Regulation of neuronal stem cell death

神经元干细胞死亡的调节

• 批准号: 6606734
• 负责人: Erhard Bieberich
• 金额: $ 30.58万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6606734
• 关键词: apoptosis; biological signal transduction; brain; cell cycle; cell differentiation; cell growth regulation; cell population study; ceramides; clinical research; cysteine endopeptidases; developmental neurobiology; embryonic stem cell; enzyme activity; fluorescence resonance energy transfer; growth factor; immunocytochemistry; immunoprecipitation; in situ hybridization; kinase inhibitor; laboratory mouse; mammalian embryology; neurons; protein kinase C; protein structure function; stem cells; terminal nick end labeling

DESCRIPTION (provided by applicant): Between gestational day E12 and 18, about half of the mitotic neuronal cells die in embryonal mouse forebrain due to apoptosis. Studies with caspase knockout mice have demonstrated that apoptosis is necessary to prevent hyperproliferation of neuronal stem cells and subsequent, severe brain malformation. It is not known, however, which factors selectively induce or prevent apoptosis in individual, differentiating neuronal stem cells. We have shown for the first time, that the peak time of apoptosis in embryonal mouse brain (E14.5) is concurrent with elevation of endogenous ceramide and activation of caspase 3. We have also shown that the concentration of ceramide is high enough to kill neuronal progenitor cells grown in culture. From these observations, we propose that elevation of ceramide may be critical for induction of apoptosis in differentiating neuronal stem cells. Recently, several studies have reported that the ceramide-mediated formation of an inhibitory complex between PAR-4 and atypical PKC ,induces apoptosis. Our own studies with in vitro differentiated embryonic stem (ES) cells have shown that induction of apoptosis by ceramide is concurrent with up-regulation of PAR-4. We propose that PAR-4 is one of probably several pro-apoptotic proteins that induce apoptosis when their expression and that of ceramide is elevated. Our main hypothesis is that simultaneous upregulation of endogenous ceramide and ceramide-associated proteins (CAPs) results in formation of a pro-apoptotic protein complex (PAC) that triggers apoptosis in mitotic neuronal stem cells by suppression of anti-apoptotic, cell survival signaling. We will test this hypothesis in three Specific Aims using murine ES cells as model system. In Specific Aim 1, we will test the hypothesis that up-regulation of ceramide induces apoptosis specifically in mitotic neuronal stem cells. In Specific Aim 2, we will test the hypothesis that ceramide/CAP-induced PAC formation results in activation of caspases. In Specific Aim 3, we will test the hypothesis that elevation of ceramide and down-regulation of cell survival signaling is synchronized by the cell cycle and growth factors. In conclusion, this study will identify mechanisms for regulation of apoptosis by ceramide that are critical for normal brain development and/or the etiology of subsequent, pathological disorders in adulthood.

描述（由申请人提供）：在E12和18日之间，大约一半的有丝分裂神经元细胞死于凋亡引起的胚胎小鼠前脑。胱天冬酶敲除小鼠的研究表明，凋亡对于防止神经元干细胞的过度增殖和随后的严重脑畸形是必要的。然而，尚不清楚哪些因素选择性诱导或预防个体区分神经元干细胞的凋亡。我们首次表明，胚胎小鼠脑中凋亡的峰值时间（E14.5）与内源性神经酰胺的升高和caspase 3的激活同时发生。我们还表明，神经酰胺的浓度足够高，足以杀死在培养中生长的神经元细胞。从这些观察结果中，我们提出，神经酰胺的升高对于诱导分化神经元干细胞中凋亡至关重要。最近，几项研究报道了神经酰胺介导的抑制性复合物在Par-4和非典型PKC之间的形成，诱导了凋亡。我们对体外分化胚胎（ES）细胞的研究表明，神经酰胺诱导凋亡与PAR-4的上调同时。我们建议Par-4可能是几种促凋亡蛋白之一，它们的表达和神经酰胺的表达升高时会诱导凋亡。我们的主要假设是，同时上调内源性神经酰胺和与神经酰胺相关的蛋白（CAP）导致形成促凋亡蛋白复合物（PAC），从而通过抑制抗凋亡，细胞存活信号传导抑制有丝分裂神经元干细胞中的凋亡中凋亡。我们将使用鼠ES细胞作为模型系统的三个特定目标来检验这一假设。在特定目标1中，我们将检验以下假设：神经酰胺的上调会诱导有丝分裂神经元干细胞的凋亡。在特定的目标2中，我们将测试神经酰胺/帽诱导的PAC形成导致胱天蛋白酶激活的假设。在特定目标3中，我们将检验以下假设：神经酰胺的升高和细胞存活信号的下调与细胞周期和生长因子同步。总之，这项研究将确定神经酰胺调节细胞凋亡的机制，这对于正常的脑发育和/或成年后病理疾病的病因至关重要。