title: Interleukin-4 inhibits RANKL-induced expression of NFATc1 and c-Fos: a possible mechanism for downregulation of osteoclastogenesis.
abstract: 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.
authors.affiliation: Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Sugitani 2630, Toyama 930-0194, Japan.
authors.forename: Saad Gad
authors.initials: SG
authors.lastname: Kamel Mohamed
authors.forename: Eiji
authors.initials: E
authors.lastname: Sugiyama
authors.forename: Kouichiro
authors.initials: K
authors.lastname: Shinoda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hounoki
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Taki
authors.forename: Muneharu
authors.initials: M
authors.lastname: Maruyama
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Miyahara
authors.forename: Masashi
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: 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*
chemical_list: 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