The prevailing model of osteology is that bones constantly undergo a remodeling process, and that the differentiation and functions of osteoblasts are partially regulated by leptin through different central hypothalamic pathways. The finding that bone remodeling is regulated by leptin suggested possible endocrinal effects of bones on energy metabolism. Recently, a reciprocal relationship between bones and energy metabolism was determined whereby leptin influences osteoblast functions and, in turn, the osteoblast-derived protein osteocalcin influences energy metabolism. The metabolic effects of bones are caused by the release of osteocalcin into the circulation in an uncarboxylated form due to incomplete gamma-carboxylation. In this regard, the Esp gene encoding osteotesticular protein tyrosine phosphatase is particularly interesting because it may regulate gamma-carboxylation of osteocalcin. Novel metabolic roles of osteocalcin have been identified, including increased insulin secretion and sensitivity, increased energy expenditure, fat mass reduction, and mitochondrial proliferation and functional enhancement. To date, only a positive correlation between osteocalcin and energy metabolism in humans has been detected, leaving causal effects unresolved. Further research topics include: identification of the osteocalcin receptor; the nature of osteocalcin regulation in other pathways regulating metabolism; crosstalk between nutrition, osteocalcin, and energy metabolism; and potential applications in the treatment of metabolic diseases.
Bone Remodeling/physiology ; Bone and Bones/*metabolism ; *Energy Metabolism ; Humans ; Leptin/metabolism ; Osteocalcin/genetics/*metabolism

Vitamin K is the cofactor for the hepatic carboxylation of glutamic acid residues in a number of proteins including the procoagulants factors ll, Vll, lX, and X. The role of vitamin K in normal bone function is not fully understood. Inherited deficiency of vitamin K dependent coagulation factors is a rare bleeding disorder reported only in a few patients. Here we present an 18-month old child who presented with osteopeni due to inherited vitamin K deficiency. While the patient had high bone specific alkaline phosphatase and parathyroid hormone levels and low osteocalcin and bone mineral density values, with the regular supplementation of vitamin K all the mentioned parameters returned to normal values.
Bone Density ; Bone Diseases, Metabolic/etiology ; Human ; Infant ; Male ; Osteocalcin/blood ; Prothrombin Time ; Vitamin K Deficiency/blood/complications/*genetics

OBJECTIVE: To explore the correlation between the genotypes and metabolic markers and microstructure of bones in children with Gitelman syndrome (GS). METHODS: For 15 children with GS and 10 healthy individuals, baseline data and bone metabolic markers including parathyroid hormone, alkaline phosphatase, osteocalcin, N-terminal propeptide of type I procollagen, beta isomer of the C-terminal telopeptide of type I collagen and 25-hydroxyvitamin D, high-resolution peripheral quantitative computed tomography indicators (volumetric bone mineral density, bone microstructure indicators) were collected. Genetic testing was carried out to determine their genotypes. RESULTS: The volumetric bone mineral density, bone geometry and bone microstructure parameters of the GS group were better than those of the healthy controls (P<0.05). Variants of the SLC12A3 gene were identified in 9 of the 15 patients but none of the 10 healthy controls. CONCLUSION The phenotype of GS children is influenced by the interaction of genetic variants, though the phenotype associated with high frequency mutations showed no specificity. There is also a correlation between their genotype and the bone microstructure.
Biomarkers ; Bone and Bones ; Child ; Collagen Type I/genetics* ; Genotype ; Gitelman Syndrome ; Humans ; Osteocalcin/genetics* ; Peptide Fragments ; Solute Carrier Family 12, Member 3

OBJECTIVETo investigate the mineralization capacity of periodontal ligament stem cells (PDLC) by determining the mRNA expressions of alkaline phosphatase (ALP), osteocalcin (OCN) and matrix extracellular phosphoglycoprotein (MEPE) and to explore the potential of MEPE as a differentiation marker for PDLC, and its possible function in PDLC osteogenic differentiation.

METHODSPDLC were digested and cultured by a solution containing collagenase type I and dispase. PDLC were preceded to osteogenic induction for 7, 14 and 21 days respectively, and the cells before induction served as controls. Mineralization nodules and the expression of OCN in PDLC were investigated by alizarin red and immunohistochemistry respectively. The expressions of ALP, OCN and MEPE mRNA were investigated by quantitative real-time RT-PCR analysis. Statistical analysis was performed to compare the differences of mRNA expression levels among cell samples collected at different time points.

