MOLECULAR BIOLOGY OF OCULOMOTOR SYSTEM DEVELOPMENT

描述(申请人提供)：这项研究的长期目标是了解脑干眼动控制系统的核和回路的分子发育。本项目的重点是研究中脑动眼神经复合体(OMC)和后脑滑车核(TRN)中动眼神经元产生的调节机制。拟议的实验将在鸡胚胎中进行，这种胚胎具有通过电穿孔进行定点转基因的实验优势，并且与其他鸟类共享一个高度组织的OMC，该OMC由离散的亚核组成，具有明显的眼外肌靶点。第一组实验评估同源结构域转录因子在指定动眼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对动眼神经细胞命运的指定的分子机制，重点是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亚核中显著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，重点放在特定的假设上，即这些分子分裂识别动眼植物中具有不同靶点的运动神经元。研究支配OMC和TRN发育的机制可能为了解动眼系统的遗传性疾病提供洞察力，最明显的是CFEOM，在这些疾病中，特定的动眼神经元池丢失。更广泛地说，了解动眼神经细胞类型的独特分子规范可能会为动眼神经疾病的治疗提供新的治疗策略，包括基于干细胞的方法，并可能深入了解动眼神经单位对某些运动神经元疾病的相对抵抗力。

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.