title: Characterization of IRE1 ribonuclease-mediated mRNA decay in plants using transient expression analyses in rice protoplasts.
abstract: In some eukaryotes, endoplasmic reticulum (ER) stress induces regulated inositol-requiring enzyme 1 (IRE1)-dependent decay (RIDD) of mRNAs. Recently, the expression levels of the mRNAs encoding some secretory proteins were reported to be downregulated by RIDD in the vegetative tissues of plants. However, the characteristics of plant RIDD have been insufficiently investigated due to difficulty of in planta analyses. Here, the RIDD susceptibilities of various mRNAs that are difficult to analyze in planta were examined using transient expression analyses of rice protoplasts. In this system, the mRNAs encoding three rice seed storage proteins (SSPs) - namely α-globulin, 16-kDa prolamin and 10-kDa prolamin - were downregulated in response to ER stress. The rapid ER stress-induced degradation of these mRNAs was repressed in cells in which the ribonuclease activity of IRE1 was specifically abolished by genome editing, suggesting that the mRNAs encoding certain SSPs are strong targets of RIDD. Furthermore, we investigated whether these RIDD targets are substrates of the IRE1 ribonuclease using a recombinant IRE1 protein, and identified candidate IRE1-mediated cleavage sites. Overall, the results demonstrate the existence of a post-transcriptional mechanism of regulation of SSPs, and illustrate the basic and multifaceted characteristics of RIDD in higher plants.
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Shimpei
authors.initials: S
authors.lastname: Hayashi
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Yuhya
authors.initials: Y
authors.lastname: Wakasa
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Kenjirou
authors.initials: K
authors.lastname: Ozawa
authors.affiliation: Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Takaiwa
mesh_terms: D000510:Alpha-Globulins / Q000235:genetics / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D055315:Prolamins / Q000235:genetics / Q000378:metabolism; D011523:Protoplasts; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D055314:Seed Storage Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000510:Alpha-Globulins; D055315:Prolamins; D012333:RNA, Messenger; D055314:Seed Storage Proteins; D012260:Ribonucleases
keywords: Oryza sativa; endoplasmic reticulum (ER) stress; regulated IRE1-dependent decay; seed storage proteins; unfolded protein response