SPHINGOLIPIDS IN INTEGRIN-MEDIATED OLIGODENDROCYTE SURVIVAL SIGNALING IN HYPOXI

缺氧时整合素介导的少突胶质细胞生存信号转导中的鞘脂

• 批准号: 7381854
• 负责人: TATYANA GUDZ
• 金额: $ 12.83万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7381854
• 关键词: SPHINGOLIPIDS; INTEGRIN; MEDIATED; OLIGODENDROCYTE; SURVIVAL

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Oligodendrocytes are critical regulators of nervous system function and play a central role in many acute neurological disorders, including stroke. Glutamate excitotoxicity contributes to ischemic oligodendrocyte injury; however, it is not clear what the intracellular mechanisms are leading to cell death. This proposal examines a hypothesis that over-activation of glutamate receptors and hypoxia/ischemia reduces oligodendrocyte survival, leading to apoptosis, which is mediated in part by ceramide and prevented by sphingosine-1-phosphate. We use primary cultures of oligodendrocytes and a mouse model of stroke to study the role of sphingolipids in neural cells. We assess cellular activity using fluorescence measurements of cell survival, western blotting, immunoprecipitation and high performance lipid chromatography coupled with mass spectrometry. In cultured oligodendrocytes, we found that stimulation of glutamate receptor induced biphasic increase in endogenous ceramide levels via two different mechanisms. The data suggest that an early increase in C18-ceramide level, which is generated by de novo synthesis and it is not accompanied with sphingomyelin hydrolysis could play a role in protecting oligodendrocytes from glutamate-induced damage. Thus, in isolated mitochondria, we found that C18-ceramide is a powerful inhibitor of mitochondrial permeability transition pore which is a pivotal part of apoptotic machinery. This is the first demonstration that endogenous ceramide could block the pore. The late increase in ceramide levels was accompanied by a substantial sphingomyelin hydrolysis. The data provide further support for our hypothesis and suggest that the late increase in ceramide level could manifest a pro-apoptotic role of ceramide in oligodendrocyte injury. It also raises the question as to what ceramide-generating enzymes are activated by ischemic insult. In the animal model of stroke, brief cerebral ischemia increased ceramide levels in brain without apparent sphingomyelin hydrolysis. These data are in line with our findings in cultured oligodendrocytes and suggest that the early activation of de novo ceramide synthesis occurs in cerebral ischemic brain injury.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子弹和调查员（PI）可能已经从其他NIH来源获得了主要资金，因此可以在其他清晰的条目中代表。列出的机构适用于该中心，这不一定是调查员的机构。少突胶质细胞是神经系统功能的关键调节剂，并且在包括中风在内的许多急性神经系统疾病中起着核心作用。谷氨酸兴奋性有助于缺血性少突胶质细胞损伤。但是，尚不清楚细胞内机制导致细胞死亡。该提案研究了一个假设，即谷氨酸受体和缺氧/缺血的过度激活降低了少突胶质细胞的存活，导致凋亡，导致细胞凋亡，部分是由神经酰胺介导的，并由鞘氨碱1-磷酸盐预防。我们使用少突胶质细胞的原发性培养物和中风的小鼠模型来研究鞘脂在神经细胞中的作用。我们使用细胞存活，蛋白质印迹，免疫沉淀和高性能脂质色谱和质谱法的荧光测量评估细胞活性。在培养的少突胶质细胞中，我们发现通过两种不同的机制刺激谷氨酸受体诱导的内源性神经酰胺水平的双相增加。数据表明，通过从头合成产生的C18-钙酰胺水平的早期增加，并且不伴有鞘氨素水解，可以在保护少突胶质细胞免受谷氨酸诱导的损伤方面发挥作用。因此，在孤立的线粒体中，我们发现C18-钙酰胺是线粒体通透性过渡孔的强大抑制剂，这是凋亡机制的关键部分。这是内源性神经酰胺可以阻塞孔的第一次演示。神经酰胺水平的晚期增加伴随着大量的鞘磷脂水解。数据为我们的假设提供了进一步的支持，并表明神经酰胺水平的晚期增加可能表现出神经酰胺在少突胶质细胞损伤中的促凋亡作用。这也提出了一个问题，即通过缺血性侮辱激活哪种神经酰胺生成酶。在中风的动物模型中，短暂的脑缺血增加了脑中神经酰胺的水平，而没有明显的鞘磷脂水解。这些数据符合我们在培养的少突胶质细胞中的发现，并表明在大脑缺血性脑损伤中发生了新的神经酰胺合成的早期激活。