bims-unfpre 2023-04-23 papers

Issue of 2023–04–23
seven papers selected by
Susan Logue, University of Manitoba

Immunohorizons. 2023 Apr 01. 7(4): 256-264

How the Unfolded Protein Response Is a Boon for Tumors and a Bane for the Immune System.

Lydia N Raines, Stanley Ching-Cheng Huang.

The correct folding of proteins is essential for appropriate cell function and is tightly regulated within the endoplasmic reticulum (ER). Environmental challenges and cellular conditions disrupt ER homeostasis and induce ER stress, which adversely affect protein folding and activate the unfolded protein response (UPR). It is now becoming recognized that cancer cells can overcome survival challenges posed within the tumor microenvironment by activating the UPR. Furthermore, the UPR has also been found to impose detrimental effects on immune cells by inducing immunoinhibitory activity in both tumor-infiltrating innate and adaptive immune cells. This suggests that these signaling axes may be important therapeutic targets, resulting in multifaceted approaches to eradicating tumor cells. In this mini-review, we discuss the role of the UPR in driving tumor progression and modulating the immune system's ability to target cancer cells. Additionally, we highlight some of the key unanswered questions that may steer future UPR research.

DOI: https://doi.org/10.4049/immunohorizons.2200064

Sci Signal. 2023 Apr 18. 16(781): eadi2176

Goblet cell stress management.

Annalisa M VanHook.

Autophagy augments the mucus-secreting capacity of goblet cells by reducing ER stress.

DOI: https://doi.org/10.1126/scisignal.adi2176

Life Sci. 2023 Apr 17. pii: S0024-3205(23)00339-9. [Epub ahead of print]323 121705

Cellular battle against endoplasmic reticulum stress and its adverse effect on health.

Subramaniyan Divya, Palaniyandi Ravanan.

The endoplasmic reticulum (ER) is a dynamic organelle and a reliable performer for precisely folded proteins. To maintain its function and integrity, arrays of sensory and quality control systems enhance protein folding fidelity and resolve the highest error-prone areas. Yet numerous internal and external factors disrupt its homeostasis and trigger ER stress responses. Cells try to reduce the number of misfolded proteins via the UPR mechanism, and ER-related garbage disposals systems like ER-associated degradation (ERAD), ER-lysosome-associated degradation (ERLAD), ER-Associated RNA Silencing (ERAS), extracellular chaperoning, and autophagy systems, which activates and increase the cell survival rate by degrading misfolded proteins, prevent the aggregated proteins and remove the dysfunctional organelles. Throughout life, organisms must confront environmental stress to survive and develop. Communication between the ER & other organelles, signaling events mediated by calcium, reactive oxygen species, and inflammation are linked to diverse stress signaling pathways and regulate cell survival or cell death mechanisms. Unresolved cellular damages can cross the threshold limit of their survival, resulting in cell death or driving for various diseases. The multifaceted ability of unfolded protein response facilitates the therapeutic target and a biomarker for various diseases, helping with early diagnosis and detecting the severity of diseases.

Keywords: Biomarkers; ER-associated degradation; ER-phagy; ER-to-lysosome-associated degradation; ERAS; Terminal UPR

DOI: https://doi.org/10.1016/j.lfs.2023.121705

Toxicology. 2023 Apr 17. pii: S0300-483X(23)00100-2. [Epub ahead of print] 153514

Wnt5a/Ca2+ signaling regulates silica-induced ferroptosis in mouse macrophages by altering ER stress-mediated redox balance.

Jia Ma, Jiaqi Wang, Chenjie Ma, Qian Cai, Shuang Wu, Wenfeng Hu, Jiali Yang, Jing Xue, Juan Chen, Xiaoming Liu.

