Mechanism Of Inhibition Research Articles

Antimicrobial effects and metabolomics analysis of the cell-free supernatant of Limosilactobacillus fermentum

In this study, Listeria monocytogenes and Escherichia coli were selected as reference bacteria, and the inhibitory effects and mechanisms of cell-free supernatants (CFS) of Limosilactobacillus fermentum 733 on its free-living bacteria and biofilm were investigated in depth. The findings demonstrated that L. fermentum 733 CFS displayed notable suppressive effects on L. monocytogenes and E. coli, which were caused by the loss of the cell membranes' structural integrity. This disturbance resulted in the release of intracellular adenosine triphosphate (ATP), alkaline phosphatase (ALP), and reactive oxygen species (ROS). Scanning electron microscopy and laser scanning confocal microscopy showed that L. fermentum 733 CFS disrupted L. monocytogenes and E. coli biofilm structure. L. fermentum 733 CFS inhibited partial population sensing and biofilm-associated gene expression of L. monocytogenes and E. coli, shown by fluorescence quantitative PCR (qPCR). Metabolomics analysis showed that L. fermentum 733 CFS strongly inhibited L. monocytogenes and E. coli by the disruption of both cellular structure and intracellular. These results offer novel perspectives and a theoretical foundation for the prevention of lactic acid bacteria (LAB) infections caused by L. monocytogenes and E. coli.

Investigation into the hydrogen inhibition mechanism of Platycladus orientalis leaf extract as a biodegradation inhibitor for waste aluminum-silicon alloy dust in wet dust collectors

This study investigates the risk of hydrogen explosion caused by waste metal dust encountering water in wet dust collectors. It proposes using renewable plant extracts to suppress hydrogen evolution from aluminum-silicon (Al-Si) alloy dust, aiming to achieve intrinsically safer production. Platycladus orientalis leaf extract (POLE) was prepared using water as a solvent. Hydrogen inhibition experiments, material characterization, and theoretical calculations were conducted to evaluate the effect of POLE on waste Al-Si dust. The inhibition experiments demonstrated that POLE exhibits excellent inhibitory performance. At a POLE concentration of 2.0 g/L, the hydrogen inhibition efficiency reaches 97.71 % after 22 h, with a reaction rate constant of 8.9708 × 10−5, approaching zero. This efficiency remained stable over 5 days. POLE formed a uniform, dense protective film on the Al-Si dust surface, with a contact angle of 99.23°. FTIR spectra revealed absorption peaks corresponding to POLE functional groups and Al-O bonds, indicating that successfully adsorption of POLE through both physical and chemical interactions. Finally, theoretical calculations were performed to further explain the hydrogen inhibition mechanism of POLE, supplementing and confirming the characterization data. This study inhibited hydrogen production from waste dust, offering a new approach to enhancing the hydrogen production rate from recycled Al scraps.

Insight into the corrosion inhibition mechanism of mild steel St1 in 2 M H2SO4 electrolyte by azithromycin

Mild steel is essential in modern industry due to its favorable mechanical properties and economic availability. However, its high susceptibility to corrosion, especially in acidic environments, poses a significant challenge, reducing service life, increasing operating costs, and raising the risk of failures. This study investigates the corrosion inhibition mechanism of mild steel St1 in a 2 M H2SO4 solution at various temperatures using the broad-spectrum antibiotic azithromycin (AZM). Experimental results indicate that AZM presence increases the polarization resistance of mild steel in the acidic solution. AZM acts as a mixed-type inhibitor, influencing the kinetics of both cathodic and anodic processes. The introduction of 200 mM AZM leads to an increase in the polarization resistance of the steel electrode in 2 M H2SO4 by up to 2.4 times. The inhibition mechanism involves forming a protective layer of protonated AZM forms on the negatively charged Fe surface. These protonated forms can also adsorb on cathodic areas, competing with hydronium ions (H3O+) and thereby inhibiting hydrogen evolution processes. The protective effect of AZM diminishes with increasing temperature of the corrosive environment, as confirmed by Monte Carlo simulations showing decreased adsorption energies for AZM and its protonated forms at higher temperatures. An assessment of the protective effect of 200 mM AZM showed that an increase in the temperature of the corrosive environment from 293 to 333 K leads to a decrease in the protective effect by almost 5.6 times. Quantum chemical calculations determined the reactivity of AZM and its protonated forms, identifying the molecular groups involved in the adsorption mechanism.

