Endoplasmic Reticulum Stress Responses in Plants

Howell, Stephen H.

doi:10.1146/annurev-arplant-050312-120053

Cited by 447 publications

(481 citation statements)

References 125 publications

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“…that binds CCAAT box-binding factors (17,18). However, proteins occasionally fail to mature in the ER and are exported from the ER for degradation by the ubiquitin-proteasome system as part of the ERAD pathway (15,19).…”

Section: Significancementioning

confidence: 99%

“…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%

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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.

114

102

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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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Section: Significancementioning

confidence: 99%

mentioning

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.

114

102

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“…Nonetheless, modeling has identified at least one Arabidopsis protein with integrin-like structure and possible stressrelated function (11), and other proteins with small integrin similarity domains also have been identified (12). Endomembrane compartments, particularly the endoplasmic reticulum (ER), are involved in responding to cytotoxic stresses such as the accumulation of unfolded proteins (13). How endomembrane proteins may be involved in responding to water limitation, and whether this may occur via mechanisms other than the unfolded protein response, is less understood.…”

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confidence: 99%

At14a-Like1 participates in membrane-associated mechanisms promoting growth during drought in Arabidopsis thaliana

Kumar

Hsieh

Verslues

2015

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

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Limited knowledge of how plants regulate their growth and metabolism in response to drought and reduced soil water potential has impeded efforts to improve stress tolerance. Increased expression of the membrane-associated protein At14a-like1 (AFL1) led to increased growth and accumulation of the osmoprotective solute proline without negative effects on unstressed plants. Conversely, inducible RNA-interference suppression of AFL1 decreased growth and proline accumulation during low water potential while having no effect on unstressed plants. AFL1 overexpression lines had reduced expression of many stress-responsive genes, suggesting AFL1 may promote growth in part by suppression of negative regulatory genes. AFL1 interacted with the endomembrane proteins protein disulfide isomerase 5 (PDI5) and NAI2, with the PDI5 interaction being particularly increased by stress. PDI5 and NAI2 are negative regulatory factors, as pdi5, nai2, and pdi5-2nai2-3 mutants had increased growth and proline accumulation at low water potential. AFL1 also interacted with Adaptor protein2-2A (AP2-2A), which is part of a complex that recruits cargo proteins and promotes assembly of clathrin-coated vesicles. AFL1 colocalization with clathrin light chain along the plasma membrane, together with predictions of AFL1 structure, were consistent with a role in vesicle formation or trafficking. Fractionation experiments indicated that AFL1 is a peripheral membrane protein associated with both plasma membrane and endomembranes. These data identify classes of proteins (AFL1, PDI5, and NAI2) not previously known to be involved in drought signaling. AFL1-predicted structure, protein interactions, and localization all indicate its involvement in previously uncharacterized membrane-associated drought sensing or signaling mechanisms.E ven relatively mild drought that causes reduced soil water potential (ψ w ) can result in dramatically reduced plant growth and agricultural productivity. Physiological analyses have shown that plant growth is actively down-regulated during drought and is not limited by carbon supply (1-3). Reductions of growth help ensure survival by conserving water but can be undesirable for agriculture, as plant productivity is reduced more than need be if growth were less sensitive to changes in water status (3). Also, specific metabolic pathways, such as proline metabolism, are stress regulated and contribute to drought tolerance.The sensing and signaling mechanisms controlling growth and metabolic responses to drought remain unclear. Many hypotheses of how plants sense water loss center on detection of mechanical stimuli generated by loss of turgor and cell shrinkage. This includes changes in membrane shape or disruption of cell wall-cell membrane connections possibly detected by proteins, such as mechanosensitive channels or receptor-like kinases that bind cell wall components (4-9). Proteins that induce or detect membrane curvature are known in mammalian cells (10) but have been little considered in plants. Also, in analogy to mammal...

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“…Once aberrant proteins are accumulated in the ER, the cell recognizes misfolded/unfolded proteins and activates several branching pathways including UPR and ER-associated degradation (ERAD) either to restore protein folding or to eliminate aberrantly configured proteins through the ubiquitin-proteasome degradation pathway. [16][17][18][19] Thus, the ER quality control monitors conditions of ER protein folding at the ER. How plasma membrane-localized G protein function affects ER homeostasis is an open question.…”

mentioning

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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Endoplasmic Reticulum Stress Responses in Plants

Cited by 447 publications

References 125 publications

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

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

At14a-Like1 participates in membrane-associated mechanisms promoting growth during drought in Arabidopsis thaliana

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

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