Signaling by the cysteinyl-leukotriene receptor 2 -: Involvement in chemokine gene transcription

Cysteinyl-leukotrienes are involved in inflammation and act on at least two G-protein-coupled receptors, CysLT1 and CysLT2. However, the role of the CysLT2 receptor as well as its signaling remain poorly understood. Here we show that leukotriene (LT)C-4 induced the production of the chemokine interleukin (IL)-8 in endothelial cells. To further study the signaling cascade involved, HEK293 cells were stably transfected with CysLT2 and used to study the transcriptional regulation of the IL-8 promoter. Stimulation of the cells with increasing concentrations of LTC4 resulted in a time- and concentration-dependent induction of IL-8 transcription and protein synthesis. Use of IL-8 promoter mutants with substitutions in their NF-kappa B, AP-1, or NF-IL-6 binding elements revealed an almost total requirement for NF-kappa B and AP-1 elements, and a lesser requirement for the NF-IL-6 element. Overexpression of dominant-negative I kappa B alpha prevented the IL-8 transactivation induced by LTC4. LTC4 stimulation induced NF-kappa B and AP-1 DNA binding, which involved the formation of a p50/p65 and a c-JUN.c-FOS complex, respectively. Transfection of the cells with a dominant negative (dn) form of PKC epsilon prevented p65 phosphorylation, whereas dnPKC delta prevented AP-1 binding. Moreover, dnPKC delta, dnPKC epsilon, and dnPKC delta prevented LTC4-induced IL-8 transcription in response to LTC4. Our data show for the first time that LTC4 can act via the CysLT2 receptor to transcriptionally activate chemokine production through induction of NF-kappa B and AP-1 transcription factors. These findings suggest the potential implication of CysLT2 in the inflammatory response through the modulation of chemokine gene transcription.