Nystose attenuates bone loss and promotes BMSCs differentiation to osteoblasts through BMP and Wnt/β-catenin pathway in ovariectomized mice

Increasing the osteogenic differentiation ability and decreasing the adipogenic differentiation ability of bone marrow mesenchymal stem cells(BMSCs)is a potential strategy for the treatment of osteoporosis(OP).Naturally derived oligosaccharides have shown significant anti-osteoporotic effects.Nystose(NST),an oligosaccharide,was isolated from the roots of Morinda officinalis How.(MO).The aim of the present study was to investigate the effects of NST on bone loss in ovariectomized mice,and explore the underlying mechanism of NST in promoting differentiation of BMSCs to osteoblasts.Administration of NST(40,80 and 160 mg/kg)and the positive control of estradiol valerate(0.2 mg/kg)for 8 weeks significantly prevented bone loss induced by ovariectomy(OVX),increased the bone mass density(BMD),improved the bone microarchitecture and reduced urine calcium and deoxypyridinoline(DPD)in ovariectomized mice,while inhibited the increase of body weight without significantly affecting the uterus weight.Furthermore,we found that NST increased osteogenic differentiation,inhibited adipogenic differentiation of BMSCs in vitro,and upregulated the expression of the key proteins of BMP and Wnt/β-catenin pathways.In addition,Noggin and Dickkopf-related protein-1(DKK-1)reversed the effect of NST on osteogenic differentiation and expression of the key proteins in BMP and Wnt/β-catenin pathway.The luciferase activities and the molecular docking analysis further supported the mechanism of NST.In conclusion,these results indicating that NST can be clinically used as a potential alternative medicine for the prevention and treatment of postmenopausal osteoporosis.

Effects of areca nut consumption on cell differentiation of osteoblasts, myoblasts, and fibroblasts

Areca nut is used worldwide as a hallucinogenic addicting drug along the tropical belt.Arecoline,a toxic compound,is the most important alkaloid in areca nuts.The adverse effects of oral uptake and chewing of areca nut are well known.For example,the possibility of cancer caused by chewing areca nuts is widely discussed.Chewing areca nut has other adverse effects on other organs,including abnormal cell differentiation,oral cancer,and several other diseases.The use of areca nut is also associated with low birthweight.Skeletal musculature is the largest organ in the body and is attached to the bones.During embryo development,the differentiation of bone and muscle cells is critical.In this article,we reviewed the effects of areca nut and arecoline on embryonic cell differentiation,particularly osteoblasts,myoblasts,and fibroblasts.

Lipolysis supports bone formation by providing osteoblasts with endogenous fatty acid substrates to maintain bioenergetic status

Bone formation is a highly energy-demanding process that can be impacted by metabolic disorders.Glucose has been considered the principal substrate for osteoblasts,although fatty acids are also important for osteoblast function.Here,we report that osteoblasts can derive energy from endogenous fatty acids stored in lipid droplets via lipolysis and that this process is critical for bone formation.As such,we demonstrate that osteoblasts accumulate lipid droplets that are highly dynamic and provide the molecular mechanism by which they serve as a fuel source for energy generation during osteoblast maturation.Inhibiting cytoplasmic lipolysis leads to both an increase in lipid droplet size in osteoblasts and an impairment in osteoblast function.The fatty acids released by lipolysis from these lipid droplets become critical for cellular energy production as cellular energetics shifts towards oxidative phosphorylation during nutrient-depleted conditions.In vivo,conditional deletion of the ATGL-encoding gene Pnpla2 in osteoblast progenitor cells reduces cortical and trabecular bone parameters and alters skeletal lipid metabolism.Collectively,our data demonstrate that osteoblasts store fatty acids in the form of lipid droplets,which are released via lipolysis to support cellular bioenergetic status when nutrients are limited.Perturbations in this process result in impairment of bone formation,specifically reducing ATP production and overall osteoblast function.

