title: c-Fos protein as a target of anti-osteoclastogenic action of vitamin D, and synthesis of new analogs.
abstract: Although active vitamin D drugs have been used for the treatment of osteoporosis, how the vitamin D receptor (VDR) regulates bone cell function remains largely unknown. Using osteoprotegerin-deficient mice, which exhibit severe osteoporosis due to excessive receptor activator of NF-kappaB ligand/receptor activator of NF-kappaB (RANKL/RANK) stimulation, we show herein that oral treatment of these mice with 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] inhibited bone resorption and prevented bone loss, suggesting that VDR counters RANKL/RANK signaling. In M-CSF-dependent osteoclast precursor cells isolated from mouse bone marrow, 1alpha,25(OH)2D3 potently and dose-dependently inhibited their differentiation into multinucleate osteoclasts induced by RANKL. Among signaling molecules downstream of RANK, 1alpha,25(OH)2D3 inhibited the induction of c-Fos protein after RANKL stimulation, and retroviral expression of c-Fos protein abrogated the suppressive effect of 1alpha,25(OH)2D3 on osteoclast development. By screening vitamin D analogs based on their c-Fos-suppressing activity, we identified a new analog, named DD281, that inhibited bone resorption and prevented bone loss in ovariectomized mice, more potently than 1alpha,25(OH)2D3, with similar levels of calcium absorption. Thus, c-Fos protein is an important target of the skeletal action of VDR-based drugs, and DD281 is a bone-selective analog that may be useful for the treatment of bone diseases with excessive osteoclastic activity.
authors.affiliation: Department of Bone and Joint Disease, Research Institute, National Center for Geriatrics and Gerontology, Obu, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Takasu
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sugita
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Uchiyama
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Katagiri
authors.forename: Makoto
authors.initials: M
authors.lastname: Okazaki
authors.forename: Etsuro
authors.initials: E
authors.lastname: Ogata
authors.forename: Kyoji
authors.initials: K
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D050071:Bone Density Conservation Agents / Q000378:metabolism* / Q000627:therapeutic use; D001862:Bone Resorption / Q000517:prevention & control; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000627:therapeutic use; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D005260:Female; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010024:Osteoporosis / Q000188:drug therapy / Q000378:metabolism; D053244:Osteoprotegerin; D010052:Ovariectomy; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism
chemical_list: D050071:Bone Density Conservation Agents; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D016760:Proto-Oncogene Proteins c-fos; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018167:Receptors, Calcitriol; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D002117:Calcitriol