ACTIVATION OF HUMAN HEAT-SHOCK GENES IS ACCOMPANIED BY OLIGOMERIZATION, MODIFICATION, AND RAPID TRANSLOCATION OF HEAT-SHOCK TRANSCRIPTION FACTOR HSF1
ACTIVATION OF HUMAN HEAT-SHOCK GENES IS ACCOMPANIED BY OLIGOMERIZATION, MODIFICATION, AND RAPID TRANSLOCATION OF HEAT-SHOCK TRANSCRIPTION FACTOR HSF1
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DOI：
10.1128/mcb.13.4.2486
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发表时间：
1993-04-01
影响因子：
5.3
通讯作者：
VOELLMY, R
中科院分区：
文献类型：
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作者：
BALER, R;DAHL, G;VOELLMY, R
热休克（hsp）基因的转录活性由一种热激活的组特异性转录因子(s)控制，该转录因子识别元件NGAAN的反向重复序列。迄今为止，两种人类因子HSF1和HSF2的基因已被分离出来。为了确定它们的性质以及它们在热应激激活过程中的变化，我们制备了针对这些因子的多克隆抗体。使用这些工具，我们已经证明人类HeLa细胞组成性地合成HSF1，但我们无法检测到HSF2。在非应激细胞中，HSF1主要存在于表观分子质量约为200 kDa的复合物中，不能与DNA结合。热处理诱导HSF1的表观分子质量转移到约700 kDa，同时获得dna结合能力。交联实验表明，这种复合物大小的变化可能反映了HSF1单体的三聚化。在非洲爪蟾卵母细胞中表达的人HSF1不结合DNA，但在同一温度下的热处理过程中，DNA结合活性的降低以及HSF1的寡聚化发生在该生物体中诱导hsp基因表达的过程中，这表明一种保守的非洲爪蟾蛋白在这一调控中起作用。失活HSF1存在于人细胞的细胞质中；激活后，它迅速转移到可溶的核部分，此后不久，它与核球结合。在热休克中，可能已经在非应激细胞中进行翻译后修饰的可活化HSF1进行进一步修饰。这些不同的过程提供了热休克蛋白基因表达的多个调控点。
Transcriptional activity of heat shock (hsp) genes is controlled by a heat-activated, group-specific transcription factor(s) recognizing arrays of inverted repeats of the element NGAAN. To date genes for two human factors, HSF1 and HSF2, have been isolated. To define their properties as well as the changes they undergo during heat stress activation, we prepared polyclonal antibodies to these factors. Using these tools, we have shown that human HeLa cells constitutively synthesize HSF1, but we were unable to detect HSF2. In unstressed cells HSF1 is present mainly in complexes with an apparent molecular mass of about 200 kDa, unable to bind to DNA. Heat treatment induces a shift in the apparent molecular mass of HSF1 to about 700 kDa, concomitant with the acquisition of DNA-binding ability. Cross-linking experiments suggest that this change in complex size may reflect the trimerization of monomeric HSF1. Human HSF1 expressed in Xenopus oocytes does not bind DNA, but derepression of DNA-binding activity, as well as oligomerization of HSF1, occurs during heat treatment at the same temperature at which hsp gene expression is induced in this organism, suggesting that a conserved Xenopus protein(s) plays a role in this regulation. Inactive HSF1 resides in the cytoplasm of human cells; on activation it rapidly translocates to a soluble nuclear fraction, and shortly thereafter it becomes associated with the nuclear pellet. On heat shock, activatable HSF1, which might already have been posttranslationally modified in the unstressed cell, undergoes further modification. These different processes provide multiple points of regulation of hsp gene expression.