect bone area by micro-computed tomography also revealed a 50% reduction in new bone volume in Ddr2-deficient mice. Ddr2 expression during calvarial bone regeneration was measured using Ddr2-LacZ knock-in mice. Expression was restricted to periosteal surfaces of uninjured calvarial bone and, after injury, was detected in select regions of the defect site by 3 d postsurgery and expanded during the healing process. The impaired bone healing associated with Ddr2 deficiency may be related to reduced osteoprogenitor or osteoblast cell proliferation and differentiation since knockdown/knockout of Ddr2 in a mesenchymal cell line and primary calvarial osteoblast cultures reduced osteoblast differentiation while Ddr2 overexpression was stimulatory. In conclusion, Ddr2 is required for cranial bone regeneration and may be a novel target for therapy.
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Affiliation(s)
- A Binrayes
- Departments of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA.,Department of Prosthetic Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
| | - C Ge
- Departments of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - F F Mohamed
- Departments of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - R T Franceschi
- Departments of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA.,Department of Biological Chemistry, School of Medicine, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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15
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Qin L, Fu X, Ma J, Lin M, Zhang P, Wang Y, Yan Q, Tao C, Liu W, Tang B, Chen D, Bai X, Cao H, Xiao G. Kindlin-2 mediates mechanotransduction in bone by regulating expression of Sclerostin in osteocytes. Commun Biol 2021; 4:402. [PMID: 33767359 PMCID: PMC7994671 DOI: 10.1038/s42003-021-01950-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 03/03/2021] [Indexed: 12/16/2022] Open
Abstract
Osteocytes act as mechanosensors in bone; however, the underlying mechanism remains poorly understood. Here we report that deleting Kindlin-2 in osteocytes causes severe osteopenia and mechanical property defects in weight-bearing long bones, but not in non-weight-bearing calvariae. Kindlin-2 loss in osteocytes impairs skeletal responses to mechanical stimulation in long bones. Control and cKO mice display similar bone loss induced by unloading. However, unlike control mice, cKO mice fail to restore lost bone after reloading. Osteocyte Kindlin-2 deletion impairs focal adhesion (FA) formation, cytoskeleton organization and cell orientation in vitro and in bone. Fluid shear stress dose-dependently increases Kindlin-2 expression and decreases that of Sclerostin by downregulating Smad2/3 in osteocytes; this latter response is abolished by Kindlin-2 ablation. Kindlin-2-deficient osteocytes express abundant Sclerostin, contributing to bone loss in cKO mice. Collectively, we demonstrate an indispensable novel role of Kindlin-2 in maintaining skeletal responses to mechanical stimulation by inhibiting Sclerostin expression during osteocyte mechanotransduction.
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Affiliation(s)
- Lei Qin
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Xuekun Fu
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Jing Ma
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Manxia Lin
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Peijun Zhang
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Yishu Wang
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Qinnan Yan
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Chu Tao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Wen Liu
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China
| | - Bin Tang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Di Chen
- Research Center for Human Tissues and Organs Degeneration, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Xiaochun Bai
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Huiling Cao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China.
| | - Guozhi Xiao
- Department of Biochemistry, School of Medicine, Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen, China.
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16
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Ascolani G, Skerry TM, Lacroix D, Dall'Ara E, Shuaib A. Analysis of mechanotransduction dynamics during combined mechanical stimulation and modulation of the extracellular-regulated kinase cascade uncovers hidden information within the signalling noise. Interface Focus 2021; 11:20190136. [PMID: 33343875 PMCID: PMC7739911 DOI: 10.1098/rsfs.2019.0136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2020] [Indexed: 12/27/2022] Open
Abstract
Osteoporosis is a bone disease characterized by brittle bone and increased fracture incidence. With ageing societies worldwide, the disease presents a high burden on health systems. Furthermore, there are limited treatments for osteoporosis with just two anabolic pharmacological agents approved by the US Food and Drug Administration. Healthy bones are believed to be maintained via an intricate relationship between dual biochemical and mechanical (bio-mechanical) stimulations. It is widely considered that osteoporosis emerges as a result of disturbances to said relationship. The mechanotransduction process is key to this balance, and disruption of its dynamics in bone cells plays a role in osteoporosis development. Nonetheless, the exact details and mechanisms that drive and secure the health of bones are still elusive at the cellular and molecular scales. This study examined the dual modulation of mechanical stimulation and mechanotransduction activation dynamics in an osteoblast (OB). The aim was to find patterns of mechanotransduction dynamics demonstrating a significant change that can be mapped to alterations in the OB responses, specifically at the level of gene expression and osteogenic markers such as alkaline phosphatase. This was achieved using a three-dimensional hybrid multiscale computational model simulating mechanotransduction in the OB and its interaction with the extracellular matrix, combined with a numerical analytical technique. The model and the analysis method predict that within the noise of mechanotransduction, owing to modulation of the bio-mechanical stimulus and consequent gene expression, there are unique events that provide signatures for a shift in the system's dynamics. Furthermore, the study uncovered molecular interactions that can be potential drug targets.
