Receptor Binding Sites Research Articles

Isolation, characterization and pharmacological potentials of methanol extract of Cassia fistula leaves: Evidenced from mice model along with molecular docking analysis

The purpose of the current investigation was to conduct a detailed analysis of the chemical components and medicinal properties of the methanolic crude extract derived from the leaves of Cassia fistula. This analysis was carried out using both experimental (in vivo) and computational (in silico) methods. Eleven chemicals were chromatographically isolated using GC-MS/MS, which utilizes a library of NIST and Wiley 2020 versions. FTIR analysis of the extract was performed to identify the functional group of the compounds. The glucose-lowering capacity, analgesic, and anti-diarrheal activities of methanolic crude extract were analyzed utilizing a well-known oral glucose tolerance test, tail immersion method, writhing assay, and castor oil-induced diarrheal mice methods, respectively. After 60 min, 120 min, and 180 min of loading the drugs, a significant reduction of blood glucose levels was examined (p < 0.05) in all the extracts of this plant (200 mg/kg, 400 mg/kg and 600 mg/kg) utilized in this research at a time-dependent manner. Similarly, all the crude extracts showed significant (p < 0.05) effects against pain centrally and peripherally compared to the standard drug morphine (2 mg/kg bw) and diclofenac sodium (50 mg/kg bw). Moreover, the methanol extract (400 mg/kg bw) manifested anti-diarrheal efficacy by inhibiting 72.0 % of the diarrheal episode in mice compared to the standard drug loperamide (inhibition = 80.0%). The results of the computational investigations corroborated existing in-vivo findings. Greater or close to equivalent binding affinity to the active binding sites of kappa opioid receptor, glucose transporter 3 (GLUT 3), and cyclooxygenase 2 was indicative of the potential anti-diarrheal, hypoglycemic, and analgesic characteristics of the isolated compounds (COX-2). Moreover, anticancer and antimicrobial potentiality was also found impressive through evaluation of binding affinity with epidermal growth factor receptor (EGFR) and dihydrofolate reductase (DHFR) receptors. Results from this study indicated that C. fistula might be a beneficial natural resource for treating diarrhea, hyperglycemia, and pain. However, additional research is required to conduct a comprehensive phytochemical screening and establish precise action mechanisms of the crude extract or the plant-derived compounds.

Cardiac GR Mediates the Diurnal Rhythm in Ventricular Arrhythmia Susceptibility.

Ventricular arrhythmias (VAs) demonstrate a prominent day-night rhythm, commonly presenting in the morning. Transcriptional rhythms in cardiac ion channels accompany this phenomenon, but their role in the morning vulnerability to VAs and the underlying mechanisms are not understood. We investigated the recruitment of transcription factors that underpins transcriptional rhythms in ion channels and assessed whether this mechanism was pertinent to the heart's intrinsic diurnal susceptibility to VA. Assay for transposase-accessible chromatin with sequencing performed in mouse ventricular myocyte nuclei at the beginning of the animals' inactive (ZT0) and active (ZT12) periods revealed differentially accessible chromatin sites annotating to rhythmically transcribed ion channels and distinct transcription factor binding motifs in these regions. Notably, motif enrichment for the glucocorticoid receptor (GR; transcriptional effector of corticosteroid signaling) in open chromatin profiles at ZT12 was observed, in line with the well-recognized ZT12 peak in circulating corticosteroids. Molecular, electrophysiological, and in silico biophysically-detailed modeling approaches demonstrated GR-mediated transcriptional control of ion channels (including Scn5a underlying the cardiac Na+ current, Kcnh2 underlying the rapid delayed rectifier K+ current, and Gja1 responsible for electrical coupling) and their contribution to the day-night rhythm in the vulnerability to VA. Strikingly, both pharmacological block of GR and cardiomyocyte-specific genetic knockout of GR blunted or abolished ion channel expression rhythms and abolished the ZT12 susceptibility to pacing-induced VA in isolated hearts. Our study registers a day-night rhythm in chromatin accessibility that accompanies diurnal cycles in ventricular myocytes. Our approaches directly implicate the cardiac GR in the myocyte excitability rhythm and mechanistically link the ZT12 surge in glucocorticoids to intrinsic VA propensity at this time.

