Nuclear factor kappaB p65 phosphorylation in orthodontic tooth movement.

Osteoclasts play a vital role in orthodontic tooth movement. Transactivation of nuclear factor kappaB (NFkappaB) by phosphorylation of the p65 component of NFkappaB at amino acid 536 (p65*(536)) plays a role in osteoclast differentiation stimulated by receptor activator of nuclear factor kappaB-ligand (RANK-L). We hypothesized that this transactivation pathway might be involved in the responses of alveolar bone cells during orthodontic tooth movement. We detected sharp increases in the levels of p65*(536) 3 and 12 hrs after the application of orthodontic stimuli in rats. In cell culture, osteoclast-like cells displayed no changes in p65*(536) in response to RANK-L, but levels rapidly increased after the cells were mechanically scraped. We conclude that p65*(536) is produced rapidly in response to orthodontic stimuli and mechanical insults, and may be important in bone remodeling associated with orthodontic tooth movement.