Role of BRCA1 in heat shock response.
Role of BRCA1 in heat shock response.
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BRCA1 在热休克反应中的作用。
DOI：
10.1038/sj.onc.1206061
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
Rosen,EliotM
中科院分区：
文献类型：
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作者：
XianMa,Yong;Fan,Saijun;Xiong,Jingbo;Yuan,Ren-Qi;Meng,Qinghui;Gao,Min;Goldberg,ItzhakD;Fuqua,SuzanneA;Pestell,RichardG;Rosen,EliotM
热休克反应是一种进化上保守的反应热和其他压力，促进维持关键的代谢功能和细胞存活。我们报道了将人前列腺（DU-145）和乳腺（MCF-7）癌细胞暴露于热（42 ℃）导致乳腺癌易感基因-1（BRCA 1）蛋白快速消失，从加热开始后101小时开始，稍微滞后于热休克蛋白70（HSP 70）水平的增加。BRCA 1的热诱导损失发生在蛋白水平，因为：（1）BRCA 1 mRNA表达不受影响;（2）在表达外源野生型BRCA 1（wtBRCA 1）的DU-145细胞中也观察到BRCA 1蛋白损失。除了热调节BRCA 1蛋白水平外，我们还发现BRCA 1可以调节热休克反应。因此，wtBRCA 1过表达的DU-145细胞克隆显示出对热诱导的细胞毒性的敏感性显著降低;而Brca 1突变小鼠胚胎成纤维细胞显示出对热的敏感性增加。DU-145 wtBRCA 1克隆也显示了小的热休克蛋白HSP 27的表达增加;报告基因分析显示，wtBRCA 1刺激HSP 27启动子活性增加2至4倍，这与其上调HSP 27 mRNA和蛋白水平的能力一致。在使用表位标记的截短BRCA 1蛋白的研究中，刺激HSP 27启动子和介导热诱导降解的能力需要BRCA 1的氨基末端而不是羧基末端。虽然BRCA 1的热诱导损失似乎是由于蛋白质降解，但各种蛋白质代谢剂（或组合）未能阻断该事件，包括：MG 132（26 S蛋白酶体抑制剂），N-乙酰基-亮氨酰-亮氨酰-正亮氨酸（钙蛋白酶抑制剂），z-VAD-falcine（泛半胱天冬酶抑制剂），氯化铵和氯喹（稳定溶酶体）。这些发现表明，除了它的其他功能，BRCA 1可能参与哺乳动物的热休克反应途径。
The heat shock response is an evolutionarily conserved response to heat and other stresses that promotes the maintenance of key metabolic functions and cell survival. We report that exposure of human prostate (DU-145) and breast (MCF-7) cancer cells to heat (42 C) caused a rapid disappearance of the breast cancer susceptibility gene-1 (BRCA1) protein, starting at≈ 1 h after the onset of heating and slightly lagging behind the increase in heat shock protein 70 (HSP70) levels. The heat-induced loss of BRCA1 occurred at the protein level, since:(1) BRCA1 mRNA expression was unaffected; and (2) the BRCA1 protein loss was also observed in DU-145 cells that expressed exogenous wild-type BRCA1 (wtBRCA1). In addition to heat regulation of BRCA1 protein levels, we also found that BRCA1 could modulate the heat shock response. Thus, wtBRCA1 overexpressing DU-145 cell clones showed significantly decreased sensitivity to heat-induced cytotoxicity; and Brca1 mutant mouse embryo fibroblasts showed increased sensitivity to heat. The DU-145 wtBRCA1 clones also showed increased expression of the small heat shock protein HSP27; and reporter assays revealed that wtBRCA1 stimulated a two to four-fold increase in HSP27 promoter activity, consistent with its ability to upregulate HSP27 mRNA and protein levels. In studies using epitope-tagged truncated BRCA1 proteins, the ability to stimulate the HSP27 promoter and to mediate heat-induced degradation required the amino-terminus but not the carboxyl-terminus of BRCA1. Although the heat-induced loss of BRCA1 appeared to be due to protein degradation, various protein metabolic agents (or combinations) failed to block this event, including: MG132 (a 26S proteasomal inhibitor), N-acetyl-leucyl-leucyl-norleucinal (a calpain inhibitor), z-VAD-fmk (a pan-caspase inhibitor), and ammonium chloride and chloroquine (which stabilize lysosomes). These findings suggest that in addition to its other functions, BRCA1 may participate in mammalian heat shock response pathways.