OBJECTIVE: To investigate the expression and its relative mechanism of hypoxia-inducible factor-1α(HIF-1α) in bone marrow(BM) of mice during G-CSF mobilization of hematopoietic stem cells (HSC) . METHODS: Flow cytometry was used to detect the proportion of Lin^-Sca-1⁺ c-kit⁺ (LSK) cells in peripheral blood of C57BL/6J mice before and after G-CSF mobilization. And the expression of HIF-1α and osteocalcin (OCN) mRNA and protein were detected by RQ-PCR and immunohistochemistry. The number of osteoblasts in bone marrow specimens of mice was counted under the microscope. RESULTS: The proportion of LSK cells in peripheral blood began to increase at day 4 of G-CSF mobilization, and reached the peak at day 5, which was significantly higher than that of control group (P<0.05). There was no distinct difference in the expression of HIF-1α mRNA between bone marrow nucleated cells and osteoblasts of steady-state mice (P=0.073), while OCN mRNA was mainly expressed in osteoblasts, which was higher than that in bone marrow nucleated cells (P=0.034). After mobilization, the expression level of HIF-1α increased, but OCN decreased, and the number of endosteum osteoblasts decreased. The change of HIF-1α expression was later than that of OCN and was consistent with the proportion of LSK cells in peripheral blood. CONCLUSION The expression of HIF-1α in bone marrow was increased during the mobilization of HSC mediated by G-CSF, and one of the mechanisms may be related to the peripheral migration of HSC induced by osteoblasts inhibition.
Mice ; Animals ; Hematopoietic Stem Cell Mobilization ; Granulocyte Colony-Stimulating Factor/pharmacology* ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; Mice, Inbred C57BL ; Bone Marrow Cells/metabolism* ; Osteocalcin/metabolism* ; RNA, Messenger/metabolism*

OBJECTIVE: To investigate the regulatory effects of miR-26a-5p on the osteogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) by regulating cAMP response element binding protein 1 (CREB1). METHODS: The adipose tissues of four 3-4 weeks old female C57BL/6 mice were collected and the cells were isolated and cultured by digestion separation method. After morphological observation and identification by flow cytometry, the 3rd-generation cells were subjected to osteogenic differentiation induction. At 0, 3, 7, and 14 days after osteogenic differentiation induction, the calcium deposition was observed by alizarin red staining, ALP activity was detected, miR- 26a-5p and CREB1 mRNA expressions were examined by real-time fluorescence quantitative PCR, and CREB1 protein and its phosphorylation (phospho-CREB1, p-CREB1) level were measured by Western blot. After the binding sites between miR-26a-5p and CREB1 was predicted by the starBase database, HEK-293T cells were used to conduct a dual-luciferase reporter gene experiment to verify the targeting relationship (represented as luciferase activity after 48 hours of culture). Finally, miR-26a-p inhibitor (experimental group) and the corresponding negative control (control group) were transfected into ADSCs. Alizarin red staining, ALP activity, real-time fluorescent quantitative PCR (miR-26a-5p) and Western blot [CREB1, p-CREB1, Runt-related transcription factor 2 (RUNX2), and osteocalcin (OCN)] were performed at 7 and 14 days after osteogenic induction culture. RESULTS: The cultured cells were identified as ADSCs. With the prolongation of osteogenic induction culture, the number of calcified nodules and ALP activity significantly increased ( P<0.05). The relative expression of miR-26a-5p in the cells gradually decreased, while the relative expressions of CREB1 mRNA and protein, as well as the relative expression of p-CREB1 protein were increased. The differences were significant between 7, 14 days and 0 day ( P<0.05). There was no significant difference in p-CREB1/CREB1 between different time points ( P>0.05). The starBase database predicted that miR-26a-5p and CREB1 had targeted binding sequences, and the dual-luciferase reporter gene experiment revealed that overexpression of miR-26a-5p significantly suppressed CREB1 wild-type luciferase activity ( P<0.05). After 7 and 14 days of osteogenic induction, compared with the control group, the number of calcified nodules, ALP activity, and relative expressions of CREB1, p-CREB1, OCN, and RUNX2 proteins in the experimental group significantly increased ( P<0.05). There was no significant difference in p-CREB1/CREB1 between the two groups ( P>0.05). CONCLUSION Knocking down miR-26a-5p promoted the osteogenic differentiation of ADSCs by up-regulating CREB1 and its phosphorylation.
Animals ; Female ; Mice ; Cell Differentiation ; Cells, Cultured ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Cyclic AMP Response Element-Binding Protein/metabolism* ; Mesenchymal Stem Cells ; Mice, Inbred C57BL ; MicroRNAs/metabolism* ; Osteocalcin/metabolism* ; Osteogenesis/genetics* ; RNA, Messenger/genetics*

