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Liu C, Liu J, Chen H. Overexpression of miR-7-5p Promoted Fracture Healing Through Inhibiting LRP4 and Activating Wnt/β-Catenin Pathway. INT J LOW EXTR WOUND 2024; 23:86-91. [PMID: 36883209 DOI: 10.1177/15347346231157443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Background. The bone healing after fracture had a great impact on the patients' life quality. However, how miR-7-5p participated in fracture healing has not been investigated. Methods. For in vitro studies, the pre-osteoblast cell line MC3T3-E1 was obtained. The male C57BL/6 mice were purchased for in vivo experiments, and the fracture model was constructed. Cell proliferation was determined by CCK8 assay, and alkaline phosphatase (ALP) activity was measured by commercial kit. Histological status was evaluated using H&E and TRAP staining. The RNA and protein levels were detected via RT-qPCR and western blotting, respectively. Results. Overexpression of miR-7-5p increased cell viability and ALP activity in vitro. Moreover, in vivo studies consistently indicated that transfection of miR-7-5p improved the histological status and increased the proportion of TRAP-positive cells. Overexpression of miR-7-5p suppressed LRP4 expression while upregulated Wnt/β-catenin pathway. Conclusion. MiR-7-5p decreased LRP4 level and further activated the Wnt/β-catenin signaling, facilitating the process of fracture healing.
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Affiliation(s)
- Changtie Liu
- The Orthopaedic Trauma, Ganzhou People's Hospital, Ganzhou, Jiangxi, China
| | - Junlin Liu
- The Orthopaedic Trauma, Ganzhou People's Hospital, Ganzhou, Jiangxi, China
| | - Hong Chen
- The Orthopaedic Trauma, Ganzhou People's Hospital, Ganzhou, Jiangxi, China
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2
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Hendrickx G, Boudin E, Mateiu L, Yorgan TA, Steenackers E, Kneissel M, Kramer I, Mortier G, Schinke T, Van Hul W. An Additional Lrp4 High Bone Mass Mutation Mitigates the Sost-Knockout Phenotype in Mice by Increasing Bone Remodeling. Calcif Tissue Int 2024; 114:171-181. [PMID: 38051321 DOI: 10.1007/s00223-023-01158-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 10/31/2023] [Indexed: 12/07/2023]
Abstract
Pathogenic variants disrupting the binding between sclerostin (encoded by SOST) and its receptor LRP4 have previously been described to cause sclerosteosis, a rare high bone mass disorder. The sclerostin-LRP4 complex inhibits canonical WNT signaling, a key pathway regulating osteoblastic bone formation and a promising therapeutic target for common bone disorders, such as osteoporosis. In the current study, we crossed mice deficient for Sost (Sost-/-) with our p.Arg1170Gln Lrp4 knock-in (Lrp4KI/KI) mouse model to create double mutant Sost-/-;Lrp4KI/KI mice. We compared the phenotype of Sost-/- mice with that of Sost-/-;Lrp4KI/KI mice, to investigate a possible synergistic effect of the disease-causing p.Arg1170Trp variant in Lrp4 on Sost deficiency. Interestingly, presence of Lrp4KI alleles partially mitigated the Sost-/- phenotype. Cellular and dynamic histomorphometry did not reveal mechanistic insights into the observed phenotypic differences. We therefore determined the molecular effect of the Lrp4KI allele by performing bulk RNA sequencing on Lrp4KI/KI primary osteoblasts. Unexpectedly, mostly genes related to bone resorption or remodeling (Acp5, Rankl, Mmp9) were upregulated in Lrp4KI/KI primary osteoblasts. Verification of these markers in Lrp4KI/KI, Sost-/- and Sost-/-;Lrp4KI/KI mice revealed that sclerostin deficiency counteracts this Lrp4KI/KI effect in Sost-/-;Lrp4KI/KI mice. We therefore hypothesize that models with two inactivating Lrp4KI alleles rather activate bone remodeling, with a net gain in bone mass, whereas sclerostin deficiency has more robust anabolic effects on bone formation. Moreover, these effects of sclerostin and Lrp4 are stronger in female mice, contributing to a more severe phenotype than in males and more detectable phenotypic differences among different genotypes.
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Affiliation(s)
- Gretl Hendrickx
- Centre for Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium
- Department of Human Genetics, KU Leuven, Louvain, Belgium
| | - Eveline Boudin
- Centre for Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium
| | - Ligia Mateiu
- Centre for Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium
| | - Timur A Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ellen Steenackers
- Centre for Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium
| | - Michaela Kneissel
- Diseases of Aging and Regenerative Medicine, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Ina Kramer
- Diseases of Aging and Regenerative Medicine, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Geert Mortier
- Centre for Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium
- Department of Human Genetics, KU Leuven, Louvain, Belgium
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Wim Van Hul
- Centre for Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium.