Effects of acupotomy on the activity of osteoclasts and osteoblasts in the subchondral bone of rabbits with early and mid-stage knee osteoarthritis models

Objective:To investigate whether acupotomy could inhibit subchondral bone remodeling in knee osteoarthritis(KOA)rabbits by regulating the activity of osteoblasts and osteoclasts.Methods:KOA rabbits were prepared by immobilization for 6 and 9 weeks by Videman method.Nine groups of rabbits(control,6 weeks and 9 weeks model,6 weeks and 9 weeks acupotomy,6 weeks and 9 weeks electroacupuncture,and 6 weeks and 9 weeks drug groups)received acupotomy,electroacupuncture and risedronate sodium intervention,respectively,for 3 weeks.Results:Acupotomy can inhibit the activity of osteoclasts and osteoblasts in subchondral bone by reducing the proteins expression of cathepsin K(CK)and tartrate-resistant acid phosphatase(TRAP)and decreasing the proteins expression of osteocalcin(OCN)and alkaline phosphatase(ALP),to intercept the abnormal bone resorption and bone formation of subchondral bone in 6-week and 9-week immobilization-induced KOA rabbits.Conclusion:These findings indicated that acupotomy may be more advantageous than risedronate sodium intervention in modulating subchondral bone remodeling in KOA rabbits,especially in 9-week immobilization-induced KOA rabbits.

The water-soluble TF3 component from Eupolyphaga sinensis Walker promotes tibial fracture healing in rats by promoting osteoblast proliferation and angiogenesis

Objective:To determine the active components of Eupolyphaga sinensis Walker(Tu Bie Chong)and explore the mechanisms underlying its fracture-healing ability.Methods: A modified Einhorn method was used to develop a rat tibial fracture model.Progression of bone healing was assessed using radiological methods.Safranin O/fast green and CD31 immunohistochemical staining were performed to evaluate the growth of bone cells and angiogenesis at the fracture site.Methylthiazoletetrazolium blue and wound healing assays were used to analyze cell viability and migration.The Transwell assay was used to explore the invasion capacity of the cells.Tubule formation assays were used to assess the angiogenesis capacity of human vascular endothelial cells(HUVECs).qRT-PCR was used to evaluate the changes in gene transcription levels.Results: Tu Bie Chong fraction 3(TF3)significantly shortened the fracture healing time in model rats.X-ray results showed that on day 14,fracture healing in the TF3 treatment group was significantly better than that in the control group(P=.0086).Tissue staining showed that cartilage growth and the number of H-shaped blood vessels at the fracture site of the TF3 treatment group were better than those of the control group.In vitro,TF3 significantly promoted the proliferation and wound healing of MC3T3-E1s and HUVECs(all P<.01).Transwell assays showed that TF3 promoted the migration of HUVECs,but inhibited the migration of MC3T3-E1 cells.Tubule formation experiments confirmed that TF3 markedly promoted the ability of vascular endothelial cells to form microtubules.Gene expression analysis revealed that TF3 significantly promoted the expression of VEGFA,SPOCD1,NGF,and NGFR in HUVECs.In MC3T3-E1 cells,the transcript levels of RUNX2 and COL2A1 were significantly elevated following TF3 treatment.Conclusion: TF3 promotes fracture healing by promoting bone regeneration associated with the RUNX2 pathway and angiogenesis associated with the VEGFA pathway.

Polycytosine RNA-binding protein 1 regulates osteoblast function via a ferroptosis pathway in type 2 diabetic osteoporosis

