Lee Byung I, Lee Doo J, Cho Kyoung J, Kim Gyung W
Department of Neurology and Brain Korea 21 Project for Medical Science, College of Medicine, Yonsei University, 134, Sinchon-dong, Seodaemun-gu, Seoul 120-752, Korea.
Neurosci Lett. 2005 Sep 23;386(1):23-7. doi: 10.1016/j.neulet.2005.05.058.
We investigated whether the endonuclease G (endoG) translocated from mitochondria to nucleus after transient focal cerebral ischemia (tFCI), thereby contributed to subsequent DNA fragmentation. Adult male mice were subjected to 60min of focal cerebral ischemia by intraluminal suture blockade of the middle cerebral artery. Western blot analysis for endoG was performed at various time points of tFCI. Nuclear endoG was detected as early as 4h after tFCI in the ischemic brain, and correspondingly mitochondrial endoG showed a significant reduction at 4h after reperfusion (p<0.01). Immunohistochemistry of endoG confirmed that the nuclear translocation of endoG was detected as early as 4h after tFCI in the middle cerebral artery (MCA) territory of the ischemic brain. Double immunofluorescent staining with endoG and AIF showed that endoG was predominantly colocalized with AIF at 24h after tFCI. Double staining with endoG immunohistochemistry and TdT-mediated dUTP-biotin nick end labeling showed a spatial relationship between endoG expression and DNA fragmentation at 24h after tFCI. These data suggest that the early nuclear translocation of endoG occurs and could induce DNA fragmentation in the ischemic brain after tFCI.
我们研究了短暂性局灶性脑缺血（tFCI）后核酸内切酶G（endoG）是否从线粒体转位至细胞核，进而导致随后的DNA片段化。成年雄性小鼠通过大脑中动脉腔内缝线阻塞法进行60分钟的局灶性脑缺血。在tFCI的不同时间点进行endoG的蛋白质印迹分析。在缺血性脑中，早在tFCI后4小时就检测到核内endoG，相应地，再灌注后4小时线粒体endoG显著减少（p<0.01）。endoG的免疫组织化学证实，早在tFCI后4小时在缺血性脑的大脑中动脉（MCA）区域就检测到endoG的核转位。endoG和凋亡诱导因子（AIF）的双重免疫荧光染色显示，tFCI后24小时endoG主要与AIF共定位。endoG免疫组织化学与TdT介导的dUTP生物素缺口末端标记双重染色显示，tFCI后24小时endoG表达与DNA片段化之间存在空间关系。这些数据表明，tFCI后缺血性脑中发生了endoG的早期核转位，并可能诱导DNA片段化。
