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Ravazzano L, Colaianni G, Tarakanova A, Xiao YB, Grano M, Libonati F. Multiscale and multidisciplinary analysis of aging processes in bone. NPJ AGING 2024; 10:28. [PMID: 38879533 PMCID: PMC11180112 DOI: 10.1038/s41514-024-00156-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 05/07/2024] [Indexed: 06/19/2024]
Abstract
The world population is increasingly aging, deeply affecting our society by challenging our healthcare systems and presenting an economic burden, thus turning the spotlight on aging-related diseases: exempli gratia, osteoporosis, a silent disease until you suddenly break a bone. The increase in bone fracture risk with age is generally associated with a loss of bone mass and an alteration in the skeletal architecture. However, such changes cannot fully explain increased fragility with age. To successfully tackle age-related bone diseases, it is paramount to comprehensively understand the fundamental mechanisms responsible for tissue degeneration. Aging mechanisms persist at multiple length scales within the complex hierarchical bone structure, raising the need for a multiscale and multidisciplinary approach to resolve them. This paper aims to provide an overarching analysis of aging processes in bone and to review the most prominent outcomes of bone aging. A systematic description of different length scales, highlighting the corresponding techniques adopted at each scale and motivating the need for combining diverse techniques, is provided to get a comprehensive description of the multi-physics phenomena involved.
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Affiliation(s)
- Linda Ravazzano
- Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Rubattino 81, Milano, 20134, Italy
| | - Graziana Colaianni
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University of Bari Aldo Moro, Piazza Giulio Cesare 11, Bari, 70124, Italy
| | - Anna Tarakanova
- School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, 06269, CT, USA
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, CT, 06269, Storrs, USA
| | - Yu-Bai Xiao
- School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut, 191 Auditorium Road, Unit 3139, Storrs, 06269, CT, USA
| | - Maria Grano
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University of Bari Aldo Moro, Piazza Giulio Cesare 11, Bari, 70124, Italy
| | - Flavia Libonati
- Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Rubattino 81, Milano, 20134, Italy.
- Department of Mechanical, Energy, Management and Transport Engineering - DIME, University of Genova, Via all'Opera Pia 15, Genova, 16145, Italy.
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Walowski CO, Herpich C, Enderle J, Braun W, Both M, Hasler M, Müller MJ, Norman K, Bosy-Westphal A. Determinants of bone mass in older adults with normal- and overweight derived from the crosstalk with muscle and adipose tissue. Sci Rep 2023; 13:5030. [PMID: 36977715 PMCID: PMC10050471 DOI: 10.1038/s41598-023-31642-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 03/15/2023] [Indexed: 03/30/2023] Open
Abstract
Lower bone mass in older adults may be mediated by the endocrine crosstalk between muscle, adipose tissue and bone. In 150 community-dwelling adults (59-86 years, BMI 17-37 kg/m2; 58.7% female), skeletal muscle mass index, adipose tissue and fat mass index (FMI) were determined. Levels of myokines, adipokines, osteokines, inflammation markers and insulin were measured as potential determinants of bone mineral content (BMC) and density (BMD). FMI was negatively associated with BMC and BMD after adjustment for mechanical loading effects of body weight (r-values between -0.37 and -0.71, all p < 0.05). Higher FMI was associated with higher leptin levels in both sexes, with higher hsCRP in women and with lower adiponectin levels in men. In addition to weight and FMI, sclerostin, osteocalcin, leptin × sex and adiponectin were independent predictors of BMC in a stepwise multiple regression analysis. Muscle mass, but not myokines, showed positive correlations with bone parameters that were weakened after adjusting for body weight (r-values between 0.27 and 0.58, all p < 0.01). Whereas the anabolic effect of muscle mass on bone in older adults may be partly explained by mechanical loading, the adverse effect of obesity on bone is possibly mediated by low-grade inflammation, higher leptin and lower adiponectin levels.
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Affiliation(s)
- Carina O Walowski
- Institute for Human Nutrition and Food Science, Christian-Albrechts-University, Düsternbrooker Weg 17, 24105, Kiel, Germany
| | - Catrin Herpich
- Institute of Nutritional Science, University of Potsdam, Potsdam, Germany
- Department of Geriatrics and Medical Gerontology, Charité Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Nutrition and Gerontology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany
| | - Janna Enderle
- Institute for Human Nutrition and Food Science, Christian-Albrechts-University, Düsternbrooker Weg 17, 24105, Kiel, Germany
| | - Wiebke Braun
- Institute for Human Nutrition and Food Science, Christian-Albrechts-University, Düsternbrooker Weg 17, 24105, Kiel, Germany
| | - Marcus Both
- Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Campus Kiel, Germany
| | - Mario Hasler
- Applied Statistics, Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University, Kiel, Germany
| | - Manfred J Müller
- Institute for Human Nutrition and Food Science, Christian-Albrechts-University, Düsternbrooker Weg 17, 24105, Kiel, Germany
| | - Kristina Norman
- Institute of Nutritional Science, University of Potsdam, Potsdam, Germany
- Department of Geriatrics and Medical Gerontology, Charité Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Nutrition and Gerontology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Anja Bosy-Westphal
- Institute for Human Nutrition and Food Science, Christian-Albrechts-University, Düsternbrooker Weg 17, 24105, Kiel, Germany.
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Yildirim G, Budell W, Berezovska O, Yagerman S, Maliath S, Mastrokostas P, Tommasini S, Dowd T. Lead induced differences in bone properties in osteocalcin +/+ and −/− female mice. Bone Rep 2023; 18:101672. [PMID: 37064000 PMCID: PMC10090701 DOI: 10.1016/j.bonr.2023.101672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 02/25/2023] [Accepted: 03/15/2023] [Indexed: 03/19/2023] Open
Abstract
Lead (Pb) toxicity is a major health problem and bone is the major reservoir. Lead is detrimental to bone, affects bone remodeling and is associated with elderly fractures. Osteocalcin (OC) affects bone remodeling, improves fracture resistance and decreases with age and in some diseases. The effect of lead in osteocalcin depleted bone is unknown and of interest. We compared bone mineral properties of control and Pb exposed (from 2 to 6 months) femora from female adult C57BL6 OC+/+ and OC-/- mice using Fourier Transform Infrared Imaging (FTIRI), Micro-computed tomography (uCT), bone biomechanical measurements and serum turnover markers (P1NP, CTX). Lead significantly increased turnover in OC+/+ and in OC-/- bones producing increased total volume, area and marrow area/total area with decreased BV/TV compared to controls. The increased turnover decreased mineral/matrix vs. Oc+/+ and increased mineral/matrix and crystallinity vs. OC-/-. PbOC-/- had increased bone formation, cross-sectional area (Imin) and decreased collagen maturity compared OC-/- and PbOC+/+. Imbalanced turnover in PbOC-/- confirmed the role of osteocalcin as a coupler of formation and resorption. Bone strength and stiffness were reduced in OC-/- and PbOC-/- due to reduced material properties vs. OC+/+ and PbOC+/+ respectively. The PbOC-/- bones had increased area to compensate for weaker material properties but were not proportionally stronger for increased size. However, at low lead levels osteocalcin plays the major role in bone strength suggesting increased fracture risk in low Pb2+ exposed elderly could be due to reduced osteocalcin as well. Years of low lead exposure or higher blood lead levels may have an additional effect on bone strength.
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Affiliation(s)
- G. Yildirim
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - W.C. Budell
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - O. Berezovska
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - S. Yagerman
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | - S.S. Maliath
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - P. Mastrokostas
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY, USA
| | - S. Tommasini
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA
| | - T.L. Dowd
- Department of Chemistry, Brooklyn College of the City University of New York, Brooklyn, NY, USA
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
- Corresponding author at: Department of Chemistry, Rm. 359 NE, Brooklyn College of the City University of New York, 2900 Bedford Ave., Brooklyn, NY 11210, USA.
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Wong L, McMahon LP. Crosstalk between bone and muscle in chronic kidney disease. Front Endocrinol (Lausanne) 2023; 14:1146868. [PMID: 37033253 PMCID: PMC10076741 DOI: 10.3389/fendo.2023.1146868] [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: 01/18/2023] [Accepted: 03/14/2023] [Indexed: 04/11/2023] Open
Abstract
With increasing life expectancy, the related disorders of bone loss, metabolic dysregulation and sarcopenia have become major health threats to the elderly. Each of these conditions is prevalent in patients with chronic kidney disease (CKD), particularly in more advanced stages. Our current understanding of the bone-muscle interaction is beyond mechanical coupling, where bone and muscle have been identified as interrelated secretory organs, and regulation of both bone and muscle metabolism occurs through osteokines and myokines via autocrine, paracrine and endocrine systems. This review appraises the current knowledge regarding biochemical crosstalk between bone and muscle, and considers recent progress related to the role of osteokines and myokines in CKD, including modulatory effects of physical exercise and potential therapeutic targets to improve musculoskeletal health in CKD patients.
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Affiliation(s)
- Limy Wong
- Department of Renal Medicine, Monash University Eastern Health Clinical School, Box Hill, VIC, Australia
- Department of Renal Medicine, Eastern Health, Box Hill, VIC, Australia
- *Correspondence: Limy Wong,
| | - Lawrence P. McMahon
- Department of Renal Medicine, Monash University Eastern Health Clinical School, Box Hill, VIC, Australia
- Department of Renal Medicine, Eastern Health, Box Hill, VIC, Australia
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Hue I, Capilla E, Rosell-Moll E, Balbuena-Pecino S, Goffette V, Gabillard JC, Navarro I. Recent advances in the crosstalk between adipose, muscle and bone tissues in fish. Front Endocrinol (Lausanne) 2023; 14:1155202. [PMID: 36998471 PMCID: PMC10043431 DOI: 10.3389/fendo.2023.1155202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 02/27/2023] [Indexed: 03/17/2023] Open
Abstract
Control of tissue metabolism and growth involves interactions between organs, tissues, and cell types, mediated by cytokines or direct communication through cellular exchanges. Indeed, over the past decades, many peptides produced by adipose tissue, skeletal muscle and bone named adipokines, myokines and osteokines respectively, have been identified in mammals playing key roles in organ/tissue development and function. Some of them are released into the circulation acting as classical hormones, but they can also act locally showing autocrine/paracrine effects. In recent years, some of these cytokines have been identified in fish models of biomedical or agronomic interest. In this review, we will present their state of the art focusing on local actions and inter-tissue effects. Adipokines reported in fish adipocytes include adiponectin and leptin among others. We will focus on their structure characteristics, gene expression, receptors, and effects, in the adipose tissue itself, mainly regulating cell differentiation and metabolism, but in muscle and bone as target tissues too. Moreover, lipid metabolites, named lipokines, can also act as signaling molecules regulating metabolic homeostasis. Regarding myokines, the best documented in fish are myostatin and the insulin-like growth factors. This review summarizes their characteristics at a molecular level, and describes both, autocrine effects and interactions with adipose tissue and bone. Nonetheless, our understanding of the functions and mechanisms of action of many of these cytokines is still largely incomplete in fish, especially concerning osteokines (i.e., osteocalcin), whose potential cross talking roles remain to be elucidated. Furthermore, by using selective breeding or genetic tools, the formation of a specific tissue can be altered, highlighting the consequences on other tissues, and allowing the identification of communication signals. The specific effects of identified cytokines validated through in vitro models or in vivo trials will be described. Moreover, future scientific fronts (i.e., exosomes) and tools (i.e., co-cultures, organoids) for a better understanding of inter-organ crosstalk in fish will also be presented. As a final consideration, further identification of molecules involved in inter-tissue communication will open new avenues of knowledge in the control of fish homeostasis, as well as possible strategies to be applied in aquaculture or biomedicine.
