Molecular Characterization of Neural Stem Cell Apoptosis

描述(申请人提供)：神经干细胞在正常神经系统发育中起关键作用，失调的神经干细胞死亡会导致脑和脊髓畸形、脑瘤形成，并可能导致神经退行性疾病和神经精神疾病。细胞死亡途径具有明显的细胞特异性和刺激性，依赖于一系列分子之间的相互作用，包括P53、Bcl2家族成员、caspase和各种自噬相关蛋白。在这笔拨款支持的一系列研究中，我们定义了几个刺激特异性神经干细胞死亡途径，涉及P53和/或Puma，Bcl2家族中的一个促凋亡成员。在这个修订的竞争性更新应用中，我们提出了一系列新的研究，重点是P53和Puma对生理性和病理性神经干细胞死亡的调控。除了众所周知的细胞凋亡性死亡(I型程序性细胞死亡)外，自噬细胞死亡(II型程序性细胞死亡)越来越多地被认为是在神经病理条件下发生的。由我们的资助支持的研究表明，P53和Bcl2家族成员在调节神经干细胞中的凋亡和自噬细胞死亡方面发挥了作用。我们最近的数据表明，神经干细胞的死亡在体内由多种病理刺激触发，包括遗传毒性应激、缺氧缺血损伤和糖皮质激素暴露。这些刺激与几种人类新生儿和儿科神经疾病的发病机制有关。在这一应用中，我们着重于调控凋亡和自噬神经干细胞死亡的分子机制，特别强调在人类神经病理学的两个重要的新生小鼠模型中，这些重叠的死亡途径在体内的相关性。为了实现我们的目标，我们将追求三个具体目标。在第一个目标中，我们将测试这一假设，即P53是自噬应激诱导的神经干细胞死亡的有效调节因子，它通过参与彪马依赖和非独立死亡途径的能力。目的研究新生小鼠脑内缺氧缺血诱导的神经干细胞死亡的分子机制，并验证P53至少部分通过转录非依赖作用调控神经干细胞死亡的假说。目的三将扩展我们的初步研究，表明彪马以一种不依赖于p53的方式调节糖皮质激素诱导的新生小鼠脑内神经干细胞的死亡，并且可能是与人类早产相关的神经缺陷的贡献者。总之，这些新的P53和/或PUMA依赖的神经干细胞死亡途径的研究代表了我们对凋亡和自噬细胞死亡途径的高效研究的重要扩展，并将对在生理和病理条件下调节神经干细胞死亡的分子机制产生新的见解。 公共卫生相关性：神经干细胞控制神经系统的发育，神经干细胞死亡过多或过少都与发育性脑畸形、脑瘤形成和神经精神疾病有关。确定调节神经干细胞死亡的分子途径对于了解神经系统如何正常发育和确定用于治疗各种人类神经病理疾病状态的分子靶点非常重要，这些疾病包括脑瘫、神经发育障碍、癫痫、自闭症、脑肿瘤和神经退行性疾病。

DESCRIPTION (provided by applicant): Neural stem cells play a critical role in normal nervous system development and dysregulated neural stem cell death contributes to brain and spinal cord malformations, brain tumor formation, and possibly, neurodegenerative and neuropsychiatric diseases. Cell death pathways are remarkably cell- and stimulus- specific and are dependent on interactions between an array of molecules including p53, Bcl-2 family members, caspases, and a variety of autophagy-associated proteins. In a series of studies supported by this grant, we have defined several stimulus-specific neural stem cell death pathways involving p53 and/or Puma, a pro-apoptotic member of the Bcl-2 family. In this revised competitive renewal application, we propose a series of novel studies focused on p53 and Puma regulation of physiological and pathological neural stem cell death. In addition to the well known role of apoptotic cell death (Type I Programmed Cell Death), autophagic cell death (Type II Programmed Cell Death) has been increasingly recognized to occur under neuropathological conditions. Studies supported by our grant have demonstrated a role for p53 and Bcl-2 family members in regulating both apoptotic and autophagic cell death in neural stem cells. Our recent data indicate that neural stem cell death is triggered in vivo by a variety of pathological stimuli including genotoxic stress, hypoxic- ischemic injury, and glucocorticoid exposure. These stimuli have been implicated in the pathogenesis of several human neonatal and pediatric neurological disorders. In this application, we focus on the molecular mechanisms regulating apoptotic and autophagic neural stem cell death, with a particular emphasis on the in vivo relevance of these overlapping death pathways in two important neonatal mouse models of human neuropathology. To accomplish our goals, we will pursue three specific aims. In aim one, we will test the hypothesis that p53 is a potent regulator of autophagic stress-induced neural stem cell death through its ability to engage both Puma-dependent and -independent death pathways. Aim two will characterize the molecular pathways involved in hypoxia-ischemia-induced neural stem cell death in the neonatal mouse brain in vivo, a model of human cerebral palsy, and test the hypothesis that p53 regulates neural stem cell death, at least in part, through a transcription-independent action. Aim three will extend our preliminary studies indicating that Puma, in a p53-independent fashion, regulates glucocorticoid-induced neural stem cell death in the neonatal mouse brain, and is a likely contributor to the neurological deficits associated with human premature birth. In total, these proposed studies of novel p53- and/or Puma-dependent neural stem cell death pathways represent an important extension of our highly productive investigations of apoptotic and autophagic cell death pathways and will yield new insights into the molecular mechanisms regulating neural stem cell death under physiological and pathological conditions. PUBLIC HEALTH RELEVANCE: Neural stem cells control nervous system development and too much, or too little, neural stem cell death is implicated in developmental brain malformations, brain tumor formation, and neuropsychiatric diseases. Defining the molecular pathways regulating neural stem cell death is important for understanding how the nervous system normally develops and identifying molecular targets for therapeutic interventions in a variety of human neuropathological disease states, including cerebral palsy, neurodevelopmental disorders, epilepsy, autism, brain tumors, and neurodegenerative diseases.