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Abstract
In addition to its structural role, the skeleton serves as an endocrine organ that controls mineral metabolism and energy homeostasis. Three major cell types in bone - osteoblasts, osteoclasts, and osteocytes - dynamically form and maintain bone and secrete factors with systemic activity. Osteocalcin, an osteoblast-derived factor initially described as a matrix protein that regulates bone mineralization, has been suggested to be an osteoblast-derived endocrine hormone that regulates multiple target organs including pancreas, liver, muscle, adipose, testes, and the central and peripheral nervous system. Sclerostin is predominantly produced by osteocytes, and is best known as a paracrine-acting regulator of WNT signaling and activity of osteoblasts and osteoclasts on bone surfaces. In addition to this important paracrine role for sclerostin within bone, sclerostin protein has been noted to act at a distance to regulate adipocytes, energy homeostasis, and mineral metabolism in the kidney. In this article, we aim to bring together evidence supporting an endocrine function for sclerostin and osteocalcin, and discuss recent controversies regarding the proposed role of osteocalcin outside of bone. We summarize the current state of knowledge on animal models and human physiology related to the multiple functions of these bone-derived factors. Finally, we highlight areas in which future research is expected to yield additional insights into the biology of osteocalcin and sclerostin.
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Affiliation(s)
- Jialiang S. Wang
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Courtney M. Mazur
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Marc N. Wein
- Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
- Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA, United States
- Harvard Stem Cell Institute, Cambridge, MA, United States
- *Correspondence: Marc N. Wein,
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Otani T, Mizokami A, Kawakubo-Yasukochi T, Takeuchi H, Inai T, Hirata M. The roles of osteocalcin in lipid metabolism in adipose tissue and liver. Adv Biol Regul 2020; 78:100752. [PMID: 32992234 DOI: 10.1016/j.jbior.2020.100752] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/08/2020] [Indexed: 06/11/2023]
Abstract
Bone provides skeletal support and functions as an endocrine organ by producing osteocalcin, whose uncarboxylated form (GluOC) increases the metabolism of glucose and lipid by activating its putative G protein-coupled receptor (family C group 6 subtype A). Low doses (≤10 ng/ml) of GluOC induce the expression of adiponectin, adipose triglyceride lipase and peroxisome proliferator-activated receptor γ, and promote active phosphorylation of lipolytic enzymes such as perilipin and hormone-sensitive lipase via the cAMP-PKA-Src-Rap1-ERK-CREB signaling axis in 3T3-L1 adipocytes. Administration of high-dose (≥20 ng/ml) GluOC induces programmed necrosis (necroptosis) through a juxtacrine mechanism triggered by the binding of Fas ligand, whose expression is induced by forkhead box O1, to Fas that is expressed in adjacent adipocytes. Furthermore, expression of adiponectin and adipose triglyceride lipase in adipocytes is triggered in the same manner as following low-dose GluOC stimulation; these effects protect mice from diet-induced accumulation of triglycerides in hepatocytes and consequent liver injury through the upregulation of nuclear translocation of nuclear factor-E2-related factor-2, expression of antioxidant enzymes, and inhibition of the c-Jun N-terminal kinase pathway. Evaluation of these molecular mechanisms leads us to consider that GluOC might have potential as a treatment for lipid metabolism disorders. Indeed, there have been many reports demonstrating the negative correlation between serum osteocalcin levels and obesity or non-alcoholic fatty liver disease, a common risk factor for which is dyslipidemia in humans. The present review summarizes the effects of GluOC on lipid metabolism as well as its possible therapeutic application for metabolic diseases including obesity and dyslipidemia.
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Affiliation(s)
- Takahito Otani
- Division of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan
| | - Akiko Mizokami
- OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, 812-8582, Japan
| | | | - Hiroshi Takeuchi
- Division of Applied Pharmacology, Kyushu Dental University, Kitakyushu, 803-8580, Japan
| | - Tetsuichiro Inai
- Division of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan; Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, 814-0193, Japan
| | - Masato Hirata
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, 814-0193, Japan.
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Abstract
This study presents an investigation into the role of Osteocalcin (OC) on bone biomechanics, with the results demonstrating that the protein's α-helix structures play a critical role in energy dissipation behavior in healthy conditions. In the first instance, α-helix structures have high affinity with the Hydroxyapatite (HAp) mineral surface and provide favorable conditions for adsorption of OC proteins onto the mineral surface. Using steered molecular dynamics simulation, several key energy dissipation mechanisms associated with α-helix structures were observed, which included stick-slip behavior, a sacrificial bond mechanism and a favorable binding feature provided by the Ca2+ motif on the OC protein. In the case of Type-2 Diabetes, this study demonstrated that possible glycation of the OC protein can occur through covalent crosslinking between Arginine and N-terminus regions, causing disruption of α-helices leading to a lower protein affinity to the HAp surface. Furthermore, the loss of α-helix structures allowed protein deformation to occur more easily during pulling and key energy dissipation mechanisms observed in the healthy configuration were no longer present. This study has significant implications for our understanding of bone biomechanics, revealing several novel mechanisms in OC's involvement in energy dissipation. Furthermore, these mechanisms can be disrupted following the onset of Type-2 Diabetes, implying that glycation of OC could have a substantial contribution to the increased bone fragility observed during this disease state.
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Affiliation(s)
- Mahdi Tavakol
- Biomedical Engineering and Biomechanics Research Centre, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland
| | - Ted J Vaughan
- Biomedical Engineering and Biomechanics Research Centre, School of Engineering, College of Science and Engineering, National University of Ireland Galway, Galway, Ireland.
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Tian A, Yang C, Jin Z. Osteocalcin in acute stress response: from the perspective of cardiac diseases. Curr Med Res Opin 2020; 36:545-546. [PMID: 31990218 DOI: 10.1080/03007995.2020.1723073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Osteocalcin is an osteoblast-derived peptide mainly found in the bone matrix but also in circulation. A recent investigation suggested that osteocalcin mediated acute stress response (ASR) by inhibiting parasympathetic tone in mice and humans. We propose a hypothesis that osteocalcin is regulated by the skeleton movement and glucocorticoids, and inhibition of the parasympathetic tone by osteocalcin may indicate a therapeutic target in the treatment of acute myocardial infarction (AMI).
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Affiliation(s)
- Aiju Tian
- Department of Cardiology, Beijing Geriatric Hospital, Beijing, China
| | - Chengzhi Yang
- Department of Cardiology and Macrovascular Disease, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Zening Jin
- Department of Cardiology and Macrovascular Disease, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
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Millar SA, John SG, McIntyre CW, Ralevic V, Anderson SI, O'Sullivan SE. An Investigation Into the Role of Osteocalcin in Human Arterial Smooth Muscle Cell Calcification. Front Endocrinol (Lausanne) 2020; 11:369. [PMID: 32587575 PMCID: PMC7298126 DOI: 10.3389/fendo.2020.00369] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/11/2020] [Indexed: 12/30/2022] Open
Abstract
Osteocalcin (OCN) is a bone-derived protein that is detected within human calcified vascular tissue. Calcification is particularly prevalent in chronic kidney disease (CKD) patients but the role of OCN in calcification, whether active or passive, has not been elucidated. Part 1: The relationship between OCN, CKD and vascular calcification was assessed in CKD patients (n = 28) and age-matched controls (n = 19). Part 2: in vitro, we analyzed whether addition of uncarboxylated osteocalcin (ucOCN) influenced the rate or extent of vascular smooth muscle cell (VSMC) calcification. Human aortic VSMCs were cultured in control media or mineralisation inducing media (MM) containing increased phosphate with or without ucOCN (10 or 30 ng/mL) for up to 21 days. Markers of osteogenic differentiation and calcification were determined [alkaline phosphatase (ALP) activity, total intracellular OCN, Runx2 expression, α-SMA expression, alizarin red calcium staining, and calcium quantification]. Part 1 results: In our human population, calcification was present (mean age 76 years), but no differences were detected between CKD patients and controls. Plasma total OCN was increased in CKD patients compared to controls (14 vs. 9 ng/mL; p < 0.05) and correlated to estimated glomerular filtration rate (p < 0.05), however no relationship was detected between total OCN and calcification. Part 2 results: in vitro, ALP activity, α-SMA expression and calcium concentrations were significantly increased in MM treated VSMCs at day 21, but no effect of ucOCN was observed. Cells treated with control media+ucOCN for 21 days did not show increases in ALP activity nor calcification. In summary, although plasma total OCN was increased in CKD patients, this study did not find a relationship between OCN and calcification in CKD and non-CKD patients, and found no in vitro evidence of an active role of ucOCN in vascular calcification as assessed over 21 days. ucOCN appears not to be a mediator of vascular calcification, but further investigation is warranted.
