Interleukin-4 inhibits RANKL-induced expression of NFATc1 and c-Fos: a possible mechanism for downregulation of osteoclastogenesis.
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 kappaB 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 10ng/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.
Kamel Mohamed
Saad Gad
SG
Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Sugitani 2630, Toyama 930-0194, Japan.
Sugiyama
Eiji
E
Shinoda
Kouichiro
K
Hounoki
Hiroyuki
H
Taki
Hirofumi
H
Maruyama
Muneharu
M
Miyahara
Tatsuro
T
Kobayashi
Masashi
M
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000502:physiology; D015847:Interleukin-4 / Q000494:pharmacology*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D014157:Transcription Factors / Q000378:metabolism*
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D009687:Nuclear Proteins; D016760:Proto-Oncogene Proteins c-fos; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D014157:Transcription Factors; D015847:Interleukin-4