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Affiliation(s)
- Gianluca Ascolani
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
| | - Timothy M. Skerry
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Damien Lacroix
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
- Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Enrico Dall'Ara
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
| | - Aban Shuaib
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
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17
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Ou M, Huang X. Influence of bone formation by composite scaffolds with different proportions of hydroxyapatite and collagen. Dent Mater 2021; 37:e231-e244. [PMID: 33509634 DOI: 10.1016/j.dental.2020.12.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 11/14/2020] [Accepted: 12/30/2020] [Indexed: 10/22/2022]
Abstract
Composite scaffolds with different proportions of hydroxyapatite (HA) and collagen (COL) produced different bone induction results. OBJECTIVE To examine the composite scaffolds with optimal proportion of HA and COL to achieve earlier bone induction and maximum bone formation. METHODS Composite scaffolds with the HA/COL weight ratio of 7:3, 3:7, 5:5 and 9:1 were prepared, as HA powder was added to collagen solution at 130℃ for 48 h. Then, the composites with different proportions of HA/COL were implanted into the extraction socket of right upper central incisor of C57BL/6 J mice. The bone formation of the extraction socket was observed by Hematoxylin-eosin (HE) and Masson-trichrome (Masson) staining at 1 and 2 weeks after operation. Five weeks later, the bone formation of extraction socket was observed by micro computed tomography (micro-CT). After MC3T3-E1 cells were co-cultured with materials of different proportions for 3 days, the number of cells attached on the surface of the materials and entering the materials were counted, and the expression of osteogenic related genes (Runx2, Ocn. Osx and Alp) was detected by reverse transcription polymerase chain reaction (RT-PCR). The composite scaffolds with different proportion of HA/COL with and without mouse bone marrow mesenchymal stem cells (BMMSCs) were implanted into the back of adult mice and cultured subcutaneously for 30 days, and observed histologically by HE and Masson staining. RESULTS After one week implantation with the composite HA/COL scaffolds with the weight ratio of 7:3, 3:7, 5:5 and 9:1, there was no new bone formation in the extraction socket in mouse. However, two weeks later, new bone was firstly observed in the tooth socket with the composite HA/COL scaffolds of 7:3. 5 weeks later, micro-CT scanning showed that the total amount of newly formed bone, trabecular width and bone mineral density of the HA/COL scaffolds of 7:3 were higher than the other HA/COL scaffolds (P < 0.05). After MC3T3-E1 cells were co-cultured with different composite HA/COL scaffolds for 3 days. The number of cells on the surface and inside of the HA/COL scaffolds of 7:3 was more than the other materials, and the difference was statistically significant (P < 0.05). The expression levels of Ocn and Osx of MC3T3-E1 cells were also the highest in the HA/COL scaffolds of 7:3 (P < 0.01). Bone formation was observed in the composite HA/COL scaffold of 7:3 with BMMSCs subcutaneously in mouse for 30 days, while only osteoid formation was observed in the same scaffold without BMMSCs. but bone formation was not detected in the other proportions of the HA/COL scaffolds. SIGNIFICANCE Compared with other proportions of HA/COL, the composite HA/COL scaffolds of 7:3 has stronger ability to promote bone formation, recruit osteoblasts to attach and enter into the scaffolds, and promote the osteogenesis of BMMSCs.
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Affiliation(s)
- Mingming Ou
- Department of Stomatology, Beijing Friendship Hospital, Capital Medical University, Beijing, China; Immunology Research Center for Oral and Systemic Health, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Xiaofeng Huang
- Department of Stomatology, Beijing Friendship Hospital, Capital Medical University, Beijing, China; Immunology Research Center for Oral and Systemic Health, Beijing Friendship Hospital, Capital Medical University, Beijing, China.
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18
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Qi S, Sun X, Choi HK, Yao J, Wang L, Wu G, He Y, Pan J, Guan JL, Liu F. FAK Promotes Early Osteoprogenitor Cell Proliferation by Enhancing mTORC1 Signaling. J Bone Miner Res 2020; 35:1798-1811. [PMID: 32286710 PMCID: PMC7486225 DOI: 10.1002/jbmr.4029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/16/2020] [Accepted: 04/05/2020] [Indexed: 02/05/2023]
Abstract
Focal adhesion kinase (FAK) has important functions in bone homeostasis but its role in early osteoprogenitor cells is unknown. We show herein that mice lacking FAK in Dermo1-expressing cells exhibited low bone mass and decreased osteoblast number. Mechanistically, FAK-deficient early osteoprogenitor cells had decreased proliferation and significantly reduced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, a central regulator of cell growth and proliferation. Furthermore, our data showed that the pharmacological inhibition of FAK kinase-dependent function alone was sufficient to decrease the proliferation and compromise the mineralization of early osteoprogenitor cells. In contrast to the Fak deletion in early osteoprogenitor cells, FAK loss in Col3.6 Cre-targeted osteoblasts did not cause bone loss, and Fak deletion in osteoblasts did not affect proliferation, differentiation, and mTORC1 signaling but increased the level of active proline-rich tyrosine kinase 2 (PYK2), which belongs to the same non-receptor tyrosine kinase family as FAK. Importantly, mTORC1 signaling in bone marrow stromal cells (BMSCs) was reduced if FAK kinase was inhibited at the early osteogenic differentiation stage. In contrast, mTORC1 signaling in BMSCs was not affected if FAK kinase was inhibited at a later osteogenic differentiation stage, in which, however, the concomitant inhibition of both FAK kinase and PYK2 kinase reduced mTORC1 signaling. In summary, our data suggest that FAK promotes early osteoprogenitor cell proliferation by enhancing mTORC1 signaling via its kinase-dependent function and the loss of FAK in osteoblasts can be compensated by the upregulated active PYK2. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Shuqun Qi
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Xiumei Sun
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Orthodontics, Jilin University School and Hospital of Stomatology, Changchun, China
| | - Han Kyoung Choi
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Jinfeng Yao
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Stomatology, The Second People's Hospital of Shenzhen, Shenzhen, China
| | - Li Wang
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Guomin Wu
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Orthodontics, Jilin University School and Hospital of Stomatology, Changchun, China
| | - Yun He
- Department of Biologic and Materials Sciences and Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Dental Department, College of Medicine, Chengdu University, Chengdu, China
| | - Jian Pan
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - 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 Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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19
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Zhang Z, Hu P, Wang Z, Qiu X, Chen Y. BDNF promoted osteoblast migration and fracture healing by up-regulating integrin β1 via TrkB-mediated ERK1/2 and AKT signalling. J Cell Mol Med 2020; 24:10792-10802. [PMID: 32803867 PMCID: PMC7521296 DOI: 10.1111/jcmm.15704] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 07/12/2020] [Accepted: 07/14/2020] [Indexed: 12/17/2022] Open
Abstract
Brain‐derived neurotrophic factor (BDNF) has been reported to participate in fracture healing, whereas the mechanism is still unclear. Since osteoblast migration is important for fracture healing, investigating effects of BDNF on osteoblasts migration may help to reveal its mechanism. Here, MC3T3‐E1 cells were used in vitro while closed femur fracture mice were applied in vivo. Cells migration was assessed with Transwell assay. The protein expression was analysed by immunoblotting. X‐ray and Micro‐CT were performed at different time after fracture. Our results showed that BDNF promoted MC3T3‐E1 cells migration, integrin β1 expression and ERK1/2 and AKT phosphorylation. K252a, a specific inhibitor for TrkB, suppressed BDNF‐induced migration, integrin β1 expression and activation of ERK1/2 and AKT. PD98059 (an ERK1/2 inhibitor) and LY294002 (an AKT inhibitor) both inhibited BDNF‐induced migration and integrin β1 expression while integrin β1 blocking antibody only suppressed cell migration. X‐ray and Micro‐CT analyses showed that the adenoviral carried integrin β1 shRNA group had slower fracture healing at 7 and 21 days, but not 35 days compared to the control group. Thus, we proposed that BDNF stimulated MC3T3‐E1 cells migration by up‐regulating integrin β1 via TrkB mediated ERK1/2 and AKT signalling, and this may help to enhance the fracture healing.
