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Frontiers in Public Health 2022Vitamin K (VK) as a nutrient, is a cofactor in the carboxylation of osteocalcin (OC), which can bind with hydroxyapatite to promote bone mineralization and increase bone... (Meta-Analysis)
Meta-Analysis
INTRODUCTION
Vitamin K (VK) as a nutrient, is a cofactor in the carboxylation of osteocalcin (OC), which can bind with hydroxyapatite to promote bone mineralization and increase bone strength. However, some studies have been inconsistent on whether vitamin K2 (VK2) can maintain or improve bone mineral density (BMD) and reduce the incidence of fractures in postmenopausal women. Therefore, the main objective of this meta-analysis was to determine the effect of VK2 as a nutritional supplement on BMD and fracture incidence in postmenopausal women.
METHODS
We searched PubMed, EMBASE, and Cochrane Library databases (published before March 17, 2022) and then extracted and pooled data from all randomized controlled trials (RCTs) that met the inclusion criteria.
RESULTS
Sixteen RCTs with a total of 6,425 subjects were included in this meta-analysis. The overall effect test of 10 studies showed a significant improvement in lumbar spine BMD (BMD LS) ( = 0.006) with VK2. The subgroup analysis of VK2 combination therapy showed that BMD LS was significantly maintained and improved with the administration of VK2 ( = 0.03). The overall effect test of the six RCTs showed no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65). However, after excluding one heterogeneous study, the overall effect test showed a significant reduction in fracture incidence with VK2 (RR = 0.43, = 0.01). In addition, this meta-analysis showed that VK2 reduced serum undercarboxylated osteocalcin (uc-OC) levels and the ratio of uc-OC to cOC in both subgroups of VK2 combined intervention and alone. However, for carboxylated osteocalcin (cOC), both subgroup analysis and overall effect test showed no significant effect of VK2 on it. And the pooled analysis of adverse reactions showed no significant difference between the VK2 and control groups (RR = 1.03, 95%CI 0.87 to 1.21, = 0.76).
CONCLUSIONS
The results of this meta-analysis seem to indicate that VK2 supplementation has a positive effect on the maintenance and improvement of BMD LS in postmenopausal women, and it can also reduce the fracture incidence, serum uc-OC levels and the ratio of uc-OC to cOC. In conclusion, VK2 can indirectly promote bone mineralization and increase bone strength.
Topics: Bone Density Conservation Agents; Female; Humans; Osteocalcin; Osteoporosis, Postmenopausal; Randomized Controlled Trials as Topic; Vitamin K 2
PubMed: 36033779
DOI: 10.3389/fpubh.2022.979649 -
The Journal of Experimental Medicine Oct 2017That osteocalcin (OCN) is necessary for hippocampal-dependent memory and to prevent anxiety-like behaviors raises novel questions. One question is to determine whether...
That osteocalcin (OCN) is necessary for hippocampal-dependent memory and to prevent anxiety-like behaviors raises novel questions. One question is to determine whether OCN is also sufficient to improve these behaviors in wild-type mice, when circulating levels of OCN decline as they do with age. Here we show that the presence of OCN is necessary for the beneficial influence of plasma from young mice when injected into older mice on memory and that peripheral delivery of OCN is sufficient to improve memory and decrease anxiety-like behaviors in 16-mo-old mice. A second question is to identify a receptor transducing OCN signal in neurons. Genetic, electrophysiological, molecular, and behavioral assays identify , an orphan G protein-coupled receptor expressed in neurons of the CA3 region of the hippocampus, as transducing OCN's regulation of hippocampal-dependent memory in part through inositol 1,4,5-trisphosphate and brain-derived neurotrophic factor. These results indicate that exogenous OCN can improve hippocampal-dependent memory in mice and identify molecular tools to harness this pathway for therapeutic purposes.
Topics: Aging; Animals; CA3 Region, Hippocampal; Cognition; Electrophysiology; Female; Male; Maze Learning; Memory; Mice; Mice, Inbred C57BL; Mice, Knockout; Osteocalcin; Receptors, G-Protein-Coupled
PubMed: 28851741
DOI: 10.1084/jem.20171320 -
Molecular Metabolism Jul 2021The bone-derived protein osteocalcin (OC), in its undercarboxylated (ucOC) form, has a beneficial effect on energy metabolism and may be a future therapeutic target for... (Review)
Review
BACKGROUND
The bone-derived protein osteocalcin (OC), in its undercarboxylated (ucOC) form, has a beneficial effect on energy metabolism and may be a future therapeutic target for metabolic diseases. Increasing evidence suggests a link between ucOC and cardiovascular disease (CVD) development; however, the exact relationship is conflicting and unclear.
SCOPE OF REVIEW
The aim of this review was to summarise the current research examining the interaction between OC and vascular dysfunction, the initiating stage in the development of atherosclerosis and CVD.
