4-Aryl-5-carbamoyl-3-isoxazolols as competitive antagonists of insect GABA receptors: Synthesis,biological activity,and molecular docking studies

Competitive antagonists (CAs) of ionotropic GABA receptors (GABARs) reportedly exhibit insecticidal activity and have potential for development as novel insecticides for overcoming emerging resistance to traditional GABAR-targeting insecticides. Our previous studies demonstrated that 4,5-disubstituted 3-isoxazolols or 3-isothiazolols are an important class of insect GABAR CAs. In the present study, we synthesized a series of 4-aryl-5-carbamoyl-3-isoxazolols and examined their antagonism of insect GABARs expressed in Xenopus oocytes. Several of these 3-isoxazolols exhibited potent antagonistic activities against housefly and common cutworm GABARs, with IC₅₀ values in the low-micromolar range in both receptors. 4-(3-Amino-4-methylphenyl)-5-carbamoyl-3-isoxazolol (3u) displayed the highest antagonism, with IC₅₀ values of 2.0 and 0.9?μM in housefly and common cutworm GABARs, respectively. Most of the synthesized 3-isoxazolols showed moderate larvicidal activities against common cutworms, with more than 50% mortality at 100?μg/g. These results indicate that 4-monocyclic aryl-5-carbamoyl-3-isoxazolol is a promising scaffold for insect GABAR CA discovery and provide important information for the design and development of GABAR-targeting insecticides with a novel mode of action.     

Structures of single‐layer β‐sheet proteins evolved from β‐hairpin repeats

Free‐standing single‐layer β‐sheets are extremely rare in naturally occurring proteins, even though β‐sheet motifs are ubiquitous. Here we report the crystal structures of three homologous, single‐layer, anti‐parallel β‐sheet proteins, comprised of three or four twisted β‐hairpin repeats. The structures reveal that, in addition to the hydrogen bond network characteristic of β‐sheets, additional hydrophobic interactions mediated by small clusters of residues adjacent to the turns likely play a significant role in the structural stability and compensate for the lack of a compact hydrophobic core. These structures enabled identification of a family of secreted proteins that are broadly distributed in bacteria from the human gut microbiome and are putatively involved in the metabolism of complex carbohydrates. A conserved surface patch, rich in solvent‐exposed tyrosine residues, was identified on the concave surface of the β‐sheet. These new modular single‐layer β‐sheet proteins may serve as a new model system for studying folding and design of β‐rich proteins.     

Lipopolysaccharide upregulates the proliferation,migration, and odontoblastic differentiation of NG2+ cells from human dental pulp in vitro

NG2⁺ cells have been proven to differentiate into odontoblasts in vivo, and their contribution to odontoblasts is significantly increased, especially after tooth injury. However, their characteristics in vitro, especially under an inflammatory environment, are still not fully understood. Therefore, this study aimed to explore their proliferation, migration, and odontoblastic differentiation ability after treatment with lipopolysaccharide (LPS) in vitro. In our study, NG2 ⁺ cells were isolated from the human dental pulp by magnetic‐activated cell sorting, and these isolated cells were proven to be NG2 ⁺ by immunostaining. When compared with human dental pulp cells (hDPCs), the NG2 ⁺ cells showed no significant differences in cell migration with or without LPS incubation, but their proliferative ability was weaker. When treated with LPS, NG2 ⁺ cells expressed elevated levels of pro‐inflammatory cytokines including interleukin‐1β (IL‐1β), IL‐6, IL‐8, and tumor necrosis factor‐α, and among these, the expression of IL‐1β and IL‐6 were higher than that of hDPCs. Their multipotent differentiation potential was confirmed by the induction of odontoblastic and adipogenic differentiation, and LPS increased their odontoblastic differentiation capacity. In the odontoblastic differentiation process, Wnt5a, BMP2, and BMP7 mRNA were increased, while the canonical Wnt‐related genes were decreased. In conclusion, the LPS stimulation promotes the migration, proliferative, and odontoblastic differentiation ability of NG2 ⁺ cells from the human dental pulp in vitro, and bone morphogenetic protein and the noncanonical Wnt pathway may be involved in their odontoblastic differentiation. These results indicated their special roles in tooth injury repair and potential application in pulp regeneration.     

