Air Breathing Direct Methanol Fuel Cell

DOEpatents

Ren; Xiaoming

2003-07-22

A method for activating a membrane electrode assembly for a direct methanol fuel cell is disclosed. The method comprises operating the fuel cell with humidified hydrogen as the fuel followed by running the fuel cell with methanol as the fuel.

Unexpected T cell regulatory activity of anti-histone H1 autoantibody: Its mode of action in regulatory T cell-dependent and -independent manners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takaoka, Yuki; Kawamoto, Seiji, E-mail: skawa@hiroshima-u.ac.jp; Katayama, Akiko

2013-02-08

Highlights: ► Anti-histone H1 autoantibody (anti-H1) acts on T cells to inhibit their activation. ► Anti-H1 suppresses T cell activation in Treg cell-dependent and -independent manners. ► Suboptimal dose of anti-H1 enhances suppressor function of Treg cells. ► High dose of anti-H1 directly inhibits T cell receptor signaling. -- Abstract: Induction of anti-nuclear antibodies against DNA or histones is a hallmark of autoimmune disorders, but their actual contribution to disease predisposition remains to be clarified. We have previously reported that autoantibodies against histone H1 work as a critical graft survival factor in a rat model of tolerogeneic liver transplantation. Heremore » we show that an immunosuppressive anti-histone H1 monoclonal antibody (anti-H1 mAb) acts directly on T cells to inhibit their activation in response to T cell receptor (TCR) ligation. Intriguingly, the T cell activation inhibitory activity of anti-H1 mAb under suboptimal dosages required regulatory T (Treg) cells, while high dose stimulation with anti-H1 mAb triggered a Treg cell-independent, direct negative regulation of T cell activation upon TCR cross-linking. In the Treg cell-dependent mode of immunosuppressive action, anti-H1 mAb did not induce the expansion of CD4{sup +}Foxp3{sup +} Treg cells, but rather potentiated their regulatory capacity. These results reveal a previously unappreciated T cell regulatory role of anti-H1 autoantibody, whose overproduction is generally thought to be pathogenic in the autoimmune settings.« less

Tetraspan TM4SF5-dependent direct activation of FAK and metastatic potential of hepatocarcinoma cells

PubMed Central

Jung, Oisun; Choi, Suyong; Jang, Sun-Bok; Lee, Sin-Ae; Lim, Ssang-Taek; Choi, Yoon-Ju; Kim, Hye-Jin; Kim, Do-Hee; Kwak, Tae Kyoung; Kim, Hyeonjung; Kang, Minkyung; Lee, Mi-Sook; Park, Sook Young; Ryu, Jihye; Jeong, Doyoung; Cheong, Hae-Kap; Kim, Hyun Jeong; Park, Ki Hun; Lee, Bong-Jin; Schlaepfer, David D.; Lee, Jung Weon

2012-01-01

Summary Transmembrane 4 L six family member 5 (TM4SF5) plays an important role in cell migration, and focal adhesion kinase (FAK) activity is essential for homeostatic and pathological migration of adherent cells. However, it is unclear how TM4SF5 signaling mediates the activation of cellular migration machinery, and how FAK is activated during cell adhesion. Here, we showed that direct and adhesion-dependent binding of TM4SF5 to FAK causes a structural alteration that may release the inhibitory intramolecular interaction in FAK. In turn, this may activate FAK at the cell's leading edge, to promote migration/invasion and in vivo metastasis. TM4SF5-mediated FAK activation occurred during integrin-mediated cell adhesion. TM4SF5 was localized at the leading edge of the cells, together with FAK and actin-organizing molecules, indicating a signaling link between TM4SF5/FAK and actin reorganization machinery. Impaired interactions between TM4SF5 and FAK resulted in an attenuated FAK phosphorylation (the signaling link to actin organization machinery) and the metastatic potential. Our findings demonstrate that TM4SF5 directly binds to and activates FAK in an adhesion-dependent manner, to regulate cell migration and invasion, suggesting that TM4SF5 is a promising target in the treatment of metastatic cancer. PMID:23077174

Chronophin coordinates cell leading edge dynamics by controlling active cofilin levels

PubMed Central

Delorme-Walker, Violaine; Seo, Ji-Yeon; Gohla, Antje; Fowler, Bruce; Bohl, Ben; DerMardirossian, Céline

2015-01-01

Cofilin, a critical player of actin dynamics, is spatially and temporally regulated to control the direction and force of membrane extension required for cell locomotion. In carcinoma cells, although the signaling pathways regulating cofilin activity to control cell direction have been established, the molecular machinery required to generate the force of the protrusion remains unclear. We show that the cofilin phosphatase chronophin (CIN) spatiotemporally regulates cofilin activity at the cell edge to generate persistent membrane extension. We show that CIN translocates to the leading edge in a PI3-kinase–, Rac1-, and cofilin-dependent manner after EGF stimulation to activate cofilin, promotes actin free barbed end formation, accelerates actin turnover, and enhances membrane protrusion. In addition, we establish that CIN is crucial for the balance of protrusion/retraction events during cell migration. Thus, CIN coordinates the leading edge dynamics by controlling active cofilin levels to promote MTLn3 cell protrusion. PMID:26324884

Genetics Home Reference: ZAP70-related severe combined immunodeficiency

MedlinePlus

... involved in the activation of helper T cells (CD4+ T cells). These cells direct and assist the functions of ... CD8+ T cells and an excess of inactive CD4+ T cells. The resulting shortage of active T cells causes ...

Corrected and Republished from: BCL11A Is a Critical Component of a Transcriptional Network That Activates Recombinase Activating Gene Expression and V(D)J Recombination

PubMed Central

Lee, Baeck-Seung; Lee, Bum-Kyu; Iyer, Vishwanath R.; Sleckman, Barry P.; Shaffer, Arthur L.; Ippolito, Gregory C.

2017-01-01

ABSTRACT Recombination activating gene 1 (RAG1) and RAG2 are critical enzymes for initiating variable-diversity-joining [V(D)J] segment recombination, an essential process for antigen receptor expression and lymphocyte development. The BCL11A transcription factor is required for B cell and plasmacytoid dendritic cell (pDC) development, but its molecular function(s) in early B cell fate specification and commitment is unknown. We show here that the major B cell isoform, BCL11A-XL, binds directly to the RAG1 promoter as well as directly to regulatory regions of transcription factors previously implicated in both B cell and pDC development to activate RAG1 and RAG2 gene transcription in pro- and pre-B cells. We employed BCL11A overexpression with recombination substrates to demonstrate direct consequences of BCL11A/RAG modulation on V(D)J recombination. We conclude that BCL11A is a critical component of a transcriptional network that regulates B cell fate by controlling V(D)J recombination. PMID:29038163

The activation of directional stem cell motility by green light-emitting diode irradiation.

PubMed

Ong, Wei-Kee; Chen, How-Foo; Tsai, Cheng-Ting; Fu, Yun-Ju; Wong, Yi-Shan; Yen, Da-Jen; Chang, Tzu-Hao; Huang, Hsien-Da; Lee, Oscar Kuang-Sheng; Chien, Shu; Ho, Jennifer Hui-Chun

2013-03-01

Light-emitting diode (LED) irradiation is potentially a photostimulator to manipulate cell behavior by opsin-triggered phototransduction and thermal energy supply in living cells. Directional stem cell motility is critical for the efficiency and specificity of stem cells in tissue repair. We explored that green LED (530 nm) irradiation directed the human orbital fat stem cells (OFSCs) to migrate away from the LED light source through activation of extracellular signal-regulated kinases (ERK)/MAP kinase/p38 signaling pathway. ERK inhibitor selectively abrogated light-driven OFSC migration. Phosphorylation of these kinases as well as green LED irradiation-induced cell migration was facilitated by increasing adenosine triphosphate (ATP) production in OFSCs after green LED exposure, and which was thermal stress-independent mechanism. OFSCs, which are multi-potent mesenchymal stem cells isolated from human orbital fat tissue, constitutionally express three opsins, i.e. retinal pigment epithelium-derived rhodopsin homolog (RRH), encephalopsin (OPN3) and short-wave-sensitive opsin 1 (OPN1SW). However, only two non-visual opsins, i.e. RRH and OPN3, served as photoreceptors response to green LED irradiation-induced OFSC migration. In conclusion, stem cells are sensitive to green LED irradiation-induced directional cell migration through activation of ERK signaling pathway via a wavelength-dependent phototransduction. Copyright © 2012 Elsevier Ltd. All rights reserved.

Prebiotics as immunostimulants in aquaculture: a review.

PubMed

Song, Seong Kyu; Beck, Bo Ram; Kim, Daniel; Park, John; Kim, Jungjoon; Kim, Hyun Duk; Ringø, Einar

2014-09-01

Prebiotics are indigestible fibers that increase beneficial gut commensal bacteria resulting in improvements of the host's health. The beneficial effects of prebiotics are due to the byproducts generated from their fermentation by gut commensal bacteria. In this review, the direct effects of prebiotics on the innate immune system of fish are discussed. Prebiotics, such as fructooligosaccharide, mannanoligosaccharide, inulin, or β-glucan, are called immunosaccharides. They directly enhance innate immune responses including: phagocytic activation, neutrophil activation, activation of the alternative complement system, increased lysozyme activity, and more. Immunosaccharides directly activate the innate immune system by interacting with pattern recognition receptors (PRR) expressed on innate immune cells. They can also associate with microbe associated molecular patterns (MAMPs) to activate innate immune cells. However, the underlying mechanisms involved in innate immune cell activation need to be further explored. Many studies have indicated that immunosaccharides are beneficial to both finfish and shellfish. Copyright © 2014 Elsevier Ltd. All rights reserved.

Vitamin D binding protein-macrophage activating factor directly inhibits proliferation, migration, and uPAR expression of prostate cancer cells.

PubMed

Gregory, Kalvin J; Zhao, Bing; Bielenberg, Diane R; Dridi, Sami; Wu, Jason; Jiang, Weihua; Huang, Bin; Pirie-Shepherd, Steven; Fannon, Michael

2010-10-18

Vitamin D binding protein-macrophage activating factor (DBP-maf) is a potent inhibitor of tumor growth. Its activity, however, has been attributed to indirect mechanisms such as boosting the immune response by activating macrophages and inhibiting the blood vessel growth necessary for the growth of tumors. In this study we show for the first time that DBP-maf exhibits a direct and potent effect on prostate tumor cells in the absence of macrophages. DBP-maf demonstrated inhibitory activity in proliferation studies of both LNCaP and PC3 prostate cancer cell lines as well as metastatic clones of these cells. Flow cytometry studies with annexin V and propidium iodide showed that this inhibitory activity is not due to apoptosis or cell death. DBP-maf also had the ability to inhibit migration of prostate cancer cells in vitro. Finally, DBP-maf was shown to cause a reduction in urokinase plasminogen activator receptor (uPAR) expression in prostate tumor cells. There is evidence that activation of this receptor correlates with tumor metastasis. These studies show strong inhibitory activity of DBP-maf on prostate tumor cells independent of its macrophage activation.

Vitamin D Binding Protein-Macrophage Activating Factor Directly Inhibits Proliferation, Migration, and uPAR Expression of Prostate Cancer Cells

PubMed Central

Bielenberg, Diane R.; Dridi, Sami; Wu, Jason; Jiang, Weihua; Huang, Bin; Pirie-Shepherd, Steven; Fannon, Michael

2010-01-01

Background Vitamin D binding protein-macrophage activating factor (DBP-maf) is a potent inhibitor of tumor growth. Its activity, however, has been attributed to indirect mechanisms such as boosting the immune response by activating macrophages and inhibiting the blood vessel growth necessary for the growth of tumors. Methods and Findings In this study we show for the first time that DBP-maf exhibits a direct and potent effect on prostate tumor cells in the absence of macrophages. DBP-maf demonstrated inhibitory activity in proliferation studies of both LNCaP and PC3 prostate cancer cell lines as well as metastatic clones of these cells. Flow cytometry studies with annexin V and propidium iodide showed that this inhibitory activity is not due to apoptosis or cell death. DBP-maf also had the ability to inhibit migration of prostate cancer cells in vitro. Finally, DBP-maf was shown to cause a reduction in urokinase plasminogen activator receptor (uPAR) expression in prostate tumor cells. There is evidence that activation of this receptor correlates with tumor metastasis. Conclusions These studies show strong inhibitory activity of DBP-maf on prostate tumor cells independent of its macrophage activation. PMID:20976141

A secreted protein is an endogenous chemorepellant in Dictyostelium discoideum

PubMed Central

Phillips, Jonathan E.; Gomer, Richard H.

2012-01-01

Chemorepellants may play multiple roles in physiological and pathological processes. However, few endogenous chemorepellants have been identified, and how they function is unclear. We found that the autocrine signal AprA, which is produced by growing Dictyostelium discoideum cells and inhibits their proliferation, also functions as a chemorepellant. Wild-type cells at the edge of a colony show directed movement outward from the colony, whereas cells lacking AprA do not. Cells show directed movement away from a source of recombinant AprA and dialyzed conditioned media from wild-type cells, but not dialyzed conditioned media from aprA− cells. The secreted protein CfaD, the G protein Gα8, and the kinase QkgA are necessary for the chemorepellant activity of AprA as well as its proliferation-inhibiting activity, whereas the putative transcription factor BzpN is dispensable for the chemorepellant activity of AprA but necessary for inhibition of proliferation. Phospholipase C and PI3 kinases 1 and 2, which are necessary for the activity of at least one other chemorepellant in Dictyostelium, are not necessary for recombinant AprA chemorepellant activity. Starved cells are not repelled by recombinant AprA, suggesting that aggregation-phase cells are not sensitive to the chemorepellant effect. Cell tracking indicates that AprA affects the directional bias of cell movement, but not cell velocity or the persistence of cell movement. Together, our data indicate that the endogenous signal AprA acts as an autocrine chemorepellant for Dictyostelium cells. PMID:22711818

Coupled excitable Ras and F-actin activation mediates spontaneous pseudopod formation and directed cell movement

PubMed Central

van Haastert, Peter J. M.; Keizer-Gunnink, Ineke; Kortholt, Arjan

2017-01-01

Many eukaryotic cells regulate their mobility by external cues. Genetic studies have identified >100 components that participate in chemotaxis, which hinders the identification of the conceptual framework of how cells sense and respond to shallow chemical gradients. The activation of Ras occurs during basal locomotion and is an essential connector between receptor and cytoskeleton during chemotaxis. Using a sensitive assay for activated Ras, we show here that activation of Ras and F-actin forms two excitable systems that are coupled through mutual positive feedback and memory. This coupled excitable system leads to short-lived patches of activated Ras and associated F-actin that precede the extension of protrusions. In buffer, excitability starts frequently with Ras activation in the back/side of the cell or with F-actin in the front of the cell. In a shallow gradient of chemoattractant, local Ras activation triggers full excitation of Ras and subsequently F-actin at the side of the cell facing the chemoattractant, leading to directed pseudopod extension and chemotaxis. A computational model shows that the coupled excitable Ras/F-actin system forms the driving heart for the ordered-stochastic extension of pseudopods in buffer and for efficient directional extension of pseudopods in chemotactic gradients. PMID:28148648

Improved Direct Methanol Fuel Cell Stack

DOEpatents

Wilson, Mahlon S.; Ramsey, John C.

2005-03-08

A stack of direct methanol fuel cells exhibiting a circular footprint. A cathode and anode manifold, tie-bolt penetrations and tie-bolts are located within the circular footprint. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet and outlet cathode manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold, where the serpentine channels of the anode are orthogonal to the serpentine channels of the cathode. Located between the two plates is the fuel cell active region.

High specific power, direct methanol fuel cell stack

DOEpatents

Ramsey, John C [Los Alamos, NM; Wilson, Mahlon S [Los Alamos, NM

2007-05-08

The present invention is a fuel cell stack including at least one direct methanol fuel cell. A cathode manifold is used to convey ambient air to each fuel cell, and an anode manifold is used to convey liquid methanol fuel to each fuel cell. Tie-bolt penetrations and tie-bolts are spaced evenly around the perimeter to hold the fuel cell stack together. Each fuel cell uses two graphite-based plates. One plate includes a cathode active area that is defined by serpentine channels connecting the inlet manifold with an integral flow restrictor to the outlet manifold. The other plate includes an anode active area defined by serpentine channels connecting the inlet and outlet of the anode manifold. Located between the two plates is the fuel cell active region.

Forced expression of Hnf4a induces hepatic gene activation through directed differentiation.

PubMed

Yahoo, Neda; Pournasr, Behshad; Rostamzadeh, Jalal; Fathi, Fardin

2016-08-05

Embryonic stem (ES) cells are capable of unlimited self-renewal and have a diverse differentiation potential. These unique features make ES cells as an attractive source for developmental biology studies. Having the mature hepatocyte in the lab with functional activities is valuable in drug discovery studies. Overexpression of hepatocyte lineage-specific transcription factors (TFs) becomes a promising approach in pluripotent cell differentiation toward liver cells. Many studies generate transgenic ES cell lines to examine the effects of specific TFs overexpression in cell differentiation. In the present report, we have addressed whether a suspension or adherent model of differentiation is an appropriate way to study the role of Hnf4a overexpression. We generated ES cells that carried a doxycycline (Dox)-inducible Hnf4a using lentiviral vectors. The transduced cells were subjected to induced Hnf4a overexpression through both spontaneous and directed differentiation methods. Gene expression analysis showed substantially increased expression of hepatic gene markers, particularly Ttr and endogenous Hnf4a, in transduced cells differentiated by the directed approach. These results demonstrated that forced expression of TFs during directed differentiation would be an appropriate way to study relevant gene activation and the effects of overexpression in the context of hepatic differentiation. Copyright © 2016 Elsevier Inc. All rights reserved.

Analysis of the promoter of the cudA gene reveals novel mechanisms of Dictyostelium cell type differentiation.

PubMed

Fukuzawa, M; Williams, J G

2000-06-01

The cudA gene encodes a nuclear protein that is essential for normal multicellular development. At the slug stage cudA is expressed in the prespore cells and in a sub-region of the prestalk zone. We show that cap site distal promoter sequences direct cudA expression in prespore cells, while proximal sequences direct expression in the prestalk sub-region. The promoter domain that directs prespore-specific transcription consists of a positively acting region, that has the potential to direct expression in all cells within the slug, and a negatively acting region that prevents expression in the prestalk cells. Dd-STATa is the STAT protein that regulates commitment to stalk cell gene expression, where it is known to function as a transcriptional repressor. We show that Dd-STATa binds in vitro to the positively acting part of the prespore domain of the cudA promoter. However, Dd-STATa cannot be utilised for this purpose in vivo, because analysis of a Dd-STATa null mutant strain shows that Dd-STATa is not necessary for cudA transcription in prespore cells. In contrast, the part of the cudA promoter that directs prestalk-specific expression contains a binding site for Dd-STATa that is essential for its biological activity. Dd-STATa appears therefore to serve as a direct activator of cudA transcription in prestalk cells, while a protein with a DNA binding specificity highly related to that of Dd-STATa is utilised to activate cudA transcription in prespore cells.

Calpain-Mediated positional information directs cell wall orientation to sustain plant stem cell activity, growth and development

USDA-ARS?s Scientific Manuscript database

Eukaryotic development and stem cell control depend on the integration of cell positional sensing with cell cycle control and cell wall positioning, yet few factors that directly link these events are known. The DEFECTIVE KERNEL1 (DEK1) gene encoding the unique plant calpain protein is fundamental f...

Molecular imaging of low-power laser irradiation induced cell proliferation

NASA Astrophysics Data System (ADS)

Gao, Xuejuan; Wang, Fang; Da, Xing

2006-02-01

Low-power laser irradiation (LPLI) has been shown to promote cell proliferation in various cell types, yet the mechanism of which has not been fully clarified. Studying the signaling pathways involved in the laser irradiation is important for understanding these processes. The Ras/Raf/MEK/ERK (extracellular-signal-regulated kinase) signaling pathway is a network that governs proliferation, differentiation and cell survival. Recent studies suggest that Ras/Raf signaling pathway is involved in the LPLI-induced cell proliferation. Protein kinase Cs (PKCs) have been recently presumed to be involved in the regulation of cell proliferation induced by LPLI. In present study, to monitor the direct interaction between Ras and Raf and PKCs activation after LPLI treatment in living cells in real time, Raichu-Ras reporter and C kinase activity reporter (CKAR) were utilized, both of which were constructed based on fluorescence resonance energy transfer (FRET) technique. Our results show that the direct interaction between Ras and Raf is monitored during cell proliferation induced by LPLI (0.8 J/cm2) in serum-starved human lung adenocarcinoma cells (ASTC-a-1) expressing Raichu-Ras reporter using FRET imaging on laser scanning confocal microscope, and that the increasing dynamics of PKCs activity is also monitored during cell proliferation induced by LPLI (0.8 J/cm2) in serum-starved ASTC-a-1 cells expressing CKAR reporter using the similar way. Taken together, LPLI induces the ASTC-a-1 cell proliferation by activated Ras directly interacting with Raf and by specifically activating PKCs.

Rectified directional sensing in long-range cell migration

PubMed Central

Nakajima, Akihiko; Ishihara, Shuji; Imoto, Daisuke; Sawai, Satoshi

2014-01-01

How spatial and temporal information are integrated to determine the direction of cell migration remains poorly understood. Here, by precise microfluidics emulation of dynamic chemoattractant waves, we demonstrate that, in Dictyostelium, directional movement as well as activation of small guanosine triphosphatase Ras at the leading edge is suppressed when the chemoattractant concentration is decreasing over time. This ‘rectification’ of directional sensing occurs only at an intermediate range of wave speed and does not require phosphoinositide-3-kinase or F-actin. From modelling analysis, we show that rectification arises naturally in a single-layered incoherent feedforward circuit with zero-order ultrasensitivity. The required stimulus time-window predicts ~5 s transient for directional sensing response close to Ras activation and inhibitor diffusion typical for protein in the cytosol. We suggest that the ability of Dictyostelium cells to move only in the wavefront is closely associated with rectification of adaptive response combined with local activation and global inhibition. PMID:25373620

A Model for Direction Sensing in Dictyostelium discoideum: Ras Activity and Symmetry Breaking Driven by a Gβγ-Mediated, Gα2-Ric8 -- Dependent Signal Transduction Network

PubMed Central

Cheng, Yougan; Othmer, Hans

2016-01-01

Chemotaxis is a dynamic cellular process, comprised of direction sensing, polarization and locomotion, that leads to the directed movement of eukaryotic cells along extracellular gradients. As a primary step in the response of an individual cell to a spatial stimulus, direction sensing has attracted numerous theoretical treatments aimed at explaining experimental observations in a variety of cell types. Here we propose a new model of direction sensing based on experiments using Dictyostelium discoideum (Dicty). The model is built around a reaction-diffusion-translocation system that involves three main component processes: a signal detection step based on G-protein-coupled receptors (GPCR) for cyclic AMP (cAMP), a transduction step based on a heterotrimetic G protein Gα2βγ, and an activation step of a monomeric G-protein Ras. The model can predict the experimentally-observed response of cells treated with latrunculin A, which removes feedback from downstream processes, under a variety of stimulus protocols. We show that Gα2βγ cycling modulated by Ric8, a nonreceptor guanine exchange factor for Gα2 in Dicty, drives multiple phases of Ras activation and leads to direction sensing and signal amplification in cAMP gradients. The model predicts that both Gα2 and Gβγ are essential for direction sensing, in that membrane-localized Gα2*, the activated GTP-bearing form of Gα2, leads to asymmetrical recruitment of RasGEF and Ric8, while globally-diffusing Gβγ mediates their activation. We show that the predicted response at the level of Ras activation encodes sufficient ‘memory’ to eliminate the ‘back-of-the wave’ problem, and the effects of diffusion and cell shape on direction sensing are also investigated. In contrast with existing LEGI models of chemotaxis, the results do not require a disparity between the diffusion coefficients of the Ras activator GEF and the Ras inhibitor GAP. Since the signal pathways we study are highly conserved between Dicty and mammalian leukocytes, the model can serve as a generic one for direction sensing. PMID:27152956

Involvement of NK cells against tumors and parasites.

PubMed

Papazahariadou, M; Athanasiadis, G I; Papadopoulos, E; Symeonidou, I; Hatzistilianou, M; Castellani, M L; Bhattacharya, K; Shanmugham, L N; Conti, P; Frydas, S

2007-01-01

Host resistance against pathogens depends on a complex interplay of innate and adaptive immune mechanisms. Acting as an early line of defence, the immune system includes activation of neutrophils, tissue macrophages, monocytes, dendritic cells, eosinophils and natural killer (NK) cells. NK cells are lymphoid cells that can be activated without previous stimulation and are therefore like macrophages in the first line of defence against tumor cells and a diverse range of pathogens. NK cells mediate significant activity and produce high levels of proinflammatory cytokines in response to infection. Their cytotoxicity production is induced principally by monocyte-, macrophage- and dendritic cell-derived cytokines, but their activation is also believed to be cytokine-mediated. Recognition of infection by NK cells is accomplished by numerous activating and inhibitory receptors on the NK cells' surface that selectively trigger the cytolytic activity in a major histocompability complex-independent manner. NK cells have trypanocidal activity of fibroblast cells and mediate direct destruction of extracellular epimastigote and trypomastigote forms of T. cruzi and T. lewisi in vitro; moreover, they kill plasmodia-infected erythrocytes directly through cell-cell interaction. This review provides a more detailed analysis of how NK cells recognize and respond to parasites and how they mediate cytotoxicity against tumor cells. Also the unique role of NK cells in innate immunity to infection and the relationship between parasites and carcinogenesis are discussed.

Ezetimibe inhibits platelet activation and uPAR expression on endothelial cells.

PubMed

Becher, Tobias; Schulze, Torsten J; Schmitt, Melanie; Trinkmann, Frederik; El-Battrawy, Ibrahim; Akin, Ibrahim; Kälsch, Thorsten; Borggrefe, Martin; Stach, Ksenija

2017-01-15

Lipid lowering therapy constitutes the basis of cardiovascular disease therapy. The purpose of this study was to investigate effects of ezetimibe, a selective inhibitor of intestinal cholesterol absorption, on platelets and endothelial cells in an in vitro endothelial cell model. After a 24h incubation period with ezetimibe (concentrations 1, 50, 100 and 1000ng/ml), human umbilical vein endothelial cells (HUVEC) were stimulated for 1h with lipopolysaccharide (LPS) and were then incubated in direct contact with activated platelets. Following this, the expression of CD40L and CD62P on platelets, and the expression of ICAM-1, VCAM-1, uPAR, and MT1-MMP on endothelial cells were measured by flow cytometry. Supernatants were analysed by enzyme linked immunosorbent assay for soluble MCP-1, IL-6 and MMP-1. The increased expression of uPAR on endothelial cells by proinflammatory stimulation with LPS and by direct endothelial contact with activated platelets was significantly reduced through pre-incubation with 100ng/ml and 1000ng/ml ezetimibe (p<0.05). Platelets directly incubated with ezetimibe but without endothelial cell contact showed significantly reduced CD62P and CD40L surface expression (p<0.05). Ezetimibe had no significant effects on HUVEC expression of MT1-MMP, ICAM-1 and VCAM-1 and on CD40L expression on platelets in direct contact with endothelial cells. Levels of soluble IL-6 in HUVEC supernatants were significantly lower after pre-incubation with ezetimibe. In this in vitro analysis, ezetimibe directly attenuates platelet activation and has significant endothelial cell mediated effects on selected markers of atherosclerosis. Copyright © 2016. Published by Elsevier Ireland Ltd.

Increase of gap junction activities in SW480 human colorectal cancer cells.

PubMed

Bigelow, Kristina; Nguyen, Thu A

2014-07-09

Colorectal cancer is one of the most common cancers in the United States with an early detection rate of only 39%. Colorectal cancer cells along with other cancer cells exhibit many deficiencies in cell-to-cell communication, particularly gap junctional intercellular communication (GJIC). GJIC has been reported to diminish as cancer cells progress. Gap junctions are intercellular channels composed of connexin proteins, which mediate the direct passage of small molecules from one cell to the next. They are involved in the regulation of the cell cycle, cell differentiation, and cell signaling. Since the regulation of gap junctions is lost in colorectal cancer cells, the goal of this study is to determine the effect of GJIC restoration in colorectal cancer cells. Gap Junction Activity Assay and protein analysis were performed to evaluate the effects of overexpression of connexin 43 (Cx43) and treatment of PQ1, a small molecule, on GJIC. Overexpression of Cx43 in SW480 colorectal cancer cells causes a 6-fold increase of gap junction activity compared to control. This suggests that overexpressing Cx43 can restore GJIC. Furthermore, small molecule like PQ1 directly targeting gap junction channel was used to increase GJIC. Gap junction enhancers, PQ1, at 200 nM showed a 4-fold increase of gap junction activity in SW480 cells. A shift from the P0 to the P2 isoform of Cx43 was seen after 1 hour treatment with 200 nM PQ1. Overexpression of Cx43 and treatment of PQ1 can directly increase gap junction activity. The findings provide an important implication in which restoration of gap junction activity can be targeted for drug development.

Does the vestibular system contribute to head direction cell activity in the rat?

NASA Technical Reports Server (NTRS)

Brown, J. E.; Yates, B. J.; Taube, J. S.; Oman, C. M. (Principal Investigator)

2002-01-01

Head direction cells (HDC) located in several regions of the brain, including the anterior dorsal nucleus of the thalamus (ADN), postsubiculum (PoS), and lateral mammillary nuclei (LMN), provide the neural substrate for the determination of head direction. Although activity of HDC is influenced by various sensory signals and internally generated cues, lesion studies and some anatomical and physiological evidence suggest that vestibular inputs are critical for the maintenance of directional sensitivity of these cells. However, vestibular inputs must be transformed considerably in order to signal head direction, and the neuronal circuitry that accomplishes this signal processing has not been fully established. Furthermore, it is unclear why the removal of vestibular inputs abolishes the directional sensitivity of HDC, as visual and other sensory inputs and motor feedback signals strongly affect the firing of these neurons and would be expected to maintain their directional-related activity. Further physiological studies will be required to establish the role of vestibular system in producing HDC responses, and anatomical studies are needed to determine the neural circuitry that mediates vestibular influences on determination of head direction.

Effects of direct current electric fields on lung cancer cell electrotaxis in a PMMA-based microfluidic device.

PubMed

Li, Yaping; Xu, Tao; Chen, Xiaomei; Lin, Shin; Cho, Michael; Sun, Dong; Yang, Mengsu

2017-03-01

Tumor metastasis is the primary cause of cancer death. Numerous studies have demonstrated the electrotactic responses of various cancer cell types, and suggested its potential implications in metastasis. In this study, we used a microfluidic device to emulate endogenous direct current electric field (dcEF) environment, and studied the electrotactic migration of non-small cell lung cancer cell lines (H460, HCC827, H1299, and H1975) and the underlying mechanisms. These cell lines exhibited greatly different response in applied dcEFs (2-6 V/cm). While H460 cells (large cell carcinoma) showed slight migration toward cathode, H1299 cells (large cell carcinoma) showed increased motility and dcEF-dependent anodal migration with cell reorientation. H1975 cells (adenocarcinoma) showed dcEF-dependent cathodal migration with increased motility, and HCC827 cells (adenocarcinoma) responded positively in migration speed and reorientation but minimally in migrating directions to dcEF. Activation of MAPK and PI3K signaling pathways was found to be associated with the realignment and directed migration of lung cancer cells. In addition, both Ca 2+ influx through activated stretch-activated calcium channels (SACCs) (but not voltage-gated calcium channels, VGCCs) and Ca 2+ release from intracellular storage were involved in lung cancer cell electrotactic responses. The results demonstrated that the microfluidic device provided a stable and controllable microenvironment for cell electrotaxis study, and revealed that the electrotactic responses of lung cancer cells were heterogeneous and cell-type dependent, and multiple signals contributed to lung cancer cells electrotaxis.

Visual coding with a population of direction-selective neurons.

PubMed

Fiscella, Michele; Franke, Felix; Farrow, Karl; Müller, Jan; Roska, Botond; da Silveira, Rava Azeredo; Hierlemann, Andreas

2015-10-01

The brain decodes the visual scene from the action potentials of ∼20 retinal ganglion cell types. Among the retinal ganglion cells, direction-selective ganglion cells (DSGCs) encode motion direction. Several studies have focused on the encoding or decoding of motion direction by recording multiunit activity, mainly in the visual cortex. In this study, we simultaneously recorded from all four types of ON-OFF DSGCs of the rabbit retina using a microelectronics-based high-density microelectrode array (HDMEA) and decoded their concerted activity using probabilistic and linear decoders. Furthermore, we investigated how the modification of stimulus parameters (velocity, size, angle of moving object) and the use of different tuning curve fits influenced decoding precision. Finally, we simulated ON-OFF DSGC activity, based on real data, in order to understand how tuning curve widths and the angular distribution of the cells' preferred directions influence decoding performance. We found that probabilistic decoding strategies outperformed, on average, linear methods and that decoding precision was robust to changes in stimulus parameters such as velocity. The removal of noise correlations among cells, by random shuffling trials, caused a drop in decoding precision. Moreover, we found that tuning curves are broad in order to minimize large errors at the expense of a higher average error, and that the retinal direction-selective system would not substantially benefit, on average, from having more than four types of ON-OFF DSGCs or from a perfect alignment of the cells' preferred directions. Copyright © 2015 the American Physiological Society.

Visual coding with a population of direction-selective neurons

PubMed Central

Farrow, Karl; Müller, Jan; Roska, Botond; Azeredo da Silveira, Rava; Hierlemann, Andreas

2015-01-01

The brain decodes the visual scene from the action potentials of ∼20 retinal ganglion cell types. Among the retinal ganglion cells, direction-selective ganglion cells (DSGCs) encode motion direction. Several studies have focused on the encoding or decoding of motion direction by recording multiunit activity, mainly in the visual cortex. In this study, we simultaneously recorded from all four types of ON-OFF DSGCs of the rabbit retina using a microelectronics-based high-density microelectrode array (HDMEA) and decoded their concerted activity using probabilistic and linear decoders. Furthermore, we investigated how the modification of stimulus parameters (velocity, size, angle of moving object) and the use of different tuning curve fits influenced decoding precision. Finally, we simulated ON-OFF DSGC activity, based on real data, in order to understand how tuning curve widths and the angular distribution of the cells' preferred directions influence decoding performance. We found that probabilistic decoding strategies outperformed, on average, linear methods and that decoding precision was robust to changes in stimulus parameters such as velocity. The removal of noise correlations among cells, by random shuffling trials, caused a drop in decoding precision. Moreover, we found that tuning curves are broad in order to minimize large errors at the expense of a higher average error, and that the retinal direction-selective system would not substantially benefit, on average, from having more than four types of ON-OFF DSGCs or from a perfect alignment of the cells' preferred directions. PMID:26289471

Design of Polymeric Culture Substrates to Promote Proangiogenic Potential of Stem Cells.

PubMed

Kwon, Byeong-Ju; Wang, Xintong; Kang, Mi-Lan; You, Jin; Lee, Shin-Jeong; Kim, Won Shik; Yoon, Young-Sup; Park, Jong-Chul; Sung, Hak-Joon

2018-02-01

Stem cells are a promising cell source for regenerative medicine due to their differentiation and self-renewal capacities. In the field of regenerative medicine and tissue engineering, a variety of biomedical technologies have been tested to improve proangiogenic activities of stem cells. However, their therapeutic effect is found to be limited in the clinic because of cell loss, senescence, and insufficient therapeutic activities. To address this type of issue, advanced techniques for biomaterial synthesis and fabrication have been approached to mimic proangiogenic microenvironment and to direct proangiogenic activities. This review highlights the types of polymers and design strategies that have been studied to promote proangiogenic activities of stem cells. In particular, scaffolds, hydrogels, and surface topographies, as well as insight into their underlying mechanisms to improve proangiogenic activities are the focuses. The strategy to promote angiogenic activities of hMSCs by controlling substrate repellency is introduced, and the future direction is proposed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The biocompatibility of modified experimental Portland cements with potential for use in dentistry.

PubMed

Camilleri, J

2008-12-01

To evaluate the biocompatibility of a group of new potential dental materials and their eluants by assessing cell viability. Calcium sulpho-aluminate cement (CSA), calcium fluoro-aluminate cement (CFA) and glass-ionomer cement (GIC; Ketac Molar), used as the control, were tested for biocompatibility. Using a direct test method cell viability was measured quantitatively using alamarBluetrade mark dye, and an indirect test method where cells were grown on material elutions and cell viability was assessed using methyltetrazolium (MTT) assay as recommended by ISO 10 993-Part 5 for in vitro testing. Statistical analysis was performed by analysis of variance and Tukey multi-comparison test method. Elution collected from the prototype cements and the GIC cured for 1 and 7 days allowed high cell activity after 24 h cell exposure, which reduced after 48 h when compared to the nontoxic glass-ionomer control, but increased significantly after 72 h cell contact. Elutions collected after 28 days revealed reduced cell activity at all cell exposure times. Cells placed in direct contact with the prototype materials showed reduced cell activity when compared with the control. Cell growth was poor when seeded in direct contact with the prototype cements. GIC encouraged cell growth after 1 day of contact. The eluted species for all the cements tested exhibited adequate cell viability in the early ages with reduced cell activity at 28 days. Changes in the production of calcium hydroxide as a by-product of cement hydration affect the material biocompatibility adversely.

Glucose, epithelium, and enteric nervous system: dialogue in the dark.

PubMed

Pfannkuche, H; Gäbel, G

2009-06-01

The gastrointestinal epithelium is in close contact with the various components of the chymus, including nutrients, bacteria and toxins. The epithelial barrier has to decide which components are effectively absorbed and which components are extruded. In the small intestine, a nutrient like glucose is mainly absorbed by the sodium linked glucose cotransporter 1 (SGLT1) and the glucose transporter 2 (GLUT2). The expression and activity of both transport proteins is directly linked to the amount of intraluminal glucose. Besides the direct interaction between glucose and the enterocytes, glucose also stimulates different sensory mechanisms within the intestinal wall. The most important types of cells involved in the sensing of intraluminal contents are enteroendocrine cells and neurones of the enteric nervous system. Regarding glucosensing, a distinct type of enteroendocrine cells, the enterochromaffine (EC) cells are involved. Excitation of EC cells by intraluminal glucose results in the release of serotonin (5-HT), which modulates epithelial functions and activates enteric secretomotorneurones. Enteric neurones are not only activated by 5-HT, but also directly by glucose. The activation of different cell types and the subsequent crosstalk between these cells may trigger appropriate absorptive and secretory processes within the intestine.

Visuomotor properties of corticotectal cells in area 17 and posteromedial lateral suprasylvian (PMLS) cortex of the cat.

PubMed

Weyand, T G; Gafka, A C

2001-01-01

We studied the visuomotor activity of corticotectal (CT) cells in two visual cortical areas [area 17 and the posteromedial lateral suprasylvian cortex (PMLS)] of the cat. The cats were trained in simple oculomotor tasks, and head position was fixed. Most CT cells in both cortical areas gave a vigorous discharge to a small stimulus used to control gaze when it fell within the retinotopically defined visual field. However, the vigor of the visual response did not predict latency to initiate a saccade, saccade velocity, amplitude, or even if a saccade would be made, minimizing any potential role these cells might have in premotor or attentional processes. Most CT cells in both areas were selective for direction of stimulus motion, and cells in PMLS showed a direction preference favoring motion away from points of central gaze. CT cells did not discharge with eye movements in the dark. During eye movements in the light, many CT cells in area 17 increased their activity. In contrast, cells in PMLS, including CT cells, were generally unresponsive during saccades. Paradoxically, cells in PMLS responded vigorously to stimuli moving at saccadic velocities, indicating that the oculomotor system suppresses visual activity elicited by moving the retina across an illuminated scene. Nearly all CT cells showed oscillatory activity in the frequency range of 20-90 Hz, especially in response to visual stimuli. However, this activity was capricious; strong oscillations in one trial could disappear in the next despite identical stimulus conditions. Although the CT cells in both of these regions share many characteristics, the direction anisotropy and the suppression of activity during eye movements which characterize the neurons in PMLS suggests that these two areas have different roles in facilitating perceptual/motor processes at the level of the superior colliculus.

Heat-directed tumor cell fusion.

PubMed

Brade, Anthony M; Szmitko, Paul; Ngo, Duc; Liu, Fei-Fei; Klamut, Henry J

2003-03-20

In previous studies we demonstrated that a modified human HSP70b promoter (HSE.70b) directs high levels of gene expression to tumor cells after mild hyperthermia treatment in the range of 41.5-44 degrees C. This transcriptional targeting system exhibits low basal activity at 37 degrees C, is highly induced (950-fold) after mild heat treatment (43 degrees C/30 min), and returns to basal activity levels within 12-24 hours of activation. Here we describe heat-directed targeting of an activated form of the Gibbon ape leukemia virus env protein (GALV FMG) to tumor cells. GALV FMG mediates cell-cell fusion, and when expressed in tumor cells can produce bystander effects of up to 1:200. Transient transfection of a HSE70b.GALV FMG minigene caused extensive syncytia formation in HeLa and HT-1080 cells following mild heat treatment (44 degrees C/30 min). Stable transfection into HT-1080 cells produced a cell line (HG5) that exhibits massive syncytia formation and a 60% reduction in viability relative to a vector-only control (CI1) following heat treatment in vitro. Mild hyperthermia also resulted in syncytia formation, necrosis, and complete macroscopic regression of HG5 xenograft tumors grown in the footpads of mice with severe combined immunodeficiency disorders (SCID). Median survival increased from 12.5 (in heated CI1 controls) to 52 days after a single heat treatment. Heat-directed tumor cell fusion may prove to be a highly beneficial adjunct to existing cancer treatment strategies that take advantage of the synergistic interaction between mild hyperthermia and radiation or chemotherapeutic drugs.

Planar cell polarity controls directional Notch signaling in the Drosophila leg

PubMed Central

Capilla, Amalia; Johnson, Ruth; Daniels, Maki; Benavente, María; Bray, Sarah J.; Galindo, Máximo Ibo

2012-01-01

The generation of functional structures during development requires tight spatial regulation of signaling pathways. Thus, in Drosophila legs, in which Notch pathway activity is required to specify joints, only cells distal to ligand-producing cells are capable of responding. Here, we show that the asymmetric distribution of planar cell polarity (PCP) proteins correlates with this spatial restriction of Notch activation. Frizzled and Dishevelled are enriched at distal sides of each cell and hence localize at the interface with ligand-expressing cells in the non-responding cells. Elimination of PCP gene function in cells proximal to ligand-expressing cells is sufficient to alleviate the repression, resulting in ectopic Notch activity and ectopic joint formation. Mutations that compromise a direct interaction between Dishevelled and Notch reduce the efficacy of repression. Likewise, increased Rab5 levels or dominant-negative Deltex can suppress the ectopic joints. Together, these results suggest that PCP coordinates the spatial activity of the Notch pathway by regulating endocytic trafficking of the receptor. PMID:22736244

Protein-scaffold Directed Nanoscale Assembly of T Cell Ligands: Artificial Antigen Presentation with Defined Valency, Density and Ratio.

PubMed

Smith, Mason R; Tolbert, Stephanie V; Wen, Fei

2018-05-07

Tuning antigen presentation to T cells is a critical step in investigating key aspects of T cell activation. However, existing technologies have limited ability to control the spatial and stoichiometric organization of T cell ligands on 3D surfaces. Here, we developed an artificial antigen presentation platform based on protein-scaffold directed assembly that allows fine control over the spatial and stoichiometric organization of T cell ligands on a 3D yeast-cell surface. Using this system, we observed that the T cell activation threshold on a 3D surface is independent of peptide-major histocompatibility complex (pMHC) valency, but instead determined by the overall pMHC surface density. When intercellular adhesion molecule 1 (ICAM-1) was co-assembled with pMHC, it enhanced antigen recognition sensitivity by 6-fold. Further, T cells responded with different magnitudes to varying ratios of pMHC and ICAM-1 and exhibited a maximum response at a ratio of 15% pMHC and 85% ICAM-1, introducing an additional parameter for tuning T cell activation. This protein-scaffold directed assembly technology is readily transferrable to acellular surfaces for translational research as well as large-scale T-cell manufacturing.

Mechanical regulation of stem-cell differentiation by the stretch-activated Piezo channel.

PubMed

He, Li; Si, Guangwei; Huang, Jiuhong; Samuel, Aravinthan D T; Perrimon, Norbert

2018-03-01

Somatic stem cells constantly adjust their self-renewal and lineage commitment by integrating various environmental cues to maintain tissue homeostasis. Although numerous chemical and biological signals have been identified that regulate stem-cell behaviour, whether stem cells can directly sense mechanical signals in vivo remains unclear. Here we show that mechanical stress regulates stem-cell differentiation in the adult Drosophila midgut through the stretch-activated ion channel Piezo. We find that Piezo is specifically expressed in previously unidentified enteroendocrine precursor cells, which have reduced proliferation ability and are destined to become enteroendocrine cells. Loss of Piezo activity reduces the generation of enteroendocrine cells in the adult midgut. In addition, ectopic expression of Piezo in all stem cells triggers both cell proliferation and enteroendocrine cell differentiation. Both the Piezo mutant and overexpression phenotypes can be rescued by manipulation of cytosolic Ca 2+ levels, and increases in cytosolic Ca 2+ resemble the Piezo overexpression phenotype, suggesting that Piezo functions through Ca 2+ signalling. Further studies suggest that Ca 2+ signalling promotes stem-cell proliferation and differentiation through separate pathways. Finally, Piezo is required for both mechanical activation of stem cells in a gut expansion assay and the increase of cytosolic Ca 2+ in response to direct mechanical stimulus in a gut compression assay. Thus, our study demonstrates the existence of a specific group of stem cells in the fly midgut that can directly sense mechanical signals through Piezo.

Old and new facts about hyperthermia-induced modulations of the immune system.

PubMed

Frey, Benjamin; Weiss, Eva-Maria; Rubner, Yvonne; Wunderlich, Roland; Ott, Oliver J; Sauer, Rolf; Fietkau, Rainer; Gaipl, Udo S

2012-01-01

Hyperthermia (HT) is a potent sensitiser for radiotherapy (RT) and chemotherapy (CT) and has been proven to modulate directly or indirectly cells of the innate and adaptive immune system. We will focus in this article on how anti-tumour immunity can be induced by HT. In contrast to some in vitro assays, in vivo examinations showed that natural killer cells and phagocytes like granulocytes are directly activated against the tumour by HT. Since heat also activates dendritic cells (DCs), HT should be combined with further death stimuli (RT, CT or immune therapy) to allocate tumour antigen, derived from, for example, necrotic tumour cells, for uptake by DCs. We will outline that induction of immunogenic tumour cells and direct tumour cell killing by HT in combination with other therapies contributes to immune activation against the tumour. Studies will be presented showing that non-beneficial effects of HT on immune cells are mostly timely restricted. A special focus is set on immune activation mediated by extracellular present heat shock proteins (HSPs) carrying tumour antigens and further danger signals released by dying tumour cells. Local HT treatment in addition to further stress stimuli exerts abscopal effects and might be considered as in situ tumour vaccination. An increased natural killer (NK) cell activity, lymphocyte infiltration and HSP-mediated induction of immunogenic tumour cells have been observed in patients. Treatments with the addition of HT therefore can be considered as a personalised cancer treatment approach by specifically activating the immune system against the individual unique tumour.

Infectious rotavirus enters cells by direct cell membrane penetration, not by endocytosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaljot, K.T.; Shaw, R.D.; Greenberg, H.B.

1988-04-01

Rotaviruses are icosahedral viruses with a segmented, double-stranded RNA genome. They are the major cause of severe infantile infectious diarrhea. Rotavirus growth in tissue culture is markedly enhanced by pretreatment of virus with trypsin. Trypsin activation is associated with cleavage of the viral hemagglutinin (viral protein 3 (VP3); 88 kilodaltons) into two fragments (60 and 28 kilodaltons). The mechanism by which proteolytic cleavage leads to enhanced growth is unknown. To determine whether trypsin treatment affected rotavirus internalization, the authors studied the kinetics of entry of infectious rhesus rotavirus (RRV) into MA104 cells. Trypsin-activated RRV was internalized with a half-time ofmore » 3 to 5 min, while nonactivated virus disappeared from the cell surface with a half-time of 30 to 50 min. In contrast to trypsin-activated RRV, loss of nonactivated RRV from the cell surface did not result in the appearance of infection, as measured by plaque formation. Purified trypsin-activated RRV added to cell monolayers at pH 7.4 mediated {sup 51}Cr, ({sup 14}C)choline, and ({sup 3}H)inositol released from prelabeled MA104 cells. This release could be specifically blocked by neutralizing antibodies to VP3. These results suggest that MA104 cell infection follows the rapid entry of trypsin-activated RRV by direct cell membrane penetration. Cell membrane penetration of infectious RRV is initiated by trypsin cleavage of VP3. Neutralizing antibodies can inhibit this direct membrane penetration.« less

Pd and polyaniline nanocomposite on carbon fiber paper as an efficient direct formic acid fuel cell anode

NASA Astrophysics Data System (ADS)

Pandey, Rakesh K.

2018-03-01

Direct formic acid fuel cells are advantageous as portable power generating devices. In the present work, an anode catalyst for direct formic acid fuel cell (DFAFC) is presented which has good catalytic activity for formic acid oxidation. The catalyst is composed of Pd and conducting polymer polyaniline (Pd-PANI) nanocomposite. The catalyst was prepared by using a single step galvanostatic electrochemical deposition method. The Pd-PANI catalyst was electrodeposited at different time durations and a comparison of the catalytic activity at each deposition time was carried out and optimized.

The PBX1 lupus susceptibility gene regulates CD44 expression

PubMed Central

Niu, Yuxin; Sengupta, Mayami; Titov, Anton A.; Choi, Seung-Chul; Morel, Laurence

2017-01-01

PBX1-d is novel splice isoform of pre-B-cell leukemia homeobox 1 (PBX1) that lacks its DNA-binding and Hox-binding domains, and functions as a dominant negative. We have shown that PBX1-d expression in CD4+ T cells is associated with systemic lupus erythematosus (SLE) in a mouse model as well as in human subjects. More specifically, PBX1-d expression leads to the production of autoreactive activated CD4+ T cells, a reduced frequency and function of Foxp3+ regulatory T (Treg) cells and an expansion of follicular helper T (Tfh) cells. Very little is known about the function of PBX1 in T cells, except that it directly regulates the expression of miRNAs associated with Treg and Tfh homeostasis. In the present study, we show that PBX1 directly regulated the expression of CD44, a marker of T cell activation. Two PBX1 binding sites in the promoter directly regulated CD44 expression, with PBX1-d driving a higher expression than the normal isoform PBX1-b. In addition, mutations in each of the two binding sites had different effects of PBX1-b and PBX1-d. Finally, we showed that an enhanced recruitment of co-factor MEIS by PBX1-d over PBX1-b, while there was no difference for co-factor PREP1 recruitment. Therefore, this study demonstrates that the lupus-associated PBX1-d isoform directly transactivates CD44, a marker of CD44 activation and memory, and that it has different DNA binding and co-factor recruitment relative to the normal isoform. Taken together, these results confirm that PBX1 directly regulates genes related to T cell activation and show that the lupus-associated isoform PBX1-d has unique molecular functions. PMID:28257976

Direct targeting of MEK1/2 and RSK2 by silybin induces cell cycle arrest and inhibits melanoma cell growth

PubMed Central

Lee, Mee-Hyun; Huang, Zunnan; Kim, Dong Joon; Kim, Sung-Hyun; Kim, Myoung Ok; Lee, Sung-Young; Xie, Hua; Park, Si Jun; Kim, Jae Young; Kundu, Joydeb Kumar; Bode, Ann M.; Surh, Young-Joon; Dong, Zigang

2013-01-01

Abnormal functioning of multiple gene products underlies the neoplastic transformation of cells. Thus, chemopreventive and/or chemotherapeutic agents with multigene targets hold promise in the development of effective anticancer drugs. Silybin, a component of milk thistle, is a natural anticancer agent. In the present study, we investigated the effect of silybin on melanoma cell growth and elucidated its molecular targets. Our study revealed that silybin attenuated the growth of melanoma xenograft tumors in nude mice. Silybin inhibited the kinase activity of mitogen-activated protein kinase kinase (MEK)-1/2 and ribosomal S6 kinase (RSK)-2 in melanoma cells. The direct binding of silybin with MEK1/2 and RSK2 was explored using a computational docking model. Treatment of melanoma cells with silybin attenuated the phosphorylation of extracellular signal-regulated kinase (ERK)-1/2 and RSK2, which are regulated by the upstream kinases MEK1/2. The blockade of MEK1/2-ERK1/2-RSK2 signaling by silybin resulted in a reduced activation of nuclear factor-kappaB, activator protein-1 and signal transducer and activator of transcription-3, which are transcriptional regulators of a variety of proliferative genes in melanomas. Silybin, by blocking the activation of these transcription factors, induced cell cycle arrest at the G1 phase and inhibited melanoma cell growth in vitro and in vivo. Taken together, silybin suppresses melanoma growth by directly targeting MEK- and RSK-mediated signaling pathways. PMID:23447564

Casp8p41 generated by HIV protease kills CD4 T cells through direct Bak activation

PubMed Central

Sainski, Amy M.; Dai, Haiming; Natesampillai, Sekar; Pang, Yuan-Ping; Bren, Gary D.; Cummins, Nathan W.; Correia, Cristina; Meng, X. Wei; Tarara, James E.; Ramirez-Alvarado, Marina; Katzmann, David J.; Ochsenbauer, Christina; Kappes, John C.

2014-01-01

Previous studies have shown that human immunodeficiency virus (HIV) protease cleaves procaspase 8 to a fragment, termed Casp8p41, that lacks caspase activity but nonetheless contributes to T cell apoptosis. Herein, we show that Casp8p41 contains a domain that interacts with the BH3-binding groove of pro-apoptotic Bak to cause Bak oligomerization, Bak-mediated membrane permeabilization, and cell death. Levels of active Bak are higher in HIV-infected T cells that express Casp8p41. Conversely, targeted mutations in the Bak-interacting domain diminish Bak binding and Casp8p41-mediated cell death. Similar mutations in procaspase 8 impair the ability of HIV to kill infected T cells. These observations support a novel paradigm in which HIV converts a normal cellular constituent into a direct activator that functions like a BH3-only protein. PMID:25246614

The role of the micro-pattern and nano-topography of hydroxyapatite bioceramics on stimulating osteogenic differentiation of mesenchymal stem cells.

PubMed

Zhao, Cancan; Wang, Xiaoya; Gao, Long; Jing, Linguo; Zhou, Quan; Chang, Jiang

2018-06-01

The micro/nano hybrid structure is considered to be a biomaterial characteristic to stimulate osteogenesis by mimicking the three-dimensional structure of the bone matrix. However, the mechanism of the hybrid structure induced osteogenic differentiation of stem cells is still unknown. For elucidating the mechanisms, one of the challenge is to directly fabricate micro/nano hybrid structure on bioceramics because of its brittleness. In this study, hydroxyapatite (HA) bioceramics with the micro/nano hybrid structure were firstly fabricated via a hydrothermal treatment and template method, and the effect of the different surface structures on the expression of integrins, BMP2 signaling pathways and cell-cell communication was investigated. Interestingly, the results suggested that the osteogenic differentiation induced by micro/nano structures was modulated first through activating integrins and then further activating BMP2 signaling pathway and cell-cell communication, while activated BMP2 could in turn activate integrins and Cx43-related cell-cell communication. Furthermore, differences in activation of integrins, BMP2 signaling pathway, and gap junction-mediated cell-cell communication were observed, in which nanorod and micropattern structures activated different integrin subunits, BMP downstream receptors and Cx43. This finding may explain the synergistic effect of the micro/nano hybrid structure on the activation of osteogenic differentiation of BMSCs. Based on our study, we concluded that the different activation mechanisms of micro- and nano-structures led to the synergistic stimulatory effect on integrin activation and osteogenesis, in which not only the direct contact of cells on micro/nano structure played an important role, but also other surface characteristics such as protein adsorption might contribute to the bioactive effect. The micro/nano hybrid structure has been found to have synergistic bioactivity on osteogenesis. However, it is still a challenge to fabricate the hybrid structure directly on the bioceramics, and the role of micro- and nano-structure, in particular the mechanism of the micro/nano-hybrid structure induced stem cell differentiation is still unknown. In this study, we firstly fabricated hydroxyapatite bioceramics with the micro/nano hybrid structure, and then investigated the effect of different surface structure on expression of integrins, BMP2 signaling pathways and cell-cell communication. Interestingly, we found that the osteogenic differentiation induced by structure was modulated first through activating integrins and then further activating BMP2 signaling pathway and cell-cell communication, and activated BMP2 could in turn activate some integrin subunits and Cx43-related cell-cell communication. Furthermore, differences in activation of integrins, BMP2 signaling pathway, and gap junction-mediated cell-cell communication were observed, in which nanorod and micropattern structures activated different integrin subunits, BMP downstream receptors and Cx43. This finding may explain the synergistic effect of the micro/nano hybrid structure on the activation of osteogenic differentiation of BMSCs. Based on our study, we concluded that the different activation mechanisms of micro- and nano-structures led to the synergistic stimulatory effect on integrin activation and osteogenesis, in which not only the direct contact of cells on micro/nano structure played an important role, but also other surface characteristics such as protein adsorption might contribute to the bioactive effect. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Protein Tyrosine Phosphatase-PEST and β8 Integrin Regulate Spatiotemporal Patterns of RhoGDI1 Activation in Migrating Cells

PubMed Central

Lee, Hye Shin; Cheerathodi, Mujeeburahiman; Chaki, Sankar P.; Reyes, Steve B.; Zheng, Yanhua; Lu, Zhimin; Paidassi, Helena; DerMardirossian, Celine; Lacy-Hulbert, Adam; Rivera, Gonzalo M.

2015-01-01

Directional cell motility is essential for normal development and physiology, although how motile cells spatiotemporally activate signaling events remains largely unknown. Here, we have characterized an adhesion and signaling unit comprised of protein tyrosine phosphatase (PTP)-PEST and the extracellular matrix (ECM) adhesion receptor β8 integrin that plays essential roles in directional cell motility. β8 integrin and PTP-PEST form protein complexes at the leading edge of migrating cells and balance patterns of Rac1 and Cdc42 signaling by controlling the subcellular localization and phosphorylation status of Rho GDP dissociation inhibitor 1 (RhoGDI1). Translocation of Src-phosphorylated RhoGDI1 to the cell's leading edge promotes local activation of Rac1 and Cdc42, whereas dephosphorylation of RhoGDI1 by integrin-bound PTP-PEST promotes RhoGDI1 release from the membrane and sequestration of inactive Rac1/Cdc42 in the cytoplasm. Collectively, these data reveal a finely tuned regulatory mechanism for controlling signaling events at the leading edge of directionally migrating cells. PMID:25666508

Low-dose ionizing radiation induces direct activation of natural killer cells and provides a novel approach for adoptive cellular immunotherapy.

PubMed

Yang, Guozi; Kong, Qingyu; Wang, Guanjun; Jin, Haofan; Zhou, Lei; Yu, Dehai; Niu, Chao; Han, Wei; Li, Wei; Cui, Jiuwei

2014-12-01

Recent evidence indicates that limited availability and cytotoxicity have restricted the development of natural killer (NK) cells in adoptive cellular immunotherapy (ACI). While it has been reported that low-dose ionizing radiation (LDIR) could enhance the immune response in animal studies, the influence of LDIR at the cellular level has been less well defined. In this study, the authors aim to investigate the direct effects of LDIR on NK cells and the potential mechanism, and explore the application of activation and expansion of NK cells by LDIR in ACI. The authors found that expansion and cytotoxicity of NK cells were markedly augmented by LDIR. The levels of IFN-γ and TNF-α in the supernatants of cultured NK cells were significantly increased after LDIR. Additionally, the effect of the P38 inhibitor (SB203580) significantly decreased the expanded NK cell cytotoxicity, cytokine levels, and expression levels of FasL and perforin. These findings indicate that LDIR induces a direct expansion and activation of NK cells through possibly the P38-MAPK pathway, which provides a potential mechanism for stimulation of NK cells by LDIR and a novel but simplified approach for ACI.

Differential activation of human T cells to allogeneic endothelial cells, epithelial cells and fibroblasts in vitro

PubMed Central

2012-01-01

Background In the direct pathway, T cells recognize intact donor major histocompatability complexes and allogeneic peptide on the surface of donor antigen presenting cells (APCs). Indirect allorecognition results from the recognition of processed alloantigen by self MHC complexes on self APCs. In this study, we wished to evaluate the relative contribution of different intragraft cells to the alloactivation of nave and memory T cells though the direct and the indirect pathway of allorecognition. Methods The processing of membrane fragments from IFN-treated single donor endothelial cells (EC), fibroblasts or renal epithelial cells (RPTEC) was evaluated by DiOC labeling of each cell type and flow cytometry following interaction with PBMC. Direct pathway activation of nave CD45RA+ or memory CD45RO+ CD4+ T cells was evaluated following coculture with IFN-treated and MHC class II-expressing EC, fibroblasts or RPTEC. Indirect pathway activation was assessed using CD45RA+ or CD45RO+ CD4+ T cells cocultured with autologous irradiated APCs in the absence or presence of sonicates derived from IFN-treated allogeneic EC, fibroblasts or RPTEC. Activation of T cells was assessed by [3H]thymidine incorporation and by ELISpot assays. Results We find that CD14+ APCs readily acquire membrane fragments from fibroblasts and RPTEC, but fail to acquire membrane fragments from intact EC. However, APCs process membranes from EC undergoing apoptosis.There was a notable direct pathway alloproliferative response of CD45RO+ CD4+ T cells to IFN-treated EC, but not to fibroblasts or RPTEC. Also, there was a minimal direct pathway response of CD45RA+ CD4+ T cells to all cell types. In contrast, we found that both CD45RA+ and CD45RO+ CD4+ T cells proliferated following coculture with autologous APCs in the presence of sonicates derived from IFN-treated EC, fibroblasts or RPTEC. By ELISpot, we found that these T cells stimulated via the indirect pathway also produced the cytokines IFN, IL-2, IL-4 and IL-5. Conclusions Recipient APCs may readily process membrane fragments from allogeneic intragraft cells, but not from EC unless they are undergoing apoptosis. This processing is sufficient for indirect pathway alloactivation of both CD45RA+ and CD45RO+ CD4+ T cells. Only graft vascular EC mediate direct pathway reactivation of CD4+ T cells. PMID:23369287

High-activity PtRuPd/C catalyst for direct dimethyl ether fuel cells.

PubMed

Li, Qing; Wen, Xiaodong; Wu, Gang; Chung, Hoon T; Gao, Rui; Zelenay, Piotr

2015-06-22

Dimethyl ether (DME) has been considered as a promising alternative fuel for direct-feed fuel cells but lack of an efficient DME oxidation electrocatalyst has remained the challenge for the commercialization of the direct DME fuel cell. The commonly studied binary PtRu catalyst shows much lower activity in DME than methanol oxidation. In this work, guided by density functional theory (DFT) calculation, a ternary carbon-supported PtRuPd catalyst was designed and synthesized for DME electrooxidation. DFT calculations indicated that Pd in the ternary PtRuPd catalyst is capable of significantly decreasing the activation energy of the CO and CH bond scission during the oxidation process. As evidenced by both electrochemical measurements in an aqueous electrolyte and polymer-electrolyte fuel cell testing, the ternary catalyst shows much higher activity (two-fold enhancement at 0.5 V in fuel cells) than the state-of-the-art binary Pt50 Ru50 /C catalyst (HiSPEC 12100). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Estrogen-related receptor α decreases RHOA stability to induce orientated cell migration

PubMed Central

Sailland, Juliette; Tribollet, Violaine; Forcet, Christelle; Billon, Cyrielle; Barenton, Bruno; Carnesecchi, Julie; Bachmann, Alice; Gauthier, Karine Cécile; Yu, Shan; Giguère, Vincent; Chan, Franky L.; Vanacker, Jean-Marc

2014-01-01

Several physiopathological processes require orientated cellular migration. This phenomenon highly depends on members of the RHO family of GTPases. Both excessive and deficient RHO activity impair directional migration. A tight control is thus exerted on these proteins through the regulation of their activation and of their stability. Here we show that the estrogen-related receptor α (ERRα) directly activates the expression of TNFAIP1, the product of which [BTB/POZ domain-containing adapter for Cullin3-mediated RhoA degradation 2 (BACURD2)] regulates RHOA protein turnover. Inactivation of the receptor leads to enhanced RHOA stability and activation. This results in cell disorientation, increased actin network, and inability to form a lamellipodium at the migration edge. As a consequence, directional migration, but not cell motility per se, is impaired in the absence of the receptor, under pathological as well as physiological conditions. Altogether, our results show that the control exerted by ERRα on RHOA stability is required for directional migration. PMID:25288732

Estrogen-related receptor α decreases RHOA stability to induce orientated cell migration.

PubMed

Sailland, Juliette; Tribollet, Violaine; Forcet, Christelle; Billon, Cyrielle; Barenton, Bruno; Carnesecchi, Julie; Bachmann, Alice; Gauthier, Karine Cécile; Yu, Shan; Giguère, Vincent; Chan, Franky L; Vanacker, Jean-Marc

2014-10-21

Several physiopathological processes require orientated cellular migration. This phenomenon highly depends on members of the RHO family of GTPases. Both excessive and deficient RHO activity impair directional migration. A tight control is thus exerted on these proteins through the regulation of their activation and of their stability. Here we show that the estrogen-related receptor α (ERRα) directly activates the expression of TNFAIP1, the product of which [BTB/POZ domain-containing adapter for Cullin3-mediated RhoA degradation 2 (BACURD2)] regulates RHOA protein turnover. Inactivation of the receptor leads to enhanced RHOA stability and activation. This results in cell disorientation, increased actin network, and inability to form a lamellipodium at the migration edge. As a consequence, directional migration, but not cell motility per se, is impaired in the absence of the receptor, under pathological as well as physiological conditions. Altogether, our results show that the control exerted by ERRα on RHOA stability is required for directional migration.

Endothelial connexin 32 regulates tissue factor expression induced by inflammatory stimulation and direct cell-cell interaction with activated cells.

PubMed

Okamoto, Takayuki; Akita, Nobuyuki; Hayashi, Tatsuya; Shimaoka, Motomu; Suzuki, Koji

2014-10-01

Endothelial cell (EC) interacts with adjacent EC through gap junction, and abnormal expression or function of Cxs is associated with cardiovascular diseases. In patients with endothelial dysfunction, the up-regulation of tissue factor (TF) expression promotes the pathogenic activation of blood coagulation, however the relationship between gap junctions and TF expression in ECs remains uncharacterized. ECs express the gap junction (GJ) proteins connexin32 (Cx32), Cx37, Cx40 and Cx43. We investigated the role of endothelial gap junctions, particularly Cx32, in modulating TF expression during vascular inflammation. Human umbilical vein endothelial cells (HUVECs) were stimulated with tumor necrosis factor-α (TNF-α) and TF activity was assessed in the presence of GJ blockers and an inhibitory anti-Cx32 monoclonal antibody. Treatment with GJ blockers and anti-Cx32 monoclonal antibody enhanced the TNF-α-induced TF activity and mRNA expression in HUVECs. TNF-α-activated effector HUVECs or mouse MS-1 cells were co-cultured with non-stimulated acceptor HUVECs and TF expression in acceptor HUVECs was detected. Effector EC induced TF expression in adjacent acceptor HUVECs through direct cell-cell interaction. Cell-cell interaction induced TF expression was reduced by anti-intercellular adhesion molecule-1 (ICAM1) monoclonal antibody. Soluble ICAM1-Fc fusion protein promotes TF expression. GJ blockers and anti-Cx32 monoclonal antibody enhanced TF expression induced by cell-cell interaction and ICAM1-Fc treatment. Blockade of endothelial Cx32 increased TF expression induced by TNF-α stimulation and cell-cell interaction which was at least partly dependent upon ICAM1. These results suggest that direct Cx32-mediated interaction modulates TF expression in ECs during vascular inflammation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

In situ elasticity modulation with dynamic substrates to direct cell phenotype

PubMed Central

Kloxin, April M.; Benton, Julie A.; Anseth, Kristi S.

2009-01-01

Microenvironment elasticity influences critical cell functions such as differentiation, cytoskeletal organization, and process extension. Unfortunately, few materials allow elasticity modulation in real-time to probe its direct effect on these dynamic cellular processes. Here, a new approach is presented for the photochemical modulation of elasticity within the cell's microenvironment at any point in time. A photodegradable hydrogel was irradiated and degraded under cytocompatible conditions to generate a wide range of elastic moduli similar to soft tissues and characterized using rheometry and atomic force microscopy (AFM). The effect of the elastic modulus on valvular interstitial cell (VIC) activation into myofibroblasts was explored. In these studies, gradient samples were used to identify moduli that either promote or suppress VIC myofibroblastic activation. With this knowledge, VICs were cultured on a high modulus, activating hydrogel substrate, and uniquely, results show that decreasing the substrate modulus with irradiation reverses this activation, demonstrating that myofibroblasts can be de-activated solely by changing the modulus of the underlying substrate. This finding is important for the rational design of biomaterials for tissue regeneration and offers insight into fibrotic disease progression. These photodegradable hydrogels demonstrate the capability to both probe and direct cell function through dynamic changes in substrate elasticity. PMID:19788947

Activation of the innate immune receptor Dectin-1 upon formation of a “phagocytic synapse”

PubMed Central

Goodridge, Helen S.; Reyes, Christopher N.; Becker, Courtney A.; Katsumoto, Tamiko R.; Ma, Jun; Wolf, Andrea J.; Bose, Nandita; Chan, Anissa S. H.; Magee, Andrew S.; Danielson, Michael E.; Weiss, Arthur; Vasilakos, John P.; Underhill, David M.

2011-01-01

Innate immune cells must be able to distinguish between direct binding to microbes and detection of components shed from the surface of microbes located at a distance. Dectin-1 is a pattern recognition receptor expressed by myeloid phagocytes (macrophages, dendritic cells and neutrophils) that detects β-glucans in fungal cell walls and triggers direct cellular anti-microbial activity, including phagocytosis and production of reactive oxygen species1, 2. In contrast to inflammatory responses stimulated upon detection of soluble ligands by other pattern recognition receptors, such as Toll-like receptors (TLRs), these responses are only useful when a cell comes into direct contact with a microbe and must not be spuriously activated by soluble stimuli. In this study we show that despite its ability to bind both soluble and particulate β-glucan polymers, Dectin-1 signalling is only activated by particulate β-glucans, which cluster the receptor in synapse-like structures from which regulatory tyrosine phosphatases CD45 and CD148 are excluded (Supplementary Figure 1). The “phagocytic synapse” now provides a model mechanism by which innate immune receptors can distinguish direct microbial contact from detection of microbes at a distance, thereby initiating direct cellular anti-microbial responses only when they are required. PMID:21525931

LIM Protein Ajuba associates with the RPA complex through direct cell cycle-dependent interaction with the RPA70 subunit.

PubMed

Fowler, Sandy; Maguin, Pascal; Kalan, Sampada; Loayza, Diego

2018-06-22

DNA damage response pathways are essential for genome stability and cell survival. Specifically, the ATR kinase is activated by DNA replication stress. An early event in this activation is the recruitment and phosphorylation of RPA, a single stranded DNA binding complex composed of three subunits, RPA70, RPA32 and RPA14. We have previously shown that the LIM protein Ajuba associates with RPA, and that depletion of Ajuba leads to potent activation of ATR. In this study, we provide evidence that the Ajuba-RPA interaction occurs through direct protein contact with RPA70, and that their association is cell cycle-regulated and is reduced upon DNA replication stress. We propose a model in which Ajuba negatively regulates the ATR pathway by directly interacting with RPA70, thereby preventing inappropriate ATR activation. Our results provide a framework to further our understanding of the mechanism of ATR regulation in human cells in the context of cellular transformation.

Baculovirus directly activates murine NK cells via TLR9.

PubMed

Moriyama, T; Suzuki, T; Chang, M O; Kitajima, M; Takaku, H

2017-04-01

The importance of natural killer (NK) cells in innate immune responses against tumors or viral infections enhances the appeal of NK cell-based immunotherapeutic approaches. We have recently reported that baculovirus (BV)-infected dendritic cells (DCs; BV-DCs) induce antitumor immunity against established tumors in mice. These antitumor effects were CD8 + T-cell and NK cell dependent; however, they were found to be CD4 + T-cell independent. In this study, we investigated the involvement of Toll-like receptor 9 (TLR9) in the process of BV recognition by NK cells. We found that BV directly stimulated NK cells, induced the expression of the activation marker CD69 and promoted interferon-gamma (IFN-γ) production and cytotoxicity. Moreover, TLR9 knockout in mice (tlr9-/- NK cells) inhibited NK cell responses to BV, indicating that TLR9 may have a relevant role in the BV-induced upregulation of NK cell functions. Our data demonstrated for the first time that NK cells directly recognize BV via TLR9, which provides opportunities for the use of this technique as an effective tool for BV-based immunotherapies against malignancies.

Modulation of innate and adaptive cellular immunity relevant to HIV-1 vaccine design by seminal plasma.

PubMed

Selva, Kevin J; Kent, Stephen J; Parsons, Matthew S

2017-01-28

Mucosal exposure to HIV-1 infection generally occurs in the presence of semen. Immunomodulation by seminal plasma is well described in the reproductive biology literature. Little is known, however, about the impact of seminal plasma on innate and adaptive anti-HIV-1 cellular immunity. The study investigated the effects of seminal plasma on immune responses considered important for prophylactic HIV-1 vaccine development, namely innate and adaptive cellular immunity mediated by natural killer (NK) cells and T cells, respectively. The ability of seminal plasma to modulate direct, antibody-dependent and cytokine-stimulated NK cell activation was assessed utilizing intracellular cytokine staining. Direct and antibody-dependent cellular cytotoxicity was assessed using lactate dehydrogenase release assays. The effects of seminal plasma on T-cell activation upon stimulation with staphylococcus enterotoxin B or HIV-1 Gag peptides were assessed by intracellular cytokine staining. The impact of seminal plasma on redirected cytolysis mediated by T cells was measured using lactate dehydrogenase release assays. Both direct and antibody-dependent NK cell activation were dramatically impaired by the presence of either HIV-1-uninfected or HIV-1-infected seminal plasma in a dose-dependent manner. Additionally, seminal plasma suppressed both direct and antibody-dependent NK cell-mediated cytolysis, including anti-HIV-1 antibody-dependent cytolysis of gp120-pulsed CEM.NKr-CCR5 cells. Finally, seminal plasma attenuated both HIV-1 Gag-specific and staphylococcus enterotoxin B-induced CTL activation. Semen contains potent immunosuppressors of both NK cell and CD8 T-cell-mediated anti-HIV-1 immune responses. This could impede attempts to provide vaccine-induced immunity to HIV-1.

Lysosome-Dependent Activation of Human Dendritic Cells by the Vaccine Adjuvant QS-21

PubMed Central

Welsby, Iain; Detienne, Sophie; N’Kuli, Francisca; Thomas, Séverine; Wouters, Sandrine; Bechtold, Viviane; De Wit, Dominique; Gineste, Romain; Reinheckel, Thomas; Elouahabi, Abdelatif; Courtoy, Pierre J.; Didierlaurent, Arnaud M.; Goriely, Stanislas

2017-01-01

The adjuvant properties of the saponin QS-21 have been known for decades. It is a component of the Adjuvant System AS01 that is used in several vaccine candidates. QS-21 strongly potentiates both cellular and humoral immune responses to purified antigens, yet how it activates immune cells is largely unknown. Here, we report that QS-21 directly activated human monocyte-derived dendritic cells (moDCs) and promoted a pro-inflammatory transcriptional program. Cholesterol-dependent QS-21 endocytosis followed by lysosomal destabilization and Syk kinase activation were prerequisites for this response. Cathepsin B, a lysosomal cysteine protease, was essential for moDC activation in vitro and contributed to the adjuvant effects of QS-21 in vivo. Collectively, these findings provide new insights into the pathways involved in the direct activation of antigen-presenting cells by a clinically relevant QS-21 formulation. PMID:28105029

Role of natural killer cells in antibacterial immunity.

PubMed

Schmidt, Stanislaw; Ullrich, Evelyn; Bochennek, Konrad; Zimmermann, Stefanie-Yvonne; Lehrnbecher, Thomas

2016-12-01

Bacteria are a significant cause of infectious complications, in particular in immunocompromised patients. There is an increasing understanding that Natural Killer (NK) cells not only exhibit direct activity against bacteria, but also exert indirect antibacterial activity through interaction with other immune cells via cytokines and interferons. Areas covered: This review seeks to give a global overview of in vitro and in vivo data how NK cells interact with bacteria. In this regard, the review describes how NK cells directly damage and kill bacteria by soluble factors such as perforin, the impact of NK cells on other arms of the immune system, as well as how bacteria may inhibit NK cell activities. Expert commentary: A better characterization of the antibacterial effects of NK cells is urgently needed. With a better understanding of the interaction of NK cells and bacteria, NK cells may become a promising tool to prevent or to combat bacterial infections, e.g. by adoptively transferring NK cells to immunocompromised patients.

O-linked β-N-acetylglucosamine transferase directs cell proliferation in idiopathic pulmonary arterial hypertension.

PubMed

Barnes, Jarrod W; Tian, Liping; Heresi, Gustavo A; Farver, Carol F; Asosingh, Kewal; Comhair, Suzy A A; Aulak, Kulwant S; Dweik, Raed A

2015-04-07

Idiopathic pulmonary arterial hypertension (IPAH) is a cardiopulmonary disease characterized by cellular proliferation and vascular remodeling. A more recently recognized characteristic of the disease is the dysregulation of glucose metabolism. The primary link between altered glucose metabolism and cell proliferation in IPAH has not been elucidated. We aimed to determine the relationship between glucose metabolism and smooth muscle cell proliferation in IPAH. Human IPAH and control patient lung tissues and pulmonary artery smooth muscle cells (PASMCs) were used to analyze a specific pathway of glucose metabolism, the hexosamine biosynthetic pathway. We measured the levels of O-linked β-N-acetylglucosamine modification, O-linked β-N-acetylglucosamine transferase (OGT), and O-linked β-N-acetylglucosamine hydrolase in control and IPAH cells and tissues. Our data suggest that the activation of the hexosamine biosynthetic pathway directly increased OGT levels and activity, triggering changes in glycosylation and PASMC proliferation. Partial knockdown of OGT in IPAH PASMCs resulted in reduced global O-linked β-N-acetylglucosamine modification levels and abrogated PASMC proliferation. The increased proliferation observed in IPAH PASMCs was directly impacted by proteolytic activation of the cell cycle regulator, host cell factor-1. Our data demonstrate that hexosamine biosynthetic pathway flux is increased in IPAH and drives OGT-facilitated PASMC proliferation through specific proteolysis and direct activation of host cell factor-1. These findings establish a novel regulatory role for OGT in IPAH, shed a new light on our understanding of the disease pathobiology, and provide opportunities to design novel therapeutic strategies for IPAH. © 2015 American Heart Association, Inc.

Reovirus-Mediated Cytotoxicity and Enhancement of Innate Immune Responses Against Acute Myeloid Leukemia

PubMed Central

Hall, Kathryn; Scott, Karen J.; Rose, Ailsa; Desborough, Michael; Harrington, Kevin; Pandha, Hardev; Parrish, Christopher; Vile, Richard; Coffey, Matt; Bowen, David; Errington-Mais, Fiona

2012-01-01

Abstract Reovirus is a naturally occurring oncolytic virus that has shown preclinical efficacy in the treatment of a wide range of tumor types and has now reached phase III testing in clinical trials. The anti-cancer activity of reovirus has been attributed to both its direct oncolytic activity and the enhancement of anti-tumor immune responses. In this study, we have investigated the direct effect of reovirus on acute myeloid leukemia (AML) cells and its potential to enhance innate immune responses against AML, including the testing of primary samples from patients. Reovirus was found to replicate in and kill AML cell lines, and to reduce cell viability in primary AML samples. The pro-inflammatory cytokine interferon alpha (IFNα) and the chemokine (C-C motif) ligand 5 (known as RANTES [regulated upon activation, normal T-cell expressed, and secreted]) were also secreted from AML cells in response to virus treatment. In addition, reovirus-mediated activation of natural killer (NK) cells, within the context of peripheral blood mononuclear cells, stimulated their anti-leukemia response, with increased NK degranulation and IFNγ production and enhanced killing of AML targets. These data suggest that reovirus has the potential as both a direct cytotoxic and an immunotherapeutic agent for the treatment of AML. PMID:23515241

Comparative analysis of signature genes in PRRSV-infected porcine monocyte-derived cells at differential activation statuses

USDA-ARS?s Scientific Manuscript database

Activation statuses of monocytic cells are critically important for antiviral immunity. Devastating viruses like porcine reproductive and respiratory syndrome virus (PRRSV) are capable of directly infecting these cells, subverting host immunity. Monocyte-derived DCs (mDCs) are major target cells in ...

Direct contact with perivascular tumor cells enhances integrin αvβ3 signaling and migration of endothelial cells

PubMed Central

Burgett, Monica E.; Lathia, Justin D.; Roth, Patrick; Nowacki, Amy S.; Galileo, Deni S.; Pugacheva, Elena; Huang, Ping; Vasanji, Amit; Li, Meizhang; Byzova, Tatiana; Mikkelsen, Tom; Bao, Shideng; Rich, Jeremy N.; Weller, Michael; Gladson, Candece L.

2016-01-01

The secretion of soluble pro-angiogenic factors by tumor cells and stromal cells in the perivascular niche promotes the aggressive angiogenesis that is typical of glioblastoma (GBM). Here, we show that angiogenesis also can be promoted by a direct interaction between brain tumor cells, including tumor cells with cancer stem-like properties (CSCs), and endothelial cells (ECs). As shown in vitro, this direct interaction is mediated by binding of integrin αvβ3 expressed on ECs to the RGD-peptide in L1CAM expressed on CSCs. It promotes both EC network formation and enhances directed migration toward basic fibroblast growth factor. Activation of αvβ3 and bone marrow tyrosine kinase on chromosome X (BMX) is required for migration stimulated by direct binding but not for migration stimulated by soluble factors. RGD-peptide treatment of mice with established intracerebral GBM xenografts significantly reduced the percentage of Sox2-positive tumor cells and CSCs in close proximity to ECs, decreased integrin αvβ3 and BMX activation and p130CAS phosphorylation in the ECs, and reduced the vessel surface area. These results reveal a previously unrecognized aspect of the regulation of angiogenesis in GBM that can impact therapeutic anti-angiogenic targeting. PMID:27270311

Identification of in vivo phosphorylation sites on human deoxycytidine kinase. Role of Ser-74 in the control of enzyme activity.

PubMed

Smal, Caroline; Vertommen, Didier; Bertrand, Luc; Ntamashimikiro, Sandrine; Rider, Mark H; Van Den Neste, Eric; Bontemps, Françoise

2006-02-24

Deoxycytidine kinase (dCK) catalyzes the rate-limiting step of the deoxyribonucleoside salvage pathway in mammalian cells and plays a key role in the activation of numerous nucleoside analogues used in anti-cancer and antiviral chemotherapy. Although compelling evidence indicated that dCK activity might be regulated by phosphorylation/dephosphorylation, direct demonstration was lacking. Here we showed that dCK overexpressed in HEK 293T cells was labeled after incubating the cells with [32P]orthophosphate. Sorbitol, which was reported to decrease dCK activity, also decreased the labeling of dCK. These results indicated that dCK may exist as a phosphoprotein in vivo and that its activity can be correlated with its phosphorylation level. After purification of 32P-labeled dCK, digestion by trypsin, and analysis of the radioactive peptides by tandem mass spectrometry, the following four in vivo phosphorylation sites were identified: Thr-3, Ser-11, Ser-15, and Ser-74, the latter being the major phosphorylation site. Site-directed mutagenesis and use of an anti-phospho-Ser-74 antibody demonstrated that Ser-74 phosphorylation was crucial for dCK activity in HEK 293T cells, whereas phosphorylation of other identified sites did not seem essential. Phosphorylation of Ser-74 was also detected on endogenous dCK in leukemic cells, in which the Ser-74 phosphorylation state was increased by agents that enhanced dCK activity. Our study provided direct evidence that dCK activity can be controlled by phosphorylation in intact cells and highlights the importance of Ser-74 for dCK activity.

Functional Coordination of WAVE and WASP in C. elegans Neuroblast Migration.

PubMed

Zhu, Zhiwen; Chai, Yongping; Jiang, Yuxiang; Li, Wenjing; Hu, Huifang; Li, Wei; Wu, Jia-Wei; Wang, Zhi-Xin; Huang, Shanjin; Ou, Guangshuo

2016-10-24

Directional cell migration is critical for metazoan development. We define two molecular pathways that activate the Arp2/3 complex during neuroblast migration in Caenorhabditis elegans. The transmembrane protein MIG-13/Lrp12 is linked to the Arp2/3 nucleation-promoting factors WAVE or WASP through direct interactions with ABL-1 or SEM-5/Grb2, respectively. WAVE mutations partially impaired F-actin organization and decelerated cell migration, and WASP mutations did not inhibit cell migration but enhanced migration defects in WAVE-deficient cells. Purified SEM-5 and MIG-2 synergistically stimulated the F-actin branching activity of WASP-Arp2/3 in vitro. In GFP knockin animals, WAVE and WASP were largely organized into separate clusters at the leading edge, and the amount of WASP was less than WAVE but could be elevated by WAVE mutations. Our results indicate that the MIG-13-WAVE pathway provides the major force for directional cell motility, whereas MIG-13-WASP partially compensates for its loss, underscoring their coordinated activities in facilitating robust cell migration. Copyright © 2016 Elsevier Inc. All rights reserved.

SOXF factors regulate murine satellite cell self-renewal and function through inhibition of β-catenin activity.

PubMed

Alonso-Martin, Sonia; Auradé, Frédéric; Mademtzoglou, Despoina; Rochat, Anne; Zammit, Peter S; Relaix, Frédéric

2018-06-08

Muscle satellite cells are the primary source of stem cells for postnatal skeletal muscle growth and regeneration. Understanding genetic control of satellite cell formation, maintenance, and acquisition of their stem cell properties is on-going, and we have identified SOXF (SOX7, SOX17, SOX18) transcriptional factors as being induced during satellite cell specification. We demonstrate that SOXF factors regulate satellite cell quiescence, self-renewal and differentiation. Moreover, ablation of Sox17 in the muscle lineage impairs postnatal muscle growth and regeneration. We further determine that activities of SOX7, SOX17 and SOX18 overlap during muscle regeneration, with SOXF transcriptional activity requisite. Finally, we show that SOXF factors also control satellite cell expansion and renewal by directly inhibiting the output of β-catenin activity, including inhibition of Ccnd1 and Axin2 . Together, our findings identify a key regulatory function of SoxF genes in muscle stem cells via direct transcriptional control and interaction with canonical Wnt/β-catenin signaling. © 2018, Alonso-Martin et al.

