PAR1-dependent COX-2/PGE2 production contributes to cell proliferation via EP2 receptors in primary human cardiomyocytes.
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ABSTRACT: BACKGROUND AND PURPOSE: Different protease-activated receptors (PARs) activated by thrombin are involved in cardiovascular disease, via up-regulation of inflammatory proteins including COX-2. However, the mechanisms underlying thrombin-regulated COX-2 expression in human cardiomyocytes remain unclear. EXPERIMENTAL APPROACH: Human cardiomyocytes were used in the study. Thrombin-induced COX-2 protein and mRNA expression, and signalling pathways were determined by Western blot, real-time PCR and COX-2 promoter luciferase reporter assays, and pharmacological inhibitors or siRNAs. PGE2 generation and cell proliferation were also determined. KEY RESULTS: Thrombin-induced COX-2 protein and mRNA expression, promoter activity and PGE2 release was attenuated by the PAR1 antagonist (SCH79797) or the inhibitors of proteinase activity (PPACK), MEK1/2 (U0126), p38 MAPK (SB202190) or JNK1/2 (SP600125), and transfection with small interfering RNA (siRNA) of PAR1, p38, p42 or JNK2. These results suggested that PAR1-dependent MAPKs participate in thrombin-induced COX-2 expression in human cardiomyocytes. Moreover, thrombin stimulated phosphorylation of MAPKs, which was attenuated by PPACK and SCH79797. Furthermore, thrombin-induced COX-2 expression was blocked by the inhibitors of AP-1 (tanshinone IIA) and NF-?B (helenalin). Moreover, thrombin-stimulated phosphorylation of c-Jun/AP-1 and p65/NF-?B was attenuated by tanshinone IIA and helenalin, respectively, suggesting that thrombin induces COX-2 expression via PAR1/MAPKs/AP-1 or the NF-?B pathway. Functionally, thrombin increased human cardiomyocyte proliferation through the COX-2/PGE2 system linking to EP2 receptors, as determined by proliferating cell nuclear antigen and cyclin D1 expression. CONCLUSIONS AND IMPLICATIONS: These findings demonstrate that MAPKs-mediated activation of AP-1/NF-?B pathways is, at least in part, required for COX-2/PGE2 /EP2 -triggered cell proliferation in human cardiomyocytes.
SUBMITTER: Chien PT
PROVIDER: S-EPMC4209155 | biostudies-literature | 2014 Oct
REPOSITORIES: biostudies-literature
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