Functional dissection of the spike glycoprotein S1 subunit and identification of cellular cofactors for regulation of swine acute diarrhea syndrome coronavirus entry.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a novel porcine enteric coronavirus, and the broad interspecies infection of SADS-CoV poses a potential threat to human health. This study provides experimental evidence to dissect the roles of distinct domains within the SADS-CoV spike S1 subunit in cellular entry. Specifically, we expressed the S1 and its subdomains, S1A and S1B. Cell binding and invasion inhibition assays revealed a preference for the S1B subdomain in binding to the receptors on the cell surface, and this unknown receptor is not utilized by the porcine epidemic diarrhea virus. Nanoparticle display demonstrated hemagglutination of erythrocytes from pigs, humans, and mice, linking the S1A subdomain to the binding of sialic acid (Sia) involved in virus attachment. We successfully rescued GFP-labeled SADS-CoV (rSADS-GFP) from a recombinant cDNA clone to track viral infection. Antisera raised against S1, S1A, or S1B contained highly potent neutralizing antibodies, with anti-S1B showing better efficiency in neutralizing rSADS-GFP infection compared to anti-S1A. Furthermore, depletion of heparan sulfate (HS) by heparinase treatment or pre-incubation of rSADS-GFP with HS or constituent monosaccharides could inhibit SADS-CoV entry. Finally, we demonstrated that active furin cleavage of S glycoprotein and the presence of type II transmembrane serine protease (TMPRSS2) are essential for SADS-CoV infection. These combined observations suggest that the wide cell tropism of SADS-CoV may be related to the distribution of Sia or HS on the cell surface, whereas the S1B contains the main protein receptor binding site. Specific host proteases also play important roles in facilitating SADS-CoV entry.IMPORTANCESwine acute diarrhea syndrome coronavirus (SADS-CoV) is a novel pathogen infecting piglet, and its unique genetic evolution characteristics and broad species tropism suggest the potential for cross-species transmission. The virus enters cells through its spike (S) glycoprotein. In this study, we identify the receptor binding domain on the C-terminal part of the S1 subunit (S1B) of SADS-CoV, whereas the sugar-binding domain located at the S1 N-terminal part of S1 (S1A). Sialic acid, heparan sulfate, and specific host proteases play essential roles in viral attachment and entry. The dissection of SADS-CoV S1 subunit's functional domains and identification of cellular entry cofactors will help to explore the receptors used by SADS-CoV, which may contribute to exploring the mechanisms behind cross-species transmission and host tropism.

5-chloro-3-(2-(2,4-dinitrophenyl) hydrazono)indolin-2-one: synthesis, characterization, biochemical and computational screening against SARS-CoV-2

Chemical prototypes with broad-spectrum antiviral activity are important toward developing new therapies that can act on both existing and emerging viruses. Binding of the SARS-CoV-2 spike protein to the host angiotensin-converting enzyme 2 (ACE2) receptor is required for cellular entry of SARS-CoV-2. Toward identifying new chemical leads that can disrupt this interaction, including in the presence of SARS-CoV-2 adaptive mutations found in variants like omicron that can circumvent vaccine, immune, and therapeutic antibody responses, we synthesized 5-chloro-3-(2-(2,4-dinitrophenyl)hydrazono)indolin-2-one (H2L) from the condensation reaction of 5-chloroisatin and 2,4-dinitrophenylhydrazine in good yield. H2L was characterised by elemental and spectral (IR, electronic, Mass) analyses. The NMR spectrum of H2L indicated a keto–enol tautomerism, with the keto form being more abundant in solution. H2L was found to selectively interfere with binding of the SARS-CoV-2 spike receptor-binding domain (RBD) to the host angiotensin-converting enzyme 2 receptor with a 50% inhibitory concentration (IC50) of 0.26 μM, compared to an unrelated PD-1/PD-L1 ligand–receptor-binding pair with an IC50 of 2.06 μM in vitro (Selectivity index = 7.9). Molecular docking studies revealed that the synthesized ligand preferentially binds within the ACE2 receptor-binding site in a region distinct from where spike mutations in SARS-CoV-2 variants occur. Consistent with these models, H2L was able to disrupt ACE2 interactions with the RBDs from beta, delta, lambda, and omicron variants with similar activities. These studies indicate that H2L-derived compounds are potential inhibitors of multiple SARS-CoV-2 variants, including those capable of circumventing vaccine and immune responses.

