scholarly journals Integrin activation is an essential component of SARS-CoV-2 infection

2021 ◽  
Author(s):  
Peter Simons ◽  
Derek Rinaldi ◽  
Virginie Bondu ◽  
Alison Kell ◽  
Steven Bradfute ◽  
...  
Keyword(s):  
Cell Entry ◽  
Productive Infection ◽  
Integrin Activation ◽  
Angiotensin Converting Enzyme 2 ◽  
Binding Function ◽  
Cell Permeable Peptide ◽  
Level 3 ◽  
Integrin Antagonists ◽  
Activity State

Cellular entry of coronaviruses depends on binding of the viral spike (S) protein to a specific cellular receptor, the angiotensin-converting enzyme 2 (ACE2). Furthermore, the viral spike protein expresses an RGD motif, suggesting that cell surface integrins may be attachment co-receptors. However, using infectious SARS-CoV-2 requires a biosafety level 3 laboratory (BSL-3), which limits the techniques that can be used to study the mechanism of cell entry. Here, we UV-inactivated SARS-CoV-2 and fluorescently labeled the envelope membrane with octadecyl rhodamine B (R18) to explore the role of integrin activation in mediating both cell entry and productive infection. We used flow cytometry and confocal fluorescence microscopy to show that fluorescently labeled SARS-CoV-2R18 particles engage basal-state integrins. Furthermore, we demonstrate that Mn2+, which activates integrins and induces integrin extension, enhances cell binding and entry of SARS-CoV-2R18 in proportion to the fraction of integrins activated. We also show that one class of integrin antagonist, which binds to the αI MIDAS site and stabilizes the inactive, closed conformation, selectively inhibits the engagement of SARS-CoV-2R18 with basal state integrins, but is ineffective against Mn2+-activated integrins. At the same time, RGD-integrin antagonists inhibited SARS-CoV-2R18 binding regardless of integrin activity state. Integrins transmit signals bidirectionally: 'inside-out' signaling primes the ligand binding function of integrins via a talin dependent mechanism and 'outside-in' signaling occurs downstream of integrin binding to macromolecular ligands. Outside-in signaling is mediated by Gα13 and induces cell spreading, retraction, migration, and proliferation. Using cell-permeable peptide inhibitors of talin, and Gα13 binding to the cytoplasmic tail of an integrin's β subunit, we further demonstrate that talin-mediated signaling is essential for productive infection by SARS-CoV-2.

scholarly journals Integrin activation is an essential component of SARS-CoV-2 infection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Peter Simons ◽  
Derek A. Rinaldi ◽  
Virginie Bondu ◽  
Alison M. Kell ◽  
Steven Bradfute ◽  
...  
Keyword(s):  
Peptide Inhibitors ◽  
Cell Entry ◽  
Productive Infection ◽  
Integrin Activation ◽  
S Protein ◽  
Angiotensin Converting Enzyme 2 ◽  
Binding Function ◽  
Cell Permeable Peptide ◽  
Integrin Antagonists

AbstractSARS-CoV-2 infection depends on binding its spike (S) protein to angiotensin-converting enzyme 2 (ACE2). The S protein expresses an RGD motif, suggesting that integrins may be co-receptors. Here, we UV-inactivated SARS-CoV-2 and fluorescently labeled the envelope membrane with octadecyl rhodamine B (R18) to explore the role of integrin activation in mediating cell entry and productive infection. We used flow cytometry and confocal microscopy to show that SARS-CoV-2R18 particles engage basal-state integrins. Furthermore, we demonstrate that Mn2+, which induces integrin extension, enhances cell entry of SARS-CoV-2R18. We also show that one class of integrin antagonist, which binds to the αI MIDAS site and stabilizes the inactive, closed conformation, selectively inhibits the engagement of SARS-CoV-2R18 with basal state integrins, but is ineffective against Mn2+-activated integrins. RGD-integrin antagonists inhibited SARS-CoV-2R18 binding regardless of integrin activation status. Integrins transmit signals bidirectionally: 'inside-out' signaling primes the ligand-binding function of integrins via a talin-dependent mechanism, and 'outside-in' signaling occurs downstream of integrin binding to macromolecular ligands. Outside-in signaling is mediated by Gα13. Using cell-permeable peptide inhibitors of talin and Gα13 binding to the cytoplasmic tail of an integrin's β subunit, we demonstrate that talin-mediated signaling is essential for productive infection.

