OLIGODENDROCYTE LINEAGE GENE FUNCTION IN THE CNS

在初步研究中，我们克隆并鉴定了一对少突胶质细胞系基因(OLG)，它们编码一类新的bHLH蛋白。人OLG-1和OLG-2在唐氏综合征关键区共定位于50kb以内。OLG基因仅在啮齿类动物的中枢神经系统(CNS)中表达。OLG的表达与已知的最早的少突胶质细胞发育标志物重叠，但先于这些标志物。此外，在细胞培养中，病毒介导的0LG-1异位表达引导多潜能皮质祖细胞表达少突胶质细胞系的早期标志。这里描述的研究建立在这项工作的基础上。我们有四个特定的目标：目标1是确定0LG基因的表达是否足以启动动物少突胶质细胞的形成。我们将使用双基因系统在转基因小鼠的神经管发育中实现野生型和突变型0LG基因的条件表达。目的2确定OLG基因表达是否对少突胶质细胞的发育是必需的。我们将使用一种稍微不寻常的方法来生成0LG-1和0LG-2的经典敲除。我们将通过分别定向插入LacZ和Cre重组酶基因来干扰这些基因。即使在0LG基因敲除中没有可识别的表型，我们以这种方式创造的小鼠品系也将对额外的实验有用(参见下面的特定目标3)。目的3是确定0LG基因是否只在少突胶质细胞的形成中起作用。我们将通过将0LG/Cre基因敲除小鼠(AIM 2)与条件报告小鼠品系交配来描绘表达0LG基因的神经前体细胞的长期命运。目的4确定0LG基因产物在多能神经前体细胞中的分子功能。我们将专注于转录调控中的角色，并描述功能活动所需的结构特征。从这些研究得出的对0LG基因功能的洞察可能会影响涉及中枢神经系统髓鞘产生细胞的广泛疾病状态。特别是，这项工作可能会阐明神经胶质瘤的分子表型，并指出可能的新疗法。

In preliminary studies, we have cloned and characterized a pair of Oligodendrocyte lineage genes (Olg) that encode a novel class of bHLH proteins. Human OLG-1 and OLG-2 co-localize within 50 kb of each other n the Down's Syndrome critical region. Olg genes are expressed exclusively within the central nervous system (CNS) of rodents. Olg expression overlaps, but precedes, the earliest known markers of oligodendrocyte development. Moreover, in cell culture, virus-mediated ectopic expression of 0lg-1 directs multipotent cortical progenitor cells to express early markers of the oligodendroycte lineage. The studies described here build upon this work. We have four specific aims: Aim 1 is to determine whether 0lg gene expression is sufficient to initiate the formation of oligodendrocytes in animals. We will use a bigenic system to achieve conditional expression of wild type and mutated 0lg genes in developing neural tube of transgenic mice. Aim 2 is to determine whether Olg gene expression is necessary for oligodendrocyte development. We will use a slightly unusual method to generate classical knockouts of of 0lg-1 and 0lg-2. We will disrupt the genes by targeted insertion of lacZ and Cre recombinase genes, respectively. The mouse strains that we create in this way will be useful for additional experiments (see specific aim 3 below) even if there is no discernable phenotype in the 0lg knockouts. Aim 3 is to determine whether 0lg genes function exclusively in formation of oligodendrocytes. We will map the long-term fate of neural progenitor cells that have expressed 0lg genes by mating the 0lg/Cre knockout mice (Aim 2) to a "Floxed" betageo conditional reporter mouse strain. Aim 4 is to define the molecular functions of 0lg gene products within multipotent neural progenitor cells. We will focus on roles in transcriptional regulation and characterize structural features required for functional activity. Insights into 0lg gene functions derived from these studies could impact a broad range of disease states involving myelin-producing cells of the CNS. In particular, the work may shed light on the molecular phenotype of glial tumors and point to possible new therapies.