Substrate Stiffness Affects Endothelial Cell Junctions and MAPK Signaling Pathway

Vascular homeostasis is critical for maintaining normal vascular structure and function. Aging is an irreversible trigger of vascular sclerosis, which causes structural and functional damage to blood vessels, leading to severe atherosclerosis. Endothelial cells (ECs) can respond to mechanical stimuli from the extracellular matrix, causing disruption of endothelial barrier function and activating signaling pathways to regulate cellular behavior under pathological conditions. In this paper, we investigated the effect of substrate stiffness on endothelial cell junctions, and the activation of mitogen-activated protein kinase (MAPK) signaling pathways. An in vitro stiffness model was established using polyacrylamide hydrogels of 1 kPa, 20 kPa and 100 kPa. By transcriptome analysis, we found that the cell-cell junction, cadherin binding, cytoskeleton and classical signaling pathways such as MAPK and Rho GTPase of endothelial cells were regulated by substrate stiffness. The expression of cell junction-related molecules TJP1, TJP2, JAM3 and JCAD was also found to be reduced at higher stiffness. The MAPK signaling pathway-related molecules MAP2K3, MAP2K7, MAP3K3, MAP3K6, MAPK3, MAPK7 were upregulated with increased stiffness. qRT-PCR analysis showed that the gene expression of JCAD was reduced with increased stiffness. Immunofluorescence staining of VE-cadherin indicated that the total fluorescence level of VE-cadherin decreased significantly with increased stiffness, and stiffness impaired the cell-cell junction with increased punctuation and discontinuity. Western blotting analysis confirmed that the protein expression ratio of pp38MAPK/p38MAPK increased with stiffness. Our research suggested that substrate stiffness played an important role in regulating endothelial cell integrity and MAPK signaling pathway.

Wnt4 increases the thickness of the epidermis in burn wounds by activating canonical Wnt signalling and decreasing the cell junctions between epidermal cells

Background:Burn wound healing is a complex process and the role of Wnt ligands varies in this process.Whether and how Wnt4 functions in burn wound healing is not well understood.In this study,we aim to reveal the effects and potential mechanisms of Wnt4 in burn wound healing.Methods:First,the expression of Wnt4 during burn wound healing was determined by immunoflu-orescence,Western blotting and qPCR.Then,Wnt4 was overexpressed in burn wounds.The healing rate and healing quality were analysed by gross photography and haematoxyline and eosin staining.Collagen secretion was observed by Masson staining.Vessel formation and fibroblast distribution were observed by immunostaining.Next,Wnt4 was knocked down in HaCaT cells.The migration of HaCaT cells was analysed by scratch healing and transwell assays.Next,the expression ofβ-catenin was detected by Western blotting and immunofluorescence.The binding of Frizzled2 and Wnt4 was detected by coimmunoprecipitation and immunofluorescence.Finally,the molecular changes induced by Wnt4 were analysed by RNA sequencing,immunofluorescence,Western blotting and qPCR in HaCaT cells and burn wound healing tissues.Results:The expression of Wnt4 was enhanced in burn wound skin.Overexpression of Wnt4 in burn wound skin increased the thickness of epidermis.Collagen secretion,vessel formation and fibroblast distribution were not significantly impacted by Wnt4 overexpression.When Wnt4 was knocked down in HaCaT cells,the ratio of proliferating cells decreased,the ratio of apoptotic cells increased and the ratio of the healing area in the scratch healing assay to the number of migrated cells in the transwell assay decreased.The nuclear translocation ofβ-catenin decreased in shRNA of Wnt4 mediated by lentivirus-treated HaCaT cells and increased in Wnt4-overexpressing epidermal cells.RNA-sequencing analysis revealed that cell junction-related signalling pathways were significantly impacted by Wnt4 knockdown.The expression of the cell junction proteins was decreased by the overexpression of Wnt4.Conclusions:Wnt4 promoted the migration of epidermal cells.Overexpression of Wnt4 increased the thickness of the burn wound.A potential mechanism for this effect is that Wnt4 binds with Frizzled2 and increases the nuclear translocation ofβ-catenin,thus activating the canonical Wnt signalling pathway and decreasing the cell junction between epidermal cells.