Binding of Inhibitors to Nuclear Localization Signal Peptide from Venezuelan Equine Encephalitis Virus Capsid Protein Explored with All-Atom Replica Exchange Molecular Dynamics.

Several small molecule inhibitors have been designed to block binding of the Venezuelan equine encephalitis virus (VEEV) nuclear localization signal (NLS) sequence to the importin-α nuclear transport protein. To probe the inhibition mechanism on a molecular level, we used all-atom explicit water replica exchange molecular dynamics to study the binding of two inhibitors, I1 and I2, to the coreNLS peptide, representing the core fragment of the VEEV NLS sequence. Our objective was to evaluate the possibility of masking wherein binding of these inhibitors to the coreNLS occurs prior to its binding to importin-α. We found that the free energy of I1 and I2 binding to the coreNLS is less favorable than that to importin-α. This outcome argues against preemptive inhibitor binding to the coreNLS prior to importin-α. Instead, both inhibitors are expected to compete with the coreNLS peptide for binding to importin-α. The two factors responsible for the low affinities of the inhibitors to the coreNLS peptide are (i) the low cooperativity of binding to the peptide and (ii) the strong hydrophobic effect associated with binding to importin-α. Our results further show that upon binding to the coreNLS peptide, the inhibitors form multiple diverse binding poses. The coreNLS peptide coincubated with I1 and I2 adopts several conformational states, including open and collapsed, which underscores the fluidity of the coreNLS conformational ensemble as a target for inhibitors. Taken together with our prior investigations, this study sheds light on the molecular mechanism by which I1 and I2 ligands inhibit binding of the VEEV capsid protein to importin-α.

In silico Exploration of Inhibition Mechanism of Lianhua Qingwen Formula (LQF) Interaction on SARS-CoV-2 Mpro

In silico Exploration of Inhibition Mechanism of Lianhua Qingwen Formula (LQF) Interaction on SARS-CoV-2 Mpro

Inhibition of efflorescence for fly ash-slag-steel slag based geopolymer: Pore network optimization and free alkali stabilization

The efflorescence problem is always an intractable problem for geopolymer. Silica fume (SF), nano-silica (NS), 5A zeolite (ZL) and nano-silica treated with silane (NST), were used to mitigate the efflorescence of fly ash (FA) - granulated blast furnace slag (GBFS) - steel slag (SS) based geopolymer. The effect of their dosages on the efflorescence was evaluated through accelerated efflorescing, leaching and unconfined compressive strength (UCS) tests. The inhibition mechanisms were explored by XRD, SEM, FTIR and MIP characterization. It revealed that SF and NS presented the most effective mitigating effect on efflorescence, with 9 % of SF and 2 % of NS totally inhibiting efflorescence and improving the compressive strength, and ZL and NST also alleviated the efflorescence at appropriate contents. Optimizing pore network and stabilizing free alkali were found to be the most important aspects for inhibiting efflorescence. The SF and NS worked efficiently in both two ways, which contained a large amount of dissolvable silicate that reacted with the excessive alkali to form C(N)-A-S-H and C-S-H gels. This filled and reduced the pores from 26 nm to less than 10 nm, and stabilized alkali with reduce the free w(Na+) by more than 50.45 %. On the other hand, ZL can solidify free alkali through the ion exchange property and fill pores due to its microaggregate nature, and NST reduced the efflorescence through blocking free alkali migration paths by hydrophobicity of the pores. These findings would guide the selection of appropriate methods to solve the efflorescence problem of geopolymers.

