Role of the Cytoskeleton in Regeneration and Sprouting

细胞骨架在再生和发芽中的作用

• 批准号: 7017754
• 负责人: LINDA M PARYSEK
• 金额: $ 30.17万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-06-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7017754
• 关键词: axon; cell proliferation; cytoskeletal proteins; developmental neurobiology; dorsal root; electron microscopy; fibrous protein; genetically modified animals; hereditary motor and sensory neuropathy; intermediate filaments; intracellular transport; laboratory mouse; microtubule associated protein; mitochondria; nerve growth factors; nervous system regeneration; neuronal guidance; posttranslational modifications; protein localization; protein protein interaction; spinal ganglion

DESCRIPTION (provided by applicant): In the adult human, perception of pain and temperature depends on stimulation of skin free nerve endings from nociceptive neurons in the dorsal root ganglion (DRG) that are characterized by their small size and unmyelinated peripheral and central neuronal processes. After damage to skin, uninjured nociceptive neurons sprout collateral branches that restore sensation to adjacent areas of damaged skin. In the previous project period, we found that disruption of peripherin intermediate filaments (IF) by expression of a dominant negative mutant peripherin gene inhibited the establishment of extensive neurite trees by these neurons when cultured in vitro. Similarly, disruption of IF limited the ability of these neurons to sprout collaterals to adjacent damaged skin in vivo, a finding that appears to echo the in vitro result. Further, knockout of the peripherin gene in mice results in proportionally fewer small-sized DRG neurons and a smaller number of central processes in the dorsal root. These findings indicate peripherin IF are crucial for differentiation and collateral sprouting of DRG neurons. To define the precise role of peripherin IF, the first Aim of this proposal focuses on determining whether loss of peripherin from birth in the knockout mouse results in actual death of small DRG neurons or simply an alteration in the proportion of these cells. In addition, we will determine whether loss of peripherin, like expression of mutant peripherin, critically affects branching of these neurons, this time in their central processes. Then, we will investigate one plausible reason why peripherin IF may be required for the sprouting, branching, and survival of neurons. In normal neurons, mitochondria are concentrated at growth cones and axonal branch points, where they are thought to provide local sources of energy essential for neurite outgrowth and branching. Defects in mitochondria distribution lead to neuronal degeneration. We have found that an intact IF network is essential for proper distribution of mitochondria in sensory neuronal processes. Similarly, in muscle, the IF protein desmin is critical for normal mitochondria! distribution and function. In muscle, IF are linked to mitochondria by a large protein called plectin. Based on our preliminary findings that that peripherin binds to plectin and that disruption of peripherin in sensory neurons causes defects in mitochondrial distribution, we will test the hypothesis that plectin mediates the interaction of peripherin IF with mitochondria and that peripherin has a critical role in distribution of mitochondria in sensory neurons. Defects in mitochondrial distribution could explain limitations on the length and collateralization of neuronal processes and, perhaps, death of nociceptors seen in the disrupter and knockout mice. These mice serve as models for human disease that could be induced by peripherin gene mutations.

描述（由申请人提供）：在成年人中，对疼痛和温度的感知取决于背根神经节（DRG）的伤害性神经元（DRG）的刺激，这些神经元的尺寸较小且不层状外周和中心神经元过程。 。对皮肤损害后，未受伤的伤害性神经元发芽附带分支，将感觉恢复到受损皮肤的相邻区域。在上一个项目时期，我们发现外周中间丝（如果）通过表达显性阴性突变蛋白外周基因的破坏会抑制这些神经元在体外培养时抑制这些神经元广泛的神经突的建立。同样，如果限制了这些神经元在体内邻近受损的皮肤的促进能力的破坏，这一发现似乎可以呼应体外结果。此外，小鼠周围基因的敲除导致小型小型DRG神经元和背根中的较少数量的中央过程。这些发现表明外围蛋白对于DRG神经元的分化和附带发芽至关重要。为了定义外围蛋白的确切作用，该提案的第一个目的集中在确定敲除小鼠中出生中外周蛋白的丧失会导致小型DRG神经元的实际死亡或仅仅改变了这些细胞的比例。此外，我们将确定外周的丧失（例如突变外周蛋白的表达）是否在其中心过程中对这些神经元的分支产生严重影响。然后，我们将研究一个合理的原因，为什么外围蛋白是否需要进行神经元的发芽，分支和存活。在正常的神经元中，线粒体集中在生长锥和轴突分支点上，在那里它们被认为为神经突生长和分支提供了必不可少的局部能源。线粒体分布的缺陷导致神经元变性。我们发现，如果网络对于在感觉神经元过程中正确分布的线粒体适当分布至关重要。同样，在肌肉中，IF蛋白脱敏对于正常线粒体至关重要！分布和功能。在肌肉中，如果通过称为蛋白质的大蛋白与线粒体相关。基于我们的初步发现，外围蛋白与蛋白质结合以及感觉神经元中周围蛋白的破坏会导致线粒体分布中的缺陷，我们将测试plectin在与线粒体和外围蛋白具有关键作用中介导外围蛋白相互作用的假说感觉神经元中的线粒体。线粒体分布的缺陷可以解释神经元过程长度和抵押的局限性，以及在dis虫和敲除小鼠中看到的伤害感受器的死亡。这些小鼠是外周基因突变可能诱导的人类疾病的模型。