title: High dose M-CSF partially rescues the Dap12-/- osteoclast phenotype.
abstract: Osteoclasts are macrophage derived cells and as such are subject to regulation by molecules impacting other members of the immune system. Dap12 is an adaptor protein expressed by NK cells and B and T lymphocytes. Dap12 also mediates maturation of myeloid cells and is expressed by osteoclasts which are dysfunctional in its absence. We find Dap12-/- osteoclast precursors fail to differentiate, in vitro, and the abnormality is partially rescued by high dose M-CSF. The relative paucity of osteoclast number, even in presence of high dose cytokine, is attended by dampened proliferation of precursor cells and their failure to normally migrate towards the osteoclast-recognized matrix protein, osteopontin. Furthermore, Dap12-/- osteoclasts generated in high dose M-CSF fail to normally organize their cytoskeleton. The incapacity of Dap12 null cells to undergo normal osteoclast differentiation is not due to blunted stimulation of major RANK ligand (RANKL) or M-CSF induced signaling pathways. On the other hand, when plated on osteopontin, Dap12-/- pre-osteoclasts do not activate the tyrosine kinase, Syk, which normally binds to the adaptor protein and transmits downstream signals. Attesting to the importance of the Dap12/Syk complex, Syk deficient macrophages do not undergo normal osteoclastogenesis. Furthermore, the same cells plated onto osteopontin, adhere poorly and fail to phosphorylate c-Src or Pyk2, two kinases central to organization of the osteoclast cytoskeleton.
authors: Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors: Roberta
authors: R
authors: Faccio
authors: Wei
authors: W
authors: Zou
authors: Graziana
authors: G
authors: Colaianni
authors: Steven L
authors: SL
authors: Teitelbaum
authors: F Patrick
authors: FP
authors: Ross
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000502:physiology*; D000818:Animals; D002116:Calcitonin / Q000235:genetics; D002352:Carrier Proteins / Q000378:metabolism; D056657:Cathepsin K; D002403:Cathepsins / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D004792:Enzyme Precursors / Q000235:genetics / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D016173:Macrophage Colony-Stimulating Factor / Q000008:administration & dosage / Q000494:pharmacology*; D020780:Matrix Metalloproteinase 9 / Q000235:genetics; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D053495:Osteopontin; D010641:Phenotype; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000502:physiology; D053245:RANK Ligand; D012333:RNA, Messenger / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B; D011971:Receptors, Immunologic / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000378:metabolism; D015398:Signal Transduction; D000072377:Syk Kinase
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D011971:Receptors, Immunologic; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; C484963:Tyrobp protein, mouse; D053495:Osteopontin; D016173:Macrophage Colony-Stimulating Factor; D002116:Calcitonin; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606897:Syk protein, mouse; D002403:Cathepsins; D056657:Cathepsin K; C534132:Ctsk protein, mouse; D020780:Matrix Metalloproteinase 9