Objective
Transforming growth factor-β (TGF-β) superfamily members, including bone morphogenetic protein
(BMP) are believed to have a strong stimulatory effect on bone formation. Recently, several studies revealed that
these two factors have effect on the bone resorption, but the results are controversial. Thus, in this study, we
examined the effect of TGF-β1 and BMP-2 on the osteoclastogenesis.
Methods
Bone marrow cells prepared from the femur and tibia of C57BL/6 mice and non-adherent cells were used
as bone marrow cell. Freshly separated bone marrow cells were cultured for 8 days in culture media including 1α,
25-(OH)2D3. After 2 or 4 days culture, TGF-β1 or BMP-2 was added with or without receptor activator of nuclear
factor kappa B ligand (RANKL). The activity of tartrate resistant acid phosphatase (TRAP) was measured and the
level of receptor activator of nuclear factor kappa B (RANK) mRNA was determined by reverse transcriptase -
polymerase chain reaction (RT-PCR).
Results
The TRAP activity was not enhanced by TGF-β1 or BMP-2 alone but increased markedly if RANKL was
added. TRAP activity increased only when the stimulants added in the early stage of culture (2nd days). The RANK
mRNA level increased in TGF-β1 with RANKL group than RANKL or RANKL with BMP group.
Conclusions
The effect of TGF-β1 or BMP-2 on the osteoclastogenesis is minimal. But if added with RANKL,
strong stimulatory effect was found on the osteoclastogenesis, especially in early stage of culture. The level of
RANK mRNA was increased significantly in TGF-β1 and RANKL but not in BMP with RANKL group.
[Korean Journal of Bone Metabolism, 17(2): 75-85, 2010]