Patient-derived induced pluripotent stem cells with a MERTK mutation exhibit cell junction abnormalities and aberrant cellular differentiation potential

BACKGROUND Human induced pluripotent stem cell(hiPSC)technology is a valuable tool for generating patient-specific stem cells,facilitating disease modeling,and invest-igating disease mechanisms.However,iPSCs carrying specific mutations may limit their clinical applications due to certain inherent characteristics.AIM To investigate the impact of MERTK mutations on hiPSCs and determine whether hiPSC-derived extracellular vesicles(EVs)influence anomalous cell junction and differentiation potential.METHODS We employed a non-integrating reprogramming technique to generate peripheral blood-derived hiPSCs with and hiPSCs without a MERTK mutation.Chromo-somal karyotype analysis,flow cytometry,and immunofluorescent staining were utilized for hiPSC identification.Transcriptomics and proteomics were employed to elucidate the expression patterns associated with cell junction abnormalities and cellular differentiation potential.Additionally,EVs were isolated from the supernatant,and their RNA and protein cargos were examined to investigate the involvement of hiPSC-derived EVs in stem cell junction and differentiation.RESULTS The generated hiPSCs,both with and without a MERTK mutation,exhibited normal karyotype and expressed pluripotency markers;however,hiPSCs with a MERTK mutation demonstrated anomalous adhesion capability and differentiation potential,as confirmed by transcriptomic and proteomic profiling.Furthermore,hiPSC-derived EVs were involved in various biological processes,including cell junction and differentiation.CONCLUSION HiPSCs with a MERTK mutation displayed altered junction characteristics and aberrant differentiation potential.Furthermore,hiPSC-derived EVs played a regulatory role in various biological processes,including cell junction and differentiation.

Determination of the Series Resistance of a Series Vertical-Junction Silicon (N+/P/P+) Solar Cell under Polychromatic Illumination and Magnetic Field: Effect of Optimum Thickness

By solving the magneto-transport equation for excess minority charge carriers in the base of the series vertical-junction silicon cell, the phenomenological parameters of the cell can be determined from the boundary conditions. Photocurrent density and photovoltage are determined for each value of applied magnetic field and corresponding optimum thickness, to establish the current-voltage characteristic (Jph(Sf, Sb, z, B, Hop)-Vph(Sf, Sb, z, B, Hop) of the silicon cell under polychromatic illumination. This study will make it possible to reduce the material used (by reducing the optimum thickness), which will help to lower prices. It will also enable us to reduce betting effects (lower series resistance), thereby boosting solar cell efficiency.

Expression Patterns of the Cell Junction-associated Genes During Rat Liver Regeneration

To study actions of the genes associated with tight junction, adherent junction, focal adhesion, and gap junction during liver regeneration （LR）, these genes were obtained by collecting data from databases and thesis, and their expression profiles in rat regenerating liver were detected employing Rat Genome 230 2.0 array. Next the LR-associated genes were identified by comparing the difference between sham operation （SO） and partial hepatectomy （PH） groups. 79, 53, 109, 53 genes involved in the above four junctions were found to be LR-associated. The initial and total expression numbers of these genes occurring in the initial phase of LR, G0/G1, cell proliferation, cell differentiation, and structure-functional rebuilding were 124, 43, 122, 10, and 249, 145, 957, 306, respectively, illustrating that genes were initi^ly expressed mainly in the initiation stage, and functioned in different phases. Up-regulation-and down-regulation to a total of 972 and 540 times, as well as, 41 types of expression patterns showed that the physiological and biochemical activities were diverse and complicated in LR. According to the data, there was an increase in the forepart and prophase, but a decrease in late-metaphase and anaphase for gap junction assembly. Focal adhesion formation displayed an enhancement in forepart, prophase, and anaphase; and formation of tight junctions and adherent junctions last throughout the LR.

