Regulation of neuronal stem cell death

神经元干细胞死亡的调节

• 批准号: 6893743
• 负责人: Erhard Bieberich
• 金额: $ 30.57万
• 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/6893743
• 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（申请人提供）：在妊娠第E12天至第18天之间，胚胎小鼠前脑中约一半的有丝分裂神经元细胞因细胞凋亡而死亡。对半胱天冬酶敲除小鼠的研究表明，细胞凋亡对于防止神经元干细胞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阻止个体分化神经元干细胞的凋亡。我们首次证明，胚胎小鼠大脑（E14.5）细胞凋亡的峰值时间与内源性神经酰胺的升高和半胱天冬酶3的激活同时发生。我们还表明，神经酰胺的浓度足够高，足以杀死培养物中生长的神经元祖细胞。根据这些观察结果，我们提出神经酰胺的升高可能对于诱导分化神经元干细胞凋亡至关重要。最近，一些研究报道，神经酰胺介导的 PAR-4 和非典型 PKC 之间抑制复合物的形成可诱导细胞凋亡。我们自己对体外分化的胚胎干 (ES) 细胞的研究表明，神经酰胺诱导细胞凋亡与 PAR-4 的上调同时发生。我们认为 PAR-4 可能是几种促凋亡蛋白之一，当其表达和神经酰胺的表达升高时，可诱导细胞凋亡。我们的主要假设是，内源性神经酰胺和神经酰胺相关蛋白 (CAP) 的同时上调会导致促凋亡蛋白复合物 (PAC) 的形成，该复合物通过抑制抗凋亡、细胞存活信号传导来触发有丝分裂神经元干细胞的凋亡。我们将使用鼠 ES 细胞作为模型系统，在三个具体目标中测试这一假设。在具体目标 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凋亡。在具体目标 2 中，我们将检验神经酰胺/CAP 诱导的 PAC 形成导致半胱天冬酶激活的假设。在具体目标 3 中，我们将测试以下假设：神经酰胺的升高和细胞存活信号的下调是由细胞周期和生长因子同步的。总之，这项研究将确定神经酰胺调节细胞凋亡的机制，这对于正常大脑发育和/或成年后病理性疾病的病因至关重要。