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Affiliation(s)
- Zitao Zhang
- Department of Orthopedics, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Polu Hu
- Nanjing Red Cross Blood Center, Nanjing, China
| | - Zhen Wang
- Department of Orthopedics, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Xusheng Qiu
- Department of Orthopedics, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
| | - Yixin Chen
- Department of Orthopedics, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China
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20
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Qin L, Liu W, Cao H, Xiao G. Molecular mechanosensors in osteocytes. Bone Res 2020; 8:23. [PMID: 32550039 PMCID: PMC7280204 DOI: 10.1038/s41413-020-0099-y] [Citation(s) in RCA: 186] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 04/07/2020] [Accepted: 04/17/2020] [Indexed: 12/11/2022] Open
Abstract
Osteocytes, the most abundant and long-lived cells in bone, are the master regulators of bone remodeling. In addition to their functions in endocrine regulation and calcium and phosphate metabolism, osteocytes are the major responsive cells in force adaptation due to mechanical stimulation. Mechanically induced bone formation and adaptation, disuse-induced bone loss and skeletal fragility are mediated by osteocytes, which sense local mechanical cues and respond to these cues in both direct and indirect ways. The mechanotransduction process in osteocytes is a complex but exquisite regulatory process between cells and their environment, between neighboring cells, and between different functional mechanosensors in individual cells. Over the past two decades, great efforts have focused on finding various mechanosensors in osteocytes that transmit extracellular mechanical signals into osteocytes and regulate responsive gene expression. The osteocyte cytoskeleton, dendritic processes, Integrin-based focal adhesions, connexin-based intercellular junctions, primary cilium, ion channels, and extracellular matrix are the major mechanosensors in osteocytes reported so far with evidence from both in vitro and in vitro studies. This review aims to give a systematic introduction to osteocyte mechanobiology, provide details of osteocyte mechanosensors, and discuss the roles of osteocyte mechanosensitive signaling pathways in the regulation of bone homeostasis.
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Affiliation(s)
- Lei Qin
- Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, and School of Medicine, Southern University of Science and Technology, Shenzhen, 518055 China
| | - Wen Liu
- Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, and School of Medicine, Southern University of Science and Technology, Shenzhen, 518055 China
| | - Huiling Cao
- Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, and School of Medicine, Southern University of Science and Technology, Shenzhen, 518055 China
| | - Guozhi Xiao
- Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Shenzhen Key Laboratory of Cell Microenvironment, and School of Medicine, Southern University of Science and Technology, Shenzhen, 518055 China
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21
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Ascolani G, Skerry TM, Lacroix D, Dall'Ara E, Shuaib A. Revealing hidden information in osteoblast's mechanotransduction through analysis of time patterns of critical events. BMC Bioinformatics 2020; 21:114. [PMID: 32183690 PMCID: PMC7079370 DOI: 10.1186/s12859-020-3394-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 02/04/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Mechanotransduction in bone cells plays a pivotal role in osteoblast differentiation and bone remodelling. Mechanotransduction provides the link between modulation of the extracellular matrix by mechanical load and intracellular activity. By controlling the balance between the intracellular and extracellular domains, mechanotransduction determines the optimum functionality of skeletal dynamics. Failure of this relationship was suggested to contribute to bone-related diseases such as osteoporosis. RESULTS A hybrid mechanical and agent-based model (Mech-ABM), simulating mechanotransduction in a single osteoblast under external mechanical perturbations, was utilised to simulate and examine modulation of the activation dynamics of molecules within mechanotransduction on the cellular response to mechanical stimulation. The number of molecules and their fluctuations have been analysed in terms of recurrences of critical events. A numerical approach has been developed to invert subordination processes and to extract the direction processes from the molecular signals in order to derive the distribution of recurring events. These predict that there are large fluctuations enclosing information hidden in the noise which is beyond the dynamic variations of molecular baselines. Moreover, studying the system under different mechanical load regimes and altered dynamics of feedback loops, illustrate that the waiting time distributions of each molecule are a signature of the system's state. CONCLUSIONS The behaviours of the molecular waiting times change with the changing of mechanical load regimes and altered dynamics of feedback loops, presenting the same variation of patterns for similar interacting molecules and identifying specific alterations for key molecules in mechanotransduction. This methodology could be used to provide a new tool to identify potent molecular candidates to modulate mechanotransduction, hence accelerate drug discovery towards therapeutic targets for bone mass upregulation.
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Affiliation(s)
- Gianluca Ascolani
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
| | - Timothy M Skerry
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Damien Lacroix
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
- Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Enrico Dall'Ara
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK
| | - Aban Shuaib
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK.
- Insigneo Institute of In Silico Medicine, University of Sheffield, Sheffield, UK.
