Matsumori Yasuhiko, Hong Shwuhuey M, Aoyama Koji, Fan Yang, Kayama Takamasa, Sheldon R Ann, Vexler Zinaida S, Ferriero Donna M, Weinstein Philip R, Liu Jialing
Department of Neurological Surgery, University of California at San Francisco 94121, USA.
J Cereb Blood Flow Metab. 2005 Jul;25(7):899-910. doi: 10.1038/sj.jcbfm.9600080.
Apoptosis is implicated in neonatal hypoxic/ischemic (H/I) brain injury among various forms of cell death. Here we investigate whether overexpression of heat shock protein (Hsp) 70, an antiapoptotic protein, protects the neonatal brain from H/I injury and the pathways involved in the protection. Postnatal day 7 (P7) transgenic mice overexpressing rat Hsp70 (Tg) and their wild-type littermates (Wt) underwent unilateral common carotid artery ligation followed by 30 mins exposure to 8% O(2). Significant neuroprotection was observed in Tg versus Wt mice on both P12 and P21, correlating with a high level of constitutive but not inducible Hsp70 in the Tg. More prominent injury was observed in Wt and Tg mice on P21, suggesting its continuous evolution after P12. Western blot analysis showed that translocation of cytochrome c, but not the second mitochondria-derived activator of caspase (Smac)/DIABLO and apoptosis-inducing factor (AIF), from mitochondria into cytosol was significantly reduced in Tg 24 h after H/I compared with Wt mice. Coimmunoprecipitation detected more Hsp70 bound to AIF in Tg than Wt mice 24 h after H/I, inversely correlating with the amount of nuclear, but not cytosolic, AIF translocation. Our results suggest that interaction between Hsp70 and AIF might have reduced downstream events leading to cell death, including the reduction of nuclear AIF translocation in the neonatal brains of Hsp70 Tg mice after H/I.
在各种形式的细胞死亡中，凋亡与新生儿缺氧缺血性（H/I）脑损伤有关。在此，我们研究抗凋亡蛋白热休克蛋白（Hsp）70的过表达是否能保护新生脑免受H/I损伤以及其中涉及的保护途径。出生后第7天（P7）的过表达大鼠Hsp70的转基因小鼠（Tg）及其野生型同窝小鼠（Wt）接受单侧颈总动脉结扎，随后暴露于8%氧气中30分钟。在P12和P21时，Tg小鼠相对于Wt小鼠观察到显著的神经保护作用，这与Tg中高水平的组成型而非诱导型Hsp70相关。在P21时，Wt和Tg小鼠中观察到更明显的损伤，表明其在P12后持续演变。蛋白质印迹分析表明，与Wt小鼠相比，H/I后24小时Tg中线粒体细胞色素c向胞质溶胶的转位显著减少，但第二线粒体衍生的半胱天冬酶激活剂（Smac）/DIABLO和凋亡诱导因子（AIF）未减少。免疫共沉淀检测到H/I后24小时Tg中与AIF结合的Hsp70比Wt小鼠更多，这与核内而非胞质内AIF转位的量呈负相关。我们的结果表明，Hsp70与AIF之间的相互作用可能减少了导致细胞死亡的下游事件，包括H/I后Hsp70 Tg小鼠新生脑中核AIF转位的减少。
