TGR5 agonist inhibits intestinal epithelial cell apoptosis via cAMP/PKA/c-FLIP/JNK signaling pathway and ameliorates dextran sulfate sodium-induced ulcerative colitis.

Excessive apoptosis of intestinal epithelial cell (IEC) is a crucial cause of disrupted epithelium homeostasis, leading to the pathogenesis of ulcerative colitis (UC). The regulation of Takeda G protein-coupled receptor-5 (TGR5) in IEC apoptosis and the underlying molecular mechanisms remained unclear, and the direct evidence from selective TGR5 agonists for the treatment of UC is also lacking. Here, we synthesized a potent and selective TGR5 agonist OM8 with high distribution in intestinal tract and investigated its effect on IEC apoptosis and UC treatment. We showed that OM8 potently activated hTGR5 and mTGR5 with EC50 values of 202 ± 55 nM and 74 ± 17 nM, respectively. After oral administration, a large amount of OM8 was maintained in intestinal tract with very low absorption into the blood. In DSS-induced colitis mice, oral administration of OM8 alleviated colitis symptoms, pathological changes and impaired tight junction proteins expression. In addition to enhancing intestinal stem cell (ISC) proliferation and differentiation, OM8 administration significantly reduced the rate of apoptotic cells in colonic epithelium in colitis mice. The direct inhibition by OM8 on IEC apoptosis was further demonstrated in HT-29 and Caco-2 cells in vitro. In HT-29 cells, we demonstrated that silencing TGR5, inhibition of adenylate cyclase or protein kinase A (PKA) all blocked the suppression of JNK phosphorylation induced by OM8, thus abolished its antagonizing effect against TNF-α induced apoptosis, suggesting that the inhibition by OM8 on IEC apoptosis was mediated via activation of TGR5 and cAMP/PKA signaling pathway. Further studies showed that OM8 upregulated cellular FLICE-inhibitory protein (c-FLIP) expression in a TGR5-dependent manner in HT-29 cells. Knockdown of c-FLIP blocked the inhibition by OM8 on TNF-α induced JNK phosphorylation and apoptosis, suggesting that c-FLIP was indispensable for the suppression of OM8 on IEC apoptosis induced by OM8. In conclusion, our study demonstrated a new mechanism of TGR5 agonist on inhibiting IEC apoptosis via cAMP/PKA/c-FLIP/JNK signaling pathway in vitro, and highlighted the value of TGR5 agonist as a novel therapeutic strategy for the treatment of UC.

Laser solid-phase synthesis of single-atom catalysts.

Single-atom catalysts (SACs) with atomically dispersed catalytic sites have shown outstanding catalytic performance in a variety of reactions. However, the development of facile and high-yield techniques for the fabrication of SACs remains challenging. In this paper, we report a laser-induced solid-phase strategy for the synthesis of Pt SACs on graphene support. Simply by rapid laser scanning/irradiation of a freeze-dried electrochemical graphene oxide (EGO) film loaded with chloroplatinic acid (H2PtCl6), we enabled simultaneous pyrolysis of H2PtCl6 into SACs and reduction/graphitization of EGO into graphene. The rapid freezing of EGO hydrogel film infused with H2PtCl6 solution in liquid nitrogen and the subsequent ice sublimation by freeze-drying were essential to achieve the atomically dispersed Pt. Nanosecond pulsed infrared (IR; 1064 nm) and picosecond pulsed ultraviolet (UV; 355 nm) lasers were used to investigate the effects of laser wavelength and pulse duration on the SACs formation mechanism. The atomically dispersed Pt on graphene support exhibited a small overpotential of -42.3 mV at -10 mA cm-2 for hydrogen evolution reaction and a mass activity tenfold higher than that of the commercial Pt/C catalyst. This method is simple, fast and potentially versatile, and scalable for the mass production of SACs.

3D Hand Pose Estimation Based on Five-Layer Ensemble CNN.

