Abstract
In this study we show that activation of p38MAPKby IL-6 acts as an inhibitory signal on IL-6-mediated activation of STAT and the α2-macroglobulin promoter. We analyzed the role of MKK6/p38MAPKfor IL-6 signal transduction and transcriptional activation of the suppressor of cytokine signaling (SOCS) 3 promoter. Pretreatment of cells with the p38MAPKspecific inhibitor SB202190 downregulates the induction of SOCS3-mRNA expression by IL-6. Accordingly, overexpression of a constitutively active MKK6 in HepG2 cells enhanced basal activity or IL-6-induced transcriptional activation of a SOCS3 promoter reporter construct, whereas overexpression of a dominant negative mutant of MKK6 downregulated the IL-6-mediated activation of the SOCS3 promoter. These data indicate that p38MAPKactivation is crucial for IL-6-induced SOCS3 expression and downregulation of IL-6-mediated gene induction.
Copyright © 2001 by Walter de Gruyter GmbH & Co. KG
