Engaging neuron-intrinsic signaling for axon growth after spinal cord injury

脊髓损伤后轴突生长的神经元内在信号传导

• 批准号: 10213845
• 负责人: Jian Zhong
• 金额: $ 61.19万
• 依托单位: WINIFRED MASTERSON BURKE MED RES INST
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-15 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10213845
• 关键词: 1-Phosphatidylinositol 3-Kinase; Address; Animal Model; Axon; Back; Behavioral Assay; Brain; Cells; Clinic; Competence; Contralateral; Corticospinal Tracts; Data; Development; Dorsal; Enterobacteria phage P1 Cre recombinase; Frequencies; Genetic; Genetic Recombination; Goals; Growth; Image; Injury; Interneurons; Intervention; Knowledge; Label; Lectin; Left; Lesion; MAP2K1 gene; MEKs; Measures; Microscopy; Mission; Mitogen-Activated Protein Kinases; Modeling; Monitor; Motor Neurons; Mus; Natural regeneration; Neuronal Injury; Neurons; Optic Nerve; PTEN gene; Paralysed; Pathway interactions; Peripheral; Photons; Pilot Projects; Process; Proteins; Public Health; Recovery of Function; Reporter; Research; Role; Signal Transduction; Site; Spinal; Spinal Cord; Spinal cord injury; Spinal cord injury patients; Synapses; Tamoxifen; Techniques; Testing; Time; Tracer; Translating; United States National Institutes of Health; Wild Type Mouse; Work; axon growth; axon regeneration; axonal sprouting; base; central nervous system injury; clinical application; curative treatments; fetal; gain of function; in vivo; injured; innovation; insight; loss of function; motor function recovery; mouse model; neurotransmission; novel; postsynaptic; postsynaptic neurons; preclinical study; regenerative; regenerative growth; repaired; repetitive transcranial magnetic stimulation; spinal nerve posterior root; synaptic function; synaptogenesis; transcription factor; treatment strategy

For victims of spinal cord injury (SCI) to recover motor function, large numbers of damaged corticospinal tract (CST) axons would need to regenerate and re-connect with spinal inter- and motor neurons. However, axons do not regenerate in the mature injured spinal cord. Decades of research into this problem have yielded much insight into the mechanisms of axon growth and reasons why they fail in the SCI context, but no strategies enabling long-range axon regeneration have emerged, much less new treatments for SCI. To address this unmet need, my lab focuses on ways to re- activate in mature injured CNS neurons the intracellular axon growth signaling mechanisms that are active in developing neurons. The long-term goal of our research is to enable long-range axon regeneration and the re-establishment of functional circuitry in the injured spinal cord. We have recently observed that activation of RAF – MEK signaling in cortical motor neurons enables substantial regenerative growth of injured CST axons in genetically modified mice. We observed similar effects in wild type mice treated with repetitive transcranial stimulation (rTMS). The overall objective of this application is to thoroughly explore the extent of axon regenerative growth and synaptic re-connection that can be achieved by elevation of RAF – MEK signaling, or by rTMS. We plan to pursue the following three Specific Aims: First, to determine how much CST axon regeneration or sprouting can be stimulated in genetically modified B-RAF gain-of function mice subjected to three different established models of SCI. Second, we have generated a novel anterograde transsynaptic tracer by fusing the lectin WGA with the inducible Cre recombinase CreERT2. Upon activation by tamoxifen, this tracer triggers the expression of a protein of choice in postsynaptic neurons in a reporter mouse. We here plan to express the tracer in cortical motor neurons, to induce expression of a genetically encoded fluorescent Ca2+ indicator in their postsynaptic neurons. This will allow us to label new synapses formed by newly sprouting CST axons, and also to demonstrate their functional activity as reflected in Ca2+ transients. Finally, we plan to explore the power of rTMS to enable CST axon regeneration in wild type mice. Initial data indicate that the level of MEK activity correlates with rTMS-dependent CST axon regeneration. Therefore, we will use MEK1/2 conditional loss-of-function mice to test whether MEK activation is crucial for rTMS- dependent regeneration. The proposed study is innovative, as it takes advantage of new technical approaches (rTMS and the CreERT2WGA fusion tracer) to address the problem of long-range axon regeneration in the spinal cord. This research is also significant because it tests new concepts and strategies that may eventually contribute to axonal repair and functional recovery in SCI patients.