MDCK-Adaptive Mutation of A169S Changes Glycosylation Pattern of Hemagglutinin and Enhances MDCK-Based H7N9 Vaccine Virus Production without Loss of Antigenicity and Immunogenicity.

The adaptation of egg-derived H7N9 candidate vaccine virus (CVV) in the mammalian cell line is an approach to developing a high-growth virus strain for the mass production of vaccine manufacturing. The adaptive mutations that occur in hemagglutinin (HA) are critical to the activity and potency of the vaccine virus. Previously, we identified a new mutation of A169S in the HA protein of an MDCK-adapted H7N9 vaccine virus (A/Anhui/2013, RG268); however, whether and how this mutation affects vaccine potency remain to be investigated. In this study, we serially passaged RG268 in MDCK cells and found that the HA titer and the TCID50 of the passaged virus RG268-M5 were 4-fold (HA units/50 μL) and 3.5-fold (log10 TCID50/mL) higher than those of the original CVV. By inspecting tandem MS spectra, we identified a new glycosylation site at N167 near the receptor binding site of the HA protein of RG268-M5. Flow cytometry results revealed that RG268-M5 could efficiently infect MDCK cells and initiate viral protein replication as well as that of RG268. Though the new glycosylation site is in the antigenic epitope of viral HA protein, the HI assay result indicated that the antigenicity of RG268-M5 was similar to RG268. Additionally, immunizing mice with RG268-M5 mixed aluminum hydroxide could induce potent antibody responses against the homologous and heterologous H7N9 viruses in vitro whereas the titers were comparable with those from the RG268 group. These results provide in-depth structural information regarding the effects of site-specific glycosylation on virus properties, which have implications for novel avian influenza vaccine development.

Genetic characterization of influenza A(H1N1)pdm09 virus in 2023 in Huzhou, China

IntroductionSince its identification in April 2009, influenza A(H1N1)pdm09 virus has continued to cause significant outbreaks of respiratory tract infections, including pandemics in humans. In the course of its evolution, the virus has acquired many mutations that cause increased disease severity. Regular molecular surveillance of the virus is essential to mark the evolutionary changes that may cause a shift in viral behavior. MethodsTwenty-five (H1N1)pdm09 isolates from Huzhou, China, in 2023 were randomly selected for whole-genome sequencing along with analysis of nucleotide and amino acid sequence identity, average genetic distance, antigen variation sites, receptor binding sites, pathogenicity, potential glycosylation sites, and drug resistance gene sites. ResultsThe 25 (H1N1)pdm09 strains and representative 2023–2024 northern hemisphere vaccine strain A/Wisconsin/67/2022 showed nucleotide and amino acid similarity of 98.41 %–99.22 % and 98.41 %–99.36 %, respectively. This virus belongs to the 6B1A.5a.2a evolutionary lineage. There were 19 amino acid variations in hemagglutinin (HA) protein. Substitutions S137P and R142K occurred in the epitope Ca2 cluster. A total of 13 amino acids were mutated in neuraminidase (NA) protein, and 9 key protease active sites and amino acid sites related to NA inhibitor (NAI) resistance were not mutated. Five amino acid sites of matrix-2 (M2) protein associated with drug resistance were not replaced, but amino acid 31 of M2 protein was shown to be N in the 2023 pandemic strain (H1N1)pdm09 and vaccine strain A/Wisconsin/67/2022. There were seven and eight potential glycosylation sites for HA protein and NA protein, respectively. Compared with the vaccine strains, there were no new or missing potential glycosylation sites in the 25 (H1N1)pdm09 influenza virus isolates. No multiple continuous alkaline amino acids were found in the HA cleavage site of the 25 isolates. ConclusionsThe recommended vaccine strain A/Wisconsin/67/2022 has good prevention potential against the current circulating influenza (H1N1)pdm09. At present, NAIs have good therapeutic and preventive effects against (H1N1)pdm09 circulating in Huzhou, China, but the virus is naturally resistant to amantadines. At present, the (H1N1)pdm09 strain circulating in Huzhou, China, is characterized by low pathogenicity. However, regular molecular surveillance of (H1N1)pdm09 is important to monitor the behavior of the virus in terms of increases in virulence, drug resistance, and emergence of novel strains.