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Wei F, Tuong ZK, Omer M, Ngo C, Asiatico J, Kinzel M, Pugazhendhi AS, Khaled AR, Ghosh R, Coathup M. A novel multifunctional radioprotective strategy using P7C3 as a countermeasure against ionizing radiation-induced bone loss. Bone Res 2023; 11:34. [PMID: 37385982 DOI: 10.1038/s41413-023-00273-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/16/2023] [Accepted: 05/28/2023] [Indexed: 07/01/2023] Open
Abstract
Radiotherapy is a critical component of cancer care but can cause osteoporosis and pathological insufficiency fractures in surrounding and otherwise healthy bone. Presently, no effective countermeasure exists, and ionizing radiation-induced bone damage continues to be a substantial source of pain and morbidity. The purpose of this study was to investigate a small molecule aminopropyl carbazole named P7C3 as a novel radioprotective strategy. Our studies revealed that P7C3 repressed ionizing radiation (IR)-induced osteoclastic activity, inhibited adipogenesis, and promoted osteoblastogenesis and mineral deposition in vitro. We also demonstrated that rodents exposed to clinically equivalent hypofractionated levels of IR in vivo develop weakened, osteoporotic bone. However, the administration of P7C3 significantly inhibited osteoclastic activity, lipid formation and bone marrow adiposity and mitigated tissue loss such that bone maintained its area, architecture, and mechanical strength. Our findings revealed significant enhancement of cellular macromolecule metabolic processes, myeloid cell differentiation, and the proteins LRP-4, TAGLN, ILK, and Tollip, with downregulation of GDF-3, SH2B1, and CD200. These proteins are key in favoring osteoblast over adipogenic progenitor differentiation, cell matrix interactions, and shape and motility, facilitating inflammatory resolution, and suppressing osteoclastogenesis, potentially via Wnt/β-catenin signaling. A concern was whether P7C3 afforded similar protection to cancer cells. Preliminarily, and remarkably, at the same protective P7C3 dose, a significant reduction in triple-negative breast cancer and osteosarcoma cell metabolic activity was found in vitro. Together, these results indicate that P7C3 is a previously undiscovered key regulator of adipo-osteogenic progenitor lineage commitment and may serve as a novel multifunctional therapeutic strategy, leaving IR an effective clinical tool while diminishing the risk of adverse post-IR complications. Our data uncover a new approach for the prevention of radiation-induced bone damage, and further work is needed to investigate its ability to selectively drive cancer cell death.
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Affiliation(s)
- Fei Wei
- Biionix Cluster, and Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Zewen Kelvin Tuong
- Molecular Immunity Unit, Department of Medicine, University of Cambridge, Cambridge, UK
- Cellular Genetics, Wellcome Sanger Institute, Hinxton, UK
| | - Mahmoud Omer
- Biionix Cluster, and Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Christopher Ngo
- Biionix Cluster, and Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Jackson Asiatico
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, USA
| | - Michael Kinzel
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, USA
| | - Abinaya Sindu Pugazhendhi
- Biionix Cluster, and Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Annette R Khaled
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA
| | - Ranajay Ghosh
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL, USA
| | - Melanie Coathup
- Biionix Cluster, and Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL, USA.
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Wu Z, Yang KG, Lam TP, Cheng JCY, Zhu Z, Lee WYW. Genetic insight into the putative causal proteins and druggable targets of osteoporosis: a large-scale proteome-wide mendelian randomization study. Front Genet 2023; 14:1161817. [PMID: 37448626 PMCID: PMC10336211 DOI: 10.3389/fgene.2023.1161817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/12/2023] [Indexed: 07/15/2023] Open
Abstract
Background: Osteoporosis is a major causative factor of the global burden of disease and disability, characterized by low bone mineral density (BMD) and high risks of fracture. We aimed to identify putative causal proteins and druggable targets of osteoporosis. Methods: This study utilized the largest GWAS summary statistics on plasma proteins and estimated heel BMD (eBMD) to identify causal proteins of osteoporosis by mendelian randomization (MR) analysis. Different GWAS datasets were used to validate the results. Multiple sensitivity analyses were conducted to evaluate the robustness of primary MR findings. We have also performed an enrichment analysis for the identified causal proteins and evaluated their druggability. Results: After Bonferroni correction, 67 proteins were identified to be causally associated with estimated BMD (eBMD) (p < 4 × 10-5). We further replicated 38 of the 67 proteins to be associated with total body BMD, lumbar spine BMD, femoral neck BMD as well as fractures, such as RSPO3, IDUA, SMOC2, and LRP4. The findings were supported by sensitivity analyses. Enrichment analysis identified multiple Gene Ontology items, including collagen-containing extracellular matrix (GO:0062023, p = 1.6 × 10-10), collagen binding (GO:0005518, p = 8.6 × 10-5), and extracellular matrix structural constituent (GO:0005201, p = 2.7 × 10-5). Conclusion: The study identified novel putative causal proteins for osteoporosis which may serve as potential early screening biomarkers and druggable targets. Furthermore, the role of plasma proteins involved in collagen binding and extracellular matrix in the development of osteoporosis was highlighted. Further studies are warranted to validate our findings and investigate the underlying mechanism.
