Osteocalcin In MC3T3-E1 Cells Research Articles

LncRNA HAGLR accelerates femoral neck fracture healing through negatively regulating miRNA-19a-3p.

This study aims to uncover the function of long non-coding RNA (lncRNA) HAGLR in the healing process of femoral neck fracture and the underlying mechanism. Expression levels of HAGLR, microRNA-19a-3p (miRNA-19a-3p) and TGFBR2 in fractured femoral neck tissues and adjacent normal tissues were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Regulatory effects of HAGLR on viability, apoptosis, migration, and protein levels of BALP and Osteocalcin in MC3T3-E1 cells were determined. Dual-Luciferase reporter gene assay was conducted to assess the binding in HAGLR/miRNA-19a-3p/TGFBR2. In addition, relative levels of TGFBR2, p-smad2, p-smad3, and RUNX2 in MSCs influenced by HAGLR were detected. HAGLR was downregulated in fractured femoral neck tissues. Knockdown of HAGLR reduced viability and migration, enhanced apoptotic rate, as well as downregulated BALP and Osteocalcin in MC3T3-E1 cells. HAGLR served as miRNA-19a-3p sponge, and miRNA-19a-3p directly targeted 3'-untranslated region (3'-UTR) of TGFBR2. Knockdown of HAGLR downregulated expressions of TGFBR2, p-smad2, p-smad3, and RUNX2 in MC3T3-E1 cells, indicating the inhibited TGF-β pathway. LncRNA HAGLR/miRNA-19a-3p/TGFBR2 regulatory loop accelerates the healing process of femoral neck fracture by inhibiting the TGF-β pathway.

Osteogenesis effect of dynamic mechanical loading on MC3T3-E1 cells in three-dimensional printing biomimetic composite scaffolds

To observe the effect of dynamic mechanical loading on the proliferation, differentiation, and specific gene expression of MC3T3-E1 cells that on three-dimensional (3D) biomimetic composite scaffolds prepared by low temperature 3D printing technology combined with freeze-drying. The silk fibroin, collagen type Ⅰ, and nano-hydroxyapatite (HA) were mixed at a mass ratio of 3∶9∶2 and were used to prepare the 3D biomimetic composite scaffolds via low temperature 3D printing technology combined with freeze-drying. General morphology of 3D biomimetic composite scaffold was observed. Micro-CT was used to observe the pore size and porosity of the scaffolds, and the water swelling rate, stress, strain, and elastic modulus were measured. Then, the MC3T3-E1 cells were seeded on the 3D biomimetic composite scaffolds and the cell-scaffold composites were randomly divided into 2 groups. The experimental group was subjected to dynamic mechanical loading (3 500 με, 1 Hz, 15 minutes per day); the control group was not subjected to loading treatment. After 7 days and 14 days, the cell-scaffold composites of 2 groups were harvested to observe the growth of cells on the scaffolds by HE staining and scanning electron microscope. And the gene and protein expressions of collagen type Ⅰ, BMP-2, and osteocalcin (OCN) were measured by real-time fluorescent quantitative PCR and Western blot. The 3D biomimetic composite scaffold was a white cubic grid. Micro-CT detection showed the pore network structure in the scaffold material with good pore connectivity. The diameters of large pore and micro-aperture were (506.37±18.63) μm and (62.14±17.35) μm, respectively. The porosity was 97.70%±1.37%, and the water absorption swelling rate was 1 341.97%±64.41%. Mechanical tests showed that the compression displacement of the scaffold was (0.376±0.004) mm, the compressive stress was (0.016±0.002) MPa, and the elastic modulus was (162.418±18.754) kPa when the scaffold was compressed to 10%. At 7 days and 14 days, HE staining and scanning electron microscope observation showed that the cells grew inside the scaffold, mainly distributed around the scaffold pore wall. The cells in experimental group were more than control group, and the cells morphology changed from shuttle to flat. There was no significant difference in the cell counting between 2 groups at 14 days after 200-fold microscopy ( t=-2.024， P=0.080), but significant differences were found between 2 groups at different time points under different magnifications ( P<0.05). Real-time fluorescent quantitative PCR showed that the mRNA relative expressions of collagen type Ⅰ and OCN in experimental group were significantly higher than those in control group at 7 and 14 days ( P<0.05). However, the mRNA relative expression of BMP-2 showing no significant difference between 2 groups ( P>0.05). The protein relative expressions of collagen type Ⅰ, BMP-2, and OCN in experimental group were significantly higher than those in control group at 7 and 14 days ( P<0.05). After dynamic mechanical loading, the expressions of BMP-2, collagen type Ⅰ, and OCN in MC3T3-E1 cells inoculated into 3D biomimetic composite scaffolds are significantly up-regulated, indicating that appropriate mechanical loads favor osteoblast differentiation of MC3T3-E1 cells.

