Apoptosis Induced by Traumatic Brain Injury

描述(摘自申请者摘要)：创伤性脑损伤(TBI) 或体外创伤性神经元损伤(TNT)导致神经元凋亡，部分， 通过激活类caspase-3蛋白。半胱氨酸氨基转移酶-3的抑制作用 体外培养可减少创伤后细胞死亡，并提供额外的神经保护 由抑制坏死性细胞死亡的药物产生。Caspase-3 激活受上游caspase的调节，包括caspase-9(固有的 Caspase-8(外源途径)。我们的初步数据表明 Caspase-9通路在神经创伤中似乎更重要。 AKT(蛋白激酶B)是一种公认的抗凋亡因子，它可能 部分地，通过调节caspase的激活来起作用。AKT本身也可以是 受多种因素的调节，包括新的肿瘤抑制蛋白 PTEN。我们实验室最近的实验表明，PTEN在 神经细胞凋亡。 我们建议研究Akt在TB后神经元凋亡中的作用！和TNT， 并阐明了关键的上游和下游信号转导途径 牵涉其中。具体假设包括：1)caspase-9，但不是caspase-8， 是caspase-3介导的一个重要的上游调控机制。 创伤后细胞凋亡；2)Akt在细胞凋亡中起重要的调节作用 跟随TBI或TN！3)Akt的抗细胞凋亡作用包括 促凋亡因子磷酸化抑制caspase-3活性的研究 坏的，以及通过其他非caspase机制；4)最近 肿瘤抑制因子PTEN在创伤或营养不良后被激活 戒断并部分通过下调调控促进神经细胞凋亡 AKT活性；5)PTEN拮抗剂的开发可能提供新的 中枢神经系统损伤的神经保护治疗策略。 我们提出了以下具体目标：1)审查亲属 内源性(caspase-9)和外源性(caspase-8)通路的作用 在调控caspase-3诱导的TB细胞凋亡中！和TNT，使用互补的 体内和体外模型系统；2)建立抗细胞凋亡的作用 TbI和TNT中的AKT，并检查拟议的机制，包括磷酸化 糟糕透顶。3)证实PTEN在TBI和TNI中的促凋亡作用，以及 表明这一行动实质上是由于其下调监管的能力 AKT，导致caspase-9和caspase-3的激活；以及4)表明 我们合作开发的PTEN拮抗剂具有神经保护作用 在体内和体外损伤后。

DESCRIPTION (Adapted from applicant's abstract): Traumatic brain injury (TBI) or traumatic neuronal injury (TNT) in vitro causes neuronal apoptosis, in part, through activation of caspase-3-like proteases. inhibition of caspase-3 in vitro reduces posttraumatic cell death and provides additive neuroprotection to that produced by agents that inhibit necrotic cell death. Caspase-3 activation is modulated by upstream caspases, including caspase-9 (intrinsic pathway) and caspase-8 (extrinsic pathway). Our preliminary data suggests that the caspase-9 pathway appears to be more important in neurotrauma. Akt (protein kinase B) is a well-established anti-apoptotic factor, which may act, in part, by modulating caspase activation. Akt itself can also be modulated by several factors, including the novel tumor suppression protein PTEN. Recent experiments in our laboratory have suggested a role for PTEN in neuronal apoptosis. We propose to examine the role of Akt in neuronal apoptosis after TB! and TNT, and elucidate the critical upstream and downstream signal transduction pathways involved. Specific hypotheses include: 1) caspase-9, but not caspase-8, represents an important upstream modulatory mechanism for caspase-3 mediated apoptosis after trauma; 2) Akt plays an important modulatory role in apoptosis following TBI or TN! in vitro; 3) Anti-apoptotic actions of Akt include inhibition of caspase-3 activation by phosphorylating the pro-apoptotic factor BAD, as well as through other non-caspase mechanisms; 4) The recently identified tumor suppressor factor PTEN is activated after trauma or trophic withdrawal and contributes to neuronal apoptosis, in part, by downregulating Akt activity; and 5) Development of PTEN antagonists may provide a novel neuroprotective treatment strategy for CNS injury. We propose the following specific aims: 1) To examine the relative contributions of the intrinsic (caspase-9) and extrinsic (caspase-8) pathways in modulating caspase-3-induced apoptosis in TB! and TNT, using complementary in vivo and in vitro model systems; 2) To establish an anti-apoptotic role for Akt in TBI and TNT and examine proposed mechanisms, including phosphorylation of BAD. 3) To demonstrate a pro-apoptotic role for PTEN in TBI and TNI, and show that this action results substantially from its ability to downregulate Akt, resulting in activation of caspase-9 and caspase-3; and 4) To show that PTEN antagonists, newly developed by us in collaboration, are neuroprotective following injury in vivo and in vitro.