scholarly journals Angiotensin-Converting Enzyme 2 (ACE2) in the Pathogenesis of ARDS in COVID-19

2021 ◽  
Vol 12 ◽  
Author(s):  
Keiji Kuba ◽  
Tomokazu Yamaguchi ◽  
Josef M. Penninger
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Neutralizing Antibodies ◽  
Cell Entry ◽  
Converting Enzyme ◽  
Sars Coronavirus ◽  
Angiotensin Converting Enzyme 2 ◽  
Infected People ◽  
Critical Attention ◽  
Novel Coronavirus

Seventeen years after the epidemic of SARS coronavirus, a novel coronavirus SARS-CoV-2-emerged resulting in an unprecedented pandemic. Angiotensin-converting enzyme 2 (ACE2) is an essential receptor for cell entry of SARS-CoV-2 as well as the SARS coronavirus. Despite many similarities to SARS coronavirus, SARS-CoV-2 exhibits a higher affinity to ACE2 and shows higher infectivity and transmissibility, resulting in explosive increase of infected people and COVID-19 patients. Emergence of the variants harboring mutations in the receptor-binding domain of the Spike protein has drawn critical attention to the interaction between ACE2 and Spike and the efficacies of vaccines and neutralizing antibodies. ACE2 is a carboxypeptidase which degrades angiotensin II, B1-bradykinin, or apelin, and thereby is a critical regulator of cardiovascular physiology and pathology. In addition, the enzymatic activity of ACE2 is protective against acute respiratory distress syndrome (ARDS) caused by viral and non-viral pneumonias, aspiration, or sepsis. Upon infection, both SARS-CoV-2 and SARS coronaviruses downregulates ACE2 expression, likely associated with the pathogenesis of ARDS. Thus, ACE2 is not only the SARS-CoV-2 receptor but might also play an important role in multiple aspects of COVID-19 pathogenesis and possibly post-COVID-19 syndromes. Soluble forms of recombinant ACE2 are currently utilized as a pan-variant decoy to neutralize SARS-CoV-2 and a supplementation of ACE2 carboxypeptidase activity. Here, we review the role of ACE2 in the pathology of ARDS in COVID-19 and the potential application of recombinant ACE2 protein for treating COVID-19.

Abstract 51: A Critical Role for Outside-In Signaling of Integrin AlphalIIIb/Beta3 in Shear-Dependent Platelet Microvesicle Formation and Phosphatidylerine Exposure

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Aiming Pang ◽  
Yujie Cui ◽  
Michael K Delaney ◽  
Aleksandra Stojanovic-Terpo ◽  
Xiaoping Du
Keyword(s):  
Flow Cytometry ◽  
Shear Stress ◽  
Critical Role ◽  
Selective Inhibitor ◽  
Wild Type ◽  
Activated Platelets ◽  
Binding Function ◽  
Integrin Antagonists ◽  
Dependent Signaling Pathway