Tumour necrosis factor α secretion induces protease activation and acinar cell necrosis in acute experimental pancreatitis in mice.

PubMed

Sendler, Matthias; Dummer, Annegret; Weiss, Frank U; Krüger, Burkhard; Wartmann, Thomas; Scharffetter-Kochanek, Karin; van Rooijen, Nico; Malla, Sudarshan Ravi; Aghdassi, Ali; Halangk, Walter; Lerch, Markus M; Mayerle, Julia

2013-03-01

Acute pancreatitis has long been considered a disorder of pancreatic self-digestion, in which intracellular activation of digestive proteases induces tissue injury. Chemokines, released from damaged pancreatic cells then attract inflammatory cells, whose systemic action ultimately determines the disease severity. In the present work the opposite mechanism is investigated; that is, whether and how inflammatory cells can activate intracellular proteases. Using mice either deficient for the CD18-α subunit of the membrane attack complex-1 (MAC-1) complex or tumour necrosis factor (TNF)α, as well as after depletion of leucocyte subpopulations, pancreatitis was induced by 7-hourly caerulein injections (50 μg/kg, intraperitoneally). Pancreatic acini were coincubated in vitro from wild-type and cathepsin-B-deficient animals with phorbol-12-myristate-13-acetate (PMA)-activated neutrophils and macrophages, caerulein or TNFα, and activities of trypsin, cathepsin-B and caspase-3 were measured, as well as necrosis using fluorogenic substrates. TNFα was inhibited with monospecific antibodies. Deletion of CD18 prevented transmigration of leucocytes into the pancreas during pancreatitis, greatly reduced disease severity and abolished digestive protease activation. Depletion of neutrophils and macrophages equally reduced premature trypsinogen activation and disease severity. In vitro activated neutrophils and macrophages directly induced premature protease activation and cell death in pancreatic acini and stimulation of acini with TNFα induced caspase-3 activation and necrosis via a cathepsin-B and calcium-dependent mechanism. Neutralising antibodies against TNFα and genetic deletion of TNFα prevented leucocyte-induced trypsin activity and necrosis in isolated acini. The soluble inflammatory cell mediator TNFα directly induces premature protease activation and necrosis in pancreatic acinar cells. This activation depends on calcium and cathepsin-B activity. The findings from the present work further suggest that targeting TNFα, for which pharmaceutical agents are readily available, could be an effective treatment strategy that directly addresses the cellular causes of pancreatitis.

Plasmacytoid dendritic cells induce NK cell-dependent, tumor antigen-specific T cell cross-priming and tumor regression in mice.

PubMed

Liu, Chengwen; Lou, Yanyan; Lizée, Gregory; Qin, Hong; Liu, Shujuan; Rabinovich, Brian; Kim, Grace J; Wang, Yi-Hong; Ye, Yang; Sikora, Andrew G; Overwijk, Willem W; Liu, Yong-Jun; Wang, Gang; Hwu, Patrick

2008-03-01

A prerequisite for strong adaptive antiviral immunity is the robust initial activation of the innate immune system, which is frequently mediated by TLR-activated plasmacytoid DCs (pDCs). Natural antitumor immunity is often comparatively weak, potentially due to the lack of TLR-mediated activation signals within the tumor microenvironment. To assess whether pDCs are capable of directly facilitating effective antitumor immune responses, mice bearing established subcutaneous B16 melanoma tumors were administered TLR9-activated pDCs directly into the tumor. We found that TLR9-activated pDCs induced robust, spontaneous CTL cross-priming against multiple B16 tumor antigens, leading to the regression of both treated tumors and untreated tumors at distant contralateral sites. This T cell cross-priming was mediated by conventional DCs (cDCs) and was completely dependent upon the early recruitment and activation of NK cells at the tumor site. NK cell recruitment was mediated by CCR5 via chemokines secreted by pDCs, and optimal IFN-gamma production by NK cells was mediated by OX40L expressed by pDCs. Our data thus demonstrated that activated pDCs are capable of initiating effective and systemic antitumor immunity through the orchestration of an immune cascade involving the sequential activation of NK cells, cDCs, and CD8(+) T cells.

E-selectin: sialyl Lewis, a dependent adhesion of colon cancer cells, is inhibited differently by antibodies against E-selectin ligands.

PubMed

Srinivas, U; Påhlsson, P; Lundblad, A

1996-09-01

Recent studies have demonstrated that selectins, a new family of cell-adhesion molecules with similar domain structures, mediate the adhesion of peripheral blood cells to interleukin-1 (IL-1)-activated endothelium. In the present study the authors evaluated the role of E-selectin-Sialyl Lewis x (SLe(x))/ Sialyl Lewis a (SLe(a)) interaction in mediating in vitro adhesion of two colon cancer cell lines, HT-29 and COLO 201, to human umbilical cord endothelial cells (HUVEC). Colon cancer cell lines had a strong expression of blood group-related carbohydrate epitopes as evaluated by fluorescence-activated cell sorter (FACS) analysis. It was established that adhesion of HT-29 and COLO 201 cells to IL-1 stimulated HUVEC was calcium dependent and could be inhibited by a monoclonal antibody directed against E-selectin. Prior incubation of cells with two different antibodies directed against SLe(x) and antibodies directed against related Lewis epitopes, Le(x) and Le(a), had no significant effect on adhesion. Three antibodies directed against SLe(a) differed in their capacity to inhibit the adhesion of HT-29 and COLO 201 cells to HUVEC. Only one antibody directed against the SLe(a) structure was effective in inhibiting adhesion of both COLO 201 and HT-29 cells. The difference could not be attributed to titre, the type or number of glycoproteins, or to a difference in the amount of SLe(a) present on individual proteins, suggesting that presence and right presentation of SLe(a) epitope might be important for adhesion of colon cancer cells. Finally, in the in vitro system used, adhesion of HT-29 and COLO 201 cells to activated HUVEC is mediated predominantly by E-selectin/SLe(a) interaction. SLe(x) and related epitopes, Le(x) and Le(a), seem to have limited relevance for colon cancer cell recognition of E-selectin.

Direct measurement of catalase activity in living cells and tissue biopsies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scaglione, Christine N.; Xu, Qijin; Ramanujan, V. Krishnan, E-mail: Ramanujanv@csmc.edu

Spatiotemporal regulation of enzyme-substrate interactions governs the decision-making steps in biological systems. Enzymes, being functional units of every living cell, contribute to the macromolecular stability of cell survival, proliferation and hence are vital windows to unraveling the biological complexity. Experimental measurements capturing this dynamics of enzyme-substrate interactions in real time add value to this understanding. Furthermore these measurements, upon validation in realistic biological specimens such as clinical biopsies – can further improve our capability in disease diagnostics and treatment monitoring. Towards this direction, we describe here a novel, high-sensitive measurement system for measuring diffusion-limited enzyme-substrate kinetics in real time. Usingmore » catalase (enzyme) and hydrogen peroxide (substrate) as the example pair, we demonstrate that this system is capable of direct measurement of catalase activity in vitro and the measured kinetics follows the classical Michaelis-Menten reaction kinetics. We further demonstrate the system performance by measuring catalase activity in living cells and in very small amounts of liver biopsies (down to 1 μg total protein). Catalase-specific enzyme activity is demonstrated by genetic and pharmacological tools. Finally we show the clinically-relevant diagnostic capability of our system by comparing the catalase activities in liver biopsies from young and old mouse (liver and serum) samples. We discuss the potential applicability of this system in clinical diagnostics as well as in intraoperative surgical settings. - Highlights: • A novel, direct measurement of Catalase enzyme activity via, oxygen sensing method. • Steady-stateprofiles of Catalase activity follow the Michaelis-Menten Kinetics. • Catalase-specific activity demonstrated using genetic and pharmacological tools. • Overcomes limitations of spectroscopic methods and indirect calorimetric approaches. • Clear demonstration of the applicability in cancer cells and aging animal tissues.« less

Surface acoustic wave actuated cell sorting (SAWACS).

PubMed

Franke, T; Braunmüller, S; Schmid, L; Wixforth, A; Weitz, D A

2010-03-21

We describe a novel microfluidic cell sorter which operates in continuous flow at high sorting rates. The device is based on a surface acoustic wave cell-sorting scheme and combines many advantages of fluorescence activated cell sorting (FACS) and fluorescence activated droplet sorting (FADS) in microfluidic channels. It is fully integrated on a PDMS device, and allows fast electronic control of cell diversion. We direct cells by acoustic streaming excited by a surface acoustic wave which deflects the fluid independently of the contrast in material properties of deflected objects and the continuous phase; thus the device underlying principle works without additional enhancement of the sorting by prior labelling of the cells with responsive markers such as magnetic or polarizable beads. Single cells are sorted directly from bulk media at rates as fast as several kHz without prior encapsulation into liquid droplet compartments as in traditional FACS. We have successfully directed HaCaT cells (human keratinocytes), fibroblasts from mice and MV3 melanoma cells. The low shear forces of this sorting method ensure that cells survive after sorting.

The Adaptor Protein SAP Directly Associates with CD3ζ Chain and Regulates T Cell Receptor Signaling

PubMed Central

Proust, Richard; Bertoglio, Jacques; Gesbert, Franck

2012-01-01

Mutations altering the gene encoding the SLAM associated protein (SAP) are responsible for the X-linked lymphoproliferative disease or XLP1. Its absence is correlated with a defective NKT cells development, a decrease in B cell functions and a reduced T cells and NK cells cytotoxic activities, thus leading to an immunodeficiency syndrome. SAP is a small 128 amino-acid long protein that is almost exclusively composed of an SH2 domain. It has been shown to interact with the CD150/SLAM family of receptors, and in a non-canonical manner with SH3 containing proteins such as Fyn, βPIX, PKCθ and Nck1. It would thus play the role of a minimal adaptor protein. It has been shown that SAP plays an important function in the activation of T cells through its interaction with the SLAM family of receptors. Therefore SAP defective T cells display a reduced activation of signaling events downstream of the TCR-CD3 complex triggering. In the present work, we evidence that SAP is a direct interactor of the CD3ζ chain. This direct interaction occurs through the first ITAM of CD3ζ, proximal to the membrane. Additionally, we show that, in the context of the TCR-CD3 signaling, an Sh-RNA mediated silencing of SAP is responsible for a decrease of several canonical T cell signaling pathways including Erk, Akt and PLCγ1 and to a reduced induction of IL-2 and IL-4 mRNA. Altogether, we show that SAP plays a central function in the T cell activation processes through a direct association with the CD3 complex. PMID:22912825

Changes in Simple Spike Activity of some Purkinje cells in the Oculomotor Vermis during Saccade Adaptation are Appropriate to Participate in Motor Learning

PubMed Central

Kojima, Yoshiko; Soetedjo, Robijanto; Fuchs, Albert F.

2010-01-01

Adaptation of saccadic eye movements provides an excellent motor learning model to study theories of neuronal plasticity. When primates make saccades to a jumping target, a backward step of the target during the saccade can make it appear to overshoot. If this deception continues for many trials, saccades gradually decrease in amplitude to go directly to the back-stepped target location. We used this adaptation paradigm to evaluate the Marr-Albus hypothesis that such motor learning occurs at the Purkinje (P-) cell of the cerebellum. We recorded the activity of identified P-cells in the oculomotor vermis, lobules VIc and VII. After determining the on and off error directions of a P-cell’s complex spike activity, we determined whether its saccade-related simple spike (SS) activity changed during saccade adaptation in those two directions. Before adaptation, 57 of 61 P-cells exhibited a clear burst, pause or a combination of both for saccades in one or both directions. Sixty-two percent of all cells, including 2 of the 4 initially unresponsive ones, behaved differently for saccades whose size changed because of adaptation than for saccades of similar sizes gathered before adaptation. In at least 42% of these, the changes were appropriate to decrease saccade amplitude based on our current knowledge of cerebellum and brain stem saccade circuitry. Changes in activity during adaptation were not compensating for the potential fatigue associated with performing many saccades. Therefore, many P-cells in the oculomotor vermis exhibit changes in SS activity specific to adapted saccades and therefore appropriate to induce adaptation. PMID:20220005

Tests of the relative roles of calcium channels and calcium pumps in controlling gravity-directed development in single spore cells of the fern Ceratopteris richardii

NASA Astrophysics Data System (ADS)

Roux, Stanley; Porterfield, D. Marshall; Haque, Aeraj Ul; Bushart, Thomas

The vector of gravity sets the direction of polarized development of single spore cells of the fern Ceratopteris richardii after light initiates their germination. Gravity also sets the direction of a trans-cell calcium current, which enters the cell along its bottom and exits it from its top. The direction of this current predicts the subsequent direction of spore development, and blocking this current with calcium channel blockers randomizes the direction of subsequent development. Recently the laboratory of D. Marshall Porterfield (Purdue University) developed a microchip device that can measure the direction and magnitude of the trans-spore calcium current in real time. Our laboratory in collaboration with Porterfield's recently found that this current inverts rapidly when the cells are turned upside down and that the magnitude of the current rises and falls with the magnitude of the g-force when these cells are tested in parabolic flight on the DC-9 aircraft. We assume that the gravity-directed entry of calcium into these cells is through calcium channels and its exit is through calcium pumps. Here we report our studies of a calcium pump that is highly expressed in the spores during the period when gravity is setting the direction of the calcium current, and we describe pharmacological tests of the relative importance of calcium pumps in maintaining the calcium current and in controlling the direction of subsequent spore development. We found that inhibitors that block the activity of calcium pumps also greatly depress the trans-cell current, but, surprisingly, have little effect on the ability of gravity to set the direction of spore development. These results, in combination with earlier findings, indicate that the gravity-directed opening of calcium channels along the bottom of spore cells plays a more important role in directing subsequent spore development than the activity of calcium pumps, despite the importance of these pumps in maintaining the trans-cell calcium current. Supported by NASA grants NAG2-1586 and NAG10-295 to S. J. R.

Differences In Early T-Cell Signaling In Cultures Grown In a Rotating Clinostat vs. Static Controls

NASA Technical Reports Server (NTRS)

Alexamder. M.; Nelman-Gonzales, M.; Penkala, J.; Sams, C.

1999-01-01

Altered gravity has previously been demonstrated to be a stress that can influence components of the immune system. Specifically, T-cell activation has been shown to be affected by changes in gravity, exhibiting a decrease in proliferative response to in vitro stimulation in microgravity. Subsequent ground based studies utilizing a rotating clinostat to model some of the effects of microgravity have been consistent with earlier flight based experiments. These ground and flight experiments have examined T-cell activation by measuring various responses including production of cytokines, DNA synthesis and the production of various cell surface activation markers. These indicators of T-cell activation were measured anywhere from 4 to 72 hours after stimulation. Prior to the work described here, the initial signaling events in T-cell activation had not been directly examined. The goal of this project was to determine how the process of early signal transduction was affected by growth in a rotating clinostat. Here we directly show a defect in signaling from TCR to MAPK in purified peripheral T-cells activated in the clinostat by OKT3/antiCD28 coated microbeads as compared to static controls.

Multi-cellular 3D human primary liver cell culture elevates metabolic activity under fluidic flow.

PubMed

Esch, Mandy B; Prot, Jean-Matthieu; Wang, Ying I; Miller, Paula; Llamas-Vidales, Jose Ricardo; Naughton, Brian A; Applegate, Dawn R; Shuler, Michael L

2015-05-21

We have developed a low-cost liver cell culture device that creates fluidic flow over a 3D primary liver cell culture that consists of multiple liver cell types, including hepatocytes and non-parenchymal cells (fibroblasts, stellate cells, and Kupffer cells). We tested the performance of the cell culture under fluidic flow for 14 days, finding that hepatocytes produced albumin and urea at elevated levels compared to static cultures. Hepatocytes also responded with induction of P450 (CYP1A1 and CYP3A4) enzyme activity when challenged with P450 inducers, although we did not find significant differences between static and fluidic cultures. Non-parenchymal cells were similarly responsive, producing interleukin 8 (IL-8) when challenged with 10 μM bacterial lipoprotein (LPS). To create the fluidic flow in an inexpensive manner, we used a rocking platform that tilts the cell culture devices at angles between ±12°, resulting in a periodically changing hydrostatic pressure drop between reservoirs and the accompanying periodically changing fluidic flow (average flow rate of 650 μL min(-1), and a maximum shear stress of 0.64 dyne cm(-2)). The increase in metabolic activity is consistent with the hypothesis that, similar to unidirectional fluidic flow, primary liver cell cultures increase their metabolic activity in response to fluidic flow periodically changes direction. Since fluidic flow that changes direction periodically drastically changes the behavior of other cells types that are shear sensitive, our findings support the theory that the increase in hepatic metabolic activity associated with fluidic flow is either activated by mechanisms other than shear sensing (for example increased opportunities for gas and metabolite exchange), or that it follows a shear sensing mechanism that does not depend on the direction of shear. Our mode of device operation allows us to evaluate drugs under fluidic cell culture conditions and at low device manufacturing and operation costs.

EGCG reverses human neutrophil elastase-induced migration in A549 cells by directly binding to HNE and by regulating α1-AT

NASA Astrophysics Data System (ADS)

Xiaokaiti, Yilixiati; Wu, Haoming; Chen, Ya; Yang, Haopeng; Duan, Jianhui; Li, Xin; Pan, Yan; Tie, Lu; Zhang, Liangren; Li, Xuejun

2015-07-01

Lung carcinogenesis is a complex process that occurs in unregulated inflammatory environment. EGCG has been extensively investigated as a multi-targeting anti-tumor and anti-inflammatory compound. In this study, we demonstrated a novel mechanism by which EGCG reverses the neutrophil elastase-induced migration of A549 cells. We found that neutrophil elastase directly triggered human adenocarcinoma A549 cell migration and that EGCG suppressed the elevation of tumor cell migration induced by neutrophil elastase. We observed that EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity based on the CDOCKER algorithm, MD stimulation by GROMACS, SPR assay and elastase enzymatic activity assay. As the natural inhibitor of neutrophil elastase, α1-antitrypsin is synthesized in tumor cells. We further demonstrated that the expression of α1-antitrypsin was up-regulated after EGCG treatment in neutrophil elastase-treated A549 cells. We preliminarily discovered that the EGCG-mediated induction of α1-antitrypsin expression might be correlated with the regulatory effect of EGCG on the PI3K/Akt pathway. Overall, our results suggest that EGCG ameliorates the neutrophil elastase-induced migration of A549 cells. The mechanism underlying this effect may include two processes: EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity; EGCG enhances the expression of α1-antitrypsin by regulating the PI3K/AKT pathway.

EGCG reverses human neutrophil elastase-induced migration in A549 cells by directly binding to HNE and by regulating α1-AT.

PubMed

Xiaokaiti, Yilixiati; Wu, Haoming; Chen, Ya; Yang, Haopeng; Duan, Jianhui; Li, Xin; Pan, Yan; Tie, Lu; Zhang, Liangren; Li, Xuejun

2015-07-16

Lung carcinogenesis is a complex process that occurs in unregulated inflammatory environment. EGCG has been extensively investigated as a multi-targeting anti-tumor and anti-inflammatory compound. In this study, we demonstrated a novel mechanism by which EGCG reverses the neutrophil elastase-induced migration of A549 cells. We found that neutrophil elastase directly triggered human adenocarcinoma A549 cell migration and that EGCG suppressed the elevation of tumor cell migration induced by neutrophil elastase. We observed that EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity based on the CDOCKER algorithm, MD stimulation by GROMACS, SPR assay and elastase enzymatic activity assay. As the natural inhibitor of neutrophil elastase, α1-antitrypsin is synthesized in tumor cells. We further demonstrated that the expression of α1-antitrypsin was up-regulated after EGCG treatment in neutrophil elastase-treated A549 cells. We preliminarily discovered that the EGCG-mediated induction of α1-antitrypsin expression might be correlated with the regulatory effect of EGCG on the PI3K/Akt pathway. Overall, our results suggest that EGCG ameliorates the neutrophil elastase-induced migration of A549 cells. The mechanism underlying this effect may include two processes: EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity; EGCG enhances the expression of α1-antitrypsin by regulating the PI3K/AKT pathway.

Antibody Therapeutics in Oncology.

PubMed

Wold, Erik D; Smider, Vaughn V; Felding, Brunhilde H

2016-03-01

One of the newer classes of targeted cancer therapeutics is monoclonal antibodies. Monoclonal antibody therapeutics are a successful and rapidly expanding drug class due to their high specificity, activity, favourable pharmacokinetics, and standardized manufacturing processes. Antibodies are capable of recruiting the immune system to attack cancer cells through complement-dependent cytotoxicity or antibody dependent cellular cytotoxicity. In an ideal scenario the initial tumor cell destruction induced by administration of a therapeutic antibody can result in uptake of tumor associated antigens by antigen-presenting cells, establishing a prolonged memory effect. Mechanisms of direct tumor cell killing by antibodies include antibody recognition of cell surface bound enzymes to neutralize enzyme activity and signaling, or induction of receptor agonist or antagonist activity. Both approaches result in cellular apoptosis. In another and very direct approach, antibodies are used to deliver drugs to target cells and cause cell death. Such antibody drug conjugates (ADCs) direct cytotoxic compounds to tumor cells, after selective binding to cell surface antigens, internalization, and intracellular drug release. Efficacy and safety of ADCs for cancer therapy has recently been greatly advanced based on innovative approaches for site-specific drug conjugation to the antibody structure. This technology enabled rational optimization of function and pharmacokinetics of the resulting conjugates, and is now beginning to yield therapeutics with defined, uniform molecular characteristics, and unprecedented promise to advance cancer treatment.

Bax/Bak activation in the absence of Bid, Bim, Puma, and p53

PubMed Central

Zhang, J; Huang, K; O'Neill, K L; Pang, X; Luo, X

2016-01-01

How BH3-only proteins activate Bax/Bak, the two gateway proteins of the mitochondria-dependent apoptotic pathway, remains incompletely understood. Although all pro-apoptotic BH3-only proteins are known to bind/neutralize the anti-apoptotic Bcl-2 proteins, the three most potent ones, Bid (tBid), Bim, and Puma, possess an additional activity of directly activating Bax/Bak in vitro. This latter activity has been proposed to be responsible for triggering Bax/Bak activation following apoptotic stimulation. To test this hypothesis, we generated Bid−/−Bim−/−Puma−/− (TKO), TKO/Bax−/−/Bak−/− (PentaKO), and PentaKO/Mcl-1−/− (HexaKO) HCT116 cells through gene editing. Surprisingly, although the TKO cells were resistant to several apoptotic stimuli, robust apoptosis was induced upon the simultaneous inactivation of Bcl-xL and Mcl-1, two anti-apoptotic Bcl-2 proteins known to suppress Bax/Bak activation and activity. Importantly, such apoptotic activity was completely abolished in the PentaKO cells. In addition, ABT-737, a BH3 mimetic that inhibits Bcl-xL/Bcl-w/Bcl-2, induced Bax activation in HexaKO cells reconstituted with endogenous level of GFP-Bax. Further, by generating TKO/p53−/− (QKO) cells, we demonstrated that p53, a tumor suppressor postulated to directly activate Bax, is not required for Bid/Bim/Puma-independent Bax/Bak activation. Together, these results strongly suggest that the direct activation activities of Bid (tBid), Bim, Puma, and p53 are not essential for activating Bax/Bak once the anti-apoptotic Bcl-2 proteins are neutralized. PMID:27310874

Comparative analysis of signature genes in porcine reproductive and respiratory syndrome virus (PRRSV)-infected porcine monocyte-derived dendritic cells at differential activation statuses

USDA-ARS?s Scientific Manuscript database

Activation statuses of monocytic cells, e.g. monocytes, macrophages and dendritic cells (DCs), are critically important for antiviral immunity. In particular, some devastating viruses, including porcine reproductive and respiratory syndrome virus (PRRSV), are capable of directly infecting these cell...

Direct liquid-feed fuel cell with membrane electrolyte and manufacturing thereof

NASA Technical Reports Server (NTRS)

Narayanan, Sekharipuram (Inventor); Surampudi, Subbarao (Inventor); Halpert, Gerald (Inventor)

1999-01-01

An improved direct liquid-feed fuel cell having a solid membrane electrolyte for electrochemical reactions of an organic fuel. Improvements in interfacing of the catalyst layer and the membrane and activating catalyst materials are disclosed.

Unique ζ-chain motifs mediate a direct TCR-actin linkage critical for immunological synapse formation and T-cell activation.

PubMed

Klieger, Yair; Almogi-Hazan, Osnat; Ish-Shalom, Eliran; Pato, Aviad; Pauker, Maor H; Barda-Saad, Mira; Wang, Lynn; Baniyash, Michal

2014-01-01

TCR-mediated activation induces receptor microclusters that evolve to a defined immune synapse (IS). Many studies showed that actin polymerization and remodeling, which create a scaffold critical to IS formation and stabilization, are TCR mediated. However, the mechanisms controlling simultaneous TCR and actin dynamic rearrangement in the IS are yet not fully understood. Herein, we identify two novel TCR ζ-chain motifs, mediating the TCR's direct interaction with actin and inducing actin bundling. While T cells expressing the ζ-chain mutated in these motifs lack cytoskeleton (actin) associated (cska)-TCRs, they express normal levels of non-cska and surface TCRs as cells expressing wild-type ζ-chain. However, such mutant cells are unable to display activation-dependent TCR clustering, IS formation, expression of CD25/CD69 activation markers, or produce/secrete cytokine, effects also seen in the corresponding APCs. We are the first to show a direct TCR-actin linkage, providing the missing gap linking between TCR-mediated Ag recognition, specific cytoskeleton orientation toward the T-cell-APC interacting pole and long-lived IS maintenance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A polysaccharide from Lentinus edodes inhibits human colon cancer cell proliferation and suppresses tumor growth in athymic nude mice

PubMed Central

Wang, Jinglin; Li, Weiyong; Huang, Xiao; Liu, Ying; Li, Qiang; Zheng, Ziming; Wang, Kaiping

2017-01-01

The antitumor effect of Lentinan is thought rely on the activation of immune responses; however, little is known about whether Lentinan also directly attacks cancer cells. We therefore investigated the direct antitumor activity of SLNT (a water-extracted polysaccharide from Lentinus edodes) and its probable mechanism. We showed that SLNT significantly inhibited proliferation of HT-29 colon cancer cells and suppressed tumor growth in nude mice. Annxein V-FITC/PI, DAPI, AO/EB and H&E staining assays all showed that SLNT induced cell apoptosis both in vitro and in vivo. SLNT induced apoptosis by activating Caspase-3 via both intrinsic and extrinsic pathways, which presented as the activation of Caspases-9 and -8, upregulation of cytochrome c and the Bax/Bcl-2 ratio, downregulation of NF-κB, and overproduction of ROS and TNF-α in vitro and in vivo. Pretreatment with the caspase-3 inhibitor Ac-DEVD-CHO or antioxidant NAC blocked SLNT-induced apoptosis. These findings suggest that SLNT exerts direct antitumor effects by inducing cell apoptosis via ROS-mediated intrinsic and TNF-α-mediated extrinsic pathways. SLNT may thus represent a useful candidate for colon cancer prevention and treatment. PMID:27888812

Comparison of the effects of gemfibrozil and clofibric acid on peroxisomal enzymes and cholesterol synthesis of rat hepatocytes.

PubMed

Hashimoto, F; Taira, S; Hayashi, H

1998-11-01

We studied whether the peroxisomal proliferation, induction of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) and activation of cholesterol synthesis by gemfibrozil shown in whole body (Hashimoto F., Ishikawa T., Hamada S. and Hayashi H., Biochemical. Pharm., 49, 1213-1221 (1995)) is also detected at a culture cell level, and we made a comparative analysis of the effects of clofibric acid. Gemfibrozil at 0.25 mM increased the activity of some peroxisomal enzymes (catalase and the cyanide-insensitive fatty acyl-CoA oxidizing system) after incubation for 72 h. However, contrary to whole body experiments, gemfibrozil decreased the activity of HMG-CoA reductase and cholesterol synthesis from [14C]acetate. At 1 mM, gemfibrozil decreased not only the activity of HMG-CoA reductase and cholesterol synthesis, but also the protein content of the cells and peroxisomal enzyme activity, indicating nonspecific inhibition at this concentration. Clofibric acid (0.25 and 1 mM) increased the activity of peroxisomal enzymes, but decreased the activity of HMG-CoA reductase and cholesterol synthesis. With respect to the direct effect on HMG-CoA reductase in the cell homogenate, gemfibrozil at 0.25 mm did not affect the activity, but it clearly inhibited the activity at 2 mM and above. Clofibric acid at 2 mM hardly affected the activity, but it clearly decreased the activity at 5 mM and over. That is, gemfibrozil directly inhibited the activity more strongly than clofibric acid. The direct inhibition of the enzyme itself required higher concentrations of both agents than did inhibition at the culture cell level. These results suggest that the cytotoxicity of gemfibrozil is greater than that of clofibric acid, and that gemfibrozil, as well as clofibric acid, can induce peroxisomal enzymes in the culture cell level. In contrast to whole body results, gemfibrozil may suppress cholesterol synthesis from [14C]acetate through the inhibition of HMG-CoA reductase at the culture cell level. The decreases in the reductase activity caused by gemfibrozil and clofibric acid at the culture cell level may not be caused by the direct inhibition of the enzyme.

Bi-directional activation between mesenchymal stem cells and CLL B-cells: implication for CLL disease progression.

PubMed

Ding, Wei; Nowakowski, Grzegorz S; Knox, Traci R; Boysen, Justin C; Maas, Mary L; Schwager, Susan M; Wu, Wenting; Wellik, Linda E; Dietz, Allan B; Ghosh, Asish K; Secreto, Charla R; Medina, Kay L; Shanafelt, Tait D; Zent, Clive S; Call, Timothy G; Kay, Neil E

2009-11-01

It was hypothesized that contact between chronic lymphocytic leukaemia (CLL) B-cells and marrow stromal cells impact both cell types. To test this hypothesis, we utilized a long-term primary culture system from bone biopsies that reliably generates a mesenchymal stem cell (MSC). Co-culture of MSC with CLL B-cells protected the latter from both spontaneous apoptosis and drug-induced apoptosis. The CD38 expression in previously CD38 positive CLL B-cells was up-regulated with MSC co-culture. Upregulation of CD71, CD25, CD69 and CD70 in CLL B-cells was found in the co-culture. CD71 upregulation was more significantly associated with high-risk CLL, implicating CD71 regulation in the microenvironment predicting disease progression. In MSC, rapid ERK and AKT phosphorylation (within 30 min) were detected when CLL B-cells and MSC were separated by transwell; indicating that activation of MSC was mediated by soluble factors. These findings support a bi-directional activation between bone marrow stromal cells and CLL B-cells.

Evidence for Osteocalcin Binding and Activation of GPRC6A in β-Cells

DOE PAGES

Pi, Min; Kapoor, Karan; Ye, Ruisong; ...

2016-05-01

The possibility that G protein-coupled receptor family C member A (GPRC6A) is the osteocalcin (Ocn)-sensing G protein-coupled receptor that directly regulates pancreatic β-cell functions is controversial. In the current study, we found that Ocn and an Ocn-derived C-terminal hexapeptide directly activate GPRC6A-dependent ERK signaling in vitro. Computational models probe the structural basis of Ocn binding to GPRC6A and predict that the C-terminal hexapeptide docks to the extracellular side of the transmembrane domain of GPRC6A. Consistent with the modeling, mutations in the computationally identified binding pocket of GPRC6A reduced Ocn and C-terminal hexapeptide activation of this receptor. In addition, selective deletionmore » of Gprc6a in β-cells (Gprc6a β-cell-cko) by crossing Gprc6a flox/flox mice with Ins2-Cre mice resulted in reduced pancreatic weight, islet number, insulin protein content, and insulin message expression. Both islet size and β-cell proliferation were reduced in Gprc6a β-cell-cko compared with control mice. Gprc6a β-cell-cko exhibited abnormal glucose tolerance, but normal insulin sensitivity. Islets isolated from Gprc6a β-cell-cko mice showed reduced insulin simulation index in response to Ocn. Here, these data establish the structural basis for Ocn direct activation of GPRC6A and confirm a role for GPRC6A in regulating β-cell proliferation and insulin secretion.« less

The WEREWOLF MYB protein directly regulates CAPRICE transcription during cell fate specification in the Arabidopsis root epidermis.

PubMed

Ryu, Kook Hui; Kang, Yeon Hee; Park, Young-hwan; Hwang, Ildoo; Schiefelbein, John; Lee, Myeong Min

2005-11-01

The Arabidopsis root epidermis is composed of two types of cells, hair cells and non-hair cells, and their fate is determined in a position-dependent manner. WEREWOLF (WER), a R2R3 MYB protein, has been shown genetically to function as a master regulator to control both of the epidermal cell fates. To directly test the proposed role of WER in this system, we examined its subcellular localization and defined its transcriptional activation properties. We show that a WER-GFP fusion protein is functional and accumulates in the nucleus of the N-position cells in the Arabidopsis root epidermis, as expected for a transcriptional regulator. We also find that a modified WER protein with a strong activation domain (WER-VP16) promotes the formation of both epidermal cell types, supporting the view that WER specifies both cell fates. In addition, we used the glucocorticoid receptor (GR) inducible system to show that CPC transcription is regulated directly by WER. Using EMSA, we found two WER-binding sites (WBSs; WBSI and WBSII) in the CPC promoter. WER-WBSI binding was confirmed in vivo using the yeast one-hybrid assay. Binding between the WER protein and both WBSs (WBSI and WBSII), and the importance of the two WBSs in CPC promoter activity were confirmed in Arabidopsis. These results provide experimental support for the proposed role of WER as an activator of gene transcription during the specification of both epidermal cell fates.

Evidence for Osteocalcin Binding and Activation of GPRC6A in β-Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pi, Min; Kapoor, Karan; Ye, Ruisong

The possibility that G protein-coupled receptor family C member A (GPRC6A) is the osteocalcin (Ocn)-sensing G protein-coupled receptor that directly regulates pancreatic β-cell functions is controversial. In the current study, we found that Ocn and an Ocn-derived C-terminal hexapeptide directly activate GPRC6A-dependent ERK signaling in vitro. Computational models probe the structural basis of Ocn binding to GPRC6A and predict that the C-terminal hexapeptide docks to the extracellular side of the transmembrane domain of GPRC6A. Consistent with the modeling, mutations in the computationally identified binding pocket of GPRC6A reduced Ocn and C-terminal hexapeptide activation of this receptor. In addition, selective deletionmore » of Gprc6a in β-cells (Gprc6a β-cell-cko) by crossing Gprc6a flox/flox mice with Ins2-Cre mice resulted in reduced pancreatic weight, islet number, insulin protein content, and insulin message expression. Both islet size and β-cell proliferation were reduced in Gprc6a β-cell-cko compared with control mice. Gprc6a β-cell-cko exhibited abnormal glucose tolerance, but normal insulin sensitivity. Islets isolated from Gprc6a β-cell-cko mice showed reduced insulin simulation index in response to Ocn. Here, these data establish the structural basis for Ocn direct activation of GPRC6A and confirm a role for GPRC6A in regulating β-cell proliferation and insulin secretion.« less

Cell surface chondroitin sulfate glycosaminoglycan in melanoma: role in the activation of pro-MMP-2 (pro-gelatinase A)

PubMed Central

Iida, Joji; Wilhelmson, Krista L.; Ng, Janet; Lee, Peter; Morrison, Charlotte; Tam, Eric; Overall, Christopher M.; McCarthy, James B.

2007-01-01

We previously reported that CS (chondroitin sulfate) GAG (glycosaminoglycan), expressed on MCSP (melanoma-specific CS proteoglycan), is important for regulating MT3-MMP [membrane-type 3 MMP (matrix metalloproteinase)]-mediated human melanoma invasion and gelatinolytic activity in vitro. In the present study, we sought to determine if CS can directly enhance MT3-MMP-mediated activation of pro-MMP-2. Co-immunoprecipitation studies suggest that MCSP forms a complex with MT3-MMP and MMP-2 on melanoma cell surface. When melanoma cells were treated with βDX (p-nitro-β-D-xylopyranoside) to inhibit coupling of CS on the core protein, both active form and proform of MMP-2 were no longer co-immunoprecipitated with either MCSP or MT3-MMP, suggesting a model in which CS directly binds to MMP-2 and presents the gelatinase to MT3-MMP to be activated. By using recombinant proteins, we determined that MT3-MMP directly activates pro-MMP-2 and that this activation requires the interaction of the C-terminal domain of pro-MMP-2 with MT3-MMP. Activation of pro-MMP-2 by suboptimal concentrations of MT3-MMP is also significantly enhanced in the presence of excess C4S (chondroitin 4-sulfate), whereas C6S (chondroitin 6-sulfate) or low-molecular-mass hyaluronan was ineffective. Affinity chromatography studies using CS isolated from aggrecan indicate that the catalytic domain of MT3-MMP and the C-terminal domain of MMP-2 directly bind to the GAG. Thus the direct binding of pro-MMP-2 with CS through the C-domain would present the catalytic domain of pro-MMP-2 to MT3-MMP, which facilitates the generation of the active form of MMP-2. These results suggest that C4S, which is expressed on tumour cell surface, can function to bind to pro-MMP-2 and facilitate its activation by MT3-MMP-expressing tumour cells to enhance invasion and metastasis. PMID:17217338

IL-33 activates eosinophils of visceral adipose tissue both directly and via innate lymphoid cells.

PubMed

Hashiguchi, Masaaki; Kashiwakura, Yuji; Kojima, Hidefumi; Kobayashi, Ayano; Kanno, Yumiko; Kobata, Tetsuji

2015-03-01

Eosinophils are multifunctional leukocytes involved in allergic reactions as well as adipose tissue regulation. IL-5 is required for eosinophil survival; however, the in vivo mechanisms of eosinophil regulation are not fully understood. A tg mouse model with il5 promoter-driven EGFP expression was established for detecting the IL-5-producing cells in vivo. Il5-egfp tg mice expressed high levels of EGFP in gonadal adipose tissue (GAT) cells. EGFP(+) cells in GAT were mainly group 2 innate lymphoid cells (ILCs). IL-33 preferentially expanded EGFP(+) cells and eosinophils in GAT in vivo. EGFP(+) ILCs were found to upregulate prg2 mRNA expression in GAT eosinophils. These results demonstrate that ILCs activate eosinophils in GAT. The blockage of IL-33Rα, on the other hand, did not impair EGFP(+) ILC numbers but did impair eosinophil numbers in vivo. GAT eosinophils expressed IL-33Rα and IL-33 expanded eosinophil numbers in CD90(+) cell-depleted mice. IL-33 was further observed to induce the expression of retnla and epx mRNA in eosinophils. These findings demonstrate that IL-33 directly activates eosinophils in GAT, and together with our other findings described above, our findings show that IL-33 has dual pathways via which it activates eosinophils in vivo: a direct activation pathway and a group 2 ILC-mediated pathway. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The PBX1 lupus susceptibility gene regulates CD44 expression.

PubMed

Niu, Yuxin; Sengupta, Mayami; Titov, Anton A; Choi, Seung-Chul; Morel, Laurence

2017-05-01

PBX1-d is novel splice isoform of pre-B-cell leukemia homeobox 1 (PBX1) that lacks its DNA-binding and Hox-binding domains, and functions as a dominant negative. We have shown that PBX1-d expression in CD4 + T cells is associated with systemic lupus erythematosus (SLE) in a mouse model as well as in human subjects. More specifically, PBX1-d expression leads to the production of autoreactive activated CD4+ T cells, a reduced frequency and function of Foxp3+ regulatory T (Treg) cells and an expansion of follicular helper T (Tfh) cells. Very little is known about the function of PBX1 in T cells, except that it directly regulates the expression of miRNAs associated with Treg and Tfh homeostasis. In the present study, we show that PBX1 directly regulated the expression of CD44, a marker of T cell activation. Two PBX1 binding sites in the promoter directly regulated CD44 expression, with PBX1-d driving a higher expression than the normal isoform PBX1-b. In addition, mutations in each of the two binding sites had different effects of PBX1-b and PBX1-d. Finally, we showed that an enhanced recruitment of co-factor MEIS by PBX1-d over PBX1-b, while there was no difference for co-factor PREP1 recruitment. Therefore, this study demonstrates that the lupus-associated PBX1-d isoform directly transactivates CD44, a marker of CD44 activation and memory, and that it has different DNA binding and co-factor recruitment relative to the normal isoform. Taken together, these results confirm that PBX1 directly regulates genes related to T cell activation and shows that the lupus-associated isoform PBX1-d has unique molecular functions. Copyright © 2017 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toriello, Nicholas M.; Douglas, Erik S.; Mathies, Richard A.

A microchip that performs directed capture and chemical activation of surface-modified single-cells has been developed. The cell-capture system is comprised of interdigitated gold electrodes microfabricated on a glass substrate within PDMS channels. The cell surface is labeled with thiol functional groups using endogenous RGD receptors and adhesion to exposed gold pads on the electrodes is directed by applying a driving electric potential. Multiple cell types can thus be sequentially and selectively captured on desired electrodes. Single-cell capture efficiency is optimized by varying the duration of field application. Maximum single-cell capture is attained for the 10 min trial, with 63+-9 percentmore » (n=30) of the electrode pad rows having a single cell. In activation studies, single M1WT3 CHO cells loaded with the calcium-sensitive dye fluo-4 AM were captured; exposure to the muscarinic agonist carbachol increased the fluorescence to 220+-74percent (n=79) of the original intensity. These results demonstrate the ability to direct the adhesion of selected living single cells on electrodes in a microfluidic device and to analyze their response to chemical stimuli.« less

MERTK as negative regulator of human T cell activation

PubMed Central

Cabezón, Raquel; Carrera-Silva, E. Antonio; Flórez-Grau, Georgina; Errasti, Andrea E.; Calderón-Gómez, Elisabeth; Lozano, Juan José; España, Carolina; Ricart, Elena; Panés, Julián; Rothlin, Carla Vanina; Benítez-Ribas, Daniel

2015-01-01

The aim of this study was to test the hypothesis whether MERTK, which is up-regulated in human DCs treated with immunosuppressive agents, is directly involved in modulating T cell activation. MERTK is a member of the TAM family and contributes to regulating innate immune response to ACs by inhibiting DC activation in animal models. However, whether MERTK interacts directly with T cells has not been addressed. Here, we show that MERTK is highly expressed on dex-induced human tol-DCs and participates in their tolerogenic effect. Neutralization of MERTK in allogenic MLR, as well as autologous DC–T cell cultures, leads to increased T cell proliferation and IFN-γ production. Additionally, we identify a previously unrecognized noncell-autonomous regulatory function of MERTK expressed on DCs. Mer-Fc protein, used to mimic MERTK on DCs, suppresses naïve and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK ligand PROS1. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine proproliferative mechanism. Collectively, these results suggest that MERTK on DCs controls T cell activation and expansion through the competition for PROS1 interaction with MERTK in the T cells. In conclusion, this report identified MERTK as a potent suppressor of T cell response. PMID:25624460

Lgr5+ Cells Regenerate Hair Cells via Proliferation and Direct Transdifferentiation in Damaged Neonatal Mouse Utricle

PubMed Central

Wang, Tian; Chai, Renjie; Kim, Grace S.; Pham, Nicole; Jansson, Lina; Nguyen, Duc-Huy; Kuo, Bryan; May, Lindsey; Zuo, Jian; Cunningham, Lisa L.; Cheng, Alan G.

2015-01-01

Recruitment of endogenous progenitors is critical during tissue repair. The inner ear utricle requires mechanosensory hair cells (HCs) to detect linear acceleration. After damage, non-mammalian utricles regenerate HCs via both proliferation and direct transdifferentiation. In adult mammals, limited transdifferentiation from unidentified progenitors occurs to regenerate extrastriolar Type II HCs. Here, we show that HC damage in neonatal mouse utricle activates the Wnt target gene Lgr5 in striolar supporting cells. Lineage tracing and time-lapse microscopy reveal that Lgr5+ cells transdifferentiate into HC-like cells in vitro. In contrast to adults, HC ablation in neonatal utricles in vivo recruits Lgr5+ cells to regenerate striolar HCs through mitotic and transdifferentiation pathways. Both Type I and II HCs are regenerated, and regenerated HCs display stereocilia and synapses. Lastly, stabilized β-catenin in Lgr5+ cells enhances mitotic activity and HC regeneration. Thus Lgr5 marks Wnt-regulated, damage-activated HC progenitors and may help uncover factors driving mammalian HC regeneration. PMID:25849379

Comparative analysis of signature genes in PRRSV-infected porcine monocyte-derived dendritic cells at differential activation statuses

USDA-ARS?s Scientific Manuscript database

Activation statuses of monocytic cells including monocytes, macrophages and dendritic cells (DCs) are critically important for antiviral immunity. In particular, some devastating viruses, including porcine reproductive and respiratory syndrome virus (PRRSV), are capable of directly infecting these c...

Mapping organelle motion reveals a vesicular conveyor belt spatially replenishing secretory vesicles in stimulated chromaffin cells.

PubMed

Maucort, Guillaume; Kasula, Ravikiran; Papadopulos, Andreas; Nieminen, Timo A; Rubinsztein-Dunlop, Halina; Meunier, Frederic A

2014-01-01

How neurosecretory cells spatially adjust their secretory vesicle pools to replenish those that have fused and released their hormonal content is currently unknown. Here we designed a novel set of image analyses to map the probability of tracked organelles undergoing a specific type of movement (free, caged or directed). We then applied our analysis to time-lapse z-stack confocal imaging of secretory vesicles from bovine Chromaffin cells to map the global changes in vesicle motion and directionality occurring upon secretagogue stimulation. We report a defined region abutting the cortical actin network that actively transports secretory vesicles and is dissipated by actin and microtubule depolymerizing drugs. The directionality of this "conveyor belt" towards the cell surface is activated by stimulation. Actin and microtubule networks therefore cooperatively probe the microenvironment to transport secretory vesicles to the periphery, providing a mechanism whereby cells globally adjust their vesicle pools in response to secretagogue stimulation.

Inhibition of the cellular function of perforin by 1-amino-2,4-dicyanopyrido[1,2-a]benzimidazoles.

PubMed

Lyons, Dani M; Huttunen, Kristiina M; Browne, Kylie A; Ciccone, Annette; Trapani, Joseph A; Denny, William A; Spicer, Julie A

2011-07-01

A high throughput screen showed the ability of a 1-amino-2,4-dicyanopyrido[1,2-a]benzimidazole analogue to directly inhibit the lytic activity of the pore-forming protein perforin. A series of analogues were prepared to study structure-activity relationships (SAR) for the this activity, either directly added to cells or released in situ by KHYG-1 NK cells, at non-toxic concentrations. These studies showed that the pyridobenzimidazole moiety was required for effective activity, with strongly basic centres disfavoured. This class of compounds was relatively unaffected by the addition of serum, which was not the case for a previous class of direct inhibitors. Copyright © 2011 Elsevier Ltd. All rights reserved.

Curcumin Inhibits CD4+ T Cell Activation, but Augments CD69 Expression and TGF-β1-Mediated Generation of Regulatory T Cells at Late Phase

PubMed Central

Kim, Girak; Jang, Mi Seon; Son, Young Min; Seo, Min Ji; Ji, Sang Yun; Han, Seung Hyun; Jung, In Duk; Park, Yeong-Min; Jung, Hyun Jung; Yun, Cheol-Heui

2013-01-01

Background Curcumin is a promising candidate for a natural medicinal agent to treat chronic inflammatory diseases. Although CD4+ T cells have been implicated in the pathogenesis of chronic inflammation, whether curcumin directly regulates CD4+ T cells has not been definitively established. Here, we showed curcumin-mediated regulation of CD2/CD3/CD28-initiated CD4+ T cell activation in vitro. Methodology/Principal Findings Primary human CD4+ T cells were stimulated with anti-CD2/CD3/CD28 antibody-coated beads as an in vitro surrogate system for antigen presenting cell-T cell interaction and treated with curcumin. We found that curcumin suppresses CD2/CD3/CD28-initiated CD4+ T cell activation by inhibiting cell proliferation, differentiation and cytokine production. On the other hand, curcumin attenuated the spontaneous decline of CD69 expression and indirectly increased expression of CCR7, L-selectin and Transforming growth factor-β1 (TGF-β1) at the late phase of CD2/CD3/CD28-initiated T cell activation. Curcumin-mediated up-regulation of CD69 at late phase was associated with ERK1/2 signaling. Furthermore, TGF-β1 was involved in curcumin-mediated regulation of T cell activation and late-phase generation of regulatory T cells. Conclusions/Significance Curcumin not merely blocks, but regulates CD2/CD3/CD28-initiated CD4+ T cell activation by augmenting CD69, CCR7, L-selectin and TGF-β1 expression followed by regulatory T cell generation. These results suggest that curcumin could directly reduce T cell-dependent inflammatory stress by modulating CD4+ T cell activation at multiple levels. PMID:23658623

Traffic jam functions in a branched pathway from Notch activation to niche cell fate.

PubMed

Wingert, Lindsey; DiNardo, Stephen

2015-07-01

The niche directs key behaviors of its resident stem cells, and is thus crucial for tissue maintenance, repair and longevity. However, little is known about the genetic pathways that guide niche specification and development. The male germline stem cell niche in Drosophila houses two stem cell populations and is specified within the embryonic gonad, thus making it an excellent model for studying niche development. The hub cells that form the niche are specified early by Notch activation. Over the next few hours, these individual cells then cluster together and take up a defined position before expressing markers of hub cell differentiation. This timing suggests that there are other factors for niche development yet to be defined. Here, we have identified a role for the large Maf transcription factor Traffic jam (Tj) in hub cell specification downstream of Notch. Tj downregulation is the first detectable effect of Notch activation in hub cells. Furthermore, Tj depletion is sufficient to generate ectopic hub cells that can recruit stem cells. Surprisingly, ectopic niche cells in tj mutants remain dispersed in the absence of Notch activation. This led us to uncover a branched pathway downstream of Notch in which Bowl functions to direct hub cell assembly in parallel to Tj downregulation. © 2015. Published by The Company of Biologists Ltd.

A DIRECT LIGHT EFFECT ON MAINTAINING PHOTOSYNTHETIC ACTIVITY OF NITELLA CHLOROPLASTS

PubMed Central

Craig, I. W.; Gibor, A.

1970-01-01

The chloroplasts of internodal cells of Nitella are fixed to a stationary layer of cytoplasm whereas the nuclei and most of the cytoplasm stream along the longitudinal axis. Isolated internodal cells were maintained for several days with half the cell kept in the dark, the other half kept under continuous light. Photosynthetic activity of the cells was checked by placing the cell evenly illuminated in a 14CO2 atmosphere. Chloroplasts of the previously dark half of the cell were found to fix only half as much CO2 as the chloroplasts which were continuously illuminated. These results are discussed in relation to the possible direct effect of light on biosynthetic reactions of mature chloroplasts. PMID:5411077

Mechanism of action of rapalogues: the antiangiogenic hypothesis.

PubMed

Faivre, Sandrine; Raymond, Eric

2008-11-01

mTOR interacts with multiple proteins involved in major signal transduction pathways controlling cell growth, proliferation, and apoptosis. mTOR is acknowledged to play major roles in cellular interplays between cancer and stroma cells, including endothelial cells. Rapalogues demonstrated antitumour activity in several hypervascularized tumours in clinical trials. Whether rapalogues directly affect cancer cells or other stroma cells in tumours remains poorly understood. Knowing whether rapalogues act directly against cancer cells and/or could be considered as antiangiogenic agents has major implications in terms of medical indications and may help to further improve their drug development. Herein, we hypothesize that current rapalogues demonstrating activity in hypervascularized tumours may primarily act through antiangiogenic effects in patients, a hypothesis that certainly requires further translational investigations.

The Mast Cell Degranulator Compound 48/80 Directly Activates Neurons

PubMed Central

Schemann, Michael; Kugler, Eva Maria; Buhner, Sabine; Eastwood, Christopher; Donovan, Jemma; Jiang, Wen; Grundy, David

2012-01-01

Background Compound 48/80 is widely used in animal and tissue models as a “selective” mast cell activator. With this study we demonstrate that compound 48/80 also directly activates enteric neurons and visceral afferents. Methodology/Principal Findings We used in vivo recordings from extrinsic intestinal afferents together with Ca++ imaging from primary cultures of DRG and nodose neurons. Enteric neuronal activation was examined by Ca++ and voltage sensitive dye imaging in isolated gut preparations and primary cultures of enteric neurons. Intraluminal application of compound 48/80 evoked marked afferent firing which desensitized on subsequent administration. In egg albumen-sensitized animals, intraluminal antigen evoked a similar pattern of afferent activation which also desensitized on subsequent exposure to antigen. In cross-desensitization experiments prior administration of compound 48/80 failed to influence the mast cell mediated response. Application of 1 and 10 µg/ml compound 48/80 evoked spike discharge and Ca++ transients in enteric neurons. The same nerve activating effect was observed in primary cultures of DRG and nodose ganglion cells. Enteric neuron cultures were devoid of mast cells confirmed by negative staining for c-kit or toluidine blue. In addition, in cultured enteric neurons the excitatory action of compound 48/80 was preserved in the presence of histamine H1 and H2 antagonists. The mast cell stabilizer cromolyn attenuated compound 48/80 and nicotine evoked Ca++ transients in mast cell-free enteric neuron cultures. Conclusions/Significance The results showed direct excitatory action of compound 48/80 on enteric neurons and visceral afferents. Therefore, functional changes measured in tissue or animal models may involve a mast cell independent effect of compound 48/80 and cromolyn. PMID:23272218

Directed Evolution to Engineer Monobody for FRET Biosensor Assembly and Imaging at Live-Cell Surface.

PubMed

Limsakul, Praopim; Peng, Qin; Wu, Yiqian; Allen, Molly E; Liang, Jing; Remacle, Albert G; Lopez, Tyler; Ge, Xin; Kay, Brian K; Zhao, Huimin; Strongin, Alex Y; Yang, Xiang-Lei; Lu, Shaoying; Wang, Yingxiao

2018-04-19

Monitoring enzymatic activities at the cell surface is challenging due to the poor efficiency of transport and membrane integration of fluorescence resonance energy transfer (FRET)-based biosensors. Therefore, we developed a hybrid biosensor with separate donor and acceptor that assemble in situ. The directed evolution and sequence-function analysis technologies were integrated to engineer a monobody variant (PEbody) that binds to R-phycoerythrin (R-PE) dye. PEbody was used for visualizing the dynamic formation/separation of intercellular junctions. We further fused PEbody with the enhanced CFP and an enzyme-specific peptide at the extracellular surface to create a hybrid FRET biosensor upon R-PE capture for monitoring membrane-type-1 matrix metalloproteinase (MT1-MMP) activities. This biosensor revealed asymmetric distribution of MT1-MMP activities, which were high and low at loose and stable cell-cell contacts, respectively. Therefore, directed evolution and rational design are promising tools to engineer molecular binders and hybrid FRET biosensors for monitoring molecular regulations at the surface of living cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

Silver Nanoparticle-Directed Mast Cell Degranulation Is Mediated through Calcium and PI3K Signaling Independent of the High Affinity IgE Receptor

PubMed Central

Alsaleh, Nasser B.; Persaud, Indushekhar; Brown, Jared M.

2016-01-01

Engineered nanomaterial (ENM)-mediated toxicity often involves triggering immune responses. Mast cells can regulate both innate and adaptive immune responses and are key effectors in allergic diseases and inflammation. Silver nanoparticles (AgNPs) are one of the most prevalent nanomaterials used in consumer products due to their antimicrobial properties. We have previously shown that AgNPs induce mast cell degranulation that was dependent on nanoparticle physicochemical properties. Furthermore, we identified a role for scavenger receptor B1 (SR-B1) in AgNP-mediated mast cell degranulation. However, it is completely unknown how SR-B1 mediates mast cell degranulation and the intracellular signaling pathways involved. In the current study, we hypothesized that SR-B1 interaction with AgNPs directs mast cell degranulation through activation of signal transduction pathways that culminate in an increase in intracellular calcium signal leading to mast cell degranulation. For these studies, we utilized bone marrow-derived mast cells (BMMC) isolated from C57Bl/6 mice and RBL-2H3 cells (rat basophilic leukemia cell line). Our data support our hypothesis and show that AgNP-directed mast cell degranulation involves activation of PI3K, PLCγ and an increase in intracellular calcium levels. Moreover, we found that influx of extracellular calcium is required for the cells to degranulate in response to AgNP exposure and is mediated at least partially via the CRAC channels. Taken together, our results provide new insights into AgNP-induced mast cell activation that are key for designing novel ENMs that are devoid of immune system activation. PMID:27907088

Low direct cytotoxicity of loxoprofen on gastric mucosal cells.

PubMed

Yamakawa, Naoki; Suemasu, Shintaro; Kimoto, Ayumi; Arai, Yasuhiro; Ishihara, Tomoaki; Yokomizo, Kazumi; Okamoto, Yoshinari; Otsuka, Masami; Tanaka, Ken-Ichiro; Mizushima, Tohru

2010-01-01

Pro-drugs of non-steroidal anti-inflammatory drugs (NSAIDs), such as loxoprofen are widely used for clinical purposes because they are not so harmful to the gastrointestinal mucosa. We recently showed that NSAIDs such as indomethacin and celecoxib have direct cytotoxicity (ability to induce necrosis and apoptosis in gastric mucosal cells) due to their membrane permeabilizing activities, which is involved in NSAID-induced gastric lesions. We show here that under conditions where indomethacin and celecoxib clearly induce necrosis and apoptosis, loxoprofen and its active metabolite loxoprofen-OH, do not have such effects in primary culture of guinea pig gastric mucosal cells. Loxoprofen and loxoprofen-OH induced apoptosis more effectively in cultured human gastric cancer cells than in the primary culture. Loxoprofen and loxoprofen-OH exhibited much lower membrane permeabilizing activities than did indomethacin and celecoxib. We thus consider that the low direct cytotoxicity of loxoprofen observed in vitro is involved in its relative safety on production of gastric lesions in clinical situation.

Microwave-assisted synthesis of palladium nanoparticles intercalated nitrogen doped reduced graphene oxide and their electrocatalytic activity for direct-ethanol fuel cells.

PubMed

Kumar, Rajesh; da Silva, Everson T S G; Singh, Rajesh K; Savu, Raluca; Alaferdov, Andrei V; Fonseca, Leandro C; Carossi, Lory C; Singh, Arvind; Khandka, Sarita; Kar, Kamal K; Alves, Oswaldo L; Kubota, Lauro T; Moshkalev, Stanislav A

2018-04-01

Palladium nanoparticles decorated reduced graphene oxide (Pd-rGO) and palladium nanoparticles intercalated inside nitrogen doped reduced graphene oxide (Pd-NrGO) hybrids have been synthesized by applying a very simple, fast and economic route using microwave-assisted in-situ reduction and exfoliation method. The Pd-NrGO hybrids materials show good activity as catalyst for ethanol electro oxidation for direct ethanol fuel cells (DEFCs) as compared to Pd-rGO hybrids. The enhanced direct ethanol fuel cell can serve as alternative to fossil fuels because it is renewable and environmentally-friendly with a high energy conversion efficiency and low pollutant emission. As proof of concept, the electrocatalytic activity of Pd-NrGO hybrid material was accessed by cyclic voltammetry in presence of ethanol to evaluate its applicability in direct-ethanol fuel cells (DEFCs). The Pd-NrGO catalyst presented higher electro active surface area (∼6.3 m 2  g -1 ) for ethanol electro-oxidation when compared to Pd-rGO hybrids (∼3.7 m 2  g -1 ). Despite the smaller catalytic activity of Pd-NrGO, which was attributed to the lower exfoliation rate of this material in relation to the Pd-rGO, Pd-NrGO showed to be very promising and its catalytic activity can be further improved by tuning the synthesis parameters to increase the exfoliation rate. Copyright © 2018 Elsevier Inc. All rights reserved.

GH Mediates Exercise-Dependent Activation of SVZ Neural Precursor Cells in Aged Mice

PubMed Central

Blackmore, Daniel G.; Vukovic, Jana; Waters, Michael J.; Bartlett, Perry F.

2012-01-01

Here we demonstrate, both in vivo and in vitro, that growth hormone (GH) mediates precursor cell activation in the subventricular zone (SVZ) of the aged (12-month-old) brain following exercise, and that GH signaling stimulates precursor activation to a similar extent to exercise. Our results reveal that both addition of GH in culture and direct intracerebroventricular infusion of GH stimulate neural precursor cells in the aged brain. In contrast, no increase in neurosphere numbers was observed in GH receptor null animals following exercise. Continuous infusion of a GH antagonist into the lateral ventricle of wild-type animals completely abolished the exercise-induced increase in neural precursor cell number. Given that the aged brain does not recover well after injury, we investigated the direct effect of exercise and GH on neural precursor cell activation following irradiation. This revealed that physical exercise as well as infusion of GH promoted repopulation of neural precursor cells in irradiated aged animals. Conversely, infusion of a GH antagonist during exercise prevented recovery of precursor cells in the SVZ following irradiation. PMID:23209615

Priming Endothelial Cells With a Melanoma-Derived Extracellular Matrix Triggers the Activation of αvβ3/VEGFR2 Axis.

PubMed

Helal-Neto, Edward; Brandão-Costa, Renata M; Saldanha-Gama, Roberta; Ribeiro-Pereira, Cristiane; Midlej, Victor; Benchimol, Marlene; Morandi, Verônica; Barja-Fidalgo, Christina

2016-11-01

The unique composition of tumor-produced extracellular matrix (ECM) can be a determining factor in changing the profile of endothelial cells in the tumor microenvironment. As the main receptor for ECM proteins, integrins can activate a series of signaling pathways related to cell adhesion, migration, and differentiation of endothelial cells that interact with ECM proteins. We studied the direct impact of the decellularized ECM produced by a highly metastatic human melanoma cell line (MV3) on the activation of endothelial cells and identified the intracellular signaling pathways associated with cell differentiation. Our data show that compared to the ECM derived from a human melanocyte cell line (NGM-ECM), ECM produced by a melanoma cell line (MV3-ECM) is considerably different in ultrastructural organization and composition and possesses a higher content of tenascin-C and laminin and a lower expression of fibronectin. When cultured directly on MV3-ECM, endothelial cells change morphology and show increased adhesion, migration, proliferation, and tubulogenesis. Interaction of endothelial cells with MV3-ECM induces the activation of integrin signaling, increasing FAK phosphorylation and its association with Src, which activates VEGFR2, potentiating the receptor response to VEGF. The blockage of αvβ3 integrin inhibited the FAK-Src association and VEGFR activation, thus reducing tubulogenesis. Together, our data suggest that the interaction of endothelial cells with the melanoma-ECM triggers integrin-dependent signaling, leading to Src pathway activation that may potentiate VEGFR2 activation and up-regulate angiogenesis. J. Cell. Physiol. 231: 2464-2473, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

In vitro studies with renal proximal tubule cells show direct cytotoxicity of Androctonus australis hector scorpion venom triggered by oxidative stress, caspase activation and apoptosis

PubMed Central

Saidani, Chanez; Hammoudi-Triki, Djelila; Laraba-Djebari, Fatima; Taub, Mary

2016-01-01

Scorpion envenomation injures a number of organs, including the kidney. Mechanisms proposed to explain the renal tubule injury include direct effects of venom on tubule epithelial cells, as well as indirect effects of the autonomic nervous system, and inflammation. Here, we report direct effects of Androctonus australis hector (Aah) scorpion venom on the viability of Renal Proximal Tubule (RPT) cells in vitro, unlike distal tubule and collecting duct cells. Extensive NucGreen nuclear staining was observed in immortalized rabbit RPT cells following treatment with Aah venom, consistent with cytotoxicity. The involvement of oxidative stress is supported by the observations that 1) anti-oxidants mitigated the Aah venom-induced decrease in the number of viable RPT cells, and 2) Aah venom-treated RPT cells were intensively stained with the CellROX® Deep Red reagent, an indicator of Reactive Oxygen Species (ROS). Relevance to normal RPT cells is supported by the red fluorescence observed in Aah venom treated primary rabbit RPT cell cultures following their incubation with the Flica reagent (indicative of caspase activation and apoptosis), and the green fluorescence of Sytox Green (indicative of dead cells). PMID:27470530

Testosterone decreases urinary bladder smooth muscle excitability via novel signaling mechanism involving direct activation of the BK channels

PubMed Central

Hristov, Kiril L.; Parajuli, Shankar P.; Provence, Aaron

2016-01-01

In addition to improving sexual function, testosterone has been reported to have beneficial effects in ameliorating lower urinary tract symptoms by increasing bladder capacity and compliance, while decreasing bladder pressure. However, the cellular mechanisms by which testosterone regulates detrusor smooth muscle (DSM) excitability have not been elucidated. Here, we used amphotericin-B perforated whole cell patch-clamp and single channel recordings on inside-out excised membrane patches to investigate the regulatory role of testosterone in guinea pig DSM excitability. Testosterone (100 nM) significantly increased the depolarization-induced whole cell outward currents in DSM cells. The selective pharmacological inhibition of the large-conductance voltage- and Ca2+-activated K+ (BK) channels with paxilline (1 μM) completely abolished this stimulatory effect of testosterone, suggesting a mechanism involving BK channels. At a holding potential of −20 mV, DSM cells exhibited transient BK currents (TBKCs). Testosterone (100 nM) significantly increased TBKC activity in DSM cells. In current-clamp mode, testosterone (100 nM) significantly hyperpolarized the DSM cell resting membrane potential and increased spontaneous transient hyperpolarizations. Testosterone (100 nM) rapidly increased the single BK channel open probability in inside-out excised membrane patches from DSM cells, clearly suggesting a direct BK channel activation via a nongenomic mechanism. Live-cell Ca2+ imaging showed that testosterone (100 nM) caused a decrease in global intracellular Ca2+ concentration, consistent with testosterone-induced membrane hyperpolarization. In conclusion, the data provide compelling mechanistic evidence that under physiological conditions, testosterone at nanomolar concentrations directly activates BK channels in DSM cells, independent from genomic testosterone receptors, and thus regulates DSM excitability. PMID:27605581

Evidence that the modulation of membrane-associated protein kinase C activity by an endogenous inhibitor plays a role in N1E-115 murine neuroblastoma cell differentiation.

PubMed

Chakravarthy, B R; Wong, J; Durkin, J P

1995-10-01

Murine neuroblastoma cells, N1E-115, were induced to differentiate into neuron-like cells by serum deprivation for 18 h. As previous studies have shown that the suppression of protein kinase C (PKC) activity by selective inhibitors or neutralizing antibodies induces neuroblastoma cells to differentiate, we tested the hypothesis that serum deprivation may cause a rapid loss in membrane PKC activity that occurs well before the morphological changes that are characteristic of cell differentiation. A significant reduction in particulate (membrane) PKC activity was indeed observed within 3 h of serum withdrawal when enzyme activity was measured in intact native membranes by the recently described in vitro "direct" assay. This rapid reduction in enzyme activity was confirmed by the decreased phosphorylation of the MARCKS protein, an endogenous PKC-selective substrate, in intact cells. The decrease in membrane PKC activity occurred without any loss in the amount of membrane-associated enzyme, suggesting that some factor(s) resident in neuroblastoma membranes was suppressing PKC activity. Indeed, results indicate the presence of an endogenous inhibitor of PKC tightly associated with neuroblastoma membranes. This inhibitory activity increased in the membranes of cells subjected to serum deprivation, raising the possibility that it was likely responsible for the decline in membrane PKC activity in differentiating N1E-115 cells. Preliminary characterization indicated that the inhibitory activity is a protein and is localized mainly in the membrane fraction. Thus, these results demonstrate directly that endogenous inhibitor can regulate membrane-associated PKC activity in cells and thereby modulate PKC-related neuronal functions.

Calmodulin-mediated activation of Akt regulates survival of c-Myc-overexpressing mouse mammary carcinoma cells.

PubMed

Deb, Tushar B; Coticchia, Christine M; Dickson, Robert B

2004-09-10

c-Myc-overexpressing mammary epithelial cells are proapoptotic; their survival is strongly promoted by epidermal growth factor (EGF). We now demonstrate that EGF-induced Akt activation and survival in transgenic mouse mammary tumor virus-c-Myc mouse mammary carcinoma cells are both calcium/calmodulin-dependent. Akt activation is abolished by the phospholipase C-gamma inhibitor U-73122, by the intracellular calcium chelator BAPTA-AM, and by the specific calmodulin antagonist W-7. These results implicate calcium/calmodulin in the activation of Akt in these cells. In addition, Akt activation by serum and insulin is also inhibited by W-7. EGF-induced and calcium/calmodulin-mediated Akt activation occurs in both tumorigenic and non-tumorigenic mouse and human mammary epithelial cells, independent of their overexpression of c-Myc. These results imply that calcium/calmodulin may be a common regulator of Akt activation, irrespective of upstream receptor activator, mammalian species, and transformation status in mammary epithelial cells. However, only c-Myc-overexpressing mouse mammary carcinoma cells (but not normal mouse mammary epithelial cells) undergo apoptosis in the presence of the calmodulin antagonist W-7, indicating the vital selective role of calmodulin for survival of these cells. Calcium/calmodulin-regulated Akt activation is mediated directly by neither calmodulin kinases nor phosphatidylinositol 3-kinase (PI-3 kinase). Pharmacological inhibitors of calmodulin kinase kinase and calmodulin kinases II and III do not inhibit EGF-induced Akt activation, and calmodulin antagonist W-7 does not inhibit phosphotyrosine-associated PI-3 kinase activation. Akt is, however, co-immunoprecipitated with calmodulin in an EGF-dependent manner, which is inhibited by calmodulin antagonist W-7. We conclude that calmodulin may serve a vital regulatory function to direct the localization of Akt to the plasma membrane for its activation by PI-3 kinase.

Persistent neural activity in head direction cells

NASA Technical Reports Server (NTRS)

Taube, Jeffrey S.; Bassett, Joshua P.; Oman, C. M. (Principal Investigator)

2003-01-01

Many neurons throughout the rat limbic system discharge in relation to the animal's directional heading with respect to its environment. These so-called head direction (HD) cells exhibit characteristics of persistent neural activity. This article summarizes where HD cells are found, their major properties, and some of the important experiments that have been conducted to elucidate how this signal is generated. The number of HD and angular head velocity cells was estimated for several brain areas involved in the generation of the HD signal, including the postsubiculum, anterior dorsal thalamus, lateral mammillary nuclei and dorsal tegmental nucleus. The HD cell signal has many features in common with what is known about how neural integration is accomplished in the oculomotor system. The nature of the HD cell signal makes it an attractive candidate for using neural network models to elucidate the signal's underlying mechanisms. The conditions that any network model must satisfy in order to accurately represent how the nervous system generates this signal are highlighted and areas where key information is missing are discussed.

The BCL11A Transcription Factor Directly Activates RAG Gene Expression and V(D)J Recombination

PubMed Central

Lee, Baeck-seung; Dekker, Joseph D.; Lee, Bum-kyu; Iyer, Vishwanath R.; Sleckman, Barry P.; Shaffer, Arthur L.; Ippolito, Gregory C.

2013-01-01

Recombination-activating gene 1 protein (RAG1) and RAG2 are critical enzymes for initiating variable-diversity-joining (VDJ) segment recombination, an essential process for antigen receptor expression and lymphocyte development. The transcription factor BCL11A is required for B cell development, but its molecular function(s) in B cell fate specification and commitment is unknown. We show here that the major B cell isoform, BCL11A-XL, binds the RAG1 promoter and Erag enhancer to activate RAG1 and RAG2 transcription in pre-B cells. We employed BCL11A overexpression with recombination substrates in a cultured pre-B cell line as well as Cre recombinase-mediated Bcl11alox/lox deletion in explanted murine pre-B cells to demonstrate direct consequences of BCL11A/RAG modulation on V(D)J recombination. We conclude that BCL11A is a critical component of a transcriptional network that regulates B cell fate by controlling V(D)J recombination. PMID:23438597

EGCG reverses human neutrophil elastase-induced migration in A549 cells by directly binding to HNE and by regulating α1-AT

PubMed Central

Xiaokaiti, Yilixiati; Wu, Haoming; Chen, Ya; Yang, Haopeng; Duan, Jianhui; Li, Xin; Pan, Yan; Tie, Lu; Zhang, Liangren; Li, Xuejun

2015-01-01

Lung carcinogenesis is a complex process that occurs in unregulated inflammatory environment. EGCG has been extensively investigated as a multi-targeting anti-tumor and anti-inflammatory compound. In this study, we demonstrated a novel mechanism by which EGCG reverses the neutrophil elastase-induced migration of A549 cells. We found that neutrophil elastase directly triggered human adenocarcinoma A549 cell migration and that EGCG suppressed the elevation of tumor cell migration induced by neutrophil elastase. We observed that EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity based on the CDOCKER algorithm, MD stimulation by GROMACS, SPR assay and elastase enzymatic activity assay. As the natural inhibitor of neutrophil elastase, α1-antitrypsin is synthesized in tumor cells. We further demonstrated that the expression of α1-antitrypsin was up-regulated after EGCG treatment in neutrophil elastase-treated A549 cells. We preliminarily discovered that the EGCG-mediated induction of α1-antitrypsin expression might be correlated with the regulatory effect of EGCG on the PI3K/Akt pathway. Overall, our results suggest that EGCG ameliorates the neutrophil elastase-induced migration of A549 cells. The mechanism underlying this effect may include two processes: EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity; EGCG enhances the expression of α1-antitrypsin by regulating the PI3K/AKT pathway. PMID:26177797

Vascular CD39/ENTPD1 Directly Promotes Tumor Cell Growth by Scavenging Extracellular Adenosine Triphosphate12

PubMed Central

Feng, Lili; Sun, Xiaofeng; Csizmadia, Eva; Han, Lihui; Bian, Shu; Murakami, Takashi; Wang, Xin; Robson, Simon C; Wu, Yan

2011-01-01

Extracellular adenosine triphosphate (ATP) is known to boost immune responses in the tumor microenvironment but might also contribute directly to cancer cell death. CD39/ENTPD1 is the dominant ectonucleotidase expressed by endothelial cells and regulatory T cells and catalyzes the sequential hydrolysis of ATP to AMP that is further degraded to adenosine by CD73/ecto-5′-nucleotidase. We have previously shown that deletion of Cd39 results in decreased growth of transplanted tumors in mice, as a result of both defective angiogenesis and heightened innate immune responses (secondary to loss of adenosinergic immune suppression). Whether alterations in local extracellular ATP and adenosine levels as a result of CD39 bioactivity directly affect tumor growth and cytotoxicity has not been investigated to date. We show here that extracellular ATP exerts antitumor activity by directly inhibiting cell proliferation and promoting cancer cell death. ATP-induced antiproliferative effects and cell death are, in large part, mediated through P2X7 receptor signaling. Tumors in Cd39 null mice exhibit increased necrosis in association with P2X7 expression. We further demonstrate that exogenous soluble NTPDase, or CD39 expression by cocultured liver sinusoidal endothelial cells, stimulates tumor cell proliferation and limits cell death triggered by extracellular ATP. Collectively, our findings indicate that local expression of CD39 directly promotes tumor cell growth by scavenging extracellular ATP. Pharmacological or targeted inhibition of CD39 enzymatic activity may find utility as an adjunct therapy in cancer management. PMID:21390184

Paxillin Mediates Sensing of Physical Cues and Regulates Directional Cell Motility by Controlling Lamellipodia Positioning

PubMed Central

Sero, Julia E.; Thodeti, Charles K.; Mammoto, Akiko; Bakal, Chris; Thomas, Sheila; Ingber, Donald E.

2011-01-01

Physical interactions between cells and the extracellular matrix (ECM) guide directional migration by spatially controlling where cells form focal adhesions (FAs), which in turn regulate the extension of motile processes. Here we show that physical control of directional migration requires the FA scaffold protein paxillin. Using single-cell sized ECM islands to constrain cell shape, we found that fibroblasts cultured on square islands preferentially activated Rac and extended lamellipodia from corner, rather than side regions after 30 min stimulation with PDGF, but that cells lacking paxillin failed to restrict Rac activity to corners and formed small lamellipodia along their entire peripheries. This spatial preference was preceded by non-spatially constrained formation of both dorsal and lateral membrane ruffles from 5–10 min. Expression of paxillin N-terminal (paxN) or C-terminal (paxC) truncation mutants produced opposite, but complementary, effects on lamellipodia formation. Surprisingly, pax−/− and paxN cells also formed more circular dorsal ruffles (CDRs) than pax+ cells, while paxC cells formed fewer CDRs and extended larger lamellipodia even in the absence of PDGF. In a two-dimensional (2D) wound assay, pax−/− cells migrated at similar speeds to controls but lost directional persistence. Directional motility was rescued by expressing full-length paxillin or the N-terminus alone, but paxN cells migrated more slowly. In contrast, pax−/− and paxN cells exhibited increased migration in a three-dimensional (3D) invasion assay, with paxN cells invading Matrigel even in the absence of PDGF. These studies indicate that paxillin integrates physical and chemical motility signals by spatially constraining where cells will form motile processes, and thereby regulates directional migration both in 2D and 3D. These findings also suggest that CDRs may correspond to invasive protrusions that drive cell migration through 3D extracellular matrices. PMID:22194823

Ultra-high-throughput screening method for the directed evolution of glucose oxidase.

PubMed

Ostafe, Raluca; Prodanovic, Radivoje; Nazor, Jovana; Fischer, Rainer

2014-03-20

Glucose oxidase (GOx) is used in many industrial processes that could benefit from improved versions of the enzyme. Some improvements like higher activity under physiological conditions and thermal stability could be useful for GOx applications in biosensors and biofuel cells. Directed evolution is one of the currently available methods to engineer improved GOx variants. Here, we describe an ultra-high-throughput screening system for sorting the best enzyme variants generated by directed evolution that incorporates several methodological refinements: flow cytometry, in vitro compartmentalization, yeast surface display, fluorescent labeling of the expressed enzyme, delivery of glucose substrate to the reaction mixture through the oil phase, and covalent labeling of the cells with fluorescein-tyramide. The method enables quantitative screening of gene libraries to identify clones with improved activity and it also allows cells to be selected based not only on the overall activity but also on the specific activity of the enzyme. Copyright © 2014 Elsevier Ltd. All rights reserved.

Tiam1 interaction with the PAR complex promotes talin-mediated Rac1 activation during polarized cell migration

PubMed Central

Wang, Shujie; Watanabe, Takashi; Matsuzawa, Kenji; Katsumi, Akira; Kakeno, Mai; Matsui, Toshinori; Ye, Feng; Sato, Kazuhide; Murase, Kiyoko; Sugiyama, Ikuko; Kimura, Kazushi; Mizoguchi, Akira; Ginsberg, Mark H.; Collard, John G.

2012-01-01

Migrating cells acquire front-rear polarity with a leading edge and a trailing tail for directional movement. The Rac exchange factor Tiam1 participates in polarized cell migration with the PAR complex of PAR3, PAR6, and atypical protein kinase C. However, it remains largely unknown how Tiam1 is regulated and contributes to the establishment of polarity in migrating cells. We show here that Tiam1 interacts directly with talin, which binds and activates integrins to mediate their signaling. Tiam1 accumulated at adhesions in a manner dependent on talin and the PAR complex. The interactions of talin with Tiam1 and the PAR complex were required for adhesion-induced Rac1 activation, cell spreading, and migration toward integrin substrates. Furthermore, Tiam1 acted with talin to regulate adhesion turnover. Thus, we propose that Tiam1, with the PAR complex, binds to integrins through talin and, together with the PAR complex, thereby regulates Rac1 activity and adhesion turnover for polarized migration. PMID:23071154

Localized Ras signaling at the leading edge regulates PI3K, cell polarity, and directional cell movement

PubMed Central

Sasaki, Atsuo T.; Chun, Cheryl; Takeda, Kosuke; Firtel, Richard A.

2004-01-01

During chemotaxis, receptors and heterotrimeric G-protein subunits are distributed and activated almost uniformly along the cell membrane, whereas PI(3,4,5)P3, the product of phosphatidylinositol 3-kinase (PI3K), accumulates locally at the leading edge. The key intermediate event that creates this strong PI(3,4,5)P3 asymmetry remains unclear. Here, we show that Ras is rapidly and transiently activated in response to chemoattractant stimulation and regulates PI3K activity. Ras activation occurs at the leading edge of chemotaxing cells, and this local activation is independent of the F-actin cytoskeleton, whereas PI3K localization is dependent on F-actin polymerization. Inhibition of Ras results in severe defects in directional movement, indicating that Ras is an upstream component of the cell's compass. These results support a mechanism by which localized Ras activation mediates leading edge formation through activation of basal PI3K present on the plasma membrane and other Ras effectors required for chemotaxis. A feedback loop, mediated through localized F-actin polymerization, recruits cytosolic PI3K to the leading edge to amplify the signal. PMID:15534002

Direct Cytoskeleton Forces Cause Membrane Softening in Red Blood Cells

PubMed Central

Rodríguez-García, Ruddi; López-Montero, Iván; Mell, Michael; Egea, Gustavo; Gov, Nir S.; Monroy, Francisco

2015-01-01

Erythrocytes are flexible cells specialized in the systemic transport of oxygen in vertebrates. This physiological function is connected to their outstanding ability to deform in passing through narrow capillaries. In recent years, there has been an influx of experimental evidence of enhanced cell-shape fluctuations related to metabolically driven activity of the erythroid membrane skeleton. However, no direct observation of the active cytoskeleton forces has yet been reported to our knowledge. Here, we show experimental evidence of the presence of temporally correlated forces superposed over the thermal fluctuations of the erythrocyte membrane. These forces are ATP-dependent and drive enhanced flickering motions in human erythrocytes. Theoretical analyses provide support for a direct force exerted on the membrane by the cytoskeleton nodes as pulses of well-defined average duration. In addition, such metabolically regulated active forces cause global membrane softening, a mechanical attribute related to the functional erythroid deformability. PMID:26083919

Detailed Multi-dimensional Modeling of Direct Internal Reforming Solid Oxide Fuel Cells.

PubMed

Tseronis, K; Fragkopoulos, I S; Bonis, I; Theodoropoulos, C

2016-06-01

Fuel flexibility is a significant advantage of solid oxide fuel cells (SOFCs) and can be attributed to their high operating temperature. Here we consider a direct internal reforming solid oxide fuel cell setup in which a separate fuel reformer is not required. We construct a multidimensional, detailed model of a planar solid oxide fuel cell, where mass transport in the fuel channel is modeled using the Stefan-Maxwell model, whereas the mass transport within the porous electrodes is simulated using the Dusty-Gas model. The resulting highly nonlinear model is built into COMSOL Multiphysics, a commercial computational fluid dynamics software, and is validated against experimental data from the literature. A number of parametric studies is performed to obtain insights on the direct internal reforming solid oxide fuel cell system behavior and efficiency, to aid the design procedure. It is shown that internal reforming results in temperature drop close to the inlet and that the direct internal reforming solid oxide fuel cell performance can be enhanced by increasing the operating temperature. It is also observed that decreases in the inlet temperature result in smoother temperature profiles and in the formation of reduced thermal gradients. Furthermore, the direct internal reforming solid oxide fuel cell performance was found to be affected by the thickness of the electrochemically-active anode catalyst layer, although not always substantially, due to the counter-balancing behavior of the activation and ohmic overpotentials.

Glutathione Efflux and Cell Death

PubMed Central

2012-01-01

Abstract Significance: Glutathione (GSH) depletion is a central signaling event that regulates the activation of cell death pathways. GSH depletion is often taken as a marker of oxidative stress and thus, as a consequence of its antioxidant properties scavenging reactive species of both oxygen and nitrogen (ROS/RNS). Recent Advances: There is increasing evidence demonstrating that GSH loss is an active phenomenon regulating the redox signaling events modulating cell death activation and progression. Critical Issues: In this work, we review the role of GSH depletion by its efflux, as an important event regulating alterations in the cellular redox balance during cell death independent from oxidative stress and ROS/RNS formation. We discuss the mechanisms involved in GSH efflux during cell death progression and the redox signaling events by which GSH depletion regulates the activation of the cell death machinery. Future Directions: The evidence summarized here clearly places GSH transport as a central mechanism mediating redox signaling during cell death progression. Future studies should be directed toward identifying the molecular identity of GSH transporters mediating GSH extrusion during cell death, and addressing the lack of sensitive approaches to quantify GSH efflux. Antioxid. Redox Signal. 17, 1694–1713. PMID:22656858

A non-mitotic role for Aurora kinase A as a direct activator of cell migration upon interaction with PLD, FAK and Src

PubMed Central

Mahankali, Madhu; Henkels, Karen M.; Speranza, Francis; Gomez-Cambronero, Julian

2015-01-01

ABSTRACT Timely activation of Aurora kinase A (AURA, also known as AURKA) is vital for centrosome formation and the progression of mitosis. Nonetheless, it is still unclear if and when other cellular functions are activated by AURA. We report here that Src phosphorylates and activates AURA at T288, and AURA also activates focal adhesion kinase (FAK, also known as PTK2), leading to initiation of cell movement. An additional and new way by which AURA is regulated, is by phospholipase D2 (PLD2), which causes AURA activation. In addition, AURA phosphorylates PLD, so both proteins engage in a positive reinforcement loop. AURA and PLD2 form a protein–protein complex and colocalize to cytoplasmic regions in cells. The reason why PLD activates AURA is because of the production of phosphatidic acid by the lipase, which binds directly to AURA, with the region E171–E211 projected to be a phosphatidic-acid-binding pocket. Furthermore, this direct interaction with phosphatidic acid enhances tubulin polymerization and cooperates synergistically with AURA, FAK and Src in yielding a fully effectual cellular migration. Thus, Src and FAK, and PLD and phosphatidic acid are new upstream regulators of AURA that mediate its role in the non-mitotic cellular function of cell migration. PMID:25501815

MMPP Attenuates Non-Small Cell Lung Cancer Growth by Inhibiting the STAT3 DNA-Binding Activity via Direct Binding to the STAT3 DNA-Binding Domain.

