Tyrosines 559 and 807 in the cytoplasmic tail of the macrophage colony-stimulating factor receptor play distinct roles in osteoclast differentiation and function.
Osteoclast (OC) differentiation requires that precursors, such as macrophage colony-stimulating factor (M-CSF)-dependent bone marrow macrophages, receive signals transduced by receptor activator of nuclear factor kappaB (RANK) and c-Fms, receptors for RANK ligand (RANKL) and M-CSF, respectively. Activated c-Fms autophosphorylates cytoplasmic tail tyrosine residues, which, by recruiting adaptor molecules, initiate specific signaling pathways. To identify which tyrosine residues are involved in c-Fms signaling in primary cells, we retrovirally transduced M-CSF-dependent bone marrow macrophages with a chimera comprising the external domain of the erythropoietin (Epo) receptor linked to the transmembrane and cytoplasmic domains of c-Fms. Transduced cells differentiate into bone-resorbing osteoclasts when treated with RANKL and either M-CSF or Epo, confirming that both endogenous and chimeric receptors transmit osteoclastogenic signals. Cells expressing chimeric receptors with Y(697)F, Y(706)F, Y(721)F, and Y(921)F single point mutations generate normal numbers of bone-resorbing OCs, with normal bone-resorbing activity when treated with RANKL and Epo. In contrast, those expressing Y(559)F generate fewer OCs, whereas theY807F mutant is incapable of osteoclastogenesis. Finally, although mature OCs expressing Y(559)F exhibit impaired bone resorption, those bearing Y807F do not. Thus, we have identified specific tyrosine residues in the cytoplasmic tail of c-Fms that are critical for transmitting M-CSF-initiated signals individually required for OC formation or function, respectively.
Feng
Xu
X
Departments of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Takeshita
Sunao
S
Namba
Noriyuki
N
Wei
Shi
S
Teitelbaum
Steven L
SL
Ross
F Patrick
FP
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology; D001862:Bone Resorption; D002352:Carrier Proteins / Q000494:pharmacology; D002454:Cell Differentiation / Q000502:physiology*; D004921:Erythropoietin / Q000494:pharmacology; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D010010:Osteoclasts / Q000166:cytology* / Q000502:physiology*; D017354:Point Mutation; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D017467:Receptors, Erythropoietin / Q000235:genetics; D011993:Recombinant Fusion Proteins; D013329:Structure-Activity Relationship; D014162:Transfection; D014443:Tyrosine
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D017467:Receptors, Erythropoietin; D011993:Recombinant Fusion Proteins; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D004921:Erythropoietin; D014443:Tyrosine; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor