Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) in plants

• Published in: Protoplasma Vol. 253; no. 3; pp. 753 - 764
• Main Authors: Wan, Shucen, Liwen Jiang
• Format: Journal Article Book Review
• Language: English
• Published: Vienna Springer Vienna 01.05.2016; Springer Nature B.V
• Subjects: Activating Transcription Factor 6 - metabolism; Arabidopsis Proteins - metabolism; Autophagy - physiology; Basic-Leucine Zipper Transcription Factors - metabolism; Biomedical and Life Sciences; Cell Biology; cell death; endoplasmic reticulum; Endoplasmic Reticulum Stress - physiology; homeostasis; Life Sciences; monitoring; Plant Sciences; Plants - genetics; Plants - metabolism; protein folding; proteins; quality control; Review Article; RNA Splicing; transcription factors; unfolded protein response; Unfolded Protein Response - physiology; Zoology; ER stress; Plant; ATF6; UPR; IRE1
• ISSN: 0033-183X; 1615-6102
• DOI: 10.1007/s00709-015-0842-1

Being a major factory for protein synthesis, assembly, and export, the endoplasmic reticulum (ER) has a precise and robust ER quality control (ERQC) system monitoring its product line. However, when organisms are subjected to environmental stress, whether biotic or abiotic, the levels of misfolded proteins may overwhelm the ERQC system, tilting the balance between the capacity of and demand for ER quality control and resulting in a scenario termed ER stress. Intense or prolonged ER stress may cause damage to the ER as well as to other organelles, or even lead to cell death in extreme cases. To avoid such serious consequences, cells activate self-rescue programs to restore protein homeostasis in the ER, either through the enhancement of protein-folding and degradation competence or by alleviating the demands for such reactions. These are collectively called the unfolded protein response (UPR). Long investigated in mammalian cells and yeasts, the UPR is also of great interest to plant scientists. Among the three branches of UPR discovered in mammals, two have been studied in plants with plant homologs existing of the ER-membrane-associated activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1 (IRE1). This review discusses the molecular mechanisms of these two types of UPR in plants, as well as the consequences of insufficient UPR, with a focus on experiments using model plants.