Hypoglycemic signaling targets in astrocytes

描述（由申请人提供）：低血糖是糖尿病治疗中常见的并发症。严重的低血糖可引起癫痫发作、无意识和不可逆转的认知障碍，可能是由于神经元损伤和死亡。星形胶质细胞是一种遍布大脑的星形胶质细胞，在支持和保护神经元方面发挥着重要作用。最近的研究表明，在低血糖时，星形胶质细胞能够迅速产生底物来喂养能量耗尽的神经元，可能是通过细胞内糖原的分解。星形胶质细胞感知葡萄糖水平下降的机制，以及控制糖原代谢的下游信号通路，目前尚不清楚。我们提出了一种基于发现的，但重点的方法来识别星形细胞低血糖信号通路的组成部分，利用两种强大的互补方法：蛋白质组学和一种新的表达克隆方法。我们将验证一个普遍的假设：星形胶质细胞具有特殊的葡萄糖信号分子和机制，能够快速调节低血糖时神经元代谢的底物。该项目的具体目标是：

DESCRIPTION (provided by applicant): Hypoglycemia is a common complication in the management of diabetes. Severe hypoglycemia can cause seizures, unconsciousness, and irreversible cognitive impairment, presumably because of neuronal injury and death. Astrocytes, the star-shaped glial cells found throughout the brain, perform important roles to support and protect neurons. Recent work indicates that in hypoglycemia, astrocytes are capable of rapidly generating substrates to feed energy-depleted neurons, probably by breakdown of intracellular glycogen. The mechanisms by which astrocytes sense dropping glucose levels, and the downstream signaling pathways controlling glycogen metabolism, are poorly understood. We propose a discovery-based, but focused approach to identify components of astrocytic hypoglycemic signaling pathways, utilizing two powerful and complementary methodologies: proteomics and a novel method of expression cloning. We will test a general hypothesis: Astrocytes possess specialized glucose signaling molecules and mechanisms enabling rapid regulation of substrates for neuronal metabolism in hypoglycemia. The specific aims of the project are: 1) Identify molecular targets of acute, subacute and episodic hypoglycemia in astrocytes using two independent and complementary approaches: a) proteomics (two-dimensional gel electrophoresis with protein identification by mass spectrometry); and b) FIMS, a novel expression cloning method developed in our laboratory. 2) Validate targets using cell culture and in vivo models of hypoglycemia. The entire set of identified hypoglycemia-regulated proteins will be made available as a database for the research community. A subset of the targets identified will be the subject of future hypothesis-driven research projects in our laboratory. The longterm goal is to develop pharmacologic or molecular methods to augment or modulate neuroprotective aspects of the astrocytic response to hypoglycemia.