Identification of oxidative stress related genes and transcription factors in vascular tissues

为了评估线粒体转录因子A（mtTFA）功能异常作为糖尿病线粒体功能障碍的原因，我们测量了由线粒体呼吸链组成的蛋白质的mRNA含量以及从对照组和链脲佐菌素诱导的糖尿病大鼠心脏中分离的线粒体中的转录和翻译活性。北方杂交结果显示，糖尿病大鼠心肌细胞色素B和ATP合成酶亚基6的mRNA含量较对照组降低40%（P <0.05）。这些异常通过胰岛素治疗完全恢复。糖尿病大鼠线粒体转录和翻译活性较对照组分别降低60%（P <0.01）和71%（P <0.01）。胰岛素治疗也使糖尿病大鼠的这些异常完全正常化。凝胶阻滞实验显示，糖尿病大鼠线粒体DNA D环与mtTFA的结合减少，但两组mtTFA的mRNA和蛋白含量无明显差异。基于这些发现，糖尿病大鼠心脏中mtTFA与D-环区域的结合活性降低可能有助于线粒体蛋白质合成减少。

To evaluate abnormalities in the mitochondrial transcription factor A (mtTFA) function as a cause of mitochondrial dysfunction in diabetes, we measured the mRNA contents of the proteins consisting of the mitochondrial respiratory chain as well as transcriptional and translational activities in the mitochondria isolated from controls and streptozotocin-induced diabetic rat hearts. Using Northern blot analysis, we found the 40 % reduced mRNA contents of mitochondrial-encoded cytochrome b and ATP synthase subunit 6 in diabetic rat hearts compared with control rats (P < 0.05). These abnormalities were completely recovered by insulin treatment. Furthermore, the mitochondrial activities of transcription and translation were decreased significantly in mitochondria isolated from diabetic rats by 60 % (P < 0.01) and by 71 % (P < 0.01), respectively compared with control rats. The insulin treatment also completely normalized these abnormalities in diabetic rats. Consistently, gel retardation assay showed a reduced binding of mtTFA to the D-loop of mitochondrial DNA in diabetic rats, although there was no difference in the mtTFA mRNA and protein contents between the two groups. Based on these findings, a reduced binding activity of mtTFA to the D-loop region in the hearts of diabetic rats may contribute to the decreased mitochondrial protein synthesis.