title: The actin binding protein adseverin regulates osteoclastogenesis.
abstract: Adseverin (Ads), a member of the Gelsolin superfamily of actin binding proteins, regulates the actin cytoskeleton architecture by severing and capping existing filamentous actin (F-actin) strands and nucleating the assembly of new F-actin filaments. Ads has been implicated in cellular secretion, exocytosis and has also been shown to regulate chondrogenesis and megakaryoblastic leukemia cell differentiation. Here we report for the first time that Ads is involved in regulating osteoclastogenesis (OCG). Ads is induced during OCG downstream of RANK-ligand (RANKL) stimulation and is highly expressed in mature osteoclasts. The D5 isoform of Ads is not involved in regulating OCG, as its expression is not induced in response to RANKL. Three clonal Ads knockdown RAW264.7 (RAW) macrophage cell lines with varying degrees of Ads expression and OCG deficiency were generated. The most drastic OCG defect was noted in the clonal cell line with the greatest degree of Ads knockdown as indicated by a lack of TRAcP staining and multinucleation. RNAi mediated knockdown of Ads in osteoclast precursors resulted in distinct morphological changes characterized by altered F-actin distribution and increased filopodia formation. Ads knockdown precursor cells experienced enhanced migration while fusion of knockdown precursors cells was limited. Transient reintroduction of de novo Ads back into the knockdown system was capable of rescuing TRAcP expression but not osteoclast multinucleation most likely due to the transient nature of Ads expression. This preliminary study allows us to conclude that Ads is a RANKL induced early regulator of OCG with a potential role in pre-osteoclast differentiation and fusion.
authors.affiliation: Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Siavash
authors.initials: S
authors.lastname: Hassanpour
authors.affiliation: Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada; Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, P. R. China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Johannes W P
authors.initials: JW
authors.lastname: Kuiper
authors.affiliation: Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Glogauer
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002999:Clone Cells; D003804:Dentin / Q000378:metabolism; D018260:Gelsolin / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D008810:Mice, Inbred C57BL; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D053245:RANK Ligand / Q000494:pharmacology; D012995:Solubility; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000199:Actins; D018260:Gelsolin; D008840:Microfilament Proteins; D053245:RANK Ligand; C065395:scinderin