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Affiliation(s)
- Sophie A. Millar
- Division of Medical Sciences & Graduate Entry Medicine, School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, United Kingdom
- *Correspondence: Sophie A. Millar
| | - Stephen G. John
- Department of Renal Medicine, Royal Derby Hospital, Derby, United Kingdom
| | - Christopher W. McIntyre
- Department of Renal Medicine, Royal Derby Hospital, Derby, United Kingdom
- London Health Sciences Centre, London, ON, Canada
| | - Vera Ralevic
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Susan I. Anderson
- Division of Medical Sciences & Graduate Entry Medicine, School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, United Kingdom
| | - Saoirse E. O'Sullivan
- Division of Medical Sciences & Graduate Entry Medicine, School of Medicine, Royal Derby Hospital, University of Nottingham, Derby, United Kingdom
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Marsot C, Chanson P, Borson-Chazot F. [Bone and metabolism]. Ann Endocrinol (Paris) 2018; 79 Suppl 1:S40-S47. [PMID: 30213304 DOI: 10.1016/s0003-4266(18)31236-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Bone is now considered as a particular endocrine organ. Its endocrine function is not yet fully understood and has been the subject of several conferences at the European Society of Endocrinology Congress 2018. Bone regulates phosphate metabolism by secreting fibroblast growth factor 23; it also regulates glucose metabolism via osteocalcin and energy metabolism, thanks to lipocalin 2, a new hormone acting on the brain. In addition, the incidence of diabetes continues to grow, and its impact on bone has been demonstrated, with an increased risk of fractures regardless the type of diabetes. The mechanism of bone fragility in this disease is not fully known but it involves a decrease in bone turnover and bone demineralization. Recent findings on the role of bone on glucose and mineral metabolism could open therapeutic perspectives, especially for the treatment of diabetes or obesity.
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Affiliation(s)
- Charlotte Marsot
- Fédération d'endocrinologie, diabétologie et maladies métaboliques, hôpital Louis-Pradel, 59, boulevard Pinel, 69500 Bron, France.
| | - Philippe Chanson
- Service d'endocrinologie, diabétologie, métabolisme et nutrition, hôpital Bicêtre, 78, rue du Général-Leclerc, 94270 Le Kremlin-Bicêtre, France
| | - Françoise Borson-Chazot
- Fédération d'endocrinologie, diabétologie et maladies métaboliques, hôpital Louis-Pradel, 59, boulevard Pinel, 69500 Bron, France
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Abstract
The emergence of the endochondral skeleton in terrestrial animals enabled ambulation against increased gravitational forces and provided a storage site for scarce minerals essential for life. This skeletal upgrade increased overall fuel requirements and altered global energy balance, prompting the evolution of endocrine networks to coordinate energy expenditure. Bone-forming osteoblasts require a large and constant supply of energy substrates to fuel bone matrix production and mineralization. When fuel demands are unmet, bone quality and strength are compromised. Recent studies suggest that key developmental signaling pathways are coupled to bioenergetic programs, accommodating changes in energy requirements at different stages of the osteoblast life cycle. Studies in genetically altered mice have confirmed a link between bone cells and global metabolism and have led to the identification of hormonal interactions between the skeleton and other tissues. These observations have prompted new questions regarding the nature of the mechanisms of fuel sensing and processing in the osteoblast and their contribution to overall energy utilization and homeostasis. Answers to such questions should advance our understanding of metabolic diseases and may ultimately improve treatments for patients with diabetes and osteoporosis.
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Levinger I, Brennan-Speranza TC, Zulli A, Parker L, Lin X, Lewis JR, Yeap BB. Multifaceted interaction of bone, muscle, lifestyle interventions and metabolic and cardiovascular disease: role of osteocalcin. Osteoporos Int 2017; 28:2265-2273. [PMID: 28289780 DOI: 10.1007/s00198-017-3994-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/28/2017] [Indexed: 12/22/2022]
Abstract
Undercarboxylated osteocalcin (ucOC) may play a role in glucose homeostasis and cardiometabolic health. This review examines the epidemiological and interventional evidence associating osteocalcin (OC) and ucOC with metabolic risk and cardiovascular disease. The complexity in assessing such correlations, due to the observational nature of human studies, is discussed. Several studies have reported that higher levels of ucOC and OC are correlated with lower fat mass and HbA1c. In addition, improved measures of glycaemic control via pharmacological and non-pharmacological (e.g. exercise or diet) interventions are often associated with increased circulating levels of OC and/or ucOC. There is also a relationship between lower circulating OC and ucOC and increased measures of vascular calcification and cardiovascular disease. However, not all studies have reported such relationship, some with contradictory findings. Equivocal findings may arise because of the observational nature of the studies and the inability to directly assess the relationship between OC and ucOC on glycaemic control and cardiovascular health in humans. Studying OC and ucOC in humans is further complicated due to numerous confounding factors such as sex differences, menopausal status, vitamin K status, physical activity level, body mass index, insulin sensitivity (normal/insulin resistance/T2DM), tissue-specific effects and renal function among others. Current observational and indirect interventional evidence appears to support a relationship between ucOC with metabolic and cardiovascular disease. There is also emerging evidence to suggest a direct role of ucOC in human metabolism. Further mechanistic studies are required to (a) clarify causality, (b) explore mechanisms involved and
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Affiliation(s)
- I Levinger
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia.
| | - T C Brennan-Speranza
- Department of Physiology and Bosch Institute for Medical Research, University of Sydney, Sydney, Australia
| | - A Zulli
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia
| | - L Parker
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia
| | - X Lin
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia
| | - J R Lewis
- Centre for Kidney Research, Children's Hospital at Westmead School of Public Health, Sydney Medical School, The University of Sydney, Sydney, Australia
- School of Medicine and Pharmacology, University of Western Australia, Perth, Australia
| | - B B Yeap
- School of Medicine and Pharmacology, University of Western Australia, Perth, Australia
- Department of Endocrinology and Diabetes, Fiona Stanley Hospital, Perth, Australia
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Zhang YY, Huang YP, Zhao HX, Zhang T, Chen F, Liu Y. Cementogenesis is inhibited under a mechanical static compressive force via Piezo1. Angle Orthod 2017; 87:618-624. [PMID: 28418701 DOI: 10.2319/110616-799.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To investigate whether Piezo1, a mechanotransduction gene mediates the cementogenic activity of cementoblasts under a static mechanical compressive force. MATERIALS AND METHODS Murine cementoblasts (OCCM-30) were exposed to a 2.0 g/cm2 static compressive force for 3, 6, 12, and 24 hours. Then the expression profile of Piezo1 and the cementogenic activity markers osteoprotegerin (Opg), osteopontin (Opn), osteocalcin (Oc), and protein tyrosine phosphataselike member A (Ptpla) were analyzed. Opg, Opn, Oc, and Ptpla expression was further measured after using siRNA to knock down Piezo1. Real-time PCR, Western blot, and cell proliferation assays were performed according to standard procedures. RESULTS After mechanical stimulation, cell morphology and proliferation did not change significantly. The expression of Piezo1, Opg, Opn, Oc, and Ptpla was significantly decreased, with a high positive correlation between Opg and Piezo1 expression. After Piezo1 knockdown, the expression of Opg, Opn, Oc, and Ptpla was further decreased under mechanical stimulation. CONCLUSIONS Cementogenic activity was inhibited in OCCM-30 cells under static mechanical force, a process that was partially mediated by the decrease of Piezo1. This study provides a new viewpoint of the pathogenesis mechanism of orthodontically induced root resorption and repair.