Silicosis is a chronic pulmonary disease characterized by diffuse fibrosis of lung caused by the deposition of silica dust (SiO2). The inhaled silica-induced oxidative stress, ROS production and macrophage ferroptosis are key drivers of the pathological process of silicosis. However, mechanisms that involved in the silica-induced macrophage ferroptosis and its contributions to pathogenesis of silicosis remain elusive. In the present study, we showed that silica induced murine macrophage ferroptosis, accompanied by elevation of inflammatory responses, Wnt5a/Ca2+ signaling activation, and concurrent increase of endoplasmic reticulum (ER) stress and mitochondrial redox imbalance in vitro and vivo. Mechanistic study further demonstrated that Wnt5a/Ca2+ signaling played a key role in silica-induced macrophage ferroptosis by modulating ER stress and mitochondrial redox balance. The presence of Wnt5a/Ca2+ signaling ligand Wnt5a protein increased the silica-induced macrophage ferroptosis by activating ER-mediated immunoglobulin heavy chain binding protein (Bip)-C/EBP homology protein (Chop) signaling cascade, reducing the expression of negative regulators of ferroptosis, glutathione peroxidase 4 (Gpx4) and solute carrier family 7 member 11 (Slc7a11), subsequentially increasing lipid peroxidation. The pharmacologic inhibition of Wnt5a signaling or block of calcium flow exhibited an opposite effect to Wnt5a, resulted in the reduction of ferroptosis and the expression of Bip-Chop signaling molecules. These findings were further corroborated by the addition of ferroptosis activator Erastin or inhibitor ferrostatin-1. These results provide a mechanism by which silica activates Wnt5a/Ca2+ signaling and ER stress, sequentially leads to redox imbalance and ferroptosis in mouse macrophage cells.

Keywords: ER stress; Silicosis; ferroptosis, Wnt5a/Ca(2+) signaling; macrophage; redox imbalance

DOI: https://doi.org/10.1016/j.tox.2023.153514

BMC Med. 2023 04 17. 21(1): 147

Three tyrosine kinase inhibitors cause cardiotoxicity by inducing endoplasmic reticulum stress and inflammation in cardiomyocytes.

Huan Wang, Yiming Wang, Jiongyuan Li, Ziyi He, Sarah A Boswell, Mirra Chung, Fuping You, Sen Han.

BACKGROUND: Tyrosine kinase inhibitors (TKIs) are anti-cancer therapeutics often prescribed for long-term treatment. Many of these treatments cause cardiotoxicity with limited cure. We aim to clarify molecular mechanisms of TKI-induced cardiotoxicity so as to find potential targets for treating the adverse cardiac complications.
METHODS: Eight TKIs with different levels of cardiotoxicity reported are selected. Phenotypic and transcriptomic responses of human cardiomyocytes to TKIs at varying doses and times are profiled and analyzed. Stress responses and signaling pathways that modulate cardiotoxicity induced by three TKIs are validated in cardiomyocytes and rat hearts.
RESULTS: Toxicity rank of the eight TKIs determined by measuring their effects on cell viability, contractility, and respiration is largely consistent with that derived from database or literature, indicating that human cardiomyocytes are a good cellular model for studying cardiotoxicity. When transcriptomes are measured for selected TKI treatments with different levels of toxicity in human cardiomyocytes, the data are classified into 7 clusters with mainly single-drug clusters. Drug-specific effects on the transcriptome dominate over dose-, time- or toxicity-dependent effects. Two clusters with three TKIs (afatinib, ponatinib, and sorafenib) have the top enriched pathway as the endoplasmic reticulum stress (ERS). All three TKIs induce ERS in rat primary cardiomyocytes and ponatinib activates the IRE1α-XBP1s axis downstream of ERS in the hearts of rats underwent a 7-day course of drug treatment. To look for potential triggers of ERS, we find that the three TKIs induce transient reactive oxygen species followed by lipid peroxidation. Inhibiting either PERK or IRE1α downstream of ERS blocks TKI-induced cardiac damages, represented by the induction of cardiac fetal and pro-inflammatory genes without causing more cell death.
CONCLUSIONS: Our data contain rich information about phenotypic and transcriptional responses of human cardiomyocytes to eight TKIs, uncovering potential molecular mechanisms in modulating cardiotoxicity. ER stress is activated by multiple TKIs and leads to cardiotoxicity through promoting expression of pro-inflammatory factors and cardiac fetal genes. ER stress-induced inflammation is a promising therapeutic target to mitigate ponatinib- and sorafenib-induced cardiotoxicity.

