Ultrastructural study of aggregates in the spinal cord of transgenic mice with a G93A mutant SOD1 gene
Ultrastructural study of aggregates in the spinal cord of transgenic mice with a G93A mutant SOD1 gene
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DOI：
10.1007/s00401-004-0939-7
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发表时间：
2005-03
影响因子：
12.7
通讯作者：
S. Sasaki;H. Warita;T. Murakami;N. Shibata;T. Komori;K. Abe;Makio Kobayashi;M. Iwata
中科院分区：
文献类型：
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作者：
S. Sasaki;H. Warita;T. Murakami;N. Shibata;T. Komori;K. Abe;Makio Kobayashi;M. Iwata
超氧化物歧化酶1阳性聚集体的超微结构特征进行了测定，以澄清这些聚集体是否与超氧化物歧化酶1突变小鼠的发病机制。我们研究了表达G93 A突变体人SOD 1基因的转基因小鼠的脊髓，该基因具有较少的拷贝数（基因拷贝10）。在症状前期（24周龄），SOD 1和泛素阳性颗粒，线性，或圆形存款偶尔被发现在前角的神经鞘。在超微结构上，在前角的神经突起包括轴突中偶尔观察到小的丝状聚集体。在症状前晚期（28周），SOD 1和泛素阳性沉积物和Lewy小体样包涵体（LI）经常被证明在神经元过程中，包括索样肿胀轴突和一些剩余的前角神经元。超微结构上，较大的丝状聚集体是常见的，占主导地位的前角，包括近端轴突的神经元过程中，但很少在胞体和树突。聚集体通常由交织的中间丝（直径约10-15 nm）组成，并且通常在中心含有类似于LI的电子致密核。偶尔聚集体主要由颗粒状、无定形或囊泡状物质组成，显示较少的丝状结构。在症状阶段（32周和35周），LI经常出现在前角的神经元突起内，特别是在索状肿胀的轴突中。在整个白色物质柱和前角和后角的灰质中观察到比前一阶段更显著的SOD 1和泛素阳性沉积物。超微结构上，聚集体经常包含电子致密的核心，并经常观察到索状肿胀的轴突组成的积累的神经丝。高水平的人SOD 1-和泛素-免疫金标记存在于小到大的聚集体中，即使在症状前阶段，聚集体的大小和频率随时间增加。紧密包装的细丝和电子致密的核心的聚集体显示SOD 1-和泛素-免疫金标记比松散包装的细丝更显着。这些研究结果表明，积累的SOD 1阳性聚集体的神经元过程中，主要是在轴突，构成了一个重要的决定因素的神经毒性和发病机制的动物模型，可能会导致损害轴突运输的螯合突变体SOD 1蛋白聚集体内，或部分通过物理阻断轴突运输。
The ultrastructural features of SOD1-positive aggregates were determined to clarify whether these aggregates are associated with the pathogenesis of SOD1 mutant mice. We examined the spinal cord of transgenic mice expressing a G93A mutant human SOD1 gene with fewer copies (gene copy 10). At the early presymptomatic stage (age 24 weeks), SOD1- and ubiquitin-positive granular, linear, or round deposits were found occasionally in the neuropil of the anterior horns. Ultrastructurally, small filamentous aggregates were observed occasionally in the neuronal processes including the axons in the anterior horns. At the late presymptomatic stage (28 weeks), SOD1- and ubiquitin-positive deposits and Lewy body-like inclusions (LIs) were frequently demonstrated in the neuronal processes including cord-like swollen axons and in some remaining anterior horn neurons. Ultrastructurally, larger filamentous aggregates were frequent, predominating in the neuronal processes of the anterior horns including the proximal axons, but were rare in the somata and dendrites. The aggregates usually consisted of interwoven intermediate filaments (about 10–15 nm in diameter) and frequently contained electron-dense cores in the center resembling LIs. Occasionally the aggregates consisted mainly of granular, amorphous, or vesicular substance, showing fewer filamentous structures. At the symptomatic stages (32 and 35 weeks), LIs were frequently demonstrated within the neuronal processes in the anterior horns, particularly in the cord-like swollen axons. Many more prominent SOD1- and ubiquitin-positive deposits were observed over the whole white matter columns and in the gray matter of the anterior and posterior horns than at the previous stage. Ultrastructurally, aggregates frequently contained electron-dense cores, and were frequently observed in cord-like swollen axons consisting of accumulated neurofilaments. A high level of human SOD1-and ubiquitin-immunogold labeling was present in small to large aggregates even at the presymptomatic stages, and the aggregates increased in size and frequency with time. Compactly packed filaments and electron-dense cores of aggregates showed SOD1-and ubiquitin-immunogold labeling more prominently than in loosely packed filaments. These findings suggest that the accumulation of SOD1-positive aggregates in the neuronal processes, predominantly in the axons, constitutes an important determinant of neurotoxicity and the pathogenesis of this animal model, probably causing impairment of axonal transport by the sequestration of mutant SOD1 protein within aggregates, or in part by physically blocking the axonal transport.