The Telomere-Telomerase System Is Detrimental to Health at High-Altitude

The hypobaric-hypoxia environment at high-altitude (HA, >2500 m) may influence DNA damage due to the production of reactive molecular species and high UV radiation. The telomere system, vital to chromosomal integrity and cellular viability, is prone to oxidative damages contributing to the severity of high-altitude disorders such as high-altitude pulmonary edema (HAPE). However, at the same time, it is suggested to sustain physical performance. This case-control study, comprising 210 HAPE-free (HAPE-f) sojourners, 183 HAPE-patients (HAPE-p) and 200 healthy highland natives (HLs) residing at ~3500 m, investigated telomere length, telomerase activity, and oxidative stress biomarkers. Fluidigm SNP genotyping screened 65 single nucleotide polymorphisms (SNPs) in 11 telomere-maintaining genes. Significance was attained at p ≤ 0.05 after adjusting for confounders and correction for multiple comparisons. Shorter telomere length, decreased telomerase activity and increased oxidative stress were observed in HAPE patients; contrarily, longer telomere length and elevated telomerase activity were observed in healthy HA natives compared to HAPE-f. Four SNPs and three haplotypes are associated with HAPE, whereas eight SNPs and nine haplotypes are associated with HA adaptation. Various gene-gene interactions and correlations between/among clinical parameters and biomarkers suggested the presence of a complex interplay underlining HAPE and HA adaptation physiology. A distinctive contribution of the telomere-telomerase system contributing to HA physiology is evident in this study. A normal telomere system may be advantageous in endurance training.

Insights into the structural and dynamical changes of spike glycoprotein mutations associated with SARS-CoV-2 host receptor binding

Novel Coronavirus or SARS-CoV-2 has received worldwide attention due to the COVID-19 pandemic, which originated in Wuhan, China leading to thousands of deaths to date. The SARS-CoV-2 Spike glycoprotein protein is one of the main focus of COVID-19 related research as it is a structural protein that facilitates its attachment, entry, and infection to the host cells. We have focused our work on mutations in two of the several functional domains in the virus spike glycoprotein, namely, receptor-binding domain (RBD) and heptad repeat 1 (HR1) domain. These domains are majorly responsible for the stability of spike glycoprotein and play a key role in the host cell attachment and infection. In our study, several mutations like R408I, L455Y, F486L, Q493N, Q498Y, N501T of RBD (319-591), and A930V, D936Y of HR1 (912-984) have been studied to examine its role on the spike glycoprotein native structure. Comparisons of MD simulations in the WT and mutants revealed a significant de-stabilization effect of the mutations on RBD and HR1 domains. We have investigated the impact of mapped mutations on the stability of the spike glycoprotein, before binding to the receptor, which may be consequential to its binding properties to the receptor and other ligands.Communicated by Ramaswamy H. Sarma.

Simultaneous Inhibition of SARS-CoV-2 Entry Pathways by Cyclosporine

The COVID-19 pandemic caused by SARS-CoV-2 represents a global public health emergency. The entry of SARS-CoV-2 into host cells requires the activation of its spike protein by host cell proteases. The serine protease, TMPRSS2, and cysteine proteases, Cathepsins B/L, activate spike protein and enable SARS-CoV-2 entry to the host cell through two completely different and independent pathways. Therefore, inhibiting either TMPRSS2 or cathepsin B/L may not sufficiently block the virus entry. We here hypothesized that simultaneous targeting of both the entry pathways would be more efficient to block the virus entry rather than targeting the entry pathways individually. To this end, we utilized the network-based drug repurposing analyses to identify the possible common drugs that can target both the entry pathways. This study, for the first time, reports the molecules like cyclosporine, calcitriol, and estradiol as candidate drugs with the binding ability to the host proteases, TMPRSS2, and cathepsin B/L. Next, we analyzed drug-gene and gene-gene interaction networks using 332 human targets of SARS-CoV-2 proteins. The network results indicate that, out of 332 human proteins, cyclosporine interacts with 216 (65%) proteins. Furthermore, we performed molecular docking and all-atom molecular dynamics (MD) simulations to explore the binding of drug with TMPRSS2 and cathepsin L. The molecular docking and MD simulation results showed strong and stable binding of cyclosporine A (CsA) with TMPRSS2 and CTSL genes. The above results indicate cyclosporine as a potential drug molecule, as apart from interacting with SARS-CoV-2 entry receptors, it also interacts with most of SARS-CoV-2 target host genes; thus it could potentially interfere with functions of SARS-CoV-2 proteins in human cells. We here also suggest that these antiviral drugs alone or in combination can simultaneously target both the entry pathways and thus can be considered as a potential treatment option for COVID-19.

