title: Identification of an alternatively spliced variant of Ca2+-promoted Ras inactivator as a possible regulator of RANKL shedding.
abstract: The receptor activator of NF-kappaB ligand (RANKL), a critical regulator of osteoclastogenesis, is synthesized as a membrane-anchored protein and cleaved into a soluble form by ectodomain shedding. We developed an assay system to identify molecules regulating the RANKL shedding. Using this system, we found that a splice variant of Ca2+-promoted Ras inactivator (CAPRI), deltaCAPRI, which is expressed in primary osteoblasts, promoted the RANKL shedding. The wild type CAPRI is a member of the Ras GTPase-activating protein (GAP) family and suppresses Ca2+-dependent Ras activation, whereas deltaCAPRI, which lacks one exon in the GAP-related domain, activated the Ras pathway. Overexpression of deltaCAPRI or a constitutive active form of Ras up-regulated the expression level of matrix-metalloproteinase 14 (MMP14), which directly cleaves the ectodomain of RANKL, whereas Erk activation by expressing the constitutive active Mek1 did not affect the MMP14 expression or RANKL shedding. These results suggest that deltaCAPRI is a possible regulator of RANKL shedding by modulating MMP14 expression through Ras signaling cascades other than the Erk pathway.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Hikita
authors.forename: Yuho
authors.initials: Y
authors.lastname: Kadono
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Chikuda
authors.forename: Akira
authors.initials: A
authors.lastname: Fukuda
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Wakeyama
authors.forename: Hisataka
authors.initials: H
authors.lastname: Yasuda
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Hiromi
authors.initials: H
authors.lastname: Oda
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Sakae
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D017398:Alternative Splicing; D000818:Animals; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D017364:Collagenases; D003470:Culture Media / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D005091:Exons; D015723:Gene Library; D005822:Genetic Vectors; D006801:Humans; D007150:Immunohistochemistry; D053509:Matrix Metalloproteinase 13; D053511:Matrix Metalloproteinase 14; D020782:Matrix Metalloproteinases / Q000378:metabolism; D053504:Matrix Metalloproteinases, Membrane-Associated; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D010006:Osteoblasts / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014162:Transfection; D015854:Up-Regulation; D020703:ras GTPase-Activating Proteins / Q000378:metabolism*; D018631:ras Proteins / Q000737:chemistry*
chemical_list: D002352:Carrier Proteins; D003470:Culture Media; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; C507096:Mmp14 protein, mouse; D053245:RANK Ligand; C491144:RASA4 protein, human; C504471:Rasa4 protein, mouse; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D020703:ras GTPase-Activating Proteins; D000469:Alkaline Phosphatase; D017364:Collagenases; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; D020782:Matrix Metalloproteinases; D053504:Matrix Metalloproteinases, Membrane-Associated; C507081:Mmp13 protein, mouse; D053511:Matrix Metalloproteinase 14; D018631:ras Proteins; D002118:Calcium