Cinnamicaldehyde regulates the expression of tight junction proteins and amino acid transporters in intestinal porcine epithelial cells

Background： Cinnamicaldehyde（CA） is a key flavor compound in cinnamon essential oil possessing various bioactivities. Tight junction（TJ） proteins are vital for the maintenance of intestinal epithelial barrier function,transport, absorption and utilization of dietary amino acids and other nutrients. In this study, we tested the hypothesis that CA may regulate the expression of TJ proteins and amino acid transporters in intestinal porcine epithelial cells（IPEC-1） isolated from neonatal pigs.Results： Compared with the control, cells incubated with 25 μmol/L CA had increased transepithelial electrical resistance（TEER） and decreased paracellular intestinal permeability. The beneficial effect of CA on mucosal barrier function was associated with enhanced protein abundance for claudin-4, zonula occludens（ZO）-1, ZO-2, and ZO-3. Immunofluorescence staining showed that 25 μmol/L CA promoted the localization of claudin-1 and claudin-3 to the plasma membrane without affecting the localization of other TJ proteins, including claudin-4, occludin,ZO-1, ZO-2, and ZO-3, compared with the control cells. Moreover, protein abundances for rBAT, xCT and LAT2 in IPEC-1 cells were enhanced by 25 μmol/L CA, while that for EAAT3 was not affected.Conclusions： CA improves intestinal mucosal barrier function by regulating the distribution of claudin-1 and claudin-3 in enterocytes, as well as enhancing protein abundance for amino acid transporters rBAT, xCT and LAT2 in enterocytes. Supplementation with CA may provide an effective nutritional strategy to improve intestinal integrity and amino acid transport and absorption in piglets.

Cell junction proteins within the cochlea: A review of recent research

Cell-cell junctions in the cochlea are highly complex and well organized. The role of these junctions is to maintain structural and functional integrity of the cochlea. In this review, we describe classification of cell junction-associated proteins identified within the cochlea and provide a brief overview of the function of these proteins in adherent junctions, gap junctions and tight junctions. Copyright ? 2016, PLA General Hospital Department of Otolaryngology Head and Neck Surgery. Production and hosting by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Ultrastructure of human neural stem/progenitor cells and neurospheres

BACKGROUND： Biological and morphological characteristics of neural stem/progenitor cells （NSPCs） have been widely investigated. OBJECTIVE： To explore the ultrastructure of human embryo-derived NSPCs and neurospheres cultivated in vitro using electron microscopy. DESIGN, TIME AND SETTING： A cell biology experiment was performed at the Brain Tumor Laboratory of Soochow University, and Jiangsu Province Key Laboratory of Neuroregeneration, Nantong University between August 2007 and April 2008. MATERIALS： Human fetal brain tissue was obtained from an 8-week-old aborted fetus; serum-free Dulbecco＇s modified Eagle＇s medium/F12 culture medium was provided by Gibco, USA; scanning electron microscope was provided by Hitachi Instruments, Japan; transmission electron microscope was provided by JEOL, Japan. METHODS： NSPCs were isolated from human fetal brain tissue and cultivated in serum-free Dulbecco＇s modified Eagle＇s medium/F12 culture medium. Cells were passaged every 5-7 days. After three passages, NSPCs were harvested and used for ultrastructural examination. MAIN OUTCOME MEASURES： Ultrastructural examination of human NSPCs and adjacent cells in neurospheres. RESULTS： Individual NSPCs were visible as spherical morphologies with rough surfaces under scanning electron microscope. Generally, they had large nuclei and little cytoplasm. Nuclei were frequently globular with large amounts of euchromatin and a small quantity of heterochromatin, and most NSPCs had only one nucleolus. The Golgi apparatus and endoplasmic reticulum were underdeveloped; however, autophagosomes were clearly visible. The neurospheres were made up of NSPCs and non-fixiform material inside. Between adjacent cells and at the cytoplasmic surface of apposed plasma membranes, there were vesicle-like structures. Some membrane boundaries with high permeabilities were observed between some contiguous NSPCs in neurospheres, possibly attributable to plasmalemmal fusion between adjacent cells. CONCLUSION： A large number of autophagosomes were observed in NSPCs and gap junctions were visible between adjacent NSPCs.

