bims-ershed 2021-09-05 papers

bims-ershed

Biomed News

on ER Stress in Health and Diseases

Issue of 2021–09–05
nine papers selected by
Matías Eduardo González Quiroz, Worker’s Hospital

The role of endoplasmic reticulum stress in astrocytes.
Influenza A viruses balance ER stress with host protein synthesis shutoff.
Neuronal regulated ire-1-dependent mRNA decay controls germline differentiation in Caenorhabditis elegans.
The ATP-dependent SWI/SNF and RSC chromatin remodelers cooperatively induce unfolded protein response genes during endoplasmic reticulum stress.
Protein disulphide isomerase (PDI) is protective against amyotrophic lateral sclerosis (ALS)-related mutant Fused in Sarcoma (FUS) in in vitro models.
The regulation of Ero1-alpha in homocysteine-induced macrophage apoptosis and vulnerable plaque formation in atherosclerosis.
Strategies for the Site-Specific Decoration of DNA Origami Nanostructures with Functionally Intact Proteins.
Autophagy promotes growth of tumors with high mutational burden by inhibiting a T-cell immune response.
Biology of the Radio- and Chemo-Responsiveness in HPV Malignancies.

Glia. 2021 Aug 31.

The role of endoplasmic reticulum stress in astrocytes.

Savannah G Sims, Rylee N Cisney, Marissa M Lipscomb, Gordon P Meares.

  Astrocytes are glial cells that support neurological function in the central nervous system (CNS), in part, by providing structural support for neuronal synapses and blood vessels, participating in electrical and chemical transmission, and providing trophic support via soluble factors. Dysregulation of astrocyte function contributes to neurological decline in CNS diseases. Neurological diseases are highly heterogeneous but share common features of cellular stress including the accumulation of misfolded proteins. Endoplasmic reticulum (ER) stress has been reported in nearly all neurological and neurodegenerative diseases. ER stress occurs when there is an accumulation of misfolded proteins in the ER lumen and the protein folding demand of the ER is overwhelmed. ER stress initiates the unfolded protein response (UPR) to restore homeostasis by abating protein translation and, if the cell is irreparably damaged, initiating apoptosis. Although protein aggregation and misfolding in neurological disease has been well described, cell-specific contributions of ER stress and the UPR in physiological and disease states are poorly understood. Recent work has revealed a role for active UPR signaling that may drive astrocytes toward a maladaptive phenotype in various model systems. In response to ER stress, astrocytes produce inflammatory mediators, have reduced trophic support, and can transmit ER stress to other cells. This review will discuss the current known contributions and consequences of activated UPR signaling in astrocytes.

Keywords:  astrocytes; cell signaling; endoplasmic reticulum; glia; protein folding; translation

DOI:  https://doi.org/10.1002/glia.24082
Proc Natl Acad Sci U S A. 2021 Sep 07. pii: e2024681118. [Epub ahead of print]118(36):

Influenza A viruses balance ER stress with host protein synthesis shutoff.

Beryl Mazel-Sanchez, Justyna Iwaszkiewicz, Joao P P Bonifacio, Filo Silva, Chengyue Niu, Shirin Strohmeier, Davide Eletto, Florian Krammer, Gene Tan, Vincent Zoete, Benjamin G Hale, Mirco Schmolke.

  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.

Keywords:  CPSF30; ER stress; NS1; influenza virus; neuraminidase

DOI:  https://doi.org/10.1073/pnas.2024681118
Elife. 2021 Sep 03. pii: e65644. [Epub ahead of print]10

Neuronal regulated ire-1-dependent mRNA decay controls germline differentiation in Caenorhabditis elegans.

Mor Levi-Ferber, Rewayd Shalash, Adrien Le-Thomas, Yehuda Salzberg, Maor Shurgi, Jennifer Ic Benichou, Avi Ashkenazi, Sivan Henis-Korenblit.