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Affiliation(s)
- Zhichong Wu
- Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
- Musculoskeletal Research Laboratory, SH Ho Scoliosis Research Laboratory, Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Kenneth Guangpu Yang
- Musculoskeletal Research Laboratory, SH Ho Scoliosis Research Laboratory, Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Prince of Wales Hospital, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Center for Neuromusculoskeletal Restorative Medicine, CUHK InnoHK Centres, Shatin, Hong Kong SAR, China
- Key Laboratory for Regenerative Medicine, School of Biomedical Sciences, Faculty of Medicine, Ministry of Education, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Tsz-Ping Lam
- Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Jack Chun Yiu Cheng
- Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Zezhang Zhu
- Division of Spine Surgery, Department of Orthopedic Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
- Musculoskeletal Research Laboratory, SH Ho Scoliosis Research Laboratory, Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Wayne Yuk-Wai Lee
- Musculoskeletal Research Laboratory, SH Ho Scoliosis Research Laboratory, Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Joint Scoliosis Research Centre of the Chinese University of Hong Kong and Nanjing University, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Prince of Wales Hospital, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Center for Neuromusculoskeletal Restorative Medicine, CUHK InnoHK Centres, Shatin, Hong Kong SAR, China
- Key Laboratory for Regenerative Medicine, School of Biomedical Sciences, Faculty of Medicine, Ministry of Education, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
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Choi RB, Hoggatt AM, Horan DJ, Rogers EZ, Loots GG, Robling AG. Sostdc1 Suppression in the Absence of Sclerostin Potentiates Anabolic Action of Cortical Bone in Mice. J Bone Miner Res 2023; 38:765-774. [PMID: 36891756 PMCID: PMC10830127 DOI: 10.1002/jbmr.4798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 02/18/2023] [Accepted: 03/02/2023] [Indexed: 03/10/2023]
Abstract
The development of Wnt-based osteoanabolic agents has progressed rapidly in recent years, given the potent effects of Wnt modulation on bone homeostasis. Simultaneous pharmacologic inhibition of the Wnt antagonists sclerostin and Dkk1 can be optimized to create potentiated effects in the cancellous bone compartment. We looked for other candidates that might be co-inhibited along with sclerostin to potentiate the effects in the cortical compartment. Sostdc1 (Wise), like sclerostin and Dkk1, also binds and inhibits Lrp5/6 coreceptors to impair canonical Wnt signaling, but Sostdc1 has greater effects in the cortical bone. To test this concept, we deleted Sostdc1 and Sost from mice and measured the skeletal effects in cortical and cancellous compartments individually. Sost deletion alone produced high bone mass in all compartments, whereas Sostdc1 deletion alone had no measurable effects on either envelope. Mice with codeletion of Sostdc1 and Sost had high bone mass and increased cortical properties (bone mass, formation rates, mechanical properties), but only among males. Combined administration of sclerostin antibody and Sostdc1 antibody in wild-type female mice produced potentiation of cortical bone gain despite no effect of Sostdc1 antibody alone. In conclusion, Sostdc1 inhibition/deletion can work in concert with sclerostin deficiency to improve cortical bone properties. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Roy B. Choi
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - April M. Hoggatt
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel J. Horan
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Emily Z. Rogers
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gabriela G. Loots
- Department of Orthopaedic Surgery, School of Medicine, UC Davis Health, Sacramento, CA, USA
| | - Alexander G. Robling
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
- Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, IN, USA
- Department of Biomedical Engineering, Indiana University–Purdue University at Indianapolis, Indianapolis, IN, USA
- Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA
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6
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Progress of Wnt Signaling Pathway in Osteoporosis. Biomolecules 2023; 13:biom13030483. [PMID: 36979418 PMCID: PMC10046187 DOI: 10.3390/biom13030483] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
Osteoporosis, one of the serious health diseases, involves bone mass loss, bone density diminishing, and degeneration of bone microstructure, which is accompanied by a tendency toward bone fragility and a predisposition to fracture. More than 200 million people worldwide suffer from osteoporosis, and the cost of treating osteoporotic fractures is expected to reach at least $25 billion by 2025. The generation and development of osteoporosis are regulated by genetic factors and regulatory factors such as TGF-β, BMP, and FGF through multiple pathways, including the Wnt signaling pathway, the Notch signaling pathway, and the MAPK signaling pathway. Among them, the Wnt signaling pathway is one of the most important pathways. It is not only involved in bone development and metabolism but also in the differentiation and proliferation of chondrocytes, mesenchymal stem cells, osteoclasts, and osteoblasts. Dkk-1 and SOST are Wnt inhibitory proteins that can inhibit the activation of the canonical Wnt signaling pathway and block the proliferation and differentiation of osteoblasts. Therefore, they may serve as potential targets for the treatment of osteoporosis. In this review, we analyzed the mechanisms of Wnt proteins, β-catenin, and signaling molecules in the process of signal transduction and summarized the relationship between the Wnt signaling pathway and bone-related cells. We hope to attract attention to the role of the Wnt signaling pathway in osteoporosis and offer new perspectives and approaches to making a diagnosis and giving treatment for osteoporosis.