BACKGROUND Recently,type 2 diabetic osteoporosis(T2DOP)has become a research hotspot for the complications of diabetes,but the specific mechanism of its occurrence and development remains unknown.Ferroptosis caused by iron overload is con-sidered an important cause of T2DOP.Polycytosine RNA-binding protein 1(PCBP1),an iron ion chaperone,is considered a protector of ferroptosis.AIM To investigate the existence of ferroptosis and specific role of PCBP1 in the development of type 2 diabetes.METHODS A cell counting kit-8 assay was used to detect changes in osteoblast viability under high glucose(HG)and/or ferroptosis inhibitors at different concentrations and times.Transmission electron microscopy was used to examine the morpho-logical changes in the mitochondria of osteoblasts under HG,and western blotting was used to detect the expression levels of PCBP1,ferritin,and the ferroptosis-related protein glutathione peroxidase 4(GPX4).A lentivirus silenced and overex-pressed PCBP1.Western blotting was used to detect the expression levels of the osteoblast functional proteins osteoprotegerin(OPG)and osteocalcin(OCN),whereas flow cytometry was used to detect changes in reactive oxygen species(ROS)levels in each group.RESULTS Under HG,the viability of osteoblasts was considerably decreased,the number of mitochondria undergoing atrophy was considerably increased,PCBP1 and ferritin expression levels were increased,and GPX4 expression was decreased.Western blotting results demonstrated that infection with lentivirus overexpressing PCBP1,increased the expression levels of ferritin,GPX4,OPG,and OCN,compared with the HG group.Flow cytometry results showed a reduction in ROS,and an opposite result was obtained after silencing PCBP1.CONCLUSION PCBP1 may protect osteoblasts and reduce the harm caused by ferroptosis by promoting ferritin expression under a HG environment.Moreover,PCBP1 may be a potential therapeutic target for T2DOP.

Paracrine and endocrine actions of bone——the functions of secretory proteins from osteoblasts, osteocytes, and osteoclasts

The skeleton is a dynamic organ that is constantly remodeled. Proteins secreted from bone cells, namely osteoblasts, osteocytes,and osteoclasts exert regulation on osteoblastogenesis, osteclastogenesis, and angiogenesis in a paracrine manner. Osteoblasts secrete a range of different molecules including RANKL/OPG, M-CSF, SEMA3A, WNT5A, and WNT16 that regulate osteoclastogenesis. Osteoblasts also produce VEGFA that stimulates osteoblastogenesis and angiogenesis. Osteocytes produce sclerostin（SOST） that inhibits osteoblast differentiation and promotes osteoclast differentiation. Osteoclasts secrete factors including BMP6, CTHRC1, EFNB2, S1P, WNT10B, SEMA4D, and CT-1 that act on osteoblasts and osteocytes, and thereby influencea A osteogenesis. Osteoclast precursors produce the angiogenic factor PDGF-BB to promote the formation of Type H vessels, which then stimulate osteoblastogenesis. Besides, the evidences over the past decades show that at least three hormones or ＂osteokines＂from bone cells have endocrine functions. FGF23 is produced by osteoblasts and osteocytes and can regulate phosphate metabolism. Osteocalcin（OCN） secreted by osteoblasts regulates systemic glucose and energy metabolism, reproduction, and cognition. Lipocalin-2（LCN2） is secreted by osteoblasts and can influence energy metabolism by suppressing appetite in the brain.We review the recent progresses in the paracrine and endocrine functions of the secretory proteins of osteoblasts, osteocytes, and osteoclasts, revealing connections of the skeleton with other tissues and providing added insights into the pathogenesis of degenerative diseases affecting multiple organs and the drug discovery process.

Modulation of Isoflavones on Bone-nodule Formation in Rat Calvaria Osteoblasts in vitro

Objective To observe the effects of two main isoflavones, daidzein and genistein on the bone-nodule formation in rat calvaria osteoblasts in vitro. Methods Osteoblasts obtained from newborn Sprague-dawley rat calvarias were cultured for several generations. The second generation cells were cultured in Minimum Essential Medium supplemented with ascorbic acid and Na-beta-glycerophosphate for several days, in the presence of daidzein and genistein, with or without the estrogen receptor antagonist ICI 182780. Number of nodules was counted at the end of the incubation period (day 20) by staining with Alizarin Red S calcium stain. The release of osteocalcin, as a marker of osteoblast activity, was also determined on day 7 and day 12 during the incubation period. Results Compared with the control, the numbers of nodules were both increased by incubation with daidzein and genistein. 17β-estradiol was used as a positive control and proved to be a more effective inducer of the increase in bone-nodules formation than daidzein and genistein. The release of osteocalcin into culture media was also increased in the presence of daidzein and genistein, as well as 17β-estradiol on day 7 and day 12 (day 12 were higher). The estrogen receptor antagonist ICI 182780 completely blocked the genistein- and 17β-estradiol-induced increase of nodule numbers and osteocalcin release in osteoblasts. However, the effects induced by daidzein could not be inhibited by ICI 182780. Conclusion These findings suggest that geinistein can stimulate bone-nodule formation and increase the release of osteocalcin in rat osteoblasts. The effects, like those induced by 17β-estradiol, are mediated by the estrogen receptor dependent pathway. Daidzein also can stimulate bone-nodule formation and increase the release of osteocalcin in rat osteoblasts, but it is not, at least not merely, mediated by the estrogen receptor dependent pathway.

