Genome-wide RNAi screening identifies protein damage as a regulator of osmoprotective gene expression
Genome-wide RNAi screening identifies protein damage as a regulator of osmoprotective gene expression
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DOI：
10.1073/pnas.0602987103
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发表时间：
2006-08-08
影响因子：
11.1
通讯作者：
Strange, Kevin
中科院分区：
文献类型：
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作者：
Lamitina, Todd;Huang, Chunyi George;Strange, Kevin
压力引起的损伤的检测、稳定和修复是细胞生命的基本要求。所有细胞都会通过介导有机渗透剂（充当化学伴侣的溶质并恢复渗透稳态的溶质）积累的基因表达增加来响应渗透应激引起的失水。人们对调节动物细胞渗透保护基因表达的信号和信号传导机制知之甚少。在这里，我们发现 gpdh-1 和 gpdh-2（介导有机渗透剂甘油积累的基因）对于线虫秀丽隐杆线虫在渗透胁迫期间的生存至关重要。仅在高渗应激期间检测到由 gpdh-1 启动子 (Pgpdh-1::GFP) 驱动的 GFP 表达，但其他应激源不会诱导 GFP 表达。使用 Pgpdh-1::GFP 表达作为表型，我们通过 RNAi 喂养筛选了 16,000 个基因，并鉴定了 122 个导致 gpdh-1 表达组成型激活和甘油积累的基因。其中许多基因的功能是调节蛋白质翻译和共翻译蛋白质折叠，并靶向和降解变性蛋白质，这表明错误折叠蛋白质的积累可作为激活动物细胞中渗透保护基因表达和有机渗透剂积累的信号。与这一假设一致的是，这些蛋白质稳态基因中的 73% 已被证明可以减缓秀丽隐杆线虫中年龄依赖性蛋白质聚集。由于不同的环境压力源和多种疾病状态会导致蛋白质错误折叠，因此必须存在区分渗透引起的蛋白质损伤和其他形式的压力引起的蛋白质损伤的机制。我们的研究结果为理解这些损伤选择性机制如何发挥作用奠定了基础。
The detection, stabilization, and repair of stress-induced damage are essential requirements for cellular life. All cells respond to osmotic stress-induced water loss with increased expression of genes that mediate accumulation of organic osmolytes, solutes that function as chemical chaperones and restore osmotic homeostasis. The signals and signaling mechanisms that regulate osmoprotective gene expression in animal cells are poorly understood. Here, we show that gpdh-1 and gpdh-2, genes that mediate the accumulation of the organic osmolyte glycerol, are essential for survival of the nematode Caenorhabditis elegans during osmotic stress. Expression of GFP driven by the gpdh-1 promoter (Pgpdh-1::GFP) is detected only during hypertonic stress but is not induced by other stressors. Using Pgpdh-1::GFP expression as a phenotype, we screened 16,000 genes by RNAi feeding and identified 122 that cause constitutive activation of gpdh-1 expression and glycerol accumulation. Many of these genes function to regulate protein translation and cotranslational protein folding and to target and degrade denatured proteins, suggesting that the accumulation of misfolded proteins functions as a signal to activate osmoprotective gene expression and organic osmolyte accumulation in animal cells. Consistent with this hypothesis, 73% of these protein-homeostasis genes have been shown to slow age-dependent protein aggregation in C. elegans. Because diverse environmental stressors and numerous disease states result in protein misfolding, mechanisms must exist that discriminate between osmotically induced and other forms of stress-induced protein damage. Our findings provide a foundation for understanding how these damage-selectivity mechanisms function.