title: Conservation of IRE1-regulated bZIP74 mRNA unconventional splicing in rice (Oryza sativa L.) involved in ER stress responses.
abstract: Protein folding in the endoplasmic reticulum (ER) is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserved unfolded protein response (UPR) is initiated to mitigate the ER stress by enhancing the protein folding capability and/or accelerating the ER-associated protein degradation. Here, we report the conservation of the activation mechanism of OsbZIP74 (also known as OsbZIP50), an important ER stress regulator in monocot plant rice (Oryza sativa L.). Under normal conditions, OsbZIP74 mRNA encodes a basic leucine-zipper transcription factor with a putative transmembrane domain. When treating with ER stress-inducing agents such as tunicamycin and DTT, the conserved double stem-loop structures of OsbZIP74 mRNA are spliced out. Thereafter, the resulting new OsbZIP74 mRNA produces the nucleus-localized form of OsbZIP74 protein, eliminating the hydrophobic region. The activated form of OsbZIP74 has transcriptional activation activity in both yeast cells and Arabidopsis leaf protoplasts. The induction of OsbZIP74 splicing is much suppressed in the OsIRE1 knock-down rice plants, indicating the involvement of OsIRE1 in OsbZIP74 splicing. We also demonstrate that the unconventional splicing of OsbZIP74 mRNA is associated with heat stress and salicylic acid, which is an important plant hormone in systemic acquired resistance against pathogen or parasite.
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200433, China.
authors.forename: Sun-Jie
authors.initials: SJ
authors.lastname: Lu
authors.forename: Zheng-Ting
authors.initials: ZT
authors.lastname: Yang
authors.forename: Ling
authors.initials: L
authors.lastname: Sun
authors.forename: Le
authors.initials: L
authors.lastname: Sun
authors.forename: Ze-Ting
authors.initials: ZT
authors.lastname: Song
authors.forename: Jian-Xiang
authors.initials: JX
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017124:Conserved Sequence; D059865:Endoplasmic Reticulum Stress / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012275:Oryza / Q000235:genetics* / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D010940:Plant Proteins; D012333:RNA, Messenger