Regulation of glial lineage by Olig2

描述（由申请方提供）：哺乳动物中枢神经系统（CNS）中表达NG 2蛋白聚糖的神经胶质细胞（NG 2细胞）出现在胚胎晚期，并迅速扩增以均匀占据整个CNS。这些细胞不同于成熟的少突胶质细胞、星形胶质细胞或静息分枝小胶质细胞，并且代表第四大胶质细胞群体。培养的NG 2细胞产生少突胶质细胞，因此被称为少突胶质细胞前体细胞（OPC）。使用我们新产生的NG 2creBAC转基因小鼠的体内命运作图研究显示，白色物质和背侧前脑中的NG 2细胞仅产生少突胶质细胞，而腹侧前脑灰质中的NG 2细胞产生少突胶质细胞和原生质星形胶质细胞。当NG 2细胞中的碱性螺旋-环-螺旋转录因子Olig 2缺失时，背侧前脑中几乎所有的NG 2细胞都以少突胶质细胞为代价分化为星形胶质细胞，导致髓鞘丢失。因此，NG 2细胞保持谱系可塑性，并且单个转录因子Olig 2在维持NG 2细胞的少突胶质细胞命运中起关键作用。在更分化的少突胶质细胞中Olig 2的缺失不改变新皮质GFAP表达的水平，与Olig 2在早期阶段的缺失相反，这表明存在发育窗口，其中少突胶质细胞谱系细胞可以在Olig 2不存在的情况下转化为星形胶质细胞。目的1将测试的假设，NG 2细胞失去其谱系可塑性，并成为不能产生星形胶质细胞，因为它们成熟为少突胶质细胞，NG 2细胞的谱系可塑性的限制是由表观遗传机制调节。目的2将验证以下假设：在正常脑中存在维持NG 2细胞中Olig 2表达并阻止其分化为星形胶质细胞的信号通路。这将通过筛选改变Olig 2转录活性的化合物的小分子文库来探索。鉴定的化合物将用于未来的研究，以描绘调节Olig 2表达的内源性信号通路。然后可以在未来的损伤修复范例中操纵该途径，以促进NG 2细胞分化为所需的细胞类型。 公共卫生相关性：NG 2细胞代表神经胶质祖细胞群，其广泛分布于中枢神经系统的灰质和白色物质中。拟议的研究旨在确定通过转录因子Olig 2调节其谱系可塑性的机制。这些研究的结果可用于未来的实验中，其中内源性NG 2细胞的命运可被操纵以最大化其对各种类型损伤中的损伤修复的贡献。

DESCRIPTION (provided by applicant): Glial cells in the mammalian central nervous system (CNS) that express the NG2 proteoglycan (NG2 cells) appear during late embryonic stages and rapidly expand to uniformly occupy the entire CNS. These cells are distinct from mature oligodendrocytes, astrocytes, or resting ramified microglia and represent a fourth major glial population. Cultured NG2 cells give rise to oligodendrocytes and are thus called oligodendrocyte precursor cells (OPCs). In vivo fate mapping studies using our newly generated NG2creBAC transgenic mice revealed that NG2 cells in the white matter and dorsal forebrain generate exclusively oligodendrocytes, while those in the gray matter of the ventral forebrain generate both oligodendrocytes and protoplasmic astrocytes. When the basic helix-loop-helix transcription factor Olig2 is deleted in NG2 cells, almost all the NG2 cells in the dorsal forebrain differentiate into astrocytes at the expense of oligodendrocytes, resulting in myelin loss. Thus, NG2 cells retain lineage plasticity, and a single transcription factor Olig2 plays a critical role in maintaining the oligodendroglial fate of NG2 cells. Deletion of Olig2 in more differentiated oligodendrocytes does not alter the level of neocortical GFAP expression, in contrast to Olig2 deletion at earlier stages, suggesting that there is a developmental window in which oligodendrocyte lineage cells can be converted into astrocytes in the absence of Olig2. Aim 1 will test the hypothesis that NG2 cells lose their lineage plasticity and become incapable of generating astrocytes as they mature into oligodendrocytes, and that restriction of lineage plasticity in NG2 cells is regulated by epigenetic mechanisms. Aim 2 will test the hypothesis that there is a signaling pathway that maintains the expression of Olig2 in NG2 cells in the normal brain and prevents them from differentiating into astrocytes. This will be explored by screening small-molecule libraries for a compound that alters Olig2 transcriptional activity. Identified compounds will be used in future studies to delineate the endogenous signaling pathways that regulate Olig2 expression. The pathway could then be manipulated in future injury repair paradigms to promote differentiation of NG2 cells into the desired cell type. PUBLIC HEALTH RELEVANCE: NG2 cells represent a glial progenitor population that is ubiquitously distributed throughout the gray and white matter of the central nervous system. The proposed studies are aimed to identify the mechanisms that regulate their lineage plasticity through the transcription factor Olig2. The results from these studies can be used in future experiments in which the fate of endogenous NG2 cells can be manipulated to maximize their contribution to lesion repair in various types injury.