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22
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Zhang Y, Zhan Y, Kou Y, Yin X, Wang Y, Zhang D. Identification of biological pathways and genes associated with neurogenic heterotopic ossification by text mining. PeerJ 2020; 8:e8276. [PMID: 31915578 PMCID: PMC6944123 DOI: 10.7717/peerj.8276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 11/22/2019] [Indexed: 12/12/2022] Open
Abstract
Background Neurogenic heterotopic ossification is a disorder of aberrant bone formation affecting one in five patients sustaining a spinal cord injury or traumatic brain injury (SCI-TBI-HO). However, the underlying mechanisms of SCI-TBI-HO have proven difficult to elucidate. The aim of the present study is to identify the most promising candidate genes and biological pathways for SCI-TBI-HO. Methods In this study, we used text mining to generate potential explanations for SCI-TBI-HO. Moreover, we employed several additional datasets, including gene expression profile data, drug data and tissue-specific gene expression data, to explore promising genes that associated with SCI-TBI-HO. Results We identified four SCI-TBI-HO-associated genes, including GDF15, LDLR, CCL2, and CLU. Finally, using enrichment analysis, we identified several pathways, including integrin signaling, insulin pathway, internalization of ErbB1, urokinase-type plasminogen activator and uPAR-mediated signaling, PDGFR-beta signaling pathway, EGF receptor (ErbB1) signaling pathway, and class I PI3K signaling events, which may be associated with SCI-TBI-HO. Conclusions These results enhance our understanding of the molecular mechanisms of SCI-TBI-HO and offer new leads for researchers and innovative therapeutic strategies.
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Affiliation(s)
- Yichong Zhang
- Department of Trauma and Orthopaedic Surgery, Peking University People's Hospital, Beijing, China
| | - Yuanbo Zhan
- Department of Periodontology and Oral Mucosa, the Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Yuhui Kou
- Department of Trauma and Orthopaedic Surgery, Peking University People's Hospital, Beijing, China
| | - Xiaofeng Yin
- Department of Trauma and Orthopaedic Surgery, Peking University People's Hospital, Beijing, China
| | - Yanhua Wang
- Department of Trauma and Orthopaedic Surgery, Peking University People's Hospital, Beijing, China
| | - Dianying Zhang
- Department of Trauma and Orthopaedic Surgery, Peking University People's Hospital, Beijing, China
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Shuaib A, Motan D, Bhattacharya P, McNabb A, Skerry TM, Lacroix D. Heterogeneity in The Mechanical Properties of Integrins Determines Mechanotransduction Dynamics in Bone Osteoblasts. Sci Rep 2019; 9:13113. [PMID: 31511609 PMCID: PMC6739315 DOI: 10.1038/s41598-019-47958-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/26/2019] [Indexed: 12/15/2022] Open
Abstract
Bone cells are exposed to dynamic mechanical stimulation that is transduced into cellular responses by mechanotransduction mechanisms. The extracellular matrix (ECM) provides a physical link between loading and bone cells, where mechanoreceptors, such as integrins, initiate mechanosensation. Though this relationship is well studied, the dynamic interplay between mechanosensation, mechanotransduction and cellular responses is unclear. A hybrid-multiscale model combining molecular, cellular and tissue interactions was developed to examine links between integrins’ mechanosensation and effects on mechanotransduction, ECM modulation and cell-ECM interaction. The model shows that altering integrin mechanosensitivity threshold (MT) increases mechanotransduction durations from hours to beyond 4 days, where bone formation starts. This is relevant to bone, where it is known that a brief stimulating period provides persistent influences for over 24 hours. Furthermore, the model forecasts that integrin heterogeneity, with respect to MT, would be able to induce sustained increase in pERK baseline > 15% beyond 4 days. This is analogous to the emergence of molecular mechanical memory signalling dynamics. Therefore, the model can provide a greater understanding of mechanical adaptation to differential mechanical responses at different times. Given reduction of bone sensitivity to mechanical stimulation with age, these findings may lead towards useful therapeutic targets for upregulation of bone mass.
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Affiliation(s)
- Aban Shuaib
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK. .,Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK.
| | - Daniyal Motan
- Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Pinaki Bhattacharya
- Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK.,Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Alex McNabb
- Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
| | - Timothy M Skerry
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Damien Lacroix
- Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK.,Department of Mechanical Engineering, University of Sheffield, Sheffield, UK
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Li YY, Lam KL, Chen AD, Zhang W, Chan BP. Collagen microencapsulation recapitulates mesenchymal condensation and potentiates chondrogenesis of human mesenchymal stem cells – A matrix-driven in vitro model of early skeletogenesis. Biomaterials 2019; 213:119210. [DOI: 10.1016/j.biomaterials.2019.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/28/2019] [Accepted: 05/10/2019] [Indexed: 01/01/2023]
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Shen B, Vardy K, Hughes P, Tasdogan A, Zhao Z, Yue R, Crane GM, Morrison SJ. Integrin alpha11 is an Osteolectin receptor and is required for the maintenance of adult skeletal bone mass. eLife 2019; 8:42274. [PMID: 30632962 PMCID: PMC6349404 DOI: 10.7554/elife.42274] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/05/2019] [Indexed: 12/13/2022] Open
Abstract
We previously discovered a new osteogenic growth factor that is required to maintain adult skeletal bone mass, Osteolectin/Clec11a. Osteolectin acts on Leptin Receptor+ (LepR+) skeletal stem cells and other osteogenic progenitors in bone marrow to promote their differentiation into osteoblasts. Here we identify a receptor for Osteolectin, integrin α11, which is expressed by LepR+ cells and osteoblasts. α11β1 integrin binds Osteolectin with nanomolar affinity and is required for the osteogenic response to Osteolectin. Deletion of Itga11 (which encodes α11) from mouse and human bone marrow stromal cells impaired osteogenic differentiation and blocked their response to Osteolectin. Like Osteolectin deficient mice, Lepr-cre; Itga11fl/fl mice appeared grossly normal but exhibited reduced osteogenesis and accelerated bone loss during adulthood. Osteolectin binding to α11β1 promoted Wnt pathway activation, which was necessary for the osteogenic response to Osteolectin. This reveals a new mechanism for maintenance of adult bone mass: Wnt pathway activation by Osteolectin/α11β1 signaling. Throughout our lives, our bones undergo constant remodeling. Cells called osteoclasts break down old bone and cells called osteoblasts lay down new. Normally, the two cell types work in balance but if the rate of breakdown outpaces new bone formation the skeleton can become weak. This weakness leads to a condition called osteoporosis, in which people suffer from fragile bones. Osteoporosis is hard to reverse, in part because our ability to encourage new bone to form is limited. In 2016, researchers discovered a protein called osteolectin, which promotes new bone formation during adulthood by helping skeletal stem cells transform into bone cells. But so far, it has been unclear how osteolectin achieves this. To investigate this further, Shen et al. – including some researchers involved in the 2016 study – marked osteolectin with a molecular tag and tested what it bound on the surface of mouse and human bone marrow cells. The experiments revealed that osteolectin binds to a specific receptor protein called α11 integrin, which can only be found on skeletal stem cells and the osteoblasts they give rise to. Once osteolectin binds to the receptor, it activates a signaling pathway that induces the stem cells to develop into osteoblasts. Mice that lacked either osteolectin or α11 integrin produced less bone and lost bone tissue faster as adults. Osteolectin could potentially be useful in the treatment of osteoporosis or broken bones. Since only skeletal stem cells and osteoblasts cells produce α11 integrin, osteolectin would specifically target these cells without affecting cells that do not form bones. A next step will be to assess how well osteolectin compares to existing treatments for fragile bones.
