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，神经干细胞失调死亡有助于脑和脊髓畸形，脑肿瘤形成，并可能导致神经退行性和神经精神疾病。细胞死亡途径具有显著的细胞特异性和刺激特异性，依赖于一系列分子之间的相互作用，包括p53、Bcl-2家族成员、半胱天蛋白酶和各种自噬相关蛋白。在该基金支持的一系列研究中，我们定义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）。在这篇修订后的竞争性更新申请中，我们提出了一系列新的研究，重点关注p53和Puma对生理性和病理性神经干细胞死亡的调控。除了众所周知的凋亡细胞死亡（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）越来越多地被认为发生在神经病理条件下。我们资助的研究已经证明p53和Bcl-2家族成员在调节神经干细胞的凋亡和自噬细胞死亡中发挥作用。我们最近的数据表明，神经干细胞的死亡是由多种病理刺激触发的，包括遗传毒性应激、缺氧缺血性损伤和糖皮质激素暴露。这些刺激已涉及到几个人类新生儿和儿童神经系统疾病的发病机制。在本应用中，我们关注调节凋亡和自噬神经干细胞死亡的分子机制，特别强调这些重叠死亡途径在两种重要的新生小鼠人类神经病理学模型中的体内相关性。为了实现我们的目标，我们将追求三个具体目标。在第一个目标中，我们将通过p53参与puma依赖性和非依赖性死亡途径的能力来验证p53是自噬应激诱导的神经干细胞死亡的有效调节因子的假设。目的二将描述新生儿小鼠大脑中缺氧缺血诱导的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至少在一定程度上通过转录不依赖的作用调节神经干细胞死亡的假设。目标3将扩展我们的初步研究，表明Puma以不依赖p53的方式调节新生小鼠大脑中糖皮质激素诱导的神经干细胞死亡，并且可能是与人类早产相关的神经功能缺陷的一个因素。总之，这些新的p53和/或puma依赖性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延伸，并将对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。

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.