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Affiliation(s)
- Isabelle Hue
- Laboratory of Fish Physiology and Genomics, UR1037, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Rennes, France
| | - Encarnación Capilla
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Enrique Rosell-Moll
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Sara Balbuena-Pecino
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Valentine Goffette
- Laboratory of Fish Physiology and Genomics, UR1037, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Rennes, France
| | - Jean-Charles Gabillard
- Laboratory of Fish Physiology and Genomics, UR1037, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Rennes, France
| | - Isabel Navarro
- Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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Carvalho MS, Cabral JMS, da Silva CL, Vashishth D. Bone Matrix Non-Collagenous Proteins in Tissue Engineering: Creating New Bone by Mimicking the Extracellular Matrix. Polymers (Basel) 2021; 13:polym13071095. [PMID: 33808184 PMCID: PMC8036283 DOI: 10.3390/polym13071095] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/18/2021] [Accepted: 03/20/2021] [Indexed: 02/06/2023] Open
Abstract
Engineering biomaterials that mimic the extracellular matrix (ECM) of bone is of significant importance since most of the outstanding properties of the bone are due to matrix constitution. Bone ECM is composed of a mineral part comprising hydroxyapatite and of an organic part of primarily collagen with the rest consisting on non-collagenous proteins. Collagen has already been described as critical for bone tissue regeneration; however, little is known about the potential effect of non-collagenous proteins on osteogenic differentiation, even though these proteins were identified some decades ago. Aiming to engineer new bone tissue, peptide-incorporated biomimetic materials have been developed, presenting improved biomaterial performance. These promising results led to ongoing research focused on incorporating non-collagenous proteins from bone matrix to enhance the properties of the scaffolds namely in what concerns cell migration, proliferation, and differentiation, with the ultimate goal of designing novel strategies that mimic the native bone ECM for bone tissue engineering applications. Overall, this review will provide an overview of the several non-collagenous proteins present in bone ECM, their functionality and their recent applications in the bone tissue (including dental) engineering field.
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Affiliation(s)
- Marta S. Carvalho
- Center for Biotechnology and Interdisciplinary Studies, Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
- Department of Bioengineering and iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (J.M.S.C.); (C.L.d.S.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Correspondence: (M.S.C.); (D.V.)
| | - Joaquim M. S. Cabral
- Department of Bioengineering and iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (J.M.S.C.); (C.L.d.S.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Cláudia L. da Silva
- Department of Bioengineering and iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (J.M.S.C.); (C.L.d.S.)
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Deepak Vashishth
- Center for Biotechnology and Interdisciplinary Studies, Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
- Correspondence: (M.S.C.); (D.V.)
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He C, He W, Hou J, Chen K, Huang M, Yang M, Luo X, Li C. Bone and Muscle Crosstalk in Aging. Front Cell Dev Biol 2020; 8:585644. [PMID: 33363144 PMCID: PMC7758235 DOI: 10.3389/fcell.2020.585644] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/09/2020] [Indexed: 12/12/2022] Open
Abstract
Osteoporosis and sarcopenia are two age-related diseases that affect the quality of life in the elderly. Initially, they were thought to be two independent diseases; however, recently, increasing basic and clinical data suggest that skeletal muscle and bone are both spatially and metabolically connected. The term "osteosarcopenia" is used to define a condition of synergy of low bone mineral density with muscle atrophy and hypofunction. Bone and muscle cells secrete several factors, such as cytokines, myokines, and osteokines, into the circulation to influence the biological and pathological activities in local and distant organs and cells. Recent studies reveal that extracellular vesicles containing microRNAs derived from senescent skeletal muscle and bone cells can also be transported and aid in regulating bone-muscle crosstalk. In this review, we summarize the age-related changes in the secretome and extracellular vesicle-microRNAs secreted by the muscle and bone, and discuss their interactions between muscle and bone cells during aging.
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Affiliation(s)
- Chen He
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
| | - Wenzhen He
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
| | - Jing Hou
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
| | - Kaixuan Chen
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
| | - Mei Huang
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
| | - Mi Yang
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
| | - Xianghang Luo
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
- Key Laboratory of Organ Injury, Aging and Regenerative Medicine of Hunan Province, Changsha, China
| | - Changjun Li
- Department of Endocrinology, Endocrinology Research Center, Xiangya Hospital of Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital of Central South University, Changsha, China
- Key Laboratory of Organ Injury, Aging and Regenerative Medicine of Hunan Province, Changsha, China
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Schatz M, Saravanan S, d'Adesky ND, Bramlett H, Perez-Pinzon MA, Raval AP. Osteocalcin, ovarian senescence, and brain health. Front Neuroendocrinol 2020; 59:100861. [PMID: 32781196 DOI: 10.1016/j.yfrne.2020.100861] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/20/2020] [Accepted: 08/05/2020] [Indexed: 12/19/2022]
Abstract
Menopause, an inevitable event in a woman's life, significantly increases risk of bone resorption and diseases such as Alzheimer's, vascular dementia, cardiac arrest, and stroke. The sole role of bones, as traditionally regarded, is to provide structural support for skeletal muscles and allow for ambulation, however this concept is becoming quickly outdated. New literature has emerged that suggests the bone cell-derived hormone osteocalcin (OCN) plays a pivotal role in cognition. OCN levels are correlated with bone mass density and bone turnover, and thus are strongly influenced by the changes associated with menopause. The goal of the current review is to discuss potential gaps in our knowledge of OCN and cognition, discrepancies in methods of OCN quantification, and therapies to enhance circulating OCN. A discussion on implementing exercise or low frequency vibration interventions at the menopausal transition to reduce risk and severity of neurological diseases and associated cognitive decline is included.
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Affiliation(s)
- Marc Schatz
- Department of Orthopaedic Surgery, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Sharnikha Saravanan
- Peritz Scheinberg Cerebral Vascular Disease Research Laboratory, Department of Neurology, Miami, FL 33136, USA
| | - Nathan D d'Adesky
- Peritz Scheinberg Cerebral Vascular Disease Research Laboratory, Department of Neurology, Miami, FL 33136, USA
| | - Helen Bramlett
- Department of Neurological Surgery, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA; Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, FL 33136, USA
| | - Miguel A Perez-Pinzon
- Peritz Scheinberg Cerebral Vascular Disease Research Laboratory, Department of Neurology, Miami, FL 33136, USA
| | - Ami P Raval
- Peritz Scheinberg Cerebral Vascular Disease Research Laboratory, Department of Neurology, Miami, FL 33136, USA.
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Li J, Guo X, Li M, Xiao Y, Bao C. [Research progress in the mechanism of protein factors in regulating bone remodeling]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2019; 33:115-123. [PMID: 30644271 DOI: 10.7507/1002-1892.201808059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Objective To review the role and mechanism of protein factors in bone remodeling, and provides theoretical basis for further elucidating the pathogenesis and clinical treatment of bone-related diseases. Methods The relevant research results at home and abroad in recent years were extensively consulted, analyzed, and summarized. Results Bone remodeling is an important physiological process to maintain bone homeostasis. Protein, as an important stimulator in bone remodeling, regulates the balance between bone resorption and bone formation. Conclusion At present, the research on the mechanism of protein in bone remodeling is insufficient. Therefore, it is necessary to further study the specific time, process, and interaction network of protein in bone remodeling, and to confirm its mechanism in bone remodeling, so as to reveal and treat the pathogenesis of bone-related diseases.
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Affiliation(s)
- Ju Li
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China;National Clinical Research Center of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China
| | - Xiaodong Guo
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China;National Clinical Research Center of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China
| | - Mingzheng Li
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China;National Clinical Research Center of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China;Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu Sichuan, 610041, P.R.China
| | - Yu Xiao
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China;National Clinical Research Center of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041,
| | - Chongyun Bao
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu Sichuan, 610041, P.R.China;Department of Oral and Maxillofacial Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu Sichuan, 610041,
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10
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Carvalho MS, Cabral JM, da Silva CL, Vashishth D. Synergistic effect of extracellularly supplemented osteopontin and osteocalcin on stem cell proliferation, osteogenic differentiation, and angiogenic properties. J Cell Biochem 2018; 120:6555-6569. [PMID: 30362184 DOI: 10.1002/jcb.27948] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 10/02/2018] [Indexed: 12/17/2022]
Abstract
A high demand for functional bone grafts is being observed worldwide, especially due to the increased life expectancy. Osteoinductive components should be incorporated into functional bone grafts, accelerating cell recruitment, cell proliferation, angiogenesis, and new bone formation at a defect site. Noncollagenous bone matrix proteins, especially osteopontin (OPN) and osteocalcin (OC), have been reported to regulate some physiological process, such as cell migration and bone mineralization. However, the effects of OPN and OC on cell proliferation, osteogenic differentiation, mineralization, and angiogenesis are still undefined. Therefore, we assessed the exogenous effect of OPN and OC supplementation on human bone marrow mesenchymal stem/stromal cells (hBM MSC) proliferation and osteogenic differentiation. OPN dose-dependently increased the proliferation of hBM MSC, as well as improved the angiogenic properties of human umbilical vein endothelial cells (HUVEC) by increasing the capillary-like tube formation in vitro. On the other hand, OC enhanced the differentiation of hBM MSC into osteoblasts and demonstrated an increase in extracellular calcium levels and alkaline phosphatase activity, as well as higher messenger RNA levels of mature osteogenic markers osteopontin and osteocalcin. In vivo assessment of OC/OPN-enhanced scaffolds in a critical-sized defect rabbit long-bone model revealed no infection, while new bone was being formed. Taken together, these results suggest that OC and OPN stimulate bone regeneration by inducing stem cell proliferation, osteogenesis and by enhancing angiogenic properties. The synergistic effect of OC and OPN observed in this study can be applied as an attractive strategy for bone regeneration therapeutics by targeting different vital cellular processes.
