scholarly journals SARS-CoV-2 ORF8 Forms Intracellular Aggregates and Inhibits IFNγ-Induced Antiviral Gene Expression in Human Lung Epithelial Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Hua Geng ◽  
Saravanan Subramanian ◽  
Longtao Wu ◽  
Heng-Fu Bu ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Viral Infection ◽  
Human Lung ◽  
Lung Epithelial Cells ◽  
Lung Epithelial Cell ◽  
Accessory Protein ◽  
Epithelial Cell Proliferation ◽  
Lung Epithelial

Infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a disease that involves significant lung tissue damage. How SARS-CoV-2 infection leads to lung injury remains elusive. The open reading frame 8 (ORF8) protein of SARS-CoV-2 (ORF8SARS-CoV-2) is a unique accessory protein, yet little is known about its cellular function. We examined the cellular distribution of ORF8SARS-CoV-2 and its role in the regulation of human lung epithelial cell proliferation and antiviral immunity. Using live imaging and immunofluorescent staining analyses, we found that ectopically expressed ORF8SARS-CoV-2 forms aggregates in the cytosol and nuclear compartments of lung epithelial cells. Using in silico bioinformatic analysis, we found that ORF8SARS-CoV-2 possesses an intrinsic aggregation characteristic at its N-terminal residues 1-18. Cell culture did not reveal any effects of ORF8SARS-CoV-2 expression on lung epithelial cell proliferation and cell cycle progression, suggesting that ORF8SARS-CoV-2 aggregates do not affect these cellular processes. Interestingly, ectopic expression of ORF8SARS-CoV-2 in lung epithelial cells suppressed basal expression of several antiviral molecules, including DHX58, ZBP1, MX1, and MX2. In addition, expression of ORF8SARS-CoV-2 attenuated the induction of antiviral molecules by IFNγ but not by IFNβ in lung epithelial cells. Taken together, ORF8SARS-CoV-2 is a unique viral accessory protein that forms aggregates when expressing in lung epithelial cells. It potently inhibits the expression of lung cellular anti-viral proteins at baseline and in response to IFNγ in lung epithelial cells, which may facilitate SARS-CoV-2 escape from the host antiviral innate immune response during early viral infection. In addition, it seems that formation of ORF8SARS-CoV-2 aggregate is independent from the viral infection. Thus, it would be interesting to examine whether any COVID-19 patients exhibit persistent ORF8 SARS-CoV-2 expression after recovering from SARS-CoV-2 infection. If so, the pathogenic effect of prolonged ORF8SARS-CoV-2 expression and its association with post-COVID symptoms warrant investigation in the future.

scholarly journals TNF Family Cytokines Induce Distinct Cell Death Modalities in the A549 Human Lung Epithelial Cell Line when Administered in Combination with Ricin Toxin

Toxins ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 450 ◽  
Author(s):  
Hodges ◽  
Kempen ◽  
McCaig ◽  
Parker ◽  
Mantis ◽  
...  
Keyword(s):  
Cell Death ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Human Lung ◽  
Lung Epithelial Cells ◽  
Lung Epithelial Cell ◽  
Distinct Cell ◽  
Tnf Α ◽  
Lung Epithelial ◽  
Human Lung Epithelial Cells

Ricin is a member of the ribosome-inactivating protein (RIP) family of toxins and is classified as a biothreat agent by the Centers for Disease Control and Prevention (CDC). Inhalation, the most potent route of toxicity, triggers an acute respiratory distress-like syndrome that coincides with near complete destruction of the lung epithelium. We previously demonstrated that the TNF-related apoptosis-inducing ligand (TRAIL; CD253) sensitizes human lung epithelial cells to ricin-induced death. Here, we report that ricin/TRAIL-mediated cell death occurs via apoptosis and involves caspases -3, -7, -8, and -9, but not caspase-6. In addition, we show that two other TNF family members, TNF-α and Fas ligand (FasL), also sensitize human lung epithelial cells to ricin-induced death. While ricin/TNF-α- and ricin/FasL-mediated killing of A549 cells was inhibited by the pan-caspase inhibitor, zVAD-fmk, evidence suggests that these pathways were not caspase-dependent apoptosis. We also ruled out necroptosis and pyroptosis. Rather, the combination of ricin plus TNF-α or FasL induced cathepsin-dependent cell death, as evidenced by the use of several pharmacologic inhibitors. We postulate that the effects of zVAD-fmk were due to the molecule’s known off-target effects on cathepsin activity. This work demonstrates that ricin-induced lung epithelial cell killing occurs by distinct cell death pathways dependent on the presence of different sensitizing cytokines, TRAIL, TNF-α, or FasL.

