MOLECULAR BIOLOGY OF OCULOMOTOR SYSTEM DEVELOPMENT

描述（由申请人提供）：本研究的长期目标是了解脑干动眼病控制系统的核和电路的分子发育。本项目的重点是研究中脑动眼肌复合体（OMC）和后脑滑车核（TrN）中动眼肌神经元产生的调控机制。该实验将在鸡胚胎中进行，鸡胚胎具有电穿孔定向转基因的实验优势，并且与其他鸟类共享由具有不同眼外肌靶点的离散亚核组成的高度组织的OMC。第一组实验评估了同源结构域转录因子在指定动眼肌神经元身份和产生离散的OMC亚核中的作用。这些实验包括对CFEOM2候选基因PHOX2A功能的分子解剖。第二组实验研究了调节中脑祖细胞向动眼肌神经元命运的分子机制，重点研究了NKX6和基本螺旋-环-螺旋转录因子在这些过程中的作用。第三组实验是基于我们在TrN和OMC亚核中明显的转录因子异质性的发现。我们将研究这种异质性的解剖学相关性，重点关注这些分子分裂识别动眼植物中具有不同目标的运动神经元的具体假设。对OMC和TrN发育的调控机制的研究可能有助于了解动眼病系统的遗传疾病，尤其是像CFEOM这样特定的动眼病神经元池丢失的疾病。更一般地说，了解动眼肌细胞类型的独特分子特征可能会提出新的治疗策略，包括基于干细胞的方法，用于治疗动眼肌疾病，并可能深入了解动眼肌单元对某些运动神经元疾病的相对抗性。

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand the molecular development of the nuclei and circuitry of the brainstem oculomotor control system. The focus of this project is on the regulatory mechanisms underlying oculomotor neuron production in the midbrain oculomotor complex (OMC) and the hindbrain trochlear nucleus (TrN). The proposed experiments will be carried out in chick embryos, which have the experimental advantage of site-directed transgenesis by electroporation and which share with other birds a highly organized OMC composed of discrete subnuclei with distinct extraocular muscle targets. The first set of experiments assesses the roles of homeodomain transcription factors in specifying oculomotor neuron identity and generating discrete OMC subnuclei. These experiments include a molecular dissection of the function of the CFEOM2 candidate gene PHOX2A. The second set of experiments investigates the molecular mechanisms that regulate the specification of midbrain progenitor cells to an oculomotor neuron fate, with a focus on the roles of NKX6 and basic helix-loop-helix transcription factors in these processes. The third set of experiments is based on our findings of pronounced transcription factor heterogeneity within the TrN and OMC subnuclei. We will investigate the anatomical correlate of this heterogeneity, focusing on the specific hypothesis that these molecular divisions identify motor neurons with distinct targets in the oculomotor plant. Study of the mechanisms that govern OMC and TrN development may provide insight into genetic diseases of the oculomotor system, most notably those such as CFEOM in which specific pools of oculomotor neurons are lost. More generally, understanding of the unique molecular specification of oculomotor cell types may suggest novel therapeutic strategies, including stem cell-based approaches, for the treatment of oculomotor disorders, and may give insight to the relative resistance of the oculomotor unit to some motor neuron diseases.