Enhanced Efficiency of Metamorphic Triple Junction Solar Cells for Space Applications

Metamorphic In0.55Ga0.45P/In0.06Ga0.94As/Ge triple-junction （3J-MM） solar cells are grown on Ge （100） sub- strates via metal organic chemical vapor deposition. Epi-structural analyses such as high resolution x-ray diffrac- tion, photoluminence, cathodoluminescence and HRTEM are employed and the results show that the high crystal quality of 3J-MM solar cells is obtained with low threading dislocation density of graded buffer （an average value of 6.8× 10^4/cm2）. Benefitting from the optimized bandgap combination, under one sun, AM0 spectrum, 25℃ conditions, the conversion efficiency is achieved about 32%, 5% higher compared with the lattice-matched In0.49Ga0.51P/In0.01Ga0.99As/Ge triple junction （3J-LM） solar cell. Under 1-MeV electron irradiation test, the degradation of the EQE and I-V characteristics of 3J-MM solar cells is at the same level as the 33-LM solar cell. The end-of-life efficiency is -27.1%. Therefore, the metamorphic triple-junction solar cell may be a promising candidate for next-generation space multi-junction solar cells.

Three Dimensional Study of Spectral Response of Polycrystalline Silicon Solar Cells： Vertical Junction Frequency Modulation Scheme

In this paper, the modeling ofa bifacial polycrystalline silicon solar cells vertical junction is presented. The study in dynamic frequency is limited to wavelengths from 400 nm to 1100 nm. The dependence of solar cell spectral response on wavelengths for several modulation frequencies was evaluated by using solar cell internal quantum efficiency.The objective is to characterize the polycrystalline silicon in 3D. The effect of frequency modulation pulsation on the phase of internal quantum efficiency was presented as well as values of shunt and series resistance for various grains size values. The results show that the value of maximum internal quantum efficiency is about 50% with a wavelength of 0,82 nm and a frequency of 103 rad/s under monochromatic illumination.

Hemicentins:What have we learned from worms?

Hemicentins are conserved extracellular matrix proteins discovered in Caenorhabditis elegans, with orthologs in all vertebrate species including human and mouse. Hemicentins share a single, highly conserved amino-terminal von Willebrand A domain, followed by a long （〉40） stretch of immunoglobulin repeats, multiple tandem epidermal growth factors and a fibulin-like carboxy-terminal module. C. elegans has a single hemicentin gene that has pleiotropic functions in transient cell contacts that are required for cell migration and basement membrane invasion and in stable contacts at hemidesmosome-mediated cell junctions and elastic fiber-like structures. Here, we summarize what is known about the function ofhemicentin in C. elegans and discuss implications for hemicentin function in other species.

Claudin-11 and occludin are major contributors to Sertoli cell tight junction function, in vitro

The Sertoli cell tight junction （T J） is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to TJ function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the TJ. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively TJ function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of junction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in TJ function of 55% （P 〈 0.01）, 51% （P 〈 0.01）, and 62% （P 〈 0.01）, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell TJ. We provide quantitative evidence that claudin-11 contributes significantly （P 〈 0.01） to Sertoli cell TJ function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant （P 〈 0.01） contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal TJ barrier structure and function.

