Hayashi Y, Tohnai I, Kaneda T, Kobayashi T, Ohtsuka K
Department of Oral Surgery, Nagoya University School of Medicine, Japan.
Radiat Res. 1991 Jan;125(1):80-8.
We have investigated intracellular translocation of hsp-70 and the synthesis of hsp-70 and total protein during heating at moderate temperatures in HeLa cells. When cells were heated at temperatures above 41 degrees C, hsp-70 translocated from the cytoplasm into the nuclei and apparently accumulated in nucleoli within 10 min. At temperatures above 42 degrees C, hsp-70 remained in the nuclei during heating. When cells were heated at 41 degrees C, the hsp-70 which had translocated into the nuclei returned gradually to the cytoplasm during heating. Synthesis of hsp-70 increased to three- to fourfold that in control cells, then decreased to the control level by 6-8 h. Total protein synthesis first decreased to 60% of the control level, then gradually recovered by 4 h. This indicates the acquisition of translational tolerance during heating at 41 degrees C. The return of hsp-70 to the cytoplasm is related to the recovery of total protein synthesis. Similar results were obtained at 42 degrees C heating in heat-induced thermotolerant cells. From these results, it is suggested that translocation of hsp-70 into the nuclei is very important for the recovery of protein synthesis (acquisition of translational tolerance) during heating at moderate temperatures. Also, cycloheximide and puromycin appeared to lower the temperature threshold about 1 degree C with respect to the translocation of hsp-70.
我们研究了HeLa细胞在适度温度加热过程中热休克蛋白70（hsp - 70）的细胞内转运以及hsp - 70和总蛋白的合成情况。当细胞在41摄氏度以上的温度加热时，hsp - 70在10分钟内从细胞质转运到细胞核，并明显积聚在核仁中。在42摄氏度以上的温度加热时，hsp - 70在加热过程中一直留在细胞核内。当细胞在41摄氏度加热时，转运到细胞核的hsp - 70在加热过程中逐渐回到细胞质。hsp - 70的合成增加到对照细胞的三到四倍，然后在6 - 8小时后降至对照水平。总蛋白合成首先降至对照水平的60%，然后在4小时内逐渐恢复。这表明在41摄氏度加热过程中获得了翻译耐受性。hsp - 70回到细胞质与总蛋白合成的恢复有关。在热诱导耐热细胞中42摄氏度加热时也得到了类似结果。从这些结果表明，在适度温度加热过程中，hsp - 70转运到细胞核对于蛋白质合成的恢复（获得翻译耐受性）非常重要。此外，环己酰亚胺和嘌呤霉素似乎使hsp - 70转运的温度阈值降低了约1摄氏度。
