In this report, we synthesized a series of TO conjugates containing different amino side chains and investigated their binding to telomeric G-quadruplex DNA (G4) using several biophysical methods ...including fluorometric titration and thermal denaturation monitored by fluorescence and circular dichroism. The composition of side chains strongly affects the binding of these molecules to G-quadruplex DNA. Incorporation of amino side chains increases the binding affinity of TO toward G4 but has a minimal effect on its selectivity for G4 over duplex DNA. The plausible binding modes are a synergistic effect of end-stacking and groove interactions as indicated by docking studies. Inhibition of human telomerase activity by TO derivatives was determined in vitro by the TRAP assay. Several derivatives can selectively inhibit the activity of telomerase over DNA polymerase at low concentrations. More significantly, TO-spermine conjugate (16) exhibits a remarkable effect on telomerase inhibition in the submicromolar range, which is comparable to the inhibition effect of a well-known G4 ligand, BRACO-19. Our results here provide guidance of utilizing TO derivatives as a viable scaffold to design novel G4 ligands, G4 probes, and potent telomerase inhibitors.
Thiazole – spermine conjugate (16) inhibits human telomerase activity at submicromolar concentrations. Display omitted
•A series of thiazole orange (TO) derivatives were successfully prepared.•Incorporation of amino side chains increases the binding affinity of TO with G4.•Amino side chains do not enhance the selectivity of TO for G4 over duplex DNA.•TO derivatives bind to G-quadruplex DNA via end stacking and groove interaction.•TO – spermine conjugate (16) is a potent telomerase inhibitor.
Abstract
Four types of cooling plates with serpent channel structures are established to study the cooling effect of rectangular lithium-ion power battery under different cooling plates. Then, the ...number of serpent bends is analyzed, whether the fillet and pipe wall thickness is set on the cooling performance of the liquid cooling plate. According to the analysis results, a new liquid flow structure form of liquid cooling plate is designed. Numerical simulation results show that the newly designed cooling plate is integrated with the front flow of water and the internal liquid side flow, achieving a cooling effect with the maximum temperature is 309.55K and a pressure drop of 6032.1pa, which has the most effective cooling performance. Under the requirement of controlling reasonable temperature and low-pressure drop, a liquid cooling plate with better performance can be designed by innovatively setting the direction of the water inlet and outlet and the water channel’s internal flow. The above results will provide some ideas for the design of a lithium-ion battery liquid cooling plate.
Guanine-rich telomeric DNA at the end of chromosomes can form a unique DNA tertiary structure - G-quadruplex, which is known to inhibit the binding of telomerase to telomeric regions in cancer cells ...and thus regulate unrestricted cancer cell growth. Hence, G-quadruplex DNA has recently become a promising target in oncology. The formation of G-quadruplex structures is greatly facilitated by G-quadruplex binding ligands such as Thiazole orange (TO). Compared with other G-quadruplex binding ligands, TO has an intriguing tunable fluorescence property. Upon binding to DNA, the fluorescence of TO can increase up to 1000-fold, making it an attractive probe for studying ligand-DNA interactions. However, the poor binding affinity and minimal binding selectivity towards different DNA conformations greatly limit its applications. My research focuses on developing G-quadruplex binding ligands using TO as a scaffold. In the first part of this work, we investigated the feasibility of increasing the TO binding affinity and selectivity toward G-quadruplex DNA by introducing side chains to the molecule. TO derivatives containing various side chains were successfully synthesized and characterized. Biophysical and biochemical studies with duplex and G-quadruplex DNA showed that tethering side chains to TO is an effective approach to tune its ability of binding to duplex or G-quadruplex DNA. Possible binding modes of the effective derivatives were studied using AutoDock. Their inhibition of telomerase activities was studied using the TRAP assay. The cytotoxicity of these derivatives toward three cancer cell lines was also investigated using the MTS assay. The second part of this work focuses on development of TO-based G-quadruplex DNA binding ligands that can bind to DNA via the dual recognition mode. TO was tethered with pyrene, naphthalene diimide, and anthraquinone respectively to yield three novel conjugates. Further investigation suggested that the conjugate of TO with naphthalene diimide (TO-NF) gave the best G-quadruplex binding affinity. It binds to G-quadruplex DNA via the end stack mode and strongly inhibits the telomerase activity. The cytotoxicity results will also be discussed in this presentation.