Platelets promote coagulation mainly by exposing membrane phosphatidylserine (PS) and releasing PS-expressing microvesicles (MV). We have recently shown that PS exposure and MV release induced by platelet agonists requires shear stress. To identify the receptor responsible for the shear-dependent signaling leading to PS exposure and MV release, we compared platelets from β 3 -/- mice and wild-type mice in MV release and PS exposure under defined shear stress introduced using a cone-plate rheometer. MV release and PS exposure were determined using flow cytometry. Shear-dependent PS exposure and MV release were significantly suppressed in β 3 -/- platelets. Similarly, Wild type platelets treated with integrin antagonists also showed defective PS exposure and MV release. These data indicate an important role for the ligand binding function of integrin αιιb/β3 in shear-dependent MV release and PS exposure. To determine whether the role of integrin αιιb/β3 is due to its outside-in signaling, β 3 -/- platelets were transplanted with wild type β 3 or a mutant β 3 with the critical Gα13 binding site of the β 3 cytoplasmic domain (EEE) changed to alanines (AAA), which was previously shown to selectively abolish outside-in signaling of αIIb/β 3 . Transplantation of wild type β 3 rescued the defective MVs release and PS exposure of β 3 -/- platelets. In contrast, AAA mutant failed to rescue these defects. Consistently, wild type platelets treated with the selective inhibitor of Gα13-integrin interaction, inhibited integrin outside-in signaling and also PS exposure and MV release under shear stress. Furthermore, we also showed that the inhibition of Src, which is important in outside-in signaling downtream of Gα13, also abolished shear-dependent MV release and PS exposure. These data suggest that integrin outside-in signaling mediated by the Gα13-β 3 interaction and Src-dependent signaling pathway plays an important role in transmitting shear-induced mechanical signals leading to MV release and PS exposure in activated platelets.

scholarly journals When Off Target Effects Are On Target: The Role Of Spironolactone In Patients With COVID-19

2021 ◽  
Author(s):  
Christopher Stuart Wilcox ◽  
Bertram Pitt
Keyword(s):  
Cell Entry ◽  
Pubmed Central ◽  
Angiotensin Converting Enzyme 2 ◽  
Randomized Controlled Clinical Trials ◽  
Loss Of Libido ◽  
Viral Cell Entry ◽  
Poor Tolerability ◽  
Positive Results ◽  
Target Effects

Aims: Spironolactone is a steroidal mineralocoricosteroid receptor antagonist (MRA) used for treatment of resistant hypertension, heart failure and edema. It exerts class specific adverse effects that are shared by other MRAs. Additionally, it exerts unique “off target” steroidal effects that include gynecomastia, impotence and loss of libido in males and menstrual irregularity in females. Together, these have led to a poor tolerability and limited use despite positive results in many randomized, controlled clinical trials. We review the off-target effects of spironolactone that may summate with its MRA action to provide an advantageous profile for prevention or treatment of patients with COVID-19. Methods: Literature review using PubMed Central. Results: The blockade by spironolactone of the androgen receptor should diminish the expression of transmembrane protease serine 2 (TMPRSS2) that has an androgen promoter while its MRA action should enhance the expression of protease nexin1 (PN1) that inhibits furin and plasmin. TMPRSS2, furin and plasmin cooperated to process the SARS-CoV-2 spike protein to increase its high affinity binding to the angiotensin converting enzyme 2 (ACE2) and thereby promote viral cell entry. Its actions as an MRA may reduce inflammation and preserve pulmonary, cardiac and vascular functions. Its anti-plasmin action may combat hemostatic dysfunction. Conclusion: The hypothesis that the off-target effects of spironolactone summate with its MRA actions to provide special benefits for COVID-19 is worthy of direct investigation and clinical trial.

scholarly journals Expression and clinical significance of SARS-COV-2 receptor ACE2 in colon cancer

2020 ◽  
Author(s):  
Hui Nie ◽  
Yutong Wang ◽  
Geting Wu ◽  
Xiaoyun He ◽  
Zhiming Liao ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Severe Acute Respiratory Syndrome ◽  
Cell Entry ◽  
Converting Enzyme ◽  
Poor Survival ◽  
Bioinformatics Analyses ◽  
Angiotensin Converting Enzyme 2 ◽  
Cancer Tissues ◽  
Entry Receptor

