Inflammation and NG2 Cell Differentiation

描述（由申请人提供）：多发性硬化症（MS）是一种脱髓鞘疾病，在美国影响35万人，是慢性神经功能缺损的主要原因，影响成年人在他们生命中最活跃的时期。再髓鞘化失败是MS的长期和原发性进行性病变的特征，并且与脉冲传导失败和轴突病理学相关。尽管髓鞘再生失败的临床效应使人衰弱，但为什么一些病变有效地髓鞘再生而另一些没有的原因仍然不清楚。表达NG 2蛋白聚糖的神经胶质细胞（NG 2细胞）广泛存在于整个成熟的中枢神经系统中。最近的遗传命运作图研究提供了直接的证据，它们不仅在发育过程中，而且在成熟的中枢神经系统中产生少突胶质细胞。使用我们已经产生的新的转基因小鼠品系，我们已经观察到，在成熟NG 2细胞中特异性地缺失碱性螺旋-环-螺旋转录因子Olig 2减少了成年大脑中从NG 2细胞产生的少突胶质细胞的数量。我们还进行了高通量筛选以鉴定上调Olig 2转录的化合物。我们将使用这些新获得的工具来测试假设，即实验性自身免疫性脑脊髓炎（EAE）中成功的髓鞘再生需要临界水平的Olig 2，EAE是MS的临床相关啮齿动物模型。在目标1中，我们将确定Olig 2的缺失是否会损害NG 2细胞在EAE病变中产生新的少突胶质细胞的能力。在目标2中，我们将确定新鉴定的增加Olig 2转录的化合物是否激活Sonic hedgehog-Gli途径或促分裂原活化蛋白激酶途径，并测试影响不同途径的化合物促进EAE髓鞘再生的能力。在目标3中，我们将确定Ezh 2的缺失是否会通过去抑制髓鞘形成所需的基因来促进髓鞘再生，Ezh 2是负责甲基化组蛋白H3上赖氨酸27的Polycomb阻遏复合物的成员。

DESCRIPTION (provided by applicant): Multiple sclerosis (MS) is a demyelinating disease that affects 350,000 people in the U.S. and is a major cause of chronic neurological deficit, affecting adults during their most active period of their lives. Remyelination failure is a characteristic of long-standing and primary progressive lesions of MS and is associated with impulse conduction failure and axonal pathology. Despite the debilitating clinical effects of remyelination failure, the reason why some lesions are effectively remyelinated while others are not remains unclear. Glial cells that express the NG2 proteoglycan (NG2 cells) exist widely throughout the mature central nervous system. Recent genetic fate mapping studies have provided direct demonstration that they generate oligodendrocytes not only during development but also in the mature central nervous system. Using new transgenic mouse lines that we have generated, we have observed that deletion of the basic helix-loop-helix transcription factor Olig2 specifically in mature NG2 cells reduces the number of oligodendrocytes that are produced from NG2 cells in the adult brain. We have also performed a high throughput screen to identify compounds that upregulate Olig2 transcription. We will use these newly acquired tools to test the hypothesis that a critical level of Olig2 is required for successful remyelination in experimental autoimmune encephalomyelitis (EAE), which is a clinically relevant rodent model of MS. This will be tested in the following three specific aims. In Aim 1, we will determine whether loss of Olig2 will compromise the ability of NG2 cells to produce new oligodendrocytes in EAE lesions. In Aim 2, we will determine whether the newly identified compounds that increase Olig2 transcription activate the Sonic hedgehog-Gli pathway or the mitogen-activated protein kinase pathway and test compounds that affect different pathways for their ability to promote remyelination in EAE. In Aim 3, we will determine whether loss of Ezh2, which is a member of the Polycomb Repressor Complex responsible for methylating lysine 27 on histone H3, will promote remyelination by derepressing genes required for myelination.