HDAC6: a target for regeneration following injury in the nervous system

HDAC6：神经系统损伤后的再生目标

• 批准号: 8241046
• 负责人: Brett Cameron Langley
• 金额: $ 38.75万
• 依托单位: WINIFRED MASTERSON BURKE MED RES INST
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8241046
• 关键词: Acetylation; Acetyltransferase; Actins; Acute; Adult; Affect; Astrocytes; Axon; Cell Culture Techniques; Cells; Chondroitin Sulfate Proteoglycan; Chronic; Cytoskeleton; Deacetylation; Development; Disease; Dorsal; Environment; Enzymes; Exposure to; Failure; Fiber; Growth; Histone Acetylation; Histones; In Vitro; Injury; Isoenzymes; Lead; Lysine; Mediating; Methods; Microfluidics; Microtubules; Modeling; Molecular; Motor; Mus; Myelin; Myelin Associated Glycoprotein; Natural regeneration; Nervous system structure; Neuraxis; Neurites; Neurons; Neurosciences; Outcome; Paralysed; Patients; Play; Process; Property; Protein Isoforms; Proteins; Publishing; Rattus; Recovery; Recovery of Function; Regulation; Rodent Model; Role; Scheme; Sensory; Signal Transduction; Spinal cord injury; Testing; Therapeutic; Treatment Efficacy; Tubulin; Zinc; axon growth; axon regeneration; central nervous system injury; disability; growth inhibitory proteins; histone deacetylase 6; improved; improved functioning; in vivo; inhibitor/antagonist; injured; injury and repair; insight; nervous system disorder; neuronal cell body; novel; overexpression; pre-clinical; public health relevance; receptor; regenerative; relating to nervous system; response; restoration; therapeutic target; transcriptional coactivator p75

DESCRIPTION (provided by applicant): Spinal cord Injury is a problem affecting millions worldwide. A dominant hypothesis in regenerative neuroscience is that patients with spinal cord injury suffer from permanent functional deficits and paralysis because of neural damage, but also because of a limited capacity of CNS axons to regenerate and restore lost neuronal connectivity. According to this scheme, a primary cause of failed regeneration is a limited intrinsic ability of adult neurons to regrow injured axons and the growth-hostile environment of the damaged cord. Several critical molecules that impede axon regeneration in the injury territory have been identified and include myelin-derived growth-inhibitory proteins such as myelin associated-glycoprotein (MAG) and reactive astrocyte-produced chondroitin sulfate proteoglycans (CSPGs). Myelin and astrocyte-derived inhibitory signals ultimately converge on the actin and microtubule cytoskeleton, affecting their stability, dynamics, and ability to direct axonal growth. We have found that specifically targeting histone deacetylase 6 (HDAC6) in neurons, using both pharmacological inhibitors and knockdown methods, can overcome the inhibitory effects of MAG or CSPGs to axon growth, in vitro. Using microfluidic chambers that isolate axons from the neuronal cell bodies we have determined that local processes in the axon mediate this effect. Consistent with this, we have found that HDAC6 inhibition or knockdown does not increase histone acetylation (a canonical function of pan-HDAC inhibitors that target multiple HDAC isozymes) and that recovery of growth can occur in the presence of a transcriptional inhibitor. A primary, and non-nuclear, function of HDAC6 is the deacetylation of 1-tubulin lysine 40 and, in turn, the modulation of microtubule dynamics. Given the role of the microtubule in axon growth, we hypothesize that HDAC6 plays a role in mediating a cell's response to myelin and astrocyte derived inhibitory signals via 1- tubulin deacetylation and microtubule destabilization. In the Specific Aims of this Application, we will examine the function of HDAC6, as well as the 1-tubulin acetylating enzyme, Elp3, in growth-inhibited axons. We will examine the extent to which their activities modulate the acetylation level of 1-tubulin and the role of 1-tubulin deacetylation in microtubule destabilization and axonal regeneration failure. We also will test whether HDAC6 plays a role in axon regeneration failure in vivo and whether increasing 1-tubulin acetylation by HDAC inhibition enhances axonal regeneration after spinal cord injury. PUBLIC HEALTH RELEVANCE: Disability following spinal cord injury is attributed, in part, to a limited ability of central nervous system axons to regenerate. Contributing to this inability is the injury environment, where a number of growth-inhibitory proteins are known to be present (e.g., myelin associated-glycoprotein and chondroitin sulfate proteoglycans). Strategies that promote axons to re-grow in their presence are needed. Signals from these growth-inhibitory proteins ultimately converge on the actin and microtubule cytoskeleton, affecting their stability, dynamics, and ability to direct axonal growth. We have found that inhibiting histone deacetylase-6 (HDAC6), an enzyme responsible for the modulation of microtubules, appears to be an excellent, non-toxic therapeutic strategy for promoting regeneration in cell culture models. The proposed studies in this application will further define the mechanisms of HDAC6 inhibition-mediated axonal regeneration, as well as test its therapeutic efficacy in pre- clinical rodent models of spinal cord injury. Our findings in this project could lead to new treatments for spinal cord injury and other central nervous system injuries and disease.

