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1.
Int J Mol Sci ; 22(19)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34638572

RESUMO

Spinal muscular atrophy (SMA) is caused by homozygous survival of motor neurons 1 (SMN1) gene deletion, leaving a duplicate gene, SMN2, as the sole source of SMN protein. However, a defect in SMN2 splicing, involving exon 7 skipping, results in a low level of functional SMN protein. Therefore, the upregulation of SMN protein expression from the SMN2 gene is generally considered to be one of the best therapeutic strategies to treat SMA. Most of the SMA drug discovery is based on synthetic compounds, and very few natural compounds have been explored thus far. Here, we performed an unbiased mechanism-independent and image-based screen of a library of microbial metabolites in SMA fibroblasts using an SMN-specific immunoassay. In doing so, we identified brefeldin A (BFA), a well-known inhibitor of ER-Golgi protein trafficking, as a strong inducer of SMN protein. The profound increase in SMN protein was attributed to, in part, the rescue of the SMN2 pre-mRNA splicing defect. Intriguingly, BFA increased the intracellular calcium concentration, and the BFA-induced exon 7 inclusion of SMN2 splicing, was abrogated by the depletion of intracellular calcium and by the pharmacological inhibition of calcium/calmodulin-dependent kinases (CaMKs). Moreover, BFA considerably reduced the expression of Tra2-ß and SRSF9 proteins in SMA fibroblasts and enhanced the binding of PSF and hnRNP M to an exonic splicing enhancer (ESE) of exon 7. Together, our results demonstrate a significant role for calcium and its signaling on the regulation of SMN splicing, probably through modulating the expression/activity of splicing factors.


Assuntos
Sinalização do Cálcio/genética , Expressão Gênica/genética , Neurônios Motores/fisiologia , Linhagem Celular , Retículo Endoplasmático/genética , Retículo Endoplasmático/fisiologia , Éxons/genética , Fibroblastos/fisiologia , Complexo de Golgi/genética , Complexo de Golgi/fisiologia , Células HEK293 , Humanos , Atrofia Muscular Espinal/genética , Transporte Proteico/genética , Transporte Proteico/fisiologia , Splicing de RNA/genética , RNA Mensageiro/genética , Proteínas do Complexo SMN/genética
2.
Arch Microbiol ; 201(10): 1427-1433, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31414157

RESUMO

We controlled and observed individual magneto-tactic bacteria (Magnetospirillum gryphiswaldense) inside a [Formula: see text]-high microfluidic channel for over 4 h. After a period of constant velocity, the duration of which varied between bacteria, all observed bacteria showed a gradual decrease in their velocity of about [Formula: see text]. After coming to a full stop, different behaviour was observed, ranging from rotation around the centre of mass synchronous with the direction of the external magnetic field, to being completely immobile. Our results suggest that the influence of the high-intensity illumination and the presence of the channel walls are important parameters to consider when performing observations of such long duration.


Assuntos
Técnicas Bacteriológicas/métodos , Magnetospirillum/fisiologia , Microfluídica , Técnicas Bacteriológicas/normas , Fatores de Tempo
3.
Nanotechnology ; 29(6): 065703, 2018 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-29239861

RESUMO

Doping effects in devices based on two-dimensional (2D) materials have been widely studied. However, detailed analysis and the mechanism of the doping effect caused by encapsulation layers has not been sufficiently explored. In this work, we present experimental studies on the n-doping effect in WSe2 field effect transistors (FETs) with a high-k encapsulation layer (Al2O3) grown by atomic layer deposition. In addition, we demonstrate the mechanism and origin of the doping effect. After encapsulation of the Al2O3 layer, the threshold voltage of the WSe2 FET negatively shifted with the increase of the on-current. The capacitance-voltage measurements of the metal insulator semiconductor (MIS) structure proved the presence of the positive fixed charges within the Al2O3 layer. The flat-band voltage of the MIS structure of Au/Al2O3/SiO2/Si was shifted toward the negative direction on account of the positive fixed charges in the Al2O3 layer. Our results clearly revealed that the fixed charges in the Al2O3 encapsulation layer modulated the Fermi energy level via the field effect. Moreover, these results possibly provide fundamental ideas and guidelines to design 2D materials FETs with high-performance and reliability.

