Glucose metabolism and mitochondrial function in adult neurons

成年神经元中葡萄糖代谢的机制和途径知之甚少。在绝大多数神经元中，细胞外葡萄糖浓度在5- 10 mM的正常范围内，与通过非胰岛素依赖性GLUT同种型介导的细胞内葡萄糖浓度平衡。通过糖酵解的葡萄糖流量受到约1- 2 mM葡萄糖的己糖激酶的限制，因此对葡萄糖具有较低亲和力的酶，如醛糖还原酶和醛还原酶，可能是活性的，并有助于整体葡萄糖代谢。在神经元中，目前还不清楚这些途径是否重要，如果激活，对神经元表型，代谢和生物能量学的后续影响仍然未知。因此，需要研究来提高我们对葡萄糖代谢的基本机制的理解，并在成人神经元中产生生物能量结果，其中高内在代谢活动对细胞提出了独特的要求。其目标如下：（1）确定在一系列葡萄糖浓度和生长因子条件下激活的葡萄糖依赖性代谢途径，并描述成年神经元中的调节机制，以及（2）研究葡萄糖代谢的改变如何影响成年神经元中的线粒体功能和表型。研究将主要集中在成年啮齿动物的培养感觉神经元的使用。技术将包括基于慢病毒的shRNA递送以调节基因表达，在线粒体水平的真实的时间共聚焦成像，线粒体表型的蛋白质组学分析，葡萄糖通量的评估和一般生物化学以研究线粒体功能和酶如醛糖还原酶和AMPK的表达。这些结果将为神经元中葡萄糖代谢的途径和影响提供更深入的了解，并为糖尿病等代谢性疾病的治疗提供新的药物靶点。

The mechanism and pathways of glucose metabolism in adult neurons are poorly understood. In the vast majority of neurons extracellular glucose concentration in the normal range of 5-10mM is equilibriated with intracellular glucose concentration mediated through non-insulin-dependent GLUT isoforms. The flux of glucose through glycolysis is limited by hexokinase at around 1-2mM glucose and so enzymes with lower affinity for glucose, such as aldose reductase and aldehyde reductase, are presumably active and contribute to overall glucose metabolism. In neurons, it is very unclear if such pathways are important and if activated the subsequent impact on neuronal phenotype, metabolism and bioenergetics remains unknown. Studies are therefore required to enhance our understanding of the basic mechanisms of glucose metabolism and resulting bioenergetic outcomes in adult neurons where the high intrinsic metabolic activity places unique demands on the cell. The aims are as follows: (1) To determine which glucose-dependent metabolic pathways are activated under a range of glucose concentrations and growth factor conditions and delineate mechanism of regulation in adult neurons, and (2) To investigate how alterations in glucose metabolism impact on mitochondrial function and phenotype in adult neurons. Studies will primarily focus on use of cultured sensory neurons from adult rodents. Techniques will include lentiviral-based delivery of shRNA to modulate gene expression, real time confocal imaging at the level of the mitochondrion, proteomic analysis of mitochondrial phenotype, assessment of glucose flux and general biochemistry to investigate mitochondrial function and expression of enzymes such as aldose reductase and AMPK. The results will provide greater insight with regard to pathways and impact of glucose metabolism in neurons and provide new drug targets for therapy in metabolic diseases such as diabetes.