p38 MAPK Signal is
Necessary for TNF-α Gene Expression in RAW Cells
JIANG Yong*, LIU Ai-Hua, HUANG Qiao-Bing and ZHAO
Ke-Seng
( Key Laboratory for Shock and Microcirculation of PLA , Department of
Pathophysiology,
The First Military Medical University, Guangzhou 510515, China
)
Abstract The luciferase reporter gene
system driven by the TNF-α promoter was constructed for the studies of the
effect of p38 MAPK signal transduction pathway on the gene expression of TNF-α.
In the experiments of co-transfection in RAW cells it was found that there was
a significant relevance between the activation of p38 by LPS and the induction
of TNF-α reporter gene transcription. The induction of TNF-α expression was not
shown after transfection of p38 only； co-transfection of p38
with the active mutant of its upstream kinase, MKK6b, however, did induce the
high expression of luciferase. Further studies showed that the induction of
TNF-α promoter activity by MKK6b(E) and LPS was similar. In addition, the
dominant negative form of p38 or p38 inhibitor gave an inhibitory effect on the
TNF-α promoter activity induced by MKK6b(E) or LPS. All these results suggest
that a possible mechanism for TNF-α production in endotoxic shock is the
increase in gene transactivity induced by LPS in monocytes/macrophages, and
that p38 MAPK signal pathway participates in the regulation of TNF-α gene
expression induced by LPS.
Key Words Lipopolysaccharide; tumor
necrosis factor; gene expression; p38 MAPK
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