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Mol. Cells 2002; 13(3): 470-475

Published online January 1, 1970

© The Korean Society for Molecular and Cellular Biology

Rac GTPase Activity Is Essential for Lipopolysaccharide Signaling to Extracellular Signal-regulated Kinase and p38 MAP Kinase Activation in Rat-2 Fibroblasts

Chang-Hoon Woo, Jae-Hong Kim

Abstract

Lipopolysaccharide (LPS) has potent proinflammatory properties by acting on many cell types. Recently, mi-togen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase (ERK), p38 kinase, and c-jun N-terminal kinase (JNK) were shown to be involved in signal transduction in response to LPS. However, the detailed mechanism of LPS-induced signaling in the cell, especially the role of the Rho family GTPases remains largely unknown. In the present study, we investigated the role of Rac1, a mem-ber of the Rho family GTPases, in the LPS-induced MAPKs activation in Rat-2 fibroblasts. Our results showed that LPS induced the activation of ERK and p38 MAP kinase in a Rac-dependent manner, suggest-ing a mediatory role of Rac1 in LPS signaling to MAPKs stimulation. We also observed that LPS caused a time-dependent activation of Rac1. In addi-tion, our results have shown that pretreatment with herbimycin or wortmannin dramatically inhibited Rac1 activation induced by LPS. These suggest that tyrosine kinase(s) and phosphatidylinositol 3-kinase (PI 3-kinase) are possibly acting upstream of Rac1 in the LPS signaling to MAPKs.

Keywords Rac, ERK, Lipopolysaccharide, p38 Kinase

Article

Research Article

Mol. Cells 2002; 13(3): 470-475

Published online June 30, 2002

Copyright © The Korean Society for Molecular and Cellular Biology.

Rac GTPase Activity Is Essential for Lipopolysaccharide Signaling to Extracellular Signal-regulated Kinase and p38 MAP Kinase Activation in Rat-2 Fibroblasts

Chang-Hoon Woo, Jae-Hong Kim

Abstract

Lipopolysaccharide (LPS) has potent proinflammatory properties by acting on many cell types. Recently, mi-togen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase (ERK), p38 kinase, and c-jun N-terminal kinase (JNK) were shown to be involved in signal transduction in response to LPS. However, the detailed mechanism of LPS-induced signaling in the cell, especially the role of the Rho family GTPases remains largely unknown. In the present study, we investigated the role of Rac1, a mem-ber of the Rho family GTPases, in the LPS-induced MAPKs activation in Rat-2 fibroblasts. Our results showed that LPS induced the activation of ERK and p38 MAP kinase in a Rac-dependent manner, suggest-ing a mediatory role of Rac1 in LPS signaling to MAPKs stimulation. We also observed that LPS caused a time-dependent activation of Rac1. In addi-tion, our results have shown that pretreatment with herbimycin or wortmannin dramatically inhibited Rac1 activation induced by LPS. These suggest that tyrosine kinase(s) and phosphatidylinositol 3-kinase (PI 3-kinase) are possibly acting upstream of Rac1 in the LPS signaling to MAPKs.

Keywords: Rac, ERK, Lipopolysaccharide, p38 Kinase

Mol. Cells
May 31, 2023 Vol.46 No.5, pp. 259~328
COVER PICTURE
The alpha-helices in the lamin filaments are depicted as coils, with different subdomains distinguished by various colors. Coil 1a is represented by magenta, coil 1b by yellow, L2 by green, coil 2a by white, coil 2b by brown, stutter by cyan, coil 2c by dark blue, and the lamin Ig-like domain by grey. In the background, cells are displayed, with the cytosol depicted in green and the nucleus in blue (Ahn et al., pp. 309-318).

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