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7
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Geng S, Paul F, Kowalczyk I, Raimundo S, Sporbert A, Mamo TM, Hammes A. Balancing WNT signalling in early forebrain development: The role of LRP4 as a modulator of LRP6 function. Front Cell Dev Biol 2023; 11:1173688. [PMID: 37091972 PMCID: PMC10119419 DOI: 10.3389/fcell.2023.1173688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/28/2023] [Indexed: 04/25/2023] Open
Abstract
The specification of the forebrain relies on the precise regulation of WNT/ß-catenin signalling to support neuronal progenitor cell expansion, patterning, and morphogenesis. Imbalances in WNT signalling activity in the early neuroepithelium lead to congenital disorders, such as neural tube defects (NTDs). LDL receptor-related protein (LRP) family members, including the well-studied receptors LRP5 and LRP6, play critical roles in modulating WNT signalling capacity through tightly regulated interactions with their co-receptor Frizzled, WNT ligands, inhibitors and intracellular WNT pathway components. However, little is known about the function of LRP4 as a potential modulator of WNT signalling in the central nervous system. In this study, we investigated the role of LRP4 in the regulation of WNT signalling during early mouse forebrain development. Our results demonstrate that LRP4 can modulate LRP5- and LRP6-mediated WNT signalling in the developing forebrain prior to the onset of neurogenesis at embryonic stage 9.5 and is therefore essential for accurate neural tube morphogenesis. Specifically, LRP4 functions as a genetic modifier for impaired mitotic activity and forebrain hypoplasia, but not for NTDs in LRP6-deficient mutants. In vivo and in vitro data provide evidence that LRP4 is a key player in fine-tuning WNT signalling capacity and mitotic activity of mouse neuronal progenitors and of human retinal pigment epithelial (hTERT RPE-1) cells. Our data demonstrate the crucial roles of LRP4 and LRP6 in regulating WNT signalling and forebrain development and highlight the need to consider the interaction between different signalling pathways to understand the underlying mechanisms of disease. The findings have significant implications for our mechanistic understanding of how LRPs participate in controlling WNT signalling.
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Affiliation(s)
- Shuang Geng
- Neuroscience, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Institute for Biology, Free University of Berlin, Berlin, Germany
| | - Fabian Paul
- Neuroscience, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Institute for Biology, Free University of Berlin, Berlin, Germany
| | - Izabela Kowalczyk
- Neuroscience, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- Institute for Biology, Free University of Berlin, Berlin, Germany
| | - Sandra Raimundo
- Advanced Light Microscopy Technology Platform, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Anje Sporbert
- Advanced Light Microscopy Technology Platform, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Tamrat Meshka Mamo
- Neuroscience, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- *Correspondence: Tamrat Meshka Mamo, ; Annette Hammes,
| | - Annette Hammes
- Neuroscience, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
- *Correspondence: Tamrat Meshka Mamo, ; Annette Hammes,
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8
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Iwamoto R, Koide M, Udagawa N, Kobayashi Y. Positive and Negative Regulators of Sclerostin Expression. Int J Mol Sci 2022; 23:ijms23094895. [PMID: 35563281 PMCID: PMC9102037 DOI: 10.3390/ijms23094895] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 04/27/2022] [Accepted: 04/27/2022] [Indexed: 02/04/2023] Open
Abstract
Sclerostin is secreted from osteocytes, binds to the Wnt co-receptor Lrp5/6, and affects the interaction between Wnt ligands and Lrp5/6, which inhibits Wnt/β-catenin signals and suppresses bone formation. Sclerostin plays an important role in the preservation of bone mass by functioning as a negative regulator of bone formation. A sclerostin deficiency causes sclerosteosis, which is characterized by an excess bone mass with enhanced bone formation in humans and mice. The expression of sclerostin is positively and negatively regulated by many factors, which also govern bone metabolism. Positive and negative regulators of sclerostin expression and their effects are introduced and discussed herein based on recent and previous findings, including our research.
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Affiliation(s)
- Rina Iwamoto
- Division of Hard Tissue Research, Institute for Oral Science, Matsumoto Dental University, 1780 Gobara Hiro-oka, Shiojiri 399-0781, Nagano, Japan; (R.I.); (M.K.)
| | - Masanori Koide
- Division of Hard Tissue Research, Institute for Oral Science, Matsumoto Dental University, 1780 Gobara Hiro-oka, Shiojiri 399-0781, Nagano, Japan; (R.I.); (M.K.)
| | - Nobuyuki Udagawa
- Department of Biochemistry, Matsumoto Dental University, 1780 Gobara Hiro-oka, Shiojiri 399-0781, Nagano, Japan;
| | - Yasuhiro Kobayashi
- Division of Hard Tissue Research, Institute for Oral Science, Matsumoto Dental University, 1780 Gobara Hiro-oka, Shiojiri 399-0781, Nagano, Japan; (R.I.); (M.K.)
- Correspondence: ; Tel.: +81-263-51-2238
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9
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Katchkovsky S, Chatterjee B, Abramovitch-Dahan CV, Papo N, Levaot N. Competitive blocking of LRP4-sclerostin binding interface strongly promotes bone anabolic functions. Cell Mol Life Sci 2022; 79:113. [PMID: 35099616 PMCID: PMC11073160 DOI: 10.1007/s00018-022-04127-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 12/16/2021] [Accepted: 01/03/2022] [Indexed: 01/07/2023]
Abstract
Induction of bone formation by Wnt ligands is inhibited when sclerostin (Scl), an osteocyte-produced antagonist, binds to its receptors, the low-density lipoprotein receptor-related proteins 5 or 6 (LRP5/6). Recently, it was shown that enhanced inhibition is achieved by Scl binding to the co-receptor LRP4. However, it is not clear if the binding of Scl to LRP4 facilitates Scl binding to LRP5/6 or inhibits the Wnt pathway in an LRP5/6-independent manner. Here, using the yeast display system, we demonstrate that Scl exhibits a stronger binding affinity for LRP4 than for LRP6. Moreover, we found stronger Scl binding to LRP6 in the presence of LRP4. We further show that a Scl mutant (SclN93A), which tightly binds LRP4 but not LRP6, does not inhibit the Wnt pathway on its own. We demonstrate that SclN93A competes with Scl for a common binding site on LRP4 and antagonizes Scl inhibition of the Wnt signaling pathway in osteoblasts in vitro. Finally, we demonstrate that 2 weeks of bi-weekly subcutaneous injections of SclN93A fused to the fragment crystallizable (Fc) domain of immunoglobulin (SclN93AFc), which retains the antagonistic activity of the mutant, significantly increases bone formation rate and enhances trabecular volumetric bone fraction, trabecular number, and bone length in developing mice. Our data show that LRP4 serves as an anchor that facilitates Scl-LRP6 binding and that inhibition of the Wnt pathway by Scl depends on its prior binding to LRP4. We further provide evidence that compounds that inhibit Scl-LRP4 interactions offer a potential strategy to promote anabolic bone functions.
