Sulfatides Act as Endogenous Toxin Reducing Efficiency of Remyelination

描述（由申请人提供）：硫脂脂是髓鞘中最丰富的脂质之一，在脱髓鞘疾病（如多发性硬化症（MS））中髓鞘破坏时，似乎被释放到脑的细胞外环境中。由于硫脂脂已被认为是少突胶质发生的负调节因子，脱髓鞘损伤期间其细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（OPCs）恢复髓磷脂的因素之一。不幸的是，巯基脂介导OPC分化负调控的机制尚不清楚。本应用的初步数据提供了一个可测试的假设，即脱髓鞘过程中释放的硫脂异构体通过解除Notch1和PDGFr¿信号通路对OPCs产生毒性作用。为了挑战我们的假设，我们提出了实验，以确定四种硫脂异构体C16:0， C18:0， C24:0和C24:1 （OPCs和髓磷脂中的主要异构体）对OPCs的增殖，细胞死亡-存活，细胞周期和分化能力的影响，使用从P7大鼠胼胝体分离的特征明确的少突胶质前体细胞。这些研究将通过免疫细胞化学分析、流式细胞术和液相色谱-质谱法对在增殖或分化条件下存在硫脂质异构体的细胞进行硫脂质分析。Notch1和PDGFr a受体的参与将通过经典表达实验和每个通路下游成分的功能分析来研究。总的来说，这些研究将使我们能够通过研究两种已被充分研究的信号通路的功能相关性，来表征四种硫代脂肪酸异构体在OPCs生物学中的作用。对这一过程的理解对于设计成功的髓鞘再生疗法具有根本的相关性，而对于那些患有这种脱髓鞘疾病的人来说，这种疗法尚不可用。

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.