Regulated in Development and DNA Damage Response 1 Knockdown Alleviates Lipopolysaccharide-Induced Acute Lung Injury

2021 ◽  
Vol 11 (7) ◽  
pp. 1333-1338
Author(s):  
Han Han ◽  
Zhenxi Yu ◽  
Mei Feng
Keyword(s):  
Acute Lung Injury ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Lung Injury ◽  
Cell Activity ◽  
Lung Epithelial Cells ◽  
Lung Epithelial Cell ◽  
Inflammatory Factors ◽  
Lung Epithelial ◽  
Damage Response

Regulated in Development and DNA Damage Response 1 (REDD1) knockdown can reduce the endoplasmic reticulum stress response in liver injury. However, its role on lipopolysaccharide (LPS)-induced acute lung injury (ALI) has not been explored. This study aimed to evaluate the effect of REDD1 on lung epithelial cells induced by LPS. Rt-qPCR and Western blot were used to detect REDD1 expression in 16HBE cells induced by LPS. The interfering REDD1 plasmid was constructed, and CCK8 was used to detect the effect of interference with REDD1 on LPS-induced lung epithelial cell activity. The expression of inflammatory factors was detected by ELISA and the apoptotic level was detected by TUNEL staining. String database was used to predict the combination of REDD1 and EP300 in lung epithelial cells, which was verified by CoIP experiment. An overexpressed plasmid of EP300 was constructed to detect the effects of EP300 on inflammatory factors and apoptosis in REDD1 lung epithelial cells. LPS-induced increased REDD1 expression in lung epithelial cells. Interference with REDD1 inhibits LPS-induced lung epithelial cell activity injury and inflammatory factor expression and inhibits LPS-induced lung epithelial cell apoptosis. After interference with REDD1, the expression of EP300 in LPS-induced lung epithelial cells was inhibited, and the overexpression of EP300 was reversed to promote the production of inflammatory factors and apoptosis. In conclusion, these results demonstrate that REDD1 knockdown alleviates LPS-induced acute lung injury.

Captopril inhibits apoptosis in human lung epithelial cells: a potential antifibrotic mechanism

1998 ◽  
Vol 275 (5) ◽  
pp. L1013-L1017 ◽  
Author(s):  
Bruce D. Uhal ◽  
Claudia Gidea ◽  
Raed Bargout ◽  
Antonio Bifero ◽  
Olivia Ibarra-Sunga ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Pulmonary Fibrosis ◽  
Dna Fragmentation ◽  
Cell Apoptosis ◽  
Human Lung ◽  
Lung Epithelial Cells ◽  
Lung Epithelial ◽  
Epithelial Cell Apoptosis

The angiotensin-converting enzyme inhibitor captopril has been shown to inhibit fibrogenesis in the lung, but the mechanisms underlying this action are unclear. Apoptosis of lung epithelial cells is believed to be involved in the pathogenesis of pulmonary fibrosis. For these reasons, we studied the effect of captopril on Fas-induced apoptosis in a human lung epithelial cell line. Monoclonal antibodies that activate the Fas receptor induced epithelial cell apoptosis as detected by chromatin condensation, nuclear fragmentation, DNA fragmentation, and increased activities of caspase-1 and -3. Apoptosis was not induced by isotype-matched nonimmune mouse immunoglobulins or nonactivating anti-Fas monoclonal antibodies. When applied simultaneously with anti-Fas antibodies, 50 ng/ml of captopril completely abrogated apoptotic indexes based on morphology, DNA fragmentation, and inducible caspase-1 activity and significantly decreased the inducible activity of caspase-3. Inhibition of apoptosis by captopril was concentration dependent, with an IC50 of 70 pg/ml. These data suggest that the inhibitory actions of captopril on pulmonary fibrosis may be related to prevention of lung epithelial cell apoptosis.

scholarly journals Lung epithelial cell-derived extracellular vesicles activate macrophage-mediated inflammatory responses via ROCK1 pathway

2015 ◽  
Vol 6 (12) ◽  
pp. e2016-e2016 ◽  
Author(s):  
H-G Moon ◽  
Y Cao ◽  
J Yang ◽  
J H Lee ◽  
H S Choi ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Extracellular Vesicles ◽  
Caspase 3 ◽  
Inflammatory Responses ◽  
Lung Epithelial Cells ◽  
Lung Epithelial Cell ◽  
Apoptotic Bodies ◽  
Protein Markers ◽  
Lung Epithelial

