Molecular Mechanisms of Hexacarbon-Induced Axon Atrophy

六碳诱发轴突萎缩的分子机制

• 批准号: 7106091
• 负责人: Richard Michael Lopachin
• 金额: $ 34.53万
• 依托单位: MONTEFIORE MEDICAL CENTER (BRONX, NY)
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-01-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7106091
• 关键词: adduct; atrophy; axon; cell morphology; cytoskeleton; environmental toxicology; ketones; kinesin; laboratory rat; microtubules; molecular assembly /self assembly; molecular pathology; neural degeneration; neurochemistry; neurofilament; neurofilament proteins; neurotoxicology; neurotoxins; occupational hazard; pathologic process; protein protein interaction; protein structure function; protein transport; proteomics; pyrroles; radiotracer; spinal cord

DESCRIPTION (provided by applicant): 2,5-Hexanedione (HD), the neurotoxic diketone metabolite of the industrial solvents methyl n-butyl ketone and n-hexane, causes a toxic neuropathy in occupationally exposed humans. Although axonal swellings have been considered the morphological hallmark, recent quantitative morphometric studies show that axon atrophy is a specific, prevalent effect that is temoporally correlated to the development of neurological defects. These findings suggest that atrophy is an essential pathophysiological component of diketone- induced neurotoxicity. The long-term objectives of this research project are to determine the molecular mechanism of axon atrophy. Studies conducted during the current funding period (yrs 04-07) indicated that HD intoxication of rats was associated with a depletion of mobile neurofilament (NF) proteins. This effect did not involve changes in NF phosphorylation or subunit gene expression. Since HD forms pyrrole adducts with NFs, we hypothesize that adduction interferes with the ability of mobile NFs to interact with the stationary cytoskeleton polymer. As a result, the subunit remains attached to the transport vector kinesin, which in the absence of compensatory changes in protein synthesis, promotes anterograde loss of NF subunits. Atrophy occurs due to depletion of the mobile NF pool and to the ensuing impairment of cytoskeletal turnover. This hypothesis will be tested by the following Specific Aims: 1) Mass spectrometry will be used to characterize HD-induced pyrrole formation in the stationary and mobile NF pools. 2) The effects of pyrrole formation on NF subunit kinesin-based transport, assembly and cytoskeletal incorportation will be determined. 3) The content and spatial relationships among cytoskeletal elements (NFs, microtubules) will be quantified in peripheral myelinated axons of HD-intoxicated rats and age-matched controls. 4) The ability of HD structural analogs (e.g., 3,4-dimethyl 2,5-HD) to predictably alter proteomic, morphological and biochemical parameters will be evaluated. Understanding the role and mechanism of axon atrophy in solvent neurotoxicity has broad-based implications for human occupational health and risk assessment.

描述（由申请人提供）：2,5-己二酮（HD），工业溶剂的神经毒性二酮代谢产物甲基N-丁基酮和N-己烷，会在占领的人类中引起有毒的神经病。尽管轴突肿胀已被认为是形态学的标志，但最近的定量形态计量学研究表明，轴突萎缩是一种特定的，普遍的效果，与神经系统缺陷的发展相关。这些发现表明萎缩是二酮诱导神经毒性的重要病理生理成分。该研究项目的长期目标是确定轴突萎缩的分子机制。在当前资助期间进行的研究（YRS 04-07）表明，大鼠的HD中毒与移动神经丝（NF）蛋白的耗竭有关。这种作用不涉及NF磷酸化或亚基基因表达的变化。由于HD与NFS形成吡咯合金，因此我们假设内收干扰了移动NF与固定细胞骨架聚合物相互作用的能力。结果，亚基仍然附着在运输载体驱动蛋白上，在没有蛋白质合成的代偿性变化的情况下，促进了NF亚基的顺行损失。萎缩是由于移动NF池的耗竭以及随之而来的细胞骨架更新损害。该假设将通过以下特定目的进行检验：1）质谱法将用于表征固定和移动NF池中HD诱导的吡咯形成。 2）将确定吡咯形成对基于NF亚基的转运，组装和细胞骨架不体事件的影响。 3）细胞骨架元素（NFS，微管）之间的含量和空间关系将在HD毒素大鼠和年龄匹配的对照组的外周髓骨轴突中进行量化。 4）将评估HD结构类似物（例如3,4-二甲基2,5-HD）的能力，可以评估可预测的改变蛋白质组学，形态学和生化参数。了解轴突萎缩在溶剂神经毒性中的作用和机制对人类职业健康和风险评估具有广泛的影响。