The aryl hydrocarbon receptor (AhR) is a transcription factor that induces the adaptive responses upon binding to a wide range of exogenous chemicals in cells. The traditional method for studying AhR ...ligands is to determine their effect on transcriptional activities (e.g., luciferase expression) in cultured cells. In this paper, we sought to investigate the feasibility of studying the ligand binding with the AhR using a Förster resonance energy transfer (FRET) assay—a novel approach. Two conjugates (βNFQ and
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) containing β-naphthoflavone and DABCYL (a quencher) with different linkers were therefore synthesized for evaluation. The luciferase expression and green fluorescent protein (GFP) expression assays showed that βNFQ is a partial AhR agonist. Simultaneous incubation of cultured cells containing expressed GFP-AhR fusion protein with βNFQ and a known AhR ligand 3-methylchloranthrene reduced the fluorescence of GFP-AhR to a lesser extent, suggesting that the reduction in fluorescence resulted from the competitive binding of ligands to GFP-AhR. Although the fluorescent quenching by βNFQ is modest, our results suggest that FRET could be a valuable tool for identifying AhR ligands with the use of a more efficient ligand–quencher.
Guanine-rich telomeric DNA at the end of chromosomes can form a unique DNA tertiary structure - G-quadruplex, which is known to inhibit the binding of telomerase to telomeric regions in cancer cells ...and thus regulate unrestricted cancer cell growth. Hence, G-quadruplex DNA has recently become a promising target in oncology. The formation of G-quadruplex structures is greatly facilitated by G-quadruplex binding ligands such as Thiazole orange (TO). Compared with other G-quadruplex binding ligands, TO has an intriguing tunable fluorescence property. Upon binding to DNA, the fluorescence of TO can increase up to 1000-fold, making it an attractive probe for studying ligand-DNA interactions. However, the poor binding affinity and minimal binding selectivity towards different DNA conformations greatly limit its applications. My research focuses on developing G-quadruplex binding ligands using TO as a scaffold. In the first part of this work, we investigated the feasibility of increasing the TO binding affinity and selectivity toward G-quadruplex DNA by introducing side chains to the molecule. TO derivatives containing various side chains were successfully synthesized and characterized. Biophysical and biochemical studies with duplex and G-quadruplex DNA showed that tethering side chains to TO is an effective approach to tune its ability of binding to duplex or G-quadruplex DNA. Possible binding modes of the effective derivatives were studied using AutoDock. Their inhibition of telomerase activities was studied using the TRAP assay. The cytotoxicity of these derivatives toward three cancer cell lines was also investigated using the MTS assay. The second part of this work focuses on development of TO-based G-quadruplex DNA binding ligands that can bind to DNA via the dual recognition mode. TO was tethered with pyrene, naphthalene diimide, and anthraquinone respectively to yield three novel conjugates. Further investigation suggested that the conjugate of TO with naphthalene diimide (TO-NF) gave the best G-quadruplex binding affinity. It binds to G-quadruplex DNA via the end stack mode and strongly inhibits the telomerase activity. The cytotoxicity results will also be discussed in this presentation.