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Affiliation(s)
- Svetlana Katchkovsky
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel
| | - Biplab Chatterjee
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel
| | - Chen-Viki Abramovitch-Dahan
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel
| | - Niv Papo
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering and the National Institute of Biotechnology in the Negev, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel.
| | - Noam Levaot
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel.
- Regenerative Medicine and Stem Cell Research Center, Ben-Gurion University of the Negev, 8410501, Beer-Sheva, Israel.
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10
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Martínez-Gil N, Ugartondo N, Grinberg D, Balcells S. Wnt Pathway Extracellular Components and Their Essential Roles in Bone Homeostasis. Genes (Basel) 2022; 13:genes13010138. [PMID: 35052478 PMCID: PMC8775112 DOI: 10.3390/genes13010138] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 12/11/2022] Open
Abstract
The Wnt pathway is involved in several processes essential for bone development and homeostasis. For proper functioning, the Wnt pathway is tightly regulated by numerous extracellular elements that act by both activating and inhibiting the pathway at different moments. This review aims to describe, summarize and update the findings regarding the extracellular modulators of the Wnt pathway, including co-receptors, ligands and inhibitors, in relation to bone homeostasis, with an emphasis on the animal models generated, the diseases associated with each gene and the bone processes in which each member is involved. The precise knowledge of all these elements will help us to identify possible targets that can be used as a therapeutic target for the treatment of bone diseases such as osteoporosis.
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Huybrechts Y, Boudin E, Hendrickx G, Steenackers E, Hamdy N, Mortier G, Martínez Díaz-Guerra G, Bracamonte MS, Appelman-Dijkstra NM, Van Hul W. Identification of Compound Heterozygous Variants in LRP4 Demonstrates That a Pathogenic Variant outside the Third β-Propeller Domain Can Cause Sclerosteosis. Genes (Basel) 2021; 13:genes13010080. [PMID: 35052419 PMCID: PMC8774882 DOI: 10.3390/genes13010080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/22/2021] [Accepted: 12/22/2021] [Indexed: 11/16/2022] Open
Abstract
Sclerosteosis is a high bone mass disorder, caused by pathogenic variants in the genes encoding sclerostin or LRP4. Both proteins form a complex that strongly inhibits canonical WNT signaling activity, a pathway of major importance in bone formation. So far, all reported disease-causing variants are located in the third β-propeller domain of LRP4, which is essential for the interaction with sclerostin. Here, we report the identification of two compound heterozygous variants, a known p.Arg1170Gln and a novel p.Arg632His variant, in a patient with a sclerosteosis phenotype. Interestingly, the novel variant is located in the first β-propeller domain, which is known to be indispensable for the interaction with agrin. However, using luciferase reporter assays, we demonstrated that both the p.Arg1170Gln and the p.Arg632His variant in LRP4 reduced the inhibitory capacity of sclerostin on canonical WNT signaling activity. In conclusion, this study is the first to demonstrate that a pathogenic variant in the first β-propeller domain of LRP4 can contribute to the development of sclerosteosis, which broadens the mutational spectrum of the disorder.
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Affiliation(s)
- Yentl Huybrechts
- Center of Medical Genetics, University of Antwerp and University Hospital Antwerp, 2650 Antwerp, Belgium; (Y.H.); (E.B.); (G.H.); (E.S.); (G.M.)
| | - Eveline Boudin
- Center of Medical Genetics, University of Antwerp and University Hospital Antwerp, 2650 Antwerp, Belgium; (Y.H.); (E.B.); (G.H.); (E.S.); (G.M.)
| | - Gretl Hendrickx
- Center of Medical Genetics, University of Antwerp and University Hospital Antwerp, 2650 Antwerp, Belgium; (Y.H.); (E.B.); (G.H.); (E.S.); (G.M.)
| | - Ellen Steenackers
- Center of Medical Genetics, University of Antwerp and University Hospital Antwerp, 2650 Antwerp, Belgium; (Y.H.); (E.B.); (G.H.); (E.S.); (G.M.)
| | - Neveen Hamdy
- Department of Internal Medicine, Division Endocrinology, Leiden University Medical Center, 2332 ZA Leiden, The Netherlands; (N.H.); (N.M.A.-D.)
| | - Geert Mortier
- Center of Medical Genetics, University of Antwerp and University Hospital Antwerp, 2650 Antwerp, Belgium; (Y.H.); (E.B.); (G.H.); (E.S.); (G.M.)
| | | | - Milagros Sierra Bracamonte
- Endocrinology and Nutrition Resident, 12 de Octubre University Hospital, 28041 Madrid, Spain; (G.M.D.-G.); (M.S.B.)
| | - Natasha M. Appelman-Dijkstra
- Department of Internal Medicine, Division Endocrinology, Leiden University Medical Center, 2332 ZA Leiden, The Netherlands; (N.H.); (N.M.A.-D.)
| | - Wim Van Hul
- Center of Medical Genetics, University of Antwerp and University Hospital Antwerp, 2650 Antwerp, Belgium; (Y.H.); (E.B.); (G.H.); (E.S.); (G.M.)
