Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A role for the ribosome-associated complex in activation of the IRE1 branch of UPR

ABSTRACT: The ubiquitous ribosome-associated complex (RAC) is a chaperone that spans ribosomes, making contacts near both the polypeptide exit tunnel and the decoding center, a position prime for sensing and coordinating translation and folding. Loss of RAC is known to result in growth defects and sensitization to translational and osmotic stresses. However, the physiological substrates of RAC and the mechanism(s) by which RAC is involved in responding to specific stresses in higher eukaryotes remain obscure. Data presented here uncover an essential function of mammalian RAC in the unfolded protein response (UPR). Knockdown of RAC sensitizes mammalian cells to ER stress and selectively interferes with IRE1 branch activation. Higher-order oligomerization of the IRE1α kinase/endoribonuclease depends upon RAC. These results reveal a surveillance function for RAC in the UPR: modulating IRE1α clustering as required for endonuclease activation and splicing of the substrate Xbp1 mRNA.

ORGANISM(S): Homo sapiens

PROVIDER: GSE173852 | GEO | 2021/06/14

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

The IRE1 interactome in human LS174T colon epithelial cells

Project description:Inositol-Requiring Enzyme (IRE)1 is an evolutionarily conserved sensor protein of the unfolded protein response (UPR). Vertebrates express two distinct paralogues: IRE1α (gene name ERN1) and IRE1β (gene name ERN2). Both proteins have a similar overall structure, with a sensor domain positioned in the endoplasmic reticulum (ER) lumen, and cytoplasmic kinase and endonuclease domains. For IRE1α, it is well-established that a protein folding chaperone called HSPA5 binds to the ER-luminal domain in conditions when the folding load and capacity are balanced. When unfolded proteins accumulate, HSPA5 is recruited to these unfolded proteins to aid in folding, thereby releasing IRE1α. This initiates a chain reaction of dimerization, trans-autophosphorylation and further oligomerization, resulting in an endonuclease-active IRE1α. Activated IRE1α cleaves an intron from the X-box binding protein 1 mRNA in an unusual cytoplasmic splicing reaction, and the resulting frameshift leads to production of a central UPR transcription factor, XBP1S. In contrast to this, IRE1β is far less extensively characterized. It is expressed solely in mucus-producing cells, more specifically goblet cells. Ectopic expression in other cell types such as Hela cells causes rapid cell death, most likely due to unregulated endonuclease activity. Upon aligning the two IRE1 paralogues, it becomes clear that the luminal domain has the lowest homology between the two paralogues, suggesting differences in how activity of either paralogue is tuned in the ER. In this project, we aimed to characterize and compare the IRE1β and IRE1α interactomes in LS174T cells, a cell line that has retained many goblet cell characteristics, to gain more insights into the regulation and downstream activity of IRE1β in a more relevant cellular background.

2023-11-21 | PXD042756 | Pride

Stress-induced tyrosine phosphorylation of RtcB modulates IRE1 activity and signaling outputs.

Project description:Endoplasmic Reticulum (ER) stress is a hallmark of various diseases, which is dealt with through the activation of an adaptive signaling pathway named the Unfolded Protein Response (UPR). This response is mediated by three ER-resident sensors and the most evolutionary conserved, IRE1α signals through its cytosolic kinase and endoribonuclease (RNase) activities. IRE1α RNase activity can either catalyze the initial step of XBP1 mRNA unconventional splicing or degrade a number of RNAs through Regulated IRE1-Dependent Decay (RIDD). The balance between these two activities plays an instrumental role in cells’ life and death decisions upon ER stress. Until now, the biochemical and biological outputs of IRE1α RNase activity have been well documented, however, the precise mechanisms controlling whether IRE1 signaling is adaptive or pro-death (terminal) remain unclear. This prompted us to further investigate those mechanisms and we hypothesized that XBP1 mRNA splicing and RIDD activity could be co-regulated by the IRE1α RNase regulatory network. We showed that a key nexus in this pathway is the tRNA ligase RtcB which, together with IRE1α, is responsible for XBP1 mRNA splicing. We demonstrated that RtcB is tyrosine phosphorylated by c-Abl and dephosphorylated by PTP1B. Moreover, we identified RtcB Y306 as a key residue which, when phosphorylated, perturbs RtcB interaction with IRE1α, thereby attenuating XBP1 mRNA splicing and favoring RIDD. Our results demonstrate that the IRE1α RNase regulatory network is dynamically fine-tuned by tyrosine kinases and phosphatases upon various stresses and that the nature of the stress determines cell adaptive or death outputs.

