scholarly journals Inadequate BiP availability defines endoplasmic reticulum stress

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Milena Vitale ◽  
Anush Bakunts ◽  
Andrea Orsi ◽  
Federica Lari ◽  
Laura Tadè ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Heavy Chain ◽  
Target Gene ◽  
Immunoglobulin M ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Secretory Immunoglobulin

How endoplasmic reticulum (ER) stress leads to cytotoxicity is ill-defined. Previously we showed that HeLa cells readjust homeostasis upon proteostatically driven ER stress, triggered by inducible bulk expression of secretory immunoglobulin M heavy chain (μs) thanks to the unfolded protein response (UPR; Bakunts et al., 2017). Here we show that conditions that prevent that an excess of the ER resident chaperone (and UPR target gene) BiP over µs is restored lead to µs-driven proteotoxicity, i.e. abrogation of HRD1-mediated ER-associated degradation (ERAD), or of the UPR, in particular the ATF6α branch. Such conditions are tolerated instead upon removal of the BiP-sequestering first constant domain (CH1) from µs. Thus, our data define proteostatic ER stress to be a specific consequence of inadequate BiP availability, which both the UPR and ERAD redeem.

scholarly journals Ratiometric sensing of BiP-client versus BiP levels by the unfolded protein response determines its signaling amplitude

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Anush Bakunts ◽  
Andrea Orsi ◽  
Milena Vitale ◽  
Angela Cattaneo ◽  
Federica Lari ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Heavy Chain ◽  
Immunoglobulin M ◽  
Unfolded Protein ◽  
Er Chaperone ◽  
Ideal System ◽  
The Unfolded Protein Response ◽  
Protein Response

Insufficient folding capacity of the endoplasmic reticulum (ER) activates the unfolded protein response (UPR) to restore homeostasis. Yet, how the UPR achieves ER homeostatic readjustment is poorly investigated, as in most studies the ER stress that is elicited cannot be overcome. Here we show that a proteostatic insult, provoked by persistent expression of the secretory heavy chain of immunoglobulin M (µs), is well-tolerated in HeLa cells. Upon µs expression, its levels temporarily eclipse those of the ER chaperone BiP, leading to acute, full-geared UPR activation. Once BiP is in excess again, the UPR transitions to chronic, submaximal activation, indicating that the UPR senses ER stress in a ratiometric fashion. In this process, the ER expands about three-fold and becomes dominated by BiP. As the UPR is essential for successful ER homeostatic readjustment in the HeLa-µs model, it provides an ideal system for dissecting the intricacies of how the UPR evaluates and alleviates ER stress.

3-O-Hydroxytyrosol glucuronide and 4-O-hydroxytyrosol glucuronide reduce endoplasmic reticulum stress in vitro

2015 ◽  
Vol 6 (10) ◽  
pp. 3275-3281 ◽  
Author(s):  
Elena Giordano ◽  
Olivier Dangles ◽  
Njara Rakotomanomana ◽  
Silvia Baracchini ◽  
Francesco Visioli
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Unfolded Protein ◽  
Atherosclerosis Development ◽  
The Unfolded Protein Response ◽  
Protein Response

Endoplasmic reticulum (ER) stress is important for atherosclerosis development and is mediated by the unfolded protein response (UPR).

scholarly journals Decoding non-canonical mRNA decay by the endoplasmic-reticulum stress sensor IRE1α

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adrien Le Thomas ◽  
Elena Ferri ◽  
Scot Marsters ◽  
Jonathan M. Harnoss ◽  
David A. Lawrence ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Endoplasmic Reticulum Stress ◽  
Er Stress ◽  
Stem Loop ◽  
Unfolded Protein ◽  
Cellular Mrnas ◽  
The Unfolded Protein Response ◽  
Protein Response

AbstractInositol requiring enzyme 1 (IRE1) mitigates endoplasmic-reticulum (ER) stress by orchestrating the unfolded-protein response (UPR). IRE1 spans the ER membrane, and signals through a cytosolic kinase-endoribonuclease module. The endoribonuclease generates the transcription factor XBP1s by intron excision between similar RNA stem-loop endomotifs, and depletes select cellular mRNAs through regulated IRE1-dependent decay (RIDD). Paradoxically, in mammals RIDD seems to target only mRNAs with XBP1-like endomotifs, while in flies RIDD exhibits little sequence restriction. By comparing nascent and total IRE1α-controlled mRNAs in human cells, we identify not only canonical endomotif-containing RIDD substrates, but also targets without such motifs—degraded by a process we coin RIDDLE, for RIDD lacking endomotif. IRE1α displays two basic endoribonuclease modalities: highly specific, endomotif-directed cleavage, minimally requiring dimers; and more promiscuous, endomotif-independent processing, requiring phospho-oligomers. An oligomer-deficient IRE1α mutant fails to support RIDDLE in vitro and in cells. Our results advance current mechanistic understanding of the UPR.