Abstract Despite decades of research, the pathogenesis of acute respiratory distress syndrome (ARDS) remains poorly understood, thus impeding the development of effective treatment. Diffuse alveolar damage (DAD) and lung epithelial cell death are prominent features of ARDS. Lung epithelial cells are the first line of defense after inhaled stimuli, such as in the case of hyperoxia. We hypothesized that lung epithelial cells release ‘messenger’ or signaling molecules to adjacent or distant macrophages, thereby initiating or propagating inflammatory responses after noxious insult. We found that, after hyperoxia, a large amount of extracellular vesicles (EVs) were generated and released into bronchoalveolar lavage fluid (BALF). These hyperoxia-induced EVs were mainly derived from live lung epithelial cells as the result of hyperoxia-associated endoplasmic reticulum (ER) stress. These EVs were remarkably different from epithelial ‘apoptotic bodies’, as reflected by the significantly smaller size and differentially expressed protein markers. These EVs fall mainly in the size range of the exosomes and smaller microvesicles (MVs) (50–120 nm). The commonly featured protein markers of apoptotic bodies were not found in these EVs. Treating alveolar macrophages with hyperoxia-induced, epithelial cell-derived EVs led to an increased secretion of pro-inflammatory cytokines and macrophage inflammatory protein 2 (MIP-2). Robustly increased macrophage and neutrophil influx was found in the lung tissue of the mice intranasally treated with hyperoxia-induced EVs. It was determined that EV-encapsulated caspase-3 was largely responsible for the alveolar macrophage activation via the ROCK1 pathway. Caspase-3-deficient EVs induced less cytokine/MIP-2 release, reduced cell counts in BALF, less neutrophil infiltration and less inflammation in lung parenchyma, both in vitro and in vivo. Furthermore, the serum circulating EVs were increased and mainly derived from lung epithelial cells after hyperoxia exposure. These circulating EVs also activated systemic macrophages other than the alveolar ones. Collectively, the results show that hyperoxia-induced, lung epithelial cell-derived and caspase-3 enriched EVs activate macrophages and mediate the inflammatory lung responses involved in lung injury.

scholarly journals The LIM-domain only protein 4 contributes to lung epithelial cell proliferation but is not essential for tumor progression

2015 ◽  
Vol 16 (1) ◽  
Author(s):  
Aliaksei Z. Holik ◽  
Caitlin E. Filby ◽  
Julie Pasquet ◽  
Kati Viitaniemi ◽  
John Ciciulla ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Epithelial Cell ◽  
Tumor Progression ◽  
Lung Epithelial Cell ◽  
Epithelial Cell Proliferation ◽  
Lim Domain ◽  
Lung Epithelial

The fibrinolytic system and the regulation of lung epithelial cell proteolysis, signaling, and cellular viability

2008 ◽  
Vol 295 (6) ◽  
pp. L967-L975 ◽  
Author(s):  
Sreerama Shetty ◽  
Joseph Padijnayayveetil ◽  
Torry Tucker ◽  
Dorota Stankowska ◽  
Steven Idell
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Plasminogen Activator ◽  
Mrna Stability ◽  
Fibrinolytic System ◽  
Lung Epithelial Cells ◽  
Lung Epithelial Cell ◽  
Plasminogen Activator Inhibitor 1 ◽  
Lung Epithelial ◽  
Pai 1

The urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1) are key components of the fibrinolytic system and are expressed by lung epithelial cells. uPA, uPAR, and PAI-1 have been strongly implicated in the pathogenesis of acute lung injury (ALI) and pulmonary fibrosis. Recently, it has become clear that regulation of uPA, uPAR, and PAI-1 occurs at the posttranscriptional level of mRNA stability in lung epithelial cells. uPA further mediates its own expression in these cells as well as that of uPAR and PAI-1 through induction of changes in mRNA stability. In addition, uPA-mediated signaling controls the expression of the tumor suppressor protein p53 in lung epithelial cells at the posttranslational level. p53 has recently been shown to be a trans-acting uPA, uPAR, and PAI-1 mRNA-binding protein that regulates the stability of these mRNAs. It is now clear that signaling initiated by uPA mediates dose-dependent regulation of lung epithelial cell apoptosis and likewise involves changes in p53, uPA, uPAR, and PAI-1 expression. These findings demonstrate that the uPA-uPAR-PAI-1 system of lung epithelial cells mediates a broad repertoire of responses that encompass but extend well beyond traditional fibrinolysis, involve newly recognized interactions with p53 that influence the viability of the lung epithelium, and are thereby implicated in the pathogenesis of ALI and its repair.

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