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，主要影响人们在 生命中的活跃年数。长期脱髓鞘导致轴突变性，严重 神经功能障碍，在大多数情况下再生髓鞘是有限的。重新髓鞘形成失败可能 发生是由于现有的少突胶质细胞(OL)不能脱髓鞘轴突或 少突胶质前体细胞(OPC)不能在病变中产生髓鞘细胞。 OLS系细胞的动态受局部神经活动的错综复杂的调节。门诊部 从神经元接收突触和非突触信号，并经历去极化或增加 细胞内钙离子。然而，OPC到底是如何感知神经元活动水平并启动一种 触发末端分化和生存反应的信号级联仍然存在 不清楚。在神经元中，去极化诱导的钙离子进入轴突触发释放 突触小泡的神经递质聚集在突触前终末，通过一系列 涉及SNARE(可溶性N-乙基马来酰亚胺敏感因子连接)的分子事件 蛋白质受体)蛋白质。OL系细胞也表达各种SNARE蛋白和转录本。我们在OPC及其后代中灭活泡泡状SNARE蛋白的初步结果显示，SNARE- 依赖机制对于适当产生可行的组织来说是至关重要的。这些观察结果导致了 美国推测晚期OPC中依赖圈套的囊泡胞吐是由 神经元信号和具有促进OL分化和生存的关键自分泌功能 新的老东家。这将通过1)有缺陷的囊泡的分裂的OPC的命运分析来检验 圈套以确定囊泡相关膜蛋白2和/或3是否丢失 (VAMP2/3)功能损害OL分化和生存(目标1)；2)成像陷阱- 在培养的OPC和体内包含囊泡和胞吐事件以确定 神经元来源的信号促进SNARE介导的胞吐和囊泡聚集 (目标2)；以及3)鉴定自分泌信号的蛋白质组学方法(S)。 依赖圈套的OPC(目标3)。该项目将为关于晚期OPC触发其终末分化和存活计划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.