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Affiliation(s)
- Bo Shen
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Kristy Vardy
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Payton Hughes
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Alpaslan Tasdogan
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Zhiyu Zhao
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Rui Yue
- Institute of Regenerative Medicine, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Genevieve M Crane
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Sean J Morrison
- Children's Research Institute, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
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26
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Chang C, Xi L, Zhang J, Zhao W, Liu Z, Guo J, Xu C. Roles of Cyclin A, Myc, Jun and Ppm1l in tumourigenic transformation of NIH3T3 cell. J Genet 2018; 97:1155-1168. [PMID: 30555065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To analyse the mechanism of tumourigenic transformation of NIH3T3 cells at the transcriptional level, we used cancerogen 3-methylcholanthrene (3-MCA) and cancerogenic substance phorbol-12-myristate-13-acetate (PMA) to transform NIH3T3 cells and the assessment of transformation was performed using Giemsa staining and methylcellulose colony formation assay. Changes in gene expression profile were detected by Mouse Genome 430 2.0 microarray; and quantitative real-time polymerase chain reaction and Western blotting were used to verify the expression changes of mRNAs and proteins, respectively. With the aid of bioinformatics method, five signalling pathways were identified to participate in different stages of NIH3T3 cell transformation. Further, our study suggested that oncogenes Cyclin A, Myc, Jun and the tumour suppressor gene Ppm1l may play important roles in these pathways.
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Affiliation(s)
- Cuifang Chang
- State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang 453007, People's Republic of China.
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ACVR1 is essential for periodontium development and promotes alveolar bone formation. Arch Oral Biol 2018; 95:108-117. [PMID: 30098439 DOI: 10.1016/j.archoralbio.2018.07.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 07/10/2018] [Accepted: 07/30/2018] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To explore the role of a BMP type I receptor (ACVR1) in regulating periodontium development, Acvr1 was conditionally disrupted in Osterix-expressing cells. METHODS Mandibles from both control (Acvr1 fx/+; Osterix-Cre (+)/(-)) and cKO (Acvr1 fx/-; Osterix-Cre (+)/(-)) mice at postnatal day 21 (PN21) were scanned by micro-CT, followed by decalcification and histological observations. Distributions and levels of differentiation markers of fibroblasts, osteoblasts and cementocytes in the periodontium were detected by immunohistochemical (IHC) staining. RESULTS Micro-CT results showed that bone mass and bone mineral density of the alveolar bones in the cKO mice were lower than those in the controls. Histomorphometry within the alveolar bones revealed that the lower bone mass observed in the cKO mice was caused by increased numbers and resorption activities of osteoclasts. The markers for osteoblast differentiation, Col I and DMP1, were reduced and the signals of the RANKL/OPG ratio were increased in the alveolar bones of the cKO mice compared to those of the control mice. The periodontal ligament in the cKO mice exhibited disorganized collagen fibers with weaker signals of Col I and periostin. However, there was no difference in terms of the cellular cementum between the two groups. CONCLUSION ACVR1 is essential for normal periodontium development. ACVR1 in the osteoblasts negatively regulates osteoclast differentiation in association with the RANKL/OPG axis and thus promotes alveolar bone formation.
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Hydrogel delivery of lysostaphin eliminates orthopedic implant infection by Staphylococcus aureus and supports fracture healing. Proc Natl Acad Sci U S A 2018; 115:E4960-E4969. [PMID: 29760099 PMCID: PMC5984524 DOI: 10.1073/pnas.1801013115] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Orthopedic implant infections require long-term antibiotic therapy and surgical debridement to successfully retain the implant; however, therapeutic failure can lead to implant removal. Here an injectable PEG-based hydrogel that adheres to exposed tissue and fracture surfaces is engineered to deliver the antimicrobial enzyme lysostaphin to infected, implant-fixed, mouse femoral fractures. Lysostaphin encapsulation within the hydrogel enhances enzyme stability while providing enhanced antibiofilm activity and serving as a controlled delivery platform. In a preclinical animal model of orthopedic-implant infection, we show that lysostaphin-delivering hydrogels outperform prophylactic antibiotic therapy and soluble lysostaphin, by eradicating infection while promoting bone repair. Importantly, lysostaphin-delivering hydrogels are effective against antibiotic-resistant infections. This lysostaphin delivery platform could be highly effective at treating and preventing implant infections. Orthopedic implant infections are a significant clinical problem, with current therapies limited to surgical debridement and systemic antibiotic regimens. Lysostaphin is a bacteriolytic enzyme with high antistaphylococcal activity. We engineered a lysostaphin-delivering injectable PEG hydrogel to treat Staphylococcus aureus infections in bone fractures. The injectable hydrogel formulation adheres to exposed tissue and fracture surfaces, ensuring efficient, local delivery of lysostaphin. Lysostaphin encapsulation within this synthetic hydrogel maintained enzyme stability and activity. Lysostaphin-delivering hydrogels exhibited enhanced antibiofilm activity compared with soluble lysostaphin. Lysostaphin-delivering hydrogels eradicated S. aureus infection and outperformed prophylactic antibiotic and soluble lysostaphin therapy in a murine model of femur fracture. Analysis of the local inflammatory response to infections treated with lysostaphin-delivering hydrogels revealed indistinguishable differences in cytokine secretion profiles compared with uninfected fractures, demonstrating clearance of bacteria and associated inflammation. Importantly, infected fractures treated with lysostaphin-delivering hydrogels fully healed by 5 wk with bone formation and mechanical properties equivalent to those of uninfected fractures, whereas fractures treated without the hydrogel carrier were equivalent to untreated infections. Finally, lysostaphin-delivering hydrogels eliminate methicillin-resistant S. aureus infections, supporting this therapy as an alternative to antibiotics. These results indicate that lysostaphin-delivering hydrogels effectively eliminate orthopedic S. aureus infections while simultaneously supporting fracture repair.
