Brain lipid metabolism/alpha-synuclein gene-abated mice

虽然α-突触核蛋白在神经元突触中高度表达，但该蛋白的功能作用尚不清楚。阐明α-突触核蛋白的生理功能很重要，因为该蛋白是家族性帕金森病(PD)的致病因素，主要是因为它与路易小体有关，路易小体是PD的病理标志。在野生型α-突触核蛋白或野生型α-突触核蛋白的细胞系中，野生型α-突触核蛋白与脂滴结合，提示天然蛋白可能参与脂类的运输或代谢。在一组使用α-突触核蛋白基因减弱的小鼠的平行研究中，与对照小鼠相比，整个大脑和分离的突触体内的一些不同磷脂的稳态质量都有很大的下降。此外，在一些不同的磷脂类别中，二十二碳六烯酸的数量显著减少，这表明对二十二碳六烯酸的摄取和运输减少。这些数据表明神经元脂代谢的下调。由于脂肪酸结合蛋白可以改变磷脂代谢和改变磷脂酰链组成，我提出了以下假设：α-突触核蛋白直接影响神经元对脂肪酸的摄取和靶向，本质上是作为神经元脂肪酸结合蛋白发挥作用。然而，α-突触核蛋白在神经元脂质摄取、运输和代谢中起作用的这一假设需要结合整个动物和细胞培养研究来进一步阐明。以下特定目的旨在利用α-突触核蛋白基因减弱的小鼠、从这些小鼠衍生的神经元培养以及稳定表达突变型和野生型α-突触核蛋白的H293细胞来研究α-突触核蛋白在脑脂代谢中的潜在作用。1.采用稳态示踪动力学分析方法，研究α-突触核蛋白对正常小鼠和α-突触核蛋白基因缺失小鼠脑内[~3H]-棕榈酸、[~3H]-花生四烯酸和[~3H]-二十二碳六烯酸摄取和代谢的影响。2.利用来自对照和基因减弱小鼠的细胞以及稳定转染的细胞系，确定α-突触核蛋白对细胞脂肪酸摄取、代谢和运输的影响。

Although alpha-synuclein is highly expressed in neuronal synapses, the functional role of this protein remains unclear. Elucidating the physiological function of alpha-synuclein is important as this protein is implicated as a causative factor in familial Parkinson disease (PD), primarily because of its association with Lewy bodies, a pathological marker of PD. In cell lines transfected with either mutant alpha- synuclein or wildtype alpha-synuclein, wildtype but not mutant alpha- synuclein associate with lipid droplets, suggesting that the native protein may be involved in lipid trafficking or metabolism. In a parallel set of studies using alpha-synuclein gene-abated mice, there was a large decrease in the steady-state mass of a number of different phospholipids in both whole brain and isolated synaptosomes compared to control mice. Further, there was a significant decrease in the amount of docosahexaenoic acid in a number of different phospholipid classes, suggesting a decrease in uptake and trafficking of docosahexaenoic acid. These data suggest a down-regulation of neuronal lipid metabolism. Because fatty acid binding proteins can alter phospholipid metabolism and alter phospholipid acyl chain composition, I submit the following hypothesis: alpha-Synuclein directly affects fatty acid uptake and targeting in neurons, essentially functioning as a neuronal fatty acid binding protein. However, this hypothesis that alpha-synuclein has a role in neuronal lipid uptake, trafficking, and metabolism needs to be further elucidated using a combination of whole animal and cell culture studies. The following specific aims are designed to address the potential role of alpha-synuclein in brain lipid metabolism using alpha- synuclein gene abated mice, neuronal cultures derived from these mice, and stably transfected H293 cells expressing mutant and wildtype alpha-synuclein. These aims are: 1. Determine the effect of alpha-synuclein on the uptake and subsequent metabolism of [3H]-palmitic, [3H]-arachidonic, and [3H]- docosahexaenoic acid in brains of control and alpha-synuclein gene- abated mice in vivo using steady-state tracer kinetic analysis. 2. Using cells derived from control and gene-abated mice as well as stably transfected cell lines, determine the effect of alpha-synuclein on cellular fatty acid uptake, metabolism, and trafficking.