Development of Avian Extraocular Muscles and Nerves

鸟类眼外肌和神经的发育

• 批准号: 6831032
• 负责人: DREW M NODEN
• 金额: $ 44.09万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-24 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6831032
• 关键词: axon; biological signal transduction; chick embryo; developmental neurobiology; electroporation; extraocular muscle; eye movements; in situ hybridization; mesencephalon; myogenesis; neurogenesis; neuronal guidance; oculomotor nerve; optic nerve; rhombencephalon

DESCRIPTION (provided by applicant): Our long-term goal is to understand mechanisms directing the initiation and morphogenesis of the extra-ocular muscles and guiding appropriate motor axons to them, defects of which contribute to congenital oculomotor diseases such as Duane syndrome. Our hypothesis is that a consortium of positive and negative myogenic signals including highly localized signals from the brain (e.g., fgf8) act upon adjacent paraxial mesoderm cells. Our preliminary data show that altering signaling properties of the avian midbrain by ectopic expression of fgf8 disrupts development of the dorsal oblique (DO). We will screen for putative myogenic signals in the avian embryo, then test candidates by introducing signal agonists or antagonists into the midbrain (for DO induction) or hindbrain (for lateral rectus, LR, induction). This will be done using electroporation and infection with RCAS retroviral constructs. To examine the response capabilities of muscle primordia, trunk mesoderm infected with response blocking constructs, e.g. sprouty1, will be transplanted into infection-resistant strains of chick embryos in place of the normal LR primordium. Embryos are assayed for several markers of extra-ocular muscle differentiation, for changes in gene expression and neurogenesis in the brain, and for patterns of axon outgrowth. Cranial nerves In, IV, and VI arise in separate locations and each shows patterns of early outgrowth that are unique. Our hypothesis is that outgrowing abducens and oculomotor axons use different combinations of guidance systems, including growth factor-receptor pairs and members of the slit-robo, semaphorin-neuropilin, and ephrin-eph families. After screening for candidate guidance molecules, we will test for prespecification of motor axon properties by transplanting motor neuron precursors between sites of nerve III, VI, and XIII formation, then evaluate the roles of identified guidance molecules by creating changes in candidate gene expression in motor neurons using electroporation. Aim 3 exploits an avian model of the cross-innervation of the LR muscle by oculomotor axons that accompanies Duane syndrome. This is produced by a simple early lesion to the abducens primordium. Our hypothesis is that in the absence of the abducens nerve, there is an upregulation of neurorepellants and/or downregulation of neuroattractants within the LR that allows n. III ingrowth. We will screen for candidate molecules, especially HGF and GDNF, then test for their roles by overexpressing neurotrophic candidates into the LR primordium.

描述（由申请人提供）：我们的长期目标是了解指导眼外肌肉起始和形态发生的机制，并将适当的运动轴突引导到它们，这些缺陷有助于先天性眼动疾病，例如杜安综合症。我们的假设是，由正和负肌源性信号的联盟（包括大脑高度局部信号）（例如FGF8）作用于相邻的副中胚层细胞上。我们的初步数据表明，通过FGF8的异位表达改变禽中脑的信号传导特性会破坏背倾斜的发展（DO）。我们将在禽类胚胎中筛选假定的肌源信号，然后通过将信号激动剂或拮抗剂引入中脑（用于诱导）或后脑（用于侧直肠，LR，诱导）来测试候选。这将使用RCAS逆转录病毒构建体的电穿孔和感染来完成。为了检查肌肉原始的反应能力，躯干中胚层感染了反应阻断构建体，例如Sprouty1将被移植到鸡胚胎的抗感染菌株中，以代替正常的LR Primordium。测定胚胎的几种眼外肌肉分化，基因表达和变化的标记 大脑中的神经发生，以及轴突生长的模式。颅神经在，IV和VI中出现在不同的位置，每个位置都显示出独特的早期生长模式。我们的假设是，超越外套和眼动轴突使用了不同的指导系统组合，包括生长因子受体对，裂隙 - 摩托杆的成员，闪光蛋白 - 神经蛋白酶和ephrin-eph家族。在筛选候选引导分子后，我们将通过在神经III，VI和XIII形成的位点之间移植运动神经元前体进行预先指定的运动轴突特性，然后评估鉴定引导分子的作用，通过使用电动器进行电动机中的运动神经元中的候选神经元中的变化来评估识别指导分子的作用。 AIM 3利用了杜安综合症伴随的动眼轴突对LR肌肉交叉的鸟类模型。这是由简单的早期病变与外皮原始病变产生的。我们的假设是，在没有外表神经的情况下，神经循环剂的上调和/或LR内神经诱使剂的下调，允许n。 iii生长。我们将筛选候选分子，尤其是HGF和GDNF，然后通过过表达神经营养的候选者进入LR Primordium来测试它们的作用。