An inhibitory mechanism prevents outdated actions of eye and hand movements

An inhibitory mechanism prevents outdated actions of eye and hand movements

Inhibitory activity and mechanism of thiosemicarbazide derivatives on tyrosinase and their anti-browning activity in fresh apple juice

Exploring tyrosinase inhibitors has been an effective way to find promising anti-browning agents in the food industry. Therefore, a class of thiosemicarbazide derivatives (4a-4m) were synthesized and we investigated the inhibitory mechanism on tyrosinase by fluorescence quenching, copper ion chelating and UV spectra study etc. 2-(2-Chlorobenzyl) hydrazine-1-carbothioamide (4f) (IC50 = 1.21 ± 0.02 μM) is the most active compound of all derivatives, which was defined as a mix-type inhibitor. Additionally, molecular docking and copper ions chelating studies indicated that compound 4f has the ability to inhibit the tyrosinase activity by chelating the copper ions in the active region. Furthermore, compound 4f also exhibited lower cytotoxicity, excellent aqueous solubility and outstanding anti-browning capacity in fresh apple juice. These findings indicated these derivatives could provide more possibility for developing more safer and effective anti-browning agents.

Inhibitory effect and mechanism of violacein on planktonic growth, spore germination, biofilm formation and toxin production of Bacillus cereus and its application in grass carp preservation

Bacillus cereus is a ubiquitous foodborne pathogen commonly found in various foods. Its ability to form spores, biofilms and diarrhoeal and/or emetic toxins further exacerbates the risk of food poisoning. Violacein is a tryptophan derivative with excellent antibacterial activity. However, the knowledge on the antibacterial action of violacein against B. cereus was lacking, and thus this study aimed to investigate the antibacterial activity and mechanism. The antibacterial results demonstrated that minimum inhibitory concentration and minimum bactericidal concentration of violacein were 3.125 mg/L and 12.50 mg/L, respectively. Violacein could effectively inhibit planktonic growth, spore germination and biofilm formation of B. cereus (P < 0.001). Meanwhile, violacein significantly downregulated the expression of toxin genes, including nheA (P < 0.05), nheB (P < 0.001), bceT (P < 0.01), cytK (P < 0.001), hblC (P < 0.001) and hblD (P < 0.001). Results of extracellular alkaline phosphatase, nucleotide and protein leakage assays and scanning and transmission electron microscopy observation tests showed violacein destroyed cell walls and membranes of B. cereus. In addition, 6.25 mg/kg of violacein could significantly inhibit B. cereus in grass carp fillets (P < 0.05). These results demonstrate that violacein has great potential as an effective natural antimicrobial preservative to control food contamination and poisoning events caused by B. cereus.

The antagonistic activity of Streptomyces spiroverticillatus (No. HS1) against of poplar canker pathogen Botryosphaeria dothidea

BackgroundPoplar canker caused by Botryosphaeria dothidea is one of the most severe plant disease of poplars worldwide. In our study, we aimed to investigate the modes of antagonism by fermentation broth supernatant (FBS) of Streptomyces spiroverticillatus HS1 against B. dothidea.ResultsIn vitro, the strain and FBS of S. spiroverticillatus HS1 significantly inhibited mycelial growth and biomass accumulation, and also disrupted the mycelium morphology of B. dothidea. On the 3rd day after treatment, the inhibition rates of colony growth and dry weight were 80.72% and 52.53%, respectively. In addition, FBS treatment damaged the plasma membrane of B. dothidea based on increased electrical conductivity in the culture medium, and malondialdehyde content of B. dothidea mycelia. Notably, the analysis of key enzymes in glycolysis pathway showed that the activity of hexokinase (HK), phosphofructokinase (PFK), and pyruvate kinase (PK), Ca2+Mg2+-ATPase were significantly increased after FBS treatment. But the glucose contents were significantly reduced, and pyruvate contents were significantly increased in B. dothidea after treatment with FBS.ConclusionsThe inhibitory mechanism of S. spiroverticillatus HS1 against B. dothidea was a complex process, which was associated with multiple levels of mycelial growth, cell membrane structure, material and energy metabolism. The FBS of S. spiroverticillatus HS1 could provide an alternative approach to biological control strategies against B. dothidea.