In-silico studies and docking of n-substituted isoindoline-1, 3-dioine analogues as anti-proliferative agents

Recently,isoindoline-1,3-dione compounds based folpet, phosmet, captonand thalidomide were developed because they have a comparable degree of anti-proliferative efficacy owing to their diverse mechanisms such as HDAC inhibitors, tryptase inhibitors, inhibits the mode of tnf-α, and angiogenesis inhibitors. It was investigated how the phthalimide pharmacophore interacted with molecules such tnf-α, HDAC, VEGF, EGF, and Tyrosine Kinase Angiogenesis. In order to assess the inhibitory activity against enzyme assay, a series of phthalimidepharmacophores with various substituent’s (Schiff's base) at the N-phenyl ring were submitted to protein-ligand docking investigations using the lib-dock method in the current work. All of the compounds' chemical structures were designed using Cambridge software, ChemBioOffice Ultra 12.0, and their molecular characteristics were determined using the online molecular modelling tool Molinspiration. Utilizing the Discovery Studio Client version 4.1, ADMETlab 2.0, and Lazar 1.4.2 softwares, ADME, Toxicity, and Molecular Docking investigations using the lib-dock method were carried out to evaluate the binding mode and interactions of synthetic hits at the binding site of receptors. Docking studies demonstrated that these sorts of ligands interacted mostly with TNF-α, HDAC, VEGF, EGF, Tyrosine kinase, and angiogenesis reports, among others, by forming hydrogen bonds and interacting hydrophobically with the domain. Our docking results indicate that compounds A1, A10, A11, A22, A26, and A28 demonstrated the greatest binding affinity with the corresponding proteins based on the predicted binding energy. These computer simulations have shown that phthalimide compounds with N-phenyl rings replaced can effectively suppress enzymatic assay.

Influenza A virus hemagglutinin: from classical fusion inhibitors to proteolysis targeting chimera-based strategies in antiviral drug discovery

The influenza virus glycoprotein hemagglutinin (HA) participates in critical steps of the attachment of viral particles to the host cell membrane receptor and membrane fusion. Due to its crucial involvement in the initial phases of influenza A infections, HA emerges as a promising target in the search of novel drug-like candidates. Given its pivotal role in the early stages of influenza A infections, intense drug discovery efforts have been undertaken to target HA in the past decades. Drug discovery studies mainly rely on preventing the recognition of sialic acid units by the receptor binding site in the globular head (GH) domain, or the conformational rearrangement required for the fusion of viral and cell membranes. In this work, the aim is to summarize the progress made in HA-targeted development of small molecule fusion inhibitors. To this end, attention will primarily be focused on the analysis of the X-ray crystallographic structures of HA bound to fusion inhibitors. Furthermore, this study also aims to highlight the efforts made in exploiting the structural information in conjunction with molecular modeling techniques to discern the mechanism of action of the fusion inhibitors and to assist the design and interpretation of structure-activity relationships of novel lead compounds will be highlighted. The final section will be dedicated to elucidating novel and promising antiviral strategies proceeding from the transformation of known small molecule antivirals in proteolysis targeting chimera (PROTAC)-based targeted protein degradation. This knowledge will be valuable to assist the exploitation of classical and novel antiviral structure-based strategies, together with a deeper understanding of the mechanism of action and minimization of the impact of drug resistance.

Synthesis, Characterization, Molecular Docking Studies and Biological Evaluation of Thiazole Schiff Base Analogs

In this work, potentially safe few Schiff base compounds containing a thiazole moiety were synthesized and characterized. Three thiazole derivatives (2a-c) were successfully synthesized through a two-step reaction involving substituted benzaldehyde, thiosemicarbazide and 1,3-dichloroacetone. The elucidation of the synthesized compounds was accomplished by using spectral studies. Antimicrobial activities demonstrated that some compounds exhibited moderate effectiveness against microbes, compared to the standard antibiotic’s ceftriaxone and amphotericin B, using the disc diffusion technique. In the DPPH free radical scavenging assay, all compounds displayed promising antioxidant effectiveness. Moreover, the molecular docking studies showed that thiazole Schiff base analogs effectively bind to potential receptor binding sites.

