Up-regulation of Nrf2-mediated heme oxygenase-1 expression by eckol, a phlorotannin compound, through activation of Erk and PI3K/Akt

作者：Kim Ki Cheon; Kang Kyoung Ah; Zhang Rui; Piao Mei Jing; Kim Gi Young; Kang Mi Young; Lee Su Jae; Lee Nam Ho; Surh Young Joon; Hyun Jin Won^*

来源：International Journal of Biochemistry & Cell Biology, 2010, 42(2): 297-305.

DOI：10.1016/j.biocel.2009.11.009

• Eckol
• Heme oxygenase-1
• NF-E2-related factor 2
• Oxidative stress
• Cytoprotection
• Extracellular regulated kinase
• Phosphatidylinositol 3-kinase

The aim of the present study was to examine the cytoprotective effect of eckol, a phlorotannin found in Ecklonia cava and to elucidate underlying mechanisms. Heme oxygenase-1 (HO-1) is an important antioxidant enzyme that plays a role in cytoprotection against oxidative stress. Eckol-induced HO-1 expression both at the level of mRNA and protein in Chinese hamster lung fibroblast (V79-4) cells, resulting in increased HO-1 activity. The transcription factor NF-E2-related factor 2 (Nrf2) is a critical regulator of HO-1, achieved by binding to the antioxidant response element (ARE). Eckol treatment resulted in the enhanced level of phosphorylated form, nuclear translocation, ARE-binding, and transcriptional activity of Nrf2. Extracellular regulated kinase (Erk) and phosphaticylinositol 3-kinase (PI3K)/protein kinase B (PKB, Akt) contributed to ARE-driven HO-1 expression. Eckol activated both Erk and Akt, and treatments with U0126 (an Erk kinase inhibitor), LY294002 (a PI3K inhibitor), specific Erk1 siRNA, and Akt siRNA suppressed the eckol-induced activation of Nrf2, resulting in a decrease in HO-1 expression. ZnPP (a HO-1 inhibitor), HO-1 siRNA, and Nrf2 siRNA markedly abolished the cytoprotective effect of eckol against hydrogen peroxide-induced cell damage. Likewise, U0126 and LY294002 inhibited the eckol-induced cytoprotective effect against oxidative cell damage. These studies demonstrate that eckol attenuates oxidative stress by activating Nrf2-mediated HO-1 induction via Erk and PI3K/Akt signaling.

• 出版日期2010-2