Novel 5-alkenylthiothiazolidinone scaffold discovery as Multi-Chitinases inhibitors to arrest the molting of Asian corn borer

Chitinases are crucial enzymes in insect growth and development processes and have thus become potential targets for the control of insect pests. Rhodanine (5-alkenylthiothiazolidinone) is an important fragment with various biological activities in agriculture. Therefore, 24 novel 5-alkenylthiothiazolidinone derivatives were designed and synthesized by introducing a hydrophobic hydrocarbon chain and a benzylformamide group on the basis of the conserved binding cavity of three chitinases, OfChtI, OfChtII and OfChi-h. These 5-alkenylthiothiazolidinone analogs were found for the first time to have inhibitory effects on OfChtII, except for their ability to inhibit the other two known chitinases, OfChtI and OfChi-h. The inhibitory activities of the target compounds against OfChtI and OfChi-h ranged from 40 % to 95 % at a concentration of 100 μM. In particular, some compounds were also found to have an inhibitory rate of 50 % against OfChtII. Among them, the Ki values of the most potent compound 5e-9 were 5.82, 27.5 and 6.77 μM against OfChtI, OfChtII and OfChi-h, respectively. The inhibition mechanism studies revealed that both π stacking interactions and hydrophobic interactions were vital for the binding of Compound 5e-9 with the three chitinases. A lethal and sublethal bioassay study revealed that Compound 5e-9 could affect the growth and development of Asian corn borers. This work suggested that 5-alkenylthiothiazolidinone could be a novel inhibitor scaffold against multichitinase for the development of insect growth regulators.

Promising organoselenium corrosion inhibitors for C1018-steel in hydrochloric acid environments

BackgroundNovel organoselenium (OSe) corrosion inhibitors, namely 2-(((4-(benzylselanyl)phenyl)imino)methyl)-5-nitrophenol (BSeOH) and its Ni (II) chelate [Ni(BSeO)2(H2O)2] were synthesized in 90 % and 88 % yields, respectively. Their chemical structures were characterized using different spectroscopic tools. MethodsThe corrosion inhibition efficiency was investigated toward C1018-steel in 1.0 M HCl solutions using potentiodynamic polarization, impedance spectroscopy, X-ray photoelectron spectroscopy, density functional theory, and Monte Carlo simulations. Several quantum chemical parameters were calculated using Density Functional Theory at the B3LYP/6–31G* computational model to elucidate the inhibitory activity of the compounds. Significant findingsElectrochemical data showed that [Ni(BSeO)2(H2O)2] has more protection efficiency (96.4 %) compared to its ligand BSeOH (93.4 %) at 15.0 × 10−6 M. In addition, the corrosion current density (icor) decreases (245.96 to 8.96 µAcm−2), the charge transfer resistance (Rct) increases (95.15 to 1926.70 Ω cm2), and the admittance (Y0) decreases (173.87 to 18.07 μΩ−1 sn cm−2) with the inhibitors’ dosage indication the formation of a protective adsorbed layer on the steel surface. Furthermore, the BSeOH and [Ni(BSeO)2(H2O)2] inhibitors were spontaneously adsorbed on the steel surface, adhering to the Langmuir isotherm. Moreover, the electrochemical and theoretical results showed that these inhibitors were effectively adsorbed on the C1018-steel surface as a preventive layer. Collectively, the utilization of OSe agents as corrosion inhibitors is a novel approach that combines several advantageous characteristics, including improved efficiency, unique chemical properties, multiple inhibition mechanisms, and the potential for derivatization. Therefore, OSe inhibitors hold significant promise in the field of corrosion prevention and further studies are highly required to develop a more substantial strategy to fight corrosion by applying OSe compounds.