RESULTSThe mRNA expressions of ALP, OCN and MEPE in PDLC before induction were 72, 1.1 and 534 respectively, but increased time-dependently in the induction cultures. The mRNA expressions of ALP, OCN and MEPE were 78, 9.56 and 629.6 on day 7; 290, 133 and 638.3 on day 14; 1108, 925 and 2261.1 on day 21 respectively. The relative mRNA levels of OCN, ALP on day 14 and 21, MEPE on day 21 were significantly higher than control group (P < 0.05).

CONCLUSIONSPDLC showed analogously temporal expression of ALP, OCN and MEPE mRNA while differentiating into cementoblast/osteoblast-like cells in vitro. MEPE may play a regulatory role in PDLC osteogenic differentiation, and may be a potential osteogenic differentiation marker along with ALP and OCN.

Alkaline Phosphatase ; genetics ; metabolism ; Cell Differentiation ; Cells, Cultured ; Extracellular Matrix Proteins ; genetics ; metabolism ; Glycoproteins ; genetics ; metabolism ; Humans ; Osteoblasts ; cytology ; metabolism ; Osteocalcin ; genetics ; metabolism ; Periodontal Ligament ; cytology ; metabolism ; Phosphoproteins ; genetics ; metabolism ; RNA, Messenger ; genetics

BACKGROUNDBone morphogenetic protein 9 (BMP9) and Wnt/β-catenin signaling pathways are able to induce osteogenic differentiation of mesenchymal stem cells (MSCs), but the role of Wnt/β-catenin signaling pathway in BMP9-induced osteogenic differentiation is not well understood. Thus, our experiment was undertaken to investigate the interaction between BMP9 and Wnt/β-catenin pathway in inducing osteogenic differentiation of MSCs.

METHODSC3H10T1/2 cells were infected with recombinant adenovirus expressing BMP9, Wnt3a, and BMP9+Wnt3a. ALP, the early osteogenic marker, was detected by quantitative and staining assay. Later osteogenic marker, mineral calcium deposition, was determined by Alizarin Red S staining. The expression of osteopotin (OPN), osteocalcin (OC), and Runx2 was analyzed by Real time PCR and Western blotting. In vivo animal experiment was carried out to further confirm the role of Wnt3a in ectopic bone formation induced by BMP9.

RESULTSThe results showed that Wnt3a enhanced the ALP activity induced by BMP9 and increased the expressions of OC and OPN, with increase of mineral calcium deposition in vitro and ectopic bone formation in vivo. Furthermore, we also found that Wnt3a increased the level of Runx2, an important nuclear transcription factor of BMP9.

CONCLUSIONCanonical Wnt/β-catenin signal pathway may play an important role in BMP9-induced osteogenic differentiation of MSCs, and Runx2 may be a linkage between the two signal pathways.

Blotting, Western ; Cell Differentiation ; genetics ; physiology ; Core Binding Factor Alpha 1 Subunit ; genetics ; metabolism ; Growth Differentiation Factor 2 ; genetics ; metabolism ; Humans ; Osteocalcin ; genetics ; metabolism ; Osteogenesis ; genetics ; physiology ; Wnt3A Protein ; genetics ; metabolism

OBJECTIVETo observe the expression profiles of osteoblast-related genes in human mesenchymal stem cells (MSCs) derived from bone marrow during osteogenic differentiation.

METHODSMSCs were induced to differentiate with MSC osteogenic differentiation medium for 7, 14, 21 and 28 days respectively. Alizarin Red staining was used to detect matrix mineralization. Expression of osteoblast-related genes, including osteocalcin, osteopontin, Runt-related transcription factor 2 (Runx2), alkaline phosphatase and collagen type 1, was assessed with quantitative reverse transcription-polymerase chain reaction.

RESULTSOn day 14 after induction of differentiation, cells were stained positively with Alizarin Red. The expression levels of these genes exhibited an upward trend as induction time was prolonged. Exposure to osteogenic differentiation medium less than 21 days did not significantly induce osteocalcin expression; osteocalcin expression levels in the differentiated cells induced for 21 and 28 days were 1.63 and 2.46 times as high as the undifferentiated cells respectively (all P<0.05). Stimulation with MSC osteogenic differentiation medium over 14 days significantly enhanced bone marrow-derived MSCs to express osteopontin and Runx2 genes (all P<0.05). Osteogenic differentiation medium could significantly induce the expressions of alkaline phosphatase and collagen type1 genes (all P<0.05). Their expressions reached the peak levels on day 21, which were increased more than 4- and 3-fold respectively.