Simulation of double junction In0.46Ga0.54N/Si tandem solar cell

A comprehensive study of high efficiency In（0.46）Ga（0.54）N/Si tandem solar cell is presented.A tunnel junction（TJ） was needed to interconnect the top and bottom sub-cells.Two TJ designs,integrated within this tandem：GaAs（n^＋）/GaAs（p^＋） and In（0.5）Ga（0.5）N（n^＋）/Si（p^＋） were considered.Simulations of GaAs（n^＋）/GaAs（p^＋）and In（0.5）Ga（0.5）N（n^＋）/Si（p^＋） TJ I-V characteristics were studied for integration into the proposed tandem solar cell.A comparison of the simulated solar cell I-V characteristics under 1 sun AM1.5 spectrum was discussed in terms of short circuit current density（J（SC））,open circuit voltage（V（OC））,fill factor（FF） and efficiency（η） for both tunnel junction designs.Using GaAs（n^＋）/GaAs（p^＋） tunnel junction,the obtained values of J（SC） = 21.74 mA/cm-2,V（OC）= 1,81 V,FF = 0.87 and η=34.28%,whereas the solar cell with the In（0.5）Ga（0.5）N/Si tunnel junction reported values of J（SC）= 21.92 mA/cm-2,V（OC）= 1.81 V,FF = 0.88 and η= 35.01%.The results found that required thicknesses for GaAs（n^＋）/GaAs（p^＋） and In（0.5）Ga（0.5）N（n^＋）/Si（p^＋） tunnel junctions are around 20 nm,the total thickness of the top InGaN can be very small due to its high optical absorption coefficient and the use of a relatively thick bottom cell is necessary to increase the conversion efficiency.

Numerical simulation of the performance of the a-Si:H/a-SiGe:H/a-SiGe:H tandem solar cell

The computer program AMPS-1D（analysis of microelectronic and photonic structures） has been employed to simulate the performance of the a-Si：H/a-SiGe：H/a-SiGe：H triple-junction solar cell at the radiation of AM1.5G（100 mW/cm2/ and room temperature. Firstly, three sub-cells with band gaps of 1.8, 1.6 and 1.4 eV are simulated, respectively. The simulation results indicate that the density of defect states is an important factor, which affects the open circuit voltage and the filling factor of the solar cell. The two-step current matching method and the control variate method are employed in the simulation. The results show that the best solar cell performance would be achieved when the intrinsic layer thickness from top to bottom is set to be 70, 180 and 220 nm, respectively. We also optimize the tunnel-junction structure of the solar cell reasonably, the simulation results show that the open circuit voltage, filling factor and conversion efficiency are all improved and the S-shape current density–voltage curve disappears during optimizing the tunnel-junction structure. Besides, the diagram of the energy band and the carrier recombination rate are also analyzed. Finally, our simulation data are compared to the experimental data published in other literature. It is demonstrated that the numerical results agree with the experimental ones very well.

Platinum nanoparticles promote breast cancer cell metastasis by disrupting endothelial barrier and inducing intravasation and extravasation

Breast cancer is a common malignancy in women with disappointing prognosis especially the triple-negative subtype.Recently,nanomedicine becomes a promising therapeutic strategy for breast cancer,such as platinum nanoparticles(PtNPs).Despite the promising anticancer effects of PtNPs,the safety of PtNPs remains to be fully evaluated.Herein,a series of cell and animal experiments demonstrate that PtNPs facilitate breast cancer metastasis by damaging the vascular endothelial barrier.PtNPs disrupt endothelial cell proliferation,migration and tube-like structure formation,destruct endothelial adhesions junctions and induce endothelial barrier leakiness in vitro most likely by stimulating intracellular reactive oxygen species(ROS)generation and altering the expression and conformation of endothelial junctional proteins,thus promoting intravasation and extravasation of the implanted 4T1 breast cancer cells and leading to cancer metastasis in female BALB/c nude mice in vivo.In addition,smaller PtNPs(5 nm)are more potent than larger PtNPs(70 nm)in exerting the above effects.The study provides the first evidence that PtNPs can promote breast cancer metastasis by damaging endothelial barrier.The unexpected detrimental effects of PtNPs should be considered in future nanomedicine designs for the treatment of breast cancer.

