Lithium-oxygen batteries with ultrahigh energy density have received considerable attention as of the future energy storage technologies. The development of effective electrocatalysts and a ...corresponding working mechanism during cycling are critically important for lithium-oxygen batteries. Here, a single cobalt atom electrocatalyst is synthesized for lithium-oxygen batteries by a polymer encapsulation strategy. The isolated moieties of single atom catalysts can effectively regulate the distribution of active sites to form micrometre-sized flower-like lithium peroxide and promote the decomposition of lithium peroxide by a one-electron pathway. The battery with single cobalt atoms can operate with high round-trip efficiency (86.2%) and long-term stability (218 days), which is superior to a commercial 5 wt% platinum/carbon catalyst. We reveal that the synergy between a single atom and the support endows the catalyst with excellent stability and durability. The promising results provide insights into the design of highly efficient catalysts for lithium-oxygen batteries and greatly expand the scope of future investigation.
Janus-faced role of SIRT1 in tumorigenesis Song, Na-Young; Surh, Young-Joon
Annals of the New York Academy of Sciences,
October 2012, Letnik:
1271, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Silent mating type information regulation 1 (Sirtuin 1; SIRT1) has been reported to regulate various physiological events, such as aging and metabolism, via deacetylation of histone and nonhistone ...proteins. Notably, cumulative evidence supports the notion that SIRT1 has a Janus‐faced role in tumorigenesis. SIRT1 contributes to anti‐inflammation, genomic stability, and cancer cell death, and hence it has tumor‐suppressor properties. On the other hand, SIRT1 can stimulate oncogenic signaling pathways and can create a tumor microenvironment favorable to growth and survival of cancer cells. Such dual functions of SIRT1 may be determined, at least in part, by its subcellular localization. Interestingly, SIRT1 displays differential localization in normal cells and cancer cells, which in turn may affect the substrate specificity for its deacetylase activity.
SIRT1, an NAD+-dependent histone/protein deacetylase, has diverse physiological actions. Recent studies have demonstrated that SIRT1 is overexpressed in colorectal cancer, suggesting its oncogenic ...potential. However, the molecular mechanisms by which overexpressed SIRT1 induces the progression of colorectal cancer and its inhibition remain largely unknown. Curcumin (diferuloymethane), a major component of the spice turmeric derived from the plant Curcuma longa L., has been reported to exert chemopreventive and anti-carcinogenic effects on colon carcinogenesis. In the present study, we found that curcumin reduced the expression of SIRT1 protein without influencing its mRNA expression in human colon cancer cells, suggesting posttranslational regulation of SIRT1 by this phytochemical. Notably, ubiquitination and subsequent proteasomal degradation of SIRT1 were induced by curcumin treatment. Results of nano-LC-ESI-MS/MS revealed the direct binding of curcumin to cysteine 67 of SIRT1. In line with this result, the protein stability and clonogenicity of a mutant SIRT1 in which cysteine 67 was substituted by alanine were unaffected by curcumin. Taken together, these observations suggest that curcumin facilitates the proteasomal degradation of oncogenic SIRT1 through covalent modification of SIRT1 at the cysteine 67 residue.
•SIRT1 is overexpressed in colorectal cancer tissues compared with normal colon tissues.•SIRT1 knockdown attenuates viability and migration of human colon cancer cells.•Silencing of SIRT1 suppressed the growth of HCT-116 derived tumor xenografts.•Curcumin inhibits migration and growth of HCT-116 cells.•Curcumin covalently modifies SIRT1 on the cysteine 67 residue, thereby stimulating its proteasomal degradation.
An anisotropic thermally conductive film with tailorable microstructures and macroproperties is fabricated using a layer-by-layer (LbL) assembly of graphene oxide (GO) and nanofibrillated cellulose ...(NFC) on a flexible NFC substrate driven by hydrogen bonding interactions, followed by chemical reduction process. The resulting NFC/reduced graphene oxide (RGO) hybrid film reveals an orderly hierarchical structure in which the RGO nanosheets exhibit a high degree of orientation along the in-plane direction. The assembly cycles dramatically increase the in-plane thermal conductivity (λ X ) of the hybrid film to 12.6 W·m–1·K–1, while the cross-plane thermal conductivity (λ Z ) shows a lower value of 0.042 W·m–1·K–1 in the hybrid film with 40 assembly cycles. The thermal conductivity anisotropy reaches up to λ X /λ Z = 279, which is substantially larger than that of similar polymeric nanocomposites, indicating that the LbL assembly on a flexible NFC substrate is an efficient technique for the preparation of polymeric nanocomposites with improved heat conducting property. Moreover, the layered hybrid film composed of 1D NFC and 2D RGO exhibits synergetic mechnical properties with outstanding flexibility and a high tensile strength (107 MPa). The combination of anisotropic thermal conductivity and superior mechanical performance may facilitate the applications in thermal management.
