Chemical genetics-based development of small molecules targeting hepatitis C virus

Research trends in chemogenetics for neuroscience in recent 14 years: A bibliometric study in CiteSpace

BACKGROUND

Chemogenetics has been widely adopted in Neuroscience. Neuroscience has become a hot research topic for scientists. Therefore, the purpose of this study is to explore the current status and trends in the global application of chemogenetics in neuroscience over the last 14 years via CiteSpace.

METHODS

Publications related to chemogenetics in neuroscience were retrieved from the Science Citation Index-Extended Web of Science from 2008 to 2021. We used CiteSpace to analyze publications, citations, cited journals, countries, institutions, authors, cited authors, cited references, and keywords.

RESULTS

A total of 947 records were retrieved from 2008 to 2021 on February 21, 2022. The number and rate of publications and citations increased significantly. Journal of Neuroscience was the most cited journal, and BRAIN RES BULL ranked first in the centrality of cited journals. The United States of America (USA) had the highest number of publications among the countries. Takashi Minamoto was the most prolific author and Armbruster BN ranked the first among authors cited. The first article in the frequency ranking of the references cited was published by Roth BL. The keyword of "nucleus accumben (NAc)" had the highest frequency. The top 3 keywords with the strongest citation bursts include "transgenic mice," "cancer," and "blood-brain barrier."

CONCLUSION

The period 2008 to 2021 has seen a marked increase in research on chemogenetics in neuroscience. The application of chemogenetics is indispensable for research in the field of neuroscience. This bibliometrics study provides the current situation and trend in chemogenetic methods in neuroscience in recent 14 years, which may help researchers to identify the hot topics and frontiers for future studies in this field.

Repurposing of artesunate, an antimalarial drug, as a potential inhibitor of hepatitis E virus

Hepatitis E virus (HEV) is endemic in several developing countries of Africa and Asia. It mainly causes self-limiting waterborne infections, in either sporadic or outbreak form. Recently, HEV was shown to cause chronic infections in immunosuppressed individuals. Ribavirin and interferon, the current off-label treatment options for hepatitis E, have several side effects. Hence, there is a need for new drugs. We evaluated the antimalarial drug artesunate (ART) against genotype 1 HEV (HEV-1) and HEV-3 using a virus-replicon-based cell culture system. ART exhibited 59% and 43% inhibition of HEV-1 and HEV-3, respectively, at the highest nontoxic concentration. Computational molecular docking analysis showed that ART can bind to the helicase active site (affinity score, -7.4 kcal/mol), indicating its potential to affect ATP hydrolysis activity. An in vitro ATPase activity assay of the helicase indeed showed 24% and 55% inhibition at 19.5 µM (EC50) and 78 µM concentrations of ART, respectively. Since ATP is a substrate of RNA-dependent RNA polymerase (RdRp) as well, we evaluated the effect of ART on the enzymatic activity of the viral polymerase. Interestingly, ART showed 26% and 40% inhibition of the RdRp polymerase activity at 19.5 µM and 78 µM concentrations of ART, respectively. It could be concluded from these findings that ART inhibited replication of both HEV-1 and HEV-3 by directly targeting the activities of the viral enzymes helicase and RdRp. Considering that ART is known to be safe in pregnant women, we think this antimalarial drug deserves further evaluation in animal models.

Evaluation of interactions between the hepatitis C virus NS3/4A and sulfonamidobenzamide based molecules using molecular docking, molecular dynamics simulations and binding free energy calculations

The Hepatitis C Virus (HCV) NS3/4A is an attractive target for the treatment of Hepatitis C infection. Herein, we present an investigation of HCV NS3/4A inhibitors based on a sulfonamidobenzamide scaffold. Inhibitor interactions with HCV NS3/4A were explored by molecular docking, molecular dynamics simulations, and MM/PBSA binding free energy calculations. All of the inhibitors adopt similar molecular docking poses in the catalytic site of the protease that are stabilized by hydrogen bond interactions with G137 and the catalytic S139, which are known to be important for potency and binding stability. The quantitative assessments of binding free energies from MM/PBSA correlate well with the experimental results, with a high coefficient of determination, R2 of 0.92. Binding free energy decomposition analyses elucidate the different contributions of Q41, F43, H57, R109, K136, G137, S138, S139, A156, M485, and Q526 in binding different inhibitors. The importance of these sidechain contributions was further confirmed by computational alanine scanning mutagenesis. In addition, the sidechains of K136 and S139 show crucial but distinct contributions to inhibitor binding with HCV NS3/4A. The structural basis of the potency has been elucidated, demonstrating the importance of the R155 sidechain conformation. This extensive exploration of binding energies and interactions between these compounds and HCV NS3/4A at the atomic level should benefit future antiviral drug design.

Recent advancement in small molecules as HCV inhibitors

Hepatitis C virus (HCV) has caused a considerable threat to human health. To date, no treatments are without side effects. The proteins and RNA associated with HCV have specific functions during the viral life cycle. The vulnerabilities to virus are associated with those proteins or RNA. Thus, targeting these proteins and RNA is an efficient strategy to develop anti-HCV therapeutics. The treatment for HCV-infected patients has been greatly improved after the approval of direct-acting antivirals (DAAs). However, the cost of DAAs is unusually high, which adds to the economic burden on patients with chronic liver diseases. So far, many efforts have been devoted to the development of small molecules as novel HCV inhibitors. Investigations on the inhibitory activities of these small molecules have involved the target identification and the mechanism of action. In this mini-review, these small molecules divided into four kinds were elaborated, which focused on their targets and structural features. Furthermore, we raised the current challenges and promising prospects. This mini-review may facilitate the development of small molecules with improved activities targeting HCV based on the chemical scaffolds of HCV inhibitors.

The Human Replicative Helicase, the CMG Complex, as a Target for Anti-cancer Therapy

DNA helicases unwind or rearrange duplex DNA during replication, recombination and repair. Helicases of many pathogenic organisms such as viruses, bacteria, and protozoa have been studied as potential therapeutic targets to treat infectious diseases, and human DNA helicases as potential targets for anti-cancer therapy. DNA replication machineries perform essential tasks duplicating genome in every cell cycle, and one of the important functions of these machineries are played by DNA helicases. Replicative helicases are usually multi-subunit protein complexes, and the minimal complex active as eukaryotic replicative helicase is composed of 11 subunits, requiring a functional assembly of two subcomplexes and one protein. The hetero-hexameric MCM2-7 helicase is activated by forming a complex with Cdc45 and the hetero-tetrameric GINS complex; the Cdc45-Mcm2-7-GINS (CMG) complex. The CMG complex can be a potential target for a treatment of cancer and the feasibility of this replicative helicase as a therapeutic target has been tested recently. Several different strategies have been implemented and are under active investigations to interfere with helicase activity of the CMG complex. This review focuses on the molecular function of the CMG helicase during DNA replication and its relevance to cancers based on data published in the literature. In addition, current efforts made to identify small molecules inhibiting the CMG helicase to develop anti-cancer therapeutic strategies were summarized, with new perspectives to advance the discovery of the CMG-targeting drugs.