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Golovkin AS, Kokov AN, Masenko V, Khryachkova ON, Malyuta Е, Barbarash OL. Markers of calcium and phosphate metabolism and osteopenic syndrome in patients with coronary artery disease. Panminerva Med 2016; 58:253-262. [PMID: 27271452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The aim of the present study is to assess the level of specific markers of calcium and phosphate metabolism in the development of coronary atherosclerosis in patients with stable coronary artery disease, depending on the severity of osteopenic syndrome. METHODSː In the study 112 male patients aged from 49 to 73 years with verified coronary artery disease were included in the study. Calcium Score was measured using the Agatston Score. Besides, all of them were tested on the serum level of parathyroid hormone, calcitonin, osteocalcin, bone-specific alkaline phosphatase, osteoprotegerin, osteopontin, cathepsin K, estradiol and testosterone. RESULTSː The distribution of patients according to the severity of coronary atherosclerosis using the Syntax Score suggested that the levels of the studied markers did not differ significantly among the patients, despite significant differences in the severity of coronary artery disease. The levels of osteoprotegerin in patients with mild, moderate and severe calcification were significantly lower compared to patients with a zero calcium score. There were no clinical manifestations of osteopenic syndrome in all patients. However, they underwent osteodensitometry with measurement of bone mineral density at the lumbar spine and femoral neck to determine pre-clinical symptoms of bone destruction. Significant increase (P=0.03) in serum levels of osteocalcin was found in patients with radiological evidence of osteoporosis while the other markers did no differ significantly. CONCLUSIONSː We suppose that there is a reciprocal interaction of regulatory vectors with increased calcium deposition in the arterial wall and resorption of bone tissue.
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Affiliation(s)
- Alexey S Golovkin
- Federal State Budgetary Institution "Research Institute for Complex Issues of Cardiovascular Disease", Kemerovo, Russia -
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Gao J, Bai T, Ren L, Ding Y, Zhong X, Wang H, Guo Y, Li J, Liu Y, Zhang Y. The PLC/PKC/Ras/MEK/Kv channel pathway is involved in uncarboxylated osteocalcin-regulated insulin secretion in rats. Peptides 2016; 86:72-79. [PMID: 27746193 DOI: 10.1016/j.peptides.2016.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 09/22/2016] [Accepted: 10/10/2016] [Indexed: 12/11/2022]
Abstract
Uncarboxylated osteocalcin, a bone matrix protein, has been proposed to regulate glucose metabolism by increasing insulin secretion, improving insulin sensitivity and stimulating β cell proliferation. Our previous study also indicated that uncarboxylated osteocalcin stimulates insulin secretion by inhibiting voltage-gated potassium (KV) channels. The goal of this study is to further investigate the underlying mechanisms for the regulation of Kv channels and insulin secretion by uncarboxylated osteocalcin. Insulin secretion and Kv channel currents were examined by radioimmunoassay and patch-clamp technique, respectively. Calcium imaging system was applied to measure intracellular Ca2+ concentration ([Ca2+]i). The protein levels were detected by western blot. The results showed that uncarboxylated osteocalcin potentiated insulin secretion, inhibited Kv channels and increased [Ca2+]i compared to control. These effects were suppressed by phospholipase-C (PLC)/protein kinase C (PKC)/Ras/MAPK-ERK kinase (MEK) signaling pathway, indicating that this signaling pathway plays an important role in uncarboxylated osteocalcin-regulated insulinotropic effect. In addition, the results also showed that adenylyl cyclase (AC) did not influence the effect of uncarboxylated osteocalcin on insulin secretion and Kv channels, suggesting that AC is not involved in uncarboxylated osteocalcin-stimulated insulin secretion. These findings provide new insight into the mechanism of uncarboxylated osteocalcin-regulated insulin secretion.
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Affiliation(s)
- Jingying Gao
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China; Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China; Department of Pediatrics, Shanxi Medical University, Taiyuan, China
| | - Tao Bai
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China; Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China; Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China
| | - Lele Ren
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yaqin Ding
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Xiangqin Zhong
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Hui Wang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yangyan Guo
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Jie Li
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China
| | - Yunfeng Liu
- Department of Endocrinology, the First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, China.
| | - Yi Zhang
- Department of Pharmacology, Shanxi Medical University, Taiyuan, China; Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China.
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Confavreux CB, Casey R, Varennes A, Goudable J, Chapurlat RD, Szulc P. Has sclerostin a true endocrine metabolic action complementary to osteocalcin in older men? Osteoporos Int 2016; 27:2301-2309. [PMID: 27007475 DOI: 10.1007/s00198-016-3540-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 02/11/2016] [Indexed: 01/27/2023]
Abstract
UNLABELLED The reported association between sclerostin and diabetes mellitus or abdominal fat may be biased by body size and bone mass. In older men, the association between serum sclerostin levels and metabolic syndrome lost significance after adjustment for bone mass. The association between sclerostin and energy metabolism needs further clarification. INTRODUCTION Sclerostin is associated with abdominal fat, but this relationship may be biased since both are associated with body size and bone mass. Osteocalcin is a bone-derived hormone regulating energy metabolism. We assessed the association between serum sclerostin and metabolic syndrome (MetS) accounting for whole body mineral content (BMC) and osteocalcin. METHODS We studied 694 men aged 51-85 who had serum osteocalcin and sclerostin measurements. RESULTS Sclerostin was higher in 216 men with MetS compared with those without MetS (p < 0.005). Average sclerostin level increased significantly across the increasing number of MetS components. In multivariable models, higher sclerostin was associated with higher odds of MetS (odds ratio (OR) = 1.24/1 standard deviation (SD) increase [95 % confidence interval (95 % CI), 1.01-1.51]; p < 0.05). After further adjustment for BMC, the association of MetS with sclerostin lost significance, whereas that with osteocalcin remained significant. Men who were simultaneously in the highest sclerostin quartile and the lowest osteocalcin quartile had higher odds of MetS (OR = 2.14 [95 % CI, 1.15-4.18]; p < 0.05) vs. men being in the three lower sclerostin quartiles and three upper osteocalcin quartiles. After adjustment for whole body BMC, the association lost significance. CONCLUSIONS Higher sclerostin level is associated with MetS severity; however, this association may be related to higher whole body BMC. The adjustment for BMC had no impact on the association between MetS and osteocalcin. Clinical cross-sectional studies do not elucidate the potential role of sclerostin in the regulation of energy metabolism and direct experimental approach is necessary.
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Affiliation(s)
- C B Confavreux
- INSERM UMR1033 - Université de Lyon, Department of Rheumatology, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, 69003, France.
| | - R Casey
- OFSEP-Université de Lyon, Hospices Civils de Lyon, Lyon, 69003, France
| | - A Varennes
- Université de Lyon, Central Biochemical Laboratory, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, 69003, France
| | - J Goudable
- INSERM UMR1060 - Université de Lyon, Lyon, France
| | - R D Chapurlat
- INSERM UMR1033 - Université de Lyon, Department of Rheumatology, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, 69003, France
| | - P Szulc
- INSERM UMR1033 - Université de Lyon, Department of Rheumatology, Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, 69003, France
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Namkoong B, Güven S, Ramesan S, Liaudanskaya V, Abzhanov A, Demirci U. Recapitulating cranial osteogenesis with neural crest cells in 3-D microenvironments. Acta Biomater 2016; 31:301-311. [PMID: 26675129 DOI: 10.1016/j.actbio.2015.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 11/11/2015] [Accepted: 12/02/2015] [Indexed: 01/20/2023]
Abstract
The experimental systems that recapitulate the complexity of native tissues and enable precise control over the microenvironment are becoming essential for the pre-clinical tests of therapeutics and tissue engineering. Here, we described a strategy to develop an in vitro platform to study the developmental biology of craniofacial osteogenesis. In this study, we directly osteo-differentiated cranial neural crest cells (CNCCs) in a 3-D in vitro bioengineered microenvironment. Cells were encapsulated in the gelatin-based photo-crosslinkable hydrogel and cultured up to three weeks. We demonstrated that this platform allows efficient differentiation of p75 positive CNCCs to cells expressing osteogenic markers corresponding to the sequential developmental phases of intramembranous ossification. During the course of culture, we observed a decrease in the expression of early osteogenic marker Runx2, while the other mature osteoblast and osteocyte markers such as Osterix, Osteocalcin, Osteopontin and Bone sialoprotein increased. We analyzed the ossification of the secreted matrix with alkaline phosphatase and quantified the newly secreted hydroxyapatite. The Field Emission Scanning Electron Microscope (FESEM) images of the bioengineered hydrogel constructs revealed the native-like osteocytes, mature osteoblasts, and cranial bone tissue morphologies with canaliculus-like intercellular connections. This platform provides a broadly applicable model system to potentially study diseases involving primarily embryonic craniofacial bone disorders, where direct diagnosis and adequate animal disease models are limited.
