Variation in ambient growth temperature can cause changes in normal animal physiology and cellular functions such as control of protein homeostasis. A key mechanism for maintaining proteostasis is the selective degradation of polyubiquitinated proteins, mediated by the ubiquitin-proteasome system (UPS). It is still largely unsolved how temperature changes affect the UPS at the organismal level. Caenorhabditis elegans nematodes are normally bred at 20 °C, but for some experimental conditions, 25 °C is often used. We studied the effect of 25 °C on C. elegans UPS by measuring proteasome activity and polyubiquitinated proteins both in vitro in whole animal lysates and in vivo in tissue-specific transgenic reporter strains. Our results show that an ambient temperature shift from 20 to 25 °C increases the UPS activity in the intestine, but not in the body wall muscle tissue, where a concomitant accumulation of polyubiquitinated proteins occurs. These changes in the UPS activity and levels of polyubiquitinated proteins were not detectable in whole animal lysates. The exposure of transgenic animals to 25 °C also induced ER stress reporter fluorescence, but not the fluorescence of a heat shock responsive reporter, albeit detection of a mild induction in hsp-16.2 mRNA levels. In conclusion, C. elegans exhibits tissue-specific responses of the UPS as an organismal strategy to cope with a rise in ambient temperature.

中文翻译：

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温度对蛋白酶体功能的组织特异性影响。

环境生长温度的变化会引起正常动物生理和细胞功能的改变，例如蛋白质稳态的控制。维持蛋白稳定的关键机制是由泛素-蛋白酶体系统（UPS）介导的多泛素化蛋白的选择性降解。温度变化如何影响机体上的UPS仍在很大程度上尚未解决。秀丽隐杆线虫线虫通常在20°C下繁殖，但在某些实验条件下，通常使用25°C。我们研究了25°C对秀丽隐杆线虫的影响通过在体外在整个动物裂解物中和体内在组织特异性转基因报道菌株中测量蛋白酶体活性和多聚泛素化蛋白来进行UPS。我们的结果表明，环境温度从20到25°C的变化会增加肠道中UPS的活性，但不会引起体壁肌肉组织中UPS活性的增加，而在体壁肌肉组织中会发生聚泛素化蛋白的积累。在整个动物裂解物中无法检测到UPS活性和多聚泛素化蛋白水平的这些变化。将转基因动物暴露于25°C也会诱导ER应激报告基因荧光，但不会引起热休克反应报告基因的荧光，尽管检测到hsp-16.2 mRNA水平有轻度诱导。总之，秀丽隐杆线虫 展示了UPS的组织特异性反应，作为应对环境温度升高的一种有机策略。