title: Receptor activator of NF-kappaB (RANK) ligand induces ectodomain shedding of RANK in murine RAW264.7 macrophages.
abstract: Osteoclastogenesis is a highly sophisticated process that involves a variety of membrane-bound proteins expressed in osteoblasts and osteoclast precursors. Over the past several years, proteolytic cleavage and release of the ectodomain of membrane-bound proteins, also referred to as ectodomain shedding, has emerged as an important posttranslational regulatory mechanism for modifying the function of cell surface proteins. In line with this notion, several membrane-bound molecules involved in osteoclastogenesis, including CSF-1R and receptor activator of NF-kappaB ligand (RANKL), are proteolytically cleaved and released from the cell surface. In this study, we investigated whether receptor activator of NF-kappaB (RANK), one of the most essential molecules in osteoclastogenesis, undergoes ectodomain shedding. The results showed that RANK is released in the form of a soluble monomeric protein and that TNF-alpha-converting enzyme is involved in this activity. We also identified potential cleavage sites in the juxtamembrane domain of RANK and found that rRANKL induces RANK shedding in a macrophage-like cell line RAW264.7 via TNFR-associated factor 6 and MAPK pathways. Furthermore, we found that RANKL-induced osteoclastogenesis is accelerated in TNF-alpha-converting enzyme-deficient osteoclast precursors. These observations suggest the potential involvement of ectodomain shedding in the regulation of RANK functions and may provide novel insights into the mechanisms of osteoclastogenesis.
authors.affiliation: Department of Orthopedic Surgery, School of Medicine, Keio University, Tokyo 160-8582, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hakozaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Yoda
authors.forename: Takahide
authors.initials: T
authors.lastname: Tohmonda
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Furukawa
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hikata
authors.forename: Shinichi
authors.initials: S
authors.lastname: Uchikawa
authors.forename: Hironari
authors.initials: H
authors.lastname: Takaishi
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Chiba
authors.forename: Keisuke
authors.initials: K
authors.lastname: Horiuchi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D051722:ADAM Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000072198:ADAM17 Protein; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D005434:Flow Cytometry; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012995:Solubility; D048029:TNF Receptor-Associated Factor 6 / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D015854:Up-Regulation
chemical_list: D008565:Membrane Proteins; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D048029:TNF Receptor-Associated Factor 6; D020928:Mitogen-Activated Protein Kinases; D051722:ADAM Proteins; D000072198:ADAM17 Protein