4.
Virol J ; 13: 99, 2016 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-27296985

RESUMO

BACKGROUND: Enterovirus 71 (EV71) is a major causative agent of hand-foot-mouth disease (HFMD) and also causes severe neurological complications, leading to fatality in young children. However, no effective therapy is currently available for the treatment of this infection. METHODS: We identified small-molecule inhibitors of EV71 from a screen of 968 Food and Drug Administration (FDA)-approved drugs, with which clinical application for EV71-associated diseases would be more feasible, using EV71 subgenomic replicon system. Primary hits were extensively evaluated for their antiviral activities in EV71-infected cells. RESULTS: We identified micafungin, an echinocandin antifungal drug, as a novel inhibitor of EV71. Micafungin potently inhibits the proliferation of EV71 as well as the replication of EV71 replicon in cells with a low micromolar IC50 (~5 µM). The strong antiviral effect of micafungin on EV71 replicon and the result from time-of-addition experiment demonstrated a targeting of micafungin on virion-independent intracellular process(es) during EV71 infection. Moreover, an extensive analysis excluded the involvement of 2C and 3A proteins, IRES-dependent translation, and also that of polyprotein processing in the antiviral effect of micafungin. CONCLUSIONS: Our research revealed a new indication of micafungin as an effective inhibitor of EV71, which is the first case reporting antiviral activity of micafungin, an antifungal drug.


Assuntos
Antivirais/farmacologia , Equinocandinas/farmacologia , Enterovirus Humano A/efeitos dos fármacos , Lipopeptídeos/farmacologia , Animais , Linhagem Celular , Reposicionamento de Medicamentos , Humanos , Micafungina
5.
Biol Pharm Bull ; 37(10): 1655-60, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25099343

RESUMO

Diacylglycerol acyltransferase 2 (DGAT2), which catalyzes the final step in triacylglycerol (TG) synthesis, is a key enzyme associated with hepatic steatosis and insulin resistance. Here, using an in vitro screen of 20000 molecules, we identified a class of compounds with a substituted 1H-pyrrolo[2,3-b]pyridine core which proved to be potent and selective inhibitors of human DGAT2. Of these compounds, H2-003 and -005 exhibited a considerable reduction in TG biosynthesis in HepG2 hepatic cells and 3T3-L1 preadipose cells. These compounds exert DGAT2-specific-inhibitory activity, which was further confirmed in DGAT2- or DGAT1-overexpressing HEK293 cells. In addition, these compounds almost completely abolished lipid droplet formation in 3T3-L1 cells when co-treated with a DGAT1 inhibitor, which was not attained using either a DGAT2 or DGAT1 inhibitor alone. Collectively, we identified two DGAT2 inhibitors, H2-003 and -005. These compounds will aid in DGAT2-related lipid metabolism research as well as in therapeutic development for the treatment of metabolic diseases associated with excessive TG.


Assuntos
Acetatos/química , Acetatos/farmacologia , Diacilglicerol O-Aciltransferase/antagonistas & inibidores , Descoberta de Drogas/métodos , Piridinas/química , Piridinas/farmacologia , Células 3T3-L1 , Animais , Diacilglicerol O-Aciltransferase/metabolismo , Células HEK293 , Células Hep G2 , Humanos , Camundongos
6.
Nat Commun ; 15(1): 676, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38263315

RESUMO

Miniaturized spectrometers have great potential for use in portable optoelectronics and wearable sensors. However, current strategies for miniaturization rely on von Neumann architectures, which separate the spectral sensing, storage, and processing modules spatially, resulting in high energy consumption and limited processing speeds due to the storage-wall problem. Here, we present a miniaturized spectrometer that utilizes a single SnS2/ReSe2 van der Waals heterostructure, providing photodetection, spectrum reconstruction, spectral imaging, long-term image memory, and signal processing capabilities. Interface trap states are found to induce a gate-tunable and wavelength-dependent photogating effect and a non-volatile optoelectronic memory effect. Our approach achieves a footprint of 19 µm, a bandwidth from 400 to 800 nm, a spectral resolution of 5 nm, and a > 104 s long-term image memory. Our single-detector computational spectrometer represents a path beyond von Neumann architectures.