Fitness costs associated with acetyl‐coenzyme A carboxylase mutations endowing herbicide resistance in American sloughgrass (Beckmannia syzigachne Steud.)

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Dynamic responses of picophytoplankton to physicochemical variation in the eastern Indian Ocean

Picophytoplankton were investigated during spring 2015 and 2016 extending from near‐shore coastal waters to oligotrophic open waters in the eastern Indian Ocean (EIO). They were typically composed of Prochlorococcus (Pro), Synechococcus (Syn), and picoeukaryotes (PEuks). Pro dominated most regions of the entire EIO and were approximately 1–2 orders of magnitude more abundant than Syn and PEuks. Under the influence of physicochemical conditions induced by annual variations of circulations and water masses, no coherent abundance and horizontal distributions of picophytoplankton were observed between spring 2015 and 2016. Although previous studies reported the limited effects of nutrients and heavy metals around coastal waters or upwelling zones could constrain Pro growth, Pro abundance showed strong positive correlation with nutrients, indicating the increase in nutrient availability particularly in the oligotrophic EIO could appreciably elevate their abundance. The exceptional appearance of picophytoplankton with high abundance along the equator appeared to be associated with the advection processes supported by the Wyrtki jets. For vertical patterns of picophytoplankton, a simple conceptual model was built based upon physicochemical parameters. However, Pro and PEuks simultaneously formed a subsurface maximum, while Syn generally restricted to the upper waters, significantly correlating with the combined effects of temperature, light, and nutrient availability. The average chlorophyll a concentrations (Chl a) of picophytoplankton accounted for above 49.6% and 44.9% of the total Chl a during both years, respectively, suggesting that picophytoplankton contributed a significant proportion of the phytoplankton community in the whole EIO.     

Diphenyleneiodonium induces ROS-independent p53 expression and apoptosis in human RPE cells

The diphenyleneiodonium (DPI) is widely used as an inhibitor of flavoenzymes, particularly NADPH oxidase. In this study, we investigated the effect of DPI on the apoptosis of human RPE cells. DPI treatment in ARPE-19 cells evoked a dose- and time-dependent growth inhibition, and also induced DNA fragmentation and protein content of the proapoptotic factor Bax. In addition, DPI significantly induced the expression and phosphorylation of p53, which induces proapoptotic genes in response to DNA damage or irreparable cell cycle arrest. ROS have been implicated as a key factor in the activation of p53 by many chemotherapeutic drugs. Recent data on the regulation of intracellular ROS by DPI are controversial. Therefore, we analyzed whether DPI could contribute to the generation of intracellular ROS. Although there was increase in ROS level from cells treated for 24h with DPI, it was not detectable at early time points, required to induce p53 expression. And DPI-induced p53 expression was not affected by the ROS scavenger NAC. We conclude that DPI induces the expression of p53 by ROS-independent mechanism in ARPE-19 cells, and renders cells sensitive to drug-induced apoptosis by induction of p53 expression.     

Molecular basis for substrate discrimination by glycine transporters

Glycine is an inhibitory neurotransmitter in the spinal cord and brain stem, where it acts on strychnine-sensitive glycine receptors, and is also an excitatory neurotransmitter throughout the brain and spinal cord, where it acts on the N-methyl-d-aspartate family of receptors. There are two Na(+)/Cl(-)-dependent glycine transporters, GLYT1 and GLYT2, which control extracellular glycine concentrations and these transporters show differences in substrate selectivity and blocker sensitivity. A bacterial Na(+)-dependent leucine transporter (LeuT(Aa)) has recently been crystallized and its structure determined. When the amino acid residues within the leucine binding site of LeuT(Aa) are aligned with residues of the two glycine transporters there are a number of identical residues and also some key differences. In this report, we demonstrate that the LeuT(Aa) structure represents a good working model of the Na(+)/Cl(-)-dependent neurotransmitters and that differences in substrate selectivity can be attributed to a single difference of a glycine residue in transmembrane domain 6 of GLYT1 for a serine residue at the corresponding position of GLYT2.     

C3d3通过促进脾脏B细胞高表达CXCR4增强hCGβ DNA免疫体液免疫效应

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