Severe osteopetrosis, defective interleukin-1 signalling and lymph node organogenesis in TRAF6-deficient mice.
BACKGROUND
TRAF6, a member of the tumour necrosis factor receptor-associated factor family, was first identified as a transducer of CD40 and interleukin-1 receptor (IL-1R) signals based on the interaction of TRAF6 with the cytoplasmic tail of CD40 and with the IL-1R associated kinase in vitro. However, the functions of TRAF6 in vivo remain unidentified.


RESULTS
We show that TRAF6-/- mice exhibit severe osteopetrosis and are defective in osteoclast formation. In vitro culture experiments revealed that osteoclast precursor cells derived from TRAF6-/- mice are unable to differentiate to functional osteoclasts in response to osteoclast differentiation factor (ODF). In bone marrow of TRAF6-/- mice, the number of sIgM+B220+ immature B cells is markedly reduced while the ratio of proB to preB cells is not affected. In contrast, development of thymocytes is not affected. Furthermore, TRAF6-/- mice are defective in lymph node organogenesis and IL-1 signalling in thymocytes.


CONCLUSIONS
The results identify TRAF6 as an essential component of ODF signalling pathway, and also show that TRAF6 plays pivotal roles in immune and inflammatory systems in vivo.
Department of Oncology, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.
A
A
Naito
S
S
Azuma
S
S
Tanaka
T
T
Miyazaki
S
S
Takaki
K
K
Takatsu
K
K
Nakao
K
K
Nakamura
M
M
Katsuki
T
T
Yamamoto
J
J
Inoue
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002454:Cell Differentiation; D005314:Embryonic and Fetal Development; D007375:Interleukin-1 / Q000378:metabolism*; D008198:Lymph Nodes / Q000196:embryology*; D051379:Mice; D018345:Mice, Knockout; D010010:Osteoclasts / Q000166:cytology; D010022:Osteopetrosis / Q000235:genetics*; D011506:Proteins / Q000235:genetics* / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D013154:Spleen / Q000166:cytology; D048029:TNF Receptor-Associated Factor 6
D007375:Interleukin-1; D011506:Proteins; D018124:Receptors, Tumor Necrosis Factor; D048029:TNF Receptor-Associated Factor 6