Estimating accurate 3D hand pose from a single RGB image is a highly challenging problem in pose estimation due to self-geometric ambiguities, self-occlusions, and the absence of depth information. To this end, a novel Five-Layer Ensemble CNN (5LENet) is proposed based on hierarchical thinking, which is designed to decompose the hand pose estimation task into five single-finger pose estimation sub-tasks. Then, the sub-task estimation results are fused to estimate full 3D hand pose. The hierarchical method is of great benefit to extract deeper and better finger feature information, which can effectively improve the estimation accuracy of 3D hand pose. In addition, we also build a hand model with the center of the palm (represented as Palm) connected to the middle finger according to the topological structure of hand, which can further boost the performance of 3D hand pose estimation. Additionally, extensive quantitative and qualitative results on two public datasets demonstrate the effectiveness of 5LENet, yielding new state-of-the-art 3D estimation accuracy, which is superior to most advanced estimation methods.

Person image generation through graph-based and appearance-decomposed generative adversarial network.

Due to the sophisticated entanglements for non-rigid deformation, generating person images from source pose to target pose is a challenging work. In this paper, we present a novel framework to generate person images with shape consistency and appearance consistency. The proposed framework leverages the graph network to infer the global relationship of source pose and target pose in a graph for better pose transfer. Moreover, we decompose the source image into different attributes (e.g., hair, clothes, pants and shoes) and combine them with the pose coding through operation method to generate a more realistic person image. We adopt an alternate updating strategy to promote mutual guidance between pose modules and appearance modules for better person image quality. Qualitative and quantitative experiments were carried out on the DeepFashion dateset. The efficacy of the presented framework are verified.

Unravelling the Mechanism of Rechargeable Aqueous Zn-MnO2 Batteries: Implementation of Charging Process by Electrodeposition of MnO2.

Poor cycling stability and mechanistic controversies have hindered the wider application of rechargeable aqueous Zn-MnO2 batteries. Herein, direct evidence was provided of the importance of Mn2+ in this type of battery by using a bespoke cell. Without pre-addition of Mn2+ , the cell exhibited an abnormal discharge-charge profile, meaning it functioned as a primary battery. By adjusting the Mn2+ content in the electrolyte, the cell recovered its charging ability through electrodeposition of MnO2 . Additionally, a dynamic pH variation was observed during the discharge-charge process, with a precipitation of Zn4 (OH)6 (SO4 )⋅5H2 O buffering the pH of the electrolyte. Contrary to the conventional Zn2+ intercalation mechanism, MnO2 was first converted into MnOOH, which reverted to MnO2 through disproportionation, resulting in the dissolution of Mn2+ . The charging process occurred by the electrodeposition of MnO2 , thus improving the reversibility through the availability of Mn2+ ions in the solution.

Dipeptidyl peptidase 4 inhibitor sitagliptin protected against dextran sulfate sodium-induced experimental colitis by potentiating the action of GLP-2.

Dipeptidyl peptidase 4 (DPP4), a ubiquitously expressed protease that cleaves off the N-terminal dipeptide from proline and alanine on the penultimate position, has important roles in many physiological processes. In the present study, experimental colitis was induced in mice receiving 3% dextran sulfate sodium (DSS) in drinking water. We found that mice with DSS-induced colitis had significantly increased intestinal DPP activity and decreased serum DPP activity, suggesting a probable correlation of DPP4 with experimental colitis. Then, we investigated whether sitagliptin, a specific DPP4 inhibitor could protect against DSS-induced colitis. We showed that oral administration of single dose of sitagliptin (30 mg/kg) on D7 remarkably inhibited DPP enzyme activity in both serum and intestine of DSS-induced colitic mice. Repeated administration of sitagliptin (10, 30 mg/kg, bid, from D0 to D8) significantly ameliorated DSS-induced colitis, including reduction of disease activity index (DAI) and body weight loss, improvement of histological score and colon length. Sitagliptin administration dose-dependently increased plasma concentrations of active form of GLP-1 and colonic expression of GLP-2R. Co-administration of GLP-2R antagonist GLP-23-33 (500 µg/kg, bid, sc) abolished the protective effects of sitagliptin in DSS-induced colitic mice. Moreover, sitagliptin administration significantly decreased the ratio of apoptotic cells and increased the ratio of proliferative cells in colon epithelium of DSS-induced colitic mice, and this effect was also blocked by GLP-23-33. Taken together, our results demonstrate that sitagliptin could attenuate DSS-induced experimental colitis and the effects can be attributed to the enhancement of GLP-2 action and the subsequent protective effects on intestinal barrier by inhibiting epithelial cells apoptosis and promoting their proliferation. These findings suggest sitagliptin as a novel therapeutic approach for the treatment of ulcerative colitis.

