Análisis de los sitios de unión de la ivermectina en la estructura de importinas α humanas

La ivermectina demostró importantes acciones antivirales ante varios virus con genoma de ARN, inclusive contra el SARS-CoV-2. Este fármaco inhibe la actividad del heterodímero importina α/ß1, sin embargo, se desconoce los blancos específicos de interacción de la molécula. Objetivos: analizar in silico los blancos de interacción de la ivermectina en interacción con la estructura de la importina α humana, utilizando la estrategia del acoplamiento molecular. Métodos: se realizaron simulaciones del acoplamiento utilizando un modelo semiflexible y el algoritmo Broyden-Fletcher-Goldfarb-Shanno entre las estructuras de ivermectina y la importina α. Resultados: los datos obtenidos revelan una mayor afinidad de interacción de la ivermectina a la región mayor de unión (armadillo ARM2-ARM4) de las importinas α humanas, con energías de unión favorables de -9,5 a -8,0 kcal.mol-1. Los aminoácidos activos de importancia en las uniones fueron el Triptófano, Asparagina y Arginina, los cuales también son fundamentales para el reconocimiento de secuencias NLS (secuencias de localización nuclear) de las proteínas virales. También se registró afinidades por los dominios H1-ARM5, H2-ARM6 y H2-ARM7, con energía de unión de -7,5 kcal.mol-1. Conclusiones: los hallazgos demuestran que la ivermectina presenta afinidades de unión favorables a la región mayor de unión (ARM2-ARM4) de las importinas a el cual es un sitio importante de unión a proteínas virales.

Ivermectin has demonstrated significant antiviral actions against several RNA-genome viruses, including SARS-CoV-2. This drug inhibits the activity of the α/ß1 importin heterodimer; however, the specific interaction targets of the molecule are unknown yet. Objectives: to analyze in silico the interaction targets of ivermectin interacting with the human α-importin structure using the molecular docking strategy. Methods: simulations of the molecular docking were carried out using a semi-flexible model and the Broyden-Fletcher-Goldfarb- Shanno algorithm between the structures of ivermectin and importin α. Results: data obtained reveal a higher interaction affinity of ivermectin to the major binding region (armadillo ARM2-ARM4) of human importins α, with favorable binding energies of -9,5 to -8,0 kcal.mol-1. The active amino acids of importance in the bindings were Tryptophan, Asparagine and Arginine, which are also critical for the recognition of NLS sequences (nuclear location sequences) of viral proteins. Affinities for H1-ARM5, H2-ARM6 and H2-ARM7 domains were also recorded, with binding energy of -7,5 kcal.mol-1. Conclusions: the findings demonstrate that ivermectin exhibits favorable binding affinities to the major binding region (ARM2-ARM4) of importins a which is an important viral protein binding site.

Relationship between Kapβ2-mediated nuclear translocation of hnRNPA2/B1 and sevoflurane-induced brain neurotoxicity: a cellular experiment / 中华麻醉学杂志

Objective:To evaluate the relationship between Karyopherin β2 (Kapβ2)-mediated nuclear translocation of nuclear inhomogeneous ribonucleoprotein A2/B1 (hnRNPA2/B1) and sevoflurane-induced brain neurotoxicity in a cellular experiment.Methods:The mouse hippocampal neuronal cell line HT22 cells were inoculated in confocal culture dishes and 6-well culture plates at a density of 2×10 5 cells/well and 1×10 6 cells/well and divided into 4 groups( n=12 each) by a random number table method: control group (GFP-C group) carrying green fluorescent protein (GFP) with empty adenovirus transfection, sevoflurane group (GFP-Sev group) carrying GFP with empty adenovirus transfection, control group (GFP-Sev group) transfected with Kapβ2 gene-overexpressing adenovirus, and sevoflurane group (Kapβ2-Sev group) transfected with Kapβ2 gene-overexpressing adenovirus. After 48 h of conventional incubation, empty adenovirus-carrying GFP (GFP-C and GFP-Sev groups) and Kapβ2 gene-overexpressing adenovirus (Kapβ2-C and Kapβ2-Sev groups) were transfected. After 48 h of transfection, the cells were conventionally incubated continuously in GFP-C and Kapβ2-C groups, and the cells were incubated for 3 h with 3% sevoflurane and then were conventionally incubated for 48 h in GFP-Sev and Kapβ2-Sev groups. The expression of Kapβ2, synaptophysin (SYP), postsynaptic density protein 95 (PSD95) and hnRNPA2/B1 nucleoplasmic ratio were measured in cells by Western blot. Immunofluorescence assay was used for hnRNPA2/B1 subcellular localization. Results:Compared with GFP-C group, the expression of SYP and PSD95 was significantly down-regulated, hnRNPA2/B1 nucleoplasmic ratio was decreased, and cytoplasmic hnRNPA2/B1 expression was up-regulated in GFP-Sev group, and Kapβ2 expression was significantly up-regulated in Kapβ2-C group ( P<0.05). Compared with Kapβ2-C group, the expression of SYP and PSD95 was significantly down-regulated, hnRNPA2/B1 nucleoplasmic ratio was decreased, and cytoplasmic hnRNPA2/B1 expression was up-regulated in Kapβ2-Sev group ( P<0.05). Compared with GFP-Sev group, the expression of Kapβ2, SYP and PSD95 was significantly up-regulated, hnRNPA2/B1 nucleoplasmic ratio was increased, and cytoplasmic hnRNPA2/B1 expression was down-regulated in Kapβ2-Sev group ( P<0.05). Conclusions:Kapβ2-mediated hnRNPA2/B1 nuclear translocation may be the endogenous protective mechanism against sevoflurane-induced brain neurotoxicity.

