Novel functions for NFκB: inhibition of bone formation

NF kappa B is a family of transcription factors involved in immunity and the normal functioning of many tissues. It has been well studied in osteoclasts, and new data indicate an important role for NF kappa B in the negative regulation of bone formation. In this article, we discuss how NF kappa B activation affects osteoblast function and bone formation. In particular, we describe how reduced NF kappa B activity in osteoblasts results in an increase in bone formation via enhanced c-Jun N-terminal kinase (JNK) activity, which regulates FOSL1 (also known as Fra1) expression. Furthermore, we discuss how estrogen and NF kappa B crosstalk in osteoblasts acts to oppositely regulate bone formation. Future NF kappa B-targeting treatments for osteoporosis, rheumatoid arthritis and other inflammatory bone diseases could lead to increased bone formation concurrent with decreased bone resorption.