scholarly journals An essential dimer-forming subregion of the endoplasmic reticulum stress sensor Ire1

2005 ◽  
Vol 391 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Daisuke Oikawa ◽  
Yukio Kimata ◽  
Masato Takeuchi ◽  
Kenji Kohno
Keyword(s):  
Endoplasmic Reticulum ◽  
Recombinant Protein ◽  
Endoplasmic Reticulum Stress ◽  
Transmembrane Protein ◽  
Type I ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Recombinant Fragments ◽  
Made In

The luminal domain of the type I transmembrane protein Ire1 senses endoplasmic reticulum stress by an undefined mechanism to up-regulate the signalling pathway for the unfolded protein response. Previously, we proposed that the luminal domain of yeast Ire1 is divided into five subregions, termed subregions I–V sequentially from the N-terminus. Ire1 lost activity when internal deletions of subregion II or IV were made. In the present paper, we show that partial proteolysis of a recombinant protein consisting of the Ire1 luminal domain suggests that subregions II–IV are tightly folded. We also show that a recombinant protein of subregions II–IV formed homodimers, and that this homodimer formation was impaired by an internal deletion of subregion IV. Furthermore, recombinant fragments of subregion IV exhibited a self-binding ability. Therefore, although its sequence is little conserved evolutionarily, subregion IV plays an essential role to promote Ire1 dimer formation.

scholarly journals IreA controls endoplasmic reticulum stress-induced autophagy and survival through homeostasis recovery

2018 ◽  
pp. MCB.00054-18 ◽  
Author(s):  
Eunice Domínguez-Martín ◽  
Laura Ongay-Larios ◽  
Laura Kawasaki ◽  
Olivier Vincent ◽  
Gerardo Coello ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Cell Survival ◽  
Eukaryotic Cell ◽  
Functional Link ◽  
Unfolded Protein ◽  
Transcriptional Changes ◽  
The Unfolded Protein Response ◽  
Protein Response

The Unfolded Protein Response (UPR) is an adaptive pathway that restores cellular homeostasis after endoplasmic reticulum (ER) stress. The ER-resident kinase/ribonuclease Ire1 is the only UPR sensor conserved during evolution. Autophagy, a lysosomal degradative pathway, also contributes to the recovery of cell homeostasis after ER-stress but the interplay between these two pathways is still poorly understood. We describe the Dictyostelium discoideum ER-stress response and characterize its single bonafide Ire1 orthologue, IreA. We found that tunicamycin (TN) triggers a gene-expression reprogramming that increases the protein folding capacity of the ER and alleviates ER protein load. Further, IreA is required for cell-survival after TN-induced ER-stress and is responsible for nearly 40% of the transcriptional changes induced by TN. The response of Dictyostelium cells to ER-stress involves the combined activation of an IreA-dependent gene expression program and the autophagy pathway. These two pathways are independently activated in response to ER-stress but, interestingly, autophagy requires IreA at a later stage for proper autophagosome formation. We propose that unresolved ER-stress in cells lacking IreA causes structural alterations of the ER, leading to a late-stage blockade of autophagy clearance. This unexpected functional link may critically affect eukaryotic cell survival under ER-stress.

scholarly journals ER stress in neurodegenerative disease: from disease mechanisms to therapeutic interventions

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Felipe Cabral-Miranda ◽  
Claudio Hetz
Keyword(s):  
Endoplasmic Reticulum ◽  
Neurodegenerative Diseases ◽  
Er Stress ◽  
Major Element ◽  
Neuronal Loss ◽  
Therapeutic Interventions ◽  
Unfolded Protein ◽  
Disease Mechanisms ◽  
The Unfolded Protein Response ◽  
Protein Response

AbstractThe conception that protein aggregates composed by misfolded proteins underlies the occurrence of several neurodegenerative diseases suggests that this phenomenon may have a common origin, ultimately driven by disruption of proteostasis control. The unfolded protein response (UPR) embodies a major element of the proteostasis network, which is engaged by endoplasmic reticulum (ER) stress. Chronic ER stress may operate as a possible mechanism of neurodegeneration, contributing to synaptic alterations, neuroinflammation and neuronal loss. In this review we discuss most recent findings relating ER stress and the development of distinct neurodegenerative diseases, and the possible strategies for disease intervention.

Sign in / Sign up

Export Citation Format

Share Document