title: AtIRE1A/AtIRE1B and AGB1 independently control two essential unfolded protein response pathways in Arabidopsis.
abstract: The endoplasmic reticulum (ER) has the ability to maintain the balance between demand for and synthesis of secretory proteins. To ensure protein-folding homeostasis in the ER, cells invoke signaling pathways known as the unfolded protein response (UPR). To initiate UPR, yeasts largely rely on a conserved sensor, IRE1. In metazoans, there are at least three independent UPR signalling pathways. Some UPR transducers have been identified in plants, but no genetic interaction among them has yet been examined. The Arabidopsis genome encodes two IRE1 sequence homologs, AtIRE1A and AtIRE1B. Here we provide evidence that AtIRE1A and AtIRE1B have overlapping functions that are essential for the plant UPR. A double mutant of AtIRE1A and AtIRE1B, atire1a atire1b, showed reduced ER stress tolerance and a compromised UPR activation phenotype. We have also established that Arabidopsis AGB1, a subunit of the ubiquitous heterotrimeric GTP-binding protein family, and AtIRE1A/AtIRE1B independently control two essential plant UPR pathways. By demonstrating that atire1a atire1b has a short root phenotype that is enhanced by an agb1 loss-of-function mutation, we have identified a role for UPR transducers in organ growth regulation.
authors.affiliation: Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Yani
authors.initials: Y
authors.lastname: Chen
authors.forename: Federica
authors.initials: F
authors.lastname: Brandizzi
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D009154:Mutation; D009928:Organ Specificity; D010641:Phenotype; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D056811:Unfolded Protein Response / Q000235:genetics*
chemical_list: C089590:AGB1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D044387:GTP-Binding Protein beta Subunits; D011494:Protein Kinases; C446527:Ire1-1 protein, Arabidopsis; C446528:Ire1-2 protein, Arabidopsis