Lu Aigang, Ran Ruiqiong, Parmentier-Batteur Sophie, Nee Alex, Sharp Frank R
Department of Neurology, University of Cincinnati, Ohio 45267-0536, USA.
J Neurochem. 2002 Apr;81(2):355-64. doi: 10.1046/j.1471-4159.2002.00835.x.
Geldanamycin (GA), a benzoquinone ansamycin, binds Hsp90 in vitro, releases heat shock factor (HSF1) and induces heat shock proteins (Hsps). Because viral and transgenic overexpression of Hsps protects cells against ischemia in vitro, we hypothesized that GA would protect brain from focal ischemia by inducing Hsps in vivo. Adult male Sprague-Dawley rats were subjected to 2-hour middle cerebral artery occlusions (MCAO) using the suture technique followed by 22-h reperfusions. GA or vehicle was injected into the lateral cerebral ventricles (i.c.v) 24 h before ischemia. Geldanamycin at 1 microg/kg decreased infarct volumes by 55.7% (p < 0.01) and TUNEL-positive cells by 30% in cerebral cortex. GA also improved behavioral outcomes (p < 0.01) and reduced brain edema (p < 0.05). Western blots showed that the 1 microg/kg GA dose induced Hsp70 and Hsp25 protein 8.2-fold and 2.7-fold, respectively, by 48 h following administration. Immunocytochemistry showed that GA induced Hsp70 in neurons and Hsp25 in glia and arteries in cortex, hippocampus, hypothalamus, and other brain regions. GA reduced co-immunoprecipitation of HSF1 with Hsp90 in brain tissue homogenates, promoted HSE-binding of HSF in brain nuclear extracts using gel shift assays, and increased luciferase reporter gene transcription for the Hsp70 promoter in PC12 cells. The data show that geldanamycin protects brain from focal ischemia and that this may be due, at least in part, to geldanamycin stimulation of heat shock gene transcription.
格尔德霉素（GA）是一种苯醌安莎霉素，在体外可与热休克蛋白90（Hsp90）结合，释放热休克因子（HSF1）并诱导热休克蛋白（Hsps）产生。由于热休克蛋白的病毒介导及转基因过表达在体外可保护细胞免受缺血损伤，我们推测GA在体内通过诱导热休克蛋白产生来保护脑免受局灶性缺血损伤。成年雄性Sprague-Dawley大鼠采用缝线技术进行2小时大脑中动脉闭塞（MCAO），随后再灌注22小时。在缺血前24小时，将GA或溶剂注入侧脑室（脑室内注射）。1微克/千克的格尔德霉素使脑梗死体积减少55.7%（p<0.01），大脑皮质中TUNEL阳性细胞减少30%。GA还改善了行为学结果（p<0.01）并减轻了脑水肿（p<0.05）。蛋白质免疫印迹显示，给药后48小时，1微克/千克的GA剂量分别使热休克蛋白70（Hsp70）和热休克蛋白25（Hsp25）的蛋白表达增加8.2倍和2.7倍。免疫细胞化学显示，GA在皮质、海马、下丘脑及其他脑区的神经元中诱导Hsp70产生，在胶质细胞和动脉中诱导Hsp25产生。GA减少了脑组织匀浆中HSF1与Hsp90的共免疫沉淀，通过凝胶迁移试验促进了脑细胞核提取物中HSF与热休克元件（HSE）的结合，并增加了PC12细胞中Hsp70启动子的荧光素酶报告基因转录。数据表明，格尔德霉素可保护脑免受局灶性缺血损伤，这可能至少部分归因于格尔德霉素对热休克基因转录的刺激作用。
