Mechanisms and Modulation of Cell Death in Traumatic Brain Injury

创伤性脑损伤中细胞死亡的机制和调节

基本信息

批准号：
8240512
负责人：
ALAN Ira FADEN
金额：
$ 45.25万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-05-18 至 2014-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8240512
关键词：
Acute Adenosine Apoptosis Apoptotic Behavioral Bioenergetics Biological Models Brain Ischemia Carrier Proteins Caspase Cause of Death Cell Culture Techniques Cell Death Cell Nucleus Cells Cessation of life Cyclophilin A DNA Damage Death Domain Health In Vitro Injury Knock-out Lesion Location Mediating Mitochondria Modeling Mus Neurologic Dysfunctions Neuronal Injury Neurons Nicotinamide adenine dinucleotide Outcome Pathway interactions Phenotype Play Poly(ADP-ribose) Polymerases Recovery Relative (related person)Role Severities Site Transgenic Model Trauma Traumatic Brain Injury United States Work apoptosis inducing factor caspase-2 caspase-3 cell injury clinically relevant controlled cortical impact disability functional outcomes improved in vitro Model in vivo inhibitor/antagonist knockout animal neuron apoptosis neuron loss tripolyphosphate

项目摘要

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI), or traumatic neuronal injury in vitro, causes neuronal apoptosis, in part through activation of caspases. Inhibition of caspase-3, in both in vivo or in vitro trauma models, reduces post-traumatic apoptosis, and improves functional outcomes in clinically relevant TBI models. However, some of these studies indicate that improvements often reflect only a delay in cell death, which still occurs eventually without the classical apoptotic phenotype. This suggests that caspase-independent pathways might play an important role in determining the final fate of cells. Recent work supports this hypothesis, demonstrating that caspase- independent apoptosis also contributes to neuronal cell death in a variety of in vitro model systems, and that translocation of apoptosis-inducing factor (AIF) from the mitochondria to the nucleus, in association with apoptotic morphological features, occurs after acute brain ischemia or TBI. Moreover, AIF translocation can occur under low energetic conditions, in association with activation of poly-ADP-ribose polymerase I (PARP-1) and reduction of nicotinamide adenine dinucleotide (NAD+). In contrast, caspase activation is generally associated with a more preserved bioenergetic state and requires adenosine 5'-triphosphate (ATP). Thus caspase-independent apoptosis may play a greater role than caspase-mediated cell death after a more severe injury, or within more central regions of the evolving lesion - sites at which cellular bioenergetic state is substantially compromised. AIF-mediated apoptosis may be initiated either by the same mechanisms responsible for intrinsic caspase activation or through PARP-1 activation. In the former, the role played by AIF becomes visible only when caspase activation has been blocked. In the latter, AIF is the main death-inducing factor. PARP-1 inhibition or PARP knockout animals, as well as knockout of the AIF carrier protein cyclophilin A, show reduced AIF translocation. We propose to utilize a well-established, controlled cortical impact (CCI) model of TBI in mouse, as well as selected in vitro models, to compare mechanisms underlying both caspase- dependent and caspase-independent programmed cell death of neurons and their relative roles as a function of injury severity and injury localization. Specific hypotheses include: 1) both caspase-independent and caspase-dependent pathways contribute to post-traumatic cell loss and associated neurological dysfunction after TBI, as well as to apoptotic neuronal cell death in cell culture models associated with DNA damage; 2) caspase-independent apoptosis is induced to a relatively greater degree than caspase-dependent cell death after more severe insults, or at more central regions of the expanding lesion, where bioenergetic state is reduced; 3) cell specific, inducible 'functional" knockouts of AIF pro-death domains, as well as models in which AIF translocation is inhibited (PARP knockout, treatment with PARP inhibitors, or cyclophilin A knockout), show reduced apoptotic cell death after TBI or after cell injury in vitro, and; 4) inhibition of both caspase- dependent and caspase-independent cell death improves recovery after CCI in additive or synergistic fashion. We propose the following specific aims: 1) to compare the relative degree and location of caspase-dependent and caspase-independent neuronal cell death after mild, moderate or moderately-severe TBI; 2) to investigate the role of AIF in TBI-induced neuronal death and behavioral recovery by comparing two inducible, neuron-specific, pro-death domain selective AIF transgenic models versus their "non-induced" controls; 3) to evaluate the effects of cyclophilin A knockout on AIF translocation, apoptosis and behavioral outcome after TBI and in selected cell culture models and; 4) to evaluate the effects of two structurally-distinct PARP inhibitors or PARP-1 knockout on AIF translocation, apoptosis and behavioral outcome after TBI and in selected cell culture models, and determine whether such effects are additive or synergistic to that of caspase inhibition. PUBLIC HEALTH RELEVANCE: Traumatic brain injury (TBI) represents a major cause of death and disability in the United States. A better understanding of the mechanisms underlying TBI would offer the possibility of improving survival and insuring a more complete recovery.