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Affiliation(s)
- Bumjin Namkoong
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Sinan Güven
- Demirci BAMM Labs, Canary Center at Stanford for Early Cancer Detection, Department of Radiology, Department of Electrical Engineering (By courtesy), Stanford School of Medicine, Palo Alto, CA 94304, USA; Izmir Biomedicine and Genome Center, Dokuz Eylul University Health Campus, Balcova, 35350 Izmir, Turkey
| | - Shwathy Ramesan
- Demirci BAMM Labs, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Volha Liaudanskaya
- Demirci BAMM Labs, Canary Center at Stanford for Early Cancer Detection, Department of Radiology, Department of Electrical Engineering (By courtesy), Stanford School of Medicine, Palo Alto, CA 94304, USA
| | - Arhat Abzhanov
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Current address: Department of Life Sciences, Imperial College London, Silwood Park Campus Buckhurst Road, Ascot, Berkshire SL5 7PY, United Kingdom; Current address: Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom.
| | - Utkan Demirci
- Demirci BAMM Labs, Canary Center at Stanford for Early Cancer Detection, Department of Radiology, Department of Electrical Engineering (By courtesy), Stanford School of Medicine, Palo Alto, CA 94304, USA; Demirci BAMM Labs, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Affiliation(s)
- Elizabeth A Streeten
- Divisions of Endocrinology, Diabetes & Nutrition and Genetics, University of Maryland School of Medicine, Baltimore, MD, USA,
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Abstract
A recent unexpected development of bone biology is that bone is an endocrine organ regulating a growing number of physiological processes. One of the functions regulated by bone through the hormone osteocalcin is glucose homeostasis. In this overview, we will explain why we hypothesized that bone mass and energy metabolism should be subjected to a coordinated endocrine regulation. We will then review the experiments that revealed the endocrine function of osteocalcin and the cell biology events that allow osteocalcin to become a hormone. We will also illustrate the importance of this regulation to understand whole-body glucose homeostasis in the physiological state and in pathological conditions. Lastly, we will mention epidemiological and genetic evidence demonstrating that this function of osteocalcin is conserved in humans.
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Affiliation(s)
- Jianwen Wei
- Department of Genetics & Development, College of Physicians and Surgeons, Columbia University, 701W 168th Street, Room 1602A HHSC, New York, New York, 10032, USA
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Abstract
A recent unexpected development of bone biology is that bone is an endocrine organ contributing to the regulation of a number of physiological processes. One of the functions regulated by bone through osteocalcin, an osteoblast specific hormone, is glucose homeostasis. In this overview, we explain the rationale why we hypothesized that there should be a coordinated endocrine regulation between bone mass and energy metabolism. We then review the experiments that identified the endocrine function of osteocalcin and the cell biology events that allow osteocalcin to become a hormone. We also demonstrate the importance of this regulation to understand whole-body glucose homeostasis in the physiological state and in pathological conditions. Lastly we discuss the epidemiological and genetic evidence demonstrating that this function of osteocalcin is conserved in humans.
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Jürimäe J, Lätt E, Mäestu J, Saar M, Purge P, Maasalu K, Jürimäe T. Osteocalcin is inversely associated with adiposity and leptin in adolescent boys. J Pediatr Endocrinol Metab 2015; 28:571-7. [PMID: 25741787 DOI: 10.1515/jpem-2014-0432] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 01/29/2015] [Indexed: 11/15/2022]
Abstract
BACKGROUND/AIMS Recently, osteocalcin (OC), an osteoblast-derived hormone, has been found to correlate with adiposity, adipocytokines and insulin resistance in adults, but few studies have investigated this in children. The aim of this study was to investigate these associations in adolescent boys, for whom it is a time of significant bone mineral accrual, taking into account possible confounders related to adipose and bone tissues. PARTICIPANTS/METHODS Participants were 141 adolescent boys (mean age 13.9±0.7 years), who were divided into tertiles according to OC levels. Across these groups, differences in total body fat mass (FM), body fat distribution, adiponectin, leptin and insulin resistance values were examined with relation to age, pubertal stage, daily energy and calcium intakes, and physical activity. RESULTS Mean body mass index (BMI), FM, body fat% and leptin differed significantly between subjects in the three OC tertiles after adjustment for age, pubertal stage, energy and calcium intakes, and physical activity. There were no differences in fat free mass (FFM), bone mineral content, energy and calcium intakes, physical activity, adiponectin and insulin resistance values between study groups. For the entire cohort, mean serum OC was 130.2±45.2 ng/mL and was related to body mass, BMI, FM, body fat distribution and leptin. Circulating OC was not associated with FFM, daily energy and calcium intakes, physical activity, adiponectin or insulin resistance (insulin, glucose, homeostasis model assessment-insulin resistance) values. CONCLUSIONS In male adolescents, OC is inversely related to body adiposity and leptin values, even after consideration of several factors that may affect bone and adipose tissues.
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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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Ma XY, Chen FQ, Hong H, Lv XJ, Dong M, Wang QY. The Relationship between Serum Osteocalcin Concentration and Glucose and Lipid Metabolism in Patients with Type 2 Diabetes Mellitus – The Role of Osteocalcin in Energy Metabolism. Ann Nutr Metab 2015; 66:110-116. [PMID: 25721846 DOI: 10.1159/000370198] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/26/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND Recent animal studies have found that the osteocalcin secreted by osteoblasts could participate in glucose and lipid metabolism. Our study aimed to investigate the relationship between serum osteocalcin concentration and glucose and lipid metabolism in patients with type 2 diabetes mellitus. METHODS 985 patients with type 2 diabetes were divided into the male group (n = 495) and the postmenopausal female group (n = 490). The average ages were 54.42 ± 10.535 and 64.93 ± 9.277, respectively. We collected the parameters of age, duration, fasting plasma glucose, HbA1c, fasting insulin, fasting C peptide, blood lipid, 25 (OH) VD3, parathyroid hormone (PTH), Alkaline phosphatase (ALP), procollagen type 1 N-terminal propeptide (P1NP), β-C-terminal telopeptide of type I collagen (β-CTx), osteocalcin, HOMA-IR, HOMA-β, body mass index (BMI), and waist-to-hip ratio (WHR). The relationship of osteocalcin and these parameters were analyzed by Pearson/Spearman correlation analysis and stepwise multiple regression analysis. RESULTS Osteocalcin was negatively correlated with HbA1c (p < 0.05) and it was also an independent relevant factor affecting HbA1c in both groups. Osteocalcin was positively correlated with HOMA-β and it was an independent relevant factor affecting HOMA-β in male group (p < 0.01). CONCLUSIONS These findings indicate the association between serum osteocalcin and glucose metabolism and beta cell function. No relationship was found between osteocalcin and insulin resistance and lipid metabolism in type 2 diabetes.
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Abstract
Expanding β-cell mass through β-cell proliferation is considered a potential therapeutic approach to treat β-cell failure in diabetic patients. A necessary step toward achieving this goal is to identify signaling pathways that regulate β-cell proliferation in vivo. Here we show that osteocalcin, a bone-derived hormone, regulates β-cell replication in a cyclin D1-dependent manner by signaling through the Gprc6a receptor expressed in these cells. Accordingly, mice lacking Gprc6a in the β-cell lineage only are glucose intolerant due to an impaired ability to produce insulin. Remarkably, this regulation occurs during both the perinatal peak of β-cell proliferation and in adulthood. Hence, the loss of osteocalcin/Gprc6a signaling has a profound effect on β-cell mass accrual during late pancreas morphogenesis. This study extends the endocrine role of osteocalcin to the developmental period and establishes osteocalcin/Gprc6a signaling as a major regulator of β-cell endowment that can become a potential target for β-cell proliferative therapies.
