scholarly journals Cell-Free Hemoglobin Does Not Attenuate the Effects of SARS-CoV-2 Spike Protein S1 Subunit in Pulmonary Endothelial Cells

2021 ◽  
Vol 22 (16) ◽  
pp. 9041
Author(s):  
Sirsendu Jana ◽  
Michael R. Heaven ◽  
Abdu I. Alayash
Keyword(s):  
Endothelial Cells ◽  
Hypoxia Inducible Factor ◽  
Spike Protein ◽  
Receptor Interaction ◽  
Low Oxygen ◽  
Viral Receptor ◽  
Hypoxic Conditions ◽  
Viral Components ◽  
Induced Changes ◽  
The Impact

SARS-CoV-2 primarily infects epithelial airway cells that express the host entry receptor angiotensin-converting enzyme 2 (ACE2), which binds to the S1 spike protein on the surface of the virus. To delineate the impact of S1 spike protein interaction with the ACE2 receptor, we incubated the S1 spike protein with human pulmonary arterial endothelial cells (HPAEC). HPAEC treatment with the S1 spike protein caused disruption of endothelial barrier function, increased levels of numerous inflammatory molecules (VCAM-1, ICAM-1, IL-1β, CCL5, CXCL10), elevated mitochondrial reactive oxygen species (ROS), and a mild rise in glycolytic reserve capacity. Because low oxygen tension (hypoxia) is associated with severe cases of COVID-19, we also evaluated treatment with hemoglobin (HbA) as a potential countermeasure in hypoxic and normal oxygen environments in analyses with the S1 spike protein. We found hypoxia downregulated the expression of the ACE2 receptor and increased the critical oxygen homeostatic signaling protein, hypoxia-inducible factor (HIF-1α); however, treatment of the cells with HbA yielded no apparent change in the levels of ACE2 or HIF-1α. Use of quantitative proteomics revealed that S1 spike protein-treated cells have few differentially regulated proteins in hypoxic conditions, consistent with the finding that ACE2 serves as the host viral receptor and is reduced in hypoxia. However, in normoxic conditions, we found perturbed abundance of proteins in signaling pathways related to lysosomes, extracellular matrix receptor interaction, focal adhesion, and pyrimidine metabolism. We conclude that the spike protein alone without the rest of the viral components is sufficient to elicit cell signaling in HPAEC, and that treatment with HbA failed to reverse the vast majority of these spike protein-induced changes.

scholarly journals Hypoxic induction of an HIF-1α–dependent bFGF autocrine loop drives angiogenesis in human endothelial cells

Blood ◽  
2006 ◽  
Vol 107 (7) ◽  
pp. 2705-2712 ◽  
Author(s):  
Maura Calvani ◽  
Annamaria Rapisarda ◽  
Badarch Uranchimeg ◽  
Robert H. Shoemaker ◽  
Giovanni Melillo
Keyword(s):  
Endothelial Cells ◽  
Mammalian Cells ◽  
Neutralizing Antibodies ◽  
Umbilical Vein ◽  
Hypoxia Inducible Factor ◽  
Transcriptional Response ◽  
Low Oxygen ◽  
Autocrine Loop ◽  
Hypoxic Induction ◽  
Hypoxic Conditions

AbstractHypoxia is a major pathophysiological condition for the induction of angiogenesis, which is a crucial aspect of growth in solid tumors. In mammalian cells, the transcriptional response to oxygen deprivation is largely mediated by hypoxia-inducible factor 1 (HIF-1), a heterodimer composed of HIF-1α and HIF-1β subunits. However, the response of endothelial cells to hypoxia and the specific involvement of HIF-α subunits in this process are still poorly understood. We show that human umbilical vein endothelial cells (HUVECs) cultured in the absence of growth factors survive and form tubelike structures when cultured under hypoxic, but not normoxic, conditions. HUVECs expressed both HIF-1α and HIF-2α when cultured under hypoxic conditions. Transfection of HIF-1α, but not HIF-2α, siRNA to HUVECs completely abrogated hypoxic induction of cords. Neutralizing antibodies to bFGF, but not IGF-1, VEGF, or PDGF-BB, blocked survival and sprouting of HUVECs under hypoxic conditions, suggesting the existence of an autocrine loop induced by low oxygen levels. Notably, bFGF-dependent induction of cord formation under normoxic conditions required HIF-1α activity, which was also essential for hypoxic induction of bFGF mRNA and protein expression. These results uncover the existence of an HIF-1α–bFGF amplification pathway that mediates survival and sprouting of endothelial cells under hypoxic conditions.