OBJECTIVE: To investigate the effect of 275 nm and 310 nm ultraviolet irradiation on ovariectomized rats' bone metabolism. METHODS: Twenty four 3-month-old female Sprague-Dawley (SD) rat were randomly divided into control group, sham operated group, 275 nm ultraviolet (UV) irradiation group and 310 nm UV irradiation group. Each group contained 6 rats. The rats in the two irradiation groups were treated with bilateral ovariectomy. The rats in sham operated group received sham operation (They were given the same back incision and a bit of par-ovarian fat were removed). Control group received no disposition. About 24 weeks after operation, all the rats received detailed bone mineral density (BMD) detection again. Detection regions include cervical vertebra, lumbar vertebra, proximal femur, mid femur and distal femur. Next, osteopenia rats in 275 nm irradiation group were UV irradiated 275 nm with fixed illumination intensity (15 μW/cm²) everyday for 16 weeks. The osteopenia rats in 310 nm irradiation group were UV irradiated 310 nm with fixed illumination intensity (15 μW/cm²) everyday for 16 weeks. The backs of the rats were shaved regularly as irradiation area (6 cm×8 cm). After 16-week irradiation, all the rats' BMD of cervical vertebra, lumbar vertebra, proximal femur, mid femur and distal femur were measured. At the end of the trial, all the rats' blood specimens were obtained and serum 25(OH)D, procollagen type Ⅰ N-peptide (PINP) and osteocalcin (OC) were measured. RESULTS: Compared with control group [(238.78±26.74) mg/cm³], the BMD of the whole body were significantly lower in 275 nm [(193.34±13.28) mg/cm³] and 310 nm [(191.19±18.48) mg/cm³] irradiation groups (P=0.002, P=0.001). There were no significant difference between sham operated group [(227.20±14.32) mg/cm³] and control group. After 16-week ultraviolet irradiation, the BMD of the whole body were significantly increased in 275 nm [(193.34±13.28) mg/cm³ vs. (221.68±25.52) mg/cm³, P=0.005] and 310 nm groups [(191.19±18.48) mg/cm³ vs. (267.48±20.54) mg/cm³, P < 0.001] after corresponding irradiation. The BMD of the four body regions (lumbar vertebra, proximal femur, mid femur and distal femur) had significantly increased after irradiation in 275 nm irradiation group. For 310 nm irradiation group, the BMD in cervical vertebra, lumbar vertebra, proximal femur, mid femur and distal femur also had increased significantly after 310 nm ultraviolet irradiation. The concentration of serum 25(OH)D and OC was higher in 275 nm irradiation group than in control group [(46.78±5.59) μg/L vs. (21.32±6.65) μg/L, P=0.002;(2.05±0.53) U/L vs. (1.32±0.07) U/L, P=0.022]. Compared with the control, the concentration of serum 25(OH)D [(58.05±12.74) μg/L], OC [(2.04±0.53) U/L] and PINP [(176.16±24.18) U/L] was significantly higher (P < 0.001, P=0.015, P=0.005) in 310 nm irradiation group. However, there were no significantly difference between sham operated group and the control. CONCLUSION Both 275 nm and 310 nm ultraviolet could improve rats' vitamin D synthesis. Both 275 nm and 310 nm ultraviolet could improve osteopenia rats' bone condition. The irradiation of 310 nm might be more effective on bone condition improvement.
Animals ; Bone Density ; Bone Diseases, Metabolic/metabolism* ; Female ; Femur/metabolism* ; Humans ; Osteocalcin/metabolism* ; Ovariectomy ; Rats ; Rats, Sprague-Dawley

