OLIGODENDROCYTE LINEAGE GENE FUNCTION IN THE CNS

在初步研究中，我们克隆并鉴定了一对编码一类新的bHLH蛋白的少突胶质细胞谱系基因（Olg）。人类的OLG-1和OLG-2在唐氏综合症关键区域共定位在50 kb以内。Olg基因仅在啮齿动物的中枢神经系统（CNS）中表达。Olg表达重叠，但先于已知的少突胶质细胞发育的最早标记。此外，在细胞培养中，病毒介导的0lg-1异位表达指导多能皮质祖细胞表达少突细胞谱系的早期标记物。这里描述的研究建立在这项工作的基础上。我们有四个具体目的：目的一是确定0lg基因表达是否足以启动动物少突胶质细胞的形成。我们将利用双基因系统实现野生型和突变型0lg基因在转基因小鼠神经管发育中的条件表达。目的2是确定Olg基因表达在少突胶质细胞发育中是否必要。我们将使用一种稍微不同寻常的方法来生成0lg1和0lg2的经典敲除。我们将分别通过靶向插入lacZ和Cre重组酶基因来破坏这些基因。我们以这种方式创建的小鼠品系将对其他实验有用（参见下面的具体目标3），即使在0lg敲除中没有可识别的表型。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敲除小鼠（Aim 2）与“Floxed”betageo条件报告小鼠株交配，来绘制表达0lg基因的神经祖细胞的长期命运。目的4：明确0lg基因产物在多能神经祖细胞中的分子功能。我们将重点关注转录调控中的角色，并描述功能活动所需的结构特征。从这些研究中获得的对0lg基因功能的见解可能影响涉及中枢神经系统髓磷脂产生细胞的广泛疾病状态。特别是，这项工作可能会揭示神经胶质肿瘤的分子表型，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.