TGR5 agonist ameliorates insulin resistance in the skeletal muscles and improves glucose homeostasis in diabetic mice.

BACKGROUND AND PURPOSE: TGR5 plays an important role in many physiological processes. However, the functions of TGR5 in the regulation of the glucose metabolism and insulin sensitivity in the skeletal muscles have not been fully elucidated. We synthesized MN6 as a potent and selective TGR5 agonist. Here, the effect of MN6 on insulin resistance in skeletal muscles was evaluated in diet-induced obese (DIO) mice and C2C12 myotubes, and the underlying mechanisms were explored. METHODS: The activation of MN6 on human and mouse TGR5 was evaluated by a cAMP assay in HEK293 cell lines stable expressing hTGR5/CRE or mTGR5/CRE cells. GLP-1 secretion was measured in NCI-H716 cells and CD1 mice. The acute and chronic effects of MN6 on regulating metabolic abnormalities were observed in ob/ob and DIO mice. 2-deoxyglucose uptake was examined in isolated skeletal muscles. Akt phosphorylation, glucose uptake and glycogen synthesis were examined to assess the effects of MN6 on palmitate-induced insulin resistance in C2C12 myotubes. RESULTS: MN6 potently activated human and mouse TGR5 with EC50 values of 15.9 and 17.9 nmol/L, respectively, and stimulated GLP-1 secretion in NCI-H716 cells and CD1 mice. A single oral dose of MN6 significantly decreased the blood glucose levels in ob/ob mice. Treatment with MN6 for 15 days reduced the fasting blood glucose and HbA1c levels in ob/ob mice. MN6 improved glucose and insulin tolerance and enhanced the insulin-stimulated glucose uptake of skeletal muscles in DIO mice. The palmitate-induced impairment of insulin-stimulated Akt phosphorylation, glucose uptake and glycogen synthesis in C2C12 myotubes could be prevented by MN6. The effect of MN6 on palmitate-impaired insulin-stimulated Akt phosphorylation was abolished by siRNA-mediated knockdown of TGR5 or by the inhibition of adenylate cyclase or protein kinase A, suggesting that this effect is dependent on the activation of TGR5 and the cAMP/PKA pathway. CONCLUSIONS: Our study identified that a TGR5 agonist could ameliorate insulin resistance by the cAMP/PKA pathway in skeletal muscles; this uncovered a new effect of the TGR5 agonist on regulating the glucose metabolism and insulin sensitivity in skeletal muscles and further strengthened its potential value for the treatment of type 2 diabetes.

3D Printing of Freestanding MXene Architectures for Current-Collector-Free Supercapacitors.