MAJOR CONCLUSIONS
In humans, the association between OC and vascular function is inconsistent. Several studies report that total OC (tOC) is associated with adverse function or beneficial function, whereas others report that tOC and ucOC has no effect on vascular function. The conflicting data are likely due to several methodological inconsistencies, in particular the lack of studies reporting circulating ucOC levels. In animal models, the direct administration of ucOC to isolated blood vessels ex vivo produced minimal changes in endothelial function, but importantly, no adverse responses. Finally, in human endothelial and vascular smooth muscle cells, ucOC treatment did not influence classical markers of cellular function, including endothelin-1, vascular adhesion molecule-1 and monocyte chemoattractant protein-1 after exposure to high glucose and inflammatory conditions. The lack of adverse effects in ex vivo and in vitro studies suggests that ucOC may be targeted as a future therapeutic for metabolic diseases, without the risk of detrimental effects in the vasculature. However, further studies are needed to confirm these findings and to investigate whether there is a direct beneficial influence of ucOC.
Topics: Animals; Atherosclerosis; Biomarkers; Bone and Bones; Cardiovascular Diseases; Cardiovascular Physiological Phenomena; Endothelial Cells; Humans; Osteocalcin; Receptors, G-Protein-Coupled
PubMed: 33684607
DOI: 10.1016/j.molmet.2021.101205 -
EMBO Reports Feb 2024Many physiological osteocalcin-regulated functions are affected in adult offspring of mothers experiencing unhealthy pregnancy. Furthermore, osteocalcin signaling during...
Many physiological osteocalcin-regulated functions are affected in adult offspring of mothers experiencing unhealthy pregnancy. Furthermore, osteocalcin signaling during gestation influences cognition and adrenal steroidogenesis in adult mice. Together these observations suggest that osteocalcin may broadly function during pregnancy to determine organismal homeostasis in adult mammals. To test this hypothesis, we analyzed in unchallenged wildtype and Osteocalcin-deficient, newborn and adult mice of various genotypes and origin maintained on different genetic backgrounds, the functions of osteocalcin in the pancreas, liver and testes and their molecular underpinnings. This analysis revealed that providing mothers are Osteocalcin-deficient, Osteocalcin haploinsufficiency in embryos hampers insulin secretion, liver gluconeogenesis, glucose homeostasis, testes steroidogenesis in adult offspring; inhibits cell proliferation in developing pancreatic islets and testes; and disrupts distinct programs of gene expression in these organs and in the brain. This study indicates that osteocalcin exerts dominant functions in most organs it influences. Furthermore, through their synergistic regulation of multiple physiological functions, osteocalcin of maternal and embryonic origins contributes to the establishment and maintenance of organismal homeostasis in newborn and adult offspring.
Topics: Animals; Female; Humans; Mice; Pregnancy; Blood Glucose; Homeostasis; Insulin; Insulin Secretion; Mammals; Osteocalcin; Prenatal Exposure Delayed Effects
PubMed: 38228788
DOI: 10.1038/s44319-023-00031-3 -
Journal of Orthopaedic Surgery and... Oct 2023The aim of this study was to investigate whether Osteonectin/Secreted protein acidic and rich in cysteine (ON/SPARC) had a two-way dose-dependent regulatory effect on...
OBJECTIVE
The aim of this study was to investigate whether Osteonectin/Secreted protein acidic and rich in cysteine (ON/SPARC) had a two-way dose-dependent regulatory effect on osteoblast mineralization and its molecular mechanism.
METHODS
Initially, different concentrations of ON were added in osteoblasts, and the gene of bone sialoprotein (BSP), osteocalcin (OCN), osteopontin (OPN) and alkaline phosphatase (ALP) were detected using reverse-transcription quantitative polymerase chain reaction (RT-PCR). Secondly, based on the above results, the Optima and inhibitory concentration of ON for osteoblast mineralization were determined and regrouped, the Control group was also set up, and the gene detections of Collagen 1 (Col 1), Discoidin domain receptor 2 (DDR2) and p38 mitogen‑activated protein kinase were added using RT-PCR. In the third stage of the experiment, osteoblasts were pretreated with 0.4Mm ethyl-3,4-dihydroxybenzoate (DHB) (a specific inhibitor of collagen synthesis) for 3 h before adding the optima SPARC, the gene and protein expressions of OCN, OPN, BSP, ALP, DDR2, ALP, Col 1, DDR2 and P38 were detected by RT‑qPCR and western blot analysis, and the mineralized nodules were observed by alizarin red staining.
RESULTS
The results showed that the expression of OCN, OPN, BSP, ALP, DDR2, ALP, Col 1, DDR2 and P38 genes and proteins in osteoblasts were significantly enhanced by 1 ug/ml ON, 100 ug/ml ON or 1 ug/ml ON added with 3,4 DHB significantly inhibited the expressions of DDR2, P38 and the above-mentioned mineralization indexes, and significantly reduced the formation of mineralized nodules.
