Colony-stimulating factor-1 induces cytoskeletal reorganization and c-src-dependent tyrosine phosphorylation of selected cellular proteins in rodent osteoclasts.
Colony-stimulating factor-1 (CSF-1) stimulates motility and cytoplasmic spreading in mature osteoclasts. Therefore, we examined the cellular events and intracellular signaling pathways that accompany CSF-1-induced spreading in normal osteoclasts. To explore the role c-src plays in these processes, we also studied osteoclasts prepared from animals with targeted disruption of the src gene. In normal osteoclasts, CSF-1 treatment induces rapid cytoplasmic spreading, with redistribution of F-actin from a well-delineated central attachment ring to the periphery of the cell. CSF-1 increases membrane phosphotyrosine staining in osteoclasts and induces the phosphorylation of several cellular proteins in cultured, osteoclast-like cells, including c-fms, c-src, and an 85-kD Grb2-binding protein. Src kinase activity is increased threefold after CSF-1 treatment. In src- cells, no attachment ring is present, and CSF-1 fails to induce spreading or a change in the pattern of F-actin distribution. Although c-fms becomes phosphorylated after CSF-1 treatment, the 85-kD protein is significantly less phosphorylated in src- osteoclast-like cells. These results indicate that c-src is critical for the normal cytoskeletal architecture of the osteoclast, and, in its absence, the spreading response induced by CSF-1 is abrogated, and downstream signaling from c-fms is altered.
Insogna
K L
KL
Department of Medicine, Yale School of Medicine, New Haven, Connecticut 06520-8020, USA. karl_insogna@qm.yale.edu
Sahni
M
M
Grey
A B
AB
Tanaka
S
S
Horne
W C
WC
Neff
L
L
Mitnick
M
M
Levy
J B
JB
Baron
R
R
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure*; D007700:Kinetics; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D016133:Polymerase Chain Reaction; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000172:deficiency / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity; D019061:src-Family Kinases / Q000378:metabolism*
D010455:Peptides; D010750:Phosphoproteins; D019000:Phosphotyrosine; D016173:Macrophage Colony-Stimulating Factor; D016392:Proto-Oncogene Proteins pp60(c-src); D019061:src-Family Kinases