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Brunner M, Mandier N, Gautier T, Chevalier G, Ribba AS, Guardiola P, Block MR, Bouvard D. β1 integrins mediate the BMP2 dependent transcriptional control of osteoblast differentiation and osteogenesis. PLoS One 2018; 13:e0196021. [PMID: 29677202 PMCID: PMC5909894 DOI: 10.1371/journal.pone.0196021] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/04/2018] [Indexed: 12/05/2022] Open
Abstract
Osteoblast differentiation is a highly regulated process that requires coordinated information from both soluble factors and the extracellular matrix. Among these extracellular stimuli, chemical and physical properties of the matrix are sensed through cell surface receptors such as integrins and transmitted into the nucleus to drive specific gene expression. Here, we showed that the conditional deletion of β1 integrins in the osteo-precursor population severely impacts bone formation and homeostasis both in vivo and in vitro. Mutant mice displayed a severe bone deficit characterized by bone fragility and reduced bone mass. We showed that β1 integrins are required for proper BMP2 dependent signaling at the pre-osteoblastic stage, by positively modulating Smad1/5-dependent transcriptional activity at the nuclear level. The lack of β1 integrins results in a transcription modulation that relies on a cooperative defect with other transcription factors rather than a plain blunted BMP2 response. Our results point to a nuclear modulation of Smad1/5 transcriptional activity by β1 integrins, allowing a tight control of osteoblast differentiation.
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Affiliation(s)
- Molly Brunner
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
| | - Noémie Mandier
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
| | - Thierry Gautier
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
| | - Genevieve Chevalier
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
| | - Anne-Sophie Ribba
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
| | - Philippe Guardiola
- Centre Hospitalier Universitaire and University of Angers, SNP Plateform, Institute for Biological Health, Transcriptome and Epigenomic, Angers, France
| | - Marc R. Block
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
| | - Daniel Bouvard
- Centre de Recherche INSERM 1209, CNRS 5309, Institute for Advanced Bioscience; Université Grenoble Alpes, Grenoble, France
- * E-mail:
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31
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Cabahug-Zuckerman P, Stout RF, Majeska RJ, Thi MM, Spray DC, Weinbaum S, Schaffler MB. Potential role for a specialized β 3 integrin-based structure on osteocyte processes in bone mechanosensation. J Orthop Res 2018; 36:642-652. [PMID: 29087614 PMCID: PMC5839970 DOI: 10.1002/jor.23792] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 10/21/2017] [Indexed: 02/04/2023]
Abstract
Osteocyte processes are an order of magnitude more sensitive to mechanical loading than their cell bodies. The mechanisms underlying this remarkable mechanosensitivity are not clear, but may be related to the infrequent αV β3 integrin sites where the osteocyte cell processes attach to canalicular walls. These sites develop dramatically elevated strains during load-induced fluid flow in the lacunar-canalicular system and were recently shown to be primary sites for osteocyte-like MLO-Y4 cell mechanotransduction. These αV β3 integrin sites lack typical integrin transduction mechanisms. Rather, stimulation at these sites alters Ca2+ signaling, ATP release and membrane potential. In the current studies, we tested the hypothesis that in authentic osteocytes in situ, key membrane proteins implicated in osteocyte mechanotransduction are preferentially localized at or near to β3 integrin-foci. We analyzed these spatial relationships in mouse bone osteocytes using immunohistochemistry combined with Structured Illumination Super Resolution Microscopy, a method that permits structural resolution at near electron microscopy levels in tissue sections. We discovered that the purinergic channel pannexin1, the ATP-gated purinergic receptor P2 × 7R and the low voltage transiently opened T-type calcium channel CaV3.2-1 all reside in close proximity to β3 integrin attachment foci on osteocyte processes, suggesting a specialized mechanotransduction complex at these sites. We further confirmed this observation on isolated osteocytes in culture using STochasitc Optical Resonance Microscopy. These findings identify a possible structural basis for the unique mechanosensation and transduction capabilities of the osteocyte process. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:642-652, 2018.