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Affiliation(s)
- Jianwen Wei
- Department of Genetics & Development, College of Physicians and Surgeons, Columbia University, New York, NY
| | - Timothy Hanna
- Department of Genetics & Development, College of Physicians and Surgeons, Columbia University, New York, NY
| | - Nina Suda
- Department of Genetics & Development, College of Physicians and Surgeons, Columbia University, New York, NY
| | - Gerard Karsenty
- Department of Genetics & Development, College of Physicians and Surgeons, Columbia University, New York, NY
| | - Patricia Ducy
- Department of Pathology & Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY
- Corresponding author: Patricia Ducy,
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21
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Affiliation(s)
- Thomas Bouckenooghe
- Laboratory of Cell Biology, Institute of Life Science, Catholic University of Louvain, Louvain-la-Neuve, Belgium
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22
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Liao M, Guo X, Yu X, Pang G, Zhang S, Li J, Tan A, Gao Y, Yang X, Zhang H, Qin X, Mo L, Lu Z, Wu C, Mo Z. Role of metabolic factors in the association between osteocalcin and testosterone in Chinese men. J Clin Endocrinol Metab 2013; 98:3463-9. [PMID: 23824426 DOI: 10.1210/jc.2013-1805] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Osteocalcin can regulate energy metabolism and increase testosterone production. Although previous studies have shown the positive association between osteocalcin and testosterone, the effect of metabolic factors in the association is unclear. DESIGN AND SETTING Osteocalcin, testosterone, and metabolic factors were accessed in 2400 men aged 20 to 69 years, who participated in the population-based Fangchenggang Area Male Health and Examination Survey in Guangxi province of China from September 2009 to December 2009. MAIN OUTCOME MEASURES Metabolic syndrome was defined based on the updated report of National Cholesterol Education Program Adult Treatment Panel III criteria. Serum total osteocalcin, total testosterone (TT), and sex hormone binding globulin (SHBG) were measured, whereas free testosterone (FT) and bioavailable testosterone (BT) were calculated based on Vermeulen's formula. The multivariable linear regression analysis was used. RESULTS Osteocalcin was positively associated with TT, FT, and BT in the unadjusted model (all P < .001). After adjusting for age, the positive association between osteocalcin and TT remained statistically significant (β = .17, 95% confidence interval = 0.14-0.20) and was not attenuated in each MetS subgroup including hypertriglyceridemia, hyperglycemia, elevated blood pressure, and low high-density lipoprotein cholesterol, while in the group of central obesity (waist circumstance ≥90 cm), the association appeared significantly stronger (β = 0.21, 95% confidence interval = 0.12-0.30). After further adjusting for SHBG, osteocalcin was positively associated with TT, FT, and BT in men with central obesity or men with any two MetS components (all P < .05). CONCLUSIONS Serum total osteocalcin is positively associated with testosterone, which is probably modified by SHBG and central obesity.
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Affiliation(s)
- Ming Liao
- Institute of Urology and Nephrology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, 530021, People's Republic of China
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23
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Abstract
Transgenic overexpression of the Notch1 intracellular domain inhibits osteoblast differentiation and causes osteopenia, and inactivation of Notch1 and Notch2 increases bone volume transiently and induces osteoblastic differentiation. However, the biology of Notch is cell-context-dependent, and consequences of Notch activation in cells of the osteoblastic lineage at various stages of differentiation and in osteocytes have not been defined. For this purpose, Rosa(Notch) mice, where a loxP-flanked STOP cassette placed between the Rosa26 promoter and the NICD coding sequence, were crossed with transgenics expressing the Cre recombinase under the control of the Osterix (Osx), Osteocalcin (Oc), Collagen 1a1 (Col2.3), or Dentin matrix protein1 (Dmp1) promoters. At 1 month, Osx-Cre;Rosa(Notch) and Oc-Cre;Rosa(Notch) mice exhibited osteopenia due to impaired bone formation. In contrast, Col2.3-Cre;Rosa(Notch) and Dmp1-Cre;Rosa(Notch) exhibited increased femoral trabecular bone volume due to a decrease in osteoclast number and eroded surface. In the four lines studied, cortical bone was either not present, was porous, or had the appearance of trabecular bone. Oc-Cre;Rosa(Notch) and Col2.3-Cre;Rosa(Notch) mice exhibited early lethality so that their adult phenotype was not established. At 3 months, Osx-Cre;Rosa(Notch) and Dmp1-Cre;Rosa(Notch) mice displayed increased bone volume, and increased osteoblasts although calcein-demeclocycline labels were diffuse and fragmented, indicating abnormal bone formation. In conclusion, Notch effects in the skeleton are cell-context-dependent. When expressed in immature osteoblasts, Notch arrests their differentiation, causing osteopenia, and when expressed in osteocytes, it causes an initial suppression of bone resorption and increased bone volume, a phenotype that evolves as the mice mature.
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Affiliation(s)
- Ernesto Canalis
- Department of Research, Saint Francis Hospital and Medical Center, 114 Woodland Street, Hartford, CT 06105-1299, USA.
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24
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Hinoi E. [Regulatory mechanism of glycolipid metabolism by bone tissue]. Nihon Yakurigaku Zasshi 2012; 140:96. [PMID: 23136695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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Abstract
It has long been known that sex steroid hormones regulate bone mass accrual. This observation raises the testable hypothesis that bone may in turn regulate the synthesis and secretion of sex steroid hormones in one or both genders. This hypothesis is comprised within a more general hypothesis that bone mass, energy metabolism, and reproduction are regulated coordinately. The identification of osteocalcin as an osteoblast-specific secreted molecule allows us to address this question in molecular terms. This review details how the regulation of male fertility by osteocalcin was unraveled, and how osteocalcin signaling in Leydig cells of the testis occurs. It also discusses the implication of this novel mode of regulation of testosterone synthesis observed in males but not in females.
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Affiliation(s)
- Gerard Karsenty
- Department of Genetics and Development, Columbia University, HHSC 701 West 168th Street, HHSC1602, New York, New York 10032, USA.
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26
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Confavreux CB, Borel O, Lee F, Vaz G, Guyard M, Fadat C, Carlier MC, Chapurlat R, Karsenty G. Osteoid osteoma is an osteocalcinoma affecting glucose metabolism. Osteoporos Int 2012; 23:1645-50. [PMID: 21681611 DOI: 10.1007/s00198-011-1684-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 05/24/2011] [Indexed: 01/25/2023]
Abstract
Osteocalcin is a hormone secreted by osteoblasts, which regulates energy metabolism by increasing β-cell proliferation, insulin secretion, insulin sensitivity, and energy expenditure. This has been demonstrated in mice, but to date, the evidence implicating osteocalcin in the regulation of energy metabolism in humans are indirect. To address this question more directly, we asked whether a benign osteoblastic tumor, such as osteoma osteoid in young adults, may secrete osteocalcin. The study was designed to assess the effect of surgical resection of osteoid osteoma on osteocalcin and blood glucose levels in comparison with patients undergoing knee surgery and healthy volunteers. Blood collections were performed the day of surgery and the following morning after overnight fasting. Patients and controls were recruited in the orthopedic surgery department of New York Presbiterian Hospital, NY-USA and Hospices Civils de Lyon, France. Seven young males were included in the study: two had osteoid osteoma, two underwent knee surgery, and three were healthy volunteers. After resection of the osteoid osteomas, we observed a decrease of osteocalcin by 62% and 30% from the initial levels. Simultaneously, blood glucose increased respectively by 32% and 15%. Bone turnover markers were not affected. This case study shows for the first time that osteocalcin in humans affects blood glucose level. This study also suggests that ostoid osteoma may be considered, at least in part, as an osteocalcinoma.