Interaction between Schwann Cells and Osteoblasts In Vitro

Aim Given the well-known properties of Schwann cells in promoting nerve regeneration, transplanting Schwann cells into implant sockets might be an effective method to promote sensory responses of osseointegrated implants. The aim of this study was to evaluate the interaction between Schwann cells and osteoblasts. Methodology Schwann cells derived from the sciatic nerves of neonatal rat were co-culured with osteoblasts using Transwell inserts. The proliferation of Schwann cells in the co-culture system was evaluated using methylthiazol tetrazolium （MTT） colorimetric method. Moreover, the secretions and mRNA levels of brain-derived neurotrophic factor （BDNF） and nerve growth factor （NGF） were measured by enzyme-linked immunosorbent assay （ELISA） and quantitative real-time PCR, respectively. In order to test the effect of Schwann cells on osteoblasts, alkaline phosphatase （ALP） staining and Alizerin red staining were performed as well. Results Schwann cells, which were co-cultured with the osteoblasts, showed an intact proliferation during the observation period. Moreover, the gene expression and synthesis of BDNF and NGF were not impaired by the osteoblasts. Meanwhile, co-cultured osteoblasts exhibited a significant increase in the proliferation on day 3 and 6 （P〈 0.05）. Co-culture of these two types of cells also led to a more intense staining of ALP and an elevated number of calcified nodules. Conclusion These findings demonstrate that, in the in vitro indirect co-culture environment, Schwann cells can maintain their normal ability to synthesize neurotrophins, which then enhance the proliferation and differentiation of osteoblasts.

New roles of osteoblasts involved in osteoclast differentiation

Bone-resorbing osteoclasts are formed from a monocyte/macrophage lineage under the strict control o bone-forming osteoblasts. So far,macrophage colonystimulating factor(M-CSF),receptor activator o nuclear factor-κB ligand(RANKL),and osteoprotegerin(OPG) produced by osteoblasts play major roles in the regulation of osteoclast differentiation. Recent studies have shown that osteoblasts regulate osteoclastogenesis through several mechanisms independent o M-CSF,RANKL,and OPG production. Identification o osteoclast-committed precursors in vivo demonstrated that osteoblasts are involved in the distribution o osteoclast precursors in bone. Interleukin 34(IL-34)a novel ligand for c-Fms,plays a pivotal role in maintaining the splenic reservoir of osteoclast-committed precursors in M-CSF deficient mice. IL-34 is also able to act as a substitute for osteoblast-producing M-CSF in osteoclastogenesis. Wnt5 a,produced by osteoblasts,enhances osteoclast differentiation by upregulating RANK expression through activation of the noncanonical Wnt pathway. Semaphorin 3A produced by osteoblasts inhibits RANKL-induced osteoclast differentiation through the suppression of immunoreceptortyrosine-based activation motif signals. Thus,recent findings show that osteoclast differentiation is tightly regulated by osteoblasts through several different mechanisms. These newly identified molecules are expected to be promising targets of therapeutic agents in bone-related diseases.

