Glycogen synthase kinase-3β (GSK-3β), a multifunctional kinase, is a regulator of lipopolysaccharide (LPS)-mediated septic shock. Apoptosis signal-regulating kinase 1 (ASK1) is also required for LPS-induced activation of p38, which is a crucial determinant for the production of pro-inflammatory cytokines via Toll-like receptor 4 (TLR4) in endotoxemia. Here, we show that attenuation of endotoxemia induced by GSK-3 inhibition is caused by the ASK1 reduction-mediated inhibition of p38, a representative downstream kinase of ASK1. LPS-stimulated activation of p38 was blocked by the reduction of ASK1 via the knockdown of GSK-3β In addition, compared with L929 control cells, ASK1 protein was reduced in L929 cells stably expressing Wnt-3a and in which β-catenin was active, due to the inhibition of GSK-3β activity. GSK-3β inhibition-mediated ASK1 reduction was also confirmed by reduced ASK1 in GSK-3β-deficient mouse embryo fibroblasts (MEFs) and MCF7 GSK-3β siRNA cells. Furthermore, ASK1 protein stability was also attenuated in MCF7 GSK-3β siRNA cells compared with GFP control cells. Consistent with stability data, a much stronger ubiquitination of ASK1 was observed in cells in which GSK-3β was knocked down. These findings suggest that GSK-3β crosstalks with p38 kinase via the regulation of ASK1 protein stability in endotoxemia.
Bibliographical noteFunding Information:
We would like to thank Dr. J. R. Woodgett (Ontario Cancer Institute, Toronto, Canada) for providing GSK-3β +/+ and GSK-3β −/− MEFs, and Dr. Hyunsung Park (University of Seoul, South Korea) for providing L929 control and Wnt-3a stable cells. This work was supported by the National Research Foundation of Korea (NRF) grant ( 2006-0093855 , 2009-0080985 , 2010-0001197 ), and by the Original Technology Research Program for Brain Science ( 20090081488 ) through NRF funded by the Korea government ( MEST ).
ASJC Scopus subject areas
- Cell Biology