COMPLEXITY OF IN VIVO AXON GUIDANCE

体内轴突引导的复杂性

• 批准号: 6126084
• 负责人: JEFFREY L DENBURG
• 金额: $ 28.19万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-04-01 至 2002-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6126084
• 关键词: Drosophilidae; antigens; basement membrane; blocking antibody; cockroach; complementary DNA; cues; developmental neurobiology; genetic library; growth cones; immunoprecipitation; innervation; laboratory mouse; laboratory rat; molecular cloning; monoclonal antibody; neural growth associated protein; neuroimmunomodulation; neuronal guidance; nonmammalian vertebrate embryology; nucleic acid sequence; polymerase chain reaction; protein purification; video microscopy

The long-term goal of this project is to learn how to manipulate axon growth in vivo. There are many instances when this would be an essential part of a therapeutic treatment after injury to the nervous system. In addition, the possible use of transplanted neurons to treat various CNS diseases may depend on these neurons sending axons to appropriate targets. The path growing axons follow during development is regulated by guidance mechanisms consisting of molecular cues that are non- uniformly distributed along the path. A particular role for gradients of attracting and repelling guidance cues has been proposed. A detailed understanding of how gradients of guidance cues direct the growth of axons is necessary to achieve this long-term goal. Recent progress has resulted in the identification and demonstration of in vivo function of 3 non-diffusible gradient molecules involved in the guidance of growth of the Til pioneer axons in the legs of the cockroach embryo. These molecules, localized to the substrate over which the axons grow, include 2 in the basement membrane and l on the surface of the epidermal epithelial cells. The complexity of the interactions between these guidance cues and the growth cone is greater than had been expected. This complexity is expressed in the fact that multiple and functionally redundant cues exist and in that these cues may interact with one another. The cockroach embryo is an ideal system in which to study the complexity of this developmental event. Its anatomical simplicity enables the proximal growth of identified pioneer axons in the leg to be observed in living preparations. In this proposal each of these cues will be molecularly characterized, the details of their ability to guide axon growth both in vivo and in vitro will be examined, as will be the in vivo interactions among them. A fourth molecule distributed in a gradient along the path of axon growth has been identified and experiments are proposed to examine its role in axon guidance. Like many developmental events, axon guidance is also likely to be phylogenetically conserved. The information obtained from studies of this insect are likely to be very relevant to understanding these processes in mammals.

该项目的长期目标是学习如何在体内操纵轴突生长。在许多情况下，这将是神经系统损伤后治疗的重要组成部分。此外，移植神经元治疗各种中枢神经系统疾病的可能用途可能取决于这些神经元将轴突发送到适当的目标。 发育过程中轴突生长所遵循的路径受到引导机制的调节，该引导机制由沿着路径不均匀分布的分子线索组成。已经提出了吸引和排斥引导线索的梯度的特殊作用。要实现这一长期目标，必须详细了解引导线索的梯度如何指导轴突的生长。最近的进展导致了 3 个非扩散梯度分子的体内功能的鉴定和演示，这些分子参与了蟑螂胚胎腿中 Til 先驱轴突生长的引导。这些分子位于轴突生长的基质上，其中 2 个位于基底膜中，1 个位于表皮上皮细胞表面。这些引导线索和生长锥之间相互作用的复杂性比预期的要大。 这种复杂性表现在以下事实：存在多个功能冗余的线索，并且这些线索可能彼此相互作用。蟑螂胚胎是研究这一发育事件复杂性的理想系统。 其解剖学简单性使得能够在活体制剂中观察到腿部中已识别的先驱轴突的近端生长。在该提议中，这些线索中的每一个都将被分子表征，它们在体内和体外引导轴突生长的能力的细节将被检查，以及它们之间的体内相互作用。已经确定了沿着轴突生长路径呈梯度分布的第四种分子，并提出了实验来检查其在轴突引导中的作用。与许多发育事件一样，轴突引导也可能在系统发育上是保守的。从这种昆虫的研究中获得的信息可能与理解哺乳动物的这些过程非常相关。