Effect of adsorption of two green biopolymers on the corrosion of aluminum in 1.0 M NaCl solution: Physicochemical, spectroscopic, surface and quantum chemical exploration

Although aluminum is an extremely versatile material and can be manufactured and used for a wide range of industrial purposes, it has a limited resistance to corrosion. Hence, the efficacy of two linear biopolymers, keratan (Ker) and chitosan (Chi), was explored, for the first time, as ecologically safe metallic corrosion inhibitors (CIs) for Al in 1.0 M NaCl solution at different temperatures. For performing this study, several experimental and theoretical methods were applied. By combining these methods, it was confirmed that the investigated biopolymers were set to be effective inhibitors for Al corrosion in 1.0 M NaCl solution. Using a 500 mg/L dose of CIs, inhibition efficiencies (% IEs) of 92.7 % and 86.4 % were achieved for Ker and Chi, respectively, indicating their strong adsorption on the metal surface. Thermodynamic and kinetic investigations signified that the adsorption was founed to be physical and obeyed the Langmuir isotherm. The kinetics and mechanism of Al corrosion as well as its inhibition by the tested biopolymers were inspected. The results demonstrated that these biopolymers behaved as mixed-type and interface-type inhibitors. To investigate the inhibition mechanism, theoretical quantum chemical methods were also applied. The experimental investigations were validated by theoretical computations.

Fundamental mechanism and potential optimization methods for the overpressure phenomenon of Novec 1230 and 2-BTP

Novec 1230 (C6F12O) and 2-BTP (C3H2BrF3) created higher peak pressures (overpressure phenomenon) than with no agent in the aerosol can test of Federal Aviation Administration. Previous researches ascribed the overpressure to the fuel-like property of 2-BTP and Novec 1230. However, the fundamental cause of the overpressure phenomenon has not been fully clarified, and no solution has been proposed to improve the inhibition effect and reduce the combustion enhancement of 2-BTP and Novec 1230. For accelerating the development process of halon replacement in aircraft cargo bay, this work in-depth studied the fundamental mechanism of the overpressure phenomenon of two agents. Novec 1230 consumes O2 at low loading from the reactions of fluorine-containing groups such as C3F7 with chain branching reactions, and further produces a large amount CO and HF. Different from Novec 1230, 2-BTP does not directly consume O2, however induces a higher concentration of H radical at high loading and further promote the reaction rate of H + O2OH+O to consume large quantities of O2. In addition, the calculated pressure and the sum of the equilibrium gas composition were studied to find that 2-BTP and Novec 1230 greatly increase the total gas content, resulting in much higher pressure rise than Halon 1301. Additionally, the recommended measures of 2-BTP and Novec 1230 to improve the reduce the overpressure were proposed based on their combustion inhibition and enhancement mechanism.

Diverse effects of ferromagnetic-paramagnetic phase transition on the activity and selectivity of ferromagnetic catalysts

Tuning the catalyst’s activity and selectivity is usually achieved by modifying the electronic structure through strategies such as alloying, doping, strain, and ligand modification, but inevitably accompanied by geometric structure changes of catalysts. It is challenging to modify a catalyst’s electronic structure without changing its geometric structure. Recent studies found that the second-order ferromagnetic to paramagnetic (FM-PM) phase transition could promote catalytic performance without altering the geometric structures of active sites, which was also known as the magneto-catalytic effect (MCE). However, the understanding of the MCE is still incomplete. Herein, we conducted systematic density functional theory (DFT) calculations to clarify the complex reaction mechanisms for conversions of nitrogen-containing small molecules on both FM and PM Ni (111) surfaces. Our microkinetic modeling (MKM) results demonstrate that FM-PM phase transition promotes the N2O decomposition activity of FM Ni catalyst but decreases its activity for NO decomposition while showing a negligible influence on the activity of ammonia decomposition. These results indicate the promotion, inhibition, and disappearance mechanisms of MCE on the catalytic activity, which further changes the selectivity of different products. We anticipate the MCE will work as an effective strategy for fine-tuning the activity and selectivity of ferromagnetic catalysts in heterogeneous catalysis, providing an extra basis for rational catalyst design.