scholarly journals The Effects of Aβ1-42 Binding to the SARS-CoV-2 Spike Protein S1 Subunit and Angiotensin-Converting Enzyme 2

2021 ◽  
Vol 22 (15) ◽  
pp. 8226
Author(s):  
John Tsu-An Hsu ◽  
Chih-Feng Tien ◽  
Guann-Yi Yu ◽  
Santai Shen ◽  
Yi-Hsuan Lee ◽  
...  
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Viral Entry ◽  
Negative Impact ◽  
Spike Protein ◽  
Infection Model ◽  
Converting Enzyme ◽  
Viral Receptor ◽  
Angiotensin Converting Enzyme 2 ◽  
People With Dementia ◽  
The Impact

Increasing evidence suggests that elderly people with dementia are vulnerable to the development of severe coronavirus disease 2019 (COVID-19). In Alzheimer’s disease (AD), the major form of dementia, β-amyloid (Aβ) levels in the blood are increased; however, the impact of elevated Aβ levels on the progression of COVID-19 remains largely unknown. Here, our findings demonstrate that Aβ1-42, but not Aβ1-40, bound to various viral proteins with a preferentially high affinity for the spike protein S1 subunit (S1) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the viral receptor, angiotensin-converting enzyme 2 (ACE2). These bindings were mainly through the C-terminal residues of Aβ1-42. Furthermore, Aβ1-42 strengthened the binding of the S1 of SARS-CoV-2 to ACE2 and increased the viral entry and production of IL-6 in a SARS-CoV-2 pseudovirus infection model. Intriguingly, data from a surrogate mouse model with intravenous inoculation of Aβ1-42 show that the clearance of Aβ1-42 in the blood was dampened in the presence of the extracellular domain of the spike protein trimers of SARS-CoV-2, whose effects can be prevented by a novel anti-Aβ antibody. In conclusion, these findings suggest that the binding of Aβ1-42 to the S1 of SARS-CoV-2 and ACE2 may have a negative impact on the course and severity of SARS-CoV-2 infection. Further investigations are warranted to elucidate the underlying mechanisms and examine whether reducing the level of Aβ1-42 in the blood is beneficial to the fight against COVID-19 and AD.

scholarly journals Hypoxia-Induced Gene Expression Occurs Solely through the Action of Hypoxia-Inducible Factor 1α (HIF-1α): Role of Cytoplasmic Trapping of HIF-2α

2003 ◽  
Vol 23 (14) ◽  
pp. 4959-4971 ◽  
Author(s):  
Sang-ki Park ◽  
Agnes M. Dadak ◽  
Volker H. Haase ◽  
Lucrezia Fontana ◽  
Amato J. Giaccia ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptional Activity ◽  
Hypoxia Inducible Factor ◽  
Low Oxygen ◽  
Hypoxic Conditions ◽  
Show Evidence ◽  
Dependent Protein ◽  
A Cell ◽  
Cell Type Specific ◽  
Inducible Genes

ABSTRACT The hypoxia-inducible factors 1α (HIF-1α) and 2α (HIF-2α) have extensive structural homology and have been identified as key transcription factors responsible for gene expression in response to hypoxia. They play critical roles not only in normal development, but also in tumor progression. Here we report on the differential regulation of protein expression and transcriptional activity of HIF-1α and -2α by hypoxia in immortalized mouse embryo fibroblasts (MEFs). We show that oxygen-dependent protein degradation is restricted to HIF-1α, as HIF-2α protein is detected in MEFs regardless of oxygenation and is localized primarily to the cytoplasm. Endogenous HIF-2α remained transcriptionally inactive under hypoxic conditions; however, ectopically overexpressed HIF-2α translocated into the nucleus and could stimulate expression of hypoxia-inducible genes. We show that the factor inhibiting HIF-1 can selectively inhibit the transcriptional activity of HIF-1α but has no effect on HIF-2α-mediated transcription in MEFs. We propose that HIF-2α is not a redundant transcription factor of HIF-1α for hypoxia-induced gene expression and show evidence that there is a cell type-specific modulator(s) that enables selective activation of HIF-1α but not HIF-2α in response to low-oxygen stress.