7.
ACS Appl Mater Interfaces ; 16(7): 9495-9505, 2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38334441

RESUMO

Nanodevices based on van der Waals heterostructures have been predicted, and shown, to have unprecedented operational principles and functionalities that hold promise for highly sensitive and selective gas sensors with rapid response times and minimal power consumption. In this study, we fabricated gas sensors based on vertical MoS2/WS2 van der Waals heterostructures and investigated their gas sensing capabilities. Compared with individual MoS2 or WS2 gas sensors, the MoS2/WS2 van der Waals heterostructure gas sensors are shown to have enhanced sensitivity, faster response times, rapid recovery, and a notable selectivity, especially toward NO2. In combination with a theoretical model, we show that it is important to take into account created trapped states (flat bands) induced by the adsorption of gas molecules, which capture charges and alter the inherent built-in potential of van der Waals heterostructure gas sensors. Additionally, we note that the performance of these MoS2/WS2 heterostructure gas sensors could be further enhanced using electrical gating and mechanical strain. Our findings highlight the importance of understanding the effects of altered built-in potentials arising from gas molecule adsorption induced flat bands, thus offering a way to enhance the gas sensing performance of van der Waals heterostructure gas sensors.

8.
Int J Biol Macromol ; 242(Pt 2): 124813, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37172699

RESUMO

We prepared nanocomposite (XG-AVE-Ag/MgO NCs) using the bimetallic Ag/MgO NPs, Aloe vera extract (AVE), and biopolymer (xanthan gum (XG)) to archive a synergetic antibacterial and wound healing activity. The changes in XRD peaks at 20° of XG-AVE-Ag/MgO NCs indicated the XG encapsulation. The XG-AVE-Ag/MgO NCs showed the zeta potential and zeta size of 151.3 ± 3.14 d.nm and -15.2 ± 1.08 mV with a PDI of 0.265 while TEM showed an average size of 61.19 ± 3.89 nm. The EDS confirmed the co-existence of Ag, Mg, carbon, oxygen, and nitrogen in NCs. XG-AVE-Ag/MgO NCs displayed higher antibacterial activity in terms of zone of inhibition, at 15.00 ± 0.12 mm for B. cereus and 14.50 ± 0.85 mm for E. coli. Moreover, NCs exhibited MICs of 2.5 µg/mL for E. coli, and 0.62 µg/mL for B. cereus. The in vitro cytotoxicity and hemolysis assays indicated the non-toxic properties of XG-AVE-Ag/MgO NCs. The higher wound closure activity was observed with the treatment of XG-AVE-Ag/MgO NCs (91.19 ± 1.87 %) compared to the control, untreated group (68.68 ± 3.54 %) at 48 h of incubation. These findings revealed that XG-AVE-Ag/MgO NCs was promising, non-toxic, antibacterial, and wound-healing agent that deserved further in-vivo studies.


Assuntos
Aloe , Nanopartículas Metálicas , Nanopartículas , Óxido de Magnésio/farmacologia , Escherichia coli , Antibacterianos/farmacologia , Cicatrização
9.
ACS Appl Mater Interfaces ; 15(13): 17335-17343, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-36972407

RESUMO

The high surface-to-volume ratio and flatness of mechanically exfoliated van der Waals (vdW) layered materials make them an ideal platform to investigate the Langmuir absorption model. In this work, we fabricated field effect transistor gas sensors, based on a variety of mechanically exfoliated vdW materials, and investigated their electrical field-dependent gas sensing properties. The good agreement between the experimentally extracted intrinsic parameters, such as equilibrium constant and adsorption energy, and theoretically predicted values suggests validity of the Langmuir absorption model for vdW materials. Moreover, we show that the device sensing behavior depends crucially on the availability of carriers, and giant sensitivities and strong selectivity can be achieved at the sensitivity singularity. Finally, we demonstrate that such features provide a fingerprint for different gases to quickly detect and differentiate between low concentrations of mixed hazardous gases using sensor arrays.

