SNARE complex-mediated exocytosis in oligodendrocyte differentiation and survival

多发性硬化症是一种慢性脱髓鞘疾病，主要影响在其发病期间的人。 活跃的岁月。长期脱髓鞘导致轴突变性， 神经缺陷，并且在大多数情况下髓鞘再生有限。再髓鞘化失败可能 由于现有的少突胶质细胞（OL）无法使脱髓鞘轴突髓鞘化而发生，或 在损伤中少突胶质细胞前体细胞（OPC）不能产生髓鞘化OL。 OLs谱系细胞的动力学受到局部神经活动的复杂调节。OPCs 从神经元接收突触和非突触信号，并经历去极化或增加 胞内Ca 2+。然而，OPCs究竟如何感知神经元活动水平并启动一个神经元活动， 触发终末分化和存活反应的信号级联反应仍然存在 不清楚在神经元中，去极化诱导的Ca 2+进入轴突触发了 来自突触囊泡的神经递质通过一系列的 涉及SNARE（可溶性N-乙基马来酰亚胺敏感因子附着）的分子事件 蛋白质受体）蛋白质。OL谱系细胞还表达各种SNARE蛋白和转录物。我们在OPCs及其后代中灭活囊泡SNARE蛋白的初步结果显示，SNARE- 依赖性机制对于正确产生有活力的OL是关键的。这些观察导致 我们假设晚期OPCs中囊泡SNARE依赖性胞吐作用是由 神经元信号，并具有重要的自分泌功能，以促进OL分化和存活 新的OL。这将通过1）具有缺陷性囊泡的分裂的OPC的命运分析来测试。 SNARE以确定囊泡相关膜蛋白2和/或3的丢失是否 （VAMP 2/3）功能损害OL分化和存活（Aim 1）; 2）成像SNARE- 含有囊泡和胞吐事件在培养的OPC和体内，以确定是否 神经源性信号促进SNARE介导的胞吐作用和囊泡聚集 (Aim 2）;和3）蛋白质组学方法，以鉴定从细胞中释放的自分泌信号， OPCs以SNARE依赖的方式（目标3）。 该项目将为晚期OPCs触发其终末分化和存活程序的细胞机制的新原理建立实验证据。 对神经元信号的反应。

Multiple sclerosis is a chronic demyelinating disease affecting primarily people during their active years of life. Long-lasting demyelination leads to axonal degeneration with severe neurological deficits, and in most cases remyelination is limited. Remyelination failure could occur due to the inability of existing oligodendrocytes (OLs) to myelinate demyelinated axons or failure of oligodendrocyte precursor cells (OPCs) to generate myelinating OLs in the lesion. The dynamics of OLs lineage cells is intricately modulated by the local neural activity. OPCs receive synaptic and non-synaptic signals from neurons and undergo depolarization or increase intracellular Ca2+. However, exactly how OPCs sense the level of neuronal activity and initiate a signaling cascade that triggers a terminal differentiation and survival response has remained unclear. In neurons, depolarization-induced Ca2+ entry into axons triggers release of neurotransmitters from synaptic vesicles clustered at the presynaptic terminal by a series of molecular events that involve SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. OL lineage cells also express various SNARE proteins and transcripts. Our preliminary results of inactivating vesicular SNARE proteins in OPCs and their progeny revealed that SNARE- dependent mechanisms are critical for the proper generation of viable OLs. These observations led us to hypothesize that vesicular SNARE-dependent exocytosis in late OPCs is triggered by neuronal signals and has a critical autocrine function to promote OL differentiation and survival of new OLs. This will be tested by 1) fate analysis of divided OPCs that have defective vesicular SNAREs to determine whether loss of Vesicle-associated membrane protein 2 and/or 3 (VAMP2/3) function compromises OL differentiation and survival (Aim 1); 2) imaging SNARE- containing vesicles and exocytosis events in cultured OPCs and in vivo to determine whether neuronally derived signals promote SNARE-mediated exocytosis and clustering of vesicles (Aim 2); and 3) a proteomics approach to identify the autocrine signal(s) that is released from OPCs in a SNARE-dependent manner (Aim 3). The project will establish experimental evidence for a novel principle regarding the cellular mechanism by which late OPCs trigger their terminal differentiation and survival programs in response to neuronal signals.