Ginsenoside Re Promotes Osteoblast Differentiation in Mouse Osteoblast Precursor MC3T3-E1 Cells and a Zebrafish Model.

Bone homeostasis is tightly regulated to balance bone formation and bone resorption. Many anabolic drugs are used as bone-targeted therapeutic agents for the promotion of osteoblast-mediated bone formation or inhibition of osteoclast-mediated bone resorption. Previous studies showed that ginsenoside Re has the effect of the suppression of osteoclast differentiation in mouse bone-marrow derived macrophages and zebrafish. Herein, we investigated whether ginsenoside Re affects osteoblast differentiation and mineralization in in vitro and in vivo models. Mouse osteoblast precursor MC3T3-E1 cells were used to investigate cell viability, alkaline phosphatase (ALP) activity, and mineralization. In addition, we examined osteoblastic signaling pathways. Ginsenoside Re affected ALP activity without cytotoxicity, and we also observed the stimulation of osteoblast differentiation through the activation of osteoblast markers including runt-related transcription factor 2, type 1 collagen, ALP, and osteocalcin in MC3T3-E1 cells. Moreover, Alizarin red S staining indicated that ginsenoside Re increased osteoblast mineralization in MC3T3-E1 cells and zebrafish scales compared to controls. These results suggest that ginsenoside Re promotes osteoblast differentiation as well as inhibits osteoclast differentiation, and it could be a potential therapeutic agent for bone diseases.

Icariin induced proliferation and differentiation of MC3T3-E1 osteoblasts via ERK and JNK signaling coupled with estrogen receptor

Objective To explore the detailed underlying molecular and signaling mechanisms in the effects of icariin on bone formation by an in vitro cell model. Methods The proliferation of MC3T3-E1 osteoblast-like cells was evaluated by MTT, and gene expression of cell cycle related proteins in MC3T3-E1 cells after icariin treatment was detected by real-time PCR. The phosphorylation of MAPK signals, including ERK, P38, and JNK was determined by Western blot, and then the inhibitors of MAPK signals were used to treat cells with icariin alone or together to determine the role of MAPKs in the process of icariin treatment on MC3T3-E1 cell proliferation. Alkaline phosphatase and Alizarin red staining were used to detect the formation of mineralization nodules, and gene expressions of alkaline phosphatase, type Ⅰ collagen, and osteocalcin in osteoblasts after being treated by icariin were evaluated by real-time PCR. ICI182780, and nilutamide was used to decide the participation of estrogen and androgen receptor signals in the process of icariin treatment on the differentiation and mineralization of MC3T3-E1 cells. Results Treatment with icariin promoted MC3T3-E1 cell growth in a time- and dose-dependent manner. This treatment also revealed that icariin increased the expression of mRNAs encoding both cyclin E and PCNA, positive regulators of cell growth, but decreased levels of mRNAs encoding Cdkn2b, a negative regulator of cell cycle progression. When MC3T3-E1 cells were cultured in a differentiated condition, icariin enhanced mineralized nodule formation and increased the expression of mRNAs encoding alkaline phosphatase, type Ⅰ collagen, and osteocalcin. Treatment with icariin significantly induced phosphorylation of both ERK and JNK and this phosphorylated effect occurred very rapidly within 5 minutes and reached peak at 15 minutes. Furthermore, the stimulated effects of icariin on proliferation and gene expression of cyclin E, PCNA, and Cdkn2b in MC3T3-E1 cells were dramatically attenuated by treatment with both U0126 and SP600125, inhibitors of MAPKs. Interestingly, such stimulating effects of icariin were at least partly reduced by treatment with ICI182780, an inhibitor of estrogen receptor. Icariin induced mineralized nodule formation and gene expression of alkaline phosphatase, type Ⅰ collagen, and osteocalcin in MC3T3-E1 cells were also partly reduced when the cells were treated with ICI182780. Conclusions Our findings indicate that the anabolic effect of icariin on bone formation is, at least partly, mediated through the MAPK signaling pathway in order to modulate osteoblast proliferation and differentiation. (Chin J Endocrinol Metab, 2015, 31: 148-154) Key words: Icariin; Osteoblasts; Estrogen receptor; Mitogen-activated protein kinase