- Correspondence: ; Tel.: +32-(0)3-275-97-61
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12
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Day RN, Day KH, Pavalko FM. Direct visualization by FRET-FLIM of a putative mechanosome complex involving Src, Pyk2 and MBD2 in living MLO-Y4 cells. PLoS One 2021; 16:e0261660. [PMID: 34941939 PMCID: PMC8699642 DOI: 10.1371/journal.pone.0261660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 12/08/2021] [Indexed: 01/12/2023] Open
Abstract
Earlier, we proposed the “mechanosome” concept as a testable model for understanding how mechanical stimuli detected by cell surface adhesion molecules are transmitted to modulate gene expression inside cells. Here, for the first time we document a putative mechanosome involving Src, Pyk2 and MBD2 in MLO-Y4 osteocytes with high spatial resolution using FRET-FLIM. Src-Pyk2 complexes were concentrated at the periphery of focal adhesions and the peri-nuclear region. Pyk2-MBD2 complexes were located primarily in the nucleus and peri-nuclear region. Lifetime measurements indicated that Src and MBD2 did not interact directly. Finally, mechanical stimulation by fluid flow induced apparent accumulation of Src-Pyk2 protein complexes in the peri-nuclear/nuclear region, consistent with the proposed behavior of a mechanosome in response to a mechanical stimulus.
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Affiliation(s)
- Richard N. Day
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Kathleen H. Day
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Fredrick M. Pavalko
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail:
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13
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Choi RB, Robling AG. The Wnt pathway: An important control mechanism in bone's response to mechanical loading. Bone 2021; 153:116087. [PMID: 34271473 PMCID: PMC8478810 DOI: 10.1016/j.bone.2021.116087] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/01/2021] [Accepted: 06/21/2021] [Indexed: 10/25/2022]
Abstract
The conversion of mechanical energy into biochemical changes within living cells is process known as mechanotransduction. Bone is a quintessential tissue for studying the molecular mechanisms of mechanotransduction, as the skeleton's mechanical competence is crucial for vertebrate movement. Bone cell mechanotransduction is facilitated by a number of cell biological pathways, one of the most prominent of which is the Wnt signaling cascade. The Wnt co-receptor Lrp5 has been identified as a crucial protein for mechanical signaling in bone, and modifiers of Lrp5 activity play important roles in mediating signaling efficiency through Lrp5, including sclerostin, Dkk1, and the co-receptor Lrp4. Mechanical regulation of sclerostin is mediated by certain members of the Hdac family. Other mechanisms that influence Wnt signaling-some of which are mechanoresponsive-are coming to light, including R-spondins and their role in organizing the Rnf43/Znrf3 and Lgr4/5/6 complex that liberates Lrp5. While the identity of the key Wnt proteins involved in bone cell mechanical signaling are elusive, the likely pool of key players is narrowing. Identification of Wnt-based molecular targets that can be modulated pharmacologically to make mechanical stimulation (e.g., exercise) more beneficial is an emerging approach to improving skeletal integrity and reducing fracture risk.
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Affiliation(s)
- Roy B Choi
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Alexander G Robling
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, USA; Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, IN, USA; Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA.
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14
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Choi RB, Bullock WA, Hoggatt AM, Horan DJ, Pemberton EZ, Hong JM, Zhang X, He X, Robling AG. Notum Deletion From Late-Stage Skeletal Cells Increases Cortical Bone Formation and Potentiates Skeletal Effects of Sclerostin Inhibition. J Bone Miner Res 2021; 36:2413-2425. [PMID: 34223673 PMCID: PMC8688238 DOI: 10.1002/jbmr.4411] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/17/2021] [Accepted: 05/29/2021] [Indexed: 12/20/2022]
Abstract
Wnt signaling plays a vital role in the cell biology of skeletal patterning, differentiation, and maintenance. Notum is a secreted member of the α/β-hydrolase superfamily that hydrolyzes the palmitoleoylate modification on Wnt proteins, thereby disrupting Wnt signaling. As a secreted inhibitor of Wnt, Notum presents an attractive molecular target for improving skeletal health. To determine the cell type of action for Notum's effect on the skeleton, we generated mice with Notum deficiency globally (Notum-/- ) and selectively (Notumf/f ) in limb bud mesenchyme (Prx1-Cre) and late osteoblasts/osteocytes (Dmp1-Cre). Late-stage deletion induced increased cortical bone properties, similar to global mutants. Notum expression was enhanced in response to sclerostin inhibition, so dual inhibition (Notum/sclerostin) was also investigated using a combined genetic and pharmacologic approach. Co-suppression increased cortical properties beyond either factor alone. Notum suppressed Wnt signaling in cell reporter assays, but surprisingly also enhanced Shh signaling independent of effects on Wnt. Notum is an osteocyte-active suppressor of cortical bone formation that is likely involved in multiple signaling pathways important for bone homeostasis © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Roy B. Choi