PubMed

Son, Dong Ju; Zheng, Jie; Jung, Yu Yeon; Hwang, Chul Ju; Lee, Hee Pom; Woo, Ju Rang; Baek, Song Yi; Ham, Young Wan; Kang, Min Woong; Shong, Minho; Kweon, Gi Ryang; Song, Min Jong; Jung, Jae Kyung; Han, Sang-Bae; Kim, Bo Yeon; Yoon, Do Young; Choi, Bu Young; Hong, Jin Tae

2017-01-01

Rationale: Signal transducer and activator of transcription-3 (STAT3) plays a pivotal role in cancer biology. Many small-molecule inhibitors that target STAT3 have been developed as potential anticancer drugs. While designing small-molecule inhibitors that target the SH2 domain of STAT3 remains the leading focus for drug discovery, there has been a growing interest in targeting the DNA-binding domain (DBD) of the protein. Methods: We demonstrated the potential antitumor activity of a novel, small-molecule (E)-2-methoxy-4-(3-(4-methoxyphenyl)prop-1-en-1-yl)phenol (MMPP) that directly binds to the DBD of STAT3, in patient-derived non-small cell lung cancer (NSCLC) xenograft model as well as in NCI-H460 cell xenograft model in nude mice. Results: MMPP effectively inhibited the phosphorylation of STAT3 and its DNA binding activity in vitro and in vivo . It induced G1-phase cell cycle arrest and apoptosis through the regulation of cell cycle- and apoptosis-regulating genes by directly binding to the hydroxyl residue of threonine 456 in the DBD of STAT3. Furthermore, MMPP showed a similar or better antitumor activity than that of docetaxel or cisplatin. Conclusion: MMPP is suggested to be a potential candidate for further development as an anticancer drug that targets the DBD of STAT3.

Effects of silver nanoparticles on the interactions of neuron- and glia-like cells: Toxicity, uptake mechanisms, and lysosomal tracking.

PubMed

Hsiao, I-Lun; Hsieh, Yi-Kong; Chuang, Chun-Yu; Wang, Chu-Fang; Huang, Yuh-Jeen

2017-06-01

Silver nanoparticles (AgNPs) are commonly used nanomaterials in consumer products. Previous studies focused on its effects on neurons; however, little is known about their effects and uptake mechanisms on glial cells under normal or activated states. Here, ALT astrocyte-like, BV-2 microglia and differentiated N2a neuroblastoma cells were directly or indirectly exposed to 10 nm AgNPs using mono- and co-culture system. A lipopolysaccharide (LPS) was pretreated to activate glial cells before AgNP treatment for mimicking NP exposure under brain inflammation. From mono-culture, ALT took up the most AgNPs and had the lowest cell viability within three cells. Moreover, AgNPs induced H 2 O 2 and NO from ALT/activated ALT and BV-2, respectively. However, AgNPs did not induce cytokines release (IL-6, TNF-α, MCP-1). LPS-activated BV-2 took up more AgNPs than normal BV-2, while the induction of ROS and cytokines from activated cells were diminished. Ca 2+ -regulated clathrin- and caveolae-independent endocytosis and phagocytosis were involved in the AgNP uptake in ALT, which caused more rapid NP translocation to lysosome than in macropinocytosis and clathrin-dependent endocytosis-involved BV-2. AgNPs directly caused apoptosis and necrosis in N2a cells, while by indirect NP exposure to bottom chamber ALT or BV-2 in Transwell, more apoptotic upper chamber N2a cells were observed. Cell viability of BV-2 also decreased in an ALT-BV-2 co-culturing study. The damaged cells correlated to NP-mediated H 2 O 2 release from ALT or NO from BV-2, which indicates that toxic response of AgNPs to neurons is not direct, but indirectly arises from AgNP-induced soluble factors from other glial cells. © 2017 Wiley Periodicals, Inc.

A single-cell spiking model for the origin of grid-cell patterns

PubMed Central

Kempter, Richard

2017-01-01

Spatial cognition in mammals is thought to rely on the activity of grid cells in the entorhinal cortex, yet the fundamental principles underlying the origin of grid-cell firing are still debated. Grid-like patterns could emerge via Hebbian learning and neuronal adaptation, but current computational models remained too abstract to allow direct confrontation with experimental data. Here, we propose a single-cell spiking model that generates grid firing fields via spike-rate adaptation and spike-timing dependent plasticity. Through rigorous mathematical analysis applicable in the linear limit, we quantitatively predict the requirements for grid-pattern formation, and we establish a direct link to classical pattern-forming systems of the Turing type. Our study lays the groundwork for biophysically-realistic models of grid-cell activity. PMID:28968386

Direct Interactions with the Integrin β1 Cytoplasmic Tail Activate the Abl2/Arg Kinase*

PubMed Central

Simpson, Mark A.; Bradley, William D.; Harburger, David; Parsons, Maddy; Calderwood, David A.; Koleske, Anthony J.

2015-01-01

Integrins are heterodimeric α/β extracellular matrix adhesion receptors that couple physically to the actin cytoskeleton and regulate kinase signaling pathways to control cytoskeletal remodeling and adhesion complex formation and disassembly. β1 integrins signal through the Abl2/Arg (Abl-related gene) nonreceptor tyrosine kinase to control fibroblast cell motility, neuronal dendrite morphogenesis and stability, and cancer cell invasiveness, but the molecular mechanisms by which integrin β1 activates Arg are unknown. We report here that the Arg kinase domain interacts directly with a lysine-rich membrane-proximal segment in the integrin β1 cytoplasmic tail, that Arg phosphorylates the membrane-proximal Tyr-783 in the β1 tail, and that the Arg Src homology domain then engages this phosphorylated region in the tail. We show that these interactions mediate direct binding between integrin β1 and Arg in vitro and in cells and activate Arg kinase activity. These findings provide a model for understanding how β1-containing integrins interact with and activate Abl family kinases. PMID:25694433

ARTD1/PARP1 negatively regulates glycolysis by inhibiting hexokinase 1 independent of NAD+ depletion

PubMed Central

Fouquerel, Elise; Goellner, Eva M.; Yu, Zhongxun; Gagné, Jean-Philippe; de Moura, Michelle Barbi; Feinstein, Tim; Wheeler, David; Redpath, Philip; Li, Jianfeng; Romero, Guillermo; Migaud, Marie; Van Houten, Bennett; Poirier, Guy G.; Sobol, Robert W.

2014-01-01

Summary ARTD1 (PARP1) is a key enzyme involved in DNA repair by synthesizing poly(ADP-ribose) (PAR) in response to strand breaks and plays an important role in cell death following excessive DNA damage. ARTD1-induced cell death is associated with NAD+ depletion and ATP loss, however the molecular mechanism of ARTD1-mediated energy collapse remains elusive. Using real-time metabolic measurements, we directly compared the effects of ARTD1 activation and direct NAD+ depletion. We found that ARTD1-mediated PAR synthesis, but not direct NAD+ depletion, resulted in a block to glycolysis and ATP loss. We then established a proteomics based PAR-interactome after DNA damage and identified hexokinase 1 (HK1) as a PAR binding protein. HK1 activity is suppressed following nuclear ARTD1 activation and binding by PAR. These findings help explain how prolonged activation of ARTD1 triggers energy collapse and cell death, revealing new insight on the importance of nucleus to mitochondria communication via ARTD1 activation. PMID:25220464

Cadherin-11 Mediates Contact Inhibition of Locomotion during Xenopus Neural Crest Cell Migration

PubMed Central

Becker, Sarah F. S.; Mayor, Roberto; Kashef, Jubin

2013-01-01

Collective cell migration is an essential feature both in embryonic development and cancer progression. The molecular mechanisms of these coordinated directional cell movements still need to be elucidated. The migration of cranial neural crest (CNC) cells during embryogenesis is an excellent model for collective cell migration in vivo. These highly motile and multipotent cells migrate directionally on defined routes throughout the embryo. Interestingly, local cell-cell interactions seem to be the key force for directionality. CNC cells can change their migration direction by a repulsive cell response called contact inhibition of locomotion (CIL). Cell protrusions collapse upon homotypic cell-cell contact and internal repolarization leads to formation of new protrusions toward cell-free regions. Wnt/PCP signaling was shown to mediate activation of small RhoGTPase RhoA and inhibition of cell protrusions at the contact side. However, the mechanism how a cell recognizes the contact is poorly understood. Here, we demonstrate that Xenopus cadherin-11 (Xcad-11) mediated cell-cell adhesion is necessary in CIL for directional and collective migration of CNC cells. Reduction of Xcad-11 adhesive function resulted in higher invasiveness of CNC due to loss of CIL. Additionally, transplantation analyses revealed that CNC migratory behaviour in vivo is non-directional and incomplete when Xcad-11 adhesive function is impaired. Blocking Wnt/PCP signaling led to similar results underlining the importance of Xcad-11 in the mechanism of CIL and directional migration of CNC. PMID:24392028

SERCA directs cell migration and branching across species and germ layers

PubMed Central

Lansdale, Nick; Navarro, Sonia; Truong, Thai V.; Bower, Dan J.; Featherstone, Neil C.; Connell, Marilyn G.; Al Alam, Denise; Frey, Mark R.; Trinh, Le A.; Fernandez, G. Esteban; Warburton, David; Fraser, Scott E.; Bennett, Daimark; Jesudason, Edwin C.

2017-01-01

ABSTRACT Branching morphogenesis underlies organogenesis in vertebrates and invertebrates, yet is incompletely understood. Here, we show that the sarco-endoplasmic reticulum Ca2+ reuptake pump (SERCA) directs budding across germ layers and species. Clonal knockdown demonstrated a cell-autonomous role for SERCA in Drosophila air sac budding. Live imaging of Drosophila tracheogenesis revealed elevated Ca2+ levels in migratory tip cells as they form branches. SERCA blockade abolished this Ca2+ differential, aborting both cell migration and new branching. Activating protein kinase C (PKC) rescued Ca2+ in tip cells and restored cell migration and branching. Likewise, inhibiting SERCA abolished mammalian epithelial budding, PKC activation rescued budding, while morphogens did not. Mesoderm (zebrafish angiogenesis) and ectoderm (Drosophila nervous system) behaved similarly, suggesting a conserved requirement for cell-autonomous Ca2+ signaling, established by SERCA, in iterative budding. PMID:28821490

HCK is a survival determinant transactivated by mutated MYD88, and a direct target of ibrutinib.

PubMed

Yang, Guang; Buhrlage, Sara J; Tan, Li; Liu, Xia; Chen, Jie; Xu, Lian; Tsakmaklis, Nicholas; Chen, Jiaji G; Patterson, Christopher J; Brown, Jennifer R; Castillo, Jorge J; Zhang, Wei; Zhang, Xiaofeng; Liu, Shuai; Cohen, Philip; Hunter, Zachary R; Gray, Nathanael; Treon, Steven P

2016-06-23

Activating mutations in MYD88 are present in ∼95% of patients with Waldenström macroglobulinemia (WM), as well as other B-cell malignancies including activated B-cell (ABC) diffuse large B-cell lymphoma (DLBCL). In WM, mutated MYD88 triggers activation of Bruton tyrosine kinase (BTK). Ibrutinib, a pleiotropic kinase inhibitor that targets BTK, is highly active in patients with mutated MYD88. We observed that mutated MYD88 WM and ABC DLBCL cell lines, as well as primary WM cells show enhanced hematopoietic cell kinase (HCK) transcription and activation, and that HCK is activated by interleukin 6 (IL-6). Over-expression of mutated MYD88 triggers HCK and IL-6 transcription, whereas knockdown of HCK reduced survival and attenuated BTK, phosphoinositide 3-kinase/AKT, and mitogen-activated protein kinase/extracellular signal-regulated kinase signaling in mutated MYD88 WM and/or ABC DLBCL cells. Ibrutinib and the more potent HCK inhibitor A419259, blocked HCK activation and induced apoptosis in mutated MYD88 WM and ABC DLBCL cells. Docking and pull-down studies confirmed that HCK was a target of ibrutinib. Ibrutinib and A419259 also blocked adenosine triphosphate binding to HCK, whereas transduction of mutated MYD88 expressing WM cells with a mutated HCK gatekeeper greatly increased the half maximal effective concentration for ibrutinib and A419259. The findings support that HCK expression and activation is triggered by mutated MYD88, supports the growth and survival of mutated MYD88 WM and ABC DLBCL cells, and is a direct target of ibrutinib. HCK represents a novel target for therapeutic development in MYD88-mutated WM and ABC DLBCL, and possibly other diseases driven by mutated MYD88. © 2016 by The American Society of Hematology.

The direction of stretch-induced cell and stress fiber orientation depends on collagen matrix stress.

PubMed

Tondon, Abhishek; Kaunas, Roland

2014-01-01

Cell structure depends on both matrix strain and stiffness, but their interactive effects are poorly understood. We investigated the interactive roles of matrix properties and stretching patterns on cell structure by uniaxially stretching U2OS cells expressing GFP-actin on silicone rubber sheets supporting either a surface-adsorbed coating or thick hydrogel of type-I collagen. Cells and their actin stress fibers oriented perpendicular to the direction of cyclic stretch on collagen-coated sheets, but oriented parallel to the stretch direction on collagen gels. There was significant alignment parallel to the direction of a steady increase in stretch for cells on collagen gels, while cells on collagen-coated sheets did not align in any direction. The extent of alignment was dependent on both strain rate and duration. Stretch-induced alignment on collagen gels was blocked by the myosin light-chain kinase inhibitor ML7, but not by the Rho-kinase inhibitor Y27632. We propose that active orientation of the actin cytoskeleton perpendicular and parallel to direction of stretch on stiff and soft substrates, respectively, are responses that tend to maintain intracellular tension at an optimal level. Further, our results indicate that cells can align along directions of matrix stress without collagen fibril alignment, indicating that matrix stress can directly regulate cell morphology.

Investigation of a direct effect of nanosecond pulse electric fields on mitochondria

NASA Astrophysics Data System (ADS)

Estlack, Larry E.; Roth, Caleb C.; Cerna, Cesario Z.; Wilmink, Gerald J.; Ibey, Bennett L.

2014-03-01

The unique cellular response to nanosecond pulsed electric field (nsPEF) exposure, as compared to longer pulse exposure, has been theorized to be due to permeabilization of intracellular organelles including the mitochondria. In this investigation, we utilized a high-throughput oxygen and pH sensing system (Seahorse® XF24 extracellular flux analyzer) to assess the mitochondrial activity of Jurkat and U937 cells after nsPEF. The XF Analyzer uses a transient micro-chamber of only a few μL in specialized cell culture micro-plates to enable oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) to be monitored in real-time. We found that for nsPEF exposures of 10 pulses at 10-ns pulse width and at 50 kV/cm e-field, we were able to cause an increase in OCR in both U937 and Jurkat cells. We also found that high pulse numbers (>100) caused a significant decrease in OCR. Higher amplitude 150 kV/cm exposures had no effect on U937 cells and yet they had a deleterious effect on Jurkat cells, matching previously published 24 hour survival data. These results suggest that the exposures were modulating metabolic activity in cells possibly due to direct effects on the mitochondria themselves. To validate this hypothesis, we isolated mitochondria from U937 cells and exposed them similarly and found no significant change in metabolic activity for any pulse number. In a final experiment, we removed calcium from the buffer solution that the cells were exposed in and found that no significant enhancement in metabolic activity was observed. These results suggest that direct permeabilization of the mitochondria is unlikely a primary effect of nsPEF exposure and calcium-mediated intracellular pathway activation is likely responsible for observed pulse-induced mitochondrial effects.

Comparative Assessment of Clinically Utilized CD20-directed Antibodies in Chronic Lymphocytic Leukemia Cells Reveals Divergent NK cell, Monocyte and Macrophage Properties

PubMed Central

Rafiq, Sarwish; Butchar, Jonathon P.; Cheney, Carolyn; Mo, Xiaokui; Trotta, Rossana; Caligiuri, Michael; Jarjoura, David; Tridandapani, Susheela; Muthusamy, Natarajan; Byrd, John C.

2013-01-01

CD20 is a widely validated, B cell specific target for therapy in B cell malignancies. Rituximab is an anti-CD20 antibody that when combined with chemotherapy prolongs survival of CLL patients. Ofatumumab and GA101 (obinutuzumab) are CD20-directed antibodies now being developed as alternative agents to rituximab in CLL based upon different properties of enhanced direct cell death (DCD), NK cell-mediated antibody dependent cellular cytotoxicity (ADCC), or complement-dependent cytotoxicity (CDC). Despite wide spread study, ofatumumab and GA101 have not been directly compared to one another, nor studied for interaction with monocytes and macrophages that are critical to CD20-mediated antibody efficacy in murine models. In CLL cells, we show that DCD is greatest with GA101 and CDC with ofatumumab. GA101 promotes enhanced NK cell activation and ADCC at high antibody concentrations. Ofatumumab has superior antibody dependent cellular phagocytosis (ADCP) with monocyte derived macrophages (MDM). GA101 demonstrated reduced activation of monocytes with diminished pERK, TNF-α release, and FcγRIIa recruitment to lipid rafts. These data demonstrate GA101 and ofatumumab are superior to rituximab against CLL cells via different mechanisms of potential tumor elimination. These findings bear relevance to potential combination strategies with each of these anti-CD20 antibodies in the treatment of CLL. PMID:23418626

Apoptotic actions of p53 require transcriptional activation of PUMA and do not involve a direct mitochondrial/cytoplasmic site of action in postnatal cortical neurons.

PubMed

Uo, Takuma; Kinoshita, Yoshito; Morrison, Richard S

2007-11-07

Recent studies in non-neuronal cells have shown that the tumor suppressor p53 can promote cell death through a transcription-independent mechanism involving its direct action with a subset of Bcl-2 family member proteins in the cytosol and at the mitochondria. In cultured cortical neurons, however, we could not find evidence supporting a significant contribution of the cytosolic/mitochondrial p53 pathway, and available evidence instead corroborated the requirement for the transcriptional activity of p53. When directly targeted to the cytosol/mitochondria, wild-type p53 lost its apoptosis-inducing activity in neurons but not in non-neuronal cells. The N-terminal p53 fragment (transactivation and proline-rich domains), which induces apoptosis in non-neuronal cells via the cytosolic/mitochondrial pathway, displayed no apoptogenic activity in neurons. In neuronal apoptosis induced by camptothecin or an MDM2 (murine double minute 2) inhibitor, nutlin-3, endogenous p53 protein did not accumulate in the cytosol/mitochondria, and transcriptional inhibition after p53 induction effectively blocked cell death. In addition, overexpression of a dominant-negative form of p53 (R273H) completely suppressed induction of proapoptotic p53 target genes and cell death. PUMA (p53-upregulated modulator of apoptosis) was one such gene induced by camptothecin, and its overexpression was sufficient to induce Bax (Bcl-2-associated X protein)-dependent neuronal death, whereas Noxa was not apoptogenic. These results collectively demonstrate that, in contrast to non-neuronal cells, the apoptotic activity of p53 in postnatal cortical neurons does not rely on its direct action at the cytosol/mitochondria but is exclusively mediated through its transcription-dependent functions. The uniqueness of p53-mediated apoptotic signaling in postnatal cortical neurons was further illustrated by the dispensable function of the proline-rich domain of p53.

CD4/CD8/Dendritic cell complexes in the spleen: CD8+ T cells can directly bind CD4+ T cells and modulate their response

PubMed Central

Barinov, Aleksandr; Galgano, Alessia; Krenn, Gerald; Tanchot, Corinne; Vasseur, Florence

2017-01-01

CD4+ T cell help to CD8+ T cell responses requires that CD4+ and CD8+ T cells interact with the same antigen presenting dendritic cell (Ag+DC), but it remains controversial whether helper signals are delivered indirectly through a licensed DC and/or involve direct CD4+/CD8+ T cell contacts and/or the formation of ternary complexes. We here describe the first in vivo imaging of the intact spleen, aiming to evaluate the first interactions between antigen-specific CD4+, CD8+ T cells and Ag+DCs. We show that in contrast to CD4+ T cells which form transient contacts with Ag+DC, CD8+ T cells form immediate stable contacts and activate the Ag+DC, acquire fragments of the DC membranes by trogocytosis, leading to their acquisition of some of the DC properties. They express MHC class II, and become able to present the specific Marilyn peptide to naïve Marilyn CD4+ T cells, inducing their extensive division. In vivo, these CD8+ T cells form direct stable contacts with motile naïve CD4+ T cells, recruiting them to Ag+DC binding and to the formation of ternary complexes, where CD4+ and CD8+ T cells interact with the DC and with one another. The presence of CD8+ T cells during in vivo immune responses leads to the early activation and up-regulation of multiple functions by CD4+ T lymphocytes. Thus, while CD4+ T cell help is important to CD8+ T cell responses, CD8+ T cells can interact directly with naïve CD4+ T cells impacting their recruitment and differentiation. PMID:28686740

Treatment of malignant pleural mesothelioma by fibroblast activation protein-specific re-directed T cells

PubMed Central

2013-01-01

Introduction Malignant pleural mesothelioma (MPM) is an incurable malignant disease, which results from chronic exposition to asbestos in at least 70% of the cases. Fibroblast activation protein (FAP) is predominantly expressed on the surface of reactive tumor-associated fibroblasts as well as on particular cancer types. Because of its expression on the cell surface, FAP is an attractive target for adoptive T cell therapy. T cells can be re-directed by retroviral transfer of chimeric antigen receptors (CAR) against tumor-associated antigens (TAA) and therefore represent a therapeutic strategy of adoptive immunotherapy. Methods To evaluate FAP expression immunohistochemistry was performed in tumor tissue from MPM patients. CD8+ human T cells were retrovirally transduced with an anti-FAP-F19-∆CD28/CD3ζ-CAR. T cell function was evaluated in vitro by cytokine release and cytotoxicity assays. In vivo function was tested with an intraperitoneal xenograft tumor model in immunodeficient mice. Results FAP was found to be expressed in all subtypes of MPM. Additionally, FAP expression was evaluated in healthy adult tissue samples and was only detected in specific areas in the pancreas, the placenta and very weakly for cervix and uterus. Expression of the anti-FAP-F19-∆CD28/CD3ζ-CAR in CD8+ T cells resulted in antigen-specific IFNγ release. Additionally, FAP-specific re-directed T cells lysed FAP positive mesothelioma cells and inflammatory fibroblasts in an antigen-specific manner in vitro. Furthermore, FAP-specific re-directed T cells inhibited the growth of FAP positive human tumor cells in the peritoneal cavity of mice and significantly prolonged survival of mice. Conclusion FAP re-directed CD8+ T cells showed antigen-specific functionality in vitro and in vivo. Furthermore, FAP expression was verified in all MPM histotypes. Therefore, our data support performing a phase I clinical trial in which MPM patients are treated with adoptively transferred FAP-specific re-directed T cells. PMID:23937772

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pi, Min; Kapoor, Karan P.; Ye, Ruisong

The possibility that G protein-coupled receptor family C member A (GPRC6A) is the osteocalcin (Ocn)-sensing G protein-coupled receptor that directly regulates pancreatic β-cell functions is controversial. In the current study, we found that Ocn and an Ocn-derived C-terminal hexapeptide directly activate GPRC6A-dependent ERK signaling in vitro. Computational models probe the structural basis of Ocn binding to GPRC6A and predict that the C-terminal hexapeptide docks to the extracellular side of the transmembrane domain of GPRC6A. Consistent with the modeling, mutations in the computationally identified binding pocket of GPRC6A reduced Ocn and C-terminal hexapeptide activation of this receptor. In addition, selective deletionmore » of Gprc6a in β-cells (Gprc6aβ-cell-cko) by crossing Gprc6aflox/flox mice with Ins2-Cre mice resulted in reduced pancreatic weight, islet number, insulin protein content, and insulin message expression. Both islet size and β-cell proliferation were reduced in Gprc6aβ-cell-cko compared with control mice. Gprc6aβ-cell-cko exhibited abnormal glucose tolerance, but normal insulin sensitivity. Islets isolated from Gprc6aβ-cell-cko mice showed reduced insulin simulation index in response to Ocn. These data establish the structural basis for Ocn direct activation of GPRC6A and confirm a role for GPRC6A in regulating β-cell proliferation and insulin secretion.« less

Natural Killer Cells and Helicobacter pylori Infection: Bacterial Antigens and Interleukin-12 Act Synergistically To Induce Gamma Interferon Production

PubMed Central

Yun, Cheol H.; Lundgren, Anna; Azem, Josef; Sjöling, Åsa; Holmgren, Jan; Svennerholm, Ann-Mari; Lundin, B. Samuel

2005-01-01

Helicobacter pylori is known to induce a local immune response, which is characterized by activation of lymphocytes and the production of IFN-γ in the stomach mucosa. Since not only T cells, but also natural killer (NK) cells, are potent producers of gamma interferon (IFN-γ), we investigated whether NK cells play a role in the immune response to H. pylori infection. Our results showed that NK cells were present in both the gastric and duodenal mucosae but that H. pylori infection did not affect the infiltration of NK cells into the gastrointestinal area. Furthermore, we could show that NK cells could be activated directly by H. pylori antigens, as H. pylori bacteria, as well as lysate from H. pylori, induced the secretion of IFN-γ by NK cells. NK cells were also activated without direct contact when separated from the bacteria by an epithelial cell layer, indicating that the activation of NK cells by H. pylori can also occur in vivo, in the infected stomach mucosa. Moreover, the production of IFN-γ by NK cells was greatly enhanced when a small amount of interleukin-12 (IL-12) was added, and this synergistic effect was associated with increased expression of the IL-12 receptor β2. It was further evident that bacterial lysate alone was sufficient to induce the activation of cytotoxicity-related molecules. In conclusion, we demonstrated that NK cells are present in the gastroduodenal mucosa of humans and that NK cells produce high levels of IFN-γ when stimulated with a combination of H. pylori antigen and IL-12. We propose that NK cells play an active role in the local immune response to H. pylori infection. PMID:15731046

A purified, fermented, extract of Triticum aestivum has lymphomacidal activity mediated via natural killer cell activation

PubMed Central

Barisone, Gustavo A.; O’Donnell, Robert T.; Ma, Yunpeng; Abuhay, Mastewal W.; Lundeberg, Kathleen; Gowda, Sonia

2018-01-01

Non-Hodgkin lymphoma (NHL) affects over 400,000 people in the United States; its incidence increases with age. Treatment options are numerous and expanding, yet efficacy is often limited by toxicity, particularly in the elderly. Nearly 70% patients eventually die of the disease. Many patients explore less toxic alternative therapeutics proposed to boost anti-tumor immunity, despite a paucity of rigorous scientific data. Here we evaluate the lymphomacidal and immunomodulatory activities of a protein fraction isolated from fermented wheat germ. Fermented wheat germ extract was produced by fermenting wheat germ with Saccharomyces cerevisiae. A protein fraction was tested for lymphomacidal activity in vitro using NHL cell lines and in vivo using mouse xenografts. Mechanisms of action were explored in vitro by evaluating apoptosis and cell cycle and in vivo by immunophenotyping and measurement of NK cell activity. Potent lymphomacidal activity was observed in a panel of NHL cell lines and mice bearing NHL xenografts. This activity was not dependent on wheat germ agglutinin or benzoquinones. Fermented wheat germ proteins induced apoptosis in NHL cells, and augmented immune effector mechanisms, as measured by NK cell killing activity, degranulation and production of IFNγ. Fermented wheat germ extract can be easily produced and is efficacious in a human lymphoma xenograft model. The protein fraction is quantifiable and more potent, shows direct pro-apoptotic properties, and enhances immune-mediated tumor eradication. The results presented herein support the novel concept that proteins in fermented wheat germ have direct pro-apoptotic activity on lymphoma cells and augment host immune effector mechanisms. PMID:29304125

Direct observation of nanoparticle-cancer cell nucleus interactions.

PubMed

Dam, Duncan Hieu M; Lee, Jung Heon; Sisco, Patrick N; Co, Dick T; Zhang, Ming; Wasielewski, Michael R; Odom, Teri W

2012-04-24

We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultrafast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy.

Withaferin A inhibits the proliferation of gastric cancer cells by inducing G2/M cell cycle arrest and apoptosis.

PubMed

Kim, Green; Kim, Tae-Hyoun; Hwang, Eun-Ha; Chang, Kyu-Tae; Hong, Jung Joo; Park, Jong-Hwan

2017-07-01

Human gastric adenocarcinoma (AGS) is one of the most common types of malignant tumor and the third-leading cause of tumor-associated mortality worldwide. Withaferin A (WA), a steroidal lactone derived from Withania somnifera , exhibits antitumor activity in a variety of cancer models. However, to the best of our knowledge, the direct effect of WA on AGS cells has not previously been determined. The present study investigated the effects of WA on the proliferation and metastatic activity of AGS cells. WA exerted a dose-dependent cytotoxic effect on AGS cells. The effect was associated with cell cycle arrest at the G2/M phase and the expression of apoptotic proteins. Additionally, WA treatment resulted in a decrease in the migration and invasion ability of the AGS cells, as demonstrated using a wound healing assay and a Boyden chamber assay. These results indicate that WA directly inhibits the proliferation and metastatic activity of gastric cancer cells, and suggest that WA may be developed as a drug for the treatment of gastric cancer.

Withaferin A inhibits the proliferation of gastric cancer cells by inducing G2/M cell cycle arrest and apoptosis

PubMed Central

Kim, Green; Kim, Tae-Hyoun; Hwang, Eun-Ha; Chang, Kyu-Tae; Hong, Jung Joo; Park, Jong-Hwan

2017-01-01

Human gastric adenocarcinoma (AGS) is one of the most common types of malignant tumor and the third-leading cause of tumor-associated mortality worldwide. Withaferin A (WA), a steroidal lactone derived from Withania somnifera, exhibits antitumor activity in a variety of cancer models. However, to the best of our knowledge, the direct effect of WA on AGS cells has not previously been determined. The present study investigated the effects of WA on the proliferation and metastatic activity of AGS cells. WA exerted a dose-dependent cytotoxic effect on AGS cells. The effect was associated with cell cycle arrest at the G2/M phase and the expression of apoptotic proteins. Additionally, WA treatment resulted in a decrease in the migration and invasion ability of the AGS cells, as demonstrated using a wound healing assay and a Boyden chamber assay. These results indicate that WA directly inhibits the proliferation and metastatic activity of gastric cancer cells, and suggest that WA may be developed as a drug for the treatment of gastric cancer. PMID:28693185

TLR4 signaling shapes B cell dynamics via MyD88-dependent pathways and Rac GTPases.

PubMed

Barrio, Laura; Saez de Guinoa, Julia; Carrasco, Yolanda R

2013-10-01

B cells use a plethora of TLR to recognize pathogen-derived ligands. These innate signals have an important function in the B cell adaptive immune response and modify their trafficking and tissue location. The direct role of TLR signaling on B cell dynamics nonetheless remains almost entirely unknown. In this study, we used a state-of-the-art two-dimensional model combined with real-time microscopy to study the effect of TLR4 stimulation on mouse B cell motility in response to chemokines. We show that a minimum stimulation period is necessary for TLR4 modification of B cell behavior. TLR4 stimulation increased B cell polarization, migration, and directionality; these increases were dependent on the MyD88 signaling pathway and did not require ERK or p38 MAPK activity downstream of TLR4. In addition, TLR4 stimulation enhanced Rac GTPase activity and promoted sustained Rac activation in response to chemokines. These results increase our understanding of the regulation of B cell dynamics by innate signals and the underlying molecular mechanisms.

Staphylococcal enterotoxin A (SEA) stimulates STAT3 activation and IL-17 expression in cutaneous T-cell lymphoma.

PubMed

Willerslev-Olsen, Andreas; Krejsgaard, Thorbjørn; Lindahl, Lise M; Litvinov, Ivan V; Fredholm, Simon; Petersen, David L; Nastasi, Claudia; Gniadecki, Robert; Mongan, Nigel P; Sasseville, Denis; Wasik, Mariusz A; Bonefeld, Charlotte M; Geisler, Carsten; Woetmann, Anders; Iversen, Lars; Kilian, Mogens; Koralov, Sergei B; Odum, Niels

2016-03-10

Cutaneous T-cell lymphoma (CTCL) is characterized by proliferation of malignant T cells in a chronic inflammatory environment. With disease progression, bacteria colonize the compromised skin barrier and half of CTCL patients die of infection rather than from direct organ involvement by the malignancy. Clinical data indicate that bacteria play a direct role in disease progression, but little is known about the mechanisms involved. Here, we demonstrate that bacterial isolates containing staphylococcal enterotoxin A (SEA) from the affected skin of CTCL patients, as well as recombinant SEA, stimulate activation of signal transducer and activator of transcription 3 (STAT3) and upregulation of interleukin (IL)-17 in immortalized and primary patient-derived malignant and nonmalignant T cells. Importantly, SEA induces STAT3 activation and IL-17 expression in malignant T cells when cocultured with nonmalignant T cells, indicating an indirect mode of action. In accordance, malignant T cells expressing an SEA-nonresponsive T-cell receptor variable region β chain are nonresponsive to SEA in monoculture but display strong STAT3 activation and IL-17 expression in cocultures with SEA-responsive nonmalignant T cells. The response is induced via IL-2 receptor common γ chain cytokines and a Janus kinase 3 (JAK3)-dependent pathway in malignant T cells, and blocked by tofacitinib, a clinical-grade JAK3 inhibitor. In conclusion, we demonstrate that SEA induces cell cross talk-dependent activation of STAT3 and expression of IL-17 in malignant T cells, suggesting a mechanism whereby SEA-producing bacteria promote activation of an established oncogenic pathway previously implicated in carcinogenesis. © 2016 by The American Society of Hematology.

Giardia lamblia: identification of molecules that contribute to direct mast cell activation.

PubMed

Muñoz-Cruz, Samira; Gomez-García, Argelia; Matadamas-Martínez, Félix; Alvarado-Torres, Juan A; Meza-Cervantez, Patricia; Arriaga-Pizano, Lourdes; Yépez-Mulia, Lilián

2018-06-02

Mast cells play a central role in the early clearance of the intestinal parasite Giardia lamblia. In a previous study, we reported that G. lamblia live trophozoites or trophozoite-derived total soluble extract induced direct activation (IgE-independent) of mast cells and release of IL-6 and TNF-α. To identify the Giardia molecules and the mast cell receptors involved in this activation, trophozoite-derived total soluble proteins separated into three fractions (F1-F3) were evaluated for its ability to activate mast cells in vitro. F2 activated mast cells in a greater extent than F1 and F3. Furthermore, F2 induced the release of IL-6 and TNF-α by mast cells. TLR2 and TLR4 expression increased slightly after mast cell stimulation with either F2 or total soluble extract; however, these receptors were not involved in F2 or total soluble extract-induced proinflammatory cytokine production. Proteins present in F2 as unique and high-intensity bands identified by liquid chromatography coupled with tandem mass spectrometry, include molecules with important biological activities such as enolase and arginine deiminase (ADI). Recombinant ADI and enolase were tested for their ability to activate mast cells, but only ADI induced a significant release of IL-6 and TNF-α. ADI product, citrulline but not ammonium, also induced mast cell release of TNF-α. Interestingly, recombinant ADI still stimulated the secretion of TNF-α by mast cells in a arginine-free medium, although in a lower extend that in the presence of arginine, indicating that either ADI itself can stimulate mast cells or through its metabolic product, citrulline.

Controlled release of GAG-binding enhanced transduction (GET) peptides for sustained and highly efficient intracellular delivery.

PubMed

Abu-Awwad, Hosam Al-Deen M; Thiagarajan, Lalitha; Dixon, James E

2017-07-15

Controlled release systems for therapeutic molecules are vital to allow the sustained local delivery of their activities which direct cell behaviour and enable novel regenerative strategies. Direct programming of cells using exogenously delivered transcription factors can by-pass growth factor signalling but there is still a requirement to deliver such activity spatio-temporally. We previously developed a technology termed GAG-binding enhanced transduction (GET) to efficiently deliver a variety of cargoes intracellularly, using GAG-binding domains which promote cell targeting, and cell penetrating peptides (CPPs) which allow cell entry. Herein we demonstrate that GET system can be used in controlled release systems to mediate sustained intracellular transduction over one week. We assessed the stability and activity of GET peptides in poly(dl-lactic acid-co-glycolic acid) (PLGA) microparticles (MPs) prepared using a S/O/W double emulsion method. Efficient encapsulation (∼65%) and tailored protein release profiles could be achieved, however intracellular transduction was significantly inhibited post-release. To retain GET peptide activity we optimized a strategy of co-encapsulation of l-Histidine, which may form a complex with the PLGA degradation products under acidic conditions. Simulations of the polymer microclimate showed that hydrolytic acidic PLGA degradation products directly inhibited GET peptide transduction activity, and use of l-Histidine significantly enhanced released protein delivery. The ability to control the intracellular transduction of functional proteins into cells will facilitate new localized delivery methods and allow approaches to direct cellular behaviour for many regenerative medicine applications. The goal for regenerative medicine is to restore functional biological tissue by controlling and augmenting cellular behaviour. Either Transcription (TFs) or growth factors (GFs) can be presented to cells in spatio-temporal gradients for programming cell fate and gene expression. Here, we have created a sustained and controlled release system for GET (Glycosaminoglycan-enhanced transducing)-tagged proteins using S/O/W PLGA microparticle fabrication. We demonstrated that PLGA and its acidic degradants inhibit GET-mediated transduction, which can be overcome by using pH-activated l-Histidine. l-Histidine inhibits the electrostatic interaction of GET/PLGA and allows enhanced intracellular transduction. GET could provide a powerful tool to program cell behaviour either in gradients or with sustained delivery. We believe that our controlled release systems will allow application of GET for tissue regeneration directly by TF cellular programming. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Antiviral Regulation in Porcine Monocytic Cells at Different Activation States

PubMed Central

Rowland, Raymond R. R.

2014-01-01

ABSTRACT Monocytic cells, including macrophages and dendritic cells, exist in different activation states that are critical to the regulation of antimicrobial immunity. Many pandemic viruses are monocytotropic, including porcine reproductive and respiratory syndrome virus (PRRSV), which directly infects subsets of monocytic cells and interferes with antiviral responses. To study antiviral responses in PRRSV-infected monocytic cells, we characterized inflammatory cytokine responses and genome-wide profiled signature genes to investigate response pathways in uninfected and PRRSV-infected monocytic cells at different activation states. Our findings showed suppressed interferon (IFN) production in macrophages in non-antiviral states and an arrest of lipid metabolic pathways in macrophages at antiviral states. Importantly, porcine monocytic cells at different activation states were susceptible to PRRSV and responded differently to viral infection. Based on Gene Ontology (GO) analysis, two approaches were used to potentiate antiviral activity: (i) pharmaceutical modulation of cellular lipid metabolism and (ii) in situ PRRSV replication-competent expression of interferon alpha (IFN-α). Both approaches significantly suppressed exogenous viral infection in monocytic cells. In particular, the engineered IFN-expressing PRRSV strain eliminated exogenous virus infection and sustained cell viability at 4 days postinfection in macrophages. These findings suggest an intricate interaction of viral infection with the activation status of porcine monocytic cells. An understanding and integration of antiviral infection with activation status of monocytic cells may provide a means of potentiating antiviral immunity. IMPORTANCE Activation statuses of monocytic cells, including monocytes, macrophages (Mϕs), and dendritic cells (DCs), are critically important for antiviral immunity. Unfortunately, the activation status of porcine monocytic cells or how cell activation status functionally interacts with antiviral immunity remains largely unknown. This is a significant omission because many economically important porcine viruses are monocytotropic, including our focus, PRRSV, which alone causes nearly $800 million economic loss annually in the U.S. swine industries. PRRSV is ideal for deciphering how monocytic cell activation statuses interact with antiviral immunity, because it directly infects subsets of monocytic cells and subverts overall immune responses. In this study, we systematically investigate the activation status of porcine monocytic cells to determine the intricate interaction of viral infection with activation statuses and functionally regulate antiviral immunity within the framework of the activation paradigm. Our findings may provide a means of potentiating antiviral immunity and leading to novel vaccines for PRRS prevention. PMID:25056886

Nickel-cobalt bimetallic anode catalysts for direct urea fuel cell

PubMed Central

Xu, Wei; Zhang, Huimin; Li, Gang; Wu, Zucheng

2014-01-01

Nickel is an ideal non-noble metal anode catalyst for direct urea fuel cell (DUFC) due to its high activity. However, there exists a large overpotential toward urea electrooxidation. Herein, NiCo/C bimetallic nanoparticles were prepared with various Co contents (0, 10, 20, 30 and 40 wt%) to improve the activity. The best Co ratio was 10% in the aspect of cell performance, with a maximum power density of 1.57 mW cm−2 when 0.33 M urea was used as fuel, O2 as oxidant at 60°C. The effects of temperature and urea concentration on DUFC performance were investigated. Besides, direct urine fuel cell reaches a maximum power density of 0.19 mW cm−2 with an open circuit voltage of 0.38 V at 60°C. PMID:25168632

Non-coplanar polychlorinated biphenyls (PCBs) are direct agonists for the human pregnane-X receptor and constitutive androstane receptor, and activate target gene expression in a tissue-specific manner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Salman, Fadheela; Plant, Nick, E-mail: N.Plant@Surrey.ac.uk

The polychlorinated biphenyl group possesses high environmental persistence, leading to bioaccumulation and a number of adverse effects in mammals. Whilst coplanar PCBs elicit their toxic effects through agonism of the aryl hydrocarbon receptor; however, non-coplanar PCBs are not ligands for AhR, but may be ligands for members of the nuclear receptor family of proteins. To better understand the biological actions of non-coplanar PCBs, we have undertaken a systematic analysis of their ability to activate PXR and CAR-mediated effects. Cells were exposed to a range of non-coplanar PCBs (99, 138, 153, 180 and 194), or the coplanar PCB77: Direct activation ofmore » PXR and CAR was measured using a mammalian receptor activation assay in human liver cells, with rifampicin and CITCO used as positive controls ligands for PXR and CAR, respectively; activation of target gene expression was examined using reporter gene plasmids for CYP3A4 and MDR1 transfected into liver, intestine and lung cell lines. Several of the non-coplanar PCBs directly activated PXR and CAR, whilst the coplanar PCB77 did not. Non-coplanar PCBs were also able to activate PXR/CAR target gene expression in a substitution- and tissue-specific manner. Non-coplanar PCBs act as direct activators for the nuclear receptors PXR and CAR, and are able to elicit transcriptional activation of target genes in a substitution- and tissue-dependent manner. Chronic activation of PXR/CAR is linked to adverse effects and must be included in any risk assessment of PCBs. -- Highlights: ► Several Non-coplanar PCBs are able to directly activate both PXR and CAR in vitro. ► PCB153 is the most potent direct activator of PXR and CAR nuclear receptors. ► Non-coplanar PCB activation of CYP3A4/MDR1 reporter genes is structure-dependent. ► Non-coplanar PCB activate CYP3A4/MDR1 reporter genes in a tissue-dependent. ► PCB153 is the most potent activator of PXR/CAR target gene in all tissues.« less

The Role of Direct Current Electric Field-Guided Stem Cell Migration in Neural Regeneration.

PubMed

Yao, Li; Li, Yongchao

2016-06-01

Effective directional axonal growth and neural cell migration are crucial in the neural regeneration of the central nervous system (CNS). Endogenous currents have been detected in many developing nervous systems. Experiments have demonstrated that applied direct current (DC) electric fields (EFs) can guide axonal growth in vitro, and attempts have been made to enhance the regrowth of damaged spinal cord axons using DC EFs in in vivo experiments. Recent work has revealed that the migration of stem cells and stem cell-derived neural cells can be guided by DC EFs. These studies have raised the possibility that endogenous and applied DC EFs can be used to direct neural tissue regeneration. Although the mechanism of EF-directed axonal growth and cell migration has not been fully understood, studies have shown that the polarization of cell membrane proteins and the activation of intracellular signaling molecules are involved in the process. The application of EFs is a promising biotechnology for regeneration of the CNS.

Platelets as Cellular Effectors of Inflammation in Vascular Diseases

PubMed Central

Rondina, Matthew T.; Weyrich, Andrew S.; Zimmerman, Guy A.

2013-01-01

Platelets are chief effector cells in hemostasis. In addition, they are multifaceted inflammatory cells with functions that span the continuum from innate immune responses to adaptive immunity. Activated platelets have key “thromboinflammatory” activities in a variety of vascular disorders and vasculopathies. Recently-identified inflammatory and immune activities provide insights into the biology of these versatile blood cells that are directly relevant to human vascular diseases. PMID:23704217

Substance P induces cardioprotection in ischemia-reperfusion via activation of AKT

PubMed Central

Jubair, Shaiban; Li, Jianping; Dehlin, Heather M.; Manteufel, Edward J.; Goldspink, Paul H.; Levick, Scott P.

2015-01-01

Accumulating evidence indicates that substance P is cardioprotective following ischemia-reperfusion primarily due to its potent coronary vasodilator actions. However, an anti-apoptotic effect of substance P has been observed in tenocytes following ischemia, which involved activation of the AKT pathway. This suggests the possibility that substance P also provides cardioprotection via direct actions to activate AKT in myocardial cells. The purpose of this study was to test the hypothesis that substance P attenuates ischemia-related cell death via direct effects on myocardial cells by activating cell survival pathways. Seven-week-old male Sprague-Dawley rats, anesthetized with intraperitoneal pentobarbital sodium (100 mg/kg), were used. The ability of substance P to prevent cellular damage was assessed following ischemia-reperfusion in an isolated heart preparation and in short-term hypoxia without reperfusion using a left ventricular tissue slice culture preparation. In addition, the NK-1 receptor and AKT involvement was assessed using the NK-1 receptor antagonist L732138 and the AKT inhibitor LY294002. The results indicate that substance P reduced the ischemia-related release of lactate dehydrogenase in both preparations and the degree of apoptosis and necrosis in the hypoxic left ventricular slices, indicating its ability to attenuate cell damage; and induced AKT phosphorylation, with both the AKT inhibitor and NK-1 receptor antagonist preventing the increased phosphorylation of AKT and the ability of substance P to attenuate hypoxic cellular damage. It is concluded that substance P reduces ischemia/hypoxia-induced myocardial cell death by acting directly on cardiac cells to initiate cell survival pathways via the NK-1 receptor and AKT. PMID:26071541

Human T-lymphotropic virus type I tax regulates the expression of the human lymphotoxin gene.

PubMed

Tschachler, E; Böhnlein, E; Felzmann, S; Reitz, M S

1993-01-01

Human T-lymphotropic virus type-I (HTLV-I)-infected T-cell lines constitutively produce high levels of lymphotoxin (LT). To analyze the mechanisms that lead to the expression of LT in HTLV-I-infected cell lines, we studied regulatory regions of the human LT promoter involved in the activation of the human LT gene. As determined by deletional analysis, sequences between +137 and -116 (relative to the transcription initiation site) are sufficient to direct expression of a reporter gene in the HTLV-I-infected cell line MT-2. Site-directed mutation of a of the single kappa B-like motif present in the LT promoter region (positions -99 to -89) completely abrogated LT promoter activity in MT-2 cells, suggesting that this site plays a critical role in the activation of the human LT gene. Transfection of LT constructs into HTLV-I-uninfected and -unstimulated Jurkat and U937 cell lines showed little to no activity of the LT promoter. Cotransfection of the same constructs with a tax expression plasmid into Jurkat cells led to detectable promoter activity, which could be significantly increased by stimulation of the cells with phorbol myristate acetate (PMA). Similarly, cotransfection of the LT promoter constructs and the tax expression plasmid into U937 cells led to significant promoter activity upon stimulation with PMA. These data suggest that HTLV-I tax is involved in the upregulation of LT gene expression in HTLV-I-infected cells.

Molecular mechanisms of the antiproliferative activity of somatostatin receptors (SSTRs) in neuroendocrine tumors.

PubMed

Florio, Tullio

2008-01-01

The current treatment of neuroendocrine tumors include the use of somatostatin (SST) agonists. These compounds are able to control most of the symptoms caused by the hypersecretory activity of the tumor cells, and for this reason, they provide a significant improvement in the well-being of the patients. Although, several reports also showed a possible direct antiproliferative activity of SST agonists in different neuroendocrine tumors, the therapeutic potential of an in vivo antiproliferative activity mediated by SST receptors is still debated. In recent years, there has been great insights on understanding the molecular basis of the antitumoral activity of SST that appears to be exerted via both direct and indirect mechanisms. Direct mechanisms require the activation of SST receptors in tumor cells and the induction of cell cycle arrest or apoptosis, mainly through the regulation of phosphotyrosine phosphatase (PTP) and MAP kinase activities. The indirect mechanisms involve the inhibition of tumor angiogenesis and the inhibition of the secretion of factors which are required for tumor growth. Here, we will review the molecular mechanisms which are implicated in the antiproliferative activity of SST. Such an understanding is necessary for improving the antitumoral efficacy of SSTR agonists as well as for the development of novel therapeutic strategies.

Kinetic Modeling of ABCG2 Transporter Heterogeneity: A Quantitative, Single-Cell Analysis of the Side Population Assay

PubMed Central

Prasanphanich, Adam F.; White, Douglas E.; Gran, Margaret A.

2016-01-01

The side population (SP) assay, a technique used in cancer and stem cell research, assesses the activity of ABC transporters on Hoechst staining in the presence and absence of transporter inhibition, identifying SP and non-SP cell (NSP) subpopulations by differential staining intensity. The interpretation of the assay is complicated because the transporter-mediated mechanisms fail to account for cell-to-cell variability within a population or adequately control the direct role of transporter activity on staining intensity. We hypothesized that differences in dye kinetics at the single-cell level, such as ABCG2 transporter-mediated efflux and DNA binding, are responsible for the differential cell staining that demarcates SP/NSP identity. We report changes in A549 phenotype during time in culture and with TGFβ treatment that correlate with SP size. Clonal expansion of individually sorted cells re-established both SP and NSPs, indicating that SP membership is dynamic. To assess the validity of a purely kinetics-based interpretation of SP/NSP identity, we developed a computational approach that simulated cell staining within a heterogeneous cell population; this exercise allowed for the direct inference of the role of transporter activity and inhibition on cell staining. Our simulated SP assay yielded appropriate SP responses for kinetic scenarios in which high transporter activity existed in a portion of the cells and little differential staining occurred in the majority of the population. With our approach for single-cell analysis, we observed SP and NSP cells at both ends of a transporter activity continuum, demonstrating that features of transporter activity as well as DNA content are determinants of SP/NSP identity. PMID:27851764

In vitro studies with renal proximal tubule cells show direct cytotoxicity of Androctonus australis hector scorpion venom triggered by oxidative stress, caspase activation and apoptosis.

PubMed

Saidani, Chanez; Hammoudi-Triki, Djelila; Laraba-Djebari, Fatima; Taub, Mary

2016-09-15

Scorpion envenomation injures a number of organs, including the kidney. Mechanisms proposed to explain the renal tubule injury include direct effects of venom on tubule epithelial cells, as well as indirect effects of the autonomic nervous system, and inflammation. Here, we report direct effects of Androctonus australis hector (Aah) scorpion venom on the viability of Renal Proximal Tubule (RPT) cells in vitro, unlike distal tubule and collecting duct cells. Extensive NucGreen nuclear staining was observed in immortalized rabbit RPT cells following treatment with Aah venom, consistent with cytotoxicity. The involvement of oxidative stress is supported by the observations that 1) anti-oxidants mitigated the Aah venom-induced decrease in the number of viable RPT cells, and 2) Aah venom-treated RPT cells were intensively stained with the CellROX(®) Deep Red reagent, an indicator of Reactive Oxygen Species (ROS). Relevance to normal RPT cells is supported by the red fluorescence observed in Aah venom treated primary rabbit RPT cell cultures following their incubation with the Flica reagent (indicative of caspase activation and apoptosis), and the green fluorescence of Sytox Green (indicative of dead cells). Copyright © 2016 Elsevier Ltd. All rights reserved.

Formation of a PKCζ/β-catenin complex in endothelial cells promotes angiopoietin-1–induced collective directional migration and angiogenic sprouting

PubMed Central

Oubaha, Malika; Lin, Michelle I.; Margaron, Yoran; Filion, Dominic; Price, Emily N.; Zon, Leonard I.; Côté, Jean-François

2012-01-01

Angiogenic sprouting requires that cell-cell contacts be maintained during migration of endothelial cells. Angiopoietin-1 (Ang-1) and vascular endothelial growth factor act oppositely on endothelial cell junctions. We found that Ang-1 promotes collective and directional migration and, in contrast to VEGF, induces the formation of a complex formed of atypical protein kinase C (PKC)-ζ and β-catenin at cell-cell junctions and at the leading edge of migrating endothelial cells. This complex brings Par3, Par6, and adherens junction proteins at the front of migrating cells to locally activate Rac1 in response to Ang-1. The colocalization of PKCζ and β-catenin at leading edge along with PKCζ-dependent stabilization of cell-cell contacts promotes directed and collective endothelial cell migration. Consistent with these results, down-regulation of PKCζ in endothelial cells alters Ang-1–induced sprouting in vitro and knockdown in developing zebrafish results in intersegmental vessel defects caused by a perturbed directionality of tip cells and by loss of cell contacts between tip and stalk cells. These results reveal that PKCζ and β-catenin function in a complex at adherens junctions and at the leading edge of migrating endothelial cells to modulate collective and directional migration during angiogenesis. PMID:22936663

Control of B-cell responses by Toll-like receptors

NASA Astrophysics Data System (ADS)

Pasare, Chandrashekhar; Medzhitov, Ruslan

2005-11-01

Toll-like receptors (TLRs) detect microbial infection and have an essential role in the induction of immune responses. TLRs can directly induce innate host defence responses, but the mechanisms of TLR-mediated control of adaptive immunity are not fully understood. Although TLR-induced dendritic cell maturation is required for activation of T-helper (TH) cells, the role of TLRs in B-cell activation and antibody production in vivo is not yet known. Here we show that activation and differentiation of TH cells is not sufficient for the induction of T-dependent B-cell responses. We find that, in addition to CD4+ T-cell help, generation of T-dependent antigen-specific antibody responses requires activation of TLRs in B cells.

CpG oligodeoxynucleotide induces apoptosis and cell cycle arrest in A20 lymphoma cells via TLR9-mediated pathways.

PubMed

Qi, Xu-Feng; Zheng, Li; Kim, Cheol-Su; Lee, Kyu-Jae; Kim, Dong-Heui; Cai, Dong-Qing; Qin, Jun-Wen; Yu, Yan-Hong; Wu, Zheng; Kim, Soo-Ki

2013-07-01

Recent studies have suggested that the anti-cancer activity of CpG-oligodeoxynucleotides (CpG-ODNs) is owing to their immunomodulatory effects in tumor-bearing host. The purpose of this study is to investigate the directly cytotoxic activity of KSK-CpG, a novel CpG-ODN with an alternative CpG motif, against A20 and EL4 lymphoma cells in comparison with previously used murine CpG motif (1826-CpG). To evaluate the potential cytotoxic effects of KSK-CpG on lymphoma cells, cell viability assay, confocal microscopy, flow cytometry, DNA fragmentation, Western blotting, and reverse transcription-polymerase chain reaction (RT-PCR) analysis were used. We found that KSK-CpG induced direct cytotoxicity in A20 lymphoma cells, but not in EL4 lymphoma cells, at least in part via TLR9-mediated pathways. Apoptotic cell death was demonstrated to play an important role in CpG-ODNs-induced cytotoxicity. In addition, both mitochondrial membrane potential decrease and G1-phase arrest were involved in KSK-CpG-induced apoptosis in A20 cells. The activities of apoptotic molecules such as caspase-3, PARP, and Bax were increased, but the activation of p27 Kip1 and ERK were decreased in KSK-CpG-treated A20 cells. Furthermore, autocrine IFN-γ partially contributed to apoptotic cell death in KSK-CpG-treated A20 cells. Collectively, our findings suggest that KSK-CpG induces apoptotic cell death in A20 lymphoma cells at least in part by inducing G1-phase arrest and autocrine IFN-γ via increasing TLR9 expression, without the need for immune system of tumor-bearing host. This new understanding supports the development of TLR9-targeted therapy with CpG-ODN as a direct therapeutic agent for treating B lymphoma. Copyright © 2013 Elsevier Ltd. All rights reserved.

Engineering a biospecific communication pathway between cells and electrodes

NASA Astrophysics Data System (ADS)

Collier, Joel H.; Mrksich, Milan

2006-02-01

Methods for transducing the cellular activities of mammalian cells into measurable electronic signals are important in many biotechnical applications, including biosensors, cell arrays, and other cell-based devices. This manuscript describes an approach for functionally integrating cellular activities and electrical processes in an underlying substrate. The cells are engineered with a cell-surface chimeric receptor that presents the nonmammalian enzyme cutinase. Action of this cell-surface cutinase on enzyme substrate self-assembled monolayers switches a nonelectroactive hydroxyphenyl ester to an electroactive hydroquinone, providing an electrical activity that can be identified with cyclic voltammetry. In this way, cell-surface enzymatic activity is transduced into electronic signals. The development of strategies to directly interface the activities of cells with materials will be important to enabling a broad class of hybrid microsystems that combine living and nonliving components. biomaterial | extracellular matrix | signal transduction

Adult subependymal neural precursors, but not differentiated cells, undergo rapid cathodal migration in the presence of direct current electric fields.

PubMed

Babona-Pilipos, Robart; Droujinine, Ilia A; Popovic, Milos R; Morshead, Cindi M

2011-01-01

The existence of neural stem and progenitor cells (together termed neural precursor cells) in the adult mammalian brain has sparked great interest in utilizing these cells for regenerative medicine strategies. Endogenous neural precursors within the adult forebrain subependyma can be activated following injury, resulting in their proliferation and migration toward lesion sites where they differentiate into neural cells. The administration of growth factors and immunomodulatory agents following injury augments this activation and has been shown to result in behavioural functional recovery following stroke. With the goal of enhancing neural precursor migration to facilitate the repair process we report that externally applied direct current electric fields induce rapid and directed cathodal migration of pure populations of undifferentiated adult subependyma-derived neural precursors. Using time-lapse imaging microscopy in vitro we performed an extensive single-cell kinematic analysis demonstrating that this galvanotactic phenomenon is a feature of undifferentiated precursors, and not differentiated phenotypes. Moreover, we have shown that the migratory response of the neural precursors is a direct effect of the electric field and not due to chemotactic gradients. We also identified that epidermal growth factor receptor (EGFR) signaling plays a role in the galvanotactic response as blocking EGFR significantly attenuates the migratory behaviour. These findings suggest direct current electric fields may be implemented in endogenous repair paradigms to promote migration and tissue repair following neurotrauma.

Sensitive kinase assay linked with phosphoproteomics for identifying direct kinase substrates

PubMed Central

Xue, Liang; Wang, Wen-Horng; Iliuk, Anton; Hu, Lianghai; Galan, Jacob A.; Yu, Shuai; Hans, Michael; Geahlen, Robert L.; Tao, W. Andy

2012-01-01

Our understanding of the molecular control of many disease pathologies requires the identification of direct substrates targeted by specific protein kinases. Here we describe an integrated proteomic strategy, termed kinase assay linked with phosphoproteomics, which combines a sensitive kinase reaction with endogenous kinase-dependent phosphoproteomics to identify direct substrates of protein kinases. The unique in vitro kinase reaction is carried out in a highly efficient manner using a pool of peptides derived directly from cellular kinase substrates and then dephosphorylated as substrate candidates. The resulting newly phosphorylated peptides are then isolated and identified by mass spectrometry. A further comparison of these in vitro phosphorylated peptides with phosphopeptides derived from endogenous proteins isolated from cells in which the kinase is either active or inhibited reveals new candidate protein substrates. The kinase assay linked with phosphoproteomics strategy was applied to identify unique substrates of spleen tyrosine kinase (Syk), a protein-tyrosine kinase with duel properties of an oncogene and a tumor suppressor in distinctive cell types. We identified 64 and 23 direct substrates of Syk specific to B cells and breast cancer cells, respectively. Both known and unique substrates, including multiple centrosomal substrates for Syk, were identified, supporting a unique mechanism that Syk negatively affects cell division through its centrosomal kinase activity. PMID:22451900

Herpes simplex virus antigens directly activate NK cells via TLR2, thus facilitating their presentation to CD4 T lymphocytes.

PubMed

Kim, Min; Osborne, Naomi R; Zeng, Weiguang; Donaghy, Heather; McKinnon, Kay; Jackson, David C; Cunningham, Anthony L

2012-05-01

NK cells infiltrate human herpetic lesions, but their role has been underexplored. HSV can stimulate innate immune responses via surface TLR2, which is expressed on monocyte-derived dendritic cells (DCs) and NK cells. In this study, UV-inactivated HSV1/2 and immunodominant HSV2 glycoprotein D peptides conjugated to the TLR2 agonist dipalmitoyl-S-glyceryl cysteine stimulated CD4 T lymphocyte IFN-γ responses within PBMCs or in coculture with monocyte-derived DCs. NK cells contributed markedly to the PBMC responses. Furthermore, NK cells alone were activated directly by both Ags, also upregulating HLA-DR and HLA-DQ and then they activated autologous CD4 T lymphocytes. Using Transwells, Ag-stimulated NK cells and CD4 T lymphocytes were shown to interact through both cell-to-cell contact and cytokines, differing in relative importance in different donors. A distinct immunological synapse between Ag-stimulated NK cells and CD4 T lymphocytes was observed, indicating the significance of their cell-to-cell contact. A large proportion (57%) of NK cells was also in contact with CD4 T lymphocytes in the dermal infiltrate of human recurrent herpetic lesions. Thus, NK cells stimulated by TLR2-activating HSV Ags can present Ag alone or augment the role of DCs in vitro and perhaps in herpetic lesions or draining lymph nodes. In addition to DCs, NK cells should be considered as targets for adjuvants during HSV vaccine development.

Metformin repositioning as antitumoral agent: selective antiproliferative effects in human glioblastoma stem cells, via inhibition of CLIC1-mediated ion current

PubMed Central

Barbieri, Federica; Peretti, Marta; Pizzi, Erika; Pattarozzi, Alessandra; Carra, Elisa; Sirito, Rodolfo; Daga, Antonio; Curmi, Paul M.G.; Mazzanti, Michele; Florio, Tullio

2014-01-01

Epidemiological and preclinical studies propose that metformin, a first-line drug for type-2 diabetes, exerts direct antitumor activity. Although several clinical trials are ongoing, the molecular mechanisms of this effect are unknown. Here we show that chloride intracellular channel-1 (CLIC1) is a direct target of metformin in human glioblastoma cells. Metformin exposure induces antiproliferative effects in cancer stem cell-enriched cultures, isolated from three individual WHO grade IV human glioblastomas. These effects phenocopy metformin-mediated inhibition of a chloride current specifically dependent on CLIC1 functional activity. CLIC1 ion channel is preferentially active during the G1-S transition via transient membrane insertion. Metformin inhibition of CLIC1 activity induces G1 arrest of glioblastoma stem cells. This effect was time-dependent, and prolonged treatments caused antiproliferative effects also for low, clinically significant, metformin concentrations. Furthermore, substitution of Arg29 in the putative CLIC1 pore region impairs metformin modulation of channel activity. The lack of drugs affecting cancer stem cell viability is the main cause of therapy failure and tumor relapse. We identified CLIC1 not only as a modulator of cell cycle progression in human glioblastoma stem cells but also as the main target of metformin's antiproliferative activity, paving the way for novel and needed pharmacological approaches to glioblastoma treatment. PMID:25361004

Metformin repositioning as antitumoral agent: selective antiproliferative effects in human glioblastoma stem cells, via inhibition of CLIC1-mediated ion current.

PubMed

Gritti, Marta; Würth, Roberto; Angelini, Marina; Barbieri, Federica; Peretti, Marta; Pizzi, Erika; Pattarozzi, Alessandra; Carra, Elisa; Sirito, Rodolfo; Daga, Antonio; Curmi, Paul M G; Mazzanti, Michele; Florio, Tullio

2014-11-30

Epidemiological and preclinical studies propose that metformin, a first-line drug for type-2 diabetes, exerts direct antitumor activity. Although several clinical trials are ongoing, the molecular mechanisms of this effect are unknown. Here we show that chloride intracellular channel-1 (CLIC1) is a direct target of metformin in human glioblastoma cells. Metformin exposure induces antiproliferative effects in cancer stem cell-enriched cultures, isolated from three individual WHO grade IV human glioblastomas. These effects phenocopy metformin-mediated inhibition of a chloride current specifically dependent on CLIC1 functional activity. CLIC1 ion channel is preferentially active during the G1-S transition via transient membrane insertion. Metformin inhibition of CLIC1 activity induces G1 arrest of glioblastoma stem cells. This effect was time-dependent, and prolonged treatments caused antiproliferative effects also for low, clinically significant, metformin concentrations. Furthermore, substitution of Arg29 in the putative CLIC1 pore region impairs metformin modulation of channel activity. The lack of drugs affecting cancer stem cell viability is the main cause of therapy failure and tumor relapse. We identified CLIC1 not only as a modulator of cell cycle progression in human glioblastoma stem cells but also as the main target of metformin's antiproliferative activity, paving the way for novel and needed pharmacological approaches to glioblastoma treatment.

6-Shogaol inhibits breast and colon cancer cell proliferation through activation of peroxisomal proliferator activated receptor γ (PPARγ).

PubMed

Tan, Boon Shing; Kang, Owen; Mai, Chun Wai; Tiong, Kai Hung; Khoo, Alan Soo-Beng; Pichika, Mallikarjuna Rao; Bradshaw, Tracey D; Leong, Chee-Onn

2013-08-09

6-Shogaol has been shown to possess many antitumor properties including inhibition of cancer cell growth, inhibition of cancer metastasis, induction of apoptosis in cancer cells and induction of cancer cell differentiation. Despite its prominent antitumor effects, the direct molecular target of 6-shogaol has remained elusive. To identify the direct targets of 6-shogaol, a comprehensive antitumor profile of 6-shogaol (NSC752389) was tested in the NCI-60 cell line in an in vitro screen. The results show that 6-shogaol is COMPARE negative suggesting that it functions via a mechanism of action distinct from existing classes of therapeutic agents. Further analysis using microarray gene profiling and Connectivity Map analysis showed that MCF-7 cells treated with 6-shogaol display gene expression signatures characteristic of peroxisome proliferator activated receptor γ (PPARγ) agonists, suggesting that 6-shogaol may activate the PPARγ signaling pathway for its antitumor effects. Indeed, treatment of MCF-7 and HT29 cells with 6-shogaol induced PPARγ transcriptional activity, suppressed NFκB activity, and induced apoptosis in breast and colon cancer cells in a PPARγ-dependent manner. Furthermore, 6-shogaol is capable of binding to PPARγ with a binding affinity comparable to 15-delta prostaglandin J2, a natural ligand for PPARγ. Together, our findings suggest that the antitumor effects of 6-shogaol are mediated through activation of PPARγ and imply that activation of PPARγ might be beneficial for breast and colon cancer treatment. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Emerging feed-forward inhibition allows the robust formation of direction selectivity in the developing ferret visual cortex

PubMed Central

Escobar, Gina M.; Maffei, Arianna; Miller, Paul

2014-01-01

The computation of direction selectivity requires that a cell respond to joint spatial and temporal characteristics of the stimulus that cannot be separated into independent components. Direction selectivity in ferret visual cortex is not present at the time of eye opening but instead develops in the days and weeks following eye opening in a process that requires visual experience with moving stimuli. Classic Hebbian or spike timing-dependent modification of excitatory feed-forward synaptic inputs is unable to produce direction-selective cells from unselective or weakly directionally biased initial conditions because inputs eventually grow so strong that they can independently drive cortical neurons, violating the joint spatial-temporal activation requirement. Furthermore, without some form of synaptic competition, cells cannot develop direction selectivity in response to training with bidirectional stimulation, as cells in ferret visual cortex do. We show that imposing a maximum lateral geniculate nucleus (LGN)-to-cortex synaptic weight allows neurons to develop direction-selective responses that maintain the requirement for joint spatial and temporal activation. We demonstrate that a novel form of inhibitory plasticity, postsynaptic activity-dependent long-term potentiation of inhibition (POSD-LTPi), which operates in the developing cortex at the time of eye opening, can provide synaptic competition and enables robust development of direction-selective receptive fields with unidirectional or bidirectional stimulation. We propose a general model of the development of spatiotemporal receptive fields that consists of two phases: an experience-independent establishment of initial biases, followed by an experience-dependent amplification or modification of these biases via correlation-based plasticity of excitatory inputs that compete against gradually increasing feed-forward inhibition. PMID:24598528

The isothiocyanate class of bioactive nutrients covalently inhibit the MEKK1 protein kinase

PubMed Central

Cross, Janet V; Foss, Frank W; Rady, Joshua M; Macdonald, Timothy L; Templeton, Dennis J

2007-01-01

Background Dietary isothiocyanates (ITCs) are electrophilic compounds that have diverse biological activities including induction of apoptosis and effects on cell cycle. They protect against experimental carcinogenesis in animals, an activity believed to result from the transcriptional induction of "Phase 2" enzymes. The molecular mechanism of action of ITCs is unknown. Since ITCs are electrophiles capable of reacting with sulfhydryl groups on amino acids, we hypothesized that ITCs induce their biological effects through covalent modification of proteins, leading to changes in cell regulatory events. We previously demonstrated that stress-signaling kinase pathways are inhibited by other electrophilic compounds such as menadione. We therefore tested the effects of nutritional ITCs on MEKK1, an upstream regulator of the SAPK/JNK signal transduction pathway. Methods The activity of MEKK1 expressed in cells was monitored using in vitro kinase assays to measure changes in catalytic activity. The activity of endogenous MEKK1, immunopurified from ITC treated and untreated LnCAP cells was also measured by in vitro kinase assay. A novel labeling and affinity reagent for detection of protein modification by ITCs was synthesized and used in competition assays to monitor direct modification of MEKK1 by ITC. Finally, immunoblots with phospho-specific antibodies were used to measure the activity of MAPK protein kinases. Results ITCs inhibited the MEKK1 protein kinase in a manner dependent on a specific cysteine residue in the ATP binding pocket. Inhibition of MEKK1 catalytic activity was due to direct, covalent and irreversible modification of the MEKK1 protein itself. In addition, ITCs inhibited the catalytic activity of endogenous MEKK1. This correlated with inhibition of the downstream target of MEKK1 activity, i.e. the SAPK/JNK kinase. This inhibition was specific to SAPK, as parallel MAPK pathways were unaffected. Conclusion These results demonstrate that MEKK1 is directly modified and inhibited by ITCs, and that this correlates with inhibition of downstream activation of SAPK. These results support the conclusion that ITCs may carry out many of their actions by directly targeting important cell regulatory proteins. PMID:17894894

The cellular mastermind(?) – Mechanotransduction and the nucleus

PubMed Central

Kaminski, Ashley; Fedorchak, Gregory R.; Lammerding, Jan

2015-01-01

Cells respond to mechanical stimulation by activation of specific signaling pathways and genes that allow the cell to adapt to its dynamic physical environment. How cells sense the various mechanical inputs and translate them into biochemical signals remains an area of active investigation. Recent reports suggest that the cell nucleus may be directly implicated in this cellular mechanotransduction process. In this chapter, we discuss how forces applied to the cell surface and cytoplasm induce changes in nuclear structure and organization, which could directly affect gene expression, while also highlighting the complex interplay between nuclear structural proteins and transcriptional regulators that may further modulate mechanotransduction signaling. Taken together, these findings paint a picture of the nucleus as a central hub in cellular mechanotransduction—both structurally and biochemically—with important implications in physiology and disease. PMID:25081618

Direct Melanoma Cell Contact Induces Stromal Cell Autocrine Prostaglandin E2-EP4 Receptor Signaling That Drives Tumor Growth, Angiogenesis, and Metastasis.

PubMed

Inada, Masaki; Takita, Morichika; Yokoyama, Satoshi; Watanabe, Kenta; Tominari, Tsukasa; Matsumoto, Chiho; Hirata, Michiko; Maru, Yoshiro; Maruyama, Takayuki; Sugimoto, Yukihiko; Narumiya, Shuh; Uematsu, Satoshi; Akira, Shizuo; Murphy, Gillian; Nagase, Hideaki; Miyaura, Chisato

2015-12-11

The stromal cells associated with tumors such as melanoma are significant determinants of tumor growth and metastasis. Using membrane-bound prostaglandin E synthase 1 (mPges1(-/-)) mice, we show that prostaglandin E2 (PGE2) production by host tissues is critical for B16 melanoma growth, angiogenesis, and metastasis to both bone and soft tissues. Concomitant studies in vitro showed that PGE2 production by fibroblasts is regulated by direct interaction with B16 cells. Autocrine activity of PGE2 further regulates the production of angiogenic factors by fibroblasts, which are key to the vascularization of both primary and metastatic tumor growth. Similarly, cell-cell interactions between B16 cells and host osteoblasts modulate mPGES-1 activity and PGE2 production by the osteoblasts. PGE2, in turn, acts to stimulate receptor activator of NF-κB ligand expression, leading to osteoclast differentiation and bone erosion. Using eicosanoid receptor antagonists, we show that PGE2 acts on osteoblasts and fibroblasts in the tumor microenvironment through the EP4 receptor. Metastatic tumor growth and vascularization in soft tissues was abrogated by an EP4 receptor antagonist. EP4-null Ptger4(-/-) mice do not support B16 melanoma growth. In vitro, an EP4 receptor antagonist modulated PGE2 effects on fibroblast production of angiogenic factors. Our data show that B16 melanoma cells directly influence host stromal cells to generate PGE2 signals governing neoangiogenesis and metastatic growth in bone via osteoclast erosive activity as well as angiogenesis in soft tissue tumors. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Direct Melanoma Cell Contact Induces Stromal Cell Autocrine Prostaglandin E2-EP4 Receptor Signaling That Drives Tumor Growth, Angiogenesis, and Metastasis*

PubMed Central

Inada, Masaki; Takita, Morichika; Yokoyama, Satoshi; Watanabe, Kenta; Tominari, Tsukasa; Matsumoto, Chiho; Hirata, Michiko; Maru, Yoshiro; Maruyama, Takayuki; Sugimoto, Yukihiko; Narumiya, Shuh; Uematsu, Satoshi; Akira, Shizuo; Murphy, Gillian; Nagase, Hideaki; Miyaura, Chisato

2015-01-01

The stromal cells associated with tumors such as melanoma are significant determinants of tumor growth and metastasis. Using membrane-bound prostaglandin E synthase 1 (mPges1−/−) mice, we show that prostaglandin E2 (PGE2) production by host tissues is critical for B16 melanoma growth, angiogenesis, and metastasis to both bone and soft tissues. Concomitant studies in vitro showed that PGE2 production by fibroblasts is regulated by direct interaction with B16 cells. Autocrine activity of PGE2 further regulates the production of angiogenic factors by fibroblasts, which are key to the vascularization of both primary and metastatic tumor growth. Similarly, cell-cell interactions between B16 cells and host osteoblasts modulate mPGES-1 activity and PGE2 production by the osteoblasts. PGE2, in turn, acts to stimulate receptor activator of NF-κB ligand expression, leading to osteoclast differentiation and bone erosion. Using eicosanoid receptor antagonists, we show that PGE2 acts on osteoblasts and fibroblasts in the tumor microenvironment through the EP4 receptor. Metastatic tumor growth and vascularization in soft tissues was abrogated by an EP4 receptor antagonist. EP4-null Ptger4−/− mice do not support B16 melanoma growth. In vitro, an EP4 receptor antagonist modulated PGE2 effects on fibroblast production of angiogenic factors. Our data show that B16 melanoma cells directly influence host stromal cells to generate PGE2 signals governing neoangiogenesis and metastatic growth in bone via osteoclast erosive activity as well as angiogenesis in soft tissue tumors. PMID:26475855

Intact LKB1 activity is required for survival of dormant ovarian cancer spheroids.

PubMed

Peart, Teresa; Ramos Valdes, Yudith; Correa, Rohann J M; Fazio, Elena; Bertrand, Monique; McGee, Jacob; Préfontaine, Michel; Sugimoto, Akira; DiMattia, Gabriel E; Shepherd, Trevor G

2015-09-08

Metastatic epithelial ovarian cancer (EOC) cells can form multicellular spheroids while in suspension and disperse directly throughout the peritoneum to seed secondary lesions. There is growing evidence that EOC spheroids are key mediators of metastasis, and they use specific intracellular signalling pathways to control cancer cell growth and metabolism for increased survival. Our laboratory discovered that AKT signalling is reduced during spheroid formation leading to cellular quiescence and autophagy, and these may be defining features of tumour cell dormancy. To further define the phenotype of EOC spheroids, we have initiated studies of the Liver kinase B1 (LKB1)-5'-AMP-activated protein kinase (AMPK) pathway as a master controller of the metabolic stress response. We demonstrate that activity of AMPK and its upstream kinase LKB1 are increased in quiescent EOC spheroids as compared with proliferating adherent EOC cells. We also show elevated AMPK activity in spheroids isolated directly from patient ascites. Functional studies reveal that treatment with the AMP mimetic AICAR or allosteric AMPK activator A-769662 led to a cytostatic response in proliferative adherent ovarian cancer cells, but they fail to elicit an effect in spheroids. Targeted knockdown of STK11 by RNAi to reduce LKB1 expression led to reduced viability and increased sensitivity to carboplatin treatment in spheroids only, a phenomenon which was AMPK-independent. Thus, our results demonstrate a direct impact of altered LKB1-AMPK signalling function in EOC. In addition, this is the first evidence in cancer cells demonstrating a pro-survival function for LKB1, a kinase traditionally thought to act as a tumour suppressor.

Differential and directional estrogenic signaling pathways induced by enterolignans and their precursors

PubMed Central

Zhu, Yun; Kawaguchi, Kayoko; Kiyama, Ryoiti

2017-01-01

Mammalian lignans or enterolignans are metabolites of plant lignans, an important category of phytochemicals. Although they are known to be associated with estrogenic activity, cell signaling pathways leading to specific cell functions, and especially the differences among lignans, have not been explored. We examined the estrogenic activity of enterolignans and their precursor plant lignans and cell signaling pathways for some cell functions, cell cycle and chemokine secretion. We used DNA microarray-based gene expression profiling in human breast cancer MCF-7 cells to examine the similarities, as well as the differences, among enterolignans, enterolactone and enterodiol, and their precursors, matairesinol, pinoresinol and sesamin. The profiles showed moderate to high levels of correlation (R values: 0.44 to 0.81) with that of estrogen (17β-estradiol or E2). Significant correlations were observed among lignans (R values: 0.77 to 0.97), and the correlations were higher for cell functions related to enzymes, signaling, proliferation and transport. All the enterolignans/precursors examined showed activation of the Erk1/2 and PI3K/Akt pathways, indicating the involvement of rapid signaling through the non-genomic estrogen signaling pathway. However, when their effects on specific cell functions, cell cycle progression and chemokine (MCP-1) secretion were examined, positive effects were observed only for enterolactone, suggesting that signals are given in certain directions at a position closer to cell functions. We hypothesized that, while estrogen signaling is initiated by the enterolignans/precursors examined, their signals are differentially and directionally modulated later in the pathways, resulting in the differences at the cell function level. PMID:28152041

Detailed Multi‐dimensional Modeling of Direct Internal Reforming Solid Oxide Fuel Cells

PubMed Central

Tseronis, K.; Fragkopoulos, I.S.; Bonis, I.

2016-01-01

Abstract Fuel flexibility is a significant advantage of solid oxide fuel cells (SOFCs) and can be attributed to their high operating temperature. Here we consider a direct internal reforming solid oxide fuel cell setup in which a separate fuel reformer is not required. We construct a multidimensional, detailed model of a planar solid oxide fuel cell, where mass transport in the fuel channel is modeled using the Stefan‐Maxwell model, whereas the mass transport within the porous electrodes is simulated using the Dusty‐Gas model. The resulting highly nonlinear model is built into COMSOL Multiphysics, a commercial computational fluid dynamics software, and is validated against experimental data from the literature. A number of parametric studies is performed to obtain insights on the direct internal reforming solid oxide fuel cell system behavior and efficiency, to aid the design procedure. It is shown that internal reforming results in temperature drop close to the inlet and that the direct internal reforming solid oxide fuel cell performance can be enhanced by increasing the operating temperature. It is also observed that decreases in the inlet temperature result in smoother temperature profiles and in the formation of reduced thermal gradients. Furthermore, the direct internal reforming solid oxide fuel cell performance was found to be affected by the thickness of the electrochemically‐active anode catalyst layer, although not always substantially, due to the counter‐balancing behavior of the activation and ohmic overpotentials. PMID:27570502

High targeted migration of human mesenchymal stem cells grown in hypoxia is associated with enhanced activation of RhoA

PubMed Central

2013-01-01

Introduction A feature which makes stem cells promising candidates for cell therapy is their ability to migrate effectively into damaged or diseased tissues. Recent reports demonstrated the increased motility of human mesenchymal stem cells (hMSC) grown under hypoxic conditions compared to normoxic cells. However, the directional migration of hMSC cultured in hypoxia has not been investigated. In this study we examined the in vitro transmembrane migration of hMSC permanently cultured in hypoxia in response to various cytokines. We also studied the involvement of RhoA, a molecule believed to play an essential role in the migration of MSC via reorganization of the cytoskeleton. Methods We compared the directional migration of human hMSCs grown permanently under normal (21%, normoxic) and low O2 (5%, hypoxic) conditions until passage 4 using an in vitro transmembrane migration assay. A series of 17 cytokines was used to induce chemotaxis. We also compared the level of GTP-bound RhoA in the cell extracts of calpeptin-activated hypoxic and normoxic hMSC. Results We found that hMSC cultured in hypoxia demonstrate markedly higher targeted migration activity compared to normoxic cells, particularly towards wound healing cytokines, including those found in ischemic and myocardial infarction. We also demonstrated for the first time that hMSC are dramatically more sensitive to activation of RhoA. Conclusions The results of this study indicate that high directional migration of hMSCs permanently grown in hypoxia is associated with the enhanced activation of RhoA. The enhanced migratory capacity of hypoxic hMSC would further suggest their potential advantages for clinical applications. PMID:23295150

The reorientation of cell nucleus promotes the establishment of front-rear polarity in migrating fibroblasts.

PubMed

Maninová, Miloslava; Klímová, Zuzana; Parsons, J Thomas; Weber, Michael J; Iwanicki, Marcin P; Vomastek, Tomáš

2013-06-12

The establishment of cell polarity is an essential step in the process of cell migration. This process requires precise spatiotemporal coordination of signaling pathways that in most cells create the typical asymmetrical profile of a polarized cell with nucleus located at the cell rear and the microtubule organizing center (MTOC) positioned between the nucleus and the leading edge. During cell polarization, nucleus rearward positioning promotes correct microtubule organizing center localization and thus the establishment of front-rear polarity and directional migration. We found that cell polarization and directional migration require also the reorientation of the nucleus. Nuclear reorientation is manifested as temporally restricted nuclear rotation that aligns the nuclear axis with the axis of cell migration. We also found that nuclear reorientation requires physical connection between the nucleus and cytoskeleton mediated by the LINC (linker of nucleoskeleton and cytoskeleton) complex. Nuclear reorientation is controlled by coordinated activity of lysophosphatidic acid (LPA)-mediated activation of GTPase Rho and the activation of integrin, FAK (focal adhesion kinase), Src, and p190RhoGAP signaling pathway. Integrin signaling is spatially induced at the leading edge as FAK and p190RhoGAP are predominantly activated or localized at this location. We suggest that integrin activation within lamellipodia defines cell front, and subsequent FAK, Src, and p190RhoGAP signaling represents the polarity signal that induces reorientation of the nucleus and thus promotes the establishment of front-rear polarity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Suppressor of Cytokine Signaling 2 Negatively Regulates NK Cell Differentiation by Inhibiting JAK2 Activity

PubMed Central

Kim, Won Sam; Kim, Mi Jeong; Kim, Dong Oh; Byun, Jae-Eun; Huy, Hangsak; Song, Hae Young; Park, Young-Jun; Kim, Tae-Don; Yoon, Suk Ran; Choi, Eun-Ji; Jung, Haiyoung; Choi, Inpyo

2017-01-01

Suppressor of cytokine signaling (SOCS) proteins are negative regulators of cytokine responses. Although recent reports have shown regulatory roles for SOCS proteins in innate and adaptive immunity, their roles in natural killer (NK) cell development are largely unknown. Here, we show that SOCS2 is involved in NK cell development. SOCS2−/− mice showed a high frequency of NK cells in the bone marrow and spleen. Knockdown of SOCS2 was associated with enhanced differentiation of NK cells in vitro, and the transplantation of hematopoietic stem cells (HSCs) into congenic mice resulted in enhanced differentiation in SOCS2−/− HSCs. We found that SOCS2 could inhibit Janus kinase 2 (JAK2) activity and JAK2-STAT5 signaling pathways via direct interaction with JAK2. Furthermore, SOCS2−/− mice showed a reduction in lung metastases and an increase in survival following melanoma challenge. Overall, our findings suggest that SOCS2 negatively regulates the development of NK cells by inhibiting JAK2 activity via direct interaction. PMID:28383049

Direct evidence for tumor necrosis factor-induced mitochondrial reactive oxygen intermediates and their involvement in cytotoxicity.

PubMed Central

Goossens, V; Grooten, J; De Vos, K; Fiers, W

1995-01-01

Tumor necrosis factor (TNF) is selectively cytotoxic to some types of tumor cells in vitro and exerts antitumor activity in vivo. Reactive oxygen intermediates (ROIs) have been implicated in the direct cytotoxic activity of TNF. By using confocal microscopy, flow cytometry, and the ROI-specific probe dihydrorhodamine 123, we directly demonstrate that intracellular ROIs are formed after TNF stimulation. These ROIs are observed exclusively under conditions where cells are sensitive to the cytotoxic activity of TNF, suggesting a direct link between both phenomena. ROI scavengers, such as butylated hydroxyanisole, effectively blocked the formation of free radicals and arrested the cytotoxic response, confirming that the observed ROIs are cytocidal. The mitochondrial glutathione system scavenges the major part of the produced ROIs, an activity that could be blocked by diethyl maleate; under these conditions, TNF-induced ROIs detectable by dihydrorhodamine 123 oxidation were 5- to 20-fold higher. Images Fig. 1 Fig. 4 PMID:7667254

Direct hydrothermal growth of GDC nanorods for low temperature solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Hong, Soonwook; Lee, Dohaeng; Yang, Hwichul; Kim, Young-Beom

2018-06-01

We report a novel synthesis technique of gadolinia-doped ceria (GDC) nano-rod (NRs) via direct hydrothermal process to enhance performance of low temperature solid oxide fuel cell by increasing active reaction area and ionic conductivity at interface between cathode and electrolyte. The cerium nitrate hexahydrate, gadolinium nitrate hexahydrate and urea were used to synthesis GDC NRs for growth on diverse substrate. The directly grown GDC NRs on substrate had a width from 819 to 490 nm and height about 2200 nm with a varied urea concentration. Under the optimized urea concentration of 40 mMol, we confirmed that GDC NRs able to fully cover the substrate by enlarging active reaction area. To maximize ionic conductivity of GDC NRs, we synthesis varied GDC NRs with different ratio of gadolinium and cerium precursor. Electrochemical analysis revealed a significant enhanced performance of fuel cells applying synthesized GDC NRs with a ratio of 2:8 gadolinium and cerium precursor by reducing polarization resistance, which was chiefly attributed to the enlarged active reaction area and enhanced ionic conductivity of GDC NRs. This method of direct hydrothermal growth of GDC NRs enhancing fuel cell performance was considered to apply other types of catalyzing application using nano-structure such as gas sensing and electrolysis fields.

