Role of uncoupling protein 2 in the regulation of bioenergetics and metabolism in the liver.

解偶联蛋白 2 在肝脏生物能学和代谢调节中的作用。

基本信息

批准号：
12660265
负责人：
KIMURA Kazuhiro
金额：
$ 2.3万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12660265/
关键词：
uncoupling protein ketone body regenerating liver redox state perfused liver beta oxidation reporter gene 代謝的熱産生糖代謝アミノ酸代謝脂質代謝脱共役タンパク質(uncoupling protein : UCP)細胞呼吸

项目摘要

Fatty acid oxidation, ketone body production, redox state and ATP levels, and their relations with mitochondrial uncoupling protein (UCP) 2 were examined in the early stages of liver regeneration after partial hepatectomy, using a perfusion system of the rat liver. The rate of fatty acid oxidation was increased in the regenerating liver, accompanied with increased ratio of oxygen consumption to ketone body production, suggesting that acetyl-CoA produced by β-oxidation preferred to be oxidized rather than being converted to ketone bodies. Mitochondrial NADH/NAD^+ ratio (redox states) was sustained at low levels even when fatty acid was infused. Thus, supply of sufficient amounts of NAD^+ presumably explains the increased fatty acid oxidation. UCP2 was remarkably increased in the remnant liver, especially in hepatocytes, and also in the sham-operated control liver, suggesting that UCP2 is unlikely to control redox states and consequent increase of fatty acid oxidation. The redox states were also not related directly with ATP levels, an index of oxidative phosphorylation, and with conversion of acetoacetate to 3-hydroxybutyrate.Next, to determine the regulatory mechanisms of UCP2 expression in the hepatocytes, transcription activity of UCP2 gene was analyzed in two hepatoma cell lines, one of which lacks endogenous UCP2 expression. In both the cells, the minimal region exhibiting full promoter activity was located between the translation-initiation site of the mouse UCP2 gene and the100bp upstream region, and the sequence and the gene mutation analyzes suggest involvement of specificity protein 1 in the full activation. In addition, treatment of the cells lacking endogenous UCP2 with azacytidine, a DNA methylation inhibitor, caused the expression of UCP2 gene. These results suggest that epigenetic control of UCP2 gene, as well as cis-acting DNA elements, is important for its expression in hepatocytes.

脂肪酸氧化，酮体产生，氧化还原状态和ATP水平以及它们与线粒体解偶联蛋白（UCP）2的关系在部分肝后期肝脏再生的早期使用大鼠肝脏的灌注系统检查。再生肝脏中脂肪酸氧化的速率增加，氧气消耗与酮体产生的比率增加，这表明β-氧化产生的乙酰辅酶A优先氧化而不是转化为酮体。线粒体NADH/NAD^+比率（氧化还原状态）即使在脂肪酸被注入时也处于低水平。这可能是供应足够量的NAD^++可能解释了脂肪酸氧化的增加。在残留的肝脏中，尤其是在肝细胞中以及假手术对照肝脏中的UCP2明显增加，这表明UCP2不太可能控制氧化还原状态，并导致脂肪酸氧化的增加。氧化还原状态也与ATP水平，氧化磷酸化指数以及将乙酰乙酸酯转化为3-羟基丁酸的转化，以确定UCP2表达在肝细胞中的调节机制，在UCP2基因的转录活性中，UCP2基因的转录活性在两个hepats in sendigent中分析了两个hepats of hepats of hepats of sypats of hepats of hepats of serpogen sypers of hepats of。在两个细胞中，表现出全启动子活性的最小区域都位于小鼠UCP2基因的翻译定位位点和100bp上游区域之间，并且序列和基因突变分析表明特异性蛋白1在全部激活中的参与。此外，用Azacytidine（一种DNA甲基化抑制剂）处理缺乏内源性UCP2的细胞引起UCP2基因的表达。这些结果表明，UCP2基因的表观遗传控制以及顺式作用DNA元素对于其在肝细胞中的表达很重要。