CONCLUSION
This study suggested that ON had a bidirectional dose-dependent regulatory effect on osteoblast mineralization, and the activation of P38 pathway by collagen binding to DDR2 was also an important molecular mechanism.
Topics: Humans; Osteonectin; Osteocalcin; Calcinosis; Integrin-Binding Sialoprotein; Collagen; Osteoblasts; Cell Differentiation; Osteogenesis
PubMed: 37807073
DOI: 10.1186/s13018-023-04250-1 -
Oncotarget Aug 2015
Topics: 1-Carboxyglutamic Acid; Animals; Humans; Mice; Osteocalcin
PubMed: 26343369
DOI: 10.18632/oncotarget.5126 -
Nutrients Jun 2018Recent advances have indicated that osteocalcin, and in particular its undercarboxylated form (ucOC), is not only a nutritional biomarker reflective of vitamin K status... (Review)
Review
Recent advances have indicated that osteocalcin, and in particular its undercarboxylated form (ucOC), is not only a nutritional biomarker reflective of vitamin K status and an indicator of bone health but also an active hormone that mediates glucose metabolism in experimental studies. This work has been supported by the putative identification of G protein-coupled receptor, class C, group 6, member A (GPRC6A) as a cell surface receptor for ucOC. Of note, ucOC has been associated with diabetes and with cardiovascular risk in epidemiological studies, consistent with a pathophysiological role for ucOC in vivo. Limitations of existing knowledge include uncertainty regarding the underlying mechanisms by which ucOC interacts with GPRC6A to modulate metabolic and cardiovascular outcomes, technical issues with commonly used assays for ucOC in serum, and a paucity of clinical trials to prove causation and illuminate the scope for novel health interventions. A key emerging area of research is the role of ucOC in relation to expression of GPRC6A in muscle, and whether exercise interventions may modulate metabolic outcomes favorably in part via ucOC. Further research is warranted to clarify potential direct and indirect roles for ucOC in human health and cardiometabolic diseases.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Animals; Blood Glucose; Carboxylic Acids; Cardiovascular Diseases; Diabetes Mellitus; Female; Homeostasis; Humans; Insulin; Insulin Resistance; Male; Middle Aged; Muscle, Skeletal; Osteocalcin; Receptors, G-Protein-Coupled; Risk Factors; Signal Transduction; Young Adult
PubMed: 29966260
DOI: 10.3390/nu10070847 -
Biochimica Et Biophysica Acta. General... Mar 2021The carboxylation status of Osteocalcin (Ocn) not only influences formation and structure in bones but also has important endocrine functions affecting energy metabolism... (Review)
Review
BACKGROUND
The carboxylation status of Osteocalcin (Ocn) not only influences formation and structure in bones but also has important endocrine functions affecting energy metabolism and expenditure. In this study, the role of γ-carboxylation of the glutamate residues in the structure-dynamics-function relationship in Ocn is investigated.
METHODS
Three forms of Ocn, differentially carboxylated at the Glu-17, 21 and 24 residues, along with a mutated form of Ocn carrying Glu/Ala mutations, are modeled and simulated using molecular dynamics (MD) simulation in the presence of calcium ions.
RESULTS
Characterization of the global conformational dynamics of Ocn, described in terms of the orientational variations within its 3-helical domain, highlights large structural variations in the non-carboxylated osteocalcin (nOcn). The bi-carboxylated Ocn (bOcn) and tri-carboxylated (tOcn) species, in contrast, display relatively rigid tertiary structures, with the dynamics of most regions strongly correlated. Radial distribution functions calculated for both bOcn and tOcn show long-range ordering of the calcium ion distribution around the carboxylated glutamate (γGlu) residues, likely playing an important role in promoting stability of these Ocns. Additionally, the same calcium ions are observed to coordinate with neighboring γGlu, better shielding their negative charges and in turn stabilizing these systems more than do the singly coordinating calcium ions observed in the case of nOcn. bOcn is also found to exhibit a more helical C-terminal structure, that has been shown to activate its cellular receptor GPRC6A, highlighting the allosteric role of Ocn carboxylation in modulating the stability and binding potential of the active C-terminal.
CONCLUSIONS
The carboxylation status of Ocn as well and its calcium coordination appear to have a direct influence on Ocn structure and dynamics, possibly leading to the known differences in Ocn biological function.
GENERAL SIGNIFICANCE
Modification of Ocn sequence or its carboxylation state may provide the blueprint for developing high-affinity peptides targeting its cellular receptor GPRC6A, with therapeutic potential for treatment of metabolic disorders.
