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

• 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
• 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

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.

项目摘要 周围神经(PN)损伤后轴突再生往往不完全。目前还没有有效的 手术重建以外的治疗，这只对一小部分病例有益。 因此，了解修复机制至关重要。在这里，我们研究一个以前未知的函数 核心昼夜节律调节因子BMal1在PN损伤后门控神经再生反应中的作用这项研究是基于 根据我们的新数据，神经元特异性缺失BMal1可以加速PN损伤后轴突的再生。这 根据我们实验室在破译方面取得的一系列进展，有了令人兴奋的发现 控制神经元固有轴突生长潜力的转录网络，即转录因子如何 (TFS)与表观遗传因素合作重塑染色质景观，以诱导再生- 相关基因(RAG)。我们最新的工作利用了我们的DNA全基因组图谱 再生背根神经节神经元的羟甲基化(5hmC)动力学。有趣的是，我们 在PN损伤后表现为5hmC变化的基因组座位上发现了丰富的BMal1结合基序， 提示BMal1与5mC/5hmC转换酶Tet3相互作用。事实上，BMal1 CKO在小鼠中 显示BMal1-Tet3-5hmC轴调节与轴突生长、新陈代谢和免疫相关的基因 互动。此外，试点数据首次显示了DRG中Tet3和5hmC的昼夜表观遗传节律 对BMal1转录振荡是反相的神经元，对应于脑内不同时间的差异 再生反应。在这里，我们将检验BMal1作为轴突抑制因子的中心假设 通过调节5hmC重新编程，再生和损伤触发的免疫激活的守门人。在……里面 目的1，我们将表征BMal1门控的再生基因程序，并检测 中枢神经系统穿透有效的REV-Erb激动剂SR9009对BMal1转录的药理抑制作用 能力。从机制上讲，我们将测试一种“两击模型”，在该模型中，BMal1缺失启动了DRG神经元，但 损伤信号是RAGS诱导所必需的。在目标2中，我们将表征Tet3/5hmC表观遗传节律性， 与“轴突生长时钟”的相关性，以及通过测试工作模型的潜在机制 BMal1控制Tet3的表达以及Tet3向5hmC重编程靶基因的募集。我们会 然后绘制出PN损伤对BMal1-Tet3-5hmC节律性的短期和长期影响，以及这些 当轴突重新连接时，节律恢复正常。在目标3中，我们将重点放在体内促进作用的研究上。 BMal1抑制神经修复，包括运动感觉功能。我们还将解决可持续发展问题 效果，性别差异，以及在PN损伤后不久的时间BMal1抑制。总而言之，我们的建议具有 连接BMal1昼夜节律通路、Tet3/5hmC表观遗传重编程、损伤触发的可能性 免疫反应和轴突再生，从而促进了神经再生和开放的基础科学 翻译路径。