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

• 批准号: 8090307
• 负责人: ALAN Ira FADEN
• 金额: $ 45.82万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-18 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8090307
• 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

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）：创伤性脑损伤（TBI）或体外创伤性神经元损伤部分通过半胱天冬酶的激活导致神经元凋亡。在体内或体外创伤模型中，抑制 caspase-3 可以减少创伤后细胞凋亡，并改善临床相关 TBI 模型的功能结果。然而，其中一些研究表明，改善通常仅反映细胞死亡的延迟，即使没有经典的凋亡表型，细胞死亡最终仍然会发生。这表明不依赖半胱天冬酶的途径可能在决定细胞的最终命运中发挥重要作用。最近的工作支持这一假设，证明在各种体外模型系统中，不依赖半胱天冬酶的细胞凋亡也导致神经元细胞死亡，并且凋亡诱导因子（AIF）从线粒体易位到细胞核，与细胞凋亡形态学相关。特征，发生在急性脑缺血或 TBI 后。此外，AIF 易位可以在低能量条件下发生，与聚 ADP 核糖聚合酶 I (PARP-1) 的激活和烟酰胺腺嘌呤二核苷酸 (NAD+) 的还原有关。相反，半胱天冬酶激活通常与更保存的生物能状态相关，并且需要 5'-三磷酸腺苷 (ATP)。因此，在更严重的损伤后，或者在病变发展的更中心区域——细胞生物能状态受到严重损害的部位，与半胱天冬酶介导的细胞死亡相比，不依赖半胱天冬酶的细胞凋亡可能发挥更大的作用。 AIF 介导的细胞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，只有当 caspase 激活被阻断时，AIF 所发挥的作用才变得可见。在后者中，AIF是主要的死亡诱导因素。 PARP-1 抑制或 PARP 敲除动物，以及 AIF 载体蛋白亲环蛋白 A 敲除，显示 AIF 易位减少。我们建议利用小鼠 TBI 的完善的受控皮质影响 (CCI) 模型以及选定的体外模型来比较 caspase 依赖性和 caspase 非依赖性神经元程序性细胞死亡的机制及其相对作用作为损伤严重程度和损伤定位的函数。具体假设包括： 1) 不依赖 caspase 的途径和依赖 caspase 的途径都会导致创伤后细胞丢失和 TBI 后相关的神经功能障碍，以及与 DNA 损伤相关的细胞培养模型中的凋亡性神经元细胞死亡； 2)在更严重的损伤后，或者在生物能状态降低的扩大病变的更中心区域，与半胱天冬酶依赖性细胞死亡相比，不依赖性半胱天冬酶依赖性细胞凋亡被诱导到相对更大的程度； 3) AIF促死亡结构域的细胞特异性、可诱导的“功能性”敲除，以及AIF易位被抑制的模型（PARP敲除、用PARP抑制剂治疗或亲环蛋白A敲除），显示TBI后凋亡细胞死亡减少或体外细胞损伤后，以及；4)抑制半胱天冬酶依赖性和非半胱天冬酶依赖性细胞死亡以相加或协同方式改善CCI后的恢复。以下具体目标：1) 比较轻度、中度或中重度 TBI 后 caspase 依赖性和 caspase 非依赖性神经元细胞死亡的相对程度和位置；2) 研究 AIF 在 TBI 诱导的神经元死亡和行为中的作用通过比较两种可诱导的、神经元特异性的、促死亡结构域选择性的 AIF 转基因模型与其“非诱导”对照来恢复；3) 评估亲环蛋白 A 敲除对 AIF 的影响； TBI 后和选定的细胞培养模型中的易位、细胞凋亡和行为结果； 4) 评估两种结构不同的 PARP 抑制剂或 PARP-1 敲除对 TBI 后和选定的细胞培养模型中 AIF 易位、细胞凋亡和行为结果的影响，并确定这种影响是否与 caspase 抑制相加或协同。公共卫生相关性：创伤性脑损伤 (TBI) 是美国死亡和残疾的主要原因。更好地了解 TBI 的潜在机制将有可能提高生存率并确保更完全的康复。