Biological activities of phthalocyanines--XVI. Tetrahydroxy- and tetraalkylhydroxy zinc phthalocyanines. Effect of alkyl chain length on in vitro and in vivo photodynamic activities.

PubMed Central

Boyle, R. W.; Leznoff, C. C.; van Lier, J. E.

1993-01-01

Zinc phthalocyanine substituted with four hydroxyl groups attached to the macrocycle, either directly or via spacer chains of three or six carbon atoms, were tested for their photodynamic ability to inactivate Chinese hamster lung fibroblasts (line V-79) in vitro, and to induce regression of EMT-6 tumours grown subcutaneously in Balb/c mice. Their potential to inflict direct cell killing during photodynamic therapy was investigated by examining vascular stasis immediately following photoirradiation using fluorescein as a marker, and also by an in vivo/in vitro EMT-6 cell survival assay. Both of the tetraalkylhydroxy substituted zinc phthalocyanines are effective photodynamic sensitisers in vivo with the tetrapropylhydroxy compound exhibiting about twice the activity of the tetrahexylhydroxy analogue. The differences in activities were accentuated in vitro, the tetrapropylhydroxy compound was two orders of magnitude more potent than the tetrahexylhydroxy analogue in photoinactivating V-79 cells. The tetrahydroxy compound lacking spacer chains failed to exhibit photodynamic activity in either system. Tumour response with the active compounds was preceded by vascular stasis immediate following irradiation which suggests, together with the absence of activity in the in vivo/in vitro assay, that tumour regression involves an indirect response to the photodynamic action rather than direct cell killing. These data demonstrate the importance of the spatial orientation of functional groups around the macrocycle of photosensitisers for their efficacy in the photodynamic therapy of cancer. PMID:8512803

SiO2 nanoparticle-induced impairment of mitochondrial energy metabolism in hepatocytes directly and through a Kupffer cell-mediated pathway in vitro

PubMed Central

Xue, Yang; Chen, Qingqing; Ding, Tingting; Sun, Jiao

2014-01-01

The liver has been shown to be a primary target organ for SiO2 nanoparticles in vivo, and may be highly susceptible to damage by these nanoparticles. However, until now, research focusing on the potential toxic effects of SiO2 nanoparticles on mitochondria-associated energy metabolism in hepatocytes has been lacking. In this work, SiO2 nanoparticles 20 nm in diameter were evaluated for their ability to induce dysfunction of mitochondrial energy metabolism. First, a buffalo rat liver (BRL) cell line was directly exposed to SiO2 nanoparticles, which induced cytotoxicity and mitochondrial damage accompanied by decreases in mitochondrial dehydrogenase activity, mitochondrial membrane potential, enzymatic expression in the Krebs cycle, and activity of the mitochondrial respiratory chain complexes I, III and IV. Second, the role of rat-derived Kupffer cells was evaluated. The supernatants from Kupffer cells treated with SiO2 nanoparticles were transferred to stimulate BRL cells. We observed that SiO2 nanoparticles had the ability to activate Kupffer cells, leading to release of tumor necrosis factor-α, nitric oxide, and reactive oxygen species from these cells and subsequently to inhibition of mitochondrial respiratory chain complex I activity in BRL cells. PMID:24959077

Spatial distribution of filament elasticity determines the migratory behaviors of a cell

PubMed Central

Harn, Hans I-Chen; Hsu, Chao-Kai; Wang, Yang-Kao; Huang, Yi-Wei; Chiu, Wen-Tai; Lin, Hsi-Hui; Cheng, Chao-Min; Tang, Ming-Jer

2016-01-01

ABSTRACT Any cellular response leading to morphological changes is highly tuned to balance the force generated from structural reorganization, provided by actin cytoskeleton. Actin filaments serve as the backbone of intracellular force, and transduce external mechanical signal via focal adhesion complex into the cell. During migration, cells not only undergo molecular changes but also rapid mechanical modulation. Here we focus on determining, the role of spatial distribution of mechanical changes of actin filaments in epithelial, mesenchymal, fibrotic and cancer cells with non-migration, directional migration, and non-directional migration behaviors using the atomic force microscopy. We found 1) non-migratory cells only generated one type of filament elasticity, 2) cells generating spatially distributed two types of filament elasticity showed directional migration, and 3) pathologic cells that autonomously generated two types of filament elasticity without spatial distribution were actively migrating non-directionally. The demonstration of spatial regulation of filament elasticity of different cell types at the nano-scale highlights the coupling of cytoskeletal function with physical characters at the sub-cellular level, and provides new research directions for migration related disease. PMID:26919488

Prohibitin, relocated to the front ends, can control the migration directionality of colorectal cancer cells

PubMed Central

Guo, Li-Li; Hu, Chun-Ting; Huang, Ying-Xin; Huang, Guan; Jing, Fang-Yan; Liu, Chao; Li, Zhuo-Yi; Zhou, Na; Yan, Qian-Wen; Lei, Yan; Zhu, Shi-Jie; Cheng, Zhi-Qiang; Cao, Guang-Wen; Deng, Yong-Jian; Ding, Yan-Qing

2017-01-01

Directional migration is a cost-effective movement allowing invasion and metastatic spread of cancer cells. Although migration related to cytoskeletal assembly and microenvironmental chemotaxis has been elucidated, little is known about interaction between extracellular and intracellular molecules for controlling the migrational directionality. A polarized expression of prohibitin (PHB) in the front ends of CRC cells favors metastasis and is correlated with poor prognosis for 545 CRC patients. A high level of vascular endothelial growth factor (VEGF) in the interstitial tissue of CRC patients is associated with metastasis. VEGF bound to its receptor, neuropilin-1, can stimulate the activation of cell division cycle 42, which recruits intra-mitochondrial PHB to the front end of a CRC cell. This intracellular relocation of PHB results in the polymerization and reorganization of filament actin extending to the front end of the cell. As a result, the migration directionality of CRC cells is targeted towards VEGF. Together, these findings identify PHB as a key modulator of directional migration of CRC cells and a target for metastasis. PMID:29100316

A heating-superfusion platform technology for the investigation of protein function in single cells.

PubMed

Xu, Shijun; Ainla, Alar; Jardemark, Kent; Jesorka, Aldo; Jeffries, Gavin D M

2015-01-06

Here, we report on a novel approach for the study of single-cell intracellular enzyme activity at various temperatures, utilizing a localized laser heating probe in combination with a freely positionable microfluidic perfusion device. Through directed exposure of individual cells to the pore-forming agent α-hemolysin, we have controlled the membrane permeability, enabling targeted delivery of the substrate. Mildly permeabilized cells were exposed to fluorogenic substrates to monitor the activity of intracellular enzymes, while adjusting the local temperature surrounding the target cells, using an infrared laser heating system. We generated quantitative estimates for the intracellular alkaline phosphatase activity at five different temperatures in different cell lines, constructing temperature-response curves of enzymatic activity at the single-cell level. Enzymatic activity was determined rapidly after cell permeation, generating five-point temperature-response curves within just 200 s.

NKT cells in leishmaniasis.

PubMed

Zamora-Chimal, Jaime; Hernández-Ruiz, Joselín; Becker, Ingeborg

2017-04-01

The role of NKT cells in the resistance or susceptibility towards Leishmania infections remains to be defined, since controversial data persist. The response of these cells seems to depend on many variables such as the infection site, the number of infecting parasites, the virulence of the strain and the Leishmania species. We here revise the activation pathways leading to NKT cell activation. NKT cells can be activated by the direct pathway, in which Leishmania glycolipids are presented by CD1d molecules on antigen presenting cells, such as dendritic cells (DC), leading to the secretion of diverse cytokines by NKT. NKT cells can also be activated by the indirect pathway, in which Leishmania glycolipids, such as LPG, stimulate TLR2 in DC, inducing their IL-12 production, which in turn activates NKT cells. The review further analyzes the role of NKT cells in disease development, both in humans as in mouse models. Finally we propose the activation of NKT cells for controlling Leishmania infections. Copyright © 2016 Elsevier GmbH. All rights reserved.

Metabolism pathways in chronic lymphocytic leukemia

PubMed Central

Rozovski, Uri; Hazan-Halevy, Inbal; Barzilay, Merav; Keating, Michael J.; Estrov, Zeev

2016-01-01

Alterations in CLL cell metabolism have been studied by several investigators. Unlike normal B lymphocytes or other leukemia cells, CLL cells, like adipocytes, store lipids and utilize free fatty acids (FFA) to produce chemical energy. None of the recently identified mutations in CLL directly affects metabolic pathways, suggesting that genetic alterations do not directly contribute to CLL cells’ metabolic reprogramming. Conversely, recent data suggest that activation of STAT3 or downregulation of microRNA-125 levels plays a crucial role in the utilization of FFA to meet CLL cells’ metabolic needs. STAT3, known to be constitutively activated in CLL, increases the levels of lipoprotein lipase that mediates lipoprotein uptake and shifts CLL cells’ metabolism towards utilization of FFA. Herein we review the evidence for altered lipid metabolism, increased mitochondrial activity, and formation of reactive oxygen species in CLL cells, and discuss possible therapeutic strategies to inhibit lipid metabolism pathways in patient with CLL. PMID:26643954

Intrinsic transcriptional heterogeneity in B cells controls early class switching to IgE

PubMed Central

Wu, Yee Ling; Teichmann, Sarah A.

2017-01-01

Noncoding transcripts originating upstream of the immunoglobulin constant region (I transcripts) are required to direct activation-induced deaminase to initiate class switching in B cells. Differential regulation of Iε and Iγ1 transcription in response to interleukin 4 (IL-4), hence class switching to IgE and IgG1, is not fully understood. In this study, we combine novel mouse reporters and single-cell RNA sequencing to reveal the heterogeneity in IL-4–induced I transcription. We identify an early population of cells expressing Iε but not Iγ1 and demonstrate that early Iε transcription leads to switching to IgE and occurs at lower activation levels than Iγ1. Our results reveal how probabilistic transcription with a lower activation threshold for Iε directs the early choice of IgE versus IgG1, a key physiological response against parasitic infestations and a mediator of allergy and asthma. PMID:27994069

Radiation-induced biologic bystander effect elicited in vitro by targeted radiopharmaceuticals labeled with alpha-, beta-, and auger electron-emitting radionuclides.

PubMed

Boyd, Marie; Ross, Susan C; Dorrens, Jennifer; Fullerton, Natasha E; Tan, Ker Wei; Zalutsky, Michael R; Mairs, Robert J

2006-06-01

Recent studies have shown that indirect effects of ionizing radiation may contribute significantly to the effectiveness of radiotherapy by sterilizing malignant cells that are not directly hit by the radiation. However, there have been few investigations of the importance of indirect effects in targeted radionuclide treatment. Our purpose was to compare the induction of bystander effects by external beam gamma-radiation with those resultant from exposure to 3 radiohaloanalogs of metaiodobenzylguanidine (MIBG): (131)I-MIBG (low-linear-energy-transfer [LET] beta-emitter), (123)I-MIBG (potentially high-LET Auger electron emitter), and meta-(211)At-astatobenzylguanidine ((211)At-MABG) (high-LET alpha-emitter). Two human tumor cell lines-UVW (glioma) and EJ138 (transitional cell carcinoma of bladder)-were transfected with the noradrenaline transporter (NAT) gene to enable active uptake of MIBG. Medium from cells that accumulated the radiopharmaceuticals or were treated with external beam radiation was transferred to cells that had not been exposed to radioactivity, and clonogenic survival was determined in donor and recipient cultures. Over the dose range 0-9 Gy of external beam radiation of donor cells, 2 Gy caused 30%-40% clonogenic cell kill in recipient cultures. This potency was maintained but not increased by higher dosage. In contrast, no corresponding saturation of bystander cell kill was observed after treatment with a range of activity concentrations of (131)I-MIBG, which resulted in up to 97% death of donor cells. Cellular uptake of (123)I-MIBG and (211)At-MABG induced increasing recipient cell kill up to levels that resulted in direct kill of 35%-70% of clonogens. Thereafter, the administration of higher activity concentrations of these high-LET emitters was inversely related to the kill of recipient cells. Over the range of activity concentrations examined, neither direct nor indirect kill was observed in cultures of cells not expressing the NAT and, thus, incapable of active uptake of MIBG. Potent toxins are generated specifically by cells that concentrate radiohalogenated MIBG. These may be LET dependent and distinct from those elicited by conventional radiotherapy.

Direct Observation of Nanoparticle-Cancer Cell Nucleus Interactions

PubMed Central

Dam, Duncan Hieu M.; Lee, Jung Heon; Sisco, Patrick N.; Co, Dick T.; Zhang, Ming; Wasielewski, Michael R.; Odom, Teri W.

2012-01-01

We report the direct visualization of interactions between drug-loaded nanoparticles and the cancer cell nucleus. Nanoconstructs composed of nucleolin-specific aptamers and gold nanostars were actively transported to the nucleus and induced major changes to the nuclear phenotype via nuclear envelope invaginations near the site of the construct. The number of local deformations could be increased by ultra-fast, light-triggered release of the aptamers from the surface of the gold nanostars. Cancer cells with more nuclear envelope folding showed increased caspase 3 and 7 activity (apoptosis) as well as decreased cell viability. This newly revealed correlation between drug-induced changes in nuclear phenotype and increased therapeutic efficacy could provide new insight for nuclear-targeted cancer therapy. PMID:22424173

Substrate stiffness regulates cadherin-dependent collective migration through myosin-II contractility

PubMed Central

Ng, Mei Rosa; Besser, Achim

2012-01-01

The mechanical microenvironment is known to influence single-cell migration; however, the extent to which mechanical cues affect collective migration of adherent cells is not well understood. We measured the effects of varying substrate compliance on individual cell migratory properties in an epithelial wound-healing assay. Increasing substrate stiffness increased collective cell migration speed, persistence, and directionality as well as the coordination of cell movements. Dynamic analysis revealed that wounding initiated a wave of motion coordination from the wound edge into the sheet. This was accompanied by a front-to-back gradient of myosin-II activation and establishment of cell polarity. The propagation was faster and farther reaching on stiff substrates, indicating that substrate stiffness affects the transmission of directional cues. Manipulation of myosin-II activity and cadherin–catenin complexes revealed that this transmission is mediated by coupling of contractile forces between neighboring cells. Thus, our findings suggest that the mechanical environment integrates in a feedback with cell contractility and cell–cell adhesion to regulate collective migration. PMID:23091067

The HTLV-I tax protein transcriptionally modulates OX40 antigen expression.

PubMed

Pankow, R; Dürkop, H; Latza, U; Krause, H; Kunzendorf, U; Pohl, T; Bulfone-Paus, S

2000-07-01

OX40 is a member of the TNF receptor family, expressed on activated T cells. It is the only costimulatory T cell molecule known to be specifically up-regulated in human T cell leukemia virus type-I (HTLV-I)-producing cells. In a T cell line, OX40 surface expression was shown to be induced by HTLV-I Tax alone. To understand molecular mechanisms of OX40 gene regulation and modulation by HTLV-I Tax, we have cloned the human OX40 gene and analyzed its 5'-flanking region. By reporter gene analysis with progressive 5' deletions from nucleotides -1259 to -64, we have defined a 157-bp DNA fragment as a minimal promoter for constitutive expression. In addition, we show that in the OX40+ cell line, Co, Tax is able to further increase OX40 surface expression. Up-regulation of OX40 promoter activity by Tax requires two upstream NF-kappaB sites, which are not active in the constitutive OX40 expression. Their deletion abrogates Tax responsiveness in reporter gene analysis. The site-directed mutagenesis of each NF-kappaB site demonstrates that cooperative NF-kappaB binding is a prerequisite for Tax-directed activity as neither site alone is sufficient for a full Tax responsiveness of the OX40 promoter. Upon Tax expression, both sites bind p65 and c-Rel. These data provide new insight into the direct regulation of OX40 by Tax and add to our understanding of the possible role of the OX40/OX40 ligand system in the proliferation of HTLV-I+ T cells.

Dual gene activation and knockout screen reveals directional dependencies in genetic networks. | Office of Cancer Genomics

Cancer.gov

Understanding the direction of information flow is essential for characterizing how genetic networks affect phenotypes. However, methods to find genetic interactions largely fail to reveal directional dependencies. We combine two orthogonal Cas9 proteins from Streptococcus pyogenes and Staphylococcus aureus to carry out a dual screen in which one gene is activated while a second gene is deleted in the same cell. We analyze the quantitative effects of activation and knockout to calculate genetic interaction and directionality scores for each gene pair.

Enhanced activity of Au-Fe/C anodic electrocatalyst for direct borohydride-hydrogen peroxide fuel cell

NASA Astrophysics Data System (ADS)

Yi, Lanhua; Wei, Wei; Zhao, Caixian; Tian, Li; Liu, Jing; Wang, Xianyou

2015-07-01

Carbon supported Au-Fe bimetallic nanocatalysts (Au-Fe/C) are facilely prepared via a modified NaBH4 reduction method in aqueous solution at room temperature, and used as the anode electrocatalyst of direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the Au-Fe/C electrocatalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), rotating disc electrode (RDE) voltammetry, chronoamperometry (CA), chronopotentiometry (CP), and fuel cell test. The results show that Au-Fe/C catalysts display higher catalytic activity for the direct electrooxidation of BH4- than carbon supported pure Au nanocatalyst (Au/C), especially Au50Fe50/C catalyst presents the highest catalytic activity among all as-prepared catalysts. Besides, the single DBHFC with Au50Fe50/C anode and Au/C cathode obtains the maximum power density as high as 34.9 mW cm-2 at 25 °C.

Intracellular fluid flow in rapidly moving cells

PubMed Central

Keren, Kinneret; Yam, Patricia T.; Kinkhabwala, Anika; Mogilner, Alex; Theriot, Julie A.

2010-01-01

Cytosolic fluid dynamics have been implicated in cell motility1–5 because of the hydrodynamic forces they induce and because of their influence on transport of components of the actin machinery to the leading edge. To investigate the existence and the direction of fluid flow in rapidly moving cells, we introduced inert quantum dots into the lamellipodia of fish epithelial keratocytes and analysed their distribution and motion. Our results indicate that fluid flow is directed from the cell body towards the leading edge in the cell frame of reference, at about 40% of cell speed. We propose that this forward-directed flow is driven by increased hydrostatic pressure generated at the rear of the cell by myosin contraction, and show that inhibition of myosin II activity by blebbistatin reverses the direction of fluid flow and leads to a decrease in keratocyte speed. We present a physical model for fluid pressure and flow in moving cells that quantitatively accounts for our experimental data. PMID:19767741

Towards depersonalized abacavir therapy: chemical modification eliminates HLA-B*57 : 01-restricted CD8+ T-cell activation.

PubMed

Naisbitt, Dean J; Yang, Emma L; Alhaidari, Mohammad; Berry, Neil G; Lawrenson, Alexandre S; Farrell, John; Martin, Philip; Strebel, Klaus; Owen, Andrew; Pye, Matthew; French, Neil S; Clarke, Stephen E; O'Neill, Paul M; Park, B Kevin

2015-11-28

Exposure to abacavir is associated with T-cell-mediated hypersensitivity reactions in individuals carrying human leukocyte antigen (HLA)-B57 : 01. To activate T cells, abacavir interacts directly with endogenous HLA-B57 : 01 and HLA-B57 : 01 expressed on the surface of antigen presenting cells. We have investigated whether chemical modification of abacavir can produce a molecule with antiviral activity that does not bind to HLA-B57 : 01 and activate T cells. An interdisciplinary laboratory study using samples from human donors expressing HLA-B57 : 01. Researchers were blinded to the analogue structures and modelling data. Sixteen 6-amino substituted abacavir analogues were synthesized. Computational docking studies were completed to predict capacity for analogue binding within HLA-B57 : 01. Abacavir-responsive CD8 clones were generated to study the association between HLA-B57 : 01 analogue binding and T-cell activation. Antiviral activity and the direct inhibitory effect of analogues on proliferation were assessed. Major histocompatibility complex class I-restricted CD8 clones proliferated and secreted IFNγ following abacavir binding to surface and endogenous HLA-B57 : 01. Several analogues retained antiviral activity and showed no overt inhibitory effect on proliferation, but displayed highly divergent antigen-driven T-cell responses. For example, abacavir and N-propyl abacavir were equally potent at activating clones, whereas the closely related analogues N-isopropyl and N-methyl isopropyl abacavir were devoid of T-cell activity. Docking abacavir analogues to HLA-B57 : 01 revealed a quantitative relationship between drug-protein binding and the T-cell response. These studies demonstrate that the unwanted T-cell activity of abacavir can be eliminated whilst maintaining the favourable antiviral profile. The in-silico model provides a tool to aid the design of safer antiviral agents that may not require a personalized medicines approach to therapy.

Single-cell analysis of radiotracers' uptake by fluorescence microscopy: direct and droplet approach

NASA Astrophysics Data System (ADS)

Gallina, M. E.; Kim, T. J.; Vasquez, J.; Tuerkcan, S.; Abbyad, P.; Pratx, G.

2017-02-01

Radionuclides are used for sensitive and specific detection of small molecules in vivo and in vitro. Recently, radioluminescence microscopy extended their use to single-cell studies. Here we propose a new single-cell radioisotopic assay that improves throughput while adding sorting capabilities. The new method uses fluorescence-based sensor for revealing single-cell interactions with radioactive molecular markers. This study focuses on comparing two different experimental approaches. Several probes were tested and Dihydrorhodamine 123 was selected as the best compromise between sensitivity, brightness and stability. The sensor was incorporated either directly within the cell cytoplasm (direct approach), or it was coencapsulated with radiolabeled single-cells in oil-dispersed water droplets (droplet approach). Both approaches successfully activated the fluorescence signal following cellular uptake of 18F-fluorodeoxyglucose (FDG) and external Xrays exposure. The direct approach offered single-cell resolution and longtime stability ( > 20 hours), moreover it could discriminate FDG uptake at labelling concentration as low as 300 μCi/ml. In cells incubated with Dihydrorhodamine 123 after exposure to high radiation doses (8-16 Gy), the fluorescence signal was found to increase with the depletion of ROS quenchers. On the other side, the droplet approach required higher labelling concentrations (1.00 mCi/ml), and, at the current state of art, three cells per droplet are necessary to produce a fluorescent signal. This approach, however, is independent on cellular oxidative stress and, with further improvements, will be more suitable for studying heterogeneous populations. We anticipate this technology to pave the way for the analysis of single-cell interactions with radiomarkers by radiofluorogenic-activated single-cell sorting.

Microgravity and Cellular Consequences in Lymphocyte Function

NASA Technical Reports Server (NTRS)

Pellis, Neal R.; Sundaresan, Alamelu

2004-01-01

Mammalian cells adapt to the environment of low gravity and express a series of responses, some possibly from direct effects on cells and others based on environmental conditions created by microgravity. Human lymphocytes in microgravity culture are functionally diminished in activation and locomotion. Both processes are integral to optimal immune response to fight pathogens. The NASA Rotating-wall vessel (RWV) is a well-accepted analog for microgravity culture on the ground. Gene array experiments and immunoblotting identified upstream events in human lymphocytes adapting to microgravity analog culture. Microgravity induces selective changes, many of which are cell membrane related. Results showed that upstream of PKC in the T cell activation cascade, PLC-gamma and LAT are significantly diminished. ZAP 70 which controls LAT activation is also down regulated in modeled microgravity. Thus events governing cell shape might warrant attention in microgravity conditions. The goal of this study is to delineate response suites that are consequential, direct or indirect effects of the microgravity environment and which of these are essential to lymphocytes

Shock wave trauma leads to inflammatory response and morphological activation in macrophage cell lines, but does not induce iNOS or NO synthesis.

PubMed

Günther, Mattias; Plantman, Stefan; Gahm, Caroline; Sondén, Anders; Risling, Mårten; Mathiesen, Tiit

2014-12-01

Experimental CNS trauma results in post-traumatic inflammation for which microglia and macrophages are vital. Experimental brain contusion entails iNOS synthesis and formation of free radicals, NO and peroxynitrite. Shock wave trauma can be used as a model of high-energy trauma in cell culture. It is known that shock wave trauma causes sub-lytic injury and inflammatory activation in endothelial cells. Mechanical disruption of red blood cells can induce iNOS synthesis in experimental systems. However, it is not known whether trauma can induce activation and iNOS synthesis in inflammatory cell lines with microglial or macrophage lineage. We studied the response and activation in two macrophage cell lines and the consequence for iNOS and NO formation after shock wave trauma. Two macrophage cell lines from rat (NR8383) and mouse (RAW264.7) were exposed to shock wave trauma by the Flyer Plate method. The cellular response was investigated by Affymetrix gene arrays. Cell survival and morphological activation was monitored for 24 h in a Cell-IQ live cell imaging system. iNOS induction and NO synthesis were analyzed by Western blot, in cell Western IR-immunofluorescence, and Griess nitrite assay. Morphological signs of activation were detected in both macrophage cell lines. The activation of RAW264.7 was statistically significant (p < 0.05), but activation of NR8383 did not pass the threshold of statistical significance alpha (p > 0.05). The growth rate of idle cells was unaffected and growth arrest was not seen. Trauma did not result in iNOS synthesis or NO induction. Gene array analyses showed high enrichment for inflammatory response, G-protein coupled signaling, detection of stimulus and chemotaxis. Shock wave trauma combined with low LPS stimulation instead led to high enrichment in apoptosis, IL-8 signaling, mitosis and DNA-related activities. LPS/IFN-ɣ stimulation caused iNOS and NO induction and morphological activation in both cell lines. Shock wave trauma by the Flyer Plate method caused an inflammatory response and morphological signs of activation in two macrophage cell lines, while iNOS induction appeared to require humoral signaling by LPS/IFN-ɣ. Our findings indicated that direct energy transfer by trauma can activate macrophages directly without humoral mediators, which comprises a novel activation mechanism of macrophages.

RAC1 GTP-ase signals Wnt-beta-catenin pathway mediated integrin-directed metastasis-associated tumor cell phenotypes in triple negative breast cancers.

PubMed

De, Pradip; Carlson, Jennifer H; Jepperson, Tyler; Willis, Scooter; Leyland-Jones, Brian; Dey, Nandini

2017-01-10

The acquisition of integrin-directed metastasis-associated (ID-MA) phenotypes by Triple-Negative Breast Cancer (TNBC) cells is caused by an upregulation of the Wnt-beta-catenin pathway (WP). We reported that WP is one of the salient genetic features of TNBC. RAC-GTPases, small G-proteins which transduce signals from cell surface proteins including integrins, have been implicated in tumorigenesis and metastasis by their role in essential cellular functions like motility. The collective percentage of alteration(s) in RAC1 in ER+ve BC was lower as compared to ER-ve BC (35% vs 57%) (brca/tcga/pub2015). High expression of RAC1 was associated with poor outcome for RFS with HR=1.48 [CI: 1.15-1.9] p=0.0019 in the Hungarian ER-veBC cohort. Here we examined how WP signals are transduced via RAC1 in the context of ID-MA phenotypes in TNBC. Using pharmacological agents (sulindac sulfide), genetic tools (beta-catenin siRNA), WP modulators (Wnt-C59, XAV939), RAC1 inhibitors (NSC23766, W56) and WP stimulations (LWnt3ACM, Wnt3A recombinant) in a panel of 6-7 TNBC cell lines, we studied fibronectin-directed (1) migration, (2) matrigel invasion, (3) RAC1 and Cdc42 activation, (4) actin dynamics (confocal microscopy) and (5) podia-parameters. An attenuation of WP, which (a) decreased cellular levels of beta-catenin, as well as its nuclear active-form, (b) decreased fibronectin-induced migration, (c) decreased invasion, (d) altered actin dynamics and (e) decreased podia-parameters was successful in blocking fibronectin-mediated RAC1/Cdc42 activity. Both Wnt-antagonists and RAC1 inhibitors blocked fibronectin-induced RAC1 activation and inhibited the fibronectin-induced ID-MA phenotypes following specific WP stimulation by LWnt3ACM as well as Wnt3A recombinant protein. To test a direct involvement of RAC1-activation in WP-mediated ID-MA phenotypes, we stimulated brain-metastasis specific MDA-MB231BR cells with LWnt3ACM. LWnt3ACM-stimulated fibronectin-directed migration was blocked by RAC1 inhibition in MDA-MB231BR cells. In the light of our previous report that WP upregulation causes ID-MA phenotypes in TNBC tumor cells, here we provide the first mechanism based evidence to demonstrate that WP upregulation signals ID-MA tumor cell phenotypes in a RAC1-GTPase dependent manner involving exchange-factors like TIAM1 and VAV2. Our study demonstrates for the first time that beta-catenin-RAC1 cascade signals integrin-directed metastasis-associated tumor cell phenotypes in TNBC.

Identifying mechanisms for superdiffusive dynamics in cell trajectories

NASA Astrophysics Data System (ADS)

Passucci, Giuseppe; Brasch, Megan; Henderson, James; Manning, M. Lisa

Self-propelled particle (SPP) models have been used to explore features of active matter such as motility-induced phase separation, jamming, and flocking, and are often used to model biological cells. However, many cells exhibit super-diffusive trajectories, where displacements scale faster than t 1 / 2 in all directions, and these are not captured by traditional SPP models. We extract cell trajectories from image stacks of mouse fibroblast cells moving on 2D substrates and find super-diffusive mean-squared displacements in all directions across varying densities. Two SPP model modifications have been proposed to capture super-diffusive dynamics: Levy walks and heterogeneous motility parameters. In mouse fibroblast cells displacement probability distributions collapse when time is rescaled by a power greater than 1/2, which is consistent with Levy walks. We show that a simple SPP model with heterogeneous rotational noise can also generate a similar collapse. Furthermore, a close examination of statistics extracted directly from cell trajectories is consistent with a heterogeneous mobility SPP model and inconsistent with a Levy walk model. Our work demonstrates that a simple set of analyses can distinguish between mechanisms for anomalous diffusion in active matter.

Role of adapter function in oncoprotein-mediated activation of NF-kappaB. Human T-cell leukemia virus type I Tax interacts directly with IkappaB kinase gamma.

PubMed

Jin, D Y; Giordano, V; Kibler, K V; Nakano, H; Jeang, K T

1999-06-18

Mechanisms by which the human T-cell leukemia virus type I Tax oncoprotein activates NF-kappaB remain incompletely understood. Although others have described an interaction between Tax and a holo-IkappaB kinase (IKK) complex, the exact details of protein-protein contact are not fully defined. Here we show that Tax binds to neither IKK-alpha nor IKK-beta but instead complexes directly with IKK-gamma, a newly characterized component of the IKK complex. This direct interaction with IKK-gamma correlates with Tax-induced IkappaB-alpha phosphorylation and NF-kappaB activation. Thus, our findings establish IKK-gamma as a key molecule for adapting an oncoprotein-specific signaling to IKK-alpha and IKK-beta.

Thermophotovoltaic in-situ mirror cell

DOEpatents

Campbell, Brian C.

1997-01-01

A photovoltaic cell used in a direct energy conversion generator for converting heat to electricity includes a reflective layer disposed within the cell between the active layers of the cell and the cell substrate. The reflective layer reflects photons of low energy back to a photon producing emitter for reabsorption by the emitter, or reflects photons with energy greater than the cell bandgap back to the cell active layers for conversion into electricity. The reflective layer can comprise a reflective metal such as gold while the substrate can comprise heavily doped silicon or a metal.

Impairment of the Anterior Thalamic Head Direction Cell Network Following Administration of the NMDA antagonist MK-801

PubMed Central

Housh, Adam A.; Berkowitz, Laura E.; Ybarra, Isaac; Kim, Esther U.; Lee, Brian R.; Calton, Jeffrey L.

2014-01-01

Head direction (HD) cells, found in the rodent Papez circuit, are thought to form the neural circuitry responsible for directional orientation. Because NMDA transmission has been implicated in spatial tasks requiring directional orientation, we sought to determine if the NMDA antagonist dizocilpine (MK-801) would disrupt the directional signal carried by the HD network. Anterior thalamic HD cells were isolated in female Long-Evans rats and initially monitored for baseline directional activity while the animals foraged in a familiar enclosure. The animals were then administered MK-801 at a dose of .05 mg/kg or 0.1 mg/kg, or isotonic saline, and cells were re-examined for changes in directional specificity and landmark control. While the cells showed no changes in directional specificity and landmark control following administration of saline or the lower dose of MK-801, the higher dose of MK-801 caused a dramatic attenuation of the directional signal, characterized by decreases in peak firing rates, signal to noise, and directional information content. While the greatly attenuated directional specificity of cells in the high dose condition usually remained stable relative to the landmarks within the recording enclosure, a few cells in this condition exhibited unstable preferred directions within and between recording sessions. Our results are discussed relative to the possibility that the findings explain the effects of MK-801 on the acquisition and performance of spatial tasks. PMID:25307435

NKp44 receptor mediates interaction of the envelope glycoproteins from the West-Nile and dengue viruses with Natural Killer cells

PubMed Central

Hershkovitz, Oren; Rosental, Benyamin; Rosenberg, Lior Ann; Navarro-Sanchez, Martha Erika; Jivov, Sergey; Zilka, Alon; Gershoni-Yahalom, Orly; Brient-Litzler, Elodie; Bedouelle, Hugues; Ho, Joanna W.; Campbell, Kerry S.; Rager-Zisman, Bracha; Despres, Philippe; Porgador, Angel

2009-01-01

Dengue virus (DV) and West Nile virus (WNV) have become a global concern due to their widespread distribution and their ability to cause a variety of human diseases. Antiviral immune defenses involve natural killer (NK) cells. In the present study, we investigated the interaction between NK cells and these two flaviviruses. We show that the NK-activating receptor NKp44 is involved in virally-mediated NK activation through direct interaction with the flavivirus envelope protein. Recombinant NKp44 directly binds to purified DV and WNV envelope proteins and specifically to domain III of WNV envelope protein (EIII); it also binds to WNV virus-like particles (VLPs). These WNV-VLPs and WNV-EIII directly bind NK cells expressing high levels of NKp44. Functionally, interaction of NK cells with infective and inactivated WNV results in NKp44-mediated NK de-granulation. Finally, WNV infection of cells results in increased binding of recombinant NKp44 that is specifically inhibited by anti-WNV serum. WNV-infected target cells induce IFNγ secretion and augmented lysis by NKp44-expressing primary NK cells that are blocked by anti-NKp44 antibodies. Our findings show that triggering of NK cells by flavivirus is mediated by interaction of NKp44 with the flavivirus envelope protein. PMID:19635919

Arid3a is essential to execution of the first cell fate decision via direct embryonic and extraembryonic transcriptional regulation

PubMed Central

Rhee, Catherine; Lee, Bum-Kyu; Beck, Samuel; Anjum, Azeen; Cook, Kendra R.; Popowski, Melissa

2014-01-01

Despite their origin from the inner cell mass, embryonic stem (ES) cells undergo differentiation to the trophectoderm (TE) lineage by repression of the ES cell master regulator Oct4 or activation of the TE master regulator Caudal-type homeobox 2 (Cdx2). In contrast to the in-depth studies of ES cell self-renewal and pluripotency, few TE-specific regulators have been identified, thereby limiting our understanding of mechanisms underlying the first cell fate decision. Here we show that up-regulation and nuclear entry of AT-rich interactive domain 3a (Arid3a) drives TE-like transcriptional programs in ES cells, maintains trophoblast stem (TS) cell self-renewal, and promotes further trophoblastic differentiation both upstream and independent of Cdx2. Accordingly, Arid3a−/− mouse post-implantation placental development is severely impaired, resulting in early embryonic death. We provide evidence that Arid3a directly activates TE-specific and trophoblast lineage-specific genes while directly repressing pluripotency genes via differential regulation of epigenetic acetylation or deacetylation. Our results identify Arid3a as a critical regulator of TE and placental development through execution of the commitment and differentiation phases of the first cell fate decision. PMID:25319825

[Expression of human-mouse chimeric antibody directed against Chikungunya virus with site-specific integration system].

PubMed

Li, Jian-min; Chen, Wei; Jia, Xiu-jie; An, Xiao-ping; Li, Bing; Fan, Ying-ru; Tong, Yi-gang

2005-05-01

To obtain CHO/dhfr(-) cells line with integrated FRT sequence in the chromosome transcription active site and to express human-mouse chimeric antibody directed against Chikungunya Virus by using the cell line. The fusion gene of FRT and HBsAg was constructed by PCR and cloned into the MCS of pCI-neo to construct pCI-FRT-HBsAg. The pCI-FRT-HBsAg was transfected into CHO/dhfr(-) cells and cell clones with high expression of HBsAg were screened by detecting the amount of HBsAg with ELISA. A CHO cell clone with the highest expression was chosen and named as CHO/dhfr(-) FRT(+). pAFRT HFLF, a expression plasmid of chimeric antibody with RFT sequence was transfected into CHO/dhfr(-) FRT(+) cells and cell clones with high expression of the chimeric antibody were screened by increasing concentration of MTX. A CHO cell clone with high expression of the chimeric antibody was cultured in large scale and supernatant was collected from which the chimeric antibody was purified. The purified chimeric antibody was analyzed by SDS-PAGE, Western blot and IFA. A CHO/dhfr(-) cells line with integrated FRT sequence in the chromosome transcription active site was obtained successfully. A cell clone with yield of 5 mg/L of chimeric antibody was obtained, as compared with routine CHO cell expression system with a yield of 2 mg/L. A cell line with integrated FRT sequence in the chromosome transcription active site was obtained and with it human-mouse chimeric antibody directed against Chikungunya virus was expressed. This system lays a solid foundation which can be used for expressing antibodies and other proteins.

Substance P induces cardioprotection in ischemia-reperfusion via activation of AKT.

PubMed

Jubair, Shaiban; Li, Jianping; Dehlin, Heather M; Manteufel, Edward J; Goldspink, Paul H; Levick, Scott P; Janicki, Joseph S

2015-08-15

Accumulating evidence indicates that substance P is cardioprotective following ischemia-reperfusion primarily due to its potent coronary vasodilator actions. However, an anti-apoptotic effect of substance P has been observed in tenocytes following ischemia, which involved activation of the AKT pathway. This suggests the possibility that substance P also provides cardioprotection via direct actions to activate AKT in myocardial cells. The purpose of this study was to test the hypothesis that substance P attenuates ischemia-related cell death via direct effects on myocardial cells by activating cell survival pathways. Seven-week-old male Sprague-Dawley rats, anesthetized with intraperitoneal pentobarbital sodium (100 mg/kg), were used. The ability of substance P to prevent cellular damage was assessed following ischemia-reperfusion in an isolated heart preparation and in short-term hypoxia without reperfusion using a left ventricular tissue slice culture preparation. In addition, the NK-1 receptor and AKT involvement was assessed using the NK-1 receptor antagonist L732138 and the AKT inhibitor LY294002. The results indicate that substance P reduced the ischemia-related release of lactate dehydrogenase in both preparations and the degree of apoptosis and necrosis in the hypoxic left ventricular slices, indicating its ability to attenuate cell damage; and induced AKT phosphorylation, with both the AKT inhibitor and NK-1 receptor antagonist preventing the increased phosphorylation of AKT and the ability of substance P to attenuate hypoxic cellular damage. It is concluded that substance P reduces ischemia/hypoxia-induced myocardial cell death by acting directly on cardiac cells to initiate cell survival pathways via the NK-1 receptor and AKT. Copyright © 2015 the American Physiological Society.

Head Direction Cell Instability in the Anterior Dorsal Thalamus after Lesions of the Interpeduncular Nucleus

PubMed Central

Clark, Benjamin J.; Sarma, Asha; Taube, Jeffrey S.

2009-01-01

Previous research has identified a population of cells throughout the limbic system that discharge as a function of the animals head direction (HD). Altering normal motor cues can alter the HD cell responses and disrupt the updating of their preferred firing directions, thus suggesting that motor cues contribute to processing the HD signal. A pathway that conveys motor information may stem from the interpeduncular nucleus (IPN), a brain region that has reciprocal connections with HD cell circuitry. To test this hypothesis, we produced electrolytic or neurotoxic lesions of the IPN and recorded HD cells in the anterior dorsal thalamus (ADN) of rats. Direction-specific firing remained present in the ADN after lesions of the IPN, but measures of HD cell properties showed that cells had reduced peak firing rates, large directional firing ranges, and firing that predicted the animal’s future heading more than in intact controls. Furthermore, preferred firing directions were moderately less influenced by rotation of a salient visual landmark. Finally, the preferred directions of cells in lesioned rats exhibited large shifts when the animals foraged for scattered food-pellets in a darkened environment and when locomoting from a familiar environment to a novel one. We propose that the IPN contributes motor information about the animal’s movements to the HD cell circuitry. Further, these results suggest that the IPN plays a broad role in the discharge properties and stability of direction-specific activity in the HD cell circuit. PMID:19144850

Wnt-beta-catenin pathway signals metastasis-associated tumor cell phenotypes in triple negative breast cancers.

PubMed

De, Pradip; Carlson, Jennifer H; Wu, Hui; Marcus, Adam; Leyland-Jones, Brian; Dey, Nandini

2016-07-12

Tumor cells acquire metastasis-associated (MA) phenotypes following genetic alterations in them which cause deregulation of different signaling pathways. Earlier, we reported that an upregulation of the Wnt-beta-catenin pathway (WP) is one of the genetic salient features of triple-negative breast cancer (TNBC), and WP signaling is associated with metastasis in TNBC. Using cBioPortal, here we found that collective % of alteration(s) in WP genes, CTNNB1, APC and DVL1 among breast-invasive-carcinomas was 21% as compared to 56% in PAM50 Basal. To understand the functional relevance of WP in the biology of heterogeneous/metastasizing TNBC cells, we undertook this comprehensive study using 15 cell lines in which we examined the role of WP in the context of integrin-dependent MA-phenotypes. Directional movement of tumor cells was observed by confocal immunofluorescence microscopy and quantitative confocal-video-microscopy while matrigel-invasion was studied by MMP7-specific casein-zymography. WntC59, XAV939, sulindac sulfide and beta-catenin siRNA (1) inhibited fibronectin-directed migration, (2) decreased podia-parameters and motility-descriptors, (3) altered filamentous-actin, (4) decreased matrigel-invasion and (5) inhibited cell proliferation as well as 3D clonogenic growth. Sulindac sulfide and beta-catenin siRNA decreased beta-catenin/active-beta-catenin and MMP7. LWnt3ACM-stimulated proliferation, clonogenicity, fibronectin-directed migration and matrigel-invasion were perturbed by WP-modulators, sulindac sulfide and GDC-0941. We studied a direct involvement of WP in metastasis by stimulating brain-metastasis-specific MDA-MB231BR cells to demonstrate that LWnt3ACM-stimulated proliferation, clonogenicity and migration were blocked following sulindac sulfide, GDC-0941 and beta-catenin knockdown. We present the first evidence showing a direct functional relationship between WP activation and integrin-dependent MA-phenotypes. By proving the functional relationship between WP activation and MA-phenotypes, our data mechanistically explains (1) why different components of WP are upregulated in TNBC, (2) how WP activation is associated with metastasis and (3) how integrin-dependent MA-phenotypes can be regulated by mitigating the WP.

Wnt-beta-catenin pathway signals metastasis-associated tumor cell phenotypes in triple negative breast cancers

PubMed Central

De, Pradip; Carlson, Jennifer H.; Wu, Hui; Marcus, Adam; Leyland-Jones, Brian; Dey, Nandini

2016-01-01

Tumor cells acquire metastasis-associated (MA) phenotypes following genetic alterations in them which cause deregulation of different signaling pathways. Earlier, we reported that an upregulation of the Wnt-beta-catenin pathway (WP) is one of the genetic salient features of triple-negative breast cancer (TNBC), and WP signaling is associated with metastasis in TNBC. Using cBioPortal, here we found that collective % of alteration(s) in WP genes, CTNNB1, APC and DVL1 among breast-invasive-carcinomas was 21% as compared to 56% in PAM50 Basal. To understand the functional relevance of WP in the biology of heterogeneous/metastasizing TNBC cells, we undertook this comprehensive study using 15 cell lines in which we examined the role of WP in the context of integrin-dependent MA-phenotypes. Directional movement of tumor cells was observed by confocal immunofluorescence microscopy and quantitative confocal-video-microscopy while matrigel-invasion was studied by MMP7-specific casein-zymography. WntC59, XAV939, sulindac sulfide and beta-catenin siRNA (1) inhibited fibronectin-directed migration, (2) decreased podia-parameters and motility-descriptors, (3) altered filamentous-actin, (4) decreased matrigel-invasion and (5) inhibited cell proliferation as well as 3D clonogenic growth. Sulindac sulfide and beta-catenin siRNA decreased beta-catenin/active-beta-catenin and MMP7. LWnt3ACM-stimulated proliferation, clonogenicity, fibronection-directed migration and matrigel-invasion were perturbed by WP-modulators, sulindac sulfide and GDC-0941. We studied a direct involvement of WP in metastasis by stimulating brain-metastasis-specific MDA-MB231BR cells to demonstrate that LWnt3ACM-stimulated proliferation, clonogenicity and migration were blocked following sulindac sulfide, GDC-0941 and beta-catenin knockdown. We present the first evidence showing a direct functional relationship between WP activation and integrin-dependent MA-phenotypes. By proving the functional relationship between WP activation and MA-phenotypes, our data mechanistically explains (1) why different components of WP are upregulated in TNBC, (2) how WP activation is associated with metastasis and (3) how integrin-dependent MA-phenotypes can be regulated by mitigating the WP. PMID:27281609

Direct measurement of catalase activity in living cells and tissue biopsies.

PubMed

Scaglione, Christine N; Xu, Qijin; Ramanujan, V Krishnan

2016-01-29

Spatiotemporal regulation of enzyme-substrate interactions governs the decision-making steps in biological systems. Enzymes, being functional units of every living cell, contribute to the macromolecular stability of cell survival, proliferation and hence are vital windows to unraveling the biological complexity. Experimental measurements capturing this dynamics of enzyme-substrate interactions in real time add value to this understanding. Furthermore these measurements, upon validation in realistic biological specimens such as clinical biopsies - can further improve our capability in disease diagnostics and treatment monitoring. Towards this direction, we describe here a novel, high-sensitive measurement system for measuring diffusion-limited enzyme-substrate kinetics in real time. Using catalase (enzyme) and hydrogen peroxide (substrate) as the example pair, we demonstrate that this system is capable of direct measurement of catalase activity in vitro and the measured kinetics follows the classical Michaelis-Menten reaction kinetics. We further demonstrate the system performance by measuring catalase activity in living cells and in very small amounts of liver biopsies (down to 1 μg total protein). Catalase-specific enzyme activity is demonstrated by genetic and pharmacological tools. Finally we show the clinically-relevant diagnostic capability of our system by comparing the catalase activities in liver biopsies from young and old mouse (liver and serum) samples. We discuss the potential applicability of this system in clinical diagnostics as well as in intraoperative surgical settings. Copyright © 2016 Elsevier Inc. All rights reserved.

Direct Measurement of Catalase Activity in Living Cells and Tissue Biopsies

PubMed Central

Scaglione, Christine N; Xu, Qijin; Ramanujan, V. Krishnan

2016-01-01

Spatiotemporal regulation of enzyme-substrate interactions governs the decision-making steps in biological systems. Enzymes, being functional units of every living cell, contribute to the macromolecular stability of cell survival, proliferation and hence are vital windows to unraveling the biological complexity. Experimental measurements capturing this dynamics of enzyme-substrate interactions in real time add value to this understanding. Furthermore these measurements, upon validation in realistic biological specimens such as clinical biopsies – can further improve our capability in disease diagnostics and treatment monitoring. Towards this direction, we describe here a novel, high-sensitive measurement system for measuring diffusion-limited enzyme-substrate kinetics in real time. Using catalase (enzyme) and hydrogen peroxide (substrate) as the example pair, we demonstrate that this system is capable of direct measurement of catalase activity in vitro and the measured kinetics follows the classical Michaelis-Menten reaction kinetics. We further demonstrate the system performance by measuring catalase activity in living cells and in very small amounts of liver biopsies (down to 1μg total protein). Catalase-specific enzyme activity is demonstrated by genetic and pharamacological tools. Finally we show the clinically-relevant diagnostic capability of our system by comparing the catalase activities in liver biopsies from young and old mouse (liver and serum) samples. We discuss the potential applicability of this system in clinical diagnostics as well as in intraoperative surgical settings. PMID:26772884

Cytotoxic macrophage-released tumour necrosis factor-alpha (TNF-α) as a killing mechanism for cancer cell death after cold plasma activation

NASA Astrophysics Data System (ADS)

Kaushik, Nagendra Kumar; Kaushik, Neha; Min, Booki; Choi, Ki Hong; Hong, Young June; Miller, Vandana; Fridman, Alexander; Choi, Eun Ha

2016-03-01

The present study aims at studying the anticancer role of cold plasma-activated immune cells. The direct anti-cancer activity of plasma-activated immune cells against human solid cancers has not been described so far. Hence, we assessed the effect of plasma-treated RAW264.7 macrophages on cancer cell growth after co-culture. In particular, flow cytometer analysis revealed that plasma did not induce any cell death in RAW264.7 macrophages. Interestingly, immunofluorescence and western blot analysis confirmed that TNF-α released from plasma-activated macrophages acts as a tumour cell death inducer. In support of these findings, activated macrophages down-regulated the cell growth in solid cancer cell lines and induced cell death in vitro. Together our findings suggest plasma-induced reactive species recruit cytotoxic macrophages to release TNF-α, which blocks cancer cell growth and can have the potential to contribute to reducing tumour growth in vivo in the near future.

Activation of postsynaptic GABAB receptors modulates the bursting pattern and synaptic activity of olfactory bulb juxtaglomerular neurons.

PubMed

Karpuk, Nikolay; Hayar, Abdallah

2008-01-01

Olfactory bulb glomeruli are formed by a network of three major types of neurons collectively called juxtaglomerular (JG) cells, which include external tufted (ET), periglomerular (PG), and short axon (SA) cells. There is solid evidence that gamma-aminobutyric acid (GABA) released from PG neurons presynaptically inhibits glutamate release from olfactory nerve terminals via activation of GABA(B) receptors (GABA(B)-Rs). However, it is still unclear whether ET cells have GABA(B)-Rs. We have investigated whether ET cells have functional postsynaptic GABA(B)-Rs using extracellular and whole cell recordings in olfactory bulb slices. In the presence of fast synaptic blockers (CNQX, APV, and gabazine), the GABA(B)-R agonist baclofen either completely inhibited the bursting or reduced the bursting frequency and increased the burst duration and the number of spikes/burst in ET cells. In the presence of fast synaptic blockers and tetrodotoxin, baclofen induced an outward current in ET cells, suggesting a direct postsynaptic effect. Baclofen reduced the frequency and amplitude of spontaneous EPSCs in PG and SA cells. In the presence of sodium and potassium channel blockers, baclofen reduced the frequency of miniature EPSCs, which were inhibited by the calcium channel blocker cadmium. All baclofen effects were reversed by application of the GABA(B)-R antagonist CGP55845. We suggest that activation of GABA(B)-Rs directly inhibits ET cell bursting and decreases excitatory dendrodendritic transmission from ET to PG and SA cells. Thus the postsynaptic GABA(B)-Rs on ET cells may play an important role in shaping the activation pattern of the glomeruli during olfactory coding.

Seamless Combination of Fluorescence-Activated Cell Sorting and Hanging-Drop Networks for Individual Handling and Culturing of Stem Cells and Microtissue Spheroids.

PubMed

Birchler, Axel; Berger, Mischa; Jäggin, Verena; Lopes, Telma; Etzrodt, Martin; Misun, Patrick Mark; Pena-Francesch, Maria; Schroeder, Timm; Hierlemann, Andreas; Frey, Olivier

2016-01-19

Open microfluidic cell culturing devices offer new possibilities to simplify loading, culturing, and harvesting of individual cells or microtissues due to the fact that liquids and cells/microtissues are directly accessible. We present a complete workflow for microfluidic handling and culturing of individual cells and microtissue spheroids, which is based on the hanging-drop network concept: The open microfluidic devices are seamlessly combined with fluorescence-activated cell sorting (FACS), so that individual cells, including stem cells, can be directly sorted into specified culturing compartments in a fully automated way and at high accuracy. Moreover, already assembled microtissue spheroids can be loaded into the microfluidic structures by using a conventional pipet. Cell and microtissue culturing is then performed in hanging drops under controlled perfusion. On-chip drop size control measures were applied to stabilize the system. Cells and microtissue spheroids can be retrieved from the chip by using a parallelized transfer method. The presented methodology holds great promise for combinatorial screening of stem-cell and multicellular-spheroid cultures.

Poised Regeneration of Zebrafish Melanocytes Involves Direct Differentiation and Concurrent Replenishment of Tissue-Resident Progenitor Cells.

PubMed

Iyengar, Sharanya; Kasheta, Melissa; Ceol, Craig J

2015-06-22

Efficient regeneration following injury is critical for maintaining tissue function and enabling organismal survival. Cells reconstituting damaged tissue are often generated from resident stem or progenitor cells or from cells that have dedifferentiated and become proliferative. While lineage-tracing studies have defined cellular sources of regeneration in many tissues, the process by which these cells execute the regenerative process is largely obscure. Here, we have identified tissue-resident progenitor cells that mediate regeneration of zebrafish stripe melanocytes and defined how these cells reconstitute pigmentation. Nearly all regeneration melanocytes arise through direct differentiation of progenitor cells. Wnt signaling is activated prior to differentiation, and inhibition of Wnt signaling impairs regeneration. Additional progenitors divide symmetrically to sustain the pool of progenitor cells. Combining direct differentiation with symmetric progenitor divisions may serve as a means to rapidly repair injured tissue while preserving the capacity to regenerate. Copyright © 2015 Elsevier Inc. All rights reserved.

The STAT3 inhibitor pyrimethamine displays anti-cancer and immune stimulatory effects in murine models of breast cancer.

PubMed

Khan, Mohammad W; Saadalla, Abdulrahman; Ewida, Ahmed H; Al-Katranji, Khalid; Al-Saoudi, Ghadier; Giaccone, Zachary T; Gounari, Fotini; Zhang, Ming; Frank, David A; Khazaie, Khashayarsha

2018-01-01

The transcription factor signal activator and transducer or transcription (STAT3), which regulates genes controlling proliferation, survival, and invasion, is activated inappropriately in many human cancers, including breast cancer. Activation of STAT3 can lead to both malignant cellular behavior and suppression of immune cell function in the tumor microenvironment. Through a chemical-biology screen, pyrimethamine (PYR), an FDA approved anti-microbial drug, was identified as an inhibitor of STAT3 function at concentrations known to be achieved safely in humans. We report that PYR shows therapeutic activity in two independent mouse models of breast cancer, with both direct tumor inhibitory and immune stimulatory effects. PYR-inhibited STAT3 activity in TUBO and TM40D-MB metastatic breast cancer cells in vitro and inhibited tumor cell proliferation and invasion into Matrigel basement membrane matrix. In tumor-transplanted mice, PYR had both direct and indirect tumor inhibitory effects. Tumor-bearing mice treated with PYR showed reduced STAT3 activation in tumor cells, attenuated tumor growth, and reduced tumor-associated inflammation. In addition, expression of Lamp1 by tumor infiltrating CD8 + T cells was elevated, indicating enhanced release of cytotoxic granules. These findings suggest that PYR may have beneficial effects in the treatment of breast cancer.

Helicobacter pylori induces activation of human peripheral γδ+ T lymphocytes.

PubMed

Romi, Benedetta; Soldaini, Elisabetta; Pancotto, Laura; Castellino, Flora; Del Giudice, Giuseppe; Schiavetti, Francesca

2011-04-29

Helicobacter pylori is a gram-negative bacterium that causes gastric and duodenal diseases in humans. Despite a robust antibody and cellular immune response, H. pylori infection persists chronically. To understand if and how H. pylori could modulate T cell activation, in the present study we investigated in vitro the interaction between H. pylori and human T lymphocytes freshly isolated from peripheral blood of H. pylori-negative donors. A direct interaction of live, but not killed bacteria with purified CD3+ T lymphocytes was observed by microscopy and confirmed by flow cytometry. Live H. pylori activated CD3+ T lymphocytes and predominantly γδ+ T cells bearing the TCR chain Vδ2. Upon interaction with H. pylori, these cells up-regulated the activation molecule CD69 and produced cytokines (such as TNFα, IFNγ) and chemokines (such as MIP-1β, RANTES) in a non-antigen-specific manner. This activation required viable H. pylori and was not exhibited by other gram-negative bacteria. The cytotoxin-associated antigen-A (CagA), was at least partially responsible of this activation. Our results suggest that H. pylori can directly interact with T cells and modulate the response of γδ+ T cells, thereby favouring an inflammatory environment which can contribute to the chronic persistence of the bacteria and eventually to the gastric pathology.

Vinblastine 20' Amides: Synthetic Analogues That Maintain or Improve Potency and Simultaneously Overcome Pgp-Derived Efflux and Resistance.

PubMed

Lukesh, John C; Carney, Daniel W; Dong, Huijun; Cross, R Matthew; Shukla, Vyom; Duncan, Katharine K; Yang, Shouliang; Brody, Daniel M; Brütsch, Manuela M; Radakovic, Aleksandar; Boger, Dale L

2017-09-14

A series of 180 vinblastine 20' amides were prepared in three steps from commercially available starting materials, systematically exploring a typically inaccessible site in the molecule enlisting a powerful functionalization strategy. Clear structure-activity relationships and a structural model were developed in the studies which provided many such 20' amides that exhibit substantial and some even remarkable enhancements in potency, many that exhibit further improvements in activity against a Pgp overexpressing resistant cancer cell line, and an important subset of the vinblastine analogues that display little or no differential in activity against a matched pair of vinblastine sensitive and resistant (Pgp overexpressing) cell lines. The improvements in potency directly correlated with target tubulin binding affinity, and the reduction in differential functional activity against the sensitive and Pgp overexpressing resistant cell lines was found to correlate directly with an impact on Pgp-derived efflux.

Cytotoxic activity of interferon alpha induced dendritic cells as a biomarker of glioblastoma

NASA Astrophysics Data System (ADS)

Mishinov, S. V.; Stupak, V. V.; Tyrinova, T. V.; Leplina, O. Yu.; Ostanin, A. A.; Chernykh, E. R.

2016-08-01

Dendritic cells (DCs) are the most potent antigen presenting cells that can play direct role in anti-tumor immune response as killer cells. DC tumoricidal activity can be stimulated greatly by type I IFN (IFNα and IFNβ). In the present study, we examined cytostatic and cytotoxic activity of monocyte-derived IFNα-induced DCs generated from patients with brain glioma and evaluated the potential use of these parameters in diagnostics of high-grade gliomas. Herein, we demonstrated that patient DCs do not possess the ability to inhibit the growth of tumor HEp-2 cell line but low-grade and high-grade glioma patients do not differ significantly in DC cytostatic activity. However, glioma patient DCs are characterized by reduced cytotoxic activity against HEp-2 cells. The impairment of DC cytotoxic function is observed mainly in glioblastoma patients. The cytotoxic activity of DCs against HEp-2 cells below 9% is an informative marker for glioblastomas.

T Cell Stimulatory Effects of Korean Red Ginseng through Modulation of Myeloid-Derived Suppressor Cells.

PubMed

Jeon, Chanoh; Kang, Soowon; Park, Seungbeom; Lim, Kyungtaek; Hwang, Kwang Woo; Min, Hyeyoung

2011-11-01

Myeloid-derived suppressor cells (MDSCs) actively suppress immune cells and have been considered as an impediment to successful cancer immunotherapy. Many approaches have been made to overcome such immunosuppressive factors and to exert effective anti-tumor effects, but the possibility of using medicinal plants for this purpose has been overlooked. Korean red ginseng (KRG) is widely known to possess a variety of pharmacological properties, including immunoboosting and anti-tumor activities. However, little has been done to assess the anti-tumor activity of KRG on MDSCs. Therefore, we examined the effects of KRG on MDSCs in tumor-bearing mice and evaluated immunostimulatory and anti-tumor activities of KRG through MDSC modulation. The data show that intraperitoneal administration of KRG compromises MDSC function and induces T cell proliferation and the secretion of IL-2 and IFN-γ, while it does not exhibit direct cytotoxicity on tumor cells and reduced MDSC accumulation. MDSCs isolated from KRG-treated mice also express significantly lower levels of inducible nitric oxide synthase and IL-10 accompanied by a decrease in nitric oxide production compared with control. Taken together, the present study demonstrates that KRG enhances T cell function by inhibiting the immunosuppressive activity of MDSCs and suggests that although KRG alone does not exhibit direct anti-tumor effects, the use of KRG together with conventional chemo- or immunotherapy may provide better outcomes to cancer patients through MDSC modulation.

Insufficient natural killer cell responses against retroviruses: how to improve NK cell killing of retrovirus-infected cells.

PubMed

Littwitz-Salomon, Elisabeth; Dittmer, Ulf; Sutter, Kathrin

2016-11-08

Natural killer (NK) cells belong to the innate immune system and protect against cancers and a variety of viruses including retroviruses by killing transformed or infected cells. They express activating and inhibitory receptors on their cell surface and often become activated after recognizing virus-infected cells. They have diverse antiviral effector functions like the release of cytotoxic granules, cytokine production and antibody dependent cellular cytotoxicity. The importance of NK cell activity in retroviral infections became evident due to the discovery of several viral strategies to escape recognition and elimination by NK cells. Mutational sequence polymorphisms as well as modulation of surface receptors and their ligands are mechanisms of the human immunodeficiency virus-1 to evade NK cell-mediated immune pressure. In Friend retrovirus infected mice the virus can manipulate molecular or cellular immune factors that in turn suppress the NK cell response. In this model NK cells lack cytokines for optimal activation and can be functionally suppressed by regulatory T cells. However, these inhibitory pathways can be overcome therapeutically to achieve full activation of NK cell responses and ultimately control dissemination of retroviral infection. One effective approach is to modulate the crosstalk between NK cells and dendritic cells, which produce NK cell-stimulating cytokines like type I interferons (IFN), IL-12, IL-15, and IL-18 upon retrovirus sensing or infection. Therapeutic administration of IFNα directly increases NK cell killing of retrovirus-infected cells. In addition, IL-2/anti-IL-2 complexes that direct IL-2 to NK cells have been shown to significantly improve control of retroviral infection by NK cells in vivo. In this review, we describe novel approaches to improve NK cell effector functions in retroviral infections. Immunotherapies that target NK cells of patients suffering from viral infections might be a promising treatment option for the future.

miR-218 inhibits the invasive ability of glioma cells by direct downregulation of IKK-{beta}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Libing, E-mail: lb.song1@gmail.com; Huang, Quan; Chen, Kun

2010-11-05

Research highlights: {yields} miR-218 is markedly downregulated in glioma cell lines and in primary glioma tissues. {yields} Upregulation of miR-218 dramatically reduces the invasive ability of glioma cells. {yields} Ectopic expression of miR-218 inactivates IKK-{beta}/NF-{kappa}B signaling pathway. {yields} miR-218 directly targets the 3'-untranslated region (3'-UTR) of IKK-{beta}. -- Abstract: Aberrant activation of nuclear factor-kappa B (NF-{kappa}B) pathway has been proven to play important roles in the development and progression of cancers. Activation of NF-{kappa}B via the classical pathway is modulated by I{kappa}Bs kinase (IKK-{beta}). However, the mechanism underlying the epigenetic regulation of IKK-{beta}/NF-{kappa}B pathway remains largely unknown. In this study,more » we found that the expression level of miR-218 was markedly downregulated in glioma cell lines and in human primary glioma tissues. Upregulation of miR-218 dramatically reduced the migratory speed and invasive ability of glioma cells. Furthermore, we showed that ectopically expressing miR-218 in glioma cells resulted in downregulation of matrix metalloproteinase-9 (MMP-9) and reduction in NF-{kappa}B transactivity at a transcriptional level, but inhibition of miR-218 enhanced the expression of MMP-9 and transcriptional activity of NF-{kappa}B. Moreover, we showed that miR-218 inactivated the NF-{kappa}B pathway through downregulating IKK-{beta} expression by directly targeting the 3'-untranslated region (3'-UTR) of IKK-{beta}. Taken together, our results suggest that miR-218 plays an important role in preventing the invasiveness of glioma cells, and our results present a novel mechanism of miRNA-mediated direct suppression of IKK-{beta}/NF-{kappa}B pathway in gliomas.« less

Immune Checkpoint Blockade for Breast Cancer.

PubMed

Swoboda, April; Nanda, Rita

An effective antitumor immune response requires interaction between cells of the adaptive and innate immune system. Three key elements are required: generation of activated tumor-directed T cells, infiltration of activated T cells into the tumor microenvironment, and killing of tumor cells by activated T cells. Tumor immune evasion can occur as a result of the disruption of each of these three key T cell activities, resulting in three distinct cancer-immune phenotypes. The immune inflamed phenotype, characterized by the presence of a robust tumor immune infiltrate, suggests impaired activated T cell killing of tumor cells related to the presence of inhibitory factors. Programmed death receptor-1 (PD-1) is an inhibitory transmembrane protein expressed on T cells, B cells, and NK cells. The interaction between PD-1 and its ligands (PD-L1/L2) functions as an immune checkpoint against unrestrained cytotoxic T effector cell activity-it promotes peripheral T effector cell exhaustion and conversion of T effector cells to immunosuppressive T regulatory (Treg) cells. Immune checkpoint inhibitors, which block the PD-1/PD-L1 axis and reactivate cytotoxic T effector cell function, are actively being investigated for the treatment of breast cancer.

Mechanisms of CDC-42 activation during contact-induced cell polarization.

PubMed

Chan, Emily; Nance, Jeremy

2013-04-01

Polarization of early embryos provides a foundation to execute essential patterning and morphogenetic events. In Caenorhabditis elegans, cell contacts polarize early embryos along their radial axis by excluding the cortical polarity protein PAR-6 from sites of cell contact, thereby restricting PAR-6 to contact-free cell surfaces. Radial polarization requires the cortically enriched Rho GTPase CDC-42, which in its active form recruits PAR-6 through direct binding. The Rho GTPase activating protein (RhoGAP) PAC-1, which localizes specifically to cell contacts, triggers radial polarization by inactivating CDC-42 at these sites. The mechanisms responsible for activating CDC-42 at contact-free surfaces are unknown. Here, in an overexpression screen of Rho guanine nucleotide exchange factors (RhoGEFs), which can activate Rho GTPases, we identify CGEF-1 and ECT-2 as RhoGEFs that act through CDC-42 to recruit PAR-6 to the cortex. We show that ECT-2 and CGEF-1 localize to the cell surface and that removing their activity causes a reduction in levels of cortical PAR-6. Through a structure-function analysis, we show that the tandem DH-PH domains of CGEF-1 and ECT-2 are sufficient for GEF activity, but that regions outside of these domains target each protein to the cell surface. Finally, we provide evidence suggesting that the N-terminal region of ECT-2 may direct its in vivo preference for CDC-42 over another known target, the Rho GTPase RHO-1. We propose that radial polarization results from a competition between RhoGEFs, which activate CDC-42 throughout the cortex, and the RhoGAP PAC-1, which inactivates CDC-42 at cell contacts.

Mechanisms of CDC-42 activation during contact-induced cell polarization

PubMed Central

Chan, Emily; Nance, Jeremy

2013-01-01

Summary Polarization of early embryos provides a foundation to execute essential patterning and morphogenetic events. In Caenorhabditis elegans, cell contacts polarize early embryos along their radial axis by excluding the cortical polarity protein PAR-6 from sites of cell contact, thereby restricting PAR-6 to contact-free cell surfaces. Radial polarization requires the cortically enriched Rho GTPase CDC-42, which in its active form recruits PAR-6 through direct binding. The Rho GTPase activating protein (RhoGAP) PAC-1, which localizes specifically to cell contacts, triggers radial polarization by inactivating CDC-42 at these sites. The mechanisms responsible for activating CDC-42 at contact-free surfaces are unknown. Here, in an overexpression screen of Rho guanine nucleotide exchange factors (RhoGEFs), which can activate Rho GTPases, we identify CGEF-1 and ECT-2 as RhoGEFs that act through CDC-42 to recruit PAR-6 to the cortex. We show that ECT-2 and CGEF-1 localize to the cell surface and that removing their activity causes a reduction in levels of cortical PAR-6. Through a structure–function analysis, we show that the tandem DH-PH domains of CGEF-1 and ECT-2 are sufficient for GEF activity, but that regions outside of these domains target each protein to the cell surface. Finally, we provide evidence suggesting that the N-terminal region of ECT-2 may direct its in vivo preference for CDC-42 over another known target, the Rho GTPase RHO-1. We propose that radial polarization results from a competition between RhoGEFs, which activate CDC-42 throughout the cortex, and the RhoGAP PAC-1, which inactivates CDC-42 at cell contacts. PMID:23424200

Cancer Vaccine Composed of Oligonucleotides Conjugated to Apoptotic Tumor Cells | NCI Technology Transfer Center | TTC

Cancer.gov

Synthetic oligodeoxynucleotides (ODN) containing unmethylated Cytosine-Guanine (CpG) motifs mimic the immunostimulatory activity of bacterial DNA. CpG ODN directly stimulate B cells and plasmacytoid dendritic cells (pDC), promote the production of T Helper 1 cells (Th1) and pro-inflammatory cytokines, and  trigger the maturation/activation of professional antigen presenting cells. The National Cancer Institute, Laboratory of Experimental Immunology, seeks interested parties to co- develop methods for inducing an immune response to tumors.

Single cell analysis of low-power laser irradiation-induced activation of signaling pathway in cell proliferation

NASA Astrophysics Data System (ADS)

Xing, Da; Gao, Xuejuan

2007-02-01

Low-power laser irradiation (LPLI) has been shown to promote cell proliferation in various cell types, yet the mechanism of which has not been fully clarified. Investigating the signaling pathways involved in the laser irradiation is important for understanding these processes. The small G protein Ras works as a binary switch in many important intracellular signaling pathways and, therefore, has been one of the focal targets of signal-transduction investigations and drug development. The Ras/Raf/MEK/ERK (extracellular-signal-regulated kinase) signaling pathway is a network that governs proliferation, differentiation and cell survival. Recent studies suggest that Ras/Raf signaling pathway is involved in the LPLI-induced cell proliferation. On the other hand, Protein kinase Cs (PKCs), the Ca 2+ activated, phospholipid-dependent serine/threonine protein kinases, have been recently presumed to be involved in the regulation of cell proliferation induced by LPLI. In this report, to monitor the direct activations of Ras and PKCs after LPLI treatment in living cells in real time, Raichu-Ras reporter and C kinase activity reporter (CKAR) were utilized, both of which were constructed based on fluorescence resonance energy transfer (FRET) technique. The direct activation of Ras is predominantly initiated from the different microdomains of the plasma membrane. The results are monitored during cell proliferation induced by LPLI (0.8 J/cm2) in serum-starved COS-7 cells expressing Raichu-Ras reporter using FRET imaging on laser scanning confocal microscope. Furthermore, the increasing activation of PKCs is also monitored during cell proliferation induced by LPLI (0.8 J/cm2) in serum-starved human lung adenocarcinoma cells (ASTC-a-1) expressing CKAR reporter using the similar way. Taken together, the dynamic increases of H-Ras and PKCs activities are observed during the processes of cell proliferation induced by LPLI.

Role of exchange protein directly activated by cAMP (EPAC1) in breast cancer cell migration and apoptosis.

PubMed

Kumar, Naveen; Gupta, Sonal; Dabral, Surbhi; Singh, Shailja; Sehrawat, Seema

2017-06-01

Despite the current progress in cancer research and therapy, breast cancer remains the leading cause of mortality among half a million women worldwide. Migration and invasion of cancer cells are associated with prevalent tumor metastasis as well as high mortality. Extensive studies have powerfully established the role of prototypic second messenger cAMP and its two ubiquitously expressed intracellular cAMP receptors namely the classic protein kinaseA/cAMP-dependent protein kinase (PKA) and the more recently discovered exchange protein directly activated by cAMP/cAMP-regulated guanine nucleotide exchange factor (EPAC/cAMP-GEF) in cell migration, cell cycle regulation, and cell death. Herein, we performed the analysis of the Cancer Genome Atlas (TCGA) dataset to evaluate the essential role of cAMP molecular network in breast cancer. We report that EPAC1, PKA, and AKAP9 along with other molecular partners are amplified in breast cancer patients, indicating the importance of this signaling network. To evaluate the functional role of few of these proteins, we used pharmacological modulators and analyzed their effect on cell migration and cell death in breast cancer cells. Hence, we report that inhibition of EPAC1 activity using pharmacological modulators leads to inhibition of cell migration and induces cell death. Additionally, we also observed that the inhibition of EPAC1 resulted in disruption of its association with the microtubule cytoskeleton and delocalization of AKAP9 from the centrosome as analyzed by in vitro imaging. Finally, this study suggests for the first time the mechanistic insights of mode of action of a primary cAMP-dependent sensor, Exchange protein activated by cAMP 1 (EPAC1), via its interaction with A-kinase anchoring protein 9 (AKAP9). This study provides a new cell signaling cAMP-EPAC1-AKAP9 direction to the development of additional biotherapeutics for breast cancer.

Parsimony and complexity: Cell fate assignment in the developing Drosophila eye.

PubMed

Mavromatakis, Yannis Emmanuel; Tomlinson, Andrew

2017-07-03

The specification of the R7 photoreceptor in the Drosophila eye has become a classic model for understanding how cell fates are assigned in developing systems. R7 is derived from a group of cells that also gives rise to the R1/6 photoreceptor class and the non-photoreceptor cone cells. Our studies examine the signals and cellular information that direct each of these cell types. The cell fates are directed by the combined actions of the Receptor Tyrosine Kinase (RTK) and Notch (N) signaling pathways. The RTK pathway acts to remove the transcription factor Tramtrack (Ttk) which represses the photoreceptor fate. If a cell receives an RTK signal sufficient to remove Ttk then the photoreceptor fate is specified; if not, the cone cell fate results. If Ttk is removed from a cell and its N activity is high then it is specified as an R7, but if its N activity is low then it becomes an R1/6 class photoreceptor. Thus, a remarkably simple molecular code underlies the specification of the fates: 1. Ttk degraded or not: 2. N activity high or low. In the R1/6 and cone cell precursors the molecular codes are achieved with relative simplicity but in the R7 precursor, manifold interactions occur between the RTK and N pathways, and to-date we have identified 4 distinct roles played by N in R7 fate specification. In this review we detail this molecular complexity, and describe how the RTK/N pathway crosstalk eventually leads to the simple molecular code of Tramtrack removed and N activity high. Furthermore, we describe the role played by the transcription factor Lozenge (Lz) in directing retinal precursor fates, and how the RTK/N signals specify different retinal cell types depending on the presence or absence of Lz.

Direct antigonadal activity of cannabinoids: suppression of rat granulosa cell functions.

PubMed

Adashi, E Y; Jones, P B; Hsueh, A J

1983-02-01

The direct effects of delta 9-tetrahydrocannabinol (THC) and related cannabinoids on ovarian granulosa cells were studied in vitro. Granulosa cells from immature, hypophysectomized, estrogen-treated rats were cultured for 2 days in an androstenedione-supplemented medium in the presence or absence of follicle-stimulating hormone (FSH) (10 ng/ml) with or without cannabinoids. FSH treatment increased progesterone and estrogen biosynthesis, whereas concomitant treatment with THC led to a dose-dependent inhibition of the FSH-stimulated accumulation of progesterone and estrogen with ED50 values of 3.5 +/- 0.3 X 10(-7) and 1.8 +/- 0.2 X 10(-6) M, respectively. Treatment with related but nonpsychoactive cannabinoids (cannabidiol, cannabinol, cannabigerol, or cannabichromene) was equally effective. The THC-induced inhibition of progesterone production was reversible and was associated with an inhibition of pregnenolone biosynthesis and a decrease of 3 beta-hydroxysteroid dehydrogenase activity. In addition, treatment with THC brought about a dose-dependent inhibition of the FSH-induced increase in luteinizing hormone (LH) receptors. The inhibitory effects of THC were not associated with changes in cell number, protein content, or cell viability. Thus, THC exerts direct inhibitory effects on FSH-dependent functions related to steroidogenesis and the acquisition of LH receptors, all of which are essential to follicular maturation. Because plasma concentrations of THC similar to those used in this study have been reported in human beings, repeated exposure of female users to THC may lead to ovarian dysfunction, due in part, to the direct antigonadal activity to THC.

Human papillomavirus-exposed Langerhans cells are activated by stabilized Poly-I:C.

PubMed

Da Silva, Diane M; Woodham, Andrew W; Rijkee, Laurie K; Skeate, Joseph G; Taylor, Julia R; Koopman, Maaike E; Brand, Heike E; Wong, Michael K; McKee, Greg M; Salazar, Andres M; Kast, W Martin

2015-12-01

Human papillomaviruses (HPV) establish persistent infections because of evolved immune evasion mechanisms, particularly HPV-mediated suppression of the immune functions of Langerhans cells (LC), the antigen presenting cells of the epithelium. Polyinosinic-polycytidilic acid (Poly-I:C) is broadly immunostimulatory with the ability to enhance APC expression of costimulatory molecules and inflammatory cytokines resulting in T cell activation. Here we investigated the activation of primary human LC derived from peripheral blood monocytes after exposure to HPV16 virus like particles followed by treatment with stabilized Poly-I:C compounds (s-Poly-I:C), and their subsequent induction of HPV16-specific T cells. Our results indicate that HPV16 particles alone were incapable of inducing LC activation as demonstrated by the lack of costimulatory molecules, inflammatory cytokines, chemokine-directed migration, and HPV16-specific CD8 + T cells in vitro . Conversely, s-Poly-I:C caused significant upregulation of costimulatory molecules and induction of chemokine-directed migration of LC that were pre-exposed to HPV16. In HLA-A*0201-positive donors, s-Poly-I:C treatment was able to induce CD8 + T cell immune responses against HPV16-derived peptides. Thus, s-Poly-I:C compounds are attractive for translation into therapeutics in which they could potentially mediate clearance of persistent HPV infection.

CD56 Is a Pathogen Recognition Receptor on Human Natural Killer Cells.

PubMed

Ziegler, Sabrina; Weiss, Esther; Schmitt, Anna-Lena; Schlegel, Jan; Burgert, Anne; Terpitz, Ulrich; Sauer, Markus; Moretta, Lorenzo; Sivori, Simona; Leonhardt, Ines; Kurzai, Oliver; Einsele, Hermann; Loeffler, Juergen

2017-07-21

Aspergillus (A.) fumigatus is an opportunistic fungal mold inducing invasive aspergillosis (IA) in immunocompromised patients. Although antifungal activity of human natural killer (NK) cells was shown in previous studies, the underlying cellular mechanisms and pathogen recognition receptors (PRRs) are still unknown. Using flow cytometry we were able to show that the fluorescence positivity of the surface receptor CD56 significantly decreased upon fungal contact. To visualize the interaction site of NK cells and A. fumigatus we used SEM, CLSM and dSTORM techniques, which clearly demonstrated that NK cells directly interact with A. fumigatus via CD56 and that CD56 is re-organized and accumulated at this interaction site time-dependently. The inhibition of the cytoskeleton showed that the receptor re-organization was an active process dependent on actin re-arrangements. Furthermore, we could show that CD56 plays a role in the fungus mediated NK cell activation, since blocking of CD56 surface receptor reduced fungal mediated NK cell activation and reduced cytokine secretion. These results confirmed the direct interaction of NK cells and A. fumigatus, leading to the conclusion that CD56 is a pathogen recognition receptor. These findings give new insights into the functional role of CD56 in the pathogen recognition during the innate immune response.

Optical micromanipulation of active cells with minimal perturbations: direct and indirect pushing.

PubMed

Wang, Chenlu; Chowdhury, Sagar; Gupta, Satyandra K; Losert, Wolfgang

2013-04-01

The challenge to wide application of optical tweezers in biological micromanipulation is the photodamage caused by high-intensity laser exposure to the manipulated living systems. While direct exposure to infrared lasers is less likely to kill cells, it can affect cell behavior and signaling. Pushing cells with optically trapped objects has been introduced as a less invasive alternative, but the technique includes some exposure of the biological object to parts of the optical tweezer beam. To keep the cells farther away from the laser, we introduce an indirect pushing-based technique for noninvasive manipulation of sensitive cells. We compare how cells respond to three manipulation approaches: direct manipulation, pushing, and indirect pushing. We find that indirect manipulation techniques lessen the impact of manipulation on cell behavior. Cell survival increases, as does the ability of cells to maintain shape and wiggle. Our experiments also demonstrate that indirect pushing allows cell-cell contacts to be formed in a controllable way, while retaining the ability of cells to change shape and move.

The murine SP-C promoter directs type II cell-specific expression in transgenic mice.

PubMed

Glasser, Stephan W; Eszterhas, Susan K; Detmer, Emily A; Maxfield, Melissa D; Korfhagen, Thomas R

2005-04-01

Genomic DNA from the mouse pulmonary surfactant protein C (SP-C) gene was analyzed in transgenic mice to identify DNA essential for alveolar type II cell-specific expression. SP-C promoter constructs extending either 13 or 4.8 kb upstream of the transcription start site directed lung-specific expression of the bacterial chloramphenicol acetyl transferase (CAT) reporter gene. In situ hybridization analysis demonstrated alveolar cell-specific expression in the lungs of adult transgenic mice, and the pattern of 4.8 SP-C-CAT expression during development paralleled that of the endogenous SP-C gene. With the use of deletion constructs, lung-specific, low-level CAT activity was detected in tissue assays of SP-C-CAT transgenic mice retaining 318 bp of the promoter. In transient and stable cell transfection experiments, the 4.8-kb SP-C promoter was 90-fold more active as a stably integrated gene. These findings indicate that 1) the 4.8-kb SP-C promoter is sufficient to direct cell-specific and developmental expression, 2) an enhancer essential for lung-specific expression maps to the proximal 318-bp promoter, and 3) the activity of the 4.8-kb SP-C promoter construct is highly dependent on its chromatin environment.

Direct anti-inflammatory effects of granulocyte colony-stimulating factor (G-CSF) on activation and functional properties of human T cell subpopulations in vitro.

PubMed

Malashchenko, Vladimir Vladimirovich; Meniailo, Maxsim Evgenievich; Shmarov, Viacheslav Anatolievich; Gazatova, Natalia Dinislamovna; Melashchenko, Olga Borisovna; Goncharov, Andrei Gennadievich; Seledtsova, Galina Victorovna; Seledtsov, Victor Ivanovich

2018-03-01

We investigated the direct effects of human granulocyte colony-stimulating factor (G-CSF) on functionality of human T-cell subsets. CD3 + T-lymphocytes were isolated from blood of healthy donors by positive magnetic separation. T cell activation with particles conjugated with antibodies (Abs) to human CD3, CD28 and CD2 molecules increased the proportion of cells expressing G-CSF receptor (G-CSFR, CD114) in all T cell subpopulations studied (CD45RA + /CD197 + naive T cells, CD45RA - /CD197 + central memory T cells, CD45RA - /CD197 - effector memory T cells and CD45RA + /CD197 - terminally differentiated effector T cells). Upon T-cell activation in vitro, G-CSF (10.0 ng/ml) significantly and specifically enhanced the proportion of CD114 + T cells in central memory CD4 + T cell compartment. A dilution series of G-CSF (range, 0.1-10.0 ng/ml) was tested, with no effect on the expression of CD25 (interleukin-2 receptor α-chain) on activated T cells. Meanwhile, G-CSF treatment enhanced the proportion of CD38 + T cells in CD4 + naïve T cell, effector memory T cell and terminally differentiated effector T cell subsets, as well as in CD4 - central memory T cells and terminally differentiated effector T cells. G-CSF did not affect IL-2 production by T cells; relatively low concentrations of G-CSF down-regulated INF-γ production, while high concentrations of this cytokine up-regulated IL-4 production in activated T cells. The data obtained suggests that G-CSF could play a significant role both in preventing the development of excessive and potentially damaging inflammatory reactivity, and in constraining the expansion of potentially cytodestructive T cells. Copyright © 2018 Elsevier Inc. All rights reserved.

Water at Biological Phase Boundaries: Its Role in Interfacial Activation of Enzymes and Metabolic Pathways.

PubMed

Damodaran, Srinivasan

2015-01-01

Many life-sustaining activities in living cells occur at the membrane-water interface. The pertinent questions that we need to ask are, what are the evolutionary reasons in biology for choosing the membrane-water interface as the site for performing and/or controlling crucial biological reactions, and what is the key physical principle that is very singular to the membrane-water interface that biology exploits for regulating metabolic processes in cells? In this chapter, a hypothesis is developed, which espouses that cells control activities of membrane-bound enzymes through manipulation of the thermodynamic activity of water in the lipid-water interfacial region. The hypothesis is based on the fact that the surface pressure of a lipid monolayer is a direct measure of the thermodynamic activity of water at the lipid-water interface. Accordingly, the surface pressure-dependent activation or inactivation of interfacial enzymes is directly related to changes in the thermodynamic activity of interfacial water. Extension of this argument suggests that cells may manipulate conformations (and activities) of membrane-bound enzymes by manipulating the (re)activity of interfacial water at various locations in the membrane by localized compression or expansion of the interface. In this respect, cells may use the membrane-bound hormone receptors, lipid phase transition, and local variations in membrane lipid composition as effectors of local compression and/or expansion of membrane, and thereby local water activity. Several experimental data in the literature will be reexamined in the light of this hypothesis.

Yeast G-proteins mediate directional sensing and polarization behaviors in response to changes in pheromone gradient direction

PubMed Central

Moore, Travis I.; Tanaka, Hiromasa; Kim, Hyung Joon; Jeon, Noo Li; Yi, Tau-Mu

2013-01-01

Yeast cells polarize by projecting up mating pheromone gradients, a classic cell polarity behavior. However, these chemical gradients may shift direction. We examine how yeast cells sense and respond to a 180o switch in the direction of microfluidically generated pheromone gradients. We identify two behaviors: at low concentrations of α-factor, the initial projection grows by bending, whereas at high concentrations, cells form a second projection toward the new source. Mutations that increase heterotrimeric G-protein activity expand the bending-growth morphology to high concentrations; mutations that increase Cdc42 activity result in second projections at low concentrations. Gradient-sensing projection bending requires interaction between Gβγ and Cdc24, whereas gradient-nonsensing projection extension is stimulated by Bem1 and hyperactivated Cdc42. Of interest, a mutation in Gα affects both bending and extension. Finally, we find a genetic perturbation that exhibits both behaviors. Overexpression of the formin Bni1, a component of the polarisome, makes both bending-growth projections and second projections at low and high α-factor concentrations, suggesting a role for Bni1 downstream of the heterotrimeric G-protein and Cdc42 during gradient sensing and response. Thus we demonstrate that G-proteins modulate in a ligand-dependent manner two fundamental cell-polarity behaviors in response to gradient directional change. PMID:23242998

Induction of suppression through human T cell interactions.

