Alteration of Apoptotic Protease-Activating Factor-1 (APAF-1)-Dependent Apoptotic Pathway During Development of Rat Brain and Liver
作者:K. Ota、A. G. Yakovlev、A. Itaya、M. Kameoka、Y. Tanaka、K. Yoshihara
DOI:10.1093/oxfordjournals.jbchem.a003067
日期:2002.1.1
Brain and liver extracts of rats at different stages after birth were examined for cyto-chrome c/dATP-dependent caspase (DEVDase)-activation (mitochondria pathway)in vitro. The caspase-activating activity in the brain extracts rapidly decreased after birth, reaching approximately 50 and 5%, at 1 and 2 weeks, respectively, of that in a 3-days-newborn sample, and essentially no caspase-activation was detected in the adult rat brain extracts. Such a dramatic change was not detected in the liver samples, suggesting that the observed abrogation of the cytochrome c-dependent mitochondria pathway after birth is a brain-specific event. In order to determine the factor(s) lacking in adult brain, we separately measured Apaf-1, procaspase 9, and pro-DEVDase activities using a supplementation assay. In adult brain, Apaf-1 activity was scarcely detected, while the tissue retained low but significant amounts of procaspase 9 (16% of that in the fetal tissue) and a pro-DEVDase (3.4%). In contrast, adult liver extracts retained relatively high levels of all of these factors. Immunoblot analyses clearly indicated that the expression of Apaf-1 and procaspase 3 is markedly suppressed within 4 weeks after birth in brain tissue while they are even expressed in adult liver. Considering these results together, we propose that, in the brain, the cytochrome c-dependent mitochondria pathway, which is essential for the programmed cell death during normal morphogenesis, is abrogated within 2—4 weeks after birth, whereas the pathway is still active in other adult tissues such as liver.
对大鼠出生后不同阶段的脑和肝提取物进行了体外细胞色素 c/dATP 依赖性 caspase(DEVDase)激活(线粒体途径)检测。大鼠出生后,脑提取物中的caspase活化活性迅速下降,1周和2周时分别约为出生3天样本的50%和5%,成年大鼠脑提取物中基本上检测不到caspase活化。在肝脏样本中没有检测到这种巨大变化,这表明观察到的出生后细胞色素 c 依赖线粒体途径的衰减是大脑特异性事件。为了确定成体大脑中缺乏的因子,我们使用补充试验分别测定了 Apaf-1、procaspase 9 和 pro-DEVDase 的活性。在成体大脑中,几乎检测不到 Apaf-1 活性,而组织中保留了少量但却很重要的 procaspase 9(为胎儿组织的 16%)和 pro-DEVDase(3.4%)。相比之下,成人肝脏提取物中所有这些因子的含量都相对较高。免疫印迹分析清楚地表明,Apaf-1和procaspase 3的表达在出生后4周内在脑组织中明显受到抑制,而在成人肝脏中甚至还有表达。综合考虑这些结果,我们认为,在大脑中,细胞色素 c 依赖性线粒体途径是正常形态发生过程中细胞程序性死亡所必需的,但在出生后 2-4 周内,该途径被废除,而在肝脏等其他成体组织中,该途径仍然活跃。