描述（由申请人提供）：脑外伤（TBI）或体外神经元损伤会导致神经元细胞凋亡，部分通过激活caspase。在体内或体外创伤模型中抑制caspase-3的抑制作用可减少创伤后凋亡，并改善临床相关的TBI模型的功能结果。然而，其中一些研究表明，改进通常仅反映了细胞死亡的延迟，最终仍出现经典凋亡表型。这表明与caspase无关的途径可能在确定细胞的最终命运中起重要作用。最近的工作支持了这一假设，表明caspase-独立的凋亡也有助于多种体外模型系统中的神经元细胞死亡，并且在急性脑部脑部iSchemia或Tbi之后，凋亡诱导因子（AIF）从线粒体到核的易位诱导因子（AIF）。此外，与多聚ADP-核糖聚合酶I（PARP-1）的激活以及烟酰胺腺嘌呤二核苷酸（NAD+）的激活相关，AIF易位可能发生在低能条件下。相反，胱天冬酶激活通常与更加保存的生物能状态有关，需要5'-三磷酸腺苷（ATP）。因此，与caspase非依赖性凋亡相比，与caspase介导的细胞死亡更为严重，或在不断发展的病变的中央区域内 - 细胞生物能状态受到严重损害的部位。 AIF介导的凋亡可以通过负责内在caspase激活的相同机制或通过PARP-1激活来启动。在前者中，只有在胱天蛋白酶激活被阻止时，AIF的作用才能看到。在后者中，AIF是主要诱发死亡的因素。 PARP-1抑制作用或PARP基因敲除动物以及AIF载体蛋白环磷脂A的基因敲除显示的AIF易位降低。我们建议利用小鼠中TBI的公认，受控的皮质影响（CCI）模型，以及选择的体外模型，比较caspase依赖性和无caspase无关神经元的神经元及其相对作用的caspase依赖性和无caspase的细胞死亡的机制，它们的相对作用是严重和受伤本地化的功能。具体假设包括：1）caspase独立和caspase依赖性途径均导致创伤后细胞损失和TBI后的相关神经功能障碍，以及与DNA损伤相关的细胞培养模型中的凋亡神经元细胞死亡； 2）与caspase依赖性细胞死亡相比，caspase非依赖性凋亡的程度相对较大，在更严重的损伤后或在降低生物能状态的膨胀病变的更中心区域。 3) cell specific, inducible 'functional" knockouts of AIF pro-death domains, as well as models in which AIF translocation is inhibited (PARP knockout, treatment with PARP inhibitors, or cyclophilin A knockout), show reduced apoptotic cell death after TBI or after cell injury in vitro, and; 4) inhibition of both caspase- dependent and caspase-independent cell death improves recovery after CCI in添加剂或协同方式。与他们的“非诱导”对照相比，评估了环粒蛋白的敲除对AIF易位，凋亡和行为结果的影响，并在选定的细胞培养模型中； 4）评估两种结构存在的PARP抑制剂或PARP-1基因敲除对TBI和选定细胞培养模型后AIF易位，凋亡和行为结果的影响，并确定此类效应是否对CASPase抑制作用是添加剂或协同作用。公共卫生相关性：创伤性脑损伤（TBI）代表了美国死亡和残疾的主要原因。更好地了解TBI的机制将提供改善生存和确保更完整恢复的可能性。