Wu Y, Liu J, Zhang Z, Huang H, Shen J, Zhang S, Jiang Y, Luo L, Yin Z

Heat shock protein 27 (HSP27) is an ubiquitiously expressed protein, which has been mediated in various biological functions. Here, we present a novel mechanism utilized by HSP27 in regulating IL-1beta induced NF-small ka, CyrillicB activation. Both over-expression and RNAi experiments indicate that HSP27 physically interacts with tumor necrosis factor receptor-associated ...

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factor 6 (TRAF6) and promotes TRAF6 ubiquitination. Over-expressed HSP27 augments IL-1beta induced TRAF6 ubiquitination and Ismall ka, CyrillicB kinase (IKK) activation. On the other hand, IL-1beta stimulation reduces endogenous HSP27/TRAF6 association, but inhibiting HSP27 phosphorylation by using SB202190, an inhibitor of p38, and MAPKAPK2 RNAi increases HSP27/TRAF6 association and thereby enhances TRAF6 ubiquitination, IKK phosphorylation as well as NF-small ka, CyrillicB activation. Furthermore, co-transfection study shows that HSP27 S78/82A, two phosphorylated serine site deficient mutants, but not wild-type HSP27 (HSP27 WT) and HSP27 S15A mutant increases TRAF6 ubiquitination and thereby mediates IL-1beta triggered IKK phosphorylation. Taken together, our data indicate that HSP27 regulates IL-1beta triggered NF-small ka, CyrillicB activation via a feedback loop which includes the interaction between HSP27 phosphorylation and ability of HSP27 to bind with TRAF6. The findings of this study reveal a novel mechanism by which HSP27 controls cytokine stimulation.

Date: Jan. 01, 2009

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