Unlocking E‐arylidene Steroid Derivatives as Promising α‐Glucosidase Inhibitors

AbstractType 2 diabetes is common and involves α‐glucosidase inhibition to regulate glucose. We synthesized twenty E‐arylidene steroids with hydroxy and methoxy groups on the aromatic ring. Compounds 3 a, 5 a, 5 b, and 5 d showed notable inhibition, with IC50 values ranging from 1.84±0.28 to 9.25±2.53 μM. Key features for bioactivity include ortho methoxy and α‐hydroxy. Various inhibition mechanisms were observed. In silico studies elucidate the possible binding modes of E‐arylidene steroids, confirming their enzymatic mechanisms of non/un‐competitive inhibitors. Allosteric site 2 emerges as a potential binding site for compounds 3 a, 5 a, and 5 b. Compound 5 d holds promise as a potent α‐glucosidase inhibitor compared to acarbose at the orthosteric receptor binding site.

Identification and functional characterization of putative ligand binding domain(s) of JlpA protein of Campylobacter jejuni

Among the major Surface Exposed Colonization Proteins (SECPs) of Campylobacter jejuni (C. jejuni), Jejuni lipoprotein A (JlpA) plays a crucial role in host cell adhesion specifically by binding to the N-terminal domain of the human heat shock protein 90α (Hsp90α-NTD). Although the JlpA binding to Hsp90α activates NF-κB and p38 MAP kinase pathways, the underlying mechanism of JlpA association with the cellular receptor remains unclear. To this end, we predicted two potential receptor binding sites within the C-terminal domain of JlpA: one spanning from amino acid residues Q332-A354 and the other from S258-T295; however, the latter exhibited weaker binding. To assess the functional attributes of these predicted sequences, we generated two JlpA mutants (JlpAΔ1: S258-T295; JlpAΔ2: Q332-A354) and assessed the Hsp90α-binding affinity–kinetics by in vitro and ex vivo experiments. Our findings confirmed that the residues Q332-A354 are of greater importance in host cell adhesion with a measurable impact on cellular responses. Further, thermal denaturation by circular dichroism (CD) confirmed that the reduced binding affinity of the JlpAΔ2 to Hsp90α is not associated with protein folding or stability. Together, this study provides a possible framework for determining the molecular function of designing rational inhibitors efficiently targeting JlpA.

Screening for new ligands of the MB327-PAM-1 binding site of the nicotinic acetylcholine receptor

Intoxications with organophosphorus compounds (OPCs) effect a severe impairment of cholinergic neurotransmission that, as a result of overstimulation may lead to desensitization of nicotinic acetylcholine receptors (nAChRs) and finally to death due to respiratory paralysis. So far, therapeutics, that are capable to address and revert desensitized neuromuscular nAChRs into their resting, i.e. functional state are still missing. Still, among a class of compounds termed bispyridinium salts, which are characterized by the presence of two pyridinium subunits, constituents have been identified, that can counteract organophosphate poisoning by resensitizing desensitized nAChRs. According to comprehensive modeling studies this effect is mediated by an allosteric binding site at the nAChR termed MB327-PAM-1 site. For MB327, the most prominent representative of the bispyridinium salts and all other analogues studied so far, the affinity for the aforementioned binding site and the intrinsic activity measured in ex vivo and in in vivo experiments are distinctly too low, to meet the criteria to be fulfilled for therapeutic use. Hence, in order to identify new compounds with higher affinities for the MB327-PAM-1 binding site, as a basic requirement for an enhanced potency, two compound libraries, the ChemDiv library with 60 constituents and the Tocriscreen Plus library with 1280 members have been screened for hit compounds addressing the MB327-PAM-1 binding site, utilizing the [2H6]MB327 MS Binding Assay recently developed by us. This led to the identification of a set of 10 chemically diverse compounds, all of which exhibit an IC50 value of ≤ 10 µM (in the [2H6]MB327 MS Binding Assay), which had been defined as selection criteria. The three most affine ligands, which besides a quinazoline scaffold share similarities with regard to the substitution pattern and the nature of the substituents, are UNC0638, UNC0642 and UNC0646. With binding affinities expressed as pKi values of 6.01 ± 0.10, 5.97 ± 0.05 and 6.23 ± 0.02, respectively, these compounds exceed the binding affinity of MB327 by more than one log unit. This renders them promising starting points for the development of drugs for the treatment of organophosphorus poisoning by addressing the MB327-PAM-1 binding site of the nAChR.

