The role of core circadian regulator Bmal1 in axonal regeneration and nerve repair

核心昼夜节律调节因子 Bmal1 在轴突再生和神经修复中的作用

基本信息

批准号：
10677932
负责人：
Hongyan Zou
金额：
$ 57.59万
依托单位：
ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-03-15 至 2028-02-29
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10677932
关键词：
ARNTL gene Acceleration Address Affect Afferent Neurons Agonist Axon Axotomy Basic Science Binding Bioinformatics Biological Assay Brain-Derived Neurotrophic Factor Chromatin Clinical Cohort Studies Collaborations DNA mapping Data Enzymes Epigenetic Process Exhibits Gatekeeping Genes Genetic Genetic Transcription Hour Immune Immune response Immunologics In Vitro Injury Investigation Knockout Mice Laboratories Link Maps Mediating Metabolism Modeling Molecular Mus Natural regeneration Nerve Regeneration Neurites Neuroimmune Neurons Output Pathway interactions Penetration Periodicity Peripheral Peripheral nerve injury Phase Phenotype Pilot Projects Process Reconstructive Surgical Procedures Regenerative response Regulation Reporting Rest Role Series Sex Differences Shapes Signal Transduction Spinal Ganglia Testing Time Work axon growth axon injury axon regeneration beta catenin cell type circadian circadian biology circadian pacemaker comparative efficacy conditional knockout design effective therapy efficacy evaluation gene induction genome-wide genomic locus immune activation in vivo inhibitor insight nerve injury nerve repair neural novel pharmacologic programs recruit regenerative repaired response sciatic nerve injury sex transcription factor transcriptomics

项目摘要

Project Summary Axon regeneration after peripheral nerve (PN) injury is often incomplete. There is currently no effective treatment beyond surgical reconstruction, which is only beneficial for a small percentage of cases. Understanding the repair mechanisms is thus crucial. Here, we investigate a previously unknown function of the core circadian regulator Bmal1 in gating neuroregenerative responses after PN injury. The study is based on our new data that neuron-specific deletion of Bmal1 accelerates axon regeneration after PN injury. This exciting finding was made in the context of a series of advances from our laboratory in deciphering transcriptional networks that control neuronal intrinsic axon growth potential, i.e., how transcription factors (TFs) cooperate with epigenetic factors to reshape the chromatin landscape for induction of regeneration- associated genes (RAGs). Our most recent work has leveraged our genome-wide mapping of DNA hydroxymethylation (5hmC) dynamics in regenerating dorsal root ganglia (DRG) neurons. Intriguingly, we discovered enrichment of the Bmal1 binding motifs in genomic loci displaying 5hmC changes after PN injury, suggesting an interaction of Bmal1 with the 5mC/5hmC converting enzyme Tet3. Indeed, Bmal1 cKO in mice showed that the Bmal1-Tet3-5hmC axis regulates genes linked to axon growth, metabolism, and immune interactions. Moreover, pilot data show for the first-time a diurnal epigenetic rhythm of Tet3 and 5hmC in DRG neurons that is anti-phasic to Bmal1 transcriptional oscillation and corresponds to time-of-day differences in regenerative responses. Here, we will test the central hypothesis that Bmal1 functions as an inhibitor of axon regeneration and a gatekeeper of injury-trigged immune activation via regulation of 5hmC reprogramming. In Aim 1, we will characterize Bmal1-gated regenerative gene programs and examine the effect of pharmacological inhibition of Bmal1 transcription by SR9009, a potent Rev-Erb agonist with CNS penetration capability. Mechanistically, we will test a “two-hit model” wherein Bmal1 deletion primes DRG neurons, but an injury signal is required for RAGs induction. In Aim 2, we will characterize Tet3/5hmC epigenetic rhythmicity, correlation with “neurite outgrowth clock”, and the underlying mechanisms by testing the working model that Bmal1 controls Tet3 expression as well as Tet3 recruitment to target loci for 5hmC reprogramming. We will then map short- and long-term impact of PN injury on Bmal1-Tet3-5hmC rhythmicity and whether these rhythms return to normal upon axonal reconnection. In Aim 3, we pivot to in vivo study of the promoting effect of Bmal1 inhibition on nerve repair, including motosensory functions. We will also address sustainability of the effect, sex differences, and timed Bmal1 inhibition shortly after PN injury. In sum, our proposal has the potential of connecting Bmal1 circadian pathway, Tet3/5hmC epigenetic reprogramming, injury-triggered immune responses, and axon regeneration, thus advancing basic science of nerve regeneration and opening translational paths.

项目概要周围神经（PN）损伤后的轴突再生往往不完全，目前尚无有效的方法。手术重建以外的治疗方法仅对一小部分病例有益。因此，了解修复机制至关重要。在这里，我们研究了以前未知的功能。该研究基于核心昼夜节律调节因子 Bmal1 控制 PN 损伤后的神经再生反应。根据我们的新数据，神经元特异性删除 Bmal1 可加速 PN 损伤后的轴突再生。我们实验室在破译方面取得了一系列进展，取得了令人兴奋的发现控制神经内在轴突生长潜力的转录网络，即转录因子如何（TF）与表观遗传因子合作重塑染色质景观以诱导再生- 我们最近的工作利用了全基因组 DNA 作图。有趣的是，我们研究了背根神经节（DRG）神经元再生中的羟甲基化（5hmC）动态。发现 PN 损伤后显示 5hmC 变化的基因组位点中 Bmal1 结合基序的富集，表明 Bmal1 与 5mC/5hmC 转换酶 Tet3 存在相互作用。事实上，Bmal1 在小鼠体内被 cKO。研究表明 Bmal1-Tet3-5hmC 轴调节与轴突生长、代谢和免疫相关的基因此外，试验数据首次显示 DRG 中 Tet3 和 5hmC 的昼夜表观遗传节律。与 Bmal1 转录振荡反相的神经元，对应于一天中时间差异在这里，我们将测试 Bmal1 作为轴突抑制剂的中心假设。通过调节 5hmC In 重编程来实现再生和损伤触发免疫激活的看门人。目标 1，我们将描述 Bmal1 门控再生基因程序的特征并检查其效果 SR9009（一种具有中枢神经系统渗透性的强效 Rev-Erb 激动剂）对 Bmal1 转录的药理学抑制从机制上讲，我们将测试 Bmal1 删除启动 DRG 神经元的“两次打击模型”，但 RAG 诱导需要损伤信号。在目标 2 中，我们将表征 Tet3/5hmC 表观遗传节律性。与“神经突生长时钟”的相关性，以及通过测试工作模型的潜在机制 Bmal1 控制 Tet3 表达以及 Tet3 招募到 5hmC 重编程的目标位点。然后绘制 PN 损伤对 Bmal1-Tet3-5hmC 节律性的短期和长期影响，以及这些影响是否在轴突重新连接后节律恢复正常在目标 3 中，我们转向促进作用的体内研究。 Bmal1 抑制对神经修复（包括运动感觉功能）的影响我们还将解决神经修复的可持续性问题。效果、性别差异和 PN 损伤后不久的定时 Bmal1 抑制总而言之，我们的建议有：连接 Bmal1 昼夜节律通路的潜力、Tet3/5hmC 表观遗传重编程、损伤触发免疫反应和轴突再生，从而推进神经再生和开放的基础科学翻译路径。