Liu A Y, Bian H, Huang L E, Lee Y K
Department of Biological Sciences, Rutgers, State University of New Jersey, Piscataway 08855-1059.
J Biol Chem. 1994 May 20;269(20):14768-75.
We evaluated the effects of a transient cold shock followed by recovery and incubation at 37 degrees C on the regulation of heat shock gene expression in the IMR-90 human diploid fibroblasts and HeLa cells in tissue culture. We showed that preincubation of cells at 4 degrees C induced the synthesis and accumulation of the heat shock proteins (HSPs) upon recovery at 37 degrees C, and the degree of this induction was directly related to the time that the cells spent at 4 degrees C. Assays on the abundance of the hsp 70 transcript, the hsp 70 gene promoter activity, and the trimerization and activation of heat shock factor (HSF) to bind to its consensus heat shock element (HSE) provided evidence that this induction of the heat shock response in cells recovering from a transient cold shock is attributable to a transcriptional event mediated by the activation of HSF. Further, the induction was a response to the temperature upshift from 4 to 37 degrees C as opposed to the 4 degrees C treatment itself; quantitation of the HSE-binding activity of cells incubated at 4 degrees C without recovery and incubation at 37 degrees C gave no evidence of an activated response. Analysis of the effects of protein synthesis inhibitors demonstrated that neither cycloheximide nor puromycin was effective in blocking the induction of HSE-binding activity in cells recovering from a transient cold shock. Experiments on the time course and temperature dependence of this induction of HSE-binding activity showed that the onset, magnitude, and duration of this induction were directly proportional to the severity of the cold stress (measured by time and temperature). We discuss the possible mechanism(s) involved in this induction of the heat shock genes at 37 degrees C by a transient cold shock and the biological implications of this observation.
我们评估了短暂冷休克后在37℃恢复和孵育对组织培养中的IMR-90人二倍体成纤维细胞和HeLa细胞热休克基因表达调控的影响。我们发现，将细胞在4℃预孵育后，在37℃恢复时会诱导热休克蛋白（HSPs）的合成和积累，这种诱导的程度与细胞在4℃停留的时间直接相关。对hsp 70转录本丰度、hsp 70基因启动子活性以及热休克因子（HSF）三聚化和激活以结合其共有热休克元件（HSE）的分析提供了证据，表明从短暂冷休克恢复的细胞中热休克反应的这种诱导归因于HSF激活介导的转录事件。此外，这种诱导是对从4℃到37℃的温度上升的反应，而不是对4℃处理本身的反应；对在4℃孵育而不恢复和在37℃孵育的细胞的HSE结合活性进行定量分析，没有发现激活反应的证据。蛋白质合成抑制剂的作用分析表明，环己酰亚胺和嘌呤霉素都不能有效阻断从短暂冷休克恢复的细胞中HSE结合活性的诱导。对这种HSE结合活性诱导过程的时间进程和温度依赖性的实验表明，这种诱导的起始、幅度和持续时间与冷应激的严重程度（通过时间和温度测量）成正比。我们讨论了短暂冷休克在37℃诱导热休克基因的可能机制以及这一观察结果的生物学意义。