PubMed

Lydyard, P M; Hayward, A R

1980-02-01

Concanavalin A (Con A) activated T cells, devoid of cells bearing Fc receptors for IgG (T - TG) help human B lymphocytes to differentiate into plasma cells (PC) in response to pokeweed mitogen (PWM). PC differentiation is reduced when adult T cells are added to such cultures. The radiosensitivity of suppression and the radioresistance of help enabled us to show that adult T cells include a suppressor-precursor which is activated by irradiated Con A-precultured T cells. Newborn T cells which include active suppressors, are both poor stimulators of suppressor-precursors and poor helpers of B cells. Our results suggest that at least two cells may mediate Con A-induced suppression, one which suppresses directly and is radiosensitive and another which is radioresistant and stimulates suppressor-precursors in a target population of T cells.

Intact LKB1 activity is required for survival of dormant ovarian cancer spheroids

PubMed Central

Peart, Teresa; Valdes, Yudith Ramos; Correa, Rohann J. M.; Fazio, Elena; Bertrand, Monique; McGee, Jacob; Préfontaine, Michel; Sugimoto, Akira; DiMattia, Gabriel E.; Shepherd, Trevor G.

2015-01-01

Metastatic epithelial ovarian cancer (EOC) cells can form multicellular spheroids while in suspension and disperse directly throughout the peritoneum to seed secondary lesions. There is growing evidence that EOC spheroids are key mediators of metastasis, and they use specific intracellular signalling pathways to control cancer cell growth and metabolism for increased survival. Our laboratory discovered that AKT signalling is reduced during spheroid formation leading to cellular quiescence and autophagy, and these may be defining features of tumour cell dormancy. To further define the phenotype of EOC spheroids, we have initiated studies of the Liver kinase B1 (LKB1)-5′-AMP-activated protein kinase (AMPK) pathway as a master controller of the metabolic stress response. We demonstrate that activity of AMPK and its upstream kinase LKB1 are increased in quiescent EOC spheroids as compared with proliferating adherent EOC cells. We also show elevated AMPK activity in spheroids isolated directly from patient ascites. Functional studies reveal that treatment with the AMP mimetic AICAR or allosteric AMPK activator A-769662 led to a cytostatic response in proliferative adherent ovarian cancer cells, but they fail to elicit an effect in spheroids. Targeted knockdown of STK11 by RNAi to reduce LKB1 expression led to reduced viability and increased sensitivity to carboplatin treatment in spheroids only, a phenomenon which was AMPK-independent. Thus, our results demonstrate a direct impact of altered LKB1-AMPK signalling function in EOC. In addition, this is the first evidence in cancer cells demonstrating a pro-survival function for LKB1, a kinase traditionally thought to act as a tumour suppressor. PMID:26068970

Alzheimer disease-related presenilin-1 variants exert distinct effects on monoamine oxidase-A activity in vitro.

PubMed

Pennington, Paul R; Wei, Zelan; Rui, Lewei; Doig, Jennifer A; Graham, Brett; Kuski, Kelly; Gabriel, Geraldine G; Mousseau, Darrell D

2011-07-01

Monoamine oxidase-A (MAO-A) has been associated with both depression and Alzheimer disease (AD). Recently, carriers of AD-related presenilin-1 (PS-1) alleles have been found to be at higher risk for developing clinical depression. We chose to examine whether PS-1 could influence MAO-A function in vitro. Overexpression of selected AD-related PS-1 variants (wildtype, Y115H, ΔEx9 and M146V) in mouse hippocampal HT-22 cells affects MAO-A catalytic activity in a variant-specific manner. The ability of the PS-1 substrate-competitor DAPT to induce MAO-A activity in cells expressing either PS-1 wildtype or PS-1(M146V) suggests the potential for a direct influence of PS-1 on MAO-A function. In support of this, we were able to co-immunoprecipitate MAO-A with FLAG-tagged PS-1 wildtype and M146V proteins. This potential for a direct protein-protein interaction between PS-1 and MAO-A is not specific for HT-22 cells as we were also able to co-immunoprecipitate MAO-A with FLAG-PS-1 variants in N2a mouse neuroblastoma cells and in HEK293 human embryonic kidney cells. Finally, we demonstrate that the two PS-1 variants reported to be associated with an increased incidence of clinical depression [e.g., A431E and L235V] both induce MAO-A activity in HT-22 cells. A direct influence of PS-1 variants on MAO-A function could provide an explanation for the changes in monoaminergic tone observed in several neurodegenerative processes including AD. The ability to induce MAO-A catalytic activity with a PS-1/γ-secretase inhibitor should also be considered when designing secretase inhibitor-based therapeutics.

Biochemical Assays of Cultured Cells

NASA Technical Reports Server (NTRS)

Barlow, G. H.

1985-01-01

Subpopulations of human embryonic kidney cells isolated from continuous flow electrophoresis experiments performed at McDonnell Douglas and on STS-8 have been analyzed. These analyses have included plasminogen activator assays involving indirect methodology on fibrin plated and direct methodology using chromogenic substrates. Immunological studies were performed and the conditioned media for erythropoietin activity and human granulocyte colony stimulating (HGCSF) activity was analyzed.

High-content analysis of single cells directly assembled on CMOS sensor based on color imaging.

PubMed

Tanaka, Tsuyoshi; Saeki, Tatsuya; Sunaga, Yoshihiko; Matsunaga, Tadashi

2010-12-15

A complementary metal oxide semiconductor (CMOS) image sensor was applied to high-content analysis of single cells which were assembled closely or directly onto the CMOS sensor surface. The direct assembling of cell groups on CMOS sensor surface allows large-field (6.66 mm×5.32 mm in entire active area of CMOS sensor) imaging within a second. Trypan blue-stained and non-stained cells in the same field area on the CMOS sensor were successfully distinguished as white- and blue-colored images under white LED light irradiation. Furthermore, the chemiluminescent signals of each cell were successfully visualized as blue-colored images on CMOS sensor only when HeLa cells were placed directly on the micro-lens array of the CMOS sensor. Our proposed approach will be a promising technique for real-time and high-content analysis of single cells in a large-field area based on color imaging. Copyright © 2010 Elsevier B.V. All rights reserved.

Lipid rafts sense and direct electric field-induced migration

PubMed Central

Lin, Bo-jian; Tsao, Shun-hao; Chen, Alex; Hu, Shu-Kai; Chao, Ling

2017-01-01

Endogenous electric fields (EFs) are involved in developmental regulation and wound healing. Although the phenomenon is known for more than a century, it is not clear how cells perceive the external EF. Membrane proteins, responding to electrophoretic and electroosmotic forces, have long been proposed as the sensing molecules. However, specific charge modification of surface proteins did not change cell migration motility nor directionality in EFs. Moreover, symmetric alternating current (AC) EF directs cell migration in a frequency-dependent manner. Due to their charge and ability to coalesce, glycolipids are therefore the likely primary EF sensor driving polarization of membrane proteins and intracellular signaling. We demonstrate that detergent-resistant membrane nanodomains, also known as lipid rafts, are the primary response element in EF sensing. The clustering and activation of caveolin and signaling proteins further stabilize raft structure and feed-forward downstream signaling events, such as rho and PI3K activation. Theoretical modeling supports the experimental results and predicts AC frequency-dependent cell and raft migration. Our results establish a fundamental mechanism for cell electrosensing and provide a role in lipid raft mechanotransduction. PMID:28739955

Lipid rafts sense and direct electric field-induced migration.

PubMed

Lin, Bo-Jian; Tsao, Shun-Hao; Chen, Alex; Hu, Shu-Kai; Chao, Ling; Chao, Pen-Hsiu Grace

2017-08-08

Endogenous electric fields (EFs) are involved in developmental regulation and wound healing. Although the phenomenon is known for more than a century, it is not clear how cells perceive the external EF. Membrane proteins, responding to electrophoretic and electroosmotic forces, have long been proposed as the sensing molecules. However, specific charge modification of surface proteins did not change cell migration motility nor directionality in EFs. Moreover, symmetric alternating current (AC) EF directs cell migration in a frequency-dependent manner. Due to their charge and ability to coalesce, glycolipids are therefore the likely primary EF sensor driving polarization of membrane proteins and intracellular signaling. We demonstrate that detergent-resistant membrane nanodomains, also known as lipid rafts, are the primary response element in EF sensing. The clustering and activation of caveolin and signaling proteins further stabilize raft structure and feed-forward downstream signaling events, such as rho and PI3K activation. Theoretical modeling supports the experimental results and predicts AC frequency-dependent cell and raft migration. Our results establish a fundamental mechanism for cell electrosensing and provide a role in lipid raft mechanotransduction.

RNA binding protein Lin28B confers gastric cancer cells stemness via directly binding to NRP-1.

PubMed

Wang, Xiaocong; Hu, Huihua; Liu, Hebo

2018-05-19

This work aims to explore the roles and related mechanisms of RNA binding protein Lin28B in gastric cancer cells stemness. We found that Lin28B expression was negatively correlated with the overall survival (OS) of gastric cancer patients, and significantly increased in gastric cancer cells compared with that in gastric epithelial cells. Lin28B overexpression increased spheroid formation, expression of gastric cancer stemness-related markers, and decreased cisplatin sensitivity in gastric cancer cells. Mechanistically, Lin28B could directly bind to NRP-1 3'UTR, thus increasing NRP-1 mRNA stability and expression, and activate the downstream Wnt/β-catenin signaling. Knockdown of NRP-1 or treatment with Wnt/β-catenin antagonist could rescue the promotive effects of Lin28B on gastric cancer stemness. Thus, thes results indicate that Lin28B could facilitate gastric cancer stemness via directly binding to NRP-1 3'UTR and activating the downstream Wnt/β-catenin signaling. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Mesenchymal stem cells inhibit RANK-RANKL interactions between osteoclasts and Th17 cells via osteoprotegerin activity

PubMed Central

Cho, Kyung-Ah; Park, Minhwa; Kim, Yu-Hee; Ryu, Kyung-Ha; Woo, So-Youn

2017-01-01

Th17 cells play a critical role in several autoimmune diseases, including psoriasis and psoriatic arthritis (PsA). Psoriasis is a chronic inflammatory skin disease associated with systemic inflammation and comorbidities, such as PsA. PsA develops in nearly 70% of patients with psoriasis, and osteoclasts associated bone erosion is a hallmark of the disease. Thus far, the effect of Th17 cells on osteoclastogenesis via direct cell-to-cell interactions is less understood. In this study, we observed that Th17 cells directly promote osteoclast differentiation and maturation via expression of receptor activator of nuclear factor-κ β ligand (RANKL) in vitro. We investigated the impact of conditioned medium obtained from human palatine tonsil-derived mesenchymal stem cells (T-CM) on the interactions between osteoclasts and Th17 cells. T-CM effectively blunted the RANK-RANKL interaction between the osteoclast precursor cell line RAW 264.7 and Th17 cells via osteoprotegerin (OPG) activity. The frequency of tartrate-resistant acid phosphatase (TRAP)-positive cells in the bone marrow of an imiquimod (IMQ)-induced psoriasis mouse model was decreased following T-CM injection. Therefore, our data provide novel insight into the therapeutic potential of tonsil-derived mesenchymal stem cell-mediated therapy (via OPG production) for the treatment of pathophysiologic processes induced by osteoclasts under chronic inflammatory conditions such as psoriasis. PMID:29137353

B cells in chronic obstructive pulmonary disease: moving to center stage

PubMed Central

Polverino, Francesca; Seys, Leen J. M.; Bracke, Ken R.

2016-01-01

Chronic inflammatory responses in the lungs contribute to the development and progression of chronic obstructive pulmonary disease (COPD). Although research studies focused initially on the contributions of the innate immune system to the pathogenesis of COPD, more recent studies have implicated adaptive immune responses in COPD. In particular, studies have demonstrated increases in B cell counts and increases in the number and size of B cell-rich lymphoid follicles in COPD lungs that correlate directly with COPD severity. There are also increases in lung levels of mediators that promote B cell maturation, activation, and survival in COPD patients. B cell products such as autoantibodies directed against lung cells, components of cells, and extracellular matrix proteins are also present in COPD lungs. These autoantibodies may contribute to lung inflammation and injury in COPD patients, in part, by forming immune complexes that activate complement components. Studies of B cell-deficient mice and human COPD patients have linked B cells most strongly to the emphysema phenotype. However, B cells have protective activities during acute exacerbations of COPD by promoting adaptive immune responses that contribute to host defense against pathogens. This review outlines the evidence that links B cells and B cell-rich lymphoid follicles to the pathogenesis of COPD and the mechanisms involved. It also reviews the potential and limitations of B cells as therapeutic targets to slow the progression of human COPD. PMID:27542809

ATM directs DNA damage responses and proteostasis via genetically separable pathways

PubMed Central

Lee, Ji-Hoon; Mand, Michael R.; Kao, Chung-Hsuan; Zhou, Yi; Ryu, Seung W.; Richards, Alicia L.; Coon, Joshua J.; Paull, Tanya T.

2018-01-01

The protein kinase ATM is a master regulator of the DNA damage response but also responds directly to oxidative stress. Loss of ATM causes Ataxia telangiectasia, a neurodegenerative disorder with pleiotropic symptoms that include cerebellar dysfunction, cancer, diabetes, and premature aging. Here, we genetically separated DNA damage activation of ATM from oxidative activation using separation-of-function mutations. We found that deficiency in ATM activation by Mre11-Rad50-Nbs1 and DNA double-strand breaks resulted in loss of cell viability, checkpoint activation, and DNA end resection in response to DNA damage. In contrast, loss of oxidative activation of ATM had minimal effects on DNA damage-related outcomes but blocked ATM-mediated initiation of checkpoint responses after oxidative stress and resulted in deficiencies in mitochondrial function and autophagy. In addition, expression of ATM lacking oxidative activation generates widespread protein aggregation. These results indicate a direct relationship between the mechanism of ATM activation and its effects on cellular metabolism and DNA damage responses in human cells and implicates ATM in the control of protein homeostasis. PMID:29317520

Direct Interaction of Jak1 and v-Abl Is Required for v-Abl-Induced Activation of STATs and Proliferation

PubMed Central

Danial, Nika N.; Losman, Julie A.; Lu, Tianhong; Yip, Natalie; Krishnan, Kartik; Krolewski, John; Goff, Stephen P.; Wang, Jean Y. J.; Rothman, Paul B.

1998-01-01

In Abelson murine leukemia virus (A-MuLV)-transformed cells, members of the Janus kinase (Jak) family of non-receptor tyrosine kinases and the signal transducers and activators of transcription (STAT) family of signaling proteins are constitutively activated. In these cells, the v-Abl oncoprotein and the Jak proteins physically associate. To define the molecular mechanism of constitutive Jak-STAT signaling in these cells, the functional significance of the v-Abl–Jak association was examined. Mapping the Jak1 interaction domain in v-Abl demonstrates that amino acids 858 to 1080 within the carboxyl-terminal region of v-Abl bind Jak1 through a direct interaction. A mutant of v-Abl lacking this region exhibits a significant defect in Jak1 binding in vivo, fails to activate Jak1 and STAT proteins, and does not support either the proliferation or the survival of BAF/3 cells in the absence of cytokine. Cells expressing this v-Abl mutant show extended latency and decreased frequency in generating tumors in nude mice. In addition, inducible expression of a kinase-inactive mutant of Jak1 protein inhibits the ability of v-Abl to activate STATs and to induce cytokine-independent proliferation, indicating that an active Jak1 is required for these v-Abl-induced signaling pathways in vivo. We propose that Jak1 is a mediator of v-Abl-induced STAT activation and v-Abl induced proliferation in BAF/3 cells, and may be important for efficient transformation of immature B cells by the v-abl oncogene. PMID:9774693

Sorting drops and cells with acoustics: acoustic microfluidic fluorescence-activated cell sorter.

PubMed

Schmid, Lothar; Weitz, David A; Franke, Thomas

2014-10-07

We describe a versatile microfluidic fluorescence-activated cell sorter that uses acoustic actuation to sort cells or drops at ultra-high rates. Our acoustic sorter combines the advantages of traditional fluorescence-activated cell (FACS) and droplet sorting (FADS) and is applicable for a multitude of objects. We sort aqueous droplets, at rates as high as several kHz, into two or even more outlet channels. We can also sort cells directly from the medium without prior encapsulation into drops; we demonstrate this by sorting fluorescently labeled mouse melanoma cells in a single phase fluid. Our acoustic microfluidic FACS is compatible with standard cell sorting cytometers, yet, at the same time, enables a rich variety of more sophisticated applications.

MiRNA-335 suppresses neuroblastoma cell invasiveness by direct targeting of multiple genes from the non-canonical TGF-β signalling pathway

PubMed Central

Lynch, Jennifer; Fay, Joanna; Meehan, Maria; Bryan, Kenneth; Watters, Karen M.; Murphy, Derek M.; Stallings, Raymond L.

2012-01-01

Transforming growth factor-β (TGF-β) signaling regulates many diverse cellular activities through both canonical (SMAD-dependent) and non-canonical branches, which includes the mitogen-activated protein kinase (MAPK), Rho-like guanosine triphosphatase and phosphatidylinositol-3-kinase/AKT pathways. Here, we demonstrate that miR-335 directly targets and downregulates genes in the TGF-β non-canonical pathways, including the Rho-associated coiled-coil containing protein (ROCK1) and MAPK1, resulting in reduced phosphorylation of downstream pathway members. Specifically, inhibition of ROCK1 and MAPK1 reduces phosphorylation levels of the motor protein myosin light chain (MLC) leading to a significant inhibition of the invasive and migratory potential of neuroblastoma cells. Additionally, miR-335 targets the leucine-rich alpha-2-glycoprotein 1 (LRG1) messenger RNA, which similarly results in a significant reduction in the phosphorylation status of MLC and a decrease in neuroblastoma cell migration and invasion. Thus, we link LRG1 to the migratory machinery of the cell, altering its activity presumably by exerting its effect within the non-canonical TGF-β pathway. Moreover, we demonstrate that the MYCN transcription factor, whose coding sequence is highly amplified in a particularly clinically aggressive neuroblastoma tumor subtype, directly binds to a region immediately upstream of the miR-335 transcriptional start site, resulting in transcriptional repression. We conclude that MYCN contributes to neuroblastoma cell migration and invasion, by directly downregulating miR-335, resulting in the upregulation of the TGF-β signaling pathway members ROCK1, MAPK1 and putative member LRG1, which positively promote this process. Our results provide novel insight into the direct regulation of TGF-β non-canonical signaling by miR-335, which in turn is downregulated by MYCN. PMID:22382496

Mediation of mouse natural cytotoxic activity by tumour necrosis factor

NASA Astrophysics Data System (ADS)

Ortaldo, John R.; Mason, Llewellyn H.; Mathieson, Bonnie J.; Liang, Shu-Mei; Flick, David A.; Herberman, Ronald B.

1986-06-01

Natural cell-mediated cytotoxic activity in the mouse has been associated with two types of effector cells, the natural killer (NK) cell and the natural cytotoxic (NC) cell, which seem to differ with regard to their patterns of target selectivity, cell surface characteristics and susceptibility to regulatory factors1. During studies on the mechanism of action of cytotoxic molecules, it became evident that WEHI-164, the prototype NC target cell, was highly susceptible to direct lysis by both human and mouse recombinant tumour necrosis factor (TNF). Here we show that NC, but not NK activity mediated by normal splenocytes, is abrogated by rabbit antibodies to recombinant and natural TNF, respectively. Thus, the cell-mediated activity defined as NC is due to release of TNF by normal spleen cells and does not represent a unique natural effector mechanism.

Ethanol does not inhibit the adhesive activity of Drosophila neuroglian or human L1 in Drosophila S2 tissue culture cells.

PubMed

Vallejo, Y; Hortsch, M; Dubreuil, R R

1997-05-02

Members of the L1 family of homophilic neural cell adhesion molecules are thought to play an important role in nervous system development and function. It is also suggested that L1 is a direct target of ethanol in fetal alcohol syndrome, since ethanol inhibits the aggregation of cultured cells expressing L1 (Ramanathan, R., Wilkemeyer, M. F., Mittel, B., Perides, G., and Charness, M. E. (1996) J. Cell Biol. 133, 381-390). If ethanol acts directly on the homophilic adhesive function of the L1 molecule, then inhibition of aggregation by ethanol should be observed in any cell type that expresses L1. Here we examined the effect of physiologically relevant concentrations of ethanol on the aggregation of Drosophila S2 cells that expressed either neuroglian (the Drosophila homolog of L1) or human L1. The aggregation of these S2 cells is known to be solely dependent on the homophilic interactions between L1 or neuroglian molecules. Neither cell adhesion molecule was affected when cell aggregation assays were carried out in the presence of >/=38 mM ethanol. The recruitment of membrane skeleton assembly at sites of cell-cell contact (a transmembrane signaling function of human L1) was also unaffected by the presence of ethanol. Thus the previously described inhibition of cell adhesion by ethanol in L1-expressing cells cannot be explained by a simple direct effect on the adhesive activity of L1 family members.

Tre1 GPCR initiates germ cell transepithelial migration by regulating Drosophila melanogaster E-cadherin

PubMed Central

Kunwar, Prabhat S.; Sano, Hiroko; Renault, Andrew D.; Barbosa, Vitor; Fuse, Naoyuki; Lehmann, Ruth

2008-01-01

Despite significant progress in identifying the guidance pathways that control cell migration, how a cell starts to move within an intact organism, acquires motility, and loses contact with its neighbors is poorly understood. We show that activation of the G protein–coupled receptor (GPCR) trapped in endoderm 1 (Tre1) directs the redistribution of the G protein Gβ as well as adherens junction proteins and Rho guanosine triphosphatase from the cell periphery to the lagging tail of germ cells at the onset of Drosophila melanogaster germ cell migration. Subsequently, Tre1 activity triggers germ cell dispersal and orients them toward the midgut for directed transepithelial migration. A transition toward invasive migration is also a prerequisite for metastasis formation, which often correlates with down-regulation of adhesion proteins. We show that uniform down-regulation of E-cadherin causes germ cell dispersal but is not sufficient for transepithelial migration in the absence of Tre1. Our findings therefore suggest a new mechanism for GPCR function that links cell polarity, modulation of cell adhesion, and invasion. PMID:18824569

Macrophages inhibit human osteosarcoma cell growth after activation with the bacterial cell wall derivative liposomal muramyl tripeptide in combination with interferon-γ.

PubMed

Pahl, Jens H W; Kwappenberg, Kitty M C; Varypataki, Eleni M; Santos, Susy J; Kuijjer, Marieke L; Mohamed, Susan; Wijnen, Juul T; van Tol, Maarten J D; Cleton-Jansen, Anne-Marie; Egeler, R Maarten; Jiskoot, Wim; Lankester, Arjan C; Schilham, Marco W

2014-03-10

In osteosarcoma, the presence of tumor-infiltrating macrophages positively correlates with patient survival in contrast to the negative effect of tumor-associated macrophages in patients with other tumors. Liposome-encapsulated muramyl tripeptide (L-MTP-PE) has been introduced in the treatment of osteosarcoma patients, which may enhance the potential anti-tumor activity of macrophages. Direct anti-tumor activity of human macrophages against human osteosarcoma cells has not been described so far. Hence, we assessed osteosarcoma cell growth after co-culture with human macrophages. Monocyte-derived M1-like and M2-like macrophages were polarized with LPS + IFN-γ, L-MTP-PE +/- IFN-γ or IL-10 and incubated with osteosarcoma cells. Two days later, viable tumor cell numbers were analyzed. Antibody-dependent effects were investigated using the therapeutic anti-EGFR antibody cetuximab. M1-like macrophages inhibited osteosarcoma cell growth when activated with LPS + IFN-γ. Likewise, stimulation of M1-like macrophages with liposomal muramyl tripeptide (L-MTP-PE) inhibited tumor growth, but only when combined with IFN-γ. Addition of the tumor-reactive anti-EGFR antibody cetuximab did not further improve the anti-tumor activity of activated M1-like macrophages. The inhibition was mediated by supernatants of activated M1-like macrophages, containing TNF-α and IL-1β. However, specific blockage of these cytokines, nitric oxide or reactive oxygen species did not inhibit the anti-tumor effect, suggesting the involvement of other soluble factors released upon macrophage activation. While LPS + IFN-γ-activated M2-like macrophages had low anti-tumor activity, IL-10-polarized M2-like macrophages were able to reduce osteosarcoma cell growth in the presence of the anti-EGFR cetuximab involving antibody-dependent tumor cell phagocytosis. This study demonstrates that human macrophages can be induced to exert direct anti-tumor activity against osteosarcoma cells. Our observation that the induction of macrophage anti-tumor activity by L-MTP-PE required IFN-γ may be of relevance for the optimization of L-MTP-PE therapy in osteosarcoma patients.

Direct cell-cell contact activates SigM to express the ESX-4 secretion system in Mycobacterium smegmatis.

PubMed

Clark, Ryan R; Judd, Julius; Lasek-Nesselquist, Erica; Montgomery, Sarah A; Hoffmann, Jennifer G; Derbyshire, Keith M; Gray, Todd A

2018-06-25

Conjugal cell-cell contact between strains of Mycobacterium smegmatis induces the esxUT transcript, which encodes the putative primary substrates of the ESAT-6 secretion system 4 (ESX-4) secretion system. This recipient response was required for conjugal transfer of chromosomal DNA from the donor strain. Here we show that the extracytoplasmic σ factor, SigM, is a cell contact-dependent activator of ESX-4 expression and is required for conjugal transfer of DNA in the recipient strain. The SigM regulon includes genes outside the seven-gene core esx4 locus that we show are also required for conjugation, and we show that some of these SigM-induced proteins likely function through ESX-4. A fluorescent reporter revealed that SigM is specifically activated in recipient cells in direct contact with donor cells. Coculture RNA-seq experiments indicated that SigM regulon induction occurred early and before transconjugants are detected. This work supports a model wherein donor contact with the recipient cell surface inactivates the transmembrane anti-SigM, thereby releasing SigM. Free SigM induces an extended ESX-4 secretion system, resulting in changes that facilitate chromosomal transfer. The contact-dependent inactivation of an extracytoplasmic σ-factor that tightly controls ESX-4 activity suggests a mechanism dedicated to detect, and appropriately respond to, external stimuli from mycobacteria.

A bioluminescent caspase-1 activity assay rapidly monitors inflammasome activation in cells.

PubMed

O'Brien, Martha; Moehring, Danielle; Muñoz-Planillo, Raúl; Núñez, Gabriel; Callaway, Justin; Ting, Jenny; Scurria, Mike; Ugo, Tim; Bernad, Laurent; Cali, James; Lazar, Dan

2017-08-01

Inflammasomes are protein complexes induced by diverse inflammatory stimuli that activate caspase-1, resulting in the processing and release of cytokines, IL-1β and IL-18, and pyroptosis, an immunogenic form of cell death. To provide a homogeneous method for detecting caspase-1 activity, we developed a bioluminescent, plate-based assay that combines a substrate, Z-WEHD-aminoluciferin, with a thermostable luciferase in an optimized lytic reagent added directly to cultured cells. Assay specificity for caspase-1 is conferred by inclusion of a proteasome inhibitor in the lytic reagent and by use of a caspase-1 inhibitor to confirm activity. This approach enables a specific and rapid determination of caspase-1 activation. Caspase-1 activity is stable in the reagent thereby providing assay convenience and flexibility. Using this assay system, caspase-1 activation has been determined in THP-1 cells following treatment with α-hemolysin, LPS, nigericin, gramicidin, MSU, R848, Pam3CSK4, and flagellin. Caspase-1 activation has also been demonstrated in treated J774A.1 mouse macrophages, bone marrow-derived macrophages (BMDMs) from mice, as well as in human primary monocytes. Caspase-1 activity was not detected in treated BMDMs derived from Casp1 -/- mice, further confirming the specificity of the assay. Caspase-1 activity can be measured directly in cultured cells using the lytic reagent, or caspase-1 activity released into medium can be monitored by assay of transferred supernatant. The caspase-1 assay can be multiplexed with other assays to monitor additional parameters from the same cells, such as IL-1β release or cell death. The caspase-1 assay in combination with a sensitive real-time monitor of cell death allows one to accurately establish pyroptosis. This assay system provides a rapid, convenient, and flexible method to specifically and quantitatively monitor caspase-1 activation in cells in a plate-based format. This will allow a more efficient and effective assessment of inflammasome activation as well as enable high-throughput screening for inflammasome modulators. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

A BMP7 Variant Inhibits Tumor Angiogenesis In Vitro and In Vivo through Direct Modulation of Endothelial Cell Biology.

PubMed

Tate, Courtney M; Mc Entire, Jacquelyn; Pallini, Roberto; Vakana, Eliza; Wyss, Lisa; Blosser, Wayne; Ricci-Vitiani, Lucia; D'Alessandris, Quintino Giorgio; Morgante, Liliana; Giannetti, Stefano; Larocca, Luigi Maria; Todaro, Matilde; Benfante, Antonina; Colorito, Maria Luisa; Stassi, Giorgio; De Maria, Ruggero; Rowlinson, Scott; Stancato, Louis

2015-01-01

Bone morphogenetic proteins (BMPs), members of the TGF-β superfamily, have numerous biological activities including control of growth, differentiation, and vascular development. Using an in vitro co-culture endothelial cord formation assay, we investigated the role of a BMP7 variant (BMP7v) in VEGF, bFGF, and tumor-driven angiogenesis. BMP7v treatment led to disruption of neo-endothelial cord formation and regression of existing VEGF and bFGF cords in vitro. Using a series of tumor cell models capable of driving angiogenesis in vitro, BMP7v treatment completely blocked cord formation. Pre-treatment of endothelial cells with BMP7v significantly reduced their cord forming ability, indicating a direct effect on endothelial cell function. BMP7v activated the canonical SMAD signaling pathway in endothelial cells but targeted gene knockdown using shRNA directed against SMAD4 suggests this pathway is not required to mediate the anti-angiogenic effect. In contrast to SMAD activation, BMP7v selectively decreased ERK and AKT activation, significantly decreased endothelial cell migration and down-regulated expression of critical RTKs involved in VEGF and FGF angiogenic signaling, VEGFR2 and FGFR1 respectively. Importantly, in an in vivo angiogenic plug assay that serves as a measurement of angiogenesis, BMP7v significantly decreased hemoglobin content indicating inhibition of neoangiogenesis. In addition, BMP7v significantly decreased angiogenesis in glioblastoma stem-like cell (GSLC) Matrigel plugs and significantly impaired in vivo growth of a GSLC xenograft with a concomitant reduction in microvessel density. These data support BMP7v as a potent anti-angiogenic molecule that is effective in the context of tumor angiogenesis.

Direct activation of Ca2+ and voltage-gated potassium channels of large conductance by anandamide in endothelial cells does not support the presence of endothelial atypical cannabinoid receptor.

PubMed

Bondarenko, Alexander I; Panasiuk, Olga; Okhai, Iryna; Montecucco, Fabrizio; Brandt, Karim J; Mach, Francois

2017-06-15

Endocannabinoid anandamide induces endothelium-dependent relaxation commonly attributed to stimulation of the G-protein coupled endothelial anandamide receptor. The study addressed the receptor-independent effect of anandamide on large conductance Ca 2+ -dependent K + channels expressed in endothelial cell line EA.hy926. Under resting conditions, 10µM anandamide did not significantly influence the resting membrane potential. In a Ca 2+ -free solution the cells were depolarized by ~10mV. Further administration of 10µM anandamide hyperpolarized the cells by ~8mV. In voltage-clamp mode, anandamide elicited the outwardly rectifying whole-cell current sensitive to paxilline but insensitive to GDPβS, a G-protein inhibitor. Administration of 70µM Mn 2+ , an agent used to promote integrin clustering, reversibly stimulated whole-cell current, but failed to further facilitate the anandamide-stimulated current. In an inside-out configuration, anandamide (0.1-30µM) facilitated single BK Ca channel activity in a concentration-dependent manner within a physiological Ca 2+ range and a wide range of voltages, mainly by reducing mean closed time. The effect is essentially eliminated following chelation of Ca 2+ from the cytosolic face and pre-exposure to cholesterol-reducing agent methyl-β-cyclodextrin. O-1918 (3µM), a cannabidiol analog used as a selective antagonist of endothelial anandamide receptor, reduced BK Ca channel activity in inside-out patches. These results do not support the existence of endothelial cannabinoid receptor and indicate that anandamide acts as a direct BK Ca opener. The action does not require cell integrity or integrins and is caused by direct modification of BK Ca channel activity. Copyright © 2017 Elsevier B.V. All rights reserved.

TiO2-Photoanode-Assisted Direct-Solar-Energy Harvesting and Storage in a Solar-Powered Redox Cell Using Halides as Active Materials.

PubMed

Zhang, Shun; Chen, Chen; Zhou, Yangen; Qian, Yumin; Ye, Jing; Xiong, Shiyun; Zhao, Yu; Zhang, Xiaohong

2018-06-27

The rapid deployment of renewable energy is resulting in significant energy security, climate change mitigation, and economic benefits. We demonstrate here the direct solar-energy harvesting and storage in a rechargeable solar-powered redox cell, which can be charged solely by solar irradiation. The cell follows a conventional redox-flow cell design with one integrated TiO 2 photoanode in the cathode side. Direct charging of the cell by solar irradiation results in the conversion of solar energy in to chemical energy. Whereas discharging the cell leads to the release of chemical energy in the form of electricity. The cell integrates energy conversion and storage processes in a single device, making the solar energy directly and efficiently dispatchable. When using redox couples of Br 2 /Br - and I 3 - /I - in the cathode side and anode side, respectively, the cell can be directly charged upon solar irradiation, yielding a discharge potential of 0.5 V with good round-trip efficiencies. This design is expected to be a potential alternative toward the development of affordable, inexhaustible, and clean solar-energy technologies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Mingshan; Jiangsu Key Laboratory of Bone Marrow Stem Cell, Xuzhou Medical College, Xuzhou, Jiangsu; Department of Hematology, Affiliated Hospital of Xuzhou Medical College, Xuzhou, Jiangsu

Constitutive NF-κB activation is required for survival of activated B cell-like subtype of diffuse large B cell lymphoma (ABC-DLBCL). However, current NF-κB targeting strategies lack cancer cell specificity. Here, we identified a novel inhibitor, piperlongumine, features direct binding to NF-κB p65 subunit and suppression of p65 nuclear import. This was accompanied by NF-κB reporter activity suppression and NF-κB target gene downregulation. Moreover, mutation of Cys{sup 38} to Ser in p65 abolished this effect of piperlongumine on inhibition of p65 nuclear import. Furthermore, we show that piperlongumine selectively inhibited proliferation and induced apoptosis of ABC-DLBCL cells. Most notably, it has beenmore » reported that piperlongumine did not affect normal cells even at high doses and was nontoxic to animals. Hence, our current study provides new insight into piperlongumine's mechanism of action and novel approach to ABC-DLBCL target therapy. - Highlights: • Current NF-κB targeting strategies lack cancer cell specificity. • Piperlongumine inhibits NF-κB p65 subunit nuclear import via directly binding to p65. • Piperlongumine selectively inhibits proliferation of ABC-DLBCL cells. • This study provides a novel approach to ABC-DLBCL target therapy.« less

Constitutive Signaling from an Engineered IL7 Receptor Promotes Durable Tumor Elimination by Tumor-Redirected T Cells.

PubMed

Shum, Thomas; Omer, Bilal; Tashiro, Haruko; Kruse, Robert L; Wagner, Dimitrios L; Parikh, Kathan; Yi, Zhongzhen; Sauer, Tim; Liu, Daofeng; Parihar, Robin; Castillo, Paul; Liu, Hao; Brenner, Malcolm K; Metelitsa, Leonid S; Gottschalk, Stephen; Rooney, Cliona M

2017-11-01

Successful adoptive T-cell immunotherapy of solid tumors will require improved expansion and cytotoxicity of tumor-directed T cells within tumors. Providing recombinant or transgenic cytokines may produce the desired benefits but is associated with significant toxicities, constraining clinical use. To circumvent this limitation, we constructed a constitutively signaling cytokine receptor, C7R, which potently triggers the IL7 signaling axis but is unresponsive to extracellular cytokine. This strategy augments modified T-cell function following antigen exposure, but avoids stimulating bystander lymphocytes. Coexpressing the C7R with a tumor-directed chimeric antigen receptor (CAR) increased T-cell proliferation, survival, and antitumor activity during repeated exposure to tumor cells, without T-cell dysfunction or autonomous T-cell growth. Furthermore, C7R-coexpressing CAR T cells were active against metastatic neuroblastoma and orthotopic glioblastoma xenograft models even at cell doses that had been ineffective without C7R support. C7R may thus be able to enhance antigen-specific T-cell therapies against cancer. Significance: The constitutively signaling C7R system developed here delivers potent IL7 stimulation to CAR T cells, increasing their persistence and antitumor activity against multiple preclinical tumor models, supporting its clinical development. Cancer Discov; 7(11); 1238-47. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 1201 . ©2017 American Association for Cancer Research.

Function of the nucleotide exchange activity of vav1 in T cell development and activation.

PubMed

Saveliev, Alexander; Vanes, Lesley; Ksionda, Olga; Rapley, Jonathan; Smerdon, Stephen J; Rittinger, Katrin; Tybulewicz, Victor L J

2009-12-15

The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal-regulated kinase and protein kinase D1, and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions.

Function of the Nucleotide Exchange Activity of Vav1 in T cell Development and Activation*

PubMed Central

Saveliev, Alexander; Vanes, Lesley; Ksionda, Olga; Rapley, Jonathan; Smerdon, Stephen J.; Rittinger, Katrin; Tybulewicz, Victor L. J.

2012-01-01

The guanine nucleotide exchange factor (GEF) Vav1 is essential for transducing T cell antigen receptor (TCR) signals and therefore plays a critical role in the development and activation of T cells. It has been presumed that the GEF activity of Vav1 is important for its function; however, there has been no direct demonstration of this. Here, we generated mice expressing enzymatically inactive, but normally folded, Vav1 protein. Analysis of these mice showed that the GEF activity of Vav1 was necessary for the selection of thymocytes and for the optimal activation of T cells, including signal transduction to Rac1, Akt, and integrins. In contrast, the GEF activity of Vav1 was not required for TCR-induced calcium flux, activation of extracellular signal–regulated kinase (ERK) and protein kinase D1 (PKD1), and cell polarization. Thus, in T cells, the GEF activity of Vav1 is essential for some, but not all, of its functions. PMID:20009105

Multi-phasic bi-directional chemotactic responses of the growth cone

PubMed Central

Naoki, Honda; Nishiyama, Makoto; Togashi, Kazunobu; Igarashi, Yasunobu; Hong, Kyonsoo; Ishii, Shin

2016-01-01

The nerve growth cone is bi-directionally attracted and repelled by the same cue molecules depending on the situations, while other non-neural chemotactic cells usually show uni-directional attraction or repulsion toward their specific cue molecules. However, how the growth cone differs from other non-neural cells remains unclear. Toward this question, we developed a theory for describing chemotactic response based on a mathematical model of intracellular signaling of activator and inhibitor. Our theory was first able to clarify the conditions of attraction and repulsion, which are determined by balance between activator and inhibitor, and the conditions of uni- and bi-directional responses, which are determined by dose-response profiles of activator and inhibitor to the guidance cue. With biologically realistic sigmoidal dose-responses, our model predicted tri-phasic turning response depending on intracellular Ca2+ level, which was then experimentally confirmed by growth cone turning assays and Ca2+ imaging. Furthermore, we took a reverse-engineering analysis to identify balanced regulation between CaMKII (activator) and PP1 (inhibitor) and then the model performance was validated by reproducing turning assays with inhibitions of CaMKII and PP1. Thus, our study implies that the balance between activator and inhibitor underlies the multi-phasic bi-directional turning response of the growth cone. PMID:27808115

Vγ9Vδ2 T cell activation by strongly agonistic nucleotidic phosphoantigens.

PubMed

Moulin, Morgane; Alguacil, Javier; Gu, Siyi; Mehtougui, Asmaa; Adams, Erin J; Peyrottes, Suzanne; Champagne, Eric

2017-12-01

Human Vγ9Vδ2 T cells can sense through their TCR tumor cells producing the weak endogenous phosphorylated antigen isopentenyl pyrophosphate (IPP), or bacterially infected cells producing the strong agonist hydroxyl dimethylallyl pyrophosphate (HDMAPP). The recognition of the phosphoantigen is dependent on its binding to the intracellular B30.2 domain of butyrophilin BTN3A1. Most studies have focused on pyrophosphate phosphoantigens. As triphosphate nucleotide derivatives are naturally co-produced with IPP and HDMAPP, we analyzed their specific properties using synthetic nucleotides derived from HDMAPP. The adenylated, thymidylated and uridylated triphosphate derivatives were found to activate directly Vγ9Vδ2 cell lines as efficiently as HDMAPP in the absence of accessory cells. These antigens were inherently resistant to terminal phosphatases, but apyrase, when added during a direct stimulation of Vγ9Vδ2 cells, abrogated their stimulating activity, indicating that their activity required transformation into strong pyrophosphate agonists by a nucleotide pyrophosphatase activity which is present in serum. Tumor cells can be sensitized with nucleotide phosphoantigens in the presence of apyrase to become stimulatory, showing that this can occur before their hydrolysis into pyrophosphates. Whereas tumors sensitized with HDMAPP rapidly lost their stimulatory activity, sensitization with nucleotide derivatives, in particular with the thymidine derivative, induced long-lasting stimulating ability. Using isothermal titration calorimetry, binding of some nucleotide derivatives to BTN3A1 intracellular domain was found to occur with an affinity similar to that of IPP, but much lower than that of HDMAPP. Thus, nucleotide phosphoantigens are precursors of pyrophosphate antigens which can deliver strong agonists intracellularly resulting in prolonged and strengthened activity.

Exosomes and their roles in immune regulation and cancer.

PubMed

Greening, David W; Gopal, Shashi K; Xu, Rong; Simpson, Richard J; Chen, Weisan

2015-04-01

Exosomes, a subset of extracellular vesicles (EVs), function as a mode of intercellular communication and molecular transfer. Exosomes facilitate the direct extracellular transfer of proteins, lipids, and miRNA/mRNA/DNAs between cells in vitro and in vivo. The immunological activities of exosomes affect immunoregulation mechanisms including modulating antigen presentation, immune activation, immune suppression, immune surveillance, and intercellular communication. Besides immune cells, cancer cells secrete immunologically active exosomes that influence both physiological and pathological processes. The observation that exosomes isolated from immune cells such as dendritic cells (DCs) modulate the immune response has enforced the way these membranous vesicles are being considered as potential immunotherapeutic reagents. Indeed, tumour- and immune cell-derived exosomes have been shown to carry tumour antigens and promote immunity, leading to eradication of established tumours by CD8(+) T cells and CD4(+) T cells, as well as directly suppressing tumour growth and resistance to malignant tumour development. Further understanding of these areas of exosome biology, and especially of molecular mechanisms involved in immune cell targeting, interaction and manipulation, is likely to provide significant insights into immunorecognition and therapeutic intervention. Here, we review the emerging roles of exosomes in immune regulation and the therapeutic potential in cancer. Copyright © 2015 Elsevier Ltd. All rights reserved.

Curcumin interacts directly with the Cysteine 259 residue of STAT3 and induces apoptosis in H-Ras transformed human mammary epithelial cells.

PubMed

Hahn, Young-Il; Kim, Su-Jung; Choi, Bu-Young; Cho, Kyung-Cho; Bandu, Raju; Kim, Kwang Pyo; Kim, Do-Hee; Kim, Wonki; Park, Joon Sung; Han, Byung Woo; Lee, Jeewoo; Na, Hye-Kyung; Cha, Young-Nam; Surh, Young-Joon

2018-04-23

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is latent but constitutively activated in many types of cancers. It is well known that STAT3 plays a key role in inflammation-associated tumorigenesis. Curcumin is an anti-inflammatory natural compound isolated from the turmeric (Curcuma longa L., Zingiberaceae) that has been extensively used in a traditional medicine over the centuries. In the present study, we have found that curcumin inhibits STAT3 signaling that is persistently overactivated in H-Ras transformed breast epithelial cells (H-Ras MCF10A). Specific cysteine residues present in STAT3 appear to be critical for the activity as well as conformation of this transcription factor. We identified the cysteine residue 259 of STAT3 as a putative site for curcumin binding. Site-directed mutation of this cysteine residue abolished curcumin-induced inactivation of STAT3 and apoptosis in H-Ras MCF10A cells. The α,β-unsaturated carbonyl moiety of curcumin appears to be essential in its binding to STAT3 in H-Ras MCF10A cells. Tetrahydrocurcumin that lacks such electrophilic moiety failed to interact with STAT3 and to induce apoptosis in the same cell line. Taken together, our findings suggest that curcumin can abrogate aberrant activation of STAT3 through direct interaction, thereby inhibiting STAT3-mediated mammary carcinogenesis.

Highly water-dispersible, mixed ionic-electronic conducting, polymer acid-doped polyanilines as ionomers for direct methanol fuel cells.

PubMed

Murthy, Arun; Manthiram, Arumugam

2011-06-28

Highly water-dispersible polymer acid-doped polyanilines have been synthesized and evaluated as an alternative for expensive Nafion ionomers in the anode of direct methanol fuel cells (DMFC). These polymers as ionomers lead to higher performance in single cell DMFC compared to Nafion ionomers due to mixed ionic-electronic conduction, water dispersibility, and co-catalytic activity. This journal is © The Royal Society of Chemistry 2011

Multiphysics of bone remodeling: A 2D mesoscale activation simulation.

PubMed

Spingarn, C; Wagner, D; Rémond, Y; George, D

2017-01-01

In this work, we present an evolutive trabecular model for bone remodeling based on a boundary detection algorithm accounting for both biology and applied mechanical forces, known to be an important factor in bone evolution. A finite element (FE) numerical model using the Abaqus/Standard® software was used with a UMAT subroutine to solve the governing coupled mechanical-biological non-linear differential equations of the bone evolution model. The simulations present cell activation on a simplified trabeculae configuration organization with trabecular thickness of 200µm. For this activation process, the results confirm that the trabeculae are mainly oriented in the active direction of the principal mechanical stresses and according to the principal applied mechanical load directions. The trabeculae surface activation is clearly identified and can provide understanding of the different bone cell activations in more complex geometries and load conditions.

Prostaglandin E2 activates channel-mediated calcium entry in human erythrocytes: an indication for a blood clot formation supporting process.

PubMed

Kaestner, Lars; Tabellion, Wiebke; Lipp, Peter; Bernhardt, Ingolf

2004-12-01

Prostaglandin E(2) (PGE(2)) is released from platelets when they are activated. Using fluorescence imaging and the patch-clamp technique, we provide evidence that PGE(2) at physiological concentrations (10(-10) M) activates calcium rises mediated by calcium influx through a non-selective cation-channel in human red blood cells. The extent of calcium increase varied between cells with a total of 45% of the cells responding. It is well known that calcium increases elicited the calcium-activated potassium channel (Gardos channel) in the red cell membrane. Previously, it was shown that the Gardos channel activation results in potassium efflux and shrinkage of the cells. Therefore, we conclude that the PGE(2) responses of red blood cells described here reveal a direct and active participation of erythrocytes in blood clot formation.

New Electrocatalysts for Direct Oxidation of Organic Fuels

DTIC Science & Technology

2009-06-12

ambient temperature . [28,29] While 13C-NMR provides information on the nature of the adsorbate and the electronic environment at the active surface of...our study to unsupported electrocatalysts that are of greater interest for direct methanol and direct ethanol fuel cells. We have developed a new in...coverage, and type of surface site on the relative adsorption rate and electrooxidative activity of the electrocatalyst. Figure 2 shows sample

Comparative effects of dietary flavanols on antioxidant defences and their response to oxidant-induced stress on Caco2 cells.

PubMed

Rodríguez-Ramiro, Ildefonso; Martín, María Angeles; Ramos, Sonia; Bravo, Laura; Goya, Luis

2011-08-01

Flavanols are an important fraction of our diet both for their antioxidant capacity and because they are constituents of greatly accepted foodstuffs such as tea, wine and cocoa. In addition to their antioxidant activity by directly scavenging intracellular reactive oxygen species (ROS), flavanols have been recently shown to enhance protective enzymes. The objective was to evaluate the antioxidant response of colon-derived Caco2 cells to dietary flavanols. Four representative flavanols were selected: epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin-3-gallate (EGCG) and procyanidin B2 (PB2). Cell viability, concentration of ROS and reduced glutathione (GSH), and activity of antioxidant/detoxification enzymes and caspase 3 were determined. Treatment of Caco2 cells with flavanols decreased ROS production but did not affect GSH content. ECG induced glutathione peroxidase (GPx), whereas PB2 evoked a dose-dependent increase in GPx, glutathione reductase and glutathione-S-transferase. Enhancement of the antioxidant defences implies an improved cell response to an oxidative challenge. Hence, Caco2 cells treated 20 h with the flavanols, especially PB2, and then submitted to an oxidative stress induced by a pro-oxidant, tert-butyl-hydroperoxide, showed a reduced ROS production, restricted activation of caspase 3 and higher viability than cells plainly submitted to the stressor. Flavanols protect Caco2 cells against an induced oxidative stress and subsequent cellular death by reducing ROS production and preventing caspase-3 activation. In particular, PB2 increases the activity of antioxidant/detoxification enzymes and thus protects Caco2 cells by directly counteracting free radicals and also by activating the antioxidant defence system.

Polymer microarray technology for stem cell engineering

PubMed Central

Coyle, Robert; Jia, Jia; Mei, Ying

2015-01-01

Stem cells hold remarkable promise for applications in tissue engineering and disease modeling. During the past decade, significant progress has been made in developing soluble factors (e.g., small molecules and growth factors) to direct stem cells into a desired phenotype. However, the current lack of suitable synthetic materials to regulate stem cell activity has limited the realization of the enormous potential of stem cells. This can be attributed to a large number of materials properties (e.g., chemical structures and physical properties of materials) that can affect stem cell fate. This makes it challenging to design biomaterials to direct stem cell behavior. To address this, polymer microarray technology has been developed to rapidly identify materials for a variety of stem cell applications. In this article, we summarize recent developments in polymer array technology and their applications in stem cell engineering. Statement of significance Stem cells hold remarkable promise for applications in tissue engineering and disease modeling. In the last decade, significant progress has been made in developing chemically defined media to direct stem cells into a desired phenotype. However, the current lack of the suitable synthetic materials to regulate stem cell activities has been limiting the realization of the potential of stem cells. This can be attributed to the number of variables in material properties (e.g., chemical structures and physical properties) that can affect stem cells. Polymer microarray technology has shown to be a powerful tool to rapidly identify materials for a variety of stem cell applications. Here we summarize recent developments in polymer array technology and their applications in stem cell engineering. PMID:26497624

Direct trans-activation of the human cyclin D2 gene by the oncogene product Tax of human T-cell leukemia virus type I.

PubMed

Huang, Y; Ohtani, K; Iwanaga, R; Matsumura, Y; Nakamura, M

2001-03-01

Cyclins are one of the pivotal determinants regulating cell cycle progression. We previously reported that the trans-activator Tax of human T-cell leukemia virus type I (HTLV-I) induces endogenous cyclin D2 expression along with cell cycle progression in a resting human T-cell line, Kit 225, suggesting a role of cyclin D2 in Tax-mediated cell cycle progression. The cyclin D2 gene has a typical E2F binding element, raising the possibility that induction of cyclin D2 expression is a consequence of cell cycle progression. In this study, we examined the role and molecular mechanism of induction of the endogenous human cyclin D2 gene by Tax. Introduction of p19(INK4d), a cyclin dependent kinase (CDK) inhibitor of the INK4 family specific for D-type CDK, inhibited Tax-mediated activation of E2F, indicating requirement of D-type CDK in Tax-mediated activation of E2F. Previously indicated E2F binding element and two NF-kappaB-like binding elements in the 1.6 kbp cyclin D2 promoter fragment had little, if any, effect on responsiveness to Tax. We found that trans-activation of the cyclin D2 promoter by Tax was mainly mediated by a newly identified NF-kappaB-like element with auxiliary contribution of a CRE-like element residing in sequences downstream of -444 which were by themselves sufficient for trans-activation by Tax. These results indicate that Tax directly trans-activates the cyclin D2 gene, resulting in growth promotion and perhaps leukemogenesis through activation of D-type CDK.

The homeobox gene mirror links EGF signalling to embryonic dorso-ventral axis formation through notch activation.

PubMed

Jordan, K C; Clegg, N J; Blasi, J A; Morimoto, A M; Sen, J; Stein, D; McNeill, H; Deng, W M; Tworoger, M; Ruohola-Baker, H

2000-04-01

Recent studies in vertebrates and Drosophila melanogaster have revealed that Fringe-mediated activation of the Notch pathway has a role in patterning cell layers during organogenesis. In these processes, a homeobox-containing transcription factor is responsible for spatially regulating fringe (fng) expression and thus directing activation of the Notch pathway along the fng expression border. Here we show that this may be a general mechanism for patterning epithelial cell layers. At three stages in Drosophila oogenesis, mirror (mirr) and fng have complementary expression patterns in the follicle-cell epithelial layer, and at all three stages loss of mirr enlarges, and ectopic expression of mirr restricts, fng expression, with consequences for follicle-cell patterning. These morphological changes are similar to those caused by Notch mutations. Ectopic expression of mirr in the posterior follicle cells induces a stripe of rhomboid (rho) expression and represses pipe (pip), a gene with a role in the establishment of the dorsal-ventral axis, at a distance. Ectopic Notch activation has a similar long-range effect on pip. Our results suggest that Mirror and Notch induce secretion of diffusible morphogens and we have identified TGF-beta (encoded by dpp) as such a molecule in germarium. We also found that mirr expression in dorsal follicle cells is induced by the EGF-receptor (EGFR) pathway and that mirr then represses pip expression in all but the ventral follicle cells, connecting EGFR activation in the dorsal follicle cells to repression of pip in the dorsal and lateral follicle cells. Our results suggest that the differentiation of ventral follicle cells is not a direct consequence of germline signalling, but depends on long-range signals from dorsal follicle cells, and provide a link between early and late events in Drosophila embryonic dorsal-ventral axis formation.

Direct Activation of NADPH Oxidase 2 by 2-Deoxyribose-1-Phosphate Triggers Nuclear Factor Kappa B-Dependent Angiogenesis

PubMed Central

Vara, Dina; Watt, Joanna M.; Fortunato, Tiago M.; Mellor, Harry; Burgess, Matthew; Wicks, Kate; Mace, Kimberly; Reeksting, Shaun; Lubben, Anneke; Wheeler-Jones, Caroline P.D.

2018-01-01

Abstract Aims: Deoxyribose-1-phosphate (dRP) is a proangiogenic paracrine stimulus released by cancer cells, platelets, and macrophages and acting on endothelial cells. The objective of this study was to clarify how dRP stimulates angiogenic responses in human endothelial cells. Results: Live cell imaging, electron paramagnetic resonance, pull-down of dRP-interacting proteins, followed by immunoblotting, gene silencing of different NADPH oxidases (NOXs), and their regulatory cosubunits by small interfering RNA (siRNA) transfection, and experiments with inhibitors of the sugar transporter glucose transporter 1 (GLUT1) were utilized to demonstrate that dRP acts intracellularly by directly activating the endothelial NOX2 complex, but not NOX4. Increased reactive oxygen species generation in response to NOX2 activity leads to redox-dependent activation of the transcription factor nuclear factor kappa B (NF-κB), which, in turn, induces vascular endothelial growth factor receptor 2 (VEGFR2) upregulation. Using endothelial tube formation assays, gene silencing by siRNA, and antibody-based receptor inhibition, we demonstrate that the activation of NF-κB and VEGFR2 is necessary for the angiogenic responses elicited by dRP. The upregulation of VEGFR2 and NOX2-dependent stimulation of angiogenesis by dRP were confirmed in excisional wound and Matrigel plug vascularization assays in vivo using NOX2−/− mice. Innovation: For the first time, we demonstrate that dRP acts intracellularly and stimulates superoxide anion generation by direct binding and activation of the NOX2 enzymatic complex. Conclusions: This study describes a novel molecular mechanism underlying the proangiogenic activity of dRP, which involves the sequential activation of NOX2 and NF-κB and upregulation of VEGFR2. Antioxid. Redox Signal. 28, 110–130. PMID:28793782

Polyclonal activation of human lymphocytes in vitro-II. Reappraisal of T and B cell-specific mitogens.

PubMed

Dosch, H M; Schuurman, R K; Gelfand, E W

1980-08-01

The capacity of the T cell mitogens phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), and Staphylococcus protein A (SpA) to induce B cell proliferation and differentiation was compared with the B cell mitogen, formalinized Staphylococcus aureus (STA). Lymphocyte subpopulations from normal donors and patients with various immunodeficiency diseases were studied. In the presence of the T cell mitogens, irradiated T cells were capable of providing a helper cell activity that enabled co-cultured B lymphocytes to proliferate in response to these mitogens and to differentiate into IgM-secreting (direct) hemolytic plaque-forming cells (PFC). In the PFC response, radioresistant T-helper and radiosensitive T-suppressor cell activities could be demonstrated. T-suppressor cell activity outweighed helper activity only in nonirradiated co-cultures stimulated with Con A. Patients with severe combined immunodeficiency lacked mitogen-induced helper T cells, whereas patients with various forms of humoral immune deficiency were normal in this respect. These findings and the tissue distribution of the helper activity is aquired early in post-thymic T cell differentiation. The data suggest that experiments with cell lineage-specific lymphocyte mitogens should be considered in the context of more complex cell-cell interactions.

Mechanisms of integrin-vascular endothelial growth factor receptor cross-activation in angiogenesis.

PubMed

Mahabeleshwar, Ganapati H; Feng, Weiyi; Reddy, Kumar; Plow, Edward F; Byzova, Tatiana V

2007-09-14

The functional responses of endothelial cells are dependent on signaling from peptide growth factors and the cellular adhesion receptors, integrins. These include cell adhesion, migration, and proliferation, which, in turn, are essential for more complex processes such as formation of the endothelial tube network during angiogenesis. This study identifies the molecular requirements for the cross-activation between beta3 integrin and tyrosine kinase receptor 2 for vascular endothelial growth factor (VEGF) receptor (VEGFR-2) on endothelium. The relationship between VEGFR-2 and beta3 integrin appears to be synergistic, because VEGFR-2 activation induces beta3 integrin tyrosine phosphorylation, which, in turn, is crucial for VEGF-induced tyrosine phosphorylation of VEGFR-2. We demonstrate here that adhesion- and growth factor-induced beta3 integrin tyrosine phosphorylation are directly mediated by c-Src. VEGF-stimulated recruitment and activation of c-Src and subsequent beta3 integrin tyrosine phosphorylation are critical for interaction between VEGFR-2 and beta3 integrin. Moreover, c-Src mediates growth factor-induced beta3 integrin activation, ligand binding, beta3 integrin-dependent cell adhesion, directional migration of endothelial cells, and initiation of angiogenic programming in endothelial cells. Thus, the present study determines the molecular mechanisms and consequences of the synergism between 2 cell surface receptor systems, growth factor receptor and integrins, and opens new avenues for the development of pro- and antiangiogenic strategies.

Proanthocyanidins from the bark of Metasequoia glyptostroboides ameliorate allergic contact dermatitis through directly inhibiting T cells activation and Th1/Th17 responses.

PubMed

Chen, Fengyang; Ye, Xiaodi; Yang, Yadong; Teng, Tianli; Li, Xiaoyu; Xu, Shifang; Ye, Yiping

2015-04-15

The leaves and bark of Metasequoia glyptostroboides are used as anti-microbic, analgesic and anti-inflammatory drug for dermatic diseases in Chinese folk medicine. However, the pharmacological effects and material basis responsible for the therapeutic use of this herb have not yet been well studied. The objectives of this study were to evaluate the anti-inflammatory effects of the proanthocyanidin fraction from the bark of M. glyptostroboides (MGEB) and to elucidate its immunological mechanisms. The anti-inflammatory activity of MGEB was evaluated using 2,4-dinitrofluorobenzene (DNFB)-induced allergic contact dermatitis (ACD) in mice. Its potential mechanisms were further investigated by determining its effects on Con A-induced T cell activation and Th1/Th17 responses in vitro. Both intraperitoneal injection and oral administration of MGEB significantly reduced the ear swelling in DNFB-induced ACD mice. MGEB inhibited Con A-induced proliferation and the expression levels of cell surface molecules CD69 and CD25 of T cells in vitro. MGEB also significantly decreased the production of Th1/Th17 specific cytokines (IL-2, IFN-γ and IL-17) and down-regulated their mRNA expression levels in activated T-cells. MGEB could ameliorate ACD, at least in part, through directly inhibiting T cells activation and Th1/Th17 responses. Copyright © 2015 Elsevier GmbH. All rights reserved.

Synergetic effect of yeast cell-surface expression of cellulase and expansin-like protein on direct ethanol production from cellulose

PubMed Central

2013-01-01

Background Numerous studies have examined the direct fermentation of cellulosic materials by cellulase-expressing yeast; however, ethanol productivity in these systems has not yet reached an industrial level. Certain microorganisms, such as the cellulolytic fungus Trichoderma reesei, produce expansin-like proteins, which have a cellulose-loosening effect that may increase the breakdown of cellulose. Here, to improve the direct conversion of cellulose to ethanol, yeast Saccharomyces cerevisiae co-displaying cellulase and expansin-like protein on the cell surface were constructed and examined for direct ethanol fermentation performance. Results The cellulase and expansin-like protein co-expressing strain showed 246 mU/g-wet cell of phosphoric acid swollen cellulose (PASC) degradation activity, which corresponded to 2.9-fold higher activity than that of a cellulase-expressing strain. This result clearly demonstrated that yeast cell-surface expressed cellulase and expansin-like protein act synergistically to breakdown cellulose. In fermentation experiments examining direct ethanol production from PASC, the cellulase and expansin-like protein co-expressing strain produced 3.4 g/L ethanol after 96 h of fermentation, a concentration that was 1.4-fold higher than that achieved by the cellulase-expressing strain (2.5 g/L). Conclusions The PASC degradation and fermentation ability of an engineered yeast strain was markedly improved by co-expressing cellulase and expansin-like protein on the cell surface. To our knowledge, this is the first report to demonstrate the synergetic effect of co-expressing cellulase and expansin-like protein on a yeast cell surface, which may be a promising strategy for constructing direct ethanol fermenting yeast from cellulose. PMID:23835302

Eukaryotic Chemotaxis: A Network of Signaling Pathways Controls Motility, Directional Sensing, and Polarity

PubMed Central

Swaney, Kristen F.; Huang, Chuan-Hsiang; Devreotes, Peter N.

2015-01-01

Chemotaxis, the directed migration of cells in chemical gradients, is a vital process in normal physiology and in the pathogenesis of many diseases. Chemotactic cells display motility, directional sensing, and polarity. Motility refers to the random extension of pseudopodia, which may be driven by spontaneous actin waves that propagate through the cytoskeleton. Directional sensing is mediated by a system that detects temporal and spatial stimuli and biases motility toward the gradient. Polarity gives cells morphologically and functionally distinct leading and lagging edges by relocating proteins or their activities selectively to the poles. By exploiting the genetic advantages of Dictyostelium, investigators are working out the complex network of interactions between the proteins that have been implicated in the chemotactic processes of motility, directional sensing, and polarity. PMID:20192768

Inflammasome - activated gasdermin D causes pyroptosis by forming membrane pores

PubMed Central

Liu, Xing; Zhang, Zhibin; Ruan, Jianbin; Pan, Youdong; Magupalli, Venkat Giri; Wu, Hao; Lieberman, Judy

2017-01-01

Inflammatory caspases (caspases 1, 4, 5 and 11) are activated in response to microbial infection and danger signals. When activated, they cleave mouse and human gasdermin D (GSDMD) after Asp276 and Asp275, respectively, to generate an N-terminal cleavage product (GSDMD-NT) that triggers inflammatory death (pyroptosis) and release of inflammatory cytokines such as interleukin-1β1,2. Cleavage removes the C-terminal fragment (GSDMD-CT), which is thought to fold back on GSDMD-NT to inhibit its activation. However, how GSDMD-NT causes cell death is unknown. Here we show that GSDMD-NT oligomerizes in membranes to form pores that are visible by electron microscopy. GSDMD-NT binds to phosphatidylinositol phosphates and phosphatidylserine (restricted to the cell membrane inner leaflet) and cardiolipin (present in the inner and outer leaflets of bacterial membranes). Mutation of four evolutionarily conserved basic residues blocks GSDMD-NT oligomerization, membrane binding, pore formation and pyroptosis. Because of its lipid-binding preferences, GSDMD-NT kills from within the cell, but does not harm neighbouring mammalian cells when it is released during pyroptosis. GSDMD-NT also kills cell-free bacteria in vitro and may have a direct bactericidal effect within the cytosol of host cells, but the importance of direct bacterial killing in controlling in vivo infection remains to be determined. PMID:27383986

Inflammasome-activated gasdermin D causes pyroptosis by forming membrane pores.

PubMed

Liu, Xing; Zhang, Zhibin; Ruan, Jianbin; Pan, Youdong; Magupalli, Venkat Giri; Wu, Hao; Lieberman, Judy

2016-07-07

Inflammatory caspases (caspases 1, 4, 5 and 11) are activated in response to microbial infection and danger signals. When activated, they cleave mouse and human gasdermin D (GSDMD) after Asp276 and Asp275, respectively, to generate an N-terminal cleavage product (GSDMD-NT) that triggers inflammatory death (pyroptosis) and release of inflammatory cytokines such as interleukin-1β. Cleavage removes the C-terminal fragment (GSDMD-CT), which is thought to fold back on GSDMD-NT to inhibit its activation. However, how GSDMD-NT causes cell death is unknown. Here we show that GSDMD-NT oligomerizes in membranes to form pores that are visible by electron microscopy. GSDMD-NT binds to phosphatidylinositol phosphates and phosphatidylserine (restricted to the cell membrane inner leaflet) and cardiolipin (present in the inner and outer leaflets of bacterial membranes). Mutation of four evolutionarily conserved basic residues blocks GSDMD-NT oligomerization, membrane binding, pore formation and pyroptosis. Because of its lipid-binding preferences, GSDMD-NT kills from within the cell, but does not harm neighbouring mammalian cells when it is released during pyroptosis. GSDMD-NT also kills cell-free bacteria in vitro and may have a direct bactericidal effect within the cytosol of host cells, but the importance of direct bacterial killing in controlling in vivo infection remains to be determined.

Antibody-Directed Cytotoxic Agents: Use of Monoclonal Antibody to Direct the Action of Toxin A Chains to Colorectal Carcinoma Cells

NASA Astrophysics Data System (ADS)

Gilliland, D. Gary; Steplewski, Zenon; Collier, R. John; Mitchell, Kenneth F.; Chang, Tong H.; Koprowski, Hilary

1980-08-01

We have constructed cell-specific cytotoxic agents by covalently coupling the A chain from diphtheria toxin or ricin toxin to monoclonal antibody directed against a colorectal carcinoma tumor-associated antigen. Antibody 1083-17-1A was modified by attachment of 3-(2-pyridyldithio)propionyl or cystaminyl groups and then treated with reduced A chain to give disulfide-linked conjugates that retained the original binding specificity of the antibody moiety. The conjugates showed cytotoxic activity for colorectal carcinoma cells in culture, but were not toxic in the same concentration range for a variety of cell lines that lacked the antigen. Under defined conditions virtually 100% of antigen-bearing cultured cells were killed, whereas cells that lacked the antigen were not affected. Conjugates containing toxin A chains coupled to monoclonal antibodies may be useful in studying functions of various cell surface components and, possibly, as tumor-specific therapeutic agents.

CD4 on CD8+ T cells directly enhances effector function and is a target for HIV infection

NASA Astrophysics Data System (ADS)

Kitchen, Scott G.; Jones, Nicole R.; Laforge, Stuart; Whitmire, Jason K.; Vu, Bien-Aimee; Galic, Zoran; Brooks, David G.; Brown, Stephen J.; Kitchen, Christina M. R.; Zack, Jerome A.

2004-06-01

Costimulation of purified CD8+ T lymphocytes induces de novo expression of CD4, suggesting a previously unrecognized function for this molecule in the immune response. Here, we report that the CD4 molecule plays a direct role in CD8+ T cell function by modulating expression of IFN- and Fas ligand, two important CD8+ T cell effector molecules. CD4 expression also allows infection of CD8 cells by HIV, which results in down-regulation of the CD4 molecule and impairs the induction of IFN-, Fas ligand, and the cytotoxic responses of activated CD8+ T cells. Thus, the CD4 molecule plays a direct role in CD8 T cell function, and infection of these cells by HIV provides an additional reservoir for the virus and also may contribute to the immunodeficiency seen in HIV disease.

Membrane nanotubes facilitate long-distance interactions between natural killer cells and target cells

PubMed Central

Chauveau, Anne; Aucher, Anne; Eissmann, Philipp; Vivier, Eric; Davis, Daniel M.

2010-01-01

Membrane nanotubes are membranous tethers that physically link cell bodies over long distances. Here, we present evidence that nanotubes allow human natural killer (NK) cells to interact functionally with target cells over long distances. Nanotubes were formed when NK cells contacted target cells and moved apart. The frequency of nanotube formation was dependent on the number of receptor/ligand interactions and increased on NK cell activation. Most importantly, NK cell nanotubes contained a submicron scale junction where proteins accumulated, including DAP10, the signaling adaptor that associates with the activating receptor NKG2D, and MHC class I chain-related protein A (MICA), a cognate ligand for NKG2D, as occurs at close intercellular synapses between NK cells and target cells. Quantitative live-cell fluorescence imaging suggested that MICA accumulated at small nanotube synapses in sufficient numbers to trigger cell activation. In addition, tyrosine-phosphorylated proteins and Vav-1 accumulated at such junctions. Functionally, nanotubes could aid the lysis of distant target cells either directly or by moving target cells along the nanotube path into close contact for lysis via a conventional immune synapse. Target cells moving along the nanotube path were commonly polarized such that their uropods faced the direction of movement. This is the opposite polarization than for normal cell migration, implying that nanotubes can specifically drive target cell movement. Finally, target cells that remained connected to an NK cell by a nanotube were frequently lysed, whereas removing the nanotube using a micromanipulator reduced lysis of these target cells. PMID:20212116

Protein S is inducible by interleukin 4 in T cells and inhibits lymphoid cell procoagulant activity

PubMed Central

Smiley, Stephen T.; Boyer, Sarah N.; Heeb, Mary J.; Griffin, John H.; Grusby, Michael J.

1997-01-01

Extravascular procoagulant activity often accompanies cell-mediated immune responses and systemic administration of pharmacologic anticoagulants prevents cell-mediated delayed-type hypersensitivity reactions. These observations suggest a direct association between coagulation and cell-mediated immunity. The cytokine interleukin (IL)-4 potently suppresses cell-mediated immune responses, but its mechanism of action remains to be determined. Herein we demonstrate that the physiologic anticoagulant protein S is IL-4-inducible in primary T cells. Although protein S was known to inhibit the classic factor Va-dependent prothrombinase assembled by endothelial cells and platelets, we found that protein S also inhibits the factor Va-independent prothrombinase assembled by lymphoid cells. Thus, protein S-mediated down-regulation of lymphoid cell procoagulant activity may be one mechanism by which IL-4 antagonizes cell-mediated immunity. PMID:9326636

Role of obestatin on growth hormone secretion: An in vitro approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pazos, Yolanda, E-mail: yolanda.pazos@usc.es; CIBER Fisiopatologia de la Obesidad y Nutricion; Alvarez, Carlos J.P.

Obestatin, the ghrelin-associated peptide, showed to activate MAPK signaling with no effect on Akt nor cell proliferating activity in rat tumor somatotroph cells (growth cells, GC). A sequential analysis of the obestatin transmembrane signaling pathway indicated a route involving the consecutive activation of G{sub i}, PI3k, novel PKC{epsilon}, and Src for ERK1/2 activation. Furthermore, obestatin treatment triggers growth hormone (GH) release in the first 30 min, being more acute at 15 min. At 1 h, obestatin treated cells showed the same levels in GH secretion than controls. Added to this functionality, obestatin was secreted by GC cells. Based on themore » capacity to stimulate GH release from somatotroph cells, obestatin may act directly in the pituitary through an autocrine/paracrine mechanism.« less

PEA and luteolin synergistically reduce mast cell-mediated toxicity and elicit neuroprotection in cell-based models of brain ischemia.

PubMed

Parrella, Edoardo; Porrini, Vanessa; Iorio, Rosa; Benarese, Marina; Lanzillotta, Annamaria; Mota, Mariana; Fusco, Mariella; Tonin, Paolo; Spano, PierFranco; Pizzi, Marina

2016-10-01

The combination of palmitoylethanolamide (PEA), an endogenous fatty acid amide belonging to the family of the N-acylethanolamines, and the flavonoid luteolin has been found to exert neuroprotective activities in a variety of mouse models of neurological disorders, including brain ischemia. Indirect findings suggest that the two molecules can reduce the activation of mastocytes in brain ischemia, thus modulating crucial cells that trigger the inflammatory cascade. Though, no evidence exists about a direct effect of PEA and luteolin on mast cells in experimental models of brain ischemia, either used separately or in combination. In order to fill this gap, we developed a novel cell-based model of severe brain ischemia consisting of primary mouse cortical neurons and cloned mast cells derived from mouse fetal liver (MC/9 cells) subjected to oxygen and glucose deprivation (OGD). OGD exposure promoted both mast cell degranulation and the release of lactate dehydrogenase (LDH) in a time-dependent fashion. MC/9 cells exacerbated neuronal damage in neuron-mast cells co-cultures exposed to OGD. Likewise, the conditioned medium derived from OGD-exposed MC/9 cells induced significant neurotoxicity in control primary neurons. PEA and luteolin pre-treatment synergistically prevented the OGD-induced degranulation of mast cells and reduced the neurotoxic potential of MC/9 cells conditioned medium. Finally, the association of the two drugs promoted a direct synergistic neuroprotection even in pure cortical neurons exposed to OGD. In summary, our results indicate that mast cells release neurotoxic factors upon OGD-induced activation. The association PEA-luteolin actively reduces mast cell-mediated neurotoxicity as well as pure neurons susceptibility to OGD. Copyright © 2016 Elsevier B.V. All rights reserved.

The Immune Adaptor SLP-76 Binds to SUMO-RANGAP1 at Nuclear Pore Complex Filaments to Regulate Nuclear Import of Transcription Factors in T Cells

PubMed Central

Liu, Hebin; Schneider, Helga; Recino, Asha; Richardson, Christine; Goldberg, Martin W.; Rudd, Christopher E.

2015-01-01

Summary While immune cell adaptors regulate proximal T cell signaling, direct regulation of the nuclear pore complex (NPC) has not been reported. NPC has cytoplasmic filaments composed of RanGAP1 and RanBP2 with the potential to interact with cytoplasmic mediators. Here, we show that the immune cell adaptor SLP-76 binds directly to SUMO-RanGAP1 of cytoplasmic fibrils of the NPC, and that this interaction is needed for optimal NFATc1 and NF-κB p65 nuclear entry in T cells. Transmission electron microscopy showed anti-SLP-76 cytoplasmic labeling of the majority of NPCs in anti-CD3 activated T cells. Further, SUMO-RanGAP1 bound to the N-terminal lysine 56 of SLP-76 where the interaction was needed for optimal RanGAP1-NPC localization and GAP exchange activity. While the SLP-76-RanGAP1 (K56E) mutant had no effect on proximal signaling, it impaired NF-ATc1 and p65/RelA nuclear entry and in vivo responses to OVA peptide. Overall, we have identified SLP-76 as a direct regulator of nuclear pore function in T cells. PMID:26321253

The Immune Adaptor SLP-76 Binds to SUMO-RANGAP1 at Nuclear Pore Complex Filaments to Regulate Nuclear Import of Transcription Factors in T Cells.

PubMed

Liu, Hebin; Schneider, Helga; Recino, Asha; Richardson, Christine; Goldberg, Martin W; Rudd, Christopher E

2015-09-03

While immune cell adaptors regulate proximal T cell signaling, direct regulation of the nuclear pore complex (NPC) has not been reported. NPC has cytoplasmic filaments composed of RanGAP1 and RanBP2 with the potential to interact with cytoplasmic mediators. Here, we show that the immune cell adaptor SLP-76 binds directly to SUMO-RanGAP1 of cytoplasmic fibrils of the NPC, and that this interaction is needed for optimal NFATc1 and NF-κB p65 nuclear entry in T cells. Transmission electron microscopy showed anti-SLP-76 cytoplasmic labeling of the majority of NPCs in anti-CD3 activated T cells. Further, SUMO-RanGAP1 bound to the N-terminal lysine 56 of SLP-76 where the interaction was needed for optimal RanGAP1-NPC localization and GAP exchange activity. While the SLP-76-RanGAP1 (K56E) mutant had no effect on proximal signaling, it impaired NF-ATc1 and p65/RelA nuclear entry and in vivo responses to OVA peptide. Overall, we have identified SLP-76 as a direct regulator of nuclear pore function in T cells. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Rotenone and Paraquat do not Directly Activate Microglia or Induce Inflammatory Cytokine Release

PubMed Central

Klintworth, Heather; Garden, Gwenn; Xia, Zhengui

2009-01-01

Both epidemiological and pathological data suggest an inflammatory response including microglia activation and neuro-inflammation in the Parkinsonian brain. Treatments with lipopolysacchride (LPS), rotenone and paraquat have been used as models for Parkinson’s disease, as they cause dopaminergic neuron degeneration in culture and in animals. Recent studies have suggested that rotenone and paraquat induce neuro-inflammation, however, it is not known if they can directly activate microglia. Here, we use primary cultured microglia to address this question. Microglia activation was analyzed by morphological changes and release of nitric oxide and inflammatory cytokines. Treatment with LPS was used as a positive control. While LPS induced morphological changes characteristic of microglial activation and release of nitric oxide and inflammatory cytokines, rotenone and paraquat did not. Our results suggest that paraquat and rotenone do not act directly on microglia and that neuro-inflammation and microglial activation in animals treated with these agents is likely non-cell autonomous, and may occur as a result of dopaminergic neuron damage or factors released by neurons and other cells. PMID:19559752

Augmented IFN-γ and TNF-α Induced by Probiotic Bacteria in NK Cells Mediate Differentiation of Stem-Like Tumors Leading to Inhibition of Tumor Growth and Reduction in Inflammatory Cytokine Release; Regulation by IL-10

PubMed Central

Bui, Vickie T.; Tseng, Han-Ching; Kozlowska, Anna; Maung, Phyu Ou; Kaur, Kawaljit; Topchyan, Paytsar; Jewett, Anahid

2015-01-01

Our previous reports demonstrated that the magnitude of natural killer (NK) cell-mediated cytotoxicity correlate directly with the stage and level of differentiation of tumor cells. In addition, we have shown previously that activated NK cells inhibit growth of cancer cells through induction of differentiation, resulting in the resistance of tumor cells to NK cell-mediated cytotoxicity through secreted cytokines, as well as direct NK-tumor cell contact. In this report, we show that in comparison to IL-2 + anti-CD16mAb-treated NK cells, activation of NK cells by probiotic bacteria (sAJ2) in combination with IL-2 and anti-CD16mAb substantially decreases tumor growth and induces maturation, differentiation, and resistance of oral squamous cancer stem cells, MIA PaCa-2 stem-like/poorly differentiated pancreatic tumors, and healthy stem cells of apical papillae through increased secretion of IFN-γ and TNF-α, as well as direct NK-tumor cell contact. Tumor resistance to NK cell-mediated killing induced by IL-2 + anti-CD16mAb + sAJ2-treated NK cells is induced by combination of IFN-γ and TNF-α since antibodies to both, and not each cytokine alone, were able to restore tumor sensitivity to NK cells. Increased surface expression of CD54, B7H1, and MHC-I on NK-differentiated tumors was mediated by IFN-γ since the addition of anti-IFN-γ abolished their increase and restored the ability of NK cells to trigger cytokine and chemokine release; whereas differentiated tumors inhibited cytokine release by the NK cells. Monocytes synergize with NK cells in the presence of probiotic bacteria to induce regulated differentiation of stem cells through secretion of IL-10 resulting in resistance to NK cell-mediated cytotoxicity and inhibition of cytokine release. Therefore, probiotic bacteria condition activated NK cells to provide augmented differentiation of cancer stem cells resulting in inhibition of tumor growth, and decreased inflammatory cytokine release. PMID:26697005

Manufacturing Natural Killer Cells as Medicinal Products

PubMed Central

Chabannon, Christian; Mfarrej, Bechara; Guia, Sophie; Ugolini, Sophie; Devillier, Raynier; Blaise, Didier; Vivier, Eric; Calmels, Boris

2016-01-01

Natural Killer (NK) cells are innate lymphoid cells (ILC) with cytotoxic and regulatory properties. Their functions are tightly regulated by an array of inhibitory and activating receptors, and their mechanisms of activation strongly differ from antigen recognition in the context of human leukocyte antigen presentation as needed for T-cell activation. NK cells thus offer unique opportunities for new and improved therapeutic manipulation, either in vivo or in vitro, in a variety of human diseases, including cancers. NK cell activity can possibly be modulated in vivo through direct or indirect actions exerted by small molecules or monoclonal antibodies. NK cells can also be adoptively transferred following more or less substantial modifications through cell and gene manufacturing, in order to empower them with new or improved functions and ensure their controlled persistence and activity in the recipient. In the present review, we will focus on the technological and regulatory challenges of NK cell manufacturing and discuss conditions in which these innovative cellular therapies can be brought to the clinic. PMID:27895646

Direct observation of frequency modulated transcription in single cells using light activation

PubMed Central

Larson, Daniel R; Fritzsch, Christoph; Sun, Liang; Meng, Xiuhau; Lawrence, David S; Singer, Robert H

2013-01-01

Single-cell analysis has revealed that transcription is dynamic and stochastic, but tools are lacking that can determine the mechanism operating at a single gene. Here we utilize single-molecule observations of RNA in fixed and living cells to develop a single-cell model of steroid-receptor mediated gene activation. We determine that steroids drive mRNA synthesis by frequency modulation of transcription. This digital behavior in single cells gives rise to the well-known analog dose response across the population. To test this model, we developed a light-activation technology to turn on a single steroid-responsive gene and follow dynamic synthesis of RNA from the activated locus. DOI: http://dx.doi.org/10.7554/eLife.00750.001 PMID:24069527

The Pseudomonas aeruginosa exopolysaccharide Psl facilitates surface adherence and NF-kappaB activation in A549 cells.

PubMed

Byrd, Matthew S; Pang, Bing; Mishra, Meenu; Swords, W Edward; Wozniak, Daniel J

2010-06-29

In order for the opportunistic Gram-negative pathogen Pseudomonas aeruginosa to cause an airway infection, the pathogen interacts with epithelial cells and the overlying mucous layer. We examined the contribution of the biofilm polysaccharide Psl to epithelial cell adherence and the impact of Psl on proinflammatory signaling by flagellin. Psl has been implicated in the initial attachment of P. aeruginosa to biotic and abiotic surfaces, but its direct role in pathogenesis has not been evaluated (L. Ma, K. D. Jackson, R. M. Landry, M. R. Parsek, and D. J. Wozniak, J. Bacteriol. 188:8213-8221, 2006). Using an NF-kappaB luciferase reporter system in the human epithelial cell line A549, we show that both Psl and flagellin are necessary for full activation of NF-kappaB and production of the interleukin 8 (IL-8) chemokine. We demonstrate that Psl does not directly stimulate NF-kappaB activity, but indirectly as a result of increasing contact between bacterial cells and epithelial cells, it facilitates flagellin-mediated proinflammatory signaling. We confirm differential adherence of Psl and/or flagellin mutants by scanning electron microscopy and identify Psl-dependent membrane structures that may participate in adherence. Although we hypothesized that Psl would protect P. aeruginosa from recognition by the epithelial cell line A549, we instead observed a positive role for Psl in flagellin-mediated NF-kappaB activation, likely as a result of increasing contact between bacterial cells and epithelial cells.

The Pseudomonas aeruginosa Exopolysaccharide Psl Facilitates Surface Adherence and NF-κB Activation in A549 Cells

PubMed Central

Byrd, Matthew S.; Pang, Bing; Mishra, Meenu; Swords, W. Edward; Wozniak, Daniel J.

2010-01-01

In order for the opportunistic Gram-negative pathogen Pseudomonas aeruginosa to cause an airway infection, the pathogen interacts with epithelial cells and the overlying mucous layer. We examined the contribution of the biofilm polysaccharide Psl to epithelial cell adherence and the impact of Psl on proinflammatory signaling by flagellin. Psl has been implicated in the initial attachment of P. aeruginosa to biotic and abiotic surfaces, but its direct role in pathogenesis has not been evaluated (L. Ma, K. D. Jackson, R. M. Landry, M. R. Parsek, and D. J. Wozniak, J. Bacteriol. 188:8213–8221, 2006). Using an NF-κB luciferase reporter system in the human epithelial cell line A549, we show that both Psl and flagellin are necessary for full activation of NF-κB and production of the interleukin 8 (IL-8) chemokine. We demonstrate that Psl does not directly stimulate NF-κB activity, but indirectly as a result of increasing contact between bacterial cells and epithelial cells, it facilitates flagellin-mediated proinflammatory signaling. We confirm differential adherence of Psl and/or flagellin mutants by scanning electron microscopy and identify Psl-dependent membrane structures that may participate in adherence. Although we hypothesized that Psl would protect P. aeruginosa from recognition by the epithelial cell line A549, we instead observed a positive role for Psl in flagellin-mediated NF-κB activation, likely as a result of increasing contact between bacterial cells and epithelial cells. PMID:20802825

T Cell Stimulatory Effects of Korean Red Ginseng through Modulation of Myeloid-Derived Suppressor Cells

PubMed Central

Jeon, Chanoh; Kang, Soowon; Park, Seungbeom; Lim, Kyungtaek; Hwang, Kwang Woo; Min, Hyeyoung

2011-01-01

Myeloid-derived suppressor cells (MDSCs) actively suppress immune cells and have been considered as an impediment to successful cancer immunotherapy. Many approaches have been made to overcome such immunosuppressive factors and to exert effective anti-tumor effects, but the possibility of using medicinal plants for this purpose has been overlooked. Korean red ginseng (KRG) is widely known to possess a variety of pharmacological properties, including immunoboosting and anti-tumor activities. However, little has been done to assess the anti-tumor activity of KRG on MDSCs. Therefore, we examined the effects of KRG on MDSCs in tumor-bearing mice and evaluated immunostimulatory and anti-tumor activities of KRG through MDSC modulation. The data show that intraperitoneal administration of KRG compromises MDSC function and induces T cell proliferation and the secretion of IL-2 and IFN-γ, while it does not exhibit direct cytotoxicity on tumor cells and reduced MDSC accumulation. MDSCs isolated from KRG-treated mice also express significantly lower levels of inducible nitric oxide synthase and IL-10 accompanied by a decrease in nitric oxide production compared with control. Taken together, the present study demonstrates that KRG enhances T cell function by inhibiting the immunosuppressive activity of MDSCs and suggests that although KRG alone does not exhibit direct anti-tumor effects, the use of KRG together with conventional chemo- or immunotherapy may provide better outcomes to cancer patients through MDSC modulation. PMID:23717093

β-Catenin signaling regulates temporally discrete phases of anterior taste bud development

PubMed Central

Thirumangalathu, Shoba; Barlow, Linda A.

