School of Medical Science, Griffith Health Institute, Griffith University, Gold Coast Campus, Gold Coast, QLD 4222, Australia.
Neurotox Res. 2013 Jan;23(1):1-21. doi: 10.1007/s12640-012-9358-z. Epub 2012 Nov 15.
Oligodendroglial inclusion bodies characterize a subset of neurodegenerative diseases. Multiple system atrophy (MSA) is characterized by α-synuclein glial cytoplasmic inclusions and progressive supranuclear palsy (PSP) is associated with glial tau inclusions. The ubiquitin homologue, SUMO-1, has been identified in inclusion bodies in MSA, located in discrete sub-domains in α-synuclein-positive inclusions. We investigated SUMO-1 associated with oligodendroglial inclusion bodies in brain tissue from MSA and PSP and in glial cell models. We examined MSA and PSP cases and compared to age-matched normal controls. Fluorescence immunohistochemistry revealed frequent SUMO-1 sub-domains within and surrounding inclusions bodies in both diseases and showed punctate co-localization of SUMO-1 and the lysosomal marker, cathepsin D, in affected brain regions. Cell counting data revealed that 70-75 % of lysosomes in inclusion body-positive oligodendrocytes were SUMO-1-positive consistently across MSA and PSP cases, compared to 20 % in neighbouring inclusion body negative oligodendrocytes and 10 % in normal brain tissue. Hsp90 co-localized with some SUMO-1 puncta. We examined the SUMO-1 status of lysosomes in 1321N1 human glioma cells over-expressing α-synuclein and in immortalized rat oligodendrocyte cells over-expressing the four repeat form of tau following treatment with the proteasome inhibitor, MG132. We also transfected 1321N1 cells with the inherently aggregation-prone huntingtin exon 1 mutant, HttQ74-GFP. Each cell model showed the association of SUMO-1-positive lysosomes around focal cytoplasmic accumulations of α-synuclein, tau or HttQ74-GFP, respectively. Association of SUMO-1 with lysosomes was also detected in glial cells bearing α-synuclein aggregates in a rotenone-lesioned rat model. SUMO-1 labelling of lysosomes showed a major increase between 24 and 48 h post-incubation of 1321N1 cells with MG132 resulting in an increase in a 90 kDa SUMO-1-positive band that was immunopositive for Hsp90 and immunoprecipitated with an anti-SUMO-1 antibody. That SUMO-1 co-localizes with a subset of lysosomes in neurodegenerative diseases with glial protein aggregates and in glial cell culture models of protein aggregation suggests a role for SUMO-1 in lysosome function.
少突胶质细胞包涵体是一组神经退行性疾病的特征。多系统萎缩症（MSA）的特征是α-突触核蛋白神经胶质细胞质包涵体，进行性核上性麻痹（PSP）与神经胶质中的 tau 包涵体有关。泛素同系物 SUMO-1 已在 MSA 的包涵体中被鉴定出来，位于 α-突触核蛋白阳性包涵体的离散亚域中。我们研究了 MSA 和 PSP 脑组织中与少突胶质细胞包涵体相关的 SUMO-1，并在神经胶质细胞模型中进行了研究。我们检查了 MSA 和 PSP 病例，并与年龄匹配的正常对照组进行了比较。荧光免疫组织化学显示，两种疾病的包涵体内部和周围都有频繁的 SUMO-1 亚域，并显示在受影响的脑区中，SUMO-1 和溶酶体标志物组织蛋白酶 D 呈点状共定位。细胞计数数据显示，包涵体阳性少突胶质细胞中 70-75%的溶酶体持续呈 SUMO-1 阳性，而相邻的包涵体阴性少突胶质细胞为 20%，正常脑组织为 10%。Hsp90 与一些 SUMO-1 斑点共定位。我们检查了在过表达 α-突触核蛋白的 1321N1 人神经胶质瘤细胞和过表达四重复形式 tau 的大鼠永生化少突胶质细胞中溶酶体的 SUMO-1 状态，这些细胞在蛋白酶体抑制剂 MG132 处理后。我们还将易聚集的 huntingtin 外显子 1 突变体 HttQ74-GFP 转染到 1321N1 细胞中。每个细胞模型均显示出 SUMO-1 阳性溶酶体在焦点细胞质 α-突触核蛋白、tau 或 HttQ74-GFP 积聚周围的聚集。在鱼藤酮损伤的大鼠模型中，具有 α-突触核蛋白聚集物的神经胶质细胞中也检测到 SUMO-1 与溶酶体的关联。在与 1321N1 细胞孵育 24 和 48 小时后，溶酶体的 SUMO-1 标记显示出显着增加，导致 90 kDa SUMO-1 阳性带增加，该带对 Hsp90 呈免疫阳性，并与抗 SUMO-1 抗体免疫沉淀。SUMO-1 与神经退行性疾病中的神经胶质蛋白包涵体和神经胶质细胞蛋白聚集的培养模型中的溶酶体共定位表明，SUMO-1 在溶酶体功能中起作用。