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Affiliation(s)
| | - Randy F. Stout
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine
- Department of Neuroscience, Albert Einstein College of Medicine
| | | | - Mia M. Thi
- Department of Orthopaedic Surgery, Albert Einstein College of Medicine
| | - David C. Spray
- Department of Neuroscience, Albert Einstein College of Medicine
| | - Sheldon Weinbaum
- Department of Biomedical Engineering, The City College of New York
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Dejaeger M, Böhm AM, Dirckx N, Devriese J, Nefyodova E, Cardoen R, St-Arnaud R, Tournoy J, Luyten FP, Maes C. Integrin-Linked Kinase Regulates Bone Formation by Controlling Cytoskeletal Organization and Modulating BMP and Wnt Signaling in Osteoprogenitors. J Bone Miner Res 2017; 32:2087-2102. [PMID: 28574598 DOI: 10.1002/jbmr.3190] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 05/28/2017] [Accepted: 05/31/2017] [Indexed: 12/19/2022]
Abstract
Cell-matrix interactions constitute a fundamental aspect of skeletal cell biology and play essential roles in bone homeostasis. These interactions are primarily mediated by transmembrane integrin receptors, which mediate cell adhesion and transduce signals from the extracellular matrix to intracellular responses via various downstream effectors, including integrin-linked kinase (ILK). ILK functions as adaptor protein at focal adhesion sites, linking integrins to the actin cytoskeleton, and has been reported to act as a kinase phosphorylating signaling molecules such as GSK-3β and Akt. Thereby, ILK plays important roles in cellular attachment, motility, proliferation and survival. To assess the in vivo role of ILK signaling in osteoprogenitors and the osteoblast lineage cells descending thereof, we generated conditional knockout mice using the Osx-Cre:GFP driver strain. Mice lacking functional ILK in osterix-expressing cells and their derivatives showed no apparent developmental or growth phenotype, but by 5 weeks of age they displayed a significantly reduced trabecular bone mass, which persisted into adulthood in male mice. Histomorphometry and serum analysis indicated no alterations in osteoclast formation and activity, but provided evidence that osteoblast function was impaired, resulting in reduced bone mineralization and increased accumulation of unmineralized osteoid. In vitro analyses further substantiated that absence of ILK in osteogenic cells was associated with compromised collagen matrix production and mineralization. Mechanistically, we found evidence for both impaired cytoskeletal functioning and reduced signal transduction in osteoblasts lacking ILK. Indeed, loss of ILK in primary osteogenic cells impaired F-actin organization, cellular adhesion, spreading, and migration, indicative of defective coupling of cell-matrix interactions to the cytoskeleton. In addition, BMP/Smad and Wnt/β-catenin signaling was reduced in the absence of ILK. Taken together, these data demonstrate the importance of integrin-mediated cell-matrix interactions and ILK signaling in osteoprogenitors in the control of osteoblast functioning during juvenile bone mass acquisition and adult bone remodeling and homeostasis. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Marian Dejaeger
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Anna-Marei Böhm
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Naomi Dirckx
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Joke Devriese
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Elena Nefyodova
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Ruben Cardoen
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - René St-Arnaud
- Shriners Hospital for Children, McGill University, Montreal, Canada
| | - Jos Tournoy
- Geriatric Medicine, University Hospitals Leuven, Leuven, Belgium.,Department of Clinical and Experimental Medicine, KU Leuven, Leuven, Belgium
| | - Frank P Luyten
- Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Christa Maes
- Laboratory of Skeletal Cell Biology and Physiology (SCEBP), Skeletal Biology and Engineering Research Center (SBE), Department of Development and Regeneration, KU Leuven, Leuven, Belgium
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Fraioli R, Dashnyam K, Kim JH, Perez RA, Kim HW, Gil J, Ginebra MP, Manero JM, Mas-Moruno C. Surface guidance of stem cell behavior: Chemically tailored co-presentation of integrin-binding peptides stimulates osteogenic differentiation in vitro and bone formation in vivo. Acta Biomater 2016; 43:269-281. [PMID: 27481289 DOI: 10.1016/j.actbio.2016.07.049] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 07/11/2016] [Accepted: 07/29/2016] [Indexed: 12/20/2022]
Abstract
UNLABELLED Surface modification stands out as a versatile technique to create instructive biomaterials that are able to actively direct stem cell fate. Chemical functionalization of titanium has been used in this work to stimulate the differentiation of human mesenchymal stem cells (hMSCs) into the osteoblastic lineage, by covalently anchoring a synthetic double-branched molecule (PTF) to the metal that allows a finely controlled presentation of peptidic motifs. In detail, the effect of the RGD adhesive peptide and its synergy motif PHSRN is studied, comparing a random distribution of the two peptides with the chemically-tailored disposition within the custom made synthetic platform, which mimics the interspacing between the motifs observed in fibronectin. Contact angle measurement and XPS analysis are used to prove the efficiency of functionalization. We demonstrate that, by rationally designing ligands, stem cell response can be efficiently guided towards the osteogenic phenotype: In vitro, PTF-functionalized surfaces support hMSCs adhesion, with higher cell area and formation of focal contacts, expression of the integrin receptor α5β1 and the osteogenic marker Runx2, and deposition a highly mineralized matrix, reaching values of mineralization comparable to fibronectin. Our strategy is also demonstrated to be efficient in promoting new bone growth in vivo in a rat calvarial defect. These results highlight the efficacy of chemical control over the presentation of bioactive peptides; such systems may be used to engineer bioactive surfaces with improved osseointegrative properties, or can be easily tuned to generate multi-functional coatings requiring a tailored disposition of the peptidic motifs. STATEMENT OF SIGNIFICANCE Organic coatings have been proposed as a solution to foster osseointegration of orthopedic implants. Among them, extracellular matrix-derived peptide motifs are an interesting biomimetic strategy to harness cell-surface interactions. Nonetheless, the combination of multiple peptide motifs in a controlled manner is essential to achieve receptor specificity and fully exploit the potentiality of synthetic peptides. Herein, we covalently graft to titanium a double branched molecule to guide stem cell fate in vitro and generate an osseoinductive titanium surface in vivo. Such synthetic ligand allows for the simultaneous presentation of two bioactive motifs, thus is ideal to test the effect of synergic sequences, such as RGD and PHSRN, and is a clear example of the versatility and feasibility of rationally designed biomolecules.
