Bhat R V, DiRocco R, Marcy V R, Flood D G, Zhu Y, Dobrzanski P, Siman R, Scott R, Contreras P C, Miller M
Cephalon Incorporated, West Chester, Pennsylvania 19380, USA.
J Neurosci. 1996 Jul 1;16(13):4146-54. doi: 10.1523/JNEUROSCI.16-13-04146.1996.
Although the interleukin-1beta converting enzyme (ICE)/CED-3 family of proteases has been implicated recently in neuronal cell death in vitro and in ovo, the role of specific genes belonging to this family in cell death in the nervous system remains unknown. To address this question, we examined the in vivo expression of one of these genes, Ice, after global forebrain ischemia in gerbils. Using RT-PCR and Western immunoblot techniques, we detected an increase in the mRNA and protein expression of ICE in hippocampus during a period of 4 d after ischemia. Chromatin condensation was observed in CA1 neurons within 2 d after ischemia. Internucleosomal DNA fragmentation and apoptotic bodies were observed between 3 and 4 d after ischemia, a period during which CA1 neuronal death is maximal. In nonischemic brains, ICE-like immunoreactivity was relatively low in CA1 pyramidal neurons but high in scattered hippocampal interneurons. After ischemia, ICE-like immunoreactivity was not altered in these neurons. ICE-like immunoreactivity, however, was observed in microglial cells in the regions adjacent to the CA1 layer as early as 2 d after ischemic insult. The increase in ICE-like immunoreactivity was robust at 4 d after ischemia, a period that correlates with the DNA fragmentation observed in hippocampal homogenates of ischemic brains. These results provide the first evidence for the localization and induction of ICE expression in vivo after ischemia and suggest an indirect role for ICE in ischemic damage through mediation of an inflammatory response.
尽管白细胞介素-1β转化酶（ICE）/CED-3蛋白酶家族最近被认为与体外和卵内的神经元细胞死亡有关，但该家族中特定基因在神经系统细胞死亡中的作用仍不清楚。为了解决这个问题，我们检测了沙土鼠全脑缺血后该家族中一个基因Ice在体内的表达情况。运用逆转录-聚合酶链反应（RT-PCR）和蛋白质免疫印迹技术，我们发现在缺血后4天内，海马中ICE的mRNA和蛋白质表达均有所增加。缺血后2天内在CA1神经元中观察到染色质凝聚。在缺血后3至4天观察到核小体间DNA断裂和凋亡小体，这一时期CA1神经元死亡最为严重。在未缺血的大脑中，CA1锥体神经元中的ICE样免疫反应性相对较低，但在散在的海马中间神经元中较高。缺血后，这些神经元中的ICE样免疫反应性没有改变。然而，早在缺血损伤后2天，就在与CA1层相邻区域的小胶质细胞中观察到ICE样免疫反应性。缺血后4天，ICE样免疫反应性显著增加，这一时期与缺血性脑的海马匀浆中观察到的DNA断裂相关。这些结果首次证明了缺血后体内ICE表达的定位和诱导，并提示ICE通过介导炎症反应在缺血损伤中起间接作用。