scholarly journals The Response of Macrophages and Neutrophils to Hypoxia in the Context of Cancer and Other Inflammatory Diseases

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Antje Egners ◽  
Merve Erdem ◽  
Thorsten Cramer
Keyword(s):  
Endothelial Cells ◽  
Inflammatory Diseases ◽  
Neutrophil Function ◽  
Proper Function ◽  
Low Oxygen ◽  
Bacterial Killing ◽  
Molecular Responses ◽  
Chronic Inflammatory Diseases ◽  
Hypoxic Conditions ◽  
Cellular Components

Lack of oxygen (hypoxia) is a hallmark of a multitude of acute and chronic diseases and can be either beneficial or detrimental for organ restitution and recovery. In the context of inflammation, hypoxia is particularly important and can significantly influence the course of inflammatory diseases. Macrophages and neutrophils, the chief cellular components of innate immunity, display distinct properties when exposed to hypoxic conditions. Virtually every aspect of macrophage and neutrophil function is affected by hypoxia, amongst others, morphology, migration, chemotaxis, adherence to endothelial cells, bacterial killing, differentiation/polarization, and protumorigenic activity. Prominent arenas of macrophage and neutrophil function, for example, acute/chronic inflammation and the microenvironment of solid tumors, are characterized by low oxygen levels, demonstrating the paramount importance of the hypoxic response for proper function of these cells. Members of the hypoxia-inducible transcription factor (HIF) family emerged as pivotal molecular regulators of macrophages and neutrophils. In this review, we will summarize the molecular responses of macrophages and neutrophils to hypoxia in the context of cancer and other chronic inflammatory diseases and discuss the potential avenues for therapeutic intervention that arise from this knowledge.

scholarly journals Hypoxic Environment Promotes Barrier Formation in Human Intestinal Epithelial Cells through Regulation of MicroRNA 320a Expression

2019 ◽  
Vol 39 (14) ◽  
Author(s):  
Stephanie Muenchau ◽  
Rosalie Deutsch ◽  
Ines J. de Castro ◽  
Thomas Hielscher ◽  
Nora Heber ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Mirna Expression ◽  
Barrier Function ◽  
Intestinal Epithelial Cells ◽  
Hypoxia Inducible Factor ◽  
Intestinal Epithelial ◽  
Low Oxygen ◽  
Direct Role ◽  
Hypoxic Conditions ◽  
Barrier Formation

ABSTRACT Intestinal epithelial cells (IECs) are exposed to the low-oxygen environment present in the lumen of the gut. These hypoxic conditions on one hand are fundamental for the survival of the commensal microbiota and, on the other hand, favor the formation of a selective semipermeable barrier, allowing IECs to transport essential nutrients/water while keeping the sterile internal compartments separated from the lumen containing commensals. The hypoxia-inducible factor (HIF) complex, which allows cells to respond and adapt to fluctuations in oxygen levels, has been described as a key regulator in maintaining IEC barrier function by regulating their tight junction integrity. In this study, we sought to better evaluate the mechanisms by which low oxygen conditions impact the barrier function of human IECs. By profiling miRNA expression in IECs under hypoxia, we identified microRNA 320a (miRNA-320a) as a novel barrier formation regulator. Using pharmacological inhibitors and short hairpin RNA-mediated silencing, we could demonstrate that expression of this microRNA (miRNA) was HIF dependent. Importantly, using overexpression and knockdown approaches of miRNA-320a, we could confirm its direct role in the regulation of barrier function in human IECs. These results reveal an important link between miRNA expression and barrier integrity, providing a novel insight into mechanisms of hypoxia-driven epithelial homeostasis.

scholarly journals Hif-1α and Hif-2α synergize to suppress AML development but are dispensable for disease maintenance

2015 ◽  
Vol 212 (13) ◽  
pp. 2223-2234 ◽  
Author(s):  
Milica Vukovic ◽  
Amelie V. Guitart ◽  
Catarina Sepulveda ◽  
Arnaud Villacreces ◽  
Eoghan O'Duibhir ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Hypoxia Inducible Factor ◽  
Leukemic Cells ◽  
Wild Type ◽  
Hypoxic Conditions ◽  
Downstream Effectors ◽  
Human Acute Myeloid Leukemia ◽  
Genetic Deletion ◽  
Hif Pathway ◽  
The Impact

