BMP-2 promotes differentiation of osteoblasts and chondroblasts in Runx2-deficient cell lines.
To investigate the molecular mechanism underlying the differentiation of osteoblasts and chondroblasts, we established a clonal cell lines, RD-C6, from Runx2-deficient mouse embryos. RD-C6 cells expressed almost undetectable levels of phenotypes related to osteoblast and chondroblast differentiation at basal culture condition, whereas treatment with recombinant human bone morphogenetic protein-2 (rhBMP-2) or transduction of BMP-2 by adenovirus effectively induced this cell line to express mRNA related to the differentiation of osteoblasts and chondroblasts including alkaline phosphatase, osteocalcin, and osterix. Transduction of Runx2 also induced the expression of these mRNA in RD-C6 cells. BMP-2 transduction increased expression levels of mRNA for Msx2 and Dlx5, but Runx2 transduction induced no significant increases in expression levels of these mRNA. Microarray analysis using RD-C6 cells with or without rhBMP-2 treatment demonstrated that BMP-2 upregulated 66 genes including 13 transcription-related molecules such as Id1, Id2, Id4, Hey1, Smad6, Smad7, and Msx2. To confirm bone and cartilage formation ability of RD-C6 cells, we transplanted RD-C6 cells into the peritoneal cavity of athymic mice using diffusion chambers with rhBMP-2. RD-C6 cells generated unmineralized cartilage but not bone. These results indicate that BMP-2 induces Runx2-deficient cells to express markers related to osteoblast and chondroblast differentiation using a Runx2-independent pathway, but it failed to induce these cells to differentiate into bone-forming osteoblasts and mature chondrocytes.
Liu
Tingjiao
T
Section of Oral Pathology, Department of Oral Restitution, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan.
Gao
Yuhao
Y
Sakamoto
Kei
K
Minamizato
Tokutaro
T
Furukawa
Keizo
K
Tsukazaki
Tomoo
T
Shibata
Yasuaki
Y
Bessho
Kazuhisa
K
Komori
Toshihisa
T
Yamaguchi
Akira
A
D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000235:genetics*; D002356:Cartilage / Q000166:cytology; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology* / Q000502:physiology*; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics*; D015194:Diffusion Chambers, Culture; D015870:Gene Expression / Q000502:physiology; D051379:Mice; D008817:Mice, Mutant Strains; D008819:Mice, Nude; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D010529:Peritoneal Cavity; D010641:Phenotype; D012886:Skull / Q000166:cytology; D016212:Transforming Growth Factor beta / Q000235:genetics*; D019737:Transplants
C525718:BMP2 protein, human; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D050659:Core Binding Factor Alpha 1 Subunit; C493716:Runx2 protein, mouse; D016212:Transforming Growth Factor beta