One-Health Challenge in H9N2 Avian Influenza: Novel Human-Avian Reassortment Virus in Guangdong Province, China

China is one of the highest producers of poultry meat output in the world, with a large scale of chicken rearing. Statistically analyzed H9N2-subtype avian influenza viruses (AIVs) have become the dominant subtype in China’s live poultry market, with the highest detection rate. Although H9N2 AIV is of low pathogenicity and tends not to cause serious disease and high mortality in poultry, it poses a great challenge to the domestic poultry farming industry by causing a decrease in appetite, a decline in egg production, and deaths caused by mixed infections with another pathogenic microorganism. Moreover, novel influenza viruses (H7N9 and H3N8) infecting humans have emerged in China, and the H9N2 AIV provides all or part of the internal genes to the new recombinant viruses, posing a potential threat to public health and safety and human health. In this research, six H9N2 AIVs were isolated from feces or oropharyngeal swabs collected from live poultry markets and duck farms in Zhanjiang. After epidemiological investigations, phylogenetic analyses, and molecular characterization, we found that the ZJ81 strain was a chicken–human–mink recombinant virus, the ML3 strain was a chicken-human recombinant virus, and all six virus strains of the virus had a bias for the human receptor-binding site and a mutation that could cause an increase in virulence in mice. Therefore, surveillance and control of H9N2 AIV should be strengthened to provide data support for cross-species transmission of H9N2 AIV.

Resistance and fitness costs of the Helicoverpa armigera after selection with the tetraniliprole newly developed diamide insecticide

The cotton bollworm (Helicoverpa armigera) (Lepidoptera: Noctuidae) is a highly destructive insect pest that feeds on more than 200 plants including cotton. Diamide insecticides are typically preferred to combat H. armigera. However, many reports of resistance to diamide insecticides such as chlorantraniliprole have been reported. Tetraniliprole is a novel diamide insecticide, but little is known about its resistance risk in H. armigera. After ten generations of treating H. armigera with tetraniliprole, neither the G4946 nor I4775 mutations were detected and no resistance to tetraniliprole was observed. The realized heritability (h2) was 0.094 after ten generations of selection with tetraniliprole, suggesting a low risk of resistance in H. armigera. Additionally, we found that the LD50 of tetraniliprole (4.01 μg/g) was lower than the LD50 of chlorantraniliprole (5.79 μg/g) in the susceptible strain. Molecular docking analysis also found a difference between the ryanodine receptor (RyR) binding sites of tetraniliprole and chlorantraniliprole, the tetraniliprole free binding energy to RyR was −6.9 kcal/mol, which was smaller than for chlorantraniliprole (−6.4 kcal/mol). Our study reveals that there is a low resistance risk to tetraniliprole in H. armigera, thus suggesting that tetraniliprole can be used as a substitute for other insecticides for this pest control.

Mechanistic insights into inhibition of CCL2-guided leukocyte recruitment by oxyresveratrol and its derivatives

Inflammatory responses are the outcomes of coordinated interactions amongst chemokines and their exclusive non-negotiable counterparts such as glycosaminoglycans and GPCRs. CCL2 in conjunction with other immune molecules positively regulates the migration, infiltration, and recruitment of macrophages to the site of inflammation, hence is a promising target from pharmaceutical perspective. Stilbenes such as resveratrol and its derivatives are well documented for their anti-inflammatory responses. The current study presents a structure-based screening and unravels the molecular recognition patterns of stilbene derivatives against CCL2 chemokine to identify their potential to interact and inhibit the proinflammatory activity of CCL2. Structure based in silico screening of aglycosidic stilbenes followed by fluorescence, NMR and in vitro chemotaxis experiments established that oxyresveratrol (ORS), a symmetrical hydroxylated stilbene, prominently binds CCL2 and inhibits macrophage migration. Further, extensive computational analysis reveals the atom level details of molecular recognition events on ORS and its two derivatives ORS10/ORS16, whereby ORS16 demonstrated as a superior CCL2 binding counterpart. Indeed, NMR and computational analysis suggested that ORS interacts through the receptor binding site of CCL2 to attenuate the leukocyte migration. In brief, the current study provides a basis for designing potential inhibitors opting ORS, and more precisely ORS16 as a primary architecture for targeting CCL2-mediated inflammatory proceedings.

