As a new class of crystalline porous organic materials, covalent organic frameworks (COFs) have attracted considerable attention for proton conduction owing to their regular channels and tailored ...functionality. However, most COFs are insoluble and unprocessable, which makes membrane preparation for practical use a challenge. In this study, we used surface‐initiated condensation polymerization of a trialdehyde and a phenylenediamine for the synthesis of sulfonic COF (SCOF) coatings. The COF layer thickness could be finely tuned from 10 to 100 nm by controlling the polymerization time. Moreover, free‐standing COF membranes were obtained by sacrificing the bridging layer without any decomposition of the COF structure. Benefiting from the abundant sulfonic acid groups in the COF channels, the proton conductivity of the SCOF membrane reached 0.54 S cm−1 at 80 °C in pure water. To our knowledge, this is one of the highest values for a pristine COF membrane in the absence of additional additives.
A free‐standing covalent organic framework (COF) membrane with controlled thickness was obtained by using a surface‐initiated polymerization strategy (see picture). The rigid organic skeleton and defined pore structure of the COF membrane as well as the abundance of sulfonic acid groups throughout the layer led to superior proton conductivity of 0.54 S cm−1 at 80 °C in pure water.
Research on heterogeneous single-atom catalysts (SACs) has become an emerging frontier in catalysis science because of their advantages in high utilization of noble metals, precisely identified ...active sites, high selectivity, and tunable activity. Graphene, as a one-atom-thick two-dimensional carbon material with unique structural and electronic properties, has been reported to be a superb support for SACs. Herein, we provide an overview of recent progress in investigations of graphene-based SACs. Among the large number of publications, we will selectively focus on the stability of metal single-atoms (SAs) anchored on different sites of graphene support and the catalytic performances of graphene-based SACs for different chemical reactions, including thermocatalysis and electrocatalysis. We will summarize the fundamental understandings on the electronic structures and their intrinsic connection with catalytic properties of graphene-based SACs, and also provide a brief perspective on the future design of efficient SACs with graphene and graphene-like materials.
Pollution by heavy metals limits the area of land available for cultivation of food crops. A potential solution to this problem might lie in the molecular breeding of food crops for phytoremediation ...that accumulate toxic metals in straw while producing safe and nutritious grains. Here, we identify a rice quantitative trait locus we name cadmium (Cd) accumulation in leaf 1 (CAL1), which encodes a defensin-like protein. CAL1 is expressed preferentially in root exodermis and xylem parenchyma cells. We provide evidence that CAL1 acts by chelating Cd in the cytosol and facilitating Cd secretion to extracellular spaces, hence lowering cytosolic Cd concentration while driving long-distance Cd transport via xylem vessels. CAL1 does not appear to affect Cd accumulation in rice grains or the accumulation of other essential metals, thus providing an efficient molecular tool to breed dual-function rice varieties that produce safe grains while remediating paddy soils.
There is an urgent need for vaccines against coronavirus disease 2019 (COVID-19) because of the ongoing SARS-CoV-2 pandemic. Among all approaches, a messenger RNA (mRNA)-based vaccine has emerged as ...a rapid and versatile platform to quickly respond to this challenge. Here, we developed a lipid nanoparticle-encapsulated mRNA (mRNA-LNP) encoding the receptor binding domain (RBD) of SARS-CoV-2 as a vaccine candidate (called ARCoV). Intramuscular immunization of ARCoV mRNA-LNP elicited robust neutralizing antibodies against SARS-CoV-2 as well as a Th1-biased cellular response in mice and non-human primates. Two doses of ARCoV immunization in mice conferred complete protection against the challenge of a SARS-CoV-2 mouse-adapted strain. Additionally, ARCoV is manufactured as a liquid formulation and can be stored at room temperature for at least 1 week. ARCoV is currently being evaluated in phase 1 clinical trials.
Display omitted
•Development of LNP-encapsulated mRNA vaccine (ARCoV) targeting the RBD of SARS-CoV-2•ARCoV induces neutralizing antibodies and T cell immunity in mice and NHPs•ARCoV vaccination confers full protection against SARS-CoV-2 challenge in mice•ARCoV is a thermostable vaccine candidate for phase I studies
ARCoV is an LNP-encapsulated mRNA vaccine platform that is highly immunogenic and safe in mice and non-human primates, conferring protection against challenge with a SARS-CoV-2 mouse-adapted strain.