10.
Biomater Adv ; 141: 213129, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36191538

RESUMO

This work developed a pH/NIR responsive antibacterial agent (CS-FeNPs) composed of chitosan (CS) and Fe3O4 nanoparticles (FeNPs). CS triggers bacterial attraction through surface charge, while Fe acts as a photothermal agent (PTA). The CS-Fe NPs exhibited antibacterial and antibiofilm activity against both bacteria (G+/G-). However, higher activity was observed against bacteria (G-) due to electrostatic interactions. The CS-FeNPs bind with the bacterial membrane through electrostatic interactions and disturb bacterial cells. Later, in an acidic environment, CS-FeNPs bind with bacterial membrane, and NIR irradiation leads the antibacterial activity. CS-FeNPs exhibited a potential photothermal conversion efficiency (η) of 21.53 %. Thus, it converts NIR irradiation into heat to kill the bacterial pathogen. The CS-FeNPs were found to be less cytotoxic with great antibacterial efficiency on planktonic bacteria and their biofilm, which indicates that they deserve to develop potential and safe treatment strategies for the treatment of bacterial infections.


Assuntos
Quitosana , Antibacterianos/farmacologia , Bactérias , Biofilmes/efeitos da radiação , Quitosana/farmacologia , Nanopartículas Magnéticas de Óxido de Ferro
11.
ACS Nano ; 16(10): 17347-17355, 2022 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-36153977

RESUMO

van der Waals heterojunctions with tunable polarity are being actively explored for more Moore and more-than-Moore device applications, as they can greatly simplify circuit design. However, inadequate control over the multifunctional operational states is still a challenge in their development. Here, we show that a vertically stacked InSe/SnS2 van der Waals heterojunction exhibits type-II band alignment, and its polarity can be tuned by an external electric field and by the wavelength and intensity of an illuminated light source. Moreover, such SnS2/InSe diodes are self-powered broadband photodetectors with good performance. The self-powered performance can be further enhanced significantly with gas adsorption, and the device can be quickly restored to the state before gas injection using a gate voltage pulse. Our results suggest a way to achieve and design multiple functions in a single device with multifield coupling of light, electrical field, gas, or other external stimulants.

12.
Ann Surg ; 253(2): 328-35, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21217520

RESUMO

PURPOSE: Surgical resection provides the only possibility of cure for pancreas cancer. A standard adjuvant approach has not been established. We tested the safety and efficacy of a granulocyte-macrophage colony-stimulating factor (GM-CSF)-based immunotherapy administered in patients with resected pancreatic adenocarcinoma. PATIENTS AND METHODS: A single institution phase II study of 60 patients with resected pancreatic adenocarcinoma was performed. Each immunotherapy treatment consisted of a total of 5 × 108 GM-CSF-secreting cells distributed equally among 3 lymph node regions. The first immunotherapy treatment was administered 8 to 10 weeks after surgical resection. Subsequently, patients received 5-FU based chemoradiation. Patients who remained disease-free after completion of chemoradiotherapy received treatments 2 to 4, each 1 month apart. A fifth and final booster was administered 6 months after the fourth immunotherapy. The primary endpoint was disease free survival and secondary endpoints were overall survival and toxicity, and the induction of mesothelin specific T cell responses. RESULTS: The median disease-free survival is 17.3 months (95% CI, 14.6-22.8) with median survival of 24.8 months (95% CI, 21.2-31.6). The administration of immunotherapy was well tolerated. In addition, the post-immunotherapy induction of mesothelin-specific CD8+ T cells in HLA-A1+ and HLA-A2+patients correlates with disease-free survival. CONCLUSIONS: An immunotherapy approach integrated with chemoradiation is safe and demonstrates an overall survival that compares favorably with published data for resected pancreas cancer. These data suggest additional boost immunotherapies given at regular intervals beyond 1 year postsurgery should be tested in future studies, and provide the rationale for conducting a multicenter phase II study.


Assuntos
Vacinas Anticâncer/uso terapêutico , Carcinoma Ductal Pancreático/terapia , Fator Estimulador de Colônias de Granulócitos e Macrófagos/uso terapêutico , Imunoterapia , Neoplasias Pancreáticas/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos de Neoplasias/imunologia , Vacinas Anticâncer/efeitos adversos , Vacinas Anticâncer/imunologia , Vacinas Anticâncer/efeitos da radiação , Carcinoma Ductal Pancreático/imunologia , Carcinoma Ductal Pancreático/mortalidade , Linhagem Celular Tumoral/metabolismo , Linhagem Celular Tumoral/efeitos da radiação , Terapia Combinada , Intervalo Livre de Doença , Feminino , Proteínas Ligadas por GPI/imunologia , Fator Estimulador de Colônias de Granulócitos e Macrófagos/metabolismo , Humanos , Hipersensibilidade Tardia/imunologia , Masculino , Mesotelina , Pessoa de Meia-Idade , Neoplasias Pancreáticas/imunologia , Neoplasias Pancreáticas/mortalidade , Taxa de Sobrevida , Linfócitos T/imunologia , Transfecção
13.
Pharmaceuticals (Basel) ; 14(8)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34451869