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Affiliation(s)
- Marta S Carvalho
- Department of Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York.,Department of Bioengineering, iBB - Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Joaquim Ms Cabral
- Department of Bioengineering, iBB - Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,The Discoveries Centre for Regenerative and Precision Medicine, Lisbon Campus, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Cláudia L da Silva
- Department of Bioengineering, iBB - Institute of Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,The Discoveries Centre for Regenerative and Precision Medicine, Lisbon Campus, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Deepak Vashishth
- Department of Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
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Li J, Zhang H, Yang C, Li Y, Dai Z. An overview of osteocalcin progress. J Bone Miner Metab 2016; 34:367-79. [PMID: 26747614 DOI: 10.1007/s00774-015-0734-7] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/22/2015] [Indexed: 12/20/2022]
Abstract
An increasing amount of data indicate that osteocalcin is an endocrine hormone which regulates energy metabolism, male fertility and brain development. However, the detailed functions and mechanism of osteocalcin are not well understood and conflicting results have been obtained from researchers worldwide. In the present review, we summarize the progress of osteocalcin studies over the past 40 years, focusing on the structure of carboxylated and undercarboxylated osteocalcin, new functions and putative receptors, the role of osteocalcin in bone remodeling, specific expression and regulation in osteoblasts, and new indices for clinical studies. The complexity of osteocalcin in completely, uncompletely and non-carboxylated forms may account for the discrepancies in its tertiary structure and clinical results. Moreover, the extensive expression of osteocalcin and its putative receptor GPRC6A imply that there are new physiological functions and mechanisms of action of osteocalcin to be explored. New discoveries related to osteocalcin function will assist its potential clinical application and physiological theory, but comprehensive investigations are required.
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Affiliation(s)
- Jinqiao Li
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, P.O.Box 1053-23#, No. 26, Beijing Road, Haidian District, Beijing, 100094, China
| | - Hongyu Zhang
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, P.O.Box 1053-23#, No. 26, Beijing Road, Haidian District, Beijing, 100094, China
| | - Chao Yang
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, P.O.Box 1053-23#, No. 26, Beijing Road, Haidian District, Beijing, 100094, China
| | - Yinghui Li
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, P.O.Box 1053-23#, No. 26, Beijing Road, Haidian District, Beijing, 100094, China
| | - Zhongquan Dai
- China Astronaut Research and Training Center, State Key Lab of Space Medicine Fundamentals and Application, P.O.Box 1053-23#, No. 26, Beijing Road, Haidian District, Beijing, 100094, China.
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12
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Liu J, Yang J. Uncarboxylated osteocalcin inhibits high glucose-induced ROS production and stimulates osteoblastic differentiation by preventing the activation of PI3K/Akt in MC3T3-E1 cells. Int J Mol Med 2015; 37:173-81. [PMID: 26719856 DOI: 10.3892/ijmm.2015.2412] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 11/16/2015] [Indexed: 11/05/2022] Open
Abstract
Uncarboxylated osteocalcin, an osteoblast-derived protein, plays an important role in the regulation of glucose metabolism. It has previously been demonstrated that high glucose levels inhibit osteoblast proliferation and differentiation. However, the mechanisms through which uncarboxylated osteocalcin regulates osteoblast proliferation and differentiation under high glucose conditions remain unclear. Thus, in the present study, we aimed to examine the effects of uncarboxylated osteocalcin on the proliferation and differentiation of MC3T3-E1 cells under high glucose conditions. We demonstrated that high glucose levels induced the production of reactive oxygen species (ROS) in MC3T3-E1 cells, and this production was inhibited by treatment with uncarboxylated osteocalcin and N-acetyl-L-cysteine (NAC), a ROS scavenger. In addition, we found that uncarboxylated osteocalcin reduced high glucose‑induced oxidative stress and increased the mRNA expression of the osteogenic markers, runt-related transcription factor 2 (Runx2), osterix and osteocalcin, as well as the formation of mineralized nodules; it also inhibited adipogenic differentiation, as shown by a decrease in the mRNA expression of the adipogenic markers, peroxisome proliferator‑activated receptor γ (PPARγ), adipocyte fatty acid-binding protein (adipocyte protein 2; aP2) and fatty acid synthase (FAS), and reduced lipid drop accumulation. Furthermore, we found that uncarboxylated osteocalcin inhibited PI3K/Akt signaling which was induced by ROS and facilitated the osteogenic differentiation of MC3T3-E1 cells under high glucose conditions. Taken together and to the best of ou knowledge, our results demonstrate for the first time that uncarboxylated osteocalcin inhibits high glucose-induced ROS production and stimulates osteoblastic differentiation by inhibiting the activation of PI3K/Akt in MC3T3-E1 cells. Therefore, we suggest that uncarboxylated osteocalcin may be a potential therapeutic agent for diabetes-related osteoporosis.
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Affiliation(s)
- Jingli Liu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Jianhong Yang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, P.R. China
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Lombardi G, Perego S, Luzi L, Banfi G. A four-season molecule: osteocalcin. Updates in its physiological roles. Endocrine 2015; 48:394-404. [PMID: 25158976 DOI: 10.1007/s12020-014-0401-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/19/2014] [Indexed: 12/28/2022]
Abstract
Osteocalcin (OC) is the main non-collagenous hydroxyapatite-binding protein synthesized by osteoblasts, odontoblasts, and hypertrophic chondrocytes. It has a regulatory role in mineralization and it is considered a marker of bone cell metabolism. Recent findings evidenced new extra-skeletal roles for OC, depicting it as a real hormone. OC shares many functional features with the common hormones, such as tissue-specific expression, circadian rhythm, and synthesis as a pre-pro-molecule. However, it has some peculiar features making it a unique molecule: OC exists in different forms based on the degree of carboxylation. Indeed, OC has three glutamic acid residues, in position 17, 21, and 24, which are subject to γ-carboxylation, through the action of a vitamin K-dependent γ-glutamyl carboxytransferase. The degree of carboxylation, and thus the negative charge density, determines the affinity for the calcium ions deposited in the extracellular matrix of the bone. The modulation of the carboxylation could, thus, represent the mechanism by which the body controls the circulating levels, and hence the hormonal function, of OC. There are evidences linking OC, and the bone metabolism, with a series of endocrine (glucose metabolism, energy metabolism, fertility) physiological (muscle activity) and pathological functions (ectopic calcification). Aim of this review is to give a full overview of the physiological roles of OC by collecting the newest experimental findings on this intriguing molecule.
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Affiliation(s)
- Giovanni Lombardi
- Laboratory of Experimental Biochemistry & Molecular Biology, I.R.C.C.S. Istituto Ortopedico Galeazzi, Via R. Galeazzi 4, 20161, Milan, Italy,
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Xu H, Han X, Meng Y, Gao L, Guo Y, Jing Y, Bai D. Favorable effect of myofibroblasts on collagen synthesis and osteocalcin production in the periodontal ligament. Am J Orthod Dentofacial Orthop 2014; 145:469-79. [PMID: 24703285 DOI: 10.1016/j.ajodo.2013.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 12/01/2013] [Accepted: 12/01/2013] [Indexed: 02/05/2023]
Abstract
INTRODUCTION In this study, we aimed to explore the expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the periodontal ligament (PDL) under orthodontic loading, and to investigate the effect of myofibroblasts on collagen synthesis and osteocalcin production. METHODS The teeth in the right maxillae of the rats were orthodontically loaded while the contralateral teeth remained unloaded as controls. The total 30 rats were divided into 5 groups, with each group corresponding to a treatment duration (0, 3, 5, 7, or 14 days, respectively). The expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the tension area of the PDL over time were analyzed by immunochemistry staining. For the in-vitro study, the expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the myofibroblasts and human osteoblast-like cells (MG63) coculture and PDL cells-MG63 coculture systems were examined by Western blot and real-time polymerase chain reaction. RESULTS Enhanced expression of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the tension area of the PDL under orthodontic loading were observed in vivo, and increased expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin in the myofibroblasts-MG63 coculture system were observed compared with the controls. CONCLUSIONS Expressions of α-smooth muscle actin, collagen type I, collagen type III, and osteocalcin are up-regulated in the PDL under orthodontic tensile loading. Myofibroblasts have a more positive effect on collagen synthesis and osteocalcin expression than do PDL cells.
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Affiliation(s)
- Hui Xu
- PhD candidate, State Key Laboratory of Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xianglong Han
- Lecturer, State Key Laboratory of Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yao Meng
- Associate professor, Department of Orthodontics, Shenzhen Children's Hospital, Shenzhen, China
| | - Lei Gao
- Postgraduate student, State Key Laboratory of Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yongwen Guo
- PhD candidate, State Key Laboratory of Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yan Jing
- PhD candidate, State Key Laboratory of Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ding Bai
- Professor and chair, State Key Laboratory of Oral Diseases, Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
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Lee JH, Park JH, El-Fiqi A, Kim JH, Yun YR, Jang JH, Han CM, Lee EJ, Kim HW. Biointerface control of electrospun fiber scaffolds for bone regeneration: engineered protein link to mineralized surface. Acta Biomater 2014; 10:2750-61. [PMID: 24468581 DOI: 10.1016/j.actbio.2014.01.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 01/11/2014] [Accepted: 01/16/2014] [Indexed: 12/12/2022]
Abstract
Control over the interface of biomaterials that favors the initial adhesion and subsequent differentiation of stem cells is one of the key strategies in bone tissue engineering. Here we engineer the interface of biopolymer electrospun fiber matrices with a fusion protein of fibronectin 9-10 domain (FNIII9-10) and osteocalcin (OCN), aiming to stimulate mesenchymal stem cell (MSC) functions, including initial adhesion, growth and osteogenic differentiation. In particular, a specific tethering of FNIII9-10-OCN protein was facilitated by the hydroxyapatite (HA) mineralization of the biopolymer surface through a molecular recognition of OCN to the HA crystal lattice. The FNIII9-10-OCN anchorage to the HA-mineralized fiber was observed to be highly specific and tightly bound to preserve stability over a long period. Initial cell adhesion levels, as well as the spreading shape and process, of MSCs within 24h were strikingly different between the fibers linked with and without fusion protein. Significant up-regulations in the mRNA expression of adhesion signaling molecules occurred with the fusion protein link, as analyzed by the reverse transcriptase polymerase chain reaction. The expression of a series of osteogenic-related genes at later stages, over 2-3weeks, was significantly improved in the fusion protein-tailored fiber, and the osteogenic protein levels were highly stimulated, as confirmed by immunofluorescence imaging and fluorescence-activated cell sorting analyses. In vivo study in a rat calvarium model confirmed a higher quantity of new bone formation in the fiber linked with fusion protein, and a further increase was noticed when the MSCs were tissue-engineered with the fusion protein-linked fiber. Collectively, these results indicate that FN-OCN fusion protein links via HA mineralization is a facile tool to generate a biointerface with cell-attractive and osteogenic potential, and that the engineered fibrous matrix is a potential bone regenerative scaffold.
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Affiliation(s)
- Jae Ho Lee
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea
| | - Jeong-Hui Park
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea
| | - Ahmed El-Fiqi
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea
| | - Joong-Hyun Kim
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea
| | - Ye-Rang Yun
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea
| | - Jun-Hyeog Jang
- Department of Biochemistry, Medical College, Inha University, Republic of Korea
| | - Cheol-Min Han
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Biomaterials Science, College of Dentistry, Dankook University, Republic of Korea
| | - Eun-Jung Lee
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea
| | - Hae-Won Kim
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Republic of Korea; Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University Graduate School, Republic of Korea; Department of Biochemistry, Medical College, Inha University, Republic of Korea.