Peroxisomes account for ~35% of total H2O2 generation in mammalian tissues. Peroxisomal ACOX1 (acyl‐CoA oxidase 1) is the first and rate‐limiting enzyme in fatty acid β‐oxidation and a major producer ...of H2O2. ACOX1 dysfunction is linked to peroxisomal disorders and hepatocarcinogenesis. Here, we show that the deacetylase sirtuin 5 (SIRT5) is present in peroxisomes and that ACOX1 is a physiological substrate of SIRT5. Mechanistically, SIRT5‐mediated desuccinylation inhibits ACOX1 activity by suppressing its active dimer formation in both cultured cells and mouse livers. Deletion of SIRT5 increases H2O2 production and oxidative DNA damage, which can be alleviated by ACOX1 knockdown. We show that SIRT5 downregulation is associated with increased succinylation and activity of ACOX1 and oxidative DNA damage response in hepatocellular carcinoma (HCC). Our study reveals a novel role of SIRT5 in inhibiting peroxisome‐induced oxidative stress, in liver protection, and in suppressing HCC development.
Synopsis
This study reveals a role for SIRT5 in regulating peroxisomal H2O2 and ROS homeostasis and indicates its potential function in liver protection and hepatocellular carcinoma suppression.
SIRT5 is localized in peroxisomes where it controls H2O2 metabolism.
SIRT5‐mediated desuccinylation inhibits ACOX1 activity by suppressing its active dimer formation.
SIRT5 downregulation increases ACOX1 activity and oxidative DNA damage response in HCC.
This study reveals a role for SIRT5 in regulating peroxisomal H2O2 and ROS homeostasis and indicates its potential function in liver protection and hepatocellular carcinoma suppression.
Mobile Edge Computing (MEC) has been widely employed to support various Internet of Things (IoT) and mobile applications. By leveraging the advantages of easily deployed and flexibility of Unmanned ...Aerial Vehicle (UAV), one of MEC primary functions is employing UAVs equipped with MEC servers to provide computation supports for the offloaded tasks by mobile users in temporally hotspot areas or some emergent scenarios, such as sports game areas or destroyed by natural disaster areas. Despite the numerous advantages of UAV carried with a MEC server, it is restricted by its limited computation resources and sensitive energy consumption. Moreover, due to the complexity of UAV-assisted MEC system, its computational resource optimization and energy consumption optimization cannot be achieved well in traditional optimization methods. Furthermore, the computational cost of the MEC system optimization is often exponentially growing with the increase of the MEC servers and mobile users. Therefore, it is considerably challenging to control the UAV positions and schedule the task offloading ratio. In this paper, we proposed a novel Deep Reinforcement Learning (DRL) method to optimize UAV trajectory controlling and users' offloaded task ratio scheduling and improve the performance of the UAV-assisted MEC system. We maximized the system stability and minimized the energy consumption and computation latency of UAV-assisted the MEC system. The simulation results show that the proposed method outperforms existing work and has better scalability.
Prevention and management of lung cancer in China Hong, Qun‐Ying; Wu, Guo-Ming; Qian, Gui‐Sheng ...