  Understanding the molecular events that regulate cell pluripotency versus acquisition of differentiated somatic cell fate is fundamentally important. Studies in Caenorhabditis elegans demonstrate that knockout of the germline-specific translation repressor gld-1 causes germ cells within tumorous gonads to form germline-derived teratoma. Previously we demonstrated that endoplasmic reticulum (ER) stress enhances this phenotype to suppress germline tumor progression(Levi-Ferber et al., 2015). Here, we identify a neuronal circuit that non-autonomously suppresses germline differentiation and show that it communicates with the gonad via the neurotransmitter serotonin to limit somatic differentiation of the tumorous germline. ER stress controls this circuit through regulated inositol requiring enzyme-1 (IRE-1)-dependent mRNA decay of transcripts encoding the neuropeptide FLP-6. Depletion of FLP-6 disrupts the circuit's integrity and hence its ability to prevent somatic-fate acquisition by germline tumor cells. Our findings reveal mechanistically how ER stress enhances ectopic germline differentiation and demonstrate that regulated Ire1-dependent decay can affect animal physiology by controlling a specific neuronal circuit.

Keywords:  C. elegans; ER stress; IRE1; RIDD; cell biology; developmental biology; germline; neuronal circuit; pluripotency; teratoma

DOI:  https://doi.org/10.7554/eLife.65644
Biochim Biophys Acta Gene Regul Mech. 2021 Aug 25. pii: S1874-9399(21)00066-3. [Epub ahead of print] 194748

The ATP-dependent SWI/SNF and RSC chromatin remodelers cooperatively induce unfolded protein response genes during endoplasmic reticulum stress.

Rakesh Kumar Sahu, Sakshi Singh, Raghuvir Singh Tomar.

  The SWI/SNF subfamily remodelers (SWI/SNF and RSC) generally promote gene expression by displacing or evicting nucleosomes at the promoter regions. Their action creates a nucleosome-depleted region where transcription machinery accesses the DNA. Their involvement has been shown critical for inducing stress-responsive transcription programs. Although the role of SWI/SNF and RSC complexes in transcription regulation of heat shock responsive genes is well studied, their involvement at other pathways such as unfolded protein response (UPR) and protein quality control (PQC) is less known. This study shows that SWI/SNF occupies promoters of UPR, HSP and PQC genes in response to unfolded protein stress, and its recruitment at UPR promoters depends on Hac1 transcription factor and other epigenetic factors like Ada2 and Ume6. Disruption of SWI/SNF's activity does not affect the remodeling of these promoters or gene expression. However, inactivation of RSC and SWI/SNF together diminishes expression of most of the UPR, HSP and PQC genes tested. Furthermore, RSC and SWI/SNF colocalize at these promoters, suggesting that these two remodelers functionally cooperate to induce stress-responsive genes under proteotoxic conditions.

Keywords:  Chromatin remodeling complexes; ER stress; RSC; SWI/SNF; Transcription regulation; UPR

DOI:  https://doi.org/10.1016/j.bbagrm.2021.194748
Sci Rep. 2021 Sep 02. 11(1): 17557

Protein disulphide isomerase (PDI) is protective against amyotrophic lateral sclerosis (ALS)-related mutant Fused in Sarcoma (FUS) in in vitro models.

S Parakh, E R Perri, M Vidal, J Sultana, S Shadfar, P Mehta, A Konopka, C J Thomas, D M Spencer, J D Atkin.

Mutations in Fused in Sarcoma (FUS) are present in familial and sporadic cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). FUS is localised in the nucleus where it has important functions in DNA repair. However, in ALS/FTD, mutant FUS mislocalises from the nucleus to the cytoplasm where it forms inclusions, a key pathological hallmark of neurodegeneration. Mutant FUS also inhibits protein import into the nucleus, resulting in defects in nucleocytoplasmic transport. Fragmentation of the neuronal Golgi apparatus, induction of endoplasmic reticulum (ER) stress, and inhibition of ER-Golgi trafficking are also associated with mutant FUS misfolding in ALS. Protein disulphide isomerase (PDI) is an ER chaperone previously shown to be protective against misfolding associated with mutant superoxide dismutase 1 (SOD1) and TAR DNA-binding protein-43 (TDP-43) in cellular and zebrafish models. However, a protective role against mutant FUS in ALS has not been previously described. In this study, we demonstrate that PDI is protective against mutant FUS. In neuronal cell line and primary cultures, PDI restores defects in nuclear import, prevents the formation of mutant FUS inclusions, inhibits Golgi fragmentation, ER stress, ER-Golgi transport defects, and apoptosis. These findings imply that PDI is a new therapeutic target in FUS-associated ALS.