Pilot Study on the Efficacy and Safety of Long-Term Oral Imepitoin Treatment for Control of (Thunder)Storm-Associated Noise Phobia/Noise Aversion in Dogs Using an Individualized-Dose Titration Approach.

Imepitoin is a low-affinity partial agonist for benzodiazepine binding sites of gamma-aminobutyric acid receptors with anxiolytic effects. It has been shown to reduce anxiety during noise-related events in dogs when given at 30 mg/kg PO BID, although this dose was associated with ataxia and increased appetite in some cases. The objective of this study was to assess its safety and efficacy for storm anxiety when started at 10 mg/kg PO BID and titrated to effect up to 30 mg/kg PO BID during storm season. Significant decreases in anxiety scores were seen in weekly surveys and storm logs (SLs) at 10, 20 and 30 mg/kg PO BID. Serious adverse events (AEs) were not reported in any subject. Ataxia was the most commonly reported non-serious AE (14/33), followed by increased hunger (13/33). The frequency of AEs was higher in the 20 mg/kg PO BID group than in the 10 mg/kg group PO BID. No clinically significant changes were seen in lab work pre- and post-study. In conclusion, Imepitoin given during storm season at doses ranging from 10 to 30 mg/kg PO BID reduced clinical signs of fear and anxiety during storms for the dogs in this study. These findings support the use of an individually titrated dose.

Evolution of human H3N2 influenza virus receptor specificity has substantially expanded the receptor-binding domain site

Hemagglutinins (HAs) from human influenza viruses descend from avian progenitors that bind α2-3-linked sialosides and must adapt to glycans with α2-6-linked sialic acids on human airway cells to transmit within the human population. Since their introduction during the 1968 pandemic, H3N2 viruses have evolved over the past five decades to preferentially recognize human α2-6-sialoside receptors that are elongated through addition of poly-LacNAc. We show that more recent H3N2 viruses now make increasingly complex interactions with elongated receptors while continuously selecting for strains maintaining this phenotype. This change in receptor engagement is accompanied by an extension of the traditional receptor-binding site to include residues in key antigenic sites on the surface of HA trimers. These results help explain the propensity for selection of antigenic variants, leading to vaccine mismatching, when H3N2 viruses are propagated in chicken eggs or cells that do not contain such receptors.

Nucleosome profiling at AR binding sites (ARBS) to provide a prognostic tool for metastatic castration-resistant prostate cancer (mCRPC).

42 Background: Prostate cancer is the second leading cause of cancer death for men in the U.S., and metastatic castration-resistant prostate cancer (mCRPC) is the most advanced form. In previous work, we have reported prognostic significance of PTEN-PI3K-AKT pathway and DNA damage response aberrations detected in cell-free DNA (cfDNA) of mCRPC. Here we utilized nucleosome profiling pattern at androgen receptor (AR) binding sites to further investigate AR signaling pathway dysregulation of mCRPC. Methods: Using the next-generation sequencing PredicineScore liquid biopsy assay (low-pass whole genome sequencing, LP-WGS), we profiled cfDNA fragment coverage centered around AR binding sites (ARBS). For 118 mCRPC patient samples, we quantified sample-level ARBS nucleosome profiling abnormality score (ARBS score) by comparing its centric fragment coverage with normal plasma background using standard Z-score. ARBS score was correlated with clinical outcomes including PSA response rate (PSA RR), progression-free survival and overall survival (OS). Results: By comparing ARBS nucleosome profiling and normal plasma background, we found that mCRPC plasma samples had significant ARBS nucleosome depletion, reflective of transcription factor binding and persistent AR signaling. Notably, ARBS nucleosome depletion was prostate cancer specific, and did not occur in other examined cancer types. ARBS score was highly correlated with tumor fraction (R=0.82), indicating that high tumor fraction mCRPC sample had higher AR binding. Importantly, we found that high ARBS score (&gt;2) in pre-treatment samples (n=86) was associated with significantly shorter OS and lower PSA RR compared with low ARBS (≤2) group for patients receiving AR pathway inhibitor (ARPI) or taxane chemotherapy (13.4 vs. 19.4 months, p=7.3×10-3, 45.7% vs. 77.5%, p=5.2×10-3). By integrating genome-wide DNA methylation profiling, we further found that ARBS was hypo-methylated in mCRPC patients, and identified a strong negative correlation between DNA methylation beta value and ARBS score (R=-0.83). Conclusions: ARBS nucleosome profiling abnormality inferred from LP-WGS can serve as a key prognostic tool for mCRPC patients. Patients with high ARBS score had worse clinical outcomes, highlighting the potential clinical utility of cfDNA fragmentomics analysis for mCRPC patient stratification. Integration of mutation, copy number variation and fragmentomics profiling of ARBS may further enhance our understanding of molecular aberrations and treatment outcomes in mCRPC.

