MESENCHYME AND OLFACTORY SYSTEM MORPHOGENESIS

这项研究提案将确定，一个不同的亚群是否 小鼠额鼻间充质生长相关蛋白-43免疫反应鉴定 负责产生调节嗅觉的RA诱导信号 系统形态发生。在PAX-6突变小鼠中，嗅觉系统无法 GAP-43免疫反应间充质细胞亚群的形成 在突变的PAX-6小鼠额鼻间充质中缺失。 因此，这项研究将检验GAP-43的假设 免疫反应性间充质细胞是维甲酸的独特来源 导致嗅觉系统形态发生的感应信号。 这一假设将通过解决以下四个具体问题来检验 目标。 具体目的1.确定GAP-43免疫反应阳性细胞的位置 正常小鼠骨髓间充质细胞。这些实验将表明 GAP-43免疫反应阳性间充质细胞群定位充分 接近视黄醇反应的前脑区域以提供视黄醇 感应信号。 特异性目的2.确定GAP-43免疫反应阳性间充质 细胞产生类维甲酸信号。这些研究将确定来源或 额鼻间充质内视黄醇信号的来源及测定 它们与GAP-43免疫反应细胞群的关系。 具体目的3.评估GAP-43免疫反应的来源 额鼻间质间充质细胞。很可能是因为 小鼠额鼻间充质内GAP-43免疫反应细胞的来源 因为在发育过程中，脑脊细胞会从神经脊迁移 额鼻区(Matsuo et All.，1993)。因此，人口 额鼻间充质来源的神经脊将被识别 通过用识别额鼻间充质的抗体进行免疫染色 神经脊特异性抗原。 具体目标4.评估维甲酸的潜在异位部位 沿着TH神经脊向下丘脑的迁移路径产生 突变的PAX-6小鼠的额鼻区。由于PAX-6会影响迁移 额鼻间充质的神经脊(Matsuo et al.，1993)，这些 研究将确定GAP-43免疫反应人群 间充质细胞因神经脊异常而位于异位 PAX-6基因突变小鼠的迁移。 在小鼠胚胎中，额鼻间充质由马赛克组成。 细胞，包括大量迁移后的脑神经 Crest cell(Le Douarin，1983；1986；1993；Noden，1975；1988；Richman and Ttickle，1989；Serbedzija等人，1992)。因此，不同的亚群 腹外侧间充质可能起源于神经脊。特定的 目标1将定义这些间充质种群相对于 发展中的嗅觉系统。具体目标2将决定是否 GAP-43免疫阳性间充质细胞或任何其他抗原性细胞 不同的额鼻间充质亚群在 嗅觉系统开发。然后，特定目标3将进一步 通过检查来描述这种产生类维A酸间充质的种群 这些细胞是否具有神经脊细胞的抗原性 表明了他们的血统。由于突变的PAX-6动物表现出异常 神经脊线迁移与嗅觉发育障碍 如果迁移的神经脊细胞是类风湿关节炎信号的来源， 那么在突变体PAX-6中可能存在异位RA的产生部位 老鼠。因此，突变的PAX-6小鼠是一个很好的系统，在其中 检验这一假设。因此，这项工作可以定义一个明显的和瞬变的 用GAP-43免疫反应区分神经脊细胞的亚系 它充填了额鼻间充质，并专门生产 调节脊椎动物前脑的区域特异性感应信号 形态发生。

This research proposal will determine whether, a distinct subpopulation of frontonasal mesenchyme identified by GAP-43 immunoreactivity in the mouse, is responsible for producing RA-inductive signals that regulate olfactory system morphogenesis. In PAX-6 mutant mice the olfactory system fails to develop, and this sub-population of GAP-43 immunoreactive mesenchymal cells is absent from the mutant PAX-6 mouse's frontonasal mesenchyme. Accordingly this study will test the hypothesis that, the GAP-43 immunoreactive mesenchymal cells are a distinct source of retinoid inductive signals that lead to the morphogenesis of the olfactory system. This hypothesis will be tested by addressing the following four specific aims. Specific Aim 1. To determine the position of the GAP-43 immunoreactive mesenchymal cells in the normal mouse. These experiments will show whether the GAP-43 immunoreactive mesenchymal population is located sufficiently close to retinoid responsive forebrain regions to provide the retinoid inductive signals. Specific Aim 2. To determine whether the GAP-43 immunoreactive mesenchymal cells produce retinoid signals. These studies will identify the source or sources of retinoid signals in the frontonasal mesenchyme and determine their relationship to the GAP-43 immunoreactive population of cells. Specific Aim 3. To assess the origin of the GAP-43 immunoreactive mesenchymal cells of the frontonasal mesenchyme. It is likely that the GAP-43 immunoreactive cells in the mouse frontonasal mesenchyme are derived from the neural crest since during development cranial crest cells migrate tot he frontonasal region (Matsuo et all., 1993). Therefore, populations of frontonasal mesenchyme that are neural crest derived will be identified by immunostaining the frontonasal mesenchyme with antibodies that recognize neural crest specific antigens. Specific Aim 4. To assess potentially ectopic sites of retinoic acid production along the migratory pathway of th neural crest to the frontonasal region in mutant PAX-6 mice. Since PAX-6 influences migration of neural crest to the frontonasal mesenchyme (Matsuo et al., 1993), these studies will determine whether the population of GAP-43 immunoreactive mesenchymal cells is ectopically positioned due to aberrant neural crest migration in PAX-6 mutant mice. In the embryonic mouse, the frontonasal mesenchyme is made up of a mosaic of cells, including a large population of post-migratory cranial neural crest cells (Le Douarin, 1983; 1986; 1993; Noden, 1975; 1988; Richman and Tickle, 1989; Serbedzija et al., 1992). Therefore, distinct subpopulations of ventrolateral mesenchyme may be derived from the neural crest. Specific Aim 1 will define the location of these mesenchymal populations relative to the developing olfactory system. Specific Aim 2 will determine whether the GAP-43 immunoreactive mesenchymal cells or any of the other antigenically distinct subpopulations of frontonasal mesenchyme provide RA signals during olfactory system development. Specific Aim 3 will then further characterize this retinoid-producing population of mesenchyme, by examining whether these cells share antigenic properties of neural crest cells indicative of their lineage. Since mutant PAX-6 animals show aberrant migration of neural crest as well as failed development of their olfactory systems, if the migrating neural crest cells are the source of RA-signals, then sites of ectopic RA production would be expected in the mutant PAX-6 mice. Accordingly mutant PAX-6 mice are an excellent system in which to test this hypothesis. Thus this work may define a distinct and transient sub lineage of neural crest cells distinguished by GAP-43 immunoreactivity that populates the frontonasal mesenchyme and is specialized to produce region specific inductive signals that regulate vertebrate forebrain morphogenesis.