Improving olfactory neuroplasticity through FAK/CNTF signaling

项目摘要 嗅上皮（olfactory epithelium，OE）中的嗅感觉神经元（olfactory sensory neurons，OSNs）由基底干不断更新 细胞并将它们的轴突生长到嗅球以维持嗅觉。未能重组运行经验 在受伤、感染或老化之后，引起嗅觉功能障碍，这是一个安全和生活质量问题。没有 治疗是可用的。确定调节嗅觉神经可塑性的信号将揭示新的 治疗目标，以改善嗅觉缺陷。睫状神经营养因子（CNTF）在哺乳动物中高度表达， 水平基底细胞（HBCs）和嗅鞘细胞（OECs），而CNTFR α受体表达 在邻近的神经元祖细胞球状基底细胞（GBC）。我们发现CNTF被抑制， 粘着斑激酶（FAK）和FAK抑制剂鼻内应用促进OE神经发生， CNTF。重要的是，FAK抑制剂进一步增强由甲巯咪唑引起的OE损伤引起的CNTF表达。 我们将在雄性和雌性小鼠中使用遗传学、药理学和行为学方法来测试 FAK抑制通过增加CNTF促进损伤后嗅觉神经可塑性假说 表情目的1将通过以下方法确定GBC增殖的FAK-CNTF-CNTFR α通路 确定FAK抑制是否在HBC、OEC或两者中诱导CNTF。我们还将确定 CNTF的释放激活CNTFR α信号在刺激GBC增殖中的作用， 通过这种细胞间机制起作用。为了增加我们的研究结果的相关性，目标2将确定 FAK抑制是否能增加急性OE损伤后通过CNTF的嗅觉神经发生。因此，我们将 使用甲巯咪唑急性损伤，并确定损伤是否增加HBC和/或OEC中的CNTF， 导致GBC增殖和神经发生增加。FAK抑制剂治疗在以下情况下的作用 甲巯咪唑可能存在于HBC和/或OEC中，我们将进行测试。为了准备进一步的研究，我们 将确定FAK抑制剂的最佳剂量，然后测试CNTF是否介导FAK抑制剂的作用， 促进急性损伤后OE神经发生。慢性嗅觉炎症抑制HBC增殖， 增加HBC中的FAK信号，表明CNTF可能被抑制。扩大与以下方面的相关性： 更多类型的嗅觉损伤，Aim3将使用改良的慢性嗅觉炎症小鼠模型， 确定FAK抑制是否增加CNTF并促进GBC增殖和嗅觉 神经发生目的4研究抑制FAK对OSN轴突生长和嗅觉功能的影响 急性和慢性OE损伤后的功能恢复，使用遗传轴突示踪方法结合 行为测试。这一建议将明确FAK和CNTF的作用，并验证其治疗潜力 FAK抑制剂，以改善损伤后的嗅觉功能。FAK抑制剂在癌症临床中耐受良好 试验和鼻内给药避免了全身副作用。

Project Summary Olfactory sensory neurons (OSNs) in the olfactory epithelium (OE) are continuously replaced from basal stem cells and grow their axons to the olfactory bulb to maintain the sense of smell. Failure to reconstitute the OE after injury, infection or aging, causes olfactory dysfunction which is a safety and a quality of life issue. No treatments are available. Defining the signals that regulate olfactory neuroplasticity would reveal new therapeutic targets to improve olfactory deficits. Ciliary neurotrophic factor (CNTF) is highly expressed in horizontal basal cells (HBCs) and olfactory ensheathing cells (OECs), while the CNTFRα receptor is expressed in the neighboring neuronal progenitor globose basal cells (GBCs). We found that CNTF is suppressed by focal adhesion kinase (FAK) and that intranasal application of an FAK inhibitor promotes OE neurogenesis via CNTF. Importantly, FAK inhibitor further enhances CNTF expression caused by OE injury with methimazole. We will use genetic, pharmacological, and behavioral approaches in male and female mice to test the hypothesis that FAK inhibition promotes olfactory neuroplasticity following injury by increasing CNTF expression. Aim 1 will define the FAK-CNTF-CNTFRα pathway underlying GBC proliferation by first determining whether FAK inhibition induces CNTF in HBCs, OECs or both. We will also determine whether CNTF is released to activate CNTFRα signaling in stimulating GBC proliferation, and whether FAK inhibition acts through this intercellular mechanism. To increase the relevance of our findings, Aim 2 will determine whether FAK inhibition can increase olfactory neurogenesis via CNTF following acute OE injury. Thus, we will use acute injury with methimazole and determine whether injury increases CNTF in HBCs and/or OECs which leads to increased GBC proliferation and neurogenesis. The effect of FAK inhibitor treatment following methimazole may be within HBCs and/or OECs, something we will test. To prepare for additional studies, we will define an optimal dose of FAK inhibitor and then test whether CNTF mediates the effect of FAK inhibitor to promote OE neurogenesis after acute injury. Chronic olfactory inflammation inhibits HBC proliferation and increases FAK signaling in HBCs, suggesting that CNTF might be suppressed. To broaden the relevance to more types of olfactory injuries, Aim 3 will use a refined chronic olfactory inflammation mouse model to determine whether FAK inhibition increases CNTF and promotes GBC proliferation and olfactory neurogenesis. Aim 4 will determine the ability of FAK inhibition to promote OSN axonal growth and olfactory function recovery following acute and chronic types of OE injury, using genetic axon tracing methods combined with behavioral tests. This proposal will define the role of FAK and CNTF and validate the therapeutic potential of FAK inhibitors to improve olfactory function after injury. FAK inhibitors are well-tolerated in cancer clinical trials and intranasal administration avoids systemic side effects.