Trilobatin Protects Against Oxidative Injury in Neuronal PC12 Cells Through Regulating Mitochondrial ROS Homeostasis Mediated by AMPK/Nrf2/Sirt3 Signaling Pathway

Abstract

Oxidative stress-induced neuronal cell damage is a crucial factor in the pathogenesis of mitochondria-associated neurological diseases. Therefore, elimination of overproduction of mitochondrial reactive oxygen species (mtROS) may be a potential strategy for prevention and treatment of neurological diseases. In the present study, the neuroprotective effects of trilobatin (TLB), a novel small molecule monomer derived from Lithocarpus polystachyus Rehd, and its underlying mechanisms were investigated in vitro using hydrogen peroxide (H2O2)-induced oxidative stress model in a neuron-like PC12 cell. The findings revealed that pre-treatment with TLB dramatically concentration-dependently suppressed H2O2-induced PC12 cells damage by enhancing cell viability, repressed reduction of mitochondrial membrane potential (MMP) and decreased mtROS overgeneration, thereby deferring cell apoptosis. Further study demonstrated that TLB not only increased the enzymatic activities of glutathione peroxidase (GPx), isocitrate dehydrogenase 2 (IDH2),superoxide dismutase 2 (SOD2) and deacetylation of SOD2, but also activated silent mating-type information regulation 2 homolog 3 (Sirt3) within the mitochondria and thereby upregulating forkheadboxO3a (FoxO3a), which regulated mitochondrial DNA genes, then led to improving complex I activity and adenosine triphosphate (ATP) synthesis. What’s more, TLB up-regulated p-adenosine monophosphate-activated protein kinase (AMPK) level, the expression of peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α), and ERRα. Intriguingly, TLB failed to mitigate H2O2-induced PC12 injury in the presence of the AMPK inhibitor (Compound C), indicating that the beneficial effects of TLB on the regulation of mtROS homeostasis were reliance on AMPK -Sirt3 signaling pathway. Moreover, TLB also facilitated nuclear factor erythroid 2-related factor 2 (Nrf2) and promoted antioxidant gene expression in turn, and knockdown of Nrf2 by siRNA dramatically reduced the neuroprotective effects of TLB. Notably, AMPK inhibitor abolished the activation of Nrf2 and Sirt3, whereas, knockdown of Nrf2 blocked the upregulation of Sirt3, but it did not affect p-AMPK level. In conclusion, our findings demonstrate that TLB protects against oxidative injury in neuronal PC12 cells through regulating mtROS homeostasis in the first time, which is, at least partly, mediated through the AMPK/Nrf2/Sirt3 signaling pathway.

tert-Butylhydroquinone Treatment Alleviates Contrast-Induced Nephropathy in Rats by Activating the Nrf2/Sirt3/SOD2 Signaling Pathway

“…Further, the Nrf-2a subunit was shown to directly bind to the Sirt3 promoter, and therefore, knockdown or overexpression of Nrf-2 could modulate Sirt3 levels in vitro system [12]. Similarly, the AMPK/Nrf2/Sirt3 axis was shown to be involved in the neuroprotective effects of TLB on H 2 O 2 -induced oxidative injury in PC12 cells, wherein the knockdown of Nrf2 led to the inhibition of Sirt3 [35]. Likewise, 17beta-estradiol was shown to enhance nuclear translocation of Nrf2, followed by Sirt3 upregulation and Mn-SOD Data were expressed as mean ± SD.…”

Icariside II inhibits lipopolysaccharide-induced inflammation and amyloid production in rat astrocytes by regulating IKK/IκB/NF-κB/BACE1 signaling pathway

“…Cell viability was assessed using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay as described in our previous study [ 38 ]. In brief, astrocytes were seeded in a 96-well plate at 1 × 10 5 cells/well and treated as described above.…”

“…Western blot analysis was performed as described in our previous study [ 38 ]. Briefly, astrocytes were treated as mentioned above, homogenized with protein extraction solution, and lysed for 40 min on ice.…”

Neuroprotection Against Oxidative Stress: Phytochemicals Targeting TrkB Signaling and the Nrf2-ARE Antioxidant System

“…The primary sources of ROS are mitochondrial oxidative phosphorylation, particularly by complex I and several redox enzymes (Zorov et al, 2014). Physiologically, a certain amount of ROS is essential for cell signaling and pro-survival pathways (Patten et al, 2010), but when ROS production overwhelms the cellular antioxidant defense system, cells are exposed to the pathological condition termed OS (Gao et al, 2018), which may lead to mitochondrial dysfunction and further ROS generation (Stelmashook et al, 2019). The endoplasmic reticulum, the primary site of protein folding, also involved in ROS generation (Chaudhari et al, 2014), and resulting protein misfolding causes ER stress and additional ROS overproduction (Lindholm et al, 2006).…”