PRECISELY CONTROLLED GRADIENTS FOR AXON GUIDANCE

精确控制轴突引导的梯度

• 批准号: 6028296
• 负责人: GEOFFREY J GOODHILL
• 金额: $ 11.38万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2002-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6028296
• 关键词: chemotaxis; collagen; cues; gel; growth cones; laboratory rat; nerve growth factors; neuronal guidance; printing; technology /technique development

DESCRIPTION (Verbatim from the Applicant's Abstract): As the brain develops, axons often grow over long distances to find appropriate targets. Some of the most important guidance cues they use to achieve this feat are concentration gradients of chemotropic molecules. These gradients are detected by the growth cone, a complex and sensitive structure at the tip of the developing axon. Understanding how growth cones detect gradients is crucial for understanding how the brain normally develops, how defects in normal wiring can occur, and how axons can appropriately regenerate after injury. However, there is currently very little quantitative information about how growth cones respond to gradients. This is primarily due to the absence of an experimental technique for establishing gradients of diffusible axon guidance molecules in vitro, such that the shape and steepness of the gradient is under the control of the experimenter. Without such a technique it is impossible to systematically vary the parameters of the gradient, and thus impossible to determine quantitatively how each of these parameters regulates axon guidance. The goal of this project is to develop and implement a novel technique to make these measurements possible. We will establish gradients by "printing" chemotropic molecules onto the surface of a long, thin block of collagen gel in which axons are growing, and allowing the molecules to diffuse into the collagen. Precisely controlled volumes of chemotropic factor can be deposited at precisely controlled locations using a method similar to that employed in inkjet printers. Because molecular movement by diffusion is fast over short distances but slow over long distances, initial local unevenness in the concentration smoothes out in a few hours, leaving behind a gradient that remains smooth and stable for several weeks. We thus have complete control over the shape of this gradient via control over the pattern of molecules deposited on the surface. By observing axon growth and turning behavior in these gradients we will obtain quantitative data of unprecedented precision on the parameters controlling axon guidance by diffusible gradients. Our initial model system will be the guidance of rat dorsal root ganglion axons by gradients of Nerve Growth Factor. However, we expect this technology to be also widely applicable to other model systems for axon guidance, and more generally to studies of cell motility and chemotaxis.

描述（逐字摘自申请人摘要）：随着大脑的发育， 轴突通常会长距离生长以找到合适的目标。一些 他们用来实现这一壮举的最重要的指导线索是注意力 趋化分子的梯度。这些梯度是通过生长检测到的 锥体，位于发育中的轴突尖端的复杂而敏感的结构。 了解生长锥如何检测梯度对于理解至关重要 大脑如何正常发育，正常线路的缺陷如何发生，以及 轴突在受伤后如何适当再生。然而，有 目前关于生长锥如何反应的定量信息很少 到渐变。这主要是由于缺乏实验技术造成的 用于在体外建立可扩散轴突引导分子的梯度，例如 梯度的形状和陡度受控制 实验者。如果没有这样的技术，就不可能系统地改变 梯度的参数，因此无法定量确定 这些参数中的每一个如何调节轴突引导。该项目的目标 是开发和实施一种新技术来进行这些测量 可能的。 我们将通过将趋化分子“打印”到 长而薄的胶原蛋白凝胶块的表面，轴突在其中生长，以及 让分子扩散到胶原蛋白中。精确控制 趋化因子的体积可以在精确控制的条件下沉积 使用与喷墨打印机中使用的方法类似的方法来定位位置。因为 通过扩散进行的分子运动在短距离内速度很快，但在长距离内移动速度较慢 随着距离的增加，最初的局部浓度不均匀性会在几个小时内变得平滑 小时，留下一个在几个小时内保持平滑和稳定的梯度 几周。因此，我们可以通过以下方式完全控制该渐变的形状 控制沉积在表面的分子模式。通过观察 这些梯度中的轴突生长和转动行为我们将获得定量 控制轴突引导的参数具有前所未有的精度数据 可扩散梯度。我们最初的模型系统将是老鼠的指导 通过神经生长因子的梯度观察背根神经节轴突。然而，我们 预计该技术也能广泛应用于其他模型系统 轴突引导，更广泛地用于细胞运动和趋化性的研究。