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Willems BAG, Vermeer C, Reutelingsperger CPM, Schurgers LJ. The realm of vitamin K dependent proteins: shifting from coagulation toward calcification. Mol Nutr Food Res 2014; 58:1620-35. [PMID: 24668744 DOI: 10.1002/mnfr.201300743] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/27/2013] [Accepted: 01/01/2014] [Indexed: 12/20/2022]
Abstract
In the past few decades vitamin K has emerged from a single-function "haemostasis vitamin" to a "multi-function vitamin." The use of vitamin K antagonists (VKA) inevitably showed that the inhibition was not restricted to vitamin K dependent coagulation factors but also synthesis of functional extrahepatic vitamin K dependent proteins (VKDPs), thereby eliciting undesired side effects. Vascular calcification is one of the recently revealed detrimental effects of VKA. The discovery that VKDPs are involved in vascular calcification has propelled our mechanistic understanding of this process and has opened novel avenues for diagnosis and treatment. This review addresses mechanisms of VKDPs and their significance for physiological and pathological calcification.
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Affiliation(s)
- Brecht A G Willems
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands; VitaK BV, Maastricht University, Maastricht, The Netherlands
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Abstract
The skeleton is an endocrine organ that regulates energy metabolism through the release of the osteoblast-derived hormone, osteocalcin (Ocn), and phosphate and vitamin D homeostasis through the secretion by osteoblasts and osteocytes of the novel hormone, FGF23 Ocn activates a widely expressed G-protein coupled receptor, GPRC6A, to regulate insulin secretion by pancreatic β-cells, testosterone secretion by testicular Leydig cells, fatty acid metabolism in the liver, and insulin sensitivity of muscle and fat, as well as other functions. FGF23 targets a limited number of tissues, including kidney, parathyroid gland, choroid plexus, and pituitary gland that co-express FGF receptors and α-Klotho complexes. Ectodomain shedding and secretion of a soluble form of Klotho also is purported to act as an anti-ageing hormone. Further elucidation of these novel endocrine networks is likely to lead to new appreciation of the cooperation between various organ systems to regulate phosphate, vitamin D, and energy metabolism.
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Affiliation(s)
- Min Pi
- Division of Nephrology, The University of Tennessee Health Science Center, 956 Court Ave, Suite B266, Memphis, TN, 38163, USA
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Quarles LD. A systems biology preview of the relationships between mineral and metabolic complications in chronic kidney disease. Semin Nephrol 2013; 33:130-42. [PMID: 23465500 DOI: 10.1016/j.semnephrol.2012.12.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
There are emerging data that the skeleton is connected to systemic biological functions through the release of two osteoblast-/osteocyte-derived hormones, fibroblastic growth factor 23 (FGF23) and undercarboxylated osteocalcin (Ocn). FGF23 is important in the regulation of phosphate and vitamin D metabolism, whereas Ocn participates in endocrine networks, coordinating bone and fat mass, energy metabolism, and sex hormone production. Bone remodeling and mineralization per se, along with the hormones leptin, insulin, glucocorticoids, PTH, and 1,25(OH)2D, regulate the release of FGF23 and Ocn, leading to complex cross-talk and coordination between endocrine networks previously thought to be distinct. These pathways are particularly important in chronic kidney disease, in which both FGF23 and Ocn are increased. Although these hormones initially serve an adaptive role, with progressive loss of renal function they show maladaptive effects, particularly on the cardiovascular system, through multiple mechanisms, including possible cross-talk with the renin angiotensin system. The complex interconnections between the various endocrine networks in chronic kidney disease may account for the difficulty in treating the uremic state.
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Affiliation(s)
- L Darryl Quarles
- Department of Medicine and Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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Neve A, Corrado A, Cantatore FP. Osteocalcin: skeletal and extra-skeletal effects. J Cell Physiol 2013; 228:1149-53. [PMID: 23139068 DOI: 10.1002/jcp.24278] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 10/29/2012] [Indexed: 12/15/2022]
Abstract
Osteocalcin (OC) is a non-collagenous, vitamin K-dependent protein secreted in the late stage of osteoblasts differentiation. The presence of the three residues of γ-carbossiglutamatic acid, specific of the active form of OC protein, allows the protein to bind calcium and consequently hydroxyapatite. The osteoblastic OC protein is encoded by the bone γ-carbossiglutamate gene whose transcription is principally regulated by the Runx2/Cbfa1 regulatory element and stimulated by vitamin D(3) through a steroid-responsive enhancer sequence. Even if data obtained in literature are controversial, the dual role of OC in bone can be presumed as follows: firstly, OC acts as a regulator of bone mineralization; secondly, OC regulates osteoblast and osteoclast activity. Recently the metabolic activity of OC, restricted to the un-carboxylated form has been demonstrated in osteoblast-specific knockout mice. This effect is mediated by the regulation of pancreatic β-cell proliferation and insulin secretion and adiponectin production by adipose tissue and leads to the regulation of glucose metabolism and fat mass. Nevertheless, clinical human studies only demonstrated the correlation between OC levels and factors related to energy metabolism. Thus further investigations in humans are required to demonstrate the role of OC in the regulation of human energy metabolism. Moreover, it is presumable that OC also acts on blood vessels by inducing angiogenesis and pathological mineralization. This review highlights the recent studies concerning skeletal and extra-skeletal effects of OC.
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Affiliation(s)
- Anna Neve
- Department of Medical and Surgical Sciences, Rheumatology Clinic, University of Foggia, Foggia, Italy
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Lee JH, Park JH, Yun YR, Jang JH, Lee EJ, Chrzanowski W, Wall IB, Kim HW. Tethering bi-functional protein onto mineralized polymer scaffolds to regulate mesenchymal stem cell behaviors for bone regeneration. J Mater Chem B 2013; 1:2731-2741. [DOI: 10.1039/c3tb00043e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chunxiao W, Yu Z, Wentao L, Jingjing L, Jiahui Y, Qingmei C. Impacts of the N-terminal fragment analog of human parathyroid hormone on structure, composition and biomechanics of bone. Eur J Pharm Sci 2012; 47:926-33. [DOI: 10.1016/j.ejps.2012.09.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 08/27/2012] [Accepted: 09/12/2012] [Indexed: 10/27/2022]
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Manavalan JS, Cremers S, Dempster DW, Zhou H, Dworakowski E, Kode A, Kousteni S, Rubin MR. Circulating osteogenic precursor cells in type 2 diabetes mellitus. J Clin Endocrinol Metab 2012; 97:3240-50. [PMID: 22740707 PMCID: PMC3431571 DOI: 10.1210/jc.2012-1546] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
CONTEXT Type 2 diabetes mellitus (T2D) is associated with an increased risk of fractures and low bone formation. However, the mechanism for the low bone formation is not well understood. Recently, circulating osteogenic precursor (COP) cells, which contribute to bone formation, have been characterized in the peripheral circulation. OBJECTIVE Our objective was to characterize the number and maturity of COP cells in T2D. PATIENTS, DESIGN, AND SETTING Eighteen postmenopausal women with T2D and 27 controls participated in this cross-sectional study at a clinical research center. MAIN OUTCOME MEASURES COP cells were characterized using flow cytometry and antibodies against osteocalcin (OCN) and early stem cell markers. Histomorphometric (n = 9) and molecular (n=14) indices of bone turnover and oxidative stress were also measured. RESULTS The percentage of OCN(+) cells in peripheral blood mononuclear cells was lower in T2D (0.8 ± 0.2 vs. 1.6 ± 0.4%; P < 0.0001), whereas the percentage of OCN(+) cells coexpressing the early marker CD146 was increased (OCN(+)/CD146(+): 33.3 ± 7 vs. 12.0 ± 4%; P < 0.0001). Reduced histomorphometric indices of bone formation were observed in T2D subjects, including mineralizing surface (2.65 ± 1.9 vs. 7.58 ± 2.4%, P = 0.02), bone formation rate (0.01 ± 0.1 vs. 0.05 ±0.2 μm(3)/um(2) · d, P = 0.02), and osteoblast surface (1.23 ±0.9 vs. 4.60 ± 2.5%, P = 0.03). T2D subjects also had reduced molecular expression of the osteoblast regulator gene Runx2 but increased expression of the oxidative stress markers p66(Shc) and SOD2. CONCLUSIONS Circulating OCN(+) cells were decreased in T2D, whereas OCN(+)/CD146(+) cells were increased. Histomorphometric indices of bone formation were decreased in T2D, as was molecular expression of osteoblastic activity. Stimulation of bone formation may have beneficial therapeutic skeletal consequences in T2D.
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Affiliation(s)
- J S Manavalan
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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Mas-Moruno C, Dorfner PM, Manzenrieder F, Neubauer S, Reuning U, Burgkart R, Kessler H. Behavior of primary human osteoblasts on trimmed and sandblasted Ti6Al4V surfaces functionalized with integrin αvβ3-selective cyclic RGD peptides. J Biomed Mater Res A 2012; 101:87-97. [DOI: 10.1002/jbm.a.34303] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 05/10/2012] [Accepted: 05/25/2012] [Indexed: 02/05/2023]
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Pi M, Quarles LD. Multiligand specificity and wide tissue expression of GPRC6A reveals new endocrine networks. Endocrinology 2012; 153:2062-9. [PMID: 22374969 PMCID: PMC3339644 DOI: 10.1210/en.2011-2117] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 01/30/2012] [Indexed: 01/29/2023]
Abstract
Emerging evidence supports the hypothesis that the skeleton is an endocrine organ that regulates energy metabolism through the release of the osteoblast-derived hormone, osteocalcin (Ocn). This bone-pancreas endocrine network is controversial because important gaps remain to be filled in our knowledge of the physiological effects of Ocn in multiple organs and the complex alterations in other hormonal networks induced by Ocn administration. A key step toward understanding the integrative regulation of energy metabolism by bone is the identification of GPCR family C group 6 member A (GPRC6A) as the Ocn receptor. GPRC6A is an amino acid-sensing G protein-coupled receptor highly expressed in β-cells and is activated by recombinant Ocn in vitro and in vivo but that is widely expressed in tissues other than the pancreas and is capable of sensing multiple structurally unrelated ligands, including l-amino acids, cations, and anabolic steroids in addition to Ocn. The broad expression and multiligand specificity of GPRC6A is identifying both systemic and paracrine regulation of seemingly disparate biological processes, ranging from energy metabolism, sexual reproduction, hypothalamic-pituitary function, bone formation, and prostate cancer. Consistent with the existence of more complex endocrine networks, ablation of GPRC6A in Gprc6a(-/-) mice results in complex metabolic abnormalities, including obesity, glucose intolerance, hepatic steatosis, insulin resistance, hyperphosphatemia, osteopenia, plus several hormonal abnormalities, including decreased circulating testosterone, IGF-I, and insulin and increased estradiol, LH, GH, and leptin. Recombinant Ocn also regulates testosterone production by the testes and male fertility through a GPRC6A-dependent mechanism, and testosterone regulation of LH secretion is abnormal in Gprc6a(-/-) mice. Thus, GPRC6A, as the biologically relevant receptor for Ocn, defines not only a molecular mechanism for linking bone metabolism with metabolic regulation of β-cells and sexual reproduction but also as a receptor shared by testosterone and dietary factors, and it is also involved in multiple endocrine networks integrating the functions of pancreas, muscle, liver, fat, testes, bone, and the hypothalamic-pituitary axis with alterations in both environmental and endogenous ligands.
