Membrane-associated histidine kinases (HKs) in two-component systems respond to environmental stimuli by autophosphorylation and phospho-transfer. HK typically contains a periplasmic sensor domain that regulates the cytoplasmic kinase domain through a conserved cytoplasmic linker. How signal is transduced from the ligand-binding site across the membrane barrier remains unclear. Here, we analyse two linker regions of a typical HK, DctB. One region connects the first transmembrane helix with the periplasmic Per-ARNT-Sim domains, while the other one connects the second transmembrane helix with the cytoplasmic kinase domains. We identify a leucine residue in the first linker region to be essential for the signal transduction and for maintaining the delicate balance of the dimeric interface, which is key to its activities. We also show that the other linker, belonging to the S-helix coiled-coil family, plays essential roles in signal transduction inside the cell. Furthermore, by combining mutations with opposing activities in the two regions, we show that these two signalling transduction elements are integrated to produce a combined effect on the final activity of DctB.
The membrane protein tyrosine phosphatase receptor U (PTPRU) has been shown to function as a negative regulator of adhesion and proliferation in certain cancer cell types, primarily through its dephosphorylation of ?-catenin and inhibition of subsequent downstream signaling. In the present study, we set out to characterize the role of PTPRU in glioma and found that, while the expression of full-length PTPRU protein is low in these tumors, a number of non-full-length PTPRU isoforms are highly expressed. Among these isoforms, one in particular is localized to the nucleus, and its expression is increased in glioma tissues in a manner that positively correlates with malignancy grade. Short hairpin RNA knockdown of endogenous PTPRU in human and rat glioma cell lines suppressed proliferation, survival, invasion, migration, adhesion and vasculogenic tube formation in vitro, as well as intracranial tumor progression in vivo. In addition, knocking down PTPRU reduced tyrosine phosphorylation (pY) and transcriptional activity of ?-catenin, and we were able to specifically rescue the cell migration defect by expressing a LEF1-?-catenin fusion protein in PTPRU-depleted cells. PTPRU knockdown also led to increased tyrosine pY of the E3 ubiquitin ligase c-Cbl and to the destabilization of several focal adhesion proteins. Taken together, our findings demonstrate that endogenous PTPRU promote glioma progression through their effect on ?-catenin and focal adhesion signaling.
The shape anisotropy of the nanostructured nanorattles is one of the key factors that affect their microwave absorption performance. In the present study, the microwave absorption performance of ellipsoidal Fe3O4@CuSiO3 nanorattles with different aspect ratios was investigated. Results demonstrated that the ellipsoidal nanorattles with the aspect ratio of 3-4 exhibited about 20% enhancement of microwave absorption intensity compared with spherical Fe3O4@CuSiO3. Generally, as the aspect ratio increased from 2.0 to 3.5, the microwave absorption peak was enhanced monotonously from -20 dB to -30 dB. It was found that the ellipsoidal nanorattles with larger aspect ratio exhibited higher coercivity and double resonance peaks of the real part of complex permittivity, resulting in the improvement of microwave absorption performance. Our research gives insights into the understanding of the anisotropic effect of nanorattles on microwave absorption performance.
Ubiquitin-specific protease 22 (USP22), a newly discovered member of ubiquitin hydrolase family, exhibits a critical function in cell cycle progression and tumorigenesis. The forkhead box M1 (FoxM1) transcription factor plays a crucial role in cell proliferation, differentiation and transformation. However, the expression and functions of USP22 in pancreatic ductal adenocarcinoma (PDA) and whether FoxM1 is involved in USP22-mediated cell cycle regulation have not been studied. We examined the expression of USP22 and FoxM1 in 136 stage II PDA tissues by immunohistochemistry. Clinical significance was analyzed by multivariate Cox regression analysis, Kaplan-Meier curves and log-rank test. RT-PCR, western blot analysis, luciferase and immunofluorescence assays were used to investigate the molecular function of USP22 and FoxM1 in PDA fresh tissues and cell lines. USP22 and FoxM1 were significantly upregulated in PDA tissues compared with the paired normal carcinoma-adjacent tissues. A statistical correlation was observed between USP22 and FoxM1 expression. The expression of USP/FoxM1 and co-expression of both factors correlated with tumor size, lymph node metastasis and overall survival. Multivariate Cox regression analysis revealed that the expression of USP22/FoxM1, especially the co-expression of both factors, is an independent, unfavorable prognostic factor. USP22 overexpression is accompanied by an increase in FoxM1 expression and USP22 increases FoxM1 expression to promote G1/S transition and cell proliferation through promoting ?-catenin nuclear translocation in PDA cell lines. USP22 promotes the G1/S phase transition by upregulating FoxM1 expression via promoting ?-catenin nuclear localization. USP22 and FoxM1 may act as prognostic markers and potential targets for PDA.
