ENZYMATIC DE-INHIBITION OF AXONAL REGENERATION

轴突再生的酶促去抑制

• 批准号: 6639541
• 负责人: DAVID F MUIR
• 金额: $ 33.17万
• 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 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6639541
• 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（逐字摘自申请人摘要）：脊髓不能再生归因于抑制轴突生长的分子占优势。基础研究支持CSPG是脊髓组织中主要抑制成分的论点。然而，研究结果也表明，抑制性CSPG可能会抑制正常成人周围神经的生长促进潜力。由于神经具有良好的再生能力，因此损伤必须引起某种机制，通过这种机制，受损的神经从抑制性环境转化为促进轴突生长的环境。如果是这样的话，这种转换不知何故未能发生在受损的脊髓。体外研究表明，细菌软骨素酶和人基质金属蛋白酶-2（MMP-2）降解和抑制存在于神经组织中的CSPG，神经和脊髓组织含有潜在的神经突促进活性，这些活性在用这些酶处理后显示。本提案中的实验将测试以下主要假设：a）CSPG的酶失活增强神经和脊髓的促神经突潜力; B）CSPG的酶失活发生在神经变性期间; c）神经变性期间CSPG的失活是MMP-2依赖性的，并且MMP-2的神经元表达提供了第二种更离散的机制用于协商受抑制的底物; d）神经和脊髓的再生能力的对比反映了在变性期间和通过受损轴突实现的CSPG失活的差异。解决这些假设的实验在五个主要目标中提出，所有这些目标都集中在抑制抑制CSPG和改善神经系统再生的机制上。目的1和2分别关注软骨素酶和MMP-2对周围神经中CSPG的失活。目的3和4集中在这些酶在脊髓中的作用。将在体外测定酶应用的功效和经处理的神经和脊髓组织的促神经突潜力，并将在几种体内损伤模型中测试它们对轴突再生的影响。目的5将确定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。这一信息将促进我们的理解轴突生长的抑制机制的调节，并将被应用于设计手段，以改善轴突再生酶失活的CSPG。该项目的主要目标是证明在受损组织中应用CSPG降解酶是改善整个神经系统轴突再生和功能恢复的有效疗法。