Abstract Background: Angiotensin-converting enzyme 2 (ACE2), a crucial cell entry receptor for severe acute respiratory syndrome coronavirus 2, has been identified as an oncogene in some tumour types. However, its role in colon cancer is poorly understood.Methods: Integrative bioinformatics analyses were performed to uncover the role of ACE2 in colon cancer-associated immunology. Results: The results showed that ACE2 was overexpressed in colon cancer tissues and correlated with poor survival. Moreover, ACE2 expression was closely associated with the immune-infiltrating levels of CD4+ T, CD8+ T, and neutrophils. Conclusions: ACE2 is closely associated with colon cancer and may be involved in tumourigenesis and cancer–immune interactions, and could be a promising prognostic and therapeutic biomarker in colon cancer.

scholarly journals Rotavirus Glycoprotein NSP4 Is a Modulator of Viral Transcription in the Infected Cell

2005 ◽  
Vol 79 (24) ◽  
pp. 15165-15174 ◽  
Author(s):  
Lynn S. Silvestri ◽  
M. Alejandra Tortorici ◽  
Rodrigo Vasquez-Del Carpio ◽  
John T. Patton
Keyword(s):  
Cell Entry ◽  
Productive Infection ◽  
Viral Transcription ◽  
Loss Of Function ◽  
Genome Packaging ◽  
Particle Assembly ◽  
Virus Particles ◽  
Feedback Inhibitor ◽  
Dsrna Genome

ABSTRACT The outer shell of the rotavirus triple-layered virion is lost during cell entry, yielding a double-layered particle (DLP) that directs synthesis of viral plus-strand RNAs. The plus-strand RNAs act as templates for synthesis of the segmented double-stranded RNA (dsRNA) genome in viral inclusion bodies (viroplasms). The viral endoplasmic reticulum (ER)-resident glycoprotein NSP4 recruits progeny DLPs formed in viroplasms to the ER, where the particles are converted to triple-layered particles (TLPs) via budding. In this study, we have used short interfering RNAs to probe the role of NSP4 in the viral life cycle. Our analysis showed that knockdown of NSP4 expression had no marked effect on the expression of other viral proteins or on the replication of the dsRNA genome segments. However, NSP4 loss of function suppressed viroplasm maturation and caused a maldistribution of nonstructural and structural proteins that normally accumulate in viroplasms. NSP4 loss of function also inhibited formation of packaged virus particles, instead inducing the accumulation of empty particles. Most significant was the observation that NSP4 knockdown led to dramatically increased levels of viral transcription late in the infection cycle. These findings point to a multifaceted role for NSP4 in virus replication, including influencing the development of viroplasms, linking genome packaging with particle assembly, and acting as a modulator of viral transcription. By recruiting transcriptionally active or potentially active DLPs to the ER for conversion to quiescent TLPs, NSP4 acts as a feedback inhibitor down-regulating viral transcription when adequate levels of plus-strand RNAs are available to allow for productive infection.

Role of key point Mutations in Receptor Binding Domain of SARS-CoV-2 Spike Glycoprotein

2020 ◽  
Vol 20 ◽  
Author(s):  
Bipin Singh
Keyword(s):  
Receptor Binding ◽  
Point Mutations ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Spike Glycoprotein ◽  
Angiotensin Converting Enzyme 2 ◽  
Recent Outbreak ◽  
Novel Coronavirus ◽  
Genomic Similarity

: The recent outbreak of novel coronavirus (SARS-CoV-2 or 2019-nCoV) and its worldwide spread is posing one of the major threats to human health and the world economy. It has been suggested that SARS-CoV-2 is similar to SARSCoV based on the comparison of the genome sequence. Despite the genomic similarity between SARS-CoV-2 and SARSCoV, the spike glycoprotein and receptor binding domain in SARS-CoV-2 shows the considerable difference compared to SARS-CoV, due to the presence of several point mutations. The analysis of receptor binding domain (RBD) from recently published 3D structures of spike glycoprotein of SARS-CoV-2 (Yan, R., et al. (2020); Wrapp, D., et al. (2020); Walls, A. C., et al. (2020)) highlights the contribution of a few key point mutations in RBD of spike glycoprotein and molecular basis of its efficient binding with human angiotensin-converting enzyme 2 (ACE2).

