IL-1 regulates cytoskeletal organization in osteoclasts via TNF receptor-associated factor 6/c-Src complex.
Targeted disruption of either c-Src or TNFR-associated factor 6 (TRAF6) in mice causes osteoclast dysfunction and an osteopetrotic phenotype, suggesting that both molecules play important roles in osteoclastic bone resorption. We previously demonstrated that IL-1 induces actin ring formation and osteoclast activation. In this study, we examined the relationship between IL-1/TRAF6-dependent and c-Src-mediated pathways in the activation of osteoclast-like cells (prefusion cells (pOCs); multinucleated cells) formed in the murine coculture system. In normal pOCs, IL-1 induces actin ring formation and tyrosine phosphorylation of p130(Cas), a known substrate of c-Src. However, in Src-deficient pOCs, p130(Cas) was not tyrosine phosphorylated following IL-1 treatment. In normal pOCs treated with IL-1, anti-TRAF6 Abs coprecipitate p130(Cas), protein tyrosine kinase 2, and c-Src. In Src-deficient pOCs, this molecular complex was not detected, suggesting that c-Src is required for formation of the TRAF6, p130(Cas), and protein tyrosine kinase 2 complex. Moreover, an immunocytochemical analysis revealed that in osteoclast-like multinucleated cells, IL-1 induced redistribution of TRAF6 to actin ring structures formed at the cell periphery, where TRAF6 also colocalized with c-Src. Taken together, these data suggest that IL-1 signals feed into the tyrosine kinase pathways through a TRAF6-Src molecular complex, which regulates the cytoskeletal reorganization essential for osteoclast activation.
Nakamura
Ichiro
I
Department of Orthopedic Surgery, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
Kadono
Yuho
Y
Takayanagi
Hiroshi
H
Jimi
Eijiro
E
Miyazaki
Tsuyoshi
T
Oda
Hiromi
H
Nakamura
Kozo
K
Tanaka
Sakae
S
Rodan
Gideon A
GA
Duong
Le T
LT
D000199:Actins / Q000378:metabolism; D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D002478:Cells, Cultured; D018920:Coculture Techniques; D050719:Crk-Associated Substrate Protein; D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004789:Enzyme Activation / Q000235:genetics; D007375:Interleukin-1 / Q000502:physiology*; D007424:Intracellular Fluid / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D010010:Osteoclasts / Q000378:metabolism* / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism / Q000502:physiology*; D050717:Retinoblastoma-Like Protein p130; D015398:Signal Transduction / Q000235:genetics; D048029:TNF Receptor-Associated Factor 6; D014443:Tyrosine / Q000378:metabolism
D000199:Actins; C493842:Bcar1 protein, mouse; D050719:Crk-Associated Substrate Protein; D007375:Interleukin-1; D010750:Phosphoproteins; D011506:Proteins; D018124:Receptors, Tumor Necrosis Factor; D050717:Retinoblastoma-Like Protein p130; D048029:TNF Receptor-Associated Factor 6; D014443:Tyrosine; D016392:Proto-Oncogene Proteins pp60(c-src)