为了让脊髓损伤（SCI）的受害者恢复运动功能，大量受损的 皮质脊髓束（CST）轴突需要再生并与脊髓间轴和运动轴突重新连接 神经元。然而，轴突在成熟的受损脊髓中不会再生。数十年的研究 对这个问题的研究使我们对轴突生长的机制及其原因有了深入的了解 他们在 SCI 背景下失败了，但还没有出现能够实现远程轴突再生的策略， 更不用说针对 SCI 的新疗法了。为了解决这一未满足的需求，我的实验室重点研究如何重新 激活成熟受损中枢神经系统神经元的细胞内轴突生长信号机制 神经元发育活跃。我们研究的长期目标是实现远程轴突 受损脊髓的再生和功能回路的重建。我们有 最近观察到，皮质运动神经元中 RAF-MEK 信号的激活使得 转基因小鼠中受损的 CST 轴突显着再生生长。我们观察到 在接受重复经颅刺激（rTMS）治疗的野生型小鼠中也有类似的效果。整体 该应用的目的是彻底探索轴突再生生长的程度和 突触重新连接可以通过增强 RAF-MEK 信号传导或 rTMS 来实现。我们 计划追求以下三个具体目标： 第一，确定 CST 轴突的数量 转基因 B-RAF 功能获得性小鼠的再生或发芽可以得到刺激 受三种不同的已建立的 SCI 模型的影响。其次，我们生成了一本小说 通过将凝集素 WGA 与诱导型 Cre 重组酶融合来构建顺行突触示踪剂 CreERT2。被他莫昔芬激活后，该示踪剂会触发所选蛋白质的表达 报告小鼠的突触后神经元。我们这里计划在皮质运动中表达示踪剂 神经元，诱导其基因编码的荧光 Ca2+ 指示剂的表达 突触后神经元。这将使我们能够标记新萌芽的 CST 形成的新突触 轴突，并展示其功能活动（如 Ca2+ 瞬变所反映）。最后，我们计划 探索 rTMS 使野生型小鼠 CST 轴突再生的能力。初始数据表明 MEK 活性水平与 rTMS 依赖性 CST 轴突再生相关。因此，我们 将使用 MEK1/2 条件性功能丧失小鼠来测试 MEK 激活是否对 rTMS 至关重要- 依赖性再生。拟议的研究具有创新性，因为它利用了新技术 解决长程轴突问题的方法（rTMS 和 CreERT2WGA 融合示踪剂） 脊髓的再生。这项研究也很重要，因为它测试了新概念 最终可能有助于 SCI 患者轴突修复和功能恢复的策略。

项目成果

Co-targeting B-RAF and PTEN Enables Sensory Axons to Regenerate Across and Beyond the Spinal Cord Injury.

• DOI: 10.3389/fnmol.2022.891463
• 发表时间: 2022
• 期刊: FRONTIERS IN MOLECULAR NEUROSCIENCE
• 影响因子: 4.8
• 作者: Noristani, Harun N.;Kim, Hyukmin;Pang, Shuhuan;Zhong, Jian;Son, Young-Jin
• 通讯作者: Son, Young-Jin

FGF-induced Pea3 transcription factors program the genetic landscape for cell fate determination.

• DOI: 10.1371/journal.pgen.1007660
• 发表时间: 2018-09
• 期刊: PLoS genetics
• 影响因子: 4.5
• 作者: Garg A;Hannan A;Wang Q;Collins T;Teng S;Bansal M;Zhong J;Xu K;Zhang X
• 通讯作者: Zhang X

Alx4 relays sequential FGF signaling to induce lacrimal gland morphogenesis.

• DOI: 10.1371/journal.pgen.1007047
• 发表时间: 2017-10
• 期刊: PLoS genetics
• 影响因子: 4.5
• 作者: Garg A;Bansal M;Gotoh N;Feng GS;Zhong J;Wang F;Kariminejad A;Brooks S;Zhang X
• 通讯作者: Zhang X