REGULATION OF MOTOR NEURON SURVIVAL IN VIVO

体内运动神经元存活的调节

• 批准号: 2750776
• 负责人: JEFFREY L ELLIOTT
• 金额: $ 10.44万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-30 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2750776
• 关键词: amyotrophic lateral sclerosis; antioxidants; apoptosis; calcium channel; degenerative motor system disease; denervation; disease /disorder model; enzyme activity; gene deletion mutation; gene expression; genetically modified animals; glutamate receptor; human tissue; in situ hybridization; laboratory mouse; mature animal; motor neurons; muscle cells; neurotransmitter biosynthesis; newborn animals; phenotype; protein structure; receptor expression; superoxide dismutase; voltage gated channel

The critical role of antioxidant enzymes in motor neuron survival has been established by the finding that missense mutations in the Cu/Zn superoxide dismutase (SOD) genes are responsible for a dominantly inherited form of amyotrophic lateral sclerosis (FALS). However, whether motor neuron loss in FALS results from a toxic gain in function by a mutant enzyme, or is related to diminished levels of Cu\Zn SOD activity is still unclear. The generation of transgenic mice heterozygous and homozygous for a Cu\Zn SOD gene deletion now allows definitive testing of the hypothesis that motor neuron survival in vivo is directly related to Cu\Zn SOD levels. In the work outlined, I will determine whether reductions of Cu/Zn SOD activity in these mice will lead to decreased motor neuron survival over time, preferential involvement of motor neurons as compared to other classes of neurons, and increased motor neuron vulnerability to axotomy. I will also test the idea that the motor neurons dying in these transgenic animals after axotomy will exhibit characteristics of apoptosis. The close relationship between antioxidant defenses and apoptosis is underscored by the observations that powerful inhibitors of apoptosis may in fact prevent death by antioxidant mechanisms. The bcl-2 family of genes, mammalian homologs of the ced-9 gene in C. elegans, represent one such class of molecules, and within this group there is evidence that bcl- XL may have the most relevance for the nervous system. Remarkably within another family of genes, mammalian homologs of the C. elegans ced-3 gene, one member ich-1s also appears to prevent apoptosis in vitro. Here, I propose to generate transgenic animals which overexpress either Bcl-XL or ICH-1s in motor neurons and then determine whether overexpression of these molecules is protective in acquired models of motor neuron degeneration. Furthermore, this project will determine whether overexpression of Bcl-XL or ICH-1s will preserve the phentoype of axotomized motor neurons with regard to neurotransmitter synthesis and functional reinnervation of muscle. Finally, I will compare expression of genes implicated in neuronal survival in both ALS-sensitive and ALS-resistant motor pools in an effort to identify molecules which account for the selective vulnerability of certain motor neuron populations in ALS. Overall, these experiments will test the idea that molecules related to antioxidant defenses or apoptosis regulate motor neuron survival in vivo. Results from these experiments will have important implications for the potential mechanisms underlying motor neuron disease as well as for possible therapeutic interventions.

抗氧化酶在运动神经元存活中的关键作用一直是 通过发现Cu/Zn超氧化物中的错义突变 歧化酶（SOD）基因负责一种显性遗传形式的 肌萎缩性侧索硬化症（ALS）。然而，运动神经元的丧失 在FALS中，由突变酶的功能毒性增益引起，或者 与Cu\Zn SOD活性降低水平的关系尚不清楚。的 Cu\Zn SOD的杂合和纯合转基因小鼠的产生 基因删除现在允许明确的假设测试， 体内神经元存活与Cu、Zn SOD水平直接相关。在 工作概述，我将确定是否减少铜/锌SOD活性 会导致运动神经元存活率随时间降低， 与其他类型的运动神经元相比， 神经元，并增加运动神经元对轴突切断的脆弱性。我也会 来验证转基因动物的运动神经元死亡 轴突损伤后会表现出细胞凋亡的特征。 抗氧化防御和细胞凋亡之间的密切关系是 观察结果强调，强大的细胞凋亡抑制剂可能 实际上是通过抗氧化机制来防止死亡。的bcl-2家族 ced-9基因的哺乳动物同源物。优雅，代表一个 这类分子，在这组中有证据表明，bcl-2- XL可能与神经系统最相关。值得注意的是 另一个基因家族，C.线虫ced-3基因， 其中一个成员ICH-1 S似乎也在体外阻止细胞凋亡。这里我 提出产生过表达Bcl-XL或Bcl-XL的转基因动物， ICH-1在运动神经元中的表达，然后确定这些表达是否 分子在获得性运动神经元变性模型中具有保护作用。 此外，本项目将确定是否过表达Bcl-XL 或ICH-1将保留轴突切断的运动神经元的表型， 关于神经递质的合成和功能性神经支配， 肌肉.最后，我将比较与神经元凋亡有关的基因的表达， 在ALS敏感和抗ALS的运动池中存活， 来识别那些导致选择性脆弱性的分子， ALS中的某些运动神经元群体。 总的来说，这些实验将测试分子相关的想法 抗氧化防御或凋亡调节体内运动神经元存活。 这些实验的结果将对研究 运动神经元疾病的潜在机制以及 可能的治疗干预。