Ultrathin microcrystalline hydrogenated Si/Ge alloyed tandem solar cells towards full solar spectrum conversion

Thin film solar cells have been proved the next generation photovoltaic devices due to their low cost,less material consumption and easy mass production.Among them,micro-crystalline Si and Ge based thin film solar cells have advantages of high efficiency and ultrathin absorber layers.Yet individual junction devices are limited in photoelectric conversion efficiency because of the restricted solar spectrum range for its specific absorber.In this work,w e designed a nd simulated a multi-junction solar cell with its four sub-cells selectively absorbing the full solar spectrum including the ultraviolet,green,red as well as near infrared range,respectively.B y tuning the G e content,the record efficiency of 24.80%has been realized with the typical quadruple junction structure of a-Si:H/a-Si0.9Ge0.1:H/μc-Si:H/μc-Si0.5Ge0.5:H.To further reduce the material cost,thickness dependent device performances have been conducted.It can be found that the design of total thickness of 4μm is the optimal device design in balancing the thickness a nd the PCE.While the design of ultrathin quadruple junction device with total thickness of 2μm is the optimized device design regarding cost and long-term stability with a little bit more reduction in PCE.These results indicated that our solar cells combine the advantages of low cost and high stability.Our work may provide a general guidance rule of utilizing the full solar spectrum for developing high efficiency and ultrathin multi-junction solar cells.

HBV Integration Induces Complex Interactions between Host and Viral Genomic Functions at the Insertion Site

Hepatitis B virus(HBV),one of the well-known DNA oncogenic viruses,is the leading cause of hepatocellular carcinoma(HCC).In infected hepatocytes,HBV DNA can be integrated into the host genome through an insertional mutagenesis process inducing tumorigenesis.Dissection of the genomic features surrounding integration sites will deepen our understanding of mechanisms underlying integration.Moreover,the quantity and biological activity of integration sites may reflect the DNA damage within affected cells or the potential survival benefits they may confer.The wellknown human genomic features include repeat elements,particular regions(such as telomeres),and frequently interrupted genes(e.g.,telomerase reverse transcriptase[i.e.TERT],lysine methyltransferase 2B[i.e.KMT2B],cyclin E1[CCNE1],and cyclin A2[CCNA2]).Consequently,distinct genomic features within diverse integrations differentiate their biological functions.Meanwhile,accumulating evidence has shown that viral proteins produced by integrants may cause cell damage even after the suppression of HBV replication.The integration-derived gene products can also serve as tumor markers,promoting the development of novel therapeutic strategies for HCC.Viral integrants can be single copy or multiple copies of different fragments with complicated rearrangement,which warrants elucidation of the whole viral integrant arrangement in future studies.All of these considerations underlie an urgent need to develop novel methodology and technology for sequence characterization and function evaluation of integration events in chronic hepatitis B-associated disease progression by monitoring both host genomic features and viral integrants.This endeavor may also serve as a promising solution for evaluating the risk of tumorigenesis and as a companion diagnostic for designing therapeutic strategies targeting integration-related disease complications.

InP/GaInP nanowire tunnel diodes

Semiconductor nanowire （NW） solar cells with a single p-n junction have exhibited efficiency comparable to that of their planar counterparts with a substantial reduction in material consumption. Tandem geometry is a path toward the fabrication of devices with even higher efficiencies, for which a key step is the fabrication of tunnel （Esaki） diodes within NWs with the correct diameter, pitch, and material combination for maximized efficiency. InP/GaInP and GaInP/InP NW tunnel diodes with band gap combinations corresponding to high-efficiency solar energy harvesting were fabricated and their electrical characteristics and material properties were compared. Four different configurations, with respect to material composition and doping, were investigated. The NW arrays were grown with metal-organic vapor-phase epitaxy from Au particles by use of nano-imprint lithography, metal evaporation and lift-off. Electrical measurements showed that the NWs behave as tunnel diodes in both InP （bottom）/GaInP （top） and GaInP （bottom）/InP （top） configurations, exhibiting a maximum peak current density of 25 A/cm^2, and maximum peak to valley current ratio of 2.5 at room temperature. The realization of NW tunnel diodes in both InP/GaInP and GaInP/InP configurations represent an opportunity for the use of NW tandem solar cells, whose efficiency is independent of the growth order of the different materials, increasing the flexibility regarding dopant incorporation polarity.