Leukotriene D4 induces stress-fibre formation in intestinal epithelial cells via activation of RhoA and PKCδ

Abstract

The intestinal epithelial barrier, which is regulated by the actin cytoskeleton, exhibits permeability changes during inflammation. Here we show that activation of the CysLT1 receptor by the inflammatory mediator leukotriene D4 (LTD4) causes a rapid increase in stress-fibre formation in intestinal epithelial cells. This effect was mimicked by cytotoxic necrotising factor-1 (CNF-1)-induced activation of RhoA, overexpression of constitutively active RhoA (L63-RhoA) and phorbol-ester-induced activation of protein kinase C (PKC). In accordance, inhibition of RhoA, by C3 exoenzyme or by dominant-negative RhoA (N19-RhoA), as well as GF109203X-induced inhibition of PKC, suppressed the LTD4-induced stress-fibre formation. Introduction of the dominant-negative regulatory domain Of PKCδ, but not the corresponding structures from PKCα, βII or ε, blocked the LTD4-induced stress-fibre formation. Evaluating the relationship between PKCδ and RhoA in LTD4-induced stress-fibre formation, we found that C3 exoenzyme inhibited the rapid LTD4-elicited translocation of PKCδ to the plasma membrane. Furthermore, CNF-1-induced stress-fibre formation was blocked by GF109203X and by overexpression of the regulatory domain of PKC-δ, whereas PKC-induced stress-fibre production was not affected by N19-RhoA. We conclude that PKC-δ is located downstream of RhoA and that active RhoA and PKCδ are both necessary for LTD4-induced stress-fibre formation.