Japanese Journal of Veterinary Research;Volume 52, Number 3

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Distribution of TNF receptors and TNF receptor-associiated intracellular signaling factors on equine tendinocytes in vitro

Hosaka, Yoshinao;Sakamoto, Yurie;Kirisawa, Rikio;Watanabe, Takafumi;Ueda, Hiromi;Takehana, Kazushige;Yamaguchi, Mamoru

Permalink : http://hdl.handle.net/2115/10519
JaLCDOI : 10.14943/jjvr.52.3.135
KEYWORDS : NF-κB;tendinocyte;TNFα;TNF-receptors;TRAF 2

Abstract

Although tumor necrosis factor (TNF)α is animportant key factor in degeneration of equine superficial digital flexor tendon (SDFT), the dynamism of TNF receptors and associated factors on tendinocytes has not been elucidated. To reveal signaling events mediated by TNF-receptors (TNF-Rs) in tendinocytes, we focused on four signaling factors, TNF-R1, TNF-R2, TNF-R-associated factor 2 (TRAF2) and nuclear factor-kappa B (NF-κB), and investigated the distribution and production of these factors. Cultured tendinocytes were obtained from SDFTs of thoroughbred horses. The tendinocytes were treated with 10ng/ml equine TNFα medium for 6 hours and then the four factors on tendinocytes were visualized by using an immunohistochemical method, and the amounts of the four factors were determined by Western blot analysis. Although TNF-R1 and TNF-R2 co-localized on the same tendinocyte, in untreated control cells (normal condition), immunoreactivity against TNF-R1 was very weak but TNF-R2 showed a strong reaction. However, TNF-R1 showed the same high level of reactionas TNF-R2 in TNFα-treated cells (inflamed condition). Intense TRAF2 and NF-κB were detected at inflamed condition, however both factors were also detected at normal condition. The distinct distributions of the four factors under diffrent conditions (normal and innamed condition) in vitro not only renect the dynamism of the cytokines but may also provide important clues for a means to prevent from occurrence of tendonitis and progress of tendon degeneration.

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