Interleukin-4 inhibits RANKL-induced expression of NFATc1 and c-Fos: A possible mechanism for downregulation of osteoclastogenesis

• Published in: Biochemical and biophysical research communications 2005-04, Vol.329 (3), p.839-845
• Main Authors: Kamel Mohamed, Saad Gad, Sugiyama, Eiji, Shinoda, Kouichiro, Hounoki, Hiroyuki, Taki, Hirofumi, Maruyama, Muneharu, Miyahara, Tatsuro, Kobayashi, Masashi
• Format: Article
• Language: English
• Subjects: Animals; c-Fos; Carrier Proteins - metabolism; Cell Differentiation - drug effects; Cell Differentiation - physiology; Cell Line; Cell Proliferation - drug effects; DNA-Binding Proteins - metabolism; Dose-Response Relationship, Drug; Down-Regulation - physiology; IL-4; Interleukin-4 - pharmacology; Male; Membrane Glycoproteins - metabolism; Mice; Monocytes - cytology; Monocytes - drug effects; Monocytes - physiology; NFATC Transcription Factors; NFATc1; Nuclear Proteins - metabolism; Osteoclastogenesis; Osteoclasts - cytology; Osteoclasts - drug effects; Osteoclasts - physiology; Proto-Oncogene Proteins c-fos - metabolism; RANK Ligand; RAW264.7 cells; Receptor Activator of Nuclear Factor-kappa B; Transcription Factors - metabolism
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.02.049

Interleukin-4 (IL-4), an anti-inflammatory cytokine, has been shown to inhibit osteoclast differentiation. Therefore, this cytokine is considered to be a promising therapeutic applicant for bone-resorbing diseases such as rheumatoid arthritis (RA). Recently NFATc1, a transcription factor, has been shown to play critical roles in osteoclastogenesis. The aim of this study was to clarify the role of IL-4 on the intracellular signaling of NFATc1. A RAW264.7 monocyte/macrophage cell line and murine bone marrow precursors were differentiated into osteoclasts in the presence of receptor activator of nuclear factor κB ligand (RANKL) and/or macrophage colony-stimulating factor. Tartrate-resistant acid phosphatase (TRAP) staining and a pit assay using dentine were used for the identification of activated osteoclasts. The protein expression of IL-4 receptor, NFATc1, and c-Fos was determined by Western blot analysis. In addition, the gene expression of NFATc1 and c-Fos was determined by reverse transcription and polymerase chain reaction. The IL-4 receptor was constitutively expressed in RAW264.7 cells. RANKL induced osteoclast generation, as determined by TRAP staining and pit assay. IL-4 inhibited RANKL-induced osteoclastogenesis at low concentrations of 10 ng/ml and more. Interestingly, IL-4 potently inhibited RANKL-induced expression of NFATc1 at mRNA level. Furthermore, IL-4 inhibited c-Fos expression, which is shown to be responsible for NFATc1 expression, in time- and dose-dependent manners. In addition, IL-4 inhibited the RANKL-induced expression of NFATc1 and c-Fos in murine bone marrow cells. Thus, we suggest that IL-4 may downregulate osteoclastogenesis in part through inhibition of the expression of transcription factors, NFATc1 and c-Fos. These findings provide new insight into development of new medication for osteoporosis and RA.