• MeSH
• Biology MeSH
• Cytology MeSH
• Molecular Biology MeSH

• Conspectus
• Biochemie. Molekulární biologie. Biofyzika
• Učební osnovy. Vyučovací předměty. Učebnice
• NML Fields
• biologie
• NML Publication type
• učebnice vysokých škol

The rapid geographic expansion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the infectious agent of Coronavirus Disease 2019 (COVID-19) pandemic, poses an immediate need for potent drugs. Enveloped viruses infect the host cell by cellular membrane fusion, a crucial mechanism required for virus replication. The SARS-CoV-2 spike glycoprotein, due to its primary interaction with the human angiotensin-converting enzyme 2 (ACE2) cell-surface receptor, is considered a potential target for drug development. In this study, around 5,800 molecules were virtually screened using molecular docking. Five molecules were selected for in vitro experiments from those that reported docking scores lower than -6 kcal/mol. Imatinib, a Bcr-Abl tyrosine kinase inhibitor, showed maximum antiviral activity in Vero cells. We further investigated the interaction of imatinib, a compound under clinical trials for the treatment of COVID-19, with SARS-CoV-2 RBD, using in silico methods. Molecular dynamics simulations verified that imatinib interacts with RBD residues that are critical for ACE2 binding. This study also provides significant molecular insights on potential repurposable small-molecule drugs and chemical scaffolds for the development of novel drugs targeting the SARS-CoV-2 spike RBD.Communicated by Ramaswamy H. Sarma.

• MeSH
• Angiotensin-Converting Enzyme 2 MeSH
• Chlorocebus aethiops MeSH
• COVID-19 * MeSH
• Imatinib Mesylate MeSH
• Humans MeSH
• SARS-CoV-2 * MeSH
• Molecular Docking Simulation MeSH
• Vero Cells MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Angiotensin-converting enzyme 2 (ACE2) was identified as a molecule that mediates the cellular entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Several membrane molecules of the host cell must cooperate in this process. While ACE2 serves in a membrane receptor-mediating interaction with the surface spike (S) glycoprotein of SARS-CoV-2 located on the virus envelope, enzyme A disintegrin and metalloproteinase 17 (ADAM17) regulates ACE2 availability on the membrane and transmembrane protease serine 2 (TMPRSS2) facilitates virus-cell membrane fusion. Interestingly, ACE2, ADAM17 and TMPRSS2 show a daily rhythm of expression in at least some mammalian tissue. The circadian system can also modulate COVID-19 progression via circadian control of the immune system (direct, as well as melatonin-mediated) and blood coagulation. Virus/ACE2 interaction causes ACE2 internalization into the cell, which is associated with suppressed activity of ACE2. As a major role of ACE2 is to form vasodilatory angiotensin 1-7 from angiotensin II (Ang II), suppressed ACE2 levels in the lung can contribute to secondary COVID-19 complications caused by up-regulated, pro-inflammatory vasoconstrictor Ang II. This is supported by the positive association of hypertension and negative COVID-19 prognosis although this relationship is dependent on numerous comorbidities. Hypertension treatment with inhibitors of renin-angiotensin system does not negatively influence prognosis of COVID-19 patients. It seems that tissue susceptibility to SARS-CoV-2 shows negative correlation to ACE2 expression. However, in lungs of infected patient, a high ACE2 expression is associated with better outcome, compared to low ACE2 expression. Manipulation of soluble ACE2 levels is a promising COVID-19 therapeutic strategy.

• MeSH
• Angiotensin-Converting Enzyme 2 metabolism   MeSH
• Time Factors MeSH
• Circadian Rhythm * MeSH
• COVID-19 metabolism   physiopathology   therapy   virology   MeSH
• Hypertension metabolism   physiopathology   MeSH
• Host-Pathogen Interactions MeSH
• Humans MeSH
• Periodicity MeSH
• Prognosis MeSH
• ADAM17 Protein metabolism   MeSH
• Renin-Angiotensin System * MeSH
• SARS-CoV-2 metabolism   pathogenicity   MeSH
• Serine Endopeptidases metabolism   MeSH
• Signal Transduction MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