CONCLUSIONHuman bone marrow-derived MSCs could exhibit the sequential expression pattern of osteoblast marker genes during osteogenic differentiation in vitro.

Alkaline Phosphatase ; genetics ; Cell Differentiation ; Cells, Cultured ; Collagen Type I ; genetics ; Core Binding Factor Alpha 1 Subunit ; genetics ; Genetic Markers ; Humans ; Mesenchymal Stromal Cells ; metabolism ; Osteocalcin ; genetics ; Osteogenesis ; Transcriptome

Homocysteine (Hcy) is thought to play an important role in the development of osteoporosis and fracture. Methionine synthase reductase (MTRR) is an enzyme involved in the conversion of Hcy to methionine. We hypothesized that certain genetic polymorphisms of MTRR leading to reduced enzyme activity may cause hyperhomocysteinemia and affect bone metabolism. We therefore examined the associations of the A66G and C524T polymorphisms of the MTRR gene with bone mineral density (BMD) and serum osteocalcin levels in postmenopausal women. Although we did not detect any significant associations between MTRR polymorphisms and BMD or serum osteocalcin levels, we found that the 66G/524C haplotype, which has reduced enzyme activity, was significantly associated with serum osteocalcin levels in a gene-dose dependent manner (P=0.002). That is, the highest osteocalcin levels (34.5+/-16.8 ng/ml) were observed in subjects bearing two copies, intermediate osteocalcin levels (32.6+/-14.4 ng/ml) were observed in subjects bearing one copy, and the lowest levels of osteocalcin (28.8+/-10.9 ng/ml) were observed in subjects bearing no copies. These results suggest that the 66G/524C haplotype of the MTRR gene affect bone turn over rate.
Postmenopause/*blood ; *Polymorphism, Genetic ; Osteocalcin/*blood ; Middle Aged ; Lumbosacral Region/radiography ; Humans ; Genotype ; Ferredoxin-NADP Reductase/*genetics/physiology ; Femur Neck/radiography ; Female ; Bone Density ; Aged, 80 and over ; Aged

OBJECTIVETo observe effects of blood circulation promoting compounds combined with medicinal guides on content of bone glaprotein (BGP), bone morphogenetic protein-2 (BPM-2) and expression of BMP-2 mRNA in rabbits with femoral head necrosis, and explore its mechanism.

METHODSNinety-eight healthy Spragur-Dawley male rabbits were collected and weighted 2.2 to 2.8 kg. Eighty-four rabbits were built femoral head necrosis model by freezing left femoral head in liquid nitrogen, then randomly divided into 6 groups, 14 in each group. The 6 groups included model group,promoting blood circulation to remove meridian obstruction group,promoting blood circulation to remove meridian obstruction combined with achyranthes bidentata group,radix angelicae pubescentis, asarum group, and platycodon grandiflorum group,other 14 rabbits were sham operation group. While drug groups were administrated corresponding Chinese herb after molding,model group and shamp operation group were given saline. Recombinant human granulocyte-colony stimulating factor ( 30 microg x kg(-1) x d(-1))were injected into all rabbits for 7 days. Samples were taken on the second and fourth week,the content of BGP and BMP-2 were detected by enzyme-linked immunosorbent assay (ELSA) and radioimmunoassay (RIA), histopathological changes of left femoral head were observed by Hematoxylin and Eeosin staining (HE), and expression of BMP-2 mRNA were tested by fluorescence in situ hybridization.

RESULTSCompared with sham operation group, the rate of empty lacunae femoral head were obviously increased in model group, and the content of BGP were increased on the second week, and BMP-2 and BMP-2 mRNA were decreased on the fourth week. Compared with model group, the content of BGP, BMP-2 and BMP-2 mRNA were higher both of the second and fourth week in promoting blood circulation to remove meridian obstruction group. The rate of empty la- cunae femoral head were lower in achyranthes bidentata group, BGP, BMP-2 and BMP-2 mRNA were higher on the fourth week. The rate of empty lacunae femoral head were lower in platycodon grandiflorum group, and BGP were decreased on the second and fourth week, BMP-2 were lower on the second week ,while BMP-2 mRNA were decreased on the fourth week; the content of BMP-2 and BMP-2 mRNA were increased in radix angelicae pubescentis group on the second week; while there was no change in asarum group.

