HSP70 ACCELERATES THE RECOVERY OF NUCLEOLAR MORPHOLOGY AFTER HEAT-SHOCK
HSP70 ACCELERATES THE RECOVERY OF NUCLEOLAR MORPHOLOGY AFTER HEAT-SHOCK
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DOI：
10.1002/j.1460-2075.1984.tb02264.x
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发表时间：
1984-01-01
期刊：
影响因子：
11.4
通讯作者：
PELHAM, HRB
中科院分区：
文献类型：
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作者：
PELHAM, HRB
热休克蛋白70是一种主要的热休克蛋白，由许多生物体的细胞在应激反应中合成。果蝇hsp 70基因在小鼠L细胞和猴COS细胞中表达，并用单克隆抗体进行免疫荧光检测。Hsp 70主要但不完全存在于非应激细胞的细胞核中。在短时间的热休克后的几个小时内，它强烈地集中在核仁中。这样的热休克会短暂地损害核仁：它们的形态变化以及核糖体的组装和输出被阻断几个小时。这种阻断可以通过加入放线菌素D来观察：在正常条件下，前核糖体被赶出核仁，后者急剧收缩，但在热休克细胞中没有看到这种收缩。用合适的表达质粒转染未应激的COS细胞，可以在其中产生高水平的hsp-70。这样的细胞在热休克后比未转染的细胞显示出更快的核仁形态恢复。热休克不能阻止它们的核仁在放线菌素存在下收缩，这表明当存在预合成的HSP-70时，核糖体输出也迅速恢复。HSP-70的一个重要功能可能是催化热休克后受损的前核糖体和其他RNP [核糖核蛋白]的重组。
The major heat-shock protein, hsp70, is synthesized by cells of many organisms in response to stress. Drosophila hsp70 was expressed from cloned genes in mouse L cells and monkey COS cells and detected by immunofluorescence using monoclonal antibodies. Hsp70 is found mostly but not exclusively in the nucleus of unstressed cells. For several hours after a short heat shock it is strongly concentrated in nucleoli. Nucleoli are transiently damaged by such a heat shock: their morphology changes and assembly and export of ribosomes is blocked for several hours. This block can be visualized by addition of actinomycin D: under normal conditions pre-ribosomes are chased out of nucleoli, and the latter shrink dramatically, but no such shrinking is seen in heat-shocked cells. High levels of hsp-70 can be produced in unstressed COS cells by transfecting them with an appropriate expression plasmid. Such cells show a more rapid recovery of nucleolar morphology following a heat shock than do untransfected cells. Heat shock does not prevent shrinkage of their nucleoli in the presence of actinomycin, which indicates that ribosome export also recovers rapidly when pre-synthesized hsp-70 is present. An important function of hsp-70 may be to catalyze reassembly of damaged pre-ribosomes and other RNP [ribonucleoprotein] after heat shock.