Unlocking the potential of LHPP: Inhibiting glioma growth and cell cycle via the MDM2/p53 pathway

The recurrence of glioma after treatment has remained an intractable problem for many years. Recently, numerous studies have explored the pivotal role of the mouse double minute 2 (MDM2)/p53 pathway in cancer treatment. Lysine phosphate phosphohistidine inorganic pyrophosphate phosphatase (LHPP), a newly discovered tumor suppressor, has been confirmed in numerous studies on tumors, but its role in glioma remains poorly understood. Expression matrices in The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases were analyzed using gene set enrichment analysis (GSEA), revealing significant alterations in the p53 pathway among glioma patients with high LHPP expression. The overexpression of LHPP in glioma cells resulted in a reduction in cell proliferation, migration, and invasive ability, as well as an increase in apoptosis and alterations to the cell cycle. The present study has identified a novel inhibitory mechanism of LHPP against glioma, both in vivo and in vitro. The results demonstrate that LHPP exerts anti-glioma effects via the MDM2/p53 pathway. These findings may offer a new perspective for the treatment of glioma in the clinic.

Inhibitory effects of calcium channel blockers nisoldipine and nimodipine on ivacaftor metabolism and their underlying mechanism.

Ivacaftor is the first potentiator of the cystic fibrosis transmembrane conductance regulator (CFTR) protein approved for use alone in the treatment of cystic fibrosis (CF). Ivacaftor is primarily metabolized by CYP3A4 and therefore may interact with drugs that are CYP3A4 substrates, resulting in changes in plasma exposure to ivacaftor. The study determined the levels of ivacaftor and its active metabolite M1 by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). We screened 79 drugs and 19 severely inhibited ivacaftor metabolism, particularly two cardiovascular drugs (nisoldipine and nimodipine). In rat liver microsomes (RLM) and human liver microsomes (HLM), the half-maximal inhibitory concentrations (IC50) of nisoldipine on ivacaftor metabolism were 6.55μM and 9.10μM, respectively, and the inhibitory mechanism of nisoldipine on ivacaftor metabolism was mixed inhibition; the IC50 of nimodipine on ivacaftor metabolism in RLM and HLM were 4.57μM and 7.15μM, respectively, and the inhibitory mechanism of nimodipine on ivacaftor was competitive inhibition. In pharmacokinetic experiments in rats, it was observed that both nisoldipine and nimodipine significantly altered the pharmacokinetic parameters of ivacaftor, such as AUC(0-t) and CLz/F. However, this difference may not be clinically relevant. In conclusion, this paper presented the results of studies investigating the interaction between these drugs and ivacaftor in vitro and in vivo. The objective is to provide a rationale for the safety of ivacaftor in combination with other drugs.

Corrosion inhibitors in H2O2 system slurry for Ru based barrier layer Cu interconnect chemical mechanical polishing and optimization