描述（由申请人提供）：脊髓损伤是影响全球数百万的问题。再生神经科学中的主要假设是，脊髓损伤患者由于神经损伤而患有永久性功能缺陷和瘫痪，这也是由于中枢神经系统轴突能力有限，可再生和恢复神经元连接性丧失。根据该方案，再生失败的主要原因是成年神经元再生受伤的轴突和受损绳索的生长 - 害羞情绪环境的内在能力有限。已经鉴定出了损害损伤区域轴突再生的几个关键分子，包括髓磷脂衍生的生长抑制蛋白，例如髓磷脂相关糖蛋白（MAG）和反应性星形胶质素产生的硫酸盐硫酸盐蛋白蛋白蛋白蛋白蛋白共糖蛋白共糖蛋白蛋白酶（CSPGS）。髓磷脂和星形胶质细胞衍生的抑制性信号最终会在肌动蛋白和微管细胞骨架上汇聚，从而影响其稳定性，动力学和直接轴突生长的能力。 我们发现，使用药理学抑制剂和敲低方法，专门针对神经元中组蛋白脱乙酰基酶6（HDAC6）可以克服MAG或CSPG对轴突生长的抑制作用，体外。使用从神经元细胞体分离轴突的微流体腔，我们已经确定轴突中的局部过程介导了这种作用。与此相一致，我们发现HDAC6抑制或敲低不会增加组蛋白乙酰化（靶向多个HDAC同工酶的PAN-HDAC抑制剂的规范函数），并且在有转录抑制剂的存在下，生长的恢复可能会发生。 HDAC6的主要且非核的功能是1-微管赖氨酸40的脱乙酰基化，也是微管动力学的调节。鉴于微管在轴突生长中的作用，我们假设HDAC6在介导细胞对髓磷脂和星形胶质细胞的反应中发挥了作用，该反应通过1-微管蛋白脱乙酰基化和微管破坏稳定。在本应用的具体目的中，我们将研究HDAC6的功能，以及1-微管蛋白乙酰化酶ELP3，在生长抑制的轴突中。我们将研究其活性在多大程度上调节1-微管蛋白的乙酰化水平以及1-微管蛋白脱乙酰化在微管破坏稳定和轴突再生失败中的作用。我们还将测试HDAC6在体内的轴突再生衰竭中起作用，以及通过HDAC抑制增加1-微管蛋白乙酰化是否会增强脊髓损伤后轴突再生。 公共卫生相关性：脊髓损伤后的残疾部分归因于中枢神经系统轴突再生的能力有限。造成这种无能为力的是损伤环境，其中已知存在许多抑制生长的蛋白质（例如，髓磷脂相关糖蛋白和硫酸软骨素蛋白聚糖）。需要促进轴突在存在下重新生长的策略。这些抑制生长蛋白的信号最终会在肌动蛋白和微管细胞骨架上汇聚，从而影响其稳定性，动力学和引导轴突生长的能力。我们发现，抑制组蛋白脱乙酰基酶-6（HDAC6）是负责调节微管的酶，似乎是一种极好的，无毒的治疗策略，用于促进细胞培养模型的再生。该应用中提出的研究将进一步定义HDAC6抑制介导的轴突再生的机制，并在脊髓损伤的临床啮齿动物模型中测试其治疗功效。我们在该项目中的发现可能导致新的脊髓损伤和其他中枢神经系统损伤和疾病的治疗方法。