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Whitney A. Bullock
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - April M. Hoggatt
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel J. Horan
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Emily Z. Pemberton
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jung Min Hong
- Division of Biomedical and Applied Sciences, Indiana University School of Dentistry, Indianapolis, IN, USA
| | - Xinjun Zhang
- F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Xi He
- F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Alexander G. Robling
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Biomedical Engineering, Indiana University–Purdue University at Indianapolis, Indianapolis, IN, USA
- Roudebush VA Medical Center, Indianapolis, IN USA
- Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA
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15
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Hui TK, Lai XS, Dong X, Jing H, Liu Z, Fei E, Chen WB, Wang S, Ren D, Zou S, Wu HT, Pan BX. Ablation of Lrp4 in Schwann Cells Promotes Peripheral Nerve Regeneration in Mice. BIOLOGY 2021; 10:biology10060452. [PMID: 34063992 PMCID: PMC8223976 DOI: 10.3390/biology10060452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/16/2021] [Accepted: 05/18/2021] [Indexed: 11/16/2022]
Abstract
Low-density lipoprotein receptor-related protein 4 (Lrp4) is a critical protein involved in the Agrin-Lrp4-MuSK signaling pathway that drives the clustering of acetylcholine receptors (AChRs) at the neuromuscular junction (NMJ). Many studies have shown that Lrp4 also functions in kidney development, bone formation, nervous system development, etc. However, whether Lrp4 participates in nerve regeneration in mammals remains unknown. Herein, we show that Lrp4 is expressed in SCs and that conditional knockout (cKO) of Lrp4 in SCs promotes peripheral nerve regeneration. In Lrp4 cKO mice, the demyelination of SCs was accelerated, and the proliferation of SCs was increased in the injured nerve. Furthermore, we identified that two myelination-related genes, Krox-20 and Mpz, were downregulated more dramatically in the cKO group than in the control group. Our results elucidate a novel role of Lrp4 in peripheral nerve regeneration and thereby provide a potential therapeutic target for peripheral nerve recovery.
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Affiliation(s)
- Tian-Kun Hui
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Xin-Sheng Lai
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Xia Dong
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
- School of Basic Medical Sciences, Nanchang University, Nanchang 330031, China
| | - Hongyang Jing
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Ziyang Liu
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Erkang Fei
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Wen-Bing Chen
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Shunqi Wang
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Dongyan Ren
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
| | - Suqi Zou
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
- Correspondence: (S.Z.); (H.-T.W.); (B.-X.P.)
| | - Hai-Tao Wu
- Department of Neurobiology, Beijing Institute of Basic Medical Sciences, Beijing 100850, China
- Key Laboratory of Neuroregeneration, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226019, China
- Correspondence: (S.Z.); (H.-T.W.); (B.-X.P.)
| | - Bing-Xing Pan
- School of Life Sciences, Nanchang University, Nanchang 330031, China; (T.-K.H.); (X.-S.L.); (H.J.); (Z.L.); (E.F.); (W.-B.C.); (S.W.); (D.R.)
- Institute of Life Science, Nanchang University, Nanchang 330031, China;
- Correspondence: (S.Z.); (H.-T.W.); (B.-X.P.)
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16
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Endocrine role of bone in the regulation of energy metabolism. Bone Res 2021; 9:25. [PMID: 34016950 PMCID: PMC8137703 DOI: 10.1038/s41413-021-00142-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 12/20/2020] [Accepted: 01/12/2021] [Indexed: 02/06/2023] Open
Abstract
Bone mainly functions as a supportive framework for the whole body and is the major regulator of calcium homeostasis and hematopoietic function. Recently, an increasing number of studies have characterized the significance of bone as an endocrine organ, suggesting that bone-derived factors regulate local bone metabolism and metabolic functions. In addition, these factors can regulate global energy homeostasis by altering insulin sensitivity, feeding behavior, and adipocyte commitment. These findings may provide a new pathological mechanism for related metabolic diseases or be used in the diagnosis, treatment, and prevention of metabolic diseases such as osteoporosis, obesity, and diabetes mellitus. In this review, we summarize the regulatory effect of bone and bone-derived factors on energy metabolism and discuss directions for future research.