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Multiple essential MT1-MMP functions in tooth root formation, dentinogenesis, and tooth eruption. Matrix Biol 2016; 52-54:266-283. [PMID: 26780723 DOI: 10.1016/j.matbio.2016.01.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 01/07/2016] [Accepted: 01/07/2016] [Indexed: 11/23/2022]
Abstract
Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a transmembrane zinc-endopeptidase that breaks down extracellular matrix components, including several collagens, during tissue development and physiological remodeling. MT1-MMP-deficient mice (MT1-MMP(-/-)) feature severe defects in connective tissues, such as impaired growth, osteopenia, fibrosis, and conspicuous loss of molar tooth eruption and root formation. In order to define the functions of MT1-MMP during root formation and tooth eruption, we analyzed the development of teeth and surrounding tissues in the absence of MT1-MMP. In situ hybridization showed that MT1-MMP was widely expressed in cells associated with teeth and surrounding connective tissues during development. Multiple defects in dentoalveolar tissues were associated with loss of MT1-MMP. Root formation was inhibited by defective structure and function of Hertwig's epithelial root sheath (HERS). However, no defect was found in creation of the eruption pathway, suggesting that tooth eruption was hampered by lack of alveolar bone modeling/remodeling coincident with reduced periodontal ligament (PDL) formation and integration with the alveolar bone. Additionally, we identified a significant defect in dentin formation and mineralization associated with the loss of MT1-MMP. To segregate these multiple defects and trace their cellular origin, conditional ablation of MT1-MMP was performed in epithelia and mesenchyme. Mice featuring selective loss of MT1-MMP activity in the epithelium were indistinguishable from wild type mice, and importantly, featured a normal HERS structure and molar eruption. In contrast, selective knock-out of MT1-MMP in Osterix-expressing mesenchymal cells, including osteoblasts and odontoblasts, recapitulated major defects from the global knock-out including altered HERS structure, short roots, defective dentin formation and mineralization, and reduced alveolar bone formation, although molars were able to erupt. These data indicate that MT1-MMP activity in the dental mesenchyme, and not in epithelial-derived HERS, is essential for proper tooth root formation and eruption. In summary, our studies point to an indispensable role for MT1-MMP-mediated matrix remodeling in tooth eruption through effects on bone formation, soft tissue remodeling and organization of the follicle/PDL region.
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The role of "bone immunological niche" for a new pathogenetic paradigm of osteoporosis. Anal Cell Pathol (Amst) 2015; 2015:434389. [PMID: 26491648 PMCID: PMC4605147 DOI: 10.1155/2015/434389] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 09/09/2015] [Indexed: 12/13/2022] Open
Abstract
Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue. The etiology and pathogenetic mechanisms of osteoporosis have not been clearly elucidated. Osteoporosis is linked to bone resorption by the activation of the osteoclastogenic process. The breakdown of homeostasis among pro- and antiosteoclastogenic cells causes unbalanced bone remodeling. The complex interactions among these cells in the bone microenvironment involve several mediators and proinflammatory pathways. Thus, we may consider the bone microenvironment as a complex system in which local and systemic immunity are regulated and we propose to consider it as an "immunological niche." The study of the "bone immunological niche" will permit a better understanding of the complex cell trafficking which regulates bone resorption and disease. The goal of a perfect therapy for osteoporosis would be to potentiate good cells and block the bad ones. In this scenario, additional factors may take part in helping or hindering the proosteoblastogenic factors. Several proosteoblastogenic and antiosteoclastogenic agents have already been identified and some have been developed and commercialized as biological therapies for osteoporosis. Targeting the cellular network of the "bone immunological niche" may represent a successful strategy to better understand and treat osteoporosis and its complications.
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β2-Adrenergic signal transduction plays a detrimental role in subchondral bone loss of temporomandibular joint in osteoarthritis. Sci Rep 2015. [PMID: 26219508 PMCID: PMC4518212 DOI: 10.1038/srep12593] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The present study tested whether activation of the sympathetic tone by aberrant joint loading elicits abnormal subchondral bone remodeling in temporomandibular joint (TMJ) osteoarthritis. Abnormal dental occlusion was created in experimental rats, which were then intraperitoneally injected by saline, propranolol or isoproterenol. The norepinephrine contents, distribution of sympathetic nerve fibers, expression of β-adrenergic receptors (β-ARs) and remodeling parameters in the condylar subchondral bone were investigated. Mesenchymal stem cells (MSCs) from condylar subchondral bones were harvested for comparison of their β-ARs, pro-osteoclastic gene expressions and pro-osteoclastic function. Increases in norepinephrine level, sympathetic nerve fiber distribution and β2-AR expression were observed in the condylar subchondral bone of experimental rats, together with subchondral bone loss and increased osteoclast activity. β-antagonist (propranolol) suppressed subchondral bone loss and osteoclast hyperfunction while β-agonist (isoproterenol) exacerbated those responses. MSCs from experimental condylar subchondral bone expressed higher levels of β2-AR and RANKL; norepinephrine stimulation further increased their RANKL expression and pro-osteoclastic function. These effects were blocked by inhibition of β2-AR or the PKA pathway. RANKL expression by MSCs decreased after propranolol administration and increased after isoproterenol administration. It is concluded that β2-AR signal-mediated subchondral bone loss in TMJ osteoarthritisis associated with increased RANKL secretion by MSCs.
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Abstract
Skeletal loading is an important physiological regulator of bone mass. Theoretically, mechanical forces or administration of drugs that activate bone mechanosensors would be a novel treatment for osteoporotic disorders, particularly age-related osteoporosis and other bone loss caused by skeletal unloading. Uncertainty regarding the identity of the molecular targets that sense and transduce mechanical forces in bone, however, has limited the therapeutic exploitation of mechanosesning pathways to control bone mass. Recently, two evolutionally conserved mechanosensing pathways have been shown to function as "physical environment" sensors in cells of the osteoblasts lineage. Indeed, polycystin-1 (Pkd1, or PC1) and polycystin-2 (Pkd2, or PC2' or TRPP2), which form a flow sensing receptor channel complex, and TAZ (transcriptional coactivator with PDZ-binding motif, or WWTR1), which responds to the extracellular matrix microenvironment act in concert to reciprocally regulate osteoblastogenesis and adipogenesis through co-activating Runx2 and a co-repressing PPARγ activities. Interactions of polycystins and TAZ with other putative mechanosensing mechanism, such as primary cilia, integrins and hemichannels, may create multifaceted mechanosensing networks in bone. Moreover, modulation of polycystins and TAZ interactions identify novel molecular targets to develop small molecules that mimic the effects of mechanical loading on bone.
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Affiliation(s)
- Zhousheng Xiao
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN 38165, USA
| | - Leigh Darryl Quarles
- Department of Medicine, University of Tennessee Health Science Center, Memphis, TN 38165, USA
- Coleman College of Medicine Building, Suite B216, University of Tennessee Health Science Center, 956 Court Avenue, Memphis, TN 38163, USA
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