a Department of Biology , Washington University in St. Louis , St. Louis , MO , USA.
Autophagy. 2018;14(11):2029-2031. doi: 10.1080/15548627.2018.1515531. Epub 2018 Sep 11.
Autophagic degradation of proteasomes (termed proteaphagy) is a conserved mechanism by which cells eliminate excess or damaged particles. This clearance is induced rapidly when organisms are starved for nitrogen and, because proteasomes are highly abundant, their breakdown likely makes an important contribution to the amino acid pools necessary for survival. By contrast, our recent studies found that proteasomes are not degraded in response to carbon starvation, even though bulk macroautophagy is similarly activated. Instead, carbon starvation induces sequestration of proteasomes into membrane-less cytoplasmic condensates previously termed proteasome storage granules (PSGs), which protect proteasomes from autophagic degradation. Preserving proteasomes in PSGs enhances the ability of yeast cells to recover from a variety of stresses, implying that rapid remobilization of stored proteasomes when conditions improve is advantageous to cell fitness. Consequently, the choice of whether to save or degrade proteasomes can profoundly impact cell survival.
自噬性蛋白酶体降解（称为蛋白酶体自噬）是细胞清除多余或受损颗粒的一种保守机制。当生物体因氮饥饿而迅速诱导这种清除时，由于蛋白酶体含量非常丰富，其分解可能对生存所需的氨基酸池做出重要贡献。相比之下，我们最近的研究发现，蛋白酶体不会因碳饥饿而降解，尽管大量的巨自噬也被激活。相反，碳饥饿诱导蛋白酶体被隔离到无膜细胞质凝聚物中，这些凝聚物以前被称为蛋白酶体储存颗粒（PSG），它们可以保护蛋白酶体免受自噬降解。将蛋白酶体保存在 PSG 中可以增强酵母细胞从各种应激中恢复的能力，这意味着当条件改善时，储存的蛋白酶体快速再循环有利于细胞适应性。因此，选择保存还是降解蛋白酶体可以深刻影响细胞的生存。