(-)-Epigallocatechin gallate inhibits thyroid hormone‑stimulated osteocalcin synthesis in osteoblasts

It is recognized that catechin possesses beneficial properties for bone metabolism. We previously revealed that triiodothyronine (T₃)-activated p38 mitogen-activated protein (MAP) kinase, but not p44/p42 MAP kinase, is involved in the synthesis of osteocalcin in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of (-)-epigallocatechin gallate (EGCG), the predominant green tea polyphenol, on the synthesis of osteocalcin in MC3T3-E1 cells. EGCG significantly suppressed T₃-stimulated osteocalcin synthesis. The inhibitory effect of EGCG was dose-dependent in the range of 3 to 30 µM. On the other hand, T₃-induced phosphorylation of p38 MAP kinase was not affected by EGCG. EGCG profoundly inhibited T₃-stimulated transcriptional activity. These results strongly suggest that EGCG suppresses T3-stimulated osteocalcin synthesis upstream of the transcriptional level in osteoblast-like MC3T3-E1 cells.

Histone Deacetylase Inhibitors Promote Osteoblast Maturation

HDIs are potential therapeutic agents for cancer and neurological diseases because of their abilities to alter gene expression, induce growth arrest or apoptosis of tumors cells, and stimulate differentiation. In this report, we show that several HDIs promote osteoblast maturation in vitro and in calvarial organ cultures. Histone deacetylase inhibitors (HDIs) are currently in phase I and II clinical trials as anticancer agents. Some HDIs are also commonly prescribed treatments for epilepsy and bipolar disorders. Although administered systemically, the effects of HDIs on osteoblasts and bone formation have not been extensively examined. In this study, we investigated the effect of histone deacetylase inhibition on osteoblast proliferation and differentiation. MC3T3-E1 cells, calvarial-derived primary osteoblasts, and calvarial organ cultures were treated with various commercially available HDIs (trichostatin A [TSA], sodium butyrate [NaB], valproic acid [VPA], or MS-275). The effects of these inhibitors on cell proliferation, viability, cell cycle progression, Runx2 transcriptional activity, alkaline phosphatase production, and matrix mineralization were determined. Expression levels of osteoblast maturation genes, type I collagen, osteopontin, bone sialoprotein, and osteocalcin in response to TSA were measured by quantitative PCR. Concentrations of HDIs that caused hyperacetylation of histone H3 induced transient increases in osteoblast proliferation and viability but did not alter cell cycle profiles. These concentrations of HDIs also increased the transcriptional activity of Runx2. TSA accelerated alkaline phosphatase production in MC3T3-E1 cells and calvarial organ cultures. In addition, TSA accelerated matrix mineralization and the expression of osteoblast genes, type I collagen, osteopontin, bone sialoprotein, and osteocalcin in MC3T3-E1 cells. These studies show that histone deacetylase activity regulates osteoblast differentiation and bone formation at least in part by enhancing Runx2-dependent transcriptional activation. Therefore, HDIs are a potentially new class of bone anabolic agents that may be useful in the treatment of diseases that are associated with bone loss such as osteoporosis and cancer.