Epithelial-mesenchymal transition (EMT) contributes to the occurrence and development of tumors, particularly to the promotion of tumor invasion and metastasis. As a newly discovered ubiquitin hydrolase family member, USP22 plays a key role in the malignant transformation of tumors and the regulation of the cell cycle. However, recent studies on USP22 have primarily focused on its role in cell cycle regulation, and the potential mechanism underlying the promotion of tumor invasion and metastasis by abnormal USP22 expression has not been reported. Our studies revealed that the overexpression of USP22 in PANC-1 cells promoted Ezrin redistribution and phosphorylation and cytoskeletal remodeling, upregulated expression of the transcription factors Snail and ZEB1 to promote EMT, and increased cellular invasion and migration. In contrast, blockade of USP22 expression resulted in the opposite effects. In addition, the focal adhesion kinase (FAK) signaling pathway was shown to play a key role in the process of EMT induction in PANC-1 cells by USP22. Thus, the present study suggests that USP22 acts as a regulatory protein for EMT in pancreatic cancer, which may provide a new approach for the targeted therapy of pancreatic cancer.
The epithelial-mesenchymal transition (EMT) is one of the main mechanisms contributing to the onset of cancer metastasis, and has proven to be associated with breast cancer progression. SHON is a novel secreted hominoid-specific protein we have previously identified; it is specifically expressed in all human cancer cell lines tested and is oncogenic for human mammary carcinoma cells. Here, we show that ectopic overexpression of SHON in immortalized human mammary epithelial cells is sufficient for cells to acquire the mesenchymal traits, as well as the enhanced cell migration and invasion, along with the epithelial stem cell properties characterized by increased CD44(high) /CD24(low) subpopulation and mammosphere-forming ability. Moreover, we demonstrate that SHON positively activates the autocrine transforming growth factor-? (TGF-?) pathway to contribute to EMT, while SHON itself is induced by TGF-? in mammary epithelial cells. These data are in favor of a SHON-TGF?-SHON-positive feedback loop that regulates EMT program in breast cancer progression. Finally, examination of the human clinic breast cancer specimens reveals that tumor cells may extracellularly release SHON protein to promote the cancerization of surrounding cells. Together, our findings define an important function of SHON in regulation of EMT via TGF-? signaling, which is closely associated with the invasive subtypes of human breast cancer.
Nek2 is a serine/threonine kinase that has a critical role in mitosis during the cell division process. Despite its importance in centrosome regulation and spindle formation, no direct binders are reported between human pancreatic cancer and Nek2 protein. Our aim in studying Nek2 expression and survival in PDA patients is to determine whether Nek2 is a valuable prognostic factor in PDA tumorigenesis. We found that Nek2 mRNA was elevated in PDA tissues. A high level of expression of Nek2 was significantly correlated with histological differentiation (P=0.042), lymph node metastasis (P=0.003) and tumor stage (P=0.001). Patients with a high Nek2 expression had a significantly worse overall survival (OS) than those patients with low Nek2 expression (P=0.002). Univariate and multivariate analysis revealed that high expression of Nek2 could serve as an independent predictor of poor prognosis. These results indicate that Nek2 could be a promising prognostic molecular marker and an attractive therapeutic target for PDA.
