An endoplasmic reticulum stress response in Arabidopsis is mediated by proteolytic processing and nuclear relocation of a membrane-associated transcription factor, bZIP28.
Stresses leading to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) elicit a highly conserved ER stress response in plants called the unfolded protein response (UPR). While the response itself is well documented in plants, the components of the signaling pathway are less well known. We have identified three membrane-associated basic domain/leucine zipper (bZIP) factors in Arabidopsis thaliana that are candidates for ER stress sensors/transducers. One of these factors, bZIP28, an ER-resident transcription factor, is activated in response to treatment by tunicamycin (TM), an agent that blocks N-linked protein glycosylation. Following TM treatment, bZIP28 is processed, releasing its N-terminal, cytoplasm-facing domain, which is translocated to the nucleus. Expression of a truncated form of bZIP28, containing only the cytoplasmic domain of the protein, upregulated the expression of ER stress response genes in the absence of stress conditions. Thus, bZIP28 serves as a sensor/transducer in Arabidopsis to mediate ER stress responses related to UPR.
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006031:Glycosylation / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D008954:Models, Biological; D017434:Protein Structure, Tertiary; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014415:Tunicamycin / Q000494:pharmacology
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; C530495:bZIP28 protein, Arabidopsis; D014415:Tunicamycin; D049452:Green Fluorescent Proteins