Three-dimensional Expansion:In Suspension Culture of SD Rat's Osteoblasts in a Rotating Wall Vessel Bioreactor

Objective To study large-scale expansion of SD （Sprague-Dawley） rat＇s osteoblasts in suspension culture in a rotating wall vessel bioreactor （RWVB）. Methods The bioreactor rotation speeds were adjusted in the range of 0 to 20 rpm, which could provide low shear on the rnicrocarriers around 1 dyn/cm^2. The cells were isolated via sequential digestions of neonatal （less than 3 days old） SD rat calvaria. After the primary culture and several passages, the cells were seeded onto the microcarriers and cultivated in T-flask, spinner flask and RWVB respectively. During the culture period, the cells were counted and observed under the inverted microscope for morphology every 12 h. After 7 days, the cells were evaluated with scanning electron microscope （SEM） for histological examination of the aggregates. Also, the hematoxylin-eosin （HE） staining and alkaline phosphatase （ALP） staining were performed. Moreover, von-Kossa staining and Alizarin Red S staining were carded out for mineralized nodule formation. Results The results showed that in RWVB, the cells could be expanded by more than ten times and they presented better morphology and vitality and stronger ability to form bones. Conclusions The developed RWVB can provide the culture environment with a relatively low shear force and necessary three-dimensional （3D） interactions among cells and is suitable for osteopath expansion in vitro.

Cloning and Expression of Rat Transforming Growth Factor β1 cDNA in Osteoblasts

Summary: Rat transforming growth factor β1 (rTGFβ1) cDNA from rat lymphocytes was cloned by RT-PCR and inserted into pcDNA3 to construct an eukaryotic expression vector, which was named pcDNA3-TGFβ1. The cloned gene was confirmed to code rat TGFβ1 by restriction enzyme analysis. pcDNA3-TGFβ1 plasmid was transfected into rat osteoblasts by using liposome-mediated gene transfer technique and the expression of TGFβ1 was detected by using irnmunohistochemical staining assay. It was found that the rat TGFβ1 expression product was obviously detectable in the transfected osteoblasts in 48 h. High expression of TGFβ1 was obtained in the rat osteoblasts in which the constructed TGFβ1 expression vector was transfected.

Effects of Lanthanum on Bone Resorbing Activity of Rabbit Mature Osteoclasts Co-Cultured with Osteoblasts

The effects of lanthanum （Ⅲ） on the bone resorbing activity of rabbit mature osteoclasts （OCs） in the presence of osteoblasts （OBs） were studied in vitro by measuring the number and area of absorption pits. La（ Ⅲ ） at concentrations ranging from 1.00 × 10^-5 to 1.00 × 10^-8 mol·L^-1 show no effect on mature OC number （P 〉 0.05）. In the OC-OB coculture systems without La（Ⅲ ）, osteoblasts alone did not influence the pit number and area whether the two kinds of cells were in contact or not （ P 〉 0.05）. Under the OC-OB not-in-contact condition, the effect of La（ Ⅲ ） on the bone-resorbing activity of OCs was similar to that of La（Ⅲ） in the absence of OBs （P 〉 0.05）. However, while OCs were in direct contact with OBs, the inhibitory effects of La（ Ⅲ ） on OCs＇ bone-resorbing activity decreased at the concentrations of 1.00 × 10^-5, 1.00×10^-6 and 1.00×10^-7mol·L^-1, and the promotion effects increased at 1.00×10^-8mol·L^-1 （P 〈0.05）. The results suggest that direct cell-cell contact between OC and OB be essential for OBs to play their role in regulating the response of OCs to La（ Ⅲ ）.

NUMB maintains bone mass by promoting degradation of PTEN and GLI1 via ubiquitination in osteoblasts

The adaptor protein NUMB is involved in asymmetric division and cell fate determination and recognized as an antagonist of Notch.Previous studies have proved that Notch activation in osteoblasts contributes to a high bone mass. In this study, however, an osteopenic phenotype was found in 9-week-old mice using osteoblastic specific Col1a1–2.3-Cre to ablate both Numb and its homologue Numbl. The trabecular bone mass decreased dramatically while the cortical bone mass was unaffected. Here, the Notch signal was not activated,while the tensin homologue deleted on human chromosome 10(PTEN), which dephosphorylates phosphatidylinositide 3-kinases, was elevated, attenuating protein kinase B(Akt). The ubiquitination assay revealed that NUMB may physiologically promote PTEN ubiquitination in the presence of neural precursor cell-expressed developmentally downregulated protein 4–1. In addition, the deficiency of Numb/Numbl also activated the Hedgehog pathway through GLI1. This process was found to improve the ratio of the receptor activator of nuclear factor-k B ligand to osteoprotegerin, which enhanced the differentiation of osteoclasts and bone resorption. In conclusion, this study provides an insight into new functons of NUMB and NUMBL on bone homeostasis.

