Daphnetin-mediated Nrf2 antioxidant signaling pathways ameliorate tert-butyl hydroperoxide (t-BHP)-induced mitochondrial dysfunction and cell death

Abstract

Daphnetin (Daph), a natural coumarin derivative isolated from plants of the Genus Daphne, possesses abundant biological activities, such as anti-inflammatory, antioxidant and anticancer properties. In the present study, we focused on investigating the protective effect of Daph against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage, mitochondrial dysfunction and the involvement of underlying molecular mechanisms. Our findings indicated that Daph effectively inhibited t-BHP-stimulated cytotoxicity, cell apoptosis, and mitochondrial dysfunction, which are associated with suppressed reactive oxygen species (ROS) generation, decreased malondialdehyde (MDA) formation, increased superoxide dismutase (SOD) levels and glutathione (GSH)/GSSG (oxidized GSH) ratio. Further investigation indicated that Daph significantly suppressed cytochrome c release and NLRP3 inflammasome activation and modulated apoptosis-related protein Bcl-2, Bax, and caspase-3 expression. Moreover, Daph dramatically induced the expression of the glutamate-cysteine ligase modifier (GCLM) subunit and the glutamate-cysteine ligase catalytic (GCLC) subunit, heme oxygenase-1 (HO-1), and NAD (P) H: quinone oxidoreductase (NQO1), which is largely dependent on upregulating the nuclear factor-erythroid 2-related factor 2 (Nrf2) nuclear translocation, reducing the Keap1 protein expression, and strengthening the antioxidant response element (ARE) promoter activity. Additionally, Daph remarkably activated a c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation, but ERK and JNK inhibitor pretreatment exhibited an evident decrease of the level of Daph-enhanced Nrf2 nuclear translocation. Furthermore, Daph exposure suppressed t-BHP-induced cytotoxicity and ROS overproduction, which are mostly blocked in Nrf2 knockout RAW 264.7 cells and peritoneal macrophages. Accordingly, Daph exhibited protective roles against t-BHP-triggered oxidative damage and mitochondrial dysfunction by the upregulation of Nrf2 antioxidant signaling pathways, which may be involved in the activation of JNK and ERK.

Cerebroprotection by salvianolic acid B after experimental subarachnoid hemorrhage occurs via Nrf2- and SIRT1-dependent pathways

“…The Nrf2 signaling pathway, a primary host defense, plays an important role in the maintenance of cellular homeostasis [18,19,32]. Under normal conditions, Nrf2 is located mainly in the cytoplasm and anchored by the Kelch-like ECH-associated protein 1 (Keapl).…”

“…Third, how SalB modulates SIRT1 and Nrf2 activation is not fully elucidated. It is known that adenosine monophosphate-activated protein kinase (AMPK) and PI3K, which serve as upstream protein kinases of Nrf2, also play key roles in the regulation of Nrf2 [18]. Previous studies have reported that SIRT1 deacetylates LKB1 and secondarily affects AMPK, and that SalB can directly affect AMPK and PI3K [68,72,73].…”

“…Nuclear factor-erythroid 2-related factor 2 (Nrf2) is an essential transcription factor that controls the intrinsic antioxidative system to reduce the progression of various oxidative stress-related disorders [18–21]. After stimulation, Nrf2 translocates into the nucleus and binds to the antioxidant response element (ARE), thereby promoting transcription of several antioxidant and detoxification genes, such as heme oxygenase-1 (HO-1), NADPH: quinine oxidoreductase-1 (NQO-1), and superoxide dismutase (SOD) [18–21].…”

“…After stimulation, Nrf2 translocates into the nucleus and binds to the antioxidant response element (ARE), thereby promoting transcription of several antioxidant and detoxification genes, such as heme oxygenase-1 (HO-1), NADPH: quinine oxidoreductase-1 (NQO-1), and superoxide dismutase (SOD) [18–21]. HO-1, one of the cytoprotective enzymes activated by the Nrf2 pathway, plays a critical role in maintaining cellular homeostasis by degrading heme [22,23].…”

Epigallocatechin-3-Gallate Ameliorates Angiotensin II-Induced Oxidative Stress and Apoptosis in Human Umbilical Vein Endothelial Cells through the Activation of Nrf2/Caspase-3 Signaling

“…Activation of the Nrf2 expression elevated cell survival under stress environments [45,46,47]. Previous reports have revealed that Nrf2 accumulation has been induced by the activation of MAPKs, which act as a central regulatory pathway for the upregulation of antioxidant enzyme expression [48].…”