Plant transducers of the endoplasmic reticulum unfolded protein response

Iwata, Yuji; Koizumi, Nozomu

doi:10.1016/j.tplants.2012.06.014

Cited by 147 publications

(146 citation statements)

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“…Contribution of RIDD to protein synthesis needs to be carefully considered with further experimental data. Considering the lack of evidence of PERK homologs in plants (4), RIDD may have a more important function in the UPR in plants than in animals. Very recently, RIDD was reported in fission yeast, although it has not been reported in budding yeast (40).…”

Section: Discussionmentioning

confidence: 99%

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Defects in IRE1 enhance cell death and fail to degrade mRNAs encoding secretory pathway proteins in the Arabidopsis unfolded protein response

Mishiba

Nagashima

Suzuki

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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167

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The unfolded protein response (UPR) is a cellular response highly conserved in eukaryotes to obviate accumulation of misfolded proteins in the endoplasmic reticulum (ER). Inositol-requiring enzyme 1 (IRE1) catalyzes the cytoplasmic splicing of mRNA encoding bZIP transcription factors to activate the UPR signaling pathway. Arabidopsis IRE1 was recently shown to be involved in the cytoplasmic splicing of bZIP60 mRNA. In the present study, we demonstrated that an Arabidopsis mutant with defects in two IRE1 paralogs showed enhanced cell death upon ER stress compared with a mutant with defects in bZIP60 and wild type, suggesting an alternative function of IRE1 in the UPR. Analysis of our previous microarray data and subsequent quantitative PCR indicated degradation of mRNAs encoding secretory pathway proteins by tunicamycin, DTT, and heat in an IRE1-dependent manner. The degradation of mRNAs localized to the ER during the UPR was considered analogous to a molecular mechanism referred to as the regulated IRE1-dependent decay of mRNAs reported in metazoans. Another microarray analysis conducted in the condition repressing transcription with actinomycin D and a subsequent Gene Set Enrichment Analysis revealed the regulated IRE1-dependent decay of mRNAs-mediated degradation of a significant portion of mRNAs encoding the secretory pathway proteins. In the mutant with defects in IRE1, genes involved in the cytosolic protein response such as heat shock factor A2 were upregulated by tunicamycin, indicating the connection between the UPR and the cytosolic protein response.heat stress | protein folding | bioinformatics T he unfolded protein response (UPR) or the endoplasmic reticulum (ER) stress response is a cellular response that is highly conserved in eukaryotes to obviate accumulation of misfolded proteins and to alleviate protein overload in the ER (1-3). Inositol-requiring enzyme 1 (IRE1), which is the primary transducer of the UPR in various organisms, catalyzes the unconventional or cytoplasmic splicing of mRNAs encoding bZIP transcription factors to up-regulate the UPR-related genes, such as genes for the ER-resident molecular chaperones, through its ribonuclease domain. The cytoplasmic splicing by IRE1 activates the bZIP transcription factors HAC1, XBP1, and bZIP60 in yeast, animals, and plants, respectively, by producing active proteins. Although the fundamental mechanism of the cytoplasmic splicing by IRE1 appears to be highly conserved, the mechanism of transcription factor activation is diverse among organisms (4).In addition to the cytoplasmic splicing of mRNAs for transcription factors, other functions of metazoan IRE1 have been reported. One such function is the degradation of mRNAencoding proteins in the secretory pathway referred to as regulated IRE1-dependent decay (RIDD) (5-7). RIDD is considered to contribute to reducing the amount of proteins entering the ER in the UPR. The metazoan UPR has an alternative mechanism to reduce the amount of protein entering the ER, and this mechanism is regulated by PKR-li...

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Section: Discussionmentioning

confidence: 99%

“…The cytoplasmic splicing by IRE1 activates the bZIP transcription factors HAC1, XBP1, and bZIP60 in yeast, animals, and plants, respectively, by producing active proteins. Although the fundamental mechanism of the cytoplasmic splicing by IRE1 appears to be highly conserved, the mechanism of transcription factor activation is diverse among organisms (4).…”

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confidence: 99%

Defects in IRE1 enhance cell death and fail to degrade mRNAs encoding secretory pathway proteins in the Arabidopsis unfolded protein response

Mishiba

Nagashima

Suzuki

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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167

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“…Different membrane-associated TFs (MTFs) transduce stress signals to the nucleus. Typically, two MTFs, bZIP28 and bZIP60, play vital roles in ensuring cell survival during ER stress in plants (16,17). These MTFs up-regulate genes encoding components of the ER protein-folding machinery, including luminal binding protein (BIP), calnexin (CNX), calreticulin (CRT), and protein disulfide isomerase (PDI).…”

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confidence: 99%

HY5, a positive regulator of light signaling, negatively controls the unfolded protein response inArabidopsis

Nawkar

Kang

Maibam

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Light influences essentially all aspects of plant growth and development. Integration of light signaling with different stress response results in improvement of plant survival rates in ever changing environmental conditions. Diverse environmental stresses affect the protein-folding capacity of the endoplasmic reticulum (ER), thus evoking ER stress in plants. Consequently, the unfolded protein response (UPR), in which a set of molecular chaperones is expressed, is initiated in the ER to alleviate this stress. Although its underlying molecular mechanism remains unknown, light is believed to be required for the ER stress response. In this study, we demonstrate that increasing light intensity elevates the ER stress sensitivity of plants. Moreover, mutation of the ELONGATED HYPOCOTYL 5 (HY5), a key component of light signaling, leads to tolerance to ER stress. This enhanced tolerance of hy5 plants can be attributed to higher expression of UPR genes. HY5 negatively regulates the UPR by competing with basic leucine zipper 28 (bZIP28) to bind to the G-box-like element present in the ER stress response element (ERSE). Furthermore, we found that HY5 undergoes 26S proteasome-mediated degradation under ER stress conditions. Conclusively, we propose a molecular mechanism of crosstalk between the UPR and light signaling, mediated by HY5, which positively mediates light signaling, but negatively regulates UPR gene expression.endoplasmic reticulum stress | light signaling | protein-folding capacity | crosstalk | unfolded protein response

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“…21,22 Approximately three hundreds genes are upregulated upon the tunicamycin-induced ER stress in Arabidopsis. 23 To investigate whether phenotype of agb1-3 upon the tunicamycin treatment is relevant to UPR pathway, we compared expression profiles of key genes in the wild-type and the agb1-3 plants.…”

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confidence: 99%

Heterotrimeric G protein subunits differentially respond to endoplasmic reticulum stress in Arabidopsis

Cho

Iwasa

et al. 2015

Plant Signaling & Behavior

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Plant transducers of the endoplasmic reticulum unfolded protein response

Cited by 147 publications

References 100 publications

Defects in IRE1 enhance cell death and fail to degrade mRNAs encoding secretory pathway proteins in the Arabidopsis unfolded protein response

Defects in IRE1 enhance cell death and fail to degrade mRNAs encoding secretory pathway proteins in the Arabidopsis unfolded protein response

HY5, a positive regulator of light signaling, negatively controls the unfolded protein response inArabidopsis

Heterotrimeric G protein subunits differentially respond to endoplasmic reticulum stress in Arabidopsis

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