研究了达白1号和鄂烟1号生长早期烟碱转化诱导后烟叶及调制后烟叶烟碱转化率与生物碱含量和新烟草碱／降烟碱值（Anat／Nnic）的关系．结果表明，烟碱转化率与烟碱含量呈显著负相关关系，与降烟碱含量呈显著正相关关系，随着烟碱转化率的增加，新烟草碱和假木贼碱含量无显著变化．烟碱转化率与Anat／Nnic存在极显著的幂函数关系．早期诱导烟叶的Anat／Nnic在低于0．8时，烟碱转化率开始显著增加，其对应的烟碱转化率为2．5％；调制后烟叶Anat／Nnic在小于1．1时烟碱转化率显著增加，对应的烟碱转化率为2．8％～2．9％．著者文摘
Burley varieties, Dabai No. 1 and Eyan No. 1, were used to investigate the relationship of nicotine conversion rate with individual alkaloid contents and the ratio of anatabine to nornicotine in ethylene treated leaves and air-cured leaves. The results indicated that nicotine conversion rate had significantly negative correlations with nicotine content, and significantly positive correlation with nornicotine content. With the increase of nicotine conversion, the contents of anatabine and anabasine remained unchanged. Nicotine conversion rate had significant power function relation with Anat/Nnic. For early conversion induced leaves, when Anat/Nnic was below 0.8, the nicotine conversion rate began to increase significantly, and the corresponding
Gap graded natural sand is widely used in hydraulic structures, foundation treatment and recharge well fillers, and it’s also common in geological structures such as landslide deposits. In order to ...study the influence of grain shape on its pore and permeability characteristics, river sand in Yichang (YS), standard sand in Henan (HS) and standard smooth glass beads (BZ) are selected as test materials, and the grain shape parameters of three materials are analyzed on multiple scales. Then tests on porosity and hydraulic conductivity of gap graded natural sand were conducted. On this basis, a numerical model considering grain size distribution, coarse grain content and grain shape was established. The results showed that the average values of the shape parameters increased or decreased with the increase of grain size, and the coefficients of variation for the parameters were between 0.026 and 0.208. The shape parameters showed a negative skewness distribution, but the absolute value of the skewness coefficient was small (0.254–0.616). Grain size distribution and grain shape are the main factors controlling the porosity and hydraulic conductivity of gap graded natural sand. The minimum values of porosity and hydraulic conductivity appear at about 70 % and 30 % of large grains, respectively. The closer the grains are to the sphere, the closer the material is stacked, and the smaller the porosity value is. The grain size ratio has a significant effect on the minimum porosity of the mixture and the minimum porosity increases with the increase of the grain size ratio. The porosity of gap graded natural sand obtained by numerical method is accurate, and the error is within 10 %. The hydraulic conductivity is obtained by deriving fluid grid information and the results show that the simulated value of hydraulic conductivity is highly matched with the experimental value, and the error range is roughly between 10 % and 30 %.
•This paper selects sand materials with different shapes, and analysis the grain shape characteristics on multiple scales.•Porosity and permeability of natural gap graded sand with different shapes and sizes are studied by laboratory tests.•A numerical calculation model reflecting grain shape parameters is established.
Perturbations of the circadian clock are linked to multiple diseases, including cancers. Pharmacological activation of REV-ERB nuclear receptors, the core components of the circadian clock, has ...antitumor effects on various malignancies, while the impact of SR9009 on prostate cancer (PCa) remains unknown. Here, we found that SR9009 was specifically lethal to PCa cell lines but had no cytotoxic effect on prostate cells. SR9009 significantly inhibited colony formation, the cell cycle, and cell migration and promoted apoptosis in PCa cells. SR9009 treatment markedly inhibited prostate cancer subtype 1 (PCS1), the most lethal and aggressive PCa subtype, through FOXM1 pathway blockade, while it had no impacts on PCS2 and PCS3. Seven representative genes, including FOXM1, CENPA, CENPF, CDK1, CCNB1, CCNB2, and BIRC5, were identified as the shared genes involved in the FOXM1 pathway and PCS1. All of these genes were upregulated in PCa tissues, associated with worse clinicopathological outcomes and downregulated after SR9009 treatment. Nevertheless, knockdown or knockout of REV-ERB could not rescue the anticancer effect of SR9009 in PCa. Further analysis confirmed that it was LXRα rather than REV-ERBs which has been activated by SR9009. The expression levels of these seven genes were changed correspondingly after LXRα knockdown and SR9009 treatment. An in vivo study validated that SR9009 restrained tumor growth in 22RV1 xenograft models and inhibited FOXM1 and its targeted gene expression. In summary, SR9009 can serve as an effective treatment option for highly aggressive and lethal PCS1 tumors through mediating the LXRα/FOXM1 pathway independently of REV-ERBs.
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