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）损伤后的轴突再生通常不完整。目前没有效力 除手术重建以外的治疗，这仅对少量病例有益。 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 PN损伤后，核心昼夜节律调节剂BMAL1在门控神经收益反应中。该研究是基于 在我们的新数据中，神经特异性删除BMAL1在PN损伤后加速了轴突再生。这 在我们的实验室一系列进步的背景下，令人兴奋的发现是解密的 控制神经元内轴突生长潜力的转录网络，即转录因子如何 （TFS）与表观遗传因子合作以重塑染色质景观以诱导再生 - 相关基因（抹布）。我们最近的工作利用了我们全基因组的DNA映射 再生背根神经元（DRG）神经元中的羟甲基（5HMC）动力学。有趣的是，我们 发现BMAL1结合基序的富集在基因组基因局中显示出PN损伤后5HMC变化的富集， 提示BMAL1与5MC/5HMC转换酶TET3的相互作用。确实，小鼠中的BMAL1 CKO 证明BMAL1-TET3-5HMC轴调节与轴突生长，代谢和免疫相关的基因 互动。此外，先导数据显示了DRG中首次tet3和5hmc的昼夜表观遗传节奏 对BMAL1转录振荡的抗强调的神经元，对应于时间的时间差异 再生反应。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重新编程，再生和受伤造成的免疫激活的看门人。在 AIM 1，我们将表征BMAL1基因再生基因程序，并研究 SR9009对BMAL1转录的药理抑制作用，SR9009是具有中枢神经系统渗透的潜在Rev-ERB激动剂 从机械上讲，我们将测试一个“两次击中模型”，其中BMAL1删除Primes DRG神经元，但 在AIM 2中，我们将表征TET3/5HMC表观遗传节奏性， 与“神经突出时钟”的相关性，以及通过测试工作模型的基本机制 BMAL1控制TET3表达以及TET3募集以靶向5HMC重编程。我们将 然后绘制PN损伤对BMAL1-TET3-5HMC节奏的短期和长期影响 轴突重新连接后节奏恢复正常。在AIM 3中，我们枢转于体内研究促进效应 BMAL1对神经修复的抑制作用，包括摩托学功能。我们还将解决 PN损伤后不久，效果，性别差异和定时BMAL1抑制作用。总而言之，我们的建议具有 连接BMAL1圆形途径的潜力，TET3/5HMC表观遗传重编程，受伤触发 免疫反应和轴突再生，从而推进神经再生的基础科学和开放 翻译路径。