Increased Expression of Receptor Activator of Nuclear Factor-κB Ligand in Osteoblasts from Adolescent Idiopathic Scoliosis Patients with Low Bone Mineral Density

Persistent generalized low bone mineral density (BMD) has been reported in patients with adolescent idiopathic scoliosis (AIS).However,the exact mechanisms and causes of the low BMD in AIS patients are largely unknown.The purpose of this study was to examine the relationship between the receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG) levels in osteoblasts (OBs) from AIS patients with low BMD and with comparison made between the patients and controls.Twenty AIS patients and eight age-matched controls were included in the present study.The BMD of lumbar spine and proximal femur was measured in all subjects.OBs from the cancellous bone of each subject was harvested and primarily cultured.The mRNA and protein expression of RANKL and OPG in OBs was detected by RT-PCR and Western blotting.The results showed BMD was lower in AIS patients than in controls.A significantly higher mRNA and protein expression of RANKL was observed in OBs from AIS patients,while no significant difference was found in the expression of OPG between AIS patients and controls.As a result,RANKL/OPG ratio in patients with AIS was remarkably higher than controls.Our study preliminarily demonstrated expression of RANKL was higher in OBs from AIS patients with low BMD as compared with controls,suggesting the unbalanced RANKL/OPG ratio caused by an over-expression of RANKL in OBs may be responsible for the low BMD in AIS patients.

Effects of Icariin on Expression of OPN mRNA and Type ⅠCollagen in Rat Osteoblasts in Vitro

To study the effects of Icariin on expression of osteopontin （OPN） mRNA and type Ⅰ collagen in rat osteoblasts in vitro and to explore its possible mechanisms in preventing osteoporosis. OB was isolated from calvaria of new-born new-born fetal Sprague-Dawley （SD） rats by means of modified sequential collagenase digestion and incubated in MEM medium and the cell morphology was observed under inverted phase contrast microscope, OB was identified by alkaline phosphatase （ALP） staining. Different concentration （0.1μg/mL, 1.0 μg/mL, 10 μ/mL） of Icariin was added to the OB and incubated. The effect of Icariin on the proliferation and osteogenesis of OB was monitored by MTT analysis. The expression of type l collagen was estimated with immunohistochemistry techniques. The expression levels of mRNA of OPN in the cells in every group were examined by reverse-transcriptase ploymerase chain reaction （RT-PCR）. The expression of OPN mRNA and type Ⅰ collagen was strengthened gradually with the increase of Icariin concentration and peaked with 10 μg/mL Icariin on the 5th day. Icariin could significantly promote the expression of OPN mRNA and type Ⅰ collagen in rat osteoblasts in vitro. The levels of expression of OPN mRNA and type Ⅰ collagen were changed with different concentration of Icariin. Icariin could effectively prevent and treat osteoporosis and promote the bone formation.

Osteogenic Differentiation of Bone Mesenchymal Stem Cells Regulated by Osteoblasts under EMF Exposure in a Co-culture System

This study examined the osteogenic effect of electromagnetic fields （EMF） under the simulated in vivo conditions. Rat bone marrow mesenchymal stem cells （BMSCs） and rat osteoblasts were co-cultured and exposed to 50 Hz, 1.0 mT EMF for different terms. Unexposed single-cultured BMSCs and osteoblasts were set as controls. Cell proliferation features of single-cultured BMSCs and osteoblasts were studied by using a cell counting kit （CCK-8）. For the co-culture system, cells in each group were randomly chosen for alkaline phosphatase （ALP） staining on the day 7. When EMF exposure lasted for 14 days, dishes in each group were randomly chosen for total RNA extraction and von Kossa staining. The mRNA expression of osteogenic markers was detected by using real-time PCR. Our study showed that short-term EMF exposure （2 h/day） could obviously promote prolifera- tion of BMSCs and osteoblasts, while long-term EMF （8 h/day） could promote osteogenic differen- tiation significantly under co-cultured conditions. Under EMF exposure, osteogenesis-related mRNA expression changed obviously in co-cultured and single-cultured cells. It was noteworthy that most osteogenic indices in osteoblasts were increased markedly after co-culture except Bmp2, which was increased gradually when ceils were exposed to EMF. Compared to other indices, the expression of Bmp2 in BMSCs was increased sharply in both single-cultured and co-cultured groups when they were exposed to EMF. The mRNA expression of Bmp2 in BMSCs was approximately four times higher in 8-h EMF group than that in the unexposed group. Our results suggest that Bmp2-mediated cellular interaction induced by EMF exposure might play an important role in the osteogenic differ- entiation of BMSCs.