2015-01-01

The sense of taste is mediated by multicellular taste buds located within taste papillae on the tongue. In mice, individual taste buds reside in fungiform papillae, which develop at mid-gestation as epithelial placodes in the anterior tongue. Taste placodes comprise taste bud precursor cells, which express the secreted factor sonic hedgehog (Shh) and give rise to taste bud cells that differentiate around birth. We showed previously that epithelial activation of β-catenin is the primary inductive signal for taste placode formation, followed by taste papilla morphogenesis and taste bud differentiation, but the degree to which these later elements were direct or indirect consequences of β-catenin signaling was not explored. Here, we define discrete spatiotemporal functions of β-catenin in fungiform taste bud development. Specifically, we show that early epithelial activation of β-catenin, before taste placodes form, diverts lingual epithelial cells from a taste bud fate. By contrast, β-catenin activation a day later within Shh+ placodes, expands taste bud precursors directly, but enlarges papillae indirectly. Further, placodal activation of β-catenin drives precocious differentiation of Type I glial-like taste cells, but not other taste cell types. Later activation of β-catenin within Shh+ precursors during papilla morphogenesis also expands taste bud precursors and accelerates Type I cell differentiation, but papilla size is no longer enhanced. Finally, although Shh regulates taste placode patterning, we find that it is dispensable for the accelerated Type I cell differentiation induced by β-catenin. PMID:26525674

Vasa promotes Drosophila germline stem cell differentiation by activating mei-P26 translation by directly interacting with a (U)-rich motif in its 3' UTR.

PubMed

Liu, Niankun; Han, Hong; Lasko, Paul

2009-12-01

Vasa (Vas) is a DEAD-box RNA-binding protein required in Drosophila at several steps of oogenesis and for primordial germ cell (PGC) specification. Vas associates with eukaryotic initiation factor 5B (eIF5B), and this interaction has been implicated in translational activation of gurken mRNA in the oocyte. Vas is expressed in all ovarian germline cells, and aspects of the vas-null phenotype suggest a function in regulating the balance between germline stem cells (GSCs) and their fate-restricted descendants. We used a biochemical approach to recover Vas-associated mRNAs and obtained mei-P26, whose product represses microRNA activity and promotes GSC differentiation. We found that vas and mei-P26 mutants interact, and that mei-P26 translation is substantially reduced in vas mutant cells. In vitro, Vas protein bound specifically to a (U)-rich motif in the mei-P26 3' untranslated region (UTR), and Vas-dependent regulation of GFP-mei-P26 transgenes in vivo was dependent on the same (U)-rich 3' UTR domain. The ability of Vas to activate mei-P26 expression in vivo was abrogated by a mutation that greatly reduces its interaction with eIF5B. Taken together, our data support the conclusion that Vas promotes germ cell differentiation by directly activating mei-P26 translation in early-stage committed cells.

Huntingtin-interacting protein 1-mediated neuronal cell death occurs through intrinsic apoptotic pathways and mitochondrial alterations.

PubMed

Choi, Shin Ae; Kim, Steven J; Chung, Kwang Chul

2006-10-02

Huntingtin interacting protein-1 (Hip1) is known to be associated with the N-terminal domain of huntingtin. Although Hip1 can induce apoptosis, the exact upstream signal transduction pathways have not been clarified yet. In the present study, we examined whether activation of intrinsic and/or extrinsic apoptotic pathways occurs during Hip1-mediated neuronal cell death. Overexpression of Hip1 induced cell death through caspase-3 activation in immortalized hippocampal neuroprogenitor cells. Interestingly, proteolytic processing of Hip1 into partial fragments was observed in response to Hip1 transfection and apoptosis-inducing drugs. Moreover, Hip1 was found to directly bind to and activate caspase-9. This promoted cytosolic release of cytochrome c and apoptosis-inducing factor via mitochondrial membrane perturbation. Furthermore, Hip1 could directly bind to Apaf-1, suggesting that the neurotoxic signals of Hip1 transmit through the intrinsic mitochondrial apoptotic pathways and the formation of apoptosome complex.

Global Representations of Goal-Directed Behavior in Distinct Cell Types of Mouse Neocortex

PubMed Central

Allen, William E.; Kauvar, Isaac V.; Chen, Michael Z.; Richman, Ethan B.; Yang, Samuel J.; Chan, Ken; Gradinaru, Viviana; Deverman, Benjamin E.; Luo, Liqun; Deisseroth, Karl

2017-01-01

SUMMARY The successful planning and execution of adaptive behaviors in mammals may require long-range coordination of neural networks throughout cerebral cortex. The neuronal implementation of signals that could orchestrate cortex-wide activity remains unclear. Here, we develop and apply methods for cortex-wide Ca2+ imaging in mice performing decision-making behavior and identify a global cortical representation of task engagement encoded in the activity dynamics of both single cells and superficial neuropil distributed across the majority of dorsal cortex. The activity of multiple molecularly defined cell types was found to reflect this representation with type-specific dynamics. Focal optogenetic inhibition tiled across cortex revealed a crucial role for frontal cortex in triggering this cortex-wide phenomenon; local inhibition of this region blocked both the cortex-wide response to task-initiating cues and the voluntary behavior. These findings reveal cell-type-specific processes in cortex for globally representing goal-directed behavior and identify a major cortical node that gates the global broadcast of task-related information. PMID:28521139

Systems Biology Reveals Cigarette Smoke-Induced Concentration-Dependent Direct and Indirect Mechanisms That Promote Monocyte-Endothelial Cell Adhesion.

PubMed

Poussin, Carine; Laurent, Alexandra; Peitsch, Manuel C; Hoeng, Julia; De Leon, Hector

2015-10-01

Cigarette smoke (CS) affects the adhesion of monocytes to endothelial cells, a critical step in atherogenesis. Using an in vitro adhesion assay together with innovative computational systems biology approaches to analyze omics data, our study aimed at investigating CS-induced mechanisms by which monocyte-endothelial cell adhesion is promoted. Primary human coronary artery endothelial cells (HCAECs) were treated for 4 h with (1) conditioned media of human monocytic Mono Mac-6 (MM6) cells preincubated with low or high concentrations of aqueous CS extract (sbPBS) from reference cigarette 3R4F for 2 h (indirect treatment, I), (2) unconditioned media similarly prepared without MM6 cells (direct treatment, D), or (3) freshly generated sbPBS (fresh direct treatment, FD). sbPBS promoted MM6 cells-HCAECs adhesion following I and FD, but not D. In I, the effect was mediated at a low concentration through activation of vascular inflammation processes promoted in HCAECs by a paracrine effect of the soluble mediators secreted by sbPBS-treated MM6 cells. Tumor necrosis factor α (TNFα), a major inducer, was actually shed by unstable CS compound-activated TNFα-converting enzyme. In FD, the effect was triggered at a high concentration that also induced some toxicity. This effect was mediated through an yet unknown mechanism associated with a stress damage response promoted in HCAECs by unstable CS compounds present in freshly generated sbPBS, which had decayed in D unconditioned media. Aqueous CS extract directly and indirectly promotes monocytic cell-endothelial cell adhesion in vitro via distinct concentration-dependent mechanisms. © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Control of Human Endometrial Stromal Cell Motility by PDGF-BB, HB-EGF and Trophoblast-Secreted Factors

PubMed Central

Schwenke, Maren; Knöfler, Martin; Velicky, Philipp; Weimar, Charlotte H. E.; Kruse, Michelle; Samalecos, Annemarie; Wolf, Anja; Macklon, Nick S.; Bamberger, Ana-Maria; Gellersen, Birgit

2013-01-01

Human implantation involves extensive tissue remodeling at the fetal-maternal interface. It is becoming increasingly evident that not only trophoblast, but also decidualizing endometrial stromal cells are inherently motile and invasive, and likely contribute to the highly dynamic processes at the implantation site. The present study was undertaken to further characterize the mechanisms involved in the regulation of endometrial stromal cell motility and to identify trophoblast-derived factors that modulate migration. Among local growth factors known to be present at the time of implantation, heparin-binding epidermal growth factor-like growth factor (HB-EGF) triggered chemotaxis (directed locomotion), whereas platelet-derived growth factor (PDGF)-BB elicited both chemotaxis and chemokinesis (non-directed locomotion) of endometrial stromal cells. Supernatants of the trophoblast cell line AC-1M88 and of first trimester villous explant cultures stimulated chemotaxis but not chemokinesis. Proteome profiling for cytokines and angiogenesis factors revealed neither PDGF-BB nor HB-EGF in conditioned media from trophoblast cells or villous explants, while placental growth factor, vascular endothelial growth factor and PDGF-AA were identified as prominent secretory products. Among these, only PDGF-AA triggered endometrial stromal cell chemotaxis. Neutralization of PDGF-AA in trophoblast conditioned media, however, did not diminish chemoattractant activity, suggesting the presence of additional trophoblast-derived chemotactic factors. Pathway inhibitor studies revealed ERK1/2, PI3 kinase/Akt and p38 signaling as relevant for chemotactic motility, whereas chemokinesis depended primarily on PI3 kinase/Akt activation. Both chemotaxis and chemokinesis were stimulated upon inhibition of Rho-associated, coiled-coil containing protein kinase. The chemotactic response to trophoblast secretions was not blunted by inhibition of isolated signaling cascades, indicating activation of overlapping pathways in trophoblast-endometrial communication. In conclusion, trophoblast signals attract endometrial stromal cells, while PDGF-BB and HB-EGF, although not identified as trophoblast-derived, are local growth factors that may serve to fine-tune directed and non-directed migration at the implantation site. PMID:23349855

β-catenin induces expression of prohibitin gene in acute leukemic cells

PubMed Central

Kim, Dong Min; Jang, Hanbit; Shin, Myung Geun; Kim, Jeong-Hoon; Shin, Sang Mo; Min, Sang-Hyun; Kim, Il-Chul

2017-01-01

Prohibitin (PHB) is a multifunctional protein conserved in eukaryotic systems and shows various expression levels in tumor cells. However, regulation of PHB is not clearly understood. Here, we focused on the regulation of PHB expression by Wnt signaling, one of dominant regulatory signals in various leukemic cells. High mRNA levels of PHB were found in half of clinical leukemia samples. PHB expression was increased by inhibition of the MAPK pathway and decreased by activation of EGF signal. Although cell proliferating signals downregulated the transcription of PHB, treatment with lithium chloride, an analog of the Wnt signal, induced PHB level in various cell types. We identified the TCF-4/LEF-1 binding motif, CATCTG, in the promoter region of PHB by site-directed mutagenesis and ChIP assay. This β-catenin-mediated activation of PHB expression was independent of c-MYC activation, a product of Wnt signaling. These data indicate that PHB is a direct target of β-catenin and the increased level of PHB in leukemia can be regulated by Wnt signaling. PMID:28440457

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu, Mingning, E-mail: lcuzfy@163.com; Liu, Lei, E-mail: leiliulab@163.com; Chen, Lieqian, E-mail: lieqianchen@163.com

Highlights: • miR-183 was up-regulated in renal cancer tissues. • Inhibition of endogenous miR-183 suppressed renal cancer cell growth and metastasis. • miR-183 increased cell growth and metastasis. • miR-183 regulated renal cancer cell growth and metastasis via directly targeting tumor suppressor protein phosphatase 2A. - Abstract: The aim of this study was to investigate the function of miR-183 in renal cancer cells and the mechanisms miR-183 regulates this process. In this study, level of miR-183 in clinical renal cancer specimens was detected by quantitative real-time PCR. miR-183 was up- and down-regulated in two renal cancer cell lines ACHN andmore » A498, respectively, and cell proliferation, Caspase 3/7 activity, colony formation, in vitro migration and invasion were measured; and then the mechanisms of miR-183 regulating was analyzed. We found that miR-183 was up-regulated in renal cancer tissues; inhibition of endogenous miR-183 suppressed in vitro cell proliferation, colony formation, migration, and invasion and stimulated Caspase 3/7 activity; up-regulated miR-183 increased cell growth and metastasis and suppressed Caspase 3/7 activity. We also found that miR-183 directly targeted tumor suppressor, specifically the 3′UTR of three subunits of protein phosphatase 2A (PP2A-Cα, PP2A-Cβ, and PP2A-B56-γ) transcripts, inhibiting their expression and regulated the downstream regulators p21, p27, MMP2/3/7 and TIMP1/2/3/4. These results revealed the oncogenes role of miR-183 in renal cancer cells via direct targeting protein phosphatase 2A.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zan, Yanlu; University of Chinese Academy of Sciences, Beijing 100049; Zhang, Yuxia, E-mail: yzhang@wehi.edu.au

Highlights: •HBeAg expression in HSCs induced production of ECM protein and liver fibrotic markers. •The activation and proliferation of HSCs were mediated by TGF-β. •HBeAg protein purified from cell medium directly activated HSCs. -- Abstract: Chronic hepatitis B virus infection is a major cause of hepatic fibrosis, leading to liver cirrhosis and hepatocellular carcinoma. Hepatitis B virus e antigen (HBeAg) is an accessory protein of HBV, not required for viral replication but important for natural infection in vivo. Hepatic stellate cells (HSCs) are the major producers of excessive extracellular matrix during liver fibrogenesis. Therefore, we examined the influence of HBeAgmore » on HSCs. The rat HSC line HSC-T6 was transfected with HBeAg plasmids, and expression of α-smooth muscle actin, collagen I, transforming growth factor-β1 (TGF-β), and tissue inhibitors of metalloproteinase 1 (TIMP-1) was investigated by quantitative real-time PCR. The proliferation of HSCs was determined by MTS analysis. HBeAg transduction induced up-regulation of these fibrogenic genes and proliferation of HSCs. We found that HBeAg induced TGF-β secretion in HSCs, and the activation of HSCs was prevented by a neutralizing anti-TGF-β antibody. Depletion and addition of HBeAg protein in conditioned medium from HSC-T6 cells transduced with HBeAg indicated that HBeAg directly induced the activation and proliferation of rat primary HSCs. Taken together, HBeAg induces the activation and proliferation of HSCs, mainly mediated by TGF-β, and HBeAg protein purified from cell medium can directly activate HSCs.« less

Involvement of dendritic cells in allograft rejection new implications of dendritic cell-endothelial cell interactions.

PubMed

Schlichting, C L; Schareck, W D; Kofler, S; Weis, M

2007-04-01

For almost half a century immunologists have tried to tear down the MHC barrier, which separates two unrelated individuals during transplantation. Latest experimental data suggest that a breakthrough in vitro is imminent. Dendritic cells (DCs), which activate naïve allo-reactive T-cells (TCs), play a central role in the establishment of allo-antigen-specific immunity. Allograft solid organ rejection is initiated at the foreign endothelial cell (EC) layer, which forms an immunogenic barrier for migrating DCs. Thus, DC/EC interactions might play a crucial role in antigen-specific allograft rejection. Organ rejection is mediated by host allo-reactive TCs, which are activated by donor DCs (direct activation) or host DCs (indirect activation). Direct allo-antigen presentation by regulatory dendritic cells (DCreg) can play an instructive role towards tolerance induction. Several groups established that, DCregs, if transplanted beforehand, enter host thymus, spleen, or bone marrow where they might eventually establish allo-antigen-specific tolerance. A fundamental aspect of DC function is migration throughout the entire organism. After solid organ transplantation, host DCs bind to ECs, invade allograft tissues, and finally transmigrate into lymphoid vessels and secondary lymphoid organs, where they present allo-antigens to naïve host TCs. Recent data suggest that in vitro manipulated DCregs may mediate allo-transplantation tolerance induction. However, the fundamental mechanisms on how such DCregs cause host TCs in the periphery towards tolerance remain unclear. One very promising experimental concept is the simultaneous manipulation of DC direct and indirect TC activation/suppression, towards donor antigen-specific allo-transplantation tolerance. The allo-antigen-specific long-term tolerance induction mediated by DCreg pre-transplantation (with simultaneous short-term immunosuppression) has become reproducible in the laboratory animal setting. Despite the shortcomings of laboratory animal studies, strong promises are deriving from these studies for clinical kidney, heart, and liver transplantation.

Cell-cycle control in the face of damage--a matter of life or death.

PubMed

Clarke, Paul R; Allan, Lindsey A

2009-03-01

Cells respond to DNA damage or defects in the mitotic spindle by activating checkpoints that arrest the cell cycle. Alternatively, damaged cells can undergo cell death by the process of apoptosis. The correct balance between these pathways is important for the maintenance of genomic integrity while preventing unnecessary cell death. Although the molecular mechanisms of the cell cycle and apoptosis have been elucidated, the links between them have not been clear. Recent work, however, indicates that common components directly link the regulation of apoptosis with cell-cycle checkpoints operating during interphase, whereas in mitosis, the control of apoptosis is directly coupled to the cell-cycle machinery. These findings shed new light on how the balance between cell-cycle progression and cell death is controlled.

Root growth restraint can be an acclimatory response to low pH and is associated with reduced cell mortality: a possible role of class III peroxidases and NADPH oxidases.

PubMed

Graças, J P; Ruiz-Romero, R; Figueiredo, L D; Mattiello, L; Peres, L E P; Vitorello, V A

2016-07-01

Low pH (<5.0) can significantly decrease root growth but whether this is a direct effect of H(+) or an active plant response is examined here. Tomato (Solanum lycopersicum cv Micro-Tom) roots were exposed directly or gradually to low pH through step-wise changes in pH over periods ranging from 4 to 24 h. Roots exposed gradually to pH 4.5 grew even less than those exposed directly, indicating a plant-coordinated response. Direct exposure to pH 4.0 suppressed root growth and caused high cell mortality, in contrast to roots exposed gradually, in which growth remained inhibited but cell viability was maintained. Total class III peroxidase activity increased significantly in all low pH treatments, but was not correlated with the observed differential responses. Use of the enzyme inhibitors salicylhydroxamic acid (SHAM) or diphenyleneiodonium chloride (DPI) suggest that peroxidase and, to a lesser extent, NADPH oxidase were required to prevent or reduce injury in all low pH treatments. However, a role for other enzymes, such as the alternative oxidase is also possible. The results with SHAM, but not DPI, were confirmed in tobacco BY-2 cells. Our results indicate that root growth inhibition from low pH can be part of an active plant response, and suggest that peroxidases may have a critical early role in reducing loss of cell viability and in the observed root growth constraint. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Basics of cancer immunotherapy.

PubMed

Fujioka, Yuki; Nishikawa, Hiroyoshi

2016-01-01

The immune system is the body's defense against infectious organisms and other invaders including cancer cells. Cancer immunotherapy, which employs our own immune systems to attack cancer cells, is now emerging as a promising modality of cancer treatment based upon the clinical successes of immune checkpoint blockade and adoptive T cell transfer. In hematologic malignancies, clinical application of anti-PD-1 mAb and CAR (chimeric antigen receptor) T therapy is now being extensively tested in Hodgkin's disease, multiple myeloma, and CD19 + acute lymphocytic leukemia. In sharp contrast to conventional anti-cancer reagents which directly kill cancer cells, cancer immunotherapy activates various types of immune effector cells to attack cancer cells. However, more than half of the treated patients showed no activation of anti-tumor CD8 + killer T cells and CD4 + helper T cells and failed to respond to immune therapies such as immune checkpoint blockade, even when administered in combination regimens. Thus, development of novel immunotherapies to achieve more effective activation of anti-cancer immunity and immuno-monitoring of biomarkers, allowing proper evaluation of immune responses in cancer patients in order to detect responders, are urgent issues. Additionally, we must pay attention to characteristic immunological side effects not observed following treatment with conventional anti-cancer reagents. Herein, we present a summary outline and discuss the future direction of cancer immunotherapy.

Updating of the spatial reference frame of head direction cells in response to locomotion in the vertical plane

PubMed Central

Wang, Sarah S.; Kim, Stanley Y.; Frohardt, Russell J.

2013-01-01

Many species navigate in three dimensions and are required to maintain accurate orientation while moving in an Earth vertical plane. Here we explored how head direction (HD) cells in the rat anterodorsal thalamus responded when rats locomoted along a 360° spiral track that was positioned vertically within the room at the N, S, E, or W location. Animals were introduced into the vertical plane either through passive placement (experiment 1) or by allowing them to run up a 45° ramp from the floor to the vertically positioned platform (experiment 2). In both experiments HD cells maintained direction-specific firing in the vertical plane with firing properties that were indistinguishable from those recorded in the horizontal plane. Interestingly, however, the cells' preferred directions were linked to different aspects of the animal's environment and depended on how the animal transitioned into the vertical plane. When animals were passively placed onto the vertical surface, the cells switched from using the room (global cues) as a reference frame to using the vertically positioned platform (local cues) as a reference frame, independent of where the platform was located. In contrast, when animals self-locomoted into the vertical plane, the cells' preferred directions remained anchored to the three-dimensional room coordinates and their activity could be accounted for by a simple 90° rotation of the floor's horizontal coordinate system to the vertical plane. These findings highlight the important role that active movement signals play for maintaining and updating spatial orientation when moving in three dimensions. PMID:23114216

Dihydroceramide accumulation mediates cytotoxic autophagy of cancer cells via autolysosome destabilization.

PubMed

Hernández-Tiedra, Sonia; Fabriàs, Gemma; Dávila, David; Salanueva, Íñigo J; Casas, Josefina; Montes, L Ruth; Antón, Zuriñe; García-Taboada, Elena; Salazar-Roa, María; Lorente, Mar; Nylandsted, Jesper; Armstrong, Jane; López-Valero, Israel; McKee, Christopher S; Serrano-Puebla, Ana; García-López, Roberto; González-Martínez, José; Abad, José L; Hanada, Kentaro; Boya, Patricia; Goñi, Félix; Guzmán, Manuel; Lovat, Penny; Jäättelä, Marja; Alonso, Alicia; Velasco, Guillermo

2016-11-01

Autophagy is considered primarily a cell survival process, although it can also lead to cell death. However, the factors that dictate the shift between these 2 opposite outcomes remain largely unknown. In this work, we used Δ 9 -tetrahydrocannabinol (THC, the main active component of marijuana, a compound that triggers autophagy-mediated cancer cell death) and nutrient deprivation (an autophagic stimulus that triggers cytoprotective autophagy) to investigate the precise molecular mechanisms responsible for the activation of cytotoxic autophagy in cancer cells. By using a wide array of experimental approaches we show that THC (but not nutrient deprivation) increases the dihydroceramide:ceramide ratio in the endoplasmic reticulum of glioma cells, and this alteration is directed to autophagosomes and autolysosomes to promote lysosomal membrane permeabilization, cathepsin release and the subsequent activation of apoptotic cell death. These findings pave the way to clarify the regulatory mechanisms that determine the selective activation of autophagy-mediated cancer cell death.

Effects of direct current electric-field using ITO plate on breast cancer cell migration.

PubMed

Kim, Min Sung; Lee, Mi Hee; Kwon, Byeong-Ju; Seo, Hyok Jin; Koo, Min-Ah; You, Kyung Eun; Kim, Dohyun; Park, Jong-Chul

2014-01-01

Cell migration is an essential activity of the cells in various biological phenomena. The evidence that electrotaxis plays important roles in many physiological phenomena is accumulating. In electrotaxis, cells move with a directional tendency toward the anode or cathode under direct-current electric fields. Indium tin oxide, commonly referred to as ITO has high luminous transmittance, high infrared reflectance, good electrical conductivity, excellent substrate adherence, hardness and chemical inertness and hence, have been widely and intensively studied for many years. Because of these properties of ITO films, the electrotaxis using ITO plate was evaluated. Under the 0 V/cm condition, MDA-MB-231 migrated randomly in all directions. When 1 V/cm of dc EF was applied, cells moved toward anode. The y forward migration index was -0.046 ± 0.357 under the 0 V/cm and was 0.273 ± 0.231 under direct-current electric field of 1 V/cm. However, the migration speed of breast cancer cell was not affected by direct-current electric field using ITO plate. In this study, we designed a new electrotaxis system using an ITO coated glass and observed the migration of MDA-MB-231 on direct current electric-field of the ITO glass.

A dendrite-autonomous mechanism for direction selectivity in retinal starburst amacrine cells.

PubMed

Hausselt, Susanne E; Euler, Thomas; Detwiler, Peter B; Denk, Winfried

2007-07-01

Detection of image motion direction begins in the retina, with starburst amacrine cells (SACs) playing a major role. SACs generate larger dendritic Ca(2+) signals when motion is from their somata towards their dendritic tips than for motion in the opposite direction. To study the mechanisms underlying the computation of direction selectivity (DS) in SAC dendrites, electrical responses to expanding and contracting circular wave visual stimuli were measured via somatic whole-cell recordings and quantified using Fourier analysis. Fundamental and, especially, harmonic frequency components were larger for expanding stimuli. This DS persists in the presence of GABA and glycine receptor antagonists, suggesting that inhibitory network interactions are not essential. The presence of harmonics indicates nonlinearity, which, as the relationship between harmonic amplitudes and holding potential indicates, is likely due to the activation of voltage-gated channels. [Ca(2+)] changes in SAC dendrites evoked by voltage steps and monitored by two-photon microscopy suggest that the distal dendrite is tonically depolarized relative to the soma, due in part to resting currents mediated by tonic glutamatergic synaptic input, and that high-voltage-activated Ca(2+) channels are active at rest. Supported by compartmental modeling, we conclude that dendritic DS in SACs can be computed by the dendrites themselves, relying on voltage-gated channels and a dendritic voltage gradient, which provides the spatial asymmetry necessary for direction discrimination.

PML–RARA-RXR Oligomers Mediate Retinoid and Rexinoid/cAMP Cross-Talk in Acute Promyelocytic Leukemia Cell Differentiation

PubMed Central

Kamashev, Dmitrii; Vitoux, Dominique; de Thé, Hugues

2004-01-01

PML–RARA was proposed to initiate acute promyelocytic leukemia (APL) through PML–RARA homodimer–triggered repression. Here, we examined the nature of the PML–RARA protein complex and of its DNA targets in APL cells. Using a selection/amplification approach, we demonstrate that PML–RARA targets consist of two AGGTCA elements in an astonishing variety of orientations and spacings, pointing to highly relaxed structural constrains for DNA binding and identifying a major gain of function of this oncogene. PML–RARA-specific response elements were identified, which all conveyed a major transcriptional response to RA only in APL cells. In these cells, we demonstrate that PML–RARA oligomers are complexed to RXR. Directly probing PML–RARA function in APL cells, we found that the differentiation enhancer cyclic AMP (cAMP) boosted transcriptional activation by RA. cAMP also reversed the normal silencing (subordination) of the transactivating function of RXR when bound to RARA or PML–RARA, demonstrating that the alternate rexinoid/cAMP-triggered APL differentiation pathway also activates PML–RARA targets. Finally, cAMP restored both RA-triggered differentiation and PML–RARA transcriptional activation in mutant RA-resistant APL cells. Collectively, our findings directly demonstrate that APL cell differentiation parallels transcriptional activation through PML–RARA-RXR oligomers and that those are functionally targeted by cAMP, identifying this agent as another oncogene-targeted therapy. PMID:15096541

External light activates hair follicle stem cells through eyes via an ipRGC-SCN-sympathetic neural pathway.

PubMed

Fan, Sabrina Mai-Yi; Chang, Yi-Ting; Chen, Chih-Lung; Wang, Wei-Hung; Pan, Ming-Kai; Chen, Wen-Pin; Huang, Wen-Yen; Xu, Zijian; Huang, Hai-En; Chen, Ting; Plikus, Maksim V; Chen, Shih-Kuo; Lin, Sung-Jan

2018-06-29

Changes in external light patterns can alter cell activities in peripheral tissues through slow entrainment of the central clock in suprachiasmatic nucleus (SCN). It remains unclear whether cells in otherwise photo-insensitive tissues can achieve rapid responses to changes in external light. Here we show that light stimulation of animals' eyes results in rapid activation of hair follicle stem cells with prominent hair regeneration. Mechanistically, light signals are interpreted by M1-type intrinsically photosensitive retinal ganglion cells (ipRGCs), which signal to the SCN via melanopsin. Subsequently, efferent sympathetic nerves are immediately activated. Increased norepinephrine release in skin promotes hedgehog signaling to activate hair follicle stem cells. Thus, external light can directly regulate tissue stem cells via an ipRGC-SCN autonomic nervous system circuit. Since activation of sympathetic nerves is not limited to skin, this circuit can also facilitate rapid adaptive responses to external light in other homeostatic tissues.

Antisense oligonucleotides suppress cell-volume-induced activation of chloride channels.

PubMed

Gschwentner, M; Nagl, U O; Wöll, E; Schmarda, A; Ritter, M; Paulmichl, M

1995-08-01

Cell volume regulation is an essential feature of most cells. After swelling in hypotonic media, the simultaneous activation of potassium and chloride channels is believed to be the initial, time-determining step in cell volume regulation. The activation of both pathways is functionally linked and enables the cells to lose ions and water, subsequently leading to cell shrinkage and readjustment of the initial volume. NIH 3T3 fibroblasts efficiently regulate their volume after swelling and bear chloride channels that are activated by decreasing extracellular osmolarity. The chloride current elicited in these cells after swelling is reminiscent of the current found in oocytes expressing an outwardly rectifying chloride current termed ICln. Introduction of antisense oligodeoxynucleotides complementary to the first 30 nucleotides of the coding region of the ICln channel into NIH 3T3 fibroblasts suppresses the activation of the swelling-induced chloride current. The experiments directly demonstrate an unambiguous link between a volume-activated chloride current and a cloned protein involved in chloride transport.

A new effective assay to detect antimicrobial activity of filamentous fungi.

PubMed

Pereira, Eric; Santos, Ana; Reis, Francisca; Tavares, Rui M; Baptista, Paula; Lino-Neto, Teresa; Almeida-Aguiar, Cristina

2013-01-15

The search for new antimicrobial compounds and the optimization of production methods turn the use of antimicrobial susceptibility tests a routine. The most frequently used methods are based on agar diffusion assays or on dilution in agar or broth. For filamentous fungi, the most common antimicrobial activity detection methods comprise the co-culture of two filamentous fungal strains or the use of fungal extracts to test against single-cell microorganisms. Here we report a rapid, effective and reproducible assay to detect fungal antimicrobial activity against single-cell microorganisms. This method allows an easy way of performing a fast antimicrobial screening of actively growing fungi directly against yeast. Because it makes use of an actively growing mycelium, this bioassay also provides a way for studying the production dynamics of antimicrobial compounds by filamentous fungi. The proposed assay is less time consuming and introduces the innovation of allowing the direct detection of fungal antimicrobial properties against single cell microorganisms without the prior isolation of the active substance(s). This is particularly useful when performing large screenings for fungal antimicrobial activity. With this bioassay, antimicrobial activity of Hypholoma fasciculare against yeast species was observed for the first time. Copyright © 2012 Elsevier GmbH. All rights reserved.

The acylphloroglucinols hyperforin and myrtucommulone A cause mitochondrial dysfunctions in leukemic cells by direct interference with mitochondria.

PubMed

Wiechmann, Katja; Müller, Hans; Fischer, Dagmar; Jauch, Johann; Werz, Oliver

2015-11-01

The acylphloroglucinols hyperforin (Hypf) and myrtucommulone A (MC A) induce death of cancer cells by triggering the intrinsic/mitochondrial pathway of apoptosis, accompanied by a loss of the mitochondrial membrane potential and release of cytochrome c. However, the upstream targets and mechanisms leading to these mitochondrial events in cancer cells remain elusive. Here we show that Hypf and MC A directly act on mitochondria derived from human leukemic HL-60 cells and thus, disrupt mitochondrial functions. In isolated mitochondria, Hypf and MC A efficiently impaired mitochondrial viability (EC50 = 0.2 and 0.9 µM, respectively), caused loss of the mitochondrial membrane potential (at 0.03 and 0.1 µM, respectively), and suppressed mitochondrial ATP synthesis (IC50 = 0.2 and 0.5 µM, respectively). Consequently, the compounds activated the adenosine monophosphate-activated protein kinase (AMPK) in HL-60 cells, a cellular energy sensor involved in apoptosis of cancer cells. Side by side comparison with the protonophore CCCP and the ATP synthase inhibitor oligomycin suggest that Hypf and MC A act as protonophores that primarily dissipate the mitochondrial membrane potential by direct interaction with the mitochondrial membrane. Together, Hypf and MC A abolish the mitochondrial proton motive force that on one hand impairs mitochondrial viability and on the other cause activation of AMPK due to lowered ATP levels which may further facilitate the intrinsic mitochondrial pathway of apoptosis.

Development of Ni-Ba(Zr,Y)O3 cermet anodes for direct ammonia-fueled solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Miyazaki, Kazunari; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

2017-10-01

In this study, the availability of Ni-Ba(Zr,Y)O3-δ (BZY) cermet for the anode of direct ammonia-fueled solid oxide fuel cells (SOFCs) is evaluated. In this device, the anodes need to be active for the catalytic ammonia decomposition as well as the electrochemical hydrogen oxidation. In the catalytic activity test, ammonia decomposes completely over Ni-BZY at ca. 600 °C, while higher temperature is required to accomplish the complete decomposition over the conventional SOFC anode of Ni-yttria-stabilized zirconia cermet. The high activity of Ni-BZY is attributed to the high basicity of BZY and the high resistance to hydrogen poisoning effect. The electrochemical property of Ni-BZY anode is also evaluated with the anode-supported cell of Ni-BZY|BZY|Pt at 600-700 °C with feeding ammonia or hydrogen as a fuel. Since the residence time of ammonia fuel in the thick Ni-BZY anode is long, the difference in the cell performance between two fuels is relatively small. Furthermore, it is proved that the steam concentration in the fuel strongly affects the cell performance. We find that this factor is important to satisfy the above mentioned requirements for the anode of direct ammonia-fueled SOFCs. Throughout this study, it is concluded that Ni-BZY cermet will be a promising anode.

Exposure of T lymphocytes to leflunomide but not to dexamethasone favors the production by monocytic cells of interleukin-1 receptor antagonist and the tissue-inhibitor of metalloproteinases-1 over that of interleukin-1beta and metalloproteinases.

PubMed

Déage, V; Burger, D; Dayer, J M

1998-12-01

On direct cell-cell contact, stimulated T lymphocytes potently trigger the production of pro-inflammatory factors such as interleukin-1beta (IL-1beta) and matrix metalloproteinases (MMP-1 and MMP-9), as well as anti-inflammatory factors such as IL-1 receptor antagonist (IL-1Ra) and the tissue inhibitor of metalloproteinases (TIMP-1) in peripheral blood monocytes and the monocytic cell line THP-1. Such mechanisms might play an important part in many inflammatory diseases where tissue destruction occurs. To assess whether anti-inflammatory agents such as dexamethasone (DEX) and leflunomide (LF) would affect contact-activation of monocytic cells, T lymphocytes were stimulated by PMA and PHA in the presence or absence of increasing concentrations of drug. LF and DEX (10- 4 M) inhibited the ability of stimulated T lymphocytes to activate monocytic cells by 66-97% and 43-70%, respectively, depending on the readout product. Upon contact with T lymphocytes stimulated in the presence of 10- 5 M LF, the molar ratio of IL-1Ra/IL-1beta and TIMP-1/MMP-1 produced by THP-1 cells was enhanced 3.6- and 1.9-fold, respectively, whereas it was enhanced only 1.3- and 1.4-fold upon contact with T lymphocytes stimulated in the presence of 10- 4 M DEX. Therefore, LF tends to favor the inhibition of pro-inflammatory and matrix-destructive factors over that of anti-inflammatory factors and metalloproteinase inhibitors, thus interfering with both inflammation and tissue destruction. These experiments indicate that LF and DEX have the potential to affect the capacity of stimulated T lymphocytes to activate, on direct cell-cell contact, monocytic cells. Furthermore, flow cytometric analysis revealed that surface molecules of T lymphocytes that were partially involved in contact-signaling of monocytes (i.e., CD69 and CD11) were not modulated by either LF or DEX, suggesting that factors which remain to be identified were mainly involved in the activation of monocytes on direct cell-cell contact.

Functional cell-surface display of a lipase-specific chaperone.

PubMed

Wilhelm, Susanne; Rosenau, Frank; Becker, Stefan; Buest, Sebastian; Hausmann, Sascha; Kolmar, Harald; Jaeger, Karl-Erich

2007-01-02

Lipases are important enzymes in biotechnology. Extracellular bacterial lipases from Pseudomonads and related species require the assistance of specific chaperones, designated "Lif" proteins (lipase specific foldases). Lifs, a unique family of steric chaperones, are anchored to the periplasmic side of the inner membrane where they convert lipases into their active conformation. We have previously shown that the autotransporter protein EstA from P. aeruginosa can be used to direct a variety of proteins to the cell surface of Escherichia coli. Here we demonstrate for the first time the functional cell-surface display of the Lif chaperone and FACS (fluorescence-activated cell sorting)-based analysis of bacterial cells that carried foldase-lipase complexes. The model Lif protein, LipH from P. aeruginosa, was displayed at the surface of E. coli cells. Surface exposed LipH was functional and efficiently refolded chemically denatured lipase. The foldase autodisplay system reported here can be used for a variety of applications including the ultrahigh-throughput screening of large libraries of foldase variants generated by directed evolution.

The Epithelial Cell-derived Atopic Dermatitis Cytokine TSLP Activates Neurons to Induce Itch

PubMed Central

Wilson, Sarah R.; Thé, Lydia; Batia, Lyn M.; Beattie, Katherine; Katibah, George E.; McClain, Shannan P.; Pellegrino, Maurizio; Estandian, Daniel M.; Bautista, Diana M.

2014-01-01

Summary Atopic dermatitis (AD) is a chronic itch and inflammatory disorder of the skin that affects one in ten people. Patients suffering from severe AD eventually progress to develop asthma and allergic rhinitis, in a process known as the “atopic march.” Signaling between epithelial cells and innate immune cells via the cytokine Thymic Stromal Lymphopoietin (TSLP) is thought to drive AD and the atopic march. Here we report that epithelial cells directly communicate to cutaneous sensory neurons via TSLP to promote itch. We identify the ORAI1/NFAT calcium signaling pathway as an essential regulator of TSLP release from keratinocytes, the primary epithelial cells of the skin. TSLP then acts directly on a subset of TRPA1-positive sensory neurons to trigger robust itch behaviors. Our results support a new model whereby calcium-dependent TSLP release by keratinocytes activates both primary afferent neurons and immune cells to promote inflammatory responses in the skin and airways. PMID:24094650

[Cell entry mechanisms of coronaviruses].

PubMed

Taguchi, Fumihiro; Matsuyama, Shutoku

2009-12-01

Enveloped viruses enter into cells via fusion of their envelope and cellular membrane. Spike (S) protein of coronavirus (CoV) is responsible for entry events. We studied the cell entry mechanisms of two different CoVs, murine coronavirus mouse hepatitis virus (MHV) and severe acute respiratory syndrome coronavirus (SARS-CoV). MHV-JHM that induces syncytia in infected cells entered directly from cell surface, i.e., fusion of envelope and plasma membrane, whereas SARS-CoV and MHV-2 that fail to induce syncytia entered via endosome in a protease-dependent fashion, i.e., fusion of envelope and endosomal membrane. The latter viruses entered directly from cell surface, when receptor-bound viruses were treated with proteases that activate fusion activity of their S proteins. The entry pathway of SARS-CoV could influence the severity of the disease. It was also reveled that a highly neurovirulent JHM spread in a receptor-independent fashion, which could result in a high neuropathogenicity of the virus.

Direct negative chronotropic action of desflurane on sinoatrial node pacemaker activity in the guinea pig heart.

PubMed

Kojima, Akiko; Ito, Yuki; Kitagawa, Hirotoshi; Matsuura, Hiroshi; Nosaka, Shuichi

2014-06-01

Desflurane inhalation is associated with sympathetic activation and concomitant increase in heart rate in humans and experimental animals. There is, however, little information concerning the direct effects of desflurane on electrical activity of sinoatrial node pacemaker cells that determines the intrinsic heart rate. Whole-cell patch-clamp experiments were conducted on guinea pig sinoatrial node pacemaker cells to record spontaneous action potentials and ionic currents contributing to sinoatrial node automaticity, namely, hyperpolarization-activated cation current (If), T-type and L-type Ca currents (ICa,T and ICa,L, respectively), Na/Ca exchange current (INCX), and rapidly and slowly activating delayed rectifier K currents (IKr and IKs, respectively). Electrocardiograms were recorded from ex vivo Langendorff-perfused hearts and in vivo hearts. Desflurane at 6 and 12% decreased spontaneous firing rate of sinoatrial node action potentials by 15.9% (n = 11) and 27.6% (n = 10), respectively, which was associated with 20.4% and 42.5% reductions in diastolic depolarization rate, respectively. Desflurane inhibited If, ICa,T, ICa,L, INCX, and IKs but had little effect on IKr. The negative chronotropic action of desflurane was reasonably well reproduced in sinoatrial node computer model. Desflurane reduced the heart rate in Langendorff-perfused hearts. High concentration (12%) of desflurane inhalation was associated with transient tachycardia, which was totally abolished by pretreatment with the β-adrenergic blocker propranolol. Desflurane has a direct negative chronotropic action on sinoatrial node pacemaking activity, which is mediated by its inhibitory action on multiple ionic currents. This direct inhibitory action of desflurane on sinoatrial node automaticity seems to be counteracted by sympathetic activation associated with desflurane inhalation in vivo.

Effects of alpha/beta-androstenediol immune regulating hormones on bone remodeling and apoptosis in osteoblasts.

PubMed

Urban, Nicole H; Chamberlin, Brett; Ramage, Samuel; Roberts, Zachary; Loria, Roger M; Beckman, Matthew J

2008-06-01

A large body of evidence suggests that the immune system directly impacts bone physiology. We tested whether immune regulating hormones (IRH), 17beta-androstenediol (beta-AED), 7beta,17beta-androstenetriol (beta-AET) or the 17alpha-androstenediol (alpha-AED), and 7alpha,17beta-androstenetriol (alpha-AET) metabolites could directly influence bone remodeling in vitro using human fetal osteoblasts (FOB-9). The impact on bone remodeling was examined by comparing the ratio of RANKL/OPG gene expression in response to AED and AET compounds. The alpha-AED was found to significantly increase in the ratio of RANKL/OPG gene expression and altering the morphology of RANKL stained FOB-9 cells. Cell viability was assessed using a Live/Dead assay. Again alpha-AED was unique in its ability to reduce the proportion of viable cells, and to induce mild apoptosis of FOB-9 cells. Treatment of FOB-9 cells with WY14643, an activator of PPAR-alpha and -gamma, also significantly elevated the percentage of dead cells. This increase was abolished by co-treatment with GW9962, a specific inhibitor of PPAR-gamma. Analysis of PPAR-gamma mRNA by Quantitative RT-PCR and its activation by DNA binding demonstrated that alpha-AED increased PPAR-gamma activation by 19%, while beta-AED conferred a 37% decrease in PPAR-gamma activation. In conclusion, alpha-AED opposed beta-AED by elevating a bone resorption scenario in osteoblast cells. The increase in RANKL/OPG is modulated by an activation of PPAR-gamma that in turn caused mild apoptosis of FOB-9 cells.

Formation and specification of a Drosophila dopaminergic precursor cell.

PubMed

Watson, Joseph D; Crews, Stephen T

2012-09-01

Dopaminergic neurons play important roles in animal behavior, including motivation, reward and locomotion. The Drosophila dopaminergic H-cell interneuron is an attractive system for studying the genetics of neural development because analysis is focused on a single neuronal cell type. Here we provide a mechanistic understanding of how MP3, the precursor to the H-cell, forms and acquires its identity. We show that the gooseberry/gooseberry-neuro (gsb/gsb-n) transcription factor genes act to specify MP3 cell fate. It is proposed that single-minded commits neuroectodermal cells to a midline fate, followed by a series of signaling events that result in the formation of a single gsb(+)/gsb-n(+) MP3 cell per segment. The wingless signaling pathway establishes a midline anterior domain by activating expression of the forkhead transcription factors sloppy paired 1 and sloppy paired 2. This is followed by hedgehog signaling that activates gsb/gsb-n expression in a subgroup of anterior cells. Finally, Notch signaling results in the selection of a single MP3, with the remaining cells becoming midline glia. In MP3, gsb/gsb-n direct H-cell development, in large part by activating expression of the lethal of scute and tailup H-cell regulatory genes. Thus, a series of signaling and transcriptional events result in the specification of a unique dopaminergic precursor cell. Additional genetic experiments indicate that the molecular mechanisms that govern MP3/H-cell development might also direct the development of non-midline dopaminergic neurons.

Formation and specification of a Drosophila dopaminergic precursor cell

PubMed Central

Watson, Joseph D.; Crews, Stephen T.

2012-01-01

Dopaminergic neurons play important roles in animal behavior, including motivation, reward and locomotion. The Drosophila dopaminergic H-cell interneuron is an attractive system for studying the genetics of neural development because analysis is focused on a single neuronal cell type. Here we provide a mechanistic understanding of how MP3, the precursor to the H-cell, forms and acquires its identity. We show that the gooseberry/gooseberry-neuro (gsb/gsb-n) transcription factor genes act to specify MP3 cell fate. It is proposed that single-minded commits neuroectodermal cells to a midline fate, followed by a series of signaling events that result in the formation of a single gsb+/gsb-n+ MP3 cell per segment. The wingless signaling pathway establishes a midline anterior domain by activating expression of the forkhead transcription factors sloppy paired 1 and sloppy paired 2. This is followed by hedgehog signaling that activates gsb/gsb-n expression in a subgroup of anterior cells. Finally, Notch signaling results in the selection of a single MP3, with the remaining cells becoming midline glia. In MP3, gsb/gsb-n direct H-cell development, in large part by activating expression of the lethal of scute and tailup H-cell regulatory genes. Thus, a series of signaling and transcriptional events result in the specification of a unique dopaminergic precursor cell. Additional genetic experiments indicate that the molecular mechanisms that govern MP3/H-cell development might also direct the development of non-midline dopaminergic neurons. PMID:22874915

Modified Vaccinia Virus Ankara-Infected Dendritic Cells Present CD4+ T-Cell Epitopes by Endogenous Major Histocompatibility Complex Class II Presentation Pathways

PubMed Central

Thiele, Frank; Tao, Sha; Zhang, Yi; Muschaweckh, Andreas; Zollmann, Tina; Protzer, Ulrike; Abele, Rubert

2014-01-01

ABSTRACT CD4+ T lymphocytes play a central role in the immune system and mediate their function after recognition of their respective antigens presented on major histocompatibility complex II (MHCII) molecules on antigen-presenting cells (APCs). Conventionally, phagocytosed antigens are loaded on MHCII for stimulation of CD4+ T cells. Certain epitopes, however, can be processed directly from intracellular antigens and are presented on MHCII (endogenous MHCII presentation). Here we characterized the MHCII antigen presentation pathways that are possibly involved in the immune response upon vaccination with modified vaccinia virus Ankara (MVA), a promising live viral vaccine vector. We established CD4+ T-cell lines specific for MVA-derived epitopes as tools for in vitro analysis of MHCII antigen processing and presentation in MVA-infected APCs. We provide evidence that infected APCs are able to directly transfer endogenous viral proteins into the MHCII pathway to efficiently activate CD4+ T cells. By using knockout mice and chemical inhibitory compounds, we further elucidated the molecular basis, showing that among the various subcellular pathways investigated, proteasomes and autophagy are key players in the endogenous MHCII presentation during MVA infection. Interestingly, although proteasomal processing plays an important role, neither TAP nor LAMP-2 was found to be involved in the peptide transport. Defining the molecular mechanism of MHCII presentation during MVA infection provides a basis for improving MVA-based vaccination strategies by aiming for enhanced CD4+ T-cell activation by directing antigens into the responsible pathways. IMPORTANCE This work contributes significantly to our understanding of the immunogenic properties of pathogens by deciphering antigen processing pathways contributing to efficient activation of antigen-specific CD4+ T cells. We identified autophagosome formation, proteasomal activity, and lysosomal integrity as being crucial for endogenous CD4+ T-cell activation. Since poxvirus vectors such as MVA are already used in clinical trials as recombinant vaccines, the data provide important information for the future design of optimized poxviral vaccines for the study of advanced immunotherapy options. PMID:25520512

Infection-induced regulation of NK cells by macrophages and collagen at the lymph node subcapsular sinus

PubMed Central

Coombes, Janine L.; Han, Seong-Ji; van Rooijen, Nico; Raulet, David H.; Robey, Ellen A.

2012-01-01

Summary Infection leads to heightened activation of natural killer (NK) cells, a process that likely involves direct cell-to-cell contact, but how this occurs in vivo is poorly understood. We have used two-photon laser-scanning microscopy in conjunction with Toxoplasma gondii-mouse infection models to address this question. We found that NK cells accumulated in the subcapsular region of the lymph node following infection where they formed low motility contacts with collagen fibers and CD169+ macrophages. We provide evidence that interactions with collagen regulate NK cell migration, whereas CD169+ macrophages increase the activation state of NK cells. Interestingly, a subset of CD169+ macrophages that co-express the inflammatory monocyte marker Ly6C had the most potent ability to activate NK cells. Our data reveal pathways through which NK cell migration and function are regulated following infection, and identify an important accessory cell population for activation of NK cell responses in lymph nodes. PMID:22840403

Biodesulfurization of gas oil using inorganic supports biomodified with metabolically active cells immobilized by adsorption.

PubMed

Dinamarca, M Alejandro; Ibacache-Quiroga, C; Baeza, P; Galvez, S; Villarroel, M; Olivero, P; Ojeda, J

2010-04-01

The immobilization of Pseudomonas stutzeri using adsorption on different inorganic supports was studied in relation to the number of adsorbed cells, metabolic activity and biodesulfurization (BDS). The electrophoretic migration (EM) measurements and Tetrazolioum (TTC) method were used to evaluate adsorption and metabolic activity. Results indicate that maximal immobilization was obtained with an initial load of 14 x 10(8) cells mL(-1) for Al and Sep, whereas Ti requires 20 x 10(8) cells mL(-1). The highest interaction was observed in the P. stutzeri/Si and P. stutzeri/Sep biocatalysts. The IEP values and metabolic activities indicate that P. stutzeri change the surface of supports and maintains metabolic activity. A direct relation between BDS activity and the adsorption capacity of the bacterial cells was observed at the adsorption/desorption equilibrium level. The biomodification of inorganic supports by the adsorption process increases the bioavailability of sulphur substrates for bacterial cells, improving BDS activity. Copyright 2009 Elsevier Ltd. All rights reserved.

Active matter, then and now.

PubMed

Keller, Evelyn Fox

2016-09-01

Historically, living was divided from dead, inert matter by its autonomous activity. Today, a number of materials not themselves alive are characterized as having inherent activity, and this activity has become the subject of a hot new field of physics, "Active Matter", or "Soft matter become alive." For active matter scientists, the relation of physics to biology is guaranteed in one direction by the assertion that the cell is a material, and hence its study can be considered a branch of material science, and in the other direction, by the claim that the physical dynamics of this material IS what brings the cell to life, and therefore its study is a proper branch of biology. I will examine these claims in relation to the concerns of nineteenth century scientists on the one hand, and on the other, in relation to future prospects of the division between animate and inanimate.

Memoryless self-reinforcing directionality in endosomal active transport within living cells

NASA Astrophysics Data System (ADS)

Chen, Kejia; Wang, Bo; Granick, Steve

2015-06-01

In contrast to Brownian transport, the active motility of microbes, cells, animals and even humans often follows another random process known as truncated Lévy walk. These stochastic motions are characterized by clustered small steps and intermittent longer jumps that often extend towards the size of the entire system. As there are repeated suggestions, although disagreement, that Lévy walks have functional advantages over Brownian motion in random searching and transport kinetics, their intentional engineering into active materials could be useful. Here, we show experimentally in the classic active matter system of intracellular trafficking that Brownian-like steps self-organize into truncated Lévy walks through an apparent time-independent positive feedback such that directional persistence increases with the distance travelled persistently. A molecular model that allows the maximum output of the active propelling forces to fluctuate slowly fits the experiments quantitatively. Our findings offer design principles for programming efficient transport in active materials.

Cdk1 activity acts as a quantitative platform for coordinating cell cycle progression with periodic transcription

PubMed Central

Banyai, Gabor; Baïdi, Feriel; Coudreuse, Damien; Szilagyi, Zsolt

2016-01-01

Cell proliferation is regulated by cyclin-dependent kinases (Cdks) and requires the periodic expression of particular gene clusters in different cell cycle phases. However, the interplay between the networks that generate these transcriptional oscillations and the core cell cycle machinery remains largely unexplored. In this work, we use a synthetic regulable Cdk1 module to demonstrate that periodic expression is governed by quantitative changes in Cdk1 activity, with different clusters directly responding to specific activity levels. We further establish that cell cycle events neither participate in nor interfere with the Cdk1-driven transcriptional program, provided that cells are exposed to the appropriate Cdk1 activities. These findings contrast with current models that propose self-sustained and Cdk1-independent transcriptional oscillations. Our work therefore supports a model in which Cdk1 activity serves as a quantitative platform for coordinating cell cycle transitions with the expression of critical genes to bring about proper cell cycle progression. PMID:27045731

The regulation of progesterone receptor by 17 beta estradiol and tamoxifen in the Zr-75-1 human breast cancer cell line in defined medium.

PubMed

Allegra, J C; Korat, O; Do, H M; Lippman, M

1981-01-01

The regulation of progesterone receptor by 17 beta estradiol and tamoxifen in the ZR-75-1 human breast cancer cell line in defined medium is described. ZR-75-1 cells maintained in serum free hormone supplemented medium minus estradiol lack progesterone receptor activity. Readdition of estradiol to these cells leads to a marked stimulation of progesterone receptor activity (0 to greater than 100 fmols of specifically bound progesterone per million cells). Tamoxifen (10(-6)M-10(-8)M) does not stimulate progesterone receptor activity in this cell line. The presence of progesterone receptor activity is not directly related to growth. Withdrawal of insulin in the continued presence of estradiol has no effect on progesterone receptor concentration although net cell growth ceases. Conversely, withdrawal of estradiol in the continued presence of insulin induces a cessation of net cell growth accompanied by a loss of all progesterone receptor activity within 3-5 days.

HTLV-1 Tax Functions as a Ubiquitin E3 Ligase for Direct IKK Activation via Synthesis of Mixed-Linkage Polyubiquitin Chains.

PubMed

Wang, Chong; Long, Wenying; Peng, Chao; Hu, Lin; Zhang, Qiong; Wu, Ailing; Zhang, Xiaoqing; Duan, Xiaotao; Wong, Catherine C L; Tanaka, Yuetsu; Xia, Zongping

2016-04-01

The HTLV-1 oncoprotein Tax plays a key role in CD4+ T cell transformation by promoting cell proliferation and survival, mainly through permanent activation of the NK-κB pathway and induction of many NF-κB target genes. Elucidating the underlying molecular mechanism is therefore critical in understanding HTLV-1-mediated transformation. Current studies have suggested multiple but controversial mechanisms regarding Tax-induced IKK activation mainly due to blending of primary Tax-induced IKK activation events and secondary IKK activation events induced by cytokines secreted by the primary Tax-induced IKK-NF-κB activation events. We reconstituted Tax-stimulated IKK activation in a cell-free system to dissect the essential cellular components for primary IKK activation by Tax and studied the underlying biochemical mechanism. We found that Tax is a putative E3 ubiquitin ligase, which, together with UbcH2, UhcH5c, or UbcH7, catalyzes the assembly of free mixed-linkage polyubiquitin chains. These free mixed-linkage polyubiquitin chains are then responsible for direct IKK activation by binding to the NEMO subunit of IKK. Our studies revealed the biochemical function of Tax in the process of IKK activation, which utilizes the minimal cellular ubiquitination components for NF-κB activation.

HTLV-1 Tax Functions as a Ubiquitin E3 Ligase for Direct IKK Activation via Synthesis of Mixed-Linkage Polyubiquitin Chains

PubMed Central

Wang, Chong; Long, Wenying; Peng, Chao; Hu, Lin; Zhang, Qiong; Wu, Ailing; Zhang, Xiaoqing; Duan, Xiaotao; Wong, Catherine C. L.; Tanaka, Yuetsu; Xia, Zongping

2016-01-01

The HTLV-1 oncoprotein Tax plays a key role in CD4+ T cell transformation by promoting cell proliferation and survival, mainly through permanent activation of the NK-κB pathway and induction of many NF-κB target genes. Elucidating the underlying molecular mechanism is therefore critical in understanding HTLV-1-mediated transformation. Current studies have suggested multiple but controversial mechanisms regarding Tax-induced IKK activation mainly due to blending of primary Tax-induced IKK activation events and secondary IKK activation events induced by cytokines secreted by the primary Tax-induced IKK-NF-κB activation events. We reconstituted Tax-stimulated IKK activation in a cell-free system to dissect the essential cellular components for primary IKK activation by Tax and studied the underlying biochemical mechanism. We found that Tax is a putative E3 ubiquitin ligase, which, together with UbcH2, UhcH5c, or UbcH7, catalyzes the assembly of free mixed-linkage polyubiquitin chains. These free mixed-linkage polyubiquitin chains are then responsible for direct IKK activation by binding to the NEMO subunit of IKK. Our studies revealed the biochemical function of Tax in the process of IKK activation, which utilizes the minimal cellular ubiquitination components for NF-κB activation. PMID:27082114

Selling Stem Cells in the USA: Assessing the Direct-to-Consumer Industry.

PubMed

Turner, Leigh; Knoepfler, Paul

2016-08-04

Direct-to-consumer marketing of unapproved stem cell interventions is a well-known phenomenon in countries with lax medical regulations. However, an examination of Internet-based marketing claims revealed widespread promotion of such interventions by businesses based in the United States. Such commercial activity suggests that regulatory agencies must better oversee this marketplace. Copyright © 2016 Elsevier Inc. All rights reserved.

A Myc-driven self-reinforcing regulatory network maintains mouse embryonic stem cell identity

PubMed Central

Fagnocchi, Luca; Cherubini, Alessandro; Hatsuda, Hiroshi; Fasciani, Alessandra; Mazzoleni, Stefania; Poli, Vittoria; Berno, Valeria; Rossi, Riccardo L.; Reinbold, Rolland; Endele, Max; Schroeder, Timm; Rocchigiani, Marina; Szkarłat, Żaneta; Oliviero, Salvatore; Dalton, Stephen; Zippo, Alessio

2016-01-01

Stem cell identity depends on the integration of extrinsic and intrinsic signals, which directly influence the maintenance of their epigenetic state. Although Myc transcription factors play a major role in stem cell self-renewal and pluripotency, their integration with signalling pathways and epigenetic regulators remains poorly defined. We addressed this point by profiling the gene expression and epigenetic pattern in ESCs whose growth depends on conditional Myc activity. Here we show that Myc potentiates the Wnt/β-catenin signalling pathway, which cooperates with the transcriptional regulatory network in sustaining ESC self-renewal. Myc activation results in the transcriptional repression of Wnt antagonists through the direct recruitment of PRC2 on these targets. The consequent potentiation of the autocrine Wnt/β-catenin signalling induces the transcriptional activation of the endogenous Myc family members, which in turn activates a Myc-driven self-reinforcing circuit. Thus, our data unravel a Myc-dependent self-propagating epigenetic memory in the maintenance of ESC self-renewal capacity. PMID:27301576

Classical dendritic cells mediate fibrosis directly via the retinoic acid pathway in severe eye allergy

PubMed Central

Ahadome, Sarah D.; Mathew, Rose; Reyes, Nancy J.; Mettu, Priyatham S.; Cousins, Scott W.; Calder, Virginia L.; Saban, Daniel R.

2016-01-01

Fibrosis is a shared end-stage pathway to lung, liver, and heart failure. In the ocular mucosa (conjunctiva), fibrosis leads to blindness in trachoma, pemphigoid, and allergy. The indirect fibrogenic role of DCs via T cell activation and inflammatory cell recruitment is well documented. However, here we demonstrate that DCs can directly induce fibrosis. In the mouse model of allergic eye disease (AED), classical CD11b+ DCs in the ocular mucosa showed increased activity of aldehyde dehydrogenase (ALDH), the enzyme required for retinoic acid synthesis. In vitro, CD11b+ DC–derived ALDH was associated with 9-cis-retinoic acid ligation to retinoid x receptor (RXR), which induced conjunctival fibroblast activation. In vivo, stimulating RXR led to rapid onset of ocular mucosal fibrosis, whereas inhibiting ALDH activity in DCs or selectively depleting DCs markedly reduced fibrosis. Collectively, these data reveal a profibrotic ALDH-dependent pathway by DCs and uncover a role for DC retinoid metabolism. PMID:27595139

A Myc-driven self-reinforcing regulatory network maintains mouse embryonic stem cell identity.

PubMed

Fagnocchi, Luca; Cherubini, Alessandro; Hatsuda, Hiroshi; Fasciani, Alessandra; Mazzoleni, Stefania; Poli, Vittoria; Berno, Valeria; Rossi, Riccardo L; Reinbold, Rolland; Endele, Max; Schroeder, Timm; Rocchigiani, Marina; Szkarłat, Żaneta; Oliviero, Salvatore; Dalton, Stephen; Zippo, Alessio

2016-06-15

Stem cell identity depends on the integration of extrinsic and intrinsic signals, which directly influence the maintenance of their epigenetic state. Although Myc transcription factors play a major role in stem cell self-renewal and pluripotency, their integration with signalling pathways and epigenetic regulators remains poorly defined. We addressed this point by profiling the gene expression and epigenetic pattern in ESCs whose growth depends on conditional Myc activity. Here we show that Myc potentiates the Wnt/β-catenin signalling pathway, which cooperates with the transcriptional regulatory network in sustaining ESC self-renewal. Myc activation results in the transcriptional repression of Wnt antagonists through the direct recruitment of PRC2 on these targets. The consequent potentiation of the autocrine Wnt/β-catenin signalling induces the transcriptional activation of the endogenous Myc family members, which in turn activates a Myc-driven self-reinforcing circuit. Thus, our data unravel a Myc-dependent self-propagating epigenetic memory in the maintenance of ESC self-renewal capacity.

Recovery of vestibular function following hair cell destruction by streptomycin

NASA Technical Reports Server (NTRS)

Jones, T. A.; Nelson, R. C.

1992-01-01

Can the vestibular periphery of warm-blooded vertebrates recover functionally from severe sensory hair cell loss? Recent findings in birds suggest a mechanism for recovery but in fact no direct functional evidence has been reported. We produced vestibular hair cell lesions using the ototoxic agent streptomycin sulfate (600 mg/kg/day, 8 days, chicks, Gallus domesticus). Compound action potentials of the vestibular nerve were used as a direct measure of peripheral vestibular function. Vestibular thresholds, neural activation latencies and amplitudes were documented. Eight days of drug treatment elevated thresholds significantly (P < 0.001) and eliminated all but remnants of vestibular activity. Virtually complete physiological recovery occurred in all animals studied over a period of 70 days following treatment. Thresholds recovered within two weeks of drug treatment whereas the return of response morphologies including activation latencies and amplitudes required an additional 6-8 weeks.

Active membrane having uniform physico-chemically functionalized ion channels

DOEpatents

Gerald, II, Rex E; Ruscic, Katarina J; Sears, Devin N; Smith, Luis J; Klingler, Robert J; Rathke, Jerome W

2012-09-24

The present invention relates to a physicochemically-active porous membrane for electrochemical cells that purports dual functions: an electronic insulator (separator) and a unidirectional ion-transporter (electrolyte). The electrochemical cell membrane is activated for the transport of ions by contiguous ion coordination sites on the interior two-dimensional surfaces of the trans-membrane unidirectional pores. One dimension of the pore surface has a macroscopic length (1 nm-1000 .mu.m) and is directed parallel to the direction of an electric field, which is produced between the cathode and the anode electrodes of an electrochemical cell. The membrane material is designed to have physicochemical interaction with ions. Control of the extent of the interactions between the ions and the interior pore walls of the membrane and other materials, chemicals, or structures contained within the pores provides adjustability of the ionic conductivity of the membrane.

Direct integrin alphavbeta6-ERK binding: implications for tumour growth.

PubMed

Ahmed, Nuzhat; Niu, Jun; Dorahy, Douglas J; Gu, Xinhua; Andrews, Sarah; Meldrum, Cliff J; Scott, Rodney J; Baker, Mark S; Macreadie, Ian G; Agrez, Michael V

2002-02-21

Blockade of the mitogen-activated protein (MAP) kinase pathway suppresses growth of colon cancer in vivo. Here we demonstrate a direct link between the extracellular signal-regulated kinase ERK2 and the growth-promoting cell adhesion molecule, integrin alphavbeta6, in colon cancer cells. Down-regulation of beta6 integrin subunit expression inhibits tumour growth in vivo and MAP kinase activity in response to serum stimulation. In alphavbeta6-expressing cells ERK2 is bound only to the beta6 subunit. The increase in cytosolic MAP kinase activity upon epidermal growth factor stimulation is all accounted for by beta6-bound ERK. Deletion of the ERK2 binding site on the beta6 cytoplasmic domain inhibits tumour growth and leads to an association between ERK and the beta5 subunit. The physical interaction between integrin alphavbeta6 and ERK2 defines a novel paradigm of integrin-mediated signalling and provides a therapeutic target for cancer treatment.

GBM heterogeneity as a function of variable epidermal growth factor receptor variant III activity.

PubMed

Lindberg, Olle R; McKinney, Andrew; Engler, Jane R; Koshkakaryan, Gayane; Gong, Henry; Robinson, Aaron E; Ewald, Andrew J; Huillard, Emmanuelle; David James, C; Molinaro, Annette M; Shieh, Joseph T; Phillips, Joanna J

2016-11-29

Abnormal activation of the epidermal growth factor receptor (EGFR) due to a deletion of exons 2-7 of EGFR (EGFRvIII) is a common alteration in glioblastoma (GBM). While this alteration can drive gliomagenesis, tumors harboring EGFRvIII are heterogeneous. To investigate the role for EGFRvIII activation in tumor phenotype we used a neural progenitor cell-based murine model of GBM driven by EGFR signaling and generated tumor progenitor cells with high and low EGFRvIII activation, pEGFRHi and pEGFRLo. In vivo, ex vivo, and in vitro studies suggested a direct association between EGFRvIII activity and increased tumor cell proliferation, decreased tumor cell adhesion to the extracellular matrix, and altered progenitor cell phenotype. Time-lapse confocal imaging of tumor cells in brain slice cultures demonstrated blood vessel co-option by tumor cells and highlighted differences in invasive pattern. Inhibition of EGFR signaling in pEGFRHi promoted cell differentiation and increased cell-matrix adhesion. Conversely, increased EGFRvIII activation in pEGFRLo reduced cell-matrix adhesion. Our study using a murine model for GBM driven by a single genetic driver, suggests differences in EGFR activation contribute to tumor heterogeneity and aggressiveness.

Correlation between dielectric property by dielectrophoretic levitation and growth activity of cells exposed to electric field.

PubMed

Hakoda, Masaru; Hirota, Yusuke

2013-09-01

The purpose of this study is to develop a system analyzing cell activity by the dielectrophoresis method. Our previous studies revealed a correlation between the growth activity and dielectric property (Re[K(ω)]) of mouse hybridoma 3-2H3 cells using dielectrophoretic levitation. Furthermore, it was clarified that the differentiation activity of many stem cells could be evaluated by the Re[K(ω)] without differentiation induction. In this paper, 3-2H3 cells exposed to an alternating current (AC) electric field or a direct current (DC) electric field were cultivated, and the influence of damage by the electric field on the growth activity of the cells was examined. To evaluate the activity of the cells by measuring the Re[K(ω)], the correlation between the growth activity and the Re[K(ω)] of the cells exposed to the electric field was examined. The relations between the cell viability, growth activity, and Re[K(ω)] in the cells exposed to the AC electric field were obtained. The growth activity of the cells exposed to the AC electric field could be evaluated by the Re[K(ω)]. Furthermore, it was found that the adverse effects of the electric field on the cell viability and the growth activity were smaller in the AC electric field than the DC electric field.

[Complex estimation of proliferative activity of epithelial cells of the large intestine damaged by polyps and cancer].

PubMed

Nalieskina, L A; Zabarko, L B; Polishchuk, L Z; Oliĭnichenko, G P; Zakhartseva, L M; Koshel', K V

2001-01-01

Peculiarities of mitotic regime and expression of proliferating cell nuclear antigen were investigated in 18 polyps and 35 cases of colorectal cancer. Direct relationship between spectrum and degree of manifestation of proliferative activity, level of morphological malignant tumors and accumulation of oncopathology in the patient pedigrees was established.

Peak firing rates of rat anterodorsal thalamic head direction cells are higher during faster passive rotations.

PubMed

Zugaro, Michaël B; Berthoz, Alain; Wiener, Sidney I

2002-01-01

Head direction cells discharge selectively when the head of the animal is oriented in a specific direction. The goal of this study was to determine how sensory signals arising from passive rotations (e.g., triggered by vestibular stimulation and dynamic visual inputs) influence the responses of anterodorsal thalamic head direction cells in the absence of voluntary movement cues (e.g., motor command, efference copy, and associated kinesthetic signals). Three unrestrained rats consumed water from a reservoir at the center of a circular platform while passively subjected to sinusoidal rotatory oscillations at fast (153 +/- 27 degrees/s, sd) and slow (38 +/- 15 degrees/s) peak velocities. In 14 anterodorsal thalamic head direction cells, the preferred directions, angular response ranges and baseline firing rates remained stable, but the peak firing rates were, on average, 36% higher during the fast rotations (Wilcoxon matched-pairs test, p < 0.001; variation range: +11% to approximately +100%). No cell changed its peak firing rate by less than 10%, while three cells (21%) increased their peak firing rates by more than 50%. The velocity-dependent increase in peak firing rates was similar for left and right rotations, and the skewness of the directional response curves were not significantly different between left and right turns (Wilcoxon matched-pairs tests, n = 14, ns). These results show that sensory signals concerning self-movements modulate the responses of the head direction cells in the absence of active locomotion.

Correction of the DNA repair defect in xeroderma pigmentosum group E by injection of a DNA damage-binding protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keeney, S.; Brody, T.; Linn, S.

1994-04-26

Cells from a subset of patients with the DNA-repair-defective disease xeroderma pigmentosum complementation group E (XP-E) are known to lack a DNA damage-binding (DDB) activity. Purified human DDB protein was injected into XP-E cells to test whether the DNA-repair defect in these cells is caused by a defect in DDB activity. Injected DDB protein stimulated DNA repair to normal levels in those strains that lack the DDB activity but did not stimulate repair in cells from other xeroderma pigmentosum groups or in XP-E cells that contain the activity. These results provide direct evidence that defective DDB activity causes the repairmore » defect in a subset of XP-E patients, which in turn establishes a role for this activity in nucleotide-excision repair in vivo.« less

Activator-inhibitor coupling between Rho signaling and actin assembly make the cell cortex an excitable medium

PubMed Central

Bement, William M.; Leda, Marcin; Moe, Alison M.; Kita, Angela M.; Larson, Matthew E.; Golding, Adriana E.; Pfeuti, Courtney; Su, Kuan-Chung; Miller, Ann L.; Goryachev, Andrew B.; von Dassow, George

2016-01-01

Animal cell cytokinesis results from patterned activation of the small GTPase Rho, which directs assembly of actomyosin in the equatorial cortex. Cytokinesis is restricted to a portion of the cell cycle following anaphase onset in which the cortex is responsive to signals from the spindle. We show that shortly after anaphase onset oocytes and embryonic cells of frogs and echinoderms exhibit cortical waves of Rho activity and F-actin polymerization. The waves are modulated by cyclin-dependent kinase 1 (Cdk1) activity and require the Rho GEF (guanine nucleotide exchange factor), Ect2. Surprisingly, during wave propagation, while Rho activity elicits F-actin assembly, F-actin subsequently inactivates Rho. Experimental and modeling results show that waves represent excitable dynamics of a reaction diffusion system with Rho as the activator and F-actin the inhibitor. We propose that cortical excitability explains fundamental features of cytokinesis including its cell cycle regulation. PMID:26479320

Schwann cells induce cancer cell dispersion and invasion

PubMed Central

Deborde, Sylvie; Lyubchik, Anna; Zhou, Yi; He, Shizhi; McNamara, William F.; Chernichenko, Natalya; Lee, Sei-Young; Barajas, Fernando; Chen, Chun-Hao; Bakst, Richard L.; Vakiani, Efsevia; He, Shuangba; Hall, Alan; Wong, Richard J.

2016-01-01

Nerves enable cancer progression, as cancers have been shown to extend along nerves through the process of perineural invasion, which carries a poor prognosis. Furthermore, the innervation of some cancers promotes growth and metastases. It remains unclear, however, how nerves mechanistically contribute to cancer progression. Here, we demonstrated that Schwann cells promote cancer invasion through direct cancer cell contact. Histological evaluation of murine and human cancer specimens with perineural invasion uncovered a subpopulation of Schwann cells that associates with cancer cells. Coculture of cancer cells with dorsal root ganglion extracts revealed that Schwann cells direct cancer cells to migrate toward nerves and promote invasion in a contact-dependent manner. Upon contact, Schwann cells induced the formation of cancer cell protrusions in their direction and intercalated between the cancer cells, leading to cancer cell dispersion. The formation of these processes was dependent on Schwann cell expression of neural cell adhesion molecule 1 (NCAM1) and ultimately promoted perineural invasion. Moreover, NCAM1-deficient mice showed decreased neural invasion and less paralysis. Such Schwann cell behavior reflects normal Schwann cell programs that are typically activated in nerve repair but are instead exploited by cancer cells to promote perineural invasion and cancer progression. PMID:26999607

Construction and Quantitative Validation of Chicken CXCR4 Expression Reporter.

PubMed

Es-Haghi, Masoumeh; Bassami, Mohammadreza; Dehghani, Hesam

2016-03-01

Site directional migration is an important biological event and an essential behavior for latent migratory cells. A migratory cell maintains its motility, survival, and proliferation abilities by a network of signaling pathways where CXCR4/SDF signaling route plays crucial role for directed homing of a polarized cell. The chicken embryo due to its specific vasculature modality has been used as a valuable model for organogenesis, migration, cancer, and metastasis. In this research, the regulatory regions of chicken CXCR4 gene have been characterized in a chicken hematopoietic lymphoblast cell line (MSB1). A region extending from -2000 bp upstream of CXCR4 gene to +68 after its transcriptional start site, in addition to two other mutant fragments were constructed and cloned in a promoter-less reporter vector. Promoter activity was analyzed by quantitative real-time RT-PCR and flow cytometry techniques. Our findings show that the full sequence from -2000 to +68 bp of CXCR4 regulatory region is required for maximum promoter functionality, while the mutant CXCR4 promoter fragments show a partial promoter activity. The chicken CXCR4 promoter validated in this study could be used for characterization of directed migratory cells in chicken development and disease models.

A 2,5-Dihydroxybenzoic Acid–Gelatin Conjugate: The Synthesis, Antiviral Activity and Mechanism of Antiviral Action Against Two Alphaherpesviruses

PubMed Central

Lisov, Alexander; Vrublevskaya, Veronika; Lisova, Zoy; Leontievsky, Alexey; Morenkov, Oleg

2015-01-01

Various natural and synthetic polyanionic polymers with different chemical structures are known to exhibit potent antiviral activity in vitro toward a variety of enveloped viruses and may be considered as promising therapeutic agents. A water-soluble conjugate of 2,5-dihydroxybezoic acid (2,5-DHBA) with gelatin was synthesized by laccase-catalyzed oxidation of 2,5-DHBA in the presence of gelatin, and its antiviral activity against pseudorabies virus (PRV) and bovine herpesvirus type 1 (BoHV-1), two members of the Alphaherpesvirinae subfamily, was studied. The conjugate produced no direct cytotoxic effect on cells, and did not inhibit cell growth at concentrations up to 1000 µg/mL. It exhibited potent antiviral activity against PRV (IC50, 1.5–15 µg/mL for different virus strains) and BoHV-1 (IC50, 0.5–0.7 µg/mL). When present during virus adsorption, the conjugate strongly inhibited the attachment of PRV and BoHV-1 to cells. The 2,5-DHBA–gelatin conjugate had no direct virucidal effect on the viruses and did not influence their penetration into cells, cell-to-cell spread, production of infectious virus particles in cells, and expression of PRV glycoproteins E and B. The results indicated that the 2,5-DHBA–gelatin conjugate strongly inhibits the adsorption of alphaherpesviruses to cells and can be a promising synthetic polymer for the development of antiviral formulations against alphaherpesvirus infections. PMID:26501311

PDGF-A suppresses contact inhibition during directional collective cell migration.

PubMed

Nagel, Martina; Winklbauer, Rudolf

2018-06-08

The leading edge mesendoderm (LEM) of the Xenopus gastrula moves as an aggregate by collective migration. However, LEM cells on fibronectin in vitro show contact inhibition of locomotion by quickly retracting lamellipodia upon mutual contact. We found that a fibronectin-integrin-syndecan module acts between p21-activated kinase-1 upstream and ephrinB1 downstream to promote the contact-induced collapse of lamellipodia. To function in this module, fibronectin has to be present as puncta on the surface of LEM cells. To overcome contact inhibition in LEM cell aggregates, PDGF-A deposited in the endogenous substratum of LEM migration blocks the fibronectin-integrin-syndecan module at the integrin level. This stabilizes lamellipodia preferentially in the direction of normal LEM movement and supports cell orientation and the directional migration of the coherent LEM cell mass. © 2018. Published by The Company of Biologists Ltd.

An Inducible Endothelial Cell Surface Glycoprotein Mediates Melanoma Adhesion

NASA Astrophysics Data System (ADS)

Rice, G. Edgar; Bevilacqua, Michael P.

1989-12-01

Hematogenous metastasis requires the arrest and extravasation of blood-borne tumor cells, possibly involving direct adhesive interactions with vascular endothelium. Cytokine activation of cultured human endothelium increases adhesion of melanoma and carcinoma cell lines. An inducible 110-kD endothelial cell surface glycoprotein, designated INCAM-110, appears to mediate adhesion of melanoma cells. In addition, an inducible endothelial receptor for neutrophils, ELAM-1, supports the adhesion of a human colon carcinoma cell line. Thus, activation of vascular endothelium in vivo that results in increased expression of INCAM-110 and ELAM-1 may promote tumor cell adhesion and affect the incidence and distribution of metastases.

Physiological concentrations of interleukin-6 directly promote insulin secretion, signal transduction, nitric oxide release, and redox status in a clonal pancreatic β-cell line and mouse islets.

PubMed

da Silva Krause, Mauricio; Bittencourt, Aline; Homem de Bittencourt, Paulo Ivo; McClenaghan, Neville H; Flatt, Peter R; Murphy, Colin; Newsholme, Philip

2012-09-01

Interleukin-6 (IL6) has recently been reported to promote insulin secretion in a glucagon-like peptide-1-dependent manner. Herein, the direct effects of IL6 (at various concentrations from 0 to 1000 pg/ml) on pancreatic β-cell metabolism, AMP-activated protein kinase (AMPK) signaling, insulin secretion, nitrite release, and redox status in a rat clonal β-cell line and mouse islets are reported. Chronic insulin secretion (in μg/mg protein per 24  h) was increased from 128·7±7·3 (no IL6) to 178·4±7·7 (at 100  pg/ml IL6) in clonal β-cells and increased significantly in islets incubated in the presence of 5·5  mM glucose for 2  h, from 0·148 to 0·167±0·003  ng/islet. Pretreatment with IL6 also induced a twofold increase in basal and nutrient-stimulated insulin secretion in subsequent 20 min static incubations. IL6 enhanced both glutathione (GSH) and glutathione disulphide (GSSG) by nearly 20% without changing intracellular redox status (GSSG/GSH). IL6 dramatically increased iNOS expression (by ca. 100-fold) with an accompanying tenfold rise in nitrite release in clonal β-cells. Phosphorylated AMPK levels were elevated approximately twofold in clonal β-cells and mouse islet cells. Calmodulin-dependent protein kinase kinase levels (CaMKK), an upstream kinase activator of AMPK, were also increased by 50% after IL6 exposure (in β-cells and islets). Our data have demonstrated that IL6 can stimulate β-cell-dependent insulin secretion via direct cell-based mechanisms. AMPK, CaMKK (an upstream kinase activator of AMPK), and the synthesis of nitric oxide appear to alter cell metabolism to benefit insulin secretion. In summary, IL6 exerts positive effects on β-cell signaling, metabolism, antioxidant status, and insulin secretion.

Global transcriptomic analysis of induced cardiomyocytes predicts novel regulators for direct cardiac reprogramming.

PubMed

Talkhabi, Mahmood; Razavi, Seyed Morteza; Salari, Ali

2017-06-01

Heart diseases are the most significant cause of morbidity and mortality in the world. De novo generated cardiomyocytes (CMs) are a great cellular source for cell-based therapy and other potential applications. Direct cardiac reprogramming is the newest method to produce CMs, known as induced cardiomyocytes (iCMs). During a direct cardiac reprogramming, also known as transdifferentiation, non-cardiac differentiated adult cells are reprogrammed to cardiac identity by forced expression of cardiac-specific transcription factors (TFs) or microRNAs. To this end, many different combinations of TFs (±microRNAs) have been reported for direct reprogramming of mouse or human fibroblasts to iCMs, although their efficiencies remain very low. It seems that the investigated TFs and microRNAs are not sufficient for efficient direct cardiac reprogramming and other cardiac specific factors may be required for increasing iCM production efficiency, as well as the quality of iCMs. Here, we analyzed gene expression data of cardiac fibroblast (CFs), iCMs and adult cardiomyocytes (aCMs). The up-regulated and down-regulated genes in CMs (aCMs and iCMs) were determined as CM and CF specific genes, respectively. Among CM specific genes, we found 153 transcriptional activators including some cardiac and non-cardiac TFs that potentially activate the expression of CM specific genes. We also identified that 85 protein kinases such as protein kinase D1 (PKD1), protein kinase A (PRKA), calcium/calmodulin-dependent protein kinase (CAMK), protein kinase C (PRKC), and insulin like growth factor 1 receptor (IGF1R) that are strongly involved in establishing CM identity. CM gene regulatory network constructed using protein kinases, transcriptional activators and intermediate proteins predicted some new transcriptional activators such as myocyte enhancer factor 2A (MEF2A) and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A), which may be required for qualitatively and quantitatively efficient direct cardiac reprogramming. Taken together, this study provides new insights into the complexity of cell fate conversion and better understanding of the roles of transcriptional activators, signaling pathways and protein kinases in increasing the efficiency of direct cardiac reprogramming and maturity of iCMs.

Severe necroinflammatory reaction caused by natural killer cell-mediated Fas/Fas ligand interaction and dendritic cells in human hepatocyte chimeric mouse.

PubMed

Okazaki, Akihito; Hiraga, Nobuhiko; Imamura, Michio; Hayes, C Nelson; Tsuge, Masataka; Takahashi, Shoichi; Aikata, Hiroshi; Abe, Hiromi; Miki, Daiki; Ochi, Hidenori; Tateno, Chise; Yoshizato, Katsutoshi; Ohdan, Hideki; Chayama, Kazuaki

2012-08-01

The necroinflammatory reaction plays a central role in hepatitis B virus (HBV) elimination. Cluster of differentiation (CD)8-positive cytotoxic T lymphocytes (CTLs) are thought to be a main player in the elimination of infected cells, and a recent report suggests that natural killer (NK) cells also play an important role. Here, we demonstrate the elimination of HBV-infected hepatocytes by NK cells and dendritic cells (DCs) using urokinase-type plasminogen activator/severe combined immunodeficiency mice, in which the livers were highly repopulated with human hepatocytes. After establishing HBV infection, we injected human peripheral blood mononuclear cells (PBMCs) into the mice and analyzed liver pathology and infiltrating human immune cells with flow cytometry. Severe hepatocyte degeneration was observed only in HBV-infected mice transplanted with human PBMCs. We provide the first direct evidence that massive liver cell death can be caused by Fas/Fas ligand (FasL) interaction provided by NK cells activated by DCs. Treatment of mice with anti-Fas antibody completely prevented severe hepatocyte degeneration. Furthermore, severe hepatocyte death can be prevented by depletion of DCs, whereas depletion of CD8-positive CTLs did not disturb the development of massive liver cell apoptosis. Our findings provide the first direct evidence that DC-activated NK cells induce massive HBV-infected hepatocyte degeneration through the Fas/FasL system and may indicate new therapeutic implications for acute severe/fulminant hepatitis B. Copyright © 2012 American Association for the Study of Liver Diseases.

ELECTROCHEMISTRY AND ON-CELL REFORMATION MODELING FOR SOLID OXIDE FUEL CELL STACKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Recknagle, Kurtis P.; Jarboe, Daniel T.; Johnson, Kenneth I.

2007-01-16

ABSTRACT Providing adequate and efficient cooling schemes for solid-oxide-fuel-cell (SOFC) stacks continues to be a challenge coincident with the development of larger, more powerful stacks. The endothermic steam-methane reformation reaction can provide cooling and improved system efficiency when performed directly on the electrochemically active anode. Rapid kinetics of the endothermic reaction typically causes a localized temperature depression on the anode near the fuel inlet. It is desirable to extend the endothermic effect over more of the cell area and mitigate the associated differences in temperature on the cell to alleviate subsequent thermal stresses. In this study, modeling tools validated formore » the prediction of fuel use, on-cell methane reforming, and the distribution of temperature within SOFC stacks, are employed to provide direction for modifying the catalytic activity of anode materials to control the methane conversion rate. Improvements in thermal management that can be achieved through on-cell reforming is predicted and discussed. Two operating scenarios are considered: one in which the methane fuel is fully pre-reformed, and another in which a substantial percentage of the methane is reformed on-cell. For the latter, a range of catalytic activity is considered and the predicted thermal effects on the cell are presented. Simulations of the cell electrochemical and thermal performance with and without on-cell reforming, including structural analyses, show a substantial decrease in thermal stresses for an on-cell reforming case with slowed methane conversion.« less

Suppression of Brain Mast Cells Degranulation Inhibits Microglial Activation and Central Nervous System Inflammation.

