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Natural Polyphenol Chlorogenic Acid Protects Against Acetaminophen-Induced Hepatotoxicity by Activating ERK/Nrf2
Mengjuan Wei1, Zhiyong Zheng1, Liang Shi1
1The MOE Key Laboratory for Standardization of Chinese Medicines, Shanghai Key Laboratory of Complex Prescription and The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
Abstract:
Hepatotoxicity due to acetaminophen (APAP) overdose is a leading cause of drug-induced acute liver failure in clinic. Chlorogenic acid (CGA), a dietary polyphenol, was reported to prevent APAP-induced liver injury in our previous studies. This study aims to investigate the protection provided by CGA against APAP-induced hepatotoxicity via focusing on nuclear factor erythroid 2-related factor 2 (Nrf2) and extracellular regulated protein kinases (ERK)1/2. CGA prevented APAP-induced oxidative liver injury and enhanced Nrf2 activation in mice and in hepatocytes in vitro. CGA-provided the protection against APAP-induced hepatotoxicity was diminished after the application of Nrf2 siRNA in vitro and Nrf2 knockout mice in vivo. CGA enhanced the expression of heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase-1 (NQO1), and their inhibitors reduced the protection provided by CGA against APAP-induced cytotoxicity in hepatocytes. Molecular docking results indicated the potential interaction of CGA with Nrf2 binding site in Kelch-like ECH-associating protein-1 (Keap1). CGA decreased the expression of protein phosphatases including PP2A subunit A (PP2A-A) and PP5, and induced the sustained ERK1/2 phosphorylation. Moreover, ERK1/2 inhibitors (U0126 and PD98059) and ERK2 siRNA abrogated CGA-induced Nrf2 phosphorylation and its subsequent transcriptional activation, and also reduced the protection provided by CGA against APAP-induced cytotoxicity in hepatocytes. These results suggest that CGA protects against APAP-induced hepatotoxicity by activating Nrf2 antioxidative signaling pathway via blocking the binding of Nrf2 to its inhibitor protein Keap1, and ERK1/2 plays a critical role in regulating CGA-induced Nrf2 transcriptional activation. CGA is a promising therapeutic agent for the detoxification of APAP-induced hepatotoxicity.
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