The PIDDosome mediates delayed death of hippocampal CA1 neurons after transient global cerebral ischemia in rats
The PIDDosome mediates delayed death of hippocampal CA1 neurons after transient global cerebral ischemia in rats
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DOI：
10.1073/pnas.0806222105
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发表时间：
2008-10-21
影响因子：
11.1
通讯作者：
Chan, Pak H.
中科院分区：
文献类型：
--
作者：
Niizuma, Kuniyasu;Endo, Hidenori;Chan, Pak H.
短暂的全脑缺血，如心脏骤停或心肺转流手术引起的缺血，会导致再灌注后数天脆弱的海马CA 1锥体神经元细胞死亡。虽然已经提出了许多因素来解释这一现象，但对其背后的机制知之甚少。我们描述了一种称为PIDDosome的细胞死亡信号，PIDDosome是p53诱导蛋白与死亡结构域（PIDD）、受体相互作用蛋白相关ICH-1/CED-3同源蛋白与死亡结构域（RAIDD）和半胱氨酸蛋白酶原-2的蛋白复合物。我们采用双侧颈总动脉阻断和低血压诱导5分钟的短暂性全脑缺血（tGCI）。Western blot分析表明，表达的两次切割片段的PIDD（PIDD-CC）增加的海马CA 1区的胞浆部分和前半胱氨酸天冬氨酸蛋白酶-2激活后tGCI。半胱天冬酶-2在脑匀浆中切割Bid。免疫共沉淀和免疫荧光研究表明，PIDD-CC，RAIDD，和procaspase-2共定位和直接结合，这表明PIDD死亡结构域复合物的形成。此外，我们通过使用在tGCI前48小时开始的小干扰RNA（siRNA）处理来测试PIDD表达的抑制。给予针对PIDD的siRNA不仅降低了PIDD-CC的表达，而且还降低了procaspase-2和Bid的活化，导致tGCI后海马CA 1亚区的组织学神经元损伤和DNA片段化减少。这些结果表明，PIDD在tGCI后半胱氨酸天冬氨酸蛋白酶原-2活化和迟发性CA 1神经元死亡中起重要作用。我们提出PIDD是一个假设的分子靶点，用于治疗tGCI后的神经元死亡。
A brief period of global brain ischemia, such as that induced by cardiac arrest or cardiopulmonary bypass surgery, causes cell death in vulnerable hippocampal CA1 pyramidal neurons days after reperfusion. Although numerous factors have been suggested to account for this phenomenon, the mechanisms underlying it are poorly understood. We describe a cell death signal called the PIDDosome, a protein complex of p53-induced protein with a death domain (PIDD), receptor-interacting protein-associated ICH-1/CED-3 homologous protein with a death domain (RAIDD), and procaspase-2. We induced 5 min of transient global cerebral ischemia (tGCI) using bilateral common carotid artery occlusion with hypotension. Western blot analysis showed that expression of twice-cleaved fragment of PIDD (PIDD-CC) increased in the cytosolic fraction of the hippocampal CA1 subregion and preceded procaspase-2 activation after tGCI. Caspase-2 cleaved Bid in brain homogenates. Co-immunoprecipitation and immunofluorescent studies demonstrated that PIDD-CC, RAIDD, and procaspase-2 were co-localized and bound directly, which indicates the formation of the PIDD death domain complex. Furthermore, we tested inhibition of PIDD expression by using small interfering RNA (siRNA) treatment that was initiated 48 h before tGCI. Administration of siRNA against PIDD decreased not only expression of PIDD-CC, but also activation of procaspase-2 and Bid, resulting in a decrease in histological neuronal damage and DNA fragmentation in the hippocampal CA1 subregion after tGCI. These results imply that PIDD plays an important role in procaspase-2 activation and delayed CA1 neuronal death after tGCI. We propose that PIDD is a hypothetical molecular target for therapy against neuronal death after tGCI.