Fondazione Italiana Fegato ONLUS, Italian Liver Foundation ONLUS, Bldg Q AREA Science Park - Basovizza Campus, 34149 Trieste, Italy.
Fondazione Italiana Fegato ONLUS, Italian Liver Foundation ONLUS, Bldg Q AREA Science Park - Basovizza Campus, 34149 Trieste, Italy; Department of Medical Sciences, University of Trieste, 34100 Trieste, Italy.
Cell Signal. 2014 Mar;26(3):512-20. doi: 10.1016/j.cellsig.2013.11.029. Epub 2013 Dec 2.
Unconjugated bilirubin (UCB) is responsible for neonatal jaundice and high level of free bilirubin (Bf) can lead to kernicterus. Previous studies suggest that oxidative stress is a critical component of UCB-induced neurotoxicity. The Nrf2 pathway is a powerful sensor for cellular redox state and is activated directly by oxidative stress and/or indirectly by stress response protein kinases. Activated Nrf2 translocates to nucleus, binds to Antioxidant Response Element (ARE), and enhances the up-regulation of cytoprotective genes that mediate cell survival. The aim of the present study was to investigate the role of Nrf2 pathway in cell response to bilirubin mediated oxidative stress in the neuroblastoma SH-SY5Y cell line. Cells exposed to a toxic concentration of UCB (140 nM Bf) showed an increased intracellular ROS levels and enhanced nuclear accumulation of Nrf2 protein. UCB stimulated transcriptional induction of ARE-GFP reporter gene and induced mRNA expression of multiple antioxidant response genes as: xCT, Gly1, γGCL-m, γGCL-c, HO-1, NQO1, FTH, ME1, and ATF3. Nrf2 siRNA decreased UCB induced mRNA expression of HO1 (75%), NQO1 (54%), and FTH (40%). The Nrf2-related HO-1 induction was reduced to 60% in cells pre-treated with antioxidant (NAC) or specific signaling pathway inhibitors for PKC, P38α and MEK1/2 (80, 40 and 25%, respectively). In conclusion, we demonstrated that SH-SY5Y cells undergo an adaptive response against UCB-mediated oxidative stress by activation of multiple antioxidant response, in part through Nrf2 pathway.
未结合胆红素（UCB）是导致新生儿黄疸的原因，而游离胆红素（Bf）水平升高可导致核黄疸。先前的研究表明，氧化应激是 UCB 诱导神经毒性的关键组成部分。Nrf2 通路是细胞氧化还原状态的有力传感器，可直接被氧化应激激活，或间接被应激反应蛋白激酶激活。激活的 Nrf2 易位到细胞核，与抗氧化反应元件（ARE）结合，并增强介导细胞存活的细胞保护基因的上调。本研究旨在探讨 Nrf2 通路在神经母细胞瘤 SH-SY5Y 细胞系对胆红素介导的氧化应激细胞反应中的作用。暴露于有毒浓度 UCB（140 nM Bf）的细胞显示细胞内 ROS 水平升高，Nrf2 蛋白核内积累增强。UCB 刺激 ARE-GFP 报告基因的转录诱导，并诱导多种抗氧化反应基因的 mRNA 表达，如：xCT、Gly1、γGCL-m、γGCL-c、HO-1、NQO1、FTH、ME1 和 ATF3。Nrf2 siRNA 降低了 UCB 诱导的 HO1（75%）、NQO1（54%）和 FTH（40%）的 mRNA 表达。在用抗氧化剂（NAC）或特定信号通路抑制剂（PKC、P38α 和 MEK1/2）预处理的细胞中，Nrf2 相关的 HO-1 诱导降低至 60%（分别为 80%、40%和 25%）。总之，我们证明 SH-SY5Y 细胞通过激活多种抗氧化反应来应对 UCB 介导的氧化应激，部分通过 Nrf2 通路。