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Affiliation(s)
- C B Confavreux
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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27
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Jürimäe J, Vaiksaar S, Mäestu J, Purge P, Jürimäe T. Adiponectin and bone metabolism markers in female rowers: eumenorrheic and oral contraceptive users. J Endocrinol Invest 2011; 34:835-9. [PMID: 21169728 DOI: 10.3275/7415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study investigated whether adiponectin, bone formation (osteocalcin) and bone resorption [type I carboxyterminal telopeptide (ICTP)] values are influenced by menstrual cycle phase and oral contraceptive use in female rowers. Twenty-four rowers divided into normally cycling athletes (NOC; no.=15) and athletes taking oral contraceptive pills (OC; no.=9) participated in this study. Fasting blood samples, body composition and aerobic capacity measurements were taken during the follicular (FP) and the luteal (LP) phases of the menstrual cycle. Adiponectin, insulin, glucose, insulin resistance, body composition and aerobic capacity did not fluctuate significantly during menstrual cycle in both groups. Osteocalcin and ICTP were lower (p<0.05) in OC compared with NOC, but did not change significantly across menstrual cycle phases in both groups. Estradiol and progesterone were not related to adiponectin, osteocalcin or ICTP (r<0.147; p>0.05). Adiponectin was correlated (p<0.05) with osteocalcin (r=0.452) and fat free mass (r=0.428), and osteocalcin was related (p<0.05) to insulin (r=-0.413), glucose (r=-0.486) and insulin resistance (r=-0.528). In conclusion, adiponectin was not affected by menstrual cycle phase and OC use in female rowers, while bone metabolism markers were lower in OC compared to NOC groups. Adiponectin and osteocalcin were interrelated and may characterise energy homeostasis in female athletes.
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Affiliation(s)
- J Jürimäe
- Institute of Sport Pedagogy and Coaching Sciences, Centre of Behavioral, Social and Health Sciences, University of Tartu, 18. Ülikooli St, Tartu 50090, Estonia.
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29
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Abstract
Bone remodelling, which maintains bone mass constant during adulthood, is an energy-demanding process. This, together with the observation that the adipocyte-derived hormone leptin is a major inhibitor of bone remodelling, led to the hypothesis that bone cells regulate energy metabolism through an endocrine mechanism. Studies to test this hypothesis identified osteocalcin, a hormone secreted by osteoblasts, as a positive regulator of insulin secretion, insulin resistance and energy expenditure. Remarkably, insulin signalling in osteoblasts is a positive regulator of osteocalcin production and activation via its ability to indirectly enhance bone resorption by osteoclasts. In contrast, leptin is a potent inhibitor of osteocalcin function through its effect on the sympathetic tone. Hence, osteocalcin is part of a complex signalling network between bone and the organs more classically associated with the regulation of energy homeostasis, such as the pancreas and adipose tissue. This review summarises the molecular and cellular bases of the present knowledge on osteocalcin biology and discusses the potential relevance of osteocalcin to human metabolism and pathology.
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Affiliation(s)
- P Ducy
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032, USA.
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Levinger I, Zebaze R, Jerums G, Hare DL, Selig S, Seeman E. The effect of acute exercise on undercarboxylated osteocalcin in obese men. Osteoporos Int 2011; 22:1621-6. [PMID: 20734028 DOI: 10.1007/s00198-010-1370-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Accepted: 08/03/2010] [Indexed: 12/21/2022]
Abstract
SUMMARY The purpose of this study was to examine if the reduction in glucose post-exercise is mediated by undercarboxylated osteocalcin (unOC). Obese men were randomly assigned to do aerobic or power exercises. The change in unOC levels was correlated with the change in glucose levels post-exercise. The reduction in glucose post-acute exercise may be partly related to increased unOC. INTRODUCTION Osteocalcin (OC) in its undercarboxylated (unOC) form may contribute to the regulation of glucose homeostasis. As exercise reduces serum glucose and improves insulin sensitivity in obese individuals and individuals with type 2 diabetes (T2DM), we hypothesised that this benefit was partly mediated by unOC. METHODS Twenty-eight middle-aged (52.4 ± 1.2 years, mean ± SEM), obese (BMI = 32.1 ± 0.9 kg m(-2)) men were randomly assigned to do either 45 min of aerobic (cycling at 75% of VO(2peak)) or power (leg press at 75% of one repetition maximum plus jumping sequence) exercises. Blood samples were taken at baseline and up to 2 h post-exercise. RESULTS At baseline, unOC was negatively correlated with glucose levels (r = -0.53, p = 0.003) and glycosylated haemoglobin (HbA1c) (r = -0.37, p = 0.035). Both aerobic and power exercises reduced serum glucose (from 7.4 ± 1.2 to 5.1 ± 0.5 mmol L(-1), p = 0.01 and 8.5 ± 1.2 to 6.0 ± 0.6 mmol L(-1), p = 0.01, respectively). Aerobic exercise significantly increased OC, unOC and high-molecular-weight adiponectin, while power exercise had a limited effect on OC and unOC. Overall, those with higher baseline glucose and HbA1c had greater reductions in glucose levels after exercise (r = -0.46, p = 0.013 and r = -0.43, p = 0.019, respectively). In a sub-group of obese people with T2DM, the percentage change in unOC levels was correlated with the percentage change in glucose levels post-exercise (r = -0.51, p = 0.038). CONCLUSIONS This study reports that the reduction in serum glucose post-acute exercise (especially aerobic exercise) may be partly related to increased unOC.
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Affiliation(s)
- I Levinger
- Institute for Sport, Exercise and Active Living, School of Sport and Exercise Science, Victoria University, Melbourne, Australia.
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Takeda S. [Control of bone metabolism by central nervous system]. Clin Calcium 2011; 21:691-696. [PMID: 21532118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It has been believed that bone is controlled by local environment through the action of hormone and cytokines, independently of other organs. However, the discovery that leptin regulates bone formation through the central nervous system shed light on a new regulatory system of bone metabolism, i.e., neuronal control. Moreover, recent discovery that osteocalcin regulates glucose metabolism and fertility clearly demonstrated that bone forms a regulatory network of metabolism, together with other organs.
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Affiliation(s)
- Shu Takeda
- Department of Internal Medicine, Keio University, School of Medicine
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32
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Yoshizawa T. [Bone remodeling and glucose/lipid metabolism]. Clin Calcium 2011; 21:709-714. [PMID: 21532121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It has been demonstrated that osteocalcin, osteoblast-derived molecule, regulates glucose/lipid metabolism through increasing insulin secretion from pancreas and insulin sensitivity in peripheral tissues. This finding established that bone is an important endocrine organ to regulate glucose/lipid metabolism. Recently, it has been reported that insulin signaling in osteoblasts was a positive regulator of bone acquisition, but also of bone resorption. Interestingly, insulin signaling in osteoblasts activated osteocalcin embedded in bone ECM by stimulating resorption activity in osteoclast. This finding indicated that the osteoblasts is an important target cells used by insulin which playing a central role in glucose/lipid metabolism. The bone/glucose metabolism interaction established by these studies will be important to a study of the two fields in the future, particularly a clinical field.
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Male fertility is in the bones: first evidence that skeleton plays a role in reproduction. Pak J Biol Sci 2011; 14:308-9. [PMID: 21870635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Abstract
Multiple myeloma (MM) is the most frequent cancer to involve the skeleton and results in purely osteolytic lesions that rarely heal. MM bone disease is responsible for some of the most devastating complications of MM. The marrow microenvironment plays a key role in MM bone disease as well as in the initiation, expansion and chemoresistance of MM cells. How this microenvironment becomes so supportive of MM, and the contribution and interaction of the various components of the microenvironment to enhancing MM growth are only beginning to be understood. However, it is clear that suppression of osteoblast activity plays a key role in the bone destructive process as well as progression of the tumor burden in myeloma. The impairment of osteoblast activity in MM results primarily from blockade of osteogenic differentiation of mesenchymal progenitors to mature osteoblasts. MM patients have low to normal levels of bone formation markers, such as alkaline phosphatase and osteocalcin in the setting of increased bone resorption. In contrast, MM patients without bone lesions display balanced bone remodeling with increased osteoclastogenesis and normal or increased bone formation rates. Both soluble factors and cell-to-cell contact between MM cells and osteoblast progenitors are responsible for the suppression of osteoblast differentiation in MM. In this article, the mechanism responsible for osteoblast suppression will be reviewed, and the effects of novel bone anabolic agents on myeloma bone disease will be discussed.
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Affiliation(s)
- G David Roodman
- Veterans Affairs Pittsburgh Healthcare System, Research and Development, Pittsburgh, Pennsylvania, USA.
