Inhibition of bromodomain-containing protein 4 ameliorates oxidative stress-mediated apoptosis and cartilage matrix degeneration through activation of NF-E2-related factor 2-heme oxygenase-1 signaling in rat chondrocytes
Inhibition of bromodomain-containing protein 4 ameliorates oxidative stress-mediated apoptosis and cartilage matrix degeneration through activation of NF-E2-related factor 2-heme oxygenase-1 signaling in rat chondrocytes
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DOI：
10.1002/jcb.27122
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发表时间：
2018-09-01
影响因子：
4
通讯作者：
Zhang, Yin-gang
中科院分区：
文献类型：
--
作者：
An, Qin-de;Li, Yun-yun;Zhang, Yin-gang
在骨关节炎的进展过程中，细胞外基质（ECM）合成代谢失调、活性氧和蛋白水解酶的异常产生已被证明会加速软骨的降解过程。本研究的目的是研究含溴结构域蛋白4 （BRD4）在过氧化氢（H2O2）刺激的软骨细胞损伤中的功能作用，并描述其潜在的分子机制。我们观察到H2O2刺激后大鼠软骨细胞中BRD4的表达明显升高。此外，使用小干扰RNA或JQ1（一种选择性强的化学抑制剂）抑制BRD4可抑制H2O2诱导的氧化应激，结果表明，当软骨细胞暴露于H2O2时，活性氧产生减少，丙二醛含量下降，抗氧化标记物超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶的活性增加。同时，BRD4的缺失导致H2O2引发的氧化应激诱导的软骨细胞凋亡受到抑制，同时抗凋亡的Bcl-2表达升高，促凋亡的Bax和caspase 3表达降低，caspase 3活性减弱。此外，BRD4敲低或JQ1处理显著减弱ECM沉积，反映在蛋白多糖II型胶原蛋白和聚集蛋白的显著上调，以及ECM降解酶基质金属蛋白酶13和a崩解素和具有血栓反应蛋白基元5 （ADAMTS-5）的下调。更重要的是，brd4激活的nf - e2相关因子2 (Nrf2)-血红素加氧酶-1信号的抑制。在机制上，BRD4抑制对h2o2刺激的细胞凋亡和软骨基质变性的保护作用被Nrf2耗尽明显取消。总之，我们得出结论，BRD4抑制对氧化应激介导的细胞凋亡和软骨基质变性的保护作用是通过nrf2 -血红素加氧酶-1信号发生的，这意味着BRD4抑制可能是一种更有效的骨关节炎治疗策略。
During the progression of osteoarthritis, dysregulation of extracellular matrix (ECM) anabolism, abnormal generation of reactive oxygen species, and proteolytic enzymes have been shown to accelerate the degradation process of cartilage. The purpose of the current study was to investigate the functional role of bromodomain-containing protein 4 (BRD4) in hydrogen peroxide (H2O2)-stimulated chondrocyte injury and delineate the underlying molecular mechanisms. We observed that the expression BRD4 was markedly elevated in rat chondrocytes after H2O2 stimulation. Additionally, inhibition of BRD4 using small interfering RNA or JQ1 (a selective potent chemical inhibitor) led to repression of H2O2-induced oxidative stress, as revealed by a decrease in the reactive oxygen species production accompanied by a decreased malondialdehyde content, along with increased activities of antioxidant markers superoxide dismutase, catalase, and glutathione peroxidase on exposure of chondrocytes to H2O2. Meanwhile, depletion of BRD4 led to repress the oxidative stress-induced apoptosis of chondrocytes triggered by H2O2 accompanied by an increase in the expression of anti-apoptotic Bcl-2 and a decrease in the expression of pro-apoptotic Bax and caspase 3 as well as attenuated caspase 3 activity. Moreover, knockdown of BRD4 or treatment with JQ1 markedly attenuated ECM deposition, reflected in a marked upregulation of proteoglycans collagen type II and aggrecan as well as downregulation of ECM-degrading enzymes matrix metalloproteinase 13 and A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5). More importantly, inhibition of BRD4-activated NF-E2-related factor 2 (Nrf2)-heme oxygenase-1 signaling. Mechanistically, the protective effect of BRD4 inhibition on H2O2-stimulated apoptosis and cartilage matrix degeneration was markedly abrogated by Nrf2 depletion. Altogether, we concluded that the protective effect of BRD4 inhibition against oxidative stress-mediated apoptosis and cartilage matrix degeneration occurred through Nrf2-heme oxygenase-1 signaling, implying that BRD4 inhibition may be a more effective therapeutic strategy against osteoarthritis.