Sulfatides Act as Endogenous Toxin Reducing Efficiency of Remyelination

描述(申请人提供)：硫脂是髓鞘中最丰富的脂质之一，在多发性硬化症(MS)等脱髓鞘疾病的髓鞘破坏过程中，似乎释放到脑细胞外环境中。由于硫脂被认为是少突胶质细胞发生的负性调节因子，脱髓鞘过程中其胞外水平的异常升高可能是限制内源性少突胶质细胞前体(OPC)恢复髓鞘的因素之一。遗憾的是，硫脂对OPC分化的负调控机制尚不清楚。本申请的初步数据提供了一个可检验的假说，即脱髓鞘过程中释放的硫脂亚型通过解除Notch1和PDGFR信号通路的调控而对OPC产生毒性作用。为了挑战我们的假设，我们提出了四种硫脂异构体，C16：0，C18：0，C24：0和C24：1(OPC和髓鞘中的主要异构体)对OPC增殖、细胞死亡存活、细胞周期和分化能力的影响的实验，利用从P7大鼠骨痂中分离的具有良好特征的少突胶质前体细胞。这些研究将通过免疫细胞化学分析、流式细胞仪和液-质联用仪对在硫脂异构体存在的情况下生长的细胞在增殖或分化条件下进行。Notch1和PDGFR a受体的参与将通过经典的表达实验和对每个途径下游成分的功能分析来研究。总之，这些研究将使我们能够通过研究两个已被充分研究的信号通路的功能相关性来表征异构体中的四种硫脂异构体在OPC生物学中的作用。对这一过程的理解对设计成功的再髓鞘疗法具有重要意义，目前尚不适用于患有这种脱髓鞘疾病的患者。

DESCRIPTION (provided by applicant): Sulfatides, one of the most abundant lipids in myelin sheaths, appear to be released into the extracellular milieu of the brain during myelin destruction in demyelinating diseases such as multiple sclerosis (MS). Because sulfatides have been proposed as negative regulators of oligodendrogenesis, an abnormal elevation of their extracellular levels during demyelinating insult may be one of the factors limiting recovery of myelin by endogenous oligodendrocyte precursors (OPCs). Unfortunately, the mechanism mediating the negative regulation of OPC differentiation by sulfatides is unknown. Preliminary data in this application provides a testable hypothesis stating that sulfatide isoforms released during demyelination exert toxic effects on OPCs by deregulation of the Notch1 and PDGFr¿ signaling pathways. To challenge our hypothesis, we propose experiments to determine the effect of four sulfatide isoforms, C16:0, C18:0, C24:0 and C24:1 (the main isoforms in OPCs and myelin), on the proliferation, cell death- survival, cell cycle, and differentiation capacity o OPCs, by using the well-characterized oligodendrocyte precursor cells isolated from P7 rat corpus callosum. These studies will be performed by immunocytochemical analysis, flow cytometry and liquid chromatography-mass spectrometry of sulfatides from cells grown in the presence of the sulfatide isoforms in proliferating or differentiating conditions. The involvement of Notch1 and PDGFr a receptors will be studied by classical expression experiments and by functional analyses of downstream components in each pathway. Altogether, these studies will allow us to characterize the role of the four sulfatide isoforms in isoforms on OPCs biology, by investigating the functional relevance of two well-studied signaling pathways. The understanding of this process is of fundamental relevance in the design of successful remyelination therapies, which are yet unavailable for those suffering from this demyelinating disease.