ERK1/2 and NFκB are key signaling pathways in the regulation of CXCL8 expression and secretion by intestinal epithelial cells in response to P2Y6 receptor activation (39.43)

Abstract

Abstract Extracellular nucleotides are recognized as inflammatory-active molecules. We have investigated the role of extracellular uridine 5'-triphosphate (UDP) and its associated P2Y6 receptor in the secretion of CXCL8 by intestinal epithelial cells. We have also characterized signaling pathways linking UDP to the expression of CXCL8. The effect of the P2Y6 activation by UDP on chemokine expression and release by epithelial cells was determined using combination of western blots, luciferase assays, Q-PCR and ELISA. We have monitored the activation of different signaling molecules by western blots, luciferase assays and EMSA, along with different pharmacological inhibitors. Stimulation of Caco-2 cells with UDP lead to PKCδ and PKCζ, as well as ERK 1/2 and NFκB-p65 phosphorylation. Mutations of the NFκB binding site in the minimal promoter of the human CXCL8 completely abolished the luciferase activity stimulated with UDP. EMSA assays showed the importance of NFκB binding site for the initiation of transcription of CXCL8 by P2Y6. In this study, we showed the most detailed signaling pathway known so far for P2Y6 receptor its implication in UDP stimulate CXCL8 expression and release by intestinal epithelial cells.