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Fernández-Real JM, Ortega F, Gómez-Ambrosi J, Salvador J, Frühbeck G, Ricart W. Circulating osteocalcin concentrations are associated with parameters of liver fat infiltration and increase in parallel to decreased liver enzymes after weight loss. Osteoporos Int 2010; 21:2101-7. [PMID: 20204603 DOI: 10.1007/s00198-010-1174-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 01/04/2010] [Indexed: 01/24/2023]
Abstract
SUMMARY The expression of liver genes was associated with insulin action in osteocalcin knockout mice. Our findings suggest that osteocalcin may play a role in the development of insulin resistance-associated fatty liver disease. INTRODUCTION The expression of insulin target genes was decreased in the liver of mice lacking osteocalcin. We aimed to explore the association of liver enzymes with osteocalcin. METHODS The associations were evaluated in a cross-sectional study (266 men) and following weight loss in 28 obese subjects (nine male, 19 females). RESULTS In the cross-sectional study, circulating osteocalcin concentration was negatively associated with alanine transaminase (ALT) (p = 0.002) and aspartate transaminase (AST) levels (p = 0.008). These associations were especially significant in non-obese subjects (n = 191). In a multiple linear regression analysis, age (p = 0.008), insulin sensitivity (p = 0.001), and osteocalcin (p = 0.04) independently contributed to 22% of ALT variance in these latter subjects. In the weight loss study, the increase in circulating osteocalcin concentration (+70.6 ± 29.3 vs. +32 ± 13.5%, p = 0.021) was significantly greater in subjects with the highest decrease in ALT levels, despite similar baseline BMI, insulin resistance and degree of weight loss than remaining subjects. In fact, the change in ALT levels were linearly associated with those of osteocalcin (r = -0.55, p = 0.003). CONCLUSIONS In summary, our findings suggest a bone-liver axis in which osteocalcin might be the active regulator.
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Affiliation(s)
- J M Fernández-Real
- Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomédica de Girona (IdIBGi) CIBEROBN Fisiopatología de la Obesidad y Nutrición CB06/03/010, Girona, Catalonia, Spain.
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36
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Hinoi E. [Control of bone remodeling by nervous system. Regulation of glucose metabolism by skeleton. - Tangent point with nervous system -]. Clin Calcium 2010; 20:1814-1819. [PMID: 21123933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It has been demonstrated that osteocalcin, osteoblast-secreted molecule, regulates energy metabolism through acting on pancreatic β-cells and adipocytes, while it has been established that the adipocyte-derived hormone leptin regulates bone metabolism through central nervous system and sympathetic nervous system. Recently, it has been reported that sympathetic tone into osteoblasts is a mediator of leptin regulation of insulin secretion. These functional relationship between bone and multiple organs illustrates the pivotal role of the skeleton in the regulation of our major physiological functions including energy metabolism.
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Affiliation(s)
- Eiichi Hinoi
- Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Japan
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37
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Yamaguchi A, Akashi T. [Vascular calcification: mutual interaction between bone and blood vessel]. Clin Calcium 2010; 20:1669-1676. [PMID: 21037387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Vascular calcification often associates with bone-cartilage formation. Artery sclerotic lesions accompany the expression of bone matrix proteins such as osteopontin, osteocalcin and matrix Gla protein and transcription factors including Runx2, osterix and Sox9. These lesions also express BMP, osteoprotegerin (OPG) and RANKL, which are important factor regulating bone formation and resorption. MGP-deficient mice exhibited extensive artery calcification as well as OPG-deficient mice. Thus, bone metabolism-related factors actively participate in vascular calcification, which had been interpreted as a passive calcification due to dystrophic calcification.
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Affiliation(s)
- Akira Yamaguchi
- Section of Oral Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University
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38
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Tsushima M. [Aortic calcification and calcium]. Clin Calcium 2010; 20:1627-1635. [PMID: 21037382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Vascular calcification occurred as the last step of arteriosclerosis makes a lot of disturbances on vascular function and should influence on the worsening of the vascular diseases. Calcium is the main component of the vascular calcification like bone, and one of causes of vascular calcification should be the hypoparathyroidism due to the lowering of serum calcium and the following calcium paradox seen in osteoporosis. Bone calcium must shift to the arterial wall from the bone. Medial calcification could be formed under the molecular regulatory control like in bone by differentiated osteoblast or chondroblast from pericyte like cell origin smooth muscle cell. Many substances such as osteopontine, osteocalcine, bone morphogenetic protein 2, matrix Gla protein and alkaliphosphatase were found in calcified area. In intimal calcification, degenerated elastin and macrophage originated calcification were found. In the process of degeneration of elastin polypentapeptide structure in elastin can be easily conbined to Ca(2+), elastin-Ca(2+) complex is neutralized by PO4(2-) and calcium phosphate is accumulated in degenerated elastin.
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Affiliation(s)
- Motoo Tsushima
- Sekijinkai-Medical-incorporation/Keio University School of Medicine
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Carnevale V, Romagnoli E, Del Fiacco R, Pepe J, Cipriani C, Piemonte S, Carlucci L, Minisola S. Relationship between bone metabolism and adipogenesis. J Endocrinol Invest 2010; 33:4-8. [PMID: 20938218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
Several findings indicate that adipose tissue and bone have a complex reciprocal relationship. The two cells lineages share a common progenitor, and adipocyte endocrine activity may influence bone metabolism. Recent evidence from animal models suggests that bone cells may contribute regulating energy metabolism.
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Affiliation(s)
- V Carnevale
- Unit of Internal Medicine, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo (FG), Italy
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40
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Amizuka N, Li M, Guo Y, Liu Z, Suzuki R, Yamamoto T. [Biological effects of vitamin K2 on bone quality]. Clin Calcium 2009; 19:1788-1796. [PMID: 19949270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Post-transcriptional maturation with the presence of vitamin K(2) promotes gamma-carboxylation of osteocalcin, enabling further binding to hydroxyapatite, from which one could infer that vitamin K(2) increased the quality of bone matrix. For instance, vitamin K(2) rescued the impaired collagen mineralization caused by Mg insufficiency, by promoting a re-association of the process of collagen mineralization with mineralized nodules. Sodium warfarin, which antagonizes the function of vitamin K(2), reduced the binding of osteocalcin to bone matrices, and consequently resulted in crystalline particles being dispersed throughout the osteoid without forming mineralized nodules. Therefore, gamma-carboxylated Gla proteins mediated by vitamin K(2) appear to play a pivotal role in normal mineralization in bone.
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Affiliation(s)
- Norio Amizuka
- Division of Oral Health Science, Hokkaido University Graduate School of Dental Medicine, Japan
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41
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Hosoi T. [Clinical implications of undercarboxylated osteocalcin]. Clin Calcium 2009; 19:1815-1821. [PMID: 19949273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Importance of vitamin K has been suggested to maintain and improve bone strength. The serum concentration of undercarboxylated osteocalcin (ucOC) is utilized to assess the vitamin K status in bone metabolism. The clinical threshold for ucOC has been determined to discriminate the people at risk for fragility fractures from the view points of vitamin K metabolism. The measurement of ucOC would be useful to select the patients who require vitamin K(2) regimen and to assess the effectiveness of vitamin K(2) therapy.
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Affiliation(s)
- Takayuki Hosoi
- Department of Clinical Research and Development, National Center for Geriatrics and Gerontology, Japan
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42
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Kaneki M. [Is ucOC a novel bone-derived anti-diabetogenic hormone in humans?]. Clin Calcium 2009; 19:1304-1310. [PMID: 19721202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Recent studies have indicated that osteocalcin, a peptide secreted by osteoblasts, functions as an anti-diabetogenic hormone in mice. Osteocalcin knock out mice exhibit obesity, hyperglycemia, and decreased insulin secretion relative to wild-type mice. Treatment with non-carboxylated osteocalcin upregulates energy expenditure, and ameliorates obesity and diabetes in mouse models of obesity-related diabetes. Of interest, the beneficial effects of osteocalcin were shown to be specific to non-carboxylated osteocalcin. This appears, however, inconsistent with recent clinical studies showing insulin-sensitizing effects of vitamin K, which promotes gamma-carboxylation of osteocalcin. These findings shed new light on the crosstalk between bone and energy expenditure, and lead to new questions. These questions include: (1) Does non-carboxylated osteocalcin exert the beneficial effects in humans?; (2) Does warfarin, a vitamin K antagonist, improve insulin, sensitivity and lower blood glucose levels?; (3) and Do estrogen and bisphosphonate, which reduce circulating osteocalcin, contribute to insulin resistance and obesity? These issues await further investigations.