Additive manufacturing (AM) technologies appear as a paradigm for scalable manufacture of electrochemical energy storage (EES) devices, where complex 3D architectures are typically required but are hard to achieve using conventional techniques. The combination of these technologies and innovative material formulations that maximize surface area accessibility and ion transport within electrodes while minimizing space are of growing interest. Herein, aqueous inks composed of atomically thin (1-3 nm) 2D Ti3 C2 Tx with large lateral size of about 8 µm possessing ideal viscoelastic properties are formulated for extrusion-based 3D printing of freestanding, high specific surface area architectures to determine the viability of manufacturing energy storage devices. The 3D-printed device achieves a high areal capacitance of 2.1 F cm-2 at 1.7 mA cm-2 and a gravimetric capacitance of 242.5 F g-1 at 0.2 A g-1 with a retention of above 90% capacitance for 10 000 cycles. It also exhibits a high energy density of 0.0244 mWh cm-2 and a power density of 0.64 mW cm-2 at 4.3 mA cm-2 . It is anticipated that the sustainable printing and design approach developed in this work can be applied to fabricate high-performance bespoke multiscale and multidimensional architectures of functional and structural materials for integrated devices in various applications.

In Situ Self-Template Synthesis of Fe-N-Doped Double-Shelled Hollow Carbon Microspheres for Oxygen Reduction Reaction.

Herein, we reported a special Fe-N-doped double-shelled hollow carbon microsphere (Fe-N-DSC) which was prepared by a facile, in situ polymerization followed by pyrolysis. With porous ferroferric oxide (Fe3O4) hollow microspheres as the templates, where pyrrole monomers were dispersed around the outer surface and prefilled the interior space. By adding hydrochloric acid, Fe3+ ions were released to initiate polymerization of pyrrole on both the outer and inner surfaces of Fe3O4 microspheres until they were completely dissolved, resulting in the Fe-containing polypyrrole double-shelled hollow carbon microspheres (Fe-PPY-DSC). The Fe-PPY-DSC was then pyrolyzed to generate the Fe-N-DSC. The Fe3O4 hollow microspheres played trifunctional roles, i.e., the template to prepare a double-shelled hollow spherical structure, the initiator (i.e., Fe3+ ions) for the polymerization of pyrrole, and the Fe source for doping. The Fe-N-DSC exhibited a superior catalytic activity for oxygen reduction as comparable to commercial Pt/C catalysts in both alkaline and acidic media. The high catalytic performance was ascribed to the special porous double-shelled hollow spherical structure, which provided more active sites and was beneficial to a high-flux mass transportation.

In vitro and in vivo antitumor effects of acetylshikonin isolated from Arnebia euchroma (Royle) Johnst (Ruanzicao) cell suspension cultures.

BACKGROUND: Shikonin derivatives have cytotoxic and antitumor effects. This study aims to investigate the antitumor effects of acetylshikonin isolated from a Chinese medicinal herb Arnebia euchroma (Royle) Johnst. METHODS: The 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the in vitro antitumor effects of acetylshikonin on human lung adenocarcinoma cell line A549, human hepatocellular carcinoma cell line Bel-7402, human breast adenocarcinoma cell line MCF-7 and mouse Lewis lung carcinoma (LLC) cell line. C57BL/6 mice with LLC model were used to study the in vivo antitumor effects of acetylshikonin. The expression of bax, bcl-2 and caspase-3 proteins in LLC tissue was determined with immunohistochemical staining. RESULTS: In A549, Bel-7402, MCF-7 and LLC cell lines, acetylshikonin inhibited cell growth in a dose-dependent manner. IC50 (means +/- SD) were 5.6 +/- 0.86 microg/ml, 6.82 +/- 1.5 microg/ml, 3.04 +/- 0.44 microg/ml and 2.72 +/- 0.38 microg/ml respectively. Acetylshikonin suppressed tumor growth in C57BL/6 mice with LLC. The inhibition rate of acetylshikonin (2 mg/kg) was 42.85%. Immunohistochemical staining revealed that in the acetylshikonin groups the expression of bax and caspase-3 increased, whereas the expression of bcl-2 decreased, suggesting that acetylshikonin induced tumor cell apoptosis through activating the pro-apoptotic bcl-2 family and caspase-3. CONCLUSION: Acetylshikonin isolated from Arnebia euchroma (Royle) Johnst cell suspension cultures exhibits specific in vivo and in vitro antitumor effects.