Elucldation of the mechanism for the development of thermotolerance in cells

植物发育性耐热性的分子机制尚不清楚，但许多研究表明热休克蛋白（heat shock proteins, Hsps），尤其是Hsp70参与了耐热性的发育。到目前为止，热敏蛋白与耐热性之间的关系已经在体外系统中进行了广泛的研究。我们利用小鼠鳞状细胞癌在体内研究了Hsp40/Hsp70的合成与耐热性的关系。这些在体内得到的结果与在体外得到的结果非常相似。接下来，我们研究热疗对移植小鼠肿瘤细胞凋亡的诱导作用。这些结果提示，细胞凋亡的诱导与高温引起的细胞死亡密切相关。热疗和OK-432治疗的抗肿瘤作用不能归因于诱导凋亡。此外，我们还研究了各种环境应激对哺乳动物HeLa细胞中Hsp40的诱导作用，以及Hsp40在成年小鼠组织中的组成性表达，并与Hsp70进行了比较。Hsp40和Hsp70的诱导模式非常相似。热休克是最有效的。氮杂啶羧酸、亚砷酸钠和乙醇是诱导热休克蛋白的中等胁迫。有趣的是，二硝基苯酚和双氧水可以诱导Hsp40，但不能诱导Hsp70。这些结果表明Hsp40和Hsp70之间的转录激活调控存在差异。Hsp40和Hsp70在所有小鼠组织中均有表达，但存在一定差异。然而，Hsp40在睾丸中的表达水平明显高于其他组织。这些结果表明，Hsp70和Hsp40在睾丸中普遍表达，并具有作为分子伴侣必不可少的功能，Hsp40在睾丸中除了具有分子伴侣活性外，可能还具有一些特殊的功能。

The molecular mechanism for translent developmental thermotolerance is still obscue, but many studies suggest that heat shock proteins (Hsps), especially Hsp70, are involved in the development thermotolerance. The correlation between Hsps and thermotolerance has been extensively studied in in vitro systems using cultured mammalian cells so far. We investigated the relationship between Hsp40/Hsp70 synthesis and the development of thermotolerance using mouse squamous cell carcinoma in vivo. These results obtained in vivo were very similar to those in vitro. Next We examine the induction of apotosis on hyperthermia using transplanted mouse tumor. These results suggested that the induction of apotosis is closely related to the cell death caused by hyperthermia. And the antitumor effect of hyperthermia and OK-432 therapy is not ascribable to the induction of apotosis. Furthermore we investigated the induction of mammalian Hsp40 by various enviromental stresses in HeLa cells and the constitutive expression of Hsp40 in adult mouse tissues in comparison with those of Hsp70. induction pattems of Hsp40 and Hsp70 were very similar. Heat shock was the most effective. Azetidine carboxylic acid, sodium arsenite and ethanol were moderate stresses for the induction Hsps. lnterestingly, dinitrophenol and hydrogen peroxide could induce Hsp40 but not Hsp70. These results suggest differential regulation of the transcriptional activation between Hsp40 and Hsp70. Both Hsp40 and Hsp70 were expressed in all mouse tissues examined with some variation. However, Hsp40 was expressed in the testies at remarkably higher level as compared with other tissues. These results suggested that both Hsp70 and Hsp40 are ubiquitously expressed and have essential and indispensable functions as molecular chaperones and that Hsp40 in the testies might have some specific function in addition to the molecular chaperone activity.