Fabrication of Host-Guest Complexes between Adamantane-Functionalized 1,3,4-Oxadiazoles and ß-Cyclodextrin with Improved Control Efficiency against Intractable Plant Bacterial Diseases.

Supramolecular chemistry provides huge potentials and opportunities in agricultural pest management. In an attempt to develop highly bioactive, eco-friendly, and biocompatible supramolecular complexes for managing intractable plant bacterial diseases, herein, a type of interesting adamantane-functionalized 1,3,4-oxadiazole was rationally prepared to facilitate the formation of supramolecular complexes via ß-cyclodextrin-adamantane host-guest interactions. Initial antibacterial screening revealed that most of these adamantane-decorated 1,3,4-oxadiazoles were obviously bioactive against three typically destructive phytopathogens. The lowest EC50 values could reach 0.936 (III18), 0.889 (III18), and 2.10 (III19) µg/mL against the corresponding Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and Pseudomonas syringae pv. actinidiae (Psa). Next, the representative supramolecular binary complex III18@ß-CD (binding mode 1:1) was successfully fabricated and characterized by 1H nuclear magnetic resonance (NMR), isothermal titration calorimetry (ITC), high-resolution mass spectrometry (HRMS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Eventually, correlative water solubility and foliar surface wettability were significantly improved after the formation of host-guest assemblies. In vivo antibacterial evaluation found that the achieved supramolecular complex could distinctly alleviate the disease symptoms and promote the control efficiencies against rice bacterial blight (from 34.6-35.7% (III18) to 40.3-43.6% (III18@ß-CD)) and kiwi canker diseases (from 41.0-42.3% (III18) to 53.9-68.0% (III18@ß-CD)) at 200 µg/mL (active ingredient). The current study can provide a feasible platform and insight for constructing biocompatible supramolecular assemblies for managing destructive bacterial infections in agriculture.

A role for the phosphatidylinositol 3-kinase--protein kinase C zeta--Sp1 pathway in the 1,25-dihydroxyvitamin D3 induction of the 25-hydroxyvitamin D3 24-hydroxylase gene in human kidney cells.

The molecular mechanisms that underlie non-genomic induction of the 25-hydroxyvitamin D3 24-hydroxylase (CYP24) gene promoter by the steroid hormone, 1,25-Dihydroxyvitamin D3 (1,25D), are poorly understood. Although we have previously identified a functional inverted GC-box in the early promoter at -113/-105 bp, it is not known whether this site is important for 1,25D induction of the promoter. Using transfected human embryonic kidney (HEK) 293T cells, we now report the functional characterisation of the GC-box and that 1,25D induction of the promoter requires PI3-kinase, PKCzeta and Sp1 but not Sp3. The data show that 1,25D rapidly stimulates PI3-kinase activity which is required for the activation of PKCzeta and the phosphorylation of Sp1. The effects of the PI3-kinase inhibitor, LY294002, and a dominant negative PKCzeta mutant on 1,25D induction of wild-type and a GC-box mutated CYP24 promoter constructs are consistent with the Sp1 site being the target of both kinases. However, these kinases are not required for basal expression of the CYP24 promoter. The data establish a novel non-genomic mechanism which couples 1,25D to the induction of CYP24 gene transcription via the PI3-kinase--PKCzeta--Sp1 pathway acting through the GC-box.

Basal and parathyroid hormone induced expression of the human 25-hydroxyvitamin D 1alpha-hydroxylase gene promoter in kidney AOK-B50 cells: role of Sp1, Ets and CCAAT box protein binding sites.

The regulation of the gene for renal 25-hydroxyvitamin D 1alpha- hydroxylase (1alpha(OH)ase; CYP27B1) by parathyroid hormone (PTH) under hypocalcemic conditions is fundamentally important for the maintenance of calcium and phosphate homeostasis. The molecular mechanism that underlies this hormonal response is of current interest and has been investigated in the present study by transfection analysis of the human 1alpha(OH)ase promoter in kidney AOK-B50 cells. We have shown that the first 305 bp of promoter can be induced by hormone in transient transfection assays and also within a chromatin environment when stably integrated. Mutagenesis of possible transcription factor binding sites within this promoter length has shown that three sites clustered within the region from -66 to -135 contribute to basal expression. A likely Sp1 and a CCAAT box site are particularly important for basal expression although these sites are not likely to functionally cooperate in a major way. Mutagenesis of the CCAAT box site consistently reduced PTH induction although mutagenesis of the Sp1, Ets and other possible binding sites in the 305 bp of promoter has no significant effect on the level of PTH induction. Other experiments showed that PTH induction but not basal expression was sensitive to the protein kinase inhibitor H89. We have therefore identified for the first time the sites in the 1alpha(OH)ase promoter responsible for basal expression and provide evidence for the role of a CCAAT box binding protein in a PTH mechanism of induction that involves an H89 sensitive step.