Monodispersed manganese oxide (Mn1-xCox)3O4 (0 ? x ? 0.5) nanoparticles, less than 10 nm size, are respectively synthesized via a facile thermolysis method at a rather low temperature, ranging from 90 to 100 °C, without any inertia gas for protection. The influences of the Co dopant content on the critical reaction temperature required for the nanoparticle formation, electronic band structures, magnetic properties, and the microwave absorption capability of (Mn1-xCox)3O4 are comprehensively investigated by means of both experimental and theoretical approaches including powder X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), super conductivity quantum interference device (SQUID) examination, and first-principle simulations. Co is successfully doped into the Mn atomic sites of the (Mn1-xCox)3O4 lattice, which is further confirmed by EELS data acquired from one individual nanoparticle. Therefore, continuous solid solutions of well-crystallized (Mn1-xCox)3O4 products are achieved without any impurity phase or phase separation. With increases in the Co dopant concentration x from 0 to 0.5, the lattice parameters change systemically, where the overall saturation magnetization at 30 K increases due to the more intense coupling of the 3d electrons between Mn and Co, as revealed by simulations. The microwave absorption properties of the (Mn1-xCox)3O4 nanoparticles are examined between 2 and 18 GHz. The maximum absorption peak -11.0 dB of the x = 0 sample is enhanced to -11.5 dB for x = 0.2, -12.7 dB for x = 0.25, -15.6 dB for x = 0.33, and -24.0 dB for x = 0.5 respectively, suggesting the Co doping effects. Our results might provide novel insights into the understanding of the influences of metallic ion doping on the electromagnetic properties of metallic oxide nanomaterials.
In this paper, we report the facile synthesis of ultrathin barium titanate (BaTiO3) nanowires with gram-level yield via a simple one-step hydrothermal treatment. Our BaTiO3 nanowires have unique features: single crystalline, uniform size distribution and ultra high aspect ratio. The synergistic effects including both Ostwald ripening and cation exchange reaction are responsible for the growth of the ultrathin BaTiO3 nanowires. The microwave absorption capability of the ultrathin BaTiO3 nanowires is improved compared to that of BaTiO3 nanotorus,1 with a maximum reflection loss as high as -24.6 dB at 9.04 GHz and an absorption bandwidth of 2.4 GHz (<-10 dB). Our method has some novel advantages: simple, facile, low cost and high synthesis yield, which might be developed to prepare other ferroelectric nanostructures. The strong microwave absorption property of the ultrathin BaTiO3 nanowires indicates that these nanowires could be used as promising materials for microwave-absorption and stealth camouflage techniques.
Yolk-shell microspheres with magnetic Fe3O4 cores and hierarchical copper silicate shells have been successfully synthesized by combining the versatile sol-gel process and hydrothermal reaction. Various yolk-shell microspheres with different core size and shell thickness can be readily synthesized by varying the experimental conditions. Compared to pure Fe3O4, the as-synthesized yolk-shell microspheres exhibit significantly enhanced microwave absorption properties in terms of both the maximum reflection loss value and the absorption bandwidth. The maximum reflection loss value of these yolk-shell microspheres can reach -23.5 dB at 7 GHz with a thickness of 2 mm, and the absorption bandwidths with reflection loss lower than -10 dB are up to 10.4 GHz. Owing to the large specific surface area, high porosity, and synergistic effect of both the magnetic Fe3O4 cores and hierarchical copper silicate shells, these unique yolk-shell microspheres may have the potential as high-efficient absorbers for microwave absorption applications.
A facile and efficient strategy for the synthesis of hierarchical yolk-shell microspheres with magnetic Fe3O4 cores and dielectric TiO2 shells has been developed. Various Fe3O4@TiO2 yolk-shell microspheres with different core sizes, interstitial void volumes, and shell thicknesses have been successfully synthesized by controlling the synthetic parameters. Moreover, the microwave absorption properties of these yolk-shell microspheres, such as the complex permittivity and permeability, were investigated. The electromagnetic data demonstrate that the as-synthesized Fe3O4@TiO2 yolk-shell microspheres exhibit significantly enhanced microwave absorption properties compared with pure Fe3O4 and our previously reported Fe3O4@TiO2 core-shell microspheres, which may result from the unique yolk-shell structure with a large surface area and high porosity, as well as synergistic effects between the functional Fe3O4 cores and TiO2 shells.
The zinc finger transcription factor ZFX functions as an important regulator of self-renewal in multiple stem cell types, as well as a sex determinant of mammals. Moreover, ZFX expression is abnormally elevated in several cancers, and correlates with malignancy grade. To investigate its role in the pathogenesis of gliomas, we used lentivirus-mediated RNA interference (RNAi) to knockdown ZFX expression in human glioma cell lines. Our results demonstrate that ZFX plays a crucial role in glioma proliferation and survival, confirming recent reports. We also show for the first time that ZFX knockdown decreases the in vivo growth potential of U87 glioma xenografts in both subcutaneous and intracranial models in nude mice. We conclude that lentivirus-mediated RNAi targeting of ZFX may serve as a promising strategy for glioma therapy.
