新的血管硒蛋白的纯化、表征及生物功能研究

Studies of the purification, characterization of vascular selenoproteins and their biological functions Huang Kaixun, Xu Huibi, Chen Zexian, Qu Xianghu, Deng Ying, Wu Qingzhi, Liu Hongmei, Deng Liqun, Tang Rong and Li Hong Huazhong University of Science and Technology, Wuhan, 430074 Abstract Selenium (Se) exists as Se-containing proteins in mammalians and exerts essential biological functions through Se-containing proteins. Atherosclerosis is a multiple vascular disease threatened severely the health of human and, has been the main disease caused to death in developed countries since the middle of 20 century. The results of epidemiological investigation showed that there is a closely relationship between cardiovascular diseases and the Se-deficient in the organism, in particularly, a Se deficiency has been incriminated strongly in the etiology of atherosclerosis. However, the study on the selenoproteins in blood vessel did not be reported before our research. To explore the distributions and biological functions of Se in the blood vessel, and provide the experimental evidences for the elucidation of the biological functions of selenoproteins in blood vessel, this researches including the primary purification, characterization and biological functions of selenoproteins in rat arterial wall have been proceeded in the integer, cell and molecular levels using the chemical and biochemical techniques such as isotopic tracing, gel filtration chromatography, isoelectrofocusing, gel electrophoresis, RT-PCR, scanning electron microscope, transmission electron microscope and so on. Eight Se-containing proteins have been found in the rat arterial wall for the first time, the molecular weight of them is 76.4, 67.0, 57.4, 30.3, 25.4, 22.7, 21.7 and 15.1 KD, respectively. Two of them have been purified and characterized as 67.0 and 15.1 kD Se-containing protein with isoelectric point at 4.5 and 5.1, respectively. By comparison effects of the Se status on activities and gene expressions of rat arterial wall selenoenzymes, glutathione peroxidase (GPx) and thioredoxin reductase (TR), different mechanisms were observed: the synthesis of GPx was controlled by selenium status in arterial wall, but the regulation of the expression of TR was mediated by reactive oxygen species (ROS) redox pathway. The activity and expression of TR were increased in the Se-deficient rats arterial walls compared to that in control. The presumed mechanism might be related to the regulation of ROS redox pathway. In the state of low Se, Se in rat arterial wall was incorporated preferentially into TR as SeCys in the regulation of ROS signaling rather than into GPx. Selenoproteins play a key role in the maintenance of vascular biological functions. In the status of Se-deficiency, oxidized cholestane induced severe damages in rat arterial endothelium, induced deeply effects on the activities of a series of related enzymes, the level of NO, the cellular channel of calcium, and other biochemical parameters of blood. The preventive mechanism of selenoproteins against vascular diseases such as atherosclerosis may be related to the capacities of selenoproteins in oxidative stress defense and influencing activities of some antioxidant enzymes in blood through the regulation of ROS.

通过对血管硒蛋白的分离、纯化和表征来确定硒在血管中的存在状态、根据硒与动脉粥样硬化、血栓、高血压等血管疾病的关系和血管疾病的氧化损伤学说开展对血管硒蛋白的生物功能和作用机理研究，不仅有可能导致新的硒蛋白（酶）的发现，而且对进一步认识硒的生物功能和作用机理以及为揭示硒与血管疾病的关系提供理论依据均具有十分重要的科学意义。