DOI: https://doi.org/10.1038/s41598-021-96181-2
Atherosclerosis. 2021 Aug 11. pii: S0021-9150(21)01276-4. [Epub ahead of print]334 39-47

The regulation of Ero1-alpha in homocysteine-induced macrophage apoptosis and vulnerable plaque formation in atherosclerosis.

Na Zhang, Lili Zhu, Xianxian Wu, Ru Yan, Shaobing Yang, Xiaoliang Jiang, Xing Liu, Xue Liu, Ning Yan, Guangzhi Cong, Zhiwei Yang, Shaobin Jia.

   BACKGROUND AND AIMS: Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis and plaque vulnerability. Macrophage apoptosis mediated by endoplasmic reticulum (ER) stress plays an important role in the pathogenesis of HHcy-aggravated atherosclerosis. Endoplasmic reticulum oxidoreductase 1α (Ero1α) is critical for ER stress-induced apoptosis. We hypothesized that Ero1α may contribute to ER-stress induced macrophage apoptosis and plaque stability in advanced atherosclerotic lesions by HHcy.
METHODS: Apoe-/- mice were maintained on drinking water containing homocysteine (Hcy, 1.8 g/L) to establish HHcy atherosclerotic models. The role of Ero1α in atherosclerotic plaque stability, macrophage apoptosis and ER stress were monitored in the plaque of aortic roots in HHcy Apoe-/- mice with or without silence or overexpression of Ero1α through lentivirus. Mouse peritoneal macrophages were used to confirm the regulation of Ero1α on ER stress dependent apoptosis in the presence of HHcy.
RESULTS: Atherosclerotic plaque vulnerability and macrophage apoptosis were promoted in Apoe-/- mice by high Hcy diet, accompanied by the upregulation of Ero1α expression and ER stress. Inhibition of Ero1α prevented macrophage apoptosis and atherosclerotic plaque vulnerability, and vice versa. Consistently, in mouse peritoneal macrophages, ER stress and apoptosis were attenuated by Ero1α deficiency, but enhanced by Ero1α overexpression.
CONCLUSIONS: Hcy, via upregulation of Ero1α expression, activates ER stress-dependent macrophage apoptosis to promote vulnerable plaque formation in atherosclerosis. Ero1α may be a potential therapeutic target for atherosclerosis induced by Hcy.

Keywords:  Endoplasmic reticulum oxidoreductase 1α; Endoplasmic reticulum stress; Hyperhomocysteinemia; Macrophage apoptosis; Vulnerable plaque

DOI:  https://doi.org/10.1016/j.atherosclerosis.2021.08.015
ACS Nano. 2021 Aug 31.

Strategies for the Site-Specific Decoration of DNA Origami Nanostructures with Functionally Intact Proteins.

Joschka Hellmeier, René Platzer, Vanessa Mühlgrabner, Magdalena C Schneider, Elke Kurz, Gerhard J Schütz, Johannes B Huppa, Eva Sevcsik.

  DNA origami structures provide flexible scaffolds for the organization of single biomolecules with nanometer precision. While they find increasing use for a variety of biological applications, the functionalization with proteins at defined stoichiometry, high yield, and under preservation of protein function remains challenging. In this study, we applied single molecule fluorescence microscopy in combination with a cell biological functional assay to systematically evaluate different strategies for the site-specific decoration of DNA origami structures, focusing on efficiency, stoichiometry, and protein functionality. Using an activating ligand of the T-cell receptor (TCR) as the protein of interest, we found that two commonly used methodologies underperformed with regard to stoichiometry and protein functionality. While strategies employing tetravalent wildtype streptavidin for coupling of a biotinylated TCR-ligand yielded mixed populations of DNA origami structures featuring up to three proteins, the use of divalent (dSAv) or DNA-conjugated monovalent streptavidin (mSAv) allowed for site-specific attachment of a single biotinylated TCR-ligand. The most straightforward decoration strategy, via covalent DNA conjugation, resulted in a 3-fold decrease in ligand potency, likely due to charge-mediated impairment of protein function. Replacing DNA with charge-neutral peptide nucleic acid (PNA) in a ligand conjugate emerged as the coupling strategy with the best overall performance in our study, as it produced the highest yield with no multivalent DNA origami structures and fully retained protein functionality. With our study we aim to provide guidelines for the stoichiometrically defined, site-specific functionalization of DNA origami structures with proteins of choice serving a wide range of biological applications.