Uniform BaTiO(3) nano-torus with either concave or epicenter holes were synthesized by a hydrothermal method. Experimental observations indicated that the BaTiO(3) nano-torus with an average diameter ranging from 50 to 100 nm was of tetragonal phases at room temperature. The morphology of the BaTiO(3) nano-torus depends on the shape of the original titanium dioxide precursor and reaction time. The microwave absorption properties of both the BaTiO(3) nano-torus and the BaTiO(3) solid nanoparticles were examined between 2-18 GHz microwave frequency bands. The maximum reflection loss of the BaTiO(3) nano-torus reached -28.38 dB at 11.36 GHz, compared to that of -12.87 dB at 16.32 GHz of the BaTiO(3) solid nanoparticles. The nearly 120% enhancement of the reflection loss in the range of 8-12 GHz was probably attributed to the hollow volume inside the BaTiO(3) nano-torus which might contribute more dissipation and scattering effects of the microwave. Growth mechanisms of the BaTiO(3) nano-torus were also investigated by changing both the reaction time from 0.5 h to 48 h and the reactants concentration ratio between Ba(OH)(2)·8H(2)O and titanium dioxide. Both an "in situ transformation" mechanism and a "dissolution-precipitation" growth mode were proposed.
Fucosyltransferase IV (FUT4) is an essential enzyme that catalyzes the synthesis of difucosylated oligosaccharide LeY which is overexpressed in the cancers derived from the epithelial tissues. Our previous studies have shown that FUT4 overexpression promotes A431 cell proliferation through the MAPK and PI3K/Akt signaling pathways, but the relationship between FUT4 and apoptosis remained unclear. Here, we investigated the effect of FUT4 overexpression on cyclophosphamide (CPA)-induced apoptosis in A431 cells. Western blot analysis showed that FUT4 overexpression decreased expression of Bax, Caspase 3, and PARP proteins, and increased anti-apoptotic Bcl-2 protein in A431 cells. The anti-apoptosis effect of FUT4 was confirmed both by Annexin-V/PI and JC-1 assays. The results showed that FUT4 overexpression up-regulated phosphorylation of ERK1/2 and Akt which was inhibited by CPA in dose-dependent manner. By blocking the ERK/MAPK and PI3K/Akt pathways with specific inhibitors, we demonstrated that these two pathways were required in mediating the anti-apoptosis effect of FUT4. We concluded that FUT4 inhibited cell apoptosis induced by CPA through decreasing the expression of apoptotic proteins Bax, Caspase 3, and PARP and increasing the expression of anti-apoptotic protein Bcl-2 via the ERK/MAPK and PI3K/Akt signaling pathways in A431 cells.
Highly luminescent water-soluble CdTe quantum dots were synthesized with an electrogenerated precursor. The size, morphology, optical properties as well as fluorescence stability were characterized by transmission electron microscope, high-resolution transmission electron microscope, powder X-ray diffraction, UV-vis-NIR spectrophotometer, and fluorescence spectrophotometer. The results show that the CdTe QDs with diameter ranging from 2.0 nm to 3.5 nm have good crystallizability, high quantum yield and favorable fluorescence stability. Moreover, the CdTe QDs demonstrate temperature-dependent reversible PL intensity variations at moderate temperatures above room temperature. It is also found that the QDs with different sizes possess different sensitivity to the temperature. All the studies indicate that the CdTe QDs are expected to be promising candidates for a variety of biological and biomedical applications.
Highly magnetic luminescent alginate-templated composite microparticles were successfully synthesized by a novel process combining emulsification and layer-by-layer self-assembly techniques. The composite microparticles were characterized by ?-potential analyzer, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscope, fluorescence spectrophotometer, and vibrating sample magnetometer. Experimental observations indicated that the composite microparticles had excellent magnetic properties, and its photoluminescence could be precisely controlled by varying the number of deposition cycles of polyelectrolytes and CdTe/polyelectrolyte multilayers. Moreover, the composite microparticles could be heated up in a high-frequency magnetic field and demonstrated linear temperature-dependent photoluminescence over the range from room temperature to hyperthermia temperature. The composite microparticles are expected to be promising candidates for biomedical applications, such as immunoassay, biosensing and imaging, and cancer diagnosis and treatment.