Binding and unbinding of potent melatonin receptor ligands: Mechanistic simulations and experimental evidence.

The labeled ligand commonly employed in competition binding studies for melatonin receptor ligands, 2-[125I]iodomelatonin, showed slow dissociation with different half-lives at the two receptor subtypes. This may affect the operational measures of affinity constants, which at short incubation times could not be obtained in equilibrium conditions, and structure-activity relationships, as the Ki values of tested ligands could depend on either interaction at the binding site or the dissociation path. To address these issues, the kinetic and saturation binding parameters of 2-[125I]iodomelatonin as well as the competition constants for a series of representative ligands were measured at a short (2 h) and a long (20 h) incubation time. Concurrently, we simulated by molecular modeling the dissociation path of 2-iodomelatonin from MT1 and MT2 receptors and investigated the role of interactions at the binding site on the stereoselectivity observed for the enantiomers of the subtype-selective ligand UCM1014. We found that equilibrium conditions for 2-[125I]iodomelatonin binding can be reached only with long incubation times, particularly for the MT2 receptor subtype, for which a time of 20 h approximates this condition. On the other hand, measured Ki values for a set of ligands including agonists, antagonists, nonselective, and subtype-selective compounds were not significantly affected by the length of incubation, suggesting that structure-activity relationships based on data collected at shorter time reflect different interactions at the binding site. Molecular modeling simulations evidenced that the slower dissociation of 2-iodomelatonin from the MT2 receptor can be related to the restricted mobility of a gatekeeper tyrosine along a lipophilic path from the binding site to the membrane bilayer. The enantiomers of the potent, MT2-selective agonist UCM1014 were separately synthesized and tested. Molecular dynamics simulations of the receptor-ligand complexes provided an explanation for their stereoselectivity as due to the preference shown by the eutomer at the binding site for the most abundant axial conformation adopted by the ligand in solution. These results suggest that, despite the slow-binding kinetics occurring for the labeled ligand, affinity measures at shorter incubation times give robust results consistent with known structure-activity relationships and with interactions taken at the receptor binding site.

Computational Design of a Truncated Javan Spitting Cobra (Naja sputatrix) Venom Cardiotoxin Analogue as a Promising Insulinotropic Agent

Treatment options for diabetes may vary widely, however, around 50% of all diabetic patients do not reach the minimum glycemic target. Therefore, drugs that are able to lower glucose levels through unconventional targets are still needed for the treatment of type 2 diabetes. This study aimed to investigate the activity of cardiotoxins from N. sputatrix towards Kv channels as potential targets for glucose level reduction. Molecular docking analysis was conducted using the ClusPro web server, and the resulting protein-ligand interactions were visualized using BioVia Discovery Studio and LigPlus v.4.5.3. The stability of the docking structures was further examined through molecular dynamics simulations. The CTX-1, CTX-3, CTX-4, CTX-5, and CTX-KJC3 sequences from N. sputatrix were aligned and modeled, focusing on the 62-81 amino acid residues. The models of CTX-3, CTX-4, and CTX-5 demonstrated interactions with the binding site of the KcsA receptor. Additionally, substituting the Val74 residue in the CTX62-81 fragment with Lys74 resulted in reduced binding energy and mitigated the cytotoxic effects of CTX, while maintaining its insulinotropic activity