Molecular Characterization of Neural Stem Cell Apoptosis

描述（由申请人提供）：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导致脑和脊髓畸形、脑肿瘤形成，并可能导致神经退行性疾病和神经精神疾病。细胞死亡途径是显著的细胞特异性和刺激特异性的，并且依赖于包括p53、Bcl-2家族成员、半胱天冬酶和多种自噬相关蛋白的一系列分子之间的相互作用。在一系列由该基金支持的研究中，我们已经确定了几种刺激特异性神经干细胞死亡途径，涉及p53和/或Puma，Bcl-2家族的促凋亡成员。在这个修订后的竞争性更新申请中，我们提出了一系列新的研究，重点是p53和Puma调节生理和病理性神经干细胞死亡。除了众所周知的凋亡性细胞死亡（I型程序性细胞死亡）的作用之外，自噬性细胞死亡（II型程序性细胞死亡）已被越来越多地认识到在神经病理学条件下发生。我们资助的研究已经证明了p53和Bcl-2家族成员在调节神经干细胞凋亡和自噬细胞死亡中的作用。我们最近的数据表明，神经干细胞死亡是由体内的各种病理刺激，包括遗传毒性应激，缺氧缺血性损伤，糖皮质激素暴露触发。这些刺激与几种人类新生儿和儿童神经系统疾病的发病机制有关。在这个应用程序中，我们专注于调节细胞凋亡和自噬性神经干细胞死亡的分子机制，特别强调这些重叠的死亡途径在两个重要的人类神经病理学新生小鼠模型的体内相关性。为了实现我们的目标，我们将追求三个具体目标。在目标一，我们将测试的假设，即p53是一个强大的自噬应激诱导的神经干细胞死亡的调节因子，通过其能力，从事两个PUMA依赖性和非依赖性死亡途径。目的二将描述缺氧缺血诱导的新生小鼠脑内神经干细胞死亡的分子途径，这是一种人类脑瘫模型，并验证p53至少部分通过转录非依赖性作用调节神经干细胞死亡的假设。目的三将扩展我们的初步研究表明，彪马，在一个p53独立的方式，调节糖皮质激素诱导的神经干细胞死亡的新生小鼠大脑，是一个可能的贡献者与人类早产相关的神经功能缺损。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的高生产力的凋亡和自噬细胞死亡途径的调查的重要延伸，并将产生新的见解调节神经干细胞死亡的分子机制在生理和病理条件下。 公共卫生相关性：神经干细胞控制神经系统发育，过多或过少的神经干细胞死亡与发育性脑畸形、脑肿瘤形成和神经精神疾病有关。定义调节神经干细胞死亡的分子通路对于理解神经系统如何正常发育和识别用于各种人类神经病理疾病状态的治疗干预的分子靶标是重要的，所述人类神经病理疾病状态包括脑瘫、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.