OBJECTIVES: To study the level of serum vitamin K₂ (VitK₂) and its association with bone metabolism markers osteocalcin (OC), type I procollagen amino-terminal peptide (PINP), and type I collagen carboxy-terminal peptide (CTX) in children. METHODS: A prospective analysis was performed on 1 732 children who underwent routine physical examination from October 2020 to October 2021. The serum levels of VitK₂ and 25-hydroxy vitamin D [25(OH)D] were measured. According to age, they were divided into four groups: <1 year, 1-3 years group, >3-6 years group, and >6-14 years. A total of 309 children with 25(OH)D≥50 nmol/L were screened out, and serum levels of OC, PINP, and CTX were measured to investigate the correlation of the serum levels of OC, PINP, and CTX with serum VitK₂ levels in different age groups. RESULTS: The prevalence rate of serum VitK₂ deficiency was 52.31% (906/1 732). The VitK₂ deficiency group had higher prevalence rates of overweight/obesity and growth pain (≥3 years of age) than the normal VitK₂ group (P<0.05). There were differences in the prevalence rate of serum VitK₂ deficiency (P<0.0083) and the serum level of VitK₂ (P<0.05) between the 1-3 years group and the >6-14 years group. The <1 year group had a higher serum level of CTX and a lower serum level of PINP than the >3-6 years group and the >6-14 years group (P<0.05). The <1 year group had a lower serum level of OC than the >6-14 years group (P<0.05). Serum VitK₂ level was positively correlated with OC level (r_s=0.347, P<0.01), and CTX level was negatively correlated with PINP level (r_s=-0.317, P<0.01). CONCLUSIONS Serum VitK₂ deficiency may be associated with overweight/obesity. Serum VitK₂ may affect the level of OC and even bone health.
Child ; Humans ; Infant ; Biomarkers/metabolism* ; Collagen Type I/metabolism* ; Obesity/complications* ; Osteocalcin/metabolism* ; Overweight/complications* ; Peptide Fragments/metabolism* ; Peptides/metabolism* ; Procollagen/metabolism* ; Vitamin K/blood* ; Child, Preschool ; Adolescent ; Bone and Bones/metabolism*

PURPOSE: Bone markers can be useful for the diagnosis and treatment of skeletal diseases in children and adolescents. Owing to high skeletal growth velocity and rapid bone turnover, children and adolescents have higher bone marker levels than adults. Thus, a valid age- and sex-specific reference should be established for pediatric populations living in similar environments. We aimed to assess the associations of procollagen type I N-terminal propeptide (P1NP) and osteocalcin with age and sex in a group of healthy Korean children and adolescents. MATERIALS AND METHODS: The participants (290 boys and 290 girls, age range 0–18 years) were Korean outpatients. Serum P1NP and osteocalcin levels were measured in control materials and patient samples by electrochemiluminescence immunoassay using an automated Cobas e411 analyzer. RESULTS: Significant age-dependent variations in bone marker levels were observed in both sexes (p<0.001). The highest P1NP levels were observed during the first year of life; thereafter, levels decreased until puberty. There was no postnatal peak for osteocalcin; however, its levels remained higher than the adult reference range throughout childhood. Significant differences were observed between boys and girls (p<0.05), especially between the ages of 12 and 17 years. Cobas e411 results for P1NP showed satisfactory precision and linearity. CONCLUSION: We established reference data for P1NP and osteocalcin levels in healthy Korean children and adolescents, as the first and only study of these parameters in pre-adulthood in Korea. Cobas e411-quantified bone markers may be useful for determining bone metabolism indices.
Adolescent ; Adult ; Bone Remodeling ; Child ; Collagen Type I ; Diagnosis ; Female ; Humans ; Immunoassay ; Korea ; Metabolism ; Osteocalcin ; Outpatients ; Procollagen ; Puberty ; Reference Values

