Hepatitis B virus X protein enhances hepatocarcinogenesis by depressing the targeting of NUSAP1 mRNA by miR-18b

Objective: The aim of this study was to investigate the underlying mechanism whereby HBx modulates the targeting of NUSAP1 by miR-18b to enhance hepatocarcinogenesis.Methods: We employed an integrated approach of bioinformatics analysis and molecular experiments in hepatoma cells, HBV transgenic mice, and clinical liver cancer tissues to investigate the role of HBx-regulated miR-18b in the development of liver cancer.Results: In this study, we report that the HBx-mediated tumor suppressor miR-18b modulates hepatocarcinogenesis during the host-HBV interaction. The expression levels of miR-18b were lower in clinical HBV-positive liver cancer tissues and liver tissues of HBV-transgenic mice. Interestingly, HBx inhibited miR-18b expression by inducing the methylation of CpG islands in its promoter. Accordingly, we tested the hypothesis that HBx enhanced hepatocarcinogenesis by increasing the expression of target genes of miR-18b. Moreover, we identified nucleolar spindle-associated protein 1(NUSAP1) as one of the target genes of miR-18b.NUSAP1 was expressed at high levels in liver cancer tissues. Interestingly, HBx up-regulated NUSAP1 by suppressing miR-18b.Functionally, miR-18b significantly inhibited the proliferation of hepatoma cells by depressing NUSAP1 levels in vivo and in vitro.Conclusions: Thus, we conclude that the targeting of NUSAP1 mRNA by the tumor suppressor miR-18b is controlled by HBxmodulated promoter methylation during the host-virus interaction, leading to hepatocarcinogenesis. Our findings provide new insights into the mechanism by which HBx-mediated miRNAs modulate hepatocarcinogenesis.

Cation-πinteractions regulate electrocatalytic water oxidation over iridium single atoms supported on conjugated polymers

Designing cost-effective and high-performing metal catalysts is significant for many renewable energy conversion technologies.Lowering metal loading without sacrificing activity and durability is highly desired for the catalyst design,especially for those reactions where the noble metals deliver the best catalyzing performance.Single-atom catalysts(SACs)with maximal metalatom utilization,homogeneous and tailorable active sites have emerged as promising catalyst candidates,where the local coordination structures of the metal atoms in SACs largely determine the reaction kinetics.Previous design strategies of constructing strong metal-support interactions can stabilize the individual metal atoms in SACs,but present obstacles to provide a flexible manipulation platform for elaborately tailoring the coordination structures to achieve performance optimization towards a specifically targeted reaction.Here,for the proof-of-concept study,we report a novel design of SAC with iridium(Ir)single atoms supported on conjugated polymer,in which the adsorption energies of reaction intermediates on Ir atoms and the reaction kinetics towards acidic water oxidation can be readily optimized through modulating the formed cation-πinteractions that can be tailored by adjusting the molecular structures of conjugated polymers.This strategy establishes a general route to develop targeted SACs for various catalytic reactions.

A mechanistic study of selective propane dehydrogenations on MoS_(2) supported single Fe atoms

On-purpose propane dehydrogenation(PDH) has emerged as a profitable alternative to the traditional cracking of oil products for propylene production. By means of density functional theory(DFT) calculations, the present work demonstrates that Fe atoms may atomically disperse on MoS_(2)(Fe_(1)/MoS_(2)) and serve as a promising single-atom catalyst(SAC) for PDH. The catalytic activity of Fe_(1)/MoS_(2)is attributed to the highly exposed d orbitals of single Fe atoms, while the propylene selectivity is originated from the kinetic inhibition of propylene dehydrogenation resulting from fast propenyl hydrogenation. The unique catalytic selectivity of Fe_(1)/MoS_(2)may inspire further investigations of on-purpose dehydrogenations of propane on SACs.

The triggering of catalysis via structural engineering at atomic level: Direct propane dehydrogenation on Fe-N_(3)P-C

The on-purpose direct propane dehydrogenation(PDH) has received extensive attention to meet the everincreasing demand of propylene.In this work,by means of density functional theory(DFT) calculations,we systematically studied the intrinsic coordinating effect of Fe single-atom catalysts in PDH.Interestingly,the N and P dual-coordinated single Fe(Fe-N_(3)P-C) significantly outperform the Fe-N_(4-)C site in catalysis and exhibit desired activity and selectivity at industrial PDH temperatures.The mechanistic origin of different performance on Fe-N_(3)P-C and Fe-N_(4-)C has been ascribed to the geometric effect.To be specific,the in-plane configuration of Fe-N_(4) site exhibits low H affinity,which results in poor activity in C-H bond activations.By contrast,the out-of-plane structure of Fe-N_(3)P-C site exhibits moderate H affinity,which not only promote the C-H bond scission but also offer a platform for obtaining appropriate H diffusion rate which ensures the high selectivity of propylene and the regeneration of catalysts.This work demonstrates promising applications of dual-coordinated single-atom catalysts for highly selective propane dehydrogenation.

Health risk assessment of heavy metals in soils and vegetables from wastewater irrigated area,Beijing-Tianjin city cluster,China

The possible health risks of heavy metals contamination to local population through food chain were evaluated in Beijing and Tianjin city cluster, China, where have a long history of sewage irrigation. The transfer factors （TF） for heavy metals from soil to vegetables for six elements including Cu, Zn, Pb, Cr, As and Cd were calculated and the pollution load indexes （PLI） were also assessed. Results indicate that only Cd exceeded the maximum acceptable limit in these sites. So far, the heavy metal concentrations in soils and vegetables were all below the permissible limits set by the Ministry of Environmental Protection of China and World Health Organization. The transfer factors of six heavy metals showed the trend as Cd 〉 Zn 〉 Cu 〉 Pb 〉 As 〉 Cr, which were dependent on the vegetable species. The estimated dietary intakes of Cu, Zn, Pb, Cr, As and Cd were far below the tolerable limits and the target hazard quotient （THQ） values were less than 1, which suggested that the health risks of heavy metals exposure through consuming vegetables were generally assumed to be safe.

Growth and metal uptake of energy sugarcane (Saccharum spp.) in different metal mine tailings with soil amendments

A pot experiment was conducted to investigate the feasibility of growing energy sugarcane （Sac- charum spp.） in three different metal mine railings （Cu, Sn and Pb/Zn tailings） amended with uncontaminated soil at different mixing ratios. The results indicated that sugarcane was highly tolerant to tailing environments. Amendments of 20% soil to Sn tailings and 30% soil to Cu tailings could increase the biomass of cane-stem for use as the raw material for bioethanol production. Heavy metals were mostly retained in roots, which indicated that sugarcane was useful for the stabilization of the tailings. Bagasse and juice, as the most valuable parts to produce bioethanol, only accounted for 0.6%- 3% and 0.6%-7% of the total metal content. Our study supported the potential use of sugarcane for tailing phytostabilization and bioenergy production.