Disruption of the actin cytoskeleton results in nuclear factor-κB activation and inflammatory mediator production in cultured human intestinal epithelial cells

The cytoskeleton in eukaryotic cells is composed of two major filament systems, the microtubule system and the actin cytoskeleton. The microtubule system has recently emerged as an important regulator of NF-κB function. However, the role that the actin microfilament system plays in controlling NF-κB activation is incompletely understood. In this study, we examined the effect of actin cytoskeleton disruption on NF-κB activation in human intestinal epithelial cells. Treatment of HT-29 or Caco-2 cells with the prototypic actin disrupting agents cytochalasin D or latrunculin B resulted in increased NF-κB DNA binding and NF-κB-dependent transcriptional activity. This NF-κB activation by cytochalasin D was secondary to an effect on IκB, because cytochalasin D-induced IκB degradation and the cytochalasin D-induced increase in NF-κB-dependent transcriptional activity was prevented by a dominant negative IκB mutant. Exposure of the cells to cytochalasins or latrunculin B increased gene expression and release of the NF-κB-dependent chemokines IL-8 and GRO-α. Cytochalasin D also activated p38 MAP kinase, which pathway contributed to the cytochalasin D-induced increase in IL-8 production. These results demonstrate that the actin cytoskeleton plays an important role in the regulation of NF-κB activation and inflammatory events in intestinal epithelial cells.