ENZYMATIC DE-INHIBITION OF AXONAL REGENERATION

轴突再生的酶促去抑制

• 批准号: 2852508
• 负责人: DAVID F MUIR
• 金额: $ 31.34万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-02 至 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2852508
• 关键词: axon; chondroitin sulfates; cryoscience; disease /disorder model; enzyme activity; gene targeting; laboratory mouse; metalloendopeptidases; nervous system regeneration; neural degeneration; neural inhibition; newborn animals; peripheral nervous system; polysaccharide carbon oxygen lyase; proteoglycan; spinal cord injury; tissue /cell culture; western blottings

DESCRIPTION (Verbatim from the Applicant's Abstract): The inability of the spinal cord to regenerate has been attributed to the preponderance of molecules that inhibit axonal growth. Foundation studies support the contention that CSPG is a main inhibitory component in spinal cord tissue. However, findings also suggest that inhibitory CSPG may suppress the growth-promoting potential of normal adult peripheral nerve. Since nerve has an excellent capacity to regenerate, injury must evoke some mechanism by which the damaged nerve is converted from a suppressive environment to one that promotes axonal growth. If so, this conversion somehow fails to occur in damaged spinal cord. In vitro studies show that bacterial chondroitinase and human matrix metalloproteinase-2 (MMP-2) degrade and inactivate inhibitory CSPG present in neural tissues and that nerve and spinal cord tissues contain latent neurite-promoting activities that are revealed after treatment with these enzymes. Experiments in this proposal will test the following main hypotheses: a) enzymatic inactivation of CSPG enhances the neurite-promoting potentials of nerve and spinal cord; b) enzymatic inactivation of CSPG occurs during nerve degeneration; c) inactivation of CSPG during nerve degeneration is MMP-2-dependent and neuronal expression of MMP-2 provides a second, more discrete mechanism for negotiation of inhibited substrata and; d) contrasts in the regenerative capacity of nerve and spinal cord reflect differences in the inactivation of CSPG achieved during degeneration and by injured axons. Experiments that address these hypotheses are presented in five major Aims, all of which center on mechanisms to inactivate inhibitory CSPG and improve nervous system regeneration. Aims 1 and 2 focus on the inactivation of CSPG in the peripheral nerve by chondroitinase and MMP-2, respectively. Aims 3 and 4 focus on the actions of these enzymes in the spinal cord. The efficacy of enzyme applications and the neurite-promoting potential of treated nerve and spinal cord tissues will be assayed in vitro and their impact on axonal regeneration will be tested in several in vivo injury models. Aim 5 will determine die expression of CSPG- inactivating enzymes in the nervous system to better understand the roles of these enzymes in the regenerative process. This information will advance our understanding of the regulation of axonal growth by inhibitory mechanisms and will be applied to devise means to improve axonal regeneration by enzymatic inactivation of CSPG. The main goal of this project is to prove that application of CSPG-degrading enzymes within injured tissues is an effective therapy to improve axonal regrowth and recovery of function throughout the nervous system.

描述(逐字摘自申请者的摘要)：脊髓再生的能力被归因于抑制轴突生长的分子的优势。基础研究支持CSPG是脊髓组织中的主要抑制成分的观点。然而，研究结果也表明，抑制性CSPG可能抑制正常成人周围神经的促生长潜力。由于神经具有良好的再生能力，损伤必须唤起某种机制，使受损的神经从抑制环境转变为促进轴突生长的环境。如果是这样的话，这种转换不知何故无法在受损的脊髓中发生。体外研究表明，细菌软骨素酶和人基质金属蛋白酶-2(MMP2)降解和钝化神经组织中存在的抑制性CSPG，神经和脊髓组织中含有潜在的促进轴突生长的活性。这一方案中的实验将检验下列主要假设：a)CSPG的酶失活增强了神经和脊髓的神经突起促进潜力；b)CSPG的酶失活发生在神经退变过程中；c)神经退变过程中CSPG的失活依赖于MMP2，神经元中MMP2的表达为抑制底物的谈判提供了第二个、更离散的机制；d)神经和脊髓的再生能力的对比反映了在退变过程中CSPG的失活与轴突损伤所实现的不同。解决这些假说的实验有五个主要目标，所有这些都集中在灭活抑制性CSPG和促进神经系统再生的机制上。目标1和目标2分别集中在软骨素酶和基质金属蛋白酶-2对周围神经中CSPG的失活。目标3和4侧重于这些酶在脊髓中的作用。将在体外测试酶应用的有效性和处理后的神经和脊髓组织的轴突促进潜力，并将在几个体内损伤模型中测试它们对轴突再生的影响。目的5将测定CSPG失活酶在神经系统中的表达，以更好地了解这些酶在再生过程中的作用。这些信息将促进我们对抑制机制对轴突生长调控的理解，并将被用于设计通过酶失活CSPG来促进轴突再生的方法。该项目的主要目的是证明在损伤组织内应用CSPG降解酶是一种有效的治疗方法，可以促进整个神经系统的轴突再生和功能恢复。