Cancer,
September 1, 2015, 2015-Sep-01, 2015-09-00, 20150901, Volume:
121, Issue:
S17
Journal Article
Retinal pigment epithelium (RPE) cell damage is implicated in the pathogenesis of age‐related macular degeneration (AMD). An increase of interferon‐γ (IFN‐γ) levels was observed in patients with AMD, ...but whether inflammatory factors are causally related to AMD progression is unclear. Here, we demonstrate a direct causal relationship between IFN‐γ and RPE cell death. IFN‐γ induced human retinal pigment epithelial cell (ARPE‐19) death accompanied by increases in Fe2+, reactive oxygen species, lipid peroxidation, and glutathione (GSH) depletion, which are main characteristics of ferroptosis. Mechanistically, IFN‐γ upregulates the level of intracellular Fe2+ through inhibiting Fe2+ efflux protein SLC40A1 and induces GSH depletion by blocking cystine/glutamate antiporter, System xc‐. At the same time, treatment with IFN‐γ decreases the level of glutathione peroxidase 4 (GPx4), rendering the cells more sensitive to ferroptosis. JAK1/2 and STAT1 inhibitors could reverse the reduction of SLC7A11, GPx4 and GSH expression induced by IFN‐γ, indicating IFN‐γ induces ARPE‐19 cell ferroptosis via activation of the JAK1‐2/STAT1/SLC7A11 signaling pathway. The above results were largely confirmed in IFN‐γ‐treated mice in vivo. Finally, we used sodium iodate (NaIO3)‐induced retinal degeneration to further explore the role of ferroptosis in AMD in vivo. Consistent with the role of IFN‐γ, treatment with NaIO3 decreased SLC7A11, GPx4 and SLC40A1 expressions. NaIO3‐induced RPE damage was accompanied by increased iron, lipid peroxidation products (4‐hydroxynonenal, malondialdehyde), and GSH depletion, and ferroptosis inhibitors could reverse the above phenomenon. Taken together, our findings suggest that inhibiting ferroptosis or reducing IFN‐γ may serve as a promising target for AMD.
IFN‐γ downregulates the expression of SLC7A11 via JAK1‐2/STAT1 signaling pathway, which results in decreases in cysteine transport and, subsequently, decreased GSH synthesis. Simultaneously, IFN‐γ increases intracellular Fe2+ levels through the inhibition of SLC40A1. GSH depletion and Fe2+ accumulation cause retinal pigment epithelial cells ferroptosis and accelerate the progression of AMD.
Mimicking proton conduction mechanism of Nafion to construct novel proton-conducting materials with low cost and high proton conductivity is of wide interest. Herein, we have designed and synthesized ...a cationic covalent organic framework with high thermal and chemical stability by combining a cationic monomer, ethidium bromide (EB) (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide), with 1,3,5-triformylphloroglucinol (TFP) in Schiff base reactions. This is the first time that the stable cationic crystalline frameworks allowed for the fabrication of a series of charged COFs (EB-COF:X, X = F, Cl, Br, I) through ion exchange processes. Exchange of the extra framework ions can finely modulate the COFs’ porosity and pore sizes at nanoscale. More importantly, by introducing PW12O40 3– into this porous cationic framework, we can greatly enhance the proton conductivity of ionic COF-based material. To the best of our knowledge, EB-COF:PW 12 shows the best proton conductivity at room temperature among ever reported porous organic materials.
Diverse cellular functions, including tumor suppressor gene expression, DNA repair, cell proliferation and apoptosis, are regulated by histone acetylation and deacetylation. Histone deacetylases ...(HDACs) are enzymes involved in remodeling of chromatin by deacetylating the lysine residues. They play a pivotal role in epigenetic regulation of gene expression. Dysregulation of HDACs and aberrant chromatin acetylation and deacetylation have been implicated in the pathogenesis of various diseases, including cancer. Histone deacetylases have become a target for the development of drugs for treating cancer because of their major contribution to oncogenic cell transformation. Overexpression of HDACs correlates with tumorigenesis. Previous work showed that inhibition of HDACs results in apoptosis and the inhibition of cell proliferation in multiple cells. A significant number of HDAC inhibitors have been developed in the past decade. These inhibitors have strong anticancer effects in vitro and in vivo, inducing growth arrest, differentiation, and programmed cell death, inhibiting cell migration, invasion, and metastasis, and suppressing angiogenesis. In addition, HDAC‐mediated deacetylation alters the transcriptional activity of nuclear transcription factors, including p53, E2F, c‐Myc, and nuclear factor‐κB, as well as the extracellular signal‐regulated kinase1/2, phosphatidylinositol 3‐kinase, Notch, and Wnt signaling pathways. This review highlights the role of HDACs in cancer pathogenesis and, more importantly, that HDACs are potential novel therapeutic targets.
PDF