Genetic studies have revealed a critical role of Distal-homeobox (Dlx) genes in bone formation, and our previous study showed that Dlx2 overexpressing in neural crest cells leads to profound abnormalities of the craniofacial tissues. The aim of this study was to investigate the role and the underlying molecular mechanisms of Dlx2 in osteogenic differentiation of mouse bone marrow stromal cells (BMSCs) and pre-osteoblast MC3T3-E1 cells. Initially, we observed upregulation of Dlx2 during the early osteogenesis in BMSCs and MC3T3-E1 cells. Moreover, Dlx2 overexpression enhanced alkaline phosphatase (ALP) activity and extracellular matrix mineralization in BMSCs and MC3T3-E1 cell line. In addition, micro-CT of implanted tissues in nude mice confirmed that Dlx2 overexpression in BMSCs promoted bone formation in vivo. Unexpectedly, Dlx2 overexpression had little impact on the expression level of the pivotal osteogenic transcription factors Runx2, Dlx5, Msx2, and Osterix, but led to upregulation of Alp and Osteocalcin (OCN), both of which play critical roles in promoting osteoblast maturation. Importantly, luciferase analysis showed that Dlx2 overexpression stimulated both OCN and Alp promoter activity. Through chromatin-immunoprecipitation assay and site-directed mutagenesis analysis, we provide molecular evidence that Dlx2 transactivates OCN and Alp expression by directly binding to the Dlx2-response cis-acting elements in the promoter of the two genes. Based on these findings, we demonstrate that Dlx2 overexpression enhances osteogenic differentiation in vitro and accelerates bone formation in vivo via direct upregulation of the OCN and Alp gene, suggesting that Dlx2 plays a crucial role in osteogenic differentiation and bone formation.
Animals ; Cell Differentiation ; physiology ; Core Binding Factor Alpha 1 Subunit ; Homeodomain Proteins ; metabolism ; Mesenchymal Stem Cells ; metabolism ; Mice ; Mice, Nude ; Osteoblasts ; metabolism ; Osteocalcin ; drug effects ; Osteogenesis ; physiology ; Transcription Factors ; metabolism ; Up-Regulation

OBJECTIVE: The purpose of this study is to investigate the potential effects of sclerostin (SOST) on the biological funtions and related mechanisms of cementoblasts under mechanical stress. METHODS: OCCM-30 cells were treated with varying doses of SOST (0, 25, 50, and 100 ng·mL⁻¹) and were loaded with uniaxial compressive stress (2 000 μ strain with a frequency of 0.5 Hz) for six hours. Western blot was utilized to detect the expressions of β-catenin, p-smad1/5/8, and smad1/5/8 proteins. Alkaline phosphatase (ALP) activity was determined, and reverse transcription polymerase chain reaction was used to measure the expressions of runt-related transcription factor 2 (Runx-2), osteocalcin (OCN), bone sialoproteins (BSP), receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) mRNA. RESULTS: The expression of p-smad
1/5/8 was significantly downregulated with increasing SOST. β-catenin and smad1/5/8 exhibited no difference. ALP activity decreased under mechanical compressive stress with increasing SOST concentrations. Runx-2 expression was reduced with increasing SOST concentrations, and a similar trend was observed for the BSP and OCN expressions. When the SOST concentration was enhanced, RANKL expression gradually increased, whereas the expression of OPG decreased. CONCLUSIONS Under mechanical comprehensive stress, SOST can adjust the bone morphogenetic protein (BMP) /smad signal pathway. Osteosclerosis inhibits the mineralization of cementoblasts under mechanical compressive stress, which may be achieved by inhibiting the expressions of osteogenesis factors (Runx2, OCN, BSP, and others) and by promoting the ratio of cementoclast-related factors (RANKL/OPG) through BMP signal pathways.
Bone Morphogenetic Proteins ; metabolism ; Core Binding Factor Alpha 1 Subunit ; Dental Cementum ; Osteocalcin ; Smad Proteins ; metabolism ; Stress, Mechanical

