Overexpression of BMP-2 modulates morphology, growth, and gene expression in osteoblastic cells.
Bone morphogenetic proteins (BMP) play a pivotal role in growth and differentiation of osteoblastic lineage cells. BMPs are potent stimulators of bone formation in various animal models. To understand the mechanism of BMP action in bone cells, we have investigated the effects of overexpression of the BMP-2 gene on proliferation and differentiation of UMR-106 rat osteosarcoma cells. A stable UMR-106 cell line overexpressing the BMP-2 gene was established by transfection of cells using a mammalian expression vector harboring human BMP-2 cDNA followed by G418 selection. After introduction of the BMP-2 gene, UMR-106 cells appeared more spindle-shaped in morphology compared to the predominantly cuboidal appearance of the parental cells. Overexpression of BMP-2 markedly inhibited proliferation as measured by cell counting and [3H]thymidine incorporation assays. Extracellular matrix (ECM) derived from cells overexpressing BMP-2 exhibited a less supportive effect on proliferation of UMR cells than did ECM derived from parental cells. Furthermore, cell-cell communication through gap junctions was reduced more than 50% as determined by nondisruptive fluorescent dye transfer assays. Overexpression of BMP-2 significantly stimulated expression of osteocalcin and alkaline phosphatase genes, indicating its role in osteoblastic differentiation. There was little effect on osteopontin gene expression.
Huang
Weibiao
W
Plastic Surgery Section, Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA.
Rudkin
George H
GH
Carlsen
Brian
B
Ishida
Kenji
K
Ghasri
Peyman
P
Anvar
Bardia
B
Yamaguchi
Dean T
DT
Miller
Timothy A
TA
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001846:Bone Development / Q000235:genetics*; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000235:genetics*; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics*; D002455:Cell Division / Q000235:genetics; D048429:Cell Size / Q000235:genetics; D016326:Extracellular Matrix Proteins / Q000378:metabolism / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000378:metabolism; D051381:Rats; D016212:Transforming Growth Factor beta; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000235:genetics*
C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016326:Extracellular Matrix Proteins; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D000469:Alkaline Phosphatase