CONCLUSIONRadix angelicae pubescentis can increase the content of BGP, BMP-2 and expression of BMP-2 mRNA ,which is an effective mechanism of preventing femoral head necrosis.

Animals ; Blood Circulation ; drug effects ; Bone Morphogenetic Protein 2 ; analysis ; genetics ; Femur Head Necrosis ; drug therapy ; pathology ; physiopathology ; Male ; Meridians ; Osteocalcin ; blood ; Osteogenesis ; drug effects ; Rabbits

OBJECTIVE: To investigate the effect of adiponectin on the osteoblast differentiation and its signal transduction. METHODS: Adipopnectin receptor (AdipoR) was detected by immunoblot analysis. Alkaline phosphatase (ALP) activity was measured by enzyme-linked immunosorbent assay. Osteocalcin was measured by a specific radioimmunoassay kit, and the extent of mineralized matrix was determined. RNA interference was used to down-regulate the expression of AdipoR1 in human osteoblasts, and the effect of adiponectin on osteoblast differentiation was investigated. RESULTS: Only AdipoR1 protein was detected in human osteoblasts. Adiponectin could promote osteoblast differentiation, and result in a dose-dependent increase in ALP activity, osteocalcin secretion, and an increase in mineralized nodules. Suppression of AdipoR1 with siRNA could abolish the adiponectin induced ALP expression. Adiponectin could induce the activation of p38 and JNK, but not ERK1/2 in osteoblasts, and the pretreatment of osteoblasts with the p38 inhibitor (SB203580) could block the adiponectin-induced ALP activity. CONCLUSION Adiponectin can induce human osteoblast differentiation via AdipoR1/p38 pathway.
Adiponectin ; pharmacology ; Alkaline Phosphatase ; metabolism ; Cell Differentiation ; drug effects ; Cells, Cultured ; Humans ; Osteoblasts ; cytology ; metabolism ; Osteocalcin ; analysis ; RNA, Small Interfering ; genetics ; Receptors, Adiponectin ; biosynthesis ; Signal Transduction

This study sought to elucidate the effect of mechanical strain on the differentiation of mesenchymal stem cells into osteoblasts. Under the conditons of inducing osteoblasts, Immunohistochemical methods and RT-PCR technology were applied in osteogenic supplements medium to detect: (1) the expression of Alkaline phosphatase (ALP), Type I collagen (COL I ), Osterx (Osx) and Osteocalcin (OCN) mRNA, with cyclic strain (3%, 0.5 Hz) applied for 15 min, 30 min, 1 h, 2 h, 4 h, 3 d, 7 d, 14 d; (2) the expression of Osx mRNA and OCN mRNA with 3% strain for 1 h. The results showed: (1) ALP mRNA expression was higher at 7 days; COL I mRNA expression was greater obviously at 7 days and 14 days than that at 3 days and that of the unstrained cells; (2) the expression of Osx mRNA was up-regulated after 15min by strain stimulation,which was significantly increased at 30 min and 1 h in the unstrained cells. The expression of OCN mRNA was not affected in the unstrained cells at 15 min, whereas strain could promote the expression of OCN mRNA at this period. The expression of OCN mRNA was more obviously upregulated in the strained cells at 30 min and 1 h when compared with that in the unstrained cells; (3) the strain (1% and 3%) significantly promoted the expression of Osx mRNA; 10% strain had a little effect on Osx mRNA expression. The expression of OCN mRNA was up-regulated by 3% strain, whereas it had little effect at 1% and 10% strain. In summary, mechanical strain can promote the differentiation of mesenchymal stem cells into osteoblasts.
Animals ; Bone Marrow Cells ; cytology ; Cell Differentiation ; Cells, Cultured ; Mechanoreceptors ; physiology ; Mechanotransduction, Cellular ; physiology ; Mesenchymal Stromal Cells ; cytology ; Mice ; Osteoblasts ; cytology ; Osteocalcin ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Sp7 Transcription Factor ; Stress, Mechanical ; Transcription Factors ; genetics ; metabolism