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Affiliation(s)
- Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Sulniute R, Lindh T, Wilczynska M, Li J, Ny T. Plasmin is essential in preventing periodontitis in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:819-28. [PMID: 21704601 PMCID: PMC3157224 DOI: 10.1016/j.ajpath.2011.05.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 04/03/2011] [Accepted: 05/02/2011] [Indexed: 12/18/2022]
Abstract
Periodontitis involves bacterial infection, inflammation of the periodontium, degradation of gum tissue, and alveolar bone resorption, which eventually leads to loss of teeth. To study the role of the broad-spectrum protease plasmin in periodontitis, we examined the oral health of plasminogen (Plg)-deficient mice. In wild-type mice, the periodontium was unaffected at all time points studied; in Plg-deficient mice, periodontitis progressed rapidly, within 20 weeks. Morphological study results of Plg-deficient mice revealed detachment of gingival tissue, resorption of the cementum layer, formation of necrotic tissue, and severe alveolar bone degradation. IHC staining showed massive infiltration of neutrophils in the periodontal tissues. Interestingly, doubly deficient mice, lacking both tissue- and urokinase-type plasminogen activators, developed periodontal disease similar to that in Plg-deficient mice; however, mice lacking only tissue- or urokinase-type plasminogen activator remained healthy. Supplementation by injection of Plg-deficient mice with human plasminogen for 10 days led to necrotic tissue absorption, inflammation subsidence, and full regeneration of gum tissues. Notably, there was also partial regrowth of degraded alveolar bone. Taken together, our results show that plasminogen is essential for the maintenance of a healthy periodontium and plays an important role in combating the spontaneous development of chronic periodontitis. Moreover, reversal to healthy status after supplementation of Plg-deficient mice with plasminogen suggests the possibility of using plasminogen for therapy of periodontal diseases.
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Affiliation(s)
- Rima Sulniute
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Tomas Lindh
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- Department of Odontology/Prosthetic Dentistry, Umeå University, Umeå, Sweden
| | | | - Jinan Li
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Tor Ny
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
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26
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Pi M, Wu Y, Quarles LD. GPRC6A mediates responses to osteocalcin in β-cells in vitro and pancreas in vivo. J Bone Miner Res 2011; 26:1680-3. [PMID: 21425331 PMCID: PMC5079536 DOI: 10.1002/jbmr.390] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A bone-pancreas endocrine loop has been identified recently that involves insulin secreted from β-cells in the pancreas stimulating insulin receptors in osteoblasts, leading to osteoblastic differentiation and increased secretion of osteocalcin (Ocn), a bone-derived hormone that regulates insulin secretion in β-cells. The identity of the Ocn-sensing receptor in β-cells is a missing component of this endocrine loop. The abnormalities in glucose homeostasis in Gprc6a null mice suggests that this pertussis toxin-sensitive G protein-coupled receptor is a candidate for mediating the effects of Ocn on insulin secretion in the pancreas. In support of this possibility, we found that transfection of non-Gprc6a-expressing HEK-293 cells with a full-length Gprc6a cDNA imparted a dose-dependent response to Ocn (5 to 60 ng/mL), as measured by PKD1 and ERK phosphorylation. In addition, Gprc6a is highly expressed in mouse pancreatic tissue and in the mouse TC-6 pancreatic β-cell line. Ocn also stimulated ERK activity in TC-6 pancreatic β-cells. Finally, intraperitoneal injection of Ocn stimulated ERK activity in the pancreas and increased serum insulin levels in wild-type mice, but these responses were markedly attenuated in Gprc6a(-/-) mice. These findings suggest that GPRC6A is a candidate for mediating the response to Ocn in the bone-pancreas endocrine loop regulating insulin signaling.
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Affiliation(s)
- Min Pi
- Musculoskeletal, Orthopedic and Dental Institute and Department of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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27
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Pi M, Chen L, Huang MZ, Zhu W, Ringhofer B, Luo J, Christenson L, Li B, Zhang J, Jackson PD, Faber P, Brunden KR, Harrington JJ, Quarles LD. GPRC6A null mice exhibit osteopenia, feminization and metabolic syndrome. PLoS One 2008; 3:e3858. [PMID: 19050760 PMCID: PMC2585477 DOI: 10.1371/journal.pone.0003858] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 11/12/2008] [Indexed: 12/20/2022] Open
Abstract
Background GPRC6A is a widely expressed orphan G-protein coupled receptor that senses extracellular amino acids, osteocalcin and divalent cations in vitro. The physiological functions of GPRC6A are unknown. Methods/Principal Findings In this study, we created and characterized the phenotype of GPRC6A−/− mice. We observed complex metabolic abnormalities in GPRC6A−/− mice involving multiple organ systems that express GPRC6A, including bone, kidney, testes, and liver. GPRC6A−/− mice exhibited hepatic steatosis, hyperglycemia, glucose intolerance, and insulin resistance. In addition, we observed high expression of GPRC6A in Leydig cells in the testis. Ablation of GPRC6A resulted in feminization of male GPRC6A−/− mice in association with decreased lean body mass, increased fat mass, increased circulating levels of estradiol, and reduced levels of testosterone. GPRC6A was also highly expressed in kidney proximal and distal tubules, and GPRC6A−/− mice exhibited increments in urine Ca/Cr and PO4/Cr ratios as well as low molecular weight proteinuria. Finally, GPRC6A−/− mice exhibited a decrease in bone mineral density (BMD) in association with impaired mineralization of bone. Conclusions/Significance GPRC6A−/− mice have a metabolic syndrome characterized by defective osteoblast-mediated bone mineralization, abnormal renal handling of calcium and phosphorus, fatty liver, glucose intolerance and disordered steroidogenesis. These findings suggest the overall function of GPRC6A may be to coordinate the anabolic responses of multiple tissues through the sensing of extracellular amino acids, osteocalcin and divalent cations.
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Affiliation(s)
- Min Pi
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Ling Chen
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Min-Zhao Huang
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Wenyu Zhu
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Brian Ringhofer
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Junming Luo
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Lane Christenson
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Benyi Li
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Jianghong Zhang
- Center for Bone Biology, Clinical Pharmacology, Division/Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
| | | | - Pieter Faber
- Athersys, Inc., Cleveland, Ohio, United States of America
| | | | | | - L. Darryl Quarles
- The Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, United States of America
- * E-mail:
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28
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Bhat BM, Robinson JA, Coleburn VE, Zhao W, Kharode Y. Evidence of in vivo osteoinduction in adult rat bone by adeno-Runx2 intra-femoral delivery. J Cell Biochem 2008; 103:1912-24. [DOI: 10.1002/jcb.21581] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Mödder UI, Khosla S. Skeletal stem/osteoprogenitor cells: Current concepts, alternate hypotheses, and relationship to the bone remodeling compartment. J Cell Biochem 2008; 103:393-400. [PMID: 17541947 DOI: 10.1002/jcb.21423] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Plastic adherent bone marrow stromal cells have become synonymous with skeletal stem cells, and perhaps rightfully so, as these cells have been extremely well characterized over the past four decades, since their original description by Friedenstein. However, although this cell population is useful as an experimental model of precursors for osteoblasts and other mesenchymal lineages, the precise role of bone marrow stromal cells in bone remodeling, fracture repair, or repair of non-skeletal tissues remains unclear. Moreover, there is a conceptual problem in terms of postulating that these cells are osteoblast precursors at sites of bone remodeling on trabecular surfaces adjacent to red marrow and yet having to posit potentially entirely different mechanisms for the origins of osteoblasts at sites of cortical bone remodeling distant from red marrow. Thus, the identification and characterization in recent years of non-adherent stem and osteoprogenitor cells in the bone marrow, of similar cells in the peripheral circulation, and of stem/osteoprogenitor cells arising either from the perivascular compartment (pericytes) or within the developing vascular wall itself, has suggested alternative candidate cell populations that may help to resolve the problem of postulating different mechanisms of remodeling in trabecular versus cortical bone. When coupled with our evolving understanding of the bone remodeling compartment (BRC), a closed cavity penetrated by capillaries which appears to be the site of remodeling in both trabecular and cortical bone, it is likely that our conceptual understanding of the fundamental mechanisms of bone remodeling will need to be modified.
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30
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Eghbali-Fatourechi GZ, Mödder UIL, Charatcharoenwitthaya N, Sanyal A, Undale AH, Clowes JA, Tarara JE, Khosla S. Characterization of circulating osteoblast lineage cells in humans. Bone 2007; 40:1370-7. [PMID: 17320497 PMCID: PMC1920541 DOI: 10.1016/j.bone.2006.12.064] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 12/09/2006] [Accepted: 12/27/2006] [Indexed: 12/11/2022]
Abstract
We recently identified circulating osteoblastic cells using antibodies to osteocalcin (OCN) or alkaline phosphatase (AP). We now provide a more detailed characterization of these cells. Specifically, we demonstrate that 46% of OCN positive (OCN(pos)) cells express AP, and 37% also express the hematopoietic/endothelial marker CD34. Using two different anti-OCN antibodies and forward/side light scatter characteristics by flow cytometry, we find that OCN(pos) cells consist of two distinct populations: one population exhibits low forward/side scatter, consistent with a small cell phenotype with low granularity, and a second population has higher forward/side scatter (larger and more granular cell). The smaller, low granularity population also co-expresses CD34, whereas the larger, more granular cells are CD34 negative. Using samples from 26 male subjects aged 28 to 68 years, we demonstrate that the concentration of circulating OCN(pos) cells increases as a function of age (R=0.59, P=0.002). By contrast, CD34(pos) cells tend to decrease with age (R=-0.31, P=0.18); as a consequence, the ratio of OCN(pos):CD34(pos) cells also increase significantly with age (R=0.54, P=0.022). These findings suggest significant overlap between circulating cells expressing OCN and those expressing the hematopoietic/endothelial marker CD34. Further studies are needed to define the precise role of circulating OCN(pos) cells not only in bone remodeling but rather also potentially in the response to vascular injury.
