Up-regulation of the clusterin gene after proteotoxic stress:: implication of HSF1-HSF2 heterocomplexes
Up-regulation of the clusterin gene after proteotoxic stress:: implication of HSF1-HSF2 heterocomplexes
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DOI：
10.1042/bj20051190
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发表时间：
2006-04-01
影响因子：
4.1
通讯作者：
Le Dréan, Y
中科院分区：
文献类型：
--
作者：
Loison, F;Debure, L;Le Dréan, Y
胆固醇是一种分泌蛋白伴侣，在多种病理学中上调，包括癌症和神经退行性疾病。本研究表明，异常蛋白的积累，引起的蛋白酶体抑制剂MG 132或氨基酸类似物AZC（L-氮杂环丁烷-2-羧酸）的掺入，增加clusterin蛋白和mRNA水平的人胶质细胞系U-251 MG。因此，MG 132处理能够刺激1.3kb的丛生蛋白基因启动子.启动子缺失和突变研究揭示了一个关键的MG 132反应区域之间的-218和-106 bp，其中包含一个特殊的热休克元件，命名为CLE为'clusterin元件'。凝胶迁移率改变实验表明，MG 132和AZC处理诱导了与CLE结合的it蛋白复合物的形成。如超位移和染色质免疫沉淀实验所示，CLE在蛋白酶体抑制后被HSF 1（热休克因子1）和HSF 2结合。此外，免疫共沉淀试验表明，这两个转录因子相互作用。凝胶过滤分析表明，蛋白酶体抑制后与CLE结合的HSF 1-HSF 2杂合物与热休克后的HSF 1同源三聚体具有相同的表观质量，表明HSF 1和HSF 2可以异源三聚体化。因此，这些研究表明，丛生蛋白是一个很好的候选人，是一个细胞防御机制的一部分，对神经退行性疾病与错误折叠的蛋白质积累或蛋白酶体活性降低。
Clusterin is a secreted protein chaperone up-regulated in several pathologies, including cancer and neurodegenerative diseases. The present study shows that accumulation of aberrant proteins, caused by the proteasome inhibitor MG 132 or the incorporation of the amino acid analogue AZC (L-azetidine-2-carboxylic acid), increased both clusterin protein and mRNA levels in the human glial cell line U-251 MG. Consistently, MG 132 treatment was capable of stimulating a 1.3 kb clusterin gene promoter. Promoter deletion and mutation Studies revealed a critical MG132-responsive region between -218 and -106 bp, which contains a particular heat-shock element, named CLE for 'clusterin element'. Gel mobility-shift assays demonstrated that MG132 and AZC treatments induced the formation of it protein complex that bound to CLE. As shown by supershift and chromatin-immunoprecipitation experiments, CLE is bound by HSF1 (heat-shock factor 1) and HSF2 upon proteasome inhibition. Furthermore, co-immunoprecipitation assays indicated that these two transcription factors interact. Gel-filtration analyses revealed that the HSF1-HSF2 heterocomplexes bound to CLE after proteasome inhibition have the same apparent mass as HSF1 homotrimers after heat shock, suggesting that HSF1 and HSF2 Could heterotrimerize. Therefore these studies indicate that the clusterin is a good candidate to be part of a Cellular defence mechanism against neurodegenerative diseases associated with misfolded protein accumulation or decrease in proteasome activity.