The heterodimeric structure of heterogeneous nuclear ribonucleoprotein C1/C2 dictates 1,25-dihydroxyvitamin D-directed transcriptional events in osteoblasts

Heterogeneous nuclear ribonucleoprotein （hnRNP） C plays a key role in RNA processing but also exerts a dominant negative effect on responses to 1,25-dihydroxyvitamin D （1,25（OH）2D） by functioning as a vitamin D response element-binding protein （VDRE-BP）. hnRNPC acts a tetramer of hnRNPC1 （huC1） and hnRNPC2 （huC2）, and organization of these subunits is critical to in vivo nucleic acid-binding. Overexpression of either huC1 or huC2 in human osteoblasts is sufficient to confer VDRE-BP suppression of 1,25（OH）2D-mediated transcription. However, huC1 or huC2 alone did not suppress 1,25（OH）2D-induced transcription in mouse osteoblastic cells. By contrast, overexpression of huC1 and huC2 in combination or transfection with a bone-specific polycistronic vector using a ＂self-cleaving＂ 2A peptide to co-express huC1/C2 suppressed 1,25D-mediated induction of osteoblast target gene expression. Structural diversity of hnRNPC between human/NWPs and mouse/rat/rabbit/dog was investigated by analysis of sequence variations within the hnRNP CLZ domain. The predicted loss of distal helical function in hnRNPC from lower species provides an explanation for the altered interaction between huC1/C2 and their mouse counterparts. These data provide new evidence of a role for hnRNPC1/C2 in 1,25（OH）2D-driven gene expression, and further suggest that species-specific tetramerization is a crucial determinant of its actions as a regulator of VDR-directed transactivation.

Gene expression profiles associated with osteoblasts differentiated from bone marrow stromal cells

Objective:To study the changes of gene expression profiles associated with osteoblasts differentiated from rat bone marrow stromal cells in vitro by gene chip technique.Methods:rat Rone marrow stromal cells were isolated and cultured,and differentiation was induced by dexamethasone,β-glycerol phosphate and vitamin C.Cellular mRNA was extracted and reverse transcribed into cDNA,thus related genes expression differences were detected by gene expression profile chip.Results:Calcifying nodules were visible in the induced cells.There were27.7%genes expressed differentially,three times more than the normal and induced cells,and some genes were related to transcription,translation,glycosylation modification.Extracellular matrix,signal molecules and metabolism were up—regulated.Conclusions:The gene chip technique can be used to detect the multi-gene different expression in the differentiationinduceed rat BMSCs,and these differentially expressed genes are necessary genes related to rat BMSCs proliferation and induction of osteoblastic differentiation.

Effect of cerium ion on the proliferation,differentiation and mineralization function of primary mouse osteoblasts in vitro

The effects of cerium ion(Ce3+) on the proliferation,differentiation,adipocytic transdifferentiation and mineralization function of primary mouse osteoblasts(OBs) were investigated.The results indicated that Ce3+ at all concentrations(1×10-9,1×10-8,1×10-7,1×10-6,1×10-5,and 1×10-4 mol/L) promoted the proliferation of osteoblasts(OBs).On day 1 and 3,Ce3+ promoted the differentiation of OBs at concentrations of 1×10-9,1×10-7,and 1×10-6 mol/L,but inhibited the differentiation of OBs at higher concentrations.On ...