To investigate the preventive effect and possible mechanism of puerarin(Pur) in rat model of disuse osteoporosis(DOP),thirty healthy Wistar female rats of 2 months old were randomly divided into control group(Control), hindlimb suspension group(HLS), and puerarin group(HLS+Pur) in hindlimb suspension, with 10 rats in each group. A disuse osteoporosis model was established by tail suspension method, and 15.4 mg·kg~(-1) puerarin suspension was administered to HLS+Pur group every day, and the same volume of distilled water was administered to Control group and HLS group respectively. After 28 days, the rats were sacrificed by abdominal aorta blood collection, the main organs of the rats were removed, and the bone tissues of the rats were dissected. The organ index of the rats was calculated and the histopathology of the organs was observed under microscope. Bone mineral density test and bone biomechanical experiment were performed. Bone histomorphometry results were observed after bone tissue sectioning, and serum biochemical markers of bone metabolism were determined. There was no significant difference in organ index between the groups. There was no obvious abnormality in the pathological examination of the organs. The results of bone mineral density showed that puerarin could significantly increase the bone density of the tibia and vertebrae caused by hindlimb suspension. The mechanical parameters experiments showed that puerarin could effectively increase the maximum load and elastic modulus of the tibia and vertebrae. Fluorescence labeling showed that the fluorosis interval increased and the bone formation increased during puerarin treatment. The VG staining results showed that compared with the HLS group, in the puerarin group, the number of trabecular bone increased, the thickness of the trabecular bone became thicker, and the bone separation became smaller, which greatly improved the bone microstructure after hindlinb suspension. In addition, serum biochemical indicators showed that puerarin could promote bone formation index bone calcium. The content of osteocalcin(OC) increased and inhibited the formation of tartrate-resistant acid phosphatase 5 b(TRACP 5 b). Puerarin has a preventive effect in the rat model of disuse osteoporosis and its effect is good, and its mechanism may be related to promoting bone formation and inhibiting bone resorption.
Animals ; Bone Density ; Female ; Isoflavones ; pharmacology ; Osteocalcin ; metabolism ; Osteoporosis ; drug therapy ; Rats ; Rats, Wistar ; Tartrate-Resistant Acid Phosphatase ; metabolism

OBJECTIVES: The objective of the study was to determine whether postburn reduction of bone formation occurred earlier than 2–3 weeks after burn injury and whether that reduction was inversely related to marrow adiposity. METHODS: Using a rat model of burn injury with sacrifice at 3 days postburn, we measured serum osteocalcin, a biomarker of bone formation, as well as a regulator of glucose metabolism, and counted tibial marrow adipocytes. RESULTS: Serum osteocalcin was reduced as early as 3 days postburn, coinciding with a trend toward decline in marrow adipocyte number rather than demonstrating an inverse relationship with adipocyte count. CONCLUSIONS: Factors that may be responsible for the dissociation include lack of circulating sclerostin, previously reported, increased energy demands following burn injury, increased sympathetic tone and perhaps oxidative stress. The relationship between bone formation and marrow adiposity is complex and subject to a variety of influences.
Adipocytes ; Adiposity ; Animals ; Bone Marrow ; Burns ; Child ; Glucose ; Humans ; Metabolism ; Models, Animal ; Osteocalcin ; Osteogenesis ; Oxidative Stress ; Rats

PURPOSE: Bone plays a role in glucose metabolism through the release of uncarboxylated osteocalcin into the systemic circulation. The identified novel roles for osteocalcin include increasing insulin secretion and sensitivity, energy expenditure, reduction of fat mass, and mitochondrial proliferation and functional enhancement. This study aimed to determine serum osteocalcin levels in overweight children and to investigate the relationships of osteocalcin with glucose metabolism and insulin sensitivity. METHODS: After overnight fasting, serum osteocalcin levels were measured in overweight (n=50) children between 6.0 and 12.9 years of age and nonoverweight controls (n=60). Height, weight, fasting serum glucose, insulin, alkaline phosphatase, total cholesterol, and 25 hydroxy vitamin D₃ (25(OH)VitD₃) were also measured in all subjects. RESULTS: There were significant differences in serum osteocalcin levels between the overweight and control groups (64.00±20.44 vs. 89.56±28.63, P<0.001). Serum osteocalcin levels were inversely correlated with body mass index (BMI) (r=-0.283, P=0.003), weight standard deviation score (SDS) (r=-0.222, P=0.020), BMI SDS (r=-0.297, P=0.002), insulin (r=-0.313, P=0.001), and homeostasis model assessment of insulin resistance (HOMA-IR) index (r=-0.268, P=0.005). In the subsequent multiple regression analyses, BMI, HOMA-IR, and age were determined to be independent predicting factors for serum osteocalcin. CONCLUSIONS: Our findings showed associations of serum osteocalcin with glucose metabolism and insulin sensitivity in overweight children, but we could not establish a causal relationship.
Alkaline Phosphatase ; Blood Glucose ; Body Mass Index ; Child ; Cholesterol ; Energy Metabolism ; Fasting ; Glucose ; Homeostasis ; Humans ; Insulin ; Insulin Resistance ; Metabolism ; Osteocalcin ; Overweight ; Vitamins