State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China.
J Integr Plant Biol. 2017 Jul;59(7):506-521. doi: 10.1111/jipb.12544.
Abiotic stresses often disrupt protein folding and induce endoplasmic reticulum (ER) stress. There is a sophisticated ER quality control (ERQC) system to mitigate the effects of malfunctioning proteins and maintain ER homeostasis. The accumulation of misfolded proteins in the ER activates the unfolded protein response (UPR) to enhance ER protein folding and the degradation of misfolded proteins mediate by ER-associated degradation (ERAD). That ERQC reduces abiotic stress damage has been well studied in mammals and yeast. However, in plants, both ERAD and UPR have been studied separately and found to be critical for plant abiotic stress tolerance. In this study, we discovered that UPR-associated transcription factors AtbZIP17, AtbZIP28 and AtbZIP60 responded to tunicamycin (TM) and NaCl induced ER stress and subsequently enhanced Arabidopsis thaliana abiotic stress tolerance. They regulated the expression level of ER chaperones and the HRD1-complex components. Moreover, overexpression of AtbZIP17, AtbZIP28 and AtbZIP60 could restore stress tolerance via ERAD in the HRD1-complex mutant hrd3a-2, which suggested that UPR and ERAD have an interactive mechanism in Arabidopsis.
非生物胁迫通常会破坏蛋白质折叠,并诱导内质网(ER)应激。有一种复杂的内质网质量控制(ERQC)系统,可以减轻功能失调蛋白质的影响,维持 ER 稳态。错误折叠蛋白质在 ER 中的积累会激活未折叠蛋白反应(UPR),以增强 ER 蛋白折叠,并通过内质网相关降解(ERAD)降解错误折叠蛋白质。在哺乳动物和酵母中,已经对 ERQC 减轻非生物胁迫损伤进行了深入研究。然而,在植物中,ERAD 和 UPR 分别进行了研究,发现它们对植物的非生物胁迫耐受性至关重要。在这项研究中,我们发现 UPR 相关转录因子 AtbZIP17、AtbZIP28 和 AtbZIP60 响应衣霉素(TM)和 NaCl 诱导的 ER 应激,随后增强了拟南芥的非生物胁迫耐受性。它们调节 ER 伴侣和 HRD1 复合物成分的表达水平。此外,AtbZIP17、AtbZIP28 和 AtbZIP60 的过表达可以通过 hrd3a-2 中 ERAD 恢复应激耐受性,这表明 UPR 和 ERAD 在拟南芥中具有相互作用机制。