Alteration of the bZIP60/IRE1 pathway affects plant response to ER stress in Arabidopsis thaliana.
The Unfolded Protein Response (UPR) is elicited under cellular and environmental stress conditions that disrupt protein folding in the endoplasmic reticulum (ER). Through the transcriptional induction of genes encoding ER resident chaperones and proteins involved in folding, the pathway contributes to alleviating ER stress by increasing the folding capacity in the ER. Similarly to other eukaryotic systems, one arm of the UPR in Arabidopsis is set off by a non-conventional splicing event mediated by ribonuclease kinase IRE1b. The enzyme specifically targets mature bZIP60 RNA for cleavage, which results in a novel splice variant encoding a nuclear localized transcription factor. Although it is clear that this molecular switch widely affects the transcriptome, its exact role in overall plant response to stress has not been established and mutant approaches have not provided much insight. In this study, we took a transgenic approach to manipulate the pathway in positive and negative fashions. Our data show that the ER-resident chaperone BiP accumulates differentially depending on the level of activation of the pathway. In addition, phenotypes of the transgenic lines suggest that BiP accumulation is positively correlated with plant tolerance to chronic ER stress.
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada. shumbert@uoguelph.ca
Sabrina
S
Humbert
Sihui
S
Zhong
Yan
Y
Deng
Stephen H
SH
Howell
Steven J
SJ
Rothstein
D000911:Antibodies, Monoclonal; D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000378:metabolism*; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D056811:Unfolded Protein Response / Q000502:physiology*
D000911:Antibodies, Monoclonal; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D002352:Carrier Proteins; D017931:DNA Primers; C533092:bZIP60 protein, Arabidopsis; C077221:BIP protein, Arabidopsis; D011494:Protein Kinases; C446527:Ire1-1 protein, Arabidopsis