Keywords: Cardiotoxicity; Endoplasmic reticulum stress; Inflammation; Transcriptomics; Tyrosine kinase inhibitor

DOI: https://doi.org/10.1186/s12916-023-02838-2

PLoS Genet. 2023 Apr 17. 19(4): e1010710

Insulin secretion deficits in a Prader-Willi syndrome β-cell model are associated with a concerted downregulation of multiple endoplasmic reticulum chaperones.

Erik A Koppes, Marie A Johnson, James J Moresco, Patrizia Luppi, Dale W Lewis, Donna B Stolz, Jolene K Diedrich, John R Yates, Ronald C Wek, Simon C Watkins, Susanne M Gollin, Hyun Jung Park, Peter Drain, Robert D Nicholls.

Prader-Willi syndrome (PWS) is a multisystem disorder with neurobehavioral, metabolic, and hormonal phenotypes, caused by loss of expression of a paternally-expressed imprinted gene cluster. Prior evidence from a PWS mouse model identified abnormal pancreatic islet development with retention of aged insulin and deficient insulin secretion. To determine the collective roles of PWS genes in β-cell biology, we used genome-editing to generate isogenic, clonal INS-1 insulinoma lines having 3.16 Mb deletions of the silent, maternal- (control) and active, paternal-allele (PWS). PWS β-cells demonstrated a significant cell autonomous reduction in basal and glucose-stimulated insulin secretion. Further, proteomic analyses revealed reduced levels of cellular and secreted hormones, including all insulin peptides and amylin, concomitant with reduction of at least ten endoplasmic reticulum (ER) chaperones, including GRP78 and GRP94. Critically, differentially expressed genes identified by whole transcriptome studies included reductions in levels of mRNAs encoding these secreted peptides and the group of ER chaperones. In contrast to the dosage compensation previously seen for ER chaperones in Grp78 or Grp94 gene knockouts or knockdown, compensation is precluded by the stress-independent deficiency of ER chaperones in PWS β-cells. Consistent with reduced ER chaperones levels, PWS INS-1 β-cells are more sensitive to ER stress, leading to earlier activation of all three arms of the unfolded protein response. Combined, the findings suggest that a chronic shortage of ER chaperones in PWS β-cells leads to a deficiency of protein folding and/or delay in ER transit of insulin and other cargo. In summary, our results illuminate the pathophysiological basis of pancreatic β-cell hormone deficits in PWS, with evolutionary implications for the multigenic PWS-domain, and indicate that PWS-imprinted genes coordinate concerted regulation of ER chaperone biosynthesis and β-cell secretory pathway function.

DOI: https://doi.org/10.1371/journal.pgen.1010710

Nat Rev Endocrinol. 2023 Apr 18.

Why does the immune system destroy pancreatic β-cells but not α-cells in type 1 diabetes?

Decio L Eizirik, Florian Szymczak, Roberto Mallone.

A perplexing feature of type 1 diabetes (T1D) is that the immune system destroys pancreatic β-cells but not neighbouring α-cells, even though both β-cells and α-cells are dysfunctional. Dysfunction, however, progresses to death only for β-cells. Recent findings indicate important differences between these two cell types. First, expression of BCL2L1, a key antiapoptotic gene, is higher in α-cells than in β-cells. Second, endoplasmic reticulum (ER) stress-related genes are differentially expressed, with higher expression levels of pro-apoptotic CHOP in β-cells than in α-cells and higher expression levels of HSPA5 (which encodes the protective chaperone BiP) in α-cells than in β-cells. Third, expression of viral recognition and innate immune response genes is higher in α-cells than in β-cells, contributing to the enhanced resistance of α-cells to coxsackievirus infection. Fourth, expression of the immune-inhibitory HLA-E molecule is higher in α-cells than in β-cells. Of note, α-cells are less immunogenic than β-cells, and the CD8+ T cells invading the islets in T1D are reactive to pre-proinsulin but not to glucagon. We suggest that this finding is a result of the enhanced capacity of the α-cell to endure viral infections and ER stress, which enables them to better survive early stressors that can cause cell death and consequently amplify antigen presentation to the immune system. Moreover, the processing of the pre-proglucagon precursor in enteroendocrine cells might favour immune tolerance towards this potential self-antigen compared to pre-proinsulin.

DOI: https://doi.org/10.1038/s41574-023-00826-3