Leukemogenesis occurs under hypoxic conditions within the bone marrow (BM). Knockdown of key mediators of cellular responses to hypoxia with shRNA, namely hypoxia-inducible factor-1α (HIF-1α) or HIF-2α, in human acute myeloid leukemia (AML) samples results in their apoptosis and inability to engraft, implicating HIF-1α or HIF-2α as therapeutic targets. However, genetic deletion of Hif-1α has no effect on mouse AML maintenance and may accelerate disease development. Here, we report the impact of conditional genetic deletion of Hif-2α or both Hif-1α and Hif-2α at different stages of leukemogenesis in mice. Deletion of Hif-2α accelerates development of leukemic stem cells (LSCs) and shortens AML latency initiated by Mll-AF9 and its downstream effectors Meis1 and Hoxa9. Notably, the accelerated initiation of AML caused by Hif-2α deletion is further potentiated by Hif-1α codeletion. However, established LSCs lacking Hif-2α or both Hif-1α and Hif-2α propagate AML with the same latency as wild-type LSCs. Furthermore, pharmacological inhibition of the HIF pathway or HIF-2α knockout using the lentiviral CRISPR-Cas9 system in human established leukemic cells with MLL-AF9 translocation have no impact on their functions. We therefore conclude that although Hif-1α and Hif-2α synergize to suppress the development of AML, they are not required for LSC maintenance.

scholarly journals Transcriptome sequencing revealed differences in the response of renal cancer cells to hypoxia and CoCl2 treatment

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 1518 ◽  
Author(s):  
Nadezhda Zhigalova ◽  
Artem Artemov ◽  
Alexander M. Mazur ◽  
Egor B. Prokhortchouk
Keyword(s):  
Cancer Cells ◽  
Human Cancer ◽  
Hypoxia Inducible Factor ◽  
Low Oxygen ◽  
Human Cancer Cells ◽  
Hypoxic Conditions ◽  
Pathway Activation ◽  
Oxygen Conditions ◽  
Order Of Magnitude ◽  
Transcriptional Changes

Human cancer cells are subjected to hypoxic conditions in many tumours. Hypoxia causes alterations in the glycolytic pathway activation through stabilization of hypoxia-inducible factor 1. Currently, two approaches are commonly used to model hypoxia: an alternative to generating low-oxygen conditions in an incubator, cells can be treated with CoCl2. We performed RNA-seq experiments to study transcriptomes of human Caki-1 cells under real hypoxia and after CoCl2 treatment. Despite causing transcriptional changes of a much higher order of magnitude for the genes in the hypoxia regulation pathway, CoCl2 treatment fails to induce alterations in the glycolysis / gluconeogenesis pathway. Moreover, CoCl2 caused aberrant activation of other oxidoreductases in glycine, serine and threonine metabolism pathways.

scholarly journals Hypoxic environment promotes barrier formation in human intestinal epithelial cells through regulation of miRNA-320a expression

2018 ◽  
Author(s):  
Stephanie Muenchau ◽  
Rosalie Deutsch ◽  
Thomas Hielscher ◽  
Nora Heber ◽  
Beate Niesler ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Mirna Expression ◽  
Barrier Function ◽  
Intestinal Epithelial Cells ◽  
Hypoxia Inducible Factor ◽  
Intestinal Epithelial ◽  
Low Oxygen ◽  
Direct Role ◽  
Hypoxic Conditions ◽  
Barrier Formation

AbstractIntestinal epithelial cells (IECs) are exposed to the low-oxygen environment present in the lumen of the gut. These hypoxic conditions are on one hand fundamental for the survival of the commensal microbiota, and on the other hand, favor the formation of a selective semipermeable barrier allowing IECs to transport essential nutrients/water while keeping the sterile internal compartments separated from the lumen containing commensals. The hypoxia-inducible factor (HIF) complex, which allows cells to respond and adapt to fluctuations in oxygen levels, has been described as a key regulator in maintaining IEC barrier function by regulating their tight junction integrity. In this study, we sought to better evaluate the mechanisms by which low oxygen conditions impact the barrier function of human IECs. By profiling miRNA expression in IECs under hypoxia, we identified miRNA-320a as a novel barrier formation regulator. Using pharmacological inhibitors and short hairpin RNA-mediated silencing we could demonstrate that expression of this miRNA was HIF-dependent. Importantly, using over-expression and knock-down approaches of miRNA-320a we could confirm its direct role in the regulation of barrier functions in human IECs. These results reveal an important link between miRNA expression and barrier integrity, providing a novel insight into mechanisms of hypoxia-driven epithelial homeostasis.

