Bone morphogenetic proteins 2, 6, and 9 differentially regulate the osteogenic differentiation of immortalized preodontoblasts

Our study attempted to compare the efficacies of bone morphogenetic protein (BMP) 2, 6, and 9 in inducing osteogenic differentiation of preodontoblasts (PDBs). We immortalized PDBs by introducing a reversible SV40 T antigen-based immortalization system. Cell proliferation capability was examined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. The effects of BMP2, 6, and 9 on the osteogenic differentiation of immortalized preodontoblasts (iPDBs) were measured by alkaline phosphatase (ALP) activity assays and alizarin red S staining. The expression of osteogenic markers was evaluated by semiquantitative real-time polymerase chain reaction analysis. To assess ectopic bone formation, rat-derived iPDBs were transfected in culture with adenoviral vectors designated Ad-BMP2, 6, and 9 and subcutaneously or intramuscularly injected into mice. Several BMPs retained endogenous expression in PDBs and regulated the mRNA expression of mineralized tissue-associated proteins. ALP activity and mineralized nodule formation were significantly increased in the Ad-BMP9-transfected group relative to the control group. In addition, the most significant hard tissue formation was in this group. The results indicated that BMP signaling was involved in the osteogenic differentiation of iPDBs. BMP9 could be an efficacious accelerant of the osteogenic differentiation of iPDBs.

Wnt3a enhances bone morphogenetic protein 9-induced osteogenic differentiation of C3H10T1/2 cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Bone 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.</p><p><b>METHODS</b>C3H10T1/2 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.</p><p><b>RESULTS</b>The 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.</p><p><b>CONCLUSION</b>Canonical 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.</p>

Purification and biological osteoinductive activity analysis of recombinant human bone morphogenetic protein 9 by eukaryotic expression / 生物医学工程学杂志

The present paper is aimed to explore the biological osteoinductive activity of recombinant human bone morphogenetic protein 9 (rhBMP-9) by various biological technologies. In this study, we firstly obtained hBMP-9 cDNA by PCR and inserted it into vector pcDNA4/His Max to reconstruct hBMP-9 eukaryotic expression vector pcDNA4/His Max-BMP-9. Recombinant Chinese hamster ovary (rCHO) cell line expressing high-level rhBMP-9 was reconstructed by co-transfecting the expression vectors pcDNA4/His* Max-hBMP-9 and plasmid pSV2-dhfr into dihydrofolate reductase (dhfr)-deficient CHO cells and the subsequent gene amplification by the methotrexate. We finally obtained a monoclonal cell line expressing the highest level protein. We purified the medium after culturing the highest-producing monoclonal by Ni-NTA His-Bind Resin columns and concentrated to by a Centricon 50 at 4 degrees C and stored at 70 degrees C until it was used. Western blot and SDS-PAGE analyses showed a specific band of about 32kD in pro-region lane and a specific band of about 50kD in pro-region complex lane. Biological activities of rhBMP-9 were tested by colorimetric determination and histochemical staining of Alkaline Phosphatase (ALP) Activity, osteocalcin and oesteopontin for C3H10 T1/2 cells, which were stimulated culture by different concentration (20, 50, 100 microg/mL) of rhBMP-9. The results showed that the rhBMP-9 could induce osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro, and were proportional to the amount. This study can provide experimental data for further tests in vivo and clinical applications.

Construction of a luciferase reporter vector containing response element of activator protein 2α and its application in study of osteogenetic differentiation / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a luciferase reporter vector containing the response element of transcription protein AP2α for screening the effect of bone morphogenetic proteins (BMPs) on the transcriptional activity of AP2α.</p><p><b>METHODS</b>Four tandem-linked response elements of AP2α were cloned to the pBGLuc luciferase reporter gene plasmid, which was digested with Bam HI and Mlu I to construct pBGLuc-AP2α-RE vector. The recombinant adenovirus Ad-AP2α and its dominant negative mutant Ad-dnAP2α were used to infect mouse mesenchymal stem cells C3H10; the changes in cellular AP2α mRNA and protein expressions were detected by real-time PCR and Western blotting, and electrophoretic mobility shift assay (EMSA) was carried out to assess the DNA-binding ability of AP2α. C3H10 cells were transfected with pBGLuc-AP2α-RE vector, and AP2α transcriptional activity was measured using luciferase reporter gene assay. In pBGLuc-AP2α-RE vector-transfected C3H10 cells infected with Ad-BMPs, luciferase reporter gene assay was performed to screen the effect of BMPs on AP2α transcriptional activity.</p><p><b>RESULTS</b>The results of PCR, enzyme digestion and sequencing all confirmed correct cloning of AP2α-RE into pBGLuc-AP2α-RE luciferase reporter vector, and Ad-AP2α infection significantly increased AP2α expression and its DNA binding ability. The dominant negative mutants expressed the corresponding mutants, and EMSA results showed that Ad-dnAP2α-δbHLH significantly lowered while Ad-dnAP2α-δTAD enhanced the DNA-binding ability of AP2α. AP2α over-expression promoted AP2α transcriptional activity, which was suppressed by the two dominant negative mutants. AP2α transcriptional activity increased in the cells infected with the recombinant adenovirus BMPs, especially in cells with BMP9 infection.</p><p><b>CONCLUSIONS</b>The luciferase reporter vector containing the response element of AP2α we constructed allows detection of AP2α transcriptional activity. BMP9 can significantly enhance AP2α transcriptional activity.</p>

Screening and identification of effective small interfering RNAs against bone morphogenetic protein-9 / 南方医科大学学报

<p><b>OBJECTIVE</b>To screen specific small interfering RNA (siRNA) targeting mouse BMP9 gene and identify its function in BNLCL.2 fetal liver cells and C3H10 cells.</p><p><b>METHODS</b>Four pairs of double-stranded DNA fragments for silencing mouse BMP9 were annealed in vitro and cloned into pSOS-BMP9 vector with BMP9 gene to construct pSOS-simBMP9 plasmid. The 4 pSOS-simBMP9 plasmids were separately transfected in HEK293 cells via Lipofectamine, and the gene silencing efficiency was assessed by GFP detection. BNLCL.2 fetal liver cells were infected with the constructed adenovirus simBMP9s, and their BMP9 expression was detected with RT-PCR and Western blotting. C3H10 cells were co-infected with Ad-simBMP9 and Ad-BMP9, and the inhibitory effect on BMP9-induced osteoblasts was evaluated by alkaline phosphatase (ALP) activity.</p><p><b>RESULTS</b>GFP expression in the two simBMP9 groups was significantly decreased in HEK293 cells, and the endogenous expression of BMP9 was reduced by 50%-70% by adenovirus-mediated simBMP9 in the fetal liver cells. ALP activity in C3H10 cells was significantly higher in BMP9 group than in the control group (P<0.01), while the activity of the two Ad-simBMP9-infected groups was significantly lower than that in Ad-BMP9-infected group (P<0.01).</p><p><b>CONCLUSION</b>Two specific siRNA targeting mouse BMP9 gene have been obtained, which can effectively inhibit both endogenous and exogenous expressions of BMP9 to facilitate the study of the mechanisms of BMP9 in liver cell differentiation.</p>