Topics: Amino Acid Sequence; Animals; Calcium; Carboxylic Acids; Glutamic Acid; Humans; Molecular Dynamics Simulation; Osteocalcin; Protein Conformation; Protein Stability
PubMed: 33340588
DOI: 10.1016/j.bbagen.2020.129809 -
Biointerphases May 2017Adsorption isotherms, circular dichroism (CD) spectroscopy, x-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were...
Adsorption isotherms, circular dichroism (CD) spectroscopy, x-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to investigate the adsorption of human osteocalcin (hOC) and decarboxylated (i.e., Gla converted back to Glu) hOC (dhOC) onto various calcium phosphate surfaces as well as silica surfaces. The adsorption isotherms and XPS nitrogen signals were used to track the amount of adsorbed hOC and dhOC. The intensities of key ToF-SIMS amino acid fragments were used to assess changes in the structure of adsorbed hOC and dhOC. CD spectra were used to investigate the secondary structure of OC. The largest differences were observed when the proteins were adsorbed onto silica versus calcium phosphate surfaces. Similar amounts (3-4 at. % N) of hOC and dhOC were adsorbed onto the silica surface. Higher amounts of hOC and dhOC were adsorbed on all the calcium phosphate surfaces. The ToF-SIMS data showed that the intensity of the Cys amino acid fragment, normalized to intensity of all amino acid fragments, was significantly higher (∼×10) when the proteins were adsorbed onto silica. Since in the native OC structure the cysteines are located in the center of three α-helices, this indicates both hOC and dhOC are more denatured on the silica surface. As hOC and dhOC denature upon adsorption to the silica surface, the cysteines become more exposed and are more readily detected by ToF-SIMS. No significant differences were detected between hOC and dhOC adsorbed onto the silica surface, but small differences were observed between hOC and dhOC adsorbed onto the calcium phosphate surfaces. In the OC structure, the α-3 helix is located above the α-1 and α-2 helices. Small differences in the ToF-SIMS intensities from amino acid fragments characteristic of each helical unit (Asn for α-1; His for α-2; and Phe for α-3) suggests either slight changes in the orientation or a slight uncovering of the α-1 and α-2 for adsorbed dhOC. XPS showed that similar amounts of hOC and dhOC were absorbed onto hydroxyapaptite and octacalcium phosphate surfaces, but ToF-SIMS detected some small differences in the amino acid fragment intensities on these surfaces for adsorbed hOC and dhOC.
Topics: Calcium Phosphates; Humans; Osteocalcin; Photoelectron Spectroscopy; Protein Structure, Secondary; Silicon Dioxide; Spectrometry, Mass, Secondary Ion; Surface Properties
PubMed: 28521505
DOI: 10.1116/1.4983407 -
Advances in Nutrition (Bethesda, Md.) Mar 2012Seventeen vitamin K-dependent proteins have been identified to date of which several are involved in regulating soft-tissue calcification. Osteocalcin, matrix Gla... (Review)
Review
Seventeen vitamin K-dependent proteins have been identified to date of which several are involved in regulating soft-tissue calcification. Osteocalcin, matrix Gla protein (MGP), and possibly Gla-rich protein are all inhibitors of soft-tissue calcification and need vitamin K-dependent carboxylation for activity. A common characteristic is their low molecular weight, and it has been postulated that their small size is essential for calcification inhibition within tissues. MGP is synthesized by vascular smooth muscle cells and is the most important inhibitor of arterial mineralization currently known. Remarkably, the extrahepatic Gla proteins mentioned are only partly carboxylated in the healthy adult population, suggesting vitamin K insufficiency. Because carboxylation of the most essential Gla proteins is localized in the liver and that of the less essential Gla proteins in the extrahepatic tissues, a transport system has evolved ensuring preferential distribution of dietary vitamin K to the liver when vitamin K is limiting. This is why the first signs of vitamin K insufficiency are seen as undercarboxylation of the extrahepatic Gla proteins. New conformation-specific assays for circulating uncarboxylated MGP were developed; an assay for desphospho-uncarboxylated matrix Gla protein and another assay for total uncarboxylated matrix Gla protein. Circulating desphospho-uncarboxylated matrix Gla protein was found to be predictive of cardiovascular risk and mortality, whereas circulating total uncarboxylated matrix Gla protein was associated with the extent of prevalent arterial calcification. Vitamin K intervention studies have shown that MGP carboxylation can be increased dose dependently, but thus far only 1 study with clinical endpoints has been completed. This study showed maintenance of vascular elasticity during a 3-y supplementation period, with a parallel 12% loss of elasticity in the placebo group. More studies, both in healthy subjects and in patients at risk of vascular calcification, are required before conclusions can be drawn.
Topics: Animals; Calcification, Physiologic; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Humans; Liver; Muscle, Smooth, Vascular; Osteocalcin; Vitamin K; Matrix Gla Protein
PubMed: 22516724
DOI: 10.3945/an.111.001628