Interacción in silico de las moléculas Agatisflavona, Amentoflavona y Punicalina con la Importina α 1 humana / In silico interaction of Agathisflavone, Amentoflavone and Punicalin molecules with human Importin α1

RESUMEN Varios virus con genoma de ARN en fases iniciales de la infección realizan la translocación de proteínas al interior del núcleo de la célula hospedera mediante la vía de las importinas α1. Este transporte es fundamental para el éxito de la replicación viral y se ha convertido en un blanco para la búsqueda y desarrollo de nuevos antivirales. El objetivo de este estudio fue determinar y caracterizar interacciones entre la Agatisflavona, Amentoflavona, Punicalina con el sitio mayor de unión de las Importinas α1 humanas mediante el análisis in silico del acoplamiento molecular y simulaciones de dinámica molecular. Las pruebas de acoplamiento molecular se realizaron entre estos fitoconstituyentes y la estructura de la importina α1 humana. Las afinidades de interacción fueron detectadas con la Agatisflavona, Amentoflavona y Punicalina (ΔG b = -8,8, -9,1 y -8,8 kcal.mol-1 respectivamente), con afinidades de interacción específicamente a los dominios ARM2-ARM5 (sitio mayor de unión) de las importinas α1. Las simulaciones de dinámica molecular revelaron interacciones significativamente favorables (P<0,001) con los ligandos Agatisflavona y Amentoflavona (ΔG b = -18,60±0,35 y -22,55±2,41 kcal.mol-1) mientras que la Punicalina registró mayores valores de energía de interacción (ΔG b = -5,33±1,72 kcal.mol-1). Los hallazgos obtenidos en este estudio computacional sugieren que las moléculas Agatisflavona y Amentoflavona presentan interacciones favorables con el sitio mayor de unión de las Importinas α1, en comparación a lo registrado con la Punicalina, sin embargo, se recomienda realizar ensayos in vitro a modo de confirmar estas observaciones.

ABSTRACT Several RNA-viruses during early stages of infection perform the translocation of proteins into the nucleus of host cell by the importin α1 pathway. This transport is essential for viral replication success and has become a target to search and development new antivirals. The objective of this study was to determine and characterize interactions between Agathisflavone, Amentoflavone and Punicalin with the major binding site of human importins α1 by in silico analysis of molecular docking and molecular dynamics simulations. Molecular docking tests were performed between these phytoconstituents and the structure of human importin α1. Interaction's affinity was detected with the Agathisflavone, Amentoflavone and Punicalin (ΔG b = -8.8, -9.1 and -8.8 kcal.mol-1 respectively), with binding affinity to ARM 2-ARM 5 domains (major binding site) of importins α1. Molecular dynamics simulations revealed significantly favorable interactions (P<0.001) with the ligands Agatisflavone and Amentoflavone (ΔG b = -18.60 ± 0.35 and -22.55 ± 2.41 kcal.mol-1) meanwhile Punicalin showed higher values of interaction free energy (ΔG b = -5.33 ± 1.72 kcal.mol-1). The findings obtained suggest that Agathisflavone and Amentoflavone could favorably interact to the major binding site of Importins α1 compared to that registered with Punicalin, however, it is recommended to perform in vitro assays to confirm these observations.

The molecular mechanism for nuclear transport and its application / 대한해부학회지

Transportation between the cytoplasm and the nucleoplasm is critical for many physiological and pathophysiological processes including gene expression, signal transduction, and oncogenesis. So, the molecular mechanism for the transportation needs to be studied not only to understand cell physiological processes but also to develop new diagnostic and therapeutic targets. Recent progress in the research of the nuclear transportation (import and export) via nuclear pore complex and four important factors affecting nuclear transport (nucleoporins, Ran, karyopherins, and nuclear localization signals/nuclear export signals) will be discussed. Moreover, the clinical significance of nuclear transport and its application will be reviewed. This review will provide some critical insight for the molecular design of therapeutics which need to be targeted inside the nucleus.

Development of Monoclonal Antibodies Against Human IRF-5 and Their Use in Identifying the Binding of IRF-5 to Nuclear Import Proteins Karyopherin-alpha1 and -beta1

PURPOSE: IRF-5 is a direct transducer of virus-mediated and TLR-mediated signaling pathways for the expression of cytokines and chemokines which form homodimers or heterodimers with IRF-7. However, direct IRF-5-specific monoclonal antibodies (mAbs) are not available at present. These could be used to further evaluate the functions of IRF-5. In this study, we produced and characterized three mouse mAbs to human IRF-5. The binding of IRF-5 to nuclear import proteins was first identified using a mAb. MATERIALS AND METHODS: His-tagged human IRF-5 protein spanning amino acid residues 193- 257 was used as an antigen and three mAbs were produced. The mAbs were tested with ELISA, Western blot analysis (WB), immunofluorescent staining (IF), and immunoprecipitation (IP). In addition, the nuclear import protein which carried phosphorylated IRF-5 was identified using one of these mAbs. RESULTS: MAbs 5IRF8, 5IRF10 and 5IRF24 which reacted with the recombinant His-IRF-5(193-257) protein were produced. All mAbs bound to human IRF-5, but not to IRF-3 or IRF-7. They could be used for WB, IF, and IP studies. The binding of phosphorylated IRF-5 to karyopherin-alpha1 and -beta1 was also identified. CONCLUSION: Human IRF-5-specific mAbs are produced for studying the immunologic roles related to IRF-5. Phosphorylated IRF-5 is transported to the nucleus by binding to nuclear import proteins karyopherin-alpha1 and -beta1.