PubMed

Dong, Hongquan; Zhang, Xiang; Wang, Yiming; Zhou, Xiqiao; Qian, Yanning; Zhang, Shu

2017-03-01

Brain inflammation has a critical role in the pathophysiology of brain diseases. Microglia, the resident immune cells in the brain, play an important role in brain inflammation, while brain mast cells are the "first responder" in the injury rather than microglia. Functional aspects of mast cell-microglia interactions remain poorly understood. Our results demonstrated that site-directed injection of the "mast cell degranulator" compound 48/80 (C48/80) in the hypothalamus induced mast cell degranulation, microglial activation, and inflammatory factor production, which initiated the acute brain inflammatory response. "Mast cell stabilizer" disodium cromoglycate (cromolyn) inhibited this effect, including decrease of inflammatory cytokines, reduced microglial activation, inhibition of MAPK and AKT pathways, and repression of protein expression of histamine receptor 1 (H 1 R), histamine receptor 4 (H 4 R), protease-activated receptor 2 (PAR2), and toll-like receptor 4 (TLR4) in microglia. We also demonstrated that C48/80 had no effect on microglial activation in mast cell-deficient Kit W-sh/W-sh mice. These results implicate that activated brain mast cells trigger microglial activation and stabilization of mast cell inhibits microglial activation-induced central nervous system (CNS) inflammation. Interactions between mast cells and microglia could constitute a new and unique therapeutic target for CNS immune inflammation-related diseases.

Information processing in the hemisphere of the cerebellar cortex for control of wrist movement

PubMed Central

Tomatsu, Saeka; Ishikawa, Takahiro; Tsunoda, Yoshiaki; Lee, Jongho; Hoffman, Donna S.

2015-01-01

A region of cerebellar lobules V and VI makes strong loop connections with the primary motor (M1) and premotor (PM) cortical areas and is assumed to play essential roles in limb motor control. To examine its functional role, we compared the activities of its input, intermediate, and output elements, i.e., mossy fibers (MFs), Golgi cells (GoCs), and Purkinje cells (PCs), in three monkeys performing wrist movements in two different forearm postures. The results revealed distinct steps of information processing. First, MF activities displayed temporal and directional properties that were remarkably similar to those of M1/PM neurons, suggesting that MFs relay near copies of outputs from these motor areas. Second, all GoCs had a stereotyped pattern of activity independent of movement direction or forearm posture. Instead, GoC activity resembled an average of all MF activities. Therefore, inhibitory GoCs appear to provide a filtering function that passes only prominently modulated MF inputs to granule cells. Third, PCs displayed highly complex spatiotemporal patterns of activity, with coordinate frames distinct from those of MF inputs and directional tuning that changed abruptly before movement onset. The complexity of PC activities may reflect rapidly changing properties of the peripheral motor apparatus during movement. Overall, the cerebellar cortex appears to transform a representation of outputs from M1/PM into different movement representations in a posture-dependent manner and could work as part of a forward model that predicts the state of the peripheral motor apparatus. PMID:26467515

Effects of deuterium oxide and galvanic vestibular stimulation on visual cortical cell function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reinis, S.; Landolt, J.P.; Weiss, D.S.

1984-03-01

The spontaneous and evoked unit activities of complex visual cortical cells were recorded from Brodmann's area 18 in immobilized, unanesthetized cats before, during, and after stimulation of the vestibular system. The vestibular system was stimulated by intravenous injection of deuterium oxide (D2O)--a noted nystagmogenic agent--or by direct galvanic stimulation of the labyrinth. Measures of the receptive-field areas, poststimulus time histograms, directional preferences, and the optimal speed of the light bar stimulating the cell were obtained before and after the application of D2O. Directional preferences were determined in a novel manner, using a method derived from a hierarchical clustering technique. Datamore » were collected and analyzed from a) visual cortical cells in cats with intact labyrinths, b) visual cortical cells in cats following bilateral labrinthectomies, and c) nonvisual cortical cells in cats with intact labyrinths. The other cellular characteristics were also altered by the D2O. Galvanic stimulation of the labyrinth resembles, in its effects, the injection of D2O. In labyrinth-intact cats, the time course of area 18 spontaneous activity dramatically increased 30 min or more after D2O was administered. It peaked 2-3 h later and still had not returned to preinjection levels even 7 h after the D2O administration. In bilaterally labyrinthectomized cats, the spontaneous activity of the visual cells did not change following D2O administration. In nonvisual cells from labyrinth-intact cats, the spontaneous activity demonstrated a slight but significant decrease over time after D2O injection. In pilot studies, the cats were injected with D2O. Within 8-10 min afterward, signs of positional nystagmus commenced; and within 30 min, problems in maintaining balance were noted. This continued for 7-8 h before disappearing. In the labyrinthectomized animals, such effects were not observed.« less

How Does Plasma Activated Media Treatment Differ From Direct Cold Plasma Treatment.

PubMed

Attri, Pankaj; Park, Ji Hoon; Ali, Anser; Choi, Eun Ha

2018-04-06

The aim of the paper is to investigate the optimum condition for generation of plasma activated media (PAM), where it can deactivate the cancer cells while minimum damage for normal cells. Over past few years, cold atmospheric plasma-activated media (PAM) have shown its promising application in plasma medicine for treatment of cancer. PAM has a tremendous ability for selective anti-cancer capacity in vitro and in vivo. We have analyzed the radicals in air using the optical emission spectroscopy and in culture media using chemical analysis. Further, we have tested the toxicity of PAM using MTT assay. We observed that more cancer cell death is for the Ar plasma followed by the Ar-N2 plasma, and the least cell death was observed for the Ar-O2 plasma at all treatment times both by direct treatment and through PAM treatment. The concentration of the RNS species is high for Ar-N2 plasma in gas as well as inside the culture media compared to that for pure Ar plasma. However, the difference is significantly less between the Ar plasma treatments and the Ar-N2 plasma treatments, showing that ROS is the main factor contributing to cell death. Among all three feeding gas plasmas the best system is Ar-O2 plasma for direct treatments towards the cancer cells. In addition, the best system for PAM preparation is Ar-N2 at low time treatments (1 min and 2 min) because it has no effect on normal cells, but kills the cancer cells. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Chromatin relaxation-mediated induction of p19INK4d increases the ability of cells to repair damaged DNA.

PubMed

Ogara, María F; Sirkin, Pablo F; Carcagno, Abel L; Marazita, Mariela C; Sonzogni, Silvina V; Ceruti, Julieta M; Cánepa, Eduardo T

2013-01-01

The maintenance of genomic integrity is of main importance to the survival and health of organisms which are continuously exposed to genotoxic stress. Cells respond to DNA damage by activating survival pathways consisting of cell cycle checkpoints and repair mechanisms. However, the signal that triggers the DNA damage response is not necessarily a direct detection of the primary DNA lesion. In fact, chromatin defects may serve as initiating signals to activate those mechanisms. If the modulation of chromatin structure could initiate a checkpoint response in a direct manner, this supposes the existence of specific chromatin sensors. p19INK4d, a member of the INK4 cell cycle inhibitors, plays a crucial role in regulating genomic stability and cell viability by enhancing DNA repair. Its expression is induced in cells injured by one of several genotoxic treatments like cis-platin, UV light or neocarzinostatin. Nevertheless, when exogenous DNA damaged molecules are introduced into the cell, this induction is not observed. Here, we show that p19INK4d is enhanced after chromatin relaxation even in the absence of DNA damage. This induction was shown to depend upon ATM/ATR, Chk1/Chk2 and E2F activity, as is the case of p19INK4d induction by endogenous DNA damage. Interestingly, p19INK4d improves DNA repair when the genotoxic damage is caused in a relaxed-chromatin context. These results suggest that changes in chromatin structure, and not DNA damage itself, is the actual trigger of p19INK4d induction. We propose that, in addition to its role as a cell cycle inhibitor, p19INK4d could participate in a signaling network directed to detecting and eventually responding to chromatin anomalies.

NEU3 Sialidase Is Activated under Hypoxia and Protects Skeletal Muscle Cells from Apoptosis through the Activation of the Epidermal Growth Factor Receptor Signaling Pathway and the Hypoxia-inducible Factor (HIF)-1α

PubMed Central

Scaringi, Raffaella; Piccoli, Marco; Papini, Nadia; Cirillo, Federica; Conforti, Erika; Bergante, Sonia; Tringali, Cristina; Garatti, Andrea; Gelfi, Cecilia; Venerando, Bruno; Menicanti, Lorenzo; Tettamanti, Guido; Anastasia, Luigi

2013-01-01

NEU3 sialidase, a key enzyme in ganglioside metabolism, is activated under hypoxic conditions in cultured skeletal muscle cells (C2C12). NEU3 up-regulation stimulates the EGF receptor signaling pathway, which in turn activates the hypoxia-inducible factor (HIF-1α), resulting in a final increase of cell survival and proliferation. In the same cells, stable overexpression of sialidase NEU3 significantly enhances cell resistance to hypoxia, whereas stable silencing of the enzyme renders cells more susceptible to apoptosis. These data support the working hypothesis of a physiological role played by NEU3 sialidase in protecting cells from hypoxic stress and may suggest new directions in the development of therapeutic strategies against ischemic diseases, particularly of the cerebro-cardiovascular system. PMID:23209287

NEU3 sialidase is activated under hypoxia and protects skeletal muscle cells from apoptosis through the activation of the epidermal growth factor receptor signaling pathway and the hypoxia-inducible factor (HIF)-1α.

PubMed

Scaringi, Raffaella; Piccoli, Marco; Papini, Nadia; Cirillo, Federica; Conforti, Erika; Bergante, Sonia; Tringali, Cristina; Garatti, Andrea; Gelfi, Cecilia; Venerando, Bruno; Menicanti, Lorenzo; Tettamanti, Guido; Anastasia, Luigi

2013-02-01

NEU3 sialidase, a key enzyme in ganglioside metabolism, is activated under hypoxic conditions in cultured skeletal muscle cells (C2C12). NEU3 up-regulation stimulates the EGF receptor signaling pathway, which in turn activates the hypoxia-inducible factor (HIF-1α), resulting in a final increase of cell survival and proliferation. In the same cells, stable overexpression of sialidase NEU3 significantly enhances cell resistance to hypoxia, whereas stable silencing of the enzyme renders cells more susceptible to apoptosis. These data support the working hypothesis of a physiological role played by NEU3 sialidase in protecting cells from hypoxic stress and may suggest new directions in the development of therapeutic strategies against ischemic diseases, particularly of the cerebro-cardiovascular system.

Synapses of Amphids Defective (SAD-A) Kinase Promotes Glucose-stimulated Insulin Secretion through Activation of p21-activated Kinase (PAK1) in Pancreatic β-Cells*

PubMed Central

Nie, Jia; Sun, Chao; Faruque, Omar; Ye, Guangming; Li, Jia; Liang, Qiangrong; Chang, Zhijie; Yang, Wannian; Han, Xiao; Shi, Yuguang

2012-01-01

The p21-activated kinase-1 (PAK1) is implicated in regulation of insulin exocytosis as an effector of Rho GTPases. PAK1 is activated by the onset of glucose-stimulated insulin secretion (GSIS) through phosphorylation of Thr-423, a major activation site by Cdc42 and Rac1. However, the kinase(s) that phosphorylates PAK1 at Thr-423 in islet β-cells remains elusive. The present studies identified SAD-A (synapses of amphids defective), a member of AMP-activated protein kinase-related kinases exclusively expressed in brain and pancreas, as a key regulator of GSIS through activation of PAK1. We show that SAD-A directly binds to PAK1 through its kinase domain. The interaction is mediated by the p21-binding domain (PBD) of PAK1 and requires both kinases in an active conformation. The binding leads to direct phosphorylation of PAK1 at Thr-423 by SAD-A, triggering the onset of GSIS from islet β-cells. Consequently, ablation of PAK1 kinase activity or depletion of PAK1 expression completely abolishes the potentiating effect of SAD-A on GSIS. Consistent with its role in regulating GSIS, overexpression of SAD-A in MIN6 islet β-cells significantly stimulated cytoskeletal remodeling, which is required for insulin exocytosis. Together, the present studies identified a critical role of SAD-A in the activation of PAK1 during the onset of insulin exocytosis. PMID:22669945

Synapses of amphids defective (SAD-A) kinase promotes glucose-stimulated insulin secretion through activation of p21-activated kinase (PAK1) in pancreatic β-Cells.

PubMed

Nie, Jia; Sun, Chao; Faruque, Omar; Ye, Guangming; Li, Jia; Liang, Qiangrong; Chang, Zhijie; Yang, Wannian; Han, Xiao; Shi, Yuguang

2012-07-27

The p21-activated kinase-1 (PAK1) is implicated in regulation of insulin exocytosis as an effector of Rho GTPases. PAK1 is activated by the onset of glucose-stimulated insulin secretion (GSIS) through phosphorylation of Thr-423, a major activation site by Cdc42 and Rac1. However, the kinase(s) that phosphorylates PAK1 at Thr-423 in islet β-cells remains elusive. The present studies identified SAD-A (synapses of amphids defective), a member of AMP-activated protein kinase-related kinases exclusively expressed in brain and pancreas, as a key regulator of GSIS through activation of PAK1. We show that SAD-A directly binds to PAK1 through its kinase domain. The interaction is mediated by the p21-binding domain (PBD) of PAK1 and requires both kinases in an active conformation. The binding leads to direct phosphorylation of PAK1 at Thr-423 by SAD-A, triggering the onset of GSIS from islet β-cells. Consequently, ablation of PAK1 kinase activity or depletion of PAK1 expression completely abolishes the potentiating effect of SAD-A on GSIS. Consistent with its role in regulating GSIS, overexpression of SAD-A in MIN6 islet β-cells significantly stimulated cytoskeletal remodeling, which is required for insulin exocytosis. Together, the present studies identified a critical role of SAD-A in the activation of PAK1 during the onset of insulin exocytosis.

Changes in Escherichia coli cells starved in seawater or grown in seawater-wastewater mixtures.

PubMed Central

Munro, P M; Gauthier, M J; Laumond, F M

1987-01-01

Some metabolic modifications of Escherichia coli cells during starvation in seawater were studied in laboratory microcosms. The apparent die-off of this bacterium under such conditions, as observed by comparing the enumeration of CFU in conventional freshwater media and direct epifluorescence counts, was partially prevented when cells were previously grown in salted organic medium or on seawater-wastewater agar. beta-Galactosidase activity of starved cells disappeared gradually with time, even though some other enzymatic activities, such as that of alkaline phosphatase, increased. Moreover, some modifications of sensitivity to antibiotics, heavy metals, and bacteriophages in seawater- and wastewater-grown cells suggested that the cells undergo structural changes under natural marine conditions. These results provide additional experimental data indicating the possible active adaptation of E. coli cells to seawater. PMID:3116927

A Novel Plasma Membrane-Anchored Protein Regulates Xylem Cell-Wall Deposition through Microtubule-Dependent Lateral Inhibition of Rho GTPase Domains.

PubMed

Sugiyama, Yuki; Wakazaki, Mayumi; Toyooka, Kiminori; Fukuda, Hiroo; Oda, Yoshihisa

2017-08-21

Spatial control of cell-wall deposition is essential for determining plant cell shape [1]. Rho-type GTPases, together with the cortical cytoskeleton, play central roles in regulating cell-wall patterning [2]. In metaxylem vessel cells, which are the major components of xylem tissues, active ROP11 Rho GTPases form oval plasma membrane domains that locally disrupt cortical microtubules, thereby directing the formation of oval pits in secondary cell walls [3-5]. However, the regulatory mechanism that determines the planar shape of active Rho of Plants (ROP) domains is still unknown. Here we show that IQD13 associates with cortical microtubules and the plasma membrane to laterally restrict the localization of ROP GTPase domains, thereby directing the formation of oval secondary cell-wall pits. Loss and overexpression of IQD13 led to the formation of abnormally round and narrow secondary cell-wall pits, respectively. Ectopically expressed IQD13 increased the presence of parallel cortical microtubules by promoting microtubule rescue. A reconstructive approach revealed that IQD13 confines the area of active ROP domains within the lattice of the cortical microtubules, causing narrow ROP domains to form. This activity required the interaction of IQD13 with the plasma membrane. These findings suggest that IQD13 positively regulates microtubule dynamics as well as their linkage to the plasma membrane, which synergistically confines the area of active ROP domains, leading to the formation of oval secondary cell-wall pits. This finding sheds light on the role of microtubule-plasma membrane linkage as a lateral fence that determines the planar shape of Rho GTPase domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interleukin 6 protects pancreatic β cells from apoptosis by stimulation of autophagy.

PubMed

Linnemann, Amelia K; Blumer, Joseph; Marasco, Michelle R; Battiola, Therese J; Umhoefer, Heidi M; Han, Jee Young; Lamming, Dudley W; Davis, Dawn Belt

2017-09-01

IL-6 is a pleiotropic cytokine with complex roles in inflammation and metabolic disease. The role of IL-6 as a pro- or anti-inflammatory cytokine is still unclear. Within the pancreatic islet, IL-6 stimulates secretion of the prosurvival incretin hormone glucagon-like peptide 1 (GLP-1) by α cells and acts directly on β cells to stimulate insulin secretion in vitro Uncovering physiologic mechanisms promoting β-cell survival under conditions of inflammation and stress can identify important pathways for diabetes prevention and treatment. Given the established role of GLP-1 in promoting β-cell survival, we hypothesized that IL-6 may also directly protect β cells from apoptosis. Herein, we show that IL-6 robustly activates signal transducer and activator of transcription 3 (STAT3), a transcription factor that is involved in autophagy. IL-6 stimulates LC3 conversion and autophagosome formation in cultured β cells. In vivo IL-6 infusion stimulates a robust increase in lysosomes in the pancreas that is restricted to the islet. Autophagy is critical for β-cell homeostasis, particularly under conditions of stress and increased insulin demand. The stimulation of autophagy by IL-6 is regulated via multiple complementary mechanisms including inhibition of mammalian target of rapamycin complex 1 (mTORC1) and activation of Akt, ultimately leading to increases in autophagy enzyme production. Pretreatment with IL-6 renders β cells resistant to apoptosis induced by proinflammatory cytokines, and inhibition of autophagy with chloroquine prevents the ability of IL-6 to protect from apoptosis. Importantly, we find that IL-6 can activate STAT3 and the autophagy enzyme GABARAPL1 in human islets. We also see evidence of decreased IL-6 pathway signaling in islets from donors with type 2 diabetes. On the basis of our results, we propose direct stimulation of autophagy as a novel mechanism for IL-6-mediated protection of β cells from stress-induced apoptosis.-Linnemann, A. K., Blumer, J., Marasco, M. R., Battiola, T. J., Umhoefer, H. M., Han, J. Y., Lamming, D. W., Davis, D. B. Interleukin 6 protects pancreatic β cells from apoptosis by stimulation of autophagy. © FASEB.

Antitumor killer lymphocytes in the peripheral blood of a patient with transitional cell carcinoma of the bladder.

PubMed

Kim, C J; Yuasa, T; Kushima, R; Tomoyoshi, T; Seto, A

1998-05-01

Peripheral blood lymphocytes (PBL) from patients with bladder cancer also contain cells possessing cytotoxic activity against autologous tumor cells. These cells are phenotypically heterogenous and include natural killer (NK) and cytotoxic T cells. This study investigated the role of cytotoxic lymphocytes directed against autologous bladder cancer cells. PBL were obtained at intervals before and after surgery and analyzed for cytotoxic activity against autologous bladder cancer cells in 4-hour 51Cr release assay. PBL stimulated with autologous tumor cells were also transformed with human T-lymphotropic virus type-1, establishing a cell line (KB31) which was analyzed for phenotype and cytotoxic activity against the autologous tumor cells. PBL preoperative cytotoxic activity was low, but increased after surgery. Cytotoxic activity was found not only against autologous bladder cancer cells, but also against heterologous bladder cancer (KK-47) and myeloid leukemia (K562) cells, with the highest activity against the heterologous cell lines. The cytotoxic activity of KB31 was 40% against autologous tumor cells 6 weeks after initiation of the cell line, but decreased to 5% by 6 months. This activity was lower than that against the other cell lines, and was similar to that of PBL in short-term culture. Fluorescence-activated cell sorter (FACS) analysis demonstrated that in KB31 cells at 6 weeks, CD8+ cells were dominant, but CD56+ cells predominated at 6 months. These results suggest that the presence of cytotoxic activity in the peripheral blood of the patient was due to both cytotoxic T cells and NK cells. The cytotoxic activity was lowest prior to surgery and increased postoperatively.

A convergent and essential interneuron pathway for Mauthner-cell-mediated escapes.

PubMed

Lacoste, Alix M B; Schoppik, David; Robson, Drew N; Haesemeyer, Martin; Portugues, Ruben; Li, Jennifer M; Randlett, Owen; Wee, Caroline L; Engert, Florian; Schier, Alexander F

2015-06-01

The Mauthner cell (M-cell) is a command-like neuron in teleost fish whose firing in response to aversive stimuli is correlated with short-latency escapes [1-3]. M-cells have been proposed as evolutionary ancestors of startle response neurons of the mammalian reticular formation [4], and studies of this circuit have uncovered important principles in neurobiology that generalize to more complex vertebrate models [3]. The main excitatory input was thought to originate from multisensory afferents synapsing directly onto the M-cell dendrites [3]. Here, we describe an additional, convergent pathway that is essential for the M-cell-mediated startle behavior in larval zebrafish. It is composed of excitatory interneurons called spiral fiber neurons, which project to the M-cell axon hillock. By in vivo calcium imaging, we found that spiral fiber neurons are active in response to aversive stimuli capable of eliciting escapes. Like M-cell ablations, bilateral ablations of spiral fiber neurons largely eliminate short-latency escapes. Unilateral spiral fiber neuron ablations shift the directionality of escapes and indicate that spiral fiber neurons excite the M-cell in a lateralized manner. Their optogenetic activation increases the probability of short-latency escapes, supporting the notion that spiral fiber neurons help activate M-cell-mediated startle behavior. These results reveal that spiral fiber neurons are essential for the function of the M-cell in response to sensory cues and suggest that convergent excitatory inputs that differ in their input location and timing ensure reliable activation of the M-cell, a feedforward excitatory motif that may extend to other neural circuits. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effect of light direction and suspended cell concentrations on algal biofilm growth rates.

PubMed

Schnurr, Peter J; Espie, George S; Allen, D Grant

2014-10-01

Algae biofilms were grown in a semicontinuous flat plate biofilm photobioreactor to study the effects of light direction and suspended algal cell populations on algal biofilm growth. It was determined that, under the growth conditions and biofilm thicknesses studied, light direction had no effect on long-term algal biofilm growth (26 days); however, light direction did affect the concentration of suspended algal cells by influencing the photon flux density in the growth medium in the photobioreactors. This suspended algal cell population affected short-term (7 days) algae cell recruitment and algal biofilm growth, but additional studies showed that enhanced suspended algal cell populations did not affect biofilm growth rates over the long term (26 days). Studying profiles of light transmittance through biofilms as they grew showed that most of the light became attenuated by the biomass after just a few days of growth (88 % after 3 days). The estimated biofilm thicknesses after these few days of growth were approximately 150 μm. The light attenuation data suggests that, although the biofilms grew to 700-900 μm, under these light intensities, only the first few hundred micrometers of the biofilm is receiving enough light to be photosynthetically active. We postulate that this photosynthetically active layer of the biofilm grows adjacent to the light source, while the rest of the biofilm is in a stationary growth phase. The results of this study have implications for algal biofilm photobioreactor design and operation.

A direct GABAergic output from the basal ganglia to frontal cortex

PubMed Central

Saunders, Arpiar; Oldenburg, Ian A.; Berezovskii, Vladimir K.; Johnson, Caroline A.; Kingery, Nathan D.; Elliott, Hunter L.; Xie, Tiao; Gerfen, Charles R.; Sabatini, Bernardo L.

2014-01-01

The basal ganglia (BG) are phylogenetically conserved subcortical nuclei necessary for coordinated motor action and reward learning1. Current models postulate that the BG modulate cerebral cortex indirectly via an inhibitory output to thalamus, bidirectionally controlled by the BG via direct (dSPNs) and indirect (iSPNs) pathway striatal projection neurons2–4. The BG thalamic output sculpts cortical activity by interacting with signals from sensory and motor systems5. Here we describe a direct projection from the globus pallidus externus (GP), a central nucleus of the BG, to frontal regions of the cerebral cortex (FC). Two cell types make up the GP-FC projection, distinguished by their electrophysiological properties, cortical projections and expression of choline acetyltransferase (ChAT), a synthetic enzyme for the neurotransmitter acetylcholine (ACh). Despite these differences, ChAT+ cells, which have been historically identified as an extension of the nucleus basalis (NB), as well as ChAT− cells, release the inhibitory neurotransmitter GABA (γ-aminobutyric acid) and are inhibited by iSPNs and dSPNs of dorsal striatum. Thus GP-FC cells comprise a direct GABAergic/cholinergic projection under the control of striatum that activates frontal cortex in vivo. Furthermore, iSPN inhibition of GP-FC cells is sensitive to dopamine 2 receptor signaling, revealing a pathway by which drugs that target dopamine receptors for the treatment of neuropsychiatric disorders can act in the BG to modulate frontal cortices. PMID:25739505

The NOTCH Ligand JAG1 Regulates GDNF Expression in Sertoli Cells

PubMed Central

Garcia, Thomas X.; Parekh, Parag; Gandhi, Pooja; Sinha, Krishna

2017-01-01

In the seminiferous epithelium of the testis, Sertoli cells are key niche cells directing proliferation and differentiation of spermatogonial stem cells (SSCs) into spermatozoa. Sertoli cells produce glial cell line-derived neurotrophic factor (GDNF), which is essential for SSC self-renewal and progenitor expansion. While the role of GDNF in the testis stem cell niche is established, little is known about how this factor is regulated. Our previous studies on NOTCH activity in Sertoli cells demonstrated a role of this pathway in limiting stem/progenitor cell numbers, thus ultimately downregulating sperm cell output. In this study we demonstrate through a double-mutant mouse model that NOTCH signaling in Sertoli cells functions solely through the canonical pathway. Further, we demonstrate through Dual luciferase assay and chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR) analysis that the NOTCH targets HES1 and HEY1, which are transcriptional repressors, directly downregulate GDNF expression by binding to the Gdnf promoter, thus antagonizing the effects of FSH/cAMP. Finally, we demonstrate that testicular stem/progenitors cells are activating NOTCH signaling in Sertoli cells in vivo and in vitro through the NOTCH ligand JAG1 at their surface, indicating that these cells may ensure their own homeostasis through negative feedback regulation. PMID:28051360

Activation of human B cells by phosphorothioate oligodeoxynucleotides.

PubMed Central

Liang, H; Nishioka, Y; Reich, C F; Pisetsky, D S; Lipsky, P E

1996-01-01

To investigate the potential of DNA to elicit immune responses in man, we examined the capacity of a variety of oligodeoxynucleotides (ODNs) to stimulate highly purified T cell-depleted human peripheral blood B cells. Among 47 ODNs of various sequences tested, 12 phosphorothioate oligodeoxynucleotides (sODNs) induced marked B cell proliferation and Ig production. IL-2 augmented both proliferation and production of IgM, IgG, and IgA, as well as IgM anti-DNA antibodies, but was not necessary for B cell stimulation. Similarly, T cells enhanced stimulation, but were not necessary for B cell activation. After stimulation with the active sODNs, more than 95% of B cells expressed CD25 and CD86. In addition, B cells stimulated with sODNs expressed all six of the major immunoglobulin VH gene families. These results indicate that the human B cell response to sODN is polyclonal. Active sODN coupled to Sepharose beads stimulated B cells as effectively as the free sODN, suggesting that stimulation resulted from engagement of surface receptors. These data indicate that sODNs can directly induce polyclonal activation of human B cells in a T cell-independent manner by engaging as yet unknown B cell surface receptors. PMID:8787674

Tyrosine Phosphorylation of the Guanine Nucleotide Exchange Factor GIV Promotes Activation of PI3K During Cell Migration

PubMed Central

Lin, Changsheng; Ear, Jason; Pavlova, Yelena; Mittal, Yash; Kufareva, Irina; Ghassemian, Majid; Abagyan, Ruben; Garcia-Marcos, Mikel; Ghosh, Pradipta

2014-01-01

GIV (Gα-interacting vesicle-associated protein; also known as Girdin), enhances Akt activation downstream of multiple growth factor– and G-protein–coupled receptors to trigger cell migration and cancer invasion. Here we demonstrate that GIV is a tyrosine phosphoprotein that directly binds to and activates phosphoinositide 3-kinase (PI3K). Upon ligand stimulation of various receptors, GIV was phosphorylated at Tyr1764 and Tyr1798 by both receptor and non-receptor tyrosine kinases. These phosphorylation events enabled direct binding of GIV to the N- and C-terminal SH2 domains of p85α, a regulatory subunit of PI3K, stabilized receptor association with PI3K, and enhanced PI3K activity at the plasma membrane to trigger cell migration. Tyrosine phosphorylation of GIV and its association with p85α increased during metastatic progression of a breast carcinoma. These results suggest a mechanism by which multiple receptors activate PI3K through tyrosine phosphorylation of GIV, thereby making the GIVPI3K interaction a potential therapeutic target within the PI3K-Akt pathway. PMID:21954290

Genotoxic stress-induced activation of Plk3 is partly mediated by Chk2.

PubMed

Xie, Suqing; Wu, Huiyun; Wang, Qi; Kunicki, Jan; Thomas, Raymond O; Hollingsworth, Robert E; Cogswell, John; Dai, Wei

2002-01-01

Polo-like kinase 3 (Plk3, alternatively termed Prk) is involved in the regulation of DNA damage checkpoint as well as in M-phase function. Plk3 physically interacts with p53 and phosphorylates this tumor suppressor protein on serine-20, suggesting that the role of Plk3 in cell cycle progression is mediated, at least in part, through direct regulation of p53. Here we show that Plk3 is rapidly activated by reactive oxygen species in normal diploid fibroblast cells (WI-38), correlating with a subsequent increase in p53 protein level. Plk3 physically interacts with Chk2 and the interaction is enhanced upon DNA damage. In addition, Chk2 immunoprecipitated from cell lysates of Daudi (which expressed little Plk3) is capable of stimulating the kinase activity of purified recombinant Plk3 in vitro, and this stimulation is more pronounced when Plk3 is supplemented with Chk2 immunoprecipitated from Daudi after DNA damage. Furthermore, ectopic expression Chk2 activates cellular Plk3. Together, our studies suggest Chk2 may mediate direct activation of Plk3 in response to genotoxic stresses.

Role of Complement on Broken Surfaces After Trauma.

PubMed

Huber-Lang, Markus; Ignatius, Anita; Brenner, Rolf E

2015-01-01

Activation of both the complement and coagulation cascade after trauma and subsequent local and systemic inflammatory response represent a major scientific and clinical problem. After severe tissue injury and bone fracture, exposure of innate immunity to damaged cells and molecular debris is considered a main trigger of the posttraumatic danger response. However, the effects of cellular fragments (e.g., histones) on complement activation remain enigmatic. Furthermore, direct effects of "broken" bone and cartilage surfaces on the fluid phase response of complement and its interaction with key cells of connective tissues are still unknown. Here, we summarize data suggesting direct and indirect complement activation by extracellular and cellular danger associated molecular patterns. In addition, key complement components and the corresponding receptors (such as C3aR, C5aR) have been detected on "exposed surfaces" of the damaged regions. On a cellular level, multiple effects of complement activation products on osteoblasts, osteoclasts, chondrocytes and mesenchymal stem cells have been found.In conclusion, the complement system may be activated by trauma-altered surfaces and is crucially involved in connective tissue healing and posttraumatic systemic inflammatory response.

Mechanisms regulating plasminogen activators in transformed retinal ganglion cells

PubMed Central

Rock, Nathan; Chintala, Shravan K.

2008-01-01

Irreversible loss of retinal ganglion cells (RGCs) is a major clinical issue in glaucoma, but the mechanisms that lead to RGC death are currently unclear. We have previously reported that elevated levels of tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) cause the death of RGCs in vivo and transformed retinal ganglion cells (RGC-5) in vitro. Yet, it is unclear how secreted proteases such as tPA and uPA directly cause RGCs' death. In this study, by employing RGC-5 cells, we report that tPA and uPA elicit their direct effect through the low-density lipoprotein-related receptor-1 (LRP-1). We also show that blockade of protease-LRP-1 interaction leads to a compete reduction in autocrine synthesis of tPA and uPA, and prevents protease-mediated death of RGC-5 cells. RGC-5 cells were cultured in serum-free medium and treated with 2.0 uM Staurosporine to induce their differentiation. Neurite outgrowth was observed by a phase contrast microscope and quantified by NeuroJ imaging software. Proteolytic activities of tPA and uPA were determined by zymography assays. Cell viability was determined by MTT assays. Compared to untreated RGC-5 cells, cells treated with Staurosporine differentiated, synthesized and secreted elevated levels of tPA and uPA, and underwent cell death. In contrast, when RGC-5 cells were treated with Staurosporine along with the receptor associated protein (RAP), proteolytic activities of both tPA and uPA were significantly reduced. Under these conditions, a significant number of RGC-5 cells survived and showed increased neurite outgrowth. These results indicate that LRP-1 regulates autocrine synthesis of tPA and uPA in RGC-5 cells and suggest that the use of RAP to antagonize the effect of proteases may be a way to prevent RGC death in glaucoma. PMID:18243176

Suppressed PHA activation of T lymphocytes in simulated microgravity is restored by direct activation of protein kinase C

NASA Technical Reports Server (NTRS)

Cooper, D.; Pellis, N. R.; McIntire, L. V. (Principal Investigator)

1998-01-01

Utilizing clinostatic rotating wall vessel (RWV) bioreactors that simulate aspects of microgravity, we found phytohemagglutinin (PHA) responsiveness to be almost completely diminished. Activation marker expression was significantly reduced in RWV cultures. Furthermore, cytokine secretion profiles suggested that monocytes are not as adversely affected by simulated microgravity as T cells. Reduced cell-cell and cell-substratum interactions may play a role in the loss of PHA responsiveness because placing peripheral blood mononuclear cells (PBMC) within small collagen beads did partially restore PHA responsiveness. However, activation of purified T cells with cross-linked CD2/CD28 and CD3/CD28 antibody pairs was completely suppressed in the RWV, suggesting a defect in signal transduction. Activation of purified T cells with PMA and ionomycin was unaffected by RWV culture. Furthermore, sub-mitogenic doses of PMA alone but not ionomycin alone restored PHA responsiveness of PBMC in RWV culture. Thus our data indicate that during polyclonal activation the signaling pathways upstream of PKC activation are sensitive to simulated microgravity.

Different Effects of Human Umbilical Cord Mesenchymal Stem Cells on Glioblastoma Stem Cells by Direct Cell Interaction or Via Released Soluble Factors

PubMed Central

Bajetto, Adriana; Pattarozzi, Alessandra; Corsaro, Alessandro; Barbieri, Federica; Daga, Antonio; Bosio, Alessia; Gatti, Monica; Pisaturo, Valerio; Sirito, Rodolfo; Florio, Tullio

2017-01-01

Glioblastoma (GBM), the most common primary brain tumor in adults, is an aggressive, fast-growing and highly vascularized tumor, characterized by extensive invasiveness and local recurrence. In GBM and other malignancies, cancer stem cells (CSCs) are believed to drive invasive tumor growth and recurrence, being responsible for radio- and chemo-therapy resistance. Mesenchymal stem cells (MSCs) are multipotent progenitors that exhibit tropism for tumor microenvironment mediated by cytokines, chemokines and growth factors. Initial studies proposed that MSCs might exert inhibitory effects on tumor development, although, to date, contrasting evidence has been provided. Different studies reported either MSC anti-tumor activity or their support to tumor growth. Here, we examined the effects of umbilical cord (UC)-MSCs on in vitro GBM-derived CSC growth, by direct cell-to-cell interaction or indirect modulation, via the release of soluble factors. We demonstrate that UC-MSCs and CSCs exhibit reciprocal tropism when co-cultured as 3D spheroids and their direct cell interaction reduces the proliferation of both cell types. Contrasting effects were obtained by UC-MSC released factors: CSCs, cultured in the presence of conditioned medium (CM) collected from UC-MSCs, increased proliferation rate through transient ERK1/2 and Akt phosphorylation/activation. Analysis of the profile of the cytokines released by UC-MSCs in the CM revealed a strong production of molecules involved in inflammation, angiogenesis, cell migration and proliferation, such as IL-8, GRO, ENA-78 and IL-6. Since CXC chemokine receptor 2 (CXCR2), a receptor shared by several of these ligands, is expressed in GBM CSCs, we evaluated its involvement in CSC proliferation induced by UC-MSC-CM. Using the CXCR2 antagonist SB225002, we observed a partial but statistically significant inhibition of CSC proliferation and migration induced by the UC-MSC-released cytokines. Conversely, CXCR2 blockade did not reduce the reciprocal tropism between CSCs and UC-MSCs grown as spheroids. In conclusion, we show that direct (cell-to-cell contact) or indirect (via the release of soluble factors) interactions between GBM CSCs and UC-MSCs in co-culture produce divergent effects on cell growth, invasion and migration, with the former mainly causing an inhibitory response and the latter a stimulatory one, involving a paracrine activation of CXCR2. PMID:29081734

Different Effects of Human Umbilical Cord Mesenchymal Stem Cells on Glioblastoma Stem Cells by Direct Cell Interaction or Via Released Soluble Factors.

PubMed

Bajetto, Adriana; Pattarozzi, Alessandra; Corsaro, Alessandro; Barbieri, Federica; Daga, Antonio; Bosio, Alessia; Gatti, Monica; Pisaturo, Valerio; Sirito, Rodolfo; Florio, Tullio

2017-01-01

Glioblastoma (GBM), the most common primary brain tumor in adults, is an aggressive, fast-growing and highly vascularized tumor, characterized by extensive invasiveness and local recurrence. In GBM and other malignancies, cancer stem cells (CSCs) are believed to drive invasive tumor growth and recurrence, being responsible for radio- and chemo-therapy resistance. Mesenchymal stem cells (MSCs) are multipotent progenitors that exhibit tropism for tumor microenvironment mediated by cytokines, chemokines and growth factors. Initial studies proposed that MSCs might exert inhibitory effects on tumor development, although, to date, contrasting evidence has been provided. Different studies reported either MSC anti-tumor activity or their support to tumor growth. Here, we examined the effects of umbilical cord (UC)-MSCs on in vitro GBM-derived CSC growth, by direct cell-to-cell interaction or indirect modulation, via the release of soluble factors. We demonstrate that UC-MSCs and CSCs exhibit reciprocal tropism when co-cultured as 3D spheroids and their direct cell interaction reduces the proliferation of both cell types. Contrasting effects were obtained by UC-MSC released factors: CSCs, cultured in the presence of conditioned medium (CM) collected from UC-MSCs, increased proliferation rate through transient ERK1/2 and Akt phosphorylation/activation. Analysis of the profile of the cytokines released by UC-MSCs in the CM revealed a strong production of molecules involved in inflammation, angiogenesis, cell migration and proliferation, such as IL-8, GRO, ENA-78 and IL-6. Since CXC chemokine receptor 2 (CXCR2), a receptor shared by several of these ligands, is expressed in GBM CSCs, we evaluated its involvement in CSC proliferation induced by UC-MSC-CM. Using the CXCR2 antagonist SB225002, we observed a partial but statistically significant inhibition of CSC proliferation and migration induced by the UC-MSC-released cytokines. Conversely, CXCR2 blockade did not reduce the reciprocal tropism between CSCs and UC-MSCs grown as spheroids. In conclusion, we show that direct (cell-to-cell contact) or indirect (via the release of soluble factors) interactions between GBM CSCs and UC-MSCs in co-culture produce divergent effects on cell growth, invasion and migration, with the former mainly causing an inhibitory response and the latter a stimulatory one, involving a paracrine activation of CXCR2.

Cellular cooperation in lymphocyte activation. III. B-cell helper effect in the enhancement of T-cell response.

PubMed

Kasahara, T; Kin, K; Itoh, Y; Kawai, T; Kano, Y; Shioiri-Nakano, K

1979-01-01

T and B cells were purified from human tonsil and peripheral blood by the removal of phagocytic cells, followed by filtration through a nylon fiber column (NC) and E-rosette formation. Purified T and B cells contained less than 1% of other cell types. The responses of T cells to concanavalin A (Con A) and soluble protein A were greatly enhanced in the presence of autologous B cells. Participation of B cells in T-cell enhancement was confirmed by the following observations: (a) purified B copulation, which was separated further from adherent B cells, retained its enhancing activity. (b) Another adherent cell-free B-cell preparation, which was purified from the NC-passed fraction, and (c) no T lymphoid but some B lymphoid cell lines, elicited strong T-cell enhancement. It was also found that the enhancing capacity of B cells required no metabolic activity, but rather an intact cell form and direct cell-to-cell contact with responding cells. The stimulatory determinants on B cells were resistant to trypsin and neuraminidase treatment. In this paper a hypothesis will be presented that at least two signals are prerequisite for the effective activation of T cells.

Moderate and strong static magnetic fields directly affect EGFR kinase domain orientation to inhibit cancer cell proliferation

PubMed Central

Wang, Wenchao; Li, Zhiyuan; Liu, Juanjuan; Yang, Xingxing; Ji, Xinmiao; Luo, Yan; Hu, Chen; Hou, Yubin; He, Qianqian; Fang, Jun; Wang, Junfeng; Liu, Qingsong; Li, Guohui; Lu, Qingyou; Zhang, Xin

2016-01-01

Static magnetic fields (SMFs) can affect cell proliferation in a cell-type and intensity-dependent way but the mechanism remains unclear. At the same time, although the diamagnetic anisotropy of proteins has been proposed decades ago, the behavior of isolated proteins in magnetic fields has not been directly observed. Here we show that SMFs can affect isolated proteins at the single molecular level in an intensity-dependent manner. We found that Epidermal Growth Factor Receptor (EGFR), a protein that is overexpressed and highly activated in multiple cancers, can be directly inhibited by SMFs. Using Liquid-phase Scanning Tunneling Microscopy (STM) to examine pure EGFR kinase domain proteins at the single molecule level in solution, we observed orientation changes of these proteins in response to SMFs. This may interrupt inter-molecular interactions between EGFR monomers, which are critical for their activation. In molecular dynamics (MD) simulations, 1-9T SMFs caused increased probability of EGFR in parallel with the magnetic field direction in an intensity-dependent manner. A superconducting ultrastrong 9T magnet reduced proliferation of CHO-EGFR cells (Chinese Hamster Ovary cells with EGFR overexpression) and EGFR-expressing cancer cell lines by ~35%, but minimally affected CHO cells. We predict that similar effects of magnetic fields can also be applied to some other proteins such as ion channels. Our paper will help clarify some dilemmas in this field and encourage further investigations in order to achieve a better understanding of the biological effects of SMFs. PMID:27223425

New physiologically-relevant liver tissue model based on hierarchically cocultured primary rat hepatocytes with liver endothelial cells.

PubMed

Xiao, Wenjin; Perry, Guillaume; Komori, Kikuo; Sakai, Yasuyuki

2015-11-01

To develop an in vitro liver tissue equivalent, hepatocytes should be cocultured with liver non-parenchymal cells to mimic the in vivo physiological microenvironments. In this work, we describe a physiologically-relevant liver tissue model by hierarchically organizing layers of primary rat hepatocytes and human liver sinusoidal endothelial cells (TMNK-1) on an oxygen-permeable polydimethylsiloxane (PDMS) membrane, which facilitates direct oxygenation by diffusion through the membrane. This in vivo-mimicking hierarchical coculture was obtained by simply proceeding the overlay of TMNK-1 cells on the hepatocyte layer re-formed on the collagen immobilized PDMS membranes. The comparison of hepatic functionalities was achieved between coculture and sandwich culture with Matrigel, in the presence and absence of direct oxygenation. A complete double-layered structure of functional liver cells with vertical contact between hepatocytes and TMNK-1 was successfully constructed in the coculture with direct oxygen supply and was well-maintained for 14 days. The hepatocytes in this hierarchical culture exhibited improved survival, functional bile canaliculi formation, cellular level polarization and maintenance of metabolic activities including Cyp1A1/2 activity and albumin production. By contrast, the two cell populations formed discontinuous monolayers on the same surfaces in the non-oxygen-permeable cultures. These results demonstrate that (i) the direct oxygenation through the PDMS membranes enables very simple formation of a hierarchical structure consisting of a hepatocyte layer and a layer of TMNK-1 and (ii) we may include other non-parenchymal cells in this format easily, which can be widely applicable to other epithelial organs.

Apigenin blocks IKKα activation and suppresses prostate cancer progression

PubMed Central

Shukla, Sanjeev; Kanwal, Rajnee; Shankar, Eswar; Datt, Manish; Chance, Mark R.; Fu, Pingfu; MacLennan, Gregory T.; Gupta, Sanjay

2015-01-01

IKKα has been implicated as a key regulator of oncogenesis and driver of the metastatic process; therefore is regarded as a promising therapeutic target in anticancer drug development. In spite of the progress made in the development of IKK inhibitors, no potent IKKα inhibitor(s) have been identified. Our multistep approach of molecular modeling and direct binding has led to the identification of plant flavone apigenin as a specific IKKα inhibitor. Here we report apigenin, in micro molar range, inhibits IKKα kinase activity, demonstrates anti-proliferative and anti-invasive activities in functional cell based assays and exhibits anticancer efficacy in experimental tumor model. We found that apigenin directly binds with IKKα, attenuates IKKα kinase activity and suppresses NF-ĸB/p65 activation in human prostate cancer PC-3 and 22Rv1 cells much more effectively than IKK inhibitor, PS1145. We also showed that apigenin caused cell cycle arrest similar to knockdown of IKKα in prostate cancer cells. Studies in xenograft mouse model indicate that apigenin feeding suppresses tumor growth, lowers proliferation and enhances apoptosis. These effects correlated with inhibition of p-IKKα, NF-ĸB/p65, proliferating cell nuclear antigen and increase in cleaved caspase 3 expression in a dose-dependent manner. Overall, our results suggest that inhibition of cell proliferation, invasiveness and decrease in tumor growth by apigenin are mediated by its ability to suppress IKKα and downstream targets affecting NF-ĸB signaling pathways. PMID:26435478

Apigenin blocks IKKα activation and suppresses prostate cancer progression.

PubMed

Shukla, Sanjeev; Kanwal, Rajnee; Shankar, Eswar; Datt, Manish; Chance, Mark R; Fu, Pingfu; MacLennan, Gregory T; Gupta, Sanjay

2015-10-13

IKKα has been implicated as a key regulator of oncogenesis and driver of the metastatic process; therefore is regarded as a promising therapeutic target in anticancer drug development. In spite of the progress made in the development of IKK inhibitors, no potent IKKα inhibitor(s) have been identified. Our multistep approach of molecular modeling and direct binding has led to the identification of plant flavone apigenin as a specific IKKα inhibitor. Here we report apigenin, in micro molar range, inhibits IKKα kinase activity, demonstrates anti-proliferative and anti-invasive activities in functional cell based assays and exhibits anticancer efficacy in experimental tumor model. We found that apigenin directly binds with IKKα, attenuates IKKα kinase activity and suppresses NF-ĸB/p65 activation in human prostate cancer PC-3 and 22Rv1 cells much more effectively than IKK inhibitor, PS1145. We also showed that apigenin caused cell cycle arrest similar to knockdown of IKKα in prostate cancer cells. Studies in xenograft mouse model indicate that apigenin feeding suppresses tumor growth, lowers proliferation and enhances apoptosis. These effects correlated with inhibition of p-IKKα, NF-ĸB/p65, proliferating cell nuclear antigen and increase in cleaved caspase 3 expression in a dose-dependent manner. Overall, our results suggest that inhibition of cell proliferation, invasiveness and decrease in tumor growth by apigenin are mediated by its ability to suppress IKKα and downstream targets affecting NF-ĸB signaling pathways.

Small-molecule agonists of mammalian Diaphanous-related (mDia) formins reveal an effective glioblastoma anti-invasion strategy.

PubMed

Arden, Jessica D; Lavik, Kari I; Rubinic, Kaitlin A; Chiaia, Nicolas; Khuder, Sadik A; Howard, Marthe J; Nestor-Kalinoski, Andrea L; Alberts, Arthur S; Eisenmann, Kathryn M

2015-11-01

The extensive invasive capacity of glioblastoma (GBM) makes it resistant to surgery, radiotherapy, and chemotherapy and thus makes it lethal. In vivo, GBM invasion is mediated by Rho GTPases through unidentified downstream effectors. Mammalian Diaphanous (mDia) family formins are Rho-directed effectors that regulate the F-actin cytoskeleton to support tumor cell motility. Historically, anti-invasion strategies focused upon mDia inhibition, whereas activation remained unexplored. The recent development of small molecules directly inhibiting or activating mDia-driven F-actin assembly that supports motility allows for exploration of their role in GBM. We used the formin inhibitor SMIFH2 and mDia agonists IMM-01/-02 and mDia2-DAD peptides, which disrupt autoinhibition, to examine the roles of mDia inactivation versus activation in GBM cell migration and invasion in vitro and in an ex vivo brain slice invasion model. Inhibiting mDia suppressed directional migration and spheroid invasion while preserving intrinsic random migration. mDia agonism abrogated both random intrinsic and directional migration and halted U87 spheroid invasion in ex vivo brain slices. Thus mDia agonism is a superior GBM anti-invasion strategy. We conclude that formin agonism impedes the most dangerous GBM component-tumor spread into surrounding healthy tissue. Formin activation impairs novel aspects of transformed cells and informs the development of anti-GBM invasion strategies. © 2015 Arden et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Active and passive immunization for cancer.

PubMed

Baxter, David

2014-01-01

Vaccination started around the 10th century AD as a means of preventing smallpox. By the end of the 19th century such therapeutic vaccines were well established with both active and passive preparations being used in clinical practice. Active immunization involved administering an immunogen that might be live/ attenuated, killed/ inactivated, toxoid or subunit in origin. Passive immunization involved giving pre-formed antibodies, usually to very recently exposed individuals. At about the same time such approaches were also tried to treat a variety of cancers - proof of principle for the protective role of the immune response against malignancy was established by the observation that tumors transplanted into syngeneic hosts were rejected by the host innate and adaptive responses. The impact of these therapeutic vaccination has taken a considerable time to become established - in part because target antigens against which an adaptive response can be directed do not appear to be uniquely expressed on malignant transformed cells; and also because tumor cells are able to manipulate their environment to downregulate the host immune response. Therapeutic cancer vaccines are also divided into active and passive types - the latter being subdivided into specific and non-specific vaccines. Active immunization utilizes an immunogen to generate a host response designed to eliminate the malignant cells, whereas in passive immunization preformed antibodies or cells are administered to directly eliminate the transformed cells - examples of each are considered in this review.

Active and passive immunization for cancer

PubMed Central

Baxter, David

2014-01-01

Vaccination started around the 10th century AD as a means of preventing smallpox. By the end of the 19th century such therapeutic vaccines were well established with both active and passive preparations being used in clinical practice. Active immunization involved administering an immunogen that might be live/ attenuated, killed/ inactivated, toxoid or subunit in origin. Passive immunization involved giving pre-formed antibodies, usually to very recently exposed individuals. At about the same time such approaches were also tried to treat a variety of cancers – proof of principle for the protective role of the immune response against malignancy was established by the observation that tumors transplanted into syngeneic hosts were rejected by the host innate and adaptive responses. The impact of these therapeutic vaccination has taken a considerable time to become established - in part because target antigens against which an adaptive response can be directed do not appear to be uniquely expressed on malignant transformed cells; and also because tumor cells are able to manipulate their environment to downregulate the host immune response. Therapeutic cancer vaccines are also divided into active and passive types – the latter being subdivided into specific and non-specific vaccines. Active immunization utilizes an immunogen to generate a host response designed to eliminate the malignant cells, whereas in passive immunization preformed antibodies or cells are administered to directly eliminate the transformed cells - examples of each are considered in this review. PMID:25424829

Tangeretin, a citrus pentamethoxyflavone, antagonizes ABCB1-mediated multidrug resistance by inhibiting its transport function.

PubMed

Feng, Sen-Ling; Yuan, Zhong-Wen; Yao, Xiao-Jun; Ma, Wen-Zhe; Liu, Liang; Liu, Zhong-Qiu; Xie, Ying

2016-08-01

Multidrug resistance (MDR) and tumor metastasis are the main causes of chemotherapeutic treatment failure and mortality in cancer patients. In this study, at achievable nontoxic plasma concentrations, citrus flavonoid tangeretin has been shown to reverse ABCB1-mediated cancer resistance to a variety of chemotherapeutic agents effectively. Co-treatment of cells with tangeretin and paclitaxel activated apoptosis as well as arrested cell cycle at G2/M-phase. Tangeretin profoundly inhibited the ABCB1 transporter activity since it significantly increased the intracellular accumulation of doxorubicin, and flutax-2 in A2780/T cells and decreased the efflux of ABCB1 substrates in Caco2 cells without altering the expression of ABCB1. Moreover, it stimulated the ATPase activity and inhibited verapamil-stimulated ATPase activity in a concentration-dependent manner, indicating a direct interaction with the transporter. The molecular docking results indicated a favorable binding of tangeretin with the transmemberane region site 1 of homology modeled ABCB1 transporter. The overall results demonstrated that tangeretin could sensitize ABCB1-overexpressing cancer cells to chemotherapeutical agents by directly inhibiting ABCB1 transporter function, which encouraged further animal and clinical studies in the treatment of resistant cancers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Capacity of tumor necrosis factor to augment lymphocyte-mediated tumor cell lysis of malignant mesothelioma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, R.V.; Manning, L.S.; Davis, M.R.

1991-01-01

Recombinant human tumor necrosis factor (rHuTNF) was evaluated both for direct anti-tumor action against human malignant mesothelioma and for its capacity to augment the generation and lytic phases of lymphocyte-mediated cytotoxicity against this tumor. rHuTNF was directly toxic by MTT assay to one of two mesothelioma cell lines evaluated, but had no effect on susceptibility to subsequent lymphocyte-mediated lysis of either line. TNF alone was incapable of generating anti-mesothelioma lymphokine-activated killer cell (LAK) activity. Furthermore, it did not augment the degree or LAK activity produced by submaximal interleukin-2 (IL-2) concentrations nor did it augment lysis of mesothelioma cells by naturalmore » killer (NK) or LAK effector cells during the 4-hr 51chromium release cytolytic reaction. The studies also suggest that mesothelioma targets are less responsive to TNF plus submaximal IL-2 concentrations than the standard LAK sensitive target Daudi, raising the possibility that intermediate LAK sensitive tumors such as mesothelioma may require separate and specific evaluation in immunomodulation studies. This in vitro study indicates that use of low-dose rHuTNF and IL-2 is unlikely to be an effective substitute for high-dose IL-2 in generation and maintenance of LAK activity in adoptive immunotherapy for mesothelioma.« less

78 FR 27186 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-09

... cell regeneration in damaged tissue, and examine the regulatory mechanisms for metabolic activity in... populations of cells develop into a coherent circuit that capably detects directional movement in a visual... a single neuron or large numbers of cells in a neuronal population. The instrument's capabilities...

Electroporation of Functional Bacterial Effectors into Mammalian Cells

DOE PAGES

Sontag, Ryan L.; Mihai, Cosmin; Orr, Galya; ...

2015-01-19

Electroporation was used to insert purified bacterial virulence effector proteins directly into living eukaryotic cells. Protein localization was monitored by confocal immunofluorescence microscopy. This method allows for studies on trafficking, function, and protein-protein interactions using active exogenous proteins, avoiding the need for heterologous expression in eukaryotic cells.

Generation of Viable Cell and Biomaterial Patterns by Laser Transfer

NASA Astrophysics Data System (ADS)

Ringeisen, Bradley

2001-03-01

In order to fabricate and interface biological systems for next generation applications such as biosensors, protein recognition microarrays, and engineered tissues, it is imperative to have a method of accurately and rapidly depositing different active biomaterials in patterns or layered structures. Ideally, the biomaterial structures would also be compatible with many different substrates including technologically relevant platforms such as electronic circuits or various detection devices. We have developed a novel laser-based technique, termed matrix assisted pulsed laser evaporation direct write (MAPLE DW), that is able to direct write patterns and three-dimensional structures of numerous biologically active species ranging from proteins and antibodies to living cells. Specifically, we have shown that MAPLE DW is capable of forming mesoscopic patterns of living prokaryotic cells (E. coli bacteria), living mammalian cells (Chinese hamster ovaries), active proteins (biotinylated bovine serum albumin, horse radish peroxidase), and antibodies specific to a variety of classes of cancer related proteins including intracellular and extracellular matrix proteins, signaling proteins, cell cycle proteins, growth factors, and growth factor receptors. In addition, patterns of viable cells and active biomolecules were deposited on different substrates including metals, semiconductors, nutrient agar, and functionalized glass slides. We will present an explanation of the laser-based transfer mechanism as well as results from our recent efforts to fabricate protein recognition microarrays and tissue-based microfluidic networks.

Nucleolus-derived mediators in oncogenic stress response and activation of p53-dependent pathways.

PubMed

Stępiński, Dariusz

2016-08-01

Rapid growth and division of cells, including tumor ones, is correlated with intensive protein biosynthesis. The output of nucleoli, organelles where translational machineries are formed, depends on a rate of particular stages of ribosome production and on accessibility of elements crucial for their effective functioning, including substrates, enzymes as well as energy resources. Different factors that induce cellular stress also often lead to nucleolar dysfunction which results in ribosome biogenesis impairment. Such nucleolar disorders, called nucleolar or ribosomal stress, usually affect cellular functioning which in fact is a result of p53-dependent pathway activation, elicited as a response to stress. These pathways direct cells to new destinations such as cell cycle arrest, damage repair, differentiation, autophagy, programmed cell death or aging. In the case of impaired nucleolar functioning, nucleolar and ribosomal proteins mediate activation of the p53 pathways. They are also triggered as a response to oncogenic factor overexpression to protect tissues and organs against extensive proliferation of abnormal cells. Intentional impairment of any step of ribosome biosynthesis which would direct the cells to these destinations could be a strategy used in anticancer therapy. This review presents current knowledge on a nucleolus, mainly in relation to cancer biology, which is an important and extremely sensitive element of the mechanism participating in cellular stress reaction mediating activation of the p53 pathways in order to counteract stress effects, especially cancer development.

Deletion of Wiskott–Aldrich syndrome protein triggers Rac2 activity and increased cross-presentation by dendritic cells

PubMed Central

Baptista, Marisa A. P.; Keszei, Marton; Oliveira, Mariana; Sunahara, Karen K. S.; Andersson, John; Dahlberg, Carin I. M.; Worth, Austen J.; Liedén, Agne; Kuo, I-Chun; Wallin, Robert P. A.; Snapper, Scott B.; Eidsmo, Liv; Scheynius, Annika; Karlsson, Mikael C. I.; Bouma, Gerben; Burns, Siobhan O.; Forsell, Mattias N. E.; Thrasher, Adrian J.; Nylén, Susanne; Westerberg, Lisa S.

2016-01-01

Wiskott–Aldrich syndrome (WAS) is caused by loss-of-function mutations in the WASp gene. Decreased cellular responses in WASp-deficient cells have been interpreted to mean that WASp directly regulates these responses in WASp-sufficient cells. Here, we identify an exception to this concept and show that WASp-deficient dendritic cells have increased activation of Rac2 that support cross-presentation to CD8+ T cells. Using two different skin pathology models, WASp-deficient mice show an accumulation of dendritic cells in the skin and increased expansion of IFNγ-producing CD8+ T cells in the draining lymph node and spleen. Specific deletion of WASp in dendritic cells leads to marked expansion of CD8+ T cells at the expense of CD4+ T cells. WASp-deficient dendritic cells induce increased cross-presentation to CD8+ T cells by activating Rac2 that maintains a near neutral pH of phagosomes. Our data reveals an intricate balance between activation of WASp and Rac2 signalling pathways in dendritic cells. PMID:27425374

Electrochemical characterization of nano-sized Pd-based catalysts as cathode materials in direct methanol fuel cells.

PubMed

Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

2011-01-01

To improve the catalytic activity of palladium (Pd) as a cathode catalyst in direct methanol fuel cells (DMFCs), we prepared palladium-titanium oxide (Pd-TiO2) catalysts which the Pd and TiO2 nanoparticles were simultaneously impregnated on carbon. We selected Pd and TiO2 as catalytic materials because of their electrochemical stability in acid solution. The crystal structure and the loading amount of Pd and TiO2 on carbon were characterized by X-ray diffraction (XRD) and energy dispersive X-ray microanalysis (EDX). The electrochemical characterization of Pd-TiO2/C catalysts for the oxygen reduction reaction was carried out in half and single cell systems. The catalytic activities of the Pd-TiO2 catalysts were strongly influenced by the TiO2 content. In the single cell test, the Pd-TiO2 catalysts showed very comparable performance to the Pt catalyst.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mouledous, Lionel; Merker, Soren; Neasta, Jeremie

*: Mu opioid (MOP) receptor activation can be functionally modulated by stimulation of Neuropeptide FF 2 (NPFF{sub 2}) G protein-coupled receptors. Fluorescence recovery after photobleaching experiments have shown that activation of the NPFF{sub 2} receptor dramatically reduces the fraction of MOP receptors confined in microdomains of the plasma membrane of SH-SY5Y neuroblastoma cells. The aim of the present work was to assess if the direct observation of receptor compartmentation by fluorescence techniques in living cells could be related to indirect estimation of receptor partitioning in lipid rafts after biochemical fractionation of the cell. Our results show that MOP receptor distributionmore » in lipid rafts is highly dependent upon the method of purification, questioning the interpretation of previous data regarding MOP receptor compartmentation. Moreover, the NPFF analogue 1DMe does not modify the distribution profile of MOP receptors, clearly demonstrating that membrane fractionation data do not correlate with direct measurement of receptor compartmentation in living cells.« less

β-Catenin signaling regulates temporally discrete phases of anterior taste bud development.

PubMed

Thirumangalathu, Shoba; Barlow, Linda A

2015-12-15

The sense of taste is mediated by multicellular taste buds located within taste papillae on the tongue. In mice, individual taste buds reside in fungiform papillae, which develop at mid-gestation as epithelial placodes in the anterior tongue. Taste placodes comprise taste bud precursor cells, which express the secreted factor sonic hedgehog (Shh) and give rise to taste bud cells that differentiate around birth. We showed previously that epithelial activation of β-catenin is the primary inductive signal for taste placode formation, followed by taste papilla morphogenesis and taste bud differentiation, but the degree to which these later elements were direct or indirect consequences of β-catenin signaling was not explored. Here, we define discrete spatiotemporal functions of β-catenin in fungiform taste bud development. Specifically, we show that early epithelial activation of β-catenin, before taste placodes form, diverts lingual epithelial cells from a taste bud fate. By contrast, β-catenin activation a day later within Shh(+) placodes, expands taste bud precursors directly, but enlarges papillae indirectly. Further, placodal activation of β-catenin drives precocious differentiation of Type I glial-like taste cells, but not other taste cell types. Later activation of β-catenin within Shh(+) precursors during papilla morphogenesis also expands taste bud precursors and accelerates Type I cell differentiation, but papilla size is no longer enhanced. Finally, although Shh regulates taste placode patterning, we find that it is dispensable for the accelerated Type I cell differentiation induced by β-catenin. © 2015. Published by The Company of Biologists Ltd.

The actions of mdivi-1, an inhibitor of mitochondrial fission, on rapidly activating delayed-rectifier K⁺ current and membrane potential in HL-1 murine atrial cardiomyocytes.

PubMed

So, Edmund Cheung; Hsing, Chung-Hsi; Liang, Chia-Hua; Wu, Sheng-Nan

2012-05-15

Mdivi-1 is an inhibitor of dynamin related protein 1- (drp1)-mediated mitochondrial fission. However, the mechanisms through which this compound interacts directly with ion currents in heart cells remain unknown. In this study, its effects on ion currents and membrane potential in murine HL-1 cardiomyocytes were investigated. In whole-cell recordings, the addition of mdivi-1 decreased the amplitude of tail current (I(tail)) for the rapidly activating delayed-rectifier K⁺ current (I(Kr)) in a concentration-dependent manner with an IC₅₀ value at 11.6 μM, a value that resembles the inhibition requirement for mitochondrial division. It shifted the activation curve of I(tail) to depolarized voltages with no change in the gating charge. However, mdivi-1 did not alter the rate of recovery from current inactivation. In cell-attached configuration, mdivi-1 inside the pipette suppressed the activity of acetylcholine-activated K⁺ channels without modifying the single-channel conductance. Mdivi-1 (30 μM) slightly depressed the peak amplitude of Na⁺ current with no change in the overall current-voltage relationship. Under current-clamp recordings, addition of mdivi-1 resulted in prolongation for the duration of action potentials (APs) and to increase the firing of spontaneous APs in HL-1 cells. Similarly, in pituitary GH₃ cells, mdivi-1 was effective in directly suppressing the amplitude of ether-à-go-go-related gene-mediated K⁺ current. Therefore, the lengthening of AP duration and increased firing of APs caused by mdivi-1 can be primarily explained by its inhibition of these K⁺ channels enriched in heart cells. The observed effects of mdivi-1 on ion currents were direct and not associated with its inhibition of mitochondrial division. Copyright © 2012 Elsevier B.V. All rights reserved.

APC and Smad7 link TGFβ type I receptors to the microtubule system to promote cell migration

PubMed Central

Ekman, Maria; Mu, Yabing; Lee, So Young; Edlund, Sofia; Kozakai, Takaharu; Thakur, Noopur; Tran, Hoanh; Qian, Jiang; Groeden, Joanna; Heldin, Carl-Henrik; Landström, Maréne

2012-01-01

Cell migration occurs by activation of complex regulatory pathways that are spatially and temporally integrated in response to extracellular cues. Binding of adenomatous polyposis coli (APC) to the microtubule plus ends in polarized cells is regulated by glycogen synthase kinase 3β (GSK-3β). This event is crucial for establishment of cell polarity during directional migration. However, the role of APC for cellular extension in response to extracellular signals is less clear. Smad7 is a direct target gene for transforming growth factor-β (TGFβ) and is known to inhibit various TGFβ-induced responses. Here we report a new function for Smad7. We show that Smad7 and p38 mitogen–activated protein kinase together regulate the expression of APC and cell migration in prostate cancer cells in response to TGFβ stimulation. In addition, Smad7 forms a complex with APC and acts as an adaptor protein for p38 and GSK-3β kinases to facilitate local TGFβ/p38–dependent inactivation of GSK-3β, accumulation of β-catenin, and recruitment of APC to the microtubule plus end in the leading edge of migrating prostate cancer cells. Moreover, the Smad7–APC complex links the TGFβ type I receptor to the microtubule system to regulate directed cellular extension and migratory responses evoked by TGFβ. PMID:22496417

Systems-level identification of PKA-dependent signaling in epithelial cells.

PubMed

Isobe, Kiyoshi; Jung, Hyun Jun; Yang, Chin-Rang; Claxton, J'Neka; Sandoval, Pablo; Burg, Maurice B; Raghuram, Viswanathan; Knepper, Mark A

2017-10-17

G protein stimulatory α-subunit (G αs )-coupled heptahelical receptors regulate cell processes largely through activation of protein kinase A (PKA). To identify signaling processes downstream of PKA, we deleted both PKA catalytic subunits using CRISPR-Cas9, followed by a "multiomic" analysis in mouse kidney epithelial cells expressing the G αs -coupled V2 vasopressin receptor. RNA-seq (sequencing)-based transcriptomics and SILAC (stable isotope labeling of amino acids in cell culture)-based quantitative proteomics revealed a complete loss of expression of the water-channel gene Aqp2 in PKA knockout cells. SILAC-based quantitative phosphoproteomics identified 229 PKA phosphorylation sites. Most of these PKA targets are thus far unannotated in public databases. Surprisingly, 1,915 phosphorylation sites with the motif x-(S/T)-P showed increased phosphooccupancy, pointing to increased activity of one or more MAP kinases in PKA knockout cells. Indeed, phosphorylation changes associated with activation of ERK2 were seen in PKA knockout cells. The ERK2 site is downstream of a direct PKA site in the Rap1GAP, Sipa1l1, that indirectly inhibits Raf1. In addition, a direct PKA site that inhibits the MAP kinase kinase kinase Map3k5 (ASK1) is upstream of JNK1 activation. The datasets were integrated to identify a causal network describing PKA signaling that explains vasopressin-mediated regulation of membrane trafficking and gene transcription. The model predicts that, through PKA activation, vasopressin stimulates AQP2 exocytosis by inhibiting MAP kinase signaling. The model also predicts that, through PKA activation, vasopressin stimulates Aqp2 transcription through induction of nuclear translocation of the acetyltransferase EP300, which increases histone H3K27 acetylation of vasopressin-responsive genes (confirmed by ChIP-seq).

RTA 408, A Novel Synthetic Triterpenoid with Broad Anticancer and Anti-Inflammatory Activity

PubMed Central

Probst, Brandon L.; Trevino, Isaac; McCauley, Lyndsey; Bumeister, Ron; Dulubova, Irina; Wigley, W. Christian; Ferguson, Deborah A.

2015-01-01

Semi-synthetic triterpenoids are antioxidant inflammation modulator (AIM) compounds that inhibit tumor cell growth and metastasis. Compounds in the AIM class bind to Keap1 and attenuate Nrf2 degradation. In the nucleus, Nrf2 increases antioxidant gene expression and reduces pro-inflammatory gene expression. By increasing Nrf2 activity, AIMs reduce reactive oxygen species and inflammation in the tumor microenvironment, which reverses tumor-mediated immune evasion and inhibits tumor growth and metastasis. AIMs also directly inhibit tumor cell growth by modulating oncogenic signaling pathways, such as IKKβ/NF-κB. Here, we characterized the in vitro antioxidant, anti-inflammatory, and anticancer activities of RTA 408, a novel AIM that is currently being evaluated in patients with advanced malignancies. At low concentrations (≤ 25 nM), RTA 408 activated Nrf2 and suppressed nitric oxide and pro-inflammatory cytokine levels in interferon-γ-stimulated RAW 264.7 macrophage cells. At higher concentrations, RTA 408 inhibited tumor cell growth (GI50 = 260 ± 74 nM) and increased caspase activity in tumor cell lines, but not in normal primary human cells. Consistent with the direct effect of AIMs on IKKβ, RTA 408 inhibited NF-κB signaling and decreased cyclin D1 levels at the same concentrations that inhibited cell growth and induced apoptosis. RTA 408 also increased CDKN1A (p21) levels and JNK phosphorylation. The in vitro activity profile of RTA 408 is similar to that of bardoxolone methyl, which was well-tolerated by patients at doses that demonstrated target engagement. Taken together, these data support clinical evaluation of RTA 408 for cancer treatment. PMID:25897966

Mucin1 shifts Smad3 signaling from the tumor-suppressive pSmad3C/p21(WAF1) pathway to the oncogenic pSmad3L/c-Myc pathway by activating JNK in human hepatocellular carcinoma cells.

PubMed

Li, Qiongshu; Liu, Guomu; Yuan, Hongyan; Wang, Juan; Guo, Yingying; Chen, Tanxiu; Zhai, Ruiping; Shao, Dan; Ni, Weihua; Tai, Guixiang

2015-02-28

Mucin1 (MUC1) is a transmembrane glycoprotein that acts as an oncogene in human hepatic tumorigenesis. Hepatocellular carcinoma (HCC) cells often gain advantage by reducing the tumor-suppressive activity of transforming growth factor beta (TGF-β) together with stimulation of its oncogenic activity as in MUC1 expressing HCC cells; however, molecular mechanisms remain largely unknown. Type I TGF-β receptor (TβRI) and c-Jun NH2-terminal kinase (JNK) differentially phosphorylate Smad3 mediator to create 2 phosphorylated forms: COOH-terminally phosphorylated Smad3 (pSmad3C) and linker-phosphorylated Smad3 (pSmad3L). Here, we report that MUC1 overexpression in HCC cell lines suppresses TβRI-mediated pSmad3C signaling which involves growth inhibition by up-regulating p21(WAF1). Instead, MUC1 directly activates JNK to stimulate oncogenic pSmad3L signaling, which fosters cell proliferation by up-regulating c-Myc. Conversely, MUC1 gene silencing in MUC1 expressing HCC cells results in preserved tumor-suppressive function via pSmad3C, while eliminating pSmad3L-mediated oncogenic activity both in vitro and in vivo. In addition, high correlation between MUC1 and pSmad3L/c-Myc but not pSmad3C/p21(WAF1) expression was observed in HCC tissues from patients. Collectively, these results indicate that MUC1 shifts Smad3 signaling from a tumor-suppressive pSmad3C/p21(WAF1) to an oncogenic pSmad3L/c-Myc pathway by directly activating JNK in HCC cells, suggesting that MUC1 is an important target for HCC therapy.

Characterisation of CCT271850, a selective, oral and potent MPS1 inhibitor, used to directly measure in vivo MPS1 inhibition vs therapeutic efficacy

PubMed Central

Faisal, Amir; Mak, Grace W Y; Gurden, Mark D; Xavier, Cristina P R; Anderhub, Simon J; Innocenti, Paolo; Westwood, Isaac M; Naud, Sébastien; Hayes, Angela; Box, Gary; Valenti, Melanie R; De Haven Brandon, Alexis K; O'Fee, Lisa; Schmitt, Jessica; Woodward, Hannah L; Burke, Rosemary; vanMontfort, Rob L M; Blagg, Julian; Raynaud, Florence I; Eccles, Suzanne A; Hoelder, Swen; Linardopoulos, Spiros

2017-01-01

Background: The main role of the cell cycle is to enable error-free DNA replication, chromosome segregation and cytokinesis. One of the best characterised checkpoint pathways is the spindle assembly checkpoint, which prevents anaphase onset until the appropriate attachment and tension across kinetochores is achieved. MPS1 kinase activity is essential for the activation of the spindle assembly checkpoint and has been shown to be deregulated in human tumours with chromosomal instability and aneuploidy. Therefore, MPS1 inhibition represents an attractive strategy to target cancers. Methods: To evaluate CCT271850 cellular potency, two specific antibodies that recognise the activation sites of MPS1 were used and its antiproliferative activity was determined in 91 human cancer cell lines. DLD1 cells with induced GFP-MPS1 and HCT116 cells were used in in vivo studies to directly measure MPS1 inhibition and efficacy of CCT271850 treatment. Results: CCT271850 selectively and potently inhibits MPS1 kinase activity in biochemical and cellular assays and in in vivo models. Mechanistically, tumour cells treated with CCT271850 acquire aberrant numbers of chromosomes and the majority of cells divide their chromosomes without proper alignment because of abrogation of the mitotic checkpoint, leading to cell death. We demonstrated a moderate level of efficacy of CCT271850 as a single agent in a human colorectal carcinoma xenograft model. Conclusions: CCT271850 is a potent, selective and orally bioavailable MPS1 kinase inhibitor. On the basis of in vivo pharmacodynamic vs efficacy relationships, we predict that more than 80% inhibition of MPS1 activity for at least 24 h is required to achieve tumour stasis or regression by CCT271850. PMID:28334731

Characterisation of CCT271850, a selective, oral and potent MPS1 inhibitor, used to directly measure in vivo MPS1 inhibition vs therapeutic efficacy.

PubMed

Faisal, Amir; Mak, Grace W Y; Gurden, Mark D; Xavier, Cristina P R; Anderhub, Simon J; Innocenti, Paolo; Westwood, Isaac M; Naud, Sébastien; Hayes, Angela; Box, Gary; Valenti, Melanie R; De Haven Brandon, Alexis K; O'Fee, Lisa; Schmitt, Jessica; Woodward, Hannah L; Burke, Rosemary; vanMontfort, Rob L M; Blagg, Julian; Raynaud, Florence I; Eccles, Suzanne A; Hoelder, Swen; Linardopoulos, Spiros

2017-04-25

The main role of the cell cycle is to enable error-free DNA replication, chromosome segregation and cytokinesis. One of the best characterised checkpoint pathways is the spindle assembly checkpoint, which prevents anaphase onset until the appropriate attachment and tension across kinetochores is achieved. MPS1 kinase activity is essential for the activation of the spindle assembly checkpoint and has been shown to be deregulated in human tumours with chromosomal instability and aneuploidy. Therefore, MPS1 inhibition represents an attractive strategy to target cancers. To evaluate CCT271850 cellular potency, two specific antibodies that recognise the activation sites of MPS1 were used and its antiproliferative activity was determined in 91 human cancer cell lines. DLD1 cells with induced GFP-MPS1 and HCT116 cells were used in in vivo studies to directly measure MPS1 inhibition and efficacy of CCT271850 treatment. CCT271850 selectively and potently inhibits MPS1 kinase activity in biochemical and cellular assays and in in vivo models. Mechanistically, tumour cells treated with CCT271850 acquire aberrant numbers of chromosomes and the majority of cells divide their chromosomes without proper alignment because of abrogation of the mitotic checkpoint, leading to cell death. We demonstrated a moderate level of efficacy of CCT271850 as a single agent in a human colorectal carcinoma xenograft model. CCT271850 is a potent, selective and orally bioavailable MPS1 kinase inhibitor. On the basis of in vivo pharmacodynamic vs efficacy relationships, we predict that more than 80% inhibition of MPS1 activity for at least 24 h is required to achieve tumour stasis or regression by CCT271850.

N6-isopentenyladenosine, an endogenous isoprenoid end product, directly affects cytotoxic and regulatory functions of human NK cells through FDPS modulation.

PubMed

Ciaglia, Elena; Pisanti, Simona; Picardi, Paola; Laezza, Chiara; Malfitano, Anna Maria; D'Alessandro, Alba; Gazzerro, Patrizia; Vitale, Mario; Carbone, Ennio; Bifulco, Maurizio

2013-12-01

iPA is a naturally occurring nucleoside with an isopentenyl moiety derived from the mevalonate pathway and a well-established anti-tumor activity. In analogy to the unique specificity for phosphoantigens, such as IPP, shown by human Vγ9Vδ2 T cells, here, we report for the first time the ability of iPA to selectively expand and directly target human NK cells. Interestingly, submicromolar doses of iPA stimulate resting human NK cells and synergize with IL-2 to induce a robust activation ex vivo with significant secretion of CCL5 and CCL3 and a large increase in TNF-α and IFN-γ production when compared with IL-2 single cytokine treatment. Moreover, iPA promotes NK cell proliferation and up-regulates the expression of specific NK cell-activating receptors, as well as CD69 and CD107a expression. Accordingly, this phenotype correlates with significantly greater cytotoxicity against tumor targets. At the molecular level, iPA leads to a selective, potent activation of MAPK signaling intermediaries downstream of the IL-2R. The effect results, at least in part, from the fine modulation of the FDPS activity, the same enzyme implicated in the stimulation of the human γδ T cells. The iPA-driven modulation of FDPS can cause an enhancement of post-translational prenylation essential for the biological activity of key proteins in NK signaling and effector functions, such as Ras. These unanticipated properties of iPA provide an additional piece of evidence of the immunoregulatory role of the intermediates of the mevalonate pathway and open novel therapeutic perspectives for this molecule as an immune-modulatory drug.

delta opioid receptors stimulate Akt-dependent phosphorylation of c-jun in T cells.

PubMed

Shahabi, Nahid A; McAllen, Kathy; Sharp, Burt M

2006-02-01

Activation of naive T cells markedly up-regulates the expression of delta opioid receptors (DORs). These receptors are bound by DOR peptides released by T cells, modulating T cell functions such as interleukin-2 production, cellular proliferation, and chemotaxis. Previous studies have shown that DOR agonists [e.g., [D-Ala(2)-D-Leu(5)]-enkephalin (DADLE)] modulate T cell antigen receptor signaling through mitogen-activated protein kinases (MAPKs; i.e., extracellular signal-regulated kinases 1 and 2) and that DORs directly induce phosphorylation of activating transcription factor-2 (implicated in cytokine gene transcription) and its association with the MAPK c-jun1 NH(2)-terminal kinase (JNK). Such observations suggest that DORs may induce the phosphorylation of c-jun. These experiments were performed to test this hypothesis and determine the potential roles of phosphoinositide 3-kinase (PI3K) and Akt (protein kinase B). DADLE (10(-10) to 10(-6) M) dose-dependently induced c-jun phosphorylation. This was blocked by pertussis toxin and the DOR-specific antagonist naltindole. Fluorescence flow cytometry showed that DADLE significantly stimulated c-jun phosphorylation by T cells. DADLE stimulated phosphorylation of membrane-associated Akt; wortmannin and LY294002 ([2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one]), specific inhibitors of PI3K, abolished the DADLE-induced phosphorylation of c-jun. Finally, inhibitors of Akt and JNK blocked DADLE-induced phosphorylation of c-jun. Thus, activated DORs directly stimulate c-jun phosphorylation through a PI3K-dependent pathway in T cells, apparently involving Akt. This implies that DORs activate JNK through a novel pathway dependent on PI3K and Akt, thereby regulating the function of activator protein-1 transcription complexes containing c-jun and other transcription partners.

NOA36 Protein Contains a Highly Conserved Nucleolar Localization Signal Capable of Directing Functional Proteins to the Nucleolus, in Mammalian Cells

PubMed Central

de Melo, Ivan S.; Jimenez-Nuñez, Maria D.; Iglesias, Concepción; Campos-Caro, Antonio; Moreno-Sanchez, David; Ruiz, Felix A.; Bolívar, Jorge

2013-01-01

NOA36/ZNF330 is an evolutionarily well-preserved protein present in the nucleolus and mitochondria of mammalian cells. We have previously reported that the pro-apoptotic activity of this protein is mediated by a characteristic cysteine-rich domain. We now demonstrate that the nucleolar localization of NOA36 is due to a highly-conserved nucleolar localization signal (NoLS) present in residues 1–33. This NoLS is a sequence containing three clusters of two or three basic amino acids. We fused the amino terminal of NOA36 to eGFP in order to characterize this putative NoLS. We show that a cluster of three lysine residues at positions 3 to 5 within this sequence is critical for the nucleolar localization. We also demonstrate that the sequence as found in human is capable of directing eGFP to the nucleolus in several mammal, fish and insect cells. Moreover, this NoLS is capable of specifically directing the cytosolic yeast enzyme polyphosphatase to the target of the nucleolus of HeLa cells, wherein its enzymatic activity was detected. This NoLS could therefore serve as a very useful tool as a nucleolar marker and for directing particular proteins to the nucleolus in distant animal species. PMID:23516598

Modulation of Estrogen Response Element-Driven Gene Expressions and Cellular Proliferation with Polar Directions by Designer Transcription Regulators

PubMed Central

Muyan, Mesut; Güpür, Gizem; Yaşar, Pelin; Ayaz, Gamze; User, Sırma Damla; Kazan, Hasan Hüseyin; Huang, Yanfang

2015-01-01

Estrogen receptor α (ERα), as a ligand-dependent transcription factor, mediates 17β-estradiol (E2) effects. ERα is a modular protein containing a DNA binding domain (DBD) and transcription activation domains (AD) located at the amino- and carboxyl-termini. The interaction of the E2-activated ERα dimer with estrogen response elements (EREs) of genes constitutes the initial step in the ERE-dependent signaling pathway necessary for alterations of cellular features. We previously constructed monomeric transcription activators, or monotransactivators, assembled from an engineered ERE-binding module (EBM) using the ERα-DBD and constitutively active ADs from other transcription factors. Monotransactivators modulated cell proliferation by activating and repressing ERE-driven gene expressions that simulate responses observed with E2-ERα. We reasoned here that integration of potent heterologous repression domains (RDs) into EBM could generate monotransrepressors that alter ERE-bearing gene expressions and cellular proliferation in directions opposite to those observed with E2-ERα or monotransactivators. Consistent with this, monotransrepressors suppressed reporter gene expressions that emulate the ERE-dependent signaling pathway. Moreover, a model monotransrepressor regulated DNA synthesis, cell cycle progression and proliferation of recombinant adenovirus infected ER-negative cells through decreasing as well as increasing gene expressions with polar directions compared with E2-ERα or monotransactivator. Our results indicate that an ‘activator’ or a ‘repressor’ possesses both transcription activating/enhancing and repressing/decreasing abilities within a chromatin context. Offering a protein engineering platform to alter signal pathway-specific gene expressions and cell growth, our approach could also be used for the development of tools for epigenetic modifications and for clinical interventions wherein multigenic de-regulations are an issue. PMID:26295471

Lamellipodin and the Scar/WAVE complex cooperate to promote cell migration in vivo

PubMed Central

Law, Ah-Lai; Vehlow, Anne; Kotini, Maria; Dodgson, Lauren; Soong, Daniel; Theveneau, Eric; Bodo, Cristian; Taylor, Eleanor; Navarro, Christel; Perera, Upamali; Michael, Magdalene; Dunn, Graham A.; Bennett, Daimark; Mayor, Roberto

2013-01-01

Cell migration is essential for development, but its deregulation causes metastasis. The Scar/WAVE complex is absolutely required for lamellipodia and is a key effector in cell migration, but its regulation in vivo is enigmatic. Lamellipodin (Lpd) controls lamellipodium formation through an unknown mechanism. Here, we report that Lpd directly binds active Rac, which regulates a direct interaction between Lpd and the Scar/WAVE complex via Abi. Consequently, Lpd controls lamellipodium size, cell migration speed, and persistence via Scar/WAVE in vitro. Moreover, Lpd knockout mice display defective pigmentation because fewer migrating neural crest-derived melanoblasts reach their target during development. Consistently, Lpd regulates mesenchymal neural crest cell migration cell autonomously in Xenopus laevis via the Scar/WAVE complex. Further, Lpd’s Drosophila melanogaster orthologue Pico binds Scar, and both regulate collective epithelial border cell migration. Pico also controls directed cell protrusions of border cell clusters in a Scar-dependent manner. Taken together, Lpd is an essential, evolutionary conserved regulator of the Scar/WAVE complex during cell migration in vivo. PMID:24247431

The Role of Spatially Controlled Cell Proliferation in Limb Bud Morphogenesis

PubMed Central

Boehm, Bernd; Westerberg, Henrik; Lesnicar-Pucko, Gaja; Raja, Sahdia; Rautschka, Michael; Cotterell, James; Swoger, Jim; Sharpe, James

2010-01-01

Although the vertebrate limb bud has been studied for decades as a model system for spatial pattern formation and cell specification, the cellular basis of its distally oriented elongation has been a relatively neglected topic by comparison. The conventional view is that a gradient of isotropic proliferation exists along the limb, with high proliferation rates at the distal tip and lower rates towards the body, and that this gradient is the driving force behind outgrowth. Here we test this hypothesis by combining quantitative empirical data sets with computer modelling to assess the potential role of spatially controlled proliferation rates in the process of directional limb bud outgrowth. In particular, we generate two new empirical data sets for the mouse hind limb—a numerical description of shape change and a quantitative 3D map of cell cycle times—and combine these with a new 3D finite element model of tissue growth. By developing a parameter optimization approach (which explores spatial patterns of tissue growth) our computer simulations reveal that the observed distribution of proliferation rates plays no significant role in controlling the distally extending limb shape, and suggests that directional cell activities are likely to be the driving force behind limb bud outgrowth. This theoretical prediction prompted us to search for evidence of directional cell orientations in the limb bud mesenchyme, and we thus discovered a striking highly branched and extended cell shape composed of dynamically extending and retracting filopodia, a distally oriented bias in Golgi position, and also a bias in the orientation of cell division. We therefore provide both theoretical and empirical evidence that limb bud elongation is achieved by directional cell activities, rather than a PD gradient of proliferation rates. PMID:20644711

Liver-Directed Human Amniotic Epithelial Cell Transplantation Improves Systemic Disease Phenotype in Hurler Syndrome Mouse Model.