Establishing reliable strategies for rationally manipulating the organization of peptide building blocks and thereby precisely creating chiral nanostructures is challenging, while meaningful toward ...development of advanced functional materials. Here we report on a peptide-interdigitating mechanism for the reliable self-assembly of lipid-inspired amphiphiles (LIPIAs) into robust twisted nanoribbons by grafting domains to one alkyl tail of lipids as an extended element. Peptide interdigitation promoted the self-assembly of LIPIAs into twisted or flat nanoribbons driven by antiparallel or parallel β-sheet hydrogen bonds, respectively, strongly associated with the connecting direction of the incorporated domains. We found that the LIPIAs containing N-terminus-connected domains with either bulky or small side chain groups formed twisted nanoribbons in a broad pH range, thus implying a sequence- and pH-independent strategy for creation of robust chiral nanostructures. Integrating the resulting twisted nanoribbons with gold nanoparticles led to supramolecular nanozymes exhibiting the excellent catalytic activity and enantioselectivity of asymmetric oxidation of 3,4-dihyroxy-phenylalanine molecules. Our finding demonstrates that the peptide-interdigitating mechanism is a reliable strategy for precise creation of chiral nanostructures serving as chiral matrices for supramolecular nanozymes with improved catalytic performance, thus potentially paving the way towards advanced biomimetic systems resembling natural systems.
Circular RNAs (circRNAs) play a critical regulatory role in cancer progression. However, the underlying mechanisms of circRNAs in hepatocellular carcinoma (HCC) metastasis remain mostly unknown.
...Has_circ_0003998 (circ0003998) was identified by RNAs sequencing in HCC patients with /without portal vein tumor thrombus (PVTT) metastasis. The expression level of circ0003998 was further detected by in situ hybridization on tissues microarray (ISH-TMA) and qRT-PCR in 25 HCC patients with PVTT metastasis. Moreover, the 25 HCC patients with PVTT metastasis and 50 HCC patients without PVTT metastasis were recruited together to analyze the correlation between circ0003998 expression and HCC clinical characteristics. Transwell, migration and CCK8 assays, as well as nude mice model of lung or liver metastasis were used to evaluate the role of circ0003998 in epithelial to mesenchymal transition (EMT) in HCC. The regulatory mechanisms of circ0003998 in miR-143-3p and PCBP1 were determined by dual-luciferase reporter assay, nuclear-cytoplasmic fractionation, fluorescent in situ hybridization, RNA pull- down, microRNA sequence, western blot and RNA immunoprecipitation.
Compared with adjacent normal liver tissues (ANL), circ0003998 expression was significantly upregulated in PVTT tissues and HCC tissues, and its expression correlates with the aggressive characteristics of HCC patients. Further assays suggested that circ0003998 promoted EMT of HCC both in vitro and in vivo. Mechanistically, our data indicated that circ0003998 may act as a ceRNA (competing endogenous RNA) of microRNA-143-3p to relieve the repressive effect on EMT-related stimulator, FOSL2; meanwhile, circ0003998 could bind with PCBP1-poly(rC) binding protein 1 (PCBP1) to increase the expression level of EMT-related genes, CD44v6.
Circ0003998 promotes EMT of HCC by circ0003998/miR-143-3p/FOSL2 axis and circ0003998 /PCBP1/CD44v6 axis.
