Despite evidence supporting a potential role for F2-isoprostanes (F2-IsoPs) in liver fibrosis, their signalling mechanisms are poorly understood. We have previously provided evidence that F2-IsoPs stimulate hepatic stellate cell (HSC) proliferation and collagen hyperproduction by activation of a modified form of isoprostane receptor homologous to the classic thromboxane receptor (TP). In this paper, we examined which signal transduction pathways are set into motion by F2-IsoPs to exert their fibrogenic effects. HSC were isolated from the rat liver, cultured to their activated myofibroblast-like phenotype, and then treated with the isoprostane 15-F2-isoprostane (15-F2t-IsoP). Inositol trisphosphate (IP3) and adenosine 3’,5’-cyclic monophosphate (cAMP) levels were determined by commercial kits. Mitogen-activated protein kinases (MAPK) and cyclin D1 expression were assessed by western blotting. Cell proliferation and collagen synthesis were determined by measuring [3H]-thymidine and [3H]-proline incorporation, respectively. 15-F2t-IsoP elicited an activation of extracellular signal-regulated kinase (ERK), p38 MAPK, and c-Jun HN2-terminal kinase (JNK), that are known to be also regulated by G-protein-coupled receptors. Preincubation with specific ERK (PD98059), p38 (SB203580) or JNK (SP600125) inhibitors prevented 15-F2t-IsoP-induced cell proliferation and collagen synthesis. 15-F2t-IsoP decreased cAMP levels within 30 minutes, suggesting the binding to TP isoform and activation of Gi protein. Also, 15-F2t-IsoP increased IP3 levels within few minutes, suggesting that Gq protein pathway is also involved. In conclusion, the fibrogenic effects of F2-IsoPs in HSC are mediated by downstream activation of MAPK, through TP binding that couples via both Gq and Gi proteins. Targeting TP receptor, or its downstream pathways, may contribute to prevent oxidative damage in liver fibrosis.
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|Titolo:||Signalling pathways involved in isoprostane-mediated fibrogenic effects in rat hepatic stellate cells|
|Citazione:||Acquaviva, A., Vecchio, D., Arezzini, B., Comporti, M., & Gardi, C. (2013). Signalling pathways involved in isoprostane-mediated fibrogenic effects in rat hepatic stellate cells. FREE RADICAL BIOLOGY & MEDICINE, 65(C), 201-207.|
|Appare nelle tipologie:||1.1 Articolo in rivista|