2022-02-21 | PXD023433 | Pride

Noncanonical mRNA decay by the endoplasmic-reticulum stress sensor IRE1-alpha promotes cancer cell survival [RNA-seq]

Project description:Eukaryotic 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, mammalian RIDD seemingly targets only mRNAs with XBP1-like endomotifs, while in flies RIDD exhibits little sequence restriction. By comparing nascent and total IRE1α-controlled mRNAs in human breast cancer cells, we discovered not only canonical endomotif-containing RIDD substrates, but also many targets lacking recognizable motifs—degraded by a process we coin RIDDLE, for RIDD lacking endomotif. IRE1α displayed two basic endoribonuclease modalities: endomotif-specific cleavage, minimally requiring dimers; and endomotif-independent promiscuous processing, requiring phospho-oligomers. An oligomer-deficient mutant that did not support RIDDLE failed to rescue cancer-cell viability. These results link IRE1α oligomers, RIDDLE, and cell survival, advancing mechanistic understanding of the UPR.

2021-06-01 | GSE169584 | GEO

Noncanonical mRNA decay by the endoplasmic-reticulum stress sensor IRE1-alpha promotes cancer cell survival [GRO-seq]

2021-06-01 | GSE169583 | GEO

Divergence and Conservation of the Major UPR Branch IRE1-bZIP Signaling Pathway across Eukaryotes.

Project description:The unfolded protein response (UPR) is crucial to life by regulating the cellular response to the stress in the endoplasmic reticulum (ER) imposed by abiotic and biotic cues such as heat shock and viral infection. The inositol requiring enzyme 1 (IRE1) signaling pathway activated by the IRE1-mediated unconventional splicing of HAC1 in yeast, bZIP60 in plants and XBP1 in metazoans, is the most ancient branch of the UPR. In this study, we systematically examined yeast IRE1p-HAC1, plant IRE1A/IRE1B-bZIP60 and human hIRE1-XBP1 pairs. We found that, unlike bZIP60, XBP1 is unable to functionally swap HAC1p in yeast, and that the inter-species heterotypic interactions among HAC1p, bZIP60 and XBP1 are not permitted. These data demonstrate evolutionary divergence of the downstream signaling of IRE1-bZIP. We also discovered that the dual cytosolic domains of plant IRE1s act in vivo in a mechanism consistent with IRE1p and hIRE1, and that plant IRE1B not only interacts with IRE1p but also forms typical IRE1 dynamic foci in yeast. Thus, the upstream components of the IRE1 signaling branch including IRE1 activation and action mechanisms are highly conserved. Taken together these data advance the molecular understanding of evolutionary divergence and conservation of the IRE1 signaling pathway across kingdoms.

| S-EPMC4891664 | biostudies-literature

A role for the ribosome-associated complex in activation of the IRE1 branch of UPR.

Project description:The ubiquitous ribosome-associated complex (RAC) is a chaperone that spans ribosomes, making contacts near both the polypeptide exit tunnel and the decoding center, a position prime for sensing and coordinating translation and folding. Loss of RAC is known to result in growth defects and sensitization to translational and osmotic stresses. However, the physiological substrates of RAC and the mechanism(s) by which RAC is involved in responding to specific stresses in higher eukaryotes remain obscure. The data presented here uncover an essential function of mammalian RAC in the unfolded protein response (UPR). Knockdown of RAC sensitizes mammalian cells to endoplasmic reticulum (ER) stress and selectively interferes with IRE1 branch activation. Higher-order oligomerization of the inositol-requiring enzyme 1α (IRE1α) kinase/endoribonuclease depends upon RAC. These results reveal a surveillance function for RAC in the UPR, as follows: modulating IRE1α clustering as required for endonuclease activation and splicing of the substrate Xbp1 mRNA.

| S-EPMC8370116 | biostudies-literature

A role for the ribosome-associated complex in activation of the IRE1 branch of UPR.