In the present study, a simple and environmentally friendly extraction method based on natural deep eutectic solvents (NADESs) was established to extract four bioactive steroidal saponins from ...Dioscoreae Nipponicae Rhizoma (DNR). A total of twenty-one types of choline chloride, betaine, and L-proline based NADESs were tailored, and the NADES composed of 1:1 molar ratio of choline chloride and malonic acid showed the best extraction efficiency for the four steroidal saponins compared with other NADESs. Then, the extraction parameters for extraction of steroidal saponins by selected tailor-made NADES were optimized using response surface methodology and the optimal extraction conditions are extraction time, 23.5 min; liquid-solid ratio, 57.5 mL/g; and water content, 54%. The microstructure of the DNR powder before and after ultrasonic extraction by conventional solvents (water and methanol) and the selected NADES were observed using field emission scanning electron microscope. In addition, the four steroidal saponins were recovered from NADESs by D101 macroporous resin with a satisfactory recovery yield between 67.27% and 79.90%. The present research demonstrates that NADESs are a suitable green media for the extraction of the bioactive steroidal saponins from DNR, and have a great potential as possible alternatives to organic solvents for efficiently extracting bioactive compounds from natural products.
Polymer materials with high thermal conductivities play an important role in the development of next-generation electronics. In this work, high thermally conductive nanofibrillated cellulose (NFC) ...hybrid films based on nanodiamonds (NDs) and graphene sheets (GSs) were prepared by a facile vacuum-filtration self-assembly process. Inspired by the structure of nacre, zero-dimensional NDs, two-dimensional GSs, and one-dimensional NFC were used to build hierarchical structures, which lead to excellent mechanical properties of the hybrid films. More importantly, an efficient thermally conductive pathway, involving NDs and GSs, endows the hybrid films with a much higher in-plane thermal conductivity. At a filler content of 10 wt %, the in-plane thermal conductivity of the f-C/ND/G hybrid film could reach 14.35 W·m–1·K–1, which is at a high level compared with other published studies. This hybrid film exhibits significant thermal conductivity combined with excellent mechanical properties that can be applied to portable electronic equipment as a lateral heat spreader.
The emphasis of our study was to determine the physiological function of miR‐1224‐5p in rectal cancer (RC) and its in‐depth mechanism. First, the expression of miR‐1224‐5p in RC tissues was analyzed ...using public data from the TCGA database. Then, miR‐1224‐5p expression in RC cell lines SW480 and SW837 was measured using the qRT‐PCR assay. The subsequent CCK‐8 assay was executed to assess the function of miR‐1224‐5p in the viability of the RC cell. Bioinformatics prediction prompted that SLC29A3 may be a potential target gene for miR‐1224‐5p. Western blotting and dual‐luciferase reporter assays were performed to affirm the above forecasting. Kaplan–Meier analysis and Cox multivariate analysis were carried out to assess the relationship between SLC29A3 and prognosis. Finally, CCK‐8, colony formation assay, and transwell assay were used for functional analysis of miR‐1224‐5p/ SLC29A3 axis in vitro. MiR‐1224‐5p was expressed at low levels in RC tissues and cell lines. Up‐regulation of miR‐1224‐5p inhibited SW480 cell viability, while inhibition of miR‐1224‐5p enhanced the viability of SW837 cells. What is more, we affirmed that miR‐1224‐5p could direct target SLC29A3, which was expressed at high levels in RC tissues. In addition, SLC29A3 could be used as an independent predictive factor of prognosis in patients with RC, and the higher SLC29A3 expression, the lower survival rate. Finally, cellular functional experiments evidenced that miR‐1224‐5p mimic can reduce the cell viability, invasion, and migration, while overexpression of SLC29A3 presented an opposite effect. Importantly, co‐transfection experiments indicated that SLC29A3 can reverse miR‐1224‐5p‐mediated inhibition in the malignant progression of RC cells. Our work raised the possibility that miR‐1224‐5p functioned as a tumor suppressor in RC, which achieved its function via targeting SLC29A3.
In this work, 3D graphene structures constructed by graphene foam (GF) were introduced into polyamide-6 (PA6) matrix for the purpose of enhancing the thermal-conductive and anti-dripping properties ...of PA6 composites. The GF were prepared by one-step hydrothermal method. The PA6 composites were synthesized by in-situ thermal polycondensation method to realize PA6 chains covalently grafted onto the graphene sheets. The 3D interconnected graphene structure favored the formation of the consecutive thermal conductive paths or networks even at relatively low graphene loadings. As a result, the thermal conductivity was improved by 300% to 0.847W·m−1·K−1 of PA6 composites at 2.0wt% graphene loading from 0.210W·m−1·K−1 of pure PA6 matrix. The presence of self-supported 3D structure alone with the covalently-grafted PA6 chains endowed the PA6 composites good anti-dripping properties.
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