Moeko Togawaa, Akira Nakajima*, Nichika Fukumashi, Hitoshi Kariya, Kotoe Mayahara, Takayuki Kawato, Mitsuru Motoyoshi
Objective: Expression of transforming growth factor (TGF)-β is strongly associated with osteoblast differentiation. However, the role of TGF-β3 in mediating the effects of compressive force as a mechanical stress on osteoblasts remains unclear. Here, we examined the effects of compressive force on the expression of TGF-β3, and downstream signaling pathways comprising inflammatory cytokines in osteoblasts. Effects of siRNA-mediated knockdown of TGF-β3 on Smad-dependent and Smadindependent signaling pathways, and on inflammatory cytokines were also examined.
Design: Cultured MC3T3-E1 osteoblast-like cells were subjected to a continuous compressive force (0.5, 1.0, or 2.0 g/cm2) for 30 min, 1 h, and 3 h. TGF-β3 expression was examined using real-time polymerase chain reaction and western blot analysis. Total/phosphorylation levels of Smad2, Smad3, ERK1/2, and p38 were determined using western blot analysis. Cox2 and IL-6 levels were also measured using western blot analysis and real-time polymerase chain reaction.
Results: The mRNA and protein levels of TGF-β3 were significantly increased upon application of 1.0 g/cm2, but not 0.5 and 2.0 g/cm2, compressive force for 1 h, relative to the respective levels in untreated control cells. At 1.0 g/cm2, compressive force also increased the phosphorylation of Smad2, Smad3, ERK1/2, and p-38, and the expressions of COX-2 and IL-6. The increased expression was attenuated by pretreatment with siRNA against TGF-β3.
Conclusion: The present findings indicate that 1.0 g/cm2 compressive force can induce the expression of inflammatory cytokines via TGF-β3 signaling in osteoblasts. These results could be suggested the critical role of TGF-β signaling in bone formation.
Published Date: 2025-02-12; Received Date: 2024-06-23