Keywords:  DNA nanostructures; DNA origami; T-cell activation; functionalization; protein conjugation; single molecule fluorescence microscopy

DOI:  https://doi.org/10.1021/acsnano.1c05411
Nat Cancer. 2020 Sep;1(9): 923-934

Autophagy promotes growth of tumors with high mutational burden by inhibiting a T-cell immune response.

Laura Poillet-Perez, Daniel W Sharp, Yang Yang, Saurabh V Laddha, Maria Ibrahim, Praveen K Bommareddy, Zhixian Sherrie Hu, Joshua Vieth, Michael Haas, Marcus W Bosenberg, Joshua D Rabinowitz, Jian Cao, Jun-Lin Guan, Shridar Ganesan, Chang S Chan, Janice M Mehnert, Edmund C Lattime, Eileen White.

Macroautophagy (hereafter autophagy) degrades and recycles intracellular components to sustain metabolism and survival during starvation. Host autophagy promotes tumor growth by providing essential tumor nutrients. Autophagy also regulates immune cell homeostasis and function and suppresses inflammation. Although host autophagy does not promote a T-cell anti-tumor immune response in tumors with low tumor mutational burden (TMB), whether this was the case in tumors with high TMB was not known. Here we show that autophagy, especially in the liver, promotes tumor immune tolerance by enabling regulatory T-cell function and limiting stimulator of interferon genes, T-cell response and interferon-γ, which enables growth of high-TMB tumors. We have designated this as hepatic autophagy immune tolerance. Autophagy thereby promotes tumor growth through both metabolic and immune mechanisms depending on mutational load and autophagy inhibition is an effective means to promote an antitumor T-cell response in high-TMB tumors.

DOI: https://doi.org/10.1038/s43018-020-00110-7
Semin Radiat Oncol. 2021 Oct;pii: S1053-4296(21)00017-5. [Epub ahead of print]31(4): 274-285

Biology of the Radio- and Chemo-Responsiveness in HPV Malignancies.

Michael T Spiotto, Cullen M Taniguchi, Ann H Klopp, Lauren E Colbert, Steven H Lin, Li Wang, Mitchell J Frederick, Abdullah A Osman, Curtis R Pickering, Steven J Frank.

In multiple anatomic sites, patients with cancers associated with the Human Papillomavirus (HPV) experience better locoregional control and overall survival after radiotherapy and/or chemoradiotherapy than patients with HPV-negative cancers. These improved outcomes suggest that relatively unique biological features in HPV-positive cancers may increase sensitivity to DNA damaging agents as well as an impaired DNA damage response. This review will address potential biological mechanisms driving this increased sensitivity of HPV-positive cancer to radiation and/or chemotherapy. This review will discuss the clinical and preclinical observations that support the intrinsic radiosensitivity and/or chemosensitivity of HPV-positive cancers. Furthermore, this review will highlight the molecular mechanisms for increased radiation sensitivity using the classical "4 Rs" of radiobiology: repair, reassortment, repopulation, and reoxygenation. First, HPV-positive cancers have increased DNA damage due to increased oxidative stress and impaired DNA damage repair due to the altered activity TP53, p16, TIP60, and other repair proteins. Second, irradiated HPV-positive cancer cells display increased G2/M arrest leading to reassortment of cancer cells in more radiosensitive phases of the cell cycle. In addition, HPV-positive cancers have less radioresistant cancer stem cell subpopulations that may limit their repopulation during radiotherapy. Finally, HPV-positive cancers may also have less hypoxic tumor microenvironments that make these cancers more sensitive to radiation than HPV-negative cells. We will also discuss extrinsic immune and microenvironmental factors enriched in HPV-positive cancers that facilities responses to radiation. Therefore, these potential biological mechanisms may underpin the improved clinical outcomes often observed in these virally induced cancers.

DOI: https://doi.org/10.1016/j.semradonc.2021.02.009