RESUMO

Juglans mandshurica Maxim., a traditional folk medicinal plant, is widely distributed in Korea and China. In our previous study, we isolated a new phenylpropanoid compound, 4-((1R,2R)-3-hydroxy-1-(4-hydroxyphenyl)-1-methoxypropan-2-yl)-2-methoxyphenol (HHMP), from J. mandshurica. In the present study, we evaluated the anti-inflammatory activity of HHMP on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and zebrafish larvae. HHMP significantly inhibited LPS-induced nitric oxide (NO) and prostaglandin E2 production in a dose-dependent manner. Moreover, HHMP treatment considerably suppressed LPS-induced expression of inducible nitric oxide synthase and cyclooxygenase-2. We also demonstrated the mechanisms of HHMP inhibition of inflammatory responses in LPS-stimulated RAW 264.7 cells via Western blot analysis and immunofluorescence staining. Furthermore, HHMP significantly inhibited NO production in LPS-stimulated zebrafish larvae. Consequently, we established that HHMP significantly inhibited the LPS-induced activation of NF-κB and MAPK and the nuclear translocation of p65 in RAW 264.7 cells. Taken together, our findings demonstrate the effect of HHMP on LPS-induced inflammatory responses in vitro and in vivo, suggesting its potential to be used as a natural anti-inflammatory agent.

14.
Chin J Integr Med ; 27(4): 273-279, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33759044

RESUMO

OBJECTIVE: To demonstrate the anti-inflammatory activity of Brassica napus L. hydrosols (BNH) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. METHODS: Composition analysis of BNH was conducted via gas chromatography-mass spectrometry after BNH were extracted. The nitric oxide (NO) production was measured using the Griess assay. Prostaglandin E2 (PGE2) production was evaluated with enzyme-linked immunosorbent assay. The effects of BNH on LPS-induced pro-inflammatory enzymes including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were evaluated using Western blot analysis. Furthermore, phosphorylation of nuclear factor-kappa B (NF-κB) and nuclear translocation of NF-κB p65 were evaluated with Western blot analysis and immunofluorescence staining, respectively. RESULTS: Compared with LPS-stimulated cells, BNH markedly decreased the generation of NO and PGE2 in LPS-stimulated RAW 264.7 cells (P<0.01 or P<0.05). Moreover, BNH inhibited protein levels of iNOS and COX-2 (P<0.01). Phosphorylation of NF-κB and nuclear translocation of NF-κB p65 was significantly inhibited by BNH (P<0.01 or P<0.05). CONCLUSION: The anti-inflammatory activities of BNH were mediated via blockage of the NF-κB signaling pathways in LPS-stimulated RAW 264.7 cells.


Assuntos
Brassica napus , Animais , Brassica napus/metabolismo , Ciclo-Oxigenase 2/metabolismo , Inflamação/tratamento farmacológico , Lipopolissacarídeos , Camundongos , NF-kappa B/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Células RAW 264.7
15.
Phytomedicine ; 92: 153695, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34500300