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Affiliation(s)
| | - Ulrike I. L. Mödder
- Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota
| | | | - Arunik Sanyal
- Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Anita H. Undale
- Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Jackie A. Clowes
- Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - James E. Tarara
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Sundeep Khosla
- Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota
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31
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Abstract
While osteoclast lineage cells are clearly present in the peripheral circulation, whether there is a comparable pool of circulating osteoblast lineage cells has remained controversial. Using assays requiring adherence to plastic (as originally described by Friedenstein and colleagues for bone marrow stromal cells over four decades ago), several studies have shown that plastic adherent cells with osteogenic potential are, indeed, present in the circulation of a number of species, but at extremely low concentrations. Work from a number of independent groups over the past decade has also identified a population of nonadherent bone marrow cells with osteogenic potential. Since these nonadherent cells may be much more likely to access the peripheral circulation than plastic adherent cells, we tested for the presence of circulating osteoblast lineage cells in humans using flow cytometry to identify cells in the peripheral blood expressing bone-related proteins. Our findings indicate that these cells are present in the circulation in significant numbers, are markedly increased in the peripheral blood of adolescent boys going through the growth spurt, and may also increase following fractures. These circulating osteogenic cells express bone-related proteins, can mineralize in vitro, and form bone in vivo. The identification of these osteogenic cells in peripheral blood opens up new questions regarding the possible role of these cells in bone remodeling, in fracture repair, and possibly in vascular calcification.
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Affiliation(s)
- Sundeep Khosla
- Endocrine Research Unit, Mayo Clinic, 200 First Street SW, 5-194 Joseph, Rochester, MN 55905, USA.
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32
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Turhani D, Watzinger E, Weissenböck M, Yerit K, Cvikl B, Ewers R, Thurnher D. Expression pattern of the chromosome 21 transcription factor Ets2 in cell-seeded three-dimensional bone constructs. J Biomed Mater Res A 2005; 73:445-55. [PMID: 15900611 DOI: 10.1002/jbm.a.30292] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ability to generate new bone for reconstructive surgery use is a major clinical need. Tissue engineering with osteoprogenitor cells isolated from the patient's periosteum and seeded into bioresorbable scaffolds offers a promising approach to the generation of skeletal tissue. To our knowledge, there is no description about the expression of Ets2 in tissue engineered "bone neotissue." The aim of our study was to manufacture cell-seeded three-dimensional bone constructs with human periosteal cells on poly (lactic-co-glycolic acid) polymer fleeces to describe the expression pattern of Ets2 and its target genes osteocalcin and osteopontin; expression analysis of type I collagen, core-binding factor-1, alkaline phosphatase, and osteonectin; the ability of matrix mineralization and ALP enzymatic activity showed the osteogenic character of the constructs. A significant correlation between the expression of Ets2 and osteopontin mRNA (r = -0.70; p < 0.05) could be shown. A 1.35-fold increase of Ets2 expression from days 1 to 9 was detected, followed by a slight decrease from days 11 to 15. Until the end of the culture period, the expression of Ets2 reached a comparable high level as detected on day 9. In contrast, the expression level of osteopontin mRNA reached a maximum at day 7, followed by a progressive 3.04-fold decrease until day 21. This study shows for the first time that Ets2 gene and its transcriptional target genes are expressed in tissue-engineered bone constructs. These findings have the potential to provide much-needed information about the role and function of Ets2 in human osteogenesis processes and creation of "bone neotissue."
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Affiliation(s)
- Dritan Turhani
- Department of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Vienna, Austria.
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33
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Krout A, Wen HB, Hippensteel E, Li P. A hybrid coating of biomimetic apatite and osteocalcin. J Biomed Mater Res A 2005; 73:377-87. [PMID: 15957205 DOI: 10.1002/jbm.a.30310] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A novel hybrid coating of biomimetic apatite(BAp) and osteocalcin (OC) was prepared by incubating BAp-coated Ti6A14V coupons in an osteocalcin-containing medium. A significant amount (up to 1.0 wt %) of OC was adsorbed by the BAp coating within 3 h of incubation as demonstrated by high-performance liquid chromatography. Characterizations of the hybrid coating with environmental scanning microscopy and X-ray diffraction indicated that protein adsorption does not alter the microstructure of the coating. The presence of OC in the hybrid coating was visualized with fluorescence microscopy using an immuno-labeling procedure. The affinity of OC to the BAp coating was examined using a 20-h elution test in phosphate-buffered saline and only a minimal amount (<10%) of the loaded OC was eluted out. When the coating was fully dissolved in hydrochloric acid solution after elution, about 78% of the loaded OC could be recovered. Enzyme-linked immunosorbent assay and peptide sodium dodecylsulfate-polyacrylamide gel electrophoresis confirmed the integrity and activity of OC molecules throughout the tests. The preliminary cell culture tests showed a significant effect of OC on the attachment and proliferation of osteoblasts. The quick loading profile and high affinity of OC to the BAp coating make it an ideal candidate for the hybrid coating preparation in clinical environment.
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Affiliation(s)
- Ashley Krout
- Bioceramics Research Group, DePuy, a Johnson & Johnson Company, 700 Orthopaedic Drive, Warsaw, Indiana 46581, USA
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34
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Billiard J, Way DS, Seestaller-Wehr LM, Moran RA, Mangine A, Bodine PVN. The orphan receptor tyrosine kinase Ror2 modulates canonical Wnt signaling in osteoblastic cells. Mol Endocrinol 2004; 19:90-101. [PMID: 15388793 DOI: 10.1210/me.2004-0153] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Ror2 is an orphan receptor tyrosine kinase that plays crucial roles in developmental morphogenesis, particularly of the skeleton. We have identified human Ror2 as a novel regulator of canonical Wnt signaling in osteoblastic (bone-forming) cells with selective activities, enhancing Wnt1 but antagonizing Wnt3. Immunoprecipitation studies demonstrated physical interactions between human Ror2 and mammalian Wnt1 and Wnt3. Functionally, Ror2 antagonized Wnt1- and Wnt3-mediated stabilization of cytosolic beta-catenin in osteoblastic cells. However, Ror2 had opposing effects on a more distal step of canonical Wnt signaling: it potentiated Wnt1 activity but inhibited Wnt3 function as assessed by changes in Wnt-responsive reporter gene activity. Despite binding to Ror2, neither Wnt1 nor Wnt3 altered receptor activity as assessed by levels of Ror2 autophosphorylation. The ability of Ror2 to regulate canonical Wnt signaling in osteoblastic cells should have physiological consequences in bone, because Wnt signaling is known to modulate osteoblast survival and differentiation. Expression of Ror2 mRNA was highly regulated in a biphasic manner during human osteoblast differentiation, being virtually undetectable in pluripotent stem cells, increasing 300-fold in committed preosteoblasts, and disappearing again in osteocytes. Furthermore, Ror2 expression in osteoblasts was suppressed by the Wnt antagonist, secreted frizzled-related protein 1. The regulated expression of Ror2 during osteoblast differentiation, its inverse expression pattern with secreted frizzled-related protein 1, and its ability to modulate Wnt signaling in osteoblastic cells suggest that Ror2 may regulate bone formation.
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Affiliation(s)
- Julia Billiard
- Women's Health Research Institute, Wyeth Research, 500 Arcola Road, Collegeville, Pennsylvania 19426, USA.
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35
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Silva TA, Rosa AL, Lara VS. Dentin matrix proteins and soluble factors: intrinsic regulatory signals for healing and resorption of dental and periodontal tissues? Oral Dis 2004; 10:63-74. [PMID: 14996275 DOI: 10.1111/j.1601-0825.2004.00992.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Dentin contains numerous polypeptides and signaling molecules sequestered in a mineralized matrix. The exposure and release of these molecules occur as a consequence of injury to the pulp and periodontal ligament, which may result from luxation, orthodontic movement or infections of tooth and periodontal structures. When released at these sites, dentin constituents have the potential to act on different surrounding cells, including periodontal cells, osteoblasts, osteoclasts and inflammatory cells, and to affect the course of dental disease. Experimental studies have highlighted the interactions between dentin and cells from tooth and periodontal tissues and reveal dentin to be a cell adhesive, signaling and migratory stimulus for various mesenchymal and inflammatory cells. These results support the hypothesis that dentin molecules might function as regulatory signals for the healing and resorption of dental and periodontal tissues. Data from recent and classical investigations are summarized, many open questions are discussed, and current hypotheses concerning the mechanisms of tooth resorption and periodontal healing are outlined. Many questions regarding the importance of dentin as a source of multifunctional molecules remain unanswered and provide important directions for future studies.
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Affiliation(s)
- T A Silva
- Department of Stomatology, Faculty of Dentistry of Bauru, University of São Paulo, São Paulo, Brazil.
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36
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Olkku A, Bodine PVN, Linnala-Kankkunen A, Mahonen A. Glucocorticoids induce glutamine synthetase expression in human osteoblastic cells: a novel observation in bone. Bone 2004; 34:320-9. [PMID: 14962810 DOI: 10.1016/j.bone.2003.09.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2003] [Revised: 08/28/2003] [Accepted: 09/26/2003] [Indexed: 01/12/2023]
Abstract
Glucocorticoids have marked effects on bone metabolism, and continued exposure of skeletal tissue to excessive amounts of these steroids results in osteoporosis. Therefore, in the present proteomic study, we characterized the potential effects of glucocorticoids on protein expression in human osteoblastic cells. Using two-dimensional gel electrophoresis and mass spectrometry, we identified an increased expression of glutamine synthetase (GS) in dexamethasone (Dex)-treated human MG-63 osteosarcoma cells. GS is an enzyme catalyzing the conversion of glutamate and ammonia to glutamine. Intracellular and extracellular glutamate levels may be important in cell signalling mediated by glutamate transporters and receptors which have recently been found in bone cells. The induction of GS protein by Dex was accompanied by an increase in mRNA level and enzyme activity. Dex induction of GS was also mediated by glucocorticoid receptors (GRs) because it was blocked by the GR antagonist RU-38486. In addition, Dex induction of GS expression was partially blocked by cyclohexamide indicating that it at least partly required new protein synthesis. GS induction by Dex was not associated with apoptosis as determined by Bax/Bcl-2 ratio and DNA staining. In addition to MG-63 cells, Dex induction of GS was also observed in human G-292 osteosarcoma cells as well as conditionally immortalized human preosteoblastic (HOB-03-C5) and mature osteoblastic (HOB-03-CE6) cells. However, in two other human osteosarcoma cell lines, SaOS-2 and U2-OS, GS expression was not affected by Dex. This observation may be explained by the lower levels of GR protein in these cells. In summary, this is the first report of the regulation of GS expression by glucocorticoids in bone cells. The role of GS in bone cell metabolism and glucocorticoid action on the skeleton is not yet known, but as a modulator of intracellular glutamate and glutamine levels, it may have an important role in these processes.
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Affiliation(s)
- A Olkku
- Department of Medical Biochemistry, University of Kuopio, Kuopio, Finland.