Ruthenium (Ru) has the advantages of low resistivity, high thermal stability, and good adhesion and wettability, making it an important solution for breaking through the 14 nm process as a new barrier layer material for multilayer copper interconnect. The purpose of copper (Cu) interconnect Ru-based barrier layer chemical mechanical polishing (CMP) is to obtain a highly flat surface, which not only includes the ideal Ru removal rate and selectivity of the Cu/Ru removal rate, but also inhibition of Cu corrosion. In this article, the corrosion inhibition mechanism of environmentally friendly and highly water-soluble inhibitor 5-methylthio-1 H-tetrazole (MTT) on Cu was studied. The inhibitory effect of MTT on Cu was analyzed through static etching rate testing, electrochemical experiments, and surface characterization. A systematic test was conducted on the planarization performance of the optimized polishing slurry. The corrosion inhibition mechanism of MTT on Cu was revealed through quantum chemical calculations and XPS testing. The experimental results show that the corrosion inhibitor MTT can effectively improve the surface quality of Cu. Quantum chemical calculations and experimental results indicate that MTT can be adsorbed on the surface of Cu through both physical and chemical methods, forming a dense passivation film, thereby inhibiting the corrosion of Cu. The optimized ratio of Ru-based barrier layer CMP polishing slurry was 5 wt% SiO2, 0.15 wt% H2O2, 20 mM ethylenediamine (EDA), 5 mM K4Fe(CN)6, and 2000 ppm MTT, resulted in the Cu/Ru removal rate selectivity of 1:1.18 and the Cu/Ru corrosion potential difference of 3 mV. The average correction values for dishing and erosion on the test pattern wafer of the Ru barrier layer were 355 Å and 280 Å, respectively. The results of this study indicate that MTT is an effective copper corrosion inhibitor in alkaline H2O2-based polishing slurry, providing meaningful references for Ru-based barrier layer copper interconnect CMP.

Revealing a hidden conducting state by manipulating the intracellular domains in KV10.1 exposes the coupling between two gating mechanisms.

The KCNH family of potassium channels serves relevant physiological functions in both excitable and non-excitable cells, reflected in the massive consequences of mutations or pharmacological manipulation of their function. This group of channels shares structural homology with other voltage-gated K+ channels, but the mechanisms of gating in this family show significant differences with respect to the canonical electromechanical coupling in these molecules. In particular, the large intracellular domains of KCNH channels play a crucial role in gating that is still only partly understood. Using KCNH1(KV10.1) as a model, we have characterized the behavior of a series of modified channels that could not be explained by the current models. With electrophysiological and biochemical methods combined with mathematical modeling, we show that the uncovering of an open state can explain the behavior of the mutants. This open state, which is not detectable in wild-type channels, appears to lack the rapid flicker block of the conventional open state. Because it is accessed from deep closed states, it elucidates intermediate gating events well ahead of channel opening in the wild type. This allowed us to study gating steps prior to opening, which, for example, explain the mechanism of gating inhibition by Ca2+-Calmodulin and generate a model that describes the characteristic features of KCNH channels gating.

Homoharringtonine promotes non-small-cell lung cancer cell death via modulating HIF-1α/ERβ/E2F1 feedforward loop.

Hypoxia conditions promote the adaptation and progression of non-small-cell lung cancer (NSCLC) via hypoxia-inducible factors (HIF). HIF-1α may regulate estrogen receptor β (ERβ) and promote the progression of NSCLC. The phytochemical homoharringtonine (HHT) exerts strong inhibitory potency on NSCLC, with molecular mechanism under hypoxia being elusive. The effects of HHT on NSCLC growth were determined by cell viability assay, colony formation, flow cytometry, and H460 xenograft models. Western blotting, molecular docking program, site-directed mutagenesis assay, immunohistochemical assay, and immunofluorescence assay were performed to explore the underlying mechanisms of HHT-induced growth inhibition in NSCLC. HIF-1α/ERβ signaling-related E2F1 is highly expressed and contributes to unfavorable survival and tumor growth. The findings in hypoxic cells, HIF-1α overexpressing cells, as well as ERβ- or E2F1-overexpressed and knockdown cells suggest that the HIF-1α/ERβ/E2F1 feedforward loop promotes NSCLC cell growth. HHT suppresses HIF-1α/ERβ/E2F1 signaling via the ubiquitin-proteasome pathway, which is dependent on the inhibition of the protein expression of HIF-1α and ERβ. Molecular docking and site-directed mutagenesis revealed that HHT binds to the GLU305 site of ERβ. HHT inhibits cell proliferation and colony formation and promotes apoptosis in both NSCLC cells and xenograft models. The formation of the HIF-1α/ERβ/E2F1 feedforward loop promotes NSCLC growth and reveals a novel molecular mechanism by which HHT induces cell death in NSCLC.