Prolyl Hydroxylation and Neuronal Cell Death

描述（由申请人提供）：在神经系统发育过程中，细胞死亡是普遍存在的，这有助于确保神经元与其目标之间形成适当数量和类型的连接。在发育过程中，当神经元不能从神经生长因子（NGF）等营养因子中获得足够的存活信号时，细胞就会死亡。越来越多的证据表明，营养因子剥夺导致的死亡也会导致人类神经紊乱和退行性疾病。我们之前发现脯氨酸羟化酶EGLN3是NGF剥夺诱导的细胞死亡的中介。EGLN3是脯氨酸羟化酶小家族中的一员，其功能是转录因子缺氧诱导因子（HIF）的氧依赖调节因子。除了调节HIF，最近的报道表明egln具有与HIF无关的功能。我们已经获得了EGLN3和促凋亡Bcl-2家族蛋白BIM（EL）之间新的相互作用的初步证据。此外，我们发现EGLN3和BIM（EL）各自与von Hippel-Lindau蛋白（pVHL）相互作用，pVHL是E3泛素连接酶的一个亚基，靶向HIF降解。在这里，我们将验证EGLN3、pVHL和BIM（EL）协同调节营养因子剥夺诱导的细胞死亡的假设。在Aim 1中，我们将使用过表达和基因敲除和敲除方法的组合来确定NGF剥夺诱导的细胞死亡期间EGLN3和BIM（EL）之间的功能关系。目的2探讨EGLN3/BIM（EL）相互作用的生化意义。实验将描述EGLN3和BIM（EL）之间的相互作用如何影响BIM（EL）的促凋亡功能和/或EGLN3的脯氨酸羟化酶活性。在Aim 3中，我们将确定pVHL如何调节EGLN3和BIM（EL）的表达和功能。我们还将验证我们的假设，即pVHL在营养因子剥夺诱导的细胞死亡中起促凋亡作用。这些研究将进一步加深我们对发育过程中导致神经元死亡的机制的理解，以及神经系统疾病如中风、脊髓损伤和其他神经退行性疾病中营养因子剥夺导致神经元损失的机制。神经营养因子剥夺导致人类脑部疾病如中风、脊髓损伤、周围神经病变和神经退行性疾病中神经元的丧失和功能障碍。该项目将描述调节神经营养因子剥夺引起的细胞死亡的新机制。从该项目中获得的信息可能有助于确定旨在防止神经元丢失的治疗的新靶点。神经营养因子剥夺是人类大脑疾病中神经元丧失和功能障碍的原因之一

DESCRIPTION (provided by applicant): Cell death is widespread during the development of the nervous system, where it helps to ensure that the proper number and types of connections are formed between neurons and their targets. During development, cell death occurs when neurons fail to receive adequate survival signals from trophic factors such as nerve growth factor (NGF). Accumulating evidence suggests that trophic factor deprivation-induced death also contributes to human neuronal disorders and degenerative diseases. We previously identified the prolyl hydroxylase EGLN3 as a mediator of NGF deprivation-induced cell death. EGLN3 is one of a small family of prolyl hydroxylases that function key as oxygen-dependent regulators of the transcription factor hypoxia- inducible factor (HIF). Besides regulating HIF, recent reports suggest that EGLNs have HIF-independent functions. We have obtained preliminary evidence for a novel interaction between EGLN3 and the pro- apoptotic Bcl-2 family protein BIM(EL). Moreover, we have found that EGLN3 and BIM(EL) each interact with the von Hippel-Lindau protein (pVHL), a subunit of the E3 ubiquitin ligase that targets HIF for degradation. Here we will test the hypothesis that EGLN3, pVHL, and BIM(EL) function coordinately to regulate trophic factor deprivation-induced cell death. In Aim 1 we will determine the functional relationship between EGLN3 and BIM(EL) during NGF deprivation-induced cell death using a combination of over-expression and gene knock-out and knock-down approaches. Aim 2 addresses the biochemical significance of the EGLN3/BIM(EL) interaction. Experiments will characterize how the interaction between EGLN3 and BIM(EL) influences the pro- apoptotic function of BIM(EL) and/or the prolyl hydroxylase activity of EGLN3. In Aim 3, we will determine how pVHL regulates EGLN3 and BIM(EL) expression and function. We will also test our hypothesis that pVHL plays a pro-apoptotic role in trophic factor deprivation-induced cell death. These studies should further our understanding of the mechanisms that lead to neuronal death during development, and in nervous systems disorders such as stroke, spinal cord injury, and other neurodegenerative conditions in which trophic factor deprivation contributes to the loss of neurons.Neurotrophic factor deprivation contributes to the loss and dysfunction of neurons in human brain diseases and disorders such as stroke, spinal cord injury, peripheral neuropathy, and neurodegenerative disease. This project will characterize new mechanisms that regulate cell death caused by neurotrophic factor deprivation. Information gained from this project may help identify new targets for therapies aimed at preventing neuronal loss. Neurotrophic factor deprivation contributes to the loss and dysfunction of neurons in human brain diseases and disorders such as stroke, spinal cord injury, peripheral neuropathy, and neurodegenerative disease. This project will characterize new mechanisms that regulate cell death caused by neurotrophic factor deprivation. Information gained from this project may help identify new targets for therapies aimed at preventing neuronal loss.