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17
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Lim KE, Bullock WA, Horan DJ, Williams BO, Warman ML, Robling AG. Co-deletion of Lrp5 and Lrp6 in the skeleton severely diminishes bone gain from sclerostin antibody administration. Bone 2021; 143:115708. [PMID: 33164872 PMCID: PMC7770084 DOI: 10.1016/j.bone.2020.115708] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 10/01/2020] [Accepted: 10/20/2020] [Indexed: 01/14/2023]
Abstract
The cysteine knot protein sclerostin is an osteocyte-derived secreted inhibitor of the Wnt co-receptors LRP5 and LRP6. LRP5 plays a dominant role in bone homeostasis, but we previously reported that Sost/sclerostin suppression significantly increased osteogenesis regardless of Lrp5 presence or absence. Those observations suggested that the bone forming effects of sclerostin inhibition can occur through Lrp6 (when Lrp5 is suppressed), or through other yet undiscovered mechanisms independent of Lrp5/6. To distinguish between these two possibilities, we generated mice with compound deletion of Lrp5 and Lrp6 selectively in bone, and treated them with sclerostin monoclonal antibody (Scl-mAb). All mice were homozygous flox for both Lrp5 and Lrp6 (Lrp5f/f; Lrp6f/f), and varied only in whether or not they carried the Dmp1-Cre transgene. Positive (Cre+) and negative (Cre-) mice were injected with Scl-mAb or vehicle from 4.5 to 14 weeks of age. Vehicle-treated Cre+ mice exhibited significantly reduced skeletal properties compared to vehicle-treated Cre- mice, as assessed by DXA, μCT, pQCT, and histology, indicating that Lrp5/6 deletions were effective and efficient. Scl-mAb treatment improved nearly every bone-related parameter among Cre- mice, but the same treatment in Cre+ mice resulted in little to no improvement in skeletal properties. For the few endpoints where Cre+ mice responded to Scl-mAb, it is likely that antibody-induced promotion of Wnt signaling occurred in cell types earlier in the mesenchymal/osteoblast differentiation pathway than the Dmp1-expressing stage. This latter conclusion was supported by changes in some histomorphometric parameters. In conclusion, unlike with the deletion of Lrp5 alone, the bone-selective late-stage co-deletion of Lrp5 and Lrp6 significantly impairs or completely nullifies the osteogenic action of Scl-mAb, and highlights a major role for both Lrp5 and Lrp6 in the mechanism of action for the bone-building effects of sclerostin antibody.
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Affiliation(s)
- Kyung-Eun Lim
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Whitney A Bullock
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel J Horan
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Bart O Williams
- Program for Skeletal Disease and Tumor Microenvironment, Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Matthew L Warman
- Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA, USA
| | - Alexander G Robling
- Department of Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, USA; Richard L. Roudebush VA Medical Center, Indianapolis, IN, USA; Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA.
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18
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Abstract
The WNT/β-catenin signalling pathway is a rich and complex network of cellular proteins that orchestrates diverse short-range cell-to-cell communication in metazoans and is essential for both embryonic development and adult homeostasis. Due to its fundamental importance in controlling cell behaviour at multiple levels, its deregulation is associated with a wide range of diseases in humans and identification of drugs targeting the pathway has attracted strong interest in the pharmaceutical sector. Transduction of WNT signals across the plasma membrane of cells involves a staggering degree of complexity and variety with respect to ligand-receptor, receptor-receptor and receptor-co-receptor interactions (Niehrs, Nat Rev Mol Cell Biol 13:767-779, 2012). Although the low-density-lipoprotein-receptor-related-protein (LRP) family is best known for its role in binding and endocytosis of lipoproteins, specific members appear to have additional roles in cellular communication. Indeed, for WNT/β-catenin signalling one apparently universal requirement is the presence of either LRP5 or LRP6 in combination with one of the ten Frizzled (FZD) WNT receptors (FZD1-10). In the 20 years since their discovery as WNT/FZD co-receptors, research on the LRP family has contributed greatly to our understanding of WNT signalling and LRPs have emerged as central players in WNT/β-catenin signalling. LRP5/6 are highly similar and represent the least redundant class of WNT receptor that transduce WNT/β-catenin signalling from a wide range of different WNT and FZD subtypes. This apparent simplicity however belies the complex arrangement of binding sites in the extracellular domain (ECD) of LRP5/6, which regulate interaction not only with WNTs but also with several inhibitors of WNT signalling. This chapter provides a historical overview, chronologically charting this remarkable progress in the field during the last 20 years of research on LRPs and their role in WNT/-catenin signalling. A more focused overview of the structural, functional and mechanistic aspects of LRP biology is also provided, together with the implications this has for pharmacological targeting of this notoriously intractable pathway.
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Affiliation(s)
- Gary Davidson
- Institute of Biological and Chemical Systems-Functional Molecular Systems (IBSC-FMS), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany.
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19
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Al-Bari AA, Al Mamun A. Current advances in regulation of bone homeostasis. FASEB Bioadv 2020; 2:668-679. [PMID: 33205007 PMCID: PMC7655096 DOI: 10.1096/fba.2020-00058] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/18/2020] [Accepted: 08/21/2020] [Indexed: 02/06/2023] Open
Abstract
Bone homeostasis is securely controlled by the dynamic well‐balanced actions among osteoclasts, osteoblasts and osteocytes. Osteoclasts are large multinucleated cells that degrade bone matrix and involve in the bone remodelling in conjunction with other bone cells, osteoblasts and osteocytes, the completely matured form of osteoblasts. Disruption of this controlling balance among these cells or any disparity in bone remodelling caused by a higher rate of resorption by osteoclasts over construction of bone by osteoblasts results in a reduction of bone matrix including bone mineral density (BMD) and bone marrow cells (BMCs). The dominating effect of osteoclasts results in advanced risk of bone crack and joint destruction in several diseases including osteoporosis and rheumatoid arthritis (RA). However, the boosted osteoblastic activity produces osteosclerotic phenotype and weakened its action primes to osteomalacia or rickets. On the other hand, senescent osteocytes predominately progress the senescence associated secretory phenotype (SASP) and may contribute to age related bone loss. Here, we discuss an advanced level work on newly identified cellular mechanisms controlling the remodelling of bone and crosstalk among bone cells as these relate to the therapeutic targeting of the skeleton.
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Affiliation(s)
| | - Abdullah Al Mamun
- Department of Genetic Engineering and Biotechnology Shahjalal University of Science and Technology Sylhet Bangladesh
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