Interaction with ribosomal proteins accompanies ER stress‐induction of the anticancer metallodrug BOLD‐100/KP1339

ABSTRACT Mammalian Ecdysoneless (ECD) is a highly conserved ortholog of the Drosophila Ecd gene product whose mutations impair the synthesis of Ecdysone and produce cell-autonomous survival defects, but the mechanisms by which ECD functions are largely unknown. Here we present evidence that ECD regulates the endoplasmic reticulum (ER) stress response. ER stress induction led to a reduced ECD protein level, but this effect was not seen in PKR-like ER kinase knockout (PERK-KO) or phosphodeficient eukaryotic translation initiation factor 2α (eIF2α) mouse embryonic fibroblasts (MEFs); moreover, ECD mRNA levels were increased, suggesting impaired ECD translation as the mechanism for reduced protein levels. ECD colocalizes and coimmunoprecipitates with PERK and GRP78. ECD depletion increased the levels of both phospho-PERK (p-PERK) and p-eIF2α, and these effects were enhanced upon ER stress induction. Reciprocally, overexpression of ECD led to marked decreases in p-PERK, p-eIF2α, and ATF4 levels but robust increases in GRP78 protein levels. However, GRP78 mRNA levels were unchanged, suggesting a posttranscriptional event. Knockdown of GRP78 reversed the attenuating effect of ECD overexpression on PERK signaling. Significantly, overexpression of ECD provided a survival advantage to cells upon ER stress induction. Taken together, our data demonstrate that ECD promotes survival upon ER stress by increasing GRP78 protein levels to enhance the adaptive folding protein in the ER to attenuate PERK signaling.

Download Full-text

Influenza A viruses balance ER stress with host protein synthesis shutoff

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2024681118 ◽

2021 ◽

Vol 118 (36) ◽

pp. e2024681118

Author(s):

Beryl Mazel-Sanchez ◽

Justyna Iwaszkiewicz ◽

Joao P. P. Bonifacio ◽

Filo Silva ◽

Chengyue Niu ◽

...

Keyword(s):

Viral Replication ◽

Er Stress ◽

Host Cell ◽

Messenger Rna ◽

Influenza A ◽

Nonstructural Protein ◽

Host Protein ◽

Stress Induction ◽

Nonstructural Protein 1

Excessive production of viral glycoproteins during infections poses a tremendous stress potential on the endoplasmic reticulum (ER) protein folding machinery of the host cell. The host cell balances this by providing more ER resident chaperones and reducing translation. For viruses, this unfolded protein response (UPR) offers the potential to fold more glycoproteins. We postulated that viruses could have developed means to limit the inevitable ER stress to a beneficial level for viral replication. Using a relevant human pathogen, influenza A virus (IAV), we first established the determinant for ER stress and UPR induction during infection. In contrast to a panel of previous reports, we identified neuraminidase to be the determinant for ER stress induction, and not hemagglutinin. IAV relieves ER stress by expression of its nonstructural protein 1 (NS1). NS1 interferes with the host messenger RNA processing factor CPSF30 and suppresses ER stress response factors, such as XBP1. In vivo viral replication is increased when NS1 antagonizes ER stress induction. Our results reveal how IAV optimizes glycoprotein expression by balancing folding capacity.

Download Full-text

Inhibitory Effect of Unsaturated Fatty Acids on Saturated Fatty Acid-Induced Apoptosis in Human Pancreatic β-Cells: Activation of Caspases and ER Stress Induction

Cellular Physiology and Biochemistry ◽

10.1159/000329954 ◽

2011 ◽

Vol 27 (5) ◽

pp. 525-538 ◽

Cited By ~ 31

Author(s):

Vlasta Němcová-Fürstová ◽

Roger F.L. James ◽

Jan Kovář

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Er Stress ◽

Saturated Fatty Acid ◽

Unsaturated Fatty Acids ◽

Inhibitory Effect ◽

Β Cells ◽

Pancreatic Β Cells ◽

Stress Induction ◽

Induced Apoptosis

Download Full-text

Genome-wide mRNA profiling identifies X-box-binding protein 1 (XBP1) as an IRE1 and PUMA repressor

Cellular and Molecular Life Sciences ◽

10.1007/s00018-021-03952-1 ◽

2021 ◽

Author(s):

Magdalena Gebert ◽

Aleksandra Sobolewska ◽

Sylwia Bartoszewska ◽

Aleksandra Cabaj ◽

David K. Crossman ◽

...

Keyword(s):

Transcription Factor ◽

Er Stress ◽

Cell Line ◽

Molecular Mechanisms ◽

Binding Protein ◽

Bioinformatic Analysis ◽

Competitive Inhibitor ◽

Human Cell Line ◽

Factor X ◽

Stress Induction

AbstractAccumulation of misfolded proteins in ER activates the unfolded protein response (UPR), a multifunctional signaling pathway that is important for cell survival. The UPR is regulated by three ER transmembrane sensors, one of which is inositol-requiring protein 1 (IRE1). IRE1 activates a transcription factor, X-box-binding protein 1 (XBP1), by removing a 26-base intron from XBP1 mRNA that generates spliced XBP1 mRNA (XBP1s). To search for XBP1 transcriptional targets, we utilized an XBP1s-inducible human cell line to limit XBP1 expression in a controlled manner. We also verified the identified XBP1-dependent genes with specific silencing of this transcription factor during pharmacological ER stress induction with both an N-linked glycosylation inhibitor (tunicamycin) and a non-competitive inhibitor of the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) (thapsigargin). We then compared those results to the XBP1s-induced cell line without pharmacological ER stress induction. Using next‐generation sequencing followed by bioinformatic analysis of XBP1-binding motifs, we defined an XBP1 regulatory network and identified XBP1 as a repressor of PUMA (a proapoptotic gene) and IRE1 mRNA expression during the UPR. Our results indicate impairing IRE1 activity during ER stress conditions accelerates cell death in ER-stressed cells, whereas elevating XBP1 expression during ER stress using an inducible cell line correlated with a clear prosurvival effect and reduced PUMA protein expression. Although further studies will be required to test the underlying molecular mechanisms involved in the relationship between these genes with XBP1, these studies identify a novel repressive role of XBP1 during the UPR.

