Guanylate-binding protein 1 inhibits inflammatory factors produced by H5N1 virus through Its GTPase activity.

The combination of inflammatory factors resulting from an influenza A virus infection is one of the main causes of death in host animals. Studies have shown that guinea pig guanosine monophosphate binding protein 1 (guanylate-binding protein 1, gGBP1) can downregulate cytokine production induced by the influenza virus. Therefore, exploring the innate immune defense mechanism of GBP1 in the process of H5N1 influenza virus infection has important implications for understanding the pathogenic mechanism, disease prevention, and the control of influenza A virus infections. We found that, in addition to inhibiting the early replication of influenza virus, gGBP1 also inhibited the production of CCL2 and CXCL10 cytokines induced by the influenza virus as well as the proliferation of mononuclear macrophages induced by these cytokines. These findings further confirmed that gGBP1 inhibited the production of cytokines through its GTPase activity and cell proliferation through its C-terminal α-helix structure. This study revealed the effect of gGBP1 on the production of cellular inflammatory factors during influenza virus infection and determined the key amino acid residues that assist in the inhibitory processes mediated by gGBP1.

4'-OH as the Action Site of Lipids and MRP1 for Enhanced Transdermal Delivery of Flavonoids.

To date, the transdermal delivery study mainly focused on the drug delivery systems' design and efficacy evaluation. Few studies reported the structure-affinity relationship of the drug with the skin, further revealing the action sites of the drugs for enhanced permeation. Flavonoids attained a considerable interest in transdermal administration. The aim is to develop a systematic approach to evaluate the substructures that were favorable for flavonoid delivery into the skin and understand how these action sites interacted with lipids and bound to multidrug resistance protein 1 (MRP1) for enhanced transdermal delivery. First, we investigated the permeation properties of various flavonoids on the porcine skin or rat skin. We found that 4'-OH (hydroxyl group on the carbon 4' position) rather than 7-OH on the flavonoids was the key group for flavonoid permeation and retention, while 4'-OCH3 and -CH2═CH2-CH-(CH3)2 were unfavorable for drug delivery. 4'-OH could decrease flavonoids' lipophilicity to an appropriate log P and polarizability for better transdermal drug delivery. In the stratum corneum, flavonoids used 4'-OH as a hand to specifically grab the C═O group of the ceramide NS (Cer), which increased the miscibility of flavonoids and Cer and then disturbed the lipid arrangement of Cer, thereby facilitating their penetration. Subsequently, we constructed overexpressed MRP1 HaCaT/MRP1 cells by permanent transfection of human MRP1 cDNA in wild HaCaT cells. In the dermis, we observed that 4'-OH, 7-OH, and 6-OCH3 substructures were involved in H-bond formation within MRP1, which increased the flavonoid affinity with MRP1 and flavonoid efflux transport. Moreover, the expression of MRP1 was significantly enhanced after the treatment of flavonoids on the rat skin. Collectively, 4'-OH served as the action site for increased lipid disruption and enhanced affinity for MRP1, which facilitate the transdermal delivery of flavonoids, providing valuable guidelines for molecular modification and drug design of flavonoids.

Study of Finite Element Simulation on the Mechano-Bactericidal Mechanism of Hierarchical Nanostructure Arrays.

Biomimetic nanostructures with bactericidal performance have become the research focus in constructing sterilization surfaces, but the mechano-bactericidal mechanism is still not fully understood, especially for the hierarchical nanostructure arrays with different heights. Herein, the interaction between Escherichia coli cells and nanostructure arrays was simulated by finite element, and the initial rupture points, i.e., critical action sites, of bacterial cells and the effects of nanostructure geometries on the cell rupture speed were analyzed based on the mechano-response of Escherichia coli cells on flat (identical heights) and hierarchical nanostructure arrays. The critical action sites of bacterial cells on nanostructure arrays are all at the three-phase junction zone of cell-liquid-nanostructure, but they are slightly shifted by the height difference ΔH of nanostructures on hierarchical nanopillar (NP)/nanosheet (NS) arrays, where the NP is higher than the NS. When ΔH < 20 nm, the site nears the NS corners, and when ΔH ≥ 20 nm, the site is consistent with that of the NP/NP array, i.e., the site locates at the three-phase junction zone of cell-liquid-high NP. In addition, except for decreasing the NP diameter, the NS thickness/width, or properly increasing the nanostructure spacing, the cell rupture can be accelerated via increasing the ΔH of nanostructures. ΔH = 40 nm is distinguished as the boundary for the effect of nanostructure ΔH on the cell rupture speed. When ΔH < 40 nm, the cell rupture speed rapidly increases as the ΔH increases; when ΔH ≥ 40 nm, the cell rupture speed reaches the maximum value and remains stable. This study provides a new strategy on how to design high-efficiency bactericidal surfaces.

Inhibition of O-acetylserine (thiol) lyase as a promising new mechanism of action for herbicides.

Enzymes of the sulfur assimilation pathway of plants have been identified as potential targets for herbicide development, given their crucial role in synthesizing amino acids, coenzymes, and various sulfated compounds. In this pathway, O-acetylserine (thiol) lyase (OAS-TL; EC 2.5.1.47) catalyzes the synthesis of L-cysteine through the incorporation of sulfate into O-acetylserine (OAS). This study used an in silico approach to select seven inhibitors for OAS-TL. The in silico experiments revealed that S-benzyl-L-cysteine (SBC) had a better docking score (-7.0 kcal mol-1) than the substrate OAS (-6.6 kcal mol-1), indicating its suitable interaction with the active site of the enzyme. In vitro experiments showed that SBC is a non-competitive inhibitor of OAS-TL from Arabidopsis thaliana expressed heterologously in Escherichia coli, with a Kic of 4.29 mM and a Kiu of 5.12 mM. When added to the nutrient solution, SBC inhibited the growth of maize and morning glory weed plants due to the reduction of L-cysteine synthesis. Remarkably, morning glory was more sensitive than maize. As proof of its mechanism of action, L-cysteine supplementation to the nutrient solution mitigated the inhibitory effect of SBC on the growth of morning glory. Taken together, our data suggest that reduced L-cysteine synthesis is the primary cause of growth inhibition in maize and morning glory plants exposed to SBC. Furthermore, our findings indicate that inhibiting OAS-TL could potentially be a novel approach for herbicidal action.