| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2009: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2008: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Research Abstract |
The cells of monocyte/macrophage lineage differentiated into osteoclasts following the stimulation of cells with RANKL. It has been reported that cell adhesion signals are required for osteoclast differentiation from their precursors. However, details of the mechanism by which cell adhesion signals induce osteoclast differentiation have not been examined yet. In the present study, we investigated that cell adhesion signals participate in RANK expression in osteoclast precursors. Mouse bone marrow-derived macrophages (BMMs) were cultured on the culture dishes (the adherent condition) or on the methylcellulose gel (the non-adherent condition), and then examined osteoclast differentiation, activation of intracellular signals, and changes in gene expression. When BMMs were cultured under adherent condition, almost all BMMs differentiated into osteoclasts in response to RANKL stimulation. However, under non-adherent condition, the efficiency of osteoclast differentiation was markedly reduced even in the presence of RANKL. Although LPS or TNF-alpha activated the NF-kappa B-mediated signaling pathways under both conditions, RANKL failed to activate these pathways under non-adherent condition. We elucidated that mRNA and protein of RANK are highly expressed under adherent condition, and then accelerated by stimulation of RANKL. The inhibition of differentiation under non-adherent condition was recovered by overexpression of RANK or TRAF6. These results suggest that cell adhesion signals play an important role in regulating RANK expression in osteoclast precursors.
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