Axonal degeneration and regeneration in a Zebrafish model of acute nerve injury

描述（由申请人提供）：急性神经损伤后最早的事件之一是轴突变性的活跃过程。尽管轴突变性和碎片清除被认为是成功的轴突再生的关键，但损伤轴突变性背后的细胞和分子机制尚不清楚。轴突变性也是遗传性神经病临床残疾的关键决定因素，在糖尿病患者中非常普遍。显然，缺乏功能性再生仍然是一个重要的临床问题，而且随着年龄的增长，这个问题更加突出。因此，对损伤和疾病引起的轴突变性的新治疗靶点的发展的核心是对潜在的分子触发和细胞过程的详细了解。这在一定程度上受到实时监测活体哺乳动物神经完整性、损伤和损伤进展等过程的能力有限的阻碍。利用激光轴切开术，我们建立了斑马鱼神经损伤模型，使我们能够在完整的活体动物中实时观察轴突退化过程中的细胞和亚细胞过程，不仅是在受伤的轴突中，而且在邻近的细胞类型中。本提案的目的是建立斑马鱼作为一种模式生物，以确定控制轴突退化和最终功能恢复的分子途径。本提案中的实验将：首先，确定斑马鱼轴突退化在多大程度上是由与高等脊椎动物相似的机制介导的。其次，确定影响轴突变性和再生的途径。长期目标是在细胞成像水平上确定受伤/切断的神经如何与它们的目标重新连接，确定它们重建功能回路的程度，并确定对神经再生重要的基因和因素。

DESCRIPTION (provided by applicant): One of the earliest events following acute nerve injury is the active process of axonal degeneration. Although axonal degeneration and debris removal are thought to be critical for successful axonal re-growth, the cellular and molecular mechanisms that underlie degeneration of injured axons are not well understood. Axonal degeneration is also a key determinant of clinical disability in hereditary neuropathies, and is highly prevalent in diabetic patients. Clearly, the lack of functional regeneration remains an important clinical problem, and is even more exuberated with age. Consequently, central to the development of novel therapeutic targets for injury and disease induced axonal degeneration is a detailed understanding of the underlying molecular triggers and cellular processes. This is in part hampered by the limited ability to monitor processes such as nerve integrity, injury and damage progression inside live mammalian animals in real time. Using laser axotomy we have established a nerve injury model in zebrafish, enabling us to visualize in real time in intact, live animals the cellular and subcellular processes during axonal degeneration, not only in injured axons but also in neighboring cell types. The objective of this proposal is to establish the zebrafish as a model organism in which to identify the molecular pathways controlling axonal degeneration, and eventually functional recovery. The experiments in this proposal will: First, determine the extent to which axonal degeneration in zebrafish is mediated by similar mechanisms as operate in higher vertebrates. Second, define pathways that impact axonal degeneration as well as regeneration. The long-term goals are to define on a cellular imaging level how injured/severed nerves reconnect with their targets, to determine the extent to which they reconstitute functional circuitries, and to identify genes and factors important for nerve regeneration. PUBLIC HEALTH RELEVANCE: Axonal degeneration is thought to be critical for successful axonal re-growth, yet the cellular and molecular mechanisms that underlie degeneration of injured axons are not well understood. Axonal degeneration and loss is also a key determinant of clinical disability in hereditary neuropathies. The objective of this proposal is to establish the zebrafish as a model organism in which to identify the molecular pathways controlling axonal degeneration, and eventually functional recovery.