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This Article Full Text Full Text (PDF) All Versions of this Article: 294/4/G928    most recent 00219.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Jin, S. Articles by Johnson, L. R. Search for Related Content PubMed PubMed Citation Articles by Jin, S. Articles by Johnson, L. R.

HORMONES AND SIGNALING

TNF-/cycloheximide-induced apoptosis in intestinal epithelial cells requires Rac1-regulated reactive oxygen species

Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee

Submitted 16 May 2007 ; accepted in final form 17 January 2008

Previously we have shown that both Rac1 and c-Jun NH₂-terminal kinase (JNK1/2) are key proapoptotic molecules in tumor necrosis factor (TNF)-/cycloheximide (CHX)-induced apoptosis in intestinal epithelial cells, whereas the role of reactive oxygen species (ROS) in apoptosis is unclear. The present studies tested the hypothesis that Rac1-mediated ROS production is involved in TNF--induced apoptosis. In this study, we showed that TNF-/CHX-induced ROS production and hydrogen peroxide (H₂O₂)-induced oxidative stress increased apoptosis. Inhibition of Rac1 by a specific inhibitor NSC23766 prevented TNF--induced ROS production. The antioxidant, N-acetylcysteine (NAC), or rotenone (Rot), the mitochondrial electron transport chain inhibitor, attenuated mitochondrial ROS production and apoptosis. Rot also prevented JNK1/2 activation during apoptosis. Inhibition of Rac1 by expression of dominant negative Rac1 decreased TNF--induced mitochondrial ROS production. Moreover, TNF--induced cytosolic ROS production was inhibited by Rac1 inhibition, diphenyleneiodonium (DPI, an inhibitor of NADPH oxidase), and NAC. In addition, DPI inhibited TNF--induced apoptosis as judged by morphological changes, DNA fragmentation, and JNK1/2 activation. Mitochondrial membrane potential change is Rac1 or cytosolic ROS dependent. Lastly, all ROS inhibitors inhibited caspase-3 activity. Thus these results indicate that TNF--induced apoptosis requires Rac1-dependent ROS production in intestinal epithelial cells.

intestinal epithelial cells-6; N17Rac1; diphenyleneiodonium; JNK1/2; oxidative stress