scholarly journals Philosophers in research ethics committees—what do they think they’re doing? An empirical-ethical analysis

2021 ◽  
Author(s):  
Charlotte Gauckler
Keyword(s):  
Research Ethics ◽  
Applied Ethics ◽  
Ethics Committees ◽  
Research Ethics Committees ◽  
Structured Interviews ◽  
Discussion Section ◽  
Philosophical Perspective ◽  
Level 3 ◽  
Practical Level

AbstractResearch ethics committees in Germany usually don’t have philosophers as members and if so, only contingently, not provided for by statute. This is interesting from a philosophical perspective, assuming that ethics is a discipline of philosophy. It prompts the question what role philosophers play in those committees they can be found in. Eight qualitative semi-structured interviews were conducted to explore the self-perception of philosophers regarding their contribution to research ethics committees. The results show that the participants generally don’t view themselves as ethics experts. They are rather unanimous on the competencies they think they contribute to the committee but not as to whether those are philosophical competencies or applied ethical ones. In some cases they don’t see a big difference between their role and the role of the jurist member. In the discussion section of this paper I bring up three topics, prompted by the interviews, that need to be addressed: (1) I argue that the interviewees’ unwillingness to call themselves ethics experts might have to do with a too narrow understanding of ethics expertise. (2) I argue that the disagreement among the interviewees concerning the relationship between moral philosophy and applied ethics might be explained on a theoretical or on a practical level. (3) I argue that there is some lack of clarity concerning the relationship between ethics and law in research ethics committees and that further work needs to be done here. All three topics, I conclude, need further investigation.

scholarly journals Role of Tissue Factor in the Pathogenesis of COVID-19 and the Possible Ways to Inhibit It

2021 ◽  
Vol 27 ◽  
pp. 107602962110039
Author(s):  
Carlos A. Cañas ◽  
Felipe Cañas ◽  
Mario Bautista-Vargas ◽  
Fabio Bonilla-Abadía
Keyword(s):  
Tissue Factor ◽  
Proinflammatory Cytokines ◽  
Antiphospholipid Antibodies ◽  
Therapeutic Strategies ◽  
Prothrombotic State ◽  
Pulmonary Epithelium ◽  
Angiotensin Converting Enzyme 2 ◽  
Patients With Heart Failure ◽  
Inflammatory Effect

COVID-19 (Coronavirus Disease 2019) is a highly contagious infection and associated with high mortality rates, primarily in elderly; patients with heart failure; high blood pressure; diabetes mellitus; and those who are smokers. These conditions are associated to increase in the level of the pulmonary epithelium expression of angiotensin-converting enzyme 2 (ACE-2), which is a recognized receptor of the S protein of the causative agent SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2). Severe cases are manifested by parenchymal lung involvement with a significant inflammatory response and the development of microvascular thrombosis. Several factors have been involved in developing this prothrombotic state, including the inflammatory reaction itself with the participation of proinflammatory cytokines, endothelial dysfunction/endotheliitis, the presence of antiphospholipid antibodies, and possibly the tissue factor (TF) overexpression. ARS-Cov-19 ACE-2 down-regulation has been associated with an increase in angiotensin 2 (AT2). The action of proinflammatory cytokines, the increase in AT2 and the presence of antiphospholipid antibodies are known factors for TF activation and overexpression. It is very likely that the overexpression of TF in COVID-19 may be related to the pathogenesis of the disease, hence the importance of knowing the aspects related to this protein and the therapeutic strategies that can be derived. Different therapeutic strategies are being built to curb the expression of TF as a therapeutic target for various prothrombotic events; therefore, analyzing this treatment strategy for COVID-19-associated coagulopathy is rational. Medications such as celecoxib, cyclosporine or colchicine can impact on COVID-19, in addition to its anti-inflammatory effect, through inhibition of TF.

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