Polyphenols downregulate PAI-1 gene expression in cultured human coronary artery endothelial cells: Molecular contributor to cardiovascular protection

Epidemiologic data have indicated that the intake of polyphenols is inversely associated with mortality from cardiovascular disease. Mitogen-activated protein kinases (MAPKs) are ubiquitous signaling proteins that have been associated with gene regulation. This study determined whether polyphenols (catechin and quercetin) activated kinase-signaling cascades that suppress PAI-1 expression and whether this suppression is at the transcription level in human coronary artery endothelial cells (ECs) remains unresolved. ECs were incubated in the absence/presence of polyphenols and RNA and protein were analyzed by real-time PCR and Western blot analysis. MAPKs were analyzed using antibodies to active form of p38, JNK, and ERK1/2. ECs were transiently transfected with a 1.1-kb PAI-1 promoter (pPAI110/luc) and promoter activity were assays after treatment with polyphenols. Catechin and quercetin decreased EC PAI-1 mRNA in a time- and dose-dependent manner, reaching a maximum at 4 and 2 h, respectively. These polyphenols activated EC p38 and ERK1/2 within 2.5 and 5 min, respectively, while maximal JNK activation occurred at 10-15 min. An inhibitor of p38 MAPK had no effect on polyphenol-induced repression of PAI-1. Inhibitors of ERK or JNK prevented polyphenol repression of EC PAI-1 gene expression. Exposing ECs transiently transfected with pPAI110/luc to polyphenols decreased promoter activity 50%. Polyphenols repress EC PAI-1 expression, in part, by activating ERK and JNK signaling pathways and this repression is at transcriptional levels. Thus MAPK seem to play an important role in polyphenol-induce repression of PAI-1 expression in ECs.