Morozov A V, Burov A V, Astakhova T M, Spasskaya D S, Margulis B A, Karpov V L
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991 Russia.
Faculty of Biology, Moscow State University, Moscow, 119991 Russia.
Mol Biol (Mosk). 2019 Jul-Aug;53(4):638-647. doi: 10.1134/S0026898419040086.
The ubiquitin-proteasome system (UPS) performs proteolysis of most intracellular proteins. The key components of the UPS are the proteasomes, multi-subunit protein complexes, playing an important role in cellular adaptation to various types of stress. We analyzed the dynamics of the proteasome activity, the content of proteasome subunits, and the expression levels of genes encoding catalytic subunits of proteasomes in the human histiocytic lymphoma U937 cell line immediately, 2, 4, 6, 9, 24, and 48 h after a heat shock (HS). The initial decrease (up to 62%) in the proteasome activity in cellular lysates was revealed, then 10 h after HS the activity began to recover. The amount of proteasomal α-subunits in the cells decreased 2 h after HS, and was restored to 24-48 h after HS. Fluctuations in the levels of mRNAs encoding proteasome catalytic subunits with the maximum expression 2 h after HS and a gradual decrease to 48 h after HS were observed. The average estimated number of mRNA copies per cell ranged from 10 for weakly to 150 for highly expressed proteasome genes. Thus, the recovery efficiency of UPS functionality after HS, which reflects the important role of proteasomes in maintaining cell homeostasis, was evaluated.
泛素-蛋白酶体系统（UPS）负责大多数细胞内蛋白质的蛋白水解。UPS的关键组成部分是蛋白酶体，即多亚基蛋白质复合物，在细胞适应各种应激类型中发挥重要作用。我们分析了人组织细胞淋巴瘤U937细胞系在热休克（HS）后即刻、2、4、6、9、24和48小时时蛋白酶体活性的动态变化、蛋白酶体亚基的含量以及编码蛋白酶体催化亚基的基因的表达水平。结果显示，细胞裂解物中蛋白酶体活性最初下降（高达62%），然后在HS后10小时活性开始恢复。HS后2小时细胞中蛋白酶体α亚基的数量减少，并在HS后24 - 48小时恢复。观察到编码蛋白酶体催化亚基的mRNA水平波动，在HS后2小时表达量最高，随后逐渐下降至HS后48小时。每个细胞中mRNA拷贝的平均估计数量范围从低表达蛋白酶体基因的10个到高表达蛋白酶体基因的150个。因此，评估了HS后UPS功能的恢复效率，这反映了蛋白酶体在维持细胞稳态中的重要作用。