RESUMO

BACKGROUND: Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a significant pathogenic factor in Down syndrome (DS), wherein DYRK1A is overexpressed by 1.5-fold because of trisomy of human chromosome 21. Thus, DYRK1A inhibition is considered a therapeutic strategy to modify the disease. PURPOSE: This study aims to identify a novel DYRK1A inhibitor and validate its therapeutic potential in DS-related pathological conditions. STUDY DESIGN: In order to identify a novel DYRK1A inhibitor, we carried out two-step screening: a structure-based virtual screening of > 300,000 chemical library (first step) and cell-based nuclear factor of activated T-cells (NFAT)-response element (RE) promoter assay (second step). Primary hits were evaluated for their DYRK1A inhibitory activity using in vitro kinase assay and Tau phosphorylation in mammalian cells. Confirmed hit was further evaluated in pathological conditions including DYRK1A-overexpressing fibroblasts, flies, and mice. RESULTS: We identified aristolactam BIII, a natural product derived from herbal plants, as a novel DYRK1A inhibitor. It potently inhibited the kinase activity of DYRK1A in vitro (IC50 = 9.67 nM) and effectively suppressed DYRK1A-mediated hyperphosphorylation of Tau in mammalian cells. Aristolactam BIII rescued the proliferative defects of DYRK1A transgenic (TG) mouse-derived fibroblasts and neurological and phenotypic defects of DS-like Drosophila models. Oral administration of aristolactam BIII acutely suppressed Tau hyperphosphorylation in the brain of DYRK1A TG mice. In the open field test, aristolactam BIII significantly ameliorated the exploratory behavioral deficit of DYRK1A TG mice. CONCLUSION: Our work revealed that aristolactam BIII as a novel DYRK1A inhibitor rescues DS phenotypes in cells and in vivo and suggested its therapeutic potential for the treatment of DYRK1A-related diseases.


Assuntos
Síndrome de Down , Animais , Encéfalo , Síndrome de Down/tratamento farmacológico , Camundongos , Camundongos Transgênicos , Fenótipo , Fosforilação
16.
Chem ; 6(6): 1408-1419, 2020 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-32864504

RESUMO

Tumor recurrence as a result of therapy-induced nuclear DNA lesions is a major issue in cancer treatment. Currently, only a few examples of potentially non-genotoxic drugs have been reported. Mitochondrial re-localization of ciprofloxacin, one of the most commonly prescribed synthetic antibiotics, is reported here as a new approach. Conjugating ciprofloxacin to a triphenyl phosphonium group (giving lead Mt-CFX), is used to enhance the concentration of ciprofloxacin in the mitochondria of cancer cells. The localization of Mt-CFX to the mitochondria induces oxidative damage to proteins, mtDNA, and lipids. A large bias in favor of mtDNA damage over nDNA was seen with Mt-CFX, contrary to classic cancer chemotherapeutics. Mt-CFX was found to reduce cancer growth in a xenograft mouse model and proved to be well tolerated. Mitochondrial relocalization of antibiotics could emerge as a useful approach to generating anticancer leads that promote cell death via the selective induction of mitochondrially-mediated oxidative damage.

17.
IUCrJ ; 7(Pt 5): 913-919, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32939283

RESUMO

Charge density waves spontaneously breaking lattice symmetry through periodic lattice distortion, and electron-electron and electron-phonon inter-actions, can lead to a new type of electronic band structure. Bulk 2H-TaS2 is an archetypal transition metal dichalcogenide supporting charge density waves with a phase transition at 75 K. Here, it is shown that charge density waves can exist in exfoliated monolayer 2H-TaS2 and the transition temperature can reach 140 K, which is much higher than that in the bulk. The degenerate breathing and wiggle modes of 2H-TaS2 originating from the periodic lattice distortion are probed by optical methods. The results open an avenue to investigating charge density wave phases in two-dimensional transition metal dichalcogenides and will be helpful for understanding and designing devices based on charge density waves.

18.
Sci Rep ; 10(1): 9849, 2020 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-32555303

RESUMO

Dual-specificity tyrosine phosphorylation-regulated kinase 1 A (DYRK1A) is essential for human development, and DYRK1A haploinsufficiency is associated with a recognizable developmental syndrome and variable clinical features. Here, we present a patient with DYRK1A haploinsufficiency syndrome, including facial dysmorphism, delayed motor development, cardiovascular system defects, and brain atrophy. Exome sequencing identified a novel de novo heterozygous mutation of the human DYRK1A gene (c.1185dup), which generated a translational termination codon and resulted in a C-terminally truncated protein (DYRK1A-E396ter). To study the molecular effect of this truncation, we generated mammalian cell and Drosophila models that recapitulated the DYRK1A protein truncation. Analysis of the structure and deformation energy of the mutant protein predicted a reduction in protein stability. Experimentally, the mutant protein was efficiently degraded by the ubiquitin-dependent proteasome pathway and was barely detectable in mammalian cells. More importantly, the mutant kinase was intrinsically inactive and had little negative impact on the wild-type protein. Similarly, the mutant protein had a minimal effect on Drosophila phenotypes, confirming its loss-of-function in vivo. Together, our results suggest that the novel heterozygous mutation of DYRK1A resulted in loss-of-function of the kinase activity of DYRK1A and may contribute to the developmental delay observed in the patient.


