氢醌代谢产物TGHQ介导活性氧依赖性细胞死亡模式的分子调控机制

Hydroquinone (HQ), a common form of pollution, is ubiquitously present in the environment. It’s also the major toxic metabolite of benzene. After absorption, HQ can be metabolized into adducts that exhibit increasing degrees of glutathione substitutions, of which 2,3,5-tris(glutathion-S-yl)-hydroquinone (TGHQ) is the most potent toxicant. TGHQ retains the ability to redox cycle and to create an oxidative stress. The generation of reactive oxygen species (ROS) has been implicated in the pathogenesis of tumor, cardiovascular diseases, diabetes, Alzheimer’s disease, and many other pathological conditions. Thus, increasing attention has been drawn to the molecular mechanism study of ROS-dependent cell death modes. We recently reported that TGHQ caused ROS-dependent cell death in both human renal proximal tubule epithelial cells (HK-2) and human promyelocytic leukemia (HL-60) cells, however, TGHQ induced apoptotic cell death in HL-60 cells but nonapoptotic cell death in HK-2 cells. Based on this, the current study is aimed to elucidate the modulation mechanism of ROS-dependent cell death modes by investigating PARP-1 and Nrf2, two most ROS-involving pathways, with the emphasis on comparing their respective signaling pathways between TGHQ-induced apoptotic and nonapoptotic cell death modes through combining different methods, including pharmacology, toxicology, proteomics, and computer modeling. This is of direct relevance to pointing to the prevention of diseases caused by exposure with HQ and benzene. Moreover, our study provides a better understanding of the mechanisms of ROS-dependent cell death, and assists in identifying novel targets for therapeutic intervention for those broad and diverse conditions of ROS related diseases.

氢醌广泛存在于自然界，是常见的环境污染物，还是苯的主要活性代谢物，进入机体后代谢为氢醌硫醚类毒性物质，其中毒性最大的是2,3,5-三谷胱甘肽氢醌硫醚，简称TGHQ。TGHQ能进行氧化还原循环，产生活性氧。由于活性氧能引起肿瘤、心血管疾病、糖尿病、老年痴呆等高发疾病，活性氧介导的细胞死亡模式日益受到关注。我们首次发现，TGHQ在人肾小管上皮细胞HK-2和人早幼粒白血病细胞HL-60中均介导活性氧依赖性细胞死亡，但TGHQ介导HL-60细胞凋亡而介导HK-2细胞非凋亡性死亡。在此基础上，本项目应用药理毒理、蛋白质组及分子模拟方法，以与活性氧密切相关的PARP和Nrf2信号通路为研究对象，重点比较其在细胞不同死亡模式中的转导通路，以阐明活性氧依赖性细胞死亡模式的调控机制。本项目不仅为防治苯及氢醌暴露引起的疾病提供理论指导，还能加深理解活性氧在病理过程中的分子机制，为诸多相关疾病的治疗提供新思路。

氢醌广泛存在于自然界，是常见的环境污染物，还是苯的主要活性代谢物，进入机体后代谢为氢醌硫醚类毒性物质，其中毒性最大的是2,3,5-三谷胱甘肽氢醌硫醚，简称TGHQ。TGHQ能进行氧化还原循环，产生活性氧。由于活性氧能引起肿瘤、心血管疾病、糖尿病、老年痴呆等高发疾病，活性氧介导的细胞死亡模式日益受到关注。我们首次发现，TGHQ在人肾小管上皮细胞HK-2和人早幼粒白血病细胞HL-60中均介导活性氧依赖性细胞死亡，但TGHQ介导HL-60细胞凋亡而介导HK-2细胞非凋亡性死亡。在此基础上，本项目结合药理学、毒理学及计算化学，考察了氢醌代谢产物TGHQ介导的PARP-1依赖性细胞死亡的下游信号通路及PARP-1与细胞内钙离子的相互调节机制；考察比较了TGHQ在HK-2 和HL-60 两种细胞中介导的活性氧依赖性细胞死亡中Nrf2信号通路的激活情况及作用机制；为了深入探讨TGHQ诱导活性氧产生的分子机制，研究结合分子对接技术阐明TGHQ与细胞线粒体中三种与活性氧产生密切相关的蛋白具有高亲和力，进而通过影响细胞线粒体呼吸链电子传递介导活性氧产生的新机制；此外，为了防治苯及氢醌暴露引起的慢性肾脏疾病中透析患者肝素使用的副作用，研究利用纳豆激酶的良好抗凝溶栓作用及其与肝素的相互作用，深入探讨了两者联用发挥减毒增效的分子机制，并对纳豆激酶进行了安全性评价，为慢性肾脏疾病透析患者提供新型有效的预防及治疗方案奠定了良好基础。