Affiliation:
1. State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
2. Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China
3. Institution of Fruit Tree Research Guangdong Academy of Agricultural Sciences Guangzhou 510640 China
Abstract
Summary
Sphingolipids are cell membrane components and signaling molecules that induce endoplasmic reticulum (ER) stress responses, but the underlying mechanism is unknown. Orosomucoid proteins (ORMs) negatively regulate serine palmitoyltransferase activity, thus helping maintain proper sphingolipid levels in humans, yeast, and plants.
In this report, we explored the roles of ORMs in regulating ER stress in Arabidopsis thaliana.
Loss of ORM1 and ORM2 function caused constitutive activation of the unfolded protein response (UPR), as did treatment with the ceramide synthase inhibitor Fumonisin B1 (FB1) or ceramides. FB1 treatment induced the transcription factor bZIP28 to relocate from the ER membrane to the nucleus. The transcription factor WRKY75 positively regulates the UPR and physically interacted with bZIP28. We also found that the orm mutants showed impaired ER‐associated degradation (ERAD), blocking the degradation of misfolded MILDEW RESISTANCE LOCUS‐O 12 (MLO‐12). ORM1 and ORM2 bind to EMS‐MUTAGENIZED BRI1 SUPPRESSOR 7 (EBS7), a plant‐specific component of the Arabidopsis ERAD complex, and regulate its stability. These data strongly suggest that ORMs in the ER membrane play vital roles in the UPR and ERAD pathways to prevent ER stress in Arabidopsis.
Our results reveal that ORMs coordinate sphingolipid homeostasis with ER quality control and play a role in stress responses.
Funder
China Postdoctoral Science Foundation
National Natural Science Foundation of China
Natural Science Foundation of Guangdong Province
Cited by
1 articles.
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