BACKGROUND: Human Syncytin-1 is a placentally-expressed cell surface glycoprotein of retroviral origin. After interaction with ASCT2, its cellular receptor, Syncytin-1 triggers cell-cell fusion and formation of a multinuclear syncytiotrophoblast layer of the placenta. The ASCT2 receptor is a multi-spanning membrane protein containing a protruding extracellular part called region C, which has been suggested to be a retrovirus docking site. Precise identification of the interaction site between ASCT2 and Syncytin-1 is challenging due to the complex structure of ASCT2 protein and the background of endogenous ASCT2 gene in the mammalian genome. Chicken cells lack the endogenous background and, therefore, can be used to set up a system with surrogate expression of the ASCT2 receptor. RESULTS: We have established a retroviral heterologous chicken system for rapid and reliable assessment of ectopic human ASCT2 protein expression. Our dual-fluorescence system proved successful for large-scale screening of mutant ASCT2 proteins. Using this system, we demonstrated that progressive deletion of region C substantially decreased the amount of ASCT2 protein. In addition, we implemented quantitative assays to determine the interaction of ASCT2 with Syncytin-1 at multiple levels, which included binding of the soluble form of Syncytin-1 to ASCT2 on the cell surface and a luciferase-based assay to evaluate cell-cell fusions that were triggered by Syncytin-1. Finally, we restored the envelope function of Syncytin-1 in a replication-competent retrovirus and assessed the infection of chicken cells expressing human ASCT2 by chimeric Syncytin-1-enveloped virus. The results of the quantitative assays showed that deletion of the protruding region C did not abolish the interaction of ASCT2 with Syncytin-1. CONCLUSIONS: We present here a heterologous chicken system for effective assessment of the expression of transmembrane ASCT2 protein and its interaction with Syncytin-1. The system profits from the absence of endogenous ASCT2 background and implements the quantitative assays to determine the ASCT2-Syncytin-1 interaction at several levels. Using this system, we demonstrated that the protruding region C was essential for ASCT2 protein expression, but surprisingly, not for the interaction with Syncytin-1 glycoprotein.

• MeSH
• Cell Line MeSH
• Fibroblasts virology   MeSH
• Fluorescence MeSH
• Gene Products, env genetics   metabolism   MeSH
• Microscopy, Confocal MeSH
• Chickens MeSH
• Humans MeSH
• Placenta virology   MeSH
• Pregnancy Proteins genetics   metabolism   MeSH
• Pregnancy MeSH
• Amino Acid Transport System ASC genetics   metabolism   MeSH
• Minor Histocompatibility Antigens genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

HIV-1 envelope (Env) N-glycosylation impact virus-cell entry and immune evasion. How each glycan interacts to shape the Env-protein-sugar complex and affects Env function is not well understood. Here, analysis of two Env variants from the same donor, with differing functional characteristics and N-glycosylation-site composition, revealed that changes to key N-glycosylation sites affected the Env structure at distant locations and had a ripple effect on Env-wide glycan processing, virus infectivity, antibody recognition, and virus neutralization. Specifically, the N262 glycan, although not in the CD4-binding site, modulated Env binding to the CD4 receptor, affected Env recognition by several glycan-dependent neutralizing antibodies, and altered site-specific glycosylation heterogeneity, with, for example, N448 displaying limited glycan processing. Molecular-dynamic simulations visualized differences in glycan density and how specific oligosaccharide positions can move to compensate for a glycan loss. This study demonstrates how changes in individual glycans can alter molecular dynamics, processing, and function of the Env-glycan shield.

• Publication type
• Journal Article MeSH

• MeSH
• Allergy and Immunology MeSH
• Immune System MeSH
• Publication type
• Textbook MeSH

• Conspectus
• Patologie. Klinická medicína
• Učební osnovy. Vyučovací předměty. Učebnice
• NML Fields
• alergologie a imunologie

Introduction: Zika Virus (ZIKV) infection is a major public health concern, affecting almost each country in the western hemisphere. A more than 20-fold increase in microcephaly risks is associated to ZIKV infection in pregnancy. A new vaccine is not expected before 2019, and alternative prophylactic and therapeutic approaches are encouraged. We expect that the Resonant Recognition Model, developed by Irena Cosic, might lay on the basis for an alternative approach to handle ZIKV. Objective: We tried to identify the resonant frequencies associated to the ZIKV polyprotein and their use for an automatic taxonomy of different ZIKV strains. We put to test the hypothesis of interaction between ZIKV envelope protein and the AXL receptor, one of the plausible mechanisms proposed for ZIKV associated microcephaly. Results: Four relevant frequencies (fRRM) were found in ZIKV polyprotein consensus spectrum. Corresponding four spectral amplitudes allowed separating African from Asian/American ZIKV isolates (k-means clustering). Peak 3 (fRRM= 0.2754) and Peak 4 (fRRM= 0.334) yielded a finer separation between Asian sequences and those from the current outbreak collected in 2015 (Asian/American). Consensus spectrum for pooled Dengue virus and ZIKV polyprotein sequences suggest that Peak 4 might be a specific hallmark of ZIKV. RRM results support the interaction between ZIKV envelope protein and AXL membrane receptor. The interacting frequency of fRRM= 0.167 seems to be a sub-harmonic of Peak 4. Conclusions: Resonant recognition model provides a plausible view of processes involved in the interactions of ZIKV with the human host, and is suggesting the exchange of electromagnetic radiation at the frequencies of 601.8nm (yellow light) and 1203.6 (near infrared) during ZIKV envelope protein with the AXL receptor in the human fetal tissue. This information might be relevant for alternative approaches to new therapeutic approaches to treat ZIKV-associated damage to newborns.

• Keywords
• electron-ion interaction potential,
• MeSH
• Electromagnetic Phenomena MeSH
• Flavivirus MeSH
• Gene Products, env chemistry   isolation & purification   MeSH
• Zika Virus Infection diagnosis   genetics   MeSH
• Polyproteins MeSH
• Zika Virus * chemistry   genetics   classification   MeSH

Anchoring of heterochromatin to the nuclear envelope appears to be an important process ensuring the spatial organization of the chromatin structure and genome function in eukaryotic nuclei. Proteins of the inner nuclear membrane (INM) mediating these interactions are able to recognize lamina-associated heterochromatin domains (termed LAD) and simultaneously bind either lamin A/C or lamin B1. One of these proteins is the lamin B receptor (LBR) that binds lamin B1 and tethers heterochromatin to the INM in embryonic and undifferentiated cells. It is replaced by lamin A/C with specific lamin A/C binding proteins at the beginning of cell differentiation and in differentiated cells. Our functional experiments in cancer cell lines show that heterochromatin in cancer cells is tethered to the INM by LBR, which is downregulated together with lamin B1 at the onset of cell transition to senescence. The downregulation of these proteins in senescent cells leads to the detachment of centromeric repetitive sequences from INM, their relocation to the nucleoplasm, and distension. In cells, the expression of LBR and LB1 is highly coordinated as evidenced by the reduction of both proteins in LBR shRNA lines. The loss of the constitutive heterochromatin structure containing LADs results in changes in chromatin architecture and genome function and can be the reason for the permanent loss of cell proliferation in senescence.

• Publication type
• Journal Article MeSH
• Review MeSH

The extent of virus transmission among individuals and species is generally determined by the presence of specific membrane-embedded virus receptors required for virus entry. Interaction of the viral envelope glycoprotein (Env) with a specific cellular receptor is the first and crucial step in determining host specificity. Using a well-established retroviral model-avian Rous sarcoma virus (RSV)-we analyzed changes in an RSV variant that had repeatedly been able to infect rodents. By envelope gene (env) sequencing, we identified eight mutations that do not match the already described mutations influencing the host range. Two of these mutations-one at the beginning (D32G) of the surface Env subunit (SU) and the other at the end of the fusion peptide region (L378S)-were found to be of critical importance, ensuring transmission to rodent, human, and chicken cells lacking the appropriate receptor. Furthermore, we carried out assays to examine the virus entry mechanism and concluded that these two mutations cause conformational changes in the Env variant and that these changes lead to an activated, or primed, state of Env (normally induced after Env interaction with the receptor). In summary, our results indicate that retroviral host range extension is caused by spontaneous Env activation, which circumvents the need for original cell receptor. This activation is, in turn, caused by mutations in various env regions.

• MeSH
• Genetic Vectors * genetics   metabolism   MeSH
• Gene Products, env * genetics   metabolism   MeSH
• Rats MeSH
• Chickens MeSH
• Humans MeSH
• Mutation, Missense * MeSH
• Cell Line, Tumor MeSH
• Amino Acid Substitution MeSH
• Transduction, Genetic * MeSH
• Rous sarcoma virus * genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

To find an effective drug for Zika virus, it is important to understand how numerous proteins which are critical for the virus' structure and function interact with their counterparts. One approach to inhibiting the flavivirus is to deter its ability to bind onto glycoproteins; however, the crystal structures of envelope proteins of the ever-evolving viral strains that decipher glycosidic or drug-molecular interactions are not always available. To fill this gap, we are reporting a holistic, simulation-based approach to predict compounds that will inhibit ligand binding onto a structurally unresolved protein, in this case the Zika virus envelope protein (ZVEP), by developing a three-dimensional general structure and analyzing sites at which ligands and small drug-like molecules interact. By examining how glycan molecules and small-molecule probes interact with a freshly resolved ZVEP homology model, we report the susceptibility of ZVEP to inhibition via two small molecules, ZINC33683341 and ZINC49605556-by preferentially binding onto the primary receptor responsible for the virus' virulence. Antiviral activity was confirmed when ZINC33683341 was tested in cell culture. We anticipate the results to be a starting point for drug discovery targeting Zika virus and other emerging pathogens.

• MeSH
• Antiviral Agents chemistry   pharmacology   MeSH
• Chlorocebus aethiops MeSH
• Small Molecule Libraries chemistry   pharmacology   MeSH
• Models, Molecular MeSH
• Computer Simulation MeSH
• Polysaccharides metabolism   MeSH
• Viral Envelope Proteins antagonists & inhibitors   chemistry   MeSH
• Structural Homology, Protein MeSH
• Binding Sites MeSH
• Vero Cells MeSH
• Viral Load drug effects   MeSH
• Zika Virus drug effects   metabolism   MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH