M-CSF regulates the cytoskeleton via recruitment of a multimeric signaling complex to c-Fms Tyr-559/697/721.
M-CSF is known to induce cytoskeletal reorganization in macrophages and osteoclasts by activation of phosphatidylinositol 3-kinase (PI3K) and c-Src, but the detailed mechanisms remain unclear. We find, unexpectedly, that tyrosine (Tyr) to phenylalanine (Phe) mutation of Tyr-721, the PI3K binding site in the M-CSF receptor c-Fms, fails to suppress cytoskeletal remodeling or actin ring formation. In contrast, mutation of c-Fms Tyr-559 to Phe blocks M-CSF-induced cytoskeletal reorganization by inhibiting formation of a Src Family Kinase SFK.c-Cbl.PI3K complex and the downstream activation of Vav3 and Rac, two key mediators of actin remodeling. Using an add-back approach in which specific Tyr residues are reinserted into c-Fms inactivated by the absence of all seven functionally important Tyr residues, we find that Tyr-559 is necessary but not sufficient to transduce M-CSF-dependent cytoskeletal reorganization. Furthermore, this same add-back approach identifies important roles for Tyr-697 and Tyr-721 in collaborating with Tyr-559 to recruit a multimeric signaling complex that can transduce signals from c-Fms to the actin cytoskeleton.
Faccio
Roberta
R
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Takeshita
Sunao
S
Colaianni
Graziana
G
Chappel
Jean
J
Zallone
Alberta
A
Teitelbaum
Steven L
SL
Ross
F Patrick
FP
D008841:Actin Cytoskeleton / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism*; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism* / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism; D010649:Phenylalanine / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine / Q000235:genetics; D019061:src-Family Kinases / Q000378:metabolism
D014443:Tyrosine; D010649:Phenylalanine; D016173:Macrophage Colony-Stimulating Factor; D050721:Proto-Oncogene Proteins c-cbl; D019869:Phosphatidylinositol 3-Kinases; D016186:Receptor, Macrophage Colony-Stimulating Factor; D019061:src-Family Kinases; C493849:Cbl protein, mouse