12-Lipoxygenase and Ischemic Brain Cell Death

描述(由申请人提供)：脂肪氧合酶和环氧合酶是导致中风后产生活性氧物种(ROS)的氧化酶之一。虽然环氧合酶COX-1和COX-2已经并将继续得到广泛的研究，但关于脂氧合酶在缺血性脑细胞死亡中的作用的数据很少。我们的初步结果表明，小鼠和大鼠脑中的主要脂氧合酶亚型12-LOX的水平在局灶性脑缺血小鼠模型中升高，主要是在大脑皮层的神经细胞中。12-LOX基因敲除的小鼠表现出显著的缩小梗塞面积，这一发现似乎与用12-LOX抑制剂治疗野生型小鼠相似。在大鼠原代神经元和小鼠海马神经细胞系中，我们证实并推广了其他人的发现，即12-LOX介导了氧化应激诱导的细胞死亡，从12-LOX基因敲除小鼠制备的神经元对这种形式的氧化应激表现出更强的抵抗力。因此，我们提出以下具体目标：1.研究12-LOX在小鼠脑缺血后不同复氧时间的表达和活性变化，并探讨12-LOX水平升高与脑损伤程度的关系；2.研究12-LOX促进培养神经细胞死亡的机制，阐明12-LOX作用下游执行细胞死亡的降解机制；3.确定12-LOX失活对小鼠局灶性脑缺血后脑损伤的影响。根据这些研究获得的知识，我们试图建立12-LOX作为治疗中风的新的治疗靶点。

DESCRIPTION (provided by applicant): Lipoxygenases and cyclooxygenases are among the oxidative enzymes that contribute to the generation of reactive oxygen species (ROS) after stroke. While the cyclooxygenases COX-1 and COX-2 have been and are continuing to be extensively studied, little data is available on the contribution of lipoxygenases to ischemic brain cell death. Our preliminary results have shown that levels of 12-LOX, the major lipoxygenase isoform in mouse and rat brain, are elevated in a mouse model of focal ischemia, predominantly in neuronal cells of the cortex. 12-LOX knockout mice show significantly reduced infarction sizes, a finding that seems to be mimicked by treatment of wild-type mice with a 12-LOX inhibitor. In both rat primary neurons and a murine hippocampal cell line, we have confirmed and extended the findings of others that 12-LOX mediates oxidative stress-induced cell death, and neurons prepared from the 12-LOX knockout mice show enhanced resistance to this form of oxidative stress. We thus propose the following Specific Aims: 1. To investigate 12-LOX upregulation and changes in activity in mouse brain after ischemia with various times of reoxyenation and to correlate increased 12-LOX levels with the extent of brain damage; 2. To study the mechanisms by which 12-LOX contributes to the death of cultured neuronal cells, and to elucidate the degradative machinery responsible for executing cell death downstream of 12-LOX action; 3. To determine the consequences of inactivating 12-LOX by either genetic or pharmacological means on brain damage after focal ischemia in the mouse. With the knowledge gained from these studies we seek to establish 12-LOX as a novel therapeutic target in the treatment of stroke.