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37
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Hoang QQ, Sicheri F, Howard AJ, Yang DSC. Bone recognition mechanism of porcine osteocalcin from crystal structure. Nature 2003; 425:977-80. [PMID: 14586470 DOI: 10.1038/nature02079] [Citation(s) in RCA: 342] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2003] [Accepted: 09/15/2003] [Indexed: 12/13/2022]
Abstract
Osteocalcin is the most abundant noncollagenous protein in bone, and its concentration in serum is closely linked to bone metabolism and serves as a biological marker for the clinical assessment of bone disease. Although its precise mechanism of action is unclear, osteocalcin influences bone mineralization, in part through its ability to bind with high affinity to the mineral component of bone, hydroxyapatite. In addition to binding to hydroxyapatite, osteocalcin functions in cell signalling and the recruitment of osteoclasts and osteoblasts, which have active roles in bone resorption and deposition, respectively. Here we present the X-ray crystal structure of porcine osteocalcin at 2.0 A resolution, which reveals a negatively charged protein surface that coordinates five calcium ions in a spatial orientation that is complementary to calcium ions in a hydroxyapatite crystal lattice. On the basis of our findings, we propose a model of osteocalcin binding to hydroxyapatite and draw parallels with other proteins that engage crystal lattices.
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Affiliation(s)
- Quyen Q Hoang
- Department of Biochemistry, Faculty of Health Science, McMaster University, Hamilton, Ontario L8N 3Z5, Canada
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38
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Dowd TL, Rosen JF, Li L, Gundberg CM. The three-dimensional structure of bovine calcium ion-bound osteocalcin using 1H NMR spectroscopy. Biochemistry 2003; 42:7769-79. [PMID: 12820886 PMCID: PMC4517610 DOI: 10.1021/bi034470s] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Structural information on osteocalcin or other noncollagenous bone proteins is very limited. We have solved the three-dimensional structure of calcium bound osteocalcin using (1)H 2D NMR techniques and proposed a mechanism for mineral binding. The protons in the 49 amino acid sequence were assigned using standard two-dimensional homonuclear NMR experiments. Distance constraints, dihedral angle constraints, hydrogen bonds, and (1)H and (13)C chemical shifts were all used to calculate a family of 13 structures. The tertiary structure of the protein consisted of an unstructured N terminus and a C-terminal loop (residues 16-49) formed by long-range hydrophobic interactions. Elements of secondary structure within residues 16-49 include type III turns (residues 20-25) and two alpha-helical regions (residues 27-35 and 41-44). The three Gla residues project from the same face of the helical turns and are surface exposed. The genetic algorithm-molecular dynamics simulation approach was used to place three calcium atoms on the NMR-derived structure. One calcium atom was coordinated by three side chain oxygen atoms, two from Asp30, and one from Gla24. The second calcium atom was coordinated to four oxygen atoms, two from the side chain in Gla 24, and two from the side chain of Gla 21. The third calcium atom was coordinated to two oxygen atoms of the side chain of Gla17. The best correlation of the distances between the uncoordinated Gla oxygen atoms is with the intercalcium distance of 9.43 A in hydroxyapatite. The structure may provide further insight into the function of osteocalcin.
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Affiliation(s)
- T L Dowd
- Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York 10467, USA.
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39
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Babij P, Zhao W, Small C, Kharode Y, Yaworsky PJ, Bouxsein ML, Reddy PS, Bodine PVN, Robinson JA, Bhat B, Marzolf J, Moran RA, Bex F. High bone mass in mice expressing a mutant LRP5 gene. J Bone Miner Res 2003; 18:960-74. [PMID: 12817748 DOI: 10.1359/jbmr.2003.18.6.960] [Citation(s) in RCA: 440] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A unique mutation in LRP5 is associated with high bone mass in man. Transgenic mice expressing this LRP5 mutation have a similar phenotype with high bone mass and enhanced strength. These results underscore the importance of LRP5 in skeletal regulation and suggest targets for therapies for bone disease. A mutation (G171V) in the low-density lipoprotein receptor related protein 5 (LRP5) has been associated with high bone mass (HBM) in two independent human kindreds. To validate the role of the mutation, several lines of transgenic mice were created expressing either the human LRP5 G171V substitution or the wildtype LRP5 gene in bone. Volumetric bone mineral density (vBMD) analysis by pQCT showed dramatic increases in both total vBMD (30-55%) and trabecular vBMD (103-250%) of the distal femoral metaphysis and increased cortical size of the femoral diaphysis in mutant G171V transgenics at 5, 9, 17, 26, and 52 weeks of age (p < 0.01 for all). In addition, high-resolution microcomputed tomography (microCT) analysis of the distal femorae and lumbar vertebrae revealed an increase (110-232%) in trabecular bone volume fraction caused by both increased trabecular number (41-74%) and increased trabecular thickness (34-46%; p < 0.01 for all) in the mutant G171V mice. The increased bone mass was associated with significant increases in vertebral compressive strength (80-140%) and the increased cortical size with significant increases in femoral bending strength (50-130%). There were no differences in osteoclast number at 17 weeks of age. However, compared with littermate controls, the mutant G171V transgenic mice showed an increase in actively mineralizing bone surface, enhanced alkaline phosphatase staining in osteoblasts, and a significant reduction in the number of TUNEL-positive osteoblasts and osteocytes. These results suggest that the increased bone mineral density in mutant G171V mice was caused by increased numbers of active osteoblasts, which could in part be because of their increased functional lifespan. While slight bone anabolic activity was observed from overexpression of the wildtype LRP5 gene, it is clear that the G171V mutation, rather than overexpression of the receptor itself, is primarily responsible for the dramatic HBM bone effects. Together, these findings establish the importance of this novel and unexpected role of a lipoprotein receptor in regulating bone mass and afford a new model to explore LRP5 and its recent association with Wnt signaling in bone biology.
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Affiliation(s)
- Philip Babij
- Genomics, Wyeth Research, Andover, Massachusetts, USA
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40
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Billiard J, Moran RA, Whitley MZ, Chatterjee-Kishore M, Gillis K, Brown EL, Komm BS, Bodine PVN. Transcriptional profiling of human osteoblast differentiation. J Cell Biochem 2003; 89:389-400. [PMID: 12704802 DOI: 10.1002/jcb.10514] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Osteoblast differentiation is a key aspect of bone formation and remodeling. To further our understanding of the differentiation process, we have developed a collection of conditionally immortalized adult human osteoblast cell lines representing discrete stages of differentiation. To evaluate changes in gene expression associated with differentiation, polyA((+)) RNA from pre-osteoblasts, early and late osteoblasts, and pre-osteocytes was subjected to gene chip analysis using the Affymetrix Hu6800 chip in conjunction with an Affymetrix custom chip enriched in bone and cartilage cDNAs. Overall, the expression of 47 genes was found to change threefold or more on both chips between the pre-osteoblastic and pre-osteocytic stages of differentiation. Many of the observed differences, including down-regulation of collagen type I and collagen-processing enzymes, reflect expected patterns and support the relevance of our results. Other changes have not been reported and offer new insight into the osteoblast differentiation process. Thus, we observed regulation of factors controlling cell cycle and proliferation, reflecting decreased proliferation, and increased apoptosis in pre-osteocytic cells. Elements maintaining the cytoskeleton, extracellular matrix, and cell-cell adhesion also changed with differentiation reflecting profound alterations in cell architecture associated with the differentiation process. We also saw dramatic down-regulation of several components of complement and other immune response factors that may be involved in recruitment and differentiation of osteoclasts. The decrease in this group of genes may provide a mechanism for controlling bone remodeling of newly formed bone. Our screen also identified several signaling proteins that may control osteoblast differentiation. These include an orphan nuclear receptor DAX1 and a small ras-related GTPase associated with diabetes, both of which increased with increasing differentiation, as well as a high mobility group-box transcription factor, SOX4, that was down-regulated during differentiation. In summary, our study provides a comprehensive transcriptional profile of human osteoblast differentiation and identifies several genes of potential importance in controlling differentiation of osteoblasts.
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Affiliation(s)
- J Billiard
- Women's Health Research Institute, Wyeth Research, Collegeville, Pennsylvania 19426, USA.
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Reddi AH, Roodman D, Freeman C, Mohla S. Mechanisms of tumor metastasis to the bone: challenges and opportunities. J Bone Miner Res 2003; 18:190-4. [PMID: 12568395 DOI: 10.1359/jbmr.2003.18.2.190] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In human cancers, bone is a common site for metastasis. It is well known that metastasis is the cause of morbidity and mortality in patients with cancer. Both breast and prostate carcinomas have a propensity to metastasize to bone. In general, metastatic breast cancers result in osteolytic lesions. On the other hand, prostate cancer metastases are osteoblastic and result in osteosclerosis. Thus, bone formation and bone resorption are at the crux of the cancer metastasis problem. For example, in the prostate, there is a vicious cycle of metastasis to bone (Fig. 1). Metastases to bone causes excruciating bone pain, pathological fractures, and eventually death, and therefore is a serious challenge to both bone biologists and cancer cell biologists. The stromal-epithelial interactions in breast and prostate are critical in initiation of carcinogenesis and the progression of the metastatic cascade to bone (Fig. 2). Over a hundred years ago, Stephen Paget enunciated the seed and soil hypothesis in which seeds of metastatic cancer cells of breast preferentially settle in the soil of bone matrix. Thus, the prostate/breast cancer bone interface and continuum has continuously presented challenges and opportunities and were discussed at a recent workshop.
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Affiliation(s)
- A Hari Reddi
- Center for Tissue Regeneration and Repair, University of California, School of Medicine, Sacramento, California 95817, USA.
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Bodine PVN, Komm BS. Tissue culture models for studies of hormone and vitamin action in bone cells. VITAMINS AND HORMONES 2002; 64:101-51. [PMID: 11898390 DOI: 10.1016/s0083-6729(02)64004-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Osteoporosis is a major health care concern and levies a serious financial burden on the world health care system. For this reason, many physicians and scientists are engaged in research to better understand and treat this disease. To this end, numerous in vitro bone cell models have been developed to explore the cellular and molecular mechanisms of skeletal biology and for the identification and characterization of new drug targets and therapies. In this chapter, we review many of these cellular models as tools to study the hormonal regulation of bone metabolism. In particular, we pay special attention to new human bone cell models, since these have the greatest relevance to osteoporosis research and drug discovery. These new models include (1) the use of peripheral blood mononuclear cells as progenitors of osteoclasts and primary cultures of mesenchymal stem cells as precursors of osteoblasts; (2) the development of conditionally immortalized preosteoclastic and osteoblastic cell lines using temperature-sensitive large T-antigens; and (3) the establishment of the first osteocytic cell lines. Thus, we now have at our disposal many good in vitro models to investigate the regulation of bone resorption and formation by hormones, vitamins and drugs. These models should accelerate our understanding of bone physiology and pathophysiology as well as our ability to develop important new therapies to prevent and treat skeletal diseases.
