Delpino A, Spinsanti P, Mattei E, Mileo A M, Vismara D, Ferrini U
Istituto Regina Elena per lo Studio e la Cura dei Tumori, Laboratorio di Biofisica, Roma, Italy.
Melanoma Res. 1992 Dec;2(5-6):369-75. doi: 10.1097/00008390-199212000-00011.
Following severe hyperthermic treatment M-14 cells synthesize at high rate a new protein of about 66 kD, in addition to the three well known major HSPs (HSP 28, HSP 70 and HSP 90). This 66 kD protein is constitutively expressed at low levels and its rate of synthesis is not enhanced by mild hyperthermic exposures (40 degrees C for 2-4 h; 42 degrees C for 1-3 h), sufficient to induce the three major HSPs. The 66 kD protein is induced whenever the thermal dose administered to cells attains a threshold, roughly corresponding to a 50% reduction in survival. The 66 kDa protein is not induced by a variety of compounds (disulfiram, arsenate, cadmium) able to elicit a stress response in M-14 cells, as indicated by enhanced synthesis of the three major HSPs. Once induced by a treatment at 45 degrees C for 15 min, the rate of synthesis of the 66 kD protein remains above the control level for 16-20 h during recovery from the stress, while the synthesis of HSP 70 is shut off between 8 and 12 h. Immunoblotting and immunoprecipitation studies showed that the 66 kD protein shares immunological determinant(s) with HSP 70. Pulse-chase experiments demonstrated that the 66 kD protein is not a degradation product or a late post-transcriptional modification of HSP 70. It is proposed that the 66 kD protein is a previously unrecognized heat shock protein (HSP 66), characterized by an unusually high threshold for its induction.
在进行严重热疗后，M - 14细胞除了合成三种众所周知的主要热休克蛋白（HSP 28、HSP 70和HSP 90）外，还高速合成一种约66 kD的新蛋白。这种66 kD的蛋白在基础状态下低水平表达，其合成速率不会因轻度热暴露（40℃处理2 - 4小时；42℃处理1 - 3小时）而增强，而这些轻度热暴露足以诱导三种主要热休克蛋白的合成。每当给予细胞的热剂量达到一个阈值时，66 kD的蛋白就会被诱导产生，该阈值大致对应于细胞存活率降低50%。如三种主要热休克蛋白合成增强所示，多种能够在M - 14细胞中引发应激反应的化合物（双硫仑、砷酸盐、镉）并不会诱导66 kD蛋白的产生。一旦经45℃处理15分钟诱导产生后，在从应激状态恢复的过程中，66 kD蛋白的合成速率在16 - 20小时内一直高于对照水平，而HSP 70的合成在8至12小时之间停止。免疫印迹和免疫沉淀研究表明，66 kD蛋白与HSP 70具有共同的免疫决定簇。脉冲追踪实验证明，66 kD蛋白不是HSP 70的降解产物或转录后晚期修饰产物。有人提出，66 kD蛋白是一种先前未被识别的热休克蛋白（HSP 66），其诱导阈值异常高。