Cordifolioside: potent inhibitor against Mpro of SARS-CoV-2 and immunomodulatory through human TGF-β and TNF-α

Therapeutic options for SARS-CoV-2 are limited merely to the symptoms or repurposed drugs and non-specific interventions to promote the human immune system. In the present study, chromatographic and in silico approaches were implemented to identify bioactive compounds which might play pivotal role as inhibitor for SARS-CoV-2 and human immunomodulator (TGF-β and TNF-α). Tinospora cordifolia (Willd.) Miers was evaluated for phenolic composition and explored for bioactive compounds by high-performance thin layer chromatography (HPTLC). Furthermore, the bioactive compounds such as cordifolioside, berberine, and magnoflorine were appraised as human immunomodulatory and potent inhibitor against Main Protease (M^pro) of SARS-CoV-2 through multiple docking strategies. Cordifolioside formed six stable H-bonds with His41, Ser144, Cys145, His163, His164, and Glu166 of M^pro of SARS-CoV-2, which displayed a significant role in the viral replication/transcription during infection acting towards the common conserved binding cleft among all strains of coronavirus. Overall, the study emphasized that the proposed cordifolioside might use for future investigations, which hold as a promising scaffold for developing anti-COVID-19 drug and reduce human cytokine storm.

A molecular journey to check the conformational dynamics of tau tubulin kinase 2 mutations associated with Alzheimer's disease

Proteins are one of the most vital components of biological functions. Proteins have evolutionarily conserved structures as the shape and folding pattern predominantly determine their function. Considerable research efforts have been made to study the protein folding mechanism. The misfolding of protein intermediates of large groups form polymers with unwanted aggregates that may initiate various diseases. Amongst the diseases caused by misfolding of proteins, Alzheimer's disease (AD) is one of the most prevalent neuro-disorders which has a worldwide impact on human health. The disease is associated with several vital proteins and single amino acid mutations. Tau tubulin kinase 2 (TTBK2) is one of the kinases which is known to phosphorylate tau and tubulin. The literature strongly supports that the mutations-K50E, D163A, R181E, A184E and K143E are associated with multiple important cellular processes of TTBK2. In this study, to understand the molecular basis of the functional effects of the mutations, we have performed structural modeling for TTBK2 and its mutations, using computational prediction algorithms and Molecular Dynamics (MD) simulations. The MD simulations highlighted the impact of the mutations on the Wild Type (WT) by the conformational dynamics, Free Energy Landscape (FEL) and internal molecular motions, indicating the structural de-stabilization which may lead to the disruption of its biological functions. The destabilizing effect of TTBK2 upon mutations provided valuable information about individuals carrying this mutant which could be used as a diagnostic marker in AD.

Screening Malaria-box compounds to identify potential inhibitors against SARS-CoV-2 Mpro, using molecular docking and dynamics simulation studies

Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) Main protease (M^pro) is one of the vital drug targets amongst all the coronaviruses, as the protein is indispensable for virus replication. The study aimed to identify promising lead molecules against M^pro enzyme through virtual screening of Malaria Venture (MMV) Malaria Box (MB) comprising of 400 experimentally proven compounds. The binding affinities were studied using virtual screening based molecular docking, which revealed five molecules having the highest affinity scores compared to the reference molecules. Utilizing the established 3D structure of M^pro the binding affinity conformations of the docked complexes were studied by Molecular Dynamics (MD) simulations. The MD simulation trajectories were analysed to monitor protein deviation, relative fluctuation, atomic gyration, compactness covariance, residue-residue map and free energy landscapes. Based on the present study outcome, we propose three Malaria_box (MB) compounds, namely, MB_241, MB_250 and MB_266 to be the best lead compounds against M^pro activity. The compounds may be evaluated for their inhibitory activities using experimental techniques.

