Role of RAGE signalling in peripheral nerve regeneration and in mediating the neurotrophic effects of the HNK-1 carbohydrate

虽然外周神经系统的再生通常不会像成年哺乳动物的中枢神经系统那样受到抑制，但由于靶向不完整或错误的问题，人类的神经修复往往不充分。股神经的优先运动神经再支配是我们研究运动神经元路径的准确性的范例，并揭示了运动轴突在股神经分叉的选择点处优先再生到正确的股神经分支的分子决定因素。我们建议通过扰动实验来研究成年小鼠的优先运动神经再支配，方法是测试晚期糖基化终产物受体(RAGE)的应用结果，RAGE是两性霉素的受体，继而与成年小鼠的HNK-1碳水化合物结合。这种碳水化合物和它的糖类化合物被我们证明有助于增强小鼠的优先运动神经再支配。我们还将测试RAGE基因缺陷的成年小鼠的再生能力。在Thy-1启动子的控制下，再生也将在表达显性-阴性RAGE的转基因小鼠中进行测试。由于脑源性神经营养因子及其同源受体参与了HNK-1碳水化合物表达的调节，因此我们将HNK-1拟糖体应用于这些突变小鼠受损的股神经，以期克服股神经切断后HNK-1表达上调的不足。这些联合实验应该会深入了解优先运动神经再支配的分子机制，希望将这些知识转化为对灵长类动物具有治疗价值的方法。

Although regeneration in the peripheral nervous system is not generally inhibited, as it is in the central nervous system of adult mammals, nerve repair in humans are often not adequate due to the problem of incomplete or faulty targeting. Preferential motor reinnervation of the femoral nerve has been paradigmatic in our studies on the accuracy of motoneuron pathfinding and uncovering the molecular determinants of this preferential regrowth of motor axons into the correct branch of the femoral nerve at the choice point where the femoral nerve bifurcates. We propose to investigate preferential motor reinnervation by perturbation experiments in adult mice by testing the outcome of application of the receptor for advanced glycation end products (RAGE), which is a receptor for amphoterin, which in turn binds to the HNK-1 carbohydrate in adult mice. This carbohydrate and its glycomimetic were shown by us to be instrumental in enhancing preferential motor reinnervation in the mouse. We will also test regeneration in adult mice that are genetically deficient in RAGE. Regeneration will also be tested in transgenic mice that express dominant-negative RAGE under the control of the Thy-1 promoter. Since the brain-derived neurotrophic factor and its cognate receptor are involved in regulation of HNK-1 carbohydrate expression, we will try to circumvent deficiency in HNK-1 upregulation after femoral nerve transection by applying the HNK-1 glycomimetic to the injured femoral nerve of these mutant mice. The combined experiments should yield insights into the molecular mechanisms of preferential motor reinnervation with the hope to translate this knowledge into a therapeutically valuable approach in primates.