Project description: Not available

| S-EPMC8372851 | biostudies-literature

A role for the ribosome-associated complex in activation of the IRE1 branch of UPR

Project description:A role for the ribosome-associated complex in activation of the IRE1 branch of UPR

| PRJNA727298 | ENA

The UPR branch IRE1-bZIP60 in plants plays an essential role in viral infection and is complementary to the only UPR pathway in yeast.

Project description:The unfolded protein response (UPR) signaling network encompasses two pathways in plants, one mediated by inositol-requiring protein-1 (IRE1)-bZIP60 mRNA and the other by site-1/site-2 proteases (S1P/S2P)-bZIP17/bZIP28. As the major sensor of UPR in eukaryotes, IRE1, in response to endoplasmic reticulum (ER) stress, catalyzes the unconventional splicing of HAC1 in yeast, bZIP60 in plants and XBP1 in metazoans. Recent studies suggest that IRE1p and HAC1 mRNA, the only UPR pathway found in yeast, evolves as a cognate system responsible for the robust UPR induction. However, the functional connectivity of IRE1 and its splicing target in multicellular eukaryotes as well as the degree of conservation of IRE1 downstream signaling effectors across eukaryotes remains to be established. Here, we report that IRE1 and its substrate bZIP60 function as a strictly cognate enzyme-substrate pair to control viral pathogenesis in plants. Moreover, we show that the S1P/S2P-bZIP17/bZIP28 pathway, the other known branch of UPR in plants, does not play a detectable role in virus infection, demonstrating the distinct function of the IRE1-bZIP60 pathway in plants. Furthermore, we provide evidence that bZIP60 and HAC1, products of the enzyme-substrate duet, rather than IRE1, are functionally replaceable to cope with ER stress in yeast. Taken together, we conclude that the downstream signaling of the IRE1-mediated splicing is evolutionarily conserved in yeast and plants, and that the IRE1-bZIP60 UPR pathway not only confers overlapping functions with the other UPR branch in fundamental biology but also may exert a unique role in certain biological processes such as virus-plant interactions.

| S-EPMC4398384 | biostudies-literature

LOXL2 drives epithelial-mesenchymal transition via activation of IRE1-XBP1 branch of unfolded protein response.

Project description:Epithelial-to-Mesenchymal Transition (EMT) is a key process contributing to the aggressiveness of cancer cells. EMT is triggered by activation of different transcription factors collectively known as EMT-TFs. Different cellular cues and cell signalling networks activate EMT at transcriptional and posttranscriptional level in different biological and pathological situations. Among them, overexpression of LOXL2 (lysyl oxidase-like 2) induces EMT independent of its catalytic activity. Remarkably, perinuclear/cytoplasmic accumulation of LOXL2 is a poor prognosis marker of squamous cell carcinomas and is associated to basal breast cancer metastasis by mechanisms no yet fully understood. Here, we report that overexpression of LOXL2 promotes its accumulation in the Endoplasmic Reticulum where it interacts with HSPA5 leading to activation of the IRE1-XBP1-branch of the Unfolded Protein Response (UPR). LOXL2-dependent UPR activation induces the expression of several EMT-TFs: SNAI1, SNAI2, ZEB2 and TCF3 that are direct transcriptional targets of XBP1. Remarkably, inhibition of IRE1 blocks LOXL2-dependent upregulation of EMT-TFs thus hindering EMT induction. LOXL2 relationship to Endoplasmic Reticulum Stress

2017-05-11 | GSE90605 | GEO

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data