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Affiliation(s)
- Masao Kaneki
- Department of Anesthesia & Critical Care, Massachusetts General Hospital, Harvard Medical School, MA, USA
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Talmage RV, Mobley HT. The concentration of free calcium in plasma is set by the extracellular action of noncollagenous proteins and hydroxyapatite. Gen Comp Endocrinol 2009; 162:245-50. [PMID: 19361508 DOI: 10.1016/j.ygcen.2009.03.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 03/26/2009] [Accepted: 03/31/2009] [Indexed: 11/19/2022]
Abstract
The late Wm. F. Neuman frequently included the following statement in his speeches: "Plasma calcium is undersaturated in respect to itself, but supersaturated in respect to bone". As a physical chemist he knew that if plasma or extracellular fluid came in direct contact with bone surfaces plasma calcium level should fall to the saturated solubility of hydroxyapatite. How could the condition given in the quote exist? He answered this question by laboratory experiments but unfortunately died before he could explain it scientifically. In the current perspective article we feel that we cannot only explain Neuman's riddle but also use the answer to describe a revised premise for extracellular control of calcium concentrations in body fluids. The answer lies in the solubility of hydroxyapatite. A simple contact of bone mineral surface with body fluids should lead to a calcium concentration in plasma too low to support life. The evolutionary process prevented this by adding one or more noncollagenous proteins at the surface of hydroxyapatite. These proteins elevated the saturated solubility of the crystal latticework sufficiently to provide a calcium concentration that would sustain life. This report explains the solubility process in as much detail as our scientific information will permit and also includes the role of parathyroid hormone in the process. We hope that serious study of our article will permit acceptance of our premise for calcium control and induce further study that should demonstrate its importance in all aspects of bone metabolism.
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Affiliation(s)
- R V Talmage
- Department of Orthopaedics, UNC School of Medicine, Chapel Hill, NC, USA.
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Abstract
Although bone has long been recognized as a target for hormones influencing calcium and phosphorus homeostasis and bone structure, recent evidence shows that the skeleton itself produces at least two hormones, fibroblast growth factor 23 (FGF23) and osteocalcin. FGF23 is produced by osteocytes in bone and acts on the kidney to inhibit 1alpha-hydroxylation of vitamin D and promote phosphorus excretion. Mouse genetics studies revealed that the osteoblast product, osteocalcin, acts on the pancreatic beta-cell to enhance insulin production and on peripheral tissues to increase glucose utilization as a result of increased insulin sensitivity and to reduce visceral fat. This review highlights the recent studies indicating bone's role as an endocrine organ.
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Affiliation(s)
- Seiji Fukumoto
- Division of Nephrology & Endocrinology, Department of Medicine, University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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45
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Kimura A, Takeda S. [Clinical aspect of recent progress in phosphate metabolism. Bone as an endocrine organ]. Clin Calcium 2009; 19:821-825. [PMID: 19483277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
FGF23, secreted by bone, inhibits renal phosphate reabsorption. Recently, it was reported that osteocalcin, secreted by bone, promotes adiponectin and insulin secretion and improves glucose metabolism. Thus, bone does not just work for a storage of calcium or resisting against gravity but an endocrine organ to affect other tissues.
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Affiliation(s)
- Ayako Kimura
- Department of Orthpedics, Tokyo Medical and Dental University graduate school
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46
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Francucci CM, Ceccoli L, Rilli S, Fiscaletti P, Caudarella R, Boscaro M. Skeletal effects of oral anticoagulants. J Endocrinol Invest 2009; 32:27-31. [PMID: 19724163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
Vitamin K antagonists (VKA) are often used as oral anticoagulants (OA) in order to prevent thromboembolic diseases. In bone, vitamin K reduces bone resorption and functions as a co-factor in the post-translational carboxylation of several bone proteins. Osteocalcin (OC), the most abundant of these bone matrix proteins, is produced by osteoblasts and released in small amounts in blood as a specific marker of bone formation. Carboxylated proteins have a high affinity for calcium and are important in the incorporation of calcium into bone and bone formation. The increased levels of undercarboxylated osteocalcin can bring about an alteration of the bone mineral density and the risk of fracture, even if contradictory results have been observed in several epidemiologic studies. However, some, but not all reports, find that vitamin K deficiency, induced by hydroxycoumarins, may be associated with low bone mass. Additionally, epidemiologic studies have found that the use of OA may be associated with either increased or no change in fracture risk. Such divergent results may imply that human studies are compromised by the physical illnesses for which OA were prescribed. Additional epidemiological or cohort studies are warranted in order to determine whether potential pharmacological effects of VKA on bone metabolism may have clinical consequences.
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Affiliation(s)
- C M Francucci
- Division of Endocrinology, Department of Internal Medicine, Polytechnic University of Marche, Ancona, Italy.
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Abstract
Osteocalcin (OCN), the most abundant non-collagenous protein of the bone matrix, whose function is not fully understood, was recently suggested to act as endocrine factor regulating energy metabolism. Besides OCN, osteoblasts also express MMP-13, a matrix metallo-proteinase important for bone development and remodeling. Although differentially, both genes are regulated by 1,25-dihydroxy vitamin D3 (1,25D3) and T3, important hormones for bone metabolism. In mouse osteoblasts with a distinct differentiation status, T3 increases the expression of both proteins. By contrast, 1,25D3 stimulates the expression of MMP-13 but inhibits the expression of OCN in these cells. In humans, however, 1,25D3 upregulates both genes while T3 inhibits the OCN expression. Using northern blot hybridization we studied gene expression in the mouse osteoblastic cell line MC3T3-E1. We show that MMP-13 expression was strongly increased by T3 when the stimulation of OCN was low and, inversely, that the MMP-13 increase was low when T3 strongly stimulated the OCN expression. These findings suggest an interrelationship between OCN and MMP-13 expression. In fact, we observed that externally added OCN attenuated the T3 induced MMP-13 expression dose dependently and, furthermore, increased the 1,25D3 stimulated MMP-13 expression. Using a protein kinase A inhibitor we were able to show that this inhibitor mimics the effect of OCN suggesting a PKA dependent pathway to be involved in this regulatory process. We therefore hypothesize that OCN is a modulator of the hormonally regulated MMP-13 expression.
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Affiliation(s)
- Franz Varga
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling. 4th Medical Department, Hanusch Hospital, Vienna, Austria
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Abstract
Recent studies have indicated a novel function for skeleton unraveling its importance in the control of energy metabolism. In the present commentary, we speculate on the meaning for bone to act as a 'rheostat' modulating glucose metabolism, and how the primitive way of communication between bone and energy metabolism through switch on/off genes (like Ptprv) evolved to a more complicated 'talking' via gain/loss of hormones activity (like osteocalcin) by carboxylation/decarboxylation process.
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Affiliation(s)
- Eva Kassi
- Department of Biological Chemistry, University of Athens Medical School, 75, Mikras Asias Street, 11527 Athens, Greece
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Lerner UH, Ohlsson C, Mellström D. [The skeletal protein osteocalcin is also an endocrine hormone. Possible significance for type 2 diabetes and the metabolic syndrome]. Lakartidningen 2008; 105:2264-2266. [PMID: 18785601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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50
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Sowa H. [Regulation of energy metabolism by bone]. Clin Calcium 2008; 18:644-649. [PMID: 18445883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In terms of feedback regulation in Endocrinology, one question was arisen from the evidences that energy metabolism regulates bone metabolism. "Does bone metabolism regulates energy metabolism?" To address this question, Dr. Gerard Karsenty and his colleagues studied energy metabolism in the mice lacking Osteocalcin, an osteoblast-specific gene. The mutant mice exhibited abnormal energy metabolism phenotypes, diabetes and obesity. Here I would like to remind you his previous and recent works so that we can discuss how to apply bone metabolism information to therapeutic strategy for metabolic syndrome.
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