Sinorhizobium meliloti DctB is a typical transmembrane sensory histidine kinase, which senses C(4)-dicarboxylic acids (DCA) and regulates the expression of DctA, the DCA transporter. We previously reported the crystal structures of its periplasmic sensory domain (DctBp) in apo and succinate-bound states, and these structures showed dramatic conformational changes at dimeric level. Here we show a ligand-induced dimeric switch in solution and a strong correlation between DctBps dimerization states and the in vivo activities of DctB. Using site-directed mutagenesis, we identify important determinants for signal perception and transduction. Specifically, we show that the ligand-binding pocket is essential for DCA-induced on activity of DctB. Mutations at different sections of DctBps dimerization interface can lock full-length DctB at either on or off state, independent of ligand binding. Taken together, these results suggest that DctBps signal perception and transduction occur through a ligand-induced dimeric switch, in which the changes in the dimeric conformations upon ligand binding are responsible for the signal transduction in DctB.
Most cases of hepatocellular carcinoma occur in the Asia-Pacific region, where chronic hepatitis B infection is an important aetiological factor. Assessing the efficacy and safety of new therapeutic options in an Asia-Pacific population is thus important. We did a multinational phase III, randomised, double-blind, placebo-controlled trial to assess the efficacy and safety of sorafenib in patients from the Asia-Pacific region with advanced (unresectable or metastatic) hepatocellular carcinoma.
In this paper, we investigated the feasibility and effect of a novel combination therapy of magnetic nanoparticles (MNPs) hyperthermia with anticancer drugs for solid malignancies using doxorubicin-loaded alginate-templated magnetic microcapsules (DAMMs) in an animal liver cancer model. Firstly, DAMMs containing 18 nm gamma-Fe2O3 with doxorubicin (Dox) were synthesized and characterized. Then, the particular behavior of Dox release under external alternating current magnetic filed (ACMF) was tested in vitro. Moreover, to obtain accurate thermotherapy, the dose of DAMMs and temperature rise were computed by Hyperthermia treatment plan (HTP) and a fiber optic temperature sensor (FOTS) was used to monitor the temperature rise during treatments on VX-2 liver tumor-bearing rabbits. Furthermore, the therapeutic effect was studied by histopathological examinations and animal survival. The results showed that ACMF can induce Dox fast release during the treatment and the high MNPs content of DMMAs guaranteed the temperature rise for hyperthermia in tumors. The rabbits bearing VX-2 tumors in the magnetic hyperthermia using DMMAs group gained the most tumor necrosis and survival time. It was indicated that DAMMs-based magnetic hyperthermia could be a feasible and effective remedy which could be targeted at liver tumors by dual effects of hyperthermia and chemotherapy.
Multifunctional composite microspheres with spinel Fe(3)O(4) cores and anatase TiO(2) shells (Fe(3)O(4)@TiO(2)) are synthesized by combining a solvothermal reaction and calcination process. The size, morphology, microstructure, phase purity, and magnetic properties are characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, selected-area electron diffraction, electron energy loss spectroscopy, powder X-ray diffraction, and superconducting quantum interference device magnetometry. The results show that the as-synthesized microspheres have a unique morphology, uniform size, good crystallinity, favorable superparamagnetism, and high magnetization. By varying the experimental conditions such as Fe(3)O(4) size and concentration, microspheres with different core sizes and shell thickneses can be readily synthesized. Furthermore, the microwave absorption properties of these microspheres are investigated in terms of complex permittivity and permeability. By integration of the chemical composition and unique structure, the Fe(3)O(4)@TiO(2) microspheres possess lower reflection loss and a wider absorption frequency range than pure Fe(3)O(4). Moreover, the electromagnetic data demonstrate that Fe(3)O(4@TiO(2) microspheres with thicker TiO(2) shells exhibit significantly enhanced microwave absorption properties compared to those with thinner TiO(2) shells, which may result from effective complementarities between dielectric loss and magnetic loss. All the results indicate that these Fe(3)O(4)@TiO(2) microspheres may be attractive candidate materials for microwave absorption applications.
Enhanced fucosyltransferase IV (FUT4) expression correlates with increased tumor malignancy in many carcinomas. However, little is known about the regulation of FUT4 expression, and whether FUT4 expression is influenced by the methylation status of the FUT4 promoter is unclear. In this study, we demonstrated that FUT4 expression is negatively correlated with the methylation degree of a CpG island in the FUT4 promoter, suggesting that the methylation status of FUT4 promoter regulates the expression of FUT4. The results indicate that manipulating the methylation status of the FUT4 promoter to regulate FUT4 expression may be a novel approach in the treatment of malignant tumors.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.