Download Full-text

Quantifying multi-layered expression regulation in response to stress of the endoplasmic reticulum

10.1101/308379 ◽

2018 ◽

Author(s):

Justin Rendleman ◽

Zhe Cheng ◽

Shuvadeep Maity ◽

Nicolai Kastelic ◽

Mathias Munschauer ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Ribosomal Proteins ◽

Time Course ◽

Gene Expression Regulation ◽

Expression Regulation ◽

Transcriptional Level ◽

Cervical Cancer Cells ◽

One Carbon Metabolism ◽

Stress Dependent

AbstractThe mammalian response to endoplasmic reticulum (ER) stress dynamically affects all layers of gene expression regulation. We quantified transcript and protein abundance along with footprints of ribosomes and non-ribosomal proteins for thousands of genes in cervical cancer cells responding to treatment with tunicamycin or hydrogen peroxide over an eight hour time course. We identify shared and stress-specific significant regulatory events at the transcriptional and post-transcriptional level and at different phases of the experiment. ER stress regulators increase transcription and translation at different times supporting an adaptive response. ER stress also induces translation of genes from serine biosynthesis and one-carbon metabolism indicating a shift in energy production. Discordant regulation of DNA repair genes suggests transcriptional priming in which delayed translation fine-tunes the early change in the transcriptome. Finally, case studies on stress-dependent alternative splicing and protein-mRNA binding demonstrate the ability of this resource to generate hypotheses for new regulatory mechanisms.

Download Full-text

A Tripartite Synergy of TLR4 Activation, ER Stress Induction and Autophagy Inhibition Is Critical for Interleukin 23 Induction in Liver Ischemia and Reperfusion Injury.

Transplantation Journal ◽

10.1097/00007890-201407151-01110 ◽

2014 ◽

Vol 98 ◽

pp. 343

Author(s):

L. Lu ◽

J. Rao ◽

S. Yue ◽

G. Li ◽

Q. Qian ◽

...

Keyword(s):

Er Stress ◽

Reperfusion Injury ◽

Ischemia And Reperfusion ◽

Liver Ischemia ◽

Ischemia And Reperfusion Injury ◽

Stress Induction ◽

Interleukin 23 ◽

Tlr4 Activation ◽

Autophagy Inhibition

Download Full-text

Tanshinone IIA induces TRAIL sensitization of human lung cancer cells through selective ER stress induction

International Journal of Oncology ◽

10.3892/ijo.2016.3441 ◽

2016 ◽

Vol 48 (5) ◽

pp. 2205-2212 ◽

Cited By ~ 13

Author(s):

EUN-OK KIM ◽

SHI EUN KANG ◽

CHANG RAK IM ◽

JUN-HEE LEE ◽

KWANG SEOK AHN ◽

...

Keyword(s):

Lung Cancer ◽

Er Stress ◽

Cancer Cells ◽

Human Lung ◽

Tanshinone Iia ◽

Lung Cancer Cells ◽

Human Lung Cancer ◽

Stress Induction ◽

Human Lung Cancer Cells

Download Full-text

Genome-Wide mRNA Profiling Identifies X-Box-Binding Protein 1 (XBP1) As An IRE1 And PUMA Repressor

10.21203/rs.3.rs-527235/v1 ◽

2021 ◽

Author(s):

Magdalena Gebert ◽

Aleksandra Sobolewska ◽

Sylwia Bartoszewska ◽

Aleksandra Cabaj ◽

David K. Crossman ◽

...

Keyword(s):

Transcription Factor ◽

Er Stress ◽

Cell Line ◽

Molecular Mechanisms ◽

Binding Protein ◽

Bioinformatic Analysis ◽

Competitive Inhibitor ◽

Human Cell Line ◽

Factor X ◽

Stress Induction

Abstract Accumulation of misfolded proteins in ER activates the unfolded protein response (UPR), a multifunctional signaling pathway that is important for cell survival. The UPR is regulated by three ER transmembrane sensors, one of which is inositol-requiring protein 1 (IRE1). IRE1 activates a transcription factor, X-box binding protein 1 (XBP1), by removing a 26-base intron from XBP1 mRNA that generates spliced XBP1 mRNA (XBP1s). To search for XBP1 transcriptional targets, we utilized an XBP1s-inducible human cell line to limit XBP1 expression in a controlled manner. We also verified the identified XBP1-dependent genes with specific silencing of this transcription factor during pharmacological ER stress induction with both an N-linked glycosylation inhibitor (tunicamycin) and a non-competitive inhibitor of the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) (thapsigargin). We then compared those results to the XBP1s-induced cell line without pharmacological ER stress induction. Using next‐generation sequencing followed by bioinformatic analysis of XBP1 binding motifs, we defined an XBP1 regulatory network and identified XBP1 as a repressor of PUMA (a proapoptotic gene) and IRE1 mRNA expression during the UPR. Our results indicate impairing IRE1 activity during ER stress conditions accelerates cell death in ER stressed cells, whereas elevating XBP1 expression during ER stress using an inducible cell line correlated with a clear prosurvival effect and reduced PUMA protein expression. Although further studies will be required to test the underlying molecular mechanisms involved the relationship between these genes with XBP1, these studies identify a novel repressive role of XBP1 during the UPR.

Download Full-text