Zou J, Salminen W F, Roberts S M, Voellmy R
Department of Biochemistry & Molecular Biology, University of Miami School of Medicine, FL 33136, USA.
Cell Stress Chaperones. 1998 Jun;3(2):130-41. doi: 10.1379/1466-1268(1998)003<0130:cbgoat>2.3.co;2.
The heat shock protein (Hsp) response is induced by heat shock and a large variety of different chemicals. Searching for a common denominator of these different inducers, we and others developed the notion that all inducers may generate abnormally folded, i.e. non-native, proteins, and that such non-native proteins may trigger the Hsp response. Experimentation prompted by this notion resulted, for example, in the demonstration that chemically denatured proteins, introduced in cells by microinjection, can activate the response. Based on the chemical nature of inducers and on results reported from several studies, we hypothesized that inducers of the Hsp response may be generally capable of triggering oxidation of non-protein thiols, particularly glutathione. Such oxidation is known to lead to formation of glutathione-protein mixed disulfides and protein-protein disulfides. Presumably, thiol adduction and cross-linking would affect the structure of proteins involved, resulting in unfolding of a fraction of these proteins, causing heat shock factor (Hsf) activation. To test the feasibility of this hypothesis, thirteen different inducers were selected, and it was shown that all chemical inducers as well as heat shock cause drastic oxidation of glutathione under conditions under which they induce HSE DNA-binding activity. Under the same conditions, all chemical inducers and heat shock also cause trimerization of Hsf1. For several inducers, it was also shown that they enhance thiol oxidation of proteins. Finally, in vitro experiments support the notion that activation of Hsf1 does not require oxidation of the factor itself or of its coregulators. These results are in complete agreement with the above hypothesis.
热休克蛋白（Hsp）应答是由热休克和多种不同化学物质诱导产生的。为了寻找这些不同诱导剂的共同特征，我们和其他研究人员提出了这样一种观点：所有诱导剂可能都会产生异常折叠的蛋白质，即非天然蛋白质，而这种非天然蛋白质可能会触发Hsp应答。基于这一观点进行的实验表明，例如，通过显微注射引入细胞内的化学变性蛋白质能够激活这种应答。根据诱导剂的化学性质以及多项研究报告的结果，我们推测Hsp应答的诱导剂可能普遍能够引发非蛋白质硫醇（尤其是谷胱甘肽）的氧化。已知这种氧化会导致谷胱甘肽 - 蛋白质混合二硫键和蛋白质 - 蛋白质二硫键的形成。据推测，硫醇加成和交联会影响相关蛋白质的结构，导致这些蛋白质中的一部分发生解折叠，从而引起热休克因子（Hsf）的激活。为了验证这一假设的可行性，我们选择了13种不同的诱导剂，并发现所有化学诱导剂以及热休克在诱导热休克元件（HSE）DNA结合活性的条件下都会导致谷胱甘肽的剧烈氧化。在相同条件下，所有化学诱导剂和热休克还会导致热休克因子1（Hsf1）三聚化。对于几种诱导剂，研究还表明它们会增强蛋白质的硫醇氧化。最后，体外实验支持了热休克因子1的激活不需要该因子自身或其共调节因子氧化的观点。这些结果与上述假设完全一致。