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Affiliation(s)
- Peter V N Bodine
- Women's Health Research Institute, Wyeth-Ayerst Research, Collegeville, Pennsylvania 19426, USA
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Papagerakis P, Berdal A, Mesbah M, Peuchmaur M, Malaval L, Nydegger J, Simmer J, Macdougall M. Investigation of osteocalcin, osteonectin, and dentin sialophosphoprotein in developing human teeth. Bone 2002; 30:377-85. [PMID: 11856645 DOI: 10.1016/s8756-3282(01)00683-4] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Biochemical investigations in rodents have shown that numerous mineralized matrix proteins share expression in bone, dentin, and cementum. Little information is available regarding the expression pattern of these proteins in human tissues, particularly during tooth formation. The aim of this study was to identify the expression pattern of the two major noncollagenous proteins of bone and dentin, osteocalcin (OC) and osteonectin (ON), in comparison to the dentin-specific protein, dentin sialophosphoprotein (DSPP). Mandibles from fetuses (5-26 weeks), neonate autopsies, forming teeth from 10-12-year-old patients, third molars extracted for orthodontic reasons, and bone tumors were collected with approval from the National Ethics Committee. Human OC, ON, and DSPP mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR) in fetal mandibles (5-11 weeks) and in primary cell cultures of dental pulp. In addition, OC, ON, and DSPP proteins were localized in forming human mineralized tissues using immunohistochemistry. In vivo, DSPP expression was associated with tooth terminal epithelial-mesenchymal interaction events, amelogenesis and dentinogenesis. Transient DSPP expression was seen in the presecretory ameloblasts with continuous expression in the odontoblasts. In contrast, both osteoblasts and odontoblasts showed a temporal gap between OC and ON expression in early development. ON was expressed in the initial stages of cytodifferentiation, whereas OC was expressed only during the later stages, especially in the teeth. At the maturation stage of enamel formation, both proteins were detected in odontoblasts and their processes within the extracellular matrix. In contrast to bone, OC was not localized extracellularly within the collagen-rich dentin matrix (predentin or intertubular dentin), but was found in the mature enamel. ON was present mostly in the nonmineralized predentin. These results demonstrate for the first time that both OC and ON are produced by human odontoblasts and determine the expression pattern of DSPP in human teeth, and suggest that OC and ON move inside the canalicule via odontoblast cell processes becoming localized to specific extracellular compartments during dentin and enamel formation. These distinct extracellular patterns may be related to the nature of DSPP, OC, and ON interactions with other matrix-specific macromolecules (i.e., amelogenin, dentin matrix protein-1) and/or to the polarized organization of odontoblast secretion as compared with osteoblasts.
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Affiliation(s)
- P Papagerakis
- Laboratoire de Biologie-Odontologie, Université Paris VII, Paris, France.
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Dowd TL, Rosen JF, Mints L, Gundberg CM. The effect of Pb(2+) on the structure and hydroxyapatite binding properties of osteocalcin. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1535:153-63. [PMID: 11342004 DOI: 10.1016/s0925-4439(00)00094-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Lead toxicity is a major environmental health problem in the United States. Bone is the major reservoir for body lead. Although lead has been shown to impair bone metabolism in animals and at the cellular level, the effect of Pb(2+) at the molecular level is largely unknown. We have used circular dichroism (CD), and a hydroxyapatite binding assay to investigate the effect of Pb(2+) on the structure and mineral binding properties of osteocalcin, a noncollagenous bone protein. The CD data indicate Pb(2+) induces a similar structure in osteocalcin as Ca(2+) but at 2 orders of magnitude lower concentration. These results were explained by the more than 4 orders of magnitude tighter binding of Pb(2+) to osteocalcin (K(d)=0.085 microM) than Ca(2+) (K(d)=1.25 mM). The hydroxyapatite binding assays show that Pb(2+) causes an increased adsorption to hydroxyapatite, similar to Ca(2+), but at 2-3 orders of magnitude lower concentration. Low Pb(2+) levels (1 microM) in addition to physiological Ca(2+) levels (1 mM) caused a significant (40%) increase in the amount of mineral bound osteocalcin as compared to 1 mM Ca(2+) alone. These results suggest a molecular mechanism of Pb(2+) toxicity where low Pb(2+) levels can inappropriately perturb Ca(2+) regulated processes. In-vivo, the increased mineral bound osteocalcin could play a role in the observed low bone formation rates and decreased bone density observed in Pb(2+)-intoxicated animals.
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Affiliation(s)
- T L Dowd
- Department of Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY 10467, USA.
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Patterson-Buckendahl P, Rusnák M, Fukuhara K, Kvetnanský R. Repeated immobilization stress reduces rat vertebral bone growth and osteocalcin. Am J Physiol Regul Integr Comp Physiol 2001; 280:R79-86. [PMID: 11124137 DOI: 10.1152/ajpregu.2001.280.1.r79] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We previously showed that psychological stressors alter plasma levels of osteocalcin (pOC), a bone-specific mineral binding protein, in ways that differ with the type of stressor. To determine effects of chronic stress, we examined vertebrae, pOC, and corticosterone levels from conscious rats subjected to foot-restraint immobilization (Immo) daily for 1-42 times. After 40-42 Immo, basal pOC was decreased by 25% compared with unstressed rats, and the subsequent rise in pOC during Immo was blunted. Corticosterone was elevated 10-fold during Immo. Immo for seven times did not change vertebral OC concentration, but caused a slight decrease in calcium and phosphorous concentrations in younger rats. Rats Immo for 42 times exhibited reduced body weight, vertebral weight, and vertebral OC concentration but no significant differences in vertebral mineral concentrations. Body fat content was visibly decreased. We do not know the source of or the stimulus for the initial rise in pOC. We conclude that both decreased growth and bone OC concentration are due to repeatedly elevated stress hormones.
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Petersen DN, Tkalcevic GT, Mansolf AL, Rivera-Gonzalez R, Brown TA. Identification of osteoblast/osteocyte factor 45 (OF45), a bone-specific cDNA encoding an RGD-containing protein that is highly expressed in osteoblasts and osteocytes. J Biol Chem 2000; 275:36172-80. [PMID: 10967096 DOI: 10.1074/jbc.m003622200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We describe the cloning and characterization of a novel bone-specific cDNA predicted to encode an extracellular matrix protein. This cDNA was identified by subtractive hybridization based upon its high expression in bone marrow-derived osteoblasts. By Northern blot analysis, we detected a single 2-kilobase mRNA transcript in bone, whereas no expression was detected in other tissues. Immunohistochemistry revealed that the protein was expressed highly in osteocytes within trabecular and cortical bone. RNA and protein expression analysis using in vivo marrow ablation as a model of bone remodeling demonstrated that this gene was expressed only in cells that were embedded within bone matrix in contrast to the earlier expression of known osteoblast markers. The cDNA was predicted to encode a serine/glycine-rich secreted peptide containing numerous potential phosphorylation sites and one RGD sequence motif. The interaction of RGD domain-containing peptides with integrins has been shown previously to regulate bone remodeling by promoting recruitment, attachment, and differentiation of osteoblasts and osteoclasts. Secretion of this RGD-containing protein from osteocytes has the potential to regulate cellular activities within the bone environment and thereby may impact bone homeostasis. We propose the name OF45 (osteoblast/osteocyte factor of 45 kDa) for this novel cDNA.
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Affiliation(s)
- D N Petersen
- Department of Cardiovascular & Metabolic Diseases, Global Research and Development, Pfizer, Inc., Groton, Connecticut 06340, USA
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Koyama H, Nakade O, Saitoh T, Takuma T, Kaku T. Evidence for the involvement of bone morphogenetic protein-2 in phenytoin-stimulated osteocalcin secretion in human bone cells. Arch Oral Biol 2000; 45:647-55. [PMID: 10869476 DOI: 10.1016/s0003-9969(00)00036-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Recent work has shown that the actions of phenytoin on bone cell proliferation and differentiation are, in part, mediated through the upregulation of transforming growth factor-beta1 (TGF-beta(1)). The present study was undertaken to examine the effect of phenytoin on bone morphogenetic proteins (BMP)-2 and -4, which are well-recognized osteoinductive proteins of the TGF-beta superfamily, in osteoblastic cells. Treatment with 5-50 microM of phenytoin increased the amount of mRNA for BMP-2 after a 0.5-24 h incubation in normal human mandible-derived bone cells (HOB-M cells), but failed to affect the mRNA for BMP-4. Phenytoin treatment for 48 h significantly increased the secretion of BMP-2 by approx. four-fold, at an optimal concentration of 10 microM. While TGF-beta(1) inhibited osteocalcin secretion from HOB-M cells, both phenytoin and BMP-2 significantly stimulated it. Importantly, the stimulatory effects of phenytoin on osteocalcin release were completely blocked by the neutralizing antihuman BMP-2 monoclonal antibody. These results indicate that the stimulatory action of phenytoin on osteocalcin secretion in normal human bone cells is mediated, at least partly, through the upregulation of BMP-2, rather than that of TGF-beta(1).
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Affiliation(s)
- H Koyama
- Department of Oral Pathology, School of Dentistry, Health Sciences University of Hokkaido, 061-0293, Ishikari-Tobetsu, Japan
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Abstract
Previous findings have shown that osteoblasts respond to parathyroid hormone (PTH) with an increase in extracellular acidification rate (ECAR) in addition to the known effect of PTH to increase local acidification by osteoclasts. We, therefore, investigated use of the Cytosensor to measure the ECAR response of whole intact bone to PTH employing microphysiometry. The Cytosensor measures a generic metabolic increase of cells to various agents. Using neonatal mouse calvaria, we found that the area surrounding the sagittal suture was particularly responsive to PTH. In this bone, the increase in ECAR was slower to develop (6 minutes) and more persistent than in cultured human osteoblast-like SaOS-2 cells and was preceded by a brief decrease in ECAR. Salmon calcitonin also produced an increase in ECAR in this tissue but with a different pattern than that elicited by PTH. Because PTH stimulates osteoclastic bone resorption in mouse calvaria via a cyclic adenosine monophosphate (cAMP)-mediated mechanism, we showed that the adenylyl cyclase activator forskolin also stimulated ECAR in this tissue. When the protein kinase A (PKA) pathway was activated by maintaining a high intracellular concentration of cAMP using N6-2'-0-dibutyryladenosine-cAMP (db-cAMP), there was a reduction of PTH-induced acidification, while isobutylmethylxanthine pretreatment potentiated the PTH-induced acidification, consistent with a PKA-mediated pathway. Thapsigargin and the protein kinase C (PKC) activator phorbol myristate acetate had no effect on the PTH-induced increase in ECAR in calvaria, indicating that PKC does not play a major role in the ECAR response in intact bone. These results indicate the utility of using microphysiometry to study ECAR responses in intact tissue and should enable elucidation of the relative importance of extracellular acidification by osteoblasts and osteoclasts to the anabolic and catabolic activities of PTH, respectively.
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Affiliation(s)
- G S Belinsky
- Department of Cancer Cell Biology, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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