Melatonin Promotes Osteoblast Differentiation and Bone Formation

Prior studies have demonstrated that the pineal hormone, melatonin, can stimulate chloramphenicol acetyltransferase activity in Drosophila SL-3 cells transfected with a chloramphenicol acetyltransferase reporter construct containing the response element of rat bone sialoprotein (BSP). Based on these findings, studies were performed to determine whether melatonin could similarly modulate the expression of BSP in two cell lines, the MC3T3-E1(MC3T3) pre-osteoblast and rat osteoblast-like osteosarcoma 17/2.8 cell. Initial studies demonstrated that MC3T3 cells grown in the presence of 50 nM melatonin underwent cell differentiation and mineralization by day 12 instead of the 21-day period normally required for cells grown in untreated media. Melatonin increased gene expression of BSP and the other bone marker proteins, including alkaline phosphatase (ALP); osteopontin; secreted protein, acidic and rich in cysteine; and osteocalcin in MC3T3 cells in a concentration-dependent manner. Levels of melatonin as low as 10 nM were capable of stimulating transcription of these genes when cells were grown in the presence of beta-glycerophosphate and ascorbic acid. Under these conditions, melatonin induced gene expression of the bone marker proteins; however, this does not occur until the 5th day after seeding the culture dishes. Thereafter, MC3T3 cells responded to melatonin within 2 h of treatment. The fully differentiated rat osteoblast-like osteosarcoma 17/2.8 cells responded rapidly to melatonin and displayed an increase in the expression of BSP, ALP, and osteocalcin genes within 1 h of exposure to the hormone. To determine whether melatonin-induced osteoblast differentiation and bone formation are mediated via the transmembrane receptor, MC3T3 cells were treated in the presence and absence of melatonin with either luzindole, a competitive inhibitor of the binding of melatonin to the transmembrane receptors, or pertussis toxin, an uncoupler of G(i) from adenylate cyclase. Both luzindole and pertussis toxin were shown to reduce melatonin-induced expression of BSP and ALP. These results demonstrate, for the first time, that the pineal hormone, melatonin, is capable of promoting osteoblast differentiation and mineralization of matrix in culture and suggest that this hormone may play an essential role in regulating bone growth.

1,25-Dihydroxy vitamin D3 and tri-iodothyronine stimulate the expression of a protein immunologically related to osteocalcin.

Osteocalcin (OC), a bone-specific protein, is a marker of late osteoblastic differentiation. Its expression is influenced by various growth factors and hormones. We investigated the effect of 1, 25-dihydroxy vitamin D3 (D3) and tri-iodothyronine (T3) on OC expression in osteoblast-like MC3T3-E1 cells. A heterologous OC green fluorescence protein (GFP) fusion vector was established and expressed to study possible effects on protein transport. Immunostaining of endogenous OC revealed a significant increase in the percentage of positive cells after D3 and T3 treatment. This was consistent for MC3T3-E1 cells as well as nonosteogenic NIH-3T3 and mammary carcinoma cells, but not for neuroblastoma cells. The perinuclear immunostaining corresponded to the NBD C6 ceramide Golgi staining. Conversely, we found a strong induction of OC in MC3T3-E1 cells at the mRNA and protein levels only with T3 and not with D3. OC mRNA and protein expression was not detected in NIH fibroblasts. OC GFP transfection experiments indicate rapid transport and secretion of OC, because OC GFP was not found to be accumulated at intracellular compartments after hormone treatment. We conclude that the strong perinuclear immunostaining does not represent OC but a protein immunologically related to OC, as indicated by preabsorption experiments. The expression of this OC epitope-sharing protein is regulated by both D3 and T3 in the osteoblastic MC3T3-E1 and in nonosteogenic cells.