Assuntos
Deficiências do Desenvolvimento/enzimologia , Deficiências do Desenvolvimento/genética , Heterozigoto , Mutação , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Animais , Drosophila melanogaster , Feminino , Células HEK293 , Humanos , Lactente , Masculino , Simulação de Dinâmica Molecular , Linhagem , Conformação Proteica em Folha beta , Domínios Proteicos , Proteínas Serina-Treonina Quinases/química , Proteínas Tirosina Quinases/química , Quinases Dyrk
19.
RSC Adv ; 10(3): 1580-1587, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-35494696

RESUMO

Monolayer MoSe2 is a transition metal dichalcogenide with a narrow bandgap, high optical absorbance and large spin-splitting energy, giving it great promise for applications in the field of optoelectronics. Producing monolayer MoSe2 films in a reliable and scalable manner is still a challenging task as conventional chemical vapor deposition (CVD) or exfoliation based techniques are limited due to the small domains/nanosheet sizes obtained. Here, based on NaCl assisted CVD, we demonstrate the simple and stable synthesis of sub-millimeter size single-crystal MoSe2 monolayers with mobilities ranging from 38 to 8 cm2 V-1 s-1. The average mobility is 12 cm2 V-1 s-1. We further determine that the optical responsivity of monolayer MoSe2 is 42 mA W-1, with an external quantum efficiency of 8.22%.

20.
Phytomedicine ; 65: 153089, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31563042

RESUMO

BACKGROUND: Spinal muscular atrophy (SMA) is a rare neuromuscular disease and a leading genetic cause of infant mortality. SMA is caused primarily by the deletion of the survival motor neuron 1 (SMN1) gene, which leaves the duplicate gene SMN2 as the sole source of SMN protein. The splicing defect (exon 7 skipping) of SMN2 leads to an insufficient amount of SMN protein. Therefore, correcting this SMN2 splicing defect is considered to be a promising approach for the treatment of SMA. PURPOSE: This study aimed to identify active compounds and extracts from plant resources to rescue SMA phenotypes through the correction of SMN2 splicing. STUDY DESIGN: Of available plant resources, candidates with SMA-related traditional medicine information were selected for screening using a robust luciferase-based SMN2 splicing reporter. Primary hits were further evaluated for their ability to correct the splicing defect and resultant increase of SMN activity in SMA patient-derived fibroblasts. Confirmed hits were finally tested to determine the beneficial effects on the severe Δ7 SMA mouse. METHODS: SMN2 splicing was analyzed using a luciferase-based SMN2 splicing reporter and subsequent RT-PCR of SMN2 mRNAs. SMA phenotypes were evaluated by the survival, body weights, and righting reflex of Δ7 SMA mice. RESULTS: In a screen of 492 selected plant extracts, we found that Brucea javanica extract and its major constituent Bruceine D have SMN2 splicing-correcting activity. Their ability to correct the splicing defect and the resulting increased SMN activity were further confirmed in SMA fibroblasts. Importantly, both B. javanica and Bruceine D noticeably improved the phenotypic defects, especially muscle function, in SMA mice. Reduced expression of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) contributed to the correction of splicing by B. javanica. CONCLUSION: Our work revealed that B. javanica and Bruceine D correct the SMN2 splicing defect and improve the symptoms of SMA in mice. These resources will provide another possibility for development of a plant-derived SMA drug candidate.


Assuntos
Brucea/química , Atrofia Muscular Espinal/tratamento farmacológico , Extratos Vegetais/farmacologia , Quassinas/farmacologia , Processamento Alternativo , Animais , Linhagem Celular , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos/métodos , Éxons , Humanos , Camundongos Transgênicos , Atrofia Muscular Espinal/genética , Extratos Vegetais/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína 2 de Sobrevivência do Neurônio Motor/genética
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