Exocyst complex component 2 is a potential host factor for SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused an epidemic and spread rapidly all over the world. Because the analysis of host factors other than receptors and proteases has not been sufficiently performed, we attempted to identify and characterize host factors essential for SARS-CoV-2 infection using iPS cells and airway organoids (AO). Based on previous CRISPR screening and RNA-seq data, we found that exocyst complex component 2 (EXOC2) is one important host factor for SARS-CoV-2 infection. The intracellular SARS-CoV-2 nucleocapsid (N) expression level was decreased to 3.7% and the virus copy number in cell culture medium was decreased to 1.6% by EXOC2 knockdown. Consistently, immunostaining results showed that N protein-positive cells were significantly decreased by EXOC2 knockdown. We also found that EXOC2 knockdown downregulates SARS-CoV-2 infection by regulating IFNW1 expression. In conclusion, controlling the EXOC2 expression level may prevent SARS-CoV-2 infection and deserves further study.

Dual inhibition of TMPRSS2 and Cathepsin Bprevents SARS-CoV-2 infection in iPS cells.

It has been reported that many receptors and proteases are required for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Although angiotensin-converting enzyme 2 (ACE2) is the most important of these receptors, little is known about the contribution of other genes. In this study, we examined the roles of neuropilin-1, basigin, transmembrane serine proteases (TMPRSSs), and cathepsins (CTSs) in SARS-CoV-2 infection using the CRISPR interference system and ACE2-expressing human induced pluripotent stem (iPS) cells. Double knockdown of TMPRSS2 and cathepsin B (CTSB) reduced the viral load to 0.036% ± 0.021%. Consistently, the combination of the CTPB inhibitor CA-074 methyl ester and the TMPRSS2 inhibitor camostat reduced the viral load to 0.0078% ± 0.0057%. This result was confirmed using four SARS-CoV-2 variants (B.1.3, B.1.1.7, B.1.351, and B.1.1.248). The simultaneous use of these two drugs reduced viral load to less than 0.01% in both female and male iPS cells. These findings suggest that compounds targeting TMPRSS2 and CTSB exhibit highly efficient antiviral effects independent of gender and SARS-CoV-2 variant.

Identification of ligands from natural products as inhibitors of glutathione S-transferases using enzyme immobilized mesoporous magnetic beads with high-performance liquid chromatography plus quadrupole time-of-flight mass spectrometry and molecular docking.

Multidrug resistance is recognized as one of the main reasons leading to the failure of chemotherapy. Studies have shown that glutathione S-transferase inhibitors could be regarded as multidrug resistance reversal agents. Herein, a method of applying enzyme immobilization, molecular docking, and high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was employed to screen glutathione S-transferase inhibitors from natural products. Magnetic mesoporous silica microspheres were synthesized and modified with a poly(dopamine) layer, which has a large quantity of amino, enabling further non-covalent binding with glutathione S-transferase. Moreover, the immobilization conditions, namely, potential of hydrogen, catalase concentration, reaction temperature and reaction time, were optimized. In total, six potential compounds were isolated and identified from Perilla frutescens (L.) Britt leaves and green tea and molecular docking was applied to identify the binding site. Rosmarinic acid, (-)-epigallocatechin-3-O-gallate and (-)-epicatechin-3-gallate showed higher binding affinity than the compounds, and their half maximal inhibitory concentration values were further determined. The results suggested that this proposed method was effective and convenient for identifying glutathione S-transferase inhibitors from natural products.

Rational synthesis of hierarchical magnetic mesoporous silica microspheres with tunable mesochannels for enhanced enzyme immobilization.

Hierarchical magnetic mesoporous silica microspheres (MMSMs) with a core-shell structure have been fabricated through an improved water/oil biphase synthesis strategy. We firstly reported that the mesopore size can be readily tuned from 6.1 to 11.4 nm by the synergistic effect of surfactant concentration and an amphiphilic agent, thus holding a bright future in many possible applications.