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

描述(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。虽然轴突退变和碎片清除被认为是轴突成功再生的关键，但损伤轴突退变的细胞和分子机制尚不清楚。轴突变性也是遗传性神经病变中临床残疾的关键决定因素，在糖尿病患者中非常常见。显然，缺乏功能再生仍然是一个重要的临床问题，而且随着年龄的增长甚至更加旺盛。因此，对于损伤和疾病引起的轴突变性的新的治疗靶点的开发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了实时监测活体哺乳动物体内神经完整性、损伤和损伤进展等过程的有限能力的阻碍。利用激光切断术，我们建立了斑马鱼的神经损伤模型，使我们能够在完整的活动物身上实时观察轴突变性过程中的细胞和亚细胞过程，不仅是在受损的轴突中，而且在邻近的细胞类型中也是如此。这项建议的目的是建立斑马鱼作为模式生物，在其中识别控制轴突退化的分子途径，并最终实现功能恢复。这项提议中的实验将：首先，确定斑马鱼的轴突退化在多大程度上受到与高等脊椎动物相似的机制的调节。第二，定义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/切断的神经如何与其靶点重新连接，确定它们重建功能回路的程度，并确定对神经再生至关重要的基因和因素。 公共卫生相关性：轴突变性被认为是轴突成功再生的关键，但损伤轴突变性背后的细胞和分子机制尚不清楚。轴突变性和丢失也是遗传性神经病临床残疾的关键决定因素。这项建议的目的是建立斑马鱼作为模式生物，在其中识别控制轴突退化的分子途径，并最终实现功能恢复。

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.