PubMed

Rodriguez, Natalie S; Yanuaria, Lisa; Parducho, Kevin Murphy R; Garcia, Irving M; Varghese, Bino A; Grubbs, Brendan H; Miki, Toshio

2017-07-01

Mucopolysaccharidosis type 1 (MPS1) is an inherited lysosomal storage disorder caused by a deficiency in the glycosaminoglycan (GAG)-degrading enzyme α-l-iduronidase (IDUA). In affected patients, the systemic accumulation of GAGs results in skeletal dysplasia, neurological degeneration, multiple organ dysfunction, and early death. Current therapies, including enzyme replacement and bone marrow transplant, improve life expectancy but the benefits to skeletal and neurological phenotypes are limited. In this study, we tested the therapeutic efficacy of liver-directed transplantation of a placental stem cell, which possesses multilineage differentiation potential, low immunogenicity, and high lysosomal enzyme activity. Unfractionated human amniotic epithelial cells (hAECs) were transplanted directly into the liver of immunodeficient Idua knockout mouse neonates. The hAECs engraftment was immunohistochemically confirmed with anti-human mitochondria staining. Enzyme activity assays indicated that hAECs transplantation restored IDUA function in the liver and significantly decreased urinary GAG excretion. Histochemical and micro-computed tomography analyses revealed reduced GAG deposition in the phalanges joints and composition/morphology improvement of cranial and facial bones. Neurological assessment in the hAEC treated mice showed significant improvement of sensorimotor coordination in the hAEC treated mice compared to untreated mice. Results confirm that partial liver cell replacement with placental stem cells can provide long-term (>20 weeks) and systemic restoration of enzyme function, and lead to significant phenotypic improvement in the MPS1 mouse model. This preclinical data indicate that liver-directed placental stem cell transplantation may improve skeletal and neurological phenotypes of MPS1 patients. Stem Cells Translational Medicine 2017;6:1583-1594. © 2017 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Curcumin directly inhibits the transport activity of GLUT1

PubMed Central

Gunnink, Leesha K.; Alabi, Ola D.; Kuiper, Benjamin D.; Gunnink, Stephen M.; Schuiteman, Sam J.; Strohbehn, Lauren E.; Hamilton, Kathryn E.; Wrobel, Kathryn E.; Louters, Larry L.

2016-01-01

Curcumin, a major ingredient in turmeric, has a long history of medicinal applications in a wide array of maladies including treatment for diabetes and cancer. Seemingly counterintuitive to the documented hypoglycemic effects of curcumin, however, a recent report indicates that curcumin directly inhibits glucose uptake in adipocytes. The major glucose transporter in adipocytes is GLUT4. Therefore, this study investigates the effects of curcumin in cell lines where the major transporter is GLUT1. We report that curcumin has an immediate inhibitory effect on basal glucose uptake in L929 fibroblast cells with a maximum inhibition of 80% achieved at 75 μM curcumin. Curcumin also blocks activation of glucose uptake by azide, glucose deprivation, hydroxylamine, or phenylarsine oxide. Inhibition does not increase with exposure time and the inhibitory effects reverse within an hour. Inhibition does not appear to involve a reaction between curcumin and the thiol side chain of a cysteine residue since neither prior treatment of cells with iodoacetamide nor curcumin with cysteine alters curcumin’s inhibitory effects. Curcumin is a mixed inhibitor reducing the Vmax of 2DG transport by about half with little effect on the Km. The inhibitory effects of curcumin are not additive to the effects of cytochalasin B and 75 μM curcumin actually reduces specific cytochalasin B binding by 80%. Taken together, the data suggest that curcumin binds directly to GLUT1 at a site that overlaps with the cytochalasin B binding site and thereby inhibits glucose transport. A direct inhibition of GLUT proteins in intestinal epithelial cells would likely reduce absorption of dietary glucose and contribute to a hypoglycemic effect of curcumin. Also, inhibition of GLUT1 activity might compromise cancer cells that overexpress GLUT1 and be another possible mechanism for the documented anticancer effects of curcumin. PMID:27039889

Recognition of prostate-specific antigenic peptide determinants by human CD4 and CD8 T cells.

PubMed

Corman, J M; Sercarz, E E; Nanda, N K

1998-11-01

It is now becoming accepted that one is not tolerant to all the determinants of self proteins: the T cell repertoire directed to some sequences in self proteins is intact and can be activated. When a self protein is exclusively expressed by tumour cells, the T cell repertoire directed to the particular self antigen can potentially be activated to attack the tumour: this would amount to induction of a beneficial autoimmune response. Prostate cancer offers a unique opportunity for activation of a tumour-specific immune response owing to the exclusive synthesis of prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM) by prostatic tissue and prostate tumour cells. In this study we examine the CD4 and CD8 T cell repertoires specific for peptides of PSA and PSM in normal human male individuals, using short-term, peptide antigen-driven CD4 and CD8 T cell lines. We show that short-term, CD4 T cell lines derived from six HLA-DR4 individuals showed strong proliferative responses to six of 10 tested peptides of PSA, selected as to contain a DR4 binding motif. Short-term, CD8 T cell lines from three HLA-A1 individuals showed specific cytolytic activity for autologous targets loaded with five of five tested peptides of PSA and PSM, selected to possess an HLA-A1 binding motif. One of the peptides chosen is termed a 'dual-motif' peptide, as it encodes determinants for both CD4 and CD8 T cells. These results, indicating the existence of CD4 and CD8 T cells against determinants of the self proteins, PSA and PSM, in healthy male individuals reveal the potential of the T cell repertoire from the typical prostate cancer patient to eradicate prostate tumours upon being appropriately activated.

Bone Talk: Activated Osteoblasts Promote Lung Cancer Growth.

PubMed

Bružas, Emilis; Egeblad, Mikala

2018-03-01

Cancer cells can directly stimulate the generation and recruitment of tumor-supportive bone marrow-derived cells (BMDCs), including neutrophils, via secreted factors. A new study demonstrates that lung tumors also remotely activate bone-residing osteoblasts, which in turn promote neutrophil production. This is a multistep mechanism of establishing a supportive tumor microenvironment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nuclear calcium is required for human T cell activation

PubMed Central

Samstag, Yvonne

2016-01-01

Calcium signals in stimulated T cells are generally considered single entities that merely trigger immune responses, whereas costimulatory events specify the type of reaction. Here we show that the “T cell calcium signal” is a composite signal harboring two distinct components that antagonistically control genomic programs underlying the immune response. Using human T cells from healthy individuals, we establish nuclear calcium as a key signal in human T cell adaptogenomics that drives T cell activation and is required for signaling to cyclic adenosine monophosphate response element–binding protein and the induction of CD25, CD69, interleukin-2, and γ-interferon. In the absence of nuclear calcium signaling, cytosolic calcium activating nuclear factor of activated T cells translocation directed the genomic response toward enhanced expression of genes that negatively modulate T cell activation and are associated with a hyporesponsive state. Thus, nuclear calcium controls the T cell fate decision between a proliferative immune response and tolerance. Modulators of nuclear calcium–driven transcription may be used to develop a new type of pro-tolerance immunosuppressive therapy. PMID:27810914

The effect of Bcr-Abl protein tyrosine kinase on maturation and proliferation of primitive haematopoietic cells.

PubMed Central

Buckle, A. M.; Mottram, R.; Pierce, A.; Lucas, G. S.; Russell, N.; Miyan, J. A.; Whetton, A. D.

2000-01-01

BACKGROUND: Chronic Myeloid Leukaemia (CML) is characterised by the chromosomal translocation resulting in expression of the Bcr-Abl protein tyrosine kinase (PTK) in early stem cells and their progeny. However the precise nature of Bcr-Abl effects in primitive CML stem cells remains a matter of active debate. MATERIALS AND METHODS: Extremely primitive Bcr-Abl fusion positive cells were purified from patients with CML using multiparameter flow cytometric analysis of CD34, Thy, and lineage marker (Lin) expression, plus rhodamine-123 (Rh-123) brightness. Progenitor cells of increasing maturity were examined for cycling status by flow cytometry and their proliferative status directly correlated with cell phenotype. The activation status of a key transcription factor, signal transducers and activators of transcription (STAT-5), was also analyzed by immunocytochemistry. RESULTS: The most primitive stem cells currently defined (CD34+Lin-Thy+ Rh-1231o) were present as a lower proportion of the stem cell compartment (CD34+Lin-) of CML patients at presentation than of normal individuals (2.3% +/- 0.4 compared with 5.1% +/- 0.6 respectively). Conversely there was a significantly higher proportion of the more mature cells (CD34+Lin-Thy-Rh-123 hi) in CML patients than in normal individuals (79.3 +/- 1.8 compared with 70.9 +/- 3.3). No primitive subpopulation of CML CD34+Lin- cells was cycling to a significantly greater degree than cells from normal donors, in fact, late progenitor cells (CD34+Lin+) were cycling significantly less in CML samples than normal samples. STAT5, however, was observed to be activated in CML cells. CONCLUSIONS: We conclude that no subpopulation of CML stem cells displays significantly increased cell cycling. Thus, increased cycling cannot be a direct consequence of Bcr-Abl PTK acquisition in highly enriched stem cells from patients with CML. In vivo CML need not be considered a disease of unbridled stem cell proliferation, but a subtle defect in the balance between self renewal and maturation. PMID:11126203

Development of a method to analyze single cell activity by using dielectrophoretic levitation.

PubMed

Hakoda, M; Hachisu, T; Wakizaka, Y; Mii, S; Kitajima, N

2005-01-01

In cell fusion and genetic recombination, although the activity of single cells is extremely important, there is no method to analyze single cell activity. Development of a quick analyzing method for single cell activity is desired in various fields. Dielectrophoresis (DEP) refers to the force exerted on the induced dipole moment of an uncharged dielectric and/or conductive particle by a nonuniform electric field. By applying DEP, we obtained experimentally a relationship between the cell activity and the dielectric property, Re[K(omega)], and examined how to evaluate the single cell activity by measuring Re[K(omega)] of a single cell. A cone and plate electrode geometry was adapted in order to achieve the feedback-controlled DEP levitation. The single cell is exposed to a nonuniform field induced by the cone and plate electrode, and a more polarizable cell is moved to the direction of the cone electrode by the DEP force. The cell settles in the position where the DEP force and gravity are balanced by controlling applied voltage. This settled position, measured on the center axis of the cone electrode, depended on the dielectric constant of the cell. From these results, the relationship between the specific growth rates in cell growth phase and the dielectric properties Re[K(omega)] was obtained. Furthermore, the effect on the cell activity of various stresses, such as concentration of carbon dioxide, temperature, etc., was examined.

Anti-angiogenic and anti-metastatic activity of JAK inhibitor AZD1480

PubMed Central

Xin, Hong; Herrmann, Andreas; Reckamp, Karen; Zhang, Wang; Pal, Sumanta; Hedvat, Michael; Zhang, Chunyan; Liang, Wei; Scuto, Anna; Weng, Shaobu; Morosini, Deborah; Cao, Zhu A.; Zinda, Michael; Figlin, Robert; Huszar, Dennis; Jove, Richard; Yu, Hua

2011-01-01

STAT3 has important functions in both tumor cells and the tumor microenvironment to facilitate cancer progression. The STAT regulatory kinase JAK has been strongly implicated in promoting oncogenesis of various solid tumors, including through the use of JAK kinase inhibitors such as AZD1480. However, direct evidence that JAK drives STAT3 function and cancer pathogenesis at the level of the tumor microenvironment has yet to be established clearly. In this study, we show that AZD1480 inhibits STAT3 in tumor-associated myeloid cells, reducing their number and inhibiting tumor metastasis. Myeloid cell-mediated angiogenesis was also diminished by AZD1480, with additional direct inhibition of endothelial cell function in vitro and in vivo. AZD1480 blocked lung infiltration of myeloid cells and formation of pulmonary metastases in both mouse syngeneic experimental and spontaneous metastatic models. Furthermore, AZD1480 reduced angiogenesis and metastasis in a human xenograft tumor model. Although the effects of AZD1480 on the tumor microenvironment were important for the observed anti-angiogenic activity, constitutive activation of STAT3 in tumor cells themselves could block these anti-angiogenic effects demonstrating the complexity of the JAK/STAT signaling network in tumor progression. Together, our results indicated that AZD1480 can effectively inhibit tumor angiogenesis and metastasis mediated by STAT3 in stromal cells as well as tumor cells. PMID:21920898

The Basic Helix-Loop-Helix Transcription Factor MYC2 Directly Represses PLETHORA Expression during Jasmonate-Mediated Modulation of the Root Stem Cell Niche in Arabidopsis[W][OA

PubMed Central

Chen, Qian; Sun, Jiaqiang; Zhai, Qingzhe; Zhou, Wenkun; Qi, Linlin; Xu, Li; Wang, Bao; Chen, Rong; Jiang, Hongling; Qi, Jing; Li, Xugang; Palme, Klaus; Li, Chuanyou

2011-01-01

The root stem cell niche, which in the Arabidopsis thaliana root meristem is an area of four mitotically inactive quiescent cells (QCs) and the surrounding mitotically active stem cells, is critical for root development and growth. We report here that during jasmonate-induced inhibition of primary root growth, jasmonate reduces root meristem activity and leads to irregular QC division and columella stem cell differentiation. Consistently, jasmonate reduces the expression levels of the AP2-domain transcription factors PLETHORA1 (PLT1) and PLT2, which form a developmentally instructive protein gradient and mediate auxin-induced regulation of stem cell niche maintenance. Not surprisingly, the effects of jasmonate on root stem cell niche maintenance and PLT expression require the functioning of MYC2/JASMONATE INSENSITIVE1, a basic helix-loop-helix transcription factor that involves versatile aspects of jasmonate-regulated gene expression. Gel shift and chromatin immunoprecipitation experiments reveal that MYC2 directly binds the promoters of PLT1 and PLT2 and represses their expression. We propose that MYC2-mediated repression of PLT expression integrates jasmonate action into the auxin pathway in regulating root meristem activity and stem cell niche maintenance. This study illustrates a molecular framework for jasmonate-induced inhibition of root growth through interaction with the growth regulator auxin. PMID:21954460

EBV induces persistent NF-κB activation and contributes to survival of EBV-positive neoplastic T- or NK-cells.

PubMed

Takada, Honami; Imadome, Ken-Ichi; Shibayama, Haruna; Yoshimori, Mayumi; Wang, Ludan; Saitoh, Yasunori; Uota, Shin; Yamaoka, Shoji; Koyama, Takatoshi; Shimizu, Norio; Yamamoto, Kouhei; Fujiwara, Shigeyoshi; Miura, Osamu; Arai, Ayako

2017-01-01

Epstein-Barr virus (EBV) has been detected in several T- and NK-cell neoplasms such as extranodal NK/T-cell lymphoma nasal type, aggressive NK-cell leukemia, EBV-positive peripheral T-cell lymphoma, systemic EBV-positive T-cell lymphoma of childhood, and chronic active EBV infection (CAEBV). However, how this virus contributes to lymphomagenesis in T or NK cells remains largely unknown. Here, we examined NF-κB activation in EBV-positive T or NK cell lines, SNT8, SNT15, SNT16, SNK6, and primary EBV-positive and clonally proliferating T/NK cells obtained from the peripheral blood of patients with CAEBV. Western blotting, electrophoretic mobility shift assays, and immunofluorescent staining revealed persistent NF-κB activation in EBV-infected cell lines and primary cells from patients. Furthermore, we investigated the role of EBV in infected T cells. We performed an in vitro infection assay using MOLT4 cells infected with EBV. The infection directly induced NF-κB activation, promoted survival, and inhibited etoposide-induced apoptosis in MOLT4 cells. The luciferase assay suggested that LMP1 mediated NF-κB activation in MOLT4 cells. IMD-0354, a specific inhibitor of NF-κB that suppresses NF-κB activation in cell lines, inhibited cell survival and induced apoptosis. These results indicate that EBV induces NF-κB-mediated survival signals in T and NK cells, and therefore, may contribute to the lymphomagenesis of these cells.

EBV induces persistent NF-κB activation and contributes to survival of EBV-positive neoplastic T- or NK-cells

PubMed Central

Shibayama, Haruna; Yoshimori, Mayumi; Wang, Ludan; Saitoh, Yasunori; Uota, Shin; Yamaoka, Shoji; Koyama, Takatoshi; Shimizu, Norio; Yamamoto, Kouhei; Fujiwara, Shigeyoshi; Miura, Osamu

2017-01-01

Epstein–Barr virus (EBV) has been detected in several T- and NK-cell neoplasms such as extranodal NK/T-cell lymphoma nasal type, aggressive NK-cell leukemia, EBV-positive peripheral T-cell lymphoma, systemic EBV-positive T-cell lymphoma of childhood, and chronic active EBV infection (CAEBV). However, how this virus contributes to lymphomagenesis in T or NK cells remains largely unknown. Here, we examined NF-κB activation in EBV-positive T or NK cell lines, SNT8, SNT15, SNT16, SNK6, and primary EBV-positive and clonally proliferating T/NK cells obtained from the peripheral blood of patients with CAEBV. Western blotting, electrophoretic mobility shift assays, and immunofluorescent staining revealed persistent NF-κB activation in EBV-infected cell lines and primary cells from patients. Furthermore, we investigated the role of EBV in infected T cells. We performed an in vitro infection assay using MOLT4 cells infected with EBV. The infection directly induced NF-κB activation, promoted survival, and inhibited etoposide-induced apoptosis in MOLT4 cells. The luciferase assay suggested that LMP1 mediated NF-κB activation in MOLT4 cells. IMD-0354, a specific inhibitor of NF-κB that suppresses NF-κB activation in cell lines, inhibited cell survival and induced apoptosis. These results indicate that EBV induces NF-κB-mediated survival signals in T and NK cells, and therefore, may contribute to the lymphomagenesis of these cells. PMID:28346502

Calibration of the head direction network: a role for symmetric angular head velocity cells.

PubMed

Stratton, Peter; Wyeth, Gordon; Wiles, Janet

2010-06-01

Continuous attractor networks require calibration. Computational models of the head direction (HD) system of the rat usually assume that the connections that maintain HD neuron activity are pre-wired and static. Ongoing activity in these models relies on precise continuous attractor dynamics. It is currently unknown how such connections could be so precisely wired, and how accurate calibration is maintained in the face of ongoing noise and perturbation. Our adaptive attractor model of the HD system that uses symmetric angular head velocity (AHV) cells as a training signal shows that the HD system can learn to support stable firing patterns from poorly-performing, unstable starting conditions. The proposed calibration mechanism suggests a requirement for symmetric AHV cells, the existence of which has previously been unexplained, and predicts that symmetric and asymmetric AHV cells should be distinctly different (in morphology, synaptic targets and/or methods of action on postsynaptic HD cells) due to their distinctly different functions.

Lymphocyte Electrotaxis in vitro and in vivo

PubMed Central

Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D.; Santiago, Juan G.; Butcher, Eugene C.

2008-01-01

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e. electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified transwell assay and a simple microfluidic device, we show that human peripheral blood lymphocytes migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well. PMID:18684937

Lymphocyte electrotaxis in vitro and in vivo.

PubMed

Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D; Santiago, Juan G; Butcher, Eugene C

2008-08-15

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e., electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified Transwell assay and a simple microfluidic device, we show that human PBLs migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well.

Mast cells express 11β-hydroxysteroid dehydrogenase type 1: a role in restraining mast cell degranulation.

PubMed

Coutinho, Agnes E; Brown, Jeremy K; Yang, Fu; Brownstein, David G; Gray, Mohini; Seckl, Jonathan R; Savill, John S; Chapman, Karen E

2013-01-01

Mast cells are key initiators of allergic, anaphylactic and inflammatory reactions, producing mediators that affect vascular permeability, angiogenesis and fibrosis. Glucocorticoid pharmacotherapy reduces mast cell number, maturation and activation but effects at physiological levels are unknown. Within cells, glucocorticoid concentration is modulated by the 11β-hydroxysteroid dehydrogenases (11β-HSDs). Here we show expression and activity of 11β-HSD1, but not 11β-HSD2, in mouse mast cells with 11β-HSD activity only in the keto-reductase direction, regenerating active glucocorticoids (cortisol, corticosterone) from inert substrates (cortisone, 11-dehydrocorticosterone). Mast cells from 11β-HSD1-deficient mice show ultrastructural evidence of increased activation, including piecemeal degranulation and have a reduced threshold for IgG immune complex-induced mast cell degranulation. Consistent with reduced intracellular glucocorticoid action in mast cells, levels of carboxypeptidase A3 mRNA, a glucocorticoid-inducible mast cell-specific transcript, are lower in peritoneal cells from 11β-HSD1-deficient than control mice. These findings suggest that 11β-HSD1-generated glucocorticoids may tonically restrain mast cell degranulation, potentially influencing allergic, anaphylactic and inflammatory responses.

Direct imaging of macrophage activation during PDT treatment

NASA Astrophysics Data System (ADS)

Song, Sheng; Zhou, Feifan; Chen, Wei R.; Xing, Da

2012-03-01

Mounting evidence describes a more complex progress of macrophage activation during photodynamic therapy (PDT), which performing distinct immunological functions and different physiologies on surrounding cells and tissues. Macrophage-targeted PDT has been applied in the selective killing of cells involved in inflammation and tumor. We have previously shown that PDT-mediated tumor cells apoptosis can induce a higher level immune response than necrosis, and enhance the macrophage activation. However, the molecular mechanism of macrophage activation during PDT-induced apoptotic cells (AC) still unclear. Here, we use confocal microscopy to image the phagocytosis of tumor cells by macrophages. We also observed that PDT-treated AC can activate Toll-like receptors (TLRs) which are present on macrophages surface. Besides, the increase in nitric oxide (NO) formation in macrophages was detected in real time by a laser scanning microscopy. This study provided more details for understanding the molecular mechanism of the immune response induced by PDT-treated AC.

Differential modulation of P-glycoprotein expression and activity by non-nucleoside HIV-1 reverse transcriptase inhibitors in cell culture.

PubMed

Störmer, Elke; von Moltke, Lisa L; Perloff, Michael D; Greenblatt, David J

2002-07-01

This study investigated the effects of the non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTI) nevirapine (NVR), efavirenz (EFV), and delavirdine (DLV) on P-glycoprotein (P-gp) activity and expression to anticipate P-gp related drug-drug interactions associated with combination therapy. NNRTIs were evaluated as P-gp substrates by measuring differential transport across Caco-2 cell monolayers. Inhibition of P-gp mediated rhodaminel23 (Rh123) transport in Caco-2 cells was used to assess P-gp inhibition by NNRTIs. Induction of P-gp expression and activity in LS180V cells following 3-day exposure to NNRTIs was measured by western blot analysis and cellular Rh123 uptake, respectively. The NNRTIs showed no differential transport between the basolateral to apical and apical to basolateral direction. NNRTI transport in either direction was not affected by the P-gp inhibitor verapamil. DLV inhibited Rh123 transport, causing a reduction to 15% of control at 100 microM (IC50 = 30 microM). NVR caused a concentration-dependent induction of P-gp expression in LS180V cells resulting in a 3.5-fold increase in immunoreactive P-gp at 100 microM NVR. Induction attributable to EFV and DLV was quantitatively smaller. NVR significantly reduced cellular uptake of Rh123 into LS180V cells, indicating increased drug efflux due to induced P-gp activity; effects of EFV and DLV were smaller. Acute DLV treatment of LS180V cells previously induced with NVR or ritonavir did not reverse the decreased Rh123 cell accumulation. NNRTIs show differential effects on P-gp activity and expression in vitro. Clinical studies are required to elucidate the clinical importance of potential drug interactions.

The MAZ transcription factor is a downstream target of the oncoprotein Cyr61/CCN1 and promotes pancreatic cancer cell invasion via CRAF-ERK signaling.

PubMed

Maity, Gargi; Haque, Inamul; Ghosh, Arnab; Dhar, Gopal; Gupta, Vijayalaxmi; Sarkar, Sandipto; Azeem, Imaan; McGregor, Douglas; Choudhary, Abhishek; Campbell, Donald R; Kambhampati, Suman; Banerjee, Sushanta K; Banerjee, Snigdha

2018-03-23

Myc-associated zinc-finger protein (MAZ) is a transcription factor with dual roles in transcription initiation and termination. Deregulation of MAZ expression is associated with the progression of pancreatic ductal adenocarcinoma (PDAC). However, the mechanism of action of MAZ in PDAC progression is largely unknown. Here, we present evidence that MAZ mRNA expression and protein levels are increased in human PDAC cell lines, tissue samples, a subcutaneous tumor xenograft in a nude mouse model, and spontaneous cancer in the genetically engineered PDAC mouse model. We also found that MAZ is predominantly expressed in pancreatic cancer stem cells. Functional analysis indicated that MAZ depletion in PDAC cells inhibits invasive phenotypes such as the epithelial-to-mesenchymal transition, migration, invasion, and the sphere-forming ability of PDAC cells. Mechanistically, we detected no direct effects of MAZ on the expression of K-Ras mutants, but MAZ increased the activity of CRAF-ERK signaling, a downstream signaling target of K-Ras. The MAZ-induced activation of CRAF-ERK signaling was mediated via p21-activated protein kinase (PAK) and protein kinase B (AKT/PKB) signaling cascades and promoted PDAC cell invasiveness. Moreover, we found that the matricellular oncoprotein cysteine-rich angiogenic inducer 61 (Cyr61/CCN1) regulates MAZ expression via Notch-1-sonic hedgehog signaling in PDAC cells. We propose that Cyr61/CCN1-induced expression of MAZ promotes invasive phenotypes of PDAC cells not through direct K-Ras activation but instead through the activation of CRAF-ERK signaling. Collectively, these results highlight key molecular players in PDAC invasiveness and may help inform therapeutic strategies to improve clinical management and outcomes of PDAC.

Role of the Stem Cell Niche in Hormone-Induced Tumorigenesis in Fetal Mouse Mammary Epithelium

DTIC Science & Technology

2005-08-01

responsive, self renewing and pluripotent. A structure specialized to contain and regulate stem cell activity has been structurally and molecularly...described in Drosophila and some mammalian tissues. The structure, the stem cell niche, functions to 1) shield the stem cell from the burden of incoming...directing stem cell renewal and maturation, 3) prevent stem cells from wandering through the tissue and producing new cells inappropriately, 4) prevent

Mechanisms of inhibition by fluoride of urease activities of cell suspensions and biofilms of Staphylococcus epidermidis, Streptococcus salivarius, Actinomyces naeslundii and of dental plaque.

PubMed

Barboza-Silva, E; Castro, A C D; Marquis, R E

2005-12-01

Fluoride is known to be a potent inhibitor of bacterial ureases and can also act in the form of hydrofluoric acid as a transmembrane proton conductor to acidify the cytoplasm of intact cells with possible indirect, acid inhibition of urease. Our research objectives were to assess the inhibitory potencies of fluoride for three urease-positive bacteria commonly found in the mouth and to determine the relative importance of direct and indirect inhibition of ureases for overall inhibition of intact cells or biofilms. The experimental design involved intact bacteria in suspensions, mono-organism biofilms, cell extracts, and dental plaque. Standard enzymatic assays for ammonia production from urea were used. We found that ureolysis by cells in suspensions or mono-organism biofilms of Staphylococcus epidermidis, Streptococcus salivarius or Actinomyces naeslundii was inhibited by fluoride at plaque levels of 0.1-0.5 mm in a pH-dependent manner. The results of experiments with the organic weak acids indomethacin and capric acid, which do not directly inhibit urease enzyme, indicated that weak-acid effects leading to cytoplasmic acidification are also involved in fluoride inhibition. However, direct fluoride inhibition of urease appeared to be the major mechanism for reduction in ureolytic activity in acid environments. Results of experiments with freshly harvested supragingival dental plaque indicated responses to fluoride similar to those of S. salivarius with pH-dependent fluoride inhibition and both direct and indirect inhibition of urease. Fluoride can act to diminish alkali production from urea by oral bacteria through direct and indirect mechanisms.

G-protein-coupled receptor-2-interacting protein-1 is required for endothelial cell directional migration and tumor angiogenesis via cortactin-dependent lamellipodia formation.

PubMed

Majumder, Syamantak; Sowden, Mark P; Gerber, Scott A; Thomas, Tamlyn; Christie, Christine K; Mohan, Amy; Yin, Guoyong; Lord, Edith M; Berk, Bradford C; Pang, Jinjiang

2014-02-01

Recent evidence suggests G-protein-coupled receptor-2-interacting protein-1 (GIT1) overexpression in several human metastatic tumors, including breast, lung, and prostate. Tumor metastasis is associated with an increase in angiogenesis. We have showed previously that GIT1 is required for postnatal angiogenesis during lung development. However, the functional role of GIT1 in pathological angiogenesis during tumor growth is unknown. In the present study, we show inhibition of angiogenesis in matrigel implants as well as reduced tumor angiogenesis and melanoma tumor growth in GIT1-knockout mice. We demonstrate that this is a result of impaired directional migration of GIT1-depleted endothelial cells toward a vascular endothelial growth factor gradient. Cortactin-mediated lamellipodia formation in the leading edge is critical for directional migration. We observed a significant reduction in cortactin localization and lamellipodia formation in the leading edge of GIT1-depleted endothelial cells. We specifically identified that the Spa homology domain (aa 250-420) of GIT1 is required for GIT1-cortactin complex localization to the leading edge. The mechanisms involved extracellular signal-regulated kinases 1 and 2-mediated Cortactin-S405 phosphorylation and activation of Rac1/Cdc42. Finally, using gain of function studies, we show that a constitutively active mutant of cortactin restored directional migration of GIT1-depleted cells. Our data demonstrated that a GIT1-cortactin association through GIT1-Spa homology domain is required for cortactin localization to the leading edge and is essential for endothelial cell directional migration and tumor angiogenesis.

Capturing the genetic makeup of the active microbiome in situ.

PubMed

Singer, Esther; Wagner, Michael; Woyke, Tanja

2017-09-01

More than any other technology, nucleic acid sequencing has enabled microbial ecology studies to be complemented with the data volumes necessary to capture the extent of microbial diversity and dynamics in a wide range of environments. In order to truly understand and predict environmental processes, however, the distinction between active, inactive and dead microbial cells is critical. Also, experimental designs need to be sensitive toward varying population complexity and activity, and temporal as well as spatial scales of process rates. There are a number of approaches, including single-cell techniques, which were designed to study in situ microbial activity and that have been successively coupled to nucleic acid sequencing. The exciting new discoveries regarding in situ microbial activity provide evidence that future microbial ecology studies will indispensably rely on techniques that specifically capture members of the microbiome active in the environment. Herein, we review those currently used activity-based approaches that can be directly linked to shotgun nucleic acid sequencing, evaluate their relevance to ecology studies, and discuss future directions.

Capturing the genetic makeup of the active microbiome in situ

PubMed Central

Singer, Esther; Wagner, Michael; Woyke, Tanja

2017-01-01

More than any other technology, nucleic acid sequencing has enabled microbial ecology studies to be complemented with the data volumes necessary to capture the extent of microbial diversity and dynamics in a wide range of environments. In order to truly understand and predict environmental processes, however, the distinction between active, inactive and dead microbial cells is critical. Also, experimental designs need to be sensitive toward varying population complexity and activity, and temporal as well as spatial scales of process rates. There are a number of approaches, including single-cell techniques, which were designed to study in situ microbial activity and that have been successively coupled to nucleic acid sequencing. The exciting new discoveries regarding in situ microbial activity provide evidence that future microbial ecology studies will indispensably rely on techniques that specifically capture members of the microbiome active in the environment. Herein, we review those currently used activity-based approaches that can be directly linked to shotgun nucleic acid sequencing, evaluate their relevance to ecology studies, and discuss future directions. PMID:28574490

HIV antibodies for treatment of HIV infection

PubMed Central

Margolis, David M.; Koup, Richard A.; Ferrari, Guido

2016-01-01

Summary The bar is high to improve on current combination antiretroviral therapy (ART), now highly effective, safe, and simple. However antibodies that bind the HIV envelope are able to uniquely target the virus as it seeks to enter new target cells, or as it is expressed from previously infected cells. Further, the use of antibodies against HIV as a therapeutic may offer advantages. Antibodies can have long half-lives, and are being considered as partners for long-acting antiretrovirals for use in therapy or prevention of HIV infection. Early studies in animal models and in clinical trials suggest that such antibodies can have antiviral activity but, as with small molecule antiretrovirals, the issues of viral escape and resistance will have to be addressed. Most promising, however, are the unique properties of anti-HIV antibodies: the potential ability to opsonize viral particles, to direct antibody-dependent cellular cytotoxicity (ADCC) against actively infected cells, and ultimately the ability to direct the clearance of HIV-infected cells by effector cells of the immune system. These distinctive activities suggest that HIV antibodies and their derivatives may play an important role in the next frontier of HIV therapeutics, the effort to develop treatments that could lead to an HIV cure. PMID:28133794

Saponins from soy bean and mung bean inhibit the antigen specific activation of helper T cells by blocking cell cycle progression.

PubMed

Lee, Suk Jun; Bae, Joonbeom; Kim, Sunhee; Jeong, Seonah; Choi, Chang-Yong; Choi, Sang-Pil; Kim, Hyun-Sook; Jung, Woon-Won; Imm, Jee-Young; Kim, Sae Hun; Chun, Taehoon

2013-02-01

Treatment of helper T (Th) cells with saponins from soy bean and mung bean prevented their activation by inhibiting cell proliferation and cytokine secretion. However, the saponins did not affect the expression of major histocompatibility complex class II (A(b)) and co-stimulatory molecule (CD86) on professional antigen-presenting cells. Instead, the saponins directly inhibited Th cell proliferation by blocking the G(1) to S phase cell cycle transition. Moreover, blocking of the cell cycle by the saponins was achieved by decreased expression of cyclin D1 and cyclin E, and constitutive expression of p27(KIP1). Saponins also increased stability of p27(KIP1) in Th cells after antigenic stimulation.

Apolipoprotein CIII-induced THP-1 cell adhesion to endothelial cells involves pertussis toxin-sensitive G protein- and protein kinase C alpha-mediated nuclear factor-kappaB activation.

PubMed

Kawakami, Akio; Aikawa, Masanori; Nitta, Noriko; Yoshida, Masayuki; Libby, Peter; Sacks, Frank M

2007-01-01

Plasma apolipoprotein CIII (apoCIII) independently predicts risk for coronary heart disease (CHD). We recently reported that apoCIII directly enhances adhesion of human monocytes to endothelial cells (ECs), and identified the activation of PKC alpha as a necessary upstream event of enhanced monocyte adhesion. This study tested the hypothesis that apoCIII activates PKC alpha in human monocytic THP-1 cells, leading to NF-kappaB activation. Among inhibitors specific to PKC activators, phosphatidylcholine-specific phospholipase C (PC-PLC) inhibitor D609 limited apoCIII-induced PKC alpha activation and THP-1 cell adhesion. ApoCIII increased PC-PLC activity in THP-1 cells, resulting in PKC alpha activation. Pertussis toxin (PTX) inhibited apoCIII-induced PC-PLC activation and subsequent PKC alpha activation, implicating PTX-sensitive G protein pathway. ApoCIII further activated nuclear factor-kappaB (NF-kappaB) through PKC alpha in THP-1 cells and augmented beta1-integrin expression. The NF-kappaB inhibitor peptide SN50 partially inhibited apoCIII-induced beta1-integrin expression and THP-1 cell adhesion. ApoCIII-rich VLDL had similar effects to apoCIII alone. PTX-sensitive G protein pathway participates critically in PKC alpha stimulation in THP-1 cells exposed to apoCIII, activating NF-kappaB, and increasing beta1-integrin. This action causes monocytic cells to adhere to endothelial cells. Furthermore, because leukocyte NF-kappaB activation contributes to inflammatory aspects of atherogenesis, apoCIII may stimulate diverse inflammatory responses through monocyte activation.

CD3ζ-based chimeric antigen receptors mediate T cell activation via cis- and trans-signalling mechanisms: implications for optimization of receptor structure for adoptive cell therapy

PubMed Central

Bridgeman, J S; Ladell, K; Sheard, V E; Miners, K; Hawkins, R E; Price, D A; Gilham, D E

2014-01-01

Chimeric antigen receptors (CARs) can mediate redirected lysis of tumour cells in a major histocompatibility complex (MHC)-independent manner, thereby enabling autologous adoptive T cell therapy for a variety of malignant neoplasms. Currently, most CARs incorporate the T cell receptor (TCR) CD3ζ signalling chain; however, the precise mechanisms responsible for CAR-mediated T cell activation are unclear. In this study, we used a series of immunoreceptor tyrosine-based activation motif (ITAM)-mutant and transmembrane-modified receptors to demonstrate that CARs activate T cells both directly via the antigen-ligated signalling chain and indirectly via associated chains within the TCR complex. These observations allowed us to generate new receptors capable of eliciting polyfunctional responses in primary human T cells. This work increases our understanding of CAR function and identifies new avenues for the optimization of CAR-based therapeutic interventions. PMID:24116999

Directed evolution of enzymes using microfluidic chips

NASA Astrophysics Data System (ADS)

Pilát, Zdeněk.; Ježek, Jan; Šmatlo, Filip; Kaůka, Jan; Zemánek, Pavel

2016-12-01

Enzymes are highly versatile and ubiquitous biological catalysts. They can greatly accelerate large variety of reactions, while ensuring appropriate catalytic activity and high selectivity. These properties make enzymes attractive biocatalysts for a wide range of industrial and biomedical applications. Over the last two decades, directed evolution of enzymes has transformed the field of protein engineering. We have devised microfluidic systems for directed evolution of haloalkane dehalogenases in emulsion droplets. In such a device, individual bacterial cells producing mutated variants of the same enzyme are encapsulated in microdroplets and supplied with a substrate. The conversion of a substrate by the enzyme produced by a single bacterium changes the pH in the droplet which is signalized by pH dependent fluorescence probe. The droplets with the highest enzymatic activity can be separated directly on the chip by dielectrophoresis and the resultant cell lineage can be used for enzyme production or for further rounds of directed evolution. This platform is applicable for fast screening of large libraries in directed evolution experiments requiring mutagenesis at multiple sites of a protein structure.

Infection-induced regulation of natural killer cells by macrophages and collagen at the lymph node subcapsular sinus.

PubMed

Coombes, Janine L; Han, Seong-Ji; van Rooijen, Nico; Raulet, David H; Robey, Ellen A

2012-07-26

Infection leads to heightened activation of natural killer (NK) cells, a process that likely involves direct cell-to-cell contact, but how this occurs in vivo is poorly understood. We have used two-photon laser-scanning microscopy in conjunction with Toxoplasma gondii mouse infection models to address this question. We found that after infection, NK cells accumulated in the subcapsular region of the lymph node, where they formed low-motility contacts with collagen fibers and CD169(+) macrophages. We provide evidence that interactions with collagen regulate NK cell migration, whereas CD169(+) macrophages increase the activation state of NK cells. Interestingly, a subset of CD169(+) macrophages that coexpress the inflammatory monocyte marker Ly6C had the most potent ability to activate NK cells. Our data reveal pathways through which NK cell migration and function are regulated after infection and identify an important accessory cell population for activation of NK cell responses in lymph nodes. Copyright © 2012 The Authors. Published by Elsevier Inc. All rights reserved.

Where is the lithium? Quantitative determination of the lithium distribution in lithium ion battery cells: Investigations on the influence of the temperature, the C-rate and the cell type

NASA Astrophysics Data System (ADS)

Vortmann-Westhoven, Britta; Winter, Martin; Nowak, Sascha

2017-04-01

With lithium being the capacity determining species in lithium-ion battery (LIB) cells, the local quantification is of enormous importance for understanding of the cell performance. The investigation of the lithium distribution in LIB full cells is performed with two different cell types, T-cells of the Swagelok® type and pouch bag cells with lithium nickel cobalt manganese oxide and mesocarbon microbead graphite as the active materials as well as a lithium hexafluorophosphate based organic carbonate solvent electrolyte. The lithium content of/at the individual components of the cells is analyzed for different states of charge (SOCs) by inductively coupled plasma-optical emission spectrometry (ICP-OES) and the lithium distribution as well as the loss of active lithium within the cells is calculated after cycling. With increasing the SOC, the lithium contents decrease in the cathodes and simultaneously increase in the anodes. The temperature increase shows a clear shift of the lithium content in the direction of the anode for the T-cells. The comparison of the C-rate influence shows that the lower the C-rate, the more the lithium content on the electrodes is shifted into the direction of the anode.

Dietary n-3 PUFA affect TcR-mediated activation of purified murine T cells and accessory cell function in co-cultures

PubMed Central

CHAPKIN, R S; ARRINGTON, J L; APANASOVICH, T V; CARROLL, R J; MCMURRAY, D N

2002-01-01

Diets enriched in n-3 polyunsaturated fatty acids (PUFA) suppress several functions of murine splenic T cells by acting directly on the T cells and/or indirectly on accessory cells. In this study, the relative contribution of highly purified populations of the two cell types to the dietary suppression of T cell function was examined. Mice were fed diets containing different levels of n-3 PUFA; safflower oil (SAF; control containing no n-3 PUFA), fish oil (FO) at 2% and 4%, or 1% purified docosahexaenoic acid (DHA) for 2 weeks. Purified (>90%) T cells were obtained from the spleen, and accessory cells (>95% adherent, esterase-positive) were obtained by peritoneal lavage. Purified T cells or accessory cells from each diet group were co-cultured with the alternative cell type from every other diet group, yielding a total of 16 different co-culture combinations. The T cells were stimulated with either concanavalin A (ConA) or antibodies to the T cell receptor (TcR)/CD3 complex and the costimulatory molecule CD28 (αCD3/αCD28), and proliferation was measured after four days. Suppression of T cell proliferation in the co-cultures was dependent upon the dose of dietary n-3 PUFA fed to mice from which the T cells were derived, irrespective of the dietary treatment of accessory cell donors. The greatest dietary effect was seen in mice consuming the DHA diet (P = 0·034 in the anova; P = 0·0053 in the Trend Test), and was observed with direct stimulation of the T cell receptor and CD28 costimulatory ligand, but not with ConA. A significant dietary effect was also contributed accessory cells (P = 0·033 in the Trend Test). We conclude that dietary n-3 PUFA affect TcR-mediated by T cell activation by both direct and indirect (accessory cell) mechanisms. PMID:12296847

Significant promotion effect of carbon nanotubes on the electrocatalytic activity of supported Pd NPs for ethanol oxidation reaction of fuel cells: the role of inner tubes.

PubMed

Zhang, Jin; Cheng, Yi; Lu, Shanfu; Jia, Lichao; Shen, Pei Kang; Jiang, San Ping

2014-11-18

The inner tubes of carbon nanotubes (CNTs) have a significant promotion effect on the electrocatalytic activity of Pd nanoparticles (NPs) for the ethanol oxidation of direct alcohol fuel cells (DAFCs) and Pd NPs supported on CNTs with 3-7 walls show a much higher activity as compared to that supported on typical single-walled and multi-walled CNTs.

Final Report: Mass Production Cost Estimation of Direct H2 PEM Fuel Cell Systems for Transportation Applications (2012-2016)

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, Brian David; Huya-Kouadio, Jennie Moton; Houchins, Cassidy

This report summarizes project activities for Strategic Analysis, Inc. (SA) Contract Number DE-EE0005236 to the U.S. Department of Energy titled “Transportation Fuel Cell System Cost Assessment”. The project defined and projected the mass production costs of direct hydrogen Proton Exchange Membrane fuel cell power systems for light-duty vehicles (automobiles) and 40-foot transit buses. In each year of the five-year contract, the fuel cell power system designs and cost projections were updated to reflect technology advances. System schematics, design assumptions, manufacturing assumptions, and cost results are presented.

Activation of human T cells in hypertension: Studies of Humanized Mice and Hypertensive Humans

PubMed Central

Itani, Hana A.; McMaster, William G.; Saleh, Mohamed A.; Nazarewicz, Rafal R.; Mikolajczyk, Tomasz P.; Kaszuba, Anna; Konior, Anna; Prejbisz, Aleksander; Januszewicz, Andrzej; Norlander, Allison E.; Chen, Wei; Bonami, Rachel H.; Marshall, Andrew F.; Poffenberger, Greg; Weyand, Cornelia M.; Madhur, Meena S.; Moore, Daniel J.; Harrison, David G.; Guzik, Tomasz J.

2016-01-01

Emerging evidence supports an important role for T cells in the genesis of hypertension. Because this work has predominantly been performed in experimental animals, we sought to determine whether human T cells are activated in hypertension. We employed a humanized mouse model in which the murine immune system is replaced by the human immune system. Angiotensin II increased systolic pressure to 162 mm Hg vs. 116 mm Hg for sham treated animals. Flow cytometry of thoracic lymph nodes, thoracic aorta and kidney revealed increased infiltration of human leukocytes (CD45+) and T lymphocytes (CD3+ and CD4+) in response to angiotensin II infusion. Interestingly, there was also an increase in the memory T cells (CD3+/CD45RO+) in the aortas and lymph nodes. Prevention of hypertension using hydralazine and hydrochlorothiazide prevented the accumulation of T cells in these tissues. Studies of isolated human T cells and monocytes indicated that angiotensin II had no direct effect on cytokine production by T cells or the ability of dendritic cells to drive T cell proliferation. We also observed an increase in circulating IL-17A producing CD4+ T cells and both CD4+ and CD8+ T cells that produce IFN-γ in hypertensive compared to normotensive humans. Thus, human T cells become activated and invade critical end-organ tissues in response to hypertension in a humanized mouse model. This response likely reflects the hypertensive milieu encountered in vivo and is not a direct effect of the hormone angiotensin II. PMID:27217403

Activation of Human T Cells in Hypertension: Studies of Humanized Mice and Hypertensive Humans.

PubMed

Itani, Hana A; McMaster, William G; Saleh, Mohamed A; Nazarewicz, Rafal R; Mikolajczyk, Tomasz P; Kaszuba, Anna M; Konior, Anna; Prejbisz, Aleksander; Januszewicz, Andrzej; Norlander, Allison E; Chen, Wei; Bonami, Rachel H; Marshall, Andrew F; Poffenberger, Greg; Weyand, Cornelia M; Madhur, Meena S; Moore, Daniel J; Harrison, David G; Guzik, Tomasz J

2016-07-01

Emerging evidence supports an important role for T cells in the genesis of hypertension. Because this work has predominantly been performed in experimental animals, we sought to determine whether human T cells are activated in hypertension. We used a humanized mouse model in which the murine immune system is replaced by the human immune system. Angiotensin II increased systolic pressure to 162 versus 116 mm Hg for sham-treated animals. Flow cytometry of thoracic lymph nodes, thoracic aorta, and kidney revealed increased infiltration of human leukocytes (CD45(+)) and T lymphocytes (CD3(+) and CD4(+)) in response to angiotensin II infusion. Interestingly, there was also an increase in the memory T cells (CD3(+)/CD45RO(+)) in the aortas and lymph nodes. Prevention of hypertension using hydralazine and hydrochlorothiazide prevented the accumulation of T cells in these tissues. Studies of isolated human T cells and monocytes indicated that angiotensin II had no direct effect on cytokine production by T cells or the ability of dendritic cells to drive T-cell proliferation. We also observed an increase in circulating interleukin-17A producing CD4(+) T cells and both CD4(+) and CD8(+) T cells that produce interferon-γ in hypertensive compared with normotensive humans. Thus, human T cells become activated and invade critical end-organ tissues in response to hypertension in a humanized mouse model. This response likely reflects the hypertensive milieu encountered in vivo and is not a direct effect of the hormone angiotensin II. © 2016 American Heart Association, Inc.

Antitumor activity of Type I and Type III interferons in BNL hepatoma model

PubMed Central

Abushahba, Walid; Balan, Murugabaskar; Castaneda, Ismael; Yuan, Yao; Reuhl, Kenneth; Raveche, Elizabeth; de la Torre, Andrew

2015-01-01

Hepatocellular carcinoma (HCC) occurs most commonly secondary to cirrhosis due to chronic hepatitis C or B virus (HCV/HBV) infections. Type I interferon (IFN-α) treatment of chronic HCV/HBV infections reduces the incidence of HCC in cirrhotic patients. However, IFN-α toxicity limits its tolerability and efficacy highlighting a need for better therapeutic treatments. A recently discovered type III IFN (IFN-λ) has been shown to possess antiviral properties against HCV and HBV in vitro. In phase I clinical trials, IFN-λ treatment did not cause significant adverse reactions. Using a gene therapy approach, we compared the antitumor properties of IFN-α and IFN-λ in a transplantable hepatoma model of HCC. BALB/c mice were inoculated with syngeneic BNL hepatoma cells, or BNL cells expressing IFN-λ (BNL.IFN-λ cells) or IFN-α (BNL.IFN-α cells). Despite the lack of antiproliferative activity of IFNs on BNL cells, both BNL.IFN-λ and BNL.IFN-α cells displayed retarded growth kinetics in vivo. Depletion of NK cells from splenocytes inhibited splenocyte-mediated cytotoxicity, demonstrating that NK cells play a role in IFN-induced antitumor responses. However, isolated NK cells did not respond directly to IFN-λ. There was also a marked NK cell infiltration in IFN-λ producing tumors. In addition, IFN-λ and, to a lesser extent, IFN-α enhanced immunocytotoxicity of splenocytes primed with irradiated BNL cells. Splenocyte cytotoxicity against BNL cells was dependent on IL-12 and IFN-λ, and mediated by dendritic cells. In contrast to NK cells, isolated from spleen CD1 1c+ and mPDCA+ dendritic cells responded directly to IFN-λ. The antitumor activities of IFN-λ against hepatoma, in combination with HCV and HBV antiviral activities warrant further investigation into the clinical use of IFN-λ to prevent HCC in HCV/HBV-infected cirrhotic patients, as well as to treat liver cancer. PMID:20217081

Antitumor activity of type I and type III interferons in BNL hepatoma model.

PubMed

Abushahba, Walid; Balan, Murugabaskar; Castaneda, Ismael; Yuan, Yao; Reuhl, Kenneth; Raveche, Elizabeth; de la Torre, Andrew; Lasfar, Ahmed; Kotenko, Sergei V

2010-07-01

Hepatocellular carcinoma (HCC) occurs most commonly secondary to cirrhosis due to chronic hepatitis C or B virus (HCV/HBV) infections. Type I interferon (IFN-alpha) treatment of chronic HCV/HBV infections reduces the incidence of HCC in cirrhotic patients. However, IFN-alpha toxicity limits its tolerability and efficacy highlighting a need for better therapeutic treatments. A recently discovered type III IFN (IFN-lambda) has been shown to possess antiviral properties against HCV and HBV in vitro. In phase I clinical trials, IFN-lambda treatment did not cause significant adverse reactions. Using a gene therapy approach, we compared the antitumor properties of IFN-alpha and IFN-lambda in a transplantable hepatoma model of HCC. BALB/c mice were inoculated with syngeneic BNL hepatoma cells, or BNL cells expressing IFN-lambda (BNL.IFN-lambda cells) or IFN-alpha (BNL.IFN-alpha cells). Despite the lack of antiproliferative activity of IFNs on BNL cells, both BNL.IFN-lambda and BNL.IFN-alpha cells displayed retarded growth kinetics in vivo. Depletion of NK cells from splenocytes inhibited splenocyte-mediated cytotoxicity, demonstrating that NK cells play a role in IFN-induced antitumor responses. However, isolated NK cells did not respond directly to IFN-lambda. There was also a marked NK cell infiltration in IFN-lambda producing tumors. In addition, IFN-lambda and, to a lesser extent, IFN-alpha enhanced immunocytotoxicity of splenocytes primed with irradiated BNL cells. Splenocyte cytotoxicity against BNL cells was dependent on IL-12 and IFN-gamma, and mediated by dendritic cells. In contrast to NK cells, isolated from spleen CD11c+ and mPDCA+ dendritic cells responded directly to IFN-lambda. The antitumor activities of IFN-lambda against hepatoma, in combination with HCV and HBV antiviral activities warrant further investigation into the clinical use of IFN-lambda to prevent HCC in HCV/HBV-infected cirrhotic patients, as well as to treat liver cancer.

Endothelial dysfunction in dengue virus pathology.

PubMed

Vervaeke, Peter; Vermeire, Kurt; Liekens, Sandra

2015-01-01

Dengue virus (DENV) is a leading cause of illness and death, mainly in the (sub)tropics, where it causes dengue fever and/or the more serious diseases dengue hemorrhagic fever and dengue shock syndrome that are associated with changes in vascular permeability. Despite extensive research, the pathogenesis of DENV is still poorly understood and, although endothelial cells represent the primary fluid barrier of the blood vessels, the extent to which these cells contribute to DENV pathology is still under debate. The primary target cells for DENV are dendritic cells and monocytes/macrophages that release various chemokines and cytokines upon infection, which can activate the endothelium and are thought to play a major role in DENV-induced vascular permeability. However, recent studies indicate that DENV also replicates in endothelial cells and that DENV-infected endothelial cells may directly contribute to viremia, immune activation, vascular permeability and immune targeting of the endothelium. Also, the viral non-structural protein-1 and antibodies directed against this secreted protein have been reported to be involved in endothelial cell dysfunction. This review provides an extensive overview of the effects of DENV infection on endothelial cell physiology and barrier function. Copyright © 2014 John Wiley & Sons, Ltd.

Human Natural Killer Cells Exhibit Direct Activity Against Aspergillus fumigatus Hyphae, But Not Against Resting Conidia

PubMed Central

Schmidt, Stanislaw; Tramsen, Lars; Hanisch, Mitra; Latgé, Jean-Paul; Huenecke, Sabine; Koehl, Ulrike

2011-01-01

Because natural killer (NK) cells kill tumor cells and combat infections, there is growing interest in adoptively transferring NK cells to hematopoietic stem cell recipients. Unfortunately, in humans, the activity of NK cells against Aspergillus species, the major cause of invasive fungal infection in stem cell recipients, are poorly characterized. Our results show that unstimulated and interleukin-2 prestimulated human NK cells kill Aspergillus fumigatus hyphae but do not affect resting conidia. Killing is also induced by the supernatant of prestimulated NK cells and human perforin. The high levels of interferon-γ and granulocyte macrophage colony-stimulating factor produced by prestimulated NK cells are significantly reduced by Aspergillus, indicating an immunosuppressive effect of the fungus. Whereas Aspergillus hyphae activate NK cells, resting, and germinating, conidia and conidia of ΔrodA mutants lacking the hydrophobic surface layer do not. Our results suggest that adoptively transferred human NK cells may be a potential antifungal tool in the transplantation context. PMID:21208932

Downregulation of telomerase activity in human promyelocytic cell line using RNA interference.

PubMed

Miri-Moghaddam, E; Deezagi, A; Soheili, Z S

2009-12-01

Telomerase is a ribonucleoprotein complex. It consists of two main components, human telomerase reverse transcriptase (hTERT) and human telomerase RNA. High telomerase activity is present in most malignant cells, but it is barely detectable in majority of somatic cells. The direct correlation between telomerase reactivation and carcinogens has made hTERT a key target for anticancer therapeutic studies. In this study, for the first time, we evaluated the ability of the new generation of short interfering RNA (siRNA) to regulate telomerase activity in the human promyelocytic leukemia cell line (HL-60). Transient transfection cell line by hTERT siRNAs resulted in statistically significant suppression of hTERT messenger RNAs which were detected by quantitative real-time polymerase chain reaction, while the expressed hTERT protein levels were measured by flow cytometry. The results of telomeric repeat amplification protocol showed that telomerase activity was significantly reduced upon transfection of the HL-60 cell line with hTERT siRNAs. The results of this study showed that telomerase activity and cell proliferation were efficiently inhibited in the hTERT siRNA-treated leukemic cell line.

NAD+ depletion or PAR polymer formation: which plays the role of executioner in ischaemic cell death?

PubMed

Siegel, C; McCullough, L D

2011-09-01

Multiple cell death pathways are activated in cerebral ischaemia. Much of the initial injury, especially in the core of the infarct where cerebral blood flow is severely reduced, is necrotic and secondary to severe energy failure. However, there is considerable evidence that delayed cell death continues for several days, primarily in the penumbral region. As reperfusion therapies grow in number and effectiveness, restoration of blood flow early after injury may lead to a shift towards apoptosis. It is important to elucidate what are the key mediators of apoptotic cell death after stroke, as inhibition of apoptosis may have therapeutic implications. There are two well described pathways that lead to apoptotic cell death; the caspase pathway and the more recently described caspase-independent pathway triggered by poly-ADP-ribose polymers (PARP) activation. Caspase-induced cell death is initiated by release of mitochondrial cytochrome c, formation of the cytosolic apoptosome, and activation of endonucleases leading to a multitude of small randomly cleaved DNA fragments. In contrast caspase-independent cell death is secondary to activation of apoptosis inducing factor (AIF). Mitochondrial AIF translocates to the nucleus, where it induces peripheral chromatin condensation, as well as characteristic high-molecular-weight (50 kbp) DNA fragmentation. Although caspase-independent cell death has been recognized for some time and is known to contribute to ischaemic injury, the upstream triggering events leading to activation of this pathway remain unclear. The two major theories are that ischaemia leads to nicotinamide adenine dinucleotide (NAD+) depletion and subsequent energy failure, or alternatively that cell death is directly triggered by a pro-apoptotic factor produced by activation of the DNA repair enzyme PARP. PARP activation is robust in the ischaemic brain producing variable lengths of poly-ADP-ribose (PAR) polymers as byproducts of PARP activation. PAR polymers may be directly toxic by triggering mitochondrial AIF release independently of NAD+ depletion. Recently, sex differences have been discovered that illustrate the importance of understanding these molecular pathways, especially as new therapeutics targeting apoptotic cell death are developed. Cell death in females proceeds primarily via caspase activation whereas caspase-independent mechanisms triggered by the activation of PARP predominate in the male brain. This review summarizes the current literature in an attempt to clarify the roles of NAD+ and PAR polymers in caspase-independent cell death, and discuss sex specific cell death to provide an example of the possible importance of these downstream mediators. © 2011 The Authors. Acta Physiologica © 2011 Scandinavian Physiological Society.

PAS kinase is activated by direct SNF1-dependent phosphorylation and mediates inhibition of TORC1 through the phosphorylation and activation of Pbp1.

PubMed

DeMille, Desiree; Badal, Bryan D; Evans, J Brady; Mathis, Andrew D; Anderson, Joseph F; Grose, Julianne H

2015-02-01

We describe the interplay between three sensory protein kinases in yeast: AMP-regulated kinase (AMPK, or SNF1 in yeast), PAS kinase 1 (Psk1 in yeast), and the target of rapamycin complex 1 (TORC1). This signaling cascade occurs through the SNF1-dependent phosphorylation and activation of Psk1, which phosphorylates and activates poly(A)- binding protein binding protein 1 (Pbp1), which then inhibits TORC1 through sequestration at stress granules. The SNF1-dependent phosphorylation of Psk1 appears to be direct, in that Snf1 is necessary and sufficient for Psk1 activation by alternate carbon sources, is required for altered Psk1 protein mobility, is able to phosphorylate Psk1 in vitro, and binds Psk1 via its substrate-targeting subunit Gal83. Evidence for the direct phosphorylation and activation of Pbp1 by Psk1 is also provided by in vitro and in vivo kinase assays, including the reduction of Pbp1 localization at distinct cytoplasmic foci and subsequent rescue of TORC1 inhibition in PAS kinase-deficient yeast. In support of this signaling cascade, Snf1-deficient cells display increased TORC1 activity, whereas cells containing hyperactive Snf1 display a PAS kinase-dependent decrease in TORC1 activity. This interplay between yeast SNF1, Psk1, and TORC1 allows for proper glucose allocation during nutrient depletion, reducing cell growth and proliferation when energy is low. © 2015 DeMille et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

The differentiation and protective function of cytolytic CD4 T cells in influenza infection

USDA-ARS?s Scientific Manuscript database

CD4 T cells that recognize peptide antigen in the context of Class II MHC can differentiate into various subsets that are characterized by their helper functions. However, increasing evidence indicates that CD4 cells with direct cytolytic activity play a role in chronic, as well as, acute infections...

Measuring P-V-T Phase Behavior with a Variable Volume View Cell

ERIC Educational Resources Information Center

Hoffmann, Markus M.; Salter, Jason D.

2004-01-01

An experiment using a variable volume cell is presented where students actively control and directly observe the phase equilibrium inside the view cell. Measuring and exploring P-V-T phase behavior through dielectric constant measurements conveys the important concept that solvent behavior can be changed continuously in the sc fluid state.

The haemagglutination activity of equine herpesvirus type 1 glycoprotein C.

PubMed

Andoh, Kiyohiko; Hattori, Shiho; Mahmoud, Hassan Y A H; Takasugi, Maaya; Shimoda, Hiroshi; Bannai, Hiroshi; Tsujimura, Koji; Matsumura, Tomio; Kondo, Takashi; Kirisawa, Rikio; Mochizuki, Masami; Maeda, Ken

2015-01-02

Equine herpesvirus type 1 (EHV-1) has haemagglutination (HA) activity toward equine red blood cells (RBCs), but the identity of its haemagglutinin is unknown. To identify the haemagglutinin of EHV-1, the major glycoproteins of EHV-1 were expressed in 293T cells, and the cells or cell lysates were mixed with equine RBCs. The results showed that only EHV-1 glycoprotein C (gC)-producing cells adsorbed equine RBCs, and that the lysate of EHV-1 gC-expressing cells agglutinated equine RBCs. EHV-1 lacking gC did not show HA activity. HA activity was inhibited by monoclonal antibodies (MAbs) specific for gC, but not by antibodies directed against other glycoproteins. In addition, HA activity was not inhibited by the addition of heparin. These results indicate that EHV-1 gC can bind equine RBCs irrespective of heparin, in contrast to other herpesvirus gC proteins. Copyright © 2014 Elsevier B.V. All rights reserved.

Circulating endothelial progenitor cells in obese children and adolescents.

PubMed

Pires, António; Martins, Paula; Paiva, Artur; Pereira, Ana Margarida; Marques, Margarida; Castela, Eduardo; Sena, Cristina; Seiça, Raquel

2015-01-01

This study aimed to investigate the relationship between circulating endothelial progenitor cell count and endothelial activation in a pediatric population with obesity. Observational and transversal study, including 120 children and adolescents with primary obesity of both sexes, aged 6-17 years, who were recruited at this Cardiovascular Risk Clinic. The control group was made up of 41 children and adolescents with normal body mass index. The variables analyzed were: age, gender, body mass index, systolic and diastolic blood pressure, high-sensitivity C-reactive protein, lipid profile, leptin, adiponectin, homeostasis model assessment-insulin resistance, monocyte chemoattractant protein-1, E-selectin, asymmetric dimethylarginine and circulating progenitor endothelial cell count. Insulin resistance was correlated to asymmetric dimethylarginine (ρ=0.340; p=0.003), which was directly, but weakly correlated to E-selectin (ρ=0.252; p=0.046). High sensitivity C-reactive protein was not found to be correlated to markers of endothelial activation. Systolic blood pressure was directly correlated to body mass index (ρ=0.471; p<0.001) and the homeostasis model assessment-insulin resistance (ρ=0.230; p=0.012), and inversely correlated to adiponectin (ρ=-0.331; p<0.001) and high-density lipoprotein cholesterol (ρ=-0.319; p<0.001). Circulating endothelial progenitor cell count was directly, but weakly correlated, to body mass index (r=0.211; p=0.016), leptin (ρ=0.245; p=0.006), triglyceride levels (r=0.241; p=0.031), and E-selectin (ρ=0.297; p=0.004). Circulating endothelial progenitor cell count is elevated in obese children and adolescents with evidence of endothelial activation, suggesting that, during infancy, endothelial repairing mechanisms are present in the context of endothelial activation. Copyright © 2015 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Anode catalysts for direct ethanol fuel cells utilizing directly solar light illumination.

PubMed

Chu, Daobao; Wang, Shuxi; Zheng, Peng; Wang, Jian; Zha, Longwu; Hou, Yuanyuan; He, Jianguo; Xiao, Ying; Lin, Huashui; Tian, Zhaowu

2009-01-01

Shine a light: A PtNiRu/TiO(2) anode catalyst for direct ethanol fuel cells shows photocatalytic activity. The peak current density for ethanol oxidation under solar light illumination is 2-3 times greater than that in the absence of solar light. Ethanol is oxidized by light-generated holes, and the electrons are collected by the TiO(2) support to generate the oxidation current.Novel PtNiRu/TiO(2) anode catalysts for direct ethanol fuel cells (DEFCs) were prepared from PtNiRu nanoparticles (1:1:1 atomic ratios) and a nanoporous TiO(2) film by a sol-gel and electrodeposition method. The performances of the catalysts for ethanol oxidation were investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results indicate a remarkable enhancement of activity for ethanol oxidation under solar light illumination. Under solar light illumination, the generated oxidation peak current density is 24.6 mA cm(-2), which is about 2.5 times higher than that observed without solar light (9.9 mA cm(-2)). The high catalytic activity of the PtNiRu/TiO(2) complex catalyst for the electrooxidation of ethanol may be attributed to the modified metal/nanoporous TiO(2) film, and the enhanced electrooxidation of ethanol under solar light may be due to the photogeneration of holes in the modified nanoporous TiO(2) film.

Evaluation of the impact of chitosan/DNA nanoparticles on the differentiation of human naive CD4+ T cells

NASA Astrophysics Data System (ADS)

Liu, Lanxia; Bai, Yuanyuan; Zhu, Dunwan; Song, Liping; Wang, Hai; Dong, Xia; Zhang, Hailing; Leng, Xigang

2011-06-01

Chitosan (CS) is one of the most widely studied polymers in non-viral gene delivery since it is a cationic polysaccharide that forms nanoparticles with DNA and hence protects the DNA against digestion by DNase. However, the impact of CS/DNA nanoparticle on the immune system still remains poorly understood. Previous investigations did not found CS/DNA nanoparticles had any significant impact on the function of human and murine macrophages. To date, little is known about the interaction between CS/DNA nanoparticles and naive CD4+ T cells. This study was designed to investigate whether CS/DNA nanoparticles affect the initial differentiation direction of human naive CD4+ T cells. The indirect impact of CS/DNA nanoparticles on naive CD4+ T cell differentiation was investigated by incubating the nanoparticles with human macrophage THP-1 cells in one chamber of a transwell co-incubation system, with the enriched human naive CD4+ T cells being placed in the other chamber of the transwell. The nanoparticles were also co-incubated with the naive CD4+ T cells to explore their direct impact on naive CD4+ T cell differentiation by measuring the release of IL-4 and IFN-γ from the cells. It was demonstrated that CS/DNA nanoparticles induced slightly elevated production of IL-12 by THP-1 cells, possibly owing to the presence of CpG motifs in the plasmid. However, this macrophage stimulating activity was much less significant as compared with lipopolysaccharide and did not impact on the differentiation of the naive CD4+ T cells. It was also demonstrated that, when directly exposed to the naive CD4+ T cells, the nanoparticles induced neither the activation of the naive CD4+ T cells in the absence of recombinant cytokines (recombinant human IL-4 or IFN-γ) that induce naive CD4+ T cell polarization, nor any changes in the differentiation direction of naive CD4+ T cells in the presence of the corresponding cytokines.

Oncogenic Receptor Tyrosine Kinases Directly Phosphorylate Focal Adhesion Kinase (FAK) as a Resistance Mechanism to FAK-kinase Inhibitors

PubMed Central

Marlowe, Timothy A.; Lenzo, Felicia L.; Figel, Sheila A.; Grapes, Abigail T.; Cance, William G.

2016-01-01

Focal adhesion kinase (FAK) is a major drug target in cancer and current inhibitors targeted to the ATP-binding pocket of the kinase domain have entered clinical trials. However, preliminary results have shown limited single-agent efficacy in patients. Despite these unfavorable data, the molecular mechanisms which drive intrinsic and acquired resistance to FAK-kinase inhibitors are largely unknown. We have demonstrated that receptor tyrosine kinases (RTKs) can directly bypass FAK-kinase inhibition in cancer cells through phosphorylation of FAK’s critical tyrosine 397 (Y397). We also showed that HER2 forms a direct protein-protein interaction with the FAK-FERM-F1 lobe, promoting direct phosphorylation of Y397. Additionally, FAK-kinase inhibition induced two forms of compensatory RTK reprogramming: 1) the rapid phosphorylation and activation of RTK signaling pathways in RTKHigh cells and 2) the long-term acquisition of RTKs novel to the parental cell line in RTKLow cells. Finally, HER2+ cancer cells displayed resistance to FAK-kinase inhibition in 3D–growth assays using a HER2 isogenic system and HER2+ cancer cell lines. Our data indicate a novel drug resistance mechanism to FAK-kinase inhibitors whereby HER2 and other RTKs can rescue and maintain FAK activation (pY397) even in the presence of FAK-kinase inhibition. These data may have important ramifications for existing clinical trials of FAK inhibitors and suggest that individual tumor stratification by RTK expression would be important to predict patient response to FAK-kinase inhibitors. PMID:27638858

Generating synchrony from the asynchronous: compensation for cochlear traveling wave delays by the dendrites of individual brainstem neurons

PubMed Central

McGinley, Matthew J.; Liberman, M. Charles; Bal, Ramazan; Oertel, Donata

2012-01-01

Broadband transient sounds, such as clicks and consonants, activate a traveling wave in the cochlea. This wave evokes firing in auditory nerve fibers that are tuned to high frequencies several milliseconds earlier than in fibers tuned to low frequencies. Despite this substantial traveling wave delay, octopus cells in the brainstem receive broadband input and respond to clicks with submillisecond temporal precision. The dendrites of octopus cells lie perpendicular to the tonotopically organized array of auditory nerve fibers, placing the earliest arriving inputs most distally and the latest arriving closest to the soma. Here, we test the hypothesis that the topographic arrangement of synaptic inputs on dendrites of octopus cells allows octopus cells to compensate the traveling wave delay. We show that in mice the full cochlear traveling wave delay is 1.6 ms. Because the dendrites of each octopus cell spread across about one third of the tonotopic axis, a click evokes a soma directed sweep of synaptic input lasting 0.5 ms in individual octopus cells. Morphologically and biophysically realistic, computational models of octopus cells show that soma-directed sweeps with durations matching in vivo measurements result in the largest and sharpest somatic excitatory postsynaptic potentials (EPSPs). A low input resistance and activation of a low-voltage-activated potassium conductance that are characteristic of octopus cells are important determinants of sweep sensitivity. We conclude that octopus cells have dendritic morphologies and biophysics tailored to accomplish the precise encoding of broadband transient sounds. PMID:22764237

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling☆

PubMed Central

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-01-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2.) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. PMID:26225731

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling.

PubMed

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-12-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2(.)) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Repression of cell proliferation by miR319-regulated TCP4.

PubMed

Schommer, Carla; Debernardi, Juan M; Bresso, Edgardo G; Rodriguez, Ramiro E; Palatnik, Javier F

2014-10-01

Leaf development has been extensively studied on a genetic level. However, little is known about the interplay between the developmental regulators and the cell cycle machinery--a link that ultimately affects leaf form and size. miR319 is a conserved microRNA that regulates TCP transcription factors involved in multiple developmental pathways, including leaf development and senescence, organ curvature, and hormone biosynthesis and signaling. Here, we analyze the participation of TCP4 in the control of cell proliferation. A small increase in TCP4 activity has an immediate impact on leaf cell number, by significantly reducing cell proliferation. Plants with high TCP4 levels have a strong reduction in the expression of genes known to be active in G2-M phase of the cell cycle. Part of these effects is mediated by induction of miR396, which represses Growth-Regulating Factor (GRF) transcription factors. Detailed analysis revealed TCP4 to be a direct regulator of MIR396b. However, we found that TCP4 can control cell proliferation through additional pathways, and we identified a direct connection between TCP4 and ICK1/KRP1, a gene involved in the progression of the cell cycle. Our results show that TCP4 can activate different pathways that repress cell proliferation. © The Author 2014. Published by the Molecular Plant Shanghai Editorial Office in association with Oxford University Press on behalf of CSPB and IPPE, SIBS, CAS.

In vitro characterization of the immunotoxic potential of several perfluorinated compounds (PFCs)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corsini, Emanuela, E-mail: emanuela.corsini@unimi.it; Sangiovanni, Enrico; Avogadro, Anna

2012-01-15

We have previously shown that PFOA and PFOS directly suppress cytokine secretion in immune cells, with different mechanisms of action. In particular, we have demonstrated a role for PPAR-α in PFOA-induced immunotoxicity, and that PFOS has an inhibitory effect on LPS-induced I-κB degradation. These studies investigate the immunomodulatory effects of four other PFCs, namely PFBS, PFOSA, PFDA, and fluorotelomer using in vitro assays. The release of the pro-inflammatory cytokines IL-6 and TNF-α was evaluated in lipolysaccharide (LPS)-stimulated human peripheral blood leukocytes (hPBL) and in the human promyelocytic cell line THP-1, while the release of IL-10 and IFN-γ was evaluated inmore » phytohemagglutinin (PHA)-stimulated hPBL. All PFCs suppressed LPS-induced TNF-α production in hPBL and THP-1 cells, while IL-6 production was suppressed by PFOSA, PFOS, PFDA and fluorotelomer. PFBS, PFOSA, PFOS, PFDA and fluorotelomer inhibited PHA-induced IL-10 release, while IFN-γ secretion was affected by PFOSA, PFOS, PFDA and fluorotelomer. Leukocytes obtained from female donors appear to be more sensitive to the in vitro immunotoxic effects of PFCs when their responses are compared to the results obtained using leukocytes from male donors. Mechanistic investigations demonstrated that inhibition of TNF-α release in THP-1 cells occurred at the transcriptional level. All PFCs, including PFOA and PFOS, decreased LPS-induced NF-κB activation. With the exception of PFOA, none of the PFCs tested was able to activate PPARα driven transcription in transiently transfected THP-1 cells, excluding a role for PPARα in the immunomodulation observed. PFBS and PFDA prevented LPS-induced I-κB degradation. Overall, these studies suggest that PFCs affect NF-κB activation, which directly suppresses cytokine secretion by immune cells. Our results indicate that PFOA is the least active of the PFCs examined followed by PFBS, PFDA, PFOS, PFOSA and fluorotelomer. -- Research Highlights: ► PFCs showed direct immunomodulatory properties and inhibition of NF-κB driven transcription. ► PFOA is the least active PFCs followed by PFBS, PFDA, PFOS, PFOSA and fluorotelomer. ► Only PFOA activates PPARalpha.« less

Pasteurella multocida Toxin Manipulates T Cell Differentiation

PubMed Central

Hildebrand, Dagmar; Heeg, Klaus; Kubatzky, Katharina F.

2015-01-01

Pasteurella multocida causes various diseases in a broad range of wild and domestic animals. Toxigenic strains of the serotypes A and D produce an AB protein toxin named Pasteurella multocida toxin (PMT). PMT constitutively activates the heterotrimeric G protein subunits Gαq, Gα13, and Gαi through deamidation of a glutamine residue, which results in cytoskeletal rearrangements as well as increased proliferation and survival of the host cell. In human monocytes, PMT alters the lipopolysaccharide (LPS)-induced activation toward a phenotype that suppresses T cell activation. Here we describe that the toxin also modulates CD4-positive T helper (Th) cells directly. PMT amplifies the expansion of Th cells through enhanced cell cycle progression and suppression of apoptosis and manipulates the differentiation of Th subclasses through activation of Signal Transducers and Activators of Transcription (STAT) family members and induction of subtype-specific master transcription factors. A large population of toxin-treated T cells is double-positive for Foxp3 and RORγt, the transcription factors expressed by Treg and Th17 cells, respectively. This suggests that these cells could have the potential to turn into Th17 cells or suppressive Treg cells. However, in terms of function, the PMT-differentiated cells behave as inflammatory Th17 cells that produce IL-17 and trigger T cell proliferation. PMID:26635744

Epidermal keratinocyte polarity and motility require Ca2+ influx through TRPV1

PubMed Central

Graham, David M.; Huang, Ling; Robinson, Kenneth R.; Messerli, Mark A.

2013-01-01

Summary Ca2+ has long been known to play an important role in cellular polarity and guidance. We studied the role of Ca2+ signaling during random and directed cell migration to better understand whether Ca2+ directs cell motility from the leading edge and which ion channels are involved in this function by using primary zebrafish keratinocytes. Rapid line-scan and time-lapse imaging of intracellular Ca2+ (Ca2+i) during migration and automated image alignment enabled us to characterize and map the spatiotemporal changes in Ca2+i. We show that asymmetric distributions of lamellipodial Ca2+ sparks are encoded in frequency, not amplitude, and that they correlate with cellular rotation during migration. Directed migration during galvanotaxis increases the frequency of Ca2+ sparks over the entire lamellipod; however, these events do not give rise to asymmetric Ca2+i signals that correlate with turning. We demonstrate that Ca2+-permeable channels within these cells are mechanically activated and include several transient receptor potential family members, including TRPV1. Last, we demonstrate that cell motility and Ca2+i activity are affected by pharmacological agents that target TRPV1, indicating a novel role for this channel during cell migration. PMID:23943873

1,5-Disubstituted benzimidazoles that direct cardiomyocyte differentiation from mouse embryonic stem cells.

PubMed

Okolotowicz, Karl J; Bushway, Paul; Lanier, Marion; Gilley, Cynthia; Mercola, Mark; Cashman, John R

2015-09-01

Cardiomyopathy is the leading cause of death worldwide. Despite progress in medical treatments, heart transplantation is one of the only current options for those with infarcted heart muscle. Stem cell differentiation technology may afford cell-based therapeutics that may lead to the generation of new, healthy heart muscle cells from undifferentiated stem cells. Our approach is to use small molecules to stimulate stem cell differentiation. Herein, we describe a novel class of 1,5-disubstituted benzimidazoles that induce differentiation of stem cells into cardiac cells. We report on the evaluation in vitro for cardiomyocyte differentiation and describe structure-activity relationship results that led to molecules with drug-like properties. The results of this study show the promise of small molecules to direct stem cell lineage commitment, to probe signaling pathways and to develop compounds for the stimulation of stem cells to repair damaged heart tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

1,5-Disubstituted benzimidazoles that direct cardiomyocyte differentiation from mouse embryonic stem cells

PubMed Central

Okolotowicz, Karl J.; Bushway, Paul; Lanier, Marion; Gilley, Cynthia; Cynthia, Mark; Cashman, John R.

2016-01-01

Cardiomyopathy is the leading cause of death worldwide. Despite progress in medical treatments, heart transplantation is one of the only current options for those with infarcted heart muscle. Stem cell differentiation technology may afford cell-based therapeutics that may lead to the generation of new, healthy heart muscle cells from undifferentiated stem cells. Our approach is to use small molecules to stimulate stem cell differentiation. Herein, we describe a novel class of 1,5-disubstituted benzimidazoles that induce differentiation of stem cells into cardiac cells. We report on the evaluation in vitro for cardiomyocyte differentiation and describe structure–activity relationship results that led to molecules with drug-like properties. The results of this study show the promise of small molecules to direct stem cell lineage commitment, to probe signaling pathways and to develop compounds for the stimulation of stem cells to repair damaged heart tissue. PMID:26278027

The Mast Cell, Contact, and Coagulation System Connection in Anaphylaxis

PubMed Central

Guilarte, Mar; Sala-Cunill, Anna; Luengo, Olga; Labrador-Horrillo, Moisés; Cardona, Victoria

2017-01-01

Anaphylaxis is the most severe form of allergic reaction, resulting from the effect of mediators and chemotactic substances released by activated cells. Mast cells and basophils are considered key players in IgE-mediated human anaphylaxis. Beyond IgE-mediated activation of mast cells/basophils, further mechanisms are involved in the occurrence of anaphylaxis. New insights into the potential relevance of pathways other than mast cell and basophil degranulation have been unraveled, such as the activation of the contact and the coagulation systems. Mast cell heparin released upon activation provides negatively charged surfaces for factor XII (FXII) binding and auto-activation. Activated FXII, the initiating serine protease in both the contact and the intrinsic coagulation system, activates factor XI and prekallikrein, respectively. FXII-mediated bradykinin (BK) formation has been proven in the human plasma of anaphylactic patients as well as in experimental models of anaphylaxis. Moreover, the severity of anaphylaxis is correlated with the increase in plasma heparin, BK formation and the intensity of contact system activation. FXII also activates plasminogen in the fibrinolysis system. Mast cell tryptase has been shown to participate in fibrinolysis through plasmin activation and by facilitating the degradation of fibrinogen. Some usual clinical manifestations in anaphylaxis, such as angioedema or hypotension, or other less common, such as metrorrhagia, may be explained by the direct effect of the activation of the coagulation and contact system driven by mast cell mediators. PMID:28798744

An in vitro comparative study of the antioxidant activity and SIRT1 modulation of natural compounds.

PubMed

Fusi, Jonathan; Bianchi, Sara; Daniele, Simona; Pellegrini, Silvia; Martini, Claudia; Galetta, Fabio; Giovannini, Luca; Franzoni, Ferdinando

2018-05-01

Oxidative stress arises from an imbalance between the production of free radicals and antioxidant defences. Several studies have suggested that dietary antioxidants (such as polyphenols and berberine) may counteract oxidative stress through the involvement of the Sirtuin 1/Adenosine Monophosphate-Activated Protein Kinase (SIRT1/AMPK) pathway. The aim of this study was to evaluate the direct and specific antioxidant activity of some natural compounds, as well as their ability to modulate the expression of SIRT1 and the activation of AMPK. Quercetin, tyrosol, ferulic acid, catechin, berberine and curcumin were evaluated for their specific and direct antioxidant activity with TOSC assay. Their ability to modulate SIRT1 and AMPK was assessed by immunoblotting assay, while their cytotoxicity by CellTiter-Blue Cell Viability Assay. No statistically significant decrease (p > 0.05) in the number of viable cells was found upon challenging with the natural compounds. Quercetin exhibited the highest antioxidant activity against peroxyl radical and peroxinitrate derivates, while curcumin showed the best anti-hydroxyl activity with respect to the other compounds and, most importantly, respect to the reference antioxidants. Finally, all the tested compounds significantly increased the SIRT1 expression and the activation of AMPK. Our results clearly disclose the specific antioxidant activity of these natural compounds and their ability to increase SIRT1 expression and AMPK activation. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Differentiation and Monitoring of Cells Using a Biochip for Regenerative Medicine

NASA Astrophysics Data System (ADS)

Uchida, Tomoyuki; Arai, Fumihito; Suzuki, Osamu; Ichikawa, Akihiko; Fukuda, Toshio; Katagiri, Takenobu; Kamijo, Ryutaro; Nakamura, Masanori; Numata, Mamoru; Watanabe, Naruaki

A novel biochip is developed for culturing stem cells. Biochip is made of Polymer (PDMS), and cells can be loaded by gradient strains in one chip. They grow well on a hydrophilic membrane and differentiation is promoted by cyclic strains. In this paper, we propose the method for culturing and monitoring of stem cells such as bone marrow stromal cells (ST2 cells) and myoblasts (C2C12 cells), and the results of culture. First we analyzed strains on a membrane when an air hole is decompressed, and clarified their range. From experiment, bone marrow stromal cells grew well in a narrow range, and we quantified their ALP activity as a measure of differentiation. As myoblasts, the direction of their differentiation was perpendicular to a groove, that is, the same direction of uniaxial strains.

SGR9, a RING type E3 ligase, modulates amyloplast dynamics important for gravity sensing.

NASA Astrophysics Data System (ADS)

Morita, Miyo T.; Nakamura, Moritaka; Tasaka, Masao

Gravitropism is triggered when the directional change of gravity is sensed in the specific cells, called statocytes. In higher plants, statocytes contain sinking heavier amyloplasts which are particular plastids accumulating starch granules. The displacement of amyloplasts within the statocytes is thought to be the initial event of gravity perception. We have demonstrated that endodermal cells are most likely to be the statocytes in Arabidop-sis shoots. Live cell imaging of the endodermal cell of stem has shown that most amyloplasts are sediment to the direction of gravity but they are not static. Several amyloplasts move dynamically in an actin filament (F-actin) dependent manner. In the presence of actin poly-merization inhibitor, all amyloplasts become static and sediment to the direction of gravity. In addition, stems treated with the inhibitor can exhibit gravitropism. These results suggest that F-actin-dependent dynamic movement of amyloplasts is not essential for gravity sensing. sgr (shoot gravitropism) 9 mutant exhibits greatly reduced shoot gravitropism. In endodermal cells of sgr9, dynamic amyloplast movement was predominantly observed and amyloplasts did not sediment to the direction of gravity. Interestingly, inhibition of actin polymerization re-stored both gravitropism and amyloplast sedimentation in sgr9. The SGR9 encodes a novel RING finger protein, which is localized to amyloplasts in endodermal cells. SGR9 showed ubiq-uitin E3 ligase activity in vitro. Together with live cell imaging of amyloplasts and F-actin, our data suggest that SGR9 modulate interaction between amyloplasts and F-actin on amylo-plasts. SGR9 positively act on amyloplasts sedimentation, probably by releasing amyloplasts from F-actin. SGR9 that is localized to amyloplast, possibly degrades unknown substrates by its E3 ligase activity, and this might promote release of amyloplasts from F-actin.