scholarly journals Glutamine Homeostasis and Its Role in the Adaptive Strategies of the Blind Mole Rat, Spalax

Metabolites ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 755
Author(s):  
Dmitry Miskevich ◽  
Anastasia Chaban ◽  
Maria Dronina ◽  
Ifat Abramovich ◽  
Eyal Gottlieb ◽  
...  
Keyword(s):  
Healthy Aging ◽  
Pyruvate Dehydrogenase Complex ◽  
Hypoxia Inducible Factor ◽  
Primary Source ◽  
Hypoxia Tolerance ◽  
Cancer Resistance ◽  
Low Oxygen ◽  
Hypoxic Conditions ◽  
Mole Rat ◽  
Tightly Coupled

Oxidative metabolism is fine-tuned machinery that combines two tightly coupled fluxes of glucose and glutamine-derived carbons. Hypoxia interrupts the coordination between the metabolism of these two nutrients and leads to a decrease of the system efficacy and may eventually cause cell death. The subterranean blind mole rat, Spalax, is an underexplored, underground, hypoxia-tolerant mammalian group which spends its life under sharply fluctuating oxygen levels. Primary Spalax cells are an exceptional model to study the metabolic strategies that have evolved in mammals inhabiting low-oxygen niches. In this study we explored the metabolic frame of glutamine (Gln) homeostasis in Spalax skin cells under normoxic and hypoxic conditions and their impacts on the metabolism of rat cells. Targeted metabolomics employing liquid chromatography and mass spectrometry (LC-MS) was used to track the fate of heavy glutamine carbons (13C5 Gln) after 24 h under normoxia or hypoxia (1% O2). Our results indicated that large amounts of glutamine-originated carbons were detected as proline (Pro) and hydroxyproline (HPro) in normoxic Spalax cells with a further increase under hypoxia, suggesting a strategy for reduced Gln carbons storage in proteins. The intensity of the flux and the presence of HPro suggests collagen as a candidate protein that is most abundant in animals, and as the primary source of HPro. An increased conversion of αKG to 2 HG that was indicated in hypoxic Spalax cells prevents the degradation of hypoxia-inducible factor 1α (HIF-1α) and, consequently, maintains cytosolic and mitochondrial carbons fluxes that were uncoupled via inhibition of the pyruvate dehydrogenase complex. A strong antioxidant defense in Spalax cells can be attributed, at least in part, to the massive usage of glutamine-derived glutamate for glutathione (GSH) production. The present study uncovers additional strategies that have evolved in this unique mammal to support its hypoxia tolerance, and probably contribute to its cancer resistance, longevity, and healthy aging.

scholarly journals Hypoxia Pathway Proteins in Normal and Malignant Hematopoiesis

Cells ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 155 ◽  
Author(s):  
Ben Wielockx ◽  
Tatyana Grinenko ◽  
Peter Mirtschink ◽  
Triantafyllos Chavakis
Keyword(s):  
Cell Fate ◽  
Current Knowledge ◽  
Hypoxia Inducible Factor ◽  
Adult Life ◽  
Low Oxygen ◽  
Hematopoietic Stem ◽  
Metabolism Regulation ◽  
Hsc Niche ◽  
Hif Pathway ◽  
The Impact

The regulation of oxygen (O2) levels is crucial in embryogenesis and adult life, as O2 controls a multitude of key cellular functions. Low oxygen levels (hypoxia) are relevant for tissue physiology as they are integral to adequate metabolism regulation and cell fate. Hence, the hypoxia response is of utmost importance for cell, organ and organism function and is dependent on the hypoxia-inducible factor (HIF) pathway. HIF pathway activity is strictly regulated by the family of oxygen-sensitive HIF prolyl hydroxylase domain (PHD) proteins. Physiologic hypoxia is a hallmark of the hematopoietic stem cell (HSC) niche in the bone marrow. This niche facilitates HSC quiescence and survival. The present review focuses on current knowledge and the many open questions regarding the impact of PHDs/HIFs and other proteins of the hypoxia pathway on the HSC niche and on normal and malignant hematopoiesis.

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