Molecular mechanism of the novel oxidative stress in diabetes

糖尿病新型氧化应激的分子机制

基本信息

批准号：
16580109
负责人：
TAKENAKA Asako
金额：
$ 2.37万
依托单位：
Meiji University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16580109/
关键词：
α-tocopherol vitamin E α-TTP insulin lysosome proteasome insulin

项目摘要

It has bee reported that a-tocopherol (vitamin E) concentration in blood was reduced in diabetic patients and animals that could induce another oxidative stress by reducing anti-oxidative activity. It has been established that liver has the main role to secrete food-derived a-tocopherol to circulation through function of a-tocopherol transfer protein (a-TTP) and a-TTP was a major determinant of plasma a-tocopherol level by this mechanism. We have found that hepatic a-TTP level was reduced in streptozotocin-induced diabetic rats and reduction of a-TTP concentration was also observed in hepatocytes cultured with low concentration of insulin (<10^<-10>M). Therefore, the aim of this study was to investigate the molecular mechanism of the reduction of hepatic a-TTP concentration under insulin depleted condition. Primary cultured rat hepatocyte was incubated with/without cyclohexymide (inhibitor of protein synthesis) and with various concentration of insulin for various periods and a-TTP level was measured by Western blot analysis. The results showed that a-TTP level decreased with low concentrations of insulin (10^<-10>M, 0M) while a-TTP level was not changed with high concentrations of insulin (10^<-8>M, 10^<-6>M) for 12 and 24 hours incubation. Furthermore, the decrease of a-TTP disappeared by preventing protein synthesis. Therefore, the decrease of a-TTP might be due to degradation by protease activity induced by low insulin concentration. Next, we investigated whether concentration of a-TTP were influenced by lysosome or proteasome inhibitor. The results showed that a-TTP concentration was greatly reduced by addition of lysosome inhibitors but not influened by a proteasome inhibitor. In conclusion, hepatic a-TTP may be degraded under low concentration of insulin, and a-TTP protease may be rapidly procecced by lysosome.

蜜蜂报道说，糖尿病患者和动物的血液中的A-生育酚（维生素E）浓度可以通过降低抗氧化活性来诱导另一种氧化应激。已经确定肝脏具有通过A-Topherol转移蛋白（A-TTP）和A-TTP的功能分泌食品来源的A-TTP的主要作用，是血浆A-TTP的主要决定因素。。我们发现，在链蛋白酶诱导的糖尿病大鼠中肝A-TTP水平降低，并且在低浓度的胰岛素（<10^<-10> m）培养的肝细胞中也观察到A-TTP浓度的降低。因此，这项研究的目的是研究在胰岛素耗尽条件下肝A-TTP浓度还原的分子机制。将原代培养的大鼠肝细胞与/无环己酰胺（蛋白质合成抑制剂）一起孵育，并在各个时期内用各种浓度的胰岛素和A-TTP水平通过Western Blot分析来测量A-TTP水平。结果表明，使用低浓度的胰岛素（10^<-10> m，0m）降低了A-TTP水平，而A-TTP水平没有使用高浓度的胰岛素（10^<-8> m，10^<）降低。 -6> m）孵育12和24小时。此外，通过预防蛋白质合成，A-TTP的减少消失了。因此，A-TTP的降低可能是由于低胰岛素浓度引起的蛋白酶活性降解所致。接下来，我们研究了A-TTP的浓度是否受溶酶体或蛋白酶体抑制剂的影响。结果表明，通过添加溶酶体抑制剂可大大降低A-TTP浓度，但不会受到蛋白酶体抑制剂的影响。总之，在低浓度的胰岛素下可能会降解肝A-TTP，并且A-TTP蛋白酶可能会通过溶酶体迅速进行。