Structural and functional alterations of nitric oxide synthase 3 due to missense variants associate with high-altitude pulmonary edema through dynamic study

The human endothelial nitric oxide synthase (NOS3) is 28 Kbp at 7q36.1 and encodes protein comprising of 1280 amino acids. Being a major source of nitric oxide, the enzyme is crucial to the vascular homeostasis and thereby to be an important pharmaceutical target. We hence have been investigating this molecule in a high-altitude disorder namely, high-altitude pulmonary edema (HAPE). We performed a genome-wide association study (GWAS) in a case-control design of sojourners that included healthy controls and HAPE patients (n = 200) each. Four NOS3 missense SNPs i.e. rs1799983 (E298D), rs3918232 (V827M), rs3918201 (R885M) and rs3918234 (Q982L), were associated significantly with HAPE (P-value < 0.05). Furthermore, extensive in silico analyses were performed to predict the detrimental effect of the four variant types and their three most relevant co-factors namely, heme, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) that are accountable for amendment of protein stability leading to structural de-construction. Subsequently, we validated the findings in a larger sample size of the two study groups. HAPE patients had a higher frequency of the four variants and significantly decreased levels of circulating nitric oxide (NO) (P-value < 0.001). The in silico and human subjects findings complement each other. This study explored the impact of HAPE-associated NOS3 variants with its protein structure stability and holds promise to be current and future drug targets.Communicated by Ramaswamy H. Sarma.

Inhibitor design against JNK1 through e-pharmacophore modeling docking and molecular dynamics simulations

c-Jun-NH2 terminal kinases (JNKs) come under a class of serine/threonine protein kinases and are encoded by three genes, namely JNK1, JNK2 and JNK3. Human JNK1 is a cytosolic kinase belonging to mitogen-activated protein kinase (MAPK) family, which plays a major role in intracrinal signal transduction cascade mechanism. Overexpressed human JNK1, a key kinase interacts with other kinases involved in the etiology of many cancers, such as skin cancer, liver cancer, breast cancer, brain tumors, leukemia, multiple myeloma and lymphoma. Thus, to unveil a novel human JNK1 antagonist, receptor-based pharmacophore modeling was performed with the available eighteen cocrystal structures of JNK1 in the protein data bank. Eighteen e-pharmacophores were generated from the 18 cocrystal structures. Four common e-pharmacophores were developed from the 18 e-pharmacophores, which were used as three-dimensional (3D) query for shape-based similarity screening against more than one million small molecules to generate a JNK1 ligand library. Rigid receptor docking (RRD) performed using GLIDE v6.3 for the 1683 compounds from in-house library and 18 cocrystal ligands with human JNK1 from lower stringency to higher stringency revealed 17 leads. Further to derive the best leads, dock complexes obtained from RRD were studied further with quantum-polarized ligand docking (QPLD), induced fit docking (IFD) and molecular mechanics/generalized Born surface area (MM-GBSA). Four leads have showed lesser binding free energy and better binding affinity towards JNK1 compared to 18 cocrystal ligands. Additionally, JNK1-lead1 complex interaction stability was reasserted using 50 ns MD simulations run and also compared with the best resolute cocrystal structure using Desmond v3.8. Thus, the results obtained from RRD, QPLD, IFD and MD simulations indicated that lead1 might be used as a potent antagonist toward human JNK1 in cancer therapeutics.

E-pharmacophore-based virtual screening to identify GSK-3β inhibitors

Glycogen synthase kinase-3β (GSK-3β) is a serine/threonine kinase which has attracted significant attention during recent years in drug design studies. The deregulation of GSK-3β increased the loss of hippocampal neurons by triggering apoptosis-mediating production of neurofibrillary tangles and alleviates memory deficits in Alzheimer's disease (AD). Given its role in the formation of neurofibrillary tangles leading to AD, it has been a major therapeutic target for intervention in AD, hence was targeted in the present study. Twenty crystal structures were refined to generate pharmacophore models based on energy involvement in binding co-crystal ligands. Four common e-pharmacophore models were optimized from the 20 pharmacophore models. Shape-based screening of four e-pharmacophore models against nine established small molecule databases using Phase v3.9 had resulted in 1800 compounds having similar pharmacophore features. Rigid receptor docking (RRD) was performed for 1800 compounds and 20 co-crystal ligands with GSK-3β to generate dock complexes. Interactions of the best scoring lead obtained through RRD were further studied with quantum polarized ligand docking (QPLD), induced fit docking (IFD) and molecular mechanics/generalized Born surface area. Comparing the obtained leads to 20 co-crystal ligands resulted in 18 leads among them, lead1 had the lowest docking score, lower binding free energy and better binding orientation toward GSK-3β. The 50 ns MD simulations run confirmed the stable nature